JP5347252B2 - Droplet discharge head and droplet discharge apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact liquid droplet discharging head, and a liquid droplet discharging apparatus. <P>SOLUTION: In this liquid droplet discharging head, a bulkhead 56 is not formed at the outside of a piezoelectric element group 66 by installing the bulkhead 56 in a space between adjacent piezoelectric element 34 and a piezoelectric element 34. Thus, the piezoelectric element groups 66 comes closer to each other in adjacent recording head units 178. Therefore, when comparing with Fig.6(A), the width of the recording head unit 178 becomes narrower, and the length of a recording head array 132 becomes shorter. That is, the projection area of the recording head array 132 becomes smaller, and an image forming section 130 and an inkjet recording apparatus 112 can be miniaturized. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a droplet discharge head and a droplet discharge device that discharge a droplet from a nozzle and record an image on a recording medium.

In an ink jet recording head using a piezo actuator, for example, as in Patent Document 1, a support member (partition wall) constituting an ink reservoir is joined to the outside of a formation area of the piezo actuator, and the support member is joined. It is necessary to secure an area for this purpose outside the formation area of the piezo actuator. In addition, the electrical wiring connected to the piezo actuator is taken out along the longitudinal direction of the ink jet recording head, and the head width becomes large.
JP 2003-311953 A

  In consideration of the above-described facts, the present invention has an object to provide a small droplet discharge head and a droplet discharge device.

A plurality of nozzles for discharging droplets, a pressure chamber connected to each of the nozzles, a vibration plate constituting a part of the pressure chamber, and provided on the opposite side of the pressure chamber with the vibration plate interposed therebetween, and deformed flexibly. In addition to discharging droplets from the nozzle, the piezoelectric body, the lower electrode provided on the surface of the piezoelectric body on the diaphragm side, and the surface of the piezoelectric body opposite to the lower electrode are provided. An upper electrode; and a partition wall provided with a lower portion of an individual wiring portion formed only between the adjacent piezoelectric elements and provided with an individual wiring connected to the upper electrode; And a plate member provided on the partition wall and supported by the partition wall to form a gap with the piezoelectric element.

According to a second aspect of the invention, in the liquid droplet ejection head according to claim 1, wherein said partition wall is arranged in a grid.

According to a third aspect of the present invention, in the liquid droplet ejection head according to the first or second aspect , the partition is formed integrally with the plate member.

According to a fourth aspect of the present invention, in the droplet discharge head according to any one of the first to third aspects, the individual wiring portion is formed of an insulating resin and the individual wiring is disposed. It is characterized by having a groove for making it.

According to a fifth aspect of the present invention, in the liquid droplet ejection apparatus, a plurality of liquid droplet ejection heads according to any one of the first to fourth aspects are arranged in a long shape.

According to a sixth aspect of the present invention, in the droplet discharge device according to the fifth aspect , the droplet discharge heads are arranged in a line.

According to the first aspect of the present invention, by forming a support portion between adjacent piezoelectric elements, the support portion is provided outside the piezoelectric element group composed of a plurality of piezoelectric elements. In comparison, the projected area of the droplet discharge head can be reduced. That is, a small droplet discharge head can be formed.

According to invention of Claim 2 , a partition can be formed continuously.

According to the invention described in claim 3 , it is not necessary to use a partition as a separate member, and the number of parts can be reduced.

According to the fifth aspect of the present invention, by using a plurality of liquid droplet ejection heads that achieve the effect of the invention according to any one of the first to fourth aspects, the nozzle region width and the head of the liquid droplet ejection head array The width can be reduced, and the size of the droplet discharge device can be reduced.

According to the sixth aspect of the present invention, the head width of the droplet discharge head array can be reduced as compared with the case where the droplet discharge heads are arranged in a staggered manner.

  An ink jet recording apparatus as a liquid droplet ejection apparatus according to an embodiment of the present invention will be described.

(Inkjet recording device)
FIG. 1 is a schematic explanatory view showing an ink jet recording apparatus. The ink jet recording apparatus 112 takes out the paper P, which is a recording medium stored in the paper feed tray 116, one by one, transports it on the transport path 122, and then performs image forming processing on the transport belt 128 by the image forming unit 130. The sheet P on which the image is formed is discharged to the discharge tray 146.

  Specifically, in the ink jet recording apparatus 112, the paper feed tray 116 is disposed at the lower part of the housing 114, and the sheets P stacked in the paper feed tray 116 are picked up one by one by the pickup roll 118. It is taken out. The paper P taken out by the pick-up roll 118 is transported by a plurality of transport roller pairs 120 constituting the transport path 122.

  In the ink jet recording apparatus 112, the driving roll 124 and the driven roll 126 are disposed horizontally and parallel to each other above the paper feed tray 116, and the driving roll 124 and the driven roll 126 are endless. A conveyor belt 128 is wound around.

  A downstream portion in the transport direction of the paper P in the transport path 122 (hereinafter, the downstream side in the transport direction of the paper P may be simply referred to as “downstream side”, and the upstream side in the transport direction of the paper P may be simply referred to as “upstream side”). A registration roll 121 is provided to correct the inclination of the paper P conveyed to the conveyance belt 128.

  A charging roll 136 connected to a power source (not shown) is disposed downstream of the registration roll 121. The power source may be a DC power source or an AC power source as long as the paper P can be charged to a predetermined potential.

  The charging roll 136 is driven with the conveying belt 128 and the paper P sandwiched between the charging roll 126 and presses the paper P toward the conveying belt 128. At this position, the charging roll 136 causes a predetermined potential difference between the charging roll 136 and the grounded driven roll 126 to apply electric charge to the paper P, thereby electrostatically adsorbing it to the transport belt 128.

  Here, the image forming unit is disposed above the transport belt 128 so as to face the flat portion 128 </ b> F of the transport belt 128. The region where the image forming unit faces is an ejection region SE where ink droplets are ejected from the image forming unit.

  The recording head array 132 constituting the image forming unit 130 used in the inkjet recording apparatus 112 has a so-called FWA (effective WAA) in which the effective recording area is longer than the width of the paper P (the length in the direction orthogonal to the transport direction). (Full Width Array).

  In the image forming unit 130, four recording head arrays 132 for inkjet recording corresponding to four colors of yellow (Y), magenta (M), cyan (S), and black (K) are transported in the direction of the paper P. They are arranged side by side (in the scanning direction) so that a full-color image can be recorded. Note that various known methods such as a so-called thermal method and a piezoelectric method can be applied as a method of ejecting ink droplets in each recording head array 132.

  Then, ink droplets corresponding to the image information are ejected from the recording head array 132 with the paper P facing the image forming unit 130, and an image (including characters) is recorded on the paper P.

  In the ink jet recording apparatus 112, image recording may be performed in a so-called single pass in which the paper P passes through the ejection region SE only once, or the paper P is circulated while being held by the transport belt 128. Thus, image recording may be performed by so-called multi-pass in which the ejection region SE is passed a plurality of times.

  On the other hand, a peeling plate 140 is disposed on the downstream side of the image forming unit 130 and is configured to peel the paper P from the transport belt 128. The paper P peeled off by the peeling plate 140 is conveyed by a plurality of discharge roller pairs 142 constituting a discharge path 144 provided on the downstream side of the peeling plate 140, and a paper discharge tray provided at the upper part of the housing 114. It is discharged on 146.

  Here, on the downstream side of the peeling plate 140 along the conveyance direction of the conveyance belt 128, a cleaning roll 148 is disposed so as to sandwich the conveyance belt 128 with the driving roll 124. The configuration is such that 128 surfaces are cleaned.

  Further, a reversing path 152 composed of a plurality of reversing roller pairs 150 is provided between the conveyance belt 128 and the paper feed tray 116, and the sheet P on which an image is recorded on one side is reversed by the reversing path 152. Then, by being guided again to the conveyor belt 128, image recording on both sides of the paper P can be easily performed.

  Further, an ink tank 154 is provided between the conveyor belt 128 and the paper discharge tray 146 to store the ink for each of the four colors. The ink or the like in the ink tank 154 is supplied to each recording head array 132 through an ink supply pipe (not shown). As the ink used here, various known inks such as water-based ink, oil-based ink, and solvent-based ink can be used.

(Recording head array)
Next, the recording head array 132 will be described.

  As shown in FIGS. 2 to 4, the image forming unit 130 includes a rectangular frame-shaped holder 134, and each recording head array 132 can be individually attached to and detached from the holder 134 (this embodiment). The number is 4 in this form, but the number can be changed as necessary).

  Specifically, the receiving plate 134A extends horizontally from the inner wall surfaces at both ends in the longitudinal direction of the holder 134, and the longitudinal direction of the long support member 135 provided in the recording head array 132 (the paper P) Both end portions (corresponding to a direction orthogonal to the transport direction) are fixed to the receiving plate 134A.

  A plurality of rectangular through holes 135A are formed at predetermined intervals along the longitudinal direction of the support member 135, and an ink tank 154 (FIG. 1) is formed in the rectangular through holes 135A via an ink supply pipe (not shown). The filter unit 156 connected to (see) can be inserted. The recording head unit 178 is attached to the support member 135 in a state where the filter unit 156 is inserted into the rectangular through hole 135A. Here, eight recording head units 178 are attached to the support member 135. .

  The recording head unit 178 includes a flow path unit 16, and the flow path unit 16 includes a thin plate-like nozzle plate 18, flow path plates 20, 22, 24, a pressure chamber plate 26, and a thin plate-like diaphragm 28. They are integrated by laminating and adhering each plate with an adhesive U.

  Here, a large number of nozzles 18A are formed in the nozzle plate 18 in a matrix, and each flow path plate 20, 22, 24 is formed as an opening (through hole), and becomes a liquid flow path. Communication paths 20A, 22A, and 24A are formed. These are in communication with each other and are connected to an opening formed in the pressure chamber plate 26 (a pressure chamber 32 constituted by the vibration plate 28).

  An ink supply hole 28A (see FIG. 5) is formed in the vibration plate 28. The ink supply hole 28A passes through an ink supply pipe (not shown) connected to the ink tank 154 (see FIG. 1). Then, the ink from which the foreign matter has been removed by the filter in the filter unit 156 is supplied.

  In addition, piezoelectric elements 34 are arranged in a matrix (see FIG. 5) on the upper surface of the diaphragm 28 corresponding to the pressure chambers 32. Each piezoelectric element 34 includes a piezoelectric body 50 that can be bent and deformed, an upper electrode 52 that is provided on an upper portion of the piezoelectric body 50 and has one polarity of the piezoelectric element 34, and an opposite side of the upper electrode 52 between the piezoelectric bodies 50. And a lower electrode 54 having the other polarity of the piezoelectric element 34, and a drive waveform is applied with the lower electrode 54 of the piezoelectric element 34 as a common electrode and the upper electrode 52 as an individual electrode. It has come to be.

  A voltage is applied to a predetermined piezoelectric element 34 at a predetermined timing by a drive IC 42 disposed on a flexible printed circuit board (FPC) 40 (see FIG. 10). As described above, when a voltage is applied to the piezoelectric element 34, the piezoelectric element 34 is bent and deformed, the diaphragm 28 vibrates, the volume of the pressure chamber 32 increases or decreases, and a pressure wave is generated. Ink droplets are ejected from the nozzle 18A through the communication passages 24A, 22A, and 20A.

  As shown in FIGS. 4 and 5, resin partition walls (supporting portions) 56 are formed in a lattice shape between the adjacent piezoelectric elements 34 and so as to be higher than the surface of the piezoelectric elements 34. Is provided. A glass top plate (plate material) 64 is joined to the end face of the partition wall 56, and a cavity (gap) 58 is formed above the piezoelectric element 34. Thereby, the driving of the piezoelectric element 34 and the vibration of the diaphragm 28 are not affected.

  In addition, between the piezoelectric elements 34 along the width direction of the recording head unit 178, an individual wiring 60 that electrically connects the upper electrode 52 of the piezoelectric element 34 and the drive IC 42 is disposed. In addition, an individual wiring portion 62 (which may be a resin adhesive) is separately provided below the partition wall 56. Here, since the individual wiring 60 is disposed on the vibration plate 28, an insulating layer 55 is formed on one end face of the piezoelectric body 50 and the lower electrode 54 so as not to be electrically connected to the individual wiring 60. Yes.

  Although not shown, the top plate 64 has air holes that connect the cavity 58 and the atmosphere so that the air in the cavity 58 can freely travel to and from the atmosphere. The vibration of the piezoelectric element 34 and the diaphragm 28 is not affected.

(Action / Effect)
Next, the operation of the ink jet recording apparatus 112 shown in FIG. 1 will be described.

  In the ink jet recording apparatus 112, the paper P taken out from the paper feed tray 116 is transported on the transport path 122 and is transported onto the transport belt 128. The paper P is transported onto the transport belt 128. Before being pressed against the conveyor belt 128 by the charging roll 136, and is attracted and held on the conveyor belt 128 by the applied voltage from the charging roll 136. In this state, when the paper P passes through the ejection region SE by circulation of the transport belt 128, ink droplets are ejected from the image forming unit 130, and an image is recorded on the surface.

  In the case of recording an image with only one pass, when the image is recorded on the surface of the paper P by passing through the ejection region SE by the transport belt 128, the paper P is peeled from the transport belt 128 by the peeling plate 140 and discharged. Is discharged onto the discharge tray 146.

  On the other hand, when image recording is performed by multi-pass, after the sheet P is circulated by the conveyor belt 128 and passed through the ejection area SE as many times as necessary for image formation, the sheet P is peeled off from the separation plate 140. Is peeled off from the conveyor belt 128 and discharged onto the discharge tray 146 through the discharge path 144.

  Further, in the case of performing image recording on both sides of the paper P, when an image is recorded on the surface of the paper P in the ejection area SE by the transport belt 128, the paper P is peeled from the transport belt 128 by the peeling plate 140, and the reverse path It is conveyed to 152. The sheet P is reversed by the reversing path 152, and an image is recorded on the back surface of the sheet P when it is transported to the transport belt 128 again. When images are formed on both sides in this way, the paper P is transported to the discharge path 144 and discharged onto the paper discharge tray 146.

  By the way, in this embodiment, as shown in FIGS. 4 and 5, the partition wall 56 for forming the cavity 58 in the upper part of the piezoelectric element 34 is formed in a lattice shape between the adjacent piezoelectric elements 34. Provided.

  A plurality of piezoelectric elements 34 are provided corresponding to the nozzles 18 </ b> A, but as shown in FIG. 6A, a piezoelectric element group 204 including a plurality of piezoelectric elements 202 provided in one recording head unit 200. In the case where the partition walls 206 (dot regions) are provided on the outer sides of the recording head units, if the recording head units 200 are arranged in a horizontal row, the adjacent recording head units 200 are adjacent to each other. As a result, the length of the recording head array 208 is increased.

  However, in this embodiment, as shown in FIG. 6B, a partition wall 56 is provided between the adjacent piezoelectric elements 34. That is, since the partition wall 56 is provided in the region where the piezoelectric element group 66 is provided, the partition wall 56 is not formed outside the piezoelectric element group 66. For this reason, in the adjacent recording head unit 178, the piezoelectric element groups 66 are close to each other.

  Therefore, as compared with FIG. 6A, the width of the recording head unit 178 is narrowed, and the length of the recording head array 132 is shortened. That is, the projected area of the recording head array 132 is reduced, and the image forming unit 130 and the inkjet recording apparatus 112 can be downsized.

Further, as shown in FIG. 7A (FIG. 7 is a diagram schematically showing FIG. 6), when a partition wall 206 (dot region) is provided outside the piezoelectric element group 204 (hatched region), When the recording head units 200 are arranged in a horizontal row, the partition walls 206 are adjacent to each other in the adjacent recording head units 200, so that the nozzle formation region (the region in which the piezoelectric element group 204 is provided) of the recording head unit 200. no longer have to increase the width W _1.

However, in this embodiment, as shown in FIG. 7B, in the adjacent recording head unit 178, the piezoelectric element groups 66 (hatched areas) are close to each other, so that compared with FIG. 7A. , the width W ₂ of the nozzle area of the recording head unit 178 (region piezoelectric element group 66 is provided) is narrowed.

  That is, the head width (short direction) of the recording head array 132 becomes narrower, and the projected area of the recording head array 132 becomes smaller. Thereby, the image forming unit 130 and the ink jet recording apparatus 112 can be downsized.

  Here, the partition wall 56 is made of resin, so that even if materials having different linear expansion coefficients are used for the flow path unit 16 and the top plate 64, the partition wall 56 causes a dimensional difference due to thermal deformation. Is absorbed.

  Here, the partition walls 56 are provided in a lattice shape between the piezoelectric elements 34 adjacent to each other. However, the partition walls 56 only need to be provided in the region where the piezoelectric element group 66 is provided. It is not limited.

  For example, as shown in FIG. 8, a linear partition wall 56 may be provided only between the piezoelectric elements 34 adjacent to each other along the width direction of each recording head unit 178. Moreover, the shape of the partition 56 is not limited to these, and may be a columnar column.

  Moreover, since it is necessary to join the partition 56 and the top plate 64 reliably, it is necessary to ensure a sufficient bonding area. For this reason, the partition 56 may be provided outside the piezoelectric element group 66 in addition to the area where the piezoelectric element group 66 is provided. However, by providing the partition 56 in the area where the piezoelectric element group 66 is provided. The width of the partition wall 56 can be made narrower than the width of the partition wall 206 shown in FIG. Therefore, the projected area of the recording head array 132 is smaller than at least in the case of FIG.

  On the other hand, in the present embodiment, as shown in FIG. 4, the glass top plate 64 is bonded to the end face of the resin partition wall 56, but the strength necessary for holding the flow path unit 16 is maintained. Therefore, as shown in FIG. 9, a resin top plate 76 in which a partition wall portion 76 </ b> A and a top plate portion 76 </ b> B constituting the side wall are integrally formed may be used.

  In this case, as shown in FIG. 10, the ink flow connecting the insertion portion 78 or the filter unit 156 through which the FPC 40 connected to the main body device can be inserted into the top plate 76 and the ink supply hole 28 </ b> A formed in the vibration plate 28. By providing the fixing portion 82 to be attached to the path 80 and the support member 135 (see FIG. 4), it is not necessary to provide another member such as a spacer for attaching the support member 135 and the top plate 76, so the number of parts is reduced.

  Further, in the present embodiment, as shown in FIG. 4, the individual wiring portion 62 provided with the individual wiring 60 for connecting the upper electrode 52 of the piezoelectric element 34 to the driving IC 42 (see FIG. 10) is provided below the partition wall 56. Although provided as a separate member, as shown in FIG. 11, a groove portion 56 </ b> A for disposing the individual wiring 60 in the partition wall 56 may be formed. In this case, the partition wall 56 is made of an insulating resin.

  In addition, an electrical wiring board 68 may be provided between the partition wall 56 and the top plate 64 as shown in FIG. A through hole 70 is formed in the electric wiring board 68, and the individual wiring 60 is disposed on the upper surface side of the electric wiring board 68 through the through hole 70.

  Specifically, the partition wall 56 is provided with a hollow portion 72, and a metal paste 74 (gold, silver, or the like) is injected into the through hole 70 and the hollow portion 72 of the electric wiring board 68. Further, the partition wall 56 is disposed so as to overlap a part of the upper electrode 52, and the hollow portion 72 is disposed on the upper electrode 52 so that the metal paste 74 flows directly into the upper electrode 52.

  As a result, as shown in FIG. 4, the wiring area of the individual wiring 60 can be increased as compared with the case where the individual wiring 60 is provided between the piezoelectric elements 34 and 34. Higher density is possible. Here, the top plate 64 and the electrical wiring board 68 are separate members, but electrical wiring may be provided on the top plate 64.

  In the ink jet recording apparatus 112 of the above embodiment, ink droplets are selectively ejected from the recording head unit 178 of each color of black, yellow, magenta, and cyan based on the image data, and a full color image is recorded on the recording paper P. However, the ink jet recording in the present invention is not limited to the recording of characters and images on the recording paper P.

  That is, the recording medium is not limited to paper, and the liquid to be ejected is not limited to ink. For example, industrial uses such as creating color filters for displays by discharging ink onto polymer films or glass, or forming bumps for component mounting by discharging solder in a welded state onto a substrate The ink jet recording apparatus 112 according to the present invention can be applied to all the liquid droplet ejecting apparatuses.

  In the inkjet recording apparatus 112 of the above-described embodiment, an example of a so-called full width array (FWA) corresponding to the paper width has been described. However, the present invention is not limited thereto, and a partial width array (PWA) having a main scanning mechanism and a sub-scanning mechanism. It may be.

  Further, it goes without saying that various other configurations can be taken without departing from the gist of the present invention.

1 is an overall configuration diagram of an ink jet recording apparatus. FIG. 3 is a perspective view showing a recording head array as a droplet discharge device according to the present embodiment. FIG. 3 is a perspective view showing a state in which a recording head array as a droplet discharge device according to the present embodiment is taken out from a holder. 2 is a cross-sectional view showing a recording head unit as a droplet discharge head according to the present embodiment. FIG. FIG. 3 is a plan view showing a main part of a recording head unit as a droplet discharge head according to the present embodiment. (B) is a top view for demonstrating the effect | action of the droplet discharge head which concerns on this Embodiment, (A) is a comparative example of (B). (B) is a conceptual diagram of FIG. 6 (B), and (A) is a comparative example of (B). FIG. 6 is a plan view showing a modification of the main part of a recording head unit as a droplet discharge head according to the present embodiment. FIG. 6 is a cross-sectional view showing a first modification of a recording head unit as a droplet discharge head according to the present embodiment. It is a disassembled perspective view for demonstrating the effect | action of a 1st modification. It is sectional drawing which shows the 2nd modification of the recording head unit as a droplet discharge head concerning this Embodiment. It is sectional drawing which shows the 3rd modification of the recording head unit as a droplet discharge head concerning this Embodiment.

Explanation of symbols

18A Nozzle 28 Diaphragm 32 Pressure chamber 34 Piezoelectric element 56 Bulkhead (supporting part)
58 Cavity (Gap)
60 Individual wiring 64 Top plate (plate material)
68 Electric wiring board (plate material)
76A Bulkhead 76 Top plate 76B Top plate 112 Inkjet recording device (droplet ejection device)
130 Image Forming Unit (Droplet Discharge Device)
132 Recording Head Array (Droplet Discharge Device)
178 Recording head unit (droplet discharge head)

Claims (6)

A plurality of nozzles for discharging droplets;
A pressure chamber connected to each of the nozzles;
A diaphragm constituting a part of the pressure chamber;
Provided on the opposite side of the pressure chamber with the diaphragm interposed therebetween, bends and deforms to eject droplets from the nozzle, and a piezoelectric body and a lower electrode provided on the surface of the piezoelectric body on the diaphragm side A piezoelectric element comprising: an upper electrode provided on a surface of the piezoelectric body opposite to the lower electrode; and
A partition provided at the lower part with an individual wiring part formed only between the adjacent piezoelectric elements and provided with an individual wiring connected to the upper electrode;
A plate member provided on the partition wall and supported by the partition wall to form a gap with the piezoelectric element;
A droplet discharge head characterized by comprising:   The droplet discharge head according to claim 1, wherein the partition walls are arranged in a grid pattern.   The droplet discharge head according to claim 1, wherein the partition wall is formed integrally with the plate member.   4. The liquid droplet ejection head according to claim 1, wherein the individual wiring portion is formed of an insulating resin and includes a groove portion for disposing the individual wiring. 5. .   5. A droplet discharge device comprising a plurality of droplet discharge heads according to claim 1 arranged in a long shape.   6. The droplet discharge device according to claim 5, wherein the droplet discharge heads are arranged in a line.

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