阅读说明：本技术 液体喷出装置的致动器驱动电路
(Actuator driving circuit for liquid ejecting apparatus
) 是由 仁田昇
小野俊一
原田苍太 于 2020-03-05 设计创作，主要内容包括：本申请公开了一种能够稳定地驱动致动器的液体喷出装置的致动器驱动电路。实施方式的液体喷出装置的致动器驱动电路具备：输出开关,该输出开关具备：第一晶体管,向致动器赋予第一电压；以及第二晶体管,向致动器赋予比第一电压大的第二电压,根据驱动电压波形进行接通/断开的动作；以及波形存储器,根据仅使第一晶体管导通、仅使第二晶体管导通、或使第一晶体管和第二晶体管双方均截止的状态的设定和执行状态的定时的设定来设定驱动电压波形,并且存储至少最后导通的晶体管互不相同的多种驱动电压波形。(An actuator driving circuit of a liquid ejection device capable of stably driving an actuator is disclosed. An actuator drive circuit of a liquid discharge apparatus according to an embodiment includes: an output switch, the output switch comprising: a first transistor that applies a first voltage to the actuator; and a second transistor that applies a second voltage larger than the first voltage to the actuator and performs an on/off operation according to the drive voltage waveform; and a waveform memory configured to set a drive voltage waveform according to setting of a state in which only the first transistor is turned on, only the second transistor is turned on, or both the first transistor and the second transistor are turned off, and setting of a timing of executing the state, and to store a plurality of types of drive voltage waveforms different from each other at least in a transistor which is turned on last.)
1. An actuator driving circuit of a liquid discharge apparatus, comprising:
an output switch, the output switch comprising: a first transistor that applies a first voltage to the actuator; and a second transistor that applies a second voltage larger than the first voltage to the actuator and performs an on/off operation according to a drive voltage waveform; and
and a waveform memory configured to set the drive voltage waveform according to setting of a state in which only the first transistor is turned on, only the second transistor is turned on, or both the first transistor and the second transistor are turned off, and setting of a timing for executing the state, and to store a plurality of types of drive voltage waveforms different from each other at least in a transistor which is turned on last.
2. The actuator driving circuit of a liquid ejection device according to claim 1,
further provided with: a third transistor that applies a third voltage, which is larger than the first voltage and smaller than the second voltage, to the actuator,
the waveform memory sets the drive voltage waveform according to setting of a state in which only the first transistor is turned on, only the second transistor is turned on, only the third transistor is turned on, or all of the first transistor, the second transistor, and the third transistor are turned off, and setting of a timing for executing the state, and stores a plurality of types of the drive voltage waveforms in which at least transistors that are turned on last are different from each other.
3. The actuator driving circuit of a liquid ejection device according to claim 1,
comprising the following drive voltage waveforms: after the second transistor is turned on to start charging the actuator, the second transistor is turned off after a first predetermined time shorter than a time required for completion of the charging operation has elapsed, and the second transistor is turned on again after a second predetermined time has further elapsed.
4. The actuator driving circuit of a liquid ejection device according to claim 2,
comprising the following drive voltage waveforms: after the second transistor is turned on to start charging the actuator, the second transistor is turned off after a first predetermined time shorter than a time required for completion of the charging operation has elapsed, and the second transistor is turned on again after a second predetermined time has further elapsed.
5. The actuator driving circuit of the liquid ejection device according to any one of claims 1 to 4,
comprising the following drive voltage waveforms: after the first transistor is turned on and discharge from the actuator is started, the first transistor is turned off after a third predetermined time shorter than a time required for completion of the discharge operation has elapsed, and the first transistor is turned on again after a fourth predetermined time has further elapsed.
6. The actuator driving circuit of the liquid ejection device according to any one of claims 2 to 4,
comprising the following drive voltage waveforms: after the third transistor is turned on to start charging or discharging the actuator, the third transistor is turned off after a fifth predetermined time shorter than a time required to complete the charging operation or the discharging operation has elapsed, and the third transistor is turned on again after a sixth predetermined time has elapsed.
7. The actuator driving circuit of a liquid ejection device according to claim 5,
comprising the following drive voltage waveforms: after the third transistor is turned on to start charging or discharging the actuator, the third transistor is turned off after a fifth predetermined time shorter than a time required to complete the charging operation or the discharging operation has elapsed, and the third transistor is turned on again after a sixth predetermined time has elapsed.
8. The actuator driving circuit of the liquid ejection device according to any one of claims 1 to 4,
the first voltage is 0V.
9. The actuator driving circuit of a liquid ejection device according to claim 5,
the first voltage is 0V.
10. The actuator driving circuit of a liquid ejection device according to claim 6,
the first voltage is 0V.
Technical Field
Embodiments of the present invention relate to an actuator driving circuit of a liquid ejecting apparatus.
Background
A liquid ejecting apparatus that supplies a predetermined amount of liquid to a predetermined position is known. The liquid discharge device is mounted on, for example, an inkjet printer, a 3D printer, a dispensing device, and the like. An ink printer ejects droplets of ink from an inkjet head and prints an image or the like on the surface of a recording medium. The 3D printer ejects and solidifies the droplets of the modeling material from the modeling material ejection head to form the three-dimensional modeled object. The dispensing device ejects droplets of a sample and supplies the droplets to a plurality of containers or the like by a predetermined amount.
An inkjet head, which is a liquid discharge device of an inkjet printer, includes a piezoelectric-driven actuator as a driving device for discharging ink from a nozzle. A set of nozzles and actuators form a channel. The head drive circuit supplies a drive voltage waveform to the selected actuator based on the print data and drives the selected actuator. For example, it is proposed to stop applying the bias when printing is not performed, because deterioration of the actuator is suppressed. For example, the method stops the application of the bias voltage when the print data is latched by the buffer of 3 stages and the next dot is blank. The drive voltage waveform for applying the bias voltage and the drive voltage waveform for stopping the bias voltage are generated by cutting out from the COM waveform. Therefore, in this method, since the COM waveform is commonly supplied to a large number of channels, the COM waveform varies depending on which portion of each channel is cut out at that time, and stable driving cannot be performed. In addition, many circuits that generate COM waveforms consume power and generate heat, and are large and expensive.
Disclosure of Invention
The present invention has been made to solve the problem of providing an actuator driving circuit for a liquid ejecting apparatus capable of stably driving an actuator.
The actuator driving circuit of the liquid ejecting apparatus according to the present embodiment includes: an output switch, the output switch comprising: a first transistor that applies a first voltage to the actuator; and a second transistor that applies a second voltage larger than the first voltage to the actuator and performs an on/off operation according to the drive voltage waveform; and a waveform memory configured to set a drive voltage waveform according to setting of a state in which only the first transistor is turned on, only the second transistor is turned on, or both the first transistor and the second transistor are turned off, and setting of a timing of executing the state, and to store a plurality of types of drive voltage waveforms different from each other at least in a transistor which is turned on last.
Drawings
Fig. 1 is an overall configuration diagram of an inkjet printer according to an embodiment.
Fig. 2 is a perspective view of the ink jet head of the ink jet printer.
Fig. 3 is a plan view of a nozzle plate of the ink jet head.
Fig. 4 is a longitudinal sectional view of the ink jet head.
Fig. 5 is a longitudinal sectional view of a nozzle plate of the ink jet head.
Fig. 6 is a block diagram showing the configuration of the control system of the ink jet printer.
Fig. 7 is a block diagram showing the configuration of the command analysis unit of the control system.
Fig. 8 is a block diagram showing the configuration of the waveform generating unit of the control system.
Fig. 9 is an explanatory diagram of a WG register showing information of a drive voltage waveform of one frame.
Fig. 10 is an explanatory diagram of the allocation and encoding of the WG registers for the respective grayscale values, and the drive voltage waveforms WK0 to WK 7.
Fig. 11 is a block diagram showing the configuration of the waveform selecting unit of the control system.
Fig. 12 is a circuit diagram of an output buffer of the above-described control system.
Fig. 13 shows an example of a series of drive voltage waveforms applied to the ink jet head.
Fig. 14 is an explanatory diagram showing a phenomenon of print thickening at the first point after the bias application is stopped.
Fig. 15 is an explanatory diagram showing the drive voltage waveform and the measurement result of the electrostatic capacitance of the actuator in the test performed to confirm the print thickening phenomenon at the first point.
Fig. 16 shows another example of a series of driving voltage waveforms applied to the ink jet head.
Fig. 17 is an explanatory diagram showing a modification of WG registers GW and GS.
Fig. 18 is an explanatory diagram showing a modification of WG registers GW and GS.
Fig. 19 is an explanatory diagram of the allocation and encoding of the WG registers for each gray-scale value, and the drive voltage waveforms WK0 to WK 7.
Fig. 20 shows another example of a series of drive voltage waveforms applied to the inkjet head.
Description of reference numerals:
10 … ink jet printer; 1A-1D … inkjet heads; 4 … ink supply section; a 51 … nozzle; 7 … head drive circuit; 72 … command analysis unit; 74 … print data buffers; 75 … waveform selection unit; 76 … output buffer; 8 … actuator; 100 … print control means; 307 … WG register storage; a 400 … WGG register; a Q0 … first transistor; a Q1 … second transistor; q2 … third transistor.
Detailed Description
Hereinafter, the liquid ejecting apparatus according to the embodiment will be described in detail with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals.
An inkjet printer 10 that prints an image on a recording medium will be described as an example of an image forming apparatus equipped with the liquid discharge apparatus 1 according to the embodiment. Fig. 1 is a schematic configuration of an inkjet printer 10. The inkjet printer 10 includes, for example, a box-shaped case 11 as an exterior body. Inside the casing 11, a cassette 12 for storing a sheet S as an example of a recording medium, an upstream conveyance path 13 for the sheet S, a conveyance belt 14 for conveying the sheet S taken out from the cassette 12, inkjet heads 1A to 1D for ejecting droplets of ink onto the sheet S on the conveyance belt 14, a downstream conveyance path 15 for the sheet S, a discharge tray 16, and a control board 17 are disposed. An operation unit 18 as a user interface is disposed on the upper side of the housing 11.
The image data printed on the sheet S is generated by, for example, the computer 2 as an external connection device. The image data generated by the computer 2 is transmitted to the control board 17 of the ink jet printer 10 via the cable 21 and the connectors 22B and 22A.
The pickup roller 23 feeds the sheets S one by one from the cassette 12 to the upstream conveying path 13. The upstream conveying path 13 is constituted by a pair of conveying rollers 13a, 13b and sheet guides 13c, 13 d. The sheet S is sent to the upper surface of the conveying belt 14 via the upstream conveying path 13. An arrow a1in the figure indicates a conveying path of the sheet S from the cassette 12 to the conveying belt 14.
The conveyor belt 14 is a mesh-like endless belt having a plurality of through holes formed in the surface thereof. The three rollers, i.e., the driving roller 14a and the driven rollers 14b and 14c, support the belt 14 to be rotatable. The motor 24 rotates the conveying belt 14 by rotating the driving roller 14 a. The motor 24 is an example of a driving device. In the figure a2 shows the direction of rotation of the conveyor belt 14. A negative pressure container 25 is disposed on the back side of the conveyor belt 14. The negative pressure container 25 is connected to a fan 26 for pressure reduction, and the inside of the container is made negative by an air flow generated by the fan 26. The sheet S is sucked and held on the upper surface of the conveying belt 14 by the negative pressure in the negative pressure container 25. In the figure a3 shows the direction of flow of the air stream.
The inkjet heads 1A to 1D are disposed opposite to the sheet S sucked and held on the conveyor belt 14 with a very small gap of, for example, 1 mm. The inkjet heads 1A to 1D respectively eject droplets of ink onto the sheet S. The sheet S is printed with an image while passing under the inkjet heads 1A to 1D. The ink jet heads 1A to 1D have the same configuration except that the colors of the discharged inks are different. The color of the ink is, for example, cyan, magenta, yellow, and black.
The ink jet heads 1A to 1D are connected to the ink tanks 3A to 3D and the ink supply pressure adjusting devices 32A to 32D, respectively, via the ink flow paths 31A to 31D. The ink flow paths 31A to 31D are, for example, resin tubes. The ink tanks 3A to 3D are containers storing ink. The ink tanks 3A to 3D are disposed above the ink jet heads 1A to 1D. In standby, the ink supply pressure adjusting devices 32A to 32D adjust the pressure inside the inkjet heads 1A to 1D to a negative pressure, for example, -1kPa, with respect to the atmospheric pressure so that ink does not leak from the nozzles 51 (see fig. 2) of the inkjet heads 1A to 1D. When printing an image, the inks of the ink tanks 3A to 3D are supplied to the inkjet heads 1A to 1D by the ink supply pressure adjusting devices 32A to 32D.
After printing, the sheet S is conveyed from the conveyor belt 14 to the downstream conveying path 15. The downstream conveying path 15 is constituted by conveying roller pairs 15a, 15b, 15c, 15d and sheet guides 15e, 15f defining a conveying path of the sheet S. The sheet S is sent from the discharge port 27 to the discharge tray 16 via the downstream conveying path 15. An arrow a4 in the figure illustrates a conveying path of the sheet S.
Next, the structure of the ink jet head 1A as a liquid ejection head will be described with reference to fig. 2 to 6. Since the ink-jet heads 1B to 1D have the same configuration as the ink-jet head 1A, detailed description thereof is omitted.
Fig. 2 is an external perspective view of the ink-jet head 1A. The ink jet head 1A includes: the ink supply unit 4, the nozzle plate 5, the flexible substrate 6, and the head drive circuit 7 are examples of the liquid supply unit. A plurality of nozzles 51 for ejecting ink are arranged on the nozzle plate 5. The ink discharged from each nozzle 51 is supplied from the ink supply portion 4 communicating with the nozzle 51. The ink flow path 31A from the ink supply pressure adjusting device 32A is connected to the upper side of the supply unit 4. The arrow a2 indicates the rotation direction of the conveyor belt 14 (see fig. 1).
Fig. 3 is a partially enlarged top view of the nozzle plate 5. The nozzles 51 are two-dimensionally arranged in a column direction (X direction) and a row direction (Y direction). The nozzles 51 arranged in the row direction (Y direction) are arranged obliquely so as not to overlap the nozzles 51 on the axis of the Y axis. The nozzles 51 are arranged at intervals of a distance X1 in the X-axis direction and a distance Y1 in the Y-axis direction. For example, the distance X1 is about 42.25 μm and the distance Y1 is about 253.5 μm. That is, the distance X1 was determined so that the recording density became 600DPI in the X-axis direction. Further, the distance Y1 was also determined in the Y-axis direction in a 600DPI printing manner. The nozzles 51 are arranged in the X direction with 8 nozzles 51 arranged in the Y direction as a set. Although not shown, for example, 150 sets of nozzles 51 are arranged in the X direction, and a total number of nozzles 51 is 1200.
A piezoelectric-driven electrostatic capacitive actuator 8 (hereinafter, simply referred to as an actuator 8) as a driving source for an ink discharge operation is provided for each nozzle 51. A set of nozzles 51 and actuators 8 form a channel. The actuators 8 are formed in an annular shape and arranged so that the nozzle 51 is positioned at the center thereof. The dimensions of the actuator 8 are, for example, an inner diameter of 30 μm and an outer diameter of 140 μm. Each actuator 8 is electrically connected to the cell electrode 81. Each actuator 8 electrically connects 8 actuators 8 arranged in the Y direction by the common electrode 82. The individual electrodes 81 and the common electrodes 82 are also electrically connected to the mounting pads 9, respectively. The mounting pad 9 becomes an input port for imparting a drive voltage waveform to the actuator 8. The cell electrodes 81 apply drive voltage waveforms to the actuators 8, and the actuators 8 are driven according to the applied drive voltage waveforms. For convenience of explanation, fig. 3 shows the actuators 8, the cell electrodes 81, the common electrode 82, and the mounting pads 9 in solid lines, but they are disposed inside the nozzle plate 5 (see the vertical cross-sectional view of fig. 4. of course, the positions of the actuators 8 are not limited to the inside of the nozzle plate 5.
The mounting pads 9 are electrically connected to wiring patterns formed on the flexible substrate 6 via, for example, an Anisotropic Conductive Film (ACF). Further, the wiring pattern of the flexible substrate 6 is electrically connected to the head drive circuit 7. The head drive Circuit 7 is, for example, an IC (Integrated Circuit). The head drive circuit 7 applies a drive voltage waveform to the actuator 8 selected based on the image data to be printed.
Fig. 4 is a longitudinal sectional view of the ink-jet head 1A. As shown in fig. 4, the nozzle 51 penetrates the nozzle plate 5 in the Z-axis direction. The nozzle 51 has a diameter of 20 μm and a length of 8 μm, for example. A plurality of pressure chambers (individual pressure chambers) 41 that communicate with the nozzles 51 are provided inside the ink supply unit 4. The pressure chamber 41 is, for example, a cylindrical space whose upper portion is open. The upper portion of each pressure chamber 41 is open and communicates with a common ink chamber 42. The ink flow path 31A communicates with the common ink chamber 42 via the ink supply port 43. The pressure chambers 41 and the common ink chamber 42 are filled with ink. The common ink chamber 42 includes, for example, a flow path shape for circulating ink. The pressure chamber 41 has a structure in which a cylindrical hole having a diameter of, for example, 200 μm is formed in a single crystal silicon wafer having a thickness of, for example, 500 μm. The ink supply portion 4 is made of, for example, alumina (Al)2O3) A structure of a space corresponding to the common ink chamber 42 is formed.
Fig. 5 is a partially enlarged view of the nozzle plate 5. The nozzle plate 5 has a structure in which a protective layer 52, an actuator 8, and a diaphragm 53 are stacked in this order from the bottom surface side. The actuator 8 has a structure in which a lower electrode 84, a piezoelectric body 85 which is a thin film as an example of a piezoelectric element, and an upper electrode 86 are laminated. The upper electrode 86 is electrically connected to the cell electrode 81, and the lower electrode 84 is electrically connected to the common electrode 82. At the boundary between the protective layer 52 and the diaphragm 53, a short circuit preventing element electrode 81 and common electrode 82 is interposedAnd an insulating layer 54. The insulating layer 54 is made of, for example, a silicon dioxide film (SiO) having a thickness of 0.5 μm2) And (4) forming. The lower electrode 84 and the common electrode 82 are electrically connected through the contact hole 55 formed in the insulating layer 54. The piezoelectric body 85 is formed of PZT (lead zirconate titanate) having a thickness of 5 μm or less, for example, in consideration of piezoelectric characteristics and dielectric breakdown voltage. The upper electrode 86 and the lower electrode 84 are formed of, for example, platinum having a thickness of 0.15 μm. The individual electrodes 81 and the common electrode 82 are formed of, for example, gold (Au) having a thickness of 0.3 μm.
The vibration plate 53 is formed of an insulating inorganic material. The insulating inorganic material is, for example, silicon dioxide (SiO)2). The thickness of the diaphragm 53 is, for example, 2 to 10 μm, preferably 4 to 6 μm. The diaphragm 53 and the protective layer 52 are subjected to d with the piezoelectric body 85 to which a voltage is applied31The pattern deforms to bend inward. When the voltage application to the piezoelectric body 85 is stopped, the state is restored. By this reversible deformation, the volume of the pressure chamber (monomer pressure chamber) 41 expands and contracts. When the volume of the pressure chamber 41 is changed, the ink pressure in the pressure chamber 41 is changed. The ink is discharged from the nozzle 51 by the expansion and contraction of the volume of the pressure chamber 41 and the change in ink pressure. That is, the nozzle 51 and the actuator 8 constitute an example of the liquid ejecting section.
The protective layer 52 is formed of polyimide having a thickness of 4 μm, for example. The protective layer 52 covers the bottom surface of the nozzle plate 5, and further covers the inner circumferential surface of the hole of the nozzle 51.
Fig. 6 is a block diagram of the configuration of the control system of the inkjet printer 10. The control system of the ink printer 10 is constituted by a print control apparatus 100 as a control unit of the printer and a head drive circuit 7. The head drive circuit 7 is an example of an actuator drive circuit. The print control apparatus 100 includes a CPU101, a storage unit 102, an image memory 103, a head interface 104, and a conveyance interface 105. The print control device 100 is mounted on the control board 17, for example. The storage unit 102 is, for example, a ROM (read only memory), and the image memory 103 is, for example, a RAM (random access memory). The image data from the computer 2 as an external connection device is transmitted to the print control apparatus 100 and stored in the image memory 103. The CPU101 reads image data from the image memory 103, converts the image data in accordance with the data format of the inkjet heads 1A to 1D, and transmits the converted image data to the head interface 104 as print data. The print data is an example of liquid ejection data. The head interface 104 sends print data and other control instructions to the head drive circuit 7. Although not shown, the head driving circuits 7 of the other ink jet heads 1B to 1D have the same circuit configuration.
The conveyance interface 105 controls the conveyance device 106 (the conveyance belt 14, the drive motor 24, and the like) to convey the sheet S in accordance with instructions from the CPU101, detects the relative positions of the sheet S and the inkjet heads 1A to 1D by a position sensor (not shown) such as an optical encoder, and transmits the timing at which the ink of each nozzle 51 should be ejected to the head interface 104. The head interface 104 sends the ejection timing to the head drive circuit 7 as a print trigger. The print trigger is one of control instructions sent to the head drive circuit 7.
In the head drive circuit 7, the actuator power supply is applied to the voltage V0 as the first voltage, the voltage V1 as the second voltage, and the voltage V2 as the third voltage. As an example, the voltage V1 is a dc voltage of 30V, the voltage V2 is a dc voltage of 10V, and the voltage V0 is a dc voltage of 0V (V1> V2> V0). The magnitudes of the voltage Vl and the voltage V2 are adjusted by a power supply circuit not shown, for example, in accordance with the ink viscosity and temperature.
The head drive circuit 7 includes a receiving unit 71, a command analyzing unit 72, a waveform generating unit 73, a print data buffer 74, a waveform selecting unit 75, and an output buffer 76. The output buffer 76 is an example of an output switch. The receiving unit 71 receives data from the print control apparatus 100 and transmits the data to the command analyzing unit 72. The command analysis unit 72 analyzes the received data. As shown in fig. 7 in detail, the command analysis unit 72 includes a waveform setting information extraction unit 200, a print trigger extraction unit 201, a Sleep (Sleep) command extraction unit 202, a Wake (Wake) command extraction unit 203, a print data extraction unit 204, and a print data transmission unit 205. The command analysis unit 72 analyzes and extracts whether the received data is waveform setting information, a print trigger, a wake-up command, a sleep command, or print data. Of course, instructions other than these are also possible. The data from the print control apparatus 100 is transmitted in units of packets by the information and the command. A plurality of instructions are sometimes included in one packet.
After the analysis, the waveform setting information is sent to the waveform generating unit 73. The print trigger is sent to both the waveform generation section 73 and the print data buffer 74. The print trigger sent to the waveform generating section 73 becomes a start signal for executing waveform generation. The print trigger transmitted to the print data buffer 74 is a buffer update signal for transferring data from the input side to the output side in the print data buffer 74. The print data, the wakeup command, and the sleep command are transmitted to the print data transmitting unit 205.
The print data transmitting portion 205, upon receiving the print data from the print data extracting portion 204, transmits the data to the print data buffer 74. The print data is, for example, multi-bit gray scale data. The gradation data indicates, for example, whether or not ejection is performed, the amount of ejection during ejection, and other operations, as gradation values of 0 to 7. For example, the gray level value 0 is the maintenance of the bias voltage application, the gray level value 1 is one drop, the gray level value 2 is two drops, the gray level value 3 is three drops, the gray level value 4 is four drops, the gray level value 5 is awake, the gray level value 6 is Sleep, and the gray level value 7 is Sleep hold (Sleep hold). In addition, when the printing control device 100 is provided with a multi-channel repeat head composed of a combination of the nozzle 51 and the actuator 8, the gray-scale value is individually allocated to each channel to be 0 to 7.
On the other hand, when the print data transmitting unit 205 receives the wake-up command from the wake-up command extracting unit 203, it transmits the grayscale value 5 defined as wake-up data to all the actuators 8 (collectively wake-up). When the sleep command is received from the sleep command extracting unit 202, the print data transmitting unit 205 transmits the grayscale value 6 defined as the sleep data to all the actuators 8 (collectively sleep). That is, the wake-up command is assigned to the gray scale value 5, which is one of the gray scale values 0 to 7 of the gray scale data, and the sleep command is assigned to the gray scale value 6. Likewise, a maintenance sleep is assigned to the gray level 7.
That is, as a method of transmitting the wakeup data to the print data buffer 74, two methods, that is, a method of transmitting the encoded print data and a method of transmitting the wakeup command, are prepared. The former may wake up only the designated actuator 8, and the latter may wake up all the actuators 8 together. Similarly, as a method of transmitting the sleep data to the print data buffer 74, two methods, that is, a method of transmitting the encoded print data and a method of transmitting the encoded print data as a sleep command, are prepared. The former may sleep only the designated actuator 8, and the latter may sleep all the actuators 8 together.
Next, as shown in fig. 8 in detail, the waveform generation unit 73 includes waveform generation circuits 300 to 306 and a WG register storage unit 307. The waveform generation circuits 300 to 306 and the WG register storage part 307 generate encoded drive voltage waveforms WK0 to WK7 corresponding to the respective grayscale values 0 to 7 using WG registers showing information of the drive voltage waveform for one frame. The information of the drive voltage waveform of one frame is represented by, for example, a state value and a timer value.
Waveform generation circuits 300 to 304 corresponding to gray scale values 0 to 4 among gray scale values 0 to 7 allocate a plurality of types of WG registers representing different pieces of information of drive voltage waveforms to 4 frames F0 to F3 arranged in time series, thereby generating encoded drive voltage waveforms WK0 to WK4 corresponding to the gray scale values 0 to 4. The waveform generation circuits 300 to 304 are examples of discharge waveform generation sections that apply drive voltage waveforms for discharging ink to the actuator 8. The waveform generation circuit 300 corresponding to the grayscale value 0 includes a WGG register 400, a frame counter 401, a selector 402, a selector 403, a status unit 404, and a timer 405. Although only the circuit configuration of the waveform generation circuit 300 is shown, the waveform generation circuits 301 to 304 have the same circuit configuration. The WGG register 400 sets which one of the WG registers is allocated to the 4 frames F0 to F3. That is, the WGG register 400 is a waveform setting unit that sets a drive voltage waveform used for each gray-scale value. Which WG register is allocated to each of the 4 frames F0 to F3 of the WGG register 400 differs depending on the gray-scale value. That is, the WGG register 400 and the WG register 307 as the waveform setting unit are examples of a waveform memory that constitutes a plurality of groups in which drive voltage waveforms and holding voltages described later are stored.
The frame counter 401 selects frames in the order of F0, F1, F2, and F3. The selector 402 selects the WG register allocated to the frame selected by the frame counter 401 based on the setting of the WG register 400. The selector 403 sets the values of the state unit 404 and the timer 405 based on the state value of the selected WG register and the timer value. The state value and the timer value of each WG register are received from the WG register storage unit 307. The timer 405 counts the set time, and the state unit 406 updates the state when the timer 405 counts the time.
The waveform generation frequency paths 305 and 306 corresponding to the gradation value 5 of the wake-up data and the gradation value 6 of the sleep data include state units 406 and 408 and timers 407 and 409. Unlike the grayscale values 0 to 4, the waveform generation circuits 305 and 306 generate the encoded drive voltage waveforms WK5 and WK6 corresponding to the wake-up and the sleep, respectively, without using a frame. Similarly, the gray-scale value 7 corresponding to the sleep data generates the encoded drive voltage waveform WK7 without using a frame. The waveform generation circuit 305 is an example of a wake-up waveform generation unit that shifts the voltage of the actuator 8 to the voltage V1 without discharging ink, and the waveform generation circuit 306 is an example of a sleep waveform generation unit that shifts the voltage of the actuator 8 to the voltage V0 without discharging ink.
The WG register storage section 307 stores a plurality of WG registers. Fig. 9 shows an example of the WG register and its setting value. In this example, 5 kinds of WG registers GW, GS, G0, G1, G2 are used. Each GW register shows information of a drive voltage waveform for one frame based on 9 state values of S0 to S8 and 8 timer values of t0 to t7, which are settings of timing of execution states. The state values are, for example, 0, 1, 2, and 3. The state value 0 indicates that the first output switch that applies the voltage V0 as the first voltage to the actuator 8 is turned on, the state value 1 indicates that the second output switch that applies the voltage V1 as the second voltage to the actuator 8 is turned on, and the state value 2 indicates that the third output switch that applies the voltage V2 as the third voltage to the actuator 8 is turned on. The state value 3 indicates that all of the first to third output switches are turned off and that the drive circuit output is set to high impedance. Each output switch is, for example, a transistor (see fig. 12).
The state of the state S0 is held for a time t0, and then the state becomes the state S1. The state of the state S1 is held for a time t1, and then the state becomes the state S2. The state of the state S2 is held for a time t2, and then the state becomes the state S3. The state of the state S3 is held for a time t3, and then the state becomes the state S4. The state of the state S4 is held for a time t4, and then the state becomes the state S5. The state of the state S5 is held for a time t5, and then the state becomes the state S6. The state of the state S6 is held for a time t6, and then the state becomes the state S7. The state of the state S7 is held for a time t7, and then the state becomes the state S8. State S8 has no hold time. The state of the holding state S8 is held until the update to the next frame, or the next print trigger occurs. That is, the voltage set to the last state S8 is the holding voltage. When the first to third transistors Q0, Q1, and Q2, which will be described later, are used for the output buffer 76, the on/off state to be held is determined. That is, information of a plurality of types of drive voltage waveforms different from each other in the transistor which is turned on last is stored in the WG register storage 307 which is an example of a waveform memory. Of course, the coded drive voltage waveforms WK0 through WK6 themselves may be stored in the waveform memory.
The state values and timer values of the WG registers GW, GS, G0, G1, and G2 are transmitted from the WG register storage unit 307 to the waveform generation circuits 300 to 306 that generate the encoded drive voltage waveforms WK0 to WK 6. The waveform generation circuits 300 to 306 generate encoded drive voltage waveforms WK0 to WK6 based on the state values of the WG registers and the timer values. WK7 is the final state of GS S8. The print trigger is a trigger for starting generation of the encoded drive voltage waveforms WK0 to WK 7. For example, when a print trigger signal is input, the waveform generation circuits 300 to 304 corresponding to the grayscale values 0 to 4 read the state values of the WG register and the timer value based on the setting of the WG register 400, output the state values corresponding to the time of the timer value to the encoded drive voltage waveforms WK0 to WK4, and repeat the state values for all frames F0 to F4.
Fig. 10 shows encoded drive voltage waveforms WK0 to WK7 generated by the distribution and generation of WG registers GW, GS, G0, G1, and G2 for gray-scale values 0 to 7, respectively. As shown in fig. 10, in the encoded drive voltage waveform WK0 corresponding to the grayscale value 0, the value of the WG register G0 is output for the period from F0 to F3, and the final value is held. All the state values of G0 are "1", and therefore, the voltage V1 is output during this period. In the encoded drive voltage waveform WK1 corresponding to the gray level value 1 at which ink is dropped once, the value of the WG register G1 is output during the period F0, the value of G0 is output during the periods F1 to F3, and the final value is held. In the encoded drive voltage waveform WK2 corresponding to the gray level value 2 of two drops of ink, the value of the WG register G1 is repeatedly output for periods F0 to F1, the value of G0 is output for periods F2 to F3, and the final value is held. In the encoded drive voltage waveform WK3 corresponding to the gray-scale value 3 of three times the ink is dropped, the value of the WG register G1 is repeatedly output for the periods F0 to F2, the value of G0 is output for the period F3, and the final value is held. In the encoded drive voltage waveform WK4 corresponding to the gray scale value 4 of four times of ink drop, the value of the WG register G1 is repeatedly output during the periods F0 to F3, the value of G2 is output at the end of F3 (state S8), and the final value is held. The state of state S8 is maintained until, for example, the next print trigger occurs. That is, the voltage set in the last state S8 is the holding voltage to which the drive voltage waveform is applied. The holding voltage can be set and changed by the printing control apparatus 100, for example.
The gray- scale values 5, 6, and 7 do not use frames, and the WGG register 400 is not set, and the operation of generating waveforms is different from the gray-scale values 0 to 4. The value of the WG register GW is output to the encoded drive voltage waveform WK5 corresponding to the grayscale value of 5, and the final value is held. The value of the WG register GS is output to the encoded drive voltage waveform WK6 corresponding to the grayscale value of 6, and the final value is held. The value of the state S8 of the WG register GS is output and held in the encoded drive voltage waveform WK7 corresponding to the grayscale value of 7. The state of state S8 is maintained until, for example, the next print trigger occurs. The encoded drive voltage waveforms WK0 to WK7 thus generated are respectively given to the selected inputs of the waveform selection units 75. In this example, setting values transmitted from the print control apparatus 100 in accordance with the waveform setting information command are set in the WG register and the WGG register 400. Of course, the setting values of the WG register and the WGG register 400 may be fixed values, but may be set by the print control apparatus 100, which has the following advantages.
That is, the ink-jet heads 1A to 1D do not hold detailed information about the ink. This is because it is not always clear how to change the drive voltage waveform when the ink is changed or when the temperature of the ink is changed, and if detailed information on the ink is fixed to the individual inkjet heads 1A to 1D, it is impossible to cope with, for example, a new ink or a new required drive condition. The ink jet heads 1A to 1D are not equipped with a normal display and an input panel, and are not directly connected to a host computer. In contrast, the print control apparatus 100, which is a control unit of the printer, may be provided with a display, such as the operation unit 18, and an input panel, and may have an interface to a host computer in many cases. Therefore, for example, characteristics of ink are input using a display and an input panel, or from a host, and a driving electric pressure waveform can be set accordingly. Therefore, detailed information on the ink is not held by the inkjet heads 1A to 1D, but held by the print control device 100, and setting the values of the WG register, the WG register 400, and the like based on the information can be used under wider conditions and a printer with greater flexibility can be obtained.
Returning to fig. 6, the print data buffer 74 is composed of an input side buffer for storing data transmitted from the print data transmitting unit 205 and an output side buffer for transmitting the data to the waveform selecting unit 75. Each buffer has a capacity for storing data of a gray scale value of each channel by the number of channels. When a print trigger is given to the print data buffer 74, the print data in the input buffer is transferred to the output buffer.
As shown in fig. 11, the waveform selection section 75 includes a selector 500, a decoder 501, and a signal trouble removal/dead time generation circuit 502. As shown in the circuit diagram of fig. 12 (a), the output buffer 76 includes: a first transistor Q0 that gives a voltage V0 to the actuator; a second transistor Q1 that gives a voltage V1 to the actuator; and a third transistor Q2(Q2p and Q2n) that gives a voltage V2 to the actuator.
As shown in fig. 11, print data is given to the selected input of the waveform selection unit 75. The print data given to the waveform selection unit 75 is a 3-bit signal having a value of 0 to 7. The values of 0-7 correspond to gray scale values of 0-7. The selector 500 of the waveform selection unit 75 selects one encoded drive voltage waveform from among the encoded drive voltage waveforms WK0 to WK7 according to the values of 0 to 7 of the print data. The encoded drive voltage waveform is a 2-bit signal stream having a value of 0 to 3. The 2-bit signal has a state value of 0 to 3 as shown in fig. 12 (b), such as "one of a first transistor Q0 for applying a voltage V0 to the actuator, a second transistor Q1 for applying a voltage V1 to the actuator, and a third transistor Q2(Q2p and Q2n) for applying a voltage V2 to the actuator is turned on or off. The state value corresponds to the state value of the WG register. The signals decoded by the decoder 501 are a0in, a1in, a2 in.
The signal malfunction generated at the time of decoding is removed by the signal malfunction removal/dead time generation circuit 502. At the same time, the signal failure removal/dead time generation circuit 502 generates signals a0, a1, a2in which dead time for turning off all the transistors is inserted once at the timing of switching on the transistors Q1, Q2(Q2p, Q2n), Q0. The signals a0, al, a2 are sent to the output buffer 76. When the signal a0 is "H" (high level), the first transistor Q0 is turned on, and a voltage V0(═ 0V) is applied to the actuator 8. When the signal a1 is "H", the second transistor Q1 is turned on, and the voltage V1 is applied to the actuator 8. When the signal a2 is "H", the third transistor Q2(Q2p, Q2n) is turned on, and the voltage V2 is applied to the actuator 8. When all of the signals a0, a1, and a2 are "L" (low level), all of the first to third transistors Q0, Q1, and Q2(Q2p and Q2n) are turned off, and the terminals of the actuator 8 have high impedance. Two or more of the signals a0, a1, a2 do not become "H" at the same time.
Fig. 13 shows a series of drive voltage waveforms applied to the actuator 8 for a series of printing operations. The print cycle was 20 mus. In the initial state, a voltage of 0V is applied to the actuator 8. Before printing, the printing control apparatus 100 issues a wake-up command (grayscale value 5) to wake up all the actuators 8 at once and a print trigger. The waveform selection unit 75 selects the coded drive voltage waveform WK5 from the coded drive voltage waveforms WK0 to WK7, and the output buffer 76 controls on/off of the first to third transistors Q0, Q1, and Q2(Q2p and Q2n), and applies a wake-up voltage waveform conforming to the coded drive voltage waveform WK5 to the actuator 8. Thereby, the voltage applied to the actuator 8 is increased from the voltage V0 to the voltage V1. I.e. from a first voltage to a second voltage (first voltage < second voltage). When the voltage rises to the voltage V1 due to the wake-up, ink is not ejected. Therefore, the cancellation of the pressure vibration is realized while suppressing the pressure amplitude at the voltage rise, and a step of setting the voltage to the voltage V2 is provided for the first 2 μ s in the wake-up voltage waveform. 2 mus is the half period of the pressure oscillation. The half-cycle of the pressure oscillation is also referred to as AL (AcousticLength: pressure oscillation).
Then, the printing control apparatus 100 sequentially issues printing data (gradation values 1 to 4) and a printing trigger, and applies n (n ≧ 1) driving voltage waveforms to the actuators 8 of the nozzles 51 that discharge ink. However, as shown in fig. 13, two or more print cycles (20 μ s in this example) are secured for the time from the wake-up to the first printing. The time of 2 cycles or more can be secured by time adjustment of issuing the next print trigger, or by issuing print data (gray-scale value 0) and print trigger subsequently and continuing to apply the voltage V1. The reason why the bias voltage is applied before printing by securing a time of two or more cycles of the drive voltage waveform from the wake-up to the first printing will be described with reference to fig. 14 to 15.
When a bias is applied to the actuator 8, the polarization of the actuator 8 changes. At this time, if the application time of the bias before printing is short, printing starts before the change in polarization is saturated, and therefore the piezoelectric constant appears high only at the first dot of printing, and the print to start printing becomes thick in the example shown in fig. 14. That is, a problem of deterioration in print quality is caused.
In order to examine this phenomenon, the actuator 8 was driven with a voltage waveform shown in fig. 15 (a), and a change in the capacitance of the actuator 8 was examined. The drive voltage waveform for ejecting ink is an encoded drive voltage waveform WK4 in which ink is dropped 4 times as 1 dot. 2 mus is the half period of the pressure oscillation. The results are shown in fig. 15 (b). As is clear from the result of fig. 15 (b), the change in capacitance is not saturated even if a bias voltage is applied for a period of 20 μ s (i.e., 1 cycle of the print cycle) before the drive voltage waveform for ejecting ink is applied. If a bias is applied for a total period of 100 μ s (5 cycles of the printing cycle) before and after the discharge, the capacitance decreases, and therefore the capacitance at the second and subsequent dots becomes stable. However, when the bias is stopped and temporarily left, the electrostatic capacitance is restored. This phenomenon is the cause of the printing phenomenon in which the first dots are darker as shown in fig. 14. Therefore, at least two cycles or more of the drive voltage waveform are ensured from the wake-up to the first printing, and the first point is suppressed from becoming rich. More preferably, 5 cycles or more corresponding to 100. mu.s before and after the discharge are ensured in total. Since the print control apparatus 100 transmits both the wakeup command and the print data (grayscale value 5) to the head drive circuit 7, the time from the wakeup to the first printing can be freely adjusted.
In the example of fig. 13, after applying a wake-up voltage waveform to the actuator 8 and applying a voltage V1 as a bias voltage (2 periods of the total print period equal to or more than 40 μ s), print data ( grayscale values 1, 2, 3, and 4) and print triggers 2 to 5 are sequentially issued from the print control apparatus 100, and 4-dot printing is performed in the order of grayscale values 1, 2, 3, and 4. Then, the print control apparatus 100 sequentially issues the print data (gray-scale value 0) and the print triggers 6 to 7, and the voltage V1 is applied to the actuator 8 to stop the temporary printing in this state. During which the voltage V1 is maintained. In this example, the voltage V1 is maintained for 4 cycles (═ 80 μ s) of the print cycle. Next, the print control apparatus 100 issues the print data (gradation values 1, 2, 3, and 4) and the print triggers 9 to 12 in this order again, and prints 4 dots in the order of the gradation values 1, 2, 3, and 4. After that, the print control apparatus 100 issues the print data (gray-scale value 0) and the print trigger 13 and applies the voltage V1 to the actuator 8.
When a series of printing operations are completed, the printing control apparatus 100 issues a sleep command (grayscale value 6) and a print trigger 14. When the sleep command is executed, the waveform selection unit 75 selects the coded drive voltage waveform WK6 from the coded drive voltage waveforms WK0 to WK7, and the output buffer 76 controls on/off of the first to third transistors Q0, Q1, and Q2(Q2p and Q2n), and supplies the sleep voltage wave following the coded drive voltage waveform WK6 to the actuator 8. The applied voltage of the actuator 8 drops from the voltage V1 to the voltage 0V. That is, from the second voltage to the first voltage (first voltage < second voltage). When the voltage drops to the voltage V0 due to the sleep, ink is not ejected. The cancellation of the pressure oscillation is realized while suppressing the pressure amplitude at the time of the voltage drop, and a step of setting the voltage to V2 is provided for the first 2 μ s in the sleep waveform. 2 mus is the half period of the pressure oscillation. Thereafter, the voltage V0 is maintained until the next print trigger is input.
In another example shown in fig. 16, a sleep is set between the printing of the first 4 dots and the printing of the next 4 dots and the application of bias is stopped. Since the printing control apparatus 100 has a buffer area of a plurality of lines unlike the inkjet heads 1A to 1D, information that has been ejected or not ejected before that is present in the plurality of lines. Therefore, the print control apparatus 100 can determine whether to perform subsequent printing immediately after several lines or to temporarily stop ejection even after several tens or hundreds of lines. If it is determined that several hundred lines or more have not been discharged before, the print control apparatus 100 issues a sleep command (gray scale value 6) and a print trigger 7. By performing the sleep, the voltage applied to the actuator 8 temporarily becomes the voltage V0(═ 0V). It is preferable to secure two or more print cycles (20 μ s in this example) from the time of the sleep maintenance voltage V0(═ 0V).
After that, the printing control apparatus 100 issues the wake-up command (gray-scale value 5) and the print trigger 8 before the next ejection by 2 cycles (40 μ s) or more ahead of the printing cycle. The voltage applied to the actuator 8 by the wake-up voltage waveform is raised to a voltage V1 and applied as a bias maintaining voltage V1. By ensuring the application time of the pre-ejection bias voltage for two or more periods of the printing cycle, the first dot of the subsequent ejection can be prevented from becoming dense, and good printing quality can be obtained.
In addition, although the above example performs the batch wake-up and batch sleep according to the command, even if the wake-up data (the gray scale value 5) and the sleep data (the gray scale value 6) are included in the print data and the wake-up and sleep are performed on the actuator 8 alone, the first dot can be prevented from being thickened in the same manner, and good print quality can be obtained.
As described above, according to the above embodiment, the application of the bias voltage to the electrostatic capacitive actuator can be stopped, and the characteristics of the actuator when the liquid is subsequently discharged can be stabilized.
Next, a modification of the setting values of the awake WG register GW and the sleep WG register GS will be described with reference to fig. 17. As shown in fig. 17, the WG register GW sets a state value 3 for turning off all of the first to third transistors Q0, Q1, and Q2 at both the rise of the voltage waveform from the voltage V0 to the voltage V2 and the rise of the voltage waveform from the voltage V2 to the voltage V1. In the figure, the "Hi-Z" is used. Specifically, after the third transistor Q2 is turned on and the charging of the actuator 8 is started, state 3 is inserted for a predetermined time (for example, 0.1 μ s) from the time when a predetermined time (for example, 0.1 μ s) shorter than the time required for the completion of the charging operation has elapsed from the start of the rise of the voltage waveform to the voltage V2, and the third transistor Q2 is turned off. When the predetermined time elapses, the third transistor Q2 is turned off again. After that, the second transistor Ql is turned on, and at the time when a predetermined time (for example, 0.1 μ s) shorter than the time required for completion of the charging operation has elapsed from the start of the rise of the voltage waveform to the voltage Vl, the state 3 is inserted for a predetermined time (for example, 0.1 μ s), and the second transistor Q1 is turned off. After that, when the predetermined time elapses, the second transistor Q1 is turned on again. Thus, the rise time of the voltage is extended by inserting state 3. Since rising charging and falling discharging of the voltage waveform require several hundred nanoseconds, the rise time is adjusted by changing to the state value 3 in time. By adjusting the rise time of the wake-up voltage waveform in this manner, unnecessary ink ejection during driving with the wake-up voltage waveform is less likely to occur.
Similarly, the WG register GS also sets the state value 3 for turning off all of the first to third transistors Q0, Q1, and Q2 at both the fall of the voltage waveform from the voltage V1 to the voltage V2 and the fall of the voltage waveform from the voltage V2 to the voltage V0. In the figure, the "Hi-Z" is used. Specifically, after the third transistor Q2 is turned on and the discharge of the actuator 8 is started, state 3 is inserted for a predetermined time (for example, 0.1 μ s) from the time when the voltage waveform of the voltage V2 falls and the predetermined time (for example, 0.1 μ s) shorter than the time required for the completion of the discharge operation elapses, and the third transistor Q2 is turned off. When the predetermined time elapses, the third transistor Q2 is turned on again. Next, the first transistor Q0 is turned on, and at a point in time when a predetermined time (for example, 0.1 μ s) shorter than the time required for completion of the discharge operation has elapsed from the start of the fall of the voltage waveform to the voltage V0, the state 3 is inserted for a predetermined time (for example, 0.1 μ s), and the first transistor Q0 is turned off. After that, when the predetermined time elapses, the first transistor Q0 is turned on again. Thus, the fall time of the voltage is extended by inserting state 3. By adjusting the fall time of the rest voltage waveform in this manner, unnecessary ink ejection during driving with the rest voltage waveform is less likely to occur.
Another modification of the setting values of the awake WG register GW and the sleep WG register GS will be described with reference to fig. 18. In the case where the section in which ink is not ejected continues in the printing illustrated in fig. 16, the voltage applied to the actuator 8 is lowered to the voltage V0 (>0V) to completely go to rest, and instead, in this modification, the voltage applied to the actuator 8 is lowered to the voltage V2(>0V) to stand by. That is, a low voltage wake state (dark wake) is set. Therefore, the state value 2 is set to all the states S0 to S8 of the WG register GW. I.e., fixed to voltage V2. On the other hand, the state value 0 is set to all the states S0 to S8 of the WG register GS. I.e., fixed to voltage V0. Since the voltage is fixed, the set values of the timers t0 to t7 may be arbitrary values.
Fig. 19 shows an example of the distribution of the WG registers GW, GS, G0, G1, and G2 and the generated encoded drive voltage waveforms WK0 to WK7 for the gray-scale values 0 to 7 when the WG registers GW and GS shown in fig. 18 are used. As shown in fig. 19, the coded drive voltage waveform WK5 corresponding to the grayscale value 5 is in a low-voltage wake-up state in which the voltage V2 is applied to the actuator 8 over the entire time range, and the coded drive voltage waveform WK6 corresponding to the grayscale value 6 is in a sleep state in which the voltage V0(═ 0V) is applied to the actuator 8 over the entire time range. Therefore, in the encoded drive voltage waveform WK5 corresponding to the grayscale value 5, the value of the WG register GW (voltage V2) is output, and the final value is held. In the encoded drive voltage waveform WK6 corresponding to the grayscale value of 6, the value of the WG register GS (voltage V0) is output, and the final value is held. When the sleep is maintained without using the grayscale value of 7, the encoded drive voltage waveform WK6 of grayscale value of 6 is used. The gray scale values 0 to 4 are the same as those in the example shown in FIG. 10.
Fig. 20 shows a series of drive voltage waveforms applied to the actuator 8 for a series of printing operations. The print cycle was 20 mus. In the initial state, a voltage of 0V is applied to the actuator 8. Before printing, if a wake-up command (grayscale value 5) and a print trigger 1 are issued from the print control apparatus 100, the waveform selection unit 75 selects the encoded drive voltage waveform WK5, and the voltage applied to all the actuators 8 rises from the voltage V0 to the voltage V2. Namely, the low-voltage wake-up state is achieved. After that, when the print control apparatus 100 issues print data (gray-scale value 0) and a print trigger 2 to the actuator 8 that performs ejection, for example, the waveform selection unit 75 selects the encoded drive voltage waveform WK0, and the voltage applied to the actuator 8 rises from the voltage V2 to the voltage V1. That is, the wake-up voltage waveform is applied and the bias voltage is applied. After that, the print data (gray-scale value 0) and the print trigger 3 are issued from the print control apparatus 100 again. As a result, the application time of the pre-ejection bias is secured for two or more print cycles, and the characteristics of the actuator 8 are stabilized.
Thereafter, the print control apparatus 100 issues print data (grayscale value 4) and a print trigger 4, and performs 1-dot printing at the grayscale value 4. If there is no next ejection, the print control apparatus 100 issues the print data (grayscale value 0) and the print trigger 5, and then at the timing when it is determined that there is no next ejection temporarily, the print control apparatus 100 issues, for example, a wake-up command (grayscale value 5) and a print trigger 7. As the print data, a gray-scale value of 5 may be given. The waveform selection unit 75 selects the coded drive voltage waveform WK5, and the voltage applied to the actuator 8 drops from the voltage V1 to the voltage V2, thereby turning into the low-voltage wake-up state. At the timing of the print cycle 2 cycles earlier than the restart of the ejection, the print control apparatus 100 issues the print data (gray-scale value 0) and the print trigger 10. The waveform selection unit 75 selects the coded drive voltage waveform WK0, and the voltage applied to the actuator 8 rises from the voltage V2 to the voltage V1. That is, a bias voltage is applied. After that, the print data (gray-scale value 0) and the print trigger 11 are issued from the print control apparatus 100 again. As a result, the application time of the pre-ejection bias is maintained for two or more print cycles, and the characteristics of the actuator 8 are stabilized.
After that, the print control apparatus 100 issues the print data (grayscale value 1) and the print trigger 12 to perform printing of 1 dot at the grayscale value 1. In the next printing cycle, print data (gradation value 4) and a print trigger 13 are sent from the print control apparatus 100, and 1 dot printing is performed at the gradation value 4. Thereafter, the print control apparatus 100 issues print data (gray-scale value 0) and a print trigger 14, and applies a voltage V1 to the actuator 8. If it is determined at this point that the ink has not been ejected for a while, the print control apparatus 100 issues a wake-up command (gray level 5) and a print trigger 15, and lowers the voltage applied to the actuator 8 to the voltage V2. In the next printing cycle, a sleep command (gray-scale value 6) and a print trigger 16 are issued, and the voltage applied to all the actuators 8 is decreased to a voltage V0(═ 0V). Namely, the completely sleep state is established.
In the above-described embodiment, the ink jet heads 1A to 1D of the ink jet printer 1 have been described as an example of the liquid ejecting apparatus, but the liquid ejecting apparatus may be a modeling material ejecting head of a 3D printer or a sample ejecting head of a dispensing apparatus. Of course, the actuator 8 is not limited to the configuration and arrangement of the above embodiment as long as it has a capacity load.
That is, the actuator driving circuit of the liquid ejecting apparatus according to the embodiment includes:
(1) an output switch, the output switch comprising: a first transistor that applies a first voltage to the actuator; and a second transistor that applies a second voltage larger than the first voltage to the actuator and performs an on/off operation according to a drive voltage waveform; and
and a waveform memory configured to set the drive voltage waveform according to setting of a state in which only the first transistor is turned on, only the second transistor is turned on, or both the first transistor and the second transistor are turned off, and setting of a timing for executing the states, and to store a plurality of types of drive voltage waveforms different from each other at least in a transistor which is turned on last.
(2) Further provided with: a third transistor that applies a third voltage, which is larger than the first voltage and smaller than the second voltage, to the actuator,
the waveform memory sets the drive voltage waveform according to setting of states in which only the first transistor is turned on, only the second transistor is turned on, only the third transistor is turned on, or all of the first transistor, the second transistor, and the third transistor are turned off, and setting of timings for executing these states, and stores a plurality of types of the drive voltage waveforms in which at least transistors that are turned on last are different from each other.
(3) Comprising the following drive voltage waveforms: after the second transistor is turned on to start charging the actuator, the second transistor is turned off after a first predetermined time shorter than a time required for completion of the charging operation has elapsed, and the second transistor is turned on again after a second predetermined time has further elapsed.
(4) Comprising the following drive voltage waveforms: after the first transistor is turned on and discharge from the actuator is started, the first transistor is turned off after a third predetermined time shorter than a time required for completion of the discharge operation has elapsed, and the first transistor is turned on again after a fourth predetermined time has further elapsed.
(5) Comprising the following drive voltage waveforms: after the third transistor is turned on to start charging or discharging the actuator, the third transistor is turned off after a fifth predetermined time shorter than a time required to complete the charging operation or the discharging operation has elapsed, and the third transistor is turned on again after a sixth predetermined time has elapsed.
(6) The predetermined time is stored in the waveform memory as the setting of the timing.
(7) The first voltage is 0V.
(8) The setting of the state corresponding to the last timing of the drive voltage waveform determines the on/off state of the transistor held after the end of the drive voltage waveform.
The embodiments of the present invention have been presented by way of example only, and are not intended to limit the scope of the invention. These new embodiments can be implemented in other various ways, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.
