JPH1158704A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high gradation image having no density unevenness and no banding by controlling a driving voltage value of a driving voltage waveform selected based on ink discharge amount unevenness correction data between a plurality of nozzles. SOLUTION: Ink discharge means 1-1 to 1-N are respectively provided at nozzles. Ink discharge amount unevenness correcting means 11-l to 11-N are respectively provided at the means l-l to l-N each to supply an output for controlling a driving voltage value of a voltage waveform selected by each of selectors 3-l to 3-N based on unevenness correction data of the ink discharge amounts generated between the plurality of the nozzles formed by measuring in advance, thereby correcting the ink discharge amounts. Thus, unevenness of the ink amount is corrected at the time of ink discharging, and uneven density or banding for causing deterioration of an image is suppressed. Hence, gradation image of high image quality can be recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus for recording an image by driving an ink jet recording head having a plurality of nozzles.

[0002]

2. Description of the Related Art An ink jet recording apparatus is an apparatus for recording an image or a character on a recording member by discharging ink droplets from a nozzle. Various methods are used for the ink discharging means. Here, an example using a heating element and a piezoelectric element will be described below. In the case of using a heating element as the ink discharging means, the film is boiled by the thermal energy generated from the element to which the current is applied, and the ink droplet is discharged by the expansion pressure of the bubble generated in the ink at that time. . Also, those using piezoelectric elements such as piezo
Ink droplets are ejected by mechanical pressure generated by extension of a piezoelectric element to which a voltage is applied.

In order to drive a recording head having such an ink ejection means, it is necessary to apply a predetermined drive waveform to the ink ejection means. FIG. 14 shows an example of such an arrangement in Japanese Patent Application Laid-Open No. Hei 4-310747. The voltage waveform is output from the scanning voltage generation circuit 101,
The recording elements (piezoelectric elements) 105 to 107 are supplied to the respective recording elements through output connections of a circuit commonly connected between the recording elements. Further, transistors 111 to 113 in which diodes 108 to 110 controlled by a recording signal are connected in antiparallel to the recording elements 105 to 107 are connected. The recording signal 103 is taken into the shift registers 117 to 119 in synchronization with the shift clock signal 104, and the latch signal 1
02, the data is transferred to the latches 114 to 116. Then, the recording elements 105 to 107 are driven based on the recording signals stored in the latches 114 to 116, and the image or the character is binary-recorded by ejecting / not ejecting the ink droplet. For example, when the print signal stored in the latches 114 to 116 is a signal of “discharge”, the print element 1
Transistors 111 to 113 connected to 05 to 107
Is turned on, and a voltage waveform is applied from the scanning voltage generation circuit 101 to the recording elements 105 to 107 to eject ink droplets.

[0004] However, in such binary recording, it is difficult to express gray scale in detail, and it is difficult to reproduce sufficient gray scale. In order to print an image with shading such as a photograph, it is necessary to change the recording dot diameter according to the shading level of the image to express halftone. As a halftone expression method using such dot diameter modulation, a method of modulating the ejection amount of ink droplets by controlling the drive time and drive voltage of a recording element has been used. When the dot diameter modulation is performed by the above-described conventional circuit, since the recording elements 105 to 107 are commonly connected in the scanning voltage generation circuit 101, the same driving voltage waveform is applied to each recording element even when the driving voltage is changed. There was a problem that only simultaneous application was possible.

[0005] As a head driving device for solving the above-mentioned problems, for example, in Japanese Patent Application Laid-Open No. Hei 4-316851, FIG.
As shown in FIG. 5, a drive circuit capable of changing the waveform width and voltage value of the voltage waveform applied to each piezoelectric element is used. FIG. 15 is an example of a circuit that changes the waveform width of the voltage waveform applied to the plurality of piezoelectric elements PZT1 to PZTn.
Hereinafter, description will be made with reference to the timing chart shown in FIG. The shift register 214 receives the clock signal CP and the data signal DAT and outputs pulse signals Q1 to Qn, as shown in FIG. Also, the pulse width generation circuit 2
Reference numeral 15 sets a pulse width TW1 to TWn of a drive waveform applied to each piezoelectric element based on gradation data of a recorded image, and outputs a pulse signal PWM. Gate circuits 231 to 23n
The high-voltage amplifiers 241 to 2 correspond to the pulse signals PWM in accordance with the pulse signals Q1 to Qn input from the shift register 214 as shown in the timing chart of FIG.
4n. Thereby, the control voltage generation circuit 212
Pulses V1 to Vn of constant voltage value VH output from
Is applied to each of the piezoelectric elements PZT1 to PZTn for a time equal to the pulse width of the pulse signal PWM, and ink is ejected from each nozzle for a time corresponding to the pulse width.

FIG. 17 shows a plurality of piezoelectric elements PZT1 to PZT1.
This is an example of a circuit that changes the drive voltage applied to PZTn. As shown in the timing chart of FIG. 18, the pulse signal PWM from the pulse width generation circuit 215 is fixed at a high level, and the pulsed high voltage from the control voltage generation circuit 217 is output. Vp
Are set to voltage values corresponding to the gradation data, whereby the high-voltage pulses V1 to V applied to the respective piezoelectric elements PZT1 to PZTn.
The amount of ink ejected from each nozzle is adjusted by changing the voltage value of n.

Further, since the control range of the ink droplet ejection amount that determines the dot diameter is narrow only by changing the waveform width and voltage value of the voltage waveform applied to the recording element, sufficient halftone expression cannot be performed. A method of obtaining a wide dot diameter modulation range by changing the voltage waveform itself has also been proposed. One example is disclosed in Japanese Patent Application Laid-Open No. 9-11457. FIG. 19 is a schematic view of the ink jet driving device disclosed in the above publication. In the drive device shown in FIG. 19, the system control means 3
A plurality of drive voltage waveforms S0 to S3 corresponding to the ink ejection amount are generated based on the generation timing signal PS from the controller 21, and the drive unit waveforms are generated by the drive unit 322 on the recording element made of a piezoelectric material based on the gradation data of the recorded image. Gradation expression is performed by selectively giving and changing the size of the recording dot diameter.

Here, in order to convert the gradation data into a selection signal of a drive voltage waveform, first, the gradation data is fetched into the storage means 323, and the signal processed by the signal processing means 327 is sent to the level converter 331. And the level converter 3
The signal whose level has been converted at 31 is transferred to a transfer gate 332.
, One of the transfer gates conducts and one of the drive waveforms is applied to the recording element. As a result, an ink amount corresponding to the drive waveform can be ejected from each nozzle, and the ink ejection amount can be controlled in a wider area as compared with the method of controlling the drive voltage value and the drive waveform width.

More specifically, the storage means 323 includes a shift circuit 324 for shifting and storing 2-bit grayscale data from the system control means 321 as a binary signal, and a latch circuit for outputting the output of the shift circuit 324 at a predetermined timing. 3
25, a 2-bit latch circuit 325 for converting serial data to parallel data,
It comprises a decoder 326 which converts 25 outputs to 4 outputs and makes one of them a positive output. The signal processing unit 327 includes an AND gate 328 that outputs four outputs from the storage unit 323 in synchronization with an enable signal from the system control unit 321, and a system control unit 321.
, And an OR gate 329 for passing the processing signals CS0 and CS3. Drive unit 3
Reference numeral 22 includes a level converter 331 that converts the output of the signal processing unit 327 to a predetermined level and outputs the output to the control terminals of the four transfer gates 332. With such a configuration, a required amount of ink is ejected from each nozzle.

Further, Japanese Patent Application Laid-Open No. 1-130949 discloses a circuit configuration in which an auxiliary pulse is added to a main waveform to create a complicated drive voltage waveform.

[0011]

As described above, an ink-jet head having a plurality of nozzles by using a method of controlling a drive voltage, a drive waveform width, and a drive voltage waveform itself to modulate a recording dot diameter. Is driven, the amount of ink ejected from each nozzle varies. The variation in the amount of ink discharged from each nozzle causes uneven density and band-like noise called banding in the head scanning direction. In order to prevent such a cause of image quality deterioration, it is necessary to correct the variation in the ink discharge amount between the nozzles and discharge the same amount of ink from each nozzle. In the circuit configuration of the above-mentioned Japanese Patent Application Laid-Open No. 1-130949, it is possible to use the variation of the ink ejection amount between the nozzles for correction, but there is a disadvantage that the correction amount cannot be changed at every ink ejection. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made in consideration of the above-described problem. It is an object of the present invention to provide an ink jet recording apparatus capable of obtaining a high gradation image without density unevenness and banding.

[0013]

An ink jet recording apparatus according to the present invention comprises a plurality of ink ejection means provided for each nozzle for ejecting ink from a plurality of ink chambers, and a plurality of ink ejection means for driving the ink ejection means. A plurality of drive voltage waveform generating means for generating drive voltage waveforms having different shapes, and a drive voltage waveform selecting means for selecting one of the plurality of different drive voltage waveforms according to gradation data of a recorded image And the drive selected by the drive voltage waveform selection means based on the correction data of the variation in the amount of ink ejection generated between the plurality of nozzles, which is provided in correspondence with the plurality of ink ejection means and is created by measuring in advance. By supplying an output obtained by controlling the drive voltage value of the voltage waveform to each of the ink ejection means, a plurality of ink ejection amount variations for correcting the ink ejection amount are compensated. It is characterized in that a means.

Further, the ink discharge amount variation correction means changes the ink discharge amount correction data for each different drive voltage waveform.

The ink discharge amount variation correcting means adjusts the ratio of the drive voltage value to the transition time from when the absolute value of the voltage of the drive voltage waveform changes from the maximum value to the standby state, thereby controlling the plurality of nozzles. The present invention is characterized in that variations in the ink ejection amount occurring between them are corrected.

Further, according to another aspect of the present invention, there is provided an ink jet recording apparatus comprising: a plurality of ink ejection means provided for each nozzle for ejecting ink from a plurality of ink chambers; and a plurality of different shapes for driving the ink ejection means. A plurality of drive voltage waveform generating means for generating the drive voltage waveforms, a selecting means for selecting at least two of the plurality of drive voltage waveforms according to gradation data of a recorded image, and at least two of the selected at least two drive voltage waveforms. A plurality of adding means for supplying an output obtained by adding the driving voltage waveforms to each of the ink discharging means is provided.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, an ink jet recording apparatus according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating an example of the ink jet recording apparatus according to the first embodiment. In FIG. 1, 1-1, 1-2,.
.., 1-N is an ink ejection means, such as a piezo, for generating pressure in the ink chamber to eject ink in the ink chamber, and is provided for each nozzle. 2-1, 2-2,
.., 2-M are driving voltage waveform generating means necessary for driving the ink discharging means, 3-1, 3-2,.
-N is a selector provided for each ink ejection means, and selects a desired drive voltage waveform from the M waveforms according to the transmitted drive voltage waveform selection data. Reference numerals 4 and 5 denote a latch and a shift register, respectively. L-bit drive voltage waveform selection data 9 and a clock signal 8 are input to the shift register 5, and a latch signal 10 is input to the latch 4. 6-1 and 6-N are latches 4
, 7-2,..., 7-N are output terminals of the shift register 5.

Further, 11-1, 11-2,..., 1
1-N is provided for each nozzle (each ink discharging means), and selectors 3-1 to 3-N are provided based on the correction data of the variation in the amount of ink discharge generated between a plurality of nozzles, which are created by measuring in advance. Is output by controlling the drive voltage value of the drive voltage waveform selected by
N is an ink ejection amount variation correction unit that corrects the ink ejection amount by supplying the ink to the N.

The apparatus shown in FIG. 1 can change the size of the recording dot diameter by selectively supplying a plurality of drive voltage waveforms generated from a common circuit to the ink discharge means, thereby causing uneven density and banding. , 1-2,..., 1
1-N. In order to control the amount of ink ejected from each nozzle, each of the ink ejection units 1-1, 1-
, 1-N, selectors 3-1, 3-2,..., 3-N in accordance with L-bit drive voltage waveform selection data.
The drive voltage waveform selected in is provided.

The drive voltage waveform selection data is generated based on the gradation data of the recorded image, and sent from the host to the shift register 5. As shown in FIG. 2, the shift register 5 fetches L-bit drive voltage waveform selection data in synchronization with the input clock signal 8, and outputs the fetched drive voltage waveform selection data 9 to output terminals 7-1 and 7-. 2, ...,
Output in order from 7-N. The drive voltage waveform selection data 9 output from the output terminals 7-1 to 7-N is stored in the latch 4, and synchronized with the latch signal 10, the output terminals 6-1 and 6-.
, 6-N are input to the selectors 3-1 to 3-N. In each of the selectors 3-1 to 3-N, based on the input drive voltage waveform selection data 9, each of the ink discharge units is selected from among the drive voltage waveform generation units 2-1 to 2-2,. One, a drive voltage waveform given to 1-1, 1-2,..., 1-N is selected and sent to each ink ejection unit.

The driving voltage waveform generating means 2-1, 2-2,.
.., M types of drive voltage waveforms generated from 2-M have various shapes such as a triangular wave, trapezoidal wave, and rectangular wave as shown in FIG. The waveform from which the diameter can be obtained is determined by simulation, experiment, or the like. Then, these M types of drive voltage waveforms are converted to the respective ink ejection units 1-1, 1--1.
2,..., 1-N, the ink ejection amount can be modulated in M steps. The drive voltage waveform selection data amount L bits and the number M of drive voltage waveforms are set so that the relationship of 2 ^L ≧ M is satisfied.

Ink ejection amount variation correction means 11-1 to 11-1
11-N is a device in which an amplifier 12-N for amplifying the drive voltage waveform signal as shown in FIG. 4 and a variable resistor 13-N for adjusting the amplification value of the amplifier are combined. The driving voltage of the driving voltage waveform can be adjusted in order to discharge the ink. Since the drive voltage needs to be adjusted according to the variation of the ink discharge amount generated between the nozzles, the change in the ink discharge amount when the drive voltage value is changed is examined in advance, and the relationship between the drive voltage value and the ink discharge amount is determined. A correction conversion table shown below is created. The above-described correction conversion table is required when correcting the variation in the ink ejection amount.

Next, a description will be given of a method of correcting variations in the ink ejection amount. First, an arbitrary drive voltage waveform is applied to each ink ejection unit, and the amount of ink ejected from each nozzle is measured. Then, an error from the ink amount ejected from each nozzle is calculated by comparing with a preset ink ejection amount reference value. Based on the calculated error and the variation correction table described above, the resistance value of the variable resistor 13-N provided in the amplifier 12-N is adjusted to provide a drive voltage waveform to each of the ink ejection units 1-1 to 1-N. A desired amount of ink is ejected from the nozzle.

In this manner, the selector 3 based on the ink ejection amount variation correction data generated between a plurality of nozzles and measured in advance by the ink ejection amount variation correction means 11-1 to 11-N. By supplying an output obtained by controlling the drive voltage value of the drive voltage waveform selected by -1 to 3-N to each of the ink ejection units 1-1 to 1-N, the ink ejection amount is corrected, so that each nozzle is corrected. This has the effect of suppressing variations in the amount of ink ejected during printing and obtaining a recorded image free from uneven density and banding.

Embodiment 2 Next, an ink jet recording apparatus according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 5 is a schematic configuration diagram illustrating an example of an ink jet recording apparatus according to the second embodiment. 5, the same components as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. As new codes, 14-1, 14-
,..., 14-N are ink ejection amount variation correcting means B provided for each nozzle (each ink discharging means) according to the second embodiment, and have a function of converting correction data into drive voltage values. The correction data of the ink ejection amount is changed for each different drive voltage waveform.

Reference numeral 15 denotes a shift register B, 16-
, 16-N are output terminals of the shift register B, 17 is a latch B, 18-1, 18-2,.
.., 18-N are output terminals from the latch B, 19 is data for correcting variation in ink ejection amount for each nozzle, 20 is a clock signal B, and 21 is a latch signal B.

The ink jet recording apparatus shown in FIG. 5 selectively gives a plurality of different drive waveforms to an ink discharge means to an ink jet head having a plurality of nozzles to perform gradation expression, and performs a time lapse, a change in an external environment, and the like. And a correcting means for correcting the variation of the ink discharge amount generated between the nozzles. The procedure for correcting the variation in the ink ejection amount in the apparatus shown in FIG. 3 is the same as that in the first embodiment. First, M types of different drive voltage waveforms are applied to each ink ejection unit, and the amount of ink ejected from each nozzle is measured. Next, an error in the ink ejection amount of each nozzle is calculated from the reference value of the ink ejection amount set for each of the M types of different drive voltage waveforms and the above-described measured value, and the C-bit variation for each drive voltage waveform and each nozzle is calculated. Create correction data. At this time, the correction data is created based on an ink ejection amount error / correction data conversion table describing the relationship between the drive voltage and the ink ejection amount prepared in advance for each drive voltage waveform.

Then, based on the correction data, a correction table is prepared using the nozzle and the drive voltage waveform as parameters, and stored in a memory or the like. After the drive voltage waveform selection data is determined based on the image data to be recorded, the variation correction data corresponding to each ink ejection unit and the drive voltage waveform is read from the above-described correction conversion table and sent to the shift register 15. The shift register 15 captures the variation correction data 19 in synchronization with the input clock signal 20, and outputs the output terminals 16-1, 16-2,.
Output in order from -N. The variation correction data 19 output from the shift register 15 is stored in the latch 17,
The output terminals 18-1 and 18- are synchronized with the latch signal 21.
, 14-N,..., 18-N, respectively.
-N.

Ink ejection amount variation correction means 14-1 to 14-1
14-N has a function of converting C-bit correction data into a drive voltage value, and outputs a drive voltage waveform adjusted based on the variation correction data 19 to each of the ink ejection units 1-1 to 1-N.
1-N, a desired amount of ink is ejected from each nozzle. In this way, by correcting the drive voltage for each nozzle according to the variation in the ink ejection amount, it is possible to suppress density unevenness and banding, which are causes of image quality deterioration.

Embodiment 3 When an ink discharge unit such as a piezo element is used, the amount of ink discharge is determined by the ratio of the drive voltage value Vd to the time Tf until the voltage value enters a standby state after the drive voltage waveform is applied to the ink discharge unit. Change. For example, in the case of the drive voltage waveform as shown in FIG. 6, that is, in the case of the drive voltage waveform including the rise time Tr, the voltage holding time Th, the fall time Tf, and the drive voltage value Vd, the change in the slope Vd / Tf of the fall portion The ejection amount of the ink changes as shown in FIG. Here, using such characteristics, a means for adjusting the slope Vd / Tf of the falling portion of the drive voltage waveform is used to correct the variation in the amount of ink ejected between a plurality of nozzles.

The ink ejection amount variation correction means according to the third embodiment uses the data shown in FIG.
, The shift register 25, the latch 27, Vd
/ Tf is provided. As means for adjusting the slope Vd / Tf of the falling portion of the drive voltage waveform, U correction transistors 29-1, 19-2,.
., 29-U can be easily realized. For example, in the case of the driving voltage waveform as shown in FIG. 6, the slope Vd / Tf of the falling portion of the driving voltage waveform depends on the current amplification factor _hFE of the transistor shown in FIG. By using this characteristic to change the current amplification factor h _FE of the transistor, the slope of the falling part of the drive voltage waveform, Vd /
Tf can be adjusted. In the third embodiment, instead of making the value of the current amplification factor h _FE of the transistor shown in FIG. 9 variable, the current amplification factor h _FE according to Vd / Tf is changed.
The fall time Tf is controlled using a plurality of transistors different from each other and a selector for switching these transistors.

FIG. 8 is a configuration diagram of an ink jet recording apparatus according to Embodiment 3 having the configuration of the above-described Vd / Tf control means. 8, the same parts as those in the first and second embodiments shown in FIGS. 1 and 5 are denoted by the same reference numerals, and the description thereof will be omitted. As a new code, 22 is a clock signal C, 23 is variation correction data, 24 is a latch signal C,
25 is a shift register C, 26-1 to 26-N are output signals from the shift register C, 27 is a latch C, 28-1
28 to N are output signals from the latch C. Also, 2
Correction transistors 9-1 to 29-U having different current amplification factors h _FE are switched by the selector C. 30 is a transistor through which current always flows,
31-1 is a selector C, 32-1 is an amplifier, and U is switched by the selector C for each ink discharging means.
It includes one correction transistor 29-1 to 29 -U and one transistor 30 through which current always flows.

[0033] Since the driving voltage value, as described above the ratio of falling time Tf and the drive voltage Vd to a standby state can correspond to the current amplification factor h _FE of the transistor, the current amplification factor h _FE Different correction transistors 29-
By selectively passing a current through 1 to 29-U, a value of a slope Vd / Tf of a falling portion of a desired driving voltage waveform can be obtained. Here, the switching of the correction transistor is performed based on the correction data calculated from the variation in the ink ejection amount. The correction data is set to M
It is created based on the error between the reference value of the amount of ink ejected when different types of drive voltage waveforms are applied and the amount of ink actually ejected from each nozzle, and the relationship between Vd / Tf and the amount of ink ejected. Value. From these correction data, a correction table corresponding to the nozzle and the drive voltage waveform is created and stored in a memory or the like.

After determining drive voltage waveform selection data to be given to each ink ejection means on the basis of image data to be recorded, variation correction data 23 corresponding to each ink ejection means and drive voltage waveform is read out from the above-described correction table, and the shift register 25 is read. Send to The shift register 25 takes in the variation correction data 23 in synchronization with the input clock signal 22 and sends it to the latch 27 and the selector 31-1. The selector 31-1 switches the correction transistor based on the variation correction data, and supplies a current to one or a plurality of correction transistors. Here, V
In order to correct the variation of the ink ejection amount between the nozzles according to the value of d / Tf, the timing of inputting the latch signal 24 is such that a drive voltage waveform is applied and the ink ejection unit shifts to a standby state as shown in FIG. Immediately before. In this way, by suppressing the variation in the amount of ink ejected from each nozzle, it is possible to prevent density unevenness and banding, which cause image quality deterioration, and to print a high-quality image.

Embodiment 4 FIG. Next, an ink jet recording apparatus according to Embodiment 4 of the present invention will be described with reference to the drawings. FIG. 11 is a schematic configuration diagram of an ink jet recording apparatus according to the fourth embodiment. In FIG. 11, 1-3, 6-
1 to 6-N and 7-1 to 7-N are the first embodiment shown in FIG.
Since it is the same as that of FIG. As new codes, reference numerals 40 and 41 denote a latch and a shift register, respectively. The latch signal 10 is input to the latch 40, and the L + K-bit drive voltage waveform selection data 42 and the clock signal 8 are input to the shift register 41. Also, 43-1 to 43-
J is a second driving voltage waveform generating means for mainly correcting the driving voltage waveforms from the driving voltage waveform generating means 2-1 to 2-M, and 44-1 to 44-N are each for each ink discharging means. The second selector provided in (1) selects a desired driving voltage waveform from the J second driving voltage waveform generating means according to the transmitted driving voltage waveform selection data.

That is, in the fourth embodiment, another set of the drive voltage waveform generating means and the selector in the first embodiment is provided for each ink discharging means. Therefore, correspondingly, the second output terminal 45 is connected to the latch 40.
The shift register 41 has second output terminals 46-1 to 46-N. Hereinafter, 2-1
-N, 3-1 to 3-N, 6-1 to 6-N, 7-1
7-N will be referred to as a first drive voltage waveform generator, a first selector, a first output terminal of a latch, and a first output terminal of a shift register, respectively. For each ink ejection means,
The first selector 3 and the second selector 44 constitute a selecting means 48 for selecting at least two drive voltage waveforms. Reference numerals 47-1 to 47-N denote addition means provided for each ink ejection means.
-1 to 3-N and second selectors 44-1 to 44-N
The two drive voltage waveforms selected by the above are added in an analog manner to create a voltage waveform to be applied to each ink ejection unit.

The adding means 47 is specifically configured as shown in FIG. In FIG. 12, reference numeral 51 denotes an operational amplifier, and R1, R2, and R3 denote resistors. When an output signal 52 of the first selector 3 and an output signal 53 of the second selector 44 are input, a waveform obtained by adding both is output. Further R3
/ R2 times and output. Incidentally, the second waveform selection data amount K bits between the number J of the second drive voltage waveform generating means is composed relationship 2 ^K ≧ J.

The operation of selecting one waveform from the drive voltage waveform generating means is the same as in the first embodiment. However,
In the first embodiment, drive voltage waveform selection data 9 is L
In contrast to the bits, the drive voltage waveform selection data 42 according to the fourth embodiment is L + K bits. Among them, the first selectors 3-1 to 3-1 to 3-3 are in accordance with L-bit data.
By -N, one of the first drive voltage waveform generating means 2-1 to 2-M is selected for each ink ejection means, and the second selectors 44-1 to 44-N operate according to K-bit data. Second drive voltage waveform generating means 43-1 to 43-J
Is selected from the other. Ink ejection means 1-1
The selected two waveforms are added to .about.1-N.
1 to 47-N.

Here, in FIG. 13, (a) is selected from, for example, the first drive voltage waveform generating means. If (d) is selected from the second driving voltage waveform generating means, the driving voltage waveform after addition remains as (a),
If (e) is selected, the fall time can be made slightly longer, and if (f) is selected, the fall time can be made a little longer. As described in the third embodiment, since the ink discharge amount can be slightly controlled by the difference in the fall time, the discharge amount variation between the nozzles depends on which of (d) to (f) is selected. Can be corrected. This is the same when a waveform other than (a) is selected in the first drive voltage waveform generation means. In the fourth embodiment, since the above-described correction can be performed each time ink is ejected, it is possible to correct the variation in the ink ejection amount of each nozzle in any gradation data.
High-quality images can be obtained by preventing density unevenness and banding that cause image quality deterioration.

In the fourth embodiment, two waveforms (one each) are selected using the first selector and the second selector.
A special selector that can select any two (or more) of the drive voltage waveform generating means may be used. In this case, the driving voltage waveform generating means does not need to be particularly divided into the first and second driving voltage waveform generating means. Further, in the fourth embodiment, an example in which the main waveform and the correction waveform are added has been described. However, the two waveforms do not necessarily have to be in a main-sub relationship, and the addition can change the waveform more dynamically. You may let it.

[0041]

As described above, according to the present invention, a plurality of ink ejection means provided for each nozzle for ejecting ink from a plurality of ink chambers and a plurality of different ink driving means for driving the ink ejection means are provided. A plurality of driving voltage waveform generating means for generating a driving voltage waveform having a shape; and a driving voltage waveform selecting means for selecting one of the plurality of different driving voltage waveforms according to gradation data of a recorded image; A drive voltage waveform provided by the drive voltage waveform selecting means based on the correction data of the ink ejection amount generated between the plurality of nozzles, which is prepared and measured in advance, corresponding to the plurality of ink discharge means; A plurality of ink ejection amount variation correction means for correcting the ink ejection amount by supplying an output obtained by controlling the drive voltage value to each of the ink ejection means. Correcting the variation of the ink amount at the time of ink discharged can be suppressed density unevenness and banding causes deterioration of image quality can be recorded tone image of high quality.

Further, since the ink ejection amount variation correction means makes it possible to change the ink ejection amount correction data for each different drive voltage waveform, it is possible to correct variations in ink ejection amount between nozzles with high accuracy, A high-quality gradation image without unevenness or banding can be recorded.

Further, the ink discharge amount variation correcting means adjusts the ratio of the transition time from the maximum value of the voltage of the drive voltage waveform to the standby state to the standby state and the drive voltage value, thereby controlling the plurality of nozzles. Since the variation of the ink discharge amount occurring during the correction is corrected, the correction data of the ink discharge amount can be changed each time for each drive voltage waveform, and a high quality image without density unevenness and banding can be recorded. it can.

According to another aspect of the present invention, there is provided an ink jet recording apparatus comprising: a plurality of ink ejection means provided for each nozzle for ejecting ink from a plurality of ink chambers; and a plurality of ink ejection means for driving the ink ejection means. A plurality of drive voltage waveform generating means for generating drive voltage waveforms having different shapes; a selecting means for selecting at least two of the plurality of drive voltage waveforms according to gradation data of a recorded image; Since there are provided a plurality of adding means for supplying an output obtained by adding two drive voltage waveforms to each of the ink discharging means, gradation can be expressed by dot diameter modulation,
By selecting two or more drive voltage waveforms and adding them, the shape of the drive voltage waveform can be delicately deformed.Therefore, it is possible to correct the variation of the ink ejection amount for each nozzle, High-quality images without banding can be recorded.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an inkjet head driving device of an inkjet recording device according to a first embodiment of the present invention.

FIG. 2 is a timing chart illustrating a time transition of capturing drive voltage waveform data into a shift register according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a relationship between a drive voltage waveform for driving an ink ejection unit such as a piezo and a change in dot diameter according to the first embodiment of the present invention;

FIG. 4 is a diagram showing one of a plurality of ink ejection amount variation correction means according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a configuration of an inkjet head driving device of an inkjet recording device according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram showing an example of a drive voltage waveform according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a relationship between a ratio Vd / Tf of a time Tf until a voltage value becomes a standby state after a drive voltage waveform is applied to an ejection unit and a drive voltage value Vd, and an ink ejection amount.

FIG. 8 is a diagram showing a configuration of an inkjet head driving device of an inkjet recording device according to Embodiment 3 of the present invention.

FIG. 9 is a diagram illustrating a method of adjusting a ratio Vd / Tf between a time Tf and a drive voltage value Vd until a voltage value enters a standby state after a drive voltage waveform according to a third embodiment of the present invention is applied to an ejection unit; It is a figure showing an example of a control device.

FIG. 10 is a timing chart of signals for driving an inkjet head according to Embodiment 3 of the present invention.

FIG. 11 is a configuration diagram of an inkjet head driving device of an inkjet recording apparatus according to Embodiment 4 of the present invention.

FIG. 12 is a configuration diagram illustrating an adding unit according to a fourth embodiment of the present invention.

FIG. 13 is a diagram illustrating an operation of an adding unit according to the fourth embodiment of the present invention.

FIG. 14 is a configuration diagram of an inkjet head driving device of an inkjet recording device according to a conventional example.

FIG. 15 is a configuration diagram of an inkjet head driving device of another conventional inkjet recording apparatus.

16 is a diagram showing a timing chart for explaining a time transition of capturing pulse width data of a drive voltage waveform of the conventional inkjet recording apparatus shown in FIG.

FIG. 17 is a configuration diagram of an inkjet head driving device of an inkjet recording apparatus according to still another conventional example.

18 is a diagram showing a timing chart for explaining a time transition of capturing voltage value data of a drive voltage waveform of the conventional inkjet recording apparatus shown in FIG.

FIG. 19 is a configuration diagram of an inkjet head driving device of an inkjet recording apparatus according to still another conventional example.

[Explanation of symbols]

1-1 to 1-N ink discharge means, 2-1 to 2-N drive voltage waveform generation means, 3-1 to 3-N selector (drive voltage waveform selection means), 4 latches, 5 shift registers, 11-1 11-N ink ejection amount variation correction means, 12-N amplifier, 13-N variable resistor, 14-1
14-N ink ejection amount variation correction means, 15 shift registers, 17 latches, 25 shift registers,
27 latch, 29-1 to 29-U correction transistor, 30 transistor, 31-1 to 31-N drive voltage waveform selection means, 35 transistor, 43-1 to 43
-N drive voltage waveform generating means, 47-1 to 47-N adding means, 48-1 to 48-N selecting means.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masatoshi Kato 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation

Claims (4)

[Claims] A plurality of ink ejection means provided for each nozzle for ejecting ink from a plurality of ink chambers; and a plurality of driving means for generating a plurality of differently shaped drive voltage waveforms for driving the ink ejection means. Voltage waveform generating means, driving voltage waveform selecting means for selecting one of the plurality of different driving voltage waveforms in accordance with gradation data of a recorded image, and a driving voltage waveform selecting means provided corresponding to the plurality of ink discharging means. The output obtained by controlling the drive voltage value of the drive voltage waveform selected by the drive voltage waveform selection means based on the variation correction data of the ink ejection amount generated between a plurality of nozzles, which is created by measuring in advance, An ink jet recording apparatus comprising: a plurality of ink ejection amount variation correction means for correcting an ink ejection amount by supplying the ink to an ink ejection unit. . 2. The ink ejection amount variation correction means,
2. The ink jet recording apparatus according to claim 1, wherein the correction data of the ink ejection amount is changed for each different driving voltage waveform. 3. The ink ejection amount variation correction means,
By adjusting the ratio of the drive voltage value to the transition time from when the absolute value of the voltage of the drive voltage waveform changes from the maximum value to the standby state and the drive voltage value, variation in the ink ejection amount occurring between the plurality of nozzles is corrected. The ink jet recording apparatus according to claim 1, wherein 4. A plurality of ink ejection means provided for each nozzle for ejecting ink from a plurality of ink chambers, respectively, and a plurality of drives for generating a plurality of differently shaped drive voltage waveforms for driving said ink ejection means. Voltage waveform generating means; selecting means for selecting at least two of the plurality of drive voltage waveforms according to gradation data of a recorded image; and outputting the sum of at least two selected drive voltage waveforms to the output An ink jet recording apparatus comprising: a plurality of adding means for supplying each of the ink discharging means.