JP2006035568A - Liquid discharge head driver, liquid discharge device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid discharge head driver, a liquid discharge device using the same and an image forming device that prevents an improper discharge from getting caused by microvibration of a meniscus, shortens a discharge period, and reduces momentary current consumption and momentary power consumption. <P>SOLUTION: The liquid discharge head driver is equipped with a first driving waveform generation means (130) to generate a common driving waveform for discharge containing a plurality of discharge waveform elements to discharge a plurality of kinds of liquid drops different in volume, and a second driving waveform generation means (132) to generate a common driving waveform for microvibration containing microvibration waveform elements to microscopically vibrate a meniscus independently and has driving selection means (116, 120 and 134) to apply discharge waveform elements to pressure generation element of nozzles discharging a liquid and to selectively apply microvibration waveform elements to the pressure generation elements of the nozzles not discharging a liquid. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid ejection head drive device, a liquid ejection device, and an image forming apparatus, and more particularly, to a configuration of a drive device suitable for driving a liquid ejection head having pressure generating elements corresponding to a large number of ejection ports (nozzles) The present invention relates to drive control technology.

  In an inkjet recording apparatus using a piezoelectric element, a single common drive waveform is used in which a plurality of drive waveform elements that eject a plurality of types of ink droplets (for example, large dots, medium dots, and small dots) having different ink volumes are combined, A common drive circuit system that selectively applies a necessary waveform portion to each piezoelectric element with a switch is generally known (Patent Documents 1 and 2). In this method, since a common drive waveform is simultaneously applied to a plurality of piezoelectric elements, it is not necessary to prepare a drive waveform generation circuit individually for each piezoelectric element, and the number of high-voltage high-precision analog circuits and the number of wirings can be reduced. There is an advantage that it can be reduced.

  Further, as one of the general problems in the ink jet system, there is a countermeasure against ejection failure typified by nozzle clogging (non-ejection), ejection amount abnormality, flight direction abnormality, and the like. With respect to measures against such ejection defects, in Patent Document 3, the inkjet head is moved to a maintenance station having the same type of ink as that used for recording, and immersed in the ink in the maintenance station, whereby the inkjet head is cleaned and the ink is removed. A method for preventing drying is disclosed. Japanese Patent Application Laid-Open No. 2004-228561 describes that recovery from clogging is possible by retracting the recording head out of the printing area and performing idle ejection (preliminary ejection).

  The techniques disclosed in Patent Documents 3 and 4 are systems (a so-called carriage system or a shuttle system) in which recording is performed by reciprocating a recording head having a plurality of nozzles in a direction perpendicular to the paper passing direction by a carriage. The recording head can be retracted outside the printing area to prevent ink from drying or to remove clogging. In the shuttle system, the recording head moves in a direction perpendicular to the paper passing direction to perform image recording. Therefore, even when a nozzle is clogged, ink is ejected from another nozzle and printing is performed. be able to.

  On the other hand, a line type recording head in which a large number of nozzles are arranged on an array over the entire width of the printing area is fixed at a predetermined position. Therefore, the recording head is retracted outside the printing area as in the carriage type. It is difficult to take measures to prevent clogging. Also, in the case of a line type recording head (fixed installation type head), it is difficult to print with other nozzles at the position corresponding to the clogged nozzle, and the image portion corresponding to the position of the clogged nozzle However, there is a problem that a white-out image in which printing dots are missing.

  In order to solve such a problem, as another prior art for ejection failure, a nozzle is applied by applying a minute drive signal that does not eject ink droplets to a piezoelectric element attached to a pressure chamber communicating with the nozzle opening. Techniques have been proposed for preventing clogging by minutely vibrating a meniscus in the vicinity of an opening (Patent Documents 5, 6, etc.).

Further, in Patent Documents 1 and 2 already introduced, one ejection drive cycle includes a plurality of drive pulses for ejecting a plurality of types of ink droplets having different ink volumes and a micro-vibration pulse for causing micro-vibration in a meniscus near the nozzle opening. Is disclosed in Japanese Patent Application Laid-Open Publication No. 2003-124867, for example, a technique that efficiently fits in the drive signal and applies a minute drive signal (microvibration pulse) even during a printing operation to slightly vibrate the meniscus and prevent nozzle clogging. .
JP 2002-154207 A JP 2000-37867 A JP-A-7-195701 JP-A-7-266580 JP 2003-1857 A JP 2003-175605 A

  A line-type recording head having a large number of nozzles can simultaneously eject ink from a plurality of nozzles and perform printing recording at high speed. However, if the above-described common drive circuit method is applied to such a recording head as it is, Since a large number of piezoelectric elements are driven simultaneously with a single drive waveform, a large amount of power is instantaneously consumed, a voltage drop occurs in the power source, and an extremely large power source is required for reliable driving. Even if the power supply is sufficiently large, a voltage drop cannot be avoided due to the wiring resistance in and around the recording head. As a result, there is a possibility that the drive energy becomes insufficient, the ink ejection becomes unstable, and the recorded image becomes defective.

  In order to avoid such a problem, it is conceivable to divide a large number of nozzles into a plurality of blocks and perform time-division driving in which each block is driven at different timings. However, if the number of nozzles becomes very large, the drive capability (for example, the collector current Icmax of the transistors constituting the circuit) that can be driven by one common drive circuit will be exceeded, and the need to have multiple common drive circuits will arise. In addition, the circuit scale becomes large.

  Further, as in Patent Documents 1 and 2, a fine vibration waveform element not directly related to print recording is prepared within one discharge drive cycle, and a necessary waveform using a common drive waveform including the fine vibration waveform element. A configuration in which the portion is selectively applied generally decreases the printing speed. In particular, in the case of a line-type recording head in which a large number of nozzles are arranged in an array, the throughput, which is a feature of the recording head, is reduced, leading to a decrease in performance as a printer.

  Furthermore, if the micro-vibration driving is always performed for several thousand piezoelectric elements by the common driving waveform method, instantaneous power consumption may increase in combination with the ejection driving, and the power supply may be insufficient. In addition, the common drive circuit may exceed the drive capability, possibly destroying the circuit, and may further deteriorate the piezoelectric element itself.

  The present invention has been made in view of such circumstances, and at the same time as discharge driving, performs fine vibration driving to slightly vibrate the meniscus in order to avoid non-discharge, thereby preventing the occurrence of defective discharge and improving the discharge performance (printer). In this case, it is possible to shorten the ejection cycle (higher printing speed) while maintaining the printing quality), and to reduce the size of the drive circuit and to reduce the instantaneous current consumption and instantaneous power consumption. It is an object of the present invention to provide an ejection head drive device, a liquid ejection device using the same, and an image forming apparatus.

  In order to achieve the above object, an invention according to claim 1 is directed to a liquid discharge head that discharges liquid from the nozzles by supplying a driving signal to a plurality of pressure generating elements provided corresponding to the plurality of nozzles. A first driving waveform generating means for generating a common driving waveform for ejection including a plurality of ejection waveform elements for ejecting a plurality of types of liquid droplets having different volumes; and ejecting liquid from the nozzle A second drive waveform generating means for generating a micro-vibration common drive waveform including a micro-vibration waveform element for causing the meniscus to vibrate to such an extent that the meniscus is not generated, and a pressure generating element of a nozzle that performs ejection among the plurality of nozzles On the other hand, at least one discharge waveform element of the discharge common drive waveform is selectively applied, a nozzle that performs fine vibration is selected from nozzles that do not perform discharge, and the selected fine vibration is selected. Characterized in that and a driving selection means for applying at least one micro-vibration waveform element of the micro-vibration for the common driving waveform with respect to the pressure generating element of the target nozzle.

  According to the present invention, the first drive waveform generating means for generating a common drive waveform for discharge including a plurality of discharge waveform elements corresponding to the discharge of a plurality of types of droplet volumes, and a fine vibration for generating a meniscus. A second drive waveform generating means for generating a common waveform element for micro vibration including a micro vibration waveform element is provided independently, and a discharge waveform element is applied to a pressure generating element of a nozzle that discharges liquid while this discharge Since the fine vibration waveform element can be selectively applied to the pressure generating element of the nozzle that does not discharge liquid simultaneously with the application of the waveform element, the fine vibration waveform element and the discharge waveform element are combined into one common drive waveform. The discharge cycle is shortened compared with the conventional method housed therein.

  Discharge quality can be maintained because some of the nozzles can be ejected and at the same time fine vibration can be selectively applied to the nozzles that are not ejecting according to the situation. The occurrence of ejection failure can be prevented.

  In addition, by controlling the timing at which fine vibration is applied to the nozzles that are not ejected during the ejection period of other nozzles, instantaneous current consumption and power consumption can be suppressed. As a result, the circuit load can be reduced, the overall current consumption (average current consumption) can be reduced, and the durability (lifetime) of the pressure generating element can be improved compared to the method of always performing microvibration. it can.

  The first drive waveform generating means and the second drive waveform generating means are divided into separate circuits, so that the load of the circuit is distributed, and driving in the case of simultaneously driving a large number of pressure generating elements. Waveform distortion is suppressed and stable ejection can be performed.

  Further, by separating the first drive waveform generating means and the second drive waveform generating means, the power consumption and heat generation of the circuit can be dispersed, and the circuit scale and the radiator can be reduced.

  According to a second aspect of the present invention, there is provided a driving apparatus for a liquid discharge head that applies a driving signal to a plurality of pressure generating elements provided corresponding to a plurality of nozzles and discharges liquid from the nozzles. First drive waveform generating means for generating a common drive waveform for discharge including a plurality of discharge waveform elements for discharging a plurality of different types of droplets, and finely vibrating the meniscus to such an extent that liquid is not discharged from the nozzle A second drive waveform generating means for generating a common drive waveform for fine vibration including a fine vibration waveform element for the pressure, and a common for discharge with respect to a pressure generating element corresponding to a nozzle that performs discharge among the plurality of nozzles At least one discharge waveform element of the drive waveform is selectively applied, and at least one of the common drive waveforms for fine vibration is applied to a pressure generating element corresponding to a nozzle that does not perform discharge. In the case of simultaneously applying the respective drive waveforms to the drive selection means for applying the vibration waveform element, the pressure generating element corresponding to the nozzle that performs the ejection, and the pressure generating element corresponding to the nozzle that does not perform the ejection, At least one of the rising portion and the falling portion of the fine vibration waveform element applied to the pressure generating element corresponding to the nozzle that does not perform discharge is applied to the pressure generating element corresponding to the nozzle that performs discharge. Drive control means for controlling so as not to overlap with the rising part or falling part.

  The drive current flowing through the pressure generating element serving as a capacitive load is charged and discharged at the drive waveform changing portion (rising portion and falling portion). Therefore, a relatively large drive current flows during a period corresponding to the rising part and the falling part (period with a waveform inclination), and almost no current flows during other periods (a flat part without the waveform inclination). According to the present invention, when the drive waveform for ejection and the drive waveform for fine vibration are simultaneously applied to the pressure generating elements of different nozzles, the rising and falling parts of the fine vibration waveform element and the rising of the discharge waveform element By preventing the overlapping portion and the falling portion from overlapping as much as possible, the timing at which the ejection driving current and the micro-vibration driving current flow is dispersed, and instantaneous current consumption can be suppressed.

  A third aspect of the present invention relates to one aspect of the liquid ejection head drive device according to the first or second aspect, wherein the drive selection means includes liquid viscosity, non-discharge period, temperature, humidity, and liquid discharged immediately before. Based on at least one of the droplet volume and the volume of the liquid ejected from the surrounding nozzles, the number of fine vibration waveform elements applied to the finely vibrating nozzle, the frequency of the fine vibration waveform element, and the fine vibration waveform element It is characterized by comprising fine vibration control means for controlling at least one of the application timings.

  According to the present invention, the necessity of microvibration is determined from at least one of the following conditions: liquid viscosity, non-ejection period, temperature, humidity, droplet volume ejected immediately before, volume of liquid ejected from surrounding nozzles, and the like. Judgment can be made and appropriate fine vibration driving can be performed according to the situation. Thereby, while being able to maintain discharge performance, unnecessary fine vibration drive can be omitted, average power consumption can be suppressed, and deterioration of the pressure generating element can be suppressed.

  The invention according to claim 4 relates to an aspect of the liquid ejection head drive device according to claim 1, 2, or 3, wherein the cycle of the micro-vibration common drive waveform is 1 of the cycle of the ejection common drive waveform. / N (where N is a positive integer).

  According to this aspect, a plurality of micro-vibration waveform elements can be applied within one ejection cycle by using a micro-vibration common drive waveform having a higher frequency than the ejection common drive waveform. In addition, the discharge waveform element and the fine vibration waveform element can be combined and applied to the pressure generating element within one discharge cycle. In this case, it is further preferable to set the number of fine vibration waveform elements and the application position according to the discharge volume.

  According to a fifth aspect of the present invention, in the liquid ejection head drive device according to any one of the first to fourth aspects, the second drive waveform generating means may be configured as the micro-vibration common drive waveform. A binary rectangular wave is generated.

  By simply driving the micro-vibration with ON / OFF pulse control, the circuit configuration is simplified as long as the slope of the waveform is not controlled, and digital circuits can be connected directly without using a D / A converter. It becomes possible.

  The invention according to claim 6 provides a liquid ejection apparatus that achieves the object. That is, a liquid discharge apparatus according to a sixth aspect includes a liquid discharge head having a plurality of pressure generating elements provided corresponding to the plurality of nozzles and the pressure chambers communicating with the nozzles. And a liquid ejection head driving device according to any one of the preceding claims.

  The invention according to claim 7 provides an image forming apparatus that achieves the object. That is, an image forming apparatus according to a seventh aspect includes the liquid ejecting apparatus according to the sixth aspect, and forms an image on a recording medium by droplets ejected from the nozzle.

  According to the image forming apparatus of the present invention, the discharge cycle is shortened and the printing speed is increased as compared with the conventional method in which the fine vibration waveform element and the discharge waveform element are contained in one common drive waveform. Can do. Further, a fine vibration waveform element can be applied to the nozzles that are not ejected during the printing period according to the situation, and ejection failure can be prevented while maintaining print quality.

  The image forming apparatus controls ejection from the nozzles by controlling the driving of the pressure generating elements based on the image data, thereby realizing a desired dot arrangement.

  As a configuration example of the liquid discharge head, a full-line type inkjet head having a nozzle row in which a plurality of nozzles for ink discharge are arranged over a length corresponding to the entire width of the recording medium can be used.

  In this case, a plurality of relatively short ejection head blocks having nozzle rows that do not have a length corresponding to the full width of the recording medium are combined, and these are joined together to make the length long, so that the whole corresponds to the full width of the recording medium. There is an aspect that constitutes a nozzle row.

  A full-line type inkjet head is usually arranged along a direction perpendicular to the relative feeding direction (relative conveyance direction) of the recording medium, but at a certain angle with respect to the direction perpendicular to the conveyance direction. There may also be a mode in which the inkjet head is arranged along an oblique direction with a gap.

  A “recording medium” is a medium that can record an image by the action of a liquid ejection head (a medium that can be called a medium to be ejected, a printing medium, an image forming medium, a recording medium, an image receiving medium, etc.). Paper, sticker paper, resin sheet such as OHP sheet, film, cloth, printed circuit board on which a wiring pattern or the like is formed, intermediate transfer medium, and other various media and shapes are included.

  A transport unit that relatively moves the recording medium and the liquid ejection head transports the recording medium to the stopped (fixed) liquid ejection head, and a mode that moves the liquid ejection head to the stopped recording medium. Alternatively, both of the modes in which both the liquid discharge head and the recording medium are moved are included.

  In this specification, the term “printing” represents the concept of forming an image in a broad sense including characters.

  According to the present invention, the first drive waveform generating means for generating the common drive waveform for discharge and the second drive waveform generating means for generating the common waveform element for fine vibration are independently provided to discharge the liquid. While applying the discharge waveform element to the pressure generating element of the nozzle, at the same time as the application of the discharge waveform element, because it is configured to selectively apply the fine vibration waveform element to the pressure generating element of the nozzle that does not discharge liquid, Compared to the conventional method in which the fine vibration waveform element and the discharge waveform element are contained in one common drive waveform, the discharge cycle can be shortened.

  Moreover, instantaneous current consumption and power consumption can be suppressed by controlling the timing at which the minute vibration is applied to the nozzles that are not ejected during the ejection period. As a result, the circuit load can be reduced, the overall current consumption can be reduced, and the durability (life) of the pressure generating element can be improved as compared with the method of always performing microvibration.

  Furthermore, according to the present invention, when the drive waveform for ejection and the drive waveform for fine vibration are simultaneously applied to the pressure generating elements of different nozzles, at least one of the rising portion and the falling portion of the fine vibration waveform element is The discharge drive current and the micro-vibration drive current are reduced by not overlapping the rising or falling portion of the discharge waveform element applied to the pressure generating element corresponding to the nozzle that performs the discharge. The flow timing is distributed, and instantaneous current consumption can be suppressed.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Overall configuration of inkjet recording apparatus]
FIG. 1 is an overall configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention. As shown in the figure, the ink jet recording apparatus 10 includes a plurality of ink jet heads (hereinafter referred to as “ink jet heads”) corresponding to black (K), cyan (C), magenta (M), and yellow (Y) inks. A printing unit 12 having 12K, 12C, 12M, and 12Y, an ink storage / loading unit 14 that stores ink to be supplied to each of the heads 12K, 12C, 12M, and 12Y, and a recording sheet as a recording medium 16 is disposed opposite to the decurling unit 20 for removing the curl of the recording paper 16 and the nozzle surface (ink ejection surface) of the printing unit 12 to improve the flatness of the recording paper 16. A suction belt conveyance unit 22 that conveys the recording paper 16 while holding it, a print detection unit 24 that reads a printing result by the printing unit 12, and a discharge that discharges the recorded recording paper (printed material) to the outside. And parts 26, and a.

  The ink storage / loading unit 14 has an ink tank that stores ink of a color corresponding to each of the heads 12K, 12C, 12M, and 12Y, and each tank has a head 12K, 12C, 12M, and 12Y through a required pipe line. Communicated with. Further, the ink storage / loading unit 14 includes notifying means (display means, warning sound generating means) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. ing.

  In FIG. 1, a magazine for rolled paper (continuous paper) is shown as an example of the paper supply unit 18, but a plurality of magazines having different paper widths, paper quality, and the like may be provided side by side. Further, instead of the roll paper magazine or in combination therewith, the paper may be supplied by a cassette in which cut papers are stacked and loaded.

  When multiple types of recording paper are used, an information recording body such as a barcode or wireless tag that records paper type information is attached to the magazine, and the information on the information recording body is read by a predetermined reader. Thus, it is preferable to automatically determine the type of recording medium (media type) to be used and perform ink ejection control so as to realize appropriate ink ejection according to the media type.

  The recording paper 16 delivered from the paper supply unit 18 retains curl due to having been loaded in the magazine. In order to remove this curl, heat is applied to the recording paper 16 by the heating drum 30 in the direction opposite to the curl direction of the magazine in the decurling unit 20. At this time, it is more preferable to control the heating temperature so that the printed surface is slightly curled outward.

  In the case of an apparatus configuration that uses roll paper, a cutter (first cutter) 28 is provided as shown in FIG. 1, and the roll paper is cut into a desired size by the cutter 28. The cutter 28 includes a fixed blade 28A having a length equal to or greater than the conveyance path width of the recording paper 16, and a round blade 28B that moves along the fixed blade 28A. The fixed blade 28A is provided on the back side of the print. The round blade 28B is disposed on the printing surface side with the conveyance path interposed therebetween. Note that the cutter 28 is not necessary when cut paper is used.

  After the decurling process, the cut recording paper 16 is sent to the suction belt conveyance unit 22. The suction belt conveyance unit 22 has a structure in which an endless belt 33 is wound between rollers 31 and 32, and at least portions facing the nozzle surface of the printing unit 12 and the sensor surface of the printing detection unit 24 are horizontal ( Flat surface).

  The belt 33 has a width that is wider than the width of the recording paper 16, and a plurality of suction holes (not shown) are formed on the belt surface. As shown in FIG. 1, a suction chamber 34 is provided at a position facing the nozzle surface of the print unit 12 and the sensor surface of the print detection unit 24 inside the belt 33 spanned between the rollers 31 and 32. The recording paper 16 is sucked and held on the belt 33 by sucking the suction chamber 34 with a fan 35 to a negative pressure.

  When the power of the motor (reference numeral 88 in FIG. 7) is transmitted to at least one of the rollers 31 and 32 around which the belt 33 is wound, the belt 33 is driven in the clockwise direction in FIG. The held recording paper 16 is conveyed from left to right in FIG.

  Since ink adheres to the belt 33 when a borderless print or the like is printed, the belt cleaning unit 36 is provided at a predetermined position outside the belt 33 (an appropriate position other than the print area). Although details of the configuration of the belt cleaning unit 36 are not shown, for example, there are a method of niping a brush roll, a water absorbing roll, etc., an air blow method of blowing clean air, or a combination thereof. In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

  Although a mode using a roller / nip conveyance mechanism instead of the suction belt conveyance unit 22 is also conceivable, if the roller / nip conveyance is performed in the print area, the image easily spreads because the roller contacts the printing surface of the sheet immediately after printing. There is a problem. Therefore, as in this example, suction belt conveyance that does not bring the image surface into contact with each other in the print region is preferable.

  A heating fan 40 is provided on the upstream side of the printing unit 12 on the paper conveyance path formed by the suction belt conveyance unit 22. The heating fan 40 heats the recording paper 16 by blowing heated air onto the recording paper 16 before printing. Heating the recording paper 16 immediately before printing makes it easier for the ink to dry after landing.

  Each of the heads 12K, 12C, 12M, and 12Y of the printing unit 12 has a length corresponding to the maximum paper width of the recording paper 16 targeted by the inkjet recording apparatus 10, and the nozzle surface has a recording medium of the maximum size. This is a full-line type head in which a plurality of nozzles for ink discharge are arranged over a length exceeding at least one side (full width of the drawable range) (see FIG. 2).

  The heads 12K, 12C, 12M, and 12Y are arranged in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side in the recording paper 16 feed direction. 12K, 12C, 12M, and 12Y are fixedly installed so as to extend along a direction substantially orthogonal to the conveyance direction of the recording paper 16.

  A color image can be formed on the recording paper 16 by discharging different color inks from the heads 12K, 12C, 12M, and 12Y while transporting the recording paper 16 by the suction belt transporting section 22.

  As described above, according to the configuration in which the full-line heads 12K, 12C, 12M, and 12Y having nozzle rows that cover the entire width of the paper are provided for each color, the recording paper 16 and the printing unit in the paper feeding direction (sub-scanning direction). The image can be recorded on the entire surface of the recording paper 16 by performing the operation of moving the 12 relatively once (that is, by one sub-scan). Thereby, it is possible to perform high-speed printing as compared with a shuttle type head in which the recording head reciprocates in a direction orthogonal to the paper transport direction, and productivity can be improved.

  In this example, the configuration of KCMY standard colors (four colors) is illustrated, but the combination of ink color and number of colors is not limited to this embodiment, and light ink, dark ink, and special color ink are used as necessary. May be added. For example, it is possible to add an ink jet head that discharges light ink such as light cyan and light magenta. Also, the arrangement order of the color heads is not particularly limited.

  The print detection unit 24 shown in FIG. 1 includes an image sensor for imaging the droplet ejection result of the printing unit 12, and means for checking nozzle clogging and other ejection defects from the droplet ejection image read by the image sensor. Function as.

  The print detection unit 24 of this example is composed of a line sensor having a light receiving element array that is wider than at least the ink ejection width (image recording width) by the heads 12K, 12C, 12M, and 12Y. The line sensor includes an R sensor row in which photoelectric conversion elements (pixels) provided with red (R) color filters are arranged in a line, a G sensor row provided with green (G) color filters, The color separation line CCD sensor is composed of a B sensor array provided with a blue (B) color filter. Instead of the line sensor, an area sensor in which the light receiving elements are two-dimensionally arranged can be used.

  A test pattern or practical image printed by the heads 12K, 12C, 12M, and 12Y of each color is read by the print detection unit 24, and ejection determination of each head is performed. The ejection determination includes the presence / absence of ejection, measurement of dot size, measurement of dot landing position, and the like.

  A post-drying unit 42 is provided following the print detection unit 24. The post-drying unit 42 is means for drying the printed image surface, and for example, a heating fan is used. Since it is preferable to avoid contact with the printing surface until the ink after printing is dried, a method of blowing hot air is preferred.

  When printing on porous paper with dye-based ink, the weather resistance of the image is improved by preventing contact with ozone or other things that cause dye molecules to break by pressurizing the paper holes with pressure. There is an effect to.

  A heating / pressurizing unit 44 is provided following the post-drying unit 42. The heating / pressurizing unit 44 is a means for controlling the glossiness of the image surface, and pressurizes with a pressure roller 45 having a predetermined surface uneven shape while heating the image surface to transfer the uneven shape to the image surface. To do.

  The printed matter generated in this manner is outputted from the paper output unit 26. It is preferable that the original image to be printed (printed target image) and the test print are discharged separately. The ink jet recording apparatus 10 is provided with a sorting means (not shown) for switching the paper discharge path in order to select the print product of the main image and the print product of the test print and send them to the discharge units 26A and 26B. Yes. Note that when the main image and the test print are simultaneously formed in parallel on a large sheet, the test print portion is separated by a cutter (second cutter) 48. The cutter 48 is provided immediately before the paper discharge unit 26, and cuts the main image and the test print unit when the test print is performed on the image margin. The structure of the cutter 48 is the same as that of the first cutter 28 described above, and includes a fixed blade 48A and a round blade 48B.

  Although not shown in FIG. 1, the paper output unit 26A for the target prints is provided with a sorter for collecting prints according to print orders.

[Head structure]
Next, the structure of the head will be described. Since the structures of the respective heads 12K, 12C, 12M, and 12Y for each color are common, the heads are represented by the reference numeral 50 in the following.

  FIG. 3A is a plan perspective view showing an example of the structure of the head 50, and FIG. 3B is an enlarged view of a part thereof. 3C is a plan perspective view showing another structure example of the head 50, and FIG. 4 is a cross-sectional view showing a three-dimensional configuration of one droplet discharge element (an ink chamber unit corresponding to one nozzle 51). FIG. 4 is a sectional view taken along line 4-4 in FIG.

  In order to increase the dot pitch printed on the recording paper 16, it is necessary to increase the nozzle pitch in the head 50. As shown in FIGS. 3A and 3B, the head 50 of this example includes a plurality of ink chamber units including nozzles 51 serving as ink droplet ejection openings, pressure chambers 52 corresponding to the nozzles 51, and the like. It has a structure in which (droplet discharge elements) 53 are arranged in a zigzag matrix (two-dimensionally), and is thereby projected so as to be arranged along the head longitudinal direction (direction perpendicular to the paper feed direction). High density of substantial nozzle interval (projection nozzle pitch) is achieved.

  The configuration in which one or more nozzle rows are configured over a length corresponding to the entire width of the recording paper 16 in a direction substantially orthogonal to the feeding direction of the recording paper 16 is not limited to this example. For example, instead of the configuration of FIG. 3 (a), short head blocks 50 ′ in which a plurality of nozzles 51 are two-dimensionally arranged are arranged in a staggered manner and connected as shown in FIG. 3 (c). A line head having a nozzle row having a length corresponding to the entire width of the recording paper 16 may be configured.

  The pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape (see FIGS. 3 (a) and 3 (b)), and is connected to the nozzle 51 at both corners on a diagonal line. An outlet and an inlet (supply port) 54 for supply ink are provided.

  As shown in FIG. 4, each pressure chamber 52 communicates with a common flow channel 55 through a supply port 54. The common channel 55 communicates with an ink tank (not shown in FIG. 4, not shown in FIG. 6 and indicated by reference numeral 60) serving as an ink supply source, and the ink supplied from the ink tank 60 passes through the common channel 55 in FIG. Then, it is distributed and supplied to each pressure chamber 52.

  An actuator 58 (corresponding to a pressure generating element) having an individual electrode 57 is joined to a pressure plate (vibrating plate also serving as a common electrode) 56 constituting the top surface of the pressure chamber 52. By applying a driving voltage to the individual electrode 57, the actuator 58 is deformed to change the volume of the pressure chamber 52, and ink is ejected from the nozzle 51 due to the pressure change accompanying this. For the actuator 58, a piezoelectric element typified by a piezo element is preferably used. After ink discharge, new ink is supplied from the common channel 55 to the pressure chamber 52 through the supply port 54.

  As shown in FIG. 5, the ink chamber unit 53 having such a structure is latticed in a fixed arrangement pattern along a row direction along the main scanning direction and an oblique column direction having a constant angle θ not orthogonal to the main scanning direction. The high-density nozzle head of this example is realized by arranging a large number in the shape.

  That is, with a structure in which a plurality of ink chamber units 53 are arranged at a constant pitch d along a certain angle θ with respect to the main scanning direction, the pitch P of the nozzles projected so as to be aligned in the main scanning direction is d × cos θ. Thus, in the main scanning direction, each nozzle 51 can be handled equivalently as a linear arrangement with a constant pitch P. With such a configuration, it is possible to realize a high-density nozzle configuration in which 2400 nozzle rows are projected per inch (2400 nozzles / inch) so as to be aligned in the main scanning direction.

  When the nozzles are driven by a full line head having a nozzle row having a length corresponding to the entire printable width, (1) all the nozzles are driven simultaneously, (2) the nozzles are sequentially moved from one side to the other. (3) The nozzles are divided into blocks, and the nozzles are sequentially driven from one side to the other for each block, etc., and one line (1 in the width direction of the paper (direction perpendicular to the paper conveyance direction)) Driving a nozzle that prints a line of dots in a row or a line consisting of dots in a plurality of rows is defined as main scanning.

  In particular, when driving the nozzles 51 arranged in a matrix as shown in FIG. 5, the main scanning as described in (3) above is preferable. That is, nozzles 51-11, 51-12, 51-13, 51-14, 51-15, 51-16 are made into one block (other nozzles 51-21,..., 51-26 are made into one block, Nozzles 51-31,..., 51-36 as one block,...), And the nozzles 51-11, 51-12,. One line is printed in 16 width directions.

  On the other hand, by relatively moving the above-mentioned full line head and the paper, printing of one line (a line formed by one line of dots or a line composed of a plurality of lines) formed by the above-described main scanning is repeatedly performed. This is defined as sub-scanning. In the implementation of the present invention, the nozzle arrangement structure is not limited to the illustrated example.

[Configuration of ink supply system]
FIG. 6 is a schematic diagram showing the configuration of the ink supply system in the inkjet recording apparatus 10. The ink tank 60 is a base tank that supplies ink to the head 50 and is installed in the ink storage / loading unit 14 described with reference to FIG. In the form of the ink tank 60, there are a system that replenishes ink from a replenishing port (not shown) and a cartridge system that replaces the entire tank when the remaining amount of ink is low. A cartridge system is suitable for changing the ink type according to the intended use. In this case, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type. The ink tank 60 in FIG. 6 is equivalent to the ink storage / loading unit 14 in FIG. 1 described above.

  As shown in FIG. 6, a filter 62 is provided between the ink tank 60 and the head 50 in order to remove foreign matters and bubbles. The filter mesh size is preferably equal to or smaller than the nozzle diameter (generally about 20 μm). Although not shown in FIG. 6, a configuration in which a sub tank is provided in the vicinity of the head 50 or integrally with the head 50 is also preferable. The sub-tank has a function of improving a damper effect and refill that prevents fluctuations in the internal pressure of the head.

  Further, the inkjet recording apparatus 10 is provided with a cap 64 as a means for preventing the nozzle 51 from drying or preventing an increase in ink viscosity near the nozzle, and a cleaning blade 66 as a means for cleaning the nozzle surface 50A. . The maintenance unit including the cap 64 and the cleaning blade 66 can be moved relative to the head 50 by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the head 50 as necessary.

  The cap 64 is displaced up and down relatively with respect to the head 50 by an elevator mechanism (not shown). The cap 64 is lifted to a predetermined raised position when the power is turned off or during printing standby, and is brought into close contact with the head 50, thereby covering the nozzle surface 50 </ b> A with the cap 64.

  The cleaning blade 66 is made of an elastic member such as rubber, and can slide on the ink discharge surface (nozzle plate surface) of the head 50 by a blade moving mechanism (not shown). When ink droplets or foreign substances adhere to the nozzle plate, the nozzle plate surface is wiped by sliding the cleaning blade 66 on the nozzle plate to clean the nozzle plate surface.

  During printing or standby, when a specific nozzle is used less frequently and the ink viscosity in the vicinity of the nozzle increases, preliminary discharge is performed toward the cap 64 to discharge the deteriorated ink.

  When air bubbles are mixed in the ink in the head 50 (in the pressure chamber 52), the cap 64 is applied to the head 50, and the ink in the pressure chamber 52 (ink in which the air bubbles are mixed) is removed by suction with the suction pump 67. Then, the sucked and removed ink is sent to the collection tank 68. In this suction operation, the deteriorated ink that has increased in viscosity (solidified) is sucked out when the ink is initially loaded into the head 50 or when the ink is used after being stopped for a long time.

  If the head 50 is not ejected for a certain period of time, the ink solvent near the nozzles evaporates and the viscosity of the ink near the nozzles increases. Will not discharge. Therefore, before this state is reached (within the viscosity range in which ink can be discharged by the operation of the actuator 58), the actuator 58 is operated toward the ink receiver to discharge ink in the vicinity of the nozzle whose viscosity has increased. “Preliminary discharge” is performed. In addition, after the dirt on the surface of the nozzle plate is cleaned by a wiper such as a cleaning blade 66 provided as a cleaning means for the nozzle surface 50A, the foreign matter is prevented from entering the nozzle 51 by the wiper rubbing operation. Also, preliminary discharge is performed. Note that the preliminary discharge may be referred to as “empty discharge”, “purge”, “spitting”, or the like.

  In addition, if bubbles are mixed into the nozzle 51 or the pressure chamber 52 or if the viscosity increase of the ink in the nozzle 51 exceeds a certain level, ink cannot be ejected by the preliminary ejection, and the suction operation described below is performed.

  That is, when bubbles are mixed in the ink in the nozzle 51 or the pressure chamber 52, or when the ink viscosity in the nozzle 51 rises to a certain level or more, the ink can be ejected from the nozzle 51 even if the actuator 58 is operated. Disappear. In such a case, a suction means for sucking ink in the pressure chamber 52 with a pump or the like is brought into contact with the nozzle surface 50A of the head 50, and an operation of sucking ink mixed with bubbles or thickened ink is performed.

  However, since the above suction operation is performed on the entire ink in the pressure chamber 52, the ink consumption is large. Therefore, when the increase in viscosity is small, it is preferable to perform preliminary discharge as much as possible.

[Explanation of control system]
FIG. 7 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10. The inkjet recording apparatus 10 includes a communication interface 70, a system controller 72, an image memory 74, a ROM 75, a motor driver 76, a heater driver 78, a print control unit 80, an image buffer memory 82, a head driver 84, and the like.

  The communication interface 70 is an interface unit that receives image data sent from the host computer 86. As the communication interface 70, a serial interface such as USB, IEEE 1394, Ethernet, and wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted.

  Image data sent from the host computer 86 is taken into the inkjet recording apparatus 10 via the communication interface 70 and temporarily stored in the image memory 74. The image memory 74 is a storage unit that temporarily stores an image input via the communication interface 70, and data is read and written through the system controller 72. The image memory 74 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system controller 72 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 10 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. . That is, the system controller 72 controls each part of the communication interface 70, the image memory 74, the motor driver 76, the heater driver 78, etc., performs communication control with the host computer 86, read / write control of the image memory 74, and the like. A control signal for controlling the motor 88 and the heater 89 of the transport system is generated.

  The ROM 75 stores programs executed by the CPU of the system controller 72 and various data necessary for control. The ROM 75 may be a non-rewritable storage unit, or may be a rewritable storage unit such as an EEPROM. The image memory 74 is used as a temporary storage area for image data, and is also used as a program development area and a calculation work area for the CPU.

  The motor driver 76 is a driver (drive circuit) that drives the motor 88 in accordance with an instruction from the system controller 72. The heater driver 78 is a driver that drives the heater 89 such as the post-drying unit 42 in accordance with an instruction from the system controller 72.

  The print control unit 80 has a signal processing function for performing various processing and correction processing for generating a print control signal from the image data in the image memory 74 according to the control of the system controller 72, and the generated print It is a control unit that supplies data (dot data) to the head driver 84. Necessary signal processing is performed in the print control unit 80, and the ejection amount and ejection timing of the ink droplets of the head 50 are controlled via the head driver 84 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 80 includes an image buffer memory 82, and image data, parameters, and other data are temporarily stored in the image buffer memory 82 when image data is processed in the print control unit 80. In FIG. 7, the image buffer memory 82 is shown in a mode associated with the print control unit 80, but it can also be used as the image memory 74. Also possible is an aspect in which the print controller 80 and the system controller 72 are integrated and configured with one processor.

  The head driver 84 drives the actuators 58 of the heads 12K, 12C, 12M, and 12Y for each color based on the print data given from the print control unit 80. The head driver 84 may include a feedback control system for keeping the head driving conditions constant.

  Image data to be printed is input from the outside via the communication interface 70 and stored in the image memory 74. At this stage, RGB image data is stored in the image memory 74.

  The image data stored in the image memory 74 is sent to the print control unit 80 via the system controller 72, and the print control unit 80 converts it into dot data for each ink color by a known method such as dithering or error diffusion. Converted. That is, the print control unit 80 performs processing for converting the input RGB image data into KCMY four-color dot data. The dot data generated by the print controller 80 is stored in the image buffer memory 82.

  The head driver 84 generates a drive control signal for the head 50 based on the dot data stored in the image buffer memory 82. By applying the drive control signal generated by the head driver 84 to the head 50, ink is ejected from the head 50. An image is formed on the recording paper 16 by controlling the ink ejection from the head 50 in synchronization with the conveyance speed of the recording paper 16.

  As described with reference to FIG. 1, the print detection unit 24 is a block including a line sensor, reads an image printed on the recording paper 16, performs necessary signal processing, and the like to perform a print status (whether ejection is performed, droplet ejection And the detection result is provided to the print control unit 80.

  The print controller 80 performs various corrections on the head 50 based on information obtained from the print detector 24 as necessary. Further, the system controller 72 performs control to perform a predetermined recovery operation such as preliminary ejection, suction, or the like based on information obtained from the print detection unit 24.

  Further, the ink jet recording apparatus 10 of this example includes an ink information reading unit 92 and a temperature / humidity detection unit 94. The ink information reading unit 92 is means for acquiring ink type information. Specifically, for example, means for reading the ink physical property information from the shape of the cartridge of the ink tank 60 (a specific shape capable of identifying the ink type) or a barcode or IC chip incorporated in the cartridge is used. it can. In addition, the operator may input necessary information using a user interface.

  The temperature / humidity detection unit 94 is a block including detection means such as sensors for detecting the temperature and humidity of the environment in which the inkjet recording apparatus 10 is installed, and a sensor for detecting the temperature of ink.

  Information obtained from each means such as the ink information reading unit 92 and the temperature / humidity detection unit 94 is sent to the system controller 72 to prevent ink ejection control (control of ejection amount and ejection timing) and meniscus thickening prevention. It is used for the control of micro vibration drive.

  Next, a method for driving the head 50 in the inkjet recording apparatus 10 of this example will be described. FIG. 8 is a main part configuration diagram of main circuits related to head driving of the inkjet recording apparatus 10. A communication interface IC 102, a CPU 104, a ROM 75, a RAM 108, a line buffer 110, and a driver IC 112 are mounted on the circuit board 100 mounted on the inkjet recording apparatus 10.

  The communication interface IC 102 corresponds to the communication interface indicated by reference numeral 70 in FIG. The CPU 104 in FIG. 8 functions as the system controller 72 described in FIG. The RAM 108 in FIG. 8 functions as the image memory 74 described in FIG. 7, and the line buffer 110 in FIG. 8 functions as the image buffer memory 82 in FIG. Note that the memory 114 may be provided in place of or in combination with the line buffer 110. The memory 114 can share a part of the RAM 108.

  Details of the driver IC 112 shown in FIG. 8 will be described later (FIGS. 9 to 11). The driver IC 112 includes a head controller 116 (corresponding to the print control unit 80 described in FIG. 7), a D / A converter, A drive circuit element 118 such as an amplifier and a transistor (corresponding to the head driver 84 described in FIG. 7) is included. The driver IC 112 in FIG. 8 is electrically connected to the head 50 via a wiring member (for example, a wiring member in which a flexible cable and a rigid board are combined) 122 on which the switch IC 120 is mounted.

  The switch IC 120 includes a serial / parallel (S / P) conversion circuit and a switch element array. In addition, a power circuit 124 is connected to the circuit board 100, and power is supplied from the power circuit 124 to each circuit block.

  FIG. 9 is a main part configuration diagram of the driver IC 112 and the switch IC 120 including the head controller 116. As shown in the figure, the driver IC 112 mainly includes a head controller 116, an ejection drive waveform generation circuit 130 (corresponding to the first drive waveform generation means), and a fine vibration drive waveform generation circuit 132 (corresponds to the second drive waveform generation means). ), A selection circuit 134 is included.

  The switch IC 120 includes a shift register 140, a latch circuit 142, a level conversion circuit 144, and a switch element array 146, as shown. In FIG. 9, the actuators (piezoelectric elements) 58 of the head 50 are shown as capacitive loads together with the symbols OUT0, OUT1, OUT2,..., OUTn. The individual electrodes 57 of each actuator 58 (the left electrode in the capacitive load shown in FIG. 9) are connected to the terminals of the corresponding switch elements 146-i (i = 0, 1, 2... N), The other electrode (common electrode) of the actuator 58 is connected to the ground (GND).

  In this example, the head controller 116, the switch IC 120, and the selection circuit 134 function as “drive selection means”.

  The ejection drive waveform generation circuit 130 includes a waveform generation circuit 152 including a D / A converter (DAC) that converts the digital waveform data output from the head controller 116 into an analog signal, and the output level of the waveform generation circuit 152. Accordingly, an amplifier circuit 154 that amplifies the drive waveform and a push-pull circuit (not shown in FIG. 9) are configured. That is, the digital waveform data of the ejection drive waveform output from the head controller 116 is input to the waveform generation circuit 152, and converted into an analog waveform signal corresponding to the input waveform data by the waveform generation circuit 152. The analog waveform signal is amplified to a predetermined level by the amplifier circuit 154, is amplified by a push-pull circuit, and is then output as a drive waveform signal for ejection. The ejection drive waveform thus generated (ejection common drive waveform) is input to the “COM1” port of the selection circuit 134.

  Similarly, the fine vibration drive waveform generation circuit 132 includes a waveform generation circuit 156, an amplifier circuit 158, and a push-pull circuit (not shown in FIG. 9). The digital waveform data of the drive waveform for fine vibration output from the head controller 116 is input to the waveform generation circuit 156, and is converted into an analog waveform signal corresponding to the input waveform data by the waveform generation circuit 156. The analog waveform signal is amplified to a predetermined level by the amplifier circuit 158, power amplified using a push-pull circuit, and then output as a drive waveform signal for fine vibration. The fine vibration drive waveform generated in this way (the fine vibration common drive waveform) is input to the “COM 2” port of the selection circuit 134.

  The selection circuit 134 is a circuit (multiplexer) that selects one output signal from two inputs of the “COM1” port and the “COM2” port based on a control signal supplied from the head controller 116.

  FIG. 10 shows the configuration of the selection circuit 134 and its truth table. As shown in FIG. 5A, the selection circuit 134 has “Enabel”, “Select A”, and “Select B” as input ports for control signals in addition to the “COM1” port and the “COM2” port. And “COMOUT” as an output port. The control signals from the head controller 116 described with reference to FIG. 9 are input to the “Enabel”, “Select A”, and “Select B” ports.

  As shown in FIG. 10B, when “ENA (Enable)” is L (Low), “COMOUT” is in a high impedance state. When “ENA (Enable)” is H (High) and “Select A” and “Select B” are both L (Low), COM1 is output from “COMOUT”. When “ENA (Enable)” is H (High), “Select A” is L (Low), and “Select B” is H (High), COM2 is output from “COMOUT”.

  Although only one selection circuit 134 is shown in FIG. 9, actually, as shown in the detailed view of FIG. 11, switch elements 146-i () corresponding to the respective piezoelectric elements (OUT0, OUT1, OUT2,..., OUTn). A selection circuit 134-i (i = 0,1,2..., n) is provided for each i = 0,1,2.

  The output terminal of each selection circuit 134-i (i = 0, 1, 2... N) is connected to the input side end of the switch element 146-i (i = 0, 1, 2... N), respectively. The drive signal is selectively applied to each piezoelectric element (OUT0, OUT1, OUT2,..., OUTn) according to ON / OFF of the switch element 146-i (i = 0, 1, 2,..., N). It has become.

  Further, the head controller 116 shown in FIG. 9 generates print data developed into a dot pattern based on image information given from the host computer 86 (see FIG. 8), and also transmits a serial transmission clock signal (CLK). ) And a latch signal (LAT) for controlling the latch timing. The print data generated by the head controller 116 of FIG. 9 is transmitted (serial transmission) to the shift register 140 as print serial data SD together with the clock signal CLK in synchronization with the clock signal CLK. The print data stored in the shift register 140 is latched by the latch circuit 142 based on the latch signal LAT output from the head controller 116.

  The signal latched by the latch circuit 142 is converted by the level conversion circuit 144 into a predetermined voltage value that can drive the switch element 146-i (i = 0, 1, 2,..., N). The ON / OFF of the switch element 146-i (i = 0, 1, 2... N) is controlled by the output signal of the level conversion circuit 144.

  As described above, ejection is performed on the input side of the switch element 146-i (i = 0, 1, 2... N) via the selection circuit 13 6-i (i = 0, 1, 2... N). Since the common drive waveform (COM1) or the micro-vibration common drive waveform (COM2) is selectively applied, the piezoelectric elements (OUT0, OUT1, OUT2,..., OUTn) are controlled by controlling the opening / closing of the switch element 146-i. ) Is selectively applied (see FIG. 11).

  FIG. 12A is a waveform diagram showing an example of the ejection common drive waveform (COM1), and FIG. 12B is a waveform diagram showing an example of the micro-vibration common drive waveform (COM2). As shown in FIG. 12A, the common driving waveform 160 for ejection includes a first waveform element 161 for ejecting a small dot droplet (for example, 3 pl) and a medium dot droplet (for example, 6 pl). ) Is continuously connected to the second waveform element 162 for discharging, and a waveform obtained by combining the first waveform element 161 and the second waveform element 162 is repeated at a period T1.

  By applying the first waveform element 161 of the ejection common drive waveform 160 to the piezoelectric element, a small dot droplet is ejected, and by applying only the second waveform element 162, a medium dot droplet is ejected. The Further, by continuously applying the first waveform element 161 and the second waveform element 162 to the piezoelectric element, a large dot droplet (for example, 9 pl) is ejected.

  Note that the drive waveform application timing (ejection timing) varies within the ejection cycle T1 depending on the volume of the ejected droplet. The difference in the landing positions of small dots and medium dots due to this time difference is substantially the same on the recording medium. It is within the range that can be regarded as one pixel.

  On the other hand, as shown in FIG. 12B, the micro-vibration common drive waveform 170 is a waveform that vibrates the meniscus while suppressing the energy to the extent that ink is not ejected from the nozzle 51, and is shown in FIG. Compared with the ejection common drive waveform 160, the micro-vibration waveform element 171 having a smaller amplitude is repeated at a period T2 (<T1). In the example of the figure, the period (T2) of the common drive waveform 170 for fine vibration is set to 1/3 of the period (T1) of the common drive waveform 160 for discharge. The relationship between the period of 170 and the period of the ejection common drive waveform is not limited to this example. By applying the period of the micro-vibration waveform element 171 in the micro-vibration common drive waveform 170 to 1 / N (where N is a positive integer) of the period (T1) of the ejection common drive waveform 160, the application of the micro-vibration waveform Timing control is facilitated, which is preferable in terms of control.

  By controlling the selection circuit 134 and the switch element 146 described with reference to FIGS. 9 to 11, the first waveform element 161, the second waveform element 162, or the minute waveform element 162 shown in FIG. The vibration waveform element 171 can be selectively applied.

  FIG. 13A shows a waveform applied to the actuator 58 during small dot ejection, FIG. 13B shows a waveform applied during medium dot ejection, and FIG. 13C shows a waveform applied during large dot ejection. . The waveform (d) is a waveform applied when the meniscus is vibrated finely.

  In each of the waveform diagrams of FIGS. 13A to 13D, the portions indicated by A1 to A4, B1 to B4, C1 to C4, and D1 to D2 represent “n” on behalf of the letters “A” to “D”. (N = A, B, C, D), “n1” is the meniscus stabilization, “n2” is the meniscus pull, “n3” is the meniscus pull (ie, discharge), and “n4” is the next This corresponds to the state of preparation for discharge.

  A nozzle that performs ejection and a nozzle that does not perform ejection are determined based on the print data, and any one of the ejection waveforms in FIGS. 13A to 13C is applied to the nozzle that performs printing. Further, the waveform shown in FIG. 13D is applied to some or all of the nozzles that do not perform printing at an appropriate timing.

  In general, when a piezoelectric element is driven, the drive current flowing through the piezoelectric element is charged and discharged during the rising and falling periods of the driving waveform. In other words, a large drive current flows in a short time with a slope of the drive waveform, but almost no current flows at other times, so the average current consumption depends on the conditions of the drive waveform and drive frequency. 1/10 or less of the instantaneous current.

The drive current I that flows through the piezoelectric element is approximately equal to t = 4 μs (capacitance of one piezoelectric element C = 1 nF and a drive waveform applied voltage of 0 V to 40 V in a general discharge driving condition as a piezoelectric element type inkjet printer (through). (Rate 10V / μs)
I = C × V / t
= 1 [nF] × 40 [V] / 4 [μs]
= 10 [mA]
It becomes. From the above equation, it can be seen that the drive current I increases as the slew rate of the drive waveform increases (the steeper slope of the waveform).

  It can be seen that when the slope time is substantially constant as in the ON / OFF drive, the drive current increases as the voltage increases.

When the meniscus is finely vibrated, energy is not required to be discharged, so the slew rate is about 20% of the discharge driving. Therefore, using the above condition,
The drive current I due to slight vibration is
I = (C × V / t) × 0.2
= 2 [mA]
It becomes.

  If the driving target is only one piezoelectric element, the driving current is not so large. However, in the case of a line head system in which a large number of piezoelectric elements are arranged in an array, a very large number of piezoelectric elements are driven at the same time. Drive current must be supplied.

If M = 1000 piezoelectric elements (nozzles) are simultaneously driven to discharge, from the above equation,
I = (C × V / t) × M
= (1 [nF] × 40 [V] / 4 [μs]) × 1000
= 10 [A]
Thus, a driving current of 10 A flows at the moment of 4 μs.

  In accordance with the instantaneous current, the driving capability of the power source and the driving circuit must be increased. As a result, the circuit scale increases, resulting in an increase in cost and a situation in which the printer system cannot be established.

  Also, if the ejection drive waveform and the micro-vibration drive waveform are separated and driven at the same timing in order to realize a high-speed ejection cycle, in addition to the instantaneous current of the ejection drive, further micro-vibration drive The instantaneous currents overlap, and the instantaneous current becomes larger than expected. For this reason, not only does the voltage drop increase and the waveform quality deteriorates, the power supply capability may be exceeded.

  Therefore, in the present embodiment, the ejection drive circuit (ejection drive waveform generation circuit 130) and the fine vibration drive circuit (fine vibration drive waveform generation circuit 132) are separated, and the application of the fine vibration waveform element 171 is further performed. By controlling the timing, instantaneous current and instantaneous power are suppressed.

  Specifically, even in a period during which no ejection is performed during the printing period, the fine vibration waveform is not always given, and the application timing of the fine vibration waveform to the actuator (piezoelectric element) 58 is dispersed.

  FIG. 14 is a diagram illustrating an example of application control of a fine vibration drive waveform to a plurality of nozzles that do not perform ejection (printing). FIG. 14A shows a micro vibration common drive waveform 170, and FIGS. 14B to 14D show examples of micro vibration waveforms applied to different nozzles 1, 2 and 3, respectively. () Is a diagram showing the current consumption of micro-vibration driving according to (b) to (d).

  By selectively distributing the micro-vibration common drive waveform 170 shown in FIG. 14A to each piezoelectric element by the switch IC 120 shown in FIG. 9, the application shown in FIGS. 14B to 14D can be realized.

  As shown in FIGS. 14B to 14D, the waveform element is applied to the nozzle 1 at the timing of “part1” of the micro-vibration common drive waveform 170, and “part2” is applied to the nozzle 2. The waveform element is applied to the nozzle 3 at the timing “part3”.

  As already described, since the piezoelectric elements are charged and discharged at the rising and falling portions of the waveform elements (part1 to part3), the current consumption is as shown in FIG.

  In this way, by shifting the timing selectively and finely vibrating the meniscus of the nozzles 1 to 3, the instantaneous current and power can be reduced, and the entire current consumption can be reduced. In addition, during the non-printing period, instead of always applying the micro vibration drive waveform to the piezoelectric element, by applying the micro vibration drive waveform at an appropriate time interval, deterioration of the piezoelectric element is suppressed, and the product lifetime Can be lengthened.

  In FIG. 14, only three nozzles 1 to 3 are shown for convenience of explanation, but a mode in which the application timing of the vibration waveform is sequentially shifted for a larger number of nozzles is also possible. Further, as shown in FIG. 14, the instantaneous current consumption can be greatly suppressed by sequentially shifting the application timing of the fine vibration waveform for each nozzle, but in the practice of the present invention, the application timing for each nozzle is not necessarily limited. It is not limited to the mode of shifting. For example, among nozzles that are not ejected, a plurality of nozzles to which a fine vibration waveform is applied at the same timing are divided into groups (group 1 to which nozzle 1 belongs, group 2 to which nozzle 2 belongs, group 3 to which nozzle 3 belongs), and group units The timing of fine vibration may be controlled. In this case, although the fine vibration waveform is simultaneously applied to a plurality of nozzles belonging to the group, the instantaneous current can be suppressed as compared with the case where all the nozzles that are not ejected are simultaneously finely vibrated. Further, the load can be made uniform by making the number of nozzles that are finely vibrated simultaneously substantially the same at each timing.

  The condition for applying the drive waveform signal for fine vibration to the piezoelectric element is that it is physically required to suppress an increase in meniscus viscosity so that the ink can be stably ejected. There are also demands such as not discharging the ink, suppressing power consumption, and suppressing deterioration of the piezoelectric element. Therefore, it is desirable to control the drive waveform for fine vibration and its application according to the situation of the apparatus.

  For example, when the viscosity of the ink is high, it is desirable to apply a fine vibration waveform frequently in order to suppress an increase in viscosity. Conversely, if the viscosity of the ink is low, the vibration is small from the viewpoint of power consumption suppression. Reduce the frequency of driving.

  Examples of conditions that should be considered in the microvibration control and examples of control corresponding to the tendency of each situation include high (low) ink viscosity, long (short) non-ejection period, and low (high) temperature. Depending on low humidity (high), small volume (large) of ink ejected immediately before, small ejection of peripheral nozzles or small ink volume (large ejection or large ink volume) Thus, the number of micro-vibration waveform elements 171 (micro-vibration drive pulses) within the ejection cycle (drive cycle) T1 is increased (reduced), and the number of micro-vibration drive pulses within the printing period is increased (reduced). Control is performed such as increasing (lowering) the frequency of the micro-vibration driving pulse and applying the micro-vibration driving pulse on the front side (rear side) of the driving cycle.

  In this case, the period of the fine vibration waveform is within the period of the ejection drive waveform, and more preferably, the fine vibration waveform period is 1 / N of the discharge waveform period (where N is a positive integer).

  In this way, by controlling the micro-vibration waveform according to the conditions, it is possible not only to suppress the occurrence of defective ejection and maintain print quality, but also to suppress unnecessary micro-vibration, thus reducing average power consumption. And deterioration of the piezoelectric element can be suppressed.

  FIG. 15 shows an example of a fine vibration waveform applied to the piezoelectric element. (A) is a common drive waveform 170 for fine vibration, and (b) to (d) are examples of a fine vibration waveform controlled according to conditions. That is, FIG. 15B is an example in which the fine vibration waveform element 171 is applied with an application interval. When the viscosity of the ink is low, the application interval of the fine vibration waveform element 171 can be made relatively long. (C) controls the ON / OFF ratio of the fine vibration waveform. It is preferable to determine the ON / OFF ratio according to the non-ejection period of the nozzle and the power consumption (number of ejections). Further, (d) shows a case where the frequency of the fine vibration waveform is changed.

  If only the viewpoint of preventing thickening of the meniscus is regarded as important, it is preferable that the meniscus is always slightly vibrated. However, there is a problem from the viewpoints of occurrence of crosstalk, power consumption, etc. when micro vibrations are constantly performed. For this reason, it is preferable to perform control such that the OFF period of the ON / OFF ratio (duty) of the minute vibration is increased for the nozzles that are driven to discharge and the peripheral nozzles. That is, when neighboring nozzles are ejected, the crosstalk due to the ejection driving is actively used to prevent thickening of the meniscus of the peripheral nozzles.

  Also, the ON / OFF duty of the minute vibration applied to the discharge nozzle and the non-discharge nozzles in the vicinity thereof can be varied in accordance with the large dot discharge, medium dot discharge, or small dot discharge (depending on the discharge volume). Conceivable. When the discharge volume is large, the liquid in the flow path is refreshed, and the amount of movement of the liquid in the peripheral flow path is large, so that the OFF period of fine vibration can be set large.

  On the contrary, when the discharge volume is small, the refreshing effect of the liquid is small, so it is preferable to repeatedly give microvibration.

  Changes in the number of micro-vibration driving pulses applied to the piezoelectric element, its generation position (application timing), frequency, etc. are controlled by the switch IC 120 described in FIGS. 8 to 11 (control of the switching timing of the switch element 146). ), Or in place of or in combination with the control of the switch IC 120, may be performed by the waveform generation unit (that is, the head controller 116, the waveform generation circuit 156, etc.) of the digital circuit.

  FIG. 16 is a waveform diagram showing an example of a drive signal applied to the piezoelectric element. The same (a) shows an example in which small dot ejection signals are continuously applied. As shown in the figure, the first waveform element 161 that contributes to the ejection of small dots is applied at the period T1 of the ejection common drive waveform 160 described in FIG. 12, and a fine vibration waveform element 171 is added before and after that. . That is, it is possible to discharge small dots continuously with the period T1, while applying the combination of the fine vibration waveform element 171 and the first waveform element 161 within the time of one discharge period T1.

  FIG. 16B shows an example in which large dot ejection signals are continuously applied. As shown in the figure, by continuously applying a large dot ejection signal that is a combination of the first waveform element 161 and the second waveform element 162, it is possible to continuously eject large dots at the period T1. During this large dot continuous discharge period, the nozzle is not subjected to slight vibration, but since the discharge volume is large, the effect of increasing the viscosity is obtained by the discharge operation itself.

  Next, examples of other drive waveforms will be described.

  FIG. 17 shows an example using a fine vibration waveform having a higher frequency than the example of FIG. FIG. 17A shows the ejection common drive waveform 160 described with reference to FIG. As shown in FIG. 17A, the ejection common drive waveform includes a combination of a first waveform element (part 1 in the figure) 161 and a second waveform element (part 2 in the figure) 162. FIG. 17B is an example of the common drive waveform for fine vibration. FIGS. 17C to 18E show the selection circuit 134 and the switch element from the common drive waveform 160 for discharge and the common drive waveform 170 for fine vibration. 7 is a diagram illustrating an example of a drive signal applied to a piezoelectric element via 146. FIG. (C) shows an example of an applied drive signal at the time of small dot ejection, (d) shows an example of an applied drive signal at the time of middle dot ejection, and (e) shows an example of an applied drive signal at the time of large dot ejection.

  As shown in FIG. 8C, when small dots are ejected, the fine vibration waveform element 171 having a high frequency is applied before the first waveform element (part1) 161 for ejection is applied. Further, as shown in (d), during the middle dot ejection, the fine vibration waveform element 171 is applied before the second waveform element (part2) 162 for ejection is applied. The position is set one pulse before the fine vibration waveform element 171.

  In the large dot ejection shown in FIG. 5E, the first waveform element 161 and the second waveform element 162 for ejection are continuously applied (part1 + part2), and the fine vibration waveform element 171 is not applied.

  As illustrated in FIGS. 17C to 17E, depending on the dot size (droplet volume) to be ejected, the number of pulses of the fine vibration waveform element 171 (fine vibration drive pulse) and the application timing (of the fine vibration waveform element 171). It is preferable to set the application position), frequency, and the like.

  As already described, since current flows at the rising and falling portions of the drive waveform, when driving a plurality of nozzles simultaneously, as shown in FIG. It is preferable to control so that the rise and fall of the waveform do not overlap as much as possible.

  In the example of FIG. 18, the rising portion P 1 in the first waveform element (part 1) 161 of the ejection common drive waveform 160 does not overlap the rise portion Q 1 of the fine vibration waveform, and the flat portion of the ejection common drive waveform 160. P2 and the rising portion Q1 of the fine vibration waveform overlap each other. Further, the falling portions P3 and P5 of the discharge common drive waveform and the falling portion Q2 of the fine vibration waveform do not overlap, and the flat portion P4 of the discharge common drive waveform 160 and the falling portion Q2 of the fine vibration waveform are not overlapped. And overlap.

  On the other hand, in the relationship between the second waveform element (part2) 162 of the ejection common drive waveform 160 and the slight vibration waveform, the rising portion Q1 'of the fine vibration waveform overlaps with the rising portion P6 having a relatively small inclination. The falling portions P8 and Q2 'of the two do not overlap, and the flat portion P7 of the discharge common drive waveform and the falling portion Q2' of the fine vibration waveform overlap.

  In this way, when the ejection drive waveform has no slope (flat part) or a part with a small slope, the drive signal application timings for both are arranged so that the slope of the micro-vibration waveform overlaps that part. Has been adjusted.

  The fine vibration waveform may be given to all the nozzles other than the nozzle to be discharged, or the fine vibration waveform may be selectively given from the nozzles other than the nozzle to be discharged.

  Thereby, instantaneous current consumption can be further suppressed. In addition, when the rise and fall of the ejection drive waveform and the rise and fall of the minute vibration waveform overlap, select the part where each inclination is as gentle as possible and set it to overlap, Instantaneous current consumption can be suppressed. Alternatively, the discharge drive waveform inclination direction and the fine vibration waveform inclination direction are overlapped with each other in opposite directions (the rising portion of the discharge drive waveform and the falling portion of the fine vibration waveform are overlapped, or the discharge The falling part of the driving waveform and the rising part of the fine vibration waveform may be overlapped).

  It is preferable to control the micro-vibration drive so as to perform appropriate micro-vibration according to the state of the meniscus. Since it is difficult to directly detect the meniscus state, in this embodiment, the meniscus state is determined based on detection information such as temperature and humidity, image data, and the like, and fine vibration is controlled according to the determination result. .

  The fine vibration control is roughly divided into a control process (non-print process) during the non-print period and a control process (print process) during the print period. FIG. 19 is a flowchart showing a control procedure of non-printing processing in the present embodiment.

  When the non-printing process is started (step S210), first, various conditions necessary for determining the meniscus state are detected (step S212). For example, various types of information such as ink type, state, temperature, and humidity are read. Based on these detected conditions, the fine vibration table is set (step S214). The fine vibration table is a data table for defining a drive waveform for fine vibration, and sets a ratio, a period, a frequency, and the like.

  Next, nozzle state data is read (step S216). The nozzle state data includes data indicating the operating status (discharge history, discharge volume, non-discharge period, etc.) of each nozzle. This read data is analyzed (step S218), the previous discharge volume, non-discharge period, presence / absence of slight vibration, discharge volume from adjacent nozzles, etc. are grasped, and a meniscus of each nozzle is used using a predetermined determination table. Determine the state.

  Based on the result of the data analysis in step S218, the necessity of applying the fine vibration is determined, and the power consumption when performing the fine vibration drive is analyzed (step S220). The conditions for performing micro-vibration driving (waveform data of common driving waveform for micro-vibration, frequency, number of actuators to be driven simultaneously, etc.) are automatically set so as to suppress instantaneous power consumption when micro-vibration is applied as much as possible.

  A fine vibration waveform is applied to the head 50 in accordance with the setting in step S220, and the meniscus is vibrated to such an extent that it is not ejected (step S222). In step S224, it is determined whether printing has been started. If NO is determined (when printing is not started), the process returns to step S216, and the above processing (steps S216 to S224) is repeated.

  If YES is determined in step S224 (when printing is started), the non-printing process routine is terminated (step S226), and the process proceeds to the printing process shown in FIG.

  FIG. 20 is a flowchart showing the control procedure of the printing process in this embodiment.

  When the printing process starts (step S310), first, various conditions necessary for determining the state of the meniscus are detected (step S312). Similarly to step S212 in FIG. 19, for example, various types of information such as ink type, state, temperature, and humidity are read, and the fine vibration table is set based on these detected conditions (step S314 in FIG. 20).

  Next, image data is read for each array (one column in the main scanning direction) for the image to be printed (step S316). The read image data for one array is analyzed and converted into print data, the previous data history is analyzed, the discharge volume, the discharge volume from the adjacent nozzle, etc. are grasped, and a predetermined determination table is used. The state of the meniscus of each nozzle is determined (step S318).

  Based on the result of the data analysis in step S318, the necessity of applying the minute vibration is determined, and the power consumption when performing the minute vibration driving is analyzed (step S320). The conditions for performing micro-vibration driving (the waveform data of the common driving waveform for micro-vibration, the frequency, the number of elements to be driven simultaneously, etc.) are automatically set so as to suppress the instantaneous power consumption when applying micro-vibration as much as possible.

  In accordance with the print data obtained in step S318 and the setting in step S320, the application of the ejection drive waveform and the fine vibration waveform is controlled to eject ink from the nozzles necessary for printing, and the meniscus is selectively selected for the nozzles not used for printing. Slightly vibrate (step S322). In step S324, it is determined whether or not the image data to be printed has been completed. If NO is determined (if image data is present), the process returns to step S316 and the above-described processing (for the next one array of image data ( Steps S316 to S324) are repeated.

  In step S324, when YES is determined (when the image data is terminated), the printing process routine is terminated (step S326), and the flow proceeds to the non-printing process described with reference to FIG.

  As described above, according to the embodiment of the present invention, since the ejection drive circuit and the micro-vibration drive circuit are separated and the timing of micro-vibration is controlled, instantaneous current, instantaneous Power consumption can be suppressed, and not only instantaneous power consumption but also overall power consumption can be reduced.

  Furthermore, since the meniscus is vibrated while suppressing the slight vibration to such an extent that it cannot be ejected, there is no need for large energy, and unlike for ejection, there are a plurality of drive waveform elements that eject multiple types of ink droplets with different ink volumes. There is no need for complicated drive circuits to be generated.

  Therefore, a simple binary rectangular wave is prepared as the micro-vibration driving waveform instead of a complicated multi-value driving waveform (see FIG. 18A) such as a driving waveform for ejecting ink, and an ON / OFF pulse is prepared. A configuration for control is also possible. The driving by such a binary rectangular wave has a very simple circuit configuration as much as the inclination of the waveform is not controlled.

  For comparison, FIG. 21 shows a configuration example of a discharge drive circuit (a drive circuit configuration using a trapezoidal wave), and FIG. 22 shows a configuration example of a micro-vibration drive circuit using a binary rectangular wave.

  As shown in FIG. 21, the ejection drive circuit includes a D / A converter 182 for D / A converting digital waveform data, an operational amplifier 184, a charge / discharge circuit 186, and a push-pull circuit 188. The final output of the push-pull circuit 188 is fed back to the operational amplifier 184 so that the output is stabilized. With this configuration, the output (COM1) of the push-pull circuit 188 is applied to each piezoelectric element 58 via the selection circuit 134-i (not shown) and the switch element 146-i (not shown) described in FIG. Is done.

  On the other hand, as shown in FIG. 22, the drive circuit for fine vibration using a binary rectangular wave is configured by a buffer 192, an inverter 194, charge / discharge circuits 196 </ b> A and 196 </ b> B, and a push-pull circuit 198. Since this fine vibration driving circuit does not need to discharge liquid, it is only necessary to obtain an output signal (COM2) lower than the driving voltage required for discharging driving, and therefore a transistor (or MOSFET) having a low withstand voltage is used. Therefore, the circuit element can be composed of highly available parts or small products. It is also possible to directly connect a digital circuit without using a D / A converter or the like. The fine vibration drive is not limited to pulse control, and the drive voltage may be variable depending on conditions.

  In the above description, an inkjet recording apparatus has been illustrated as an example of an image forming apparatus, but the scope of application of the present invention is not limited to this. For example, the liquid ejection head driving apparatus and the liquid ejection apparatus of the present invention can be applied to a photographic image forming apparatus that applies a developing solution to a photographic paper in a non-contact manner. In addition, the application range of the liquid ejection head driving device and the liquid ejection device according to the present invention is not limited to the image forming apparatus, and various types of ejecting processing liquid and other various liquids toward the ejection target medium using the liquid ejection head. The present invention can be applied to these devices (coating device, coating device, wiring drawing device, etc.).

1 is an overall configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 1 is a plan view of a main part around a printing unit of the ink jet recording apparatus shown in FIG. Plane perspective view showing structural example of head Enlarged view of the main part of Fig. 3 (a) Plane perspective view showing another configuration example of a full-line head Sectional view along line 4-4 in Fig. 3 (a) Enlarged view showing the nozzle arrangement of the head shown in FIG. Schematic diagram showing the configuration of the ink supply system in the inkjet recording apparatus of this example Main block diagram showing the system configuration of the inkjet recording apparatus of this example Main part configuration diagram of main circuit related to head driving of ink jet recording apparatus of this example FIG. 9 is a configuration diagram of a main part of the driver IC and the switch IC in FIG. Explanation of operation of selection circuit Detailed configuration diagram of selection circuit (A) is a waveform diagram showing an example of the ejection common drive waveform (COM1), (b) is a waveform diagram showing an example of the micro-vibration common drive waveform (COM2). The figure which showed the example of the drive waveform applied to an actuator (piezoelectric element) The figure which showed an example of application control of the drive waveform for fine vibration to a plurality of nozzles Waveform diagram showing an example of a fine vibration waveform applied to an actuator (piezoelectric element) Waveform diagram showing an example of the drive signal applied to the actuator (piezoelectric element) (A) is a waveform diagram showing an example of a common drive waveform for ejection, (b) is a waveform diagram showing an example of a common drive waveform for fine vibration, and (c) is a waveform of a drive signal applied during small dot ejection. The figure which showed the example, The figure which showed the waveform example of the waveform example of the drive signal applied at the time of medium dot discharge, (e) The waveform example of the waveform example of the drive signal applied at the time of large dot discharge Illustration shown Waveform diagram showing an example of the relationship between the common drive waveform for ejection and the waveform for microvibration The flowchart which showed the control procedure of the non-printing process in this embodiment A flowchart showing a control procedure of printing processing in the present embodiment Main circuit diagram showing a configuration example of the ejection drive circuit (a drive circuit configuration using trapezoidal waves) Main part circuit diagram showing a configuration example of a driving circuit for micro vibration by a binary rectangular wave

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 12 ... Printing part, 12K, 12C, 12M, 12Y ... Head, 14 ... Ink storage / loading part, 16 ... Recording paper, 18 ... Paper feed part, 22 ... Adsorption belt conveyance part, 31, 32 ... Roller, 33 ... Belt, 34 ... Adsorption chamber, 35 ... Fan, 50 ... Head, 50A ... Nozzle surface, 51 ... Nozzle, 52 ... Pressure chamber, 58 ... Actuator, 72 ... System controller, 75 ... ROM, 80 ... Print Control unit 104 ... CPU, 108 ... RAM, 110 ... line buffer, 116 ... head controller, 112 ... driver IC, 118 ... driver circuit element, 120 ... switch IC, 130 ... ejection drive waveform generation circuit, 132 ... micro vibration Drive waveform generation circuit, 134... Selection circuit, 146... Switch element array, 160. 61 ... first waveform element, 162 ... second waveform element, 170 ... common drive waveform for micro-vibration, 171 ... slight vibration waveform component

Claims (7)

A liquid ejection head drive device for supplying a drive signal to a plurality of pressure generating elements provided corresponding to a plurality of nozzles to discharge liquid from the nozzles,
First drive waveform generating means for generating a common drive waveform for discharge including a plurality of discharge waveform elements for discharging a plurality of types of droplets having different volumes;
Second drive waveform generation means for generating a common drive waveform for fine vibration including a fine vibration waveform element for finely vibrating a meniscus to such an extent that liquid is not discharged from the nozzle;
At least one discharge waveform element of the common drive waveform for discharge is selectively applied to a pressure generating element of a nozzle that performs discharge among the plurality of nozzles, and fine vibration is performed from nozzles that do not perform discharge. Drive selection means for selecting a nozzle to be applied and applying at least one fine vibration waveform element of the common drive waveform for fine vibration to the pressure generating element of the selected fine vibration target nozzle;
A drive apparatus for a liquid discharge head, comprising: A liquid ejection head drive device for supplying a drive signal to a plurality of pressure generating elements provided corresponding to a plurality of nozzles to discharge liquid from the nozzles,
First drive waveform generating means for generating a common drive waveform for discharge including a plurality of discharge waveform elements for discharging a plurality of types of droplets having different volumes;
Second drive waveform generation means for generating a common drive waveform for fine vibration including a fine vibration waveform element for finely vibrating a meniscus to such an extent that liquid is not discharged from the nozzle;
At least one discharge waveform element of the discharge common drive waveform is selectively applied to a pressure generating element corresponding to a nozzle that performs discharge among the plurality of nozzles, and pressure generation corresponding to a nozzle that does not perform discharge Drive selection means for applying at least one fine vibration waveform element of the common drive waveform for fine vibration to an element;
The pressure generating element corresponding to the nozzle that does not perform the ejection when the drive waveforms are simultaneously applied to the pressure generating element corresponding to the nozzle that performs the ejection and the pressure generating element corresponding to the nozzle that does not perform the ejection At least one of the rising part and the falling part of the micro-vibration waveform element applied to the nozzle does not overlap the rising part or the falling part of the discharge waveform element applied to the pressure generating element corresponding to the nozzle that performs the discharge. Drive control means to control,
A drive apparatus for a liquid discharge head, comprising:   The drive selection means is a nozzle that finely vibrates based on at least one of the following conditions: liquid viscosity, non-ejection period, temperature, humidity, volume of liquid droplets ejected immediately before, volume of liquid ejected from surrounding nozzles And a fine vibration control means for controlling at least one of the number of fine vibration waveform elements applied to the frequency, the frequency of the fine vibration waveform elements, and the application timing of the fine vibration waveform elements. 3. A drive device for a liquid discharge head according to 1 or 2.   4. The liquid ejection according to claim 1, wherein the period of the common drive waveform for fine vibration is 1 / N (where N is a positive integer) of the period of the common drive waveform for ejection. Head drive device.   5. The liquid ejection head drive device according to claim 1, wherein the second drive waveform generation unit generates a binary rectangular wave as the common drive waveform for fine vibration. 6. A liquid ejection head having a plurality of pressure generating elements provided corresponding to each of the plurality of nozzles and each pressure chamber communicating with each nozzle;
A drive device for a liquid discharge head according to any one of claims 1 to 5,
A liquid ejection apparatus comprising: An image forming apparatus comprising the liquid ejection device according to claim 6, wherein an image is formed on a recording medium by droplets ejected from the nozzle.

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