阅读说明：本技术 流体特性传感器 (Fluid property sensor ) 是由 A·D·斯图德 D·N·奥尔森 M·W·坎比 C-H·陈 J·M·加德纳 S·A·林恩 于 2019-04-05 设计创作，主要内容包括：一种流体特性传感器可以包括：集成电路(IC),该集成电路包括流体液位传感器和/或压力传感器；以及外部接口,该外部接口电耦接到EC的近端,其中,压力传感器可以被配置成测量流体特性传感器的挠曲。(A fluid property sensor may include: an Integrated Circuit (IC) including a fluid level sensor and/or a pressure sensor; and an external interface electrically coupled to a proximal end of the EC, wherein the pressure sensor may be configured to measure a deflection of the fluid property sensor.)

1. A fluid property sensor comprising:

an Integrated Circuit (IC) comprising

A fluid level sensor, and

a pressure sensor; and

an external interface electrically coupled to a proximal end of the EC, wherein the pressure sensor is configured to measure a deflection of the fluid property sensor.

2. The fluid property sensor of claim 1, the fluid level sensor comprising a plurality of point sensors distributed along a length of the IC to sense a fluid level.

3. The fluid property sensor of claim 1 or 2, wherein the IC and the external interface are packaged together to form the fluid property sensor.

4. The fluid property sensor of any preceding claim, wherein the IC comprises an Elongate Circuit (EC) having an aspect ratio of length to width of at least 20: 1.

5. The fluid property sensor of any preceding claim, wherein the IC comprises a proximal Elongate Circuit (EC) and a distal EC electrically coupled to the proximal EC, wherein the proximal EC and the distal EC each comprise a portion of the pressure sensor.

6. A fluid property sensor according to any preceding claim, wherein the IC and the external interface are packaged together to form the fluid property sensor.

7. The fluid property sensor of any preceding claim, wherein the fluid property sensor has a datum for locating and attaching the sensor to a wall of a fluid container to allow the fluid property sensor to measure the deflection of the wall.

8. A fluid property sensor according to any preceding claim wherein the pressure sensors comprise at least five stress sensors.

9. The fluid property sensor of any preceding claim, wherein the pressure sensor comprises a plurality of stress sensors formed along the length of the IC and formed as one of a doped diffused Elongate Circuit (EC) and a piezoresistive element bonded to the EC.

10. A fluid property sensor according to any preceding claim wherein the IC comprises a die crack sensor.

11. A fluid container comprising a fluid property sensor according to any preceding claim and comprising a reservoir with fluid, at least part of the fluid property sensor extending along the reservoir.

12. The fluid container of claim 11, further comprising a fluid interface for supplying fluid from the reservoir to a printer along a generally horizontal axis, the fluid interface being closer to a gravitational bottom of the reservoir than to a middle of a height of the reservoir, and an air interface for the printer to provide air pressure to the reservoir through the air interface to pressurize fluid in the reservoir, the air interface being disposed above the fluid interface.

13. The fluid container of any preceding claim, further comprising a pressure regulator, wherein the air interface is connected to the pressure regulator.

14. A fluid container, comprising:

a reservoir for containing a fluid; and

a fluid property sensor having:

a plurality of Integrated Circuits (ICs) sharing a common interface bus,

a fluid level sensor exposed to the fluid, an

A pressure sensor; and

an external interface exposed outside of the reservoir and electrically coupled to the interface bus, wherein the fluid property sensor is attached to a sidewall of the fluid container and the pressure sensor is to report an amount of deflection of the sidewall.

15. The fluid container of claim 14, wherein the plurality of ICs includes a proximal Elongated Circuit (EC) having a set of various types of sensors, a distal EC having a high density of fluid property sensors, and a central EC between the proximal EC and the distal EC, the central EC having a minimal set of fluid property sensors and a passage of the common interface bus.

16. The fluid container of claim 14 or 15, wherein at least one of the plurality of ICs and the interface bus are packaged together to form the fluid property sensor.

17. The fluid container of any one of claims 14-16, wherein the pressure sensor comprises a plurality of stress sensors distributed along a length of the IC to monitor stress within a package of the fluid property sensor.

18. The fluid container of any one of claims 14-17, wherein the pressure sensor is configured to detect an over-inflation cycle performed within the fluid container.

19. The fluid container of any one of claims 14-18, wherein the pressure sensor is to detect an over-inflation cycle performed on an adjacent fluid container.

20. The fluid container of any one of claims 14-19, wherein the pressure sensor is to detect at least one of inertial movement of the fluid container and fluid movement within the fluid container.

21. The fluid container according to any one of claims 14-20, wherein the pressure sensor is used to monitor the fluid container for leaks or maintenance operations.

22. The fluid container of any one of claims 14-21, wherein the fluid level sensor comprises a plurality of point sensors distributed along a length of the IC to sense fluid level.

23. The fluid container of any one of claims 14-21, wherein the IC comprises an Elongate Circuit (EC) having a length to width aspect ratio of at least 20: 1.

24. The fluid container of any one of claims 14-23, wherein the sensing portion comprises a plurality of thermal impedance sensors, a plurality of electrical impedance sensors, a stress sensor, and a die crack sensor.

Background

Accurate fluid level sensing is often complex and expensive. Accurate fluid levels may prevent waste of fluid, as well as premature replacement of fluid tanks and fluid-based devices such as inkjet printheads. Furthermore, accurate fluid levels prevent low quality fluid-based products that may result from insufficient supply levels, thereby also reducing waste of finished products.

Drawings

The disclosure may be better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other. Instead, emphasis has instead been placed upon clearly illustrating the claimed subject matter. Moreover, in the several views, like reference numerals designate corresponding similar parts, but may not be identical. For the sake of brevity, some of the reference numerals described in the previous figures may not be repeated in subsequent figures.

FIG. 1A is a block diagram of an exemplary fluid-based system;

FIG. 1B is an alternative block diagram of the example fluid-based system of FIG. 1A;

FIG. 2A is a diagram of an exemplary sidewall with an exemplary fluid property sensor attached;

FIG. 2B is a diagram of a fluid container having the example sidewall of FIG. 2A and an example fluid property sensor;

FIG. 3 is an illustration of an exemplary fluid container of another shape;

FIG. 4 is an illustration of another shape of a fluid actuation assembly;

fig. 5A-5D are diagrams of different exemplary embodiments of an elongated Electrical Circuit (EC) including a fluid property sensor;

fig. 6 is another example of an Elongated Circuit (EC) housing bond pads;

FIG. 7 is an example of an opening in a protective layer to expose a sensor on an EC die;

FIG. 8 is a schematic diagram of an exemplary circuit for allowing point sensors to be individually selected for pulse measurement or commonly read together for parallel measurement;

FIG. 9A is an example of a fluid level sensor based on temperature impedance;

FIG. 9B is an example of an electrical impedance-based fluid level sensor;

FIG. 9C is another example of a fluid level sensor based on temperature impedance;

FIG. 10 is an exemplary cross section of an EC of a possible point sensor;

FIG. 11 is an exemplary cross section of a piezoresistive metal temperature sensor surrounded by polysilicon heater resistors;

FIG. 12 is an exemplary pressure sensor implemented along the length of an EC die;

13A-13H are exemplary methods of making a packaged fluid property sensor;

14A-14D are another exemplary method of making a packaged fluid property sensor;

15A-15D are illustrations of another exemplary process of fabricating a packaged fluid property sensor;

FIG. 16 is a flow diagram of the example fluid sensing routine of FIG. 1; and

FIG. 17 is an exemplary fluid cartridge having a fluid property sensor with a fluid level sensor and a pressure sensor.

Detailed Description

The present disclosure relates to a novel fluid property sensor. The fluid property to be sensed by such a sensor may comprise at least one of a pressure and a fluid level, but other properties may also be sensed in addition to or instead of said pressure or fluid level. Some examples of such sensors incorporate at least one Integrated Circuit (IC) with one or more sensors mounted on a substrate and/or packaged to protect any bond wires and circuitry, for example. Other examples of such sensors combine narrow elongated (also called "slivers") circuits (ECs) with multiple sensors mounted on a substrate and packaged to protect any bond wires and EC circuits, for example better than chip-on-board technology. An IC may be a semiconductor integrated circuit, a hybrid circuit, or other fabricated circuit having a plurality of electrical and electronic components fabricated into an integrated package. By placing a high density of exposed sets of multiple point sensors and pressure sensors along the length of the elongated circuit, the fluid property sensor can provide significantly increased resolution and accuracy. Multiple ICs may be arranged in a daisy chain fashion (interleaving is one example) to create a long fluid property sensor that covers the depth of fluid in the container. Multiple ICs may share a common interface bus and may include test circuitry, safety, bias, amplification and latch circuits.

When the fluid cartridge has a small amount of fluid, the sets of multiple sensors may be distributed non-linearly to allow for increased resolution. Further, a group having multiple sensors may be configured to be read in parallel for some applications to increase surface contact with a fluid, or to be gated separately in other applications. Not only can the level of the fluid be sensed, but complex impedance measurements can be made. Additional sensors may be configured or added for property sensing of the fluid (e.g., ink type, pH), temperature sensing of the fluid, strain sensing of the sensing portion, pressure sensing within the fluid reservoir, or verification of fluid container servicing. The multiple ICs may be of the same type or different types depending on the desired characteristics of the fluid property sensor. One of the multiple ICs may contain a container driver circuit (also known as a keepout chip) with memory, or the container driver circuit may be located on a separate IC. The length to width aspect ratio of the driver circuit may be 10:1 or less, for example 5:1 or less, for example coupled to the common interface bus as a non-elongated circuit. The following are several different examples and descriptions of various techniques for making and using the claimed subject matter.

In the present disclosure, the driver circuit may include decode logic or decode functionality as part of the integrated circuit. The decode logic may include enable circuitry, such as power, ground, clock, and/or data lines, that enables the at least one sensor in response to other logic in the IC receiving an enable instruction. Based on signals received from the printer over the external interface and/or common interface bus, the decoding logic may facilitate addressing each sensor, or each point sensor of the sensor array. The decode logic may comprise a rewritable memory array, such as a shift register array connected to an interface bus and/or an external interface. The decode logic may include multiplexing circuitry for driving the respective sensors and/or sensor dots based on the values written to the rewritable memory array. The driver circuit may comprise circuitry for converting input and/or output signals between the external interface and the at least one connected sensor. The driver circuit may comprise circuitry for converting signals between analog and digital and/or between digital and analog, and/or from analog to analog and/or digital to digital. The driver circuit may comprise an offset function for offsetting the input and/or output signals between the at least one sensor and the external interface. The driver circuit may comprise an amplifier function for amplifying input and/or output signals between the at least one sensor and the external interface. The driver circuit may include other calibration functions in addition to offset and/or amplifier functions. The input and output signals may comprise analog signals and/or digital values. The driver circuit may be adapted to drive a plurality of sensors having different sensing functions, and/or individual point sensors of each of the plurality of sensors. In some examples, the driver circuit may comprise an Application Specific Integrated Circuit (ASIC).

Fig. 1A is a block diagram of an exemplary fluid-based system 10, such as an inkjet printer. System 10 may include a carriage 12 having a Fluid Actuation Assembly (FAA)20 with a printhead 30. The FAA20 may include or be connected to one or more fluid containers 40. In this example, there are four fluid containers 40 having cyan (C), yellow (Y), magenta (M), and black (K) inks. Other colors and other printing liquids may be used, including any 2D or 3D printing agent. The ink may be based on dyes or pigments, or a combination of dyes or pigments. The FAA20 may be located on a stationary carriage 12, for example with a page wide array system 10, or the FAA may be located on a movable carriage 12, and the printhead 30 scanned across the media 14 in one or more directions. The fluid containers 40 may be in close proximity to one another such that they may expand and contact adjacent fluid containers 40 during an hyperinflation event initiated by pump 19 in service station 18.

Media 14 is moved using a print media transport 16, typically from a media tray to an output tray. Print media transport 16 is controlled by controller 100 to synchronize movement of media 14 with any movement and/or actuation of printhead 30 to accurately place fluid on media 14. The controller 100 may have one or more processors with one or more cores. The controller 100 is coupled to a tangible and non-transitory Computer Readable Medium (CRM)120 that stores instructions readable and executable by the controller 100. The CRM 120 may include several different routines for operating and controlling the system 10. One such routine may be a fluid sensing routine 102 (see fig. 16) for monitoring and measuring a fluid level and/or a fluid characteristic in one of the FAA20 and the fluid container 40. Another such routine may be a stress measurement routine for monitoring the operation of pump 19 during, for example, one or more stresses within fluid container 40 during a hyperinflation event, interactions between fluid containers 40, or maintenance operations.

Computer-readable medium 120 allows for storage of one or more sets of data structures and instructions (e.g., software, firmware, logic) embodying or utilized by any one or more of the methodologies or functions described herein. The instructions may also reside, completely or at least partially, within static memory, main memory, and/or within a processor of the controller 100 during execution thereof by the system 10. The main memory, the driver circuit 204 memory, and the processor memory also constitute the computer-readable medium 120. The term "computer-readable medium" 120 may include a single medium or multiple media (centralized or distributed) that store one or more instructions or data structures. Computer readable media 120 may be implemented to include, but is not limited to, solid-state, optical, and magnetic media, whether volatile or non-volatile. Examples of such include semiconductor memory devices (e.g., erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory devices), magnetic disks such as internal hard drives and removable disks, magneto-optical disks, and CD-ROMs (compact disk read-only memory) and DVDs (digital versatile disk) disks.

The system 10 may include a service station 18 for performing maintenance and air pressure adjustments to the printhead 30, such as for performing an over-inflation event to transfer fluid from the fluid container 40 to the FAA20, and for maintaining back pressure during normal operation within each of the fluid cartridge 40 and the FAA 20. Such maintenance may include cleaning, priming, setting back pressure levels, and reading fluid levels. The service station 18 may include a pump 19 for providing air pressure to move fluid from the fluid container 40 to the printhead 30, and for setting a back pressure within the FAA20 to prevent accidental leakage of fluid from the printhead 30.

Fig. 1B is an alternative block diagram of the system 10 illustrating the operation of the fluid container 40 and the FAA 20. Fluid container 40 includes a fluid reservoir 44 having a fluid level 43 that is coupled to fluid chamber 22 through a fluid line to FAA fluid interface 25 via a container fluid interface 45. Fluid chamber 22 is also fluidly coupled to printhead 30. To move fluid from the fluid container 40 to the FAA20 having a separate fluid level 43, the pressure regulator bag 42 may be inflated within the fluid reservoir 44 through an air interface 47 coupled to the pump 19. The container 40 may include other types of pressure regulators other than a bag connected to the air interface 47, for example, any collapsible/expandable air chamber having at least one resilient, flexible wall.

In use, the fluid interface 45 may supply fluid from the reservoir 44 to the FAA20 along a generally horizontal axis. In a use orientation in which the fluid flows substantially horizontally and the height of the reservoir 44 extends substantially vertically, the fluid interface 45 is disposed closer to the gravitational bottom of the reservoir 44 than to the middle of the height of the interior volume to facilitate emptying of the reservoir 44, which is also in a nearly depleted state. In this orientation, the air interface 47 may be disposed above the fluid interface 45, e.g., near or above the middle of the height of the reservoir 44.

To monitor and measure the fluid level 43 in the fluid container 40 or the FAA20 or both, a fluid property sensor 46 may be located within the fluid reservoir 44. Controller 100 may be electrically coupled to electrical interface 48 on fluid property sensor 46, which may be an external electrical interface. The fluid property sensor 46 may be oriented substantially perpendicular to the fluid level 43, or it may be angled with respect to the fluid level 43. In various examples, the sensor 46 may extend from near the gravitational bottom of the fluid reservoir 44 to: (i) below the middle of the height of the fluid reservoir 44, (ii) near the middle of the height of the reservoir 44, or (iii) along the entire height of the reservoir 44. The electrical interface 48 of the container 40 may be positioned near the full fluid level 43 as shown for the fluid container 40, such as above the air interface 47 and/or near the top of the container 40. Fluid property sensor 46 may have one fluid level sensor or an array of substantially evenly distributed fluid level sensors as illustrated for fluid container 40. In another example, a similar fluid property sensor 46 is used for the fluid chamber 22 of the FAA20, where the level sensor may be provided non-uniformly and with a higher density closer to the bottom of gravity as shown for the fluid chamber 22. In addition to the fluid level sensor, the fluid property sensor 46 may include additional sensors, such as a stress sensor, a temperature sensor, a crack sensor, to name a few. The example fluid chamber 22 with fluid property sensor 46 may similarly include an electrical interface 48.

Fig. 2A is an illustration of an exemplary sidewall 41 of the exemplary fluid container 40 shown in fig. 2B to demonstrate placement of the fluid property 46. For example, the or each side wall 41 of the container 40 may be relatively rigid to contain free ink and not collapse when fluid is removed in normal use, except for a relatively small amount of deflection due to a pressurization event, as will be explained later. The fluid property sensor 46 has an IC, in this example an elongated Electrical Circuit (EC)49, with a plurality of sensors encased within an encapsulating can 50, for example by being overmolded with or adhered to a compound and/or metal or directly to the wall 41. Although examples of elongated circuits are described throughout this disclosure, it will be clear that other types of integrated circuits having different form factors (e.g., other length to width ratios) may also be used for the same purpose.

The encapsulating envelope 50 may have an opening for heat staking the fluid property sensor 46 to the sidewall 41 or otherwise attaching to the sidewall 41. In one example, the attachment of fluid characteristic sensor 46 to sidewall 41 is sufficient to allow fluid characteristic sensor 46 to conform to the flexing of sidewall 41. As shown in fig. 2A, the sidewall 41 to which the fluid property sensor 46 is attached also forms an outer wall of the fluid container 40. The opposing housing portion includes opposing sidewalls 41, the housing having an air interface 47, an electrical interface 48, and a container fluid interface 45 (fig. 2B). As illustrated, fluid container 40 in fig. 2B may be slightly tilted at an angle θ, for example, about 3 degrees to about 30 degrees, to allow fluid within fluid container 40 to flow to the bottom of container fluid interface 45 and fluid property sensor 46 to minimize wasted fluid when fluid container 40 is near empty. In the present disclosure, an angle of about 0 to 30 degrees relative to horizontal may be considered substantially horizontal, as distinguished from, for example, a generally vertically mounted container (see, e.g., fig. 3 and 4). The slight angle of inclination of the fluid container 40 may also facilitate the fluid property sensor 46 remaining in contact with the fluid to provide accurate fluid levels.

The package can 50 allows for improved silicon die separation rates, eliminates silicon slotting costs, eliminates fan-out daughter boards (chiclet), simultaneously forms fluid contact slots for multiple slivers, and avoids many process integration issues. Overmolding or adhesive techniques may be used to fully or partially encapsulate the fluid property sensor 46 to protect the Electrical Circuit Assembly (ECA)159 and bond wire interconnections while exposing the plurality of level sensors only to the fluid within the container. In some examples, the fluid may be irritating, e.g., having low and high pH or reactive components. By employing an integrated package, ECA 159, bond wires, any driver circuitry 204, memory, ASICs or other ICs, and EC 49 may be embedded in the packaging material (except for the sensor area) to improve reliability. ECA 159 comprises thin strips of conductive material (e.g., copper or aluminum) that have been etched, laid, laser sintered, or otherwise secured directly from a layer to a flat insulating sheet (e.g., an epoxy, plastic, ceramic, or Mylar (Mylar) substrate), and to which integrated circuits and other components are attached. In some examples, the traces may be buried within the substrate of ECA 159. The bonding wires may be encased in epoxy or glue, as just a few examples.

Fig. 3 is a representation 60 of another shape of an exemplary fluid container 40, in which fluid container 40 fluid property sensor 46 is not attached to a sidewall of fluid container 40 but is suspended within the fluid. The EC 49 is surrounded by an encapsulating envelope 50 except for an opening for the sensor portion with the sensor array. The full fluid level 43 extends from the top of the EC 49 to the gravitational bottom of the fluid container 40 where the electrical interface 48 and the container fluid interface 45 are present. In this example, the fluid container 40 has a non-uniform cross-section because the container wall tapers to the fluid interface 45. Fluid property sensor 46 may have a non-linear or non-uniform distribution of point sensors to adapt the fluid level readings to the changing cross-sectional shape of the fluid container. That is, fluid property sensor 46 may have a less dense set of point sensors near full fluid level 43 and a denser set of point sensors where fluid container 40 tapers to fluid interface 45. The point sensor may be a fluid level sensor or a pressure sensor. Different point sensor types may be provided, such as a fluid level sensor and a pressure sensor.

Fig. 4 is a diagram 70 of FAA20 with fluid chamber 22 and printhead 30. In one example, the top portion 72 of the FAA20 has an FFA fluid interface 25 that can be coupled to the container fluid interface 45 of fig. 3 to deliver fluid to the fluid chamber 22. In other examples, the illustration 70 may represent a replaceable fluid container having a printhead. The fluid property sensor 46 extends from a proximal end at the gravitational bottom of the FAA20 into the fluid to a distal end at the full fluid level 43. As with fluid container 40 of fig. 3, the electrical interface is located near the bottom of gravity, and near one or more printhead dies 30. In one example, FAA fluidic interface 45 may be used to refill fluid chamber 22 when fluid is withdrawn according to use, to adjust back pressure, and to prevent damage to printhead die 30 from being starved. In one example, it may be desirable to increase the density of dot sensors near the gravitational bottom of FAA20 to detect when printhead die 30 may be starved of fluid, especially during long print jobs.

Thus, the fluid container 40 or FAA20 (collectively referred to as fluid container 40) may comprise a package containing the fluid chamber 22 containing the fluid or the fluid reservoir 44. Fluid property sensor 46 may include a sensing portion that extends into fluid chamber 22 or fluid reservoir 44, and may include multiple Integrated Circuits (ICs) that share a common interface bus 83. At least one IC, in this example an Elongated Circuit (EC)49, may have multiple exposed sets of multiple sensors distributed along the length of the EC 49. The interface portion may be exposed outside the package and include an electrical interface 48 electrically coupled to the proximal end of the sensing portion. Multiple ICs are packaged together with electrical interface 48 to form fluid property sensor 46. The groups of multiple exposed groups with multiple sensors may be non-linearly or non-uniformly distributed along the length of the EC 49 and have the following layout: when used, the density increases along the portion of the EC 49 near the gravitational bottom of the fluid container 40 or FAA 20. The density of the point sensors may be between 20 and 100 per inch (1 inch is about 2.54 cm), and in some cases at least 50 per inch. In other examples, the density of point sensors may be more than 40 sensors per centimeter in higher density regions and less than 10 sensors per centimeter in lower density regions. The sensing portion may include at least one additional sensor to enable one of sensing of a property of the fluid, sensing of a temperature of the fluid, sensing of a strain of the sensing portion, and sensing of a pressure within the chamber. The EC 49 may have a thickness of between about 10 μm to about 200 μm, a width of between 80 μm to 600 μm, and a length of between about 0.5 inches to about 3 inches, for example any length above about 1 cm. The aspect ratio of length to width of the EC 49 die may be at least 20:1 or 50:1, meaning at least 20 or at least 50 times longer than the width, respectively. In some examples, the length to width ratio may exceed 100 or two orders of magnitude in length versus width. In contrast, driver circuit 204 may be an IC with a length to width aspect ratio of less than 10: 1. Thus, the fluid property sensor may include an EC 49 having an aspect ratio five or even ten times greater than the aspect ratio of the driver circuit 204. In one example, the sensor and driver circuitry are provided on the same IC or EC, whereby the sensor (and/or sensor spot array) may extend along a longer portion of the length of the IC or EC than the driver circuitry.

Fig. 5A-5D are illustrations of different exemplary embodiments of fluid property sensor 46. For ease of discussion, top and bottom direction descriptors are used to help identify components. The top and bottom reference numbers relate to how the fluid property sensor 46 is used in the fluid container relative to gravity. The terms top and bottom are not meant to be limiting. Moreover, the terms proximal, distal and central are also used to describe the components with respect to their position relative to the electrical interface 48, and thus are independent of gravitational effects.

Fig. 5A is an example of a fluid property sensor 46 having a single EC 49 electrically coupled to an electrical interface 48 on top (with respect to gravity) of fluid property sensor 46 by a set of bond wires and encapsulated with an epoxy or glue coating 81 to protect bond wires 82 when encapsulation of enclosure 50 occurs. In this example, the electrical interface 48 is shown with five contacts (VCC, GND, data signals, clock signals, and sense signals) forming a common interface bus 83, but may have more or fewer contacts depending on the application. In other examples, the external interface includes at least three (e.g., GND, data, clock or VCC, GND, data or VCC, GND, sense) or at least four (e.g., VCC, GND, data, clock) bond pads. The sensing signal may be used to provide a digital or analog signal, and may also be used for testing, security, or other purposes. The data signals and clock signals are typically digital signals, where the data lines are bidirectional lines, and the clock signal is typically an input into the EC 49 or other IC (e.g., driver circuit 204).

Encapsulation enclosure 50 in this example includes a first encapsulation section 51 and a second encapsulation section 52 on opposite ends of ECA 159 of fluid property sensor 46. The first package section 51 protects the encapsulated wire bonds 82. The second encapsulation section 52 of the encapsulation enclosure 50 provides support from twisting and provides support for mounting. The two separate encapsulation sections 51, 52 of encapsulation enclosure 50 allow for improved thermal expansion differences between EC 49, ECA 159 and encapsulation enclosure 50. As shown, the fluid level and/or pressure point sensors 80 may be distributed along at least a portion of the length of the EC 49.

FIG. 5B is an example of a fluid property sensor 46 having two different types of ECs 49 that are interleaved and daisy-chained on ECA 159 to form a longer fluid property sensor 46. Top EC 49 is electrically coupled to electrical interface 48 proximal to the top of fluid property sensor 46. The top EC 49 in this example has a plurality of sensors, such as a fluid level sensor 80, a pressure (point) sensor 84, and a temperature sensor 86. The bottom distal end of the top EC 49 has a set of bond pads that are coupled within the top EC 49 to the common interface bus 83 on the top distal end of the top EC 49 and thus enable passage of the common interface bus 83. The bottom bond pads of the top EC 49 are coupled to a set of top bond pads on the bottom EC 49 by bond wires 82 to provide a common interface bus 83 to the bottom EC 49. In this example, the bottom EC 49 includes a uniform set of point sensors 80. These point sensors are distributed at a higher density than the point sensors 80 of the top EC 49 to achieve better resolution near the gravitational bottom of the fluid container.

In this example, the encapsulating envelope 50 spans the entire length of the fluid property sensor 46 less the external electrical interface 48 and includes a first opening 53 on the top or proximal EC 49 and a second opening 54 on the bottom or distal EC 49.

Fig. 5C is an example of electrical interface 48 proximate the gravitational bottom of the fluid property sensor. The top distal end of fluid property sensor 46 has a top EC 49 similar to top EC 49 of fig. 5B, but in this example there is no top distal bond pad set. The bottom set of bond pads allows the bond wires 82 to couple to the top set of bond pads of a common interface bus 83 on the bottom EC 49. The bottom end of the bottom EC 49 includes a second set of bond pads for coupling the common interface bus 83 to the electrical interface 48. The bond pads and bond wires 82 may be encapsulated with epoxy or glue to prevent damage to the bond wires during later packaging of the fluid property sensor 46. Like fig. 5B, the bottom EC 49 has a denser set of point sensors 80 than the top EC 49. The top EC 49 may have additional sensors, such as a pressure sensor 84 and a temperature sensor 86.

Like the example in fig. 5B, in this example, the encapsulating envelope 50 spans the entire length of the fluid property sensor 46 minus the external electrical interface 48 and includes a first opening 53 on the top or distal EC 49 and a second opening 54 on the bottom or proximal EC 49.

Fig. 5D is an example where there are at least three ECs 49, which may have the same or different configurations. In this example, the top EC 49 is bonded to the electrical interface 48 and is configured similar to the top EC 49 of fig. 5B. The middle or central EC 49 is electrically coupled to both the top EC 49 and the bottom EC 49. The intermediate EC 49 may be only a very low cost EC 49 with a path for the common interface bus 83, or it may include a path with a minimal set of point sensors 80. In other examples, the middle EC may have the same configuration as the top EC 49. The bottom EC 49 may be an EC with a non-uniform distribution of point sensors 80, where the density of the bottom distal end is higher for improved resolution during low-on-ink (LOI) or other low fluid levels. In some examples, middle EC 49 and bottom EC 49 may contain sets of pressure sensors 84 for allowing measurement of stresses not only within EC 49 but also along the entire length of fluid property sensor 46, such as when the fluid property sensor is attached to a wall of fluid container 40 or FAA 20. Thus, a group having a plurality of point sensors 80 may be distributed non-linearly along the length of the EC 49 or fluid property sensor 46, and have the following layout: when used, the density increases along the portion of the EC 49 or fluid property sensor 46 near the gravitational bottom of the fluid container 40 or FAA 20.

The encapsulating enclosure 50 includes a first opening 53 on the top or proximal EC 49, a second opening 54 on the bottom or distal EC 49, and an additional third opening 55 in the middle or central EC 49.

Thus, fluid property sensor 46 may include an elongated Electrical Circuit (EC)49 having a plurality of exposed sets of a plurality of point sensors 80 distributed along the length of EC 49. An external electrical interface 48 may be coupled to a proximal end of the EC 49, where the EC 49 and the external electrical interface 48 are packaged together to form the fluid property sensor 46. The multiple ECs 49 may be daisy-chained end-to-end along the length of the fluid property sensor 46 and share a common interface bus 83. In some examples, a second elongate circuit 49 (second EC) may also be packaged together and extend from a distal end of EC 49 in a length direction of fluid property sensor 46, and electrically coupled from the distal end of EC 49 to a proximal end of second EC 49. In other examples, the plurality of ECs 49 may include a central EC 49 between the proximal EC 49 and the distal EC 49, the central EC 49 having a minimal set of point sensors 80 and a passage of the common interface bus 83. The plurality of ECs 49 may include a proximal EC 49 having a set of various types of sensors, and a distal EC 49 having a high density of at least 50 point sensors 80 per inch. In some examples, the set of point sensors 80 is non-linearly distributed along the length of EC 49, and in other examples, the set of point sensors 80 is non-linearly distributed along the length of fluid property sensor 46.

Fig. 6 is an example of a slightly wider EC 49 for accommodating four or five bond pads for a common interface bus 83 in a single horizontal (relative to vertical in the previous example) direction. This arrangement of bond pad layouts allows more silicon area to allow more digital and analog circuitry to be integrated within the EC 49, as well as providing more structural support to prevent die cracking during flexing. Also, the ECs 49 may be arranged in-line rather than staggered. The plurality of ECs 49 may include a proximal EC 49 having a set of sensors of various types, and a distal EC 49 having a set of multiple point sensors 80 having a high density of at least 40 point sensors per centimeter.

Fig. 7 is an example of openings in a protective layer, such as an oxide, nitride, or another passivation layer (e.g., TEOS layer 158, fig. 10 and 11), that are used to expose electrical impedance sensors on the EC 49 die (fig. 9B). Depending on the type of sensor, it may be better to have a single opening 88. In other examples, to provide additional protection of the EC die from the irritating fluid, it may be better to have a sensor with limited openings or a single opening 89 per sensor.

Fig. 8 is a schematic diagram 90 of an exemplary circuit of how the point sensors 80 can be individually selected for pulse measurement or collectively read for parallel measurement. For some analyses of the fluid, a single fluid level sensor 80 may be used, for example, to detect the presence of fluid at the level of the point sensor 80. In other analyses, it may be desirable to increase the surface area to obtain good characterization of the fluid, for example to determine the chemical composition. Furthermore, since fluid levels may vary, it may be desirable not to combine point sensors 80 that are in contact with air rather than fluid. The parallel register 93, which may be a latch, a flip-flop, or another memory cell, receives a data signal that enters the parallel register 93 along with a clock signal. The clock signal and the data signal are derived from a common bus interface, as are the sense signals, which may be analog signals or digital signals, depending on the implementation. The Q output of the parallel register 93 is coupled to the or gate bank 92. If set high, the parallel register 93 enables the switch 91 from each point sensor 80 to close and couple the point sensor 80 to the sense signal for parallel measurement. The Q outputs of the parallel registers 93 are also coupled to the D inputs of pulse registers 94, and the Q outputs of these pulse registers are coupled to the next pulse register 94 to allow the excitation signal to shift down the chain of pulse registers 94 at each clock cycle to allow each fluid level sensor 80 to be individually coupled to the sense line to allow pulse measurements to be made by internal gated excitation. Thus, the plurality of point sensors 80 may be configured to allow at least one of parallel measurements and internal gated excitation for pulsed measurements. A single data signal may first be synchronously recorded into the parallel register 93 to provide parallel measurements and then transmitted along the pulse register 94 on successive clock signals to provide internal gated excitation for pulse measurements from each fluid property sensor. The point sensor 80 may be several different types of point sensors 80, such as a fluid chemistry sensor, a temperature impedance sensor, an electrical impedance sensor, and the like. Each of the various sensors may be read and measured individually or in combination with other similar sensors to make parallel measurements, based on the data input and synchronously recorded into the parallel register 93 and the pulse register 93.

FIG. 9A is an example of a fluid level sensor 80 based on temperature impedance. In this example, heater 150, which is formed of a resistive or semiconductor element, is powered and controlled by a V + voltage using NFET 156. In other examples, a PFET coupled between V + and heater 150 may be used to power and control the heater. The thermally sensitive piezoresistive elements 152 are used to sense the heat transferred by the heater 150. If there is fluid in contact with the fluid level sensor 80, heat from the heater 150 will dissipate into the fluid at a faster rate than when the fluid level sensor 80 is in contact with air within the fluid container. Thus, the amount of heat absorbed by the piezoresistive elements 152 will be different for the fluid versus air interaction at the fluid level sensor 80. The read circuit 154 may include an amplifier analog/digital converter, offset compensation, etc., and may be used to amplify and convert the change in resistance of the piezoresistor 152 into a more usable signal. Also, the time at which heat from the heater 150 dissipates into the fluid and is detected by the piezoresistor 152 will vary depending on the composition of the fluid. For example, a fluid with a dye will typically have less mass than a fluid with particles such as pigments. Different solvents within the fluid will have different degrees of heat absorption. Some fluids may separate over time and may create a boundary layer. Also, particulate fluids such as pigment-based inks may have different densities at different gravitational heights due to settling. Thus, by examining the output of the read circuit 154 over time from the heater 150 activation and performing a Fourier or other time-to-frequency transformation, different types of ink can be characterized by their FFT (or another transformation) signatures. In one example, the point sensors 80 may each pulse their heaters 150 in parallel and individually read the thermally sensitive piezoresistive elements to allow for a fast search for the fluid level 43. The temperature of those point sensors 80 that are in contact with air will be higher than those point sensors that are in contact with fluid.

FIG. 9B is an example of an electrical impedance-based fluid level sensor 80 that may be used alone or in combination with the example of FIG. 9A. In this example, a voltage or current (AC, DC, or both) excitation signal 166 is applied to the bimetallic pad set 160 of the fluid level sensor 80, and the response to the excitation signal is read by the read circuitry 154. Based on the ionic chemistry (pH, resistance, etc.) of the fluid composition in the fluid reservoir 40, the fluid will generally have a capacitance C-fluid and a resistance (R-fluid), causing a change between the excitation signal and the measured response from the read circuitry 154. Certain fluid characteristics (e.g., pH) may be determined by the conductivity of the fluid, but at the same pH level, different fluid components may have different conductivities. Thus, it may also be advantageous to apply a varying AC signal and determine the appropriate response at each frequency and perform an FFT or another time-frequency transform to retrieve a frequency signature that can be used to find a particular known fluid that has been characterized. Based on the identified fluid type, the pH reading may be adjusted to compensate or calibrate for other ionic chemicals. In addition, a temperature sensor 86 may be used to provide temperature compensation for the pH readings.

FIG. 9C is another example of a fluid level sensor based on temperature impedance. In this example, the piezoresistive element 152 of FIG. 9A is replaced by a diode 166, which is biased with a voltage bias source (Vbias). The forward voltage on diode 166 will vary based on the temperature sensed due to the change in conductivity of the dopant ions. Characterization of the fluid level may be accomplished by checking the voltage on diode 166 after a set time from heater activation. When fluid is in contact with fluid level sensor 80, the temperature change will be lower than when air is in contact with fluid level sensor 80.

Fig. 10 is an exemplary cross section of EC 49 including point sensor 80. In this example, an Electrical Circuit Assembly (ECA)159 supports a silicon-based elongate circuit (EC 49) having a fluid level sensor 80. The silicon base layer 151 may be a CMOS, PMOS, NMOS, or other type of known semiconductor surface. The silicon-based layer 151 may include transistors, diodes, and other semiconductor components. In some examples, the temperature sensing diode 166 may be incorporated into the silicon base layer 151. To improve thermal sensitivity, the silicon base layer 151 may be planarized and thinned to allow less silicon mass to absorb heat from the heater resistor 150, for example, formed in a polysilicon or metal layer separated from the thermal diode 166, for example, by a Field Oxide (FOX) layer 155 and a Tetraethylorthosilicate (TEOS) oxide layer 156. To isolate the heater resistor 150 from surrounding components, the heater resistor may be surrounded by an additional TEOS layer 157. To protect the heater resistor 150 from the harsh chemicals of the fluid in the container, one or more additional TEOS layers 158 may be present between the heater resistor 150 and the fluid or air of the fluid container.

In some cases it may be preferable to have a thicker silicon base layer 151 to provide greater structural strength, such as the example in fig. 5A, where there are two separate encapsulated portions with the EC 49 suspended between them. To improve the amount of temperature difference detected between air and fluid and prevent the silicon base layer 151 from having to be thinned and thus provide additional strength to the EC 49 die, a piezoresistive metal temperature sensor 152 may be formed in the metal layer near the fluid interface. The metal layer may be doped with various impurities, such as boron, to provide the desired piezoresistive effect. In this example, the temperature sensing diode 166 is not present in the silicon, and the polysilicon heater resistor 150 is used to heat the piezoresistive metal temperature sensor 152. Since the heater resistor 150 is close to the metal temperature sensor 152, the metal temperature sensor will heat up quickly. If fluid is present adjacent to the metal temperature sensor 152, then after the heat is removed, the metal temperature sensor will cool at a faster rate than if air were adjacent to the metal temperature sensor. The rate of change of temperature may be used to determine whether fluid is present. In other examples, the resistance of the metal temperature sensor 152 is sampled for a fixed time after power to the heater resistor 150 has been terminated, and a comparison to a predetermined threshold may be used to determine whether fluid is present.

In one example, the thickness of the silicon base layer 151 may be about 100 μm (microns) and the depth of the temperature diode 166, if present, is about 1 μm. A thinner silicon based layer 151, e.g., about 20 μm, allows for higher temperature differential changes between the air and fluid interfaces. For example, a20 μm silicon-based layer 151 may have a temperature difference variation between air and fluid of greater than 14 degrees celsius, while a 100 μm silicon-based layer 151 may have a temperature difference of about 6 degrees celsius. As the die becomes thinner, the thinner die may also raise the maximum temperature of the fluid/air interface due to the smaller mass of the die absorbing thermal energy. The FOX layer 155 may have a depth of about 1 μm, the first TEOS layer 156 may have a depth of about 2 μm, and the second TEOS layer with polysilicon may also have a depth of about 2 μm. If the metal temperature sensor 152 is not used, the additional TEOS layer 158 may be about 2 μm. If a metal temperature sensor 152 is used, it may be positioned about 1 μm from the polysilicon heater resistor 150 and be about 1 μm thick and covered on top with an additional TEOS layer of about 1 μm thickness.

Depending on the various compositions of the fluids used in a system having multiple fluid containers, it may be desirable to keep the maximum temperature at the fluid/air interface substantially constant relative to the amount of energy applied to the heater resistor 150 and to keep the temperature differential at the fluid/air interface also substantially constant. This may enable more consistent readings and less calibration.

Figure 11 is another example of a point sensor 80 in the form of a piezoresistive metal temperature sensor 152 surrounded by a polysilicon heater resistor 150. In this example of a ring heater, heat from the polysilicon heater resistor 150 is more easily transferred to the fluid and only indirectly heats the metal temperature sensor 152. In such a configuration, the temperature difference between the fluid and air interface may remain relatively constant at about 8 degrees celsius, in one example. While the maximum temperature at the fluid/air interface may be slightly higher than the example in fig. 10, the increase in thermal conductivity from the heater resistor to the fluid allows the fluid to maintain a steady maximum temperature over the range of energy applied to the heater resistor 150. This example has dimensions similar to those described with respect to fig. 10. In another example, the temperature sensor 152 may form a ring around the resistor 150, which may be square or other shape.

Fig. 12 is an example EC 49 pressure sensor 84 that includes a strain sensor group 99 implemented along a length of the EC 49 die, e.g., at least five, at least ten, at least twenty, at least forty, at least eighty, at least one hundred, or at least one hundred twenty strain sensors, e.g., approximately one hundred twenty six strain sensors. In one example, the dopant diffusion within the silicon base layer 151 extends along the length of the die and has various taps at different resistive elements 98 to allow for stress at various locations along the length to be measured. In one example, an impurity such as boron is diffused into the silicon base layer 151 to create a piezoresistive response film based strain gauge. In another example, each stress sensor may be a semiconductor bonded strain gauge, wherein the piezoresistive element is bonded to silicon. Thus, fluid characteristic sensor 46 may include a stress sensor group 99 formed along the length of the EC 49 die as one of doped diffused within EC 49 and piezoresistive elements bonded to the EC 49 die. In the example shown in fig. 12, a resistance element 98 is measured using a differential amplifier 96. However, in other examples, the resistive element may be measured using single-ended measurements. Also, rather than using only a single resistor element 98 at one location, multiple resistor elements 98, for example in a full Wheatstone bridge or partial bridge configuration, may be used. To minimize power consumption, in other examples, stress sensor 99 may be power controlled by NFET97 or PFET from V +. The output of each location on the stress sensor 99 can be individually selected for a sense signal to the common interface bus 83 using a switch 91 (e.g., a transmission gate). The switch 91 may be controlled by cascading the select signals using a bank of registers 94 (e.g., D flip-flops), using the data signal and the clock signal of the common interface bus 83.

Since stress sensor 99 extends along the length of the EC 49 die, any stresses due to packaging or mechanical mounting of the die may be read at the time of manufacture or before or at the time of installation or during use to verify performance requirements and to compensate for these inherent packaging and/or mounting stresses of the fluid property sensor 46 when mounted to fluid container 20, 40, so as to subsequently read stresses within the fluid container, such as stresses due to (back) pressure regulation, while accounting for variations due to the packaging and/or mounting stresses. For example, the fluid property sensor 46 in combination with the stress sensor 99 is mounted to a sidewall of the fluid container 40 (as shown in fig. 2A and 2B), and then internal stresses within the fluid container 40 will cause the sidewall of the fluid container 40 to flex and be detected.

On the left side of fig. 12 is a graph illustrating the amount of sidewall deflection in the horizontal axis as a function of the length of fluid property sensor 46. To transfer fluid from the fluid container 40 to the FAA20 (as shown in fig. 1A and 1B), the controller 100 may cause the pump 19 in the service station 18 to perform an hyperinflation event. In this case, the pump 19 fills the pressure regulating bag 42 to its maximum expansion, which causes the walls of the fluid container 40 to deform and flex, thereby forcing the transfer of fluid from the fluid container 40 to the fluid chamber 22 of the FAA 20. Typically, this will result in a ballooning package flexing, as shown in the right-most drawing (see also fig. 17). If the system has multiple fluid containers 40 mounted adjacent to each other such that they come into contact upon one hyperinflation, the stress sensor 99 may detect an hyperinflation event in which adjacent containers come into physical contact. This adjacent container flexing will be in the opposite direction (inward into the package rather than outward bulging) as a local hyperinflation event. The degree of deflection is generally less than a local hyperinflation event and is shown as the leftmost plot. After the over-inflation event, the back pressure within the fluid container 40 and the FAA20 may return to a desired level that may be monitored and measured by the stress sensor 99.

The magnitude of the EC 49 die stress is generally less than the magnitude of the local and adjacent hyperinflation events, rather than the concavity or convexity likely varying randomly over the length of fluid characteristic sensor 46, as shown in the leftmost second graph. In addition to package deflection, the stress sensor 99 may also detect movement of the fluid container 40 due to inertial (acceleration) forces and can detect "splashing" of fluid onto the fluid property sensor 46, for example, during a container movement stop or change event. This type of signal for spatter, which occurs at the air and fluid interface, may only be present at a few resistive elements 98. For inertial movement, the detected stress will typically be sensed uniformly (less any spatter) along the length of the resistive element 98, as shown in the rightmost second graph. In some examples, splash and other liquid movement may be sensed by fluid level sensor 80 instead of or in addition to a pressure sensor.

Because fluid property sensor 46 will experience several different amounts and types of deflection, the EC 49 die may sometimes become overstressed. The crack sensor 95 may extend along the length of the EC 49 die or around the die and is made of a thin film material, such as metal or polymer (poly), that is narrow and may crack when the EC die is subjected to excessive stress. The output of the crack sensor 95 may be designed to communicate on the sense signal of the common interface bus 83, or it may be used to disable operation of the fluid property sensor 46. The crack sensor may comprise an elongated resistor trace.

Thus, having an integral strain gauge in stress sensor 99 allows for monitoring and measuring backpressure regulation, hyperinflation events, movement of fluid containers 40 and FAAs 20 during printing or maintenance operations, presence of adjacent containers, monitoring for air or fluid leaks in the inspection system, and verifying operation of service station 18 and operation of pump 19. Since inertial forces can also be measured, in systems such as printers, the operation of the container movement can be monitored to detect gear wear, obstructions, and paper binding, to name a few. Depending on the container configuration and the type of backpressure regulating system used (spring bag, inflator, sponge, etc.), the stress sensor 99 may also be used to determine the type of backpressure regulation based on package deflection and/or pressure differential during over-inflation and backpressure regulating events.

Fig. 13A-13H are exemplary methods 200 for a process of manufacturing packaged fluid property sensor 46. In fig. 13A, an Elongated Circuit (EC)49 has a silicon substrate 151 on which a group of dot sensors 80 is formed. In fig. 13B, when a thermal fluid level sensor having a diode-based temperature sensor is used, the silicon base layer 151 is planarized to thin the silicon base layer to a range of about 200 to 20 μm. The die thinning operation in fig. 13B may not be performed when a metal-based temperature sensor is used or higher die strength is required. In fig. 13C, the driver circuit 204 may be mounted on an Electrical Circuit Assembly (ECA)159, the ECA 159 having an electrical interface 48 on an opposite side thereof that is coupled to the common interface bus 83 bonding site.

In fig. 13D, ECA 159 and one or more ECs 49 are placed on tape 208 and carrier or substrate 206 in a die/electrical circuit substrate attach operation. In fig. 13E, the EC 49 die and ECA 159 may be transfer molded with a compound, such as an epoxy molding compound or a thermoplastic compound, at a temperature of about 130 degrees celsius to about 200 degrees celsius (e.g., 150 degrees celsius to 190 degrees celsius, such as about 175 degrees celsius). For purposes of this disclosure, "compound" is broadly defined herein to include at least any material that is a thermoset material, polyurethane, polyester plastic, resin, etc. with epoxy functionality. In one example, the compound may be a self-crosslinking epoxy resin and cured by catalytic homopolymerization. In another example, the compound may be a polyepoxide that uses a co-reactant to cure the polyepoxide. Curing of the compounds forms thermosetting polymers with high mechanical properties, high temperature resistance and high chemical resistance.

The carrier 206 and tape 204 are released and the package assembly 50 is flipped over as shown. In fig. 13F, ECA 159 common interface bus 83 is wire bonded to the proximal EC 49 at the proximal end of the EC 49 die. The distal end of the EC 49 die is wire bonded to the distal EC 49 die at the proximal end of the distal EC 49 die. The wire bonds 81 are then encapsulated with an epoxy or glue coating 82. Fig. 13G illustrates that the operations in fig. 13D-13F may be performed using a panel of an array of fluid property sensors 46. The panel may be of any size, but in one example is about 300mm by 100mm, allowing an array of about a 6 x 6 array to be implemented. In step 13H, individual fluid property sensors 46 with encapsulating enclosures 50 and electrical interfaces 48 are singulated from the array.

Accordingly, a method of making a fluid property sensor may include placing an Electrical Circuit Assembly (ECA)159 on a carrier substrate 206, and placing an elongated Electrical Circuit (EC)49 on the carrier substrate 206, the elongated electrical circuit having a plurality of exposed sets of a plurality of point sensors 80 distributed along a length of the EC 49. The method includes encapsulating the external interface board 159 and the EC 49 using transfer molding, and removing the carrier substrate 206. External interface board 159 is electrically coupled to common interface bus 83 with EC 49 using bond wires 82. The electrically coupled bond wires 81 are encapsulated with an epoxy or glue coating 82. In some examples, there are multiple ECs 49 arranged in a daisy chain pattern and share a common interface bus 83. The common interface bus 83 may be electrically coupled in a daisy chain pattern between respective far and near ends of the plurality of ECs 49. In some examples, the EC 49 silicon base layer 151 may be thinned prior to placement on the carrier substrate 206. Fluid property sensors 46 may be formed on an ECA panel, with a plurality of fluid property sensors 46 forming an array and singulated from the array after being electrically coupled with epoxy encapsulation.

Fig. 14A-14D are another exemplary method of making fluid property sensor 46. In fig. 14A, one or more ECs 49 are placed on an ECA 159 having an external electrical interface 48 and driver circuitry 204. EC 49 and driver circuitry 204 are wire bonded to ECA 159 by bond wires 82 and encapsulated with epoxy or glue coating 81. Fig. 14B is a cross-section along cut line a-a of fig. 14A for a transfer over mold packaging operation. Transfer overmolding is a manufacturing process in which a casting material is forced into a mold to overmold other items, such as ECA 159, EC(s) 49, and driver circuitry 204, within the mold. In fig. 14B, a top mold 304 is placed on the top surface of the ECA 159, and a bottom mold 306 is placed on the bottom surface of the ECA 159. The top mold 304 and the bottom mold 306 form a cavity 310 into which a compound is to be injected in a transfer overmolding operation. The top mold 308 may have one or more recesses 308 to allow the implementation of an epoxy or glue coating 82 on the bond wires 81. The top and bottom surfaces of ECA 159 are encapsulated with compound while exposing the sensing portion of the EC without overmolding, such as openings 53 and 54 shown in finished fluid property sensor 46 with encapsulating can 50 and external electrical interface 48. Fig. 14D is a cross-sectional side view of fig. 14C along cut line B-B. ECA 159 is shown supporting the external electrical interface 48 and EC 49 within the encapsulating enclosure 50. The openings 53 and 54 allow the sensor area of the EC 49 to be in contact with fluid or air.

Fig. 15A-15D are illustrations of another exemplary process 350 for fabricating fluid property sensor 46. Fig. 15A shows a top side view of an ECA 159 having an external electrical interface 48, an EC 49 mounted to the ECA 159 and wire bonded to traces on the ECA by bond wires 81, and a driver circuit 204 also mounted to the ECA 159 and wire bonded to traces on the ECA. The wire bonds may be encapsulated with epoxy to provide protection during transfer overmolding. ECA 159 may include a reference set 302 for facilitating positioning and mounting of product fluid property sensor 46 to a fluid container. Proper positioning can help improve the performance of the sensor. In some examples, ECA 159 may be a flexible circuit, while in other examples, may be a glass, polymer, ceramic, paper, or FR4 glass epoxy electrical circuit substrate with copper, solder, tin, nickel, or gold plating or other single or double sided conductive traces. As shown in the side view, in some examples, a support structure 352 may be placed under the ECA 159 to provide structural strength during transfer overmolding to protect the EC 49 from excessive stress. In another example, a removable support 354 may be used in place of support structure 352. To allow removal, a release liner 356 may be placed between the removable support 354 and the ECA 159. Release liner 356 may also be applied to top mold 304 and bottom mold 306 to facilitate removal of fluid property sensor 46 from the molds. In another example, the bottom mold 306 may include a support topography on the bottom mold 306, and the top mold 304 may include a notch (chase) that extends downward and seals a sensing portion of the EC 49 during overmolding.

Fig. 15B shows the ECA 159 of fig. 15A inside a mold having a top mold 304 and a bottom mold 306. Support structure 352 may be made of the same compound used in transfer molding, or in other examples may be made of a material that provides a better coefficient of thermal expansion similar to that of ECA 159. In another example, the support structure may be provided by a support topography that is part of the bottom mold cavity. Fig. 15C shows product fluid property sensor 46 having compound support member 356 potted into potting enclosure 50. Fig. 15D shows the finished fluid property sensor 46 after the removable support 354 is used and removed after overmolding. This process may be used to produce a fluid property sensor 46 having a first package section 51 and a second package section 52 as shown in fig. 5A. As with other processes, ECAs 159 may be formed in an ECA panel having an array of ECAs 159, and an overmolding process may be performed on the ECA panel prior to singulating finished fluid property sensors 46.

FIG. 16 is a flow diagram of an exemplary fluid sensing routine 102 (FIG. 1). The fluid sensing routine 102 may be performed by software or hardware or a combination of both. The routines may constitute software modules (e.g., code embedded in a tangible, non-transitory, machine-readable medium 120) or hardware modules. Hardware modules, such as the controller 100 and/or the driver circuit 204, are tangible units capable of performing certain operations and may be configured or arranged in certain ways. In one example, one or more computer systems or one or more hardware modules of a computer system may be configured by software (e.g., an application or a portion of an application) as a hardware module that operates to perform certain operations described herein. In some examples, the hardware modules may be implemented to be electronically programmable. For example, a hardware module may comprise special purpose circuitry or logic that is permanently configured (e.g., as a special purpose processor, state machine, Field Programmable Gate Array (FPGA), or Application Specific Integrated Circuit (ASIC)) to perform certain operations. A hardware module may also comprise programmable logic or circuitry (e.g., as contained in a general-purpose processor or another programmable processor) that is temporarily configured by software to perform certain operations.

At block 402, a level or position of fluid within a fluid container is determined. The liquid level may be determined by detecting a fluid/air boundary using a thermal impedance sensor and/or an electrical impedance sensor. At block 404, multiple impedance measurements are performed on the fluid over time. Impedance measurements may be made by using thermal impedance sensors and/or electrical impedance sensors. At block 406, a time-to-frequency transform, such as a fast fourier transform, cosine transform, or other time-to-frequency transform, is performed using multiple impedance measurements. At block 408, the output of the frequency transform is then used to compare to various frequency signatures of known fluid components to determine the chemical composition of the fluid.

In summary, fig. 17 is an exemplary fluid cartridge 40 having an exemplary fluid level sensor 46 and an exemplary pressure sensor 84 for detecting an over-inflation event. The left-most drawing illustrates the fluid container 40 with the fluid property sensor 86 attached to a sidewall of the fluid container 40. The fluid property sensor 86 may have a datum to aid in mounting and positioning the sensor to the sidewall. The fluid property sensor 86 has an external interface 48 coupled to a common interface bus 83 that includes only analog and digital signals. Fluid property sensor 86 may include an Electrical Circuit Assembly (ECA) 159. ECA 159 may include an external interface 84 coupled to a common interface bus 83 having a digital interface for digital signals such as data and clock signals, and an analog interface for analog signals such as sense signals. The sense signal may also be used as a digital signal or the enable signal may be used as a sense signal to enable the fluid characteristic sensor 49. Fluid level sensor 46 is coupled to common interface bus 83 to indicate fluid level 43. A pressure sensor 84 is coupled to the common interface bus 83 to indicate a pressure event, such as an over-inflated pressure event. Driver circuit 204 is coupled to common interface bus 83 by fluid level sensor 46 and pressure sensor 84, and communicates characteristics of fluid level sensor 46 and pressure sensor 84 on an analog interface, and communicates threshold indications of both fluid level 43 and pressure events on a digital interface.

The center-most drawing of the container 40-1 is a side view of the fluid container 40 illustrating an exemplary over-inflation event within the fluid container 40. The pressure regulating bag 42 (or other type of pressure regulator) is pressurized by air from the air interface 47, causing the pressure regulating bag to bulge outward and create the concave shape of the container 40. Since the fluid property sensor 86 in this example is attached to the sidewall of the container 40-1, the fluid property sensor 86 also forms a concave shape that closely matches the shape of the container 40. The fluid level 43 may rise as the pressure regulating bag 42 expands to occupy additional space within the fluid container 40 to displace fluid to another area within the fluid container 40 or to be expelled from the fluid container 40 to the fluid actuation assembly 20. In some examples, a printhead 30 die may be attached to a fluid container 40 and over-inflated to reset the back pressure within the fluid container 40.

The rightmost drawing of the container 40-2 is another side view of the fluid container 40, this time illustrating only the deformation of the sidewall of the fluid container 40 caused by performing an over-inflation cycle in the adjacent fluid container 40-1 immediately adjacent to the fluid container 40-2. When the adjacent fluid container 40-1 is inflated and bulges outward to form a concave shape, the shape contacts the sidewall of the fluid container 40-2 and bulges inward to a convex shape. This convex shape causes the sidewall to occupy an area within the fluid reservoir 40-2 and, thus, may also cause the fluid level 43 to rise, but at a lower magnitude than during an over-inflation event within the fluid reservoir 40. Thus, in some examples, a pressure event may be one of an over-inflation cycle within a fluid container 40 and an over-inflation cycle within an adjacent fluid container 40-1. In other examples, the pressure event may include other air inflation events of the pressure regulating bag 42, such as a maintenance operation or detection of a backpressure regulation of the fluid container 40 in the service station 18. In still other examples, pressure sensor 84 may be used to detect many forms of stress on fluid property sensor 84, such as inertial movement of fluid property sensor 86 under acceleration or movement of carriage 12, or even fluid movement within fluid container 40 as fluid splashes onto pressure sensor 84. Thus, the fluid property sensor may communicate the concave, convex, or normal shape of the sidewall of the container 40. Also, an over-inflation cycle may be detected and communicated based on a change in fluid level 43 detected by fluid level sensor 46.

Fluid characteristic sensor 86 may include a plurality of fluid level sensors 80 distributed linearly or non-linearly along the length of fluid level sensor 46, and a plurality of stress sensors 99 distributed along the length of pressure sensor 84 to measure the deflection of ECA 159 of fluid characteristic sensor 86. ECA 159, fluid level sensor 46 and pressure sensor 84, and external interface 48 may be packaged together to form fluid property sensor 86. The fluid level sensor 46 may include a proximal Elongated Circuit (EC)49, and a distal EC 49 electrically coupled to the proximal EC 49 through a common interface bus 83. The proximal EC 49 and the distal EC 49 may each comprise a portion of the pressure sensor 84. In other examples, the fluid level sensor 46 may include an elongated Electrical Circuit (EC)49 and the pressure sensor 84 may include a plurality of stress sensors 99 formed along a length of the EC 49. The plurality of stress sensors 99 may be formed as doped diffused within the EC 49 or piezoresistive elements bonded to the EC 49. The fluid property sensor 86 may be over-deflected if it is deflected too much or due to other circumstances. To detect such occurrences, the fluid property sensor 86 may cause the driver circuit 204 to be configured to communicate the status of the die crack sensor 95 for the EC 49.

Thus, the fluid container 40 comprises a housing containing the chamber 22 or fluid reservoir 44 for containing the fluid. Fluid characteristic sensor 86 may include a sensing portion that extends into reservoir 44 or chamber 22. The sensing portion may include a fluid property sensor 46 for indicating the fluid level 43, and a pressure sensor 84 for indicating a pressure event. The interface section may share a common interface bus 83 with the sensing section and include an analog interface (sensing signal), a digital interface (data signal and clock signal), and an external interface 48 exposed outside the package and electrically coupled to the common interface bus 83. The sense signal may also be used as a digital signal on a digital interface. Driver circuit 204 may be coupled to common interface bus 83 to communicate with fluid level sensor 46 and pressure sensor 84, and to communicate characteristics of fluid level sensor 46 and pressure sensor 84 over an analog interface, and to communicate threshold indications of fluid level 43 and pressure events over a digital interface. The interface portion may be configured to indicate an amount of deflection of the sidewall of the chamber with a plurality of pressure readings. The sensing portion and interface portion may be packaged together to form the fluid property sensor 86 and attached to the sidewall. In some examples, the sensing portion and interface portion may communicate the concave, convex, or normal shape of the sidewall of the container 40. Also, an over-inflation cycle may be detected and communicated based on a change in fluid level 43 detected by fluid level sensor 46. In other examples, the interface portion is used to communicate the chemical composition of a fluid, such as discussed in fig. 16.

In some examples, pressure sensor 84 includes a plurality of stress sensors 99 distributed along the length of fluid property sensor 46 to monitor stress events within the packaging of fluid property sensor 86. Fluid level sensor 46 may include an Elongated Circuit (EC)49 having a plurality of point sensors 80, and pressure sensor 84 may include a plurality of stress sensors 99 formed along the length of EC 49 that form one of a doped diffusion within the EC and a piezoresistive element bonded to the EC. In some examples, the interface portion may be configured to communicate stress events within a package of the fluid property sensor. For example, the stress event may be the detection of inertial movement, fluid movement within the fluid container 40, vibration of the carriage 12 mechanism, and a maintenance event in the service station 18.

The present disclosure describes different examples of fluid property sensors that include an Integrated Circuit (IC) that includes a fluid level sensor and/or a pressure sensor. In some examples, only a pressure level sensor is provided, e.g. in combination with at least one different sensor. An external interface may be electrically coupled to the proximal end of the EC. The pressure sensor may be configured to measure a deflection of the fluid property sensor. The fluid level sensor may include a plurality of point sensors distributed along the length of the IC to sense fluid level. The IC and the external interface may be packaged together to form a fluid property sensor. The IC may include an Elongated Circuit (EC) having a length to width aspect ratio of at least 20: 1. The IC may include a proximal Elongate Circuit (EC) and a distal EC electrically coupled to the proximal EC. The proximal EC and the distal EC may each comprise a portion of a pressure sensor. The IC and the external interface may be packaged together to form a fluid property sensor. Multiple Integrated Circuits (ICs) may be provided that share a common interface bus. The fluid property sensor may include a reference for positioning and attaching the sensor to a wall of the fluid container to allow the fluid property sensor to measure the deflection of the wall. The pressure sensors may include at least five stress sensors. The pressure sensor may include a plurality of stress sensors formed along a length of the IC, for example, for monitoring stress within a package of the fluid property sensor, for example, formed as one of a doped diffused Elongated Circuit (EC) and a piezoresistive element bonded to the EC. The IC may include a die crack sensor.

The fluid container may comprise a fluid property sensor and a reservoir for containing a fluid, for example as described above. The reservoir may contain a fluid along which at least a portion of the fluid property sensor extends and/or is exposed to. The fluid container may further include a fluid interface for supplying fluid from the reservoir to the printer along a generally horizontal axis, the fluid interface being closer to a gravitational bottom of the reservoir than to a middle of a height of the reservoir, and an air interface for the printer to provide air pressure to the reservoir through the air interface to pressurize the fluid in the reservoir, the air interface being disposed above the fluid interface. The fluid container may further comprise a pressure regulator, wherein the air interface is connected to the pressure regulator. An external interface may be exposed outside of the reservoir and electrically coupled to the interface bus, wherein the fluid property sensor is attached to a sidewall of the fluid container, and the pressure sensor is to report an amount of deflection of the sidewall. The fluid property sensor may be attached to a sidewall of the fluid container and may be configured to communicate a concave, convex, or normal shape of the sidewall of the container.

In one example container and/or fluid property sensor, the plurality of ICs includes a proximal Elongate Circuit (EC) having a set of various types of sensors, a distal EC having a high density of fluid property sensors, and a central EC between the proximal EC and the distal EC, the central EC having a minimal set of fluid property sensors and a passageway of a common interface bus. At least one of the plurality of ICs and the interface bus may be packaged together to form a fluid property sensor.

The example pressure sensor may be configured to perform at least one of the following operations: (i) detecting an hyperinflation cycle performed within a fluid container, (ii) detecting an hyperinflation cycle performed on an adjacent fluid container, (iii) detecting at least one of inertial movement of a fluid container and fluid movement within a fluid container, and (iv) monitoring a fluid container for leaks or maintenance operations. The sensing portion of the fluid property sensor may include at least one of a plurality of thermal impedance sensors, a plurality of electrical impedance sensors, a stress sensor, and a die crack sensor.

Exemplary fluid property sensors (which may be any of the fluid property sensors of the preceding examples) may include: (i) an Electrical Circuit Assembly (ECA) including an external interface coupled to a common interface bus; (ii) a fluid level sensor coupled to the common interface bus to indicate a sensor of a fluid level and/or a pressure sensor coupled to the common interface bus to indicate a pressure event; and (iii) a driver circuit coupled to the common interface bus configured to communicate characteristics of the fluid level sensor and the pressure sensor. In some examples, only a pressure level sensor is provided, e.g. in combination with at least one different sensor. The pressure event may be at least one of: an over-inflation cycle within a fluid container, an over-inflation cycle within an adjacent fluid container, a maintenance operation on a fluid container, inertial movement of a fluid property sensor, and fluid movement within a fluid container. The fluid property sensor may include a plurality of point fluid level sensors distributed along a length of the fluid property sensor; and/or a plurality of stress sensors distributed along the length of the pressure sensor for measuring the deflection of the ECA. The fluid property sensor may include a proximal Elongate Circuit (EC) and a distal EC electrically coupled to the proximal EC, wherein one or both ECs are coupled to a common interface bus, and wherein the proximal EC and the distal EC each comprise a portion of a pressure sensor. The sensor portion with the sensor may have a length to width aspect ratio that is five times greater than the aspect ratio of the driver circuit.

The fluid property sensor and/or the container may include interfaces for interfacing the fluid property sensor with the sensing portion, the interfaces including at least one of an analog interface and a digital interface, and an external interface exposed outside the reservoir. Also, a driver circuit coupled to at least one of the interfaces may be provided to communicate with and communicate characteristics of the fluid level sensor and the pressure sensor via the external interface. The sensing portion (e.g., including a pressure sensor) may be configured to communicate at least one of: (i) deflection of the sidewall of the reservoir, (ii) concave, convex, or normal shape of the sidewall of the container, and (iii) chemical composition of the fluid. The pressure sensor may include a plurality of stress sensors distributed along a length of the fluid property sensor to monitor stress events within a package of the fluid property sensor. The external interface is configured to communicate a stress event. The stress event may be at least one of: an over-inflation cycle performed within the fluid container, an over-inflation cycle performed on an adjacent fluid container, inertial movement of the fluid container, fluid movement within the fluid container, leakage of the fluid container, and a maintenance operation of the fluid container.

All publications, patents, and patent documents cited in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. The use of the incorporated reference(s) should be considered supplementary to the present document if the use between this document and those incorporated by reference is inconsistent. For contradictory inconsistencies, the usage in this document controls.

While the claimed subject matter has been particularly shown and described with reference to the foregoing examples, it will be understood by those skilled in the art that many changes may be made therein without departing from the intended scope of the claimed subject matter. The foregoing examples are illustrative, and no single feature or element is essential or critical to all possible combinations that may be claimed in this or a later application. Where the claims recite "a" or "a first" element or the equivalent thereof, such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements.