JP2010269450A - Recording device - Google Patents

Abstract

To provide a recording apparatus using a head frame for fixing a plurality of liquid discharge heads and capable of performing high-precision printing even when the liquid discharge heads are heated.
A recording apparatus main body having a plurality of liquid ejection heads 2 and a head frame 60 to which the plurality of liquid ejection heads are fixed, a conveyance unit for conveying a recording medium, the plurality of liquid ejection heads 2 and the conveyance The liquid discharge head 2 includes a liquid discharge hole group 7 in which a plurality of liquid discharge holes are arranged long in one direction, a plurality of liquid pressurization devices, A fixing portion for fixing the liquid discharge head to the head frame 60 and a first heater provided outside the one end of the liquid discharge hole group 7, and the head frame 60. Includes a second heater 72, and the control unit controls the first heater and the second heater 72.
[Selection] Figure 7

Description

  The present invention relates to a recording apparatus for printing an image by attaching to a recording apparatus main body a head frame in which a plurality of liquid discharge heads for discharging droplets are fixed.

  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 ink as droplets from the ink ejection holes, and a part of the wall of the ink channel filled with ink is bent and displaced by a displacement element, and the ink in the ink channel is mechanically pressurized, and the ink A piezoelectric method for discharging liquid droplets from discharge holes is generally known.

  In addition, in such a liquid discharge head, a serial type that performs recording while moving the liquid discharge head in a direction orthogonal to the conveyance direction of the recording medium, and a state in which the liquid discharge head that is longer in the main scanning direction than the recording medium is fixed Alternatively, there is a line type in which recording is performed on a recording medium conveyed in the sub-scanning direction in a state where a plurality of liquid discharge heads are arranged and fixed so that the recording range is wider than the recording medium. 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 displacement elements provided so as to cover the liquid pressurization chambers, respectively. There is known a configuration in which an actuator unit having a laminated structure is formed (see, for example, Patent Document 1). In this liquid ejection head, the liquid pressurizing chambers connected to the plurality of liquid ejection holes are arranged in a matrix, and the displacement elements of the actuator unit provided so as to cover the chambers are displaced so that each liquid ejection chamber Ink is ejected and printing is possible at a resolution of 600 dpi in the main scanning direction.

JP 2003-305852 A

  When a plurality of liquid discharge heads as described in Patent Document 1 are arranged in the main scanning direction and printing is performed in a wider range, it is necessary to arrange the plurality of liquid discharge heads with high accuracy. For example, when the distance in the main scanning direction between two liquid ejection heads is longer than a predetermined distance, another liquid ejection head adjacent to a pixel printed by one liquid ejection head Since the distance between the printed pixels is larger than a predetermined pixel interval, there is a possibility that the color density of the portion may appear light or the unprinted background may be seen. In addition, in any case, when the distance in the main scanning direction between the two liquid ejection heads becomes shorter, the distance in the direction perpendicular to the main scanning direction changes, or the angle between the two liquid ejection heads changes. Print accuracy is poor.

  Further, if the liquid discharge head requiring such high accuracy is directly attached to the recording apparatus main body, the operation becomes complicated and it is difficult to increase the attachment accuracy in the first place. Therefore, a method of attaching a plurality of liquid discharge heads to the head frame with high accuracy and attaching a head frame to which the liquid discharge head is attached to the recording apparatus main body can be considered.

  Further, in the liquid discharge head, the liquid discharge head may be heated to a constant temperature in order to make the viscosity of the liquid flowing inside the liquid discharge head constant in order to stabilize the liquid discharge characteristics. However, even if the liquid ejection head is attached to the head frame with high accuracy at a temperature of about room temperature, if the liquid ejection head is heated, the arrangement of the liquid ejection heads in the head frame is shifted, resulting in poor printing accuracy. It was.

  Accordingly, an object of the present invention is to provide a recording apparatus using a head frame in which a plurality of liquid discharge heads are fixed and capable of performing high-precision printing even when the liquid discharge head is heated.

  The recording apparatus of the present invention includes a recording apparatus main body having a plurality of liquid ejection heads and a head frame to which the plurality of liquid ejection heads are fixed, a transport unit that transports a recording medium to the liquid ejection head, and the plurality A liquid ejection head and a control unit that controls the transport unit, wherein the liquid ejection head includes a liquid ejection hole group in which a plurality of liquid ejection holes are arranged long in one direction, and the plurality of liquid ejection holes. A plurality of liquid pressurizing devices that respectively discharge liquid from the liquid discharge holes, and a fixing portion that is provided outside the one-direction end of the liquid discharge hole group and that fixes the liquid discharge head to the head frame And the first heater, the head frame includes a second heater, and the control unit controls the first heater and the second heater. The features.

  Further, when the thermal expansion coefficient of the liquid discharge head is larger than the thermal expansion coefficient of the head frame, the control unit controls the temperature of the first heater to be lower than that of the second heater, and the liquid When the thermal expansion coefficient of the ejection head is smaller than the thermal expansion coefficient of the head frame, the control unit preferably controls the temperature of the first heater to be higher than that of the second heater.

Furthermore, the thermal expansion coefficient of the liquid discharge head is α _H / ° C., the thermal expansion coefficient of the head frame is α _F / ° C., and the liquid discharge head and the head frame are fixed at T ° C. When the recording is performed such that the temperature of the liquid discharge head is set to T _H ° C. by the first heater, the control unit moves the head frame to α _F (T _F −T) by the second heater. It is preferable to control the temperature so that the temperature T _F ° C satisfying α _H (T _H −T) is satisfied.

Furthermore, it is preferable that the head frame includes a cooling unit using a thermoelectric conversion element, and the control unit controls the temperature of the head frame to be T _F ° C by the cooling unit.

  Furthermore, the liquid discharge head is disposed so that the liquid discharge hole group is continuous when viewed from the transport direction in which the transport unit transports the recording medium to the liquid discharge head, and the head frame is It is preferable that the second heater is continuously provided in a certain range of the liquid discharge head as viewed from the transport direction.

  Furthermore, it is preferable that the head frame has a flat plate shape, and the second heater is provided symmetrically on the upper and lower surfaces of the head frame.

  The recording apparatus of the present invention is characterized in that the head frame is flat and the second heater is provided between the upper and lower surfaces of the head frame.

  According to the recording apparatus of the present invention, a recording apparatus main body having a plurality of liquid ejection heads and a head frame to which the plurality of liquid ejection heads are fixed, a transport unit that transports a recording medium to the liquid ejection head, The recording apparatus having a plurality of liquid ejection heads and a control unit that controls the transport unit, wherein the liquid ejection head includes a liquid ejection hole group in which a plurality of liquid ejection holes are arranged long in one direction; A plurality of liquid pressurizing devices that respectively discharge liquid from the plurality of liquid discharge holes, and the liquid discharge head provided outside the one-direction end of the liquid discharge hole group are fixed to the head frame. A fixing unit; a first heater; the head frame includes a second heater; and the control unit controls the first heater and the second heater. Thus, the elongation due to thermal expansion of the head frame and the elongation due to thermal expansion of the liquid ejection head can be controlled separately, so that the position between the liquid ejection heads can be maintained while maintaining the liquid ejection head at a temperature suitable for printing. Accuracy can be maintained.

  Further, when the thermal expansion coefficient of the liquid discharge head is larger than the thermal expansion coefficient of the head frame, the control unit controls the temperature of the first heater to be lower than that of the second heater, and the liquid When the thermal expansion coefficient of the ejection head is smaller than the thermal expansion coefficient of the head frame, the control unit controls the temperature of the first heater to be higher than that of the second heater. In this case, after the liquid discharge head is fixed to the head frame at about room temperature, the first heater is used to maintain the liquid discharge head at a temperature suitable for printing, while the second heater Since the elongation due to the thermal expansion of the head frame can be close to the elongation due to the thermal expansion of the liquid ejection head, the positional accuracy between the liquid ejection heads can be maintained.

Furthermore, the thermal expansion coefficient of the liquid discharge head is α _H / ° C., the thermal expansion coefficient of the head frame is α _F / ° C., and the liquid discharge head and the head frame are fixed at T ° C. When the recording is performed such that the temperature of the liquid discharge head is set to T _H ° C. by the first heater, the control unit moves the head frame to α _F (T _F −T) by the second heater. When the temperature T _F is controlled to satisfy α = _H (T _H −T), the elongation due to the thermal expansion of the head frame and the elongation due to the thermal expansion of the liquid discharge head are substantially equal. Since the temperature can be controlled, the positional accuracy between the liquid ejection heads can be further maintained, and the positional accuracy between the liquid ejection heads can be further maintained.

Further, the head frame includes a cooling unit using a thermoelectric conversion element, and the control unit controls the second frame when the temperature of the head frame is controlled to T _F ° C by the cooling unit. Even if the heating is not performed by the heater, the head frame is cooled by the cooling unit even when the temperature of the head frame becomes T _F ° C or higher due to the heat transmitted from the liquid discharge head. Thus, the temperature of the head frame can be controlled to T _F ° C., and the positional accuracy between the liquid ejection heads can be further maintained.

  Furthermore, the liquid discharge head is disposed so that the liquid discharge hole group is continuous when viewed from the transport direction in which the transport unit transports the recording medium to the liquid discharge head, and the head frame is When the second heater is continuously provided in a range of the liquid discharge head as viewed from the transport direction, the temperature in the head frame of the range of the liquid discharge head that discharges droplets to the recording medium And the positional accuracy between the liquid discharge heads can be further maintained.

  Furthermore, when the head frame has a flat plate shape and the second heater is provided symmetrically on the upper and lower surfaces of the head frame, the flat head frame bends due to a temperature difference between the upper surface and the lower surface. Therefore, the positional accuracy between the liquid ejection heads can be further maintained.

  Furthermore, when the head frame has a flat plate shape and the second heater is provided between the upper and lower surfaces of the head frame, the flat head frame bends due to a temperature difference between the upper surface and the lower surface. Therefore, the positional accuracy between the liquid ejection heads can be further maintained.

1 is a schematic configuration diagram of a printer that is a recording apparatus 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. FIG. 3 is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. It is a longitudinal cross-sectional view along the VV line of FIG. FIG. 5 is a schematic diagram illustrating a method for fixing a liquid ejection head to a head frame in an embodiment of the present invention. (A) is a top view of the head frame in one embodiment of the present invention, and (b) is a side view. (C) is a top view of the head frame in other one Embodiment of this invention, (d) is a side view. (E) is a top view of the head frame in other one Embodiment of this invention, (f) is a side view. (A) is a top view of the head frame in other one Embodiment of this invention, (b) is a side view. (C) is a top view of the head frame in other one Embodiment of this invention, (d) is a side view. (E) is a top view of the head frame in other one Embodiment of this invention, (f) is a side view.

  FIG. 1 is a schematic configuration diagram of a color ink jet printer which is a recording apparatus including a liquid discharge head according to an embodiment of the present invention. The color inkjet printer 1 (hereinafter referred to as printer 1) has 16 liquid ejection heads 2. FIG. 1 shows eight liquid discharge heads 2, but two liquid discharge heads 2 are arranged in the direction from the front to the back of FIG. 1, and four liquid discharge heads 2 are one head frame. 60 is fixed. The four head frames 60 are arranged along the conveyance direction of the printing paper P and are fixed to the printer 1. The liquid discharge head 2 includes a first heater (not shown) and stabilizes the liquid discharge characteristics by keeping the temperature of the liquid therein constant. The head frame 60 includes a second heater (not shown), and the head frame 60 is heated to reduce the variation in the position of the liquid ejection head 2.

  In the printer 1, 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 part of the printer 1 such as the liquid ejection head 2 including the first heater, the second heater, and the paper feed 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 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 are rotatably installed and rotate in conjunction with the conveyance 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 16 liquid ejection 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 large number of liquid ejection holes 8 for ejecting liquid are provided on the lower surface of the head body 13 (see FIG. 3).

  Liquid droplets (ink) of the same color are ejected from the liquid ejection holes 8 provided in one liquid ejection head 2. The liquid ejection holes 8 of each liquid ejection head 2 are arranged at equal intervals in one direction (a direction parallel to the printing paper P and perpendicular to the transport direction of the printing paper P, the longitudinal direction of the liquid ejection head 2). The four liquid discharge heads 2 fixed to one head frame 60 are arranged so that the liquid discharge holes 8 are equally spaced in the one direction. Can print without gaps. In other words, when the liquid discharge hole group 7 including the liquid discharge holes 8 included in the liquid discharge head 2 is viewed from the transport direction, the liquid discharge hole group 7 is in a continuous state. That is, the ejection head 2 is arranged.

  The color of the liquid ejected from each liquid ejection head 2 is the same in the four liquid ejection heads 2 fixed to one head frame 60, and magenta (M), yellow (Y), and cyan, respectively. (C) and black (K). 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, droplets are ejected from the head main body 13 constituting the liquid ejection 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 out 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 top view showing the head main body 13 shown in FIG. FIG. 3 is an enlarged top view of a region surrounded by the alternate long and short dash line in FIG. 2 and is a part of the head main body 13. FIG. 4 is an enlarged perspective view of the same position as in FIG. 3, in which some of the flow paths are omitted so that the position of the liquid discharge holes 8 can be easily understood. 3 and 4, in order to make the drawings easy to understand, the liquid pressurizing chamber 10 (liquid pressurizing chamber group 9), the squeezing 12, and the liquid discharge holes which are to be drawn by broken lines below the piezoelectric actuator unit 21. 8 is drawn with a solid line. FIG. 5 is a longitudinal sectional view taken along line VV in FIG.

  The head body 13 includes a flat plate-like flow path member 4 and a piezoelectric actuator unit 21 that is an actuator unit on the flow path member 4. 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 to each other on the flow path member 4 partially overlap in the short direction of the flow path member 4. In the area printed by driving the overlapping piezoelectric actuator unit 21, the droplets ejected by the two piezoelectric actuator units 21 are mixed and landed.

  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 main body 13 adjacent to each other in regions facing the 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 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 almost 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 E1-E4 sub-manifolds 5a arranged in parallel with each other in the short direction of the flow path member 4, and each sub-manifold The liquid pressurizing chambers 10 connected to 5a constitute a row of liquid pressurizing chambers 10 arranged in the longitudinal direction of the flow path member 4 at equal intervals, and the four rows are arranged in parallel to each other in the short direction. Yes. 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 displacement element 50 that is an actuator. ing. 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 the sub-manifolds 5a are not always connected at equal intervals when the liquid ejection holes 8 for 600 dpi are divided and connected to the four sub-manifolds 5a. This means that the individual flow paths 32 are formed at intervals of an average of 170 μm (25.4 mm / 150 = 169 μm intervals 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. These liquid discharge hole groups 7 occupy an area having almost the same size and shape as the piezoelectric actuator unit 21, and the liquid discharge holes 8 are made to drop liquid by displacing the displacement element 50 of the corresponding piezoelectric actuator unit 21. Can be discharged. The arrangement of the liquid discharge holes 8 will be described in detail later. 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.

  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. A number of holes are formed in these plates. Each plate is aligned and laminated so that these holes communicate with each other to form the individual flow path 32 and the sub-manifold 5a. As shown in FIG. 5, the head main body 13 has a liquid pressurizing chamber 10 on the upper surface of the flow path member 4, the sub-manifold 5a on the inner lower surface side, and the liquid discharge holes 8 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 holes formed in each plate will be described. 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 27-30.

  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.

  As shown in FIG. 5, 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 and the flow path member 4 are bonded through, for example, an adhesive layer. As the adhesive layer, in order not to affect the piezoelectric actuator unit 21 and the flow path member 4, at least one kind selected from the group of epoxy resin, phenol resin, and polyphenylene ether resin having a thermosetting temperature of 100 to 150 ° C. A thermosetting resin adhesive is used. The reason why the thermosetting resin adhesive is used is that the room temperature curing adhesive may not ensure sufficient ink resistance. For this reason, the piezoelectric actuator unit 21 is in a state in which a stress generated by a difference in thermal expansion coefficient between the flow path member 4 and the piezoelectric actuator unit 21 is applied by being cooled from the thermosetting temperature to room temperature. When the stress is large, the piezoelectric actuator unit 21 may be broken, and even if the stress is not so high that the piezoelectric actuator unit 21 is broken, the characteristics of the piezoelectric actuator unit 21 vary depending on the applied stress. Specifically, in a state where compressive stress is applied, the piezoelectric constant is lowered, but the influence of the phenomenon of drive deterioration in which the amount of displacement is reduced when the drive is repeated for a very long time is reduced. On the contrary, in a state where tensile stress is applied, the piezoelectric constant increases, but the influence of drive deterioration increases. In any case, the difference in coefficient of thermal expansion between the flow path member 4 and the piezoelectric actuator unit 21 needs to be reduced. It is preferable that a small compressive stress is weakly applied. Therefore, when PZT ceramics are used for the piezoelectric actuator unit 21, it is preferable to use 42 alloy as the material of the flow path member 4.

  The first heater provided in the liquid discharge head 2 has the same shape as that of the piezoelectric actuator unit 21 when viewed in plan, and is attached on the piezoelectric actuator unit 21 or on the FPC on the piezoelectric actuator unit 21 or on the manifold. It can be attached to another flow path for filtering the liquid before entering the opening 5b. As the first heater, various types such as a film heater and a ceramic heater can be used.

  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, a drive signal is supplied to the individual electrode 35 from the control unit 100 through the FPC. The drive signal is supplied in a constant cycle in synchronization with the conveyance speed of the print medium P.

  The common electrode 34 is formed over almost the entire surface in the area 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. 5, the common electrode 34 and the individual electrode 35 are disposed 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.

  As will be described later, when a predetermined drive signal is selectively supplied 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 discharged from the corresponding liquid discharge ports 8 through the individual flow paths 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 port 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 ejected from the liquid ejection port 8 by one ejection 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 in the polarization direction to the piezoelectric ceramic layer 21b by setting the individual electrode 35 to a potential different from that of the common electrode 34, the portion to which this electric field is applied is piezoelectric. Acts as an active part that is distorted by the effect 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 surface 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. In other words, 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). This is a so-called unimorph type configuration in which the piezoelectric ceramic layer 21a on the side) is an inactive layer.

  In this configuration, when the individual electrode 35 is set to a predetermined positive or negative potential with respect to the common electrode 34 by the actuator controller so that the electric field and the polarization are in the same direction, a portion sandwiched between the electrodes of the piezoelectric ceramic layer 21b. (Active part) contracts in the surface direction. On the other hand, the piezoelectric ceramic layer 21a, which is an inactive layer, is not affected by an electric field, so that it does not spontaneously shrink and tries to restrict deformation of the active portion. As a result, there is a difference in 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 an actual driving procedure in the present 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, a drive 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.

  In such a printer 1, by adjusting the period to the conveyance speed and drive signal of the printing paper P, an image having a resolution of 600 dpi in the longitudinal direction and 600 dpi in the conveyance direction can be recorded. For example, if the drive signal is 20 kHz and the transport speed is 0.83 m / sec, the discharged droplets can land on the printing paper P every about 42 μm in the transport direction, and the resolution in the transport direction is 600 dpi. .

  Further, details of the head frame 60 will be described with reference to a plan view of the head frame 60 in FIG. 7A and FIG. 7B which is a side view thereof. FIG. 7B is a side view seen from the lower side in FIG. 7A. However, since it is complicated, the liquid discharge head 2 and the second heater 72 on the back side in FIG. It is omitted.

  The recording apparatus of the present invention has a structure in which a plurality of liquid ejection heads 2 are fixed to a head frame 60 and the head frame 60 is attached to the recording apparatus. By adopting such a structure, working efficiency is improved as compared with the case where a plurality of liquid ejection heads 2 are directly fixed to the recording apparatus main body. In addition, for example, the liquid ejection head 2 can be positioned on the head frame 60 using a precise large-sized measuring device, so that it can be attached with high positional accuracy.

  The head complaint 60 includes an opening 65, and the liquid ejection head 2 is inserted into the opening 65 and fixed by fixing portions 52 at both ends thereof. A second heater 72 is also provided. Furthermore, a mounting portion 67 for attaching the head frame to the recording apparatus is provided, so that the head frame is attached to the recording apparatus main body. The liquid discharge hole group 7 of the liquid discharge head 2 is continuous in one direction, which is the longitudinal direction of the liquid discharge hole group 7, when viewed from the vertical direction of the drawing, which is the transport direction in FIG. In addition, a liquid discharge head 2 is arranged. Further, the fixing portion 52 that fixes the liquid discharge head 2 and the head complaint 60 is located outside the one direction of the liquid discharge hole group 7 and in a direction perpendicular to the one direction of the liquid discharge hole group 7. It is provided within the range where the hole group 7 exists.

  The thermal expansion coefficient of the liquid ejection head 2 occupies most of the volume and is often close to the flow path member 4 that is a structural member, and the thermal expansion coefficient is often matched to the piezoelectric actuator 21 to some extent. Further, the head frame 60 is often selected from various metal materials such as SUS due to its strength and cost. However, since it is possible to use different types of liquid discharge heads 2, the liquid discharge heads may be used. 2 often has a different coefficient of thermal expansion.

  Further, the fixing environment is often about room temperature (25 ° C.). In the liquid discharge head 2, the viscosity of the liquid flowing inside the liquid discharge head 2 is made constant for the purpose of stabilizing the liquid discharge characteristics. Therefore, the liquid discharge head 2 is heated by the first heater so that the temperature becomes constant. Part of this heat is transferred to the head frame 60 and raises the temperature of the head frame 60. When the second heater 72 is not used, the elongation due to the thermal expansion of the liquid ejection head 2 and the elongation due to the thermal expansion of the head frame 60 are greatly different. As a result, the mounting position of the liquid ejection head 2 is the position at the room temperature. Deviate. And the printing accuracy deteriorates because the landing position of the ejected droplets shifts.

  Therefore, if the temperature of the liquid ejection head 2 and the temperature of the head frame 60 are controlled separately using the second heater 72, the positional relationship of the liquid ejection head 2 can be kept close to the room temperature position. it can. That is, when the thermal expansion coefficient of the liquid discharge head 2 is larger than the thermal expansion coefficient of the head frame 60, the temperature of the first heater is controlled to be lower than the second heater 72, and the heat of the liquid discharge head 2 is controlled. When the expansion coefficient is smaller than the thermal expansion coefficient of the head frame 60, the temperature of the first heater is controlled to be higher than that of the second heater 72. It is possible to approach elongation due to thermal expansion of the head, and the positional accuracy of the liquid discharge head 2 can be kept close to a room temperature position. In addition, as the 2nd heater 72, various things, such as a film heater and a ceramic heater, can be used.

More specifically, the thermal expansion coefficient of the liquid discharge head 2 is α _H / ° C., the thermal expansion coefficient of the head frame 60 is α _F / ° C., and the liquid discharge head 2 and the head frame 60 are connected to T ° C. When the recording is performed so that the temperature of the liquid ejection head 2 is set to T _H ° C. by the first heater, the head frame 60 is moved to α _F (T _F −T) = α _H by the second heater 72. By controlling so that the temperature T _F ° C satisfies (T _H −T), the elongation due to the thermal expansion of the head frame 60 and the elongation due to the thermal expansion of the liquid ejection head can be made substantially equal. The position accuracy can be kept close to the room temperature position. It should be noted that the thermal expansion history number and the numerical value of the temperature can be stored and controlled in advance in the control unit, or can be controlled by inputting and setting before starting printing.

  At this time, since the fixing portion 52 for fixing the liquid discharge head 2 to the head frame 60 is provided outside the one end of the liquid discharge hole group 7, there is room for the liquid discharge hole group 7 to freely thermally expand. Is decreasing. By doing so, even if there is a difference between the expansion due to the thermal expansion of the head frame 60 and the expansion due to the thermal expansion of the liquid discharge head due to fluctuations in the environmental temperature, etc., the liquid discharge hole group of one liquid discharge head 2 The position of the end 7 is not easily displaced from the end of the liquid discharge hole group 7 of the adjacent liquid discharge head 2, and the printing accuracy is improved.

  When the liquid discharge head 2 and the head frame 60 are fixed via a heat insulating material, different temperatures are hardly transmitted to the other in the vicinity of the boundary between the liquid discharge head 2 and the head frame 60, It is easy to keep the difference constant.

  As described above, since the thermal expansion coefficient of the liquid discharge head 2 is often close to that of piezoelectric ceramics such as PZT, the thermal expansion coefficient of the head frame 60 is higher than the thermal expansion coefficient of the liquid discharge head 2. Is considered to be larger. In such a case, even if the second heater 72 is not heated, the elongation due to the thermal expansion of the head frame 60 due to the heat transmitted from the liquid ejection head 2 becomes larger than the elongation due to the thermal expansion of the liquid ejection head 2. It is also possible. In such a case, as shown in FIGS. 8E and 8F, the head frame 560 is provided with a cooling unit 573 using a thermoelectric conversion element, and the control unit 100 controls the cooling unit so that the liquid The positional accuracy of the ejection head 2 can be kept close to the room temperature position. If the thermal expansion coefficient and operating temperature of the liquid discharge head and the head frame are known, if the head frame does not need to be heated, the second heater is not provided, but only the cooling unit is provided. Also good.

Then, the specific example of control is shown. As the piezoelectric actuator unit 21, a piezoelectric ceramic layer having a thermal expansion coefficient of 7 × 10 ⁻⁶ / ° C. where the piezoelectric ceramic layers are 21 a and 21 b is PZT, and the plates 22 to 31 are Fe—Cr based as the liquid ejection head 2. An alloy having a thermal expansion coefficient of 12 × 10 ⁻⁶ / ° C. is used, and an aluminum alloy having a thermal expansion coefficient of 20 × 10 ⁻⁶ / ° C. is used as the head frame 60. The length of the long side of the liquid discharge hole group 7 is about 108.25 mm (4.25 inches). The liquid ejection head 2 is incorporated into the head frame 60 in a state where each member is at 25 ° C. in an environment where the temperature is 25 ° C. Further, the head frame 60 is incorporated in the printer 1.

  In order to perform printing, the liquid discharge head 2 is heated to 50 ° C. by the first heater. For example, if the temperature of the temperature sensor provided in the liquid ejection head 2 is lower than 50 ° C., the first heater is controlled to generate heat. If printing is continued in such a state, the head frame 60 may reach about 30 ° C. due to heat transferred from the liquid ejection head 2. In this case, due to the difference in temperature and thermal expansion between the liquid ejection head 2 and the head frame 60, a difference of about 22 μm occurs in the length of the liquid ejection hole group 7, and the liquid ejection head 2 and the head frame 60 are deformed. As a result, the position of the liquid discharge hole 8 changes. Therefore, the temperature of the head frame 60 may be controlled to 40 ° C. by the second heater 72. For example, if the temperature of the temperature sensor attached to the head frame 60 is lower than 34 ° C., the second heater 72 may be controlled to generate heat. If the head frame 60 is controlled within 40 ± 2 ° C., the positional deviation due to thermal expansion will be within 4 μm at the maximum. When printing at 600 dpi, the printing dot interval is about 42 μm, and good printing can be achieved if the deviation is 1/10 or less.

  Next, details of a method of fixing the liquid ejection head 2 to the head frame 60 will be described with reference to FIG. FIG. 6A is a schematic perspective view of a part of the head frame 60 in a state where the liquid ejection head 2 is fixed to the head frame 60. FIG. 6B is a schematic perspective view before the liquid discharge head 2 is fixed to the head frame 60 shown in FIG. 6A, and shows the positional relationship between the head frame 60 and the liquid discharge head 2. FIG. 6C is a partial top view of FIG. 6B showing a state where the liquid discharge head 2 and the positioning pin of the head frame 60 are in contact with each other. FIG. 6D is a partial bottom view of FIG. 6B showing a state where the liquid discharge head 2 and the positioning pin of the head frame 60 are in contact with each other. The liquid discharge hole group 7 constituted by the liquid discharge holes 8 has the same arrangement as the liquid discharge holes 8 shown in FIG. 4, and the four liquid discharge holes arranged in a trapezoidal shape are alternately arranged. However, in FIG. 6D, the number of the liquid discharge holes 8 is reduced to show the outline.

  The liquid ejection hole group 7 of the liquid ejection head 2 has a rectangular shape that is long in the longitudinal direction of the liquid ejection head 2 on the nozzle plate 31 that is the lower surface of the liquid ejection head 2. In FIG. 6D, the liquid discharge holes 8 that are out of the liquid discharge hole group 7 are liquid discharge holes 8 that do not discharge liquid, and the range that is printed by the liquid discharge head 2 is a rectangular liquid discharge hole group. 7 is the range of the width of the long side. The liquid discharge head 2 is the lower surface thereof, and the nozzle plate 31 in which the liquid discharge hole group 7 is formed is incorporated in the head frame 60 so as to be parallel to the main surface of the head frame 60. The liquid discharge head 2 is in contact with two positioning pins 61a and 61b provided perpendicularly from the main surface of the head frame 60 on the outer side from the short side of the liquid discharge hole group 7, and one positioning pin 61a is The center of rotation of the liquid ejection head 2 is determined within a plane parallel to the main surface of the head frame 60, and the other positioning pin 61b regulates the rotation of the liquid ejection head 2. The liquid discharge head 2 is screwed to the head frame 60 by screws 55a at a fixing portion 52a between the outer side of the short side of the liquid discharge hole group 7 on the positioning pin 61a side and the contact portion with the positioning pin 61a. The head frame 60 is screwed to the head frame 60 by screws 55b at a fixing portion 52b between the outer side of the short side of the liquid discharge hole group 7 on the positioning pin 21b side and the contact portion of the positioning pin 21b.

  Thereby, the position of the liquid discharge head 2 is determined without play with respect to the positioning pins 61a and 61b. That is, the position of the liquid discharge hole group 7 formed in the liquid discharge head 2 with respect to the positioning pins 61a and 61b is determined without play, and the position of the liquid discharge hole 8 can be assembled to the head frame 60 with high accuracy.

  This assembly can be performed in a very short time because the liquid ejection head 2 is simply pressed against the head frame 60 and fixed. Further, when assembling, it is not necessary to measure the position of the liquid ejection head 2, and it is possible to replace only the liquid ejection head 2 while the head frame 60 remains attached to the printer 1.

  The liquid discharge head 2 and the head frame 60 are fixed by attaching the screws 25a and 25b to the screw holes 62a and 62b of the head frame 60 through the through holes, respectively. Fixing may be performed with bolts and nuts by forming through holes in portions 24a and 24b. By using screws or bolts, it can be easily removed and re-fixed.

  The portions of the positioning pins 61a and 61b that are in contact with the liquid ejection head 2 are each formed of a curved surface that protrudes outward as viewed from the direction perpendicular to the main surface of the head frame 60. One positioning pin 61a Is preferably in line contact with two surfaces of the head frame 60 in the length direction, and the other positioning pin 61b is in line contact with one surface of the head frame 60 in the length direction. In this way, even if the abutting action is repeated as compared with the case of point contact, there is little deterioration in accuracy. Each surface is more preferably a flat surface. This is because it is easy to increase the processing accuracy of the surface.

  Furthermore, it is more preferable that the positioning pins 61a and 61b have a cylindrical shape. Thereby, since the contact part is a smooth curve, even if the contact | abutting action is repeated, there is little degradation of an accuracy. Also, a product with high dimensional accuracy is easy to manufacture. Note that a cross-section with a semicircular cross section excluding a portion that does not clearly contact, or a columnar shape with a quarter of the circumference as a straight line may be used.

  Further, since the head frame 60 and the liquid discharge head 2 are in contact with each other mainly on the main surface of the head frame 60, a heat insulating material is provided between the head frame 60 and the liquid discharge head 2 in that portion. If it is inserted, in the vicinity of the boundary between the liquid ejection head 2 and the head frame 60, the influence of the different temperatures on the other is reduced, and the temperature difference is easily kept constant. As the heat insulating material, those having a lower thermal conductivity than metal, for example, resin and rubber are preferable, and those in which a large amount of air is contained by foaming them are more preferable.

  7 (c) to 7 (f) and FIGS. 8 (a) to 8 (f) are other examples of the head frame in the present invention. FIG. 7C is a plan view of the head frame 160, and FIG. 7D is a side view thereof. FIG. 7E is a plan view of the head frame 260, and FIG. 7F is a side view thereof. FIG. 8A is a plan view of the head frame 360, and FIG. 8B is a side view thereof. FIG. 8C is a plan view of the head frame 460, and FIG. 8D is a side view thereof. FIG. 8E is a plan view of the head frame 560, and FIG. 8F is a side view thereof.

  The head claims 160, 260, 360, 460, 560 are provided with openings 165, 265, 365, 465, 565, into which liquid discharge heads 102, 202, 302, 302, 402, 502 are placed. It is fixed by fixing portions 152, 252, 352, 452, and 552 at both ends. In addition, second heaters 172, 272, 372, 472, and 572 are provided. Furthermore, it has mounting portions 167, 267, 367, 467, and 567 for attaching the head frame to the recording apparatus, and is attached to the recording apparatus main body. Note that the liquid discharge hole groups 107, 207, 307, 307, 407, and 507 included in the liquid discharge heads 102, 202, 302, 302, 402, and 502 are liquid discharge hole groups 107, 207, The liquid discharge heads 102, 202, 302, 302, 402, 502 are arranged so as to be continuous in a direction that is the longitudinal direction of 307, 307, 407, 507. Further, the fixing portions 152, 252, 352, 452, and 552 that fix the liquid discharge heads 102, 202, 302, 302, 402, 502 and the head claims 160, 260, 360, 460, 560 are the liquid discharge hole group 107. , 207, 307, 307, 407, 507 and in the direction perpendicular to the one direction of the liquid discharge hole groups 107, 207, 307, 307, 407, 507, the liquid discharge hole group 107, 207, 307, 307, 407, 507 are provided in the existing range.

  In the head claims 160 and 260, the second heaters 172 and 272 are continuously provided in a range of all the liquid discharge heads 102 and 202 in the one direction of the head frames 160 and 260. The difference in temperature between 160 and 260 can be reduced, and the positional accuracy between the liquid ejection heads 102 and 202 can be further maintained. Since the head frame 260 includes the second heater 272 on the side surface of the frame, the head frame 260 is provided even though the second heater 272 is continuously provided in a certain range of the liquid discharge head 202. Can be reduced.

  The head frame 360 has a flat plate shape, and when the second heater 372 is provided symmetrically on the upper and lower surfaces of the head frame 360, the flat head frame 360 can be prevented from being bent due to a temperature difference between the upper surface and the lower surface. Therefore, the positional accuracy between the liquid discharge heads 202 can be further maintained. When the head frame 360 is bent, the landing position is shifted because the distance from the recording medium changes.

  The head frame 460 is flat and has a recess 469, and a second heater 472 is provided in the recess 469. That is, since the second heater 472 is provided between the upper and lower surfaces of the head frame 460, the flat head frame 460 can be prevented from being bent due to a temperature difference between the upper surface and the lower surface. The position accuracy can be further maintained.

  In the above, the embodiment in which four liquid ejection heads for one color are incorporated in one head frame has been described. However, the present invention is not limited to this, and is modified or improved without departing from the gist of the present invention. Is also applicable. For example, the number of liquid ejection heads incorporated in the head frame is not limited as long as it is two or more. Further, the liquid ejection head incorporated in the head frame is not limited to ejecting droplets of the same color, and a multicolor head may be incorporated.

  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 plates 22 to 31 obtained by a rolling method or the like. Holes to be the manifold 5, the individual supply flow path 6, the liquid pressurizing chamber 10, the descender, and the like are processed in the plates 22 to 31 into a predetermined shape by etching.

  These plates 22 to 31 are preferably formed of at least one metal selected from the group consisting 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. Further, when the flow path member 4 and the piezoelectric actuator unit 21 are bonded with a thermosetting resin, an Fe—Ni system that can reduce the difference in thermal expansion coefficient is more preferable, and a weak compressive stress is applied to the electric actuator unit 21. The 42 alloy is particularly preferable in that it can be brought into a state of contact.

  The piezoelectric actuator unit 21 and the flow path member 4 can be laminated and bonded via an adhesive layer, for example. A well-known adhesive layer can be used as the adhesive layer, but in order not to affect the piezoelectric actuator unit 21 and the flow path member 4, an epoxy resin, phenol resin, polyphenylene having a thermosetting temperature of 100 to 150 ° C. It is preferable to use an adhesive of at least one thermosetting resin selected from the group of ether resins. It adheres by heating to the thermosetting temperature using such an adhesive layer, and is attached to another flow path member equipped with a first heater while filtering the liquid before entering the opening 5b of the manifold. Thus, the liquid discharge head 2 can be obtained.

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 7 ... Liquid discharge hole Group 8 ... Liquid discharge hole 9 ... Liquid pressurization chamber group 10 ... Liquid pressurization chamber 11a, b, c, d ... Liquid pressurization chamber row 12 ... Squeeze 15a, b, c , D: liquid discharge hole array 21: piezoelectric actuator unit 21a: piezoelectric ceramic layer (vibrating plate)
21b ... Piezoelectric ceramic layer 22-31 ... Plate 32 ... Individual flow path 34 ... Common electrode 35 ... Individual electrode 36 ... Connection electrode 50 ... Displacement element 60 ... Head Frame 65... Opening of head frame 67... Attachment portion of head frame to recording apparatus 72... Second heater

Claims (7)

  A recording apparatus main body having a plurality of liquid ejection heads and a head frame to which the plurality of liquid ejection heads are fixed, a conveyance unit for conveying a recording medium to the liquid ejection head, the plurality of liquid ejection heads and the conveyance The liquid ejection head includes a liquid ejection hole group in which a plurality of liquid ejection holes are arranged long in one direction, and a liquid from each of the plurality of liquid ejection holes. A plurality of liquid pressurizing devices that discharge the liquid, a fixing portion that is provided outside the one-direction end of the liquid discharge hole group, and that fixes the liquid discharge head to the head frame; a first heater; The recording apparatus is characterized in that the head frame includes a second heater, and the control unit controls the first heater and the second heater. .   When the thermal expansion coefficient of the liquid discharge head is larger than the thermal expansion coefficient of the head frame, the control unit controls the temperature of the first heater to be lower than that of the second heater, and the liquid discharge head The control unit controls the temperature of the first heater to be higher than that of the second heater when the coefficient of thermal expansion of the head frame is smaller than that of the head frame. The recording device described. The liquid discharge head has a thermal expansion coefficient of α _H / ° C., the head frame has a thermal expansion coefficient of α _F / ° C., and the liquid discharge head and the head frame are fixed at T ° C., When the recording is performed such that the temperature of the liquid discharge head is set to T _H ° C. by the first heater, the control unit moves the head frame to α _F (T _F −T) = α by the second heater. The recording apparatus according to claim 1, wherein the recording apparatus is controlled to have a temperature T _F ° C. that satisfies _H (T _H −T). The head frame includes a cooling unit using a thermoelectric conversion element, and the control unit controls the temperature of the head frame to be T _F ° C by the cooling unit. The recording device described.   The liquid ejection head is disposed so that the liquid ejection hole group is continuous when viewed from the conveyance direction in which the conveyance unit conveys the recording medium to the liquid ejection head, and the head frame is 5. The recording apparatus according to claim 1, wherein the second heater is continuously provided in a range of the liquid discharge head as viewed from a direction.   The recording apparatus according to claim 1, wherein the head frame has a flat plate shape, and the second heater is provided symmetrically on the upper and lower surfaces of the head frame.   The recording apparatus according to claim 1, wherein the head frame has a flat plate shape, and the second heater is provided between upper and lower surfaces of the head frame.

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