JP2020049710A - Liquid ejection head, liquid ejection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an electric influence between piezoelectric elements in a liquid discharge head. SOLUTION: A plurality of liquid chambers provided with nozzles, a vibrating plate constituting one surface of the liquid chamber, and arranged at a position facing the liquid chamber via the vibrating plate, and a voltage is applied. The piezoelectric element is provided with a piezoelectric element that vibrates the vibrating plate and discharges the liquid stored in the liquid chamber from the nozzle, and the piezoelectric element is a laminated body in which a plurality of electrodes and piezoelectric bodies are alternately laminated. It is characterized by having an insulator on the laminated side surface of the laminated body. [Selection diagram] Fig. 1

Description

  The present invention relates to a liquid ejection head and a liquid ejection device.

  In recent years, as a substitute for a spray used for painting or coating, there has been an increasing demand for an ink jet type liquid ejecting apparatus which ejects liquid from a liquid ejecting head which ejects liquid (or droplets) to paper.

  In such a liquid discharging apparatus, liquid is discharged from a nozzle by displacement of a piezoelectric element such as a piezo element. 2. Description of the Related Art In a liquid ejecting apparatus used for a conventional image forming, an image forming output is performed by ejecting 1 to 100 pL of liquid from a nozzle at a time (for example, see Patent Document 1).

  On the other hand, when used for painting or coating, if a liquid having a higher viscosity than ink is ejected at a time of 10 to 100 nL at a time, the working efficiency will be reduced, and a large amount of liquid will be ejected at one time. For this purpose, it is necessary to increase the size of the piezoelectric element and apply a high voltage.

  However, in the conventional liquid ejection head disclosed in Patent Document 1, the piezoelectric element is exposed. The liquid ejection head includes a plurality of nozzles (ejection ports) for ejecting liquid, and the piezoelectric elements are arranged corresponding to the respective nozzles. Therefore, when a high voltage is applied to the bare piezoelectric element, the insulation between the piezoelectric elements is broken, causing a short circuit and a short circuit.

  The short-circuited piezoelectric element does not operate normally even when a voltage is applied, so that the liquid cannot be discharged. In a conventional liquid ejection head, it is necessary to increase the distance between the piezoelectric elements in order to prevent short-circuiting of the piezoelectric elements. It is manufactured in such a size that it is configured so that it is cut out so as to leave a space between adjacent piezoelectric elements. Therefore, in order to prevent the piezoelectric elements from being short-circuited, a large amount of dicing is required to increase the spacing between the piezoelectric elements.

  The present invention has been made to solve such a problem, and an object of the present invention is to reduce an electric influence between piezoelectric elements in a liquid ejection head.

  In order to solve the above-described problems, one embodiment of the present invention is directed to a plurality of liquid chambers provided with nozzles, a vibration plate that forms one surface of the liquid chamber, and the liquid chamber facing the liquid chamber via the vibration plate. A piezoelectric element that is disposed at a position, vibrates the diaphragm by applying a voltage, and discharges the liquid stored in the liquid chamber from the nozzle, and the piezoelectric element includes an electrode and a piezoelectric body. Are alternately laminated, and an insulator is provided on a side surface of the laminate.

  According to the present invention, it is possible to reduce the electric influence between the piezoelectric elements in the liquid ejection head.

FIG. 2 is a cross-sectional view of the liquid ejection head according to the embodiment of the present invention. FIG. 2 is a top plan view of the liquid ejection head according to the embodiment of the present invention. FIG. 1 is an explanatory diagram of a structure of a laminated piezo body according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of the laminated piezo body according to the embodiment of the present invention, taken along line BB ′. FIG. 9 is a diagram showing an arrangement of a laminated piezo body in a conventional liquid ejection head. The figure which shows arrangement | positioning of the laminated piezoelectric body which concerns on embodiment of this invention. FIG. 3 is a diagram illustrating an example of a cross section of the liquid ejection head according to the embodiment of the present invention. The figure explaining other examples of the structure of the lamination piezo body concerning the embodiment of the present invention. FIG. 5 is a cross-sectional view of the laminated piezo body according to the embodiment of the present invention, taken along line CC ′. The DD 'sectional view of the lamination | stacking piezoelectric body which concerns on embodiment of this invention. FIG. 1 is a schematic configuration diagram of a liquid ejection device according to an embodiment of the present invention. FIG. 2 is an array diagram of nozzles according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, an example will be described in which a liquid discharge head 1 discharges liquid from a nozzle and a liquid discharge apparatus 1000 including the liquid discharge head 1.

  FIG. 1 is a longitudinal sectional view of a liquid discharge head 1 according to the present embodiment, and FIG. 2 is a top plan view of the liquid discharge head 1. The liquid ejection head 1 includes a nozzle plate 10, a flow path plate 20, a vibration plate 30, a frame 40, a laminated piezo body 50, a piezo fixing plate 60, a common electrode wire 71, and an individual electrode wire 72. FIG. 1 is a diagram showing a cross section taken along line AA ′ of FIG.

  The nozzle plate 10 is provided with nozzles 10n at predetermined intervals (for example, at intervals of 5 to 20 nm). Note that the interval at which the nozzles 10n are provided may be determined based on the size of the pressure chamber 21 determined according to the target droplet size of the liquid and the viscosity of the liquid. Further, a configuration may be adopted in which the planar size of the liquid ejection head 1 is 200 mm × 50 mm, and about 10 to 30 nozzles 10 n are provided at equal intervals.

  As shown in FIG. 3, the laminated piezo body 50 is a piezoelectric element in which a plurality of common electrodes 51, piezoelectric elements 52, which are piezoelectric bodies, and individual electrodes 53 are laminated. The common electrode 51 is designed to have a length that does not contact the side surface individual electrode 55, and the individual electrode 53 is designed to have a length that does not contact the side surface common electrode 54. The laminated piezo body 50 is laminated so that the common electrodes 51 and the individual electrodes 53 are alternately sandwiched between the piezo elements 52, and the periphery thereof is covered with an insulating film 56 which is an insulator as shown in FIG. It is formed.

  Returning to FIG. 1, the description will be continued. In the liquid ejection head 1 according to the present embodiment, a pressure chamber 21 is formed by the nozzle plate 10, the flow path plate 20, the vibration plate 30, and the frame 40. Further, the laminated piezo body 50 is arranged in a gap formed by the diaphragm 30, the frame 40, and the piezo fixing plate 60. Therefore, the laminated piezo body 50 and the pressure chamber 21 are in a positional relationship facing each other with the diaphragm 30 interposed therebetween. The pressure chamber 21 is also called an individual liquid chamber.

  A predetermined voltage is applied to the laminated piezo body 50 from the individual electrode wires 72. The common electrode wires 71 and the individual electrode wires 72, which are electrode terminals, are fixed so as to be drawn out from openings 71a, 72a provided in the piezo fixing plate 60, respectively, and are connected to a drive circuit. Therefore, the direction in which the common electrode wire 71 and the individual electrode wire 72 are connected to the laminated piezo body 50 is a direction perpendicular to the arrangement direction of the nozzles 10n.

  When a voltage is applied, the laminated piezo body 50 expands or contracts according to the potential. One surface of the laminated piezo body 50 is in contact with the diaphragm 30 forming one surface of the pressure chamber 21. Therefore, when the laminated piezoelectric body 50 vibrates due to the application of the voltage, the diaphragm 30 also vibrates. When the diaphragm 30 is pushed down in the direction of the pressure chamber 21 with the expansion of the laminated piezo body 50, the volume of the pressure chamber 21 contracts.

  The pressure chamber 21 stores a liquid such as a paint, a coating agent, and ink. Therefore, the volume of the pressure chamber 21 is contracted by the vibration plate 30, and the pressure in the pressure chamber 21 is increased, so that the liquid stored in the pressure chamber 21 is discharged from the nozzle 10n.

  Here, an arrangement of the laminated piezo body 50 in the conventional liquid ejection head will be described with reference to FIG. FIG. 5 is a diagram exemplifying an arrangement of the laminated piezo bodies 50 (50a to 50e) in a conventional liquid ejection head.

  In the subordinate liquid ejection head, nozzles are arranged at intervals of 0.08 mm to 0.40 mm. Therefore, in order to form the laminated piezo bodies 50a, 50b, 50c, 50d, and 50e corresponding to the nozzle intervals, the large laminated piezo body 500 is diced by the dicer 200. Each electrode is exposed between the body 50e and the body 50e.

  Further, since the piezo element is an expensive member, it is not very desirable to cut off many piezo elements by dicing from the viewpoint of product cost. Further, in the conventional liquid ejection head, the applied voltage is small because the size of the ejected liquid droplet is small.

  However, the liquid discharge head 1 according to the present embodiment is configured to discharge 10 to 100 nL of liquid at one time. Therefore, in the liquid ejection head 1 according to the present embodiment, as shown in FIG. 6, a laminated structure in which a plurality of common electrodes 51, piezo elements 52, and individual electrodes 53 included in a separately formed laminated piezo body 50 are alternately laminated. The periphery of the side surface (laminated side surface) of the body is covered with an insulating film 56. This insulating film 56 can reduce the occurrence of electrode short-circuiting between a plurality of adjacent stacked piezo bodies 50.

  Further, in the laminated piezo body 50, by increasing the number of laminations, increasing the electric field strength, and adjusting the expansion displacement of the laminated piezo body 50 when a voltage is applied, 10 to 100 nL per time can be obtained. The liquid can be discharged. Further, since the contracted volume of the pressure chamber 21 can be increased, a high-viscosity liquid (for example, a liquid of 50 mPa · s or more) can be discharged.

  When the laminated piezo body 50 and the diaphragm 30 are adhered using an adhesive, the surface where the laminated piezo body 50 is joined to the diaphragm 30 may be polished to remove the insulating film 56 and adhered. In this way, the liquid discharge head 1 can be assembled with high accuracy, and therefore, the discharge direction and discharge amount of the liquid hardly vary.

  Further, as shown in FIG. 7, an island 90 which is a structure for increasing the vibration amount (displacement amount) of the diaphragm 30 may be provided below the laminated piezo body 50. By making the size of the island 90 larger than the planar projected area of the laminated piezo body 50, that is, the area of the laminated piezo body 50 in a portion that can come into contact with the diaphragm 30, the vibration amount of the diaphragm 30 can be increased. , The pressure chamber 21 can be more greatly deformed. As a material of the island 90, a resin or the like may be used.

  Further, in FIG. 3, the laminated piezo body 50 in which the common electrode 51 and the individual electrode 53 are laminated alternately so as to be interposed between the piezo elements 52 has been described. A configuration in which the piezo body 50 is mounted on the liquid ejection head 1 may be employed.

  In the laminated piezo body 50 shown in FIG. 8, the common electrode 51 and the individual electrode 53 are designed to have the same length as the piezo element 52, and the laminated piezo body 50 is configured such that the common electrode 51 and the individual electrode 53 are alternately piezo-electric. The layers are stacked so as to be sandwiched between the elements 52.

  As shown in FIG. 9, an electrode single-layer insulating film 57 is provided at an end of the common electrode 51 on the side surface individual electrode 55 side to prevent contact between the common electrode 51 and the side surface individual electrode 55. Can be. Further, as shown in FIG. 10, an electrode single-layer insulating film 57 is provided at an end of the individual electrode 53 on the side common electrode 54 side to prevent the contact between the individual electrode 53 and the side common electrode 54. Can be.

  Next, an example of a liquid ejection device 1000 to which the liquid ejection head 1 according to the embodiment is applied will be described. FIG. 11 and FIG. 12 are views showing the configuration of the liquid ejection device 1000 according to the present embodiment.

  In the liquid ejection device 1000, the carriage 33 is movably held by a main guide member 11 and a sub guide member which are laid on the left and right side plates. The carriage 33 reciprocates in the main scanning direction by the driving of the main scanning motor 58 via the timing belt 8 bridged between the driving pulley 66 and the driven pulley 67.

  The carriage 33 includes two liquid discharge heads 1 a and 1 b (hereinafter, simply referred to as “liquid discharge head 1” when there is no need to distinguish between the two liquid discharge heads) as the image forming unit, and a liquid discharge head 1 a. , 1b are provided with liquid chambers 57a and 57b for supplying liquid. The liquid discharge head 1 discharges, for example, yellow (Y), cyan (C), magenta (M), and black (K) inks.

  As shown in FIG. 12, the liquid ejection heads 1a and 1b have nozzle rows 4an1, 4an2, 4bn1, and 4bn2 in each of which a plurality of nozzles 10n are arranged. The nozzle rows 4an1, 4an2 are arranged in a staggered manner with their positions shifted in the nozzle arrangement direction. Note that the nozzle rows 4bn1 and 4bn2 have the same arrangement.

  The nozzle row 4an1 discharges black (K) liquid, and the nozzle row 4an2 discharges cyan (C) liquid. The nozzle row 4bn1 discharges magenta (M) liquid, and the nozzle row 4bn2 discharges yellow (Y) liquid.

  In addition, as the liquid discharge head 1, a plurality of nozzles are arranged on one nozzle surface and provided with a plurality of nozzle rows that discharge liquid of each color (for example, a liquid that discharges black liquid from each of the two nozzle rows). It is also possible to adopt a configuration using such as.

  The liquid chambers 57a and 57b are provided with a plurality of tank sections by forming two sets of tank sections corresponding to the two nozzle rows 4an1, 4an2, 4bn1 and 4bn2 of the liquid discharge heads 1a and 1b, respectively. Is done. Note that the liquid chambers 57a and 57b may be provided with tank portions for the number corresponding to the number of nozzle rows arranged in the liquid discharge heads 1a and 1b or for the type of liquid to be discharged.

  Liquids of each color are supplied to the liquid chambers 57a and 57b from a cartridge 55CD including main tanks 55K, 55C, 55M and 55Y containing liquids of the respective colors of CMYK. The cartridge 55CD is exchangeably attached to the cartridge holder 55HD.

  The cartridge holder 55HD is provided with a pump P for supplying a liquid from the cartridge 55CD to the liquid chambers 57a and 57b. A liquid of each color is drawn from the cartridge 55CD by the pump P, and a tube 560 provided for each color is provided. The liquids of the respective colors are supplied to the liquid chambers 57a and 57b via the.

  As the liquid ejection mechanism in the liquid ejection head 1, for example, a piezoelectric actuator such as a piezoelectric element, or a thermal actuator using a phase change due to liquid film boiling using an electrothermal conversion element such as a heating resistor is used. Can be.

  Further, the liquid ejection device 1000 includes a transport belt 12 as a transport mechanism M that transports the sheet material S so as to face the liquid ejection head 1. The transport belt 12 is an endless belt and is stretched between a transport roller 13 and a tension roller 14.

  In addition, the transport belt 12 is rotated in the sub-scanning direction by rotating the transport roller 13 via the timing belt 17 and the timing pulley 18 by driving the sub-scanning motor 16. The transport belt 12 is charged and charged by a known charging roller while moving around.

  Further, the transport mechanism M includes a transport region R that is disposed so as to face the sheet material S downstream of the region where the liquid is discharged from the liquid discharge head 1 in the traveling direction of the transport belt 12. The sheet material S is transported between the transport region R and the carriage 33, and an image is formed on the sheet material S by discharging liquid from the liquid discharge head 1 to the sheet material S.

  At one end of the carriage 33 in the main scanning direction, a maintenance / recovery mechanism 27 for maintaining and recovering the liquid ejection head 1 is arranged, and on the other side, an empty space for performing empty ejection from the liquid ejection head 1 beside the transport belt 12. The discharge receivers 28 are respectively arranged.

  The maintenance / recovery mechanism 27 includes, for example, a cap member for capping the nozzle surface (surface on which the nozzles are formed) of the liquid discharge head 1, a wiper member for wiping the nozzle surface, and a known empty discharge receiver for discharging liquid that does not contribute to image formation. It is composed of

  An encoder scale 23 having a predetermined pattern is mounted between both side plates along the main scanning direction of the carriage 33. Further, the carriage 33 includes an encoder sensor 24 that reads a pattern of the encoder scale 23. The encoder scale 23 and the encoder sensor 24 constitute a linear encoder (main scanning encoder) that detects the movement of the carriage 33.

  A code wheel 25 is attached to the shaft of the transport roller 13, and an encoder sensor 26 for detecting a pattern formed on the code wheel 25 is provided. The code wheel 25 and the encoder sensor 26 constitute a rotary encoder (sub-scanning encoder) that detects the moving amount and the moving position of the transport belt 12.

  With the configuration described above, the liquid ejection device 1000 according to the present embodiment transports the sheet material S in the sub-scanning direction by the orbital movement of the transport belt 12 in a state where the sheet material S is attracted to the charged transport belt 12. Is done.

  Then, while moving the carriage 33 in the main scanning direction, the liquid ejection head 1 is driven in accordance with a signal for forming an image, thereby ejecting the liquid to the stopped sheet material S, thereby forming one line. Record. Next, after the sheet material S is conveyed by a predetermined amount, recording of the next line is performed.

  Upon receiving a recording end signal or a signal indicating that the rear end of the sheet material S has reached the recording area, the recording operation is terminated, and the sheet material S is discharged to the discharge tray via the transport area R. Note that the conveyance of the sheet material S is not limited to the above-described conveyance belt method. The sheet material S is sucked by a plurality of suction ports, and the sheet material S is moved in the sub-scanning direction by driving a conveyance roller sandwiching the sheet material S. A transport system may be used.

  The present invention is not limited to the above-described embodiment, and can be changed in other embodiments, additions, modifications, deletions, and the like within a range that can be conceived by those skilled in the art. As long as the functions and effects of the present invention are exhibited, they are included in the scope of the present invention.

1: liquid ejection head 8: timing belt 10: nozzle plate 10n: nozzle 11: main guide member 12: transport belt 13: transport roller 14: tension roller 16: sub-scanning motor 17: timing belt 18: timing pulley 20: flow path Plate 21: Pressure chamber 23: Encoder scale 24: Encoder sensor 25: Code wheel 26: Encoder sensor 27: Maintenance / recovery mechanism 28: Empty discharge receiver 30: Diaphragm 33: Carriage 40: Frame 50: Laminated piezo body 51: Common electrode 52: Piezo element 53: Individual electrode 54: Side common electrode 55: Side individual electrode 55C: Main tank 56: Insulating film 57: Single electrode insulating film 58: Main scanning motor 60: Piezo fixed plate 71: Common electrode wire 71a: Opening 72: Individual electrode wire 72a: Opening 90: Island 200: Dicer 1000: Liquid ejection device

JP-A-11-58736

Claims (6)

A plurality of liquid chambers provided with nozzles,
A diaphragm constituting one surface of the liquid chamber,
A piezoelectric element disposed at a position facing the liquid chamber via the vibration plate, vibrating the vibration plate by applying a voltage, and discharging the liquid stored in the liquid chamber from the nozzle,
With
The liquid ejection head according to claim 1, wherein the piezoelectric element includes a stacked body in which a plurality of electrodes and piezoelectric bodies are alternately stacked, and an insulator is provided on a stacked side surface of the stacked body.   The liquid ejection head according to claim 1, wherein the vibration plate and the piezoelectric element are joined via an adhesive. The liquid ejection head according to claim 1, further comprising: a structure that deforms the liquid chamber between the vibration plate and the piezoelectric element.   The liquid ejection head according to claim 3, wherein the diaphragm is made of resin.   5. The liquid ejection device according to claim 1, wherein the piezoelectric element includes two electrode terminals connected in a direction perpendicular to an arrangement direction of the plurality of liquid chambers. 6. head.   A liquid ejection apparatus comprising the liquid ejection head according to claim 1.