JP4683295B2 - Liquid discharge head, liquid discharge apparatus, and liquid discharge method - Google Patents

Description

  The present invention relates to a liquid discharge head, a liquid discharge apparatus, and a liquid discharge method, and more particularly, to a droplet discharge technique that discharges a droplet of a minute size from a nozzle.

  In recent years, inkjet recording apparatuses (inkjet printers) have become widespread as recording apparatuses that print and record images taken by digital still cameras. An ink jet recording apparatus includes a plurality of nozzles in a head, and ink droplets are ejected from the nozzles onto a recording medium to record a desired image on the recording medium. In such an ink jet recording apparatus, the ink droplets ejected from the nozzles are miniaturized, and minute size dots formed by the minute size ink droplets are arranged at high density, thereby improving the image quality of the recorded image. . In order to arrange the dots of such small-sized ink droplets at high density, the size of the nozzles for discharging the ink droplets is miniaturized and the nozzles are arranged at high density in the inkjet head. Yes.

  Further, in a general ink jet recording apparatus, ink in a pressure chamber communicating with a nozzle is pressurized with a pressure generating element to form an ink liquid column from the nozzle to the outside, and this ink liquid column utilizes the interaction of force. In this way, ink droplets are formed. An ink droplet forming technique is realized in which the volume of ink droplets formed in this way is about several pl to 10 pl (including satellites).

The invention described in Patent Document 1 is a thermal method in which ink in a pressure chamber is heated to generate bubbles in the pressure chamber to discharge ink droplets, and the orifice plate is deformed to deform the pressure chamber. Gray tone recording is realized by changing the size of ink droplets ejected from the nozzles. Specifically, the volume of the pressure chamber can be changed directly by driving the piezoelectric body provided on the ink discharge port formation surface in synchronism with the heater (discharge force generation source) to thereby change the size of the ink droplet. Is changed in the range of several tens of pl to several hundred pl.
JP 7-156408 A

  However, in order to further improve image quality and gradation modulation, it is necessary to further reduce the ink droplet size, and to realize an ink droplet volume of less than 1 pl (however, only main droplets do not include satellites). is required. In addition, in order to land an ink droplet on a recording medium without accelerating the ink droplet after ejection, the ink droplet is ejected at a certain speed, that is, at a certain speed. It is necessary to divide the liquid column, and the shape of the liquid column until it is divided is thin and long with time. Therefore, if the liquid column division timing is delayed, there is a concern about the generation of satellites. If the satellite adheres to the ejection surface of the ink jet head, it causes a discharge abnormality, and if the satellite adheres to the recording medium, the image quality deteriorates.

  In order to perform image recording by causing a droplet (micro droplet) having a minute volume of less than 1 pl to land on a medium without acceleration after ejection, a liquid column formed thin and long from the nozzle to the outside is exposed to the outside of the nozzle. It is necessary to divide at an early timing later to form ink droplets. Further, when a high viscosity liquid is used to improve the image quality, the liquid column to be formed tends to be more difficult to break because it is formed thinner and longer due to the effect of viscosity. It is very difficult to divide such a thin and long liquid column at an early timing.

  In the invention described in Patent Document 1, a droplet size of several tens of pl to one hundred and several tens of pl is realized, but there is no description of a droplet of a further minute size having a volume of less than 1 pl, In the technique described in Document 1, it is considered difficult to realize an ink droplet having a droplet size of less than 1 pl that includes only main droplets and does not include satellites.

  The present invention has been made in view of such circumstances, and a liquid discharge head, a liquid discharge apparatus, and a liquid discharge method capable of forming a fine liquid droplet in which a main liquid droplet that does not contain satellites has a volume of less than 1 pl. The purpose is to provide.

  In order to achieve the above object, a liquid discharge head according to the present invention includes a nozzle, a pressure chamber communicating with the nozzle, a pressure generating element that pressurizes the liquid in the pressure chamber, and three or more actuators having the same shape. And an opening corresponding to the center of the nozzle opening between the actuators and a slit-like gap from the opening toward the periphery, and disposed on the liquid discharge side of the nozzle so as to cover the nozzle opening. An actuator block, and the liquid that has been pressurized by the pressure generating element and discharged from the opening is divided by deformation of the actuator to form a droplet having a predetermined volume.

  According to the present invention, since the columnar liquid (liquid column) ejected from the nozzle by the pressurization of the pressure generating element is divided at an early timing before being formed thin and long, a droplet having a minute volume of less than 1 pl Can be formed.

  The liquid discharge head may be a full-line head in which nozzles are arranged over the entire region in a direction substantially perpendicular to the conveyance direction of the discharge medium, or while moving the print head in a direction substantially orthogonal to the discharge medium conveyance direction. A shuttle scan type print head for discharging liquid may also be used.

  The medium to be ejected is a medium that receives the liquid ejected by the liquid ejection head, and is not limited to a continuous sheet, a cut sheet, a seal sheet, a resin sheet such as an OHP sheet, a film, a cloth, or any other material or shape. Includes media.

  A piezoelectric element (piezoelectric actuator) such as PZT or PVDF is preferably used as the pressure generating element.

  According to a second aspect of the present invention, there is provided the liquid ejection head according to the first aspect, wherein a space is provided between the deformed portion of the actuator and the nozzle.

  According to the second aspect of the present invention, the deformation of the deformed portion of the actuator is not constrained by providing the space between the deformed portion of the actuator and the nozzle.

  There is a mode in which a thin plate member is provided between the nozzle forming surface on which the nozzle is formed and the actuator, and the space portion is formed by providing an opening at a position corresponding to the nozzle of the thin plate member. It is preferable that the width (minimum width) of the space portion is greater than the nozzle radius and less than twice the nozzle diameter.

  According to a third aspect of the present invention, there is provided the liquid discharge head according to the first or second aspect, wherein a liquid repellent film is provided on a liquid discharge side surface of the nozzle and a liquid contact portion of the actuator. .

  According to the third aspect of the present invention, by forming the liquid repellent film on the nozzle forming surface and the liquid contact portion of the actuator, the liquid can be easily divided and the liquid contact surface can be made maintenance-free. .

  A fourth aspect of the invention relates to an aspect of the liquid discharge head according to the first, second, or third aspect, wherein the actuator includes a piezoelectric bimorph actuator.

  The piezoelectric bimorph actuator has a simple structure and good controllability, and can obtain a relatively large force with respect to its size.

  In order to achieve the above object, a liquid ejecting apparatus according to the invention described in claim 5 includes a nozzle, a pressure chamber communicating with the nozzle and containing a liquid ejected from the nozzle, and a liquid in the pressure chamber. A pressure generating element that pressurizes the pressure sensor and three or more actuators having the same shape, each having an opening corresponding to the center of the nozzle opening and a slit-shaped gap from the opening toward the periphery, between the actuators, An actuator block disposed on the liquid ejection side of the nozzle so as to cover the nozzle opening, and a drive signal supply means for supplying a drive signal to the actuator, and is pressurized by the pressure generating element from the opening. The discharged liquid is deformed and divided by the drive signal supplied from the drive signal supply means to form a droplet having a predetermined volume. Characterized in that it.

  There is an aspect in which the drive signal supply unit includes a waveform generation unit that generates a waveform of the drive signal, a voltage conversion unit that converts the drive signal into a predetermined voltage, and an output unit that outputs the drive signal converted into the predetermined voltage. .

  Control that provides pressure drive signal supply means for supplying a drive signal (control signal) to the pressure generating element and controls the drive signal supplied to the actuator block and the drive signal supplied to the pressure generating element in association with each other. There exists an aspect provided with a means.

  A sixth aspect of the invention relates to an aspect of the liquid ejection apparatus according to the fifth aspect, wherein all the actuators of the actuator block are substantially simultaneously driven by a common drive signal supplied from the drive signal supply means. It is characterized by that.

  According to the sixth aspect of the present invention, all the actuators of the actuator block are driven substantially simultaneously by the common drive signal, so that the deformation amounts of all the actuators become substantially the same, and the ink liquid formed by being divided by the actuators. No bending occurs in the direction of drop flight. Moreover, in the aspect using a common drive signal, reduction of the control load of a drive signal supply means is anticipated.

  In an aspect in which all actuators of the actuator block are driven with a common drive signal, there is an aspect in which a drive signal transmission member that transmits a drive signal supplied to all the actuators is made common.

  A seventh aspect of the invention relates to an aspect of the liquid ejection apparatus according to the fifth aspect, wherein at least one actuator of the actuator block is driven by an individual drive signal supplied from the drive signal supply means. It is characterized by.

  According to the seventh aspect of the present invention, when the actuators of the actuator block are configured to be individually driven, deflection control in the droplet flying direction and droplet volume control are possible.

  The present invention also provides a method invention for achieving the above object. That is, a liquid discharge method according to an eighth aspect of the present invention is a liquid discharge method of a liquid discharge head including a nozzle, a pressure chamber communicating with the nozzle, and a pressure generating element that pressurizes the liquid in the pressure chamber. In the method, a pressurizing step of pressurizing a liquid in the pressure chamber, and three or more identically shaped actuators are arranged between the actuator and an opening corresponding to the center of the nozzle opening and the opening toward the periphery. A liquid having a slit-like gap and outside the actuator block disposed on the liquid ejection side of the nozzle so as to cover the nozzle opening is divided by deforming the actuator. Forming a droplet having a desired volume.

  After the actuator is deformed to form an opening serving as a liquid passage (opening forming process), the liquid in the pressure chamber is pressurized and a predetermined amount of liquid is discharged from the opening through the nozzle (pressurizing process) ), An embodiment in which the actuator is turned off to divide the columnar liquid to form droplets (droplet forming step).

  According to the present invention, the columnar liquid (liquid column) ejected from the nozzle by the pressurization of the pressure generating element is divided at an early timing before being formed thin and long, so that the droplet having a minute volume of less than 1 pl. Can be formed.

  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 inkjet recording apparatus 10 includes a print unit 12 having a plurality of print heads 12K, 12C, 12M, and 12Y provided for each ink color, and each print head 12K, 12C, 12M, An ink storage / loading unit 14 for storing ink to be supplied to 12Y, a paper feeding unit 18 for supplying recording paper 16, a decurling unit 20 for removing curling of the recording paper 16, and a nozzle of the printing unit 12 The suction belt conveyance unit 22 that conveys the recording paper 16 while maintaining the flatness of the recording paper 16 and the printing result by the printing unit 12 is arranged opposite to the surface (ink ejection surface, not shown in FIG. 1). A print detection unit 24 for reading and a paper discharge unit 26 for discharging printed recording paper (printed matter) to the outside are provided.

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. Therefore, it is preferable to automatically determine the type of paper to be used and perform ink ejection control so as to realize appropriate ink ejection according to the type of paper.

  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. Then, the suction chamber 34 is sucked by the fan 35 to be a negative pressure, whereby the recording paper 16 on the belt 33 is sucked and held.

  When the power of a motor (not shown in FIG. 1, described as reference numeral 88 in FIG. 6) is transmitted to at least one of the rollers 31 and 32 around which the belt 33 is wound, the belt 33 rotates in the clockwise direction in FIG. , And the recording paper 16 held on the belt 33 is conveyed from left to right in FIG. Details of the belt 33 will be described later.

  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.

  The printing unit 12 is a so-called full line type head in which line type heads having a length corresponding to the maximum paper width are arranged in a direction (main scanning direction) orthogonal to the paper feed direction (see FIG. 2). Although a detailed structural example will be described later, each of the print heads 12K, 12C, 12M, and 12Y has a length that exceeds at least one side of the maximum size recording paper 16 targeted by the inkjet recording apparatus 10, as shown in FIG. A line type head in which a plurality of ink discharge ports (nozzles) are arranged is formed.

  A print head 12K corresponding to each color ink in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side along the feeding direction of the recording paper 16 (hereinafter referred to as the paper transport direction). , 12C, 12M, 12Y are arranged. A color image can be formed on the recording paper 16 by discharging the color inks from the print heads 12K, 12C, 12M, and 12Y while the recording paper 16 is conveyed.

  Thus, according to the printing unit 12 in which the full line head that covers the entire area of the paper width is provided for each ink color, the operation of relatively moving the recording paper 16 and the printing unit 12 in the sub-scanning direction is performed once. An image can be recorded on the entire surface of the recording paper 16 only by performing it (that is, in one sub-scan). Thereby, it is possible to perform high-speed printing as compared with a shuttle type head in which the print head reciprocates in the main scanning direction, and productivity can be improved.

  In this example, the configuration of KCMY standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink and dark ink are added as necessary. May be. For example, it is possible to add a print head that discharges light ink such as light cyan and light magenta.

  As shown in FIG. 1, the ink storage / loading unit 14 has tanks that store inks of colors corresponding to the print heads 12K, 12C, 12M, and 12Y, and each tank is connected via a conduit (not shown). The print heads 12K, 12C, 12M, and 12Y communicate with each other. Further, the ink storage / loading unit 14 includes notifying means (display means, warning sound generating means, etc.) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. is doing.

  The print detection unit 24 includes an image sensor for imaging the droplet ejection result of the print unit 12, and functions as a means for checking nozzle clogging and other ejection defects from the droplet ejection image read by the image sensor.

  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 print 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.

  The print detection unit 24 reads the test pattern printed by the print heads 12K, 12C, 12M, and 12Y for each color, and detects the ejection of each head. The ejection determination includes the presence / absence of ejection, measurement of dot size, measurement of dot landing position, and the like. In addition, the print detection unit 24 includes a light source (not shown) that irradiates light to the ejected dots.

  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 blocking the paper holes by pressurization. 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) that switches the paper discharge path so as 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. Reference numeral 26B denotes a test print discharge unit.

  Next, the structure of the print head 50 will be described. Since the structures of the print heads 12K, 12C, 12M, and 12Y provided for the respective ink colors are common, the print heads are represented by reference numeral 50 in the following.

  FIG. 3 (a) is a plan perspective view showing an example of the structure of the print head 50, and FIG. 3 (b) is an enlarged view of a part thereof. FIG. 3C is a perspective plan view showing another structural example of the print head 50. In order to increase the dot pitch printed on the recording paper surface, it is necessary to increase the nozzle pitch in the print head 50. As shown in FIGS. 3A to 3C, the print head 50 of this example includes a plurality of ink chamber units 53 including nozzles 51 from which ink is ejected and pressure chambers 52 corresponding to the nozzles 51. In this way, a high density of the apparent nozzle pitch is achieved.

  That is, as shown in FIGS. 3A and 3B, the print head 50 according to the present embodiment prints a plurality of nozzles 51 that eject ink in a direction substantially orthogonal to the print medium feed direction (paper feed direction). A full line head having one or more nozzle rows arranged over a length corresponding to the entire width of the medium.

  Further, as shown in FIG. 3 (c), short two-dimensionally arranged print heads 50 'may be arranged in a staggered manner and connected to form a length corresponding to the entire width of the print medium. Although not shown, short heads may be connected linearly. 3A and 3B, the nozzle 51, the pressure chamber 52, and the supply port 54 are indicated by broken lines.

  As shown in FIGS. 3A to 3C, the pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape, and the nozzle 51 and the nozzle 51 are located at both diagonal corners. A supply port 54 is provided. Moreover, each pressure chamber 52 is connected with the common flow path 55 via the supply port 54 (refer Fig.4 (a)).

  As shown in FIG. 3B, a large number of ink chamber units 53 having such a structure are arranged along a row direction along the main scanning direction and an oblique column direction having a constant angle θ that is not orthogonal to the main scanning direction. It has a structure that is arranged in a lattice pattern with a fixed arrangement pattern. 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. .

  That is, 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. Hereinafter, for convenience of explanation, it is assumed that the nozzles 51 are linearly arranged at a constant interval (pitch P) along the longitudinal direction (main scanning direction) of the head.

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

  In particular, when the nozzles 51 arranged in the matrix as shown in FIGS. 3A to 3C are driven, the main scanning as described in the above (3) is preferable. On the other hand, the sub-scan is defined as the above-described full-line head and the paper are moved relative to each other to repeatedly print a line composed of one row of dots or a line composed of a plurality of rows of dots formed by the above-described main scan. To do.

  That is, nozzle driving that prints a line formed by a single line of dots or a line formed by a plurality of lines in the width direction of the paper is referred to as main scanning, and a line or a plurality of lines formed by a single line formed by the main scanning. Repeatedly printing a line made up of dots is called sub-scanning. In the implementation of the present invention, the nozzle arrangement structure is not limited to the illustrated example.

  4A is a sectional view showing a three-dimensional configuration of the ink chamber unit (a sectional view taken along line 4-4 in FIGS. 3A and 3B), and FIG. FIG. 4C is a diagram for explaining the structure of the piezoelectric bimorph actuator.

  As shown in FIG. 4A, a pressure generating element (piezoelectric element) 58 having an individual electrode 57 is joined to the pressure plate 56 constituting the top surface of the pressure chamber 52. By applying the driving voltage, the pressure generating element 58 is flexibly deformed, the pressure chamber 52 is deformed, and the ink liquid column is ejected from the opening of the nozzle 51 (see FIG. 5B).

  The liquid column of the ink discharged from the opening of the nozzle 51 to the outside is divided by the actuator 102 and the actuator 104 (see FIG. 4B) provided on the opposite side (ink discharge side) of the nozzle 51 to 1pl. Micro-sized ink droplets having a volume of less than are formed. The minute size ink droplets are landed on the recording paper 16 to form minute size dots.

  When the pressurization of the ink in the pressure chamber 52 by the pressure generating element 58 is completed after the ink droplets are ejected, new ink is supplied to the pressure chamber 52 from the common channel 55 through the supply port 54.

  As shown in FIG. 4 (b), the actuator block 100 shown in this example includes four piezoelectric bimorph actuators 102 having the same shape and the same size, each having a piezoelectric active portion (deformed portion) having a substantially isosceles triangular plane shape. 104, 106, and 108. FIG. 4B shows a state where the piezoelectric active portions of the actuators 102, 104, 106, and 108 are not deformed.

  The actuator block 100 is disposed so that a perpendicular passing through the center of the opening of the nozzle 51 passes through the center of the actuator block 100, and an ink liquid column that is straight out from the opening of the nozzle 51 is at the center of the actuator block 100. A passing opening 113 is formed.

  That is, the actuators 102, 104, 106, 108 are arranged so that the apex angle at which the angle of the piezoelectric active portion of each actuator 102, 104, 106, 108 is approximately 90 ° is equidistant from the center of the actuator block 100, An opening 113 having a width w in the static state of the actuators 102, 104, 106, 108 is formed. The actuators 102, 104, 106, and 108 are arranged so that the width w of the opening 113 when the actuators 102, 104, 106, and 108 are stationary is smaller than the diameter D of the nozzle 51 (w <D).

  The diameter D of the nozzle 51 applied to this example is 1 μm ≦ D ≦ 100 μm. More preferably, 50 μm ≦ D ≦ 100 μm. That is, in this example, the ink discharge port is substantially equal to the minimum width (w ′, see FIGS. 5B and 5C) of the opening (reference numeral 113 in FIG. 5) when the actuators 102, 104, 106, and 108 are driven. Therefore, the diameter D of the nozzle 51 can be set to a value larger than w ′, and improvement in manufacturability of the nozzle opening is expected.

  The apex angle at which the angle of the actuator 102 is approximately 90 ° and the apex angle at which the angle of the actuator 104 is approximately 90 ° are opposed to each other at approximately the center of the actuator block 100, and the angle of the actuator 106 is approximately 90 °. And the apex angle at which the angle of the actuator 108 is approximately 90 ° are opposed to each other at approximately the center of the actuator block 100.

  The actuator 102 is disposed adjacent to the actuator 106 and the actuator 108 and opposed to the actuator 104, and the actuator 104 is disposed adjacent to the actuator 106 and the actuator 108 and opposed to the actuator 102.

  Similarly, the actuator 106 is disposed adjacent to the actuator 102 and the actuator 104 and facing the actuator 104, and the actuator 108 is disposed adjacent to the actuator 102 and the actuator 104 and facing the actuator 108. .

  Further, the actuators 102, 104, 106, and 108 are arranged apart from each other by a predetermined distance s so as not to physically interfere with each other. That is, it can be said that a space (groove portion) 110 having a width s is formed between adjacent actuators.

  In the actuator block 100 shown in FIG. 4B, the substantially square actuator block 100 has approximately the same shape and approximately the same area by two slit-shaped gaps 110 that intersect at approximately the center of the opening of the nozzle 51. It can be said that the actuator is divided into four actuators 102, 104, 106 and 108. In other words, the actuators 102, 104, 106, 108 have a structure in which the substantially square actuator block 100 is divided into four by two diagonal lines, and the width of the dividing groove (reference numeral 110) when dividing the actuator block 100 is s. It has become.

  Between the actuator block 100 and the nozzle 51 (nozzle plate on which the nozzle 51 is formed), a deformed portion (piezoelectric active portion) of the actuators 102, 104, 106, and 108 so as not to restrict the operation of the actuator block 100. Is provided with a space portion 112 (substantially square shape shown by a broken line in FIG. 4B).

  That is, as shown in FIG. 4A, an opening (hole) serving as a space 112 shown in FIG. 4B is provided between the nozzle plate on which the nozzle 51 is formed and the actuators 102, 104, 106, and 108. ) Having a space plate 114. An embodiment in which the thickness of the space plate 114 is substantially the same as the thickness of the actuators 102, 104, 106, 108 is preferable.

  Individual electrodes (not shown) to which drive signals are applied are formed in the piezoelectric active portions of the actuators 102, 104, 106, and 108. When drive signals are applied to the individual electrodes, the actuators 102, 104, 106, and 108 The piezoelectric active portion is deflected and the piezoelectric active portions of the actuators 102, 104, 106, and 108 are deformed in a direction substantially parallel to the ink ejection direction.

  By setting the width s of the slit-shaped gap 110 shown in FIG. 4B to be equal to or less than the radius of the nozzle 51 (s ≦ D / 2), at least a part of the opening of the nozzle 51 is actuators 102, 104, 106, Since it is covered with the piezoelectric active part 108, the ink liquid column ejected from the nozzle 51 can be reliably divided.

Further, the minimum width of the opening 113 formed at the center of the actuator block 100 where the two slit-shaped gaps 110 intersect (the width when the actuators 102, 104, 106, and 108 are stationary (when not deformed)) w Is represented by w = s × 2 ^1/2 , and when the actuators 102, 104, 106, 108 are deformed, the width w of the opening 113 (the opening area of the opening 113) increases. The maximum length L (corresponding to the height of a substantially isosceles triangle) of the piezoelectric active portion of each actuator 102, 104, 106, 108 is D / 2 <L, and is determined by the amount of displacement and the response frequency. Note that the maximum length L of the piezoelectric active portion of the actuators 102, 104, 106, and 108 in this example is calculated using the diameter D of the nozzle 51 and the arrangement pitch d of the nozzle 51 (see FIG. 3B). 2 <L <(d × sin θ) / 2 (where D <d).

  In the nozzle arrangement in which the nozzles are arranged in a matrix form as shown in FIG. 3B, the actuators 102, 104, 106, and 108 are arranged in an oblique direction (a direction that forms an angle θ with the main scanning direction) substantially parallel to the nozzle arrangement direction. Is arranged, the maximum length L of the piezoelectric active portion of the actuators 102, 104, 106, 108 is D / 2 <L <d / 2.

FIG. 4C is a cross-sectional view showing the structure of the piezoelectric bimorph actuator block 100 applied to the actuator block 100. As shown in FIG. 4 (c), the actuator block _100, by laminating a piezoelectric layer 100A and the piezoelectric layer 100B of two layers of _{d 31} mode, scissors electrode layer 100C that serves as a common electrode between them, Furthermore, an electrode layer 100D and an electrode layer 100E functioning as individual electrodes are respectively formed on the surfaces of the piezoelectric layer 100A and the piezoelectric layer 100B opposite to the electrode layer 100C.

  The piezoelectric layer 100A and the piezoelectric layer 100B are polarized so that the polarization directions are opposite. For example, when the piezoelectric layer 100A is polarized so that the piezoelectric layer 100A expands when a positive voltage is applied to the electrode layer 100D with the electrode layer 100C as a reference, the piezoelectric layer 100B becomes an electrode layer with the electrode layer 100C as a reference. When a positive voltage is applied to 100E, the piezoelectric layer 100B is polarized so as to contract.

  That is, when a positive voltage (drive signal) is applied to the electrode layer 100D and the electrode layer 100E with the electrode layer 100C as a reference, the piezoelectric layer 100A bends and deforms in the expansion direction and the piezoelectric layer 100B deforms in the contraction direction. The actuator block 100 is bent (deformed) so as to protrude in the direction of the piezoelectric layer 100A (upward in FIG. 4C). When the drive signal is not applied, the actuator block 100 is in a non-deformed state (static state). FIG. 4C shows a static state of the actuator block 100.

  The actuators 102, 104, 106 and 108 of the actuator block 100 divide the ink liquid column while deforming in the direction opposite to the traveling direction of the ink liquid column pressurized by the pressure generating element 58. It is necessary to generate a greater force. Further, a force larger than the pressure of the ink liquid column is generated by the piezoelectric active portion having an area less than ¼ of the area of the nozzle 51, and the response is equivalent to the ink ejection frequency (several tens of kHz to 100 kHz). It is necessary to correspond to the frequency. The piezoelectric bimorph actuator 1 shown in FIG. 4 (c) is an element that satisfies all the conditions of size, generated force, and response frequency, and is suitable for the actuator block 100 of the present invention.

  In the present embodiment, a method is employed in which ink is pressurized by deformation of a pressure generating element 58 typified by a piezo element (piezoelectric element). In implementing the present invention, an actuator other than the piezoelectric element can be applied to the pressure generating element 58. Alternatively, a thermal method may be applied in which ink inside the pressure chamber 52 is generated by a heater provided in the pressure chamber 52 to generate bubbles and the ink droplets in the pressure chamber 52 are heated by the bubbles. Good.

[Description of Ink Liquid Column Splitting Structure (Detailed Structure of Actuator Block 100), First Embodiment]
FIGS. 5A to 5D show ink by separating the ink liquid column 130 by the actuators 102 and 104 (only the actuators 102 and 104 of the actuator block 100 are shown in FIGS. 5A to 5D). It is a figure explaining the process in which the droplet 132 is formed, and is the enlarged view which expanded the vicinity (part shown by (circle) in FIG.4 (b)) of the nozzle 51. FIG.

  As shown in FIGS. 5 (a) to 5 (d), a surface that forms a space 112 on the outer side (opposite to the pressure chamber 52) of the nozzle plate on which the nozzle 51, which is a liquid contact portion in contact with ink, is formed. A liquid repellent film 120 (shown by a thick line) is formed on the surface that forms the slit-shaped gap 110 and the outer surface of the actuators 102, 104, 106, and 108 (the surface opposite to the space plate 114). Note that the actuator 106 and the actuator 108 are not shown in FIGS.

  That is, the outer surface of the nozzle plate that is the ink contact surface (the portion corresponding to the opening of the space plate 114 near the nozzle 51), the inner surface of the actuators 102, 104, 106, 108, the actuators 102, 104, 106, Since the liquid repellent film 120 having a predetermined liquid repellent performance is formed on the side surface 108 and the outer surface of the actuators 102, 104, 106, 108, the ink liquid column 130 (see FIGS. 5B to 5D). The discharge surface (the outer surface of the actuators 102, 104, 106, 108) is made maintenance-free.

  Here, a mechanism for dividing the ink liquid column by the actuators 102, 104, 106, and 108 will be described.

  FIG. 5A shows the static state of the actuators 102, 104, 106, and 108, and the discharge standby state. In the discharge standby state shown in FIG. 5A, a negative pressure is generated in the pressure chamber 52 (not shown in FIG. 5A) to form a meniscus surface 122 inside the nozzle 51, and the actuators 102, 104, 106 and 108 are all in a state in which no drive signal is applied.

  5B and 5C show the maximum deformation state of the actuators 102, 104, 106, and 108. FIG. In the maximum deformation state of the actuators 102, 104, 106, and 108 shown in FIGS. 5B and 5C, the same drive signal is applied to the actuators 102, 104, 106, and 108, and the actuators 102, 104, 106, and 108 are applied. The openings 113 formed by the side surfaces are radially spread evenly while maintaining the center position at the time of stabilization.

  The minimum width w ′ of the opening 113 in the maximum deformation state of the actuators 102, 104, 106, 108 shown in FIGS. 5B and 5C is not more than the diameter D of the nozzle 51 (w <w ′ ≦ D).

  When the pressure generating element 58 shown in FIG. 4A is operated in the maximum deformation state of the actuators 102, 104, 106, 108 to pressurize the ink in the pressure chamber 52, the ink liquid column 130 is externally connected via the nozzle 51. Extruded. FIG. 5B shows a state in which the ink liquid column 130 protruding outside the nozzle 51 enters the opening 113, and FIG. 5C shows a state in which the tip of the ink liquid column 130 protrudes from the opening 113. State.

  In this way, the four actuators 102, 104, 106, and 108 are deformed substantially at the same time by substantially the same amount to increase the opening area of the opening 113, so that the ink liquid column 130 is substantially perpendicular to the nozzle formation surface. Extruded.

  When the ink liquid column 130 shown in FIG. 5C protrudes outside the opening 113 and the volume of the protruding portion of the ink liquid column 130 reaches the desired volume of ink droplets, the actuators 102, 104, 106, and 108 are driven. In the process of turning off the actuators 102, 104, 106, and 108 with no signal applied and the actuators 102, 104, 106, and 108 returning from the maximum deformation state to the static state shown in FIG. A micro-sized ink droplet 132 is formed.

  FIG. 5D shows a state in which the tip portion (predetermined ejection volume portion) of the ink liquid column 130 protruding from the opening 113 is divided to form (discharge) a micro-sized ink droplet 132. is there.

  The minute size of the ink droplet in this example means that the volume of only the main droplet not containing satellite is less than 1 pl. As shown in FIGS. 5A to 5D, in the aspect having the actuators 102, 104, 106, and 108 (actuator block 100) as the means (mechanism) for dividing the ink liquid column 130, the generation of satellites is suppressed. However, a micro-sized ink droplet 132 having a volume of less than 1 pl is realized.

  In addition, since the ink liquid column 130 is divided by turning off the four actuators 102, 104, 106, and 108 at substantially the same timing, the ink droplet 132 is ejected in a direction substantially perpendicular to the nozzle formation surface (original ejection direction). Can be made.

[Description of supply system]
FIG. 6 is a schematic diagram showing the configuration of the ink supply system in the inkjet recording apparatus 10.

  The ink supply tank 60 is a base tank for supplying ink, and is installed in the ink storage / loading unit 14 described with reference to FIG. There are two types of ink supply tank 60: a system that replenishes ink from a replenishment 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.

  As shown in FIG. 6, a filter 62 is provided between the ink supply tank 60 and the print head 50 in order to remove foreign substances 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 print head 50 or integrally with the print 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.

  The mode in which the internal pressure is controlled by the sub tank includes a mode in which the internal pressure in the ink chamber unit 53 is controlled by the difference in the ink water level between the sub tank opened to the atmosphere and the ink chamber unit 53 in the head 50, and is connected to a sealed sub tank. There is a mode in which the internal pressures of the sub tank and the ink chamber are controlled by the pump that is used, and any mode may be applied.

  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.

  The maintenance unit including the cap 64 can be moved relative to the print head 50 by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the print head 50 as necessary.

  The cap 64 is displaced up and down relatively with respect to the print head 50 by an elevator mechanism (not shown). The cap 64 is raised to a predetermined raised position when the power is turned off or during printing standby, and is brought into close contact with the print head 50, thereby covering the ink discharge surface (the outer surface of the actuator block 100) with the cap 64.

  During printing or standby, if the frequency of use of a specific nozzle 51 is reduced and ink is not ejected for a certain period of time, the ink solvent near the nozzle evaporates and the ink viscosity increases. In such a state, ink cannot be ejected from the nozzle 51 even if the pressure generating element 58 operates.

  Before such a state is reached, the pressure generating element 58 is operated (within the range of the viscosity that can be discharged by the operation of the pressure generating element 58), and the deteriorated ink (ink near the nozzle whose viscosity has increased) should be discharged. Preliminary ejection (purging, idle ejection, spit ejection) is performed toward the cap 64 (ink receiver).

  Further, when air bubbles are mixed in the ink in the print head 50 (in the pressure chamber 52), the ink cannot be ejected from the nozzle even if the pressure generating element 58 is operated. In such a case, the cap 64 is applied to the print head 50, the ink in the pressure chamber 52 (ink mixed with bubbles) is removed by suction with the suction pump 67, and the suctioned and removed ink is sent to the collection tank 68. . In this suction operation, the deteriorated ink with increased viscosity (solidified) is sucked out when the ink is initially loaded into the head or when the ink is used after being stopped for a long time. Since the suction operation is performed on the entire ink in the pressure chamber 52, the amount of ink consumption increases. Therefore, it is preferable to perform preliminary ejection when the increase in ink viscosity is small.

[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 motor driver 76, a heater driver 78, a print control unit 80, an image buffer memory 82, a head driver 84, an actuator driver 85, 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 (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a 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 is a control unit that controls each unit such as the communication interface 70, the image memory 74, the motor driver 76, and the heater driver 78. The system controller 72 includes a central processing unit (CPU) and its peripheral circuits, and performs communication control with the host computer 86, read / write control of the image memory 74, and the like, as well as a transport system motor 88 and heater 89. A control signal for controlling is generated.

  The motor driver 76 is a driver (drive circuit) that drives the motor 88 in accordance with an instruction from the system controller 72. Although only the motor driver 76 and the motor 88 are shown in FIG. 7, the system controller 72 controls a plurality of motor drivers and motors.

  As an example, there are a motor for rotating the roller 31 (32) shown in FIG. 1, a motor for the cap moving mechanism described above, and the like.

  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 A control unit that supplies a control signal (print data) to the head driver 84. Necessary signal processing is performed in the print controller 80, and the ejection amount and ejection timing of the ink droplets of the print 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 a single processor.

  The head driver 84 drives the pressure generating element 58 of the print head 50 for each color based on the print data supplied from the print control unit 80. The head driver 84 may include a feedback control system for keeping the head driving conditions constant.

  The actuator driver 85 generates a drive signal for operating the actuators 102, 104, 106, and 108 (not shown in FIG. 7) of the actuator block 100 in response to the control of the pressure generating element 58, and a drive signal wiring (not shown). Is a functional block for sending the drive signal to the actuators 102, 104, 106, 108 via the.

  That is, the print control unit 80 controls the actuators 102, 104, 106, and 108 via the actuator driver 85 in response to the pressurization control of the pressure chamber 52 by the pressure generating element 58. The actuator driver 85 generates a drive signal for driving the actuators 102, 104, 106, and 108 based on the control signal sent from the print control unit 80. In other words, the actuator driver 85 generates a drive signal waveform of the actuators 102, 104, 106, and 108 from a control signal sent from the print control unit 80, and a block that converts the drive signal waveform into a predetermined voltage. And a block for outputting a drive signal.

[Explanation of drive signal]
Next, a drive signal (pressurization drive signal) applied to the pressure generating element 58 and a drive signal (separation drive signal) applied to the actuator block 100 will be described. FIG. 8A shows a dividing drive signal 200 applied to the actuators 102, 104, 106, 108 of the actuator block 100, and FIG. 8B shows a pressurizing signal applied to the pressure generating element 58. A drive signal 220 is shown. Note that, while waiting for discharge, a negative pressure is generated in the pressure chamber 52 to form a meniscus surface inside the nozzle 51 (see FIG. 5A), but in the pressurizing drive signal 220 shown in FIG. Waveform elements that generate negative pressure in the pressure chamber 52 during discharge standby are omitted.

  The dividing drive signal 200 shown in FIG. 8 (a) indicates that the actuators 102, 104, 106, and 108 are in a statically deformed state (see FIG. 5 (a)) to a maximum deformed state (see FIGS. 5 (b) and (c)). An expanded waveform 202 that expands the opening area of the opening 113 by maintaining the maximum deformation area of the actuators 102, 104, 106, and 108 and maintains the maximum opening area of the opening 113, and an actuator And a divided waveform 206 that divides the ink liquid column 130 in the process of returning 102, 104, 106, and 108 from the maximum deformation state to the static state.

  In addition, a pressurizing drive signal 220 shown in FIG. 8B includes a pressurizing waveform 222 for increasing the pressure generated by the pressure generating element 58 to a predetermined pressure for one pressurizing operation, and the pressure generating element 58. A constant pressure waveform 224 that maintains the generated pressure at the above-described predetermined pressure and a decompression waveform 226 that reduces the generated pressure of the pressure generating element 58 from the above-described predetermined pressure are configured.

Start timing t ₁ of shed drive signal 200 shown in FIG. 8 (a) is earlier by a predetermined period than the start timing t ₁₁ of the pressurizing driving signals 220 shown in Figure 8 (b). That is, the actuators 102, 104, 104 are operated so that the pressure generating element 58 is operated to pressurize the ink in the pressure chamber 52 after the actuators 102, 104, 106, 108 are operated to maximize the opening area of the opening 113. , 106, 108 and the pressure generating element 58 are controlled.

Further, the start timing t ₂ of the divided waveform 206 of shed drive signal 200 is in the period of constant pressure waveform 224 for pressurization drive signal 220, the actuator while maintaining the pressure generated by the pressure generating element 58 at a predetermined pressure The dividing operation of the ink liquid column 130 of the block 100 is started.

Changing the start timing _{t 2} of the divided waveform 206 of shed drive signal 200, it is possible to change the volume of the ink liquid column 130 exiting the opening 113 to the outside, the ink liquid column 130 by the start timing _{t 2} of the divided waveform 206 The volume of the ink droplet 132 formed by being separated from the ink is controlled.

The end timing t ₂₁ of the pressurizing drive signal 220 is later than the end timing t ₃ of the dividing drive signal 200. That is, after the operation of dividing the ink liquid column 130 is completed, the pressure chamber 52 is depressurized by the pressure generating element 58. The dividing waveform of the dividing drive signal 200 may be a waveform indicated by reference numeral 206 ′ or reference numeral 206 ″ in FIG. 8A. In the divided waveform 206 ′ in FIG. t ₃ ′ is substantially the same timing as the end timing t ₂₁ of the pressurization drive signal 220, and the end timing t ₃ ″ of the divided waveform 206 ″ is later than the end timing t ₂₁ of the pressurization drive signal 220.

  The drive signals supplied to the pressure generating element 58 and the actuators 102, 104, 106, and 108 described above are merely examples, and the actuator 102 is started before the pressure generating element 58 starts to press the ink in the pressure chamber 52. , 104, 106, and 108 are operated, and the pressure generating element 58 and the actuators 102, 104, 106, and 108 may be controlled so that the opening area of the opening 113 becomes a predetermined area.

  It is also possible to vary the volume of the ink droplet 132 by changing the opening area of the opening 113. That is, when the opening area of the opening 113 at the start of pressurization by the pressure generating element 58 is increased, the volume of the ink droplet 132 is increased, and when the opening area of the opening 113 at the start of pressurization by the pressure generating element 58 is decreased. The volume of the ink droplet 132 is reduced.

  In the ink jet recording apparatus 10 configured as described above, an ink block 130 provided outside the nozzle plate on which the nozzle 51 is formed (the outermost surface of the print head 50) is provided with the ink liquid column 130 that is discharged from the nozzle 51. Since it is configured to be divided using 100, the ink liquid column can be divided before the ink liquid column is formed to be thin and long, and a micro-sized ink droplet having a volume of less than 1 pl can be formed. It is.

  The actuator block 100 includes four actuators 102, 104, 106, and 108 having piezoelectric active portions having substantially the same area, and the four actuators 102, 104, 106, and 108 are arranged on the outer periphery of the opening of the nozzle 51. Accordingly, since the actuators 102, 104, 106, and 108 are operated at substantially the same amount by substantially the same amount by the inkjet head, the ink droplet 132 formed by dividing the ink liquid column 130 is made substantially perpendicular to the ink ejection surface. You can fly.

  In this example, the aspect in which the actuator block 100 is configured from the four actuators 102, 104, 106, and 108 has been shown. However, the number of actuators configuring the actuator block 100 is not limited to four, and may be three or five. The above may be used, and the actuators are arranged evenly along the outer circumference of the opening of the nozzle 51 so that the actuators do not physically interfere (the actuators constituting the actuator block are symmetrical even if they are rotated by a predetermined angle with respect to the center of the actuator block 100). It is sufficient if the arrangement is maintained). In addition, the aspect which sets the number of the actuators which comprise an actuator block to 4 from a viewpoint on manufacture or a viewpoint on control is preferable.

  In this example, the four actuators 102, 104, 106, and 108 are operated substantially simultaneously with substantially the same drive signal (the pressurization drive signal 220 in FIG. 8A), so that the drive signals are supplied to these individual electrodes. A common drive signal wiring may be used.

  Further, the liquid repellent film 120 is formed on the outer surface of the nozzle plate and the inner surface, side surface (opening 113 forming surface), and outer surface of the actuators 102, 104, 106, 108, so that the ink liquid column can be easily divided. The portion where the liquid repellent film 120 is formed can be made maintenance-free.

  As the above-described method for manufacturing the print head 50, a manufacturing method in which a plurality of cavity plates are stacked and these cavity plates are joined by pressure heating and a joining member is suitably used.

  The actuators 102, 104, 106, and 108 constituting the actuator block 100 are formed by dividing into four by dicing or a semiconductor process after an integral bimorph piezoelectric element is formed at a predetermined position. By using such a manufacturing method, the actuators 102, 104, 106, 108, the slit-shaped gap 110, and the opening 113 can be formed with high accuracy.

[Second Embodiment, Volume Control of Ink Droplet]
Next, a second embodiment of the present invention will be described. FIG. 9 is a diagram illustrating ink droplet ejection control according to the second embodiment of the present invention. In FIG. 9, parts that are the same as or similar to those in FIG. 4A are given the same reference numerals, and descriptions thereof are omitted.

  As shown in the figure, a common drive signal is applied to the actuator 102 and the actuator 104 among the actuators 102, 104, 106, and 108 constituting the actuator block 100, and a common drive signal is applied to the actuator 106 and the actuator 108. Is applied. Separate drive signals are applied to the pair of actuators 102 and 104 and the pair of actuators 106 and 108.

  That is, the drive signals of two actuator pairs composed of two opposing actuators are made common, and the two actuator pairs can be individually driven, so that the opening area of the opening 113 can be varied to change the ink droplets. The discharge volume can be varied.

  Specifically, when the actuator pair including the actuator 102 and the actuator 104 is simultaneously driven by a common drive signal and the actuator pair including the actuator 106 and the actuator 108 is not driven (or the deformation amount of the actuator 106 and the actuator 108 is reduced). Thus, when the four actuators 102, 104, 106, 108 are simultaneously driven with the common drive signal, the opening area of the opening 113 becomes smaller than when the four actuators 102, 104, 106, 108 are simultaneously driven with the common drive signal. , 104, 106, 108 are simultaneously driven by a common drive signal, and when the pressure applied by the pressure generating element 58 and the operation timing of the actuator 102 and the actuator 104 are substantially the same, the four actuators 102, 104 Ejection volume of the ink droplets as compared with the case of simultaneously driving the 106 and 108 by a common driving signal is reduced.

  Further, since the two actuator pairs are simultaneously driven by a common drive signal, the ink droplets can be ejected without causing a flight direction curve.

  Note that the drive signal wiring that supplies the drive signal to the actuators (in this example, the actuator 102 and the actuator 104, and the actuator 106 and the actuator 108) that are simultaneously driven by the common drive signal may be shared.

  According to the second embodiment described above, the actuator pair composed of two opposing actuators is simultaneously driven by a common drive signal, and the two actuator pairs are individually driven to vary the opening area of the opening 113. Thus, the volume of the ink droplet can be varied. Also, since the two actuator pairs are simultaneously driven by a common drive signal, no bending occurs in the flying direction of the ink droplets.

  That is, the volume of ink droplets can be controlled by making the deformation amounts of the two pairs of actuators different. Further, when the actuator pairs are simultaneously driven with a common drive signal, no flying bend occurs in the ink droplet ejection direction.

[Third embodiment, control of flying direction of ink droplets]
Next, a third embodiment of the present invention will be described. FIGS. 10A and 10B are diagrams illustrating ink droplet ejection control according to the third embodiment of the present invention. In FIG. 10 (a), the same or similar parts as in FIGS. 4 (a) and 9 are denoted by the same reference numerals, and in FIG. 10 (b), the same or similar parts as in FIG. The description thereof will be omitted.

  In the ink droplet ejection control according to the third embodiment, the opposing actuators (in this example, the actuator 102 and the actuator 104, or the actuator 106 and the actuator 108) are individually driven to change the flying direction of the ink droplets. Deflection is possible.

  As shown in FIG. 10A, the actuator 102 and the actuator 104 are individually controlled by individual drive signals, and the actuator 106 and the actuator 108 are simultaneously driven by a common drive signal. Note that the drive signal wiring of the actuator 106 and the actuator 108 driven by a common drive signal may be shared.

  FIG. 10B shows a state in which the flying direction of the ink droplet is deflected by individually driving the actuator 102 and the actuator 104. As shown in FIG. 10B, when the actuator 102 is not driven and the actuator 104 is driven with a predetermined drive signal, the ink liquid column 130 formation direction is bent toward the actuator 102, and the ink liquid column 130 is moved by the actuator 104. The flying direction of the ink droplet 132 formed by being divided is deflected from the vertical direction (the flying direction of the ink droplet 132 when the flying direction is not deflected) to the actuator 102 side (left side in FIG. 10B). Can do.

  Note that when the actuator 102 and the actuator 104 are individually driven, the actuator 106 and the actuator 108 (both not shown in FIG. 10B) may be simultaneously driven by a common drive signal, or both may be non-driven. Good.

  FIG. 10B shows a mode in which the actuator 102 is not driven and the actuator 104 is driven to deflect the flying direction of the ink droplet 132 toward the actuator 102. However, the actuator 102 is driven and the actuator 104 is not driven. Then, the flying direction of the ink droplet 132 can be deflected to the actuator 104 side.

  Although not shown, when the actuator 102 and the actuator 104 are not driven or simultaneously driven with a common drive signal, and the actuator 106 and the actuator 108 are individually driven with an individual drive signal, the flying direction of the ink droplets is changed to the actuator 106 side or You may deflect to the actuator 108 side.

  In this way, of the two actuator pairs composed of two opposing actuators, one actuator pair individually drives two actuators, and the other actuator pair simultaneously drives two actuators with a common drive signal (or , Non-driving), the flying direction of the ink droplet can be deflected.

  When the actuator 102 and the actuator 104 are individually driven and the actuator 106 and the actuator 108 are simultaneously driven by a common drive signal, the flying direction of the ink droplet 132 is set in a direction substantially parallel to the main scanning direction shown in FIG. When the actuator 102 and the actuator 104 are simultaneously driven by a common drive signal and the actuator 106 and the actuator 108 are individually driven, the ink droplets 132 fly in the sub-scanning direction shown in FIG. The direction can be deflected.

  The actuators 102, 104, 106, and 108 may be individually controlled. For example, when the adjacent actuator 102 and actuator 106 are driven and the actuator 104 and actuator 106 are not driven, the flying direction of the ink droplet 132 is set to an oblique direction that forms an angle of approximately 45 degrees with the main scanning direction and the sub-scanning direction. Can be deflected.

  That is, by selectively driving one to three of the four actuators 102, 104, 106, and 108, the flying direction of the ink droplet 132 can be controlled on a two-dimensional plane. Further, the volume of the ink droplet 132 can be varied by varying the deformation amount of the four actuators 102, 104, 106 and 108.

  The relationship between the driving actuator and the flying direction of the ink droplets and the relationship between the deformation amount of the driving actuator and the volume of the ink droplets are stored in advance as a data table. A mode in which necessary data is read from the data table at the time of droplet discharge control) is preferable.

  When the above-described ink droplet flight direction control is used, even in a mode in which the diameter D of the nozzle 51 (see FIG. 4B) is increased and the arrangement density of the nozzles 51 is sparse, a plurality of landing positions from the same nozzle. Since ink droplets can be landed at (dot formation position), the dot density can be increased.

  In the embodiment of the present invention described above, the ink jet recording apparatus 10 that forms a color image on the recording paper 16 by ejecting ink droplets on the recording paper 16 has been described. However, the scope of the present invention is applied to the ink jet recording apparatus. The present invention is not limited, and the present invention can be applied to a liquid discharge apparatus that discharges liquids such as water, chemical liquid, and processing liquid from discharge holes (nozzles) provided in the head.

  INDUSTRIAL APPLICABILITY The present invention can obtain a particularly great effect in a liquid discharge head that discharges a high-viscosity liquid whose viscosity increases by containing a functional substance, and a liquid discharge apparatus that includes the liquid discharge head.

1 is a basic configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 1 is a plan view of the main part around the printing of the ink jet recording apparatus shown in FIG. Plane perspective view showing structural example of print head Diagram showing the three-dimensional structure of the print head The figure explaining the ink discharge control of 1st Embodiment of this invention. Schematic diagram showing the configuration of the ink supply unit in the inkjet recording apparatus according to the present embodiment Main part block diagram which shows the system configuration | structure of the inkjet recording device which concerns on this embodiment. The figure explaining the drive signal applied to a pressure generating element and an actuator The figure explaining the ink discharge control of 2nd Embodiment of this invention. The figure explaining the ink discharge control of 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device 50, 50 '... Print head, 51 ... Nozzle, 52 ... Pressure chamber, 58 ... Pressure generating element, 80 ... Print control part, 84 ... Head driver, 85 ... Actuator driver, 100 ... Actuator block, 102, 104, 106, 108 ... Actuator, 113 ... Opening, 200 ... Dividing drive signal, 220 ... Pressurizing drive signal

Claims (8)

A nozzle,
A pressure chamber communicating with the nozzle;
A pressure generating element that pressurizes the liquid in the pressure chamber;
Three or more actuators having the same shape have an opening corresponding to the center of the nozzle opening between the actuators and a slit-like gap from the opening toward the periphery, and cover the nozzle opening. An actuator block disposed on the liquid discharge side of
With
A liquid discharge head, wherein the liquid pressurized by the pressure generating element and discharged from the opening is divided by deformation of the actuator to form droplets having a predetermined volume.   The liquid discharge head according to claim 1, further comprising a space between the deformed portion of the actuator and the nozzle.   The liquid discharge head according to claim 1, wherein a liquid repellent film is provided on a liquid discharge side of the nozzle and a liquid contact portion of the actuator.   The liquid ejection head according to claim 1, wherein the actuator includes a piezoelectric bimorph actuator. A nozzle,
A pressure chamber communicating with the nozzle and containing a liquid to be discharged from the nozzle;
A pressure generating element that pressurizes the liquid in the pressure chamber;
Three or more actuators having the same shape have an opening corresponding to the center of the nozzle opening between the actuators and a slit-like gap from the opening toward the periphery, and cover the nozzle opening. An actuator block disposed on the liquid discharge side of
Drive signal supply means for supplying a drive signal to the actuator;
With
The liquid pressurized by the pressure generating element and discharged from the opening is deformed and divided by the drive signal supplied from the drive signal supply means to form a droplet having a predetermined volume. A liquid ejecting apparatus.   6. The liquid ejecting apparatus according to claim 5, wherein all the actuators of the actuator block are substantially simultaneously driven by a common drive signal supplied from the drive signal supply means.   6. The liquid ejecting apparatus according to claim 5, wherein at least one actuator of the actuator block is driven by an individual drive signal supplied from the drive signal supply means. A liquid discharge method for a liquid discharge head comprising a nozzle, a pressure chamber communicating with the nozzle, and a pressure generating element that pressurizes the liquid in the pressure chamber,
A pressurizing step of pressurizing the liquid in the pressure chamber;
Three or more actuators having the same shape have an opening corresponding to the center of the nozzle opening between the actuators, and a slit-like gap from the opening toward the periphery, and cover the nozzle opening. A liquid droplet forming step of forming a liquid droplet of a desired volume by deforming the actuator and deforming the liquid discharged outside from the opening of the actuator block disposed on the liquid discharge side of
A liquid discharge method comprising:

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