JP2006199045A - Inkjet printer and device and method for driving recording head for inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer capable of obtaining a high-quality print image by suppressing a cross-talk phenomenon generated between a plurality of nozzles. <P>SOLUTION: The inkjet printer comprises a plurality of nozzles 118 for ejecting ink droplets; a plurality of piezoelectric elements 116 which are provided in respective nozzles to generate energy for ejecting ink droplets from the corresponding nozzles; and a head controller 14 which supplies a drive signal to the piezoelectric elements 116 to put them into operation for ejecting ink and which also supplies an auxiliary drive signal to ink non-ejecting piezoelectric elements 116, to cancel out the effect that is generated on accompanying the ink ejection operation of the ink ejecting piezoelectric elements 116. The head controller 14 prepares a combination of the drive signal and auxiliary drive signal beforehand in a time series for supplying to the respective piezoelectric elements 116 and supplies the combination of both signals to the respective piezoelectric elements 116 at each of their ejection timings. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet printer that includes a plurality of nozzle portions and discharges ink droplets from each nozzle portion to perform recording on a recording sheet, and a recording head driving apparatus and method for an ink jet printer.

  In recent years, inkjet printers that perform recording on recording paper by ejecting ink droplets from nozzle openings that communicate with an ink chamber have become widespread. In particular, recently, an ink jet printer having a so-called multi-nozzle head having a plurality of nozzle portions has been introduced in order to improve the printing speed (Patent Document 1).

FIG. 13 shows a schematic configuration of a multi-nozzle head and its driving circuit in a conventional ink jet printer. As shown in this figure, the multi-nozzle head 500 includes a plurality of nozzles 501-1 to 501-n and piezoelectric elements 502-1 to 502-n provided corresponding to these nozzles. ing. Each piezoelectric element 502-1 to 502-n is fixed to each wall surface of a plurality of ink chambers (not shown) to which ink is supplied via an ink flow path (not shown). A drive signal 504 having a predetermined waveform is selectively input to these piezoelectric elements 502-1 to 502-n via on / off switches 503-1 to 503-n, respectively. Specifically, the drive signal 504 is input to the piezoelectric element connected to the on / off switch that is in the on state among the on / off switches 503-1 to 503-n. The piezoelectric element to which the drive signal 504 is input bends in the direction of reducing the volume of the corresponding ink chamber, thereby ejecting ink droplets from the nozzles.
Japanese Patent Laid-Open No. 7-76087

  In this type of ink jet printer, since the ejection operation from a plurality of nozzles is controlled simultaneously, the ink ejection operation at one nozzle has an influence on the ink ejection operation at another nozzle. There is a possibility that the ink droplet size or the like cannot be obtained. Such a crosstalk phenomenon is expected to increase particularly in nozzles adjacent to each other.

  However, in the conventional multi-nozzle head drive circuit shown in FIG. 13, only one type of drive signal 504 is input to all the piezoelectric elements. It was only controlling whether or not to discharge. For this reason, even if the above-described crosstalk phenomenon occurs between the nozzles, there is no way to suppress this phenomenon, and as a result, there is a possibility that the expected print quality cannot be obtained.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an inkjet printer capable of obtaining a high-quality printed image by suppressing a crosstalk phenomenon occurring between a plurality of nozzles, and an inkjet printer. It is an object to provide a recording head driving apparatus and method.

  An inkjet printer according to the present invention includes a plurality of nozzle portions for discharging ink droplets, and a plurality of discharge energy generating means that are provided in each nozzle portion and generate energy for discharging ink droplets from the corresponding nozzle portions. And a drive signal for causing the ink discharge operation to be supplied to the drive target discharge energy generating means, and an auxiliary drive signal for canceling the influence caused by the ink discharge operation of the drive target discharge energy generating means. And a head controller for supplying the discharge energy generating means. The head controller prepares in advance a combination of drive signals and auxiliary drive signals supplied to each discharge energy generating means in time series, and sets each drive energy and auxiliary drive signal combination to each discharge energy generating means at each discharge timing. To supply.

  A recording head driving apparatus for an ink jet printer according to the present invention generates a plurality of nozzle portions for ejecting ink droplets and energy for ejecting ink droplets from the corresponding nozzle portions. Auxiliary driving for supplying a plurality of ejection energy generating means and a drive signal for causing ink ejection operation to the ejection energy generating means to be driven and canceling the influence caused by the ink ejection operation of the ejection energy generating means to be driven And a head controller that supplies a signal to the ejection energy generating means that is not driven. The head controller prepares in advance a combination of drive signals and auxiliary drive signals supplied to each discharge energy generating means in time series, and sets each drive energy and auxiliary drive signal combination to each discharge energy generating means at each discharge timing. To supply.

  A method for driving a recording head for an ink jet printer according to the present invention generates a plurality of nozzle portions for ejecting ink droplets and energy for ejecting ink droplets from the corresponding nozzle portions. A method for driving a recording head for an inkjet printer comprising a plurality of ejection energy generating means, wherein a drive signal for causing an ink ejection operation is supplied to the ejection energy generating means to be driven, and the ejection energy generating means to be driven An auxiliary drive signal for canceling the influence caused by the ink discharge operation is supplied to the non-drive target discharge energy generating means, and the combination of the drive signal and the auxiliary drive signal supplied to each discharge energy generating means is time-sequentially. A combination of drive signal and auxiliary drive signal at each discharge timing It is obtained so as to supply to each of the ejection energy generating means.

  In the inkjet printer and the recording head drive apparatus and method according to the present invention, a drive signal for performing an ink ejection operation is supplied to the ejection energy generating unit to be driven, and the ink ejection of the ejection energy generating unit to be driven is performed. An auxiliary drive signal for canceling the influence caused by the operation is supplied to the discharge energy generating means not to be driven, and a combination of the drive signal and the auxiliary drive signal supplied to each discharge energy generating means is prepared in time series. The combination of the drive signal and the auxiliary drive signal is supplied to each discharge energy generating means at each discharge timing.

  According to the ink jet printer, the ink jet printer recording head driving apparatus, or the ink jet printer recording head driving method according to the present invention, a driving signal for performing an ink discharging operation is supplied to a driving target ejection energy generating means, and the driving target is driven. The auxiliary drive signal for canceling the influence caused by the ink discharge operation of the discharge energy generating means is supplied to the non-drive target discharge energy generating means, and the drive signal and auxiliary drive signal supplied to each discharge energy generating means are supplied. Since the combinations are prepared in time series in advance and the combination of the drive signal and the auxiliary drive signal is supplied to each discharge energy generating means at each discharge timing, the influence of crosstalk generated between a plurality of nozzles can be reduced. Can be suppressed. As a result, it is possible to reduce variations in the ink droplet ejection state among a plurality of nozzles, and it is possible to obtain a stable and high-quality print output.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 shows a schematic configuration of a main part of the ink jet printer according to the embodiment of the present invention. The recording head driving apparatus and method for an ink jet printer according to the embodiment of the present invention is embodied by the ink jet printer according to the present embodiment, and will be described below.

  The inkjet printer 1 includes a recording head 11 that performs recording by ejecting ink droplets onto the recording paper 2, an ink cartridge 12 that supplies ink to the recording head 11, the position of the recording head 11, and the recording paper 2. A head position / paper feed controller 13 for controlling the paper feed, a head controller 14 for controlling the ink droplet ejection operation of the recording head 11 by the drive signal 21, and predetermined image processing on the input image data, and print data The image processing unit 15 is supplied to the head controller 14 as 22, and the system controller 16 controls the head position / paper feed controller 13, the head controller 14, and the image processing unit 15 by control signals 23, 24, and 25, respectively. .

  3 shows a perspective sectional structure of the recording head 11 in FIG. 2, FIG. 4 shows a sectional structure of the recording head 11 in FIG. 3 viewed from the direction of arrow Z (FIG. 3), and FIG. 5 shows the recording head in FIG. 11 represents a cross-sectional structure viewed from the direction of arrow W (FIG. 3). As shown in these drawings, the recording head 11 includes a thin nozzle plate plate 111, a flow path plate 112 stacked on the nozzle plate 111, and a vibration plate 113 stacked on the flow path plate 112. Configured. Each of these plates is bonded to each other with an adhesive (not shown), for example.

  Concave portions are selectively formed on the upper surface side of the flow path plate 112, and the concave portions and the vibration plate 113 constitute a plurality of ink chambers 114 and a common flow path 115 communicating with the ink chambers. ing. A communication portion between the common flow path 115 and each ink chamber 114 forms a narrow passage, and the flow path width increases from this point toward the ink chamber 114. On the vibration plate 113 directly above each ink chamber 114, a piezoelectric element 116 made of, for example, a piezoelectric element is fixed. On each piezoelectric element 116, electrodes (not shown) are arranged in a stacked manner, and by applying a drive signal from the head controller 14 (FIG. 2) to these electrodes, each piezoelectric element 116, and hence the vibration plate 113 is moved to an arrow. By bending in the direction of P (FIG. 5), the volume of the ink chamber 114 can be increased (expanded) or decreased (contracted). Here, the piezoelectric element 116 corresponds to “ejection energy generating means” in the present invention.

  The portion of each ink chamber 114 opposite to the side communicating with the common flow path 115 has a structure in which the flow path width is gradually narrowed, and the flow path plate 112 at the end thereof is perforated in the thickness direction. A channel hole 117 is provided. The channel hole 117 communicates with a minute nozzle 118 formed in the lowermost nozzle plate 111 so that ink droplets are ejected from the nozzle 118. In the present embodiment, the recording head 11 has a plurality of nozzles 118 formed in a line at equal intervals along the paper feeding direction (arrow X in FIG. 3) of the recording paper 2 (FIG. 2). Other arrangements (for example, two rows in a staggered manner) may be used. Here, the nozzle 118 corresponds to a “nozzle portion” in the present invention.

  The common channel 115 communicates with the ink cartridge 12 (not shown in FIGS. 3 and 4) shown in FIG. Then, the ink is always supplied from the ink cartridge 12 to each ink chamber 114 through the common flow path 115 at a constant speed. The ink supply can be performed by using, for example, a capillary phenomenon, but in addition, the ink cartridge 12 may be provided with a predetermined pressurizing mechanism and pressurized.

  The recording head 11 ejects ink droplets while reciprocating in a direction Y perpendicular to the paper feeding direction X of the recording paper 2 by a carriage drive motor (not shown) and a carriage mechanism associated therewith, whereby an image is recorded on the recording paper 2. It comes to record.

  FIG. 1 shows a circuit configuration of the head controller 14 in FIG. As shown in this figure, the head controller 14 includes a plurality of waveform selection units 141-1 to 141-n, a drive waveform generation unit 142 that generates four drive signals 145a to 145d having different waveforms, And a drive waveform selection control unit 143 that controls operations of the waveform selection units 141-1 to 141-n. Here, n is a positive integer.

  The drive signals 145a to 145d output from the drive waveform generation unit 142 are branched into n pieces each and input to the waveform selection units 141-1 to 141-n, respectively. The drive waveform selection control unit 143 inputs the selection signals 146-1 to 146-n to the waveform selection units 141-1 to 141-n so as to correspond to the waveform selection units 141-1 to 141-n, respectively. 1 to 141-n performs control so that any one of the drive signals 145a to 145d is selected. The waveform selectors 141-1 to 141-n supply the drive signals 21-1 to 21-n selected from the drive signals 145a to 145d to the recording head 11, respectively. The drive signals 21-1 to 21-n correspond to the drive signal 21 in FIG. Here, each of the waveform selectors 141-1 to 141-n corresponds to “selecting means” in the present invention.

  For example, the drive waveform generation unit 142 is not shown in the figure, but includes a microprocessor, a ROM (ReadOnly Memory) in which a program executed by the microprocessor is stored, a predetermined calculation by the microprocessor, temporary data storage, and the like. RAM (Random Access Memory) used as a work memory, a drive waveform storage unit composed of a non-volatile memory, and digital analog (D / A) for converting digital data read from the drive waveform storage unit into analog ) A converter and an amplifier that amplifies the output of the D / A converter. Here, the drive waveform storage unit stores waveform data indicating the voltage waveforms of the drive signals 145a to 145d supplied to the recording head 11, and this waveform data is read by the microprocessor and is output by the D / A converter. After being converted into an analog signal, it is amplified by an amplifier and output as drive signals 145a to 145d. However, the drive waveform generation unit 142 is not limited to the above configuration, and may be configured differently.

  FIG. 6 illustrates an example of the waveforms of the drive signals 145a to 145d output from the drive waveform generation unit 142. In this figure, (a) to (d) represent drive signals 145a to 145d, respectively. Among these, the drive signal 145a is a signal waveform used for actually performing the ink ejection operation, and the drive signals 145b and 145c are signal waveforms for suppressing the influence of crosstalk between the nozzles. The drive signal 145d has a constant voltage (V1) waveform that does not cause ink droplets to be ejected. Here, the drive signals 145b and 145c correspond to the “auxiliary drive signal” in the present invention.

  Next, the significance of the waveform of the drive signal 145a will be described in detail with reference to FIG.

  FIG. 7 shows the relationship between the waveform of the drive signal 145a, the behavior of the piezoelectric element 116, and the change in the position of the front end of the ink in the nozzle 118 (hereinafter referred to as the meniscus position). (A) of this figure represents the waveform for one period of the drive signal 145a. (B) represents the state of the ink chamber 114, and (c) represents the change in the meniscus position in the nozzle 118. In (a), for the sake of convenience of explanation, repetition of drive signals having the same waveform is depicted. In this figure, the symbol ts represents the signal switching timing for each cycle, and the symbol te represents the ink droplet ejection start timing.

  In FIG. 6A, first, a process (from A to B) in which the drive voltage is changed from the first voltage V1 (= constant) to the voltage 0 is a first process, and a time required for this process is t1. Also, the process (from B to C) in which the voltage 0 is maintained and waits is defined as the second process, and the time required for this process is defined as t2. Furthermore, the process (from C to D) for changing from the voltage 0 to the second voltage V2 is the third process, and the time required for this process is t3. In the following description, the first voltage V1 is referred to as a pull-in voltage, and the second voltage V2 is referred to as a discharge voltage.

  The recording head 11 is driven at a constant frequency (for example, about 1 to 10 kHz), and the ink droplet ejection cycle T is determined in accordance with the driving frequency. Time C and time G, which are the start time of the third stroke, are timings at which discharge is started, and the first and second strokes are performed prior to the start of discharge.

  First, at time A and before, as shown in the state PA of FIG. 6B, the vibration plate 113 is stopped in a state of being slightly bent inward by the application of the voltage V1 to the piezoelectric element 122, and the ink chamber 114 Is in a contracted state. At time A, the position of the meniscus in the nozzle 118 is assumed to be substantially the same as the opening end of the nozzle 118 as shown in the state MA in FIG.

  Next, when the first step of reducing the drive voltage from the voltage V1 at the time point A to the voltage 0V at the time point B is performed, the voltage applied to the piezoelectric element 116 becomes zero, so the deflection of the vibration plate 113 is eliminated, and the ink chamber 114 expands (state PB in FIG. 6B). For this reason, the meniscus in the nozzle 118 is drawn in the direction of the ink chamber 114, and at the time point B, for example, the meniscus moves back to the state of MB in FIG. 6C (that is, moves away from the opening end).

  Here, since the amount of meniscus pull-in in the first stroke can be changed by changing the magnitude of the potential difference (pull-in voltage V1) between time A and time B, the end of the next second stroke is indirectly performed. It is possible to adjust the meniscus position at the time, that is, at the start of the third stroke. The meniscus position, that is, the distance from the opening end to the meniscus greatly affects the size of the ink droplets ejected in the third stroke, and the size of the ink droplets can be controlled by adjusting this. That is, the ink droplet size can be controlled by changing the amount of meniscus pull-in (more specifically, pull-in voltage V1) in the first stroke.

  Next, during a time t2 from time point B to time point C, a second process is performed to keep the volume of the ink chamber 114 constant by fixing the drive voltage to 0 and keeping the vibration plate 113c free from deflection. . However, since the ink supply from the ink cartridge 12 is continuously performed during this time, the meniscus position in the nozzle 118 is displaced toward the opening end, and at the point C, for example, the state of MC in FIG. Move forward to.

  Here, the amount of advancement of the meniscus position is changed by changing the time t2 required for the second stroke, and the meniscus position at the start of the third stroke can be adjusted. As a result, the ink droplet size is controlled. It is possible. Specifically, the ink droplet size can be reduced as the required time t2 of the second stroke is shortened.

  Next, a third step is performed in which the drive voltage is rapidly increased from the voltage 0 V at time C to the ejection voltage V2 at time D. Here, time point C is the timing at which ejection is started, as described above. In this case, since the large discharge voltage V2 is applied to the piezoelectric element 122 at the time point D, the vibration plate 113 is greatly bent inward as shown in the state PD of FIG. 6B, and the ink chamber 114 is rapidly contracted. . For this reason, as shown in the state MD of FIG. 6C, the meniscus in the nozzle 118 is pushed at a stroke toward the opening end and is ejected as ink droplets from here. The ejected ink droplets fly in the air and land on the recording paper 2 (FIG. 2). Here, it is possible to control the size of the ink droplet by changing the magnitude of the ejection voltage V2.

  Thereafter, the drive voltage is decreased again to V1, and the vibration plate 113 is bent slightly inward to be in an initial state (state PE in FIG. 6B), and this state is the start point of the first stroke of the next discharge operation. Maintain up to F. At time E immediately after the drive voltage is decreased again to V1, as shown in the state ME in FIG. 6C, the meniscus position is retracted by an amount substantially corresponding to the ejected ink droplet amount. However, due to ink filling (refilling) performed thereafter, the meniscus position at the first stroke start time point F of the next ejection operation is the same as the opening end as shown in the state MF in FIG. 6C. Until it becomes the same as the state MA at time A.

  In this way, one discharge operation is completed. Thereafter, by repeating such a cycle operation in parallel for each nozzle 118, image recording on the recording paper 2 (FIG. 2) is continuously performed.

  The drive waveform 145a is created so as to satisfy the following conditions. That is, the required time t1 of the second stroke is equal to or less than the required time from when the meniscus is drawn until the meniscus reaches the nozzle tip, and the discharge voltage V2 is large enough to discharge ink droplets. The three conditions are that the slope of the voltage change in the third stroke is constant.

  Now, returning to FIG. 6 again, the characteristics of the drive signals 145b and 145c will be described. As described above, the drive signals 145b and 145c are signal waveforms for suppressing the influence of crosstalk between the nozzles. Among them, the drive signal 145b has a waveform shape substantially in phase with the drive signal 145a, holds the voltage V3 slightly smaller than the pull-in voltage V1 during the second process period of the drive signal 145a, and drives the drive signal 145b. During the period in which the signal 145a is held at the discharge voltage V2, the voltage V4 slightly higher than the pull-in voltage V1 is held. The pull-in voltage V1 is held during other periods. On the other hand, the drive signal 145c has a waveform shape substantially opposite in phase to the drive signal 145a, holds the voltage V5 slightly higher than the pull-in voltage V1 during the second process period of the drive signal 145a, and drives the drive signal 145c. During a period in which 145a is held at the discharge voltage V2, a voltage V6 slightly smaller than the pull-in voltage V1 is held. The pull-in voltage V1 is held during other periods.

  Next, the overall operation of the ink jet printer 1 of FIG. 1 will be described with reference to FIG. Here, FIG. 7 shows a main part of one ejection operation in the head controller 14 (FIG. 1).

  In FIG. 1, when print data is input to the inkjet printer 1 from an information processing apparatus such as a personal computer (not shown), the image processing unit 15 performs predetermined image processing (for example, decompression of compressed data) on the input data. And the like are sent to the head controller 14 as the print data 22.

  When the print data 22 for n dots corresponding to the number of nozzles of the recording head 11 is input to the drive waveform selection control unit 143 of the head controller 14 (Step S101 in FIG. 8, each nozzle is based on these print data 22). For each 118, the presence / absence of dot formation and the necessity of crosstalk suppression measures are determined, and the drive signal waveform to be selected in each waveform selection unit 141-1 to 141-n is determined from the determination result. Specifically, the waveform selection unit 141-j determines the drive signal waveform to be selected while sequentially incrementing the variable j from “1” to “n” (steps S102 to S105).

  When the determination of the drive signal to be selected for all of the n waveform selectors 141-1 to 141-n is completed (step S105; Y), the drive waveform selection controller 143 has a predetermined switching timing ts (FIG. 7). ) Has arrived (step S106; Y), the waveform selection signals 146-1 to 146-146 for selecting the drive signals having the determined waveforms for the waveform selection units 141-1 to 141-n, respectively. n is output (step S107).

  The waveform selection units 141-1 to 141-n select corresponding ones from the drive signals 145a to 145d based on the input waveform selection signals 146-1 to 146-n, and output these. Accordingly, for example, drive signals 145a to 145d having waveforms as shown in FIGS. 6A to 6D are supplied to the piezoelectric elements 116 of the respective nozzles of the recording head 11. Each nozzle of the recording head 11 performs ink droplet ejection by three strokes as described with reference to FIG. 7 and a crosstalk suppression operation as described later, based on the voltage waveform of each drive signal.

  Next, with reference to FIG. 9 to FIG. 12, the characteristic operation of the ink jet printer according to the present embodiment will be specifically described.

  FIG. 9 shows an example of the state of the recording head 11 being driven when no special measures against crosstalk are taken, and shows a state seen from the same direction as FIG. Here, for example, a state when the ink droplets are ejected by applying the drive signal 145a of FIG. 6 to the piezoelectric element 116-3 provided corresponding to the ink chamber 114-3 in the center of the drawing is shown. Yes. At this time, a constant voltage waveform (drive signal 145d in FIG. 6) is applied to the other piezoelectric elements 116-1, 116-2, 116-4, and 116-5, and ink droplets are not ejected. And

  In this figure, when the drive signal 145a is applied to the piezoelectric element 116-3 of the ink chamber 114-3 and the vibration plate 113 of the ink chamber 114-3 bends inward, the vibration is generated in the other ink chamber 114-1. , 114-2, 114-4, and 114-5 are transmitted to the vibration plate 113. Therefore, under certain conditions, the vibration plates 113 under the other piezoelectric elements 116-1, 116-2, 116-4, and 116-5 are alternately displaced in opposite phases as shown in the figure, The volume of each ink chamber also changes. In particular, since the vibration plates 113 of the adjacent ink chambers 114-2 and 114-4 are largely bent outward, the volume increase amount of these ink chambers 114-2 and 114-4 is large. However, when such a displacement of the vibration plate 113 occurs, the ink in the ink chamber 114-3 corresponding to the ejected piezoelectric element 116-3 flows into the adjacent ink chamber 114 via the common channel 115. As a result, the pressure in the ink chamber 114-3 does not reach the desired state. For this reason, there arises a problem that ink droplets of a predetermined size cannot be obtained.

  In the ink jet printer according to the present embodiment, in order to reduce the influence of such crosstalk, for example, a combination as shown in FIG. 10 is applied to piezoelectric elements other than the piezoelectric element 116-3 that has ejected ink droplets. Thus, an auxiliary drive signal is applied. FIG. 10 shows time-series changes in the combination of drive signals applied to the piezoelectric elements 116-1 to 116-5 shown in FIG. 9. Further, “a”, “b”, and “c” in this figure indicate that the drive signals 145a, 145b, and 145c are applied, respectively.

  In this specific example, for example, when the drive signal 145a is applied to the piezoelectric element 116-3 at a certain discharge timing and ink-like discharge is performed, the drive signal is applied to the piezoelectric elements 116-2 and 116-4 on both sides. A drive signal 145b having the same phase as that of 145a is applied, and a drive signal having a phase opposite to that of the drive signal 145a is applied to the piezoelectric elements 116-1 and 116-5 that are separated from the piezoelectric element 116-3 by one. 145c is applied. In this case, a voltage V4 slightly higher than the reference voltage V1 is applied to each of the piezoelectric elements 116-2 and 116-4 that are to be displaced outward, and the displacement of the vibration plate 113 is suppressed. On the other hand, a voltage V6 slightly smaller than the reference voltage V1 is applied to the piezoelectric elements 116-1 and 116-5 that are to be displaced inward, and the displacement of the vibration plate 113 is suppressed.

  The same applies to the subsequent ejection timings, and the drive signal 145b having the same phase is applied to the piezoelectric element adjacent to the piezoelectric element that performs the ejection operation, and is separated from the piezoelectric element that performs the ejection operation one by one. A driving signal 145c having an opposite phase is applied to the piezoelectric element.

  As described above, in this specific example, the auxiliary drive signal that can suppress the volume displacement of each ink chamber is applied to the piezoelectric elements other than the piezoelectric element that has performed the ejection operation. It is possible to eliminate variations in print quality such that the volume of the ink chamber corresponding to the other nozzles is not displaced by the ejection operation of the nozzle 118, and ink droplets of a predetermined size can be obtained.

  Next, another specific example will be described.

  FIG. 11 shows another state of the recording head 11 that is being driven when no special measures against crosstalk are taken, and shows a state seen from the same direction as FIG. Here, for example, a state when the ink droplets are ejected by applying the drive signal 145a of FIG. 6 to the piezoelectric element 116-3 provided corresponding to the ink chamber 114-3 in the center of the drawing is shown. Yes. At this time, a constant voltage waveform (drive signal 145d in FIG. 6) is applied to the other piezoelectric elements 116-1, 116-2, 116-4, and 116-5, and ink droplets are not ejected. And

  In the example shown here, when the drive signal 145a is applied to the piezoelectric element 116-3 and the vibration plate 113 of the ink chamber 114-3 bends inward, the vibration is generated in the other ink chambers 114-1, 114. -2, 114-4, and 114-5 are also transmitted to the vibration plates 113, and the vibration plates 113 under the other piezoelectric elements 116-1, 116-2, 116-4, and 116-5 are all the same as shown in the figure. It is displaced inward in the form of a phase. Therefore, for the same reason as in the above example, there arises a problem that ink droplets of a predetermined size cannot be obtained.

  In this specific example, in order to reduce the influence of such crosstalk, an auxiliary drive signal is applied to piezoelectric elements other than the piezoelectric element 116-3 that has ejected ink droplets, for example, by a combination as shown in FIG. Is applied. FIG. 12 shows a time-series change in the combination of drive signals applied to the piezoelectric elements 116-1 to 116-5 shown in FIG. 11, and “a” and “c” The drive signals 145a and 145c are applied, respectively.

  In this specific example, for example, when the drive signal 145a is applied to the piezoelectric element 116-3 at a certain ejection timing and ink ejection is performed, all other piezoelectric elements 116-1, 116-2, 116-4 are performed. , 116-5, a drive signal 145c having a phase opposite to that of the drive signal 145a is applied. In this case, a voltage V6 that is slightly smaller than the reference voltage V1 is applied to each of the piezoelectric elements 116-1, 116-2, 116-4, and 116-5 to be displaced inward. Displacement is suppressed.

  The same applies to the discharge timings subsequent to this, and the drive signal 145c having the opposite phase is applied to all the piezoelectric elements other than the piezoelectric elements that perform the discharge operation.

  As described above, in this specific example, the auxiliary drive signal that can suppress the volume displacement of each ink chamber is applied to all the piezoelectric elements other than the piezoelectric element that has performed the ejection operation. In addition, it is possible to eliminate variations in print quality, such as the ink chamber volume corresponding to other nozzles is not displaced by the ejection operation of one nozzle 118, and ink droplets of a predetermined size can be obtained. Become.

  9 and 11, it is considered that the displacement amount of the vibration plate 113 in other ink chambers in which ink droplets are not ejected decreases as the distance from the ink chamber in which ink droplets are ejected decreases. Therefore, a plurality of types of auxiliary drive signals having different peak values (voltage values V3 to V6) are prepared as auxiliary drive signals for crosstalk suppression, and these are applied to the corresponding piezoelectric elements. May be. By doing so, finer crosstalk suppression control can be performed.

  In the example described with reference to FIGS. 9 to 12, the ink droplet ejection operation is performed only with one certain piezoelectric element and the ink droplet operation is not performed with the other piezoelectric elements. In the case where a plurality of piezoelectric elements or a plurality of piezoelectric elements separated by several simultaneously perform ink droplet ejection, the following may be performed.

  For example, assuming that ink droplets are ejected simultaneously by the piezoelectric elements 116-3 and 116-4 in FIG. 9, the piezoelectric elements 116-3 and 116-4 are as follows. That is, when the ink droplet ejection is performed only by the piezoelectric element 116-3, the waveform of the auxiliary drive signal (here, the drive signal 145b or 145c) to be applied to the adjacent piezoelectric element 116-4 and the original ink droplet A drive signal having a waveform obtained by superimposing the discharge waveform (here, the drive signal 145a) is prepared in advance and applied to the piezoelectric elements 116-3 and 116-4.

  On the other hand, the piezoelectric elements 116-1, 116-2, and 116-5 that do not discharge ink droplets are as follows. That is, when ink droplet ejection is performed only by the piezoelectric element 116-3, the waveform of the auxiliary drive signal to be applied to each of the piezoelectric elements 116-1, 116-2, 116-5 (here, the drive signal 145b or 145c) and the waveform of the auxiliary drive signal to be applied to each of the piezoelectric elements 116-1, 116-2, 116-5 when the ink droplet ejection is performed only by the piezoelectric element 116-4 (here, the drive signal) 145b or 145c) are prepared in advance so as to have waveform driving signals obtained by superimposing them in correspondence with each other, and these are appropriately selected and applied to the piezoelectric elements 116-1, 116-2, 116-5, respectively. .

  The same applies to the case where two piezoelectric elements are simultaneously driven by other combinations, and the case where three or more piezoelectric elements are simultaneously driven by any combination. That is, drive signals of all waveform patterns obtained by superimposing auxiliary drive signals of waveforms to be applied to other piezoelectric elements when driven individually are prepared in advance, and according to the drive patterns of the piezoelectric elements. Therefore, a corresponding drive signal may be applied. By doing so, even when ink droplets are ejected simultaneously by a plurality of nozzles, it is possible to reduce the influence of crosstalk between the nozzles.

  While the present invention has been described with reference to the embodiment, the present invention is not limited to this embodiment and can be variously changed. For example, in the above embodiment, as shown in FIG. 6, only one type of drive signal is used for the ejection operation and the ink droplet size is one type, but the present invention is limited to this. For example, a plurality of drive signals having various waveforms in which the pull-in voltage V1, the second process time t2, or the discharge voltage V2 are appropriately set are prepared, and are selectively switched for each dot and supplied to the piezoelectric elements of the nozzles. By doing so, it becomes possible to eject ink droplets of many sizes.

  In the above embodiment (FIG. 6), only one type of drive signal is prepared for each of the auxiliary drive signals for in-phase crosstalk suppression and anti-phase crosstalk suppression, but the present invention is limited to this. As described above, for example, auxiliary drive signals having various waveforms in which the voltage values V3 to V6 are appropriately set are prepared and selectively supplied to the piezoelectric elements of the respective nozzles as necessary. By doing so, more detailed crosstalk countermeasures can be taken.

1 is a block diagram illustrating a schematic configuration of a drive device for a recording head for an ink jet printer according to an embodiment of the present invention. 1 is a block diagram illustrating a schematic configuration of an inkjet printer according to an embodiment of the present invention. FIG. 3 is a perspective cross-sectional view illustrating a structural example of a recording head. FIG. 3 is a cross-sectional view illustrating a structural example of a recording head. FIG. 6 is another cross-sectional view illustrating a structural example of a recording head. It is a figure showing an example of the waveform of the drive signal output from the drive waveform production | generation part in FIG. FIG. 6 is a diagram for explaining a relationship between a drive signal waveform for ejection, a state of an ink chamber, and a change in a meniscus position in a nozzle. 4 is a flowchart for explaining the main operation of the head controller. FIG. 6 is a cross-sectional view illustrating a state of a recording head during driving when no special countermeasure against crosstalk is taken. It is a figure showing the combination of the drive signal applied to each piezoelectric element in the displacement mode shown in FIG. FIG. 9 is a cross-sectional view illustrating another state of the recording head during driving when no special measures against crosstalk are taken. It is a figure showing the combination of the drive signal applied to each piezoelectric element in the displacement mode shown in FIG. It is a block diagram showing schematic structure of the multi-nozzle head in the conventional inkjet printer, and its drive circuit.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Inkjet printer, 2 ... Recording paper, 11 ... Recording head, 12 ... Ink cartridge, 14 ... Head controller, 21 ... Drive signal, 22 ... Print data, 113 ... Vibration plate, 114 ... Ink chamber, 115 ... Joint flow path 116: Piezoelectric element 118: Nozzle 141-1 to 141-n Waveform selection unit 142 Drive waveform generation unit 143 Drive waveform selection control unit 145a to 145d Drive signal 146-1 to 146 n ... Waveform selection signal, V1 ... Pull-in voltage, V2 ... Discharge voltage, t1 ... Time required for the first stroke, t2 ... Time required for the second stroke, t3 ... Time required for the third stroke, ts ... Switching timing, te ... Discharge start timing.

Claims (3)

A plurality of nozzles for ejecting ink droplets;
A plurality of ejection energy generating means provided in each of the nozzle portions and generating energy for discharging ink droplets from the corresponding nozzle portion;
A drive signal for causing the ink discharge operation is supplied to the drive target discharge energy generation means, and an auxiliary drive signal for canceling the influence caused by the ink discharge operation of the drive target discharge energy generation means is discharged to the drive non-target. A head controller that supplies energy generation means,
The head controller prepares a combination of the drive signal and the auxiliary drive signal supplied to each of the ejection energy generating means in time series in advance, and combines the drive signal and the auxiliary drive signal at each ejection timing. Is supplied to each of the discharge energy generating means. A plurality of nozzles for ejecting ink droplets;
A plurality of ejection energy generating means provided in each of the nozzle portions and generating energy for discharging ink droplets from the corresponding nozzle portion;
A drive signal for causing the ink discharge operation is supplied to the drive target discharge energy generation means, and an auxiliary drive signal for canceling the influence caused by the ink discharge operation of the drive target discharge energy generation means is discharged to the drive non-target. A head controller that supplies energy generation means,
The head controller prepares a combination of the drive signal and the auxiliary drive signal supplied to each of the ejection energy generating means in time series in advance, and combines the drive signal and the auxiliary drive signal at each ejection timing. Is supplied to each of the discharge energy generating means. A recording head drive device for an ink jet printer, wherein: For an inkjet printer comprising a plurality of nozzle portions for discharging ink droplets, and a plurality of discharge energy generating means provided in each nozzle portion for generating energy for discharging ink droplets from the corresponding nozzle portions A method of driving a recording head,
A drive signal for causing the ink discharge operation is supplied to the drive target discharge energy generation means, and an auxiliary drive signal for canceling the influence caused by the ink discharge operation of the drive target discharge energy generation means is discharged to the drive non-target. To supply energy generation means,
A combination of the drive signal and the auxiliary drive signal supplied to each discharge energy generating means is prepared in time series in advance, and the combination of the drive signal and the auxiliary drive signal is set to each discharge energy at each discharge timing. A method for driving a recording head for an ink jet printer, comprising: supplying to a generating unit.

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