JP2013063552A - Liquid discharge head and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that bubbles in a common liquid chamber at the downstream side more than a filter are moved to a nozzle side, causing discharge failure.SOLUTION: A common liquid chamber 5 is divided in a filter upper common liquid chamber 7 at the upstream side and a filter lower common liquid chamber 8 at the downstream side by a filter 6. A rib 9 which does not intercept a flow of the liquid by contacting the filter 6 is formed in the filter lower common liquid chamber 8. The filter 6 is divided in an area 6a facing to a liquid supply channel 4 to a pressure chamber 3 and an area 6b not facing to the liquid supply channel 4 to the pressure chamber 3 by the rib 9.

Description

  The present invention relates to a liquid discharge head and an image forming apparatus.

  As an image forming apparatus such as a printer, a facsimile, a copying machine, a plotter, or a complex machine of these, for example, a liquid discharge recording type image forming using a recording head composed of a liquid discharge head (droplet discharge head) that discharges ink droplets. Devices such as ink jet recording devices are known.

  In the liquid ejection head, in order to eject droplets from fine nozzles, if dust or bubbles are mixed in the head flow path, the droplet ejection characteristics become unstable or a droplet ejection failure occurs.

  Therefore, conventionally, a filter member that collects foreign matters in the common liquid chamber is arranged (Patent Document 1), and the bubbles that flow into the head are prevented from moving to the pressure chamber or nozzle (Patent Documents 2 to 4). 4) A device that changes the flow velocity on the downstream side of the filter member so that bubbles that have passed through the filter member in the common liquid chamber do not accumulate on the downstream side of the filter member is known (Patent Document 5).

JP 7-329301 A JP 2002-103045 A JP 2002-144550 A JP 2010-23437 A JP 2010-82893 A

  However, in the configuration disclosed in Patent Document 1, the filter corresponds to the nozzle row width. However, when the head is downsized, it is necessary to arrange the filter in a wider range than the nozzle row. In this case, in the common liquid chamber on the downstream side of the filter outside the nozzle row, the flow of the liquid is slowed, so that bubbles are difficult to escape. For such bubbles, the flow velocity distribution of the entire common liquid chamber fluctuates when the flow rate changes, for example, when the number of discharge nozzles suddenly changes, causing bubbles to move from the common liquid chamber to the nozzles and causing defective discharge. There is a risk.

  In the configurations disclosed in Patent Documents 2 to 4, since a bubble reservoir for collecting bubbles is provided, it is possible to suppress bubbles from flowing into the nozzle. However, a dedicated discharge channel is used for discharging bubbles. An extra control mechanism is needed.

  In the configuration disclosed in Patent Document 5, the flow direction of the liquid is made uniform on the downstream side of the filter, but when the flow rate difference between the area where the nozzle is present and the portion where it is not large, such as the common liquid chamber, It is difficult to prevent bubbles from accumulating even if the flow direction is simply made uniform.

  The present invention has been made in view of the above points, and an object thereof is to prevent bubbles on the downstream side of the filter member in the common liquid chamber from moving to the pressure chamber side.

In order to solve the above-described problem, a liquid discharge head according to the present invention includes:
A plurality of nozzles for discharging droplets;
A plurality of pressure chambers communicating with the nozzle;
A common liquid chamber that shares a liquid via a liquid supply path that communicates with the plurality of pressure chambers;
A filter that collects foreign matter contained in the liquid flowing into the common liquid chamber,
The common liquid chamber is divided by the filter into an upstream filter common liquid chamber and a downstream filter lower common liquid chamber,
A rib that does not block the flow of liquid in contact with the filter is formed in the common liquid chamber under the filter,
The filter is configured to be divided into a region facing the liquid supply path to the pressure chamber and a region not facing the liquid supply path to the pressure chamber by the rib.

  The liquid discharge head according to the present invention can prevent bubbles on the downstream side of the filter in the common liquid chamber from moving to the pressure chamber side.

FIG. 3 is an explanatory cross-sectional view along the nozzle arrangement direction of the liquid ejection head according to the first embodiment of the present invention. FIG. 2 is a cross-sectional explanatory view taken along line AA in FIG. 1. It is a cross-sectional explanatory drawing which follows the BB line of FIG. FIG. 3 is a cross-sectional explanatory view taken along line CC in FIG. 1. It is a plane explanatory view of the filter member of the embodiment, and a cross-sectional explanatory view along the DD line. It is a plane explanatory view of the 2nd common liquid chamber member, and a section explanatory view which meets an EE line similarly. FIG. 6 is a cross-sectional explanatory diagram along a nozzle arrangement direction of a liquid ejection head according to a second embodiment of the present invention. It is a plane explanatory view of the 2nd common liquid chamber member of the embodiment, and a section explanatory view which meets a FF line. FIG. 10 is a cross-sectional explanatory diagram along a nozzle arrangement direction of a liquid ejection head according to a third embodiment of the present invention. FIG. 10 is a cross-sectional explanatory view taken along line GG in FIG. 9. It is an expanded sectional explanatory view of the H section of FIG. It is a plane explanatory view of the 2nd common liquid chamber member of the embodiment, and a section explanatory view which meets an II line. FIG. 10 is an explanatory cross-sectional view along a nozzle arrangement direction of a liquid ejection head according to a fourth embodiment of the present invention. It is sectional explanatory drawing which follows the JJ line | wire of FIG. It is an expanded sectional explanatory view of the K section of FIG. It is a plane explanatory view of the 2nd common liquid chamber member of the embodiment, and a sectional explanatory view which meets a LL line. FIG. 10 is a cross-sectional explanatory diagram along a nozzle arrangement direction of a liquid ejection head according to a fifth embodiment of the present invention. It is sectional explanatory drawing which follows the MM line | wire of FIG. FIG. 18 is an explanatory cross-sectional view taken along line NN in FIG. 17. It is sectional explanatory drawing which follows the OO line of FIG. It is plane explanatory drawing of the filter member of the embodiment, sectional explanatory drawing along a PP line, and sectional explanatory drawing along a QQ line. Similarly, it is a plane explanatory view of the second common liquid chamber member and a cross-sectional explanatory view along the line RR. FIG. 10 is a cross-sectional explanatory view along a nozzle arrangement direction of a liquid ejection head according to a sixth embodiment of the present invention. It is sectional explanatory drawing which follows the SS line | wire of FIG. It is sectional explanatory drawing which follows the TT line | wire of FIG. FIG. 26 is an enlarged cross-sectional explanatory diagram of a U portion in FIG. 25. It is a plane explanatory view of the diaphragm member of the embodiment. FIG. 10 is an explanatory cross-sectional view along the nozzle arrangement direction of a liquid ejection head according to a seventh embodiment of the present invention. It is sectional explanatory drawing which follows the VV line | wire of FIG. It is sectional explanatory drawing which follows the WW line of FIG. FIG. 31 is an enlarged cross-sectional explanatory view of a portion X in FIG. 30. It is plane explanatory drawing of the 2nd common liquid chamber member of the embodiment, sectional explanatory drawing along a YY line, sectional explanatory drawing along a ZZ line, and sectional explanatory drawing along an A1-A1 line. 1 is a schematic side view illustrating a mechanism unit of an example of an image forming apparatus according to the present invention. It is principal part plane explanatory drawing of the mechanism part.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. A liquid discharge head according to a first embodiment of the present invention will be described with reference to FIGS. 1 is a cross-sectional explanatory view along the nozzle arrangement direction of the head, FIGS. 2 to 4 are cross-sectional explanatory views along the lines AA, BB, and CC in FIG. 1, and FIG. 5 is a filter member. FIG. 6 is an explanatory plan view of the second common liquid chamber member and an explanatory sectional view taken along the line E-E.

  In the liquid discharge head, the nozzle plate 12, the flow path plate 13, and the vibration plate member 14 are joined.

  In the nozzle plate 12, a plurality of nozzles 1 for discharging droplets are arranged in two rows in a staggered manner. For the nozzle plate 12, the nozzle 1 was formed by press working using, for example, stainless steel (here, SUS316).

  The flow path plate 13 forms a pressure chamber 3 that communicates with the nozzle 1. This flow path plate 13 was formed by press working using, for example, stainless steel (here, SUS304), and post-processing was performed so that deformation and burrs caused by the press became substantially flat by double-side polishing.

  The diaphragm member 14 forms a part of the wall surface of the pressure chamber 3 as a displaceable vibration region 14a. In addition, a liquid supply path 4 is formed in the diaphragm member 14 so as to face the below-filter common liquid chamber 8, which will be described later, and through the under-filter common liquid chamber 8 and each pressure chamber 3. The diaphragm member 14 has a three-layer structure and is formed by Ni electroforming.

  A second common liquid chamber member 15, a filter member 16, and a first common liquid chamber member 17 that also serves as a frame of the head are laminated and bonded to the side of the diaphragm member 14 opposite to the pressure chamber 3.

  A common liquid chamber 5 communicating with each pressure chamber 3 is formed by the first common liquid chamber member 17 and the second common liquid chamber member 15. The filter member 16 is formed with a filter 6 for collecting foreign matter.

  Thereby, the common liquid chamber 5 is separated from the filter 6 by the filter 6 of the filter member 16 interposed between the first common liquid chamber member 17 and the second common liquid chamber member 15. And the downstream filter common liquid chamber 8.

  In the second common liquid chamber member 15, a rib 9 that is in contact with the filter 6 of the filter member 16 and does not block the liquid flow at a position corresponding to the nozzle row end side is orthogonal to the nozzle arrangement direction ( (Short direction of the head). That is, the rib lower flow path 10 is formed on the rib 9 on the diaphragm member 14 side. The rib 9 divides the filter 6 into a region 6 a facing the liquid supply path 4 to the pressure chamber 3 and a region 6 b not facing the liquid supply path 4 to the pressure chamber 3.

  The common liquid chamber 8 under the filter is connected to the chamber portion 8 a facing the liquid supply path 4 to the pressure chamber 3 and the liquid supply path 4 to the pressure chamber 3, which are communicated by the rib 9 with the rib lower flow path 10. It is divided into a chamber portion 8b that does not face.

  Here, the filter member 16 is formed of Ni by electroforming. The filter 6 is disposed in the same range as the length and width of the common liquid chamber 5. Therefore, the length of the filter 6 in the nozzle arrangement direction is longer than the length of the nozzle row.

  As described above, the second common liquid chamber member 15 forms the rib 9 and the rib lower flow path 10 at a position slightly outside the length of the common liquid chamber 8 under the filter and the nozzle row. The width of the rib 9 in the nozzle arrangement direction is formed in a range narrower than the pitch of the nozzles 1 and is provided so as to cross the common liquid chamber 5, that is, in a direction orthogonal to the nozzle arrangement direction.

  The second common liquid chamber member 15 is made of stainless steel (SUS304 in this case), the common liquid chamber 8 under the filter is formed by full etching (through), and the ribs 9 are formed by half etching. By using half-etching, the cross-sectional area of the rib lower passage 10 can be determined by the etching amount. In addition, the rib lower flow path 10 can also be formed by press work.

  The first common liquid chamber member 17 forms the filter common liquid chamber 7 and is provided with a liquid supply port 11 for supplying a liquid from the outside. The liquid supply ports 11 are arranged at both ends in the longitudinal direction of the filter common liquid chamber 7. The liquid supply port 11 is disposed at the end of the filter 6.

  The first common liquid chamber member 17 is formed by cutting SUS303, but may be formed by, for example, resin injection molding.

  In addition, a piezoelectric actuator 20 is disposed on the vibration member 14 on the opposite side of the vibration region 14 a from the pressure chamber 3. In the piezoelectric actuator 20, two piezoelectric members 18 in which columnar piezoelectric elements (piezoelectric columns) are formed at one half of the nozzle pitch, for example, are joined to one base member 19 in accordance with two nozzle rows. Each piezoelectric column of the piezoelectric member 18 is joined to the vibration region 14a of the diaphragm member 14, and a drive signal is given through a wiring member (not shown).

  In order to provide the piezoelectric actuator 20, the filter member 16 and the second common liquid chamber member 15 are provided with an opening 21 for inserting a piezoelectric actuator, as shown in FIGS. Further, the portion of the diaphragm member 14 that forms the wall surface of the chamber portion 18b of the lower filter common liquid chamber 8 is a deformable damper region 27, and the flow path plate 13 has a lower filter common liquid chamber 8 in the damper region 27. A damper chamber 28 is formed on the opposite side.

  In this liquid discharge head, the piezoelectric actuator 20 is driven to displace the vibration region 14 a of the vibration plate member 14, so that the liquid in the pressure chamber 3 is pressurized and liquid droplets are discharged from the nozzle 1.

  When assembling the liquid discharge head, first, the nozzle plate 12, the flow path plate 13, and the diaphragm member 14 are joined together, and then the second common liquid chamber member 15 and the filter member 16 are joined to the diaphragm member 14. To do. Next, the piezoelectric actuator 20 is joined to the diaphragm member 14. Finally, the first common liquid chamber member 17 is joined to the filter member 16.

  Next, the flow of bubbles when filling the liquid discharge head will be described.

  While the liquid is filled into the common liquid chamber 5 from any one of the liquid supply port portions 11 of the first common liquid chamber member 17, the liquid and the bubbles generated during filling are discharged from the liquid supply port portion 11 on the opposite side.

  Next, liquid is filled on the nozzle side. At this time, if bubbles enter the common liquid chamber 8 under the filter located outside the nozzle row in the nozzle arrangement direction, it becomes difficult to move because the flow velocity is slow. In this case, if a strong force such as choke suction is applied, the bubbles can be discharged, but it is difficult to eliminate them completely.

  Here, since the ribs 9 are provided in the vicinity of the nozzle row end in the nozzle arrangement direction of the filter 6, as described above, the chamber portion 8b of the lower filter common liquid chamber 8 located outside the nozzle row in the nozzle arrangement direction. Even if air bubbles remain on the surface, the air bubbles can be trapped by the rib 9. Since the bubbles move in the direction opposite to the gravity, if the rib 9 is disposed only on the side (upper side) in contact with the filter 6, the bubbles can be trapped.

  Thereby, bubbles remaining in the chamber portion 8b of the lower filter common liquid chamber 8 located outside the nozzle row in the nozzle arrangement direction do not enter the chamber portion 8a facing the liquid supply path 4 beyond the rib 9, and pressure It is possible to prevent bubbles from entering the chamber 3 and the nozzle 1 to cause a droplet ejection failure (bending in the ejection direction or inability to eject the droplet). It is possible to perform stable droplet discharge over a long period of time.

  A liquid discharge head according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a sectional explanatory view along the nozzle arrangement direction of the head, and FIG. 8 is a plan explanatory view of the second common liquid chamber member and a sectional explanatory view along the line FF.

  In this embodiment, the rib 9 of the second common liquid chamber member 15 is formed so that the width L1 in the nozzle arrangement direction on the side close to the nozzle 1 is wider than the width L2 on the side far from the nozzle 1 when viewed in plan. . Accordingly, when viewed from the flow of the liquid, the fluid resistance due to the rib 9 is large on the side close to the nozzle 1, and the fluid resistance due to the rib 9 is small on the far side.

  With this configuration, when liquid is ejected with a high duty (high frequency driving), even if liquid is drawn from both ends of the nozzle row, bubbles do not cross the rib 9. That is, by performing high-frequency driving, a large amount of liquid is drawn, so that the bubbles easily move. However, by increasing the fluid resistance on the side close to the nozzle 1, the bubbles do not easily cross the rib 9. You can

  Next, a liquid ejection head according to a third embodiment of the present invention will be described with reference to FIGS. 9 is a cross-sectional explanatory view taken along the nozzle arrangement direction of the head, FIG. 10 is a cross-sectional explanatory view taken along the line GG in FIG. 9, FIG. 11 is an enlarged cross-sectional explanatory view of a portion H in FIG. It is a plane explanatory view of a common liquid chamber member, and a sectional explanatory view which meets an II line.

  In the present embodiment, in the second embodiment, among the plurality of liquid supply paths 4, the liquid supply paths 4 at both ends in the nozzle arrangement direction are provided at positions facing the ribs 9. The liquid supply path 4 is opened to the rib lower flow path 10.

  With this configuration, when the bubbles accumulated in the chamber portion 8b of the common liquid chamber 8 under the filter are discharged, the bubbles can be discharged only from the nozzles 2 at both ends in the nozzle arrangement direction. It becomes easy.

  In other words, in the case where the configuration is not such, if the bubbles exceeding the rib 9 move to the side in contact with the filter 6 again, they are trapped by the filter 6 and are difficult to discharge. As in the present embodiment, even when air bubbles accumulate over the ribs 9, the air bubbles can be discharged before the air bubbles move to the region 6 a of the filter 6 by collecting the air bubbles in a narrow portion of the rib lower flow path 10. The reliability of the bubble discharge process is improved. The nozzles at both ends in the nozzle arrangement direction may be dummy nozzles that do not discharge liquid.

  Next, a liquid discharge head according to a fourth embodiment of the invention will be described with reference to FIGS. 13 is a cross-sectional explanatory view taken along the nozzle arrangement direction of the head, FIG. 14 is a cross-sectional explanatory view taken along the line JJ in FIG. 13, FIG. 15 is an enlarged cross-sectional explanatory view of a portion K in FIG. It is a plane explanatory view of a common liquid chamber member, and a sectional explanatory view which meets a LL line.

  In the present embodiment, in the third embodiment, the liquid supply path 4 a communicating with the nozzles 1 at both ends of the nozzle array has a length in a direction orthogonal to the nozzle array direction, and the nozzle array direction of the other liquid supply paths 4. It is formed longer than the length in the orthogonal direction. Here, the length of the liquid supply path 4a at both ends of the nozzle array in the direction orthogonal to the nozzle array direction is equal to the width of the direction perpendicular to the nozzle array direction of the rib lower flow path 10 (perpendicular to the nozzle array direction of the common liquid chamber). Same as width).

  By comprising in this way, the bubble which passes the rib lower flow path 10 from the chamber part 8b of the filter lower common liquid chamber 8 can be discharged | emitted reliably.

  Next, a liquid ejection head according to a fifth embodiment of the invention will be described with reference to FIGS. 17 is a cross-sectional explanatory view taken along the nozzle arrangement direction of the head, FIGS. 18 to 20 are cross-sectional explanatory views taken along lines MM, NN, and OO in FIG. 17, and FIG. 21 is a filter member. FIG. 22 is an explanatory plan view of the second common liquid chamber member and a sectional explanatory view along the line RR. FIG. 22 is an explanatory plan view of the second common liquid chamber member. .

  In the present embodiment, the nozzles at both ends of the nozzle row of the nozzle plate 12 are dummy nozzles 2a that are not used for image formation. Here, the dummy nozzle 2a and the dummy pressure chamber 3a through which the dummy nozzle 2a communicates are different in size from the nozzle 1 and the pressure chamber 3 used for image formation, and have a shape in which bubbles are easily discharged. Further, the liquid supply path 4 leading to the dummy pressure chamber 3a also becomes a dummy liquid supply path 4b.

  Further, the second common liquid chamber member 15 is provided with ribs 9 that are in contact with the filter 6 of the filter member 16 and that do not block the liquid flow outside the liquid supply path 4 in a direction orthogonal to the nozzle arrangement direction. It is provided along the direction (longitudinal direction of the head). That is, the rib lower flow path 10 is formed on the rib 9 on the diaphragm member 14 side. The rib 9 divides the filter 6 into a region 6 a facing the liquid supply path 4 to the pressure chamber 3 and a region 6 b not facing the liquid supply path 4 to the pressure chamber 3.

  The common liquid chamber 8 under the filter is connected to the chamber portion 8 a facing the liquid supply path 4 to the pressure chamber 3 and the liquid supply path 4 to the pressure chamber 3, which are communicated by the rib 9 with the rib lower flow path 10. It is divided into a chamber portion 8b that does not face.

  In the present embodiment, the damper region 27 that can be deformed by the filter member 16 is formed, and the damper chamber 28 is formed by the second common liquid chamber member 15.

  The flow of bubbles during liquid filling in this embodiment will be described.

  While the liquid is filled into the common liquid chamber 5 from any one of the liquid supply port portions 11 of the first common liquid chamber member 17, the liquid and the bubbles generated during filling are discharged from the liquid supply port portion 11 on the opposite side.

  Next, ink is filled on the nozzle side. The bubbles can be discharged through the nozzle 2 by being pressurized from the upstream side of the liquid supply port 11 or sucked from the nozzle 2 side. By this pressurization or suction, the bubbles can move over the rib 9 and move to the nozzle 2 side.

  By the way, the bubbles may be sucked into the head from the nozzle 2 side not only at the time of filling but also by an unexpected operation. At this time, if a proper bubble discharging operation is performed, the bubble can be discharged. However, if the bubble enters during printing for some reason, it is necessary to prevent the bubble from moving to the nozzle 2 side.

  In the present embodiment, the under-filter common liquid chamber 8 is divided into two sides, the side close to the liquid supply path 4 (chamber part 8a) and the far side (chamber part 8b). In the chamber part 8a close to the liquid supply path 4, Since the liquid flow rate can be increased, bubbles are discharged from the nozzle 2 via the pressure chamber 3. On the other hand, in the chamber portion 8b far from the liquid supply path 4, the flow velocity is slow, so that it is difficult to discharge the bubbles.

  Therefore, the rib 9 is provided so that the chamber portion 8b far from the liquid supply path 4 cannot be easily moved to the chamber portion 8a near the liquid supply path 4.

  As a result, even if bubbles that could not be removed in the normal printing state remain, they are trapped by the rib 9 and can be prevented from entering the pressure chamber 3 from the liquid supply path 4.

  In addition, since the dummy nozzle 2a, the dummy pressure chamber 3a, and the dummy liquid supply path 4b (collectively referred to as “dummy channel”) are provided at both ends of the nozzle row, the accumulated bubbles are discharged from the dummy channel. It is possible. In this case, it is preferable to increase the suction force for the dummy channel.

  Next, a liquid ejection head according to a sixth embodiment of the present invention will be described with reference to FIGS. 23 is a cross-sectional explanatory view along the nozzle arrangement direction of the head, FIGS. 24 and 25 are cross-sectional explanatory views along the SS line and the TT line of FIG. 23, and FIG. 26 is an enlarged view of the U portion of FIG. Cross-sectional explanatory drawing and FIG. 27 are plan explanatory views of the diaphragm member.

  In the present embodiment, the guide member 24 that extends the dummy liquid supply path 4b to the diaphragm member 14 up to a region 6b where the filter does not face the liquid supply path, that is, the position facing the chamber portion 8b in the common liquid chamber 8 below the filter. Is forming.

  In this embodiment, the guiding portion 24 has a three-layer structure including the first layer 14A to the third layer 14C, the vibration region 14a is formed by the first layer 14A, and the guiding portion 24 is formed by patterning. 2. The first layer 14A is surrounded by the third layers 14B and 14C to form a groove.

  That is, when performing the above-described liquid filling and bubble discharge, in order to discharge the bubbles remaining in the chamber portion 8b of the common liquid chamber 8 under the filter from the nozzle 2 beyond the rib 9, the resistance is large and the pressure or suction is increased. It is necessary to increase power.

  Therefore, by providing a guiding portion 24 that leads from the chamber portion 8b of the lower filter common liquid chamber 8 to the dummy liquid supply path 4b, bubbles in the chamber portion 8b of the lower filter common liquid chamber 8 are transferred from the guiding portion 24 to the dummy liquid supply path. It becomes easy to move to 4b. Thereby, the pressurizing force and suction output when the bubbles are discharged from the dummy nozzle 2a can be suppressed. In addition, discharge | emission becomes easier by making the dimension of the dummy nozzle 2a into a dimension (for example, enlarging a nozzle diameter) which is easy to discharge a bubble.

  Next, a liquid ejection head according to a seventh embodiment of the present invention will be described with reference to FIGS. 28 is a cross-sectional explanatory view along the nozzle arrangement direction of the head, FIGS. 29 and 30 are cross-sectional explanatory views along the VV line and the WW line of FIG. 28, and FIG. 31 is an enlarged view of the portion X in FIG. FIG. 32 is a sectional explanatory view, FIG. 32 is a plan explanatory view of the second common liquid chamber member, a sectional explanatory view along the YY line, a sectional explanatory view along the ZZ line, and a sectional explanatory view along the A1-A1 line.

  In the present embodiment, in the sixth embodiment, the guiding portion 29 is also provided on the second common liquid chamber member 15 side by not forming the rib 9 in the portion facing the guiding portion 24. In other words, on the rib 9 side, a guide portion 29 is provided which is formed by a groove portion in a direction orthogonal to the nozzle arrangement direction, in the same direction as the dummy liquid supply path 4b in the direction along the nozzle arrangement direction. The guiding portion 29 in this case can be formed by, for example, pressing.

  With this configuration, air bubbles can move from the chamber portion 8b of the under-filter common liquid chamber 8 to the dummy liquid supply path 4b through the portion without the rib 9 (leading portion 29). Bubbles in the chamber portion 8b are more easily moved to the dummy liquid supply path 4b. Thereby, the pressurizing force and suction output when the bubbles are discharged from the dummy nozzle 2a can be suppressed.

  In the above-described embodiment, the wall surface member forming the wall surface of the individual flow path constituting the flow path member is described as a piezoelectric head that is a diaphragm member, but the substrate provided with the heating resistor is the wall surface. The present invention can be similarly applied to a thermal head as a member and other electrostatic heads.

  Also, a head-integrated liquid cartridge (cartridge-integrated head) can be obtained by integrating the above-described liquid discharge head and a tank that supplies liquid to the liquid discharge head.

  Next, an example of the image forming apparatus according to the present invention including the liquid discharge head according to the present invention will be described with reference to FIGS. FIG. 33 is an explanatory side view of the mechanism portion of the apparatus, and FIG.

  This image forming apparatus is a serial type image forming apparatus, and a carriage 233 is slidably held in the main scanning direction by main and slave guide rods 231 and 232 which are guide members horizontally mounted on the left and right side plates 221A and 221B. The main scanning motor that does not perform moving scanning in the direction indicated by the arrow (carriage main scanning direction) via the timing belt.

  The carriage 233 is supplied with ink supplied to the same head as the liquid discharge head according to the present invention for discharging ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). A recording head 234 with an integrated tank is arranged in a sub-scanning direction orthogonal to the main scanning direction with a nozzle row composed of a plurality of nozzles, and is mounted with the ink droplet ejection direction facing downward.

  Each of the recording heads 234 has two nozzle rows, and one nozzle row of one recording head 234a has a black (K) droplet, the other nozzle row has a cyan (C) droplet, and the other nozzle row has the other nozzle row. One nozzle row of the recording head 234b discharges magenta (M) droplets, and the other nozzle row discharges yellow (Y) droplets. Here, a configuration in which droplets of four colors are ejected in a two-head configuration is used, but it is also possible to arrange four nozzle rows per head and eject each of the four colors with one head.

  Further, the ink of each color is replenished and supplied from the ink cartridge 210 of each color to the tank 235 of the recording head 234 via the supply tube 236 of each color.

  On the other hand, as a paper feeding unit for feeding the paper 242 stacked on the paper stacking unit (pressure plate) 241 of the paper feed tray 202, a half-moon roller (feeding) that separates and feeds the paper 242 one by one from the paper stacking unit 241. A separation pad 244 made of a material having a large coefficient of friction is provided opposite to the sheet roller 243 and the sheet feeding roller 243, and the separation pad 244 is urged toward the sheet feeding roller 243 side.

  A guide 245 for guiding the paper 242, a counter roller 246, a conveyance guide member 247, and a tip pressure roller 249 are used to feed the paper 242 fed from the paper feeding unit to the lower side of the recording head 234. And a holding belt 251 which is a conveying means for electrostatically attracting the fed paper 242 and conveying it at a position facing the recording head 234.

  The conveyor belt 251 is an endless belt, and is configured to wrap around the conveyor roller 252 and the tension roller 253 so as to circulate in the belt conveyance direction (sub-scanning direction). In addition, a charging roller 256 that is a charging unit for charging the surface of the transport belt 251 is provided. The charging roller 256 is disposed so as to come into contact with the surface layer of the conveyor belt 251 and to rotate following the rotation of the conveyor belt 251. The transport belt 251 rotates in the belt transport direction when the transport roller 252 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 242 recorded by the recording head 234, a separation claw 261 for separating the paper 242 from the transport belt 251, a paper discharge roller 262, and a paper discharge roller 263 are provided. A paper discharge tray 203 is provided below the paper discharge roller 262.

  A double-sided unit 271 is detachably attached to the back surface of the apparatus main body. The duplex unit 271 takes in the paper 242 returned by the reverse rotation of the transport belt 251, reverses it, and feeds it again between the counter roller 246 and the transport belt 251. The upper surface of the duplex unit 271 is a manual feed tray 272.

  Further, a maintenance / recovery mechanism 281 that is a head maintenance / recovery device according to the present invention includes a recovery means for maintaining and recovering the nozzle state of the recording head 234 in the non-printing area on one side of the carriage 233 in the scanning direction. Is arranged. The maintenance / recovery mechanism 281 includes cap members (hereinafter referred to as “caps”) 282a and 282b (hereinafter referred to as “caps 282” when not distinguished) for capping each nozzle surface of the recording head 234, and nozzle surfaces. A wiper blade 283 that is a blade member for wiping the ink, and an empty discharge receiver 284 that receives liquid droplets for discharging the liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid. ing.

  Further, in the non-printing area on the other side in the scanning direction of the carriage 233, there is an empty space for receiving a liquid droplet when performing an empty discharge for discharging a liquid droplet that does not contribute to the recording in order to discharge the recording liquid thickened during the recording. A discharge receiver 288 is disposed, and the idle discharge receiver 288 is provided with an opening 289 along the nozzle row direction of the recording head 234 and the like.

  In this image forming apparatus configured as described above, the sheets 242 are separated and fed one by one from the sheet feeding tray 202, and the sheet 242 fed substantially vertically upward is guided by the guide 245, and is conveyed to the conveyor belt 251 and the counter. It is sandwiched between the rollers 246 and conveyed, and further, the leading end is guided by the conveying guide 237 and pressed against the conveying belt 251 by the leading end pressing roller 249, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately applied to the charging roller 256, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 251 alternates, that is, in the sub-scanning direction that is the circumferential direction. , Plus and minus are alternately charged in a band shape with a predetermined width. When the sheet 242 is fed onto the conveyance belt 251 charged alternately with plus and minus, the sheet 242 is attracted to the conveyance belt 251, and the sheet 242 is conveyed in the sub scanning direction by the circumferential movement of the conveyance belt 251.

  Therefore, by driving the recording head 234 according to the image signal while moving the carriage 233, ink droplets are ejected onto the stopped paper 242 to record one line, and after the paper 242 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 242 has reached the recording area, the recording operation is finished and the paper 242 is discharged onto the paper discharge tray 203.

  As described above, since the image forming apparatus includes the liquid discharge head according to the present invention as a recording head, a high-quality image can be stably formed.

  In the present application, the “paper” is not limited to paper, but includes OHP, cloth, glass, a substrate, etc., and means a material to which ink droplets or other liquids can be attached. , Recording media, recording paper, recording paper, and the like. In addition, image formation, recording, printing, printing, and printing are all synonymous.

  The “image forming apparatus” means an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. “Formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply causing a droplet to land on the medium). ) Also means.

  The “ink” is not limited to an ink unless otherwise specified, but includes any liquid that can form an image, such as a recording liquid, a fixing processing liquid, or a liquid. Used generically, for example, includes DNA samples, resists, pattern materials, resins, and the like.

  In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

  Further, the image forming apparatus includes both a serial type image forming apparatus and a line type image forming apparatus, unless otherwise limited.

2 Nozzle 3 Pressure chamber 4 Liquid supply path 5 Common liquid chamber 6 Filter 7 Filter common liquid chamber 8 Filter common liquid chamber 9 Rib 10 Rib lower flow path 12 Nozzle plate 13 Flow path plate 14 Vibration plate member 15 Second common liquid chamber Member 16 Filter member 17 First common liquid chamber member 20 Piezoelectric actuator 24, 29 Guide portion 233 Carriage 234a, 234b Recording head

Claims (10)

A plurality of nozzles for discharging droplets;
A plurality of pressure chambers communicating with the nozzle;
A common liquid chamber that shares a liquid via a liquid supply path that communicates with the plurality of pressure chambers;
A filter that collects foreign matter contained in the liquid flowing into the common liquid chamber,
The common liquid chamber is divided by the filter into an upstream filter common liquid chamber and a downstream filter lower common liquid chamber,
A rib that does not block the flow of liquid in contact with the filter is formed in the common liquid chamber under the filter,
The liquid ejection head according to claim 1, wherein the filter is divided by the rib into a region facing the liquid supply path to the pressure chamber and a region not facing the liquid supply path to the pressure chamber.   The liquid ejection head according to claim 1, wherein the rib is provided in a direction orthogonal to a nozzle arrangement direction.   3. The rib according to claim 2, wherein the rib is formed so that a width in a nozzle arrangement direction on a side closer to the nozzle is wider than a width in a nozzle arrangement direction on a side far from the nozzle as viewed in a plan view. Liquid discharge head.   4. The liquid discharge head according to claim 2, wherein a liquid supply path at both ends of the liquid supply path in the nozzle arrangement direction faces the rib. 5.   The length in the direction orthogonal to the nozzle arrangement direction of the liquid supply path at both ends of the nozzle arrangement direction is longer than the length in the direction orthogonal to the nozzle arrangement direction of the other liquid supply path. Liquid discharge head.   The liquid ejection head according to claim 1, wherein the rib is provided in a direction along a nozzle arrangement direction.   The liquid discharge head according to claim 6, wherein the nozzles at both ends in the nozzle arrangement direction are dummy nozzles that do not contribute to image formation.   The liquid discharge head according to claim 7, further comprising a guiding portion that extends the liquid supply path corresponding to the dummy nozzle to a region where the filter does not face the liquid supply path.   9. The liquid ejection head according to claim 7, wherein the rib is formed with a groove portion in a direction orthogonal to the nozzle arrangement direction in a portion corresponding to the dummy nozzle in the nozzle arrangement direction.   An image forming apparatus comprising the liquid discharge head according to claim 1.

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