JP6034207B2 - Liquid discharge head and recording apparatus - Google Patents

Description

  The present invention relates to a liquid discharge head that discharges droplets and a recording apparatus.

  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, such a liquid ejection head has a serial type that performs recording while moving the liquid ejection head in a direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) of the recording medium, and is long in 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 the liquid discharge head 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.

  Therefore, a long liquid discharge head in one direction is provided so as to cover the pressure chamber and a flow path member having discharge holes that connect the manifold and the manifold through a plurality of pressure chambers, respectively, as a common flow path. In addition, an actuator unit that includes a plurality of actuator units having a plurality of displacement elements is known (see, for example, Patent Document 1). In this liquid ejection head, pressurization chambers connected to a plurality of ejection holes are arranged in a matrix, and the displacement element of the actuator unit provided so as to cover it is displaced to eject ink from each ejection hole. Thus, printing is possible at a resolution of 600 dpi in the main scanning direction.

  In addition, a technique for circulating ink to be ejected to a liquid ejection head is known (see, for example, Patent Document 2).

JP 2003-305852 A JP 2008-254196 A

  Circulating the liquid to be discharged into the flow path including the liquid discharge head can be achieved by flowing a temperature-adjusted liquid so that the temperature of the liquid discharge head can be kept constant, or liquid that tends to settle or volatilize. In use, the liquid state in the liquid discharge head can be easily maintained constant. Assuming that the liquid discharge head main body that discharges the liquid is provided with a reservoir, if the reservoir is provided so as to overlap the head main body, the temperature of the head main body can be easily kept constant.

  However, on the side of the reservoir that does not face the liquid discharge head body, heat is radiated from the reservoir to the outside, so that it is difficult to maintain the temperature. As a result, there is a problem that it is difficult to maintain the temperature of the liquid discharge head body.

  Accordingly, an object of the present invention is to provide a liquid discharge head and a recording apparatus that can easily maintain the temperature of the liquid discharge head main body.

The liquid discharge head of the present invention is a liquid discharge head including a flat plate-shaped liquid discharge head body that is long in one direction and a flat plate-shaped reservoir that is laminated in the liquid discharge head body, and is long in the one direction. the liquid ejecting head main body, a common channel which the liquid flows to be discharged, are connected respectively with said common channel, includes a first opening and a second opening, said reservoir, said one direction A first reservoir channel connected to the first opening, and a second reservoir flow arranged along the one direction and connected to the second opening. The first and second reservoir channels are arranged so as to overlap in order of the first reservoir channel and the second reservoir channel from the liquid discharge head main body side. The first Flow path resistance of the reservoir flow path, the second much larger than the flow path resistance of the reservoir flow path, the first reservoir passage comprises a first damper, the second reservoir passage A second damper having a smaller compliance than the first damper is provided .
The liquid discharge head of the present invention is a liquid discharge head including a flat plate-like long liquid discharge head main body, and a flat plate-like long reservoir in one direction laminated on the liquid discharge head main body. The liquid discharge head main body includes a common flow path through which liquid to be discharged flows, and a first opening and a second opening connected to the common flow path, respectively, A first reservoir channel arranged along one direction and connected to the first opening, and a second reservoir channel arranged along the one direction and connected to the second opening. A reservoir channel, and the first and second reservoir channels are arranged so as to overlap in order of the first reservoir channel and the second reservoir channel from the liquid discharge head main body side. Before and The flow path resistance of the first reservoir flow path is greater than the flow path resistance of the second reservoir flow path, the first reservoir flow path includes a first damper, and the second reservoir flow The road includes a second damper having a smaller compliance than the first damper.
The liquid discharge head of the present invention is a liquid discharge head including a flat plate-like long liquid discharge head main body, and a flat plate-like long reservoir in one direction laminated on the liquid discharge head main body. The liquid discharge head main body includes a common flow path through which liquid to be discharged flows, and a first opening and a second opening connected to the common flow path, respectively, A first reservoir channel arranged along one direction and connected to the first opening, and a second reservoir channel arranged along the one direction and connected to the second opening. A reservoir channel, and the first and second reservoir channels are arranged so as to overlap in order of the first reservoir channel and the second reservoir channel from the liquid discharge head main body side. Before and The flow path resistance of the first reservoir flow path is larger than the flow path resistance of the second reservoir flow path, and the one-way direction is between the first reservoir flow path and the second reservoir flow path. A damper chamber is disposed along at least one of a portion between the damper chamber and the first reservoir flow path, and a portion between the damper chamber and the second reservoir flow path, It is a deformable damper.

  In addition, the recording apparatus of the present invention sends the liquid discharge head, a transport unit that transports a recording medium to the liquid discharge head, the liquid to be discharged to the first reservoir flow path, and one of the liquids. A liquid circulation mechanism for collecting the portion from the second reservoir flow path, and a control unit for controlling the liquid discharge head.

  According to the liquid discharge head of the present invention, the liquid discharged from the first reservoir channel side is supplied and used so as to be recovered from the second reservoir channel. Since the side not facing the discharge head overlaps the second reservoir flow path, the heat transfer between the first reservoir flow path and the outside can be suppressed, and the liquid discharge head main body can be passed through the first reservoir flow path. Therefore, it is easy to maintain the temperature of the liquid flowing in the liquid discharge head body.

  According to the recording apparatus of the present invention, the side of the first reservoir channel that does not face the liquid ejection head overlaps the second reservoir channel, so that the first reservoir channel and the outside are Heat can be prevented from entering and exiting, and the temperature of the liquid sent to the liquid discharge head body through the first reservoir channel can be easily maintained. Therefore, the temperature of the liquid flowing to the liquid discharge head body can be easily maintained.

1 is a schematic configuration diagram of a color inkjet printer that is a recording apparatus including a liquid ejection head according to an embodiment of the present invention. FIG. 2 is a plan view of 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. 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. (A) is a longitudinal cross-sectional view of the liquid discharge head of FIG. 1, (b) and (c) are plan views of the plate used in (a), and (d) shows the present invention. FIG. 10 is a plan view of a plate used in place of the plate of (c) in another liquid discharge head.

  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. This color inkjet printer 1 (hereinafter referred to as printer 1) has four liquid ejection heads 2. These liquid discharge heads 2 are arranged along the conveyance direction of the printing paper P, and the liquid discharge heads 2 fixed to the printer 1 have an elongated shape extending in the direction from the front to the back in FIG. ing. This long direction is sometimes called the longitudinal direction.

  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 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 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 liquid discharge head 2 has a head body 2a at the lower end. The lower surface of the head body 2a is a discharge hole surface 4-1, which is a first main surface, provided with a large number of discharge holes for discharging liquid.

  Liquid droplets (ink) of the same color are ejected from the liquid ejection holes 8 provided in one liquid ejection head 2. Each liquid discharge head 2 is supplied with liquid from an external liquid tank (not shown). The liquid discharge holes 8 of each liquid discharge head 2 are opened in the discharge hole surface 4-1, and are in one direction (a direction parallel to the print paper P and perpendicular to the transport direction of the print paper P). In this case, printing can be performed without gaps in one direction. The colors of the liquid ejected from each liquid ejection head 2 are, for example, magenta (M), yellow (Y), cyan (C), and black (K), respectively. Each liquid discharge head 2 is arranged with a slight gap between the discharge hole surface 4-1, which is 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 2 a 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.

  In addition, the printer 1 has a circulation mechanism that supplies liquid to be discharged to the liquid discharge head 2 and collects liquid that has not been discharged. If the liquid is transferred by a pump or the like and circulated, and the liquid to be transferred is heated or cooled by the temperature control unit, the temperature of the liquid discharge head 2 can be stabilized.

  Next, the liquid discharge head 2 of the present invention will be described. FIG. 2 is a plan view of the head main body 2a. FIG. 3 is an enlarged view of the region surrounded by the alternate long and short dash line in FIG. 2, and is a plan view in which some of the flow paths are omitted for explanation. FIG. 4 is an enlarged view of a region surrounded by a one-dot chain line in FIG. 2, and is a diagram in which a part of the flow paths different from FIG. In FIGS. 3 and 4, for easy understanding of the drawings, the squeeze 6, the discharge hole 8, the pressurizing chamber 10, etc., which are to be drawn by broken lines below the piezoelectric actuator substrate 21, are drawn by solid lines. Further, the discharge hole 8 in FIG. 4 is drawn larger than the actual diameter for easy understanding of the position. FIG. 5 is a longitudinal sectional view of the head main body 2a taken along line VV in FIG. 6A is a longitudinal cross-sectional view of the liquid discharge head of FIG. 1, and FIGS. 6B and 6C are views of the upper side of some plates used in FIG. 6A (plate 40a). It is the top view seen from the side. FIG. 6D is a plan view seen from above the plate 240f used in place of the plate 40f in FIG. 6C in another liquid discharge head of the present invention. 6 (b) to (c) are not strictly the openings 41a of the first reservoir channel and the openings 42a of the second reservoir channel, The same code | symbol was attached | subjected as a site | part connected.

  The liquid discharge head 2 includes a head main body (liquid discharge head main body) 2a, a reservoir 40, and a metal casing 90. Both the head main body 2a and the reservoir 40 are long in one direction and are joined to each other. Also. The head body 2 a includes a flow path member 4 and a piezoelectric actuator substrate 21 in which a displacement element (pressurizing unit) 30 is formed. Further, the reservoir 40 includes a first reservoir channel 41 and a second reservoir channel 42.

  The flow path member 4 constituting the head main body 2a includes a manifold (common flow path) 5, a plurality of pressure chambers 10 connected to the manifold 5, and a plurality of discharge holes connected to the plurality of pressure chambers 10, respectively. 8, the pressurizing chamber 10 is opened on the upper surface of the flow path member 4, and the upper surface of the flow path member 4 is a pressurizing chamber surface 4-2. Further, on the upper surface of the flow path member 4, a first opening 5 a-1 and a second opening 5 a-2 connected to the manifold 5 are opened at both ends in the longitudinal direction of the head main end. Part of the liquid supplied from the first reservoir flow path of the reservoir 40 via the first opening 5a-1 is discharged from the discharge hole 8, and the rest of the liquid is supplied via the second opening 5a-2. Toward the second reservoir channel 42.

A piezoelectric actuator substrate 21 including a displacement element 30 is bonded to the upper surface of the flow path member 4, and each displacement element 30 is provided so as to be positioned on the pressurizing chamber 10. In addition, a signal transmission unit 92 such as an FPC (Flexible Printed Circuit) for supplying a signal to each displacement element 30 is connected to the piezoelectric actuator substrate 21. In FIG. 2, the outline of the vicinity of the signal transmission unit 92 connected to the piezoelectric actuator 21 is indicated by a dotted line so that the two signal transmission units 92 are connected to the piezoelectric actuator substrate 21. In the region of the signal transmission portion 92 facing the piezoelectric actuator substrate 21, a large number of wires are arranged along the short direction of the head main body 2a, and the left and right portions of FIG. It is connected. The signal sent from the control unit 100 passes through another circuit board or the like as necessary, is transmitted to the signal transmission unit 92, and is supplied to the displacement element 30. On the piezoelectric actuator substrate 21 side of the wiring is an electrode electrically connected to the piezoelectric actuator 21, and this electrode is disposed in a rectangular shape at the end of the signal transmission unit 92. This electrode is electrically connected to the individual electrode 25 of the displacement element 30 via a connection electrode 26 which is a bump of conductive resin. The two signal transmission portions 92 are connected so that their ends come to the center portion in the short direction of the piezoelectric actuator substrate 21. The two signal transmission portions 92 extend from the central portion toward the long side of the piezoelectric actuator substrate 21.

  In addition, a driver IC is mounted on the signal transmission unit 92. The driver IC is mounted so as to be pressed against the metal casing, and the heat of the driver IC is transmitted to the metal casing and dissipated to the outside. A drive signal for driving the displacement element 30 on the piezoelectric actuator substrate 21 is generated in the driver IC. A signal for controlling the generation of the drive signal is generated by the control unit 100 and input from the end of the signal transmission unit 92 opposite to the side connected to the piezoelectric actuator substrate 21. A circuit board or the like is provided in the liquid ejection head 2 between the control unit 100 and the signal transmission unit 92 as necessary.

  The reservoir 40 is arranged so as to sandwich the piezoelectric actuator substrate 21 between the head main body 2a and straddle the piezoelectric actuator substrate 21 in the longitudinal direction of the head main body 2a. The reservoir 40 is provided with a first reservoir channel 41 and a second reservoir along the longitudinal direction. The reservoir 40 is stacked on the head body 2a, and the first reservoir channel 41 and the second reservoir channel 42 are the first reservoir channel 41 and the second reservoir channel from the head body 2a side. 42 are arranged so as to overlap in the order of 42.

  The liquid ejected by the liquid ejection head 2 first enters the first reservoir channel 41, then enters the head body 2a and is partially ejected, then enters the second reservoir channel 42, and then externally. Get out. Since the second reservoir channel 42 is disposed on the opposite side of the first reservoir channel 41 from the head main body 2a, the temperature of the liquid in the first reservoir channel 41 affects the influence of the external environment. Since it is difficult to receive, it is easy to keep the temperature of the liquid flowing into the head body 2a constant.

  Further, if the temperature is adjusted by providing a heater so as to face the first reservoir channel 41, the temperature can be controlled in a state where it is hardly affected by the outside, so that the temperature stability of the liquid sent to the head body 2a can be improved. Can be higher.

  A more detailed flow of liquid follows. The liquid supplied from the outside first enters the first reservoir channel 41 through the opening 41a of the first reservoir channel provided at one end of the reservoir 40 in the longitudinal direction. The liquid travels from one end of the reservoir 40 to the other end in the first reservoir channel body 41 b of the first reservoir channel 41. The other end of the first reservoir channel body 41 b is connected to a first (reservoir channel) connection channel 41 c that is a part of the first reservoir channel 41. The first connection channel 41c faces the head body 2a (lower side) and is connected to the first opening 5a-1 on the other end side of the joint portion between the reservoir 40 and the head body 2a. In the manifold 5 of the head main body 2a, the amount of liquid discharged is reduced from the other end with the first opening 5a-1 toward the one end with the second opening 5a-2 while reducing the amount.

  The second opening 5a-2 on one end side of the joint portion between the reservoir 40 and the head body 2a is a second (reservoir channel) connection channel 42c that is a part of the second reservoir channel. It is connected to. The second connection channel 42c is directed upward and is connected to the second reservoir channel main body 42b. The liquid is discharged from the opening 42a of the second reservoir channel disposed in the other end of the reservoir 40 toward the other end in the second reservoir channel body 42b from one end to the other end. The first reservoir channel 41 and the second reservoir channel 42 are basically independent and are not connected, but may be connected by a narrow channel so as not to inhibit the main flow described above. .

The first reservoir channel main body 41b and the second reservoir channel main body 42b are portions that are larger in the short direction of the reservoir 40 in the first reservoir channel 41 and the second reservoir channel 42. . The width is preferably ½ or more of the width of the reservoir 40 in the short direction, more preferably 2/3 or more. By increasing the volume of the entering liquid as described above, the supply and discharge of the liquid can be stabilized, and the circulation of the liquid as the printer 1 can be stabilized. Further, the first reservoir channel main body 41b and the second reservoir channel main body 42b are overlapped over more than 1/2 of the width in the short direction of the reservoir 40 and more than 2/3. It becomes difficult for heat to escape from the reservoir channel main body 41b to the outside.

  The opening 41a of the first reservoir channel is connected to the lower side of the first reservoir channel body 41a, and the first connection channel 41c is connected to the upper side of the first reservoir channel body 41a. Therefore, while the liquid flows through the first reservoir channel main body 41b, bubbles that may be mixed in the liquid can hardly stay in the first reservoir channel main body 41b. The second connecting channel 42c is connected to the lower side of the second reservoir channel main body 42b, and the opening 41a of the second reservoir channel is connected to the upper side of the second reservoir channel main body 42a. Therefore, while the liquid flows through the second reservoir channel main body 42b, bubbles that may be mixed in the liquid are less likely to remain in the second reservoir channel main body 42b.

  The channel resistance of the first reservoir channel 41 is preferably larger than the channel resistance of the second reservoir channel 42. By doing so, it is possible to prevent the liquid from flowing into the second reservoir channel 42, thereby suppressing the liquid ejection characteristics from being affected by the liquid in the head body 2 a being compressed. The channel resistance is determined by changing the dimensions of the first reservoir channel body 41b and the second reservoir channel body 42b, or by measuring the dimensions of the first reservoir channel opening 41a and the second reservoir channel opening 42a. It can be adjusted by changing For example, the diameter of the opening 42a of the second reservoir channel may be made larger than the diameter of the opening 41a of the first reservoir channel.

  The reservoir 40 is configured by laminating plates 40a to 40g. The plates 40a, b, e and f have a thickness of about 0.5 to 10 mm. The three layers of the plate 40e and the plates 40c and e which are damper plates have a thickness of about 0.5 to 2 mm as a whole. Has been. The plates 41a, b, d, f, and g can be formed of metal, resin, or ceramics.

  The plate 40c constituting the lower surface of the first reservoir channel body 41b and the plate 40e constituting the upper surface of the second reservoir channel body 42b have a thickness of about 5 to 30 μm and can be deformed. It is a resin plate or a metal plate that has been subjected to grooving and is easily deformed. The surface opposite to the reservoir flow path of those portions faces the damper chamber 46, and the first damper 45-1 and the second damper that can change the volume of the reservoir flow path. It is a damper 45-2. Either one of the dampers may be used, but by providing both, the influence from the outside can be made less susceptible. Further, since the damper chamber 46 is provided between the first reservoir channel body 41b and the second reservoir channel body 42b, the thermal conductivity of the air is low. The liquid can be made less susceptible to external temperature. Furthermore, even if the dampers are provided on both sides, the damper chamber 46 can be shared, so that the size of the liquid discharge head 2 can be reduced. Note that unlike the present embodiment, it is not necessary to damper the entire upper surface of the first reservoir channel body 41b and the lower surface of the second reservoir channel body 42b, but if so, the capacity of the damper is increased. Can be big.

If the compliance of the second damper 45-2 is larger than the compliance of the first damper 45-1, when the liquid supply from the outside becomes excessive, the second damper 45-2 is deformed and the second damper 45-2 deforms. When the change in the volume of the reservoir channel 42 becomes larger than the change in the volume of the first reservoir channel 41 by the first damper 45-1, a liquid flow is generated in the manifold 5 and formed in the discharge hole 8. Affects the liquid meniscus. By making the compliance of the second damper 45-2 smaller than the compliance of the first damper 45-1, the steadiness of the liquid flow in the manifold 5 can be increased, and the meniscus can be stabilized. Thereby, it is possible to reduce the ejection failure due to the destruction of the meniscus and the variation in ejection characteristics caused by the meniscus being displaced from the steady position.

  The head main body 2 a has one piezoelectric actuator substrate 21 including a flat plate-like channel member 4 and a displacement element 30 joined on the channel member 4. The planar shape of the piezoelectric actuator substrate 21 is a rectangular shape, and the piezoelectric actuator substrate 21 is disposed on the pressurizing chamber surface 4-2 that is the upper surface of the flow path member 4 so that the long side of the rectangle is along the longitudinal direction of the flow path member 4. .

  Two manifolds 5 are formed inside the flow path member 4. The manifold 5 has an elongated shape that extends from one end side in the longitudinal direction of the flow path member 4 to the other end side, and the manifold opening 5a that opens to the upper surface of the flow path member 4 at both ends. Is formed.

  The manifold 5 has at least a central portion in the longitudinal direction, which is a region connected to the pressurizing chamber 10, partitioned by a partition wall 15 provided at an interval in the lateral direction. The partition wall 15 has the same height as the manifold 5 in the central portion in the longitudinal direction, which is an area connected to the pressurizing chamber 10, and completely partitions the manifold 5 into a plurality of sub-manifolds 5b. By doing so, it is possible to provide the discharge hole 8 and a descender connected from the discharge hole 8 to the pressurizing chamber 10 so as to overlap with the partition wall 15 when seen in a plan view.

  In FIG. 2, the whole of the manifold 5 excluding both ends is partitioned by a partition wall 15. In addition to this, one of the both end portions other than one end portion may be partitioned by the partition wall 15. In addition, only the vicinity of the opening 5a opened on the upper surface of the flow path member 4 is not partitioned, and a partition wall may be provided in the depth direction of the flow path member 4 from the opening 5a.

  The portion of the manifold 5 divided into a plurality of parts may be referred to as a sub-manifold 5b. In the present embodiment, two manifolds 5 are provided independently, and openings 5a are provided at both ends. One manifold 5 is provided with seven partition walls 15 and divided into eight sub-manifolds 5b. The width of the sub-manifold 5b is larger than the width of the partition wall 15, so that a large amount of liquid can flow through the sub-manifold 5b. In addition, the length of the seven partition walls 15 becomes longer as it is closer to the center in the short direction, and the end of the partition wall 15 is closer to the end of the manifold 5 as the partition wall 15 is closer to the center in the short direction at both ends of the manifold 5. Near the edge. As a result, the flow resistance generated by the outer wall of the manifold 5 and the flow resistance generated by the partition wall 15 are balanced, and the individual supply flow that is the portion connected to the pressurizing chamber 10 in each sub-manifold 5b. The pressure difference of the liquid at the end of the region where the channel 14 is formed can be reduced. Since the pressure difference in the individual supply channel 14 leads to a pressure difference applied to the liquid in the pressurizing chamber 10, the discharge variation can be reduced if the pressure difference in the individual supply channel 14 is reduced.

  The flow path member 4 is formed by two-dimensionally expanding a plurality of pressurizing chambers 10. The pressurizing chamber 10 is a hollow region having a substantially rhombic planar shape having two acute angle portions and two acute angle portions with rounded corners.

  The pressurizing chamber 10 is connected to one sub-manifold 5b through an individual supply channel 14. Along with one sub-manifold 5b, pressurizing chamber rows 11 that are columns of pressurizing chambers 10 connected to the sub-manifold 5b are provided in two columns, one on each side of the sub-manifold 5b. Yes. Accordingly, 16 columns of pressurizing chambers 11 are provided for one manifold 5, and 32 columns of pressurizing chamber rows 11 are provided in the entire head body 2a. The intervals in the longitudinal direction of the pressurizing chambers 10 in the respective pressurizing chamber rows 11 are the same, for example, 37.5 dpi.

  A dummy pressurizing chamber 16 is provided at the end of each pressurizing chamber row 11. The dummy pressurizing chamber 16 is connected to the manifold 5 but is not connected to the discharge hole 8. A dummy pressurizing chamber row in which dummy pressurizing chambers 16 are arranged in a straight line is provided outside the 32 columns of pressurizing chamber rows 11. The dummy pressurizing chamber 16 is not connected to either the manifold 5 or the discharge hole 8. By these dummy pressurizing chambers 16, the structure (rigidity) around the pressurizing chamber 10 one inner side from the end is close to the structure (rigidity) of the other pressurizing chambers 10, so that the difference in liquid ejection characteristics can be reduced. Less. In addition, since the influence of the surrounding structure difference has a great influence on the pressurizing chambers 10 adjacent to each other in the longitudinal direction, the dummy pressurizing chambers 16 are provided at both ends in the longitudinal direction. Since the influence on the short side direction is relatively small, it is provided only on the side closer to the end of the head main body 21a. Thereby, the width | variety of the head main body 21a can be made small.

  The pressurizing chambers 10 connected to one manifold 5 are arranged at substantially equal intervals on the rows and on the columns along the row direction which is the longitudinal direction of the liquid discharge head 2 and the column direction which is the short direction. Is arranged. The row direction is a direction along a diagonal line that connects the obtuse angle portions of the rhombus-shaped pressurizing chamber 10, and is also a direction formed by connecting the area centers of gravity of the pressurizing chambers 10 that are arranged with the obtuse angle portions facing each other. The rhombus shape of the pressurizing chamber 10 may have a side length different by about 10%. In addition, the direction of the diagonal line connecting the obtuse angle portions and the row direction have an angle of about 10 degrees or less because the pressurizing chamber 10 is arranged in a state of being rotated in a plane or the length of the side is different. May be. The column direction is a direction along a diagonal line connecting the acute angle portions of the rhombus-shaped pressurizing chambers 10, and is also a direction formed by connecting the area centroids of the pressurizing chambers 10 arranged with the acute angle portions facing each other. Even if the direction of the diagonal line connecting the acute angle portions and the column direction are arranged in a state where the pressurizing chamber 10 is rotated in a plane or the length of the sides is different, the angle is about 10 degrees or less. Good. That is, the angle formed by the rhombic diagonal lines of the pressurizing chamber 10 with respect to the row direction and the column direction is small. By arranging the pressurizing chambers 10 in a lattice shape and arranging the rhombic pressurizing chambers 10 having such angles, crosstalk can be reduced. This is because the corners face each other in both the row direction and the column direction with respect to one pressurizing chamber 10, so that the flow path member is more than the case where the sides face each other. This is because vibration is difficult to be transmitted through 4. Here, by making the obtuse angled portions face each other in the longitudinal direction, the pressurizing chamber 10 in the longitudinal direction can be arranged with a high density, thereby increasing the density of the discharge holes 8 in the longitudinal direction, and high resolution. The liquid discharge head 2 can be obtained. If the intervals between the pressurizing chambers 10 on the rows and columns are equal, the crosstalk can be reduced by eliminating the narrower intervals than others, but the intervals may differ by about ± 20%.

  When the pressurizing chambers 10 are arranged in a lattice shape and the piezoelectric actuator 21 is formed in a rectangular shape having outer sides along rows and columns, the piezoelectric actuator substrate 21 is formed on the pressurizing chamber 10 from the outer sides. Since the individual electrodes 25 are arranged at an equal distance, the piezoelectric actuator substrate 21 can be hardly deformed when the individual electrodes 25 are formed. When the piezoelectric actuator substrate 21 and the flow path member 4 are joined, if this deformation is large, stress may be applied to the displacement element 30 near the outer side, resulting in variations in displacement characteristics. However, by reducing the deformation, The variation can be reduced. In addition, since the dummy pressurizing chamber row of the dummy pressurizing chamber 16 is provided outside the pressurizing chamber row 11 closest to the outer side, the influence of deformation can be made less susceptible. The pressurizing chambers 10 belonging to the pressurizing chamber row 11 are arranged at equal intervals, and the individual electrodes 25 corresponding to the pressurizing chamber rows 11 are also arranged at equal intervals. The pressurizing chamber rows 11 are arranged at equal intervals in the short direction, and the columns of the individual electrodes 25 corresponding to the pressurizing chamber rows 11 are also arranged at equal intervals in the short direction. Thereby, it is possible to eliminate a portion where the influence of the crosstalk becomes particularly large.

When the flow path member 4 is viewed in plan, the pressurizing chamber 10 belonging to one pressurizing chamber row 11 is overlapped with the pressurizing chamber 10 belonging to the adjacent pressurizing chamber row 11 in the longitudinal direction of the liquid ejection head 2. By arranging so as not to become crosstalk, crosstalk can be suppressed. On the other hand, if the distance between the pressurizing chamber rows 11 is increased, the width of the liquid discharge head 2 is increased, so that the liquid discharge head 2 for the printer 1 is increased.
The influence of the accuracy of the installation angle and the accuracy of the relative position of the liquid ejection head 2 when using a plurality of liquid ejection heads 2 on the printing result is increased. Therefore, by making the width of the partition wall 15 smaller than that of the sub-manifold 5b, the influence of the accuracy on the printing result can be reduced.

  The pressurizing chambers 10 connected to one sub-manifold 5 b constitute two pressurizing chamber rows 11, and the discharge holes 8 connected to the pressurizing chambers 10 belonging to one pressurizing chamber row 11 are One discharge hole row 9 is configured. The discharge holes 8 connected to the pressurizing chambers 10 belonging to the two pressurizing chamber rows 11 open to different sides of the sub-manifold 5b. In FIG. 4, the partition wall 15 is provided with two rows of discharge hole rows 9, but the discharge holes 8 belonging to the respective discharge hole rows 9 are connected to the sub-manifold 5 b on the side close to the discharge holes 8 in the pressurizing chamber 10. Are connected through. When the discharge hole 8 connected to the adjacent sub-manifold 5b via the pressurizing chamber row 11 and the liquid discharge head 2 are arranged so as not to overlap in the longitudinal direction, the pressurizing chamber 10 and the discharge hole 8 are connected. Since crosstalk between the flow paths can be suppressed, the crosstalk can be further reduced. If the entire flow path connecting the pressurizing chamber 10 and the discharge hole 8 is arranged so as not to overlap in the longitudinal direction of the liquid discharge head 2, the crosstalk can be further reduced.

  In addition, the width of the liquid discharge head 2 can be reduced by arranging the pressurizing chamber 10 and the sub-manifold 5b so as to overlap each other in plan view. When the ratio of the overlapping area to the area of the pressurizing chamber 10 is 80% or more, and further 90% or more, the width of the liquid discharge head 2 can be further reduced. Further, the bottom surface of the pressurizing chamber 10 where the pressurizing chamber 10 and the sub-manifold 5b overlap is less rigid than the case where the pressurizing chamber 10 and the sub-manifold 5b do not overlap. There is a risk of variation. By making the ratio of the area of the pressurizing chamber 10 overlapping the sub-manifold 5b to the area of the entire pressurizing chamber 10 substantially the same in each pressurizing chamber 10, the rigidity of the bottom surface constituting the pressurizing chamber 10 is increased. Variations in ejection characteristics due to changes can be reduced. Here, “substantially the same” means that the difference in area ratio is 10% or less, particularly 5% or less.

  A plurality of pressurizing chambers are formed by a plurality of pressurizing chambers 10 connected to one manifold 5. Since there are two manifolds 5, there are two pressurizing chamber groups. The arrangement of the pressurizing chambers 10 related to ejection in each pressurizing chamber group is the same, and is arranged to be translated in the lateral direction. These pressurizing chambers 10 are arranged over almost the entire surface although there are portions where the gaps between the pressurizing chamber groups are slightly wide in the region facing the piezoelectric actuator substrate 21 on the upper surface of the flow path member 4. . That is, the pressurizing chamber group formed by these pressurizing chambers 10 occupies an area having almost the same size and shape as the piezoelectric actuator substrate 21. Further, the opening of each pressurizing chamber 10 is closed by bonding the piezoelectric actuator substrate 21 to the upper surface of the flow path member 4.

  A descender connected to the discharge hole 8 opened in the discharge hole surface 4-1 on the lower surface of the flow path member 4 extends from a corner portion of the pressurizing chamber 10 facing the corner portion where the individual supply flow path 14 is connected. ing. The descender extends in a direction away from the pressurizing chamber 10 in plan view. More specifically, the pressurizing chamber 10 extends away from the direction along the long diagonal line while being shifted to the left and right with respect to that direction. As a result, the discharge chambers 8 can be arranged at intervals of 1200 dpi as a whole, while the pressurization chambers 10 are arranged in a lattice pattern in which the intervals within the pressurization chamber rows 11 are 37.5 dpi.

In other words, when the discharge holes 8 are projected so as to be orthogonal to the virtual straight line parallel to the longitudinal direction of the flow path member 4, each manifold 5 is within the range of R of the virtual straight line shown in FIG. That is, 16 discharge holes 8 connected to, and a total of 32 discharge holes 8 are equally spaced by 1200 dpi. Thus, by supplying the same color ink to all the manifolds 5, an image can be formed with a resolution of 1200 dpi in the longitudinal direction as a whole.
Further, one discharge hole 8 connected to one manifold 5 is equally spaced at 600 dpi within the range of R of the imaginary straight line. As a result, by supplying different colors of ink to the respective manifolds 5, it is possible to form two-color images with a resolution of 600 dpi in the longitudinal direction as a whole. In this case, if two liquid ejection heads 2 are used, an image of four colors can be formed at a resolution of 600 dpi, and printing accuracy is higher and printing settings are easier than using a liquid ejection head capable of printing at 600 dpi. Can be.

  Individual electrodes 25 are formed at positions facing the pressurizing chambers 10 on the upper surface of the piezoelectric actuator substrate 21. The individual electrode 25 includes an individual electrode main body 25a that is slightly smaller than the pressurizing chamber 10 and has a shape substantially similar to the pressurizing chamber 10, and an extraction electrode 25b that is extracted from the individual electrode main body 25a. In the same manner as the pressurizing chamber 10, the individual electrode 25 constitutes an individual electrode row and an individual electrode group. One end of the extraction electrode 25 b is connected to the individual electrode body 25 a, and the other end passes through the acute angle portion of the pressurizing chamber 10, and outside the pressurizing chamber 10, the two acute angle portions 10 a of the pressurizing chamber 10. It is drawn out to the area which does not overlap with the extended line of the diagonal line connecting. Thereby, crosstalk can be reduced.

  Further, on the upper surface (corresponding to the second main surface 21a-1) of the piezoelectric actuator substrate 21, a common electrode surface electrode 28 electrically connected to the common electrode 24 through a via hole is formed. The common electrode surface electrodes 28 are formed in two rows along the longitudinal direction at the central portion of the piezoelectric actuator substrate 21 in the lateral direction, and are formed in one row along the lateral direction near the end in the longitudinal direction. ing. Although the illustrated common electrode surface electrode 28 is intermittently formed on a straight line, it may be formed continuously on a straight line.

  The piezoelectric actuator substrate 21 is formed by laminating and firing a piezoelectric ceramic layer 21a having a via hole, a common electrode 24, and a piezoelectric ceramic layer 21b, as will be described later, and then forming individual electrodes 25 and a common electrode surface electrode 28 in the same process. It is preferable to do this. The positional variation between the individual electrode 25 and the pressurizing chamber 10 greatly affects the ejection characteristics, and if the individual electrode 25 is formed and then fired, the piezoelectric actuator substrate 21 may be warped. When the substrate 21 is joined to the flow path member 4, stress is applied to the piezoelectric actuator substrate 21, and the displacement may vary due to the influence. Therefore, the individual electrode 25 is formed after firing. Similarly, the surface electrode 28 for the common electrode may be warped, and if the surface electrode 28 is formed at the same time as the individual electrode 25, the positional accuracy becomes higher and the process can be simplified. The surface electrode 28 is formed in the same process.

  Such a positional variation of via holes due to firing shrinkage that may occur when firing the piezoelectric actuator substrate 21 mainly occurs in the longitudinal direction of the piezoelectric actuator substrate 21, and therefore, a manifold having an even number of common electrode surface electrodes 28. 5, in other words, it is provided at the center in the short direction of the piezoelectric actuator substrate 21, and the common electrode surface electrode 28 has a long shape in the longitudinal direction of the piezoelectric actuator substrate 21. In addition, it is possible to prevent the via hole and the common electrode surface electrode 28 from being electrically connected due to misalignment.

  Two signal transmission portions 92 are arranged and bonded to the piezoelectric actuator substrate 21 from the two long sides of the piezoelectric actuator substrate 21 toward the center. At this time, the connection is facilitated by forming the connection electrode 26 and the common electrode connection electrode on the extraction electrode 25b and the common electrode surface electrode 28 of the piezoelectric actuator substrate 21a, respectively, and connecting them. At this time, if the area of the common electrode surface electrode 28 and the common electrode connection electrode is made larger than the area of the connection electrode 26, the end of the signal transmission unit 92 (the end of the piezoelectric actuator substrate 21 in the longitudinal direction) ) Can be made stronger by the connection on the common electrode surface electrode 28, so that the signal transmission portion 92 can be made difficult to peel off from the end.

  Further, the discharge hole 8 is arranged at a position avoiding the area facing the manifold 5 arranged on the lower surface side of the flow path member 4. Further, the discharge hole 8 is disposed in a region facing the piezoelectric actuator substrate 21 on the lower surface side of the flow path member 4. These discharge holes 8 occupy a region having almost the same size and shape as the piezoelectric actuator substrate 21 as a group, and the displacement elements 30 of the corresponding piezoelectric actuator substrate 21 are displaced to displace the discharge holes 8 from the discharge holes 8. Droplets can be ejected.

  The flow path member 4 included in the head main body 2a has a laminated structure in which a plurality of plates are laminated. These plates are a cavity plate 4a, a base plate 4b, an aperture plate 4c, a supply plate 4d, manifold plates 4e to j, a cover plate 4k, and a nozzle plate 4l in order from the upper surface of the flow path member 4. A number of holes are formed in these plates. Since the thickness of each plate is about 10 to 300 μm, the formation accuracy of the holes to be formed can be increased. Each plate is aligned and laminated so that these holes communicate with each other to form the individual flow path 12 and the manifold 5. In the head main body 2a, the pressurizing chamber 10 is on the upper surface of the flow path member 4, the manifold 5 is on the inner lower surface side, the discharge holes 8 are on the lower surface, and the parts constituting the individual flow path 12 are close to each other in different positions. The manifold 5 and the discharge hole 8 are connected via the pressurizing chamber 10.

  The holes formed in each plate will be described. These holes include the following. The first is the pressurizing chamber 10 formed in the cavity plate 4a. Second, there is a communication hole that constitutes an individual supply channel 14 that is connected from one end of the pressurizing chamber 10 to the manifold 5. This communication hole is formed in each plate from the base plate 4b (specifically, the inlet of the pressurizing chamber 10) to the supply plate 4c (specifically, the outlet of the manifold 5). The individual supply flow path 14 includes a squeeze 6 that is formed in the aperture plate 4c and is a portion where the cross-sectional area of the flow path is small.

  Third, there is a communication hole constituting a flow path communicating from the other end of the pressurizing chamber 10 to the discharge hole 8, and this communication hole is referred to as a descender (partial flow path) in the following description. The descender is formed on each plate from the base plate 4b (specifically, the outlet of the pressurizing chamber 10) to the nozzle plate 4l (specifically, the discharge hole 8). The hole of the nozzle plate 41 is opened as a discharge hole 8 having a diameter of 10 to 40 μm, for example, which is open to the outside of the flow path member 4, and the diameter increases toward the inside. . Fourthly, communication holes constituting the manifold 5. The communication holes are formed in the manifold plates 4e to 4j. Holes are formed in the manifold plates 4e to 4j so that the partition walls 15 remain so as to constitute the sub-manifold 5b. The partition 15 in each manifold plate 4e-j cannot be held when the entire portion to be the manifold 5 is made a hole, so the partition 15 is connected to the outer periphery of each manifold plate 4e-j with a half-etched tab. To be.

  The first to fourth communication holes are connected to each other to form an individual flow path 12 from the liquid inflow port (outlet of the manifold 5) to the discharge hole 8 from the manifold 5. The liquid supplied to the manifold 5 is discharged from the discharge hole 8 through the following path. First, from the manifold 5, it enters the individual supply flow path 14 and reaches one end of the throttle 6. Next, it proceeds horizontally along the extending direction of the restriction 6 and reaches the other end of the restriction 6. From there, it reaches one end of the pressurizing chamber 10 upward. Furthermore, it progresses horizontally along the extending direction of the pressurizing chamber 10 and reaches the other end of the pressurizing chamber 10. While moving little by little in the horizontal direction from there, it proceeds mainly downward and proceeds to the discharge hole 8 opened in the lower surface.

The piezoelectric actuator substrate 21 includes two piezoelectric ceramic layers 21a and 21b that are piezoelectric bodies.
It has the laminated structure which consists of. Each of these piezoelectric ceramic layers 21a and 21b has a thickness of about 20 μm. The thickness from the lower surface of the piezoelectric ceramic layer 21a of the piezoelectric actuator substrate 21 to the upper surface of the piezoelectric ceramic layer 21b is about 40 μm. Both of the piezoelectric ceramic layers 21 a and 21 b extend so as to straddle the plurality of pressure chambers 10. These piezoelectric ceramic layers 21a and 21b are made of, for example, a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  The piezoelectric actuator substrate 21 includes a common electrode 24 made of a metal material such as Ag—Pd and an individual electrode 25 made of a metal material such as Au. As described above, the individual electrode 25 includes the individual electrode main body 25a disposed at the position facing the pressurizing chamber 10 on the upper surface of the piezoelectric actuator substrate 21, and the extraction electrode 25b extracted therefrom. A connection electrode 26 is formed at a portion of one end of the extraction electrode 25 b that is extracted outside the region facing the pressurizing chamber 10. The connection electrode 26 is made of a conductive resin containing silver particles, for example, and has a convex shape with a thickness of about 5 to 100 μm. The connection electrode 26 is electrically joined to an electrode provided in the signal transmission unit 92. Although details will be described later, a drive signal is supplied from the control unit 100 to the individual electrode 25 through the signal transmission unit 92. The drive signal is supplied in a constant cycle in synchronization with the conveyance speed of the print medium P.

  The common electrode 24 is formed over almost the entire surface in the region between the piezoelectric ceramic layer 21a and the piezoelectric ceramic layer 21b. That is, the common electrode 24 extends so as to cover all the pressurizing chambers 10 in the region facing the piezoelectric actuator substrate 21. The thickness of the common electrode 24 is about 2 μm. The common electrode 24 is connected to the common electrode surface electrode 28 formed at a position avoiding the electrode group composed of the individual electrodes 25 on the piezoelectric ceramic layer 21b through a via hole formed in the piezoelectric ceramic layer 21b. Grounded and held at ground potential. The common electrode surface electrode 28 is connected to another electrode on the signal transmission unit 92 in the same manner as the large number of individual electrodes 25.

  As will be described later, when a predetermined drive signal is selectively supplied to the individual electrode 25, the volume of the pressurizing chamber 10 corresponding to the individual electrode 25 changes, and the liquid in the pressurizing chamber 10 is pressurized. Is added. As a result, droplets are discharged from the corresponding liquid discharge ports 8 through the individual flow paths 12. That is, the portion of the piezoelectric actuator substrate 21 that faces each pressurizing chamber 10 corresponds to the individual displacement element 30 corresponding to each pressurizing chamber 10 and the liquid discharge port 8. That is, a displacement element 30, which is a piezoelectric actuator having a unit structure as shown in FIG. 5, is added to each pressurizing chamber 10 in a laminate composed of two piezoelectric ceramic layers 21 a and 21 b. The piezoelectric actuator substrate 21 includes a plurality of displacement elements 30 as pressurizing portions. The diaphragm 21a is located directly above the pressure chamber 10, is formed by a common electrode 24, a piezoelectric ceramic layer 21b, and individual electrodes 25. Yes. In the present embodiment, the amount of liquid ejected from the liquid ejection port 8 by one ejection operation is about 1.5 to 4.5 pl (picoliter).

  The large number of individual electrodes 25 are individually electrically connected to the control unit 100 via the signal transmission unit 92 and wiring so that the potential can be individually controlled. When an electric field is applied to the piezoelectric ceramic layer 21b in the polarization direction by setting the individual electrode 25 to a potential different from that of the common electrode 24, a portion to which the electric field is applied functions as an active portion that is distorted by the piezoelectric effect. In this configuration, when the control unit 100 sets the individual electrode 25 to a predetermined positive or negative potential with respect to the common electrode 24 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 pressurizing chamber 10 (unimorph deformation).

In an actual driving procedure in the present embodiment, the individual electrode 25 is set to a potential higher than the common electrode 24 (hereinafter referred to as a high potential) in advance, and the individual electrode 25 is temporarily set to the same potential as the common electrode 24 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 their original shapes at the timing when the individual electrode 25 becomes low potential, and the volume of the pressurizing chamber 10 increases compared to the initial state (the state where the potentials of both electrodes are different). To do. At this time, a negative pressure is applied to the pressurizing chamber 10 and the liquid is sucked into the pressurizing chamber 10 from the manifold 5 side. After that, at the timing when the individual electrode 25 is set to a high potential again, the piezoelectric ceramic layers 21 a and 21 b are deformed so as to protrude toward the pressurizing chamber 10, and the pressure in the pressurizing chamber 10 is reduced by the volume reduction of the pressurizing chamber 10. The pressure becomes positive and the pressure on the liquid rises, and droplets are ejected. That is, in order to discharge the droplet, a drive signal including a pulse based on a high potential is supplied to the individual electrode 25. The ideal pulse width is AL (Acoustic Length), which is the length of time during which the pressure wave propagates from the orifice 6 to the discharge hole 8. According to this, when the inside of the pressurizing chamber 10 is reversed from the negative pressure state to the positive pressure state, both pressures are combined, and the liquid droplets can be discharged at a stronger pressure.

  In gradation printing, gradation expression is performed by the number of droplets ejected continuously from the 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 designated gradation expression is continuously performed from the discharge holes 8 corresponding to the designated 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 this case, it is considered that the speed of the liquid droplets ejected later increases, but this is preferable because the landing points of a plurality of liquid droplets are close.

  As in the present embodiment, when there are a plurality of manifolds 5 and they are arranged side by side in the direction intersecting the longitudinal direction, that is, in the lateral direction, the first reservoir channel 41 and the second reservoir channel 42 The reservoir channel is preferably branched at the end connected to the manifold 5. By making the branch closer to the manifold 5, the difference in the amount of liquid flowing into the manifold 5 and the pressure difference can be reduced.

  At that time, the first reservoir channel 41 (specifically, the channel from the opening 41a of the first reservoir channel to the first reservoir channel body 41b) is branched to have a plurality of second connection channels 42c. By arranging so as to pass between the two, there is no need to provide a long flow path that bypasses the second connection flow path 42c, and by providing such a flow path, There is no need to increase the length of the direction.

  In this case, the plate 40f shown in FIG. 6C is arranged in the stacking direction from the head body 2a to the second reservoir channel body 42b. That is, the passage from the opening 41a of the first reservoir channel to the first reservoir channel body 41b passes between the plurality of second connection channels 42c facing upward. .

  At this time, if the distance W2 in the short direction of the liquid discharge head 2 between the second connection channels 42c is made larger than the distance W1 in the short direction of the liquid discharge head 2 between the manifolds 5, Since the place where the 1st reservoir flow path 41 passes can be ensured, it is preferable. In order to do so, the manifold 5 should be set so that the distance between the both ends of the head main body 2a extends to W2, and the second connecting flow path 42c is directed directly upward at the position of the end. Good.

  A plate 240f shown in FIG. 6D is a plate used in place of the plate 40f in another liquid discharge head of the present invention. In the other liquid ejection head of the present invention, it is necessary to change the position of the opening of the other plate in accordance with the opening of the flow path formed in the plate 240f. That is, the first opening 5a-1 and the second opening of the head body 2a are shifted by the amount of the position of the portion of the first connection channel 241c and the second connection channel 242c in the stacking direction that is shifted in the stacking direction. The position of the opening 5a-2 is shifted. Moreover, the position of the connection channel of the second connection channel 242c formed in the plates 40b to 40e is also shifted.

  In the plate 240 f, the second connection flow path 242 c is arranged so as to be shifted in the longitudinal direction of the reservoir 40. As a result, a large place where the first reservoir channel 41 passes can be secured. In this case, the first connection channel 241c is also preferably shifted in the longitudinal direction of the reservoir 40 in the same manner as the second connection channel 242c. In this way, the difference in length between the plurality of manifolds 5 can be reduced, and the same length can be obtained.

In addition, a channel 241d connected to the second opening of the first reservoir channel is provided at the end of the first reservoir channel 41 opposite to the (first) opening 41a of the first reservoir channel. May be. The second opening of the first reservoir channel opens to the outside at a position immediately above the right end of the channel 241d connected to the second opening of the first reservoir channel in FIG. Further, the channel 241d connected to the second opening of the first reservoir channel is connected to the upper side of the first reservoir channel body 41b. When liquid is first put into the liquid discharge head 2, if a part of the liquid is removed from the second opening of the first reservoir flow path, bubbles that may be mixed with liquid can hardly be directed to the head body 2a. Therefore, it is preferable. In that case, it is preferable that the first connection channel 241 c be arranged so as to be connected to the lower side of the first reservoir channel 41. Note that the second opening of the first reservoir channel is closed after the introduction of the liquid is completed. The second opening of the first reservoir channel is kept closed during regular use of the liquid ejection head 2, but is discharged when bubbles accumulate in the first reservoir channel 41. It may be used for

DESCRIPTION OF SYMBOLS 1 ... Printer 2 ... Liquid discharge head 2a ... (Liquid discharge) Head main body 4 ... Channel member 4a-l ... (Channel member) plate 4-1 ... Discharge hole Surface 4-2 ... Pressure chamber surface 5 ... Manifold (common flow path)
5a ... (manifold) opening 5a-1 ... first opening 5a-2 ... second opening 5b ... sub-manifold 6 ... squeezing 8 ... discharge hole 9 ... Discharge hole row 10 ... Pressure chamber 11 ... Pressure chamber row 12 ... Individual channel 14 ... Individual supply channel 15 ... Partition wall 21 ... Piezoelectric actuator substrate 21a ... Piezoelectric Ceramic layer (diaphragm)
21b ... Piezoelectric ceramic layer 24 ... Common electrode 25 ... Individual electrode 25a ... Individual electrode body 25b ... Extraction electrode 30 ... Displacement element (pressure part)
40 ... reservoirs 40a-g, 240f ... (reservoir) plate 41c, e ... (damper) plate 41 ... first reservoir channel 41a ... (first reservoir channel) 1st) opening 41b ... 1st reservoir channel body 41c, 241c ... 1st (reservoir channel) connection channel 241d ... 2nd opening of 1st reservoir channel Connected flow path 42... First reservoir flow path 42 a... Second reservoir flow path opening 42 b... Second reservoir flow path body 42 c, 242 c. ) Connection flow path 45-1 ... first damper 45-2 ... second damper 46 ... damper chamber

Claims (10)

A liquid discharge head main body that is flat and long in one direction, and a liquid discharge head that is stacked on the liquid discharge head main body and includes a reservoir that is flat and long in the one direction;
The liquid ejecting head main body is provided with a common flow channel through which the liquid discharged, are connected respectively with said common channel, and a first opening and a second opening,
The reservoir is disposed along the one direction and connected to the first opening, and the reservoir is disposed along the one direction and connected to the second opening. A second reservoir flow path,
The first and second reservoir channels are arranged so as to overlap in order of the first reservoir channel and the second reservoir channel from the liquid ejection head main body side, and the first reservoir channel flow resistance of the flow path, much larger than the flow resistance of the second reservoir channel,
The common flow path is disposed along the one direction,
The first reservoir channel is open to the outside at one end of the liquid ejection head, and the first reservoir channel and the first opening are connected by the other end of the liquid ejection head. And
The second reservoir channel is open to the outside at the other end of the liquid discharge head, and the second reservoir channel and the second opening are at the one end of the liquid discharge head. A liquid discharge head characterized by being connected . A plurality of the common flow paths are arranged along the one direction in a direction intersecting the one direction,
The second reservoir channel is branched from the second reservoir channel main body and the second reservoir channel main body at the one end, and connected to the plurality of second openings. A connecting flow path,
The first reservoir channel is disposed so as to pass between a plurality of the second connection channels, and between the second connection channels through which the first reservoir channel passes. The distance in the direction that intersects the one direction is greater than the distance in the direction that intersects the one direction between the common channels in which the second connection channels are connected via the second openings. The liquid discharge head according to claim 1 , wherein the liquid discharge head is also long. A plurality of the common flow paths are arranged along the one direction in a direction intersecting the one direction,
The second reservoir channel is branched from the second reservoir channel main body and the second reservoir channel main body at the one end, and connected to the plurality of second openings. A connecting flow path,
The first reservoir channel is disposed so as to pass between a plurality of the second connection channels, and in the second connection channel through which the first reservoir channel passes, toward the second reservoir passage body from the first of the second opening, a portion extending in the stacking direction, according to claim 1 or 2, characterized in that it is arranged offset in the one direction Liquid discharge head. The first reservoir passage, the liquid discharge head according to claim 1, characterized in that it is open to the outside at the other end of the liquid ejection head. The first reservoir channel includes a first damper, and the second reservoir channel includes a second damper having a smaller compliance than the first damper. Item 5. The liquid ejection head according to any one of Items 1 to 4 . A damper chamber is disposed along the one direction between the first reservoir channel and the second reservoir channel, and a portion between the damper chamber and the first reservoir channel. , and at least one site between the damper chamber and the second reservoir passage, the liquid discharge head according to any one of claims 1 to 5, characterized in that has a deformable damper . A liquid discharge head main body that is flat and long in one direction, and a liquid discharge head that is stacked on the liquid discharge head main body and includes a reservoir that is flat and long in the one direction;
The liquid discharge head main body includes a common flow path through which liquid to be discharged flows, and a first opening and a second opening connected to the common flow path, respectively.
The reservoir is disposed along the one direction and connected to the first opening, and the reservoir is disposed along the one direction and connected to the second opening. A second reservoir flow path,
The first and second reservoir channels are arranged so as to overlap in order of the first reservoir channel and the second reservoir channel from the liquid ejection head main body side, and the first reservoir channel The flow path resistance of the flow path is greater than the flow path resistance of the second reservoir flow path,
The first reservoir channel includes a first damper, and the second reservoir channel includes a second damper having a smaller compliance than the first damper. Discharge head. A liquid discharge head main body that is flat and long in one direction, and a liquid discharge head that is stacked on the liquid discharge head main body and includes a reservoir that is flat and long in the one direction;
The liquid discharge head main body includes a common flow path through which liquid to be discharged flows, and a first opening and a second opening connected to the common flow path, respectively.
The reservoir is disposed along the one direction and connected to the first opening, and the reservoir is disposed along the one direction and connected to the second opening. A second reservoir flow path,
The first and second reservoir channels are arranged so as to overlap in order of the first reservoir channel and the second reservoir channel from the liquid ejection head main body side, and the first reservoir channel The flow path resistance of the flow path is greater than the flow path resistance of the second reservoir flow path,
A damper chamber is disposed along the one direction between the first reservoir channel and the second reservoir channel, and a portion between the damper chamber and the first reservoir channel. And at least one of the portions between the damper chamber and the second reservoir channel is a deformable damper . Both the part between the damper chamber and the first reservoir flow path and the part between the damper chamber and the second reservoir flow path are deformable dampers. The liquid discharge head according to claim 8 . A liquid discharge head according to any one of claims 1 to 9 , a transport unit for transporting a recording medium to the liquid discharge head, a liquid to be discharged to the first reservoir channel, A recording apparatus comprising: a liquid circulation mechanism that partially collects from the second reservoir channel; and a control unit that controls the liquid discharge head.

Images