JP2010076265A - Liquid discharge head and printer using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid discharge head which adjusts temperature of a liquid in a liquid pressurizing chamber. <P>SOLUTION: The liquid discharge head includes a flow path member 4 and a plurality of pressurizing means (displacing elements 50). The flow path member 4 includes: a plurality of liquid discharge holes 8 consisting of a plurality of stacked plates 22 to 31 including a heater plate 22 consisting of an electric resistor; a plurality of liquid pressurizing chambers 10 connected with the plurality of liquid discharge holes 8, respectively; and heater wiring 41 and 42 formed on the main surface of the heater plate 22. The plurality of pressurizing means pressurize the liquids in the plurality of liquid pressurizing chambers 10, respectively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a printing apparatus that prints an image by ejecting droplets, and more particularly to a printing apparatus that prints an image using a plurality of liquid ejection heads.

  In recent years, printing apparatuses using inkjet recording methods such as inkjet printers and inkjet plotters are not only printers for general consumers, but also, for example, formation of electronic circuits, manufacture of color filters for liquid crystal displays, manufacture of organic EL displays It is also widely used for industrial applications.

  In such an ink jet printing apparatus, a liquid discharge head for discharging liquid is mounted as a print head. This type of print head includes a heater as a pressurizing unit in an ink flow path filled with ink, heats and boiles the ink with the heater, pressurizes the ink with bubbles generated in the ink flow path, A thermal head system that ejects droplets from the ink ejection holes, and a part of the walls of the ink flow path filled with ink is bent and displaced by a pressurizing means, and the ink in the ink flow path is mechanically pressurized, A piezoelectric method in which ink is ejected as droplets from ink ejection holes is generally known.

  In addition, in such a liquid discharge head, recording is performed with respect to a serial type in which recording is performed while moving the liquid discharge head in a direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) of the recording medium, and the main scanning direction. There is a line type in which recording is performed on a recording medium conveyed in the sub-scanning direction with a head longer than the medium fixed. The line type has the advantage that high-speed recording is possible because there is no need to move the liquid discharge head as in the serial type.

  In order to print droplets at a high density in any of the serial type and line type liquid discharge heads, the density of the liquid discharge holes for discharging the droplets formed in the liquid discharge head must be increased. There is a need to.

  Accordingly, the liquid discharge head is connected to the manifold and the flow path member having the liquid discharge holes connecting the manifold via the plurality of liquid pressurization chambers, and the plurality of pressurization means provided so as to cover the liquid pressurization chambers, respectively. There is known a technique in which an actuator unit having a structure is laminated (see, for example, Patent Document 1). In the liquid discharge head, the liquid pressurizing chamber connected to each liquid discharge hole is displaced by a pressurizing unit provided so as to cover the liquid pressurization chamber, thereby discharging ink from each liquid discharge hole and 600 dpi in the main scanning direction. It is possible to print at a resolution of.

Also known is a liquid discharge head that is provided with a heater outside the flow path member to keep the temperature of the flow path member constant in order to stabilize the discharge characteristics of the liquid droplets discharged from the liquid discharge holes. ing.
JP 2003-305852 A

  However, the temperature adjustment is most required for the liquid in the liquid pressurizing chamber where the discharge characteristics may vary depending on the temperature. Therefore, even if the heater is provided outside the flow path member, the heater is liquid pressurized. Since it is away from the room, there is a problem that a time difference occurs until the temperature of the liquid in the liquid pressurizing room rises after the temperature of the heater rises, resulting in poor response.

  Accordingly, an object of the present invention is to provide a liquid discharge head capable of adjusting the temperature of the liquid in the liquid pressurizing chamber.

  The liquid discharge head according to the present invention includes a plurality of liquid discharge holes formed by laminating a plurality of plates including a heater plate made of an electric resistor, and a plurality of liquid pressurizing chambers respectively connected to the plurality of liquid discharge holes. A flow path member including heater wiring formed on a main surface of the heater plate, and a plurality of pressurizing units that pressurize the liquid in the plurality of liquid pressurizing chambers, respectively.

  Moreover, it is preferable that the plate constituting the wall surfaces of the plurality of liquid pressurizing chambers is the heater plate, and the heater wiring is formed in the vicinity of the liquid pressurizing chamber.

  Furthermore, it is preferable that the plurality of liquid pressurizing chambers are opened on one main surface of the flow path member, and the plate constituting the one main surface is the heater plate.

  Furthermore, it is preferable that the heater wiring is formed opposite to each other on both main surfaces of the heater plate.

  Furthermore, when the flow path member is viewed in plan from the stacking direction, the flow path member includes a liquid pressurization chamber forming region in which the plurality of liquid pressurization chambers are arranged in a matrix and other than the liquid pressurization chamber forming region. It is preferable that the heater wiring has the same pattern in the liquid pressurization chamber formation region and the liquid pressurization chamber formation region.

  The printing apparatus of the present invention includes the liquid discharge head, a transport unit that transports a recording medium to the liquid discharge head, and a control unit that controls the drive of the liquid discharge head and the temperature of the heater plate. It is characterized by.

  A plurality of liquid discharge holes, a plurality of liquid pressurizing chambers connected to the plurality of liquid discharge holes, and a main surface of the heater plate are formed by laminating a plurality of plates including a heater plate made of an electric resistor. Near the liquid pressurizing chamber in the flow path member by providing a flow path member including the heater wiring that is provided, and a plurality of pressurizing means that pressurize the liquid in the plurality of liquid pressurizing chambers, respectively. Since the liquid in the liquid pressurizing chamber can be heated by the heater, the temperature can be adjusted more finely.

  In addition, when the plate constituting the wall surfaces of the plurality of liquid pressurizing chambers is the heater plate and the heater wiring is formed in the vicinity of the liquid pressurizing chamber, the liquid in the liquid pressurizing chamber Can be directly heated, so that the temperature can be adjusted more finely.

  Further, when the plurality of liquid pressurizing chambers are opened on one main surface of the flow path member, and the plate constituting the one main surface is the heater plate, the heater wiring and the heater generate heat. Electrical connection with the control unit to be controlled can be facilitated.

  Furthermore, when the heater wiring is formed on both main surfaces of the heater plate so as to face each other, the position of the heater that generates heat can be easily adjusted.

  Furthermore, when the flow path member is viewed in plan from the stacking direction, the flow path member includes a liquid pressurization chamber forming region in which the plurality of liquid pressurization chambers are arranged in a matrix and other than the liquid pressurization chamber forming region. When the heater wire has the same pattern in the liquid pressurization chamber formation region and the liquid pressurization chamber formation region, all the heater wires If electricity is supplied at a constant voltage difference, the calorific value per unit area of the liquid pressurization chamber forming region and the calorific value per unit area of the liquid pressurization chamber forming region are almost the same. Easy to adjust temperature.

  According to the printing apparatus of the present invention, the liquid discharge head, a transport unit that transports the recording medium to the liquid discharge head, and a control unit that controls the driving of the liquid discharge head and the temperature of the heater plate are provided. By providing, it is possible to perform printing with less printing variation caused by the temperature difference of the liquid in the flow path member.

  FIG. 1 is a schematic configuration diagram of a color ink jet printer which is a printing apparatus of the present invention including a liquid discharge head according to an embodiment of the present invention. This color inkjet printer 1 (hereinafter referred to as printer 1) has four liquid ejection heads 2. These liquid ejection heads 2 are arranged along the transport direction of the printing paper P that is a recording medium, and are fixed in the printer 1. The liquid discharge head 2 has an elongated shape in a direction from the front side to the back side in FIG.

  The printer 1 includes a transport unit that moves the printing paper P, which is a recording medium, relative to the liquid ejection head 2. Specifically, a paper feed unit 114, a transport unit 120, and a paper receiver 116 are sequentially provided along the transport path of the printing paper P. In addition, the printer 1 is provided with a control unit 100 for controlling the operation of each unit of the printer 1 such as the liquid discharge head 2 and the paper feeding unit 114.

  The paper supply unit 114 includes a paper storage case 115 that can store a plurality of printing papers P, and a paper supply roller 145. The paper feed roller 145 can send out the uppermost print paper P among the print papers P stacked and stored in the paper storage case 115 one by one.

  Between the paper feed unit 114 and the transport unit 120, two pairs of feed rollers 118a and 118b and 119a and 119b are arranged along the transport path of the printing paper P. The printing paper P sent out from the paper supply unit 114 is guided by these feed rollers 118, 118 a, 119, and 119 a and further sent out to the transport unit 120.

  The transport unit 120 includes an endless transport belt 111 and two belt rollers 106 and 107. The conveyor belt 111 is wound around belt rollers 106 and 107. The conveyor belt 111 is adjusted to such a length that it is stretched with a predetermined tension when it is wound around two belt rollers. Thus, the conveyor belt 111 is stretched without slack along two parallel planes each including a common tangent line of the two belt rollers. Of these two planes, the plane closer to the liquid ejection head 2 is a transport surface 127 that transports the printing paper P.

  As shown in FIG. 1, a conveyance motor 174 is connected to the belt roller 106. The transport motor 174 can rotate the belt roller 106 in the direction of arrow A. The belt roller 107 can rotate in conjunction with the transport belt 111. Therefore, the conveyance belt 111 moves along the direction of arrow A by driving the conveyance motor 174 and rotating the belt roller 106.

  In the vicinity of the belt roller 107, a nip roller 138 and a nip receiving roller 139 are arranged so as to sandwich the conveyance belt 111. The nip roller 138 is urged downward by a spring (not shown). A nip receiving roller 139 below the nip roller 138 receives the nip roller 138 biased downward via the conveying belt 111. The two nip rollers 138 and 139 are rotatably installed and rotate in conjunction with the transport belt 111.

  The printing paper P sent out from the paper supply unit 114 to the transport unit 120 is sandwiched between the nip roller 138 and the transport belt 111. As a result, the printing paper P is pressed against the transport surface 127 of the transport belt 111 and is fixed on the transport surface 127. The printing paper P is transported in the direction in which the liquid ejection head 2 is installed according to the rotation of the transport belt 111. The outer peripheral surface 113 of the conveyor belt 111 may be treated with adhesive silicon rubber. Thereby, the printing paper P can be securely fixed to the transport surface 127.

  The four liquid discharge heads 2 are arranged close to each other along the conveyance direction by the conveyance belt 111. Each liquid discharge head 2 has a head body 13 at the lower end. A number of liquid ejection holes 8 for ejecting liquid are provided on the lower surface of the head body 13 (see FIGS. 3 and 4).

  The liquid (ink) of the same color is ejected from the liquid ejection holes 8 provided in one liquid ejection head 2. The colors of the liquid ejected from each liquid ejection head 2 are magenta (M), yellow (Y), cyan (C), and black (K), respectively. Each liquid ejection head 2 is disposed with a slight gap between the lower surface of the head body 13 and the transport surface 127 of the transport belt 111.

  The printing paper P transported by the transport belt 111 passes through the gap between the liquid ejection head 2 and the transport belt 111. At that time, liquid is discharged from the head main body 13 constituting the liquid discharge head 2 toward the upper surface of the printing paper P. As a result, a color image based on the image data stored by the control unit 100 is formed on the upper surface of the printing paper P.

A separation plate 140 and two pairs of feed rollers 121a and 121b and 122a and 122b are arranged between the transport unit 120 and the paper receiver 116.
The printing paper P on which the color image is printed is conveyed to the peeling plate 140 by the conveying belt 111. At this time, the printing paper P is peeled from the transport surface 127 by the right end of the peeling plate 140. Then, the printing paper P is sent to the paper receiving unit 116 by the feed rollers 121a to 122b. In this way, the printed printing paper P is sequentially sent to the paper receiving unit 116 and stacked on the paper receiving unit 116.

  Note that a paper surface sensor 133 is installed between the liquid ejection head 2 and the nip roller 138 that are the most upstream in the transport direction of the printing paper P. The paper surface sensor 133 includes a light emitting element and a light receiving element, and can detect the leading end position of the printing paper P on the transport path. The detection result by the paper surface sensor 133 is sent to the control unit 100. The control unit 100 can control the liquid ejection head 2, the conveyance motor 174, and the like so that the conveyance of the printing paper P and the printing of the image are synchronized based on the detection result sent from the paper surface sensor 133.

  Next, the head main body 13 constituting the liquid discharge head of the present invention will be described. FIG. 2 is a plan view showing the head main body 13 shown in FIG. FIG. 3 is an enlarged plan view of a region surrounded by a one-dot chain line in FIG. 2 and is a part of the head main body 13. For convenience of explanation, the piezoelectric actuator unit 21 is shown by a two-dot chain line in FIG. In addition, the squeezing 12 and the liquid discharge holes 8 that are originally formed in the flow path member 4 and on the lower surface, which should be indicated by broken lines, are indicated by solid lines. 4A is a longitudinal sectional view taken along line IV-IV in FIG. 3, and FIG. 4B is an enlarged view of a part of FIG. FIG. 5A is a plan view of the heater plate 22. FIG. 5B is a plan view of the heater plate 22 in the same place as FIG. 5A, and the pattern heater wiring 42 is omitted and the ground heater wiring 41 is seen through.

  The head body 13 includes a flat plate-like flow path member 4 and a piezoelectric actuator unit 21 stacked on the flow path member 4. The piezoelectric actuator unit 21 includes a plurality of later-described displacement elements 50 that are pressurizing means. The piezoelectric actuator unit 21 has a trapezoidal shape, and is disposed on the upper surface of the flow path member 4 so that a pair of parallel opposing sides of the trapezoid is parallel to the longitudinal direction of the flow path member 4. Further, two piezoelectric actuator units 21 are arranged on the flow path member 4 as a whole in a zigzag manner, two along each of two virtual straight lines parallel to the longitudinal direction of the flow path member 4. Yes. The oblique sides of the piezoelectric actuator units 21 adjacent on the flow path member 4 partially overlap in the width direction of the flow path member 4.

  A manifold 5 that is a part of the liquid flow path is formed inside the flow path member 4. The manifold 5 has an elongated shape extending along the longitudinal direction of the flow path member 4, and an opening 5 b of the manifold 5 is formed on the upper surface of the flow path member 4. A total of ten openings 5 b are formed along each of two straight lines (imaginary lines) parallel to the longitudinal direction of the flow path member 4. The opening 5b is formed at a position that avoids a region where the four piezoelectric actuator units 21 are disposed. The manifold 5 is supplied with liquid from a liquid tank (not shown) through the opening 5b.

  The manifold 5 formed in the flow path member 4 is branched into a plurality of branches (the manifold 5 at the branched portion may be referred to as a sub-manifold 5a). The manifold 5 connected to the opening 5 b extends along the oblique side of the piezoelectric actuator unit 21 and is disposed so as to intersect with the longitudinal direction of the flow path member 4. In a region sandwiched between two piezoelectric actuator units 21, one manifold 5 is shared by adjacent piezoelectric actuator units 21, and the sub-manifold 5 a branches off from both sides of the manifold 5. These sub-manifolds 5 a extend in the longitudinal direction of the head body 13 adjacent to each other in regions facing the respective piezoelectric actuator units 21 inside the flow path member 4.

  The flow path member 4 has four liquid pressurizing chamber groups 9 in which a plurality of liquid pressurizing chambers 10 are formed in a matrix (that is, two-dimensionally and regularly). The inside of each liquid pressurizing chamber group 9 inside the outermost liquid pressurizing chamber 10 is a liquid pressurizing chamber forming region 15 in which the liquid pressurizing chamber 10 is formed. The area other than the liquid pressurizing chamber forming area 15 is an area 16 outside the liquid pressurizing chamber forming area. The liquid pressurizing chamber 10 is a hollow region having a substantially rhombic planar shape with rounded corners. The liquid pressurizing chamber 10 is formed so as to open on the upper surface of the flow path member 4. These liquid pressurizing chambers 10 are arranged over substantially the entire surface of the upper surface of the flow path member 4 facing the piezoelectric actuator unit 21. Accordingly, each liquid pressurizing chamber group 9 formed by these liquid pressurizing chambers 10 occupies a region having almost the same size and shape as the piezoelectric actuator unit 21. Further, the opening of each liquid pressurizing chamber 10 is closed by adhering the piezoelectric actuator unit 21 to the upper surface of the flow path member 4.

  In the present embodiment, as shown in FIG. 3, the manifold 5 branches into four rows of sub-manifolds 5a arranged in parallel to each other in the short direction of the flow path member 4, and is connected to each sub-manifold 5a. The liquid pressurizing chambers 10 form a row of the liquid pressurizing chambers 10 arranged at equal intervals in the longitudinal direction of the flow path member 4, and the four rows are arranged in parallel to each other in the short side direction. Two rows of liquid pressurizing chambers 10 connected to the sub-manifold 5a are arranged on both sides of the sub-manifold 5a.

  As a whole, the liquid pressurizing chambers 10 connected from the manifold 5 constitute rows of the liquid pressurizing chambers 10 arranged in the longitudinal direction of the flow path member 4 at equal intervals, and the rows are 16 rows parallel to each other in the short direction. It is arranged. The number of liquid pressurizing chambers 10 included in each liquid pressurizing chamber row is arranged so as to gradually decrease from the long side toward the short side corresponding to the outer shape of the piezoelectric actuator unit 21. . The liquid discharge holes 8 are also arranged in the same manner. As a result, it is possible to form an image with a resolution of 600 dpi in the longitudinal direction as a whole. That is, the individual flow paths 32 are connected to each sub-manifold 5a at intervals corresponding to 150 dpi on average. This is because the individual flow paths 32 connected to each sub-manifold 5a are not necessarily connected at equal intervals when the 600 dpi liquid discharge holes 8 are divided and connected to the four sub-manifolds 5a. That is, the individual flow paths 32 are formed at intervals of an average of 170 μm (25.4 mm / 150 = 169 μm if 150 dpi) in the extending direction of 5a, that is, the main scanning direction.

  Individual electrodes 35 to be described later are formed at positions facing the liquid pressurizing chambers 10 on the upper surface of the piezoelectric actuator unit 21. The individual electrode 35 is slightly smaller than the liquid pressurizing chamber 10, has a shape substantially similar to the liquid pressurizing chamber 10, and fits in a region facing the liquid pressurizing chamber 10 on the upper surface of the piezoelectric actuator unit 21. Is arranged.

  A large number of liquid discharge holes 8 are formed in the liquid discharge surface on the lower surface of the flow path member 4. These liquid discharge holes 8 are arranged at a position avoiding a region facing the sub-manifold 5 a arranged on the lower surface side of the flow path member 4. Further, these liquid discharge holes 8 are arranged in a region facing the piezoelectric actuator unit 21 on the lower surface side of the flow path member 4 and constitute a group of four liquid discharge holes. These liquid discharge hole groups occupy an area having almost the same size and shape as the piezoelectric actuator unit 21, and by displacing the displacement element 50 of the corresponding piezoelectric actuator unit 21, a droplet is discharged from the liquid discharge hole 8. Can be discharged. The liquid discharge holes 8 in each region are arranged at equal intervals along a plurality of straight lines parallel to the longitudinal direction of the flow path member 4.

  These liquid discharge holes 8 are projected on the virtual straight line parallel to the longitudinal direction of the flow path member 4 by projecting the projected positions of the liquid discharge holes 8 from the direction perpendicular to the virtual straight line. They are formed at positions that are arranged at regular intervals at intervals corresponding to the resolution. As a result, the liquid ejection head 2 can print without interruption at intervals corresponding to the printing resolution over almost the entire area in the longitudinal direction of the area where the liquid ejection holes 8 are formed in the flow path member 4. Yes.

  A large number of apertures 12 are formed inside the flow path member 4. These throttles 12 are arranged in a region facing the liquid pressurizing chamber group 9. The aperture 12 of the present embodiment extends along one direction parallel to the horizontal plane. One end of the squeezing 12 is connected to the sub-manifold 5a via the individual supply channel 6 described later. Further, the other end of the squeezing 12 is connected to the liquid pressurizing chamber 10.

  The flow path member 4 included in the head body 13 has a stacked structure in which a plurality of plates are stacked. These plates are a cavity plate 22, a base plate 23, an aperture (squeezing) plate 24, supply plates 25 and 26, manifold plates 27, 28 and 29, a cover plate 30 and a nozzle plate 31 in order from the upper surface of the flow path member 4. is there. Although details will be described later, at least one of these plates is made of an electric resistor and used as a heater plate that generates heat. Moreover, many holes are formed in each plate 22-31. The plates 22 to 31 are stacked in alignment so that these holes communicate with each other to form the manifold 5 and the individual flow path 32. As shown in FIG. 4, in the head main body 13, the liquid pressurizing chamber 10 is on the upper surface of the flow path member 4, the sub-manifold 5a is on the inner lower surface side, and the liquid discharge holes 8 are on the lower surface. Each portion constituting the path 32 is disposed close to each other at different positions, and the sub manifold 5 a and the liquid discharge hole 8 are connected via the liquid pressurizing chamber 10.

  The hole formed in each plate 22-31 is demonstrated. These holes include the following. First, the liquid pressurizing chamber 10 formed in the cavity plate 22. Second, there is a communication hole that forms a flow path that connects from one end of the liquid pressurizing chamber 10 to the sub-manifold 5a. This communication hole is formed in each plate from the base plate 23 (specifically, the inlet of the liquid pressurizing chamber 10) to the supply plate 25 (specifically, the outlet of the sub manifold 5a). The communication hole includes the aperture 12 formed in the aperture plate 24 and the individual supply flow path 6 formed in the supply plates 25 and 26.

  Third, there is a communication hole that constitutes a flow channel that communicates from the other end of the liquid pressurizing chamber 10 to the liquid discharge hole 8, and this communication hole is referred to as a descender (partial flow channel) in the following description. . The descender is formed on each plate from the base plate 23 (specifically, the outlet of the liquid pressurizing chamber 10) to the nozzle plate 31 (specifically, the liquid discharge hole 8). Fourthly, there is a communication hole constituting the sub-manifold 5a. The communication holes are formed in the manifold plates 27 to 29.

  Such communication holes are connected to each other to form an individual flow path 32 from the liquid inflow port (the outlet of the submanifold 5a) from the submanifold 5a to the liquid discharge hole 8. The liquid supplied to the sub manifold 5a is discharged from the liquid discharge hole 8 through the following path. First, from the sub-manifold 5a, it passes through the individual supply flow path 6 and reaches one end of the throttle 12. Next, it proceeds horizontally along the extending direction of the aperture 12 and reaches the other end of the aperture 12. From there, it reaches one end of the liquid pressurizing chamber 10 upward. Further, the liquid pressurizing chamber 10 proceeds horizontally along the extending direction of the liquid pressurizing chamber 10 and reaches the other end of the liquid pressurizing chamber 10. While moving little by little in the horizontal direction from there, it proceeds mainly downward and proceeds to the liquid discharge hole 8 opened on the lower surface.

  By attaching a displacement element 50 to be described later to the liquid pressurizing chamber 10 of the flow path member 4 and deforming the displacement element 50, it is possible to eject droplets from the liquid ejection holes 8. At this time, if the temperature of the liquid in the liquid pressurizing chamber 10 fluctuates, the viscosity of the liquid changes. Therefore, even if the deformation of the displacement element 50 is the same, the speed and amount of the ejected droplets fluctuate, and printing is performed. Since the position of landing on the paper P and the area of the liquid that spreads after landing change, the accuracy of the printed image and the like may be deteriorated.

  At least one of the plates 22 to 31 is made of an electric resistor having a high conductor resistance to form a heater plate. Heat can be generated by forming a heater wiring on the main surface of the heater plate and flowing electricity. In this case, heat is generated near the liquid in the liquid pressurizing chamber 10 that most affects the ejection characteristics. Therefore, the time until the temperature of the liquid in the liquid pressurizing chamber 10 rises after the heat is generated. Shorter and finer temperature control.

  The heater wiring may form a heater wiring capable of voltage difference in one main surface of the heater plate, and a current may flow in a direction perpendicular to the stacking direction. A voltage difference between one main surface and the other main surface of the heater plate may be applied. A heater wiring that can be formed may be formed, and a current may flow in the stacking direction. The former is preferable because the heater wiring can be formed only on one main surface and the manufacturing process can be simplified. The latter is preferable because the portion that generates heat and the amount of heat generated can be easily controlled by the pattern to be formed. Whichever type of heater wiring is formed, the heater wiring is preferably provided in the vicinity of the liquid pressurizing chamber 10. Here, the vicinity of the liquid pressurizing chamber 10 may be any position in the flow path member 4 in the stacking direction, and is closest to one liquid pressurizing chamber 10 in the direction perpendicular to the stacking direction. This is a position closer to the liquid pressurizing chamber 10.

  Any of the plates 22 to 31 may be a heater plate, but the plate constituting the wall surface of the liquid pressurizing chamber 10 so that heat can be generated near the liquid pressurizing chamber 10. That is, at least one of the cavity plate 22 and the base plate 23 is preferably a heater plate. In addition, it is preferable to use the cavity plate 22 as a heater plate because the heater plate can be formed almost uniformly on the entire flow path member 4 because the cavity plate 22 has few holes other than the liquid pressurizing chamber 10. Furthermore, when the plate forming the main surface on which the displacement elements 50 of the flow path member 4 are stacked is a heater plate and the heater wiring is formed on the main surface, the electrical connection between the heater wiring and the control unit 100 is facilitated. be able to.

  5A and 5B, the cavity plate 22 is used as a heater plate, and as a heater wiring, a ground heater wiring 41 is formed on one main surface of the cavity plate 22, and a pattern heater wiring 42 is formed on the other main surface. In addition, the ground heater wiring 41 and the pattern heater wiring 42 have opposing portions facing each other. A voltage is applied between the ground heater wiring 41 and the pattern heater wiring 42 by the control unit 100, and current flows in the stacking direction at the facing portion, and the heater plate in the portion where the current flows generates heat. In such a configuration, heat is generated only in the facing portion where the heater wiring is formed almost vertically, and the amount of heat generation is proportional to the area of the facing portion. The calorific value can be easily adjusted. In addition, heater wires having a potential difference in the same plane need not be provided close to each other, so that the heater wires are not short-circuited by liquid.

  If it is desired to form wiring through the heater plate, a through hole is formed in the heater plate and a conductor is inserted into the through hole. In this case, the through hole is preferably formed (1 mm or more) sufficiently separated from the liquid pressurizing chamber 10, the end of the flow path member 4, and the pattern having a potential difference.

  The ground heater wiring 41 is formed on substantially the entire surface of the cavity plate 22 as shown in FIG. The reason why the ground heater wiring 41 is not formed around the liquid pressurizing chamber 10 is that the ground heater wiring 41 is not corroded by the liquid.

  Similar to the ground heater wiring 41, the pattern heater wiring 42 is provided with a portion that is not formed around the liquid pressurizing chamber 10. That is, in the liquid pressurizing chamber forming region 15 where the liquid pressurizing chamber 10 is formed as one lump, a heater wiring non-forming portion similar to the liquid pressurizing chamber is provided. Further, a heater wiring non-forming portion may be provided also in the liquid pressurization chamber forming region outside region 16 where the liquid pressurization chamber 10 is not formed. By doing in this way, since the whole flow path member 4 is heated on average, it is preferable. At this time, the heater wiring non-forming portion in the liquid pressurization chamber forming region outside region 16 is also designed easily if the heater wiring non-forming portion in the liquid pressurizing chamber forming region 15 has the same shape and arrangement interval. Further, the heater wiring non-forming portion in the liquid pressurization chamber forming region outside region 16 may be similar and slightly larger than the heater wiring non-forming portion in the liquid pressurizing chamber forming region 15. In this case, since the liquid is continuously supplied, the heat generation in the region 16 outside the liquid pressurization chamber forming region 16 is less than that in the region 15 where the liquid pressurization chamber forming region needs to be heated, and the entire balance is achieved.

  Next, an application example in which the pattern heater wiring 42 is formed by dividing it into several regions will be described. The structure other than how the pattern heater wiring 42 is formed is the same as described above.

  FIG. 6A is a plan view of the flow path member 4-1, and the pattern heater wiring 42 is formed in the pattern heater wiring area 42-1 so as to include the liquid pressurizing chamber forming area 15-1. Although details of the pattern heater wiring 42 are omitted in the figure, a heater wiring non-forming portion similar in shape to the liquid pressurizing chamber 10 is provided on the whole as in FIG. That is, the same pattern heater wiring as that in the liquid pressurizing chamber forming region 15-1 is formed in the region outside the liquid pressurizing chamber forming region. Although not shown, the ground heater wiring 41 is formed in the same manner as in FIG. 5B, and the ground heater wiring electrode 43-1 electrically connected to the ground heater wiring 41 by the conductor of the through hole is provided. Is formed. The pattern heater wirings in the pattern heater wiring region 42-1 are all connected, and a voltage is applied between the control unit 100 and the ground heater wiring 41, and the pattern heater wiring region 42-1 is almost uniform. Fever.

  FIG. 6B is a plan view of the flow path member 4-2, and the pattern heater wiring 42 is formed in the pattern heater wiring area 42-2 so as to include the liquid pressurizing chamber forming area 15-2. Although details of the pattern heater wiring 42 are omitted in the figure, a heater wiring non-forming portion similar in shape to the liquid pressurizing chamber 10 is provided on the whole as in FIG. That is, the same pattern heater wiring as that of the liquid pressurizing chamber forming region 15-2 is also formed in the region outside the liquid pressurizing chamber forming region. Although not shown, the ground heater wiring 41 is formed in the same manner as in FIG. 5B, and the ground heater wiring electrode 43-2 electrically connected to the ground heater wiring 41 by the conductor of the through hole is provided. Is formed.

  The pattern heater wiring 42 is formed by being divided into four pattern heater wiring areas 42-2a to 4d each including a liquid pressurizing chamber forming area 15-2 corresponding to the piezoelectric actuator unit 21. That is, the pattern heater wirings 42 formed in the pattern heater wiring regions 42-2a to 42-2d are not connected to each other, and the amount of heat generated in each region can be changed by changing the amount of current flowing through the pattern heater wiring in each region. it can. If a temperature sensor is attached to each region, the temperature can be adjusted according to the state of each region. In addition, when there is a difference in the characteristics of each piezoelectric actuator unit 21, it is possible to adjust the temperature setting for each region so as to cancel the difference in the characteristics of the piezoelectric actuator unit 21. For example, when the average displacement amount of the displacement element 50 included in a certain piezoelectric actuator 21 is lower than the average displacement amount of the displacement elements 50 included in the other piezoelectric actuators 21, the temperature of the region corresponding to the piezoelectric actuator 21 is increased. By lowering the viscosity of the liquid, the amount of liquid droplets is increased and the speed of the liquid droplets is increased even with a small amount of displacement, so that variations in liquid ejection characteristics can be reduced.

  FIG. 6C is a plan view of the flow path member 4-3, and the pattern heater wiring is formed in the pattern heater wiring region 42-3 so as to include the liquid pressurizing chamber forming region 15-3. Although details of the pattern heater wiring are omitted in the figure, a heater wiring non-forming portion similar in shape to the liquid pressurizing chamber 10 is provided on the whole as in 5 (a). That is, the same pattern heater wiring as the liquid pressurizing chamber forming region 15-3 is formed also in the region outside the liquid pressurizing chamber forming region. Although not shown, the ground heater wiring 41 is formed in the same manner as in FIG. 5B, and the ground heater wiring electrode 43-3 electrically connected to the ground heater wiring 41 by the conductor of the through hole is provided. Is formed.

  The pattern heater wiring is divided into four pattern heater wiring areas 42-3a to 42d along the sub-manifold 5a. That is, the pattern heater wirings formed in the pattern heater wiring regions 42-3a to 42-3d are not connected to each other, and the amount of heat generated in each region can be changed by changing the amount of current flowing through the pattern heater wiring formed in each. it can. If a temperature sensor is attached to each region, the temperature can be adjusted according to the state of each region.

  6B and 6C, the pattern heater wiring 42 is divided into 16 pattern heater wiring areas for each sub-manifold 5a in the area corresponding to the piezoelectric actuator unit 21. It may be formed. By doing in this way, it can divide and adjust to a finer area | region. Further, in such a liquid discharge head 2, when the flow path member 4 and the piezoelectric actuator unit 21 are joined with a thermosetting resin, a compression pressure is applied to the piezoelectric actuator 21 due to a difference in thermal expansion coefficient, thereby causing the piezoelectric actuator unit 21. The displacement element 50 on the short side of the trapezoid may have a larger displacement than the displacement element 50 on the long side. In such a case, the displacement is applied to the region on the short side of the trapezoid of the piezoelectric actuator unit 21. By reducing the amount of current and increasing the viscosity of the liquid flowing in the sub-manifold 5a corresponding to the displacement element 50, it is possible to reduce variations in ejection characteristics.

  Furthermore, the pattern heater wiring 42 in the region above the manifold 5 before branching to the sub-manifold 5a near the opening 5b may be separately formed and temperature controlled separately. Since a liquid having a temperature difference from the flow path member 4 may enter from the opening 5b and the temperature fluctuation may increase, this is preferable because this fluctuation can be reduced.

  Next, the piezoelectric actuator unit 21 will be described. As shown in FIG. 4, the piezoelectric actuator unit 21 has a laminated structure including two piezoelectric ceramic layers 21a and 21b. Each of these piezoelectric ceramic layers 21a and 21b has a thickness of about 20 μm. The total thickness of the piezoelectric actuator unit 21 is about 40 μm. Each of the piezoelectric ceramic layers 21a and 21b extends so as to straddle the plurality of liquid pressurizing chambers 10 (see FIG. 3). The piezoelectric ceramic layers 21a and 21b are made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  The piezoelectric actuator unit 21 includes a common electrode 34 made of a metal material such as Ag—Pd and an individual electrode 35 made of a metal material such as Au. As described above, the individual electrode 35 is disposed at a position facing the liquid pressurizing chamber 10 on the upper surface of the piezoelectric actuator unit 21. One end of the individual electrode 35 is drawn out of a region facing the liquid pressurizing chamber 10 to form a connection electrode 36. The connection electrode 36 is made of, for example, gold containing glass frit, and has a convex shape with a thickness of about 15 μm. The connection electrode 36 is electrically joined to an electrode provided in an FPC (Flexible Printed Circuit) (not shown). Although details will be described later, an ejection signal is supplied to the individual electrode 35 from the control unit 100 through the FPC.

  The common electrode 34 is formed over substantially the entire surface in the region between the piezoelectric ceramic layer 21a and the piezoelectric ceramic layer 21b. That is, the common electrode 34 extends so as to cover all the liquid pressurizing chambers 10 in the region facing the piezoelectric actuator unit 21. The thickness of the common electrode 34 is about 2 μm. The common electrode 34 is grounded in a region not shown, and is held at the ground potential. In the present embodiment, a surface electrode (not shown) different from the individual electrode 35 is formed on the piezoelectric ceramic layer 21b at a position avoiding the electrode group composed of the individual electrodes 35. The surface electrode is electrically connected to the common electrode 34 through a through-hole formed in the piezoelectric ceramic layer 21b, and is connected to another electrode on the FPC in the same manner as many individual electrodes 35. ing.

  As shown in FIG. 4, the common electrode 34 and the individual electrode 35 are arranged so as to sandwich only the uppermost piezoelectric ceramic layer 21b. A region sandwiched between the individual electrode 35 and the common electrode 34 in the piezoelectric ceramic layer 21b is referred to as an active portion, and the piezoelectric ceramic in that portion is polarized. In the piezoelectric actuator unit 21 of the present embodiment, only the uppermost piezoelectric ceramic layer 21b includes an active portion, and the piezoelectric ceramic 21a does not include an active portion and functions as a diaphragm. The piezoelectric actuator unit 21 has a so-called unimorph type configuration.

  Then, by selectively supplying a predetermined discharge signal to the individual electrode 35, pressure is applied to the liquid in the liquid pressurizing chamber 10 corresponding to the individual electrode 35. As a result, droplets are ejected from the corresponding liquid ejection holes 8 through the individual channels 32. That is, the portion of the piezoelectric actuator unit 21 that faces each liquid pressurizing chamber 10 corresponds to an individual displacement element 50 (actuator) corresponding to each liquid pressurizing chamber 10 and the liquid discharge hole 8. That is, in the laminate composed of two piezoelectric ceramic layers, the displacement element 50 having a unit structure as shown in FIG. 5 is provided immediately above the liquid pressurizing chamber 10 for each liquid pressurizing chamber 10. Are formed by a diaphragm 21a, a common electrode 34, a piezoelectric ceramic layer 21b, and individual electrodes 35, and the piezoelectric actuator unit 21 includes a plurality of displacement elements 50. In the present embodiment, the amount of liquid discharged from the liquid discharge hole 8 by one discharge operation is about 5 to 7 pL (picoliter).

  A large number of individual electrodes 35 are individually electrically connected to the actuator control means via contacts and wirings on the FPC so that potentials can be individually controlled.

In the piezoelectric actuator unit 21 in the present embodiment, when an electric field is applied to the piezoelectric ceramic layer 21b with the individual electrode 35 different in potential from the common electrode 34, the portion to which this electric field is applied becomes the piezoelectric effect. Acts as an active part that is distorted by At this time, the piezoelectric ceramic layer 21b expands or contracts in the thickness direction, that is, the stacking direction, and tends to contract or extend in the direction perpendicular to the stacking direction, that is, the plane direction, due to the piezoelectric lateral effect. On the other hand, since the remaining piezoelectric ceramic layer 21a is an inactive layer that does not have a region sandwiched between the individual electrode 35 and the common electrode 34, it does not spontaneously deform. That is, the piezoelectric actuator unit 21 uses the upper piezoelectric ceramic layer 21b (that is, the side away from the liquid pressurizing chamber 10) as a layer including the active portion and the lower side (that is, close to the liquid pressurizing chamber 10). In this configuration, the individual electrodes 35 are connected to the common electrode 34 by the actuator control means so that the electric field and the polarization are in the same direction. When the potential is positive or negative, the portion (active portion) sandwiched between the electrodes of the piezoelectric ceramic layer 21b contracts in the plane direction. On the other hand, since the piezoelectric ceramic layer 21a which is an inactive layer is not affected by an electric field, the piezoelectric ceramic layer 21a does not spontaneously shrink and tries to restrict deformation of the active portion. As a result, there is a difference in the strain in the polarization direction between the piezoelectric ceramic layer 21b and the piezoelectric ceramic layer 21a, and the piezoelectric ceramic layer 21b is deformed so as to protrude toward the liquid pressurizing chamber 10 (unimorph deformation). .

  In the actual driving procedure in this embodiment, the individual electrode 35 is set to a potential higher than the common electrode 34 (hereinafter referred to as a high potential) in advance, and the individual electrode 35 is temporarily set to the same potential as the common electrode 34 every time there is a discharge request. (Hereinafter referred to as a low potential), and then set to a high potential again at a predetermined timing. As a result, the piezoelectric ceramic layers 21a and 21b return to the original shape at the timing when the individual electrode 35 becomes low potential, and the volume of the liquid pressurizing chamber 10 is compared with the initial state (the state where the potentials of both electrodes are different). To increase. At this time, a negative pressure is applied to the liquid pressurizing chamber 10 and the liquid is sucked into the liquid pressurizing chamber 10 from the manifold 5 side. Thereafter, at the timing when the individual electrode 35 is set to a high potential again, the piezoelectric ceramic layers 21a and 21b are deformed so as to protrude toward the liquid pressurizing chamber 10, and the volume of the liquid pressurizing chamber 10 is reduced so that the inside of the liquid pressurizing chamber 10 Becomes a positive pressure, the pressure on the liquid rises, and droplets are ejected. That is, an ejection signal including a pulse based on a high potential is supplied to the individual electrode 35 in order to eject a droplet. The ideal pulse width is AL (Acoustic Length), which is the length of time during which the pressure wave propagates from the manifold 5 to the liquid discharge hole 8 in the liquid pressurizing chamber 10. According to this, when the inside of the liquid pressurizing chamber 10 is reversed from the negative pressure state to the positive pressure state, both pressures are combined, and the liquid droplet can be ejected with a stronger pressure.

  In gradation printing, gradation expression is performed by the number of droplets ejected continuously from the liquid ejection holes 8, that is, the droplet amount (volume) adjusted by the number of droplet ejections. For this reason, the number of droplet discharges corresponding to the specified gradation expression is continuously performed from the liquid discharge hole 8 corresponding to the specified dot region. In general, when liquid ejection is performed continuously, it is preferable that the interval between pulses supplied to eject liquid droplets is AL. As a result, the period of the residual pressure wave of the pressure generated when discharging the previously discharged liquid droplet coincides with the pressure wave of the pressure generated when discharging the liquid droplet discharged later, and these are superimposed. Thus, the pressure for discharging the droplet can be amplified.

  The liquid discharge head 2 as described above is manufactured as follows, for example.

  A tape composed of a piezoelectric ceramic powder and an organic composition is formed by a general tape forming method such as a roll coater method or a slit coater method, and a plurality of green sheets that become piezoelectric ceramic layers 21a and 21b after firing are produced. . An electrode paste to be the common electrode 34 is formed on a part of the green sheet by a printing method or the like. Further, if necessary, a via hole is formed in a part of the green sheet, and a via conductor is inserted into the via hole.

  Next, each green sheet is laminated to produce a laminate, and pressure adhesion is performed. The laminated body after pressure contact is fired in a high-concentration oxygen atmosphere, and then the individual electrodes 25 are printed on the fired body surface using an organic gold paste, fired, and then the connection electrode 36 is printed using an Ag paste. And the piezoelectric actuator unit 21 is produced by baking.

  Next, the flow path member 4 is produced by laminating the plates 22 to 31 with the adhesive layer 45 interposed therebetween. The plate (heater plate) 22 is an electric resistor having a high conductor resistance such as silicon nitride. Like the piezoelectric ceramic layers 21a and 21b described above, the silicon nitride powder is formed into a tape to form a hole that becomes the liquid pressurizing chamber 10. After being opened by punching and fired in a non-oxidizing atmosphere, the ground heater wiring 41 and the pattern heater wiring 42 were printed with Cu paste and fired in a non-oxidizing atmosphere. You may form the protective layer which protects the pattern heater wiring 42 as needed.

  The plates 23 to 31 are produced by producing a plate by a rolling method or the like and then processing holes to be the manifold 5, the individual flow path 32, a descender, and the like into a predetermined shape by etching. These plates 23 to 31 are preferably formed of at least one metal selected from the group of Fe—Cr, Fe—Ni, and WC—TiC, particularly when ink is used as a liquid. Since it is desired to be made of a material having excellent corrosion resistance against ink, Fe-Cr is more preferable.

  The piezoelectric actuator 21 and the flow path member 4 can be laminated and bonded via an adhesive layer 45, for example. A well-known adhesive layer can be used as the adhesive layer. However, in order not to affect the piezoelectric actuator 21 and the flow path member 4, an epoxy resin, a phenol resin, or a polyphenylene ether having a thermosetting temperature of 100 to 150 ° C. It is preferable to use at least one thermosetting resin adhesive selected from the group of resins. By heating to the thermosetting temperature using such an adhesive layer, the piezoelectric actuator 21 and the flow path member 4 can be heat-bonded.

  The adhesive layer 45 that bonds the heater plate 22 to the plate 21 or the piezoelectric actuator 21 may be an insulating adhesive or a conductive adhesive. Use of a conductive adhesive is preferable because electrical connection on the ground side of the heater plate 22 can be made through the plate of the flow path member 4.

  Thereafter, if necessary, a wiring for electrically connecting the heater wiring and the control unit 100, an FPC for electrically connecting the piezoelectric actuator 21 and the control unit 100, and the like are joined to form a liquid ejection head. 2 can be obtained.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims.

1 is a schematic configuration diagram illustrating a printer using a liquid discharge head according to an embodiment of the present invention. FIG. 2 is a plan view showing a head body that constitutes the liquid ejection head of FIG. 1. FIG. 3 is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. 2. (A) It is a longitudinal cross-sectional view along the IV-IV line of FIG. (B) It is the enlarged view to which a part of (a) was expanded. (A) It is the enlarged view to which a part of FIG. 2 was expanded. FIG. 2B is an enlarged view of the same location as FIG. 2A, in which the pattern heater wiring 42 is omitted and the ground heater wiring 41 is transmitted. (A) (b) (c) It is a schematic diagram of the flow-path member used for the modification of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Printer 2 ... Liquid discharge head 4 ... Flow path member 5 ... Manifold 5a ... Sub manifold 5b ... Opening 6 ... Individual supply flow path 8 ... Liquid discharge hole DESCRIPTION OF SYMBOLS 9 ... Liquid pressurization chamber group 10 ... Liquid pressurization chamber 12 ... Squeezing 21 ... Piezoelectric actuator unit 21a ... Piezoelectric ceramic layer (diaphragm)
21b: Piezoelectric ceramic layer 22: Plate (heater plate)
23-31 ... Plate 32 ... Individual flow path 34 ... Common electrode 35 ... Individual electrode 36 ... Connection electrode 41 ... Ground heater wiring 42 ... Pattern heater wiring 50 ... Displacement element

Claims (6)

  A plurality of liquid discharge holes, a plurality of liquid pressurizing chambers connected to the plurality of liquid discharge holes, and a main surface of the heater plate are formed by laminating a plurality of plates including a heater plate made of an electric resistor. A liquid discharge head, comprising: a flow path member including a heater wiring that is provided; and a plurality of pressurizing units that pressurize the liquid in the plurality of liquid pressurizing chambers.   2. The liquid according to claim 1, wherein the plate constituting the wall surfaces of the plurality of liquid pressurizing chambers is the heater plate, and the heater wiring is formed in the vicinity of the liquid pressurizing chamber. Discharge head.   3. The liquid according to claim 1, wherein the plurality of liquid pressurizing chambers are opened on one main surface of the flow path member, and the plate constituting the one main surface is the heater plate. Discharge head.   The liquid discharge head according to claim 1, wherein the heater wiring is formed on both main surfaces of the heater plate so as to face each other.   When the flow path member is viewed in plan from the stacking direction, the flow path member includes a liquid pressurization chamber forming region in which the plurality of liquid pressurization chambers are arranged in a matrix and a liquid pressurization other than the liquid pressurization chamber forming region. 5. The liquid according to claim 4, further comprising a pressure chamber forming region outside region, wherein the heater wiring has the same pattern in the liquid pressurizing chamber forming region and the liquid pressurizing chamber forming region outside region. Discharge head.   A liquid discharge head according to any one of claims 1 to 5, a transport unit that transports a recording medium to the liquid discharge head, a control unit that controls driving of the liquid discharge head and the temperature of the heater plate, A printing apparatus comprising:

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