JP2014004767A - Cover member for liquid discharge head, and liquid discharge head with cover and recording apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cover member for a liquid discharge head to be attached to the liquid discharge head so that a mist of liquid does not easily enter the liquid discharge head, and a liquid discharge head with cover and a recording apparatus using the same.SOLUTION: A cover member 80 for a liquid discharge head 2 protects a connection portion of a wiring portion 99, attached to the liquid discharge head 2 for driving the liquid discharge head 2, and the liquid discharge head 2. The wiring portion 99 is a wiring cable obtained by binding a plurality of cables in a linear shape or a flat cable. The cover member 80 includes an opening through which the wiring portion 99 passes. The opening is displaceable along both surfaces of the wiring portion 99.

Description

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

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

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

  Therefore, the head body is connected to the manifold (common flow path) and the flow path member having the discharge holes connecting the manifold through the plurality of pressure chambers, and the plurality of displacement elements provided so as to cover the pressure chambers, respectively. It is known that the actuator unit having the structure is laminated (see, for example, Patent Document 1). In this head body, pressurizing chambers connected to a plurality of 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 ink is ejected from each ejection hole. In the main scanning direction, printing is possible at a resolution of 600 dpi. In addition, a housing is attached to the head body to form a liquid discharge head, and a signal for driving the head body is transmitted by a signal cable through a hole opened in the housing, and the hole is a resin lid. It is blocked by.

JP 2010-522562 A

However, in the liquid ejection head described in Patent Document 1, details of the lid are not described, and depending on the shape of the liquid ejection head, a signal cable and lid such as a liquid mist generated during printing, or a housing between the lid and the housing. There is a problem that the liquid discharge head may not work because the liquid enters the body and the liquid is short-circuited between the signal wirings.

  Accordingly, an object of the present invention is to provide a cover member of a liquid discharge head that is attached to a liquid discharge head so that liquid mist does not easily enter, and a cover-equipped liquid discharge head and a recording apparatus using the cover member.

  The cover member of the liquid discharge head according to the present invention is a wiring cable that is attached to the liquid discharge head and drives the liquid discharge head, in which a plurality of cables are linearly bundled or a flat cable. A cover member of the liquid discharge head that protects the connection portion with the liquid discharge head, and includes an opening through which the wiring portion passes, and the opening can be deformed along both surfaces of the wiring portion. It is characterized by being.

  In the liquid discharge head with a cover according to the present invention, the cover member of the liquid discharge head is attached to the liquid discharge head.

  Also, the recording apparatus of the present invention includes the cover-equipped liquid ejection head, a transport unit that transports the recording medium to the cover-equipped liquid ejection head, and the cover-equipped liquid ejection head via the wiring unit. And a control unit that controls the liquid discharge head with cover.

  According to the cover member of the liquid discharge head of the present invention, the opening of the cover member is deformed so as to be along both surfaces of the wiring part passing through the opening. The gap between the openings along the side is reduced, and mist or the like is less likely to enter the liquid ejection head.

1 is a schematic configuration diagram of a printer that is a recording apparatus according to an embodiment of the present invention. It is a perspective view of an example of the liquid discharge head to which the cover member of the liquid discharge head of the present invention is attached. (A) is a perspective view of the cover member of the liquid discharge head which concerns on one Embodiment of this invention, (b) is the top view, (c) is the longitudinal cross-sectional view. 3 is a longitudinal sectional view taken along line XX in FIG. 2 in a state where a cover member of the liquid discharge head shown in FIG. 3 is attached to the liquid discharge head shown in FIG. FIG. 5 is a plan view of an ejection head body that is a part of the liquid ejection head shown in FIG. 4. FIG. 5 is a partial longitudinal sectional view of a discharge head main body that is a part of the liquid discharge head shown in FIG. 4.

  FIG. 1 is a schematic configuration diagram of a color inkjet printer 1 that is a recording apparatus including a cover-equipped liquid ejection head 102 to which a liquid ejection head cover member according to an embodiment of the present invention is attached. The color inkjet printer 1 (hereinafter referred to as printer 1) has four liquid discharge heads 102 with a cover. These cover-equipped liquid ejection heads 102 are arranged along the transport direction of the recording medium P such as paper and are fixed to the printer 1. The cover-equipped liquid ejection head 102 has an elongated shape in a direction from the front to the back in FIG. 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 recording medium 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 feed unit 114 includes a paper storage case 115 that can store a plurality of recording media P, and a paper supply roller 145. The paper feed roller 145 can send out the uppermost recording medium P among the recording media 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 recording medium P. The recording medium P sent out from the paper feed 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 conveyance surface 127 that conveys the recording medium 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 recording medium 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 recording medium P is pressed against the conveying surface 127 of the conveying belt 111 and is fixed on the conveying surface 127. Then, the recording medium 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 recording medium P can be reliably fixed to the transport surface 127.

  The four cover-equipped liquid ejection heads 102 are arranged close to each other along the conveyance direction by the conveyance belt 111. Each cover-equipped liquid discharge head 102 is a liquid discharge head 2 to which a cover member 80 is attached. The liquid ejection head 2 includes a head main body 13 at the lower end and a reservoir 40 and a housing 90 attached to the head main body 13. The lower surface of the head body 13 is a discharge hole surface 4a provided with a large number of discharge holes 8 for discharging liquid (see FIGS. 4 and 6).

  Liquid droplets (ink) of the same color are ejected from the ejection holes 8 provided in one liquid ejection head 102 with a cover. The discharge holes 8 of each liquid discharge head 102 with cover are arranged at equal intervals in one direction (a direction parallel to the recording medium P and perpendicular to the conveyance direction of the recording medium P, and the longitudinal direction of the liquid discharge head 102 with cover). Therefore, it is possible to print without a gap in one direction. The colors of the liquid ejected from each liquid ejecting head with cover 102 are magenta (M), yellow (Y), cyan (C), and black (K), respectively. Each cover-equipped liquid discharge head 102 is disposed with a slight gap between the discharge hole opening plane 4 a on the lower surface of the head body 13 and the transport surface 127 of the transport belt 111.

  The recording medium P transported by the transport belt 111 passes through the gap between the liquid ejection head with cover 102 and the transport belt 111. At that time, droplets are ejected from the head main body 13 constituting the liquid ejection head with cover 102 toward the upper surface of the recording medium 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 recording medium 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 recording medium P on which the color image is printed is transported to the peeling plate 140 by the transport belt 111. At this time, the recording medium P is peeled from the transport surface 127 by the right end of the peeling plate 140. Then, the recording medium P is sent out to the paper receiving unit 116 by the feed rollers 121a to 122b. In this way, the printed recording medium P is sequentially sent to the paper receiving unit 116 and stacked on the paper receiving unit 116.

  A paper surface sensor 133 is installed between the cover-equipped liquid ejection head 102 and the nip roller 138 that are furthest upstream in the conveyance direction of the recording medium 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 recording medium P on the conveyance 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 with cover 102, the conveyance motor 174, and the like so that the conveyance of the recording medium P and the printing of the image are synchronized with each other based on the detection result sent from the paper surface sensor 133.

  FIG. 2 is a perspective view of the liquid discharge head 2. 3A to 3C are a perspective view, a plan view, and a longitudinal sectional view of the cover member 80 (of the liquid discharge head), respectively. 4 is a cross-sectional view of the liquid discharge head 102 with a cover in which the cover member 80 is attached to the liquid discharge head 2 shown in FIG. 3, taken along the line XX in the liquid discharge head 2 shown in FIG. Strictly speaking, the wiring part 99 and the connector 98 are not included in the liquid discharge head 102 with a cover.

  The liquid discharge head 2 includes a head main body 13, a housing 90, and an internal wiring portion. The internal wiring portion is a general term for portions that transmit drive signals supplied from the outside to the head main body 13, and includes an internal connector 82, a wiring board 84, and the like. The casing 90 is made of metal and has a rectangular parallelepiped shape and covers most of the head main body 13 and the internal wiring portion. The housing 90 has an opening 90a through which the wiring part 99 or the internal wiring part passes.

The cover member 80 is attached so as to cover the opening 90a, and the opening 80a-1 through which the wiring part 99 passes is open. Thereby, the cover member 80 includes a connection portion between the wiring portion 99 and the liquid discharge head 2, more specifically, a connection portion between the end portion (including the connector 98) of the wiring portion 99 and the external collector 92. It protects from short-circuiting to mist from the outside, and further protects the internal wiring part inside the housing 99. The wiring part 99 is a wiring cable in which a plurality of cables are bundled in a straight line, or is a flat cable. A plurality of cables bundled in a straight line means that the cables are arranged in a straight line, or the cables are arranged in two or more lines in a straight line, and the state in which the cables are arranged, It doesn't have to be regular. That is, when the cross section of the bundle of cables is viewed, the aggregate of the cross section has a shape that is long in one direction, and two surfaces are roughly configured along the long direction in one direction. That's fine.

  The cover member 80 is made of a flexible material such as a resin such as polyethylene or polypropylene terephthalate, and the opening 80a-1 extends along the wiring part 99 by passing the wiring part 99 therethrough. Deform. As a result, the gap between the wiring portion 99a and the opening portion 80a-1 becomes small, and mist does not easily enter the housing 90 or adhere to the connector 98. Further, when the wiring portion 99 is a bundle of cables, it works so as to narrow the gap between the cables, so that it is difficult for mist to enter the housing 90 or adhere to the connector 98 from between the cables.

  The opening 80 a-1 is configured by a main slit 80 a-1 that is a cut provided in the cover member 80 (it is the same part as the opening and is represented by the same symbol). The main slit 80a-1 is provided substantially parallel to the parallel direction in which the terminals of the external connector 82 in the liquid ejection head 2 are arranged, so that both surfaces of the wiring portion 99 and the main slit 80a-1 are substantially parallel. Thus, the opening 80 a-1 is easily deformed along both surfaces of the wiring portion 99. Since the cover member 80 is flexible and the wiring portion 99 is also often flexible, a slight angle difference can be absorbed. Therefore, the parallel direction of the main slit 80a-1 and the terminal of the external connector 82 The angle may be about -10 to 10 degrees.

  If the sub slit 80a-2 is provided so as to intersect the main slit 80a-1, each piece delimited by the sub slit 80a-2 will be along the wiring part 99, which is more preferable. This is a particularly preferable property when the wiring portion 99 is a bundle of cables or the like and the unevenness on both sides thereof is irregular to some extent. Further, even when the tip of the wiring part 99 is the connector 98 where the opening 80a-1 opens more largely due to the presence of the sub slit 80a-2, the connector 98 can be easily passed. Further, even when the wiring portion 99 is thick, the opening 80 a-1 is easily deformed along the wiring portion 99.

  If the sub slit 80 a-2 is provided so as to be substantially orthogonal to the main slit 80 a-1, each piece divided by the sub slit 80 a-2 can be easily along the wiring part 99. Further, when a plurality of sub slits 80 a-2 are provided, each piece delimited by the sub slit 80 a-2 can be more easily along the wiring portion 99. If the sub slit 80a-2 is arranged in a straight line with the main slit 80a-1 interposed therebetween, the pieces separated by the sub slit 80a-2 are opposed to each other with the wiring portion 99 interposed therebetween. Therefore, the gap between the wiring part 99 can be made narrower. Moreover, the process which cut | disconnects and opens the sub slit 80a-2 becomes easy.

  The opening 80a-1 is provided in the accommodating portion 80a that is a protruding portion of the cover member 80 so that the external connector 82 and the connector 98 can be accommodated when they protrude from the housing 90. Good. As a result, the cover member 80 has a shape substantially along one surface of the housing 90, so that mist or the like can hardly enter from between the housing 90 and the cover member 80. The accommodating portion 80a is made larger than the external connector 82 and the connector 98 protruding from the opening 90a of the housing 90.

The housing portion 80a is substantially parallel to the surface of the housing 90 where the opening 90a is provided, the top plate portion provided with the main slit 80a-1 and the sub slit 80a-2, and the housing 90 of the top plate portion and the cover member 80. And a side surface connecting the surface along the surface on which the opening 90a is provided. The shape of the side surface of the housing portion 80a, that is, the shape of the cross section parallel to the opening 80a-1 of the housing portion 80a, or the shape of the cross section in the direction orthogonal to the direction in which the electricity of the wiring portion 99 of the housing portion 80a flows is By being a hexagonal or more polygonal shape, the shape of the accommodating portion 80a is not easily collapsed, and the opening 80a-1 can be easily maintained in a shape along the wiring portion 99.

  Here, the hexagonal or more polygonal shape means that the shape of the cross section of the accommodating portion 80a is a rectangle that is long in one direction as a whole, and some corners are formed in the middle of two sides along the long direction. Thus, the accommodating portion 80a can be hardly deformed so as to fall in a direction orthogonal to the long direction. Accordingly, the polygonal corners referred to here do not include corners provided in the vicinity of the four rectangular corners in order to give the four rectangular corners an R shape. That is, the shape of the cross section of the accommodating portion 80a shown in FIGS. 3 (a) and 3 (b) is strictly a decagonal shape, but among these, there are 2 portions corresponding to four rectangular corners. One corner is considered to form a corner with one R, and here it is a hexagon. By making the polygonal shape into a convex polygon, the shape of the accommodating portion 80a is not easily collapsed, and the accommodating portion 80a is easily formed during processing. If the polygonal shape is a hexagonal shape in which a corner is provided in the center in the long direction of the accommodating portion 80a, the shape can be hardly collapsed so as to increase the number of corners.

  Moreover, the shape of the accommodating part 80a can be made hard to collapse by making the side surface of the accommodating part 80a incline and the cross section becomes smaller as it goes upward.

  The cover member 80 covers one surface (upper surface) with the opening 90a of the housing 90 on the rectangular parallelepiped, and covers a part of the four side surfaces connected to the upper surface. That is, the cover member 80 covers one end including the upper surface of the casing 90 on the rectangular parallelepiped. Of the four side surfaces, the first protrusion 80b-1 is provided on the cover member 80a that covers the two side surfaces that are connected to each other with the upper surface and the long side of the upper surface sandwiched therebetween. The size of the cover member 80 in the portion where the first protrusion 80b-1 is provided is smaller than that of the housing 90. When the first protrusion 80b-1 hits the housing 90, the cover member 80 is By deforming, the cover member 80 can be attached to the housing 90.

  By providing the first protrusion 80b-1 at the end in the direction along the long side of the upper surface, the first protrusion 80b-1 is close to a corner that is not easily deformed of the cover member 80a. As a result, the cover member 80a is difficult to come off. In addition, an edge part here is a part of 1/3 of each both ends when the length of a long side is divided into 3 equal parts.

  Further, the second protrusion 80b-3 is provided on the cover member 80a that covers the two side surfaces of the four side surfaces of the casing 90 that are connected to each other with the short side of the upper surface sandwiched therebetween. May be. The size of the cover member 80 in the portion where the second protrusion 80b-2 is provided is smaller than that of the housing 90. When the second protrusion 80b-1 hits the housing 90, the cover member 80 is By deforming, the cover member 80 becomes difficult to shift with respect to the housing 90.

  Next, other parts of the liquid discharge head 2 will be described. The body discharge head 2 may further include a reservoir 40 provided with a reservoir channel. The reservoir channel supplies the head body 13 with the liquid supplied from the outside through the opening 41b of the reservoir channel. A part of the inner wall of the reservoir channel is a damper made of an elastically deformable material. Since the damper can be deformed in the direction facing the reservoir flow path, the damper can be elastically deformed to change the volume of the reservoir flow path, and the liquid discharge amount has changed abruptly. In some cases, the liquid can be supplied stably. In addition, it is preferable to provide a filter in the reservoir flow path so that foreign matter contained in the liquid does not easily enter the ejection head 2 and can suppress non-ejection caused by clogging of foreign matter.

In addition, an elastic plate 96 provided with a heat insulating member 97 and a guide frame 88 for fixing a wiring board 84 for processing a drive signal for discharging liquid from the head main body 13 are fixed to the reservoir 40. . The drive signal sent from the control unit 100 via the wiring unit 99 passes through the external connector 82, the wiring board 84, the internal connector 86, the signal transmission unit 92, and the driver IC 55 mounted on the signal transmission unit 92, By driving the displacement element 50 of the piezoelectric actuator substrate 21 and pressurizing the liquid inside the flow path member 4, droplets are ejected. Note that the wiring board 84 divides the drive signal into a plurality of piezoelectric actuator boards 21 or rectifies the drive signal, for example. The signal transmission portion 92 is a flexible belt-like member, and has a metal wiring inside. A part of the wiring is exposed on the surface of the signal transmission unit 92, and is electrically connected to the internal connector 86, the driver IC 55, and the piezoelectric actuator substrate 21 by the exposed wiring. The signal transmission unit 92 is, for example, an FPC (Flexible Printed Circuit).

  Further, the reservoir 40 is provided with a recess 62 in which the piezoelectric actuator substrate 21 is disposed between the reservoir 40 and the flow path member 4.

  The driver IC 55 generates heat when processing the drive signal. Since the driver IC 55 is pressed against the metal casing 90 by deflecting the elastic plate 96, the generated heat is mainly transmitted to the casing 90, and further spreads quickly over the entire casing 90 and is radiated to the outside. . The heat insulating member 97 makes it difficult for heat to be transferred to the reservoir channel member. The heat insulating member 97 may also be made elastic to help press the driver IC 55 against the metal housing 90.

  Next, the flow path member 4 constituting the liquid discharge head 2 will be described. FIG. 5 is a plan view showing the flow path member 4 and the piezoelectric actuator 21 in the head main body 13. FIG. 5 is a partial longitudinal sectional view of FIG.

  The head main body 13 includes a flat plate-like flow path member 4 and a piezoelectric actuator substrate 21 including a displacement element 50 as a pressurizing portion on the flow path member 4. The piezoelectric actuator substrate 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. In addition, two piezoelectric actuator substrates 21 are arranged on the flow path member 4 as a whole in a zigzag manner, two along each of the two virtual straight lines parallel to the longitudinal direction of the flow path member 4. Yes. The oblique sides of the piezoelectric actuator substrates 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 substrates 21 are mixed and landed.

  A manifold 5 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 substrates 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). The flow path connecting from the opening 5 b to the sub manifold extends along the oblique side of the piezoelectric actuator substrate 21 and is arranged so as to intersect with the longitudinal direction of the flow path member 4. In the region sandwiched between the two piezoelectric actuator substrates 21, one manifold 5 is shared by the adjacent piezoelectric actuator substrates 21, and the sub manifold is branched from both sides of the manifold 5. These sub-manifolds extend in the longitudinal direction of the head body 13 adjacent to each other in a region facing each piezoelectric actuator substrate 21 inside the flow path member 4.

  The flow path member 4 has four pressure chamber groups 9 in which a plurality of pressure chambers 10 are formed in a matrix (that is, two-dimensionally and regularly). The pressurizing chamber 10 is a hollow region having a substantially rhombic planar shape with rounded corners. The pressurizing chamber 10 is formed so as to open on the upper surface of the flow path member 4. These pressurizing chambers 10 are arranged over almost the entire surface of the upper surface of the flow path member 4 facing the piezoelectric actuator substrate 21. Therefore, each pressurizing chamber group 9 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 adhering the piezoelectric actuator substrate 21 to the upper surface of the flow path member 4.

  In the present embodiment, four sub-manifolds arranged side by side as shown in FIG. 4 are connected to four rows of pressurizing chambers, respectively. Two rows of pressurizing chambers connected to one sub-manifold are arranged on both sides of the sub-manifold. As a result, a total of 16 pressurizing chamber rows are arranged, and the rows of discharge holes 8 connected from the pressurizing chamber rows are also 16 rows. The discharge holes 8 in each row of the discharge holes 8 are arranged at equal intervals, and the discharge holes 8 in each row are arranged slightly shifted. As a result, the discharge hole 8 as a whole can form an image with a resolution of 600 dpi in the longitudinal direction.

  That is, when the discharge holes 8 are projected so as to be orthogonal to a virtual straight line parallel to the longitudinal direction of the flow path member 4, the four discharges connected to each sub-manifold are within the range of R of the virtual straight line shown in FIG. The holes 8, that is, a total of 16 discharge holes 8 are equally spaced at 600 dpi. In addition, individual flow paths 32 are connected to each sub-manifold at intervals corresponding to 150 dpi on average. This is because when the discharge holes 8 for 600 dpi are divided and connected to the four sub-manifolds, the individual flow paths 32 connected to the sub-manifolds are not necessarily connected at equal intervals. The individual flow paths 32 are formed in the present direction, that is, in the main scanning direction at an average interval of 170 μm or less (25.4 mm / 150 = 169 μm interval if 150 dpi).

  Individual electrodes 35 to be described later are formed at positions facing the pressurizing chambers 10 on the upper surface of the piezoelectric actuator substrate 21. The individual electrode 35 is slightly smaller than the pressurizing chamber 10, has a shape substantially similar to the pressurizing chamber 10, and is disposed so as to be within a region facing the pressurizing chamber 10 on the upper surface of the piezoelectric actuator substrate 21. ing.

  A large number of discharge holes 8 are formed in the liquid discharge surface on the lower surface of the flow path member 4. These discharge holes 8 are arranged at positions avoiding the region facing the sub-manifold arranged on the lower surface side of the flow path member 4.

  Further, these discharge holes 8 are arranged 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 an area having almost the same size and shape as the piezoelectric actuator substrate 21 as one group, and the displacement elements 50 of the corresponding piezoelectric actuator substrate 21 are displaced from the discharge holes 8. Droplets can be ejected. The discharge holes 8 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, in order from the top surface of the flow path member 4, the cavity plate 22, the base plate 23, the aperture (squeezing) plate 24, the supply plates 25 and 26, the manifold plates 27, 28 and 29, the cover plate 30 and the nozzle plate 31.
It is. A number of holes are formed in these plates. Each plate is aligned and stacked such that these holes communicate with each other to form the individual flow path 32 and the sub-manifold. As shown in FIG. 5, the head body 13 includes an individual flow path 32 in which the pressurizing chamber 10 is on the upper surface of the flow path member 4, the sub manifold is on the inner lower surface side, the discharge hole 8 is on the lower surface. The constituent parts are arranged close to each other at different positions, and the sub-manifold 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. First, the pressurizing chamber 10 formed in the cavity plate 22. Secondly, there is a communication hole that forms a flow path connecting from one end of the pressurizing chamber 10 to the sub manifold. This communication hole is formed in each plate from the base plate 23 (specifically, the inlet of the pressurizing chamber 10) to the supply plate 25 (specifically, the outlet of the sub manifold). 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 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 23 (specifically, the outlet of the pressurizing chamber 10) to the nozzle plate 31 (specifically, the discharge hole 8).

  Fourth, there is a communication hole constituting the sub manifold. The communication holes are formed in the manifold plates 27 to 29.

  Such communication holes are connected to each other to form an individual flow path 32 extending from the liquid inlet (submanifold outlet) to the discharge hole 8 from the submanifold. The liquid supplied to the sub manifold is discharged from the discharge hole 8 through the following path. First, from the sub-manifold, it passes through the individual supply channel 6 and reaches one end of the aperture 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 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.

  Similarly to the flow path member 4, the branch flow path member 60 is obtained by a rolling method or the like, and is processed into a predetermined shape by etching on the plates 60a to 60c. In addition, a recess 63 is provided in which the liquid channel 61 and the piezoelectric actuator are accommodated.

  As shown in FIG. 6, the piezoelectric actuator substrate 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 substrate 21 is about 40 μm. Each of the piezoelectric ceramic layers 21a and 21b extends so as to straddle the plurality of pressure 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 substrate 21 has 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 pressurizing chamber 10 on the upper surface of the piezoelectric actuator substrate 21. One end of the individual electrode 35 is drawn out of a region facing the pressurizing chamber 10 to form a connection electrode 36. The connection electrode 36 is made of, for example, silver-palladium containing glass frit, and has a convex shape with a thickness of about 15 μm. Further, the connection electrode 36 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 35 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 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 pressurizing chambers 10 in the region facing the piezoelectric actuator substrate 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, like the large number of individual electrodes 35, another electrode on the signal transmission unit 92. Connected with.

  As shown in FIG. 6, 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 substrate 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 substrate 21 has a so-called unimorph type configuration.

  In addition, by selectively supplying a predetermined drive signal to the individual electrode 35, pressure is applied to the liquid in the 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 substrate 21 that faces each pressurizing chamber 10 corresponds to the individual displacement element 50 corresponding to each pressurizing chamber 10 and the liquid discharge port 8. That is, in the laminated body composed of two piezoelectric ceramic layers, a displacement element 50 that is a piezoelectric actuator having a structure as shown in FIG. 6 as a unit structure is provided for each pressurizing chamber 10. Is formed by a diaphragm 21a, a common electrode 34, a piezoelectric ceramic layer 21b, and an individual electrode 35. The piezoelectric actuator substrate 21 includes a plurality of displacement elements 50 as pressurizing portions. 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).

  The large number of individual electrodes 35 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.

  In the piezoelectric actuator substrate 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. It works 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. That is, the piezoelectric actuator substrate 21 has the piezoelectric ceramic layer 21b on the upper side (that is, the side away from the pressurizing chamber 10) as a layer including the active portion and the lower side (that is, the side close to the pressurizing chamber 10). This piezoceramic layer 21a is a so-called unimorph type structure having an inactive layer.

In this configuration, when the control unit 100 sets the individual electrode 35 to a predetermined positive or negative potential with respect to the common electrode 34 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).

  When printing is performed with such a liquid discharge head 2, some of the discharged droplets become minute mists and float in the air. Mist may be generated due to other liquid discharge heads or other factors, but anyway, if it enters the housing 90 and adheres to the exposed portion of the wiring portion, a short circuit or the like occurs. There is a fear. Therefore, as described above, the protective cover 80 is attached so as to cover a part of the liquid discharge head 2 and the end of the wiring part 99 that electrically connects the liquid discharge head 2 and the control unit.

  The protective cover can be produced by vacuum forming, for example, as follows. A sheet of resin such as polypropylene or polyethylene terephthalate is heated and sucked from the concave mold to make the sheet have the same shape as the concave mold. Then, after cooling and removing from the concave mold, it is separated from the sheet. Then, the main slit 80a-1 and the sub slit 80a-2 are formed by pressing the metal mold | die with which the blade was embedded.

  In vacuum forming, a convex mold may be used. However, if a concave mold is used, stress remains in the cover member 80, and the cover member 80 along the side surface of the housing 90 is covered by the lower side of the cover member 80. It becomes difficult to get into the mist because it gets drowned. In particular, when the first protrusion 80b-1 is provided at the end portion, stress that sag in the central portion therebetween remains, so that intrusion of mist from the side surface can be suppressed. Whether the convex mold or the concave mold is used can be determined by, for example, looking at the traces of the suction holes remaining in the cover member 80. For example, if the trace of the suction hole remaining at the upper end of the housing portion 80a is directed outward, it is sucked and molded to fit the concave mold.

DESCRIPTION OF SYMBOLS 1 ... Printer 2 ... Liquid discharge head 4 ... Channel member 4a ... Discharge hole surface 5 ... Manifold 5b ... Manifold opening (liquid introduction hole)
6 ... Individual supply flow path 8 ... Discharge hole 9 ... Pressurizing chamber group 10 ... Pressurizing chamber 12 ... Squeeze 13 ... Head body 21 ... Piezoelectric actuator substrate 21a ...・ Piezoelectric ceramic layer (diaphragm)
21b ... Piezoelectric ceramic layer 22-31 ... Plate 32 ... Individual flow path 34 ... Common electrode 35 ... Individual electrode 36 ... Connection electrode 40 ... Reservoir 41b ... Reservoir flow Liquid inlet hole 50 ... Displacement element (pressurizing part)
55 ... Driver IC
63 ... Recessed part (accommodating the piezoelectric actuator substrate) 80 ... Cover member (of the liquid ejection head) 80a ... Storage part 80a-1 ... Main slit (opening part)
80a-2 ... sub slit 80b-1 ... first projection 80b-2 ... second projection 82 ... external connector 84 ... wiring board 86 ... internal connector 88 ..Guide frame 90 ... Case 90a ... (Case opening) 92 ... Signal transmission part 96 ... Elastic plate 97 ... Heat insulation member 98 ... Connector 99 ... Wiring Section (bundle of wiring cables)
102: Liquid discharge head with cover

Claims (9)

A wiring cable that is attached to a liquid ejection head and drives the liquid ejection head, or a wiring cable in which a plurality of cables are bundled in a straight line or a connection portion between the liquid ejection head and a flat cable is protected. A cover member for the liquid discharge head,
A cover member for a liquid discharge head, comprising an opening through which the wiring portion passes, wherein the opening can be deformed along both surfaces of the wiring portion.   2. The liquid according to claim 1, wherein the opening includes a linear main slit that is long in one direction and sub-slits provided on both sides of the main slit so as to intersect the main slit. Cover member for the discharge head.   3. The cover member for a liquid discharge head according to claim 2, wherein the sub slits provided on both sides of the main slit are arranged linearly across the main slit.   The liquid ejection head cover according to claim 1, further comprising a housing portion that protrudes so that the connection portion can be housed, and the opening portion is disposed at a tip thereof. Element.   The cover member of the liquid discharge head according to claim 4, wherein a shape of a cross section parallel to the opening of the housing portion is a hexagonal or more polygonal shape. When attached to the rectangular parallelepiped liquid ejection head, each of the four sides of the liquid ejection head connected to each other on one side of the rectangular surface with the connecting portion of the liquid ejection head and sandwiching each side of the one surface It covers a part,
Among the four side surfaces, a projection is provided that sandwiches the one side and the side on the long side that is connected with the long side of the one side in between, and the projection is the long side of the side on the long side The cover member for a liquid discharge head according to claim 1, wherein the cover member is disposed at each of both end portions in a direction along the line.   A liquid discharge head with a cover, wherein the cover member of the liquid discharge head according to claim 1 is attached to the liquid discharge head.   The liquid discharge head with a cover, wherein the liquid discharge head includes a connector as the connecting portion, and a direction of the main slit is substantially parallel to an arrangement direction of terminals of the connector.   A liquid discharge head with a cover according to claim 7, a transport unit for transporting a recording medium to the liquid discharge head with a cover, and the cover-equipped liquid discharge head electrically via the wiring unit. And a controller that controls the cover-equipped liquid ejection head.