JP2003118093A - Drive controller of ink jet head and method for detecting incomplete ink ejection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect incomplete ink ejection due to mixture of a bubble in an electrostatic driving type ink jet head through a simple arrangement. SOLUTION: The drive controller 1 of an electrostatic driving type ink jet head 100 comprises an ink jet head control section 2 and a head driver IC wherein an incomplete nozzle judging circuit 23 at the ink jet head control section 2 judges presence of an ink nozzle ejecting ink incompletely based on a drive current being generated between the diaphragm and the discrete electrode of each ink nozzle and detected by a drive current detecting circuit 22. When incomplete ink ejection is detected, a head recovery control circuit 31 drives an ink suction mechanism 32 to suck ink from the ink nozzle 105 thus removing a mixed bubble.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet head drive control device having a mechanism for determining whether or not ink droplets are normally ejected from ink nozzles of an electrostatically driven inkjet head. . Also,
The present invention relates to a method for detecting defective ink ejection of an inkjet head, which determines whether or not ink droplets are normally ejected from an ink nozzle of an electrostatically driven inkjet head.

[0002]

2. Description of the Related Art As an ink jet head, an electrostatic drive type ink jet head is known in which an ink droplet is ejected from an ink nozzle by utilizing electrostatic force. In this electrostatic drive type inkjet head, a vibrating plate capable of vibrating in an out-of-plane direction is formed on the bottom surface of the ink pressure chamber communicating with the ink nozzle, and the vibrating plate is opposed to the counter electrode at regular intervals, A drive voltage pulse having a predetermined waveform is applied between the diaphragm and the counter electrode.

When a driving voltage pulse is applied between the vibrating plate and the counter electrode, the vibrating plate is attracted to the counter electrode by the electrostatic attraction force generated therebetween, and the volume of the ink pressure chamber increases, and the driving is performed. When the application of the voltage pulse is released, the electrostatic attraction force disappears, so that the diaphragm is released from the counter electrode by the elastic restoring force, and the volume of the ink pressure chamber is rapidly reduced. The volume variation causes a pressure variation in the ink pressure chamber, which causes a predetermined amount of ink droplets to be ejected from the ink nozzle.

In the ink jet head having this structure, when air bubbles are mixed in the ink flow paths such as the ink nozzles and ink pressure chambers, the ink viscosity in the ink nozzles is increased, or foreign matter such as paper dust is contained in the ink nozzles. In the case of adhesion, an appropriate amount of ink droplets may not be ejected from the ink nozzle at an appropriate speed, which may result in ink ejection failure. Depending on the case, the problem of dot omission in which ink droplets are not ejected also occurs.

For this reason, in an ink jet printer equipped with a conventional ink jet head, in order to prevent ejection failure of the ink jet head, for example, an ink droplet ejection operation unrelated to printing is periodically performed. The thickened ink is removed, and the air bubbles mixed in are removed. Alternatively, the ink nozzle surface of the inkjet head is wiped with a wiper blade to remove foreign matter such as paper dust attached thereto.

[0006]

The nozzle recovery operation of such an ink jet head is regularly performed regardless of whether or not ink ejection failure has occurred in the ink nozzles. Therefore, when the ink ejection failure does not occur, the ink is simply wasted, and the ink utilization efficiency is poor.

Even if the nozzle recovery operation is performed, the ink ejection failure of each ink nozzle may not be solved.
In this case, conventionally, it is not possible to confirm whether or not the ink ejection failure of each ink nozzle has been eliminated without actually observing the printed matter visually.

In view of the above problems, an object of the present invention is to electrostatically drive an ink ejection failure such as dot omission caused by the inclusion of bubbles, which can be easily detected and an unnecessary nozzle recovery operation can be avoided. The purpose of the present invention is to propose a drive control device for an inkjet head.

Another object of the present invention is to easily detect ink ejection defects such as missing dots due to air bubble inclusion.
An object of the present invention is to propose a method for detecting defective ink ejection of an electrostatically driven inkjet head that can avoid an unnecessary nozzle recovery operation.

[0010]

In order to solve the above-mentioned problems, the present invention forms an ink nozzle, an ink pressure chamber communicating with the ink nozzle, and a part of the ink pressure chamber. In a drive control device for an inkjet head having a vibrating plate that is elastically displaceable in an out-of-plane direction and a counter electrode that is arranged to face the vibrating plate, the vibrating plate is used to eject ink droplets from the ink nozzles. And drive voltage pulse generating means for applying a drive voltage pulse of a predetermined waveform between the counter electrode and a drive current for detecting a drive current generated between the diaphragm and the counter electrode when the drive voltage pulse is applied. Based on the detection means and the detection drive current detected by the drive current detection means, it is determined whether or not ink droplets are normally ejected from the ink nozzle. It is characterized by having an ink discharge failure determination means.

In the electrostatic drive type ink jet head, when air bubbles are mixed in the ink pressure chamber, the vibration characteristics of the diaphragm change from those when only the ink is filled. This change affects the rate of change of the electrostatic capacitance between the diaphragm and the counter electrode during vibration of the diaphragm, so that the drive current generated between the diaphragm and the counter electrode changes.
In the present invention, by detecting this drive current, it is possible to easily detect whether or not an ink ejection failure has occurred in the ink nozzle.

The ink ejection failure determination means can perform determination based on the current waveform of the detection drive current.
Further, the determination can be made based on the peak current value of the detected drive current. Alternatively, the determination can be made based on the differential waveform of the detected drive current. Of course, these may be used together to make the determination.

Here, the change in the drive current due to the inclusion of bubbles appears during the period in which the diaphragm is elastically displaced toward the counter electrode, or during the period in which the diaphragm is elastically displaced in the direction away from the counter electrode. Therefore, it suffices to detect the drive current during this period.

Further, the ink ejection failure judging means can judge by comparing the detected driving current with a normal driving current stored in advance.

When a plurality of the ink nozzles, a plurality of the ink pressure chambers, and a plurality of sets of the vibrating plate and the counter electrode are provided, the ink ejection failure judging means is:
Determined by comparing the combined current of the detected drive currents obtained when the driving voltage pulse is applied simultaneously between a plurality of sets of the diaphragm and the counter electrode with the combined current of the normal drive current stored in advance. It can be performed.

Instead of this, the ink ejection failure determination means makes a determination by comparing the detected drive currents obtained when the drive voltage pulse is applied between a plurality of sets of the diaphragm and the counter electrode with each other. You can also do

Next, by the drive voltage pulse generating means, a first drive voltage pulse for ejecting ink droplets for printing and a first drive voltage pulse having a gentle rising waveform as compared with the first drive voltage pulse are provided. The second drive voltage pulse can be generated, and the ink ejection failure determination means can perform the determination based on the drive current generated when the second drive voltage pulse is applied.

Instead of the above, the drive voltage pulse generating means causes a first drive voltage pulse for ejecting ink droplets for printing and a second drive voltage pulse having a voltage value smaller than that of the first drive voltage pulse. The drive voltage pulse may be generated, and the ink ejection failure determination means may perform the determination based on the drive current generated when the second drive voltage pulse is applied.

By using such a second drive voltage pulse, it is possible to increase the amount of change in the drive current that appears due to the inclusion of bubbles, so that the detection sensitivity or accuracy can be improved.

Next, in the case of having a nozzle recovery means for recovering an ink nozzle having an ink ejection failure, if the ink ejection failure determination means determines that there is an ink ejection failure, The recovery operation of the ink nozzles may be performed by the nozzle recovery means.

As the nozzle recovery means for removing the air bubbles mixed in the ink pressure chamber, generally, an ink suction means provided with an ink pump for sucking ink from the ink nozzles may be adopted.

On the other hand, the present invention utilizes the electrostatic force generated by applying a drive voltage pulse between the opposing electrodes to detect the ejection failure of the ink droplet in the ink jet head which ejects the ink droplet from the ink nozzle. In the method for detecting defective ink ejection, a drive current waveform generated between the opposed electrodes is measured, and based on the drive current waveform, it is determined whether ink droplets are normally ejected from the ink nozzle. It is characterized by that.

The determination can be made based on the peak current value of the drive current waveform and / or the differential waveform of the drive current waveform.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrostatic drive type inkjet head drive control device to which the present invention is applied will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an electrostatic drive type ink jet head of this example, and FIG. 2 is a schematic block diagram showing a drive control device thereof.

(Inkjet Head) First, with reference to FIG. 1, the structure of the electrostatically driven inkjet head of this example will be described. The inkjet head 100 includes a glass substrate 102, a silicon substrate 103, and an electrode glass substrate 104 that are stacked, and two of these substrates 102,
A plurality of ink nozzles 105 and an independent ink pressure chamber 1 communicating with each ink nozzle 105
In addition to dividing and forming 06, a vibration plate 107 that is elastically displaceable in the out-of-plane direction is formed on the bottom surface portion of each ink pressure chamber 106.

A counter electrode 109 is formed on the electrode glass substrate 104 laminated on the back side of the vibrating plate 107 so as to face each vibrating plate 107 with a constant gap. Each diaphragm 107 functions as a common electrode, and each counter electrode 109 functions as an individual electrode. When a driving voltage pulse having a predetermined waveform is applied between them, an electrostatic force is generated between them and each diaphragm 107 can be vibrated individually.

When the vibrating plate 107 vibrates, the volume of the corresponding ink pressure chamber 106 increases or decreases, which causes a pressure fluctuation in the ink pressure chamber 106, and based on this, the ink nozzles communicating with the ink pressure chamber 106. Ink droplets 110 are ejected from 105.

(Drive Control Device) Next, a drive control device for driving and controlling the ink jet head 100 will be described with reference to FIG. The inkjet head drive control device 1 of the present example includes an inkjet head control unit 2 mainly including a CPU. External device 3 for CPU
The print information is supplied from the printer via the bus, and the ROM, the RAM and the character generator 4 are connected via the internal bus.

In this ink jet head controller 2,
Using the storage area in RAM as a work area, the control program stored in ROM is executed, and based on the character information generated from the character generator 4,
A control signal for driving the inkjet head is generated. The control signal becomes a drive control signal corresponding to the print information via the logic gate array 5 and the drive pulse generating circuit 6, and is supplied to the head driver IC 9 formed on the head substrate 8 via the connector 7. . Further, the reference driver voltage pulse signal V3, the control signal LP, and the polarity inversion control signal REV are also supplied to the head driver IC 9 (see FIG. 3).

In the head driver IC 9, a drive voltage pulse signal to be applied to each diaphragm 107 of the ink jet head 100, that is, a common electrode is generated based on the above-mentioned supplied signals and the drive voltage Vp supplied from the power supply circuit 10. The drive voltage that is output from the output terminal COM and should be applied to each counter electrode (individual electrode) 109 corresponding to each ink nozzle 105 is output from the number of output terminals SEG corresponding to each individual electrode. The potential difference between these COM output and SEG output is applied to each ink nozzle 105 (between the vibration plate 107 and the counter electrode 109). A drive potential difference waveform in a designated direction is applied during driving (ink ejection), and no drive potential difference is applied during non-driving.

In FIG. 3A, the reference drive voltage pulse signal V3, the control signal LP, the polarity inversion control signal REV, the COM output, the SEG output, and the common drive voltage supplied from the ink jet head controller 2 to the head driver IC 9 are shown. The potential difference (nozzle drive voltage waveform) generated between the electrode and the individual electrode 109 is shown. The print mode shown in this figure is 1 by two consecutive ink droplet ejections (2 shots).
There is a 2-shot / dot mode that forms dot pixels,
The control signal LP controls the one-dot pixel to be performed in two shots.

The polarity reversal control signal REV is for reversing the polarity of the potential difference applied for ejecting ink droplets twice consecutively. By reversing the polarity of the potential difference generated between the common electrode and the individual electrode in this way, residual charge is generated between the electrodes, the electrostatic force fluctuates, and the initial ink ejection characteristics cannot be obtained. The adverse effect can be avoided.

FIG. 3B shows a reference drive voltage pulse signal V for forming one dot in the 2-shot / dot mode.
The voltage waveform of No. 3 is shown. As shown in this figure, the pulse width of one cycle of the voltage waveform of the reference drive voltage pulse signal V3 is Pwia, the pulse widths of the charging portions that rise at a constant gradient are Pwca1 and Pwca2, and after the rising, the voltage becomes a constant voltage. After being held, the pulse width of the discharging portion that falls at a steeper gradient than the charging portion is Pwda
1 and Pwda2, and the pulse widths from the start time of the charging portion to the start time of the discharging portion are Pwa1 and Pwa2.

Referring again to FIG. 2, the ink jet head control unit 2 of this example comprises a drive current detection circuit 22 for detecting the drive current I flowing through the supply line 21 of the reference drive voltage pulse signal V3. The drive current detection circuit 22 detects each drive current flowing through each ink nozzle 105 (between the vibration plate 107 and the counter electrode 109). The detected drive current detected by the drive current detection circuit 22 is supplied to the nozzle failure determination circuit 23.
In the nozzle failure determination circuit 23, based on the detected drive current,
It is determined whether or not an ink ejection failure has occurred in each ink nozzle 105.

The nozzle defect determination circuit 23 of this example determines whether or not an ink ejection defect has occurred in each ink nozzle 105 as follows. FIG. 4 shows the waveform of the drive current I detected when the reference drive voltage pulse signal V3 is applied for one pulse. This drive current waveform indicates, as Io, the drive current waveform detected when all the ink nozzles 105 are not driven when the ink jet head 100 of this example has 128 ink nozzles 105, All ink nozzles 1
The drive current waveform detected when ink droplets are normally ejected from all ink nozzles when 05 is driven is shown as I (128), and when all ink nozzles 105 are driven, The drive current waveform detected when ink droplets are not ejected from the ink nozzle is shown as I (0).

These drive current waveforms Io and I (128)
As can be seen from a comparison between I and (0), the drive current waveform I (0) detected when ink droplets are not ejected from the ink nozzle 105 despite applying the drive voltage pulse is Drive current waveform Io when not driven and drive current waveform I (12) when ink droplets are normally ejected from all ink nozzles
It is different from any of 8). Further, the drive current waveform I (0) has a larger absolute value of the peak current value in the peak waveform portion than the drive current waveform I (128).

More specifically, the peak of the drive current waveform I appears near the end point of rising of the reference drive voltage pulse signal V3 and near the end point of its falling. That is, when the reference drive voltage pulse signal V3 is applied between the vibrating plate 107 and the counter electrode 109, the vibrating plate 107 starts to elastically be displaced by the electrostatic attraction force generated between them and is attracted to the counter electrode 109, Adsorbed on the surface. The capacitance between the vibration plate 107 and the counter electrode 109 changes in inverse proportion to the gap between them, and the drive current I changes in proportion to the time change rate of the capacitance. Therefore, at the time of the rise of the reference drive voltage pulse signal V3, the electrostatic capacitance rapidly decreases, and accordingly, the drive current rises in the positive direction, for example. On the contrary, when the reference drive voltage pulse signal V3 falls, the electrostatic attraction force decreases and the diaphragm 10 attracted to the counter electrode 109.
7 rapidly separates therefrom due to the elastic restoring force. Therefore, the drive current falls in the negative direction.

When bubbles are mixed in the ink pressure chamber 106 and ink is not ejected or cannot be ejected, the ink filling rate in the ink pressure chamber 106 is low. The vibration speed of the plate 107 is increased. As a result, the rate of change in capacitance increases. Therefore, the drive current I has peak waveforms Ia and Ib at the time when the diaphragm 107 is attracted to and released from the individual electrode 109 as shown by the drive current waveform I (0) in FIG. 4A. Appear, and these have steeper waveforms and the absolute values of their peak current values are larger than the corresponding waveform portions that appear during normal driving.

In the nozzle failure determination circuit 22 of this example, paying attention to such characteristic changes in the electrostatically driven ink jet head 100, the presence or absence of ejection failure of ink droplets of the ink nozzle 105 is detected based on the drive current I. I am trying to do it.

In FIG. 4, 128 is shown in order to clarify the difference between the waveforms of the drive current obtained from the normal ink nozzle and the drive current obtained from the defective ink nozzle.
The drive current waveform I (0) when all the ink nozzles are defective and the drive current waveform I (128) when all the 128 ink nozzles are normal are shown. However, this relationship can be similarly applied between the drive current waveform obtained from one normal ink nozzle and the drive current waveform obtained from one defective ink nozzle, although the fluctuation range is small. confirmed. Therefore, it is possible to determine whether each ink nozzle is normal or defective based on such a change in the drive current waveform caused by the inclusion of bubbles.

(Nozzle Defect Discrimination Method) Here, as a method for discriminating whether or not an ink ejection defect has occurred in the ink nozzle 105 performed in the nozzle defect discrimination circuit 23, a peak waveform of the detection drive current I, for example, There is a method of comparing the peak waveform Ia on the positive side with the waveform portion of the drive current obtained from the ink nozzle 105 in the normal state. In this case, the waveform portion of the drive current in the normal state is stored in advance, and the nozzle defect determination circuit 23 compares the waveform portion of the drive current with the peak waveform Ia of the detected drive current I and determines the difference between them. When is larger than a predetermined threshold value, it can be determined that the ejection failure has occurred in the ink nozzle to be measured.

In addition, such a determination may be made by individually applying the drive voltage pulse to the plurality of ink nozzles 105 and individually determining the presence or absence of ejection failure, or at the same time for all the ink nozzles 105. A composite waveform that combines the drive currents that are obtained when a drive voltage pulse is applied to the ink nozzles, and a composite waveform that combines the drive currents that are obtained when simultaneously driving all the ink nozzles in the normal state that are stored in advance. You may make it discriminate | determine by comparing with.

Further, the determination is made by using the peak value of the detection drive current I (the peak value Ipe of the detection drive current I (0) in FIG. 4A) which is previously stored in the drive current obtained from the normal ink nozzle. 4 (the peak value Ip of the drive current I (128) in FIG. 4A), and if the difference exceeds a predetermined threshold value, it is determined that the ink nozzle is defective. May be.

Also in this case, the peak value of the drive current in the normal state is stored in advance, and the peak value of the drive current is compared with the peak value of the detected drive current I in the nozzle failure determination circuit 23. When the difference between them exceeds a predetermined threshold value, it can be determined that the ejection failure has occurred in the ink nozzle to be measured.

In addition, such a determination may be performed by applying drive voltage pulses to a plurality of ink nozzles in order and individually determining the presence or absence of ejection failure, or at the same time for all ink nozzles. The peak value of the composite waveform that combines the drive currents obtained when the drive voltage pulse is applied to the drive current pulse that is obtained by simultaneously driving all the ink nozzles in the normal state stored in advance. The determination may be made by comparing with the peak value of the waveform.

Further, the discrimination can be performed based on the peak waveform appearing in the differential waveform obtained by differentiating the detected drive current waveform. That is, as shown in FIG. 4B, the drive current I (12
In 8), the positive-side peak waveform and the negative-side peak waveforms d1 and d2 appear in the differential waveform D (128) at the rising edge and the falling edge of the current waveform. On the other hand, in the differential waveform D (0) of the drive current in the defective state, after it first rises, it rises again in the same direction and a peak waveform portion appears, so the positive peak waveform d
a and db appear continuously, and the peak waveform dc on the negative side appears immediately after that. Therefore, it is possible to discriminate between normal and defective based on whether or not the peak waveform on the positive side continuously appears. Alternatively, immediately before the fall of the current waveform, it is possible to determine whether the defect is normal or not based on the presence or absence of the peak waveform on the positive side.

The discrimination based on the differential waveform has an advantage of higher sensitivity than the discrimination based on the peak current waveform and the peak value. Also in this case, the determination may be made by individually applying the drive voltage pulse to a plurality of ink nozzles and determining the presence or absence of the ejection failure individually, or at the same time for all the ink nozzles. The determination may be made based on the differentiated waveform obtained by differentiating the combined waveform obtained by combining the drive currents obtained when the drive voltage pulse is applied.

(Driving Voltage Pulse for Defect Determination) Here,
When determining the ink ejection failure of the ink nozzle, the reference drive voltage pulse signal V used for normal ink nozzle drive is used.
A drive voltage pulse for discrimination having a waveform different from that of No. 3 may be applied to each ink nozzle 105.

That is, since the difference between the driving current waveforms detected in the normal state and the defective state is small, the waveform difference between these driving current waveforms is enlarged in order to improve the sensitivity or accuracy of the discrimination. It is desirable to apply a drive voltage pulse. In order to do this, the rising edge of the drive voltage pulse may be made gentle. In other words, the pulse width in FIG. 3B may be lengthened.

Alternatively or in combination with this,
The voltage of the drive voltage pulse may be lowered to reduce the potential difference between the diaphragm 107 and the individual electrode 109. When the potential difference is reduced, if a predetermined amount or more of air bubbles are mixed in the ink pressure chamber 106, the vibrating plate 107 causes the individual electrode 109 to move.
Diaphragm 107 in a normal state without bubbles
It is possible to generate an electrostatic force of a magnitude that does not cause the particles to be attracted to the individual electrode 109. If a drive voltage pulse that can form this state is used, the difference between the drive current waveform in the normal case and the drive current waveform in the case of a defect becomes clearer, and therefore it is possible to distinguish between normal and defective with high sensitivity. It will be possible.

(Nozzle Recovery Process) Next, in the ink jet head drive control device 1 of the present embodiment, in addition to the above configuration, as shown by an imaginary line in FIG. The nozzle recovery operation control circuit 31 for controlling the recovery operation may be provided. The nozzle recovery operation control circuit 31 is, for example,
This is a circuit for controlling the recovery operation of the ink nozzle using the ink suction mechanism 32 that recovers the nozzle clogging by sucking the ink from the ink nozzle 105. The ink suction mechanism 32 includes, for example, a head cap 32a that can be capped on the ink nozzle surface 100a of the inkjet head 100, an ink suction pump 32b, and a collection unit 32c that collects waste ink sucked by the ink suction pump 32b. Since a known mechanism having the above can be used as it is, further description will be omitted in this specification.

In the nozzle recovery operation control circuit 31 of this example,
When the nozzle failure determination circuit 23 detects that there is a defective ink nozzle, the ink suction mechanism 32 is driven at a timing that does not interfere with the printing operation, and ink is sucked from the ink nozzle. Then, the air bubbles mixed in are removed.

If this configuration is adopted, conventionally, regardless of the presence / absence of defective ink nozzles, it is possible to periodically eject or suck ink from each ink nozzle to discharge defective ink or bubbles to the outside. It is possible to suppress waste of ink as compared with the head recovery process that is performed.

[0054]

As described above, in the present invention, in the electrostatic drive type ink jet head, the drive current generated between the diaphragm and the individual electrode due to the inclusion of bubbles in the ink pressure chamber. Of the ink ejection failure by detecting this drive current and comparing it with the drive current obtained in the normal state, or by comparing the drive current obtained from each ink nozzle with each other. The presence / absence of an ink nozzle in which ink cannot be ejected is detected.

Therefore, according to the present invention, by simply adding a mechanism for detecting the drive current to the existing ink jet head drive control device, ink ejection failure due to the inclusion of bubbles can be performed easily and inexpensively. It is possible to detect the presence or absence of an ink nozzle that is

By applying the present invention, it is possible to perform a head recovery operation including removal of mixed bubbles by using a head recovery mechanism such as an ink suction mechanism only when an abnormality occurs in an ink nozzle. Therefore, compared with the case where the head recovery operation is performed regularly and the ink is sucked from the ink nozzles regardless of the state of the ink nozzles,
Ink waste can be suppressed, and efficient head recovery processing can be realized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an electrostatic drive type inkjet head to which the present invention can be applied.

FIG. 2 is a schematic block diagram showing an example of a drive control device for an inkjet head according to the present invention.

3 is a timing chart showing signal waveforms of respective parts in the drive control device of FIG. 2, and FIG. 3A is a signal output from the inkjet head control unit and a signal output from a head driver IC of FIG. The potential difference (nozzle drive waveform) generated between the electrodes is shown, and (B) shows the waveform of the reference drive voltage pulse signal V3 for one dot.

4A and 4B are diagrams for explaining a detection operation by the ink ejection failure detection circuit of FIG. 2, in which FIG. 4A is a drive current Io obtained in a non-driving state and a drive current I (128) obtained in a normal driving state. ), And a drive current I (0) obtained when ink cannot be ejected, and (b) is a differential waveform diagram of drive currents I (128) and I (0).
(C) is a waveform diagram showing the reference drive voltage pulse signal V3 for one pulse.

[Explanation of symbols]

1 Drive controller for electrostatic ink jet head 2 Inkjet head controller 6 Drive pulse generation circuit 8 head substrate 9 Head drive IC 22 Drive current detection circuit 23 Nozzle failure determination circuit 31 Head Recovery Processing Control Circuit 32 ink suction mechanism 100 Electrostatic drive inkjet head 105 ink nozzles 106 ink pressure chamber 107 Vibration plate (common electrode) 109 Individual electrode (counter electrode) 110 ink droplets Io Drive current obtained when not driven I (128) Drive current obtained during normal drive I (0) Drive current obtained when ink ejection is defective D (128) Differential waveform of drive current I (128) D (0) Differential waveform of drive current I (0) Ia, Ib peak waveform Ip, Ipa peak value

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C056 EA14 EA15 EA25 EB03 EB08                       EB39 EB40 EC08 EC24 EC42                       EC49 EC57 EC60 EC73 FA02                 2C057 AF72 AF80 AL03 AL13 AM06                       AM33 BA03 BA15

Claims (15)

[Claims] 1. An ink nozzle, an ink pressure chamber communicating with the ink nozzle, a vibrating plate forming a part of the ink pressure chamber and elastically displaceable in an out-of-plane direction, and the vibrating plate. In a drive control device of an inkjet head having a counter electrode arranged to face each other, in order to eject an ink droplet from the ink nozzle,
A drive voltage pulse generating means for applying a drive voltage pulse having a predetermined waveform between the diaphragm and the counter electrode, and a drive current generated between the diaphragm and the counter electrode when the drive voltage pulse is applied are detected. And a drive current detection unit that determines whether or not ink droplets are normally discharged from the ink nozzle based on the detected drive current detected by the drive current detection unit. A drive control device for an inkjet head, characterized in that 2. The drive control device for an inkjet head according to claim 1, wherein the ink ejection failure determination unit makes a determination based on a current waveform of the detected drive current. 3. The drive control device for an inkjet head according to claim 1, wherein the ink ejection failure determination unit makes a determination based on a peak current value of the detected drive current. 4. The drive control device for an inkjet head according to claim 1, 2 or 3, wherein the ink ejection failure determination means performs determination based on a differential waveform of the detected drive current. 5. The drive current detection means according to claim 1, 2, 3 or 4, in a period in which the diaphragm is elastically displaced toward the counter electrode, or in a direction in which the diaphragm is separated from the counter electrode. A drive control device for an jet head, wherein the drive current is detected during a period of elastic displacement. 6. The ink ejection failure determination means according to claim 2, 3, 4 or 5,
A drive control device for an jet head, wherein the determination is made by comparing with a normal drive current stored and held in advance. 7. The ink jet defect determination device according to claim 6, further comprising a plurality of the ink nozzles, a plurality of the ink pressure chambers, and a plurality of sets of the vibrating plate and a counter electrode. The determination is performed by comparing the combined current of the detected driving currents obtained when the driving voltage pulse is simultaneously applied between the diaphragm and the counter electrode with the combined current of the braking driving currents stored in advance. An inkjet head drive control device. 8. The ink ejection failure according to claim 2, comprising a plurality of the ink nozzles, a plurality of the ink pressure chambers, and a plurality of sets of the vibration plate and the counter electrode. The discriminating means discriminates by mutually comparing the respective detected drive currents obtained when the drive voltage pulse is applied between the plurality of sets of the diaphragm and the counter electrode. Control device. 9. The driving voltage pulse generating means according to claim 1, wherein the driving voltage pulse generating means includes a first driving voltage pulse for ejecting ink droplets for printing, and the first driving voltage pulse. It is possible to generate a second drive voltage pulse having a gentler rising waveform than that of the voltage pulse, and the ink ejection failure determination means makes a determination based on a drive current generated when the second drive voltage pulse is applied. A drive control device for an inkjet head, characterized in that 10. The drive voltage pulse generating means according to claim 1, wherein the drive voltage pulse generating means includes a first drive voltage pulse for ejecting ink droplets for printing, and the first drive voltage pulse. It is possible to generate a second drive voltage pulse having a voltage value smaller than that of the voltage pulse, and the ink ejection failure determination means makes a determination based on a drive current generated when the second drive voltage pulse is applied. A drive control device for a characteristic inkjet head. 11. The ink recovery apparatus according to claim 1, further comprising a nozzle recovery unit for recovering an ink nozzle having an ink ejection failure, wherein the ink ejection failure determination unit determines that the ink ejection failure has occurred. In the case where it is determined that there is, a recovery control operation of the ink nozzle is performed by the nozzle recovery means, and a drive control device for an inkjet head. 12. The drive control device for an inkjet head according to claim 11, wherein the nozzle recovery unit is an ink suction unit that sucks ink from the ink nozzle. 13. An ink ejection failure detecting an ejection failure of an ink droplet in an inkjet head which ejects an ink droplet from an ink nozzle by utilizing an electrostatic force generated by applying a driving voltage pulse between opposed electrodes. A detection method, wherein a drive current waveform generated between the opposed electrodes is measured, and based on the drive current waveform, it is determined whether or not an ink droplet is normally ejected from the ink nozzle. Method for detecting defective ink ejection of inkjet head. 14. The method according to claim 13, wherein the determination is performed based on a peak current value of the drive current waveform. 15. The method according to claim 13 or 14, wherein the determination is performed based on a differential waveform of the drive current waveform.