JP5481618B2 - Inkjet recording apparatus and inkjet head driving method - Google Patents

Description

  The present invention relates to an ink jet recording apparatus including an ink jet head that ejects ink droplets from an ink ejection port communicating with a pressure chamber filled with ink, and a method for driving the ink jet head.

  The ink jet recording apparatus performs printing and image recording by ejecting minute ink droplets from an ink ejection port of an ink jet head to a recording medium, and can perform a recording operation in a state separated from the recording medium. It can be recorded on recording media and articles of various materials and is used in a wide range of applications.

  In recent years, in such an ink jet recording apparatus, in order to record high-definition image data, it is required to increase the density of recorded images and increase the recording speed. Therefore, development of an ink jet head in which a large number of ink discharge ports and pressure chambers are arranged at a high density is in progress, and there is a demand for miniaturization and uniformization of ink droplets discharged from each ink discharge port.

  Various types of ink-jet heads used for ink-jet recording have been developed. For example, a pressure chamber filled with ink is expanded and contracted by applying a voltage to a piezoelectric element to deform the ink, thereby forming an ink. Piezo-type inkjet heads that cause pressure fluctuations and eject ink droplets have been developed.

  In such a piezo-type inkjet head, it has been proposed to improve the ejection characteristics of ink droplets by controlling the deformation of the piezoelectric element by the drive waveform of the voltage applied to the piezoelectric element. For example, Patent Document 1 describes that a drive voltage waveform for charging and discharging at a predetermined peak voltage is generated by inputting a discharge charge signal and a discharge discharge signal. By controlling this, the ink ejection operation at a high frequency is stabilized. Further, in Patent Document 2, a rising waveform and a falling waveform are generated in the waveform generation unit depending on whether the voltage level output from the D / A converter is higher or lower than a predetermined potential, and the voltage is set when the voltage level is a predetermined potential. It is described that the voltage waveform is generated so as to be maintained and the piezoelectric actuator of the inkjet head is driven.

JP-A-9-39228 Re-published patent 2002/034528

  In the above-mentioned patent document, it is possible to adjust the drive waveform applied to the piezoelectric element that is the drive element of the ink jet head, but in order to adjust the rise and fall waveforms of the drive waveform, the circuit configuration Therefore, it is difficult to easily adjust the resistance value and the capacitance.

  In an inkjet head in which a plurality of ink ejection ports and a plurality of pressure chambers communicating with each ink ejection port are formed, a plurality of drive elements are provided corresponding to each pressure chamber. Are different depending on the structure of the pressure chamber and the ink flow path and the difference of the driving elements. For this reason, it is necessary to finely adjust the drive waveform applied to the drive element in accordance with the discharge characteristics of each ink discharge port to make the discharged ink droplets uniform. It is difficult to make adjustments according to the ejection characteristics of the ink ejection ports.

  SUMMARY An advantage of some aspects of the invention is that it provides an ink jet recording apparatus and an ink jet head driving method capable of easily adjusting a driving waveform applied to a driving element in accordance with ejection characteristics of a plurality of ink ejection ports.

An ink jet recording apparatus according to the present invention includes an ink jet head provided with a drive element corresponding to a pressure chamber filled with ink and communicating with an ink discharge port, and driving the drive element to the ink in the pressure chamber. In the ink jet recording apparatus including a drive circuit that causes pressure fluctuations to eject ink droplets from the ink ejection port, the drive circuit has a rise time , a fall time , and a peak value related to a drive waveform that drives the drive element. Storage means for storing setting data including: timing control means for generating timing control signals related to rising and falling of the drive waveform; rising and falling waveforms based on the setting data and the timing control signal; and Bei a waveform generating means for generating the driving waveform having the peak value between the two waveforms And wherein the are. Further, the storage means stores correction data related to the setting data for finely adjusting the drive waveform corresponding to the drive element, and the waveform generation means is configured to store the drive element based on the correction data. Another drive waveform is generated.

The ink jet head driving method according to the present invention drives a driving element provided corresponding to a pressure chamber that is filled with ink and communicates with an ink discharge port to cause pressure fluctuation in the ink in the pressure chamber. In the inkjet head driving method for discharging ink droplets from the ink discharge port, setting data including a rise time , a fall time , and a peak value related to a drive waveform for driving the drive element, and timing related to the rise and fall of the drive waveform generating the driving waveform having the peak value during the rising waveform and falling waveform and the both waveforms on the basis of the control signal, and applying the generated the driving waveform to the driving element.

  The present invention has the above-described configuration, so that it is possible to generate a rising waveform that rises to a predetermined peak value based on the rising time related to the drive waveform stored as setting data, and the stored falling time The falling waveform that falls from a predetermined peak value can be generated based on the above. Since the width of the drive waveform is determined based on the timing control signal related to the rise and fall of the drive waveform, the drive waveform can be easily changed based on the setting data and the timing control signal.

  Accordingly, it is possible to make the ink droplets ejected from each ink ejection port uniform by finely adjusting the drive waveform according to the ink ejection characteristics from each ink ejection port. In addition, the ink ejection characteristics change if the characteristics such as the viscosity of the ink used differ, but the optimum ejection operation for the ink characteristics can be achieved by changing the setting data and timing control signal in response to such changes. Can be easily adjusted.

  Further, if the peak value of the drive waveform can also be set according to the ink discharge characteristics from each ink discharge port, the drive waveform can be adjusted more finely according to the ink discharge characteristics.

  In addition, setting data is stored corresponding to the driving element, the setting data is adjusted according to the ink ejection characteristics, and fine adjustment is performed so that a driving waveform can be generated with high accuracy based on the correction data, thereby driving efficiently. Waveform generation processing can be performed.

1 is a schematic configuration diagram of an ink jet recording apparatus according to the present invention. It is a schematic diagram which shows the structure for discharging ink from a nozzle. It is a circuit block block diagram which controls operation | movement of an inkjet recording device. It is a functional block block diagram regarding a head drive circuit. It is a functional block block diagram regarding a drive waveform generation part. It is a timing chart which shows an example of the generated drive waveform.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are preferable specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.

  FIG. 1 is a schematic configuration diagram of an ink jet recording apparatus according to the present invention. The ink jet head 100 is disposed over the entire width of the sheet-like recording medium P, and ink discharge ports are formed in a line shape along the direction X on the lower surface of the ink jet head 100. Below the ink jet head 100, an endless transport belt 101 disposed opposite to the ink discharge ports is stretched between a pair of transport rollers 102. The recording medium P is placed on the transport belt 101 and transported in the scanning direction Y. After ejecting ink from the ink ejection port of the inkjet head 100 and performing a recording operation of a predetermined line on the surface of the recording medium P, the conveying belt 101 is controlled to be transported in the scanning direction Y, and the recording medium P is printed by a predetermined line. The next line is recorded. By repeating such a recording operation and conveyance control, an image or the like can be recorded on the surface of the recording medium P.

  The inkjet head 100 includes a plurality of ink discharge units, and each ink discharge unit is formed with a plurality of nozzles that are ink discharge ports. FIG. 2 is a schematic diagram illustrating a configuration for ejecting ink from each nozzle. A pressure chamber 111 filled with ink is formed inside the ink discharge unit 110, and a nozzle 112 is formed on the discharge surface side of the ink discharge unit 110. A channel through which ink flows is formed between the nozzle 112 and the pressure chamber 111. An ink supply path communicating with an ink tank (not shown) is connected to the pressure chamber 111 so that ink is supplied from the ink tank.

  A vibration plate 113 is attached to the upper portion of the pressure chamber 111, and a piezoelectric element 114 as a driving element is bonded and fixed to the upper surface of the vibration plate 113 corresponding to the pressure chamber 111. The piezoelectric element 114 has a lower electrode formed on the surface on the diaphragm 113 side, and an upper electrode formed on the opposite surface.

  The piezoelectric element 114 expands and contracts in a direction perpendicular to the thickness direction by applying a drive signal between the lower electrode and the upper electrode, and accordingly, the diaphragm 113 bonded to the piezoelectric element 114 bends. When the vibration plate 113 is deformed in the direction in which the pressure chamber 111 is expanded, the internal pressure is reduced due to the expansion of the pressure chamber 111, and ink is drawn into the pressure chamber 111. Thereafter, the diaphragm 113 is deformed in a direction in which the pressure chamber 111 is contracted, so that the internal pressure rises due to the contraction of the pressure chamber 111 and the ink staying in the pressure chamber 111 is discharged from the nozzle 112.

FIG. 3 is a circuit block configuration diagram for controlling the operation of the ink jet recording apparatus. The recording control circuit 30 that controls the recording operation performs the recording operation by controlling the head driving circuit 31 and the conveyance driving circuit 32 based on the recording signal input from the outside. The head drive circuit 31 drives the piezoelectric elements of the ink ejection units 10 ₁ to 10 _n based on the reference timing control signal, setting data, and recording data transmitted from the recording control circuit 30 to eject ink droplets from the ink ejection ports. Discharge.

  The reference timing control signal is a signal for determining the timing for performing the recording operation, and the setting data is data for generating a drive waveform of the drive voltage of the piezoelectric element. The setting data is for setting parameters such as the rise time and fall time of the drive waveform and the peak value of the drive waveform, and is adjusted according to the ink ejection characteristics of each drive element. The correction data is data for fine adjustment so as to generate the drive waveform with high accuracy.

  For setting data, data is determined in advance according to ink characteristics such as viscosity and ink ejection characteristics for each drive element, and each drive is fine-tuned with correction data to generate a drive waveform for each drive element with high accuracy. What is necessary is just to optimize the ink discharge characteristic of an element.

  The conveyance drive circuit 32 drives and controls a conveyance motor that performs the conveyance operation of the conveyance belt 101 based on the reference timing control signal and the conveyance control data transmitted from the recording control circuit 30.

  FIG. 4 is a functional block configuration diagram relating to the head drive circuit 31. The recording data processing unit 310 receives the reference timing control signal T1 and recording data from the recording control circuit 30, and records the recording data D1, the setting data D2, and the correction data D3, respectively, as the recording data memory 311, the setting data memory 312 and the correction. The data is stored in the data memory 313 and the reference timing control signal T1 is transmitted to the timing control signal generation unit 314.

The timing control signal generation unit 314 supplies the drive waveform generation units 320 _{1 to} 320 _n to the drive waveform generation units 320 _{1 to} 320 _n based on the received reference timing control signal T1 and the recording data D1 and setting data D2 read from the recording data memory 311 and the setting data memory 312, respectively. A drive timing control signal T2 is transmitted. The drive waveform generators 320 _{1 to} 320 _n are provided corresponding to the ink discharge units 10 ₁ to 10 _n , respectively, and generate drive waveforms for driving the piezoelectric elements of the respective ink discharge units to generate piezoelectric elements. Apply to.

  The timing control signal generation unit 314 includes a delay circuit that shifts the transmission timing of the drive timing control signal T2. For example, when performing color recording, when different color inks are sequentially ejected to the same recording line, the drive timing control signal T2 is ejected to each ink according to the timing when the ink ejection unit corresponding to each color faces the recording line. Must be sent to the unit. Therefore, it is possible to accurately perform color recording by transmitting the drive timing control signal T2 by using a delay circuit in synchronization with the recording timing of each ink discharge unit.

  The drive timing control signal T2 is a signal that determines the rise and fall timings of the drive waveform, and the pulse width of the drive waveform is determined by the interval between the rise timing signal and the fall timing signal.

The drive data output unit 315 reads the recording data D1, the setting data D2, and the correction data D3 from the recording data memory 311, the setting data memory 312 and the correction data memory 313, converts them into corresponding driving waveforms, and a driving waveform generation unit 320. to send to the _{1 ~320 n.}

FIG. 5 is a functional block configuration diagram relating to the drive waveform generation units 320 _{1 to} 320 _n . The drive waveform generation unit 320 includes a rising waveform generation unit 321, a falling waveform generation unit 322, a wave height generation unit 323, and a waveform synthesis unit 324.

  The rising waveform generation unit 321 generates a rising waveform based on the rising time data and the peak value in the setting data D2. For example, a rising waveform in which the potential changes linearly so that the time until it rises from the base potential to the peak potential is the rising time, and is generated in accordance with the rising timing of the drive timing control signal T2. Outputs the rising waveform.

  The falling waveform generation unit 322 generates a falling waveform based on the falling time data and the peak value in the setting data D2. For example, a falling waveform in which the potential changes linearly so that the time from the peak value potential to the base potential falls as the falling time is generated and generated in accordance with the falling timing of the drive timing control signal T2. Output falling waveform.

  The peak generation unit 323 outputs a waveform generated so that the potential of the peak value is maintained between the rising waveform and the falling waveform.

  In the example described above, the peak value is stored as setting data and transmitted to the drive waveform generation unit. However, if it is not necessary to change the peak value, the peak value is stored in advance in the drive waveform generation unit. You may make it leave.

  The waveform synthesizing unit 324 synthesizes the waveforms generated by the rising waveform generating unit 321, the falling waveform generating unit 322, and the wave height generating unit 323 to synthesize a driving waveform, and the synthesized driving waveform is applied to each piezoelectric of the ink ejection unit 10. Output to the element and drive.

FIG. 6 is a timing chart showing an example of the generated drive waveform. The reference timing control signal T1 is turned on for a predetermined time according to the timing of the recording operation. Then, the drive timing control signal T2 is turned on with a delay of time t ₀ from the timing when the reference timing control signal T1 is turned on. The delay time t ₀ is a time set corresponding to the ink ejection unit, and is set to shift the recording timing when performing color recording as described above.

  The drive timing control signal T2 has a pulse for setting the rise and fall timings of the drive waveform. In this example, the timing at which the first pulse P1 rises after the reference timing control signal T1 is turned on is the rise timing of the first drive waveform, and the timing at which the next pulse P2 rises is the fall timing of the first drive waveform. . In the example shown in FIG. 6, the second drive waveform is generated next to the first drive waveform, and for the second drive waveform, the timing at which the pulse P3 rises becomes the rise timing of the second drive waveform, The timing when the next pulse P4 rises becomes the fall timing of the second drive waveform. The pulse width of the first drive waveform is determined by the interval W1 between the pulses P1 and P2, and the pulse width of the second drive waveform is determined by the interval W2 between the pulses P3 and P4. The timing of the second drive waveform is also set based on the interval W3 between the pulses P2 and P3.

Further, the rising waveform of the first drive waveform is generated based on the rising time and peak value set in advance and their correction data, and rises linearly from the base potential V ₀ to the potential V ₁ corresponding to the peak value. Is generated as follows. In this example, the rise time is set to be the same as the width of the pulse P1, but may be set to a time shorter or longer than the width of the pulse P1. Alternatively, the potential V ₁ may be forcibly set at the falling timing of the pulse P1.

The falling waveform of the first drive waveform is generated based on the preset falling time, peak value, and correction data thereof, and linearly decreases from the potential V ₁ corresponding to the peak value to the base potential V _0. Is generated as follows. In this example, the fall time is set to be the same as the width of the pulse P2, but may be set to a time shorter or longer than the width of the pulse P2. Alternatively, the potential V ₀ may be forcibly set at the falling timing of the pulse P2.

The generated rising waveform is output at the rising timing of the pulse P1, and the falling waveform is output at the rising timing of the pulse P2, so that the potential V ₁ is maintained between the rising waveform and the falling waveform. A first drive waveform is generated.

Also for the second drive waveform, a rise waveform is generated so as to rise linearly from the base potential V ₀ to the potential V ₂ corresponding to the peak value based on the preset rise time and peak value and their correction data. The falling waveform is generated so as to decrease linearly from the potential V ₂ to the base potential V ₀ based on the preset falling time and peak value and their correction data. Then, the rising waveform is output at the rising timing of the pulse P3, the falling waveform is output at the rising timing of the pulse P4, and the second drive is performed so that the potential V ₂ is maintained between the rising waveform and the falling waveform. Generate a waveform.

  As described above, since the output timing and pulse width of the drive waveform can be determined by the drive timing control signal T2, the drive waveform can be easily changed by changing the setting of the drive timing control signal T2. In addition, since the drive waveform is generated by setting data such as the rise time, fall time, and peak value of the drive waveform, the setting data is appropriately changed according to the ink characteristics and the ink discharge characteristics of the ink discharge unit. The drive waveform can be finely adjusted.

  In the example described above, a combination of two trapezoidal waveforms is generated as the drive waveform, but the drive timing control signal T2 is appropriately set for a combination of one trapezoidal waveform or a plurality of waveforms. By doing so, it can be easily generated. Therefore, various drive waveforms can be generated without being limited to the above example.

  When performing a recording operation, the recording control circuit 30 first generates setting data and correction data and transmits them to the head drive circuit 31. The head drive circuit 31 temporarily stores the transmitted setting data and correction data in a memory, and transmits the setting data and correction data to the drive waveform generation unit 320 based on a data update command from the recording control circuit 30. Update data.

  After setting data and correction data are set, a reference timing control signal T 1 and recording data D 1 are transmitted from the recording control circuit 30 to the head driving circuit 31. In the head driving circuit 31, a driving timing control signal T2 is generated based on the reference timing control signal, and the generated driving timing control signal T2 and recording data D1 are transmitted to the driving waveform generation unit 320, and correspond to the recording data D1. A drive waveform is generated and output to the ink discharge unit. Thereafter, a reference timing control signal T1 and new recording data D1 are transmitted from the recording control circuit 30, and a recording operation is performed.

100 inkjet head
101 Conveyor belt
102 Conveyor roller
110 Ink ejection unit
111 Pressure chamber
112 nozzles
113 Diaphragm
114 Piezoelectric element

Claims (3)

An ink jet head provided with a drive element corresponding to a pressure chamber filled with ink and communicating with an ink discharge port, and driving the drive element to cause a pressure fluctuation in the ink in the pressure chamber, thereby discharging the ink. In an ink jet recording apparatus comprising a drive circuit for ejecting ink droplets from an outlet, the drive circuit stores setting data including a rise time , a fall time , and a peak value related to a drive waveform for driving the drive element. When the timing control means for generating a timing control signal related to the rise and fall of the driving waveform, the peak value during the rising waveform and falling waveform and the both waveforms on the basis of the setting data and the timing control signal An inkjet comprising: waveform generation means for generating the drive waveform having Recording apparatus. The storage means stores correction data relating to the setting data for finely adjusting the drive waveform corresponding to the drive element, and the waveform generation means is configured to determine the drive data for each drive element based on the correction data. The inkjet recording apparatus according to claim 1, wherein the drive waveform is generated. Inkjet that drives a drive element provided corresponding to a pressure chamber that is filled with ink and communicates with an ink discharge port to cause pressure fluctuation in the ink in the pressure chamber and discharge ink droplets from the ink discharge port In the head driving method, a rising waveform and a falling waveform based on setting data including a rising time, a falling time and a peak value related to a driving waveform for driving the driving element, and a timing control signal related to the rising and falling of the driving waveform. In addition, the driving waveform having the peak value between the two waveforms is generated, and the generated driving waveform is applied to the driving element.

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