阅读说明：本技术 物理量检测装置以及印刷装置 (Physical quantity detection device and printing device ) 是由 米村贵幸 于 2020-09-25 设计创作，主要内容包括：本发明提供一种能够准确地对检测对象物体的剩余量进行检测的物理量检测装置以及印刷装置。物理量检测装置的特征在于,具备：容器,其在内部具有对由电介质所构成的检测对象物体进行收纳的收纳空间；第一电极以及至少一个第二电极,其经由所述收纳空间而被对置配置；静电电容检测部,其以互电容方式而对所述第一电极、所述第二电极之间的静电电容进行检测。此外,优选为,物理量检测装置具备对所述第一电极以及所述第二电极进行覆盖的绝缘层、和对所述绝缘层进行覆盖的电磁波屏蔽件。(The invention provides a physical quantity detection device and a printing device capable of accurately detecting the residual quantity of a detection object. The physical quantity detection device is characterized by comprising: a container having a storage space therein for storing a detection target object made of a dielectric material; a first electrode and at least one second electrode arranged to face each other through the housing space; and a capacitance detection unit that detects capacitance between the first electrode and the second electrode in a mutual capacitance manner. Preferably, the physical quantity detection device includes an insulating layer covering the first electrode and the second electrode, and an electromagnetic wave shield covering the insulating layer.)

1. A physical quantity detection device is characterized by comprising:

a container having a storage space therein for storing a detection target object made of a dielectric material;

a first electrode and at least one second electrode arranged to face each other through the housing space;

and a capacitance detection unit that detects capacitance between the first electrode and the second electrode in a mutual capacitance manner.

2. The physical quantity detection apparatus according to claim 1,

the electromagnetic wave shielding device includes an insulating layer covering the first electrode and the second electrode, and an electromagnetic wave shield covering the insulating layer.

3. The physical quantity detection apparatus according to claim 1 or 2,

when an x-axis, a y-axis and a z-axis are set to be orthogonal to each other, the container is a member in which the z-axis direction is set to be a depth direction,

the second electrode has an elongated shape extending along the y-axis direction, and is disposed apart from the first electrode in the x-axis direction.

4. The physical quantity detection apparatus according to claim 3,

the first electrode is in the shape of an elongated strip extending along the z-axis direction,

the second electrodes are provided in plurality so as to be separated from each other along the z-axis direction.

5. The physical quantity detection apparatus according to claim 1,

the detection target object has fluidity,

the container has a discharge unit that discharges the detection target object.

6. The physical quantity detection apparatus according to claim 1,

the capacitance detection unit includes:

a first power supply that applies a pulse voltage to the first electrode and is capable of switching a phase of the pulse voltage;

a second power supply that applies a pulse voltage to the second electrode;

and a detection unit that detects a current or a voltage between the first electrode and the second electrode.

7. The physical quantity detection apparatus according to claim 6,

the capacitance detection unit includes a determination unit that determines the presence or absence of the detection target object between the first electrode and the second electrode based on a detection result of the detection unit.

8. The physical quantity detection apparatus according to claim 7,

the determination unit performs an operation of canceling out parasitic capacitances of an equivalent circuit including the first power supply, the second power supply, and the detection unit, based on a detection result of the detection unit.

9. A printing device is characterized in that a printing device is provided,

a physical quantity detection device according to any one of claims 1 to 8.

Technical Field

The present invention relates to a physical quantity detection device and a printing device.

Background

For example, in a printing apparatus or the like, as remaining amount detection means for detecting the remaining amount of ink in an ink tank, there is known a technique as described in patent document 1. The remaining amount detecting unit described in patent document 1 includes an ink container that contains ink, a pair of electrodes that are arranged to face each other via the ink container, and a capacitance detecting portion that detects an electric signal corresponding to a capacitance value between the pair of electrodes. Each electrode is formed in a long shape extending along a vertical direction. When viewed from a direction in which the electrodes face each other, a portion where the electrodes overlap each other becomes an effective region functioning as a capacitor.

The capacitance values detected by the capacitance detecting portion are different between a case where the ink is present between the electrodes and a case where the ink is reduced from this state so that the ink is not present between the electrodes. This is because the dielectric constants of ink and air are different. The printing apparatus described in patent document 1 detects the remaining amount of ink based on the change in the capacitance value.

However, in the remaining amount detecting unit described in patent document 1, the capacitance value between the electrodes is smaller than the parasitic capacitance value between each electrode and the peripheral portion. Therefore, when the capacitance value between the electrodes is detected, the capacitance value between the electrodes is affected by the parasitic capacitance value, and it is difficult to accurately detect the capacitance value between the electrodes.

Patent document 1: japanese laid-open patent publication No. 2001-121681

Disclosure of Invention

The present invention has been made to solve at least part of the above problems, and can be realized by the following means.

The physical quantity detection device of the present application example is characterized by including: a container having a storage space therein for storing a detection target object made of a dielectric material; a first electrode and at least one second electrode arranged to face each other through the housing space; and a capacitance detection unit that detects capacitance between the first electrode and the second electrode by a mutual capacitance method.

Drawings

Fig. 1 is a schematic configuration diagram showing a printing apparatus according to the present invention.

Fig. 2 is a perspective view of a container provided in the physical quantity sensing device shown in fig. 1.

Fig. 3 is a view seen from the x-axis direction in fig. 2.

Fig. 4 is a view seen from the y-axis direction in fig. 2, and is a view showing electrical connection with the capacitance detection unit.

Fig. 5 is a circuit diagram of the physical quantity detection apparatus shown in fig. 1.

Fig. 6 is a block diagram of the physical quantity detection apparatus shown in fig. 1.

Fig. 7 is a graph showing a temporal change in the current detected by the detection unit.

Fig. 8 is a graph showing a temporal change in the current detected by the detection unit.

Fig. 9 is a graph showing a temporal change in the current detected by the detection unit.

Fig. 10 is a graph showing a temporal change in the current detected by the detection unit.

Fig. 11 is a diagram for explaining a positional relationship between the first electrode and the second electrode.

Fig. 12 is a flowchart for explaining a control operation performed by the control unit shown in fig. 6.

Fig. 13 is a flowchart for explaining a control operation performed by the control unit shown in fig. 6.

Detailed Description

Hereinafter, the physical quantity detection device and the printing device according to the present invention will be described in detail based on preferred embodiments shown in the drawings.

< first embodiment >

Fig. 1 is a schematic configuration diagram showing a printing apparatus according to the present invention. Fig. 2 is a perspective view of a container provided in the physical quantity detection device shown in fig. 1. Fig. 3 is a view seen from the x-axis direction in fig. 2. Fig. 4 is a view seen from the y-axis direction in fig. 2, and is a view showing electrical connection with the capacitance detection unit. Fig. 5 is a circuit diagram of the physical quantity detection device shown in fig. 1. Fig. 6 is a block diagram of the physical quantity detection apparatus shown in fig. 1. Fig. 7 to 10 are graphs showing temporal changes in the current detected by the detection unit. Fig. 11 is a diagram for explaining a positional relationship between the first electrode and the second electrode. Fig. 12 and 13 are flowcharts for explaining a control operation performed by the control unit shown in fig. 6.

For convenience of explanation, in fig. 2 to 4 and fig. 11, an x axis, a y axis, and a z axis are set as three axes orthogonal to each other, and the explanation will be given based on these axes. In addition, hereinafter, a direction parallel to the x axis is referred to as "x axis direction", a direction parallel to the y axis is referred to as "y axis direction", and a direction parallel to the z axis is referred to as "z axis direction".

In fig. 2 to 4 and 11, the z-axis direction, i.e., the vertical direction, is referred to as the "vertical direction", the x-axis direction and the y-axis direction, i.e., the left-right direction, is referred to as the "horizontal direction", and the x-y plane is referred to as the "horizontal plane".

Hereinafter, the tip side of each arrow mark to be illustrated is referred to as "+ (plus)" or "plus", and the base end side is referred to as "- (minus)" or "minus". For convenience of explanation, the upper side in the + z-axis direction in fig. 2 to 4 and 11 is referred to as "upper" or "upper", and the lower side in the-z-axis direction is referred to as "lower" or "lower".

The physical quantity detection device 1 shown in fig. 1 is a device for detecting the remaining quantity of a detection target object made of a dielectric material. The detection target object is not particularly limited as long as it is composed of a dielectric substance, and examples thereof include various liquids such as ink, chemical solution, mercury, oil, gasoline, drinking water, and other water, and various powders or granules such as toner, sand, cement, chemicals, wheat flour, salt, and granulated sugar. These liquids, powders or granules have fluidity.

Further, the detection target object may not have fluidity. Examples of the non-flowable substance include paper and various sheets.

In the present specification, a dielectric refers to a substance having an insulating property. In addition, the dielectric refers to a substance having a relative permittivity larger than that of air, that is, a relative permittivity larger than 1.

In the following description, a case where the physical quantity detection device 1 is incorporated in the printing apparatus 10 and the detection target object is the ink 100 will be described as an example. The ink 100 is not particularly limited, and examples thereof include cyan, magenta, black, transparent, and metal powder-containing inks. In addition, these color materials may be either dyes or pigments. The physical quantity detection device 1 can detect the remaining amount of the ink 100 regardless of the type thereof.

First, the printing apparatus 10 will be described before the description of the physical quantity detection apparatus 1.

The printing apparatus 10 includes: a storage section 11 that stores sheets S as printing paper, an inkjet head 12 that ejects ink 100 to the sheets S supplied from the storage section 11, a physical quantity detection device 1, and a display section 13. Further, the ink 100 is supplied from the physical quantity detection device 1 to the inkjet head 12.

As described later, the display unit 13 functions as an informing unit for informing of the remaining amount of the ink 100 detected by the physical quantity detecting device 1. The display unit 13 is configured by, for example, a liquid crystal screen. The notification unit is not limited to the display unit 13, and may be configured to notify by voice, to notify by vibration, or to notify by a blinking pattern of a lamp, for example. Further, a device having a communication function such as a PC screen or a smartphone can also function as a notification unit.

By incorporating the physical quantity detection device 1 into the printing apparatus 10, as will be described later, the remaining amount of the ink 100 can be accurately detected, and the user can accurately grasp the remaining amount of the ink 100.

Next, the physical quantity detection device 1 will be explained.

As shown in fig. 2 to 6, the physical quantity detection device 1 includes a container 2, a first electrode 3, a second electrode 4, a capacitance detection unit 50, and a control unit 6. The control unit 6 may also serve as a control unit that controls each unit of the printing apparatus 10.

The container 2 has a storage space 20 therein, and can store ink 100 as an object to be detected in the storage space 20. The container 2 has a bottomed cylindrical shape with the z-axis direction set to the depth direction. That is, as shown in fig. 2, the container 2 includes a bottom plate 21 located on the-z axis side, and four side walls 22, 23, 24, and 25 that are provided upright so as to project from the bottom plate 21 toward the + z axis side. The storage space 20 is a space surrounded by the bottom plate 21 and the side walls 22 to 25.

Although not shown, container 2 has a ceiling on the side opposite to bottom plate 21, that is, on the + z axis side of side walls 22 to 25. The top plate may be joined to the side walls 22 to 25, or may be configured to be detachable.

The bottom plate 21 is a plate member joined to the-z-axis side of the side walls 22 to 25. The bottom plate 21 has a discharge port 211, which is a discharge portion formed by a through hole. This enables the ink 100 in the housing space 20 to be discharged to the outside of the container 2. The discharge port 211 is connected to the inkjet head 12 via a not-shown conduit. The ink 100 discharged from the discharge port 211 is supplied to the inkjet head 12 shown in fig. 1 via a conduit to perform printing on the sheet S.

When the ink 100 is discharged from the discharge port 211, the amount of the ink 100 in the housing space 20 decreases so that the liquid surface moves toward the-z axis while maintaining a state in which the liquid surface is along the horizontal direction.

The ink 100 as the detection target object is liquid and has fluidity. The container 2 has a discharge port 211 which is a discharge portion for discharging the ink 100 as the detection target object. In this way, when the ink 100 in the tank 2 is discharged and gradually decreases, it is necessary to grasp the remaining amount in the tank 2 in advance. By grasping the remaining amount in advance, the ink 100 can be prevented from being used up at an unintended timing.

The discharge port 211 may be provided in a portion other than the bottom plate 21, for example, in the vicinity of the bottom plate 21 of any one of the side walls 22 to 25. Further, the configuration is not limited to the configuration having the discharge port 211, and for example, a tube or the like may be inserted into the housing space 20 from a portion other than the bottom plate 21 to suck the ink 100 in the container 2. In this case, the tube functions as a discharge portion.

The side wall 22 is erected along the + z-axis side from the edge portion on the-x-axis side of the bottom plate 21. The side wall 22 is plate-shaped with the x-axis direction as the thickness direction. Three second electrodes 4A to 4C are arranged on the outer surface side of the side wall 22, that is, on the-x-axis side surface side.

The side wall 23 is erected along the + z-axis side from the edge portion on the-y-axis side of the bottom plate 21. The side wall 23 is plate-shaped with the y-axis direction as the thickness direction.

The side wall 24 is erected along the + z-axis side from the edge portion of the + x-axis side of the bottom plate 21. The side wall 24 is plate-shaped with the x-axis direction as the thickness direction. The first electrode 3 is disposed on the outer surface side of the side wall 24, that is, on the + x axis side surface side.

The side wall 25 is erected along the + z-axis side from the edge portion on the + y-axis side of the bottom plate 21. The side wall 25 is plate-shaped with the y-axis direction as the thickness direction.

The side walls 22 and 24 are disposed in parallel and opposite to each other, apart from each other in the x-axis direction. The side walls 22 and 24 are the same size and shape. The side walls 23 and 25 are disposed apart from each other in the y-axis direction and are parallel to each other. The side wall 23 and the side wall 25 are the same in size and shape. That is, the container 2 has a rectangular parallelepiped outer shape.

The side walls 22 to 25 are flat plates. However, at least a part of the elastic member may be bent or curved.

It is preferable that the length of the side walls 23 and 25 in the x-axis direction, that is, the distance D between the first electrode 3 and the second electrode 4, which will be described later, be shorter than the length y3 of the side walls 22 and 24 in the y-axis direction. This can sufficiently secure the maximum capacitances of the first capacitor ca (capacitor) to the third capacitor cc (capacitor) described later, and can improve the detection accuracy of the remaining amount of the ink 100.

The spacing distance D is preferably 5mm or more and 100mm or less, and more preferably 10mm or more and 50mm or less. This can more reliably exhibit the above-described effects.

The length y3 in the y-axis direction of the side walls 22 and 24 is preferably 20mm or more and 200mm or less, and more preferably 30mm or more and 150mm or less. This can more reliably exhibit the above-described effects.

The material of the container 2 is not particularly limited as long as it is made of a dielectric material that does not allow the ink 100 to penetrate therethrough, and various resin materials such as polyolefin, polycarbonate, and polyester, and various glass materials can be used. The container 2 may be a hard container, a soft container, or a container partially hard and the rest soft.

Further, the relative permittivity of the constituent material of the container 2 is preferably 1 or more, and further preferably 2 or more. This is advantageous for detecting the remaining amount of the ink 100.

The container 2 may or may not have visible light permeability, but preferably has visible light permeability, that is, internal visibility. This makes it possible to grasp the remaining amount of ink 100 even by visual observation. In particular, the side walls 23 and 25 preferably have internal visibility.

A first electrode 3 and at least one second electrode 4 are arranged on the outside of such a container 2. As shown in fig. 2 and 3, the first electrode 3 and the second electrode 4 are opposed to each other in parallel in the x-axis direction. Although described in detail below, the first electrode 3 has an elongated shape extending in the z-axis direction.

Although the second electrode 4 is operated individually, it is preferable that a plurality of second electrodes are provided separately from each other along the z-axis. This allows the remaining amount of ink 100 to be detected in stages as described later.

In the present embodiment, the second electrode 4 is provided with three, and hereinafter, they are referred to as a second electrode 4A, a second electrode 4B, and a second electrode 4C. The second electrodes 4A to 4C are arranged apart from each other in this order from the + z axis side along the z axis direction. The second electrodes 4A to 4C are provided so as to be parallel to each other.

As shown in fig. 3, when the first electrode 3 and the second electrodes 4A to 4Cx are projected in the axial direction, that is, when viewed from the x-axis direction, the first electrode 3 and the second electrodes 4A to 4C form three regions overlapping each other. Hereinafter, a region where the first electrode 3 and the second electrode 4A overlap is set as an effective region 300A, a region where the first electrode 3 and the second electrode 4B overlap is set as an effective region 300B, and a region where the first electrode 3 and the second electrode 4C overlap is set as an effective region 300C. The effective regions 300A to 300C are separated from each other along the z-axis direction and arranged in this order from the + z-axis side.

The portions of the first electrode 3 and the second electrode 4A corresponding to the effective region 300A, that is, the portions of the first electrode 3 and the second electrode 4A forming the effective region 300A constitute a first capacitor Ca in an equivalent circuit shown in fig. 5. The portions of the first electrode 3 and the second electrode 4B corresponding to the effective region 300B, that is, the portions of the first electrode 3 and the second electrode 4B forming the effective region 300B constitute a second capacitor Cb in an equivalent circuit shown in fig. 5. The portions of the first electrode 3 and the second electrode 4C corresponding to the effective region 300C, that is, the portions of the first electrode 3 and the second electrode 4C forming the effective region 300C constitute a third capacitor Cc in an equivalent circuit shown in fig. 5. The first to third capacitors Ca to Cc are capacitors (capacitors) and are represented by an equivalent circuit shown in fig. 5. This will be described in detail below.

First, the structure of the first electrode 3 will be described.

The first electrode 3 is a transmission electrode to which a pulse voltage is applied from a first power supply 8A described later. As shown in fig. 2 to 4, the first electrode 3 is disposed outside the side wall 24, i.e., on the + x axis side. The first electrode 3 is made of a conductive material, for example, a metal material such as gold, silver, copper, aluminum, iron, nickel, cobalt, or an alloy containing these metals. The first electrode 3 may be formed directly on the outer surface of the side wall 24 by, for example, plating, vapor deposition, printing, or the like, may be attached to the outer surface of the side wall 24 via an adhesive layer not shown, or may be supported on the side wall 24 in a contact or non-contact manner by a support member not shown.

The first electrode 3 is elongated in the z-axis direction. As shown in fig. 3, the width of the first electrode 3, i.e., the length y1 in the y-axis direction is fixed along the z-axis direction. The length y1 is not particularly limited, and is preferably 2mm or more and 100mm or less, and more preferably 5mm or more and 50mm or less, for example. This makes it easy to secure sufficient sizes of the effective areas 300A to 300C, and the accuracy of detecting the remaining amount of the ink 100 can be improved.

The length of the first electrode 3, that is, the length z1 in the z-axis direction is not particularly limited, and is, for example, preferably 3mm or more and 100mm or less, and more preferably 5mm or more and 200mm or less. Thus, the first electrode 3 can be more reliably overlapped with each of the second electrodes 4A to 4C when viewed from the x-axis direction. The effective regions 300A to 300C can be made to have the same area.

In addition, the area S1 of the first electrode 3 in the shape of a plan view as viewed from the x-axis direction is preferably 6mm²Above 30000mm²Hereinafter, and more preferably 25mm²Above and 10000mm²The following. This makes it easy to secure sufficient sizes of the effective areas 300A to 300C, and the accuracy of detecting the remaining amount of the ink 100 can be improved.

The end of the first electrode 3 on the-z axis side is located closer to the-z axis side than the bottom surface 212 of the container 2 facing the storage space 20. If the end of the first electrode 3 on the-z axis side is located on the + z axis side with respect to the bottom surface 212 of the container 2 facing the storage space 20, the area of the effective region 300C where the first electrode 3 and the second electrode 4C overlap may be reduced due to the position of the second electrode 4C. In contrast, in the physical quantity detection device 1, the area of the effective region 300C can be secured as large as possible by the above configuration. Therefore, the accuracy of detecting the remaining amount of ink 100 can be improved.

In the illustrated structure, the end portion of the first electrode 3 on the + z axis side is located on the-z axis side with respect to the edge portion of the sidewall 24 on the + z axis side. However, the present invention is not limited to this, and the end portion of the first electrode 3 on the + z axis side may be aligned with the edge portion of the sidewall 24 on the + z axis side.

In the illustrated configuration, the first electrode 3 has an elongated shape extending in the z-axis direction, but the present invention is not limited to this, and may have a shape satisfying a relationship of y1 ≧ z1 depending on the shape of the side wall 24. The first electrode 3 may be divided into portions other than the portions where the effective regions 300A to 300C are formed.

Next, the second electrodes 4A to 4C will be explained.

The second electrodes 4A to 4C are receiving electrodes and are disposed on the outer surface of the side wall 22, i.e., on the-x-axis side. The second electrodes 4A to 4C are each formed in a long shape extending in the y-axis direction. The second electrodes 4A to 4C are arranged along the z-axis direction so as to be separated from each other in this order from the + z-axis side. The second electrodes 4A to 4C are provided in parallel.

As shown in fig. 2 to 4, the second electrodes 4A to 4C are disposed outside the side wall 22, i.e., on the-x-axis side. The second electrodes 4A to 4C can be formed using the same materials and formation methods as those listed for the first electrode 3.

Since the second electrodes 4A to 4C have the same shape, size, and interval, the second electrode 4A will be representatively described below. However, the present invention is not limited to this, and at least one of the shape, size, and interval may be different.

As shown in fig. 3, in the present invention, the length of the second electrode 4A, i.e., the length y2 along the y-axis direction is longer than the length y1 of the first electrode 3 in the y-axis direction, and is preferably 3mm or more and 110mm or less, and more preferably 6mm or more and 60mm or less, for example. This makes it easy to secure sufficient sizes of the effective areas 300A to 300C, and the accuracy of detecting the remaining amount of the ink 100 can be improved.

In the present invention, the width of the second electrode 4A, that is, the length z2 along the z-axis direction is shorter than the length z1 of the first electrode 3, and is preferably 0.2mm or more and 10mm or less, and more preferably 0.5mm or more and 5mm or less, for example. Thus, when viewed from the x-axis direction, all of the second electrodes 4A to 4C can be maximally overlapped with the first electrode 3. The effective regions 300A to 300C can be made to have the same area.

In addition, the area S2 of the second electrode 4A in the shape of a plan view as viewed from the x-axis direction is preferably 0.6mm²Above and 1100mm²Hereinafter, and more preferably 3mm²Above and 300mm²The following. This makes it easy to secure sufficient sizes of the effective areas 300A to 300C, and the accuracy of detecting the remaining amount of the ink 100 can be improved.

In the illustrated structure, the end portion of the second electrode 4A on the + y axis side coincides with the edge portion of the sidewall 22 on the + y axis side. However, the end portion of the second electrode 4A on the + y axis side may be positioned closer to the-y axis side than the edge portion of the sidewall 22 on the + y axis side.

In the illustrated structure, the-y-axis-side end of the second electrode 4A coincides with the-y-axis-side edge of the side wall 22. However, the end portion of the second electrode 4A on the-y axis side may be located on the + y axis side of the edge portion of the sidewall 22 on the-y axis side.

When the x axis, the y axis, and the z axis along the vertical direction are set to be orthogonal to each other as described above, the container 2 is a container in which the z axis direction is the depth direction, and the second electrode 4 is elongated extending along the y axis direction and is disposed apart from the first electrode 3 in the x axis direction. As a result, as will be described later, the remaining amount of the ink 100 in the container 2 can be accurately detected regardless of the arrangement accuracy of the first electrode 3 and the second electrode 4.

In the physical quantity detection device 1, one first electrode 3 is configured to have both one electrode plate of the first capacitor Ca, one electrode plate of the second capacitor Cb, and one electrode plate of the third capacitor Cc. Thus, when a voltage is applied to the first electrode 3, the voltages applied to the first capacitor Ca, the second capacitor Cb, and the third capacitor Cc can be made the same. Therefore, variations in the detection accuracy of the capacitances of the first capacitor Ca, the second capacitor Cb, and the third capacitor Cc can be suppressed, and high detection accuracy can be achieved regardless of the remaining amount of the ink 100.

Here, when two opposing electrodes of the capacitance detection unit are slightly displaced as described in patent document 1, the area of the effective region is reduced. Since the maximum electrostatic capacitance value of the capacitor is reduced when the effective area is reduced, the detection accuracy of the electrostatic capacitance is lowered. Therefore, in the capacitance detection unit of patent document 1, high positional accuracy of each electrode is required in order to obtain high detection accuracy. In contrast, as described below, the physical quantity detecting device 1 can prevent or suppress a decrease in the detection accuracy of the electrostatic capacitance even if the position of each electrode is slightly shifted. This will be explained below.

As shown in fig. 3, in the physical quantity detecting apparatus 1, the length y1 of the first electrode 3 in the y-axis direction, the length z1 of the first electrode 3 in the z-axis direction, the length y2 of the second electrodes 4A to 4C in the y-axis direction, and the length z2 of the second electrodes 4A to 4C in the z-axis direction satisfy y1 < y2, and z1 > z 2. Accordingly, even if the first electrode 3 and the second electrodes 4A to 4C are relatively shifted in the + y-axis direction, the-y-axis direction, the + z-axis direction, and the-z-axis direction by a small amount, the areas of the effective regions 300A to 300C do not change. Even if the first electrodes 3 are provided in a state in which the extending direction thereof is slightly inclined with respect to the z-axis as shown in fig. 11, for example, the shapes of the effective regions 300A to 300C are changed from rectangular to parallelogram without changing the areas. According to this aspect, the maximum capacitance of the first to third capacitors Ca to Cc is prevented from decreasing, and the accuracy of detecting the capacitance can be prevented or suppressed from decreasing. As a result, the remaining amount of the ink 100 in the container 2 can be accurately detected regardless of the arrangement accuracy of the first electrode 3 and the second electrodes 4A to 4C.

Although not shown, when the extending direction of the second electrodes 4A to 4C is slightly inclined with respect to the y-axis, the shapes of the effective regions 300A to 300C are changed and the areas of the effective regions 300A to 300C are not changed, as in the above. Therefore, it is apparent that the same effects as described above can be obtained even when the arrangement accuracy of the second electrodes 4A to 4C is deteriorated.

As shown in fig. 3, the first electrode 3 has portions projecting toward the + z axis and the-z axis of the effective region 300A, portions projecting toward the + z axis and the-z axis of the effective region 300B, and portions projecting toward the + z axis and the-z axis of the effective region 300C, respectively, when viewed from the x axis direction. Accordingly, even if the arrangement accuracy of the first electrode 3 and the second electrodes 4A to 4C is lowered, the areas of the effective regions 300A to 300C can be more reliably prevented from changing.

When the regions where the first electrode 3 overlaps the second electrodes 4A to 4C are defined as the effective region 300A, the effective region 300B, and the effective region 300C as viewed in the x-axis direction, the first electrode 3 has portions protruding toward the positive side in the z-axis direction and the negative side in the z-axis direction of the effective regions 300A to 300C, respectively. Accordingly, even if the arrangement accuracy of the first electrode 3 or the second electrodes 4A to 4C is lowered, the areas of the effective regions 300A to 300C can be more reliably prevented from changing.

As shown in fig. 3, the second electrode 4A has portions protruding toward the + y axis side and the-y axis side of the effective region 300A when viewed from the x axis direction. The second electrode 4B has portions protruding toward the + y axis and the-y axis of the effective region 300B when viewed from the x axis direction. The second electrode 4C has portions protruding toward the + y axis and the-y axis of the effective region 300C when viewed from the x axis direction. Accordingly, even if the arrangement accuracy of the first electrode 3 and the second electrodes 4A to 4C is lowered, the areas of the effective regions 300A to 300C can be more reliably prevented from changing.

When the regions where the first electrode 3 overlaps the second electrodes 4A to 4C are the effective region 300A, the effective region 300B, and the effective region 300C as viewed in the x-axis direction, the second electrodes 4A to 4C have portions protruding toward the y-axis direction positive side and the y-axis direction negative side of the effective regions 300A to 300C, respectively. Accordingly, even if the arrangement accuracy of the first electrode 3 or the second electrodes 4A to 4C is lowered, the areas of the effective regions 300A to 300C can be more reliably prevented from changing.

As shown in fig. 3, the length z1 of the first electrode 3 is longer than the maximum distance z3, which is the distance between the + z-axis long side 41 of the second electrode 4A and the-z-axis long side 42 of the second electrode 4C. That is, the length z1 of the first electrode 3 is longer than the maximum length in the z-axis direction of the region in which the second electrodes 4A to 4C are formed.

As described above, when the maximum distance between the vertically upper long side 41 of the second electrode 4A located most vertically above among the plurality of second electrodes 4 and the vertically lower long side 42 of the second electrode 4C located most vertically below among the plurality of second electrodes 4 along the z axis is z3, z1 > z3 is satisfied. This makes it possible to more reliably realize a configuration in which the first electrode 3 has portions protruding toward the + z axis and the-z axis in the effective regions 300A to 300C, respectively, when viewed from the x axis direction. Therefore, the above-described effects can be more reliably exhibited.

When the total area of the effective regions 300A to 300C is S0 and the area of the first electrode 3 is S1, it is preferable that 0.03. ltoreq.S 0/S1. ltoreq.0.7 is satisfied, and more preferably 0.05. ltoreq.S 0/S1. ltoreq.0.6 is satisfied. This can sufficiently secure the sizes of the effective regions 300A to 300C, and can improve the detection accuracy of the ink 100.

When the total area of the effective regions 300A to 300C is S0 and the total area of the second electrodes 4A to 4C is S2, it is preferable that 0.1. ltoreq.S 0/S2. ltoreq.0.6 is satisfied, and more preferably 0.2. ltoreq.S 0/S2. ltoreq.0.5 is satisfied. This can sufficiently secure the sizes of the effective regions 300A to 300C, and can improve the detection accuracy of the ink 100.

When the maximum depth of the housing space 20 of the container 2 is D1 and the minimum distance between the second electrode 4C and the bottom surface 212 as the bottom of the container 2 when viewed from the x-axis direction is D2, it is preferable to satisfy 0 ≦ D2/D1 ≦ 0.5, and more preferably satisfy 0 ≦ D2/D1 ≦ 0.3. By thus biasing the second electrode 4C toward the bottom surface 212 of the container 2, it is possible to detect that the remaining amount of the ink 100 is 0 or close to 0.

As shown in fig. 4, the first electrode 3 and the second electrodes 4A to 4C are covered with an insulating layer 7. The outside of the insulating layer 7 is further covered with a shielding material 9. The shielding material 9 is an electromagnetic wave shield. By providing the shielding material 9, it is possible to prevent the first electrode 3 and the second electrodes 4A to 4C from interfering with other electronic circuits or other electronic components, not shown, or from noise entering the detection signal. Therefore, the detection accuracy of the remaining amount of ink 100 can be improved. Further, the insulating layer 7 prevents the first electrode 3 and the second electrodes 4A to 4C from being electrically connected to the shield material 9.

The material of each insulating layer 7 is not particularly limited, and various rubber materials, various resin materials, and the like can be used, for example.

Further, each of the shield materials 9 is connected to a reference potential, that is, a ground electrode. As the material constituting the shield material 9, the same materials as those listed as the material constituting the first electrode 3 and the second electrodes 4A to 4C can be used.

Next, a circuit diagram of a main portion of the physical quantity detection device 1 will be explained.

As shown in fig. 5, the physical quantity detection device 1 includes: a first power supply 8A electrically connected to the first electrode 3, a second power supply 8B electrically connected to the second electrode 4A to the second electrode 4C, a first capacitor Ca, a second capacitor Cb, a third capacitor Cc, a detection unit 5 electrically connected to the second electrodes 4A to 4C, and a control unit 6. The first power supply 8A, the second power supply 8B, the detection unit 5, and the control unit 6 constitute a capacitance detection unit 50.

The first capacitor Ca, the second capacitor Cb, and the third capacitor Cc are connected in parallel with each other. The first power supply 8A applies pulse voltages having the same period, phase, and magnitude to the first electrodes 3 of the first to third capacitors Ca to Cc. The second power supply 8B applies pulse voltages having the same period, phase, and magnitude to the second electrodes 4A to 4C of the first to third capacitors Ca to Cc, respectively. The magnitude of the pulse voltage applied by the first power supply 8A and the magnitude of the pulse voltage applied by the second power supply 8B are different. Further, the magnitude of the pulse voltage applied by the first power supply 8A and the magnitude of the pulse voltage applied by the second power supply 8B may be the same.

The frequency of the pulse voltage applied by the first power supply 8A and the second power supply 8B is preferably 1kHz or more, and more preferably 1MHz or more. Thus, even if the ink 100 adheres to the inner surface of the container 2 above the liquid surface, for example, the remaining amount of the ink 100 can be accurately and quickly detected.

When detecting the remaining amount of the ink 100, the first power supply 8A applies a pulse voltage of a pulse wave of a predetermined frequency to the first electrode 3. The second power supply 8B applies a pulse voltage of a pulse wave having the same frequency as the first power supply 8A to the second electrodes 4A to 4C. The first power supply 8A can be switched between a state in which a pulse voltage having the same phase as the second power supply 8B is applied to the first electrode 3 and a state in which a pulse voltage having the opposite phase to the second power supply 8B is applied to the first electrode 3. As a result, the first to third capacitors Ca to Cc are switched between a first state in which the pulse voltages of the same phase are applied and a second state in which the pulse voltages of opposite phases are applied.

In the equivalent circuit shown in fig. 5, a first parasitic capacitor Ca ' is connected in series to the first capacitor Ca, a second parasitic capacitor Cb ' is connected in series to the second capacitor Cb, and a third parasitic capacitor Cc ' is connected in series to the third capacitor Cc.

The first parasitic capacitor Ca' is a parasitic capacitance formed by the first electrode 3 or the second electrode 4A of the first capacitor Ca and the peripheral portion thereof, for example, the insulating layer 7 and the shielding material 9, and is a portion that operates as a capacitor.

Similarly, the second parasitic capacitor Cb' is a parasitic capacitance formed by the first electrode 3 or the second electrode 4B of the second capacitor Cb and the peripheral portion thereof, for example, the insulating layer 7 and the shielding material 9, and operates as a capacitor.

Similarly, the third parasitic capacitor Cc' is a parasitic capacitance formed by the first electrode 3 or the second electrode 4C of the third capacitor Cc and the peripheral portion thereof, for example, the insulating layer 7 and the shielding material 9, and is a portion that operates as if it were a capacitor.

Further, the first parasitic capacitor Ca' is connected to the first capacitor Ca in series connection in the equivalent circuit. In addition, the second parasitic capacitor Cb' is connected to the second capacitor Cb in series connection in the equivalent circuit. The third parasitic capacitor Cc' is connected to the third capacitor Cc in series in the equivalent circuit.

The detection unit 5 is an ammeter that detects a current flowing between the first electrode 3 and the second electrode 4 with time as information on capacitance between the first electrode 3 and the second electrode 4. In the present embodiment, the currents of the first to third capacitors Ca to Cc are detected. When the first power supply 8A and the second power supply 8B apply the pulse voltages to the first to third capacitors Ca to Cc, the capacitance values of the first to third capacitors Ca to Cc change depending on the presence or absence of the ink 100, and the current waveform changes depending on the capacitance. The detector 5 outputs information on the current to the controller 6.

The detection unit 5 may be a voltmeter that temporally detects the voltage between the first electrode 3 and the second electrode 4 as information related to the capacitance between the first electrode 3 and the second electrode 4.

As shown in fig. 6, the control Unit 6 includes a CPU (Central Processing Unit) 61 and a storage Unit 62. The control unit 6 is a determination unit that determines the presence or absence of the ink 100 between the first electrode 3 and the second electrode 4 based on the detection result of the detection unit 5.

The CPU61 reads and executes various programs and the like stored in the storage unit 62. The storage unit 62 stores various programs executable by the CPU 61. Examples of the storage unit 62 include a volatile Memory such as a RAM (Random Access Memory), a nonvolatile Memory such as a ROM (Read Only Memory), and a detachable external storage device.

The storage unit 62 stores various programs executed by the CPU61, and the first to third reference values K1 to K3.

Next, the principle of detecting the remaining amount of the ink 100 will be described. Hereinafter, the first capacitor Ca, that is, the first electrode 3 and the second electrode 4A will be described.

When the liquid surface of the ink 100 is located at the position P1 shown in fig. 4, that is, when the ink 100 is present between the first electrode 3 and the second electrode 4A, the detection unit 5 detects the current waveform shown in fig. 7 in the first state of the same phase, and the detection unit 5 detects the current waveform shown in fig. 8 in the second state of the opposite phase. These current waveforms are in opposite phases.

Based on these current waveforms, the control unit 6 calculates an average current value i (a) in the first capacitor Ca in the first state and an average current value i (b) in the first capacitor Ca in the second state. The average current value i (a) in the first state is represented by the following formula (1), and the average current value i (b) in the second state is represented by the following formula (2).

I(A)＝F·((Vt-Vd)·Cm+Vt·CpT)…(1)

I(B)＝F·((Vt+Vd)·Cm+Vt·CpT)…(2)

In equations (1) and (2), F represents the frequency of the pulse voltage, Vt represents the maximum value of the pulse voltage applied to the first electrode 3, Vd represents the maximum value of the pulse voltage applied to the second electrode 4, Cm represents the capacitance value of the first capacitor Ca, and CpT represents the capacitance value of the first parasitic capacitor Ca'.

Then, the control unit 6 calculates a difference Δ I ═ I (a) -I (b) between the average current value I (a) and the average current value I (b). That is, the following formula (3) is calculated.

ΔI＝F·((Vt-Vd)·Cm+Vt·CpT)-F·((Vt+Vd)·Cm+Vt·CpT)…(3)

When equation (3) is calculated, the difference Δ I becomes 2F · Vd · Cm, and the capacitance value CpT of the first parasitic capacitor Ca' is cancelled. Therefore, the capacitance value CpT of the first parasitic capacitor Ca' is not affected when the remaining amount of the ink 100 is detected.

Then, the control unit 6 determines whether or not the difference Δ I is smaller than the first reference value K1. The first reference value K1 is a value stored in advance in the storage unit 62. In the state where the ink 100 is located between the first electrode 3 and the second electrode 4 as described above, since the difference Δ I is equal to or greater than the first reference value K1, it is determined that the ink 100 is present between the first electrode 3 and the second electrode 4.

On the other hand, when the remaining amount of the ink 100 is reduced until the liquid surface of the ink 100 is located at the position P2 shown in fig. 4, that is, when the ink 100 is not present between the first electrode 3 and the second electrode 4A, the detection unit 5 detects the current waveform shown in fig. 9 in the first state of the same phase, and the detection unit 5 detects the current waveform shown in fig. 10 in the second state of the opposite phase.

The amplitude of the current waveform shown in fig. 9 and 10, that is, the maximum value of the current is smaller than the maximum value of the current in the current waveform shown in fig. 7 and 8. This is because the capacitance of the first capacitor Ca changes due to the dielectric in the first capacitor Ca being replaced with air from the ink 100.

Further, as described above, the control unit 6 calculates the average current value I (a) in the first state and the average current value I (b) in the second state, respectively, and calculates the difference Δ I therebetween. Then, it is determined whether or not the difference Δ I is smaller than the first reference value K1. When the ink 100 is not present between the first electrode 3 and the second electrode 4A, the difference Δ I is smaller than the first reference value K1. Therefore, the control unit 6 determines that the ink 100 is not present between the first electrode 3 and the second electrode 4A.

As described above, the method of calculating the difference Δ I between the average current value I (a) of the first capacitor Ca in the first state and the average current value I (b) of the first capacitor Ca in the second state based on the detection result of the detection unit 5 and determining the presence or absence of the ink 100 based on the calculation result is a so-called mutual capacitance method. In such a mutual capacitance method, as described above, the capacitance value CpT of the first parasitic capacitor Ca' is eliminated when calculating the difference Δ I, and therefore the value of the capacitance value CpT is not taken into consideration in the difference Δ I. Therefore, the comparison between the difference Δ I and the first reference value K1 can be accurately performed, and the presence or absence of the ink 100 can be accurately determined.

The control unit 6 performs such determination also in the second capacitor Cb and the third capacitor Cc. That is, the control unit 6 detects the presence or absence of the ink 100 between the first electrode 3 and the second electrode 4B and detects the presence or absence of the ink 100 between the first electrode 3 and the second electrode 4C in the same manner as described above. The second reference value K2 is used to detect the presence or absence of the ink 100 between the first electrode 3 and the second electrode 4B, and the third reference value K3 is used to detect the presence or absence of the ink 100 between the first electrode 3 and the second electrode 4C. The first reference value K1 to the third reference value K3 may be the same value or different values.

In the present embodiment, the detection unit 5 is configured to detect the currents of the first to third capacitors Ca to Cc, but the present invention is not limited thereto, and the detection unit 5 may be configured to detect the voltages, for example.

By performing such determination, information on the remaining amount of ink 100 in the container 2 can be obtained based on the detection result of the detection unit 5.

Examples of the information related to the remaining amount of the ink 100 include information for digitizing the remaining amount of the ink 100 in stages, such as "0", "1/2", "1", or "0%", "30%", "60%", and "100%", and characters or symbols in order according to the remaining amount of the ink 100, such as "a", "B", "C", and "D". Hereinafter, they are collectively referred to as only "the remaining amount of the ink 100".

Such information is displayed on the display unit 13. This allows the user to grasp the remaining amount of ink 100.

As described above, the physical quantity detection device 1 includes: a container 2 having a storage space 20 therein for storing ink 100 as an object to be detected made of a dielectric material; a first electrode 3 and at least one second electrode 4, the first electrode 3 and the at least one second electrode 4 being arranged to face each other via a housing space 20; and a capacitance detecting unit 50 for detecting the capacitance between the first electrode 3 and the second electrode 4 by mutual capacitance. By detecting the electrostatic capacitance between the first electrode 3 and the second electrode 4 by the mutual capacitance method, the detection result is not affected by the parasitic capacitances, that is, the first parasitic capacitor Ca 'to the third parasitic capacitor Cc'. Therefore, the capacitance between the first electrode 3 and the second electrode 4 can be accurately detected. As a result, the remaining amount of the ink 100 can be accurately detected.

The physical quantity detection device 1 further includes an insulating layer 7 that covers the first electrode 3 and the second electrode 4, and a shielding material 9 that is an electromagnetic wave shield that covers the insulating layer 7. With this configuration, it is possible to reduce the influence of noise while preventing the first electrode 3 and the second electrode 4 from being electrically connected to the surroundings as described above. In addition, according to this configuration, the first to third parasitic capacitors Ca 'to Cc' as described above are formed in the equivalent circuit, but in the present invention, the capacitance detection unit 50 detects the remaining amount of the ink 100 by the mutual capacitance method, and therefore, the influence of the first to third parasitic capacitors Ca 'to Cc' can be eliminated. That is, the effect of the present invention is remarkable only because of the structure having the insulating layer 7 and the shielding material 9.

The capacitance detection unit 50 further includes: a first power supply 8A that applies a pulse voltage to the first electrode 3 and can switch the phase of the pulse voltage; a second power supply 8B that applies a pulse voltage to the second electrode 4; and a detection unit 5 for detecting a current or a voltage between the first electrode 3 and the second electrode 4. The capacitance detection unit 50 further includes a control unit 6, and the control unit 6 is a determination unit that determines the presence or absence of an object to be detected between the first electrode 3 and the second electrode 4 based on the detection result of the detection unit 5. This makes it possible to detect the remaining amount of the ink 100 in the mutual capacitance system as described above.

As described above, the control unit 6 as the determination unit performs an operation of canceling out the parasitic capacitances of the circuits including the first power supply 8A, the second power supply 8B, and the detection unit 5 (the capacitances of the first parasitic capacitor Ca 'to the third parasitic capacitor Cc') based on the detection result of the detection unit 5. Accordingly, the influence of the first to third parasitic capacitors Ca 'to Cc' can be ignored, and the remaining amount of the ink 100 can be accurately detected.

The printing apparatus 10 of the present invention includes the physical quantity detection apparatus 1 of the present invention. This makes it possible to perform printing while enjoying the advantages of the physical quantity detection device 1 described above. In particular, since the remaining amount of ink 100 can be accurately detected, for example, when the remaining amount of ink 100 gradually decreases, ink 100 is appropriately replenished, thereby preventing printing from being stopped at an unintended timing. In addition, when a plurality of second electrodes 4 are provided, the degree of reduction of the ink 100 can be grasped in stages, and the timing of replenishment of the ink 100 can be predicted well.

Next, the control operation performed by the control unit 6 will be described with reference to a flowchart shown in fig. 12.

First, in step S101, detection of the remaining amount of ink 100 is started. That is, voltages are applied to the first to third capacitors Ca to Cc shown in fig. 5, and currents corresponding to the capacitances of the first to third capacitors Ca to Cc are detected, respectively.

In step S102, it is determined whether or not the difference Δ I between the average current value I (a) and the average current value I (b) of the first capacitor Ca (hereinafter simply referred to as "difference Δ I") is smaller than the first reference value K1. For example, as shown in fig. 4, when the liquid surface of the ink 100 is at the position P1, the dielectric in the first capacitor Ca is the ink 100, the difference Δ I is equal to or greater than the first reference value K1, it is determined in step S102 that the difference Δ I is not less than the first reference value K1, and the remaining amount is displayed in step S103. That is, information that the liquid level of the ink 100 is located above the first capacitor Ca is displayed on the display unit 13.

As described above, the display method includes information such as "0", "1/2", "1", or "0%", "30%", "60%", and "100%", information for digitizing the remaining amount of the ink 100 in stages, characters or symbols sorted in order according to the remaining amount of the ink 100, such as "a", "B", "C", and "D". For example, "100%" or "a" is displayed in step S103.

When it is determined in step S102 that the current of the first capacitor Ca is smaller than the first reference value K1, the process proceeds to step S104. For example, when the liquid surface of the ink 100 is at the position P2 shown in fig. 4, the dielectric in the first capacitor Ca is air, and the amplitude of the current in the first capacitor Ca decreases as shown in fig. 9.

In step S104, it is determined whether or not the difference Δ I between the second capacitors Cb is smaller than the second reference value K2. When the liquid surface of the ink 100 is at the position P2 shown in fig. 4, the dielectric in the second capacitor Cb is the ink 100, and the difference Δ I between the second capacitors Cb is equal to or greater than the second reference value K2. In this case, it is determined in step S104 that the difference Δ I of the second capacitor Cb is not smaller than the second reference value K2, and the remaining amount is displayed in step S105. That is, information that the liquid level of the ink 100 is located between the first capacitor Ca and the second capacitor Cb is displayed on the display unit 13. For example, "60%" or "B" is displayed in step S105.

If it is determined in step S104 that the difference Δ I of the second capacitor Cb is smaller than the second reference value K2, the process proceeds to step S106. For example, when the liquid surface of the ink 100 is at the position P3 shown in fig. 4, the dielectric in the second capacitor Cb is air, and the amplitude of the current in the second capacitor Cb decreases as shown in fig. 9.

In step S106, it is determined whether or not the difference Δ I between the third capacitors Cc is smaller than a third reference value K3. When the liquid surface of the ink 100 is at the position P3 shown in fig. 4, the dielectric in the third capacitor Cc is the ink 100, and it is determined in step S106 that the difference Δ I of the third capacitor Cc is not less than the third reference value K3, and the remaining amount is displayed in step S107. That is, information that the liquid level of the ink 100 is located between the second capacitor Cb and the third capacitor Cc is displayed on the display unit 13. For example, "30%" or "C" is displayed in step S107.

When it is determined in step S106 that the difference Δ I of the third capacitor Cc is smaller than the third reference value K3, information that the remaining amount of ink 100 is 0 is displayed on the display unit 13 in step S108. For example, "0%" or "D" is displayed in step S108.

For example, when the remaining amount of the ink 100 is 0, the dielectric in the third capacitor Cc is air, and the amplitude of the current in the third capacitor Cc decreases as shown in fig. 9.

Then, in step S109, it is determined whether or not an end instruction is given. The determination of this step is performed based on whether or not the user of the printing apparatus 10 turns off the power supply, for example. If it is determined in step S109 that the end instruction has been given, the routine is ended here. When it is determined in step S109 that the end instruction has not been issued, the process returns to step S108, and the display unit 13 is kept in a state in which information that the remaining amount of ink 100 is 0 is displayed.

Through the above steps, the remaining amount of the ink 100 can be accurately detected. Further, such a control operation as shown in fig. 13 may be performed. Only the differences from the control operation shown in fig. 12 will be described below.

In the control operation shown in fig. 13, the process returns to step S102 after step S103, returns to step S102 after step S105, returns to step S102 after step 107, and returns to step S102 when no is determined in step 109. That is, when detecting the remaining amount of the ink 100, the difference Δ I between all of the first to third capacitors Ca to Cc is detected regardless of the remaining amount of the ink 100. With this configuration, even when the ink 100 is replenished in the middle, the amount of the replenished ink 100 can be accurately detected.

Although the physical quantity detection device and the printing device of the present invention have been described above based on the illustrated embodiments, the present invention is not limited thereto, and the configuration of each part may be replaced with any configuration having the same function. In addition, any other structure may be added.

The container may be detachable from the printing apparatus, or may be a fixed member. When detachable, the container may be replaced with a new one immediately after the ink is used up, or may be used repeatedly by replenishing the ink. In the case of a configuration in which the container is fixed to the printing apparatus, the ink is used so as to be replenished if the remaining amount of ink decreases.

In the above-described embodiment, the case where the physical quantity detection device is applied to the ink tank of the printing apparatus has been described, but the present invention is not limited to this, and can be suitably applied to detection of the remaining amount of the dielectric material tank in which the internal capacity changes. As other embodiments, a molding material tank having a 3D printer or an injection molding machine, a water heater, a beverage tank, a medical tank for drip or insulin, or a refrigerant tank for cooling, and the like are exemplified. The present invention is not limited to the liquid tank, and can be applied to solid remaining amount detection, for example, a hopper for paper feeding (stocker), a hopper for paper discharge, and the like.

Description of the symbols

10 … printing device; 11 … storage part; 12 … ink jet head; a display part 13 …; 1 … physical quantity detecting means; 2 … container; 20 … storage space; 21 … a bottom panel; 211 … discharge port; 212 … bottom surface; 22 … side walls; 23 … side walls; 24 … side walls; 25 … side walls; 3 … a first electrode; 4 … a second electrode; 4a … second electrode; 4B … second electrode; a 4C … second electrode; 41 … long side; 42 … long side; a 5 … detection unit; 6 … control section; 7 … an insulating layer; 8a … first power supply; 8B … second power supply; 9 … a shielding material; 50 … electrostatic capacitance detection unit; 61 … CPU; 62 … storage section; 100 … ink; 300a … effective area; 300B … effective area; 300C … effective area; ca … first capacitor; ca' … first parasitic capacitor; a Cb … second capacitor; cb' … second parasitic capacitor; cc … third capacitor; cc' … third parasitic capacitor; d … separation distance; d1 … maximum depth; d2 … minimum separation distance; position P1 …; position P2 …; position P3 …; an S … sheet; area S0 …; area S1 …; area S2 …; y1 … length; y2 … length; y3 … length; z1 … length; z2 … length.