JP2006256190A - Circuit for driving liquid jetting head, and liquid jetting apparatus equipped with circuit for driving liquid jetting head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a liquid jetting apparatus low in consumption power and compact by a liquid jetting head driving circuit which can stably control jetting of a liquid correspondingly also to a plurality of liquid jetting controlling patterns of different driving voltages or the like of a capacitive load, and which less consumes power and less generates heat because of loss of power. <P>SOLUTION: A first switching transistor Q3 is set to be able to turn ON/OFF a charging course from a first constant voltage source Vdd to a collector of an NPN type transistor Q1. A second switching transistor Q4 is set to be able to turn ON/OFF a discharging course from a collector of a PNP type transistor Q2 to GND. A first control circuit 185 controls to turn ON/OFF the first switching transistor Q3 on the basis of a voltage between electrodes of a piezoelectric oscillator 77. A second control circuit 186 controls to turn ON/OFF the second switching transistor Q4 on the basis of the voltage between electrodes of the piezoelectric oscillator 77. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention includes an opening for ejecting liquid, a pressure generating chamber communicating with a common liquid chamber via a liquid supply path, and a capacitive load for expanding and contracting the pressure generating chamber by applying a potential difference between the electrodes. The present invention relates to a liquid ejecting head driving circuit for driving a liquid ejecting head in which a large number of nozzles having nozzles are arranged on a head surface, and a liquid ejecting apparatus including the liquid ejecting head driving circuit.

  Here, the liquid ejecting apparatus refers to an ink jet recording apparatus, a copying machine, a facsimile, or the like that performs recording on a recording material by ejecting ink from a recording head as a liquid ejecting head to a recording material such as recording paper. In addition to the recording apparatus, instead of ink, a liquid corresponding to a specific application is ejected from the liquid ejecting head corresponding to the recording head to the ejected material corresponding to the recording material, and the liquid is ejected to the ejected material. Used to include the device to be attached. In addition to the recording head described above, the liquid ejecting head includes a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an electrode material used for forming an electrode such as an organic EL display and a surface emitting display (FED) ( Examples thereof include a conductive paste) ejection head, a bio-organic matter ejection head used for biochip manufacturing, and a sample ejection head that ejects a sample as a precision pipette.

  As an example of a liquid ejecting head of a liquid ejecting apparatus typified by an ink jet recording apparatus that ejects ink from a recording head onto a recording surface of a recording paper to form dots and prints a digital image or the like on the recording surface of the recording paper. An opening for injecting liquid, a pressure generating chamber communicating with a common liquid chamber via a liquid supply path, and a piezoelectric vibrator (capacitive load) that expands and contracts the pressure generating chamber by applying a potential difference between the electrodes ) Are arranged on the head surface facing the material to be ejected. A piezoelectric vibrator used in a general liquid ejecting head expands and contracts by changing a potential difference between electrodes or a direction in which a current flows. The generation chamber is configured to expand and contract.

  For example, in a recording head such as an ink jet recording apparatus, a liquid ejecting head driving circuit for driving such a liquid ejecting head first outputs a digital control signal of a nozzle for expanding and contracting a pressure generating chamber. Convert to analog AC signal with a converter. Since the AC signal as it is is low in voltage, the piezoelectric vibrator cannot be directly driven. Therefore, an AC signal obtained by amplifying the amplitude voltage of the AC signal to about 42 V is applied between the electrodes of the piezoelectric vibrator. In general, the nozzle is driven.

  Specifically, in a known push-pull amplifier circuit that operates with a power supply voltage of DC 42 V, an analog AC signal that is DA-converted from the nozzle digital control signal is amplified to an AC signal with an amplitude of 0 to 42 V to Apply to electrode. The push-pull amplifier circuit is, for example, an amplifier circuit in which two class B amplifier circuits are combined. In a region where the voltage of the AC input signal is a positive voltage with reference to the bias voltage, only one class B amplifier circuit operates. In the region where the voltage of the AC input signal is a negative voltage with respect to the bias voltage, only the other class B amplifier circuit operates, and the outputs of both class B amplifier circuits are combined and output.

  When the AC signal voltage is higher than the bias voltage, the fluid pressure generating chamber expands. In the AC signal voltage lower than the bias voltage, the piezoelectric vibrator generates fluid pressure so that the fluid pressure generating chamber contracts. It is arranged near the room. When the hydraulic pressure generating chamber expands, ink is sucked from the ink cartridge into the hydraulic pressure generating chamber, and the hydraulic pressure generating chamber is contracted from that state, whereby the ink in the hydraulic pressure generating chamber is ejected from the nozzle opening of the nozzle. The That is, by applying an alternating current to the piezoelectric vibrator and repeating the expansion and contraction of the hydraulic pressure generating chamber, it is possible to eject ink from the nozzles continuously in the period of the alternating current signal.

  In the conventional liquid jet head driving circuit having such a circuit configuration, all the electric power necessary for charging and discharging the piezoelectric vibrator is supplied from a single power source to the piezoelectric vibrator, and according to the driving waveform of the piezoelectric vibrator. The electric charge of the piezoelectric vibrator is charged / discharged. Therefore, a large power loss occurs in the transistor of the push-pull amplifier circuit, and there is a problem that the power consumption of the liquid ejecting head driving circuit increases due to unnecessary power consumption caused by the large power loss. As a result, the heat-dissipating means such as a heat sink provided to protect the transistor from the heat loss due to power loss in the transistor of the push-pull amplifier circuit is increased in size. There was a problem that the apparatus would be enlarged.

  As an example of a conventional technique for solving such a problem, a capacitor is provided in addition to a power source as a charge supply source for the capacitive load (piezoelectric vibrator), and a part of the charge discharged from the capacitive load to the GND is obtained. A drive circuit for a capacitive load that is held in a capacitor and supplies the charge held in the capacitor again to the capacitive load is known (see, for example, Patent Document 1). That is, not all of the electric charge released from the capacitive load is released to the GND, but a part thereof is held in the capacitor and reused. Accordingly, power consumption of the power source can be reduced, and heat generation due to power loss in the transistors of the push-pull amplifier circuit can be reduced, and the heat sink can be downsized.

JP 2000-238264 A

  By the way, in the prior art disclosed in Patent Document 1, the circuit configuration is based on the premise that the potential of the capacitor is stable at a constant potential. However, if the liquid injection amount per one time from the liquid injection nozzle driven by the capacitive load (piezoelectric vibrator) is different, the drive pattern of the capacitive load (piezoelectric vibrator) is different, and the charge / discharge waveform is also different. Will be different. Therefore, the potential of the capacitor is displaced according to the amount of liquid injection per one time. For example, in an ink jet printer or the like, it is displaced with the size of the dot size (large dot, medium dot, small dot) formed on the recording surface of the recording paper. That is, the potential of the capacitor is displaced according to fluctuations in the drive voltage of the capacitive load (piezoelectric vibrator).

  However, in the prior art disclosed in Patent Document 1, since circuit constants (such as a Zener voltage of a Zener diode) are set on the assumption that the potential of the capacitor is constant at a predetermined potential, once When multiple patterns of liquid ejection control with different amounts of liquid ejection are performed, the potential of the capacitor does not become constant at a predetermined potential, and the drive waveform of the capacitive load (piezoelectric vibrator) becomes unstable. There is a possibility that stable liquid ejection cannot be performed in the head.

  The present invention has been made in view of such a situation, and the problem is that stable liquid ejection control can be executed in correspondence with a plurality of liquid ejection control patterns with different capacitive load driving voltages, and the like. In addition, a liquid jet head driving circuit that generates less heat due to power consumption and power loss realizes low power consumption and downsizing of the liquid jet apparatus.

  In order to achieve the above object, a first aspect of the present invention is to provide a potential difference between an opening for ejecting liquid, a pressure generating chamber communicating with a common liquid chamber via a liquid supply path, and an electrode. A liquid ejecting head driving circuit for driving a liquid ejecting head in which a plurality of nozzles having a capacitive load for expanding and contracting the pressure generating chamber are disposed on a head surface, and expanding the pressure generating chamber. Nozzle control signal generating means for outputting the nozzle control signal for sucking the liquid in the liquid chamber into the pressure generating chamber, contracting the pressure generating chamber, and ejecting the liquid in the pressure generating chamber from the opening; A first constant voltage source; a second constant voltage source capable of supplying constant voltage power having a voltage lower than the voltage of the first constant voltage source; the first constant voltage source; and the second constant voltage. And the power supplied from the source A capacitive load drive circuit that amplifies the amplitude voltage of the control signal to the drive voltage of the capacitive load and applies it between the electrodes of the capacitive load, and the first constant voltage source to the capacitive load drive circuit A switching control circuit having a configuration in which a charging path and a discharging path from the capacitive load driving circuit to GND can be independently turned ON / OFF based on an inter-electrode voltage of the capacitive load, and the switching control The circuit is configured to charge the capacitive load from the first constant voltage source to the capacitive load driving circuit while the voltage between the electrodes of the capacitive load is equal to or lower than the voltage of the second constant voltage source. And the charging path from the first constant voltage source to the capacitive load drive circuit is turned on while the voltage between the electrodes of the capacitive load exceeds the voltage of the second constant voltage source. And the capacitive negative When discharging the charge charged to the capacitor, the discharge path from the capacitive load drive circuit to GND is turned off while the voltage between the electrodes of the capacitive load exceeds the voltage of the second constant voltage source, and the capacitance In the liquid jet head driving circuit, the discharge path from the capacitive load driving circuit to the GND is turned on while the voltage between the electrodes of the capacitive load is equal to or lower than the voltage of the second constant voltage source.

  The capacitive load driving circuit charges and discharges the capacitive load with power supplied from two constant voltage sources, that is, a first constant voltage source and a second constant voltage source having a voltage lower than that of the first constant voltage source. The control is configured to be executable. In addition, the switching control circuit separates the charging path from the first constant voltage source to the capacitive load driving circuit and the discharging path from the capacitive load driving circuit to GND based on the interelectrode voltage of the capacitive load. It is configured to be able to be turned ON / OFF independently.

  Accordingly, the liquid ejection head is configured to perform the liquid ejection by configuring the switching control circuit so that the capacitive load driving circuit is charged and discharged based on the voltage between the electrodes of the capacitive load as follows. The electric power consumed by can be reduced.

  First, when charging the capacitive load, the charging path from the first constant voltage source to the capacitive load driving circuit is set while the voltage between the electrodes of the capacitive load is equal to or lower than the voltage of the second constant voltage source. Turn off. Thereby, electric power is supplied only from the second constant voltage source, and the capacitive load is charged. Since the voltage of the second constant voltage source is lower than that of the first constant voltage source, the power loss when charging the capacitive load is smaller than when charging only from the first constant voltage source. Therefore, it is possible to reduce the power and the amount of heat generated when charging the capacitive load.

  When charging the capacitive load, the charging path from the first constant voltage source to the capacitive load drive circuit is turned on while the voltage between the electrodes of the capacitive load exceeds the voltage of the second constant voltage source. To do. As a result, electric power is also supplied from the first constant voltage source to charge the capacitive load, so the inter-electrode voltage of the capacitive load is increased to the drive voltage with the electric power supplied from the first constant voltage source. Can be made.

  On the other hand, when discharging the charge charged in the capacitive load, the discharge path from the capacitive load drive circuit to GND is turned off while the voltage between the electrodes of the capacitive load exceeds the voltage of the second constant voltage source. . Thereby, the electric charge charged in the capacitive load is discharged to the second constant voltage source having a potential lower than the positive electrode potential of the capacitive load without being discharged to the GND. Since the positive electrode of the second constant voltage source is higher than the GND potential by the voltage of the second constant voltage source, the charge charged in the capacitive load is transferred from the positive electrode of the capacitive load to the positive electrode of the second constant voltage source. The power loss at the time of discharging becomes smaller than that of discharging to GND as it is. Therefore, it is possible to reduce the electric power and the amount of heat generated when electric charges are discharged from the capacitive load.

  When discharging the charge charged in the capacitive load, the discharge path from the capacitive load drive circuit to GND is turned on while the voltage between the electrodes of the capacitive load is equal to or lower than the voltage of the second constant voltage source. To do. Thereby, the interelectrode voltage of the capacitive load can be lowered to the GND potential.

  In this way, charge / discharge control of the capacitive load is executed with the power supplied from the two constant voltage sources, that is, the first constant voltage source and the second constant voltage source having a lower voltage than the first constant voltage source. A capacitive load drive circuit is configured as possible, and the charging path from the first constant voltage source to the capacitive load drive circuit and the capacitive load drive circuit to GND are based on the voltage between the electrodes of the capacitive load as described above. Each of the discharge paths is ON / OFF controlled independently by the switching control circuit. As a result, power consumption and heat generation due to power loss in the liquid ejecting head driving circuit can be reduced, so that power consumption can be reduced and heat dissipation means such as a heat sink can be reduced.

  In addition, the ON / OFF timing of the charging path from the first constant voltage source to the capacitive load driving circuit and the discharging path from the capacitive load driving circuit to GND by the switching control circuit is always maintained at a constant voltage. This is executed with reference to the voltage of the two constant voltage sources. Therefore, the voltage (the voltage of the second constant voltage source) serving as the timing of the switching control in the switching control circuit can always be a substantially constant voltage even when the drive voltage of the capacitive load changes. Therefore, the timing of the switching control in the switching control circuit can always be made constant regardless of the driving pattern of the capacitive load, the driving voltage, and the like, whereby stable liquid ejection control can always be executed.

As a result, according to the liquid jet head drive circuit according to the first aspect of the present invention, it is possible to always perform stable liquid jet control regardless of the capacitive load drive pattern, drive voltage, etc. There is obtained an effect that stable liquid ejection control can be executed in correspondence with a plurality of liquid ejection control patterns having different drive voltages or the like of the load.
In addition, the liquid ejecting head driving circuit that generates less heat due to power consumption and power loss enables lower power consumption of the liquid ejecting head driving circuit and downsizing of heat dissipation means such as a heat sink. The effect that electric power and size reduction can be realized is obtained.

  According to a second aspect of the present invention, in the first aspect, the capacitive load driving circuit is a push-pull amplifier circuit configured by a complementary SEPP circuit in which an NPN transistor and a PNP transistor are combined. The switching control circuit includes a first switching transistor arranged to be able to turn on / off a charging path from the first constant voltage source to the collector of the NPN transistor, and from the collector of the PNP transistor to GND. A second switching transistor disposed so as to be able to turn on / off the discharge path, and a switching transistor control circuit that performs on / off control of the first switching transistor and the second switching transistor. A liquid jet head driving circuit characterized by .

  In this way, the first switching transistor is disposed so that the charging path from the first constant voltage source to the collector of the NPN transistor can be turned ON / OFF, and the discharging path from the collector of the PNP transistor to GND is turned ON / OFF. By disposing the second switching transistor so that it can be turned off, the charging path from the first constant voltage source to the capacitive load drive circuit and the discharge path from the capacitive load drive circuit to GND are turned on independently of each other. / OFF.

  According to a third aspect of the present invention, in the second aspect described above, the current path is limited only in the charging direction in the charging path from the second constant voltage source to the capacitive load driving circuit. And a discharge diode disposed in a discharge path from the capacitive load driving circuit to the second constant voltage source so as to limit a current direction only in the discharge direction. This is a liquid ejecting head driving circuit.

  In this way, the first switching transistor is turned on by disposing the charging diode in the charging path from the second constant voltage source to the capacitive load driving circuit so as to limit the current direction only in the charging direction. In this case, it is possible to prevent a current from flowing directly from the first constant voltage source to the second constant voltage source. When the second switching transistor is turned on by disposing a discharge diode so as to limit the current direction only in the discharge direction in the discharge path from the capacitive load driving circuit to the second constant voltage source In addition, it is possible to prevent the positive electrode of the second constant voltage source from being directly connected to GND.

  According to a fourth aspect of the present invention, in the third aspect described above, the switching transistor control circuit includes a voltage obtained by subtracting a predetermined voltage Vd1 from the voltage of the second constant voltage source so that the interelectrode voltage of the capacitive load is The first control circuit that controls ON of the first switching transistor only during the above and the inter-electrode voltage of the capacitive load is equal to or lower than the voltage obtained by adding the predetermined voltage Vd2 to the voltage of the second constant voltage source. And a second control circuit that performs ON control of the second switching transistor only in the meantime.

Here, the predetermined voltage Vd1 is a total value of a voltage drop caused by the first switching transistor, the NPN transistor, and the charging diode, and a voltage change during the period from when the first switching transistor is turned on. The predetermined voltage Vd2 is a total value of the voltage drop of the second switching transistor, the PNP transistor, and the discharge diode and the voltage change during the period when the second switching transistor is turned on.
The switching transistor control circuit has a first control circuit that controls ON of the first switching transistor only while the voltage between the electrodes of the capacitive load is equal to or higher than the voltage obtained by subtracting the predetermined voltage Vd1 from the voltage of the second constant voltage source. is doing. That is, when the first control circuit increases the inter-electrode voltage of the capacitive load to the driving voltage, the first control circuit does not increase the voltage of the second constant voltage power source, which is decreased by the predetermined voltage Vd1 due to a voltage drop due to the semiconductor element. The voltage between the electrodes of the capacitive load is increased only by supplying power from the constant voltage source 2. After that, since the interelectrode voltage of the capacitive load cannot be further increased only by the power supply from the second constant voltage source, the first switching transistor is turned on to turn on the first constant voltage. Power is also supplied from the source to increase the interelectrode voltage of the capacitive load to the drive voltage.

  On the other hand, the switching transistor control circuit is a second control circuit that controls ON of the second switching transistor only while the voltage between the electrodes of the capacitive load is equal to or lower than the voltage obtained by adding the predetermined voltage Vd2 to the voltage of the second constant voltage source. have. That is, when the second control circuit discharges the electric charge charged in the capacitive load and lowers the positive potential of the capacitive load that has risen to the drive voltage to approximately the GND potential, the second control circuit may be caused by a voltage drop or the like caused by a semiconductor element. Until the positive potential of the second constant voltage power source increased by the predetermined voltage Vd2, the charge charged in the capacitive load is discharged only to the second constant voltage source to lower the positive potential of the capacitive load. After that, since the positive potential of the capacitive load cannot be further lowered by only discharging to the second constant voltage source, the second switching transistor is turned on to form a discharge path to GND. Then, the electric charge charged in the capacitive load is also discharged to GND, and the positive electrode potential of the capacitive load is lowered to approximately the GND potential.

  In this way, in consideration of a voltage drop or the like due to a semiconductor element constituting the circuit, charging to the capacitive load driving circuit (push-pull driving circuit) from the first constant voltage source (first switching transistor ON) and Discharge from the capacitive load drive circuit (push-pull drive circuit) to GND (second switching transistor ON) is limited to the minimum necessary, and the capacity is limited to only the second constant voltage source having a low voltage as much as possible. By performing charge / discharge of the capacitive load, power consumption and heat generation in the capacitive load drive circuit (push-pull drive circuit) can be further reduced.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects described above, the voltage of the second constant voltage source is approximately ½ of the voltage of the first constant voltage source. This is a liquid ejecting head driving circuit.
The power consumption during charging of the capacitive load can be reduced to approximately ½, and the power consumption during discharging from the capacitive load can also be reduced to approximately ½. That is, it is most efficient to set the voltage of the second constant voltage source to approximately ½ that of the first constant voltage source, thereby reducing the power consumption and the heat generation amount of the liquid jet head driving circuit by approximately ½. Can be reduced.

A sixth aspect of the present invention is a liquid ejecting apparatus including the liquid ejecting head and the liquid ejecting head driving circuit according to any one of the first to fifth aspects described above.
According to the liquid ejecting apparatus described in the sixth aspect of the present invention, in the liquid ejecting apparatus, it is possible to obtain the operational effects of the invention described in any of the first to fifth aspects described above.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a schematic configuration of an ink jet recording apparatus as an example of the “liquid ejecting apparatus” according to the invention will be described.

FIG. 1 is a plan view of an essential part of an ink jet recording apparatus according to the present invention, and FIG. 2 is a side view thereof. FIG. 3 is a schematic block diagram of the ink jet recording apparatus according to the present invention.
The ink jet recording apparatus 50 includes a “main scanning drive unit” that scans the recording paper P in the main scanning direction X by ejecting ink onto the recording paper P as a “recording material”. As shown, a carriage 61 supported by a carriage guide shaft 51 so as to be movable in the main scanning direction X is provided. The carriage 61 is equipped with a recording head 62 and a PW sensor 34 to be described later, and the rotational driving force of the CR motor 63 (FIG. 3) is transmitted by a belt transmission mechanism using an endless belt (not shown) to perform the main scanning direction. Reciprocates to X. A platen 52 that defines a gap between the head surface of the recording head 62 and the recording paper P is provided at a position facing the head surface of the recording head 62.

  A known capping device 59 is provided outside the one end side of the reciprocating region of the carriage 61 in the main scanning direction X. In a standby state in which recording is not performed, the carriage 61 moves over the capping device 59 and stops, and the head surface of the recording head 62 is sealed by the cap CP provided in the capping device 59. The stop position of the carriage 61 is defined as a home position HP.

  Further, in the ink jet recording apparatus 50, a conveyance driving roller 53 that conveys the recording paper P in the sub-scanning direction Y is used as “sub-scanning driving means” that causes the recording head 62 to scan the recording paper P in the sub-scanning direction Y. And a conveyance driven roller 54 are provided. The conveyance driving roller 53 rotates when the rotation driving force of the PF motor 58 (FIG. 3) is transmitted to the gear, and the recording paper P is conveyed in the sub-scanning direction Y by the rotation of the conveyance driving roller 53. A plurality of transport driven rollers 54 are provided and are individually urged by the transport driving roller 53, and the recording paper P is in contact with the recording paper P when the recording paper P is transported by the rotation of the transport driving roller 53. Rotates following the transport of A coating having a high frictional resistance is applied to the outer peripheral surface of the transport driving roller 53. The recording paper P pressed against the outer peripheral surface of the transport driving roller 53 by the transport driven roller 54 comes into close contact with the outer peripheral surface of the transport driving roller 53 by the frictional resistance of the outer peripheral surface, and rotates in the sub scanning direction by the transport driving roller 53. To be transported. The “recording execution unit” of the inkjet recording apparatus 50 includes the above-described “main scanning driving unit” and “sub-scanning driving unit”, and the recording paper P is placed between the carriage 61 and the platen 52 in the sub-scanning direction Y. Recording is performed on the recording paper P by alternately repeating the operation of transporting the recording head 62 with the transport amount and the operation of ejecting ink from the recording head 62 onto the recording paper P while the recording head 62 is reciprocated once in the main scanning direction X. Is called.

  On the upstream side of the conveyance drive roller 53 in the sub-scanning direction Y, a paper feed tray 57 as a “recording material stacking unit” capable of stacking a large number of recording sheets P is disposed. The paper feed tray 57 is configured to feed (feed) recording paper P such as plain paper or photo paper. In the vicinity of the paper feed tray 57, an ASF (automatic feeding means) that automatically feeds the uppermost recording paper P stacked on the paper feeding tray 57 to the "recording execution means" Auto sheet feeder) is provided. The ASF is an automatic paper feed mechanism having a paper feed roller 57b provided on the paper feed tray 57 and a separation pad (not shown). The paper feed roller 57 b is disposed on one side of the paper feed tray 57. The recording paper guide 57a is provided on the paper feed tray 57 so as to be slidable in the width direction in accordance with the width of the recording paper P. Then, the recording paper P placed on the paper feed tray 57 is fed by the rotational drive force of the paper feed roller 57b rotated by the transmission of the rotational drive force of the PF motor 58 (FIG. 3) and the frictional resistance of the separation pad. Paper. At this time, a plurality of recording sheets P are not fed at a time, but only the top recording sheet P is accurately separated and automatically fed one by one. A paper detector 33 according to a known technique is disposed between the paper feed roller 57b and the conveyance drive roller 53.

On the other hand, as means for discharging the recording paper P after execution of recording, a paper discharge driving roller 55 and a paper discharge driven roller 56 as “discharge driving rollers” are provided. The paper discharge driving roller 55 is rotated by transmission of the rotational driving force of the PF motor 58 (FIG. 3), and the recording paper P after recording is discharged in the sub-scanning direction Y by the rotation of the paper discharge driving roller 55. Is done. The paper discharge driven roller 56 has a plurality of teeth around it, and is a toothed roller sharply sharpened so that the tip of each tooth makes point contact with the recording surface of the recording paper P. The plurality of paper discharge driven rollers 56 are individually urged by the paper discharge driving roller 55, and come into contact with the recording paper P when the recording paper P is discharged by the rotation of the paper discharge driving roller 55. The paper rotates as the paper is discharged.
A PF motor 58 (FIG. 3) that rotationally drives the paper feed roller 57b, the conveyance drive roller 53, and the paper discharge drive roller 55, and a CR motor 63 (FIG. 3) that drives the carriage 61 in the main scanning direction will be described later. The drive is controlled by the recording control unit 10. Similarly, the recording head 62 is driven and controlled by the recording control unit 10 to eject ink onto the surface of the recording paper P.

The recording control unit 10 as a “recording control device” will be described with reference to FIGS.
The recording control unit 10 includes a ROM 11, a RAM 12, an ASIC (application specific integrated circuit) 13, an MPU 14, a nonvolatile memory 15 as a “nonvolatile storage medium”, a PF motor driver 16, a CR motor driver 17, and a head driver 18. ing. The MPU 14 includes a rotary encoder 31 as a “rotation amount detection unit” that detects the rotation amount of the transport driving roller 53 via the ASIC 13, and a linear encoder 32 as a “carriage movement amount detection unit” that detects the movement amount of the carriage 61. The paper detector 33 for detecting the leading edge and the trailing edge of the conveyed recording paper P, the PW sensor 34 for detecting the edge of the recording paper P in the main scanning direction X, and the ink jet recording apparatus 50 are turned on. An output signal of the power switch 35 for turning off / off is input.

The known rotary encoder 31 has a rotary scale 311 that rotates in conjunction with the rotation of the conveyance drive roller 53, and a rotary scale sensor 312 that detects slits formed at equal intervals along the outer periphery of the rotary scale 311. (FIG. 2). An output signal of the rotary scale sensor 312 that changes with the rotation of the transport driving roller 53 is output to the MPU 14 via the ASIC 13.
A known linear encoder 32 detects a linear scale 321 disposed in the vicinity of the carriage 61 substantially in parallel with the main scanning direction X and a linear scale that detects slits formed at equal intervals in the linear scale 321 mounted on the carriage 61. And a scale sensor 322 (FIG. 2). An output signal of the linear scale sensor 322 in which the pulse period corresponding to the moving amount of the carriage 61 in the main scanning direction X changes with the moving speed is output to the MPU 14 via the ASIC 13.

  The known paper detector 33 is given a self-returning behavior to a standing posture and protrudes into the conveyance path of the recording paper P so as to be able to rotate only in the conveyance direction (sub-scanning direction Y) of the recording paper P. This detector has a lever that is pivotally supported in the state, and the lever rotates when the tip of the lever is pushed by the recording paper P, whereby the recording paper P is detected (FIG. 2). . The paper detector 33 detects the start end position and the end position of the recording paper P fed from the paper feed roller 57 b, and the detection signal is output to the MPU 14 via the ASIC 13. The PW sensor 34 is configured by a non-contact optical sensor, and detects the end position (side end position of the recording paper P) of the recording paper P in the main scanning direction X, and the detection signal is transmitted via the ASIC 13. And output to the MPU 14. Based on the output signals of the paper detector 33 and the PW sensor 34, the MPU 14 calculates the transport position of the recording paper P, the size of the recording paper P, and the like.

  A ROM 11, a RAM 12, an ASIC 13, an MPU 14, and a nonvolatile memory 15 are connected to the system bus of the recording control unit 10. The MPU 14 performs arithmetic processing for executing recording control of the ink jet recording apparatus 50 and other necessary arithmetic processing. The ROM 11 stores a recording control program (firmware) necessary for controlling the ink jet recording apparatus 50 by the MPU 14, and various data necessary for processing the recording control program is stored in the nonvolatile memory 15. . The RAM 12 is used as a work area for the MPU 14 and a storage area for recording data.

  The ASIC 13 has a control circuit for performing speed control of the PF motor 58 and the CR motor 63 that are DC motors and driving control of the recording head 62. Based on the control command sent from the MPU 14, the output signal of the rotary encoder 31, and the output signal of the linear encoder 32, various calculations for controlling the speed of the PF motor 58 and the CR motor 63 are performed. The motor control signal based on this is sent to the PF motor driver 16 and the CR motor driver 17. Further, based on the recording data sent from the MPU 14, a control signal for the recording head 62 is calculated and generated and sent to the head driver 18 to drive-control the recording head 62. The ASIC 13 has a host IF 131 as “information transmission means” that realizes information transmission with the personal computer 301 or the like as an “information processing apparatus”.

Next, the configuration of the recording head 62 will be described with reference to FIG.
FIG. 4 illustrates the internal structure of the recording head 62. Here, only the internal structure from the ink supply needle 88 corresponding to one ink cartridge (not shown) to the nozzle 96 is shown, but the structure for ejecting ink or fixing liquid of each color from the nozzle 96 is shown respectively. The same as FIG.

  The recording head 62 includes a case 72, a vibrator unit 73 accommodated in the case 72, a flow path unit 74 joined to one end side of the case 72, and a supply needle disposed on the other end side of the case 72. The unit 76 is schematically configured. The supply needle unit 76 is a portion to which an ink cartridge is connected, and is generally configured by a needle support portion 87, an ink supply needle 88, and a filter 89. The ink supply needle 88 is a portion that is inserted into the ink cartridge and has a function of introducing ink or the like stored in the ink cartridge. The tip of the ink supply needle 88 has a plurality of ink introduction holes that communicate with the inside and outside of the ink supply needle 88. The needle support portion 87 is a member for mounting the ink supply needle 88, and a base 91 for fixing the base portion of the ink supply needle 88 is formed side by side on the surface thereof by the number of ink cartridges. Yes. The pedestal 91 is formed in a circular shape that matches the bottom shape of the ink supply needle 88.

  In addition, an ink discharge port 92 that penetrates the thickness direction of the needle support portion 87 is formed at the approximate center of the bottom surface of the base. The filter 89 is a member that blocks the passage of foreign matter in the ink such as dust and flashes at the time of molding, and is constituted by, for example, a fine metal net. The filter 89 is bonded to a filter holding groove formed in the pedestal 91. The supply needle unit 76 is disposed on the mounting surface of the case 72. In this arrangement state, the ink discharge port 92 of the supply needle unit 76 and the protruding portion 86 of the case 72 communicate with each other in a liquid-tight state via the seal member 93.

  The piezoelectric vibrator 77 serving as a “capacitive load” has a fixed end side that is joined to a fixed plate 78 so that the free end side protrudes outward from the tip surface of the fixed plate 78. The free end portion of each piezoelectric vibrator 77 is configured by alternately stacking piezoelectric elements and internal electrodes, and has a structure in which the piezoelectric elements can be expanded and contracted in the longitudinal direction by applying a potential difference between the opposing electrodes. ing. The flexible cable 79 is electrically connected to the piezoelectric vibrator 77. On the surface of the flexible cable 79, a control integrated circuit 81 for controlling driving of the piezoelectric vibrator 77 and the like is provided. In addition, the fixing plate 78 that supports each piezoelectric vibrator 77 is formed of a plate-like member made of a material such as stainless steel having rigidity capable of receiving a reaction force from the piezoelectric vibrator 77.

  The case 72 is a block-shaped member formed of a thermosetting resin such as an epoxy resin. Inside the case 72, a space 82 in which the vibrator unit 73 can be accommodated, and an ink supply path 83 as a “liquid supply path” constituting a part of the ink flow path are formed. A concave portion 85 that becomes a common ink chamber 84 is formed at the tip of the case 72. The space 82 is a space large enough to accommodate the vibrator unit 73, and the inner wall of the case 72 partially protrudes laterally at the tip side, and the upper surface of the protruding portion is fixed. It functions as a plate contact surface. The vibrator unit 73 is accommodated in the space 82 with the tip facing the opening. In this stored state, the front end surface of the fixed plate 78 is bonded in a state of being in contact with the fixed plate contact surface.

  The recessed portion 85 is a substantially trapezoidal recessed portion formed on the left and right outside of the space 82, and is formed so that the lower base of the trapezoid is located on the space 82 side. The ink supply path 83 is formed so as to penetrate the height direction of the case 72, and the tip communicates with the recess 85. Further, the end portion on the attachment surface side in the ink supply path 83 is formed in a protruding portion 86 protruding from the attachment surface. The connection board 75 is a wiring board on which electrical wiring for various signals to be supplied to the recording head 62 is formed and a connector to which a signal cable can be connected is provided. And this connection board 75 is arrange | positioned on the attachment surface in case 72, and the flexible cable 79 is connected there. In the flow path unit 74, the nozzle plate 102 is bonded to one surface of the pressure generating chamber forming plate 101, and the elastic plate 103 composed of the support plate 107 and the elastic film 108 is bonded to the other surface of the pressure generating chamber forming plate 101. This is the structure. The nozzle plate 102 is a plate-like member made of metal such as stainless steel, for example, in which nozzles 96 having “openings” for ejecting liquid are arranged. The nozzles 96 are arranged at a pitch corresponding to the dot formation density.

  By joining the elastic plate 103 to one surface of the pressure generating chamber forming plate 101, that is, the forming surface of the groove-like recess 104, the diaphragm 97 seals the opening surface of the groove-like recess 104 and pressurizes. A generation chamber 99 is defined. The nozzle 96 communicates with the corresponding communication port 105 by joining the nozzle plate 102 to the other surface of the pressure generating chamber forming plate 101. In this state, when the piezoelectric vibrator 77 bonded to the island portion 98 is expanded or contracted, the elastic film 108 around the island portion 98 is deformed, and the island portion 98 is pushed toward the groove-like depression 104 side, or the groove-like depression 104 side. It is pulled away from the direction. Due to the deformation of the elastic film 108, the pressure generation chamber 99 expands or contracts, and pressure fluctuation is applied to the ink in the pressure generation chamber 99. Furthermore, the compliance portion 95 seals the recess 85 by joining the elastic plate 103 (that is, the flow path unit 74) to the case 72. The compliance unit 95 absorbs pressure fluctuations of ink stored in the common ink chamber 84. That is, the elastic film 108 expands or contracts in accordance with the pressure of the stored ink or the like and deforms. The escape recess 106 forms a space for the elastic film 108 to expand when the elastic film 108 expands.

  The recording head 62 configured as described above includes a common ink flow path from the ink supply needle 88 to the common ink chamber 84, and an individual ink flow path from the common ink chamber 84 through the pressure generation chamber 99 to each nozzle 96. Have The ink stored in the ink cartridge is introduced from the ink supply needle 88 and stored in the common ink chamber 84 through the common ink flow path. The ink stored in the common ink chamber 84 is ejected from the nozzle 96 through the individual ink channel. For example, when the piezoelectric vibrator 77 is contracted, the diaphragm 97 is pulled toward the vibrator unit 73 and the pressure generating chamber 99 expands. Due to this expansion, the pressure generation chamber 99 has a negative pressure, so that the ink in the common ink chamber 84 flows into the pressure generation chambers 99 through the ink supply ports 94. Next, when the piezoelectric vibrator 77 is extended, the diaphragm 97 is pushed toward the pressure generating chamber forming plate 101 and the pressure generating chamber 99 contracts. By this contraction, the ink pressure in the pressure generating chamber 99 rises, and ink droplets are ejected from the corresponding nozzle 96.

Next, the “liquid ejecting head driving circuit” according to the present invention will be described with reference to FIG.
FIG. 5 is a schematic configuration diagram illustrating a liquid jet head driving circuit 100 according to the present invention.
The liquid ejecting head driving circuit 100 includes a head driver 18 and a piezoelectric vibrator driving circuit 181 as a “capacitive load driving circuit”. The head driver 18 includes a nozzle control signal generation unit 182 and a push-pull transistor control circuit 184. The nozzle control signal generation means 182 expands the pressure generation chamber 99 (FIG. 4), sucks the ink in the common ink chamber 84 (FIG. 4) into the pressure generation chamber 99, and contracts the pressure generation chamber 99 to thereby reduce the pressure generation chamber. A “nozzle control signal” for ejecting the ink in 99 from the nozzle 96 (FIG. 4) is output.

  The push-pull transistor control circuit 184 generates a control signal for the push-pull amplifier circuit 183 from the digital control signal for driving the recording head 62 received via the system bus SB, and outputs the control signal to the nozzle control signal generation means 182. The nozzle control signal generation means 182 outputs an analog AC signal obtained by D / A converting the digital control signal input from the push-pull amplifier circuit 183 to the piezoelectric vibrator driving circuit 181 as the nozzle control signal CS.

  Further, the liquid jet head driving circuit 100 includes a first constant voltage source Vdd that can supply constant voltage power up to the maximum driving voltage of the piezoelectric vibrator 77 and a constant voltage lower than the voltage of the first constant voltage source Vdd. And a second constant voltage source Vcc capable of supplying voltage power. In this embodiment, the voltage of the first constant voltage source Vdd is DC42V, and the voltage of the second constant voltage source Vcc is DC21V. The piezoelectric vibrator driving circuit 181 amplifies the amplitude voltage of the nozzle control signal CS to the driving voltage of the piezoelectric vibrator 77 with the power supplied from the first constant voltage source Vdd and the second constant voltage source Vcc. Applied between the electrodes of the piezoelectric vibrator 77.

  The piezoelectric vibrator driving circuit 181 has a circuit configuration in which the amplitude voltage of the nozzle control signal CS is amplified to the driving voltage of the piezoelectric vibrator 77 and applied between the electrodes of the piezoelectric vibrator 77, and the first constant voltage source Vdd. And a push-pull amplifier circuit 183 that operates with a DC power supply voltage supplied from the second constant voltage source Vcc. The push-pull amplifier circuit 183 is a complementary SEPP circuit in which an NPN transistor Q1 and a PNP transistor Q2 are combined, and a nozzle control signal CS is input to the bases of the NPN transistor Q1 and the PNP transistor Q2. In the output of the push-pull amplifier circuit 183 in which the emitter of the NPN transistor Q1 and the emitter of the PNP transistor Q2 are connected, one side of the electrodes of all the piezoelectric vibrators 77 arranged in the recording head 62 is in parallel. The other electrodes of all the piezoelectric vibrators 77 are connected to GND. Further, as described above, the recording head 62 has the control integrated circuit 81 for controlling the driving of the piezoelectric vibrator 77 and the like. The control integrated circuit 81 is a piezoelectric circuit driven by the piezoelectric vibrator drive circuit 181. The circuit configuration is such that the expansion and contraction operations of the vibrator 77 can be turned on / off for each piezoelectric vibrator 77.

  Further, the liquid ejecting head driving circuit 100 turns on / off the charging path from the first constant voltage source Vdd to the piezoelectric vibrator driving circuit 181 and the discharging path from the piezoelectric vibrator driving circuit 181 to the GND. It has a “switching control circuit” having a configuration that can be independently turned ON / OFF based on the voltage between the electrodes of the piezoelectric vibrator 77 estimated from CS. In this embodiment, the “switching control circuit” includes a first control circuit 185 and a second control circuit 186 as a “switching transistor control circuit”, a first switching transistor Q3, and a second switching transistor Q4. The first switching transistor Q3 and the second switching transistor Q4 are field effect transistors (FETs).

The first switching transistor Q3 is arranged so that a charging path from the first constant voltage source Vdd to the collector of the NPN transistor Q1 can be turned ON / OFF. The second switching transistor Q4 is arranged so that the discharge path from the collector of the PNP transistor Q2 to GND can be turned on / off.
In the charging path from the second constant voltage source Vcc to the piezoelectric vibrator driving circuit 181, a charging diode D1 is disposed so as to limit the current direction only in the charging direction. In addition, a discharge diode D2 is disposed on the discharge path from the piezoelectric vibrator driving circuit 181 to the second constant voltage source Vcc so as to limit the current direction only in the discharge direction.

The first control circuit 185 is configured by connecting a resistor R11, a resistor R12, a transistor Q11, and a Zener diode ZD11 as shown in the figure, and turns on the first switching transistor Q3 based on the voltage between the electrodes of the piezoelectric vibrator 77. / OFF control. That is, the first control circuit 185 is only during a period when the interelectrode voltage Vhd of the piezoelectric vibrator 77 is equal to or higher than the voltage obtained by subtracting the predetermined voltage Vd1 from the voltage of the second constant voltage source Vcc (reference numerals T1 to T6 in FIG. 7). The transistor Q11 is turned off and the first switching transistor Q3 is turned on.
The predetermined voltage Vd1 is a total value of a voltage drop caused by the first switching transistor Q3, the NPN transistor Q1, and the charging diode D1, and a voltage change during the time when the first switching transistor Q3 is turned on.

  Specifically, while the interelectrode voltage Vhd of the piezoelectric vibrator 77 is equal to or higher than the voltage obtained by subtracting the predetermined voltage Vd1 from the voltage of the second constant voltage source Vcc (reference numerals T1 to T6 in FIG. 7), the piezoelectric vibrator 77. The potential difference between the positive electrode potential and the base potential of the transistor Q11 becomes equal to or higher than the Zener voltage of the Zener diode ZD11. Thereby, during that time (reference characters T1 to T6 in FIG. 7), the transistor Q11 is turned on, the first switching transistor Q3 is turned on, and the charging path from the first constant voltage source Vdd to the piezoelectric vibrator driving circuit 181 is established. Composed.

The second control circuit 186 is configured by connecting a resistor R21, a transistor Q21, and a Zener diode ZD21 as shown in the figure, and controls ON / OFF of the second switching transistor Q4 based on the voltage between the electrodes of the piezoelectric vibrator 77. To do. That is, the second control circuit 186 operates while the voltage Vhd between the electrodes of the piezoelectric vibrator 77 is equal to or lower than the voltage obtained by adding the predetermined voltage Vd2 to the voltage of the second constant voltage source Vcc (references T0 to T2 and reference numerals in FIG. 7). Only in T5 to T7), the second switching transistor Q4 is ON-controlled.
The predetermined voltage Vd2 is a total value of the voltage drop of the second switching transistor Q4, the PNP transistor Q2, and the discharging diode D2, and the voltage change during the period when the second switching transistor Q4 is turned on.

  Specifically, while the interelectrode voltage Vhd of the piezoelectric vibrator 77 is equal to or lower than the voltage obtained by adding the predetermined voltage Vd2 to the voltage of the second constant voltage source Vcc (references T0 to T2 and reference signs T5 to T7 in FIG. 7). The potential difference between the positive electrode potential of the piezoelectric vibrator 77 and the base potential of the transistor Q21 becomes equal to or less than the Zener voltage of the Zener diode ZD21. Thereby, during that time (references T0 to T2 and reference signs T5 to T7 in FIG. 7), the transistor Q21 is turned OFF, the second switching transistor Q4 is turned ON, and a discharge path from the piezoelectric vibrator driving circuit 181 to GND is formed. Is done.

  Subsequently, the control of the first switching transistor Q3 by the first control circuit 185 and the control of the second switching transistor Q4 by the second control circuit 186 will be further described.

FIG. 6 is a circuit diagram illustrating a main part of the liquid jet head driving circuit 100.
FIG. 7 is a timing chart showing the relationship between the interelectrode voltage (head drive voltage) of the piezoelectric vibrator 77 and the ON / OFF control timing of the switching transistor Q3 and the switching transistor Q4.
First, the NPN transistor Q1 is turned on in response to the nozzle control signal CS from the state in which the interelectrode voltage Vhd of the piezoelectric vibrator 77 is substantially 0 V, that is, the positive electrode potential of the piezoelectric vibrator 77 is substantially GND potential (T0 in FIG. 7). To do. At this time, since the first switching transistor Q3 of the piezoelectric vibrator 77 is OFF (reference numerals T0 to T1 in FIG. 7), the electric charge is charged only by the power supply from the second constant voltage source Vcc. (Reference sign R1 in FIG. 6) The interelectrode voltage Vhd increases (reference signs T0 to T1 in FIG. 7).

  Since the second constant voltage source Vcc is approximately half the voltage of the first constant voltage source Vdd, the power loss when charging the piezoelectric vibrator 77 is charged only from the first constant voltage source Vdd. About half of the case. Therefore, the electric power and the amount of heat generated when charging the piezoelectric vibrator 77 can be reduced to about ½.

  While the interelectrode voltage Vhd of the piezoelectric vibrator 77 rises above the voltage obtained by subtracting the predetermined voltage Vd1 from the voltage of the second constant voltage source Vcc (reference numerals T1 to T3 in FIG. 7), the first switching transistor Q3 Turn on. Therefore, during that time, electric power is also supplied from the first constant voltage source Vdd to the piezoelectric vibrator 77, and the piezoelectric vibrator 77 is charged (reference numeral R2 in FIG. 6). The interelectrode voltage Vhd of the piezoelectric vibrator 77 rises to a drive voltage (near the voltage (DC42V) of the first constant voltage source Vdd) in accordance with the nozzle control signal CS, and the NPN transistor Q1 is turned OFF at that time. (T3 in FIG. 7). In accordance with the nozzle control signal CS, the interelectrode voltage Vhd of the piezoelectric vibrator 77 is maintained at the drive voltage for a predetermined time (reference characters T3 to T4 in FIG. 7).

  Subsequently, the PNP transistor Q2 is turned on in response to the nozzle control signal CS (reference numeral T4 in FIG. 7). At this time, since the second switching transistor Q4 is OFF, the piezoelectric vibrator 77 is discharged only to the second constant voltage source Vcc (reference numeral R3 in FIG. 6). Vhd decreases (reference numerals T4 to T5 in FIG. 7).

  Since the positive electrode of the second constant voltage source Vcc is higher than the GND potential by the voltage obtained by adding the predetermined voltage Vd2 to the voltage (DC21V) of the second constant voltage source Vcc, the charge charged in the piezoelectric vibrator 77 is piezoelectric. The power loss when discharging from the vibrator 77 to the positive electrode of the second constant voltage source Vcc is smaller than when discharging to GND as it is. Therefore, it is possible to reduce the electric power and the amount of heat generated when electric charges are discharged from the piezoelectric vibrator 77.

  While the interelectrode voltage Vhd of the piezoelectric vibrator 77 falls below the voltage obtained by adding the predetermined voltage Vd2 to the voltage of the second constant voltage source Vcc (reference numerals T5 to T7 in FIG. 7), the second switching transistor Q4 turns on. Accordingly, during this time, the electric charge charged in the piezoelectric vibrator 77 is also discharged to GND (reference R4 in FIG. 6). The interelectrode voltage Vhd of the piezoelectric vibrator 77 decreases to the GND potential according to the nozzle control signal CS (reference numerals T5 to T7 in FIG. 7).

Here, in order to make the explanation easier to understand, the time T1 (time from timing T0 to T1) is set to half the time T3 (time from timing T0 to T3) and corresponds to the predetermined voltages Vd1 and Vd2. Assuming that there is no voltage drop or the like due to the semiconductor element to be operated, if there is no energy loss in the charging / discharging process, the piezoelectric vibrator 77 is connected to the piezoelectric vibrator 77 between T0 and T3 only by the conventional first constant voltage source Vdd. The energy Eo required for charging the electric charge is as shown in the following formula (1).

Eo = I · ∫ ^T3 _T0 (t · V / T3) dt
= VI ・ T3 / 2
= VI · T1 (J) (1)

On the other hand, in the liquid jet head driving circuit 100 according to the present invention, the piezoelectric vibrator 77 is charged only by the power supply from the second constant voltage source Vcc between T0 and T1, and the following equation (2) is obtained. Energy can be reduced by the calculated energy Ec.

Ec = I · ∫ ^T1 _T0 (t · V / T1) dt
= VI ・ T1 / 2
= Eo / 2 (J) (2)

  As a result, according to the liquid jet head driving circuit 100 according to the present invention, the power consumption can be reduced by about 50% compared to the conventional art. In other words, the energy E0 is conventionally consumed by the NPN transistor Q1 and the PNP transistor Q2 of the push-pull drive circuit 183 as heat, but in the liquid jet head drive circuit 100 according to the present invention, the power consumption And the calorific value can be halved. Actually, the power consumption cannot be reduced to 50% because there is a loss of the predetermined voltages Vd1 and Vd2, but it is possible to obtain a power consumption reduction effect close to that.

Thus, according to the liquid jet head driving circuit 100 according to the present invention, the charging path from the first constant voltage source Vdd to the piezoelectric vibrator driving circuit 181 and the discharging path from the piezoelectric vibrator driving circuit 181 to GND. The ON / OFF timing is executed with reference to the voltage (DC21V) of the second constant voltage source Vcc at which the voltage is always kept constant. As a result, stable liquid ejection control can be executed regardless of the driving voltage of the piezoelectric vibrator 77 and the like, so that the liquid ejection control pattern with different driving voltages of the piezoelectric vibrator 77 can be stably handled. The liquid ejection control can be executed.
In addition, the liquid jet head driving circuit 100 that generates less heat due to power consumption and power loss enables the power consumption of the liquid jet head driving circuit 100 and the size of heat dissipation means such as a heat sink. 50 power consumption and downsizing can be realized.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

1 is a schematic plan view of an ink jet recording apparatus according to the present invention. 1 is a schematic side view of an ink jet recording apparatus according to the present invention. 1 is a schematic block diagram of an ink jet recording apparatus according to the present invention. An internal structure of the recording head will be described. FIG. 3 is a schematic configuration diagram illustrating a liquid ejecting head driving circuit. FIG. 5 is a circuit diagram illustrating a main part of a liquid jet head driving circuit. 3 is a timing chart showing control of a switching transistor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Recording control part, 11 ROM, 12 RAM, 13 ASIC, 14 MPU, 15 Non-volatile memory, 16 PF motor driver, 17 CR motor driver, 18 Head driver, 50 Inkjet recording device, 51 Carriage guide shaft, 52 Platen, 53 Carrying drive roller, 54 Carrying driven roller, 55 Paper discharge driving roller, 56 Paper discharge driven roller, 57 Paper feed tray, 57b Paper feed roller, 58 PF motor, 59 Capping device, 61 Carriage, 62 Recording head, 63 CR motor , 77 Piezoelectric vibrator, 83 Ink supply path, 96 nozzles, 99 Pressure generating chamber, 100 Liquid ejecting head drive circuit, 181 Piezoelectric vibrator drive circuit, 182 Nozzle control signal generating means, 183 Push-pull amplifier circuit, 184 Push-pull transition Star control circuit, 185 first control circuit, 186 second control circuit, P recording paper, Q3 first switching transistor, Q4 second switching transistor, Vdd first constant voltage source, Vcc second constant voltage source, X main scanning direction, Y sub scanning direction

Claims (6)

A nozzle having an opening for ejecting liquid, a pressure generating chamber communicating with a common liquid chamber via a liquid supply path, and a capacitive load for expanding and contracting the pressure generating chamber by applying a potential difference between the electrodes Is a liquid ejecting head driving circuit for driving a liquid ejecting head arranged in a large number on the head surface,
Outputs a nozzle control signal for expanding the pressure generating chamber to suck the liquid in the liquid chamber into the pressure generating chamber and contracting the pressure generating chamber to eject the liquid in the pressure generating chamber from the opening. Nozzle control signal generating means for performing,
A first constant voltage source; a second constant voltage source capable of supplying constant voltage power having a voltage lower than the voltage of the first constant voltage source;
The amplitude voltage of the nozzle control signal is amplified to the drive voltage of the capacitive load by the power supplied from the first constant voltage source and the second constant voltage source, and applied between the electrodes of the capacitive load. A capacitive load driving circuit,
The charging path from the first constant voltage source to the capacitive load driving circuit and the discharging path from the capacitive load driving circuit to GND are independently turned ON / OFF based on the inter-electrode voltage of the capacitive load. A switching control circuit having a configuration that can be turned off,
When charging the capacitive load, the switching control circuit is configured to supply the capacitive load from the first constant voltage source while the interelectrode voltage of the capacitive load is equal to or lower than the voltage of the second constant voltage source. Charging from the first constant voltage source to the capacitive load driving circuit is performed while the charging path to the load driving circuit is turned OFF and the voltage between the electrodes of the capacitive load exceeds the voltage of the second constant voltage source When the path is turned on and the charge charged in the capacitive load is discharged, the capacitive load drive circuit is connected to GND while the voltage between the electrodes of the capacitive load exceeds the voltage of the second constant voltage source. And the discharge path from the capacitive load drive circuit to GND is turned on while the voltage between the electrodes of the capacitive load is equal to or lower than the voltage of the second constant voltage source. Liquid ejecting head driving circuit. 2. The push-pull amplifier circuit according to claim 1, wherein the capacitive load driving circuit is a complementary SEPP circuit in which an NPN transistor and a PNP transistor are combined.
The switching control circuit includes a first switching transistor arranged to be able to turn on / off a charging path from the first constant voltage source to the collector of the NPN transistor;
A second switching transistor disposed so that a discharge path from the collector of the PNP transistor to GND can be turned ON / OFF;
A liquid ejecting head driving circuit comprising: a switching transistor control circuit that controls ON / OFF of the first switching transistor and the second switching transistor. 3. The charging diode according to claim 2, wherein a charging diode is disposed in a charging path from the second constant voltage source to the capacitive load driving circuit so as to limit a current direction only in a charging direction, and the capacitive load driving. A liquid jet head driving circuit comprising: a discharge diode disposed in a discharge path from the circuit to the second constant voltage source so as to limit a current direction only in a discharge direction. . 4. The switching transistor control circuit according to claim 3, wherein the switching transistor control circuit controls the first switching transistor only while the voltage between the electrodes of the capacitive load is equal to or higher than a voltage obtained by subtracting a predetermined voltage Vd1 from the voltage of the second constant voltage source. ON control of the second switching transistor is performed only while the inter-electrode voltage of the capacitive load is equal to or lower than the voltage obtained by adding the predetermined voltage Vd2 to the voltage of the second constant voltage source. And a second control circuit. A liquid jet head drive circuit, comprising: a second control circuit; 5. The liquid jet head driving circuit according to claim 1, wherein the voltage of the second constant voltage source is substantially ½ of the voltage of the first constant voltage source. 6. . A liquid ejecting apparatus including the liquid ejecting head and the liquid ejecting head driving circuit according to claim 1.

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