JP6597777B2 - Inkjet head, bubble removal method for inkjet head, and inkjet recording apparatus - Google Patents

Description

  The present invention relates to an ink jet head, a method for removing bubbles in an ink jet head, and an ink jet recording apparatus, and more specifically, an ink jet head capable of efficiently removing residual bubbles in an ink storage chamber equipped with a filter, a method for removing air bubbles in an ink jet head, and The present invention relates to an ink jet recording apparatus.

  In an ink jet head, bubbles in an ink storage chamber (also referred to as a common ink chamber) that stores ink to be supplied in common to a plurality of pressure chambers remain in the pressure chamber or in the vicinity of the pressure chamber, so Ink ejection may be affected. In particular, an ink jet head provided with an ink storage chamber with a filter for preventing contaminants and bubbles in the ink from flowing into the pressure chamber has an air bubble attached under the filter (pressure chamber side). Bubbles may flow into the pressure chamber and affect ink ejection.

  Conventionally, in an ink jet head equipped with a filter, an ink storage chamber is divided into an upstream side and a downstream side by a filter, and an ink inlet and a circulation outlet are provided in the upstream ink chamber, whereby ink is circulated on the upstream side to generate bubbles. Is known (Patent Document 1). However, since the circulating flow only passes through the ink chamber on the upstream side of the filter, the bubbles remaining under the filter cannot be discharged to the outside.

  In addition, when the filter is in the second state by providing the filter to be rotatable between a first state in which the liquid passes through the filter and a second state in which the liquid flows along the filter, the filter An ink jet head that discharges bubbles adhering to the outside is also known (Patent Document 2). However, in this case, a rotation mechanism for rotating the filter is required, and there is a problem that the structure of the inkjet head is complicated.

  For this reason, in addition to the ink inflow path and the ink discharge path, a bubble removal path communicating with the downstream side of the filter via a filter is provided in the ink storage chamber, and the ink is pressurized and introduced from the ink inflow path, and bubbles are passed through the filter. An ink jet head has been proposed in which bubbles remaining on the downstream side of the filter are removed by flowing out from the extraction path (Patent Document 3).

JP 2006-263996 A JP 2012-799 A JP 2012-218398 A

  However, in the ink jet head described in Patent Document 3, in order to actually cause the bubbles under the filter to flow out of the bubble removal path, the ink must be allowed to flow from the ink inflow path with the ink discharge path on the upstream side of the filter closed. Don't be. Since the filter has a pressure loss, the ink outflow on the upstream side of the filter is given priority even if the ink flows in from the ink inflow path. For this reason, it is necessary to provide an opening / closing valve such as a solenoid valve in the ink discharge path on the upstream side of the filter, and to control the opening / closing when removing bubbles.

  In addition, in order to completely remove bubbles in the ink storage chamber, it is necessary to separately execute the step of flowing out the ink upstream of the filter and the step of flowing out the ink downstream of the filter while controlling the on-off valve. There is also a problem that the time for removing bubbles and the ink consumption during that time increase.

  Accordingly, an object of the present invention is to provide an inkjet head, an inkjet head bubble removal method, and an inkjet recording apparatus that can efficiently remove residual bubbles in an ink storage chamber provided with a filter.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

1.
A nozzle that ejects ink; a pressure chamber that communicates with the nozzle; an ink manifold that forms an ink reservoir chamber that communicates with the pressure chamber; and a filter disposed within the ink manifold, wherein the ink reservoir chamber comprises: And an upstream ink chamber far from the pressure chamber and a downstream ink chamber near the pressure chamber, and an inflow path and a first outflow path communicate with the upstream ink chamber, respectively. An inkjet head in which a second outflow path communicates with the downstream ink chamber without passing through the filter,
A pressure loss is applied to the first outflow path and / or ink is sucked from the second outflow path and the ink flowing into the upstream ink chamber from the inflow path is passed through the filter to the downstream ink chamber. The ink jet head is configured so that ink flows simultaneously into the upstream ink chamber and the downstream ink chamber by causing the ink to also flow.
2.
2. The ink jet head according to 1, wherein a flow rate adjusting member is provided in the first outflow path so as to impart pressure loss by partially narrowing a cross-sectional area of the first outflow path.
3.
3. The inkjet head according to 2, wherein the flow rate adjusting member is a constricting member that is held in the first outflow path and partially reduces the flow path of the first outflow path.
4).
4. The ink jet head according to 1, 2, or 3, wherein a suction pump that sucks ink from the second outflow path is provided in the second outflow path.
5.
5. The ink jet head according to 4, wherein the inner diameter of the second outflow path is smaller than the inner diameter of the first outflow path.
6).
The inkjet head according to any one of 1 to 5, wherein the first outflow path and the second outflow path are joined together by a pipe connecting member.
7).
7. The ink jet head according to 6, wherein a check valve is provided in the second outflow path.
8).
A nozzle that ejects ink; a pressure chamber that communicates with the nozzle; an ink manifold that forms an ink reservoir chamber that communicates with the pressure chamber; and a filter disposed within the ink manifold, wherein the ink reservoir chamber comprises: And an upstream ink chamber far from the pressure chamber and a downstream ink chamber near the pressure chamber, and an inflow path and a first outflow path communicate with the upstream ink chamber, respectively. A method for removing bubbles in an ink jet head, wherein a second outflow path communicates with the downstream ink chamber without passing through the filter, and ink is allowed to flow in from the inflow path to remove residual bubbles in the ink storage chamber. Because
A pressure loss is applied to the first outflow path and / or ink is sucked from the second outflow path and the ink flowing into the upstream ink chamber from the inflow path is passed through the filter to the downstream ink chamber. Ink jet air bubble removal method in which ink is allowed to flow simultaneously into the upstream ink chamber and the downstream ink chamber.
9. 9. The method for removing bubbles in an inkjet head according to 8, wherein a pressure loss is applied to the first outflow path by providing a flow rate adjusting member that partially narrows a cross-sectional area of the first outflow path.
10.
10. The method of removing air bubbles in an ink jet head according to 9, wherein the flow rate adjusting member is a constricting member that is held in the first outflow path and partially reduces the flow path of the first outflow path.
11.
11. The method of removing bubbles in an ink jet head according to 8, 9, or 10, wherein ink is sucked from the second outflow path by providing a suction pump in the second outflow path.
12
12. The method for removing bubbles in an ink jet head according to 11, wherein the inner diameter of the second outflow path is smaller than the inner diameter of the first outflow path.
13.
The method for removing bubbles of an ink jet head according to any one of 8 to 12, wherein the first outflow path and the second outflow path are joined together by a pipe connection portion.
14
14. The method of removing bubbles in an ink jet head according to 13, wherein a check valve is provided in the second outflow path.
15.
The inkjet head according to any one of 1 to 7;
An ink tank for storing ink to be supplied to the inkjet head;
An ink jet recording apparatus comprising: an ink supply unit that supplies ink in the ink tank to the ink jet head.

  ADVANTAGE OF THE INVENTION According to this invention, the inkjet head which can remove efficiently the residual bubble of the ink storage chamber provided with the filter, the bubble removal method of an inkjet head, and an inkjet recording device can be provided.

1 is a schematic configuration diagram of a main part showing an example of an ink jet recording apparatus according to the present invention. Partial enlarged sectional view of the inkjet head shown in FIG. The perspective view which shows an example of the constriction member which shows the state which notched the 1st outflow pipe partially (A) (b) is a figure explaining the bubble removal method which concerns on this invention Schematic configuration diagram showing another example of the inkjet head according to the present invention in a partial cross section

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Inkjet recording device)
FIG. 1 is a schematic configuration diagram of a main part showing an example of an ink jet recording apparatus according to the present invention, and shows a partial cross section of an ink jet head.

  The ink jet recording apparatus 100 records an image by ejecting ink from the ink jet head 1 onto a recording medium transported in a certain direction (sub-scanning direction) by a transport unit (not shown). The ink jet head 1 is mounted on a carriage (not shown), and ejects ink from a nozzle toward a recording medium in the process of moving the carriage along the main scanning direction. In the ink jet recording apparatus 100 shown in the present embodiment, the ink jet head 1 is installed such that main scanning is performed in the horizontal direction and the ink ejection direction from the nozzles is downward in the vertical direction.

  In FIG. 1, only one inkjet head 1 is shown, but in general, the inkjet recording apparatus 100 includes, for example, yellow (Y), magenta (M), cyan (C), and K (black) ink colors. A plurality of inkjet heads 1 are provided. In the ink jet recording apparatus 100 shown in the present embodiment, an ink tank 101 for storing ink and the ink jet head 1 are communicated with each other by an ink supply pipe 102 and an ink return pipe 103.

  A circulation pump 105 that is driven and controlled by the control unit 104 of the inkjet recording apparatus 100 is provided in the middle of the ink supply pipe 102. When the circulation pump 105 is driven, the ink in the ink tank 101 is supplied to the inkjet head 1 via the ink supply pipe 102, and the ink (ink including bubbles and the like) is supplied from the inkjet head 1 to the ink return pipe 103. Is returned to the ink tank 101. In the inkjet recording apparatus 100, the ink supply pipe 102, the control unit 104, and the circulation pump 105 constitute an ink supply unit that supplies ink in the ink tank 101 to the inkjet head 1.

  The ink tank 101 is not particularly limited, but is preferably divided into an ink supply chamber 101b and an ink return chamber 101c by a partition plate 101a that does not reach the bottom plate of the tank. One end of the ink supply tube 102 is disposed in the ink supply chamber 101b, and one end of the ink return tube 103 is disposed in the ink return chamber 101c. The partition plate 101a is provided to sufficiently deaerate ink so that bubbles in the ink returned to the ink return chamber 101c are not supplied from the ink supply pipe 102 again. Since the bubbles themselves have high buoyancy, the bubbles are restricted from passing under the partition plate 101a and being sent to the ink supply chamber 101b. Such an embodiment is a preferred embodiment when the ink is circulated.

(Inkjet head)
Next, a specific configuration of the inkjet head 1 according to the present invention shown in FIG. 1 will be described. FIG. 2 is a partially enlarged cross-sectional view of the inkjet head 1.

  The inkjet head 1 has a head chip 2, a substrate 3 bonded to the head chip 2, and an ink manifold 4 bonded to a surface opposite to the head chip 2 with the substrate 3 interposed therebetween. In the head chip 2, a nozzle plate 21 having nozzles 22 is bonded to the surface opposite to the substrate 3.

  The ink jet head 1 shown in the present embodiment is installed and used so that the ejection surface 1S faces downward in FIGS. In this specification, “upper” or “lower” is based on the use state shown in FIGS. Accordingly, the upper side in FIGS. 1 and 2 is “upper” and the lower side is “lower”.

  The head chip 2 has a pressure chamber 23. The number of pressure chambers 23 is not particularly limited. In the head chip 2 shown in the present embodiment, a plurality of pressure chambers 23 are arranged along the X direction which is the longitudinal direction of the head chip 2. The pressure chamber 23 applies ejection pressure to the ink inside, and ejects ink from the nozzle 22 communicating with one end of the pressure chamber 23. The other end of the pressure chamber 23 is opened on the end surface of the head chip 2 on the substrate 3 side.

  Any specific means for applying discharge pressure to the ink in the pressure chamber 23 can be used, and any known means can be employed. In the present embodiment, the head chip 2 is illustrated in which the partition wall that separates the adjacent pressure chambers 23 and 23 is the drive wall 24 formed by a piezoelectric element. The drive wall 24 is shear-deformed by applying a drive signal of a predetermined voltage from, for example, the control unit 104 to a drive electrode (not shown) formed on a surface facing the pressure chamber 23. When the drive walls 24, 24 on both sides of the pressure chamber 23 undergo shear deformation, the pressure chamber 23 expands or contracts. As a result, pressure is applied to the ink in the pressure chamber 23, and the ink is ejected from the nozzle 22.

  The substrate 3 is, for example, a glass substrate, and has wiring (not shown) for applying a voltage to the drive electrode of each drive wall 24 of the head chip 2. The substrate 3 is bonded to the end face of the head chip 2 where the other end of the pressure chamber 23 is open. The size of the substrate 3 is larger than the end face of the head chip 2. For this reason, the outer periphery of the substrate 3 protrudes outside the head chip 2. The substrate 3 is formed with through holes 31 that individually communicate with the pressure chambers 23 of the head chip 2 and allow ink to flow into the pressure chambers 23.

  The ink manifold 4 is formed of a synthetic resin or the like into a horizontally long box shape having an opening 4a on one surface, and is bonded to the substrate 3 so as to close the opening 4a. The internal space of the ink manifold 4 forms an ink storage chamber 41 in which ink supplied from the ink tank 101 is stored. The ink storage chamber 41 communicates with all the pressure chambers 23 of the head chip 2 through the through holes 31 of the substrate 3. Accordingly, the ink in the ink storage chamber 41 is commonly supplied to all the pressure chambers 23 through the respective through holes 31.

  In the ink manifold 4, for example, a filter 42 formed of a mesh-like metal or resin porous body is arranged substantially parallel to the substrate 3 so that the ink storage chamber 41 is divided into two in the vertical direction in FIG. Has been. Accordingly, the ink storage chamber 41 is divided into an upstream ink chamber 411 far from the pressure chamber 23 and a downstream ink chamber 412 near the pressure chamber 23 with the filter 42 interposed therebetween. The filter 42 prevents bubbles and contaminants contained in the ink flowing into the upstream ink chamber 411 via the ink supply pipe 102 from flowing into the downstream ink chamber 412.

  In the present invention, the filter 42 is one of the pressure loss elements when the ink supplied to the ink storage chamber 41 flows into the downstream ink chamber 412. As for the pressure loss factor, in the ink pump circulation, the length of the pipe, the number of bent parts of the pipe, and the like can be considered, but these are negligible compared with the pressure loss of the filter. The circulation pump 105 has a pressure exceeding the pressure loss due to the pressure loss element such as the filter 42.

  In the downstream ink chamber 412, a damper member 43 in which a gas is sealed is disposed. The damper member 43 is arranged at a predetermined distance from the substrate 3 so that a damper surface 431 formed of a flexible film faces the substrate 3. The damper member 43 absorbs a pressure wave propagating from the pressure chamber 23 to the ink storage chamber 41 when ink is ejected. As a result, the influence of the pressure wave generated in the pressure chamber 23 on the other pressure chambers 23 via the ink storage chamber 41 can be reduced.

  In the ink manifold 4, pipe joint portions 44a, 44b, and 44c are raised upward.

  The pipe joint portion 44 a communicates with the upstream ink chamber 411 and forms an ink inflow port for allowing ink to flow into the upstream ink chamber 411. One end of the inflow pipe 5a is connected to the pipe joint portion 44a. Thereby, the inflow pipe 5 a communicates with the upstream ink chamber 411.

  The pipe joint 44 a and the inflow pipe 5 a constitute an inflow path that communicates with the upstream ink chamber 411 in the inkjet head 1.

  The pipe joint portion 44b communicates with the upstream ink chamber 411 and forms a first ink outflow port for allowing ink to flow out from the upstream ink chamber 411 together with air bubbles. One end of the first outflow pipe 5b is connected to the pipe joint portion 44b. Thus, the first outflow pipe 5b communicates with the upstream ink chamber 411.

  Note that the pipe joint portion 44b and the first outflow pipe 5b constitute a first outflow path that communicates with the upstream ink chamber 411 in the inkjet head 1.

  The pipe joint portion 44 c communicates with the downstream ink chamber 412 and forms a second ink outflow port for allowing ink to flow out from the downstream ink chamber 412 together with air bubbles. One end of the second outflow pipe 5c is connected to the pipe joint 44c. The filter 42 does not cover the opening of the pipe joint portion 44c. Thereby, the second outflow pipe 5 c communicates with the downstream ink chamber 412 without passing through the filter 42.

  The pipe joint portion 44 c and the second outflow pipe 5 c constitute a second outflow path that communicates with the downstream ink chamber 412 without passing through the filter 42 in the inkjet head 1.

  In the inkjet head 1 shown in the present embodiment, the inner diameter of the first outflow path constituted by the pipe joint portion 44b and the first outflow pipe 5b, and the second outflow path constituted by the pipe joint portion 44c and the second outflow pipe 5c. Are set to have the same inner diameter.

  It is preferable that the pipe joint part 44 a and the pipe joint part 44 b are arranged apart from each other at both ends in the longitudinal direction of the upstream ink chamber 411. In the present embodiment, the pipe joint portion 44a is disposed on the left side in FIG. 1 on the upper surface of the ink manifold 4, and the pipe joint portion 44b is disposed on the right side in FIG. As a result, the ink that has flowed into the upstream ink chamber 411 from the inflow pipe 5a can flow over the entire upstream ink chamber 411 toward the first outflow pipe 5b. Therefore, it is difficult to form a portion where the ink stays in the upstream ink chamber 411, and bubbles in the ink can be more efficiently removed.

  Further, it is preferable that the pipe joint portion 44c is disposed near the end of the downstream ink chamber 412 on the side farther from the pipe joint portion 44a than the pipe joint portion 44b. The ink manifold 4 in this embodiment is formed such that the downstream ink chamber 412 protrudes further to the right in the longitudinal direction in FIG. 1 than the upstream ink chamber 411. And the pipe joint part 44c is arrange | positioned in the edge part vicinity which protruded. As a result, the ink that has flowed into the downstream ink chamber 412 from the inflow pipe 5a through the upstream ink chamber 411 and the filter 42 flows toward the second outflow pipe 5c over the entire downstream ink chamber 412. Can do. Therefore, it is difficult to form a portion where the ink stays in the downstream ink chamber 412, and bubbles in the ink can be more efficiently removed.

  The ink jet head 1 is joined by connecting the first outflow pipe 5b and the second outflow pipe 5c to a common pipe connection member 6, which is a preferred embodiment in the present invention. The pipe connecting member 6 has two inlets 6a and 6b and one outlet 6c. The inlets 6a and 6b are connected to the outlet ends of the first outlet pipe 5b and the second outlet pipe 5c. An outlet pipe 61 is connected to the outlet 6c. Thereby, the pipe connection member 6 joins the ink flowing through the first outflow pipe 5b and the second outflow pipe 5c, and causes the ink to flow out from one outlet 6c. As such a pipe connection member 6, for example, a T-shaped joint, a Y-shaped joint, or the like can be used.

  Connection joints 7a and 7b are provided at the ends of the inflow pipe 5a and the outlet pipe 61, respectively. The connection joint portions 7a and 7b are connection means for connecting the inkjet head 1 to piping or the like constituting an ink circulation system on the inkjet recording apparatus 100 side. In the ink jet head 1 shown in the present embodiment, the connecting joint portion 7a is detachably connected to the connecting joint portion 106a communicating with the ink supply pipe 102 on the ink jet recording apparatus 100 side, and the connecting joint portion 7b is connected to the ink jet recording apparatus 100. It is detachably connected to a connecting joint portion 106b communicating with the ink return pipe 103 on the side. Thereby, the inkjet head 1 is installed so that ink can be supplied and returned to the inkjet recording apparatus 100.

  As described above, in the inkjet head 1 shown in the present embodiment, the first outflow pipe 5b and the second outflow pipe 5c are joined to the single outlet pipe 61 by the single pipe connecting member 6, and therefore, the inkjet recording apparatus 100. The connection part with the side piping or the like is also only required at two locations of the inflow pipe 5a (connecting joint part 7a) and the outlet pipe 61 (connecting joint part 7b). Therefore, the number of connection parts with the piping or the like on the ink jet recording apparatus 100 side does not increase, and the connection work does not become complicated.

  Further, the ink jet head 1 shown in the present embodiment includes only two places of the inflow pipe 5a (connecting joint part 7a) and the outlet pipe 61 (connecting joint part 7b), and the connecting joint parts 106a and 106b on the ink jet recording apparatus 100 side. Since the structure is connected, there is also an effect of having compatibility with an ink jet head of an existing ink jet recording apparatus provided with a circulation mechanism. That is, in general, an ink jet recording apparatus having a circulation mechanism that circulates ink in an ink manifold has a structure in which a pipe connection is made to each ink jet head at two locations, an ink inflow portion and an outflow portion. For this reason, according to the inkjet head 1 shown in the present embodiment, it is possible to replace and install by connecting only two portions of the connection joint portions 7a and 7b without changing the design of the existing device.

  A check valve 8 is provided in the second outflow pipe 5c. The check valve 8 functions to permit the outflow of ink from the downstream ink chamber 412 toward the pipe connection member 6 and to block the flow of ink on the opposite side. For example, when the filter 42 is clogged by impurities contained in the ink and the pressure on the downstream ink chamber 412 side is reduced, a pressure difference is generated between the upstream ink chamber 411 and the upstream ink chamber 411. In this case, the ink flowing out from the first outflow pipe 5b may flow backward from the pipe connecting member 6 to the second outflow pipe 5c. By providing the check valve 8 in the second outflow pipe 5c, it is possible to prevent bubbles and foreign substances from entering the downstream ink chamber 412 due to the back flow of ink. Thus, the aspect which provides the non-return valve 8 is a preferable aspect when the 1st outflow pipe 5b and the 2nd outflow pipe 5c are made to merge by the piping connection member 6. FIG. This check valve 8 is also one of the pressure loss elements.

  In the inkjet head 1 shown in the present embodiment, a pressure loss is given to the first outflow path. Specifically, a flow rate adjusting member that partially narrows the cross-sectional area of the first outflow path is provided in the first outflow path.

  An example of the flow rate adjusting member is shown in FIG. FIG. 3 is a perspective view showing a state in which the first outflow pipe 5b provided with an example of the flow rate adjusting member is partially cut away.

  The flow rate adjusting member shown in FIGS. 1 and 3 is a constricting member 9 that is held in the first outflow pipe 5b and partially reduces the flow path of the first outflow pipe 5b. According to this, it is possible to easily provide a flow rate adjusting member that imparts a desired pressure loss to the first outflow path by simply connecting the first outflow pipe 5b holding the constriction member 9 in advance to the pipe joint portion 44b. it can.

  As shown in FIG. 3, the constricting member 9 integrally has large-diameter portions 92 and 92 that are larger in diameter than the small-diameter portion 91 on both end sides of the small-diameter portion 91. The material of the constricting member 9 is not particularly limited, and examples thereof include metals such as stainless steel, ceramics, and synthetic resins that are excellent in ink impermeability, easy to insert into the first outflow pipe 5b, and excellent in corrosion resistance to ink.

  The outer diameters of the large diameter portions 92 and 92 are formed such that the outer peripheral surface thereof can be in close contact with the inner peripheral surface of the first outflow pipe 5b. Therefore, after the constriction member 9 is inserted into the first outflow pipe 5b, the large diameter portions 92 and 92 are brought into close contact with the inner peripheral surface of the first outflow pipe 5b, whereby a predetermined position in the first outflow pipe 5b is obtained. Retained.

  The narrowing member 9 is formed with a small diameter portion 91 and a flow path hole 94 extending vertically through the large diameter portions 92 and 92. Since the large diameter portions 92 and 92 are in close contact with the inner peripheral surface of the first outflow pipe 5b, the flow path in the first outflow pipe 5b at the portion where the narrowing member 9 is disposed is only the flow path hole 94. . Accordingly, the narrowing member 9 partially narrows the flow passage cross-sectional area of the first outflow pipe 5b by the flow passage hole 94, and loses the pressure of the ink flowing in the first outflow pipe 5b.

  A groove portion 93 extending in the axial direction is formed on a part of the outer peripheral surface of the large diameter portion 92 on the ink inflow side. Due to the groove 93, air bubbles in the ink flow between the inner wall of the first outflow pipe 5b and the small diameter portion 91, and this air is trapped. Since this air is in contact with the ink in the first outflow pipe 5b, it plays the role of a damper. The role of the damper is to prevent the carriage vibration from propagating inside the head. When the ink is deaerated, the air between the inner wall of the first outflow pipe 5b and the small diameter portion 91 decreases, but this air is filled by the gas permeability of the tube. The large diameter portion 92 may be provided only on the ink outflow side. Further, when the flow rate adjusting member 9 does not need to have a damper function, the small diameter portion 91 may not be provided.

  The pressure loss applied by the constricting member 9 is caused by the fact that the ink flowing into the ink storage chamber 41 flows through the upstream ink chamber 411 toward the first outflow pipe 5b, and at the same time, a part of the ink passes through the filter 42. This is a pressure loss that passes through and flows through the downstream ink chamber 412 toward the second outflow pipe 5c. This pressure loss is adjusted by the inner diameter of the flow path hole 94.

  That is, in the case of the inkjet head 1 shown in the present embodiment, the ink flowing into the ink storage chamber 41 from the inflow tube 5a passes through the upstream ink chamber 411 and flows out from the first outflow tube 5b. Part of the ink pressure is lost and part of the ink pressure is lost. The pressure corresponding to the loss becomes a pressure at which the ink can pass through the filter 42 by appropriately adjusting the inner diameter of the flow path hole 94. Therefore, part of the ink that has flowed into the upstream ink chamber 411 passes through the filter 42 and flows into the downstream ink chamber 412. As a result, the ink that has flowed into the upstream ink chamber 411 flows not only through the upstream ink chamber 411 but also through the filter 42 into the downstream ink chamber 412 at the same time.

  Therefore, according to the ink jet head 1 and the ink jet recording apparatus 100 including the ink jet head 1, the remaining bubbles in the ink storage chamber 41 are allowed to flow through the upstream ink chamber 411 to the first outflow only by flowing ink from the inflow pipe 5 a. In addition to being discharged from the pipe 5b, it can be discharged from the second outflow pipe 5c through the downstream ink chamber 412 with the filter 42 therebetween. Therefore, the residual bubbles in the entire ink storage chamber 41 can be efficiently removed without the need for opening / closing control of the opening / closing valve or the like as in the prior art.

  Further, according to the inkjet head 1 and the inkjet recording apparatus 100 including the inkjet head 1, the ink in the downstream ink chamber 412 is also circulated through the filter 42 when the ink is circulated with the ink tank 101 during image recording. Can be made. For this reason, air bubbles drawn from the nozzles 22 during image recording can be quickly discharged. In addition, when ink containing particles or pigments that easily settle is used, sedimentation of particles or pigments in the downstream ink chamber 412 during image recording is effectively suppressed, and the ink density distribution is reduced. Can be suppressed.

  The specific inner diameter of the flow path hole 94 of the constriction member 9 takes into consideration the pressure loss of the filter 42, the check valve 8, etc., which are pressure loss elements, and the pressure loss of the first outflow path becomes the desired pressure loss. Is adjusted as appropriate. For example, the inner diameter of the flow path hole 94 of the constriction member 9 is adjusted so that the ink flow rate flowing out from the first outflow tube 5b and the ink flow rate passing through the filter 42 and outflowing from the second outflow tube 5c are uniform. In this case, the ink can flow evenly in the upstream ink chamber 411 and the downstream ink chamber 412. This is a preferable mode particularly when ink is initially introduced because ink can be quickly stored in the upstream ink chamber 411 and the downstream ink chamber 412.

  Further, by adjusting the inner diameter of the flow path hole 94 of the narrowing member 9, the ink flow rate flowing out from the first outflow tube 5b and the ink flow rate flowing through the filter 42 and out of the second outflow tube 5c are made different. You can also. For example, since the ink flow rate that passes through the filter 42 and flows out from the second outflow tube 5c is larger than the ink flow rate that flows out from the first outflow tube 5b, there are also bubbles that are difficult to remove attached to the lower surface of the filter 42. It can be easily removed.

  The constricting member 9 shown in FIG. 3 is merely an example, and the specific structure is not limited to that shown in FIG. For example, as described above, the large diameter portion 92 may be provided only on one side. Further, the small diameter portion 91 may not be provided.

(Bubble removal method)
Next, in the inkjet head 1 configured as described above, a method of removing residual bubbles in the ink storage chamber 41 when ink is initially introduced will be described with reference to FIGS. In FIG. 4, the inflow pipe 5a, the first outflow pipe 5b and the second outflow pipe 5c holding the constriction member 9 are not shown.

  The bubble removing operation in the inkjet recording apparatus 100 is performed by controlling the driving of the circulation pump 105 according to a predetermined program stored in advance in the control unit 104, for example.

  First, the control unit 104 drives the circulation pump 105 to cause the ink in the ink tank 101 to flow into the ink storage chamber 41 in the ink manifold 4 from the inflow pipe 5a with a predetermined pressure. The ink that has flowed into the ink storage chamber 41 flows toward the first outflow pipe 5b through the upstream ink chamber 411 (FIG. 4A).

  Here, as shown in FIGS. 1 and 3, the first outflow pipe 5 b is provided with a constriction member 9 as a flow rate adjusting member in consideration of pressure loss such as the filter 42 and the check valve 8. Therefore, a part of the ink about to flow out from the first outflow pipe 5b is stopped by the constriction member 9, and the ink pressure is partially lost. The pressure corresponding to the loss is a pressure at which ink can pass through the filter 42 by appropriately adjusting the inner diameter of the flow path hole 94. Accordingly, a part of the ink flowing in the upstream ink chamber 411 flows into the downstream ink chamber 412 through the filter 42 (FIG. 4B).

  As a result, the ink storage chamber 41 passes through the upstream ink chamber 411 and flows out of the first outflow pipe 5b as it is, and passes through the filter 42 and flows into the downstream ink chamber 412. A flow of ink flowing out from the second outflow pipe 5c through the ink chamber 412 is simultaneously formed (FIG. 4C).

  Accordingly, the ink that has flowed into the ink storage chamber 41 flows out from both the first outflow pipe 5b and the second outflow pipe 5c. At this time, the remaining bubbles in the upstream ink chamber 411 are discharged from the first outflow pipe 5b together with the ink, and the remaining bubbles in the downstream ink chamber 412 are discharged from the second outflow pipe 5c together with the ink.

  The control unit 104 stops the driving of the circulation pump 105 after continuing for a predetermined time set in advance. In addition, for example, a sensor for detecting bubbles in the ink is provided in the ink return pipe 103, and when this sensor no longer detects bubbles in the ink flowing in the pipe, the driving of the circulation pump 105 is stopped. Also good. As a result, the bubble removing operation is completed, and the ink storage chamber 41 is filled with ink.

  As described above, the ink jet head 1 not only causes the ink to flow out from the first outflow pipe 5b only by flowing the ink into the ink storage chamber 41, but also causes the ink to flow out from the second outflow pipe 5c via the filter 42. Can be drained. Since it is not necessary to operate the on-off valve or the like to remove bubbles, and to separately cause ink to flow out of the upstream ink chamber 411 and the downstream ink chamber 412, the ink storage chamber can be obtained without complicating the structure of the inkjet head 1. Residual bubbles in 41 can be efficiently removed.

  Further, since the ink containing bubbles can flow out from both the upstream ink chamber 411 and the downstream ink chamber 412, the bubble removal operation can be performed in comparison with the case where the bubble removal operation is performed individually in each of the ink chambers 411 and 412. This time can be shortened and ink consumption for removing bubbles can be suppressed.

  The above bubble removal operation can be performed not only when ink is initially introduced but also when an image is recorded on a recording medium. In other words, by driving the circulation pump 105 during image recording, not only the ink in the upstream ink chamber 411 but also the ink in the downstream ink chamber 412 between the filter 42 and the pressure chamber 23 can be circulated. . Thereby, the ink circulation not only removes bubbles even during image recording, but also supplies homogeneous ink having no density distribution to each pressure chamber 23. For this reason, a higher quality image can be formed.

  As described above, according to the present invention, it is possible to provide an inkjet head, an inkjet head bubble removal method, and an inkjet recording apparatus that can efficiently remove residual bubbles in an ink storage chamber equipped with a filter. .

(Another embodiment of the flow rate adjusting member)
The flow rate adjusting member is not limited to the one provided in the first outflow path like the constriction member 9 shown in FIGS. 1 and 3, and may be provided in the second outflow path as shown in FIG. 5. FIG. 5 is a schematic configuration diagram of a main part showing another example of the ink jet recording apparatus according to the present invention, in which the ink jet head is partially shown in cross section. Since the site | part of the same code | symbol as FIG. 1 is a site | part of the same structure, these description uses the said description and abbreviate | omits here.

  The flow rate adjusting member in FIG. 5 is configured by a suction pump 10 provided in the second outflow pipe 5c. The suction pump 10 is driven by the control of the control unit 104 and forcibly sucks the ink in the second outflow pipe 5c. As a result, the flow rate of ink from the upstream ink chamber 411 to the downstream ink chamber 412 where the ink hardly flows due to the pressure loss of the filter 42 is increased. The drive amount (suction amount) of the suction pump 10 at this time is such that a part of the ink that flows into the upstream ink chamber 411 can pass through the filter 42 and also flow into the downstream ink chamber 412. 104 is adjusted appropriately.

  Therefore, according to the ink jet head 1 provided with such a suction pump 10, not only does the ink flow into the ink storage chamber 41, but the ink flows out from the first outflow pipe 5 b as well as through the filter 42. Since the ink can also flow out from the second outflow pipe 5c, the residual bubbles in the ink storage chamber 41 can be efficiently removed as in the case where the narrowing member 9 is provided.

  Further, the suction pump 10 can appropriately adjust the ink flow rate by controlling the drive amount. For this reason, the ink flow rate flowing out from the first outflow tube 5b and the ink flow rate flowing out from the second outflow tube 5c are equalized, for example, the ink flow rate flowing out from the second outflow tube 5c is larger than that of the first outflow tube 5b. As described above, it is possible to easily change the flow rates of ink flowing out from the first outflow pipe 5b and the second outflow pipe 5c only by adjusting the driving amount of the suction pump 10.

  Furthermore, since the negative pressure is generated in the downstream ink chamber 412 by driving the suction pump 10, it is possible to suppress the wasteful discharge of the ink from the nozzles 22 when the ink is initially introduced.

  In the present embodiment, the inner diameter of the first outflow path constituted by the pipe joint portion 44b and the first outflow pipe 5b is set the same as the inner diameter of the second outflow path by the pipe joint portion 44c and the second outflow pipe 5c. However, when the suction pump 10 is provided in this way, it is also preferable to make the inner diameter of the second outflow path smaller than the inner diameter of the first outflow path. When the suction pump 10 is driven, the pressure fluctuation in the downstream ink chamber 412 can be suppressed, and the ink flow rate can be easily adjusted.

  In the present invention, the flow rate adjusting member provided in the first outflow path constituted by the pipe joint portion 44b and the first outflow pipe 5b is not limited to the narrowing member 9 described above. For example, although not shown, a flow rate adjusting valve may be provided in the first outflow pipe 5b, and the pressure loss may be applied by partially narrowing the cross-sectional area of the first outflow pipe 5b. Appropriate pressure loss can be imparted to the first outflow passage by appropriately adjusting the opening of the flow regulating valve. The flow rate adjusting member may be a check valve. Furthermore, when the first outflow pipe 5b is formed of a flexible pipe, pressure loss is applied by partially narrowing the cross-sectional area of the flow path from the outside of the first outflow pipe 5b using a sandwiching member or the like. May be.

(Another embodiment of inkjet head and inkjet recording apparatus)
In the inkjet head 1 and the inkjet recording apparatus 100 shown in FIG. 5, in addition to providing the suction pump 10 in the second outflow pipe 5c, for example, the first outflow pipe 5b is provided with a flow rate adjusting member such as a constriction member 9 to remove bubbles. Sometimes it is also preferred to use these in combination. Since the pressure loss is given by the flow rate adjusting member provided in the first outflow pipe 5b, the driving amount of the suction pump 10 can be reduced accordingly. Thereby, the suction pump 10 may be a low capacity pump, and the initial cost and running cost can be reduced.

  Further, when the flow rate adjusting member of the first outflow pipe 5b and the suction pump 10 of the second outflow pipe 5c are used in combination, the first outflow pipe is compared with the case where the flow rate adjusting member is provided only in the first outflow pipe 5b. The pressure loss applied to the pipe 5b can be set small. For example, when the constriction member 9 is used as the flow rate adjusting member, the inner diameter of the flow path hole 94 can be made larger than when the constriction member 10 is not used together. For this reason, it is possible to use high-viscosity ink that does not easily flow in the narrow flow passage hole 94, and the types of usable ink can be expanded.

  Further, in the ink jet head 1 shown in FIGS. 1 and 5, the ink flowing through the first outflow pipe 5b and the ink flowing through the second outflow pipe 5c are merged by the common pipe connection member 6, but the pipe connection The member 6 is not necessarily provided. In this case, since there are three connection sites with the piping or the like on the inkjet recording apparatus 100 side, compatibility with the existing apparatus is impaired, but the ink flows out from the first outflow pipe 5b and the second outflow pipe 5c, respectively. Since they do not merge with each other, the check valve 8 of the second outflow pipe 5c becomes unnecessary.

  In the ink jet recording apparatus 100 described above, ink is circulated between the ink jet head 1 and the ink tank 101. However, the present invention is not limited to this. For example, if it is only necessary to remove residual bubbles when the ink is initially introduced, the ink that has flowed out of the first outflow pipe 5b and the second outflow pipe 5c is not returned to the ink tank 101 but is returned to the waste ink tank. You may comprise so that it may discharge | emit.

1: Inkjet head 1S: Discharge surface 2: Head chip 21: Nozzle plate 22: Nozzle 23: Pressure chamber 24: Drive wall 3: Substrate 31: Through hole 4: Ink manifold 4a: Opening 41: Ink reservoir chamber 411: Upstream Side ink chamber 412: Downstream side ink chamber 42: Filter 43: Damper member 431: Damper surface 44a, 44b, 44c: Piping joint 5a: Inflow pipe 5b: First outflow pipe 5c: Second outflow pipe 6: Piping connection member 6a, 6b: Inlet 6b: Outlet 61: Outlet pipe 7a, 7b: Connection joint 8: Check valve 9: Narrowing member (flow rate adjusting member)
91: Small diameter part 92: Large diameter part 93: Groove part 94: Channel hole 10: Suction pump (flow rate adjusting member)
DESCRIPTION OF SYMBOLS 100: Inkjet recording device 101: Ink tank 102: Ink supply pipe 103: Ink return pipe 104: Control part 105: Circulation pump 106a: Connection joint part 106b: Connection joint part

Claims (15)

A nozzle that ejects ink; a pressure chamber that communicates with the nozzle; an ink manifold that forms an ink reservoir chamber that communicates with the pressure chamber; and a filter disposed within the ink manifold, wherein the ink reservoir chamber comprises: And an upstream ink chamber far from the pressure chamber and a downstream ink chamber near the pressure chamber, and an inflow path and a first outflow path communicate with the upstream ink chamber, respectively. An inkjet head in which a second outflow path communicates with the downstream ink chamber without passing through the filter,
A pressure loss is applied to the first outflow path and / or ink is sucked from the second outflow path and the ink flowing into the upstream ink chamber from the inflow path is passed through the filter to the downstream ink chamber. Inflow is also configured so that ink flows simultaneously into the upstream ink chamber and the downstream ink chamber ,
An ink jet head provided with a suction pump for sucking ink from the second outflow path in the second outflow path .   The inkjet head according to claim 1, wherein a flow rate adjusting member that applies pressure loss by partially narrowing a cross-sectional area of the first outflow path is provided in the first outflow path.   The inkjet head according to claim 2, wherein the flow rate adjusting member is a constricting member that is held in the first outflow path and partially reduces the flow path of the first outflow path. An outflow pipe for holding the constriction member inside;
The ink jet head according to claim 3, wherein the outflow pipe is connected to an ink outflow port of the upstream ink chamber. Wherein the inner diameter of the second outlet channel, the ink-jet head according to claim 1 which is smaller than the inner diameter of the first outlet channel.   The inkjet head according to claim 1, wherein the first outflow path and the second outflow path are joined together by a pipe connecting member.   The inkjet head according to claim 6, wherein a check valve is provided in the second outflow path. A nozzle that ejects ink; a pressure chamber that communicates with the nozzle; an ink manifold that forms an ink reservoir chamber that communicates with the pressure chamber; and a filter disposed within the ink manifold, wherein the ink reservoir chamber comprises: And an upstream ink chamber far from the pressure chamber and a downstream ink chamber near the pressure chamber with the filter interposed therebetween, and an inflow path and a first outflow path communicate with the upstream ink chamber, respectively. A method for removing bubbles in an ink jet head, wherein a second outflow path communicates with the downstream ink chamber without passing through the filter, and ink is allowed to flow in from the inflow path to remove residual bubbles in the ink storage chamber. Because
A pressure loss is applied to the first outflow path and / or ink is sucked from the second outflow path and the ink flowing into the upstream ink chamber from the inflow path is passed through the filter to the downstream ink chamber. also by inflow, simultaneously flow the ink to the downstream ink chamber and the upstream ink chamber,
A method of removing bubbles in an ink jet head , wherein a suction pump is provided in the second outflow path to suck ink from the second outflow path .   9. The method of removing bubbles in an ink jet head according to claim 8, wherein pressure loss is applied to the first outflow path by providing a flow rate adjusting member that partially narrows the cross-sectional area of the first outflow path.   The method for removing bubbles of an ink jet head according to claim 9, wherein the flow rate adjusting member is a constricting member that is held in the first outflow path and partially reduces the flow path of the first outflow path. Providing an outflow pipe for holding the constriction member inside;
The method of claim 10, wherein the outflow pipe is connected to an ink outflow port of the upstream ink chamber. The method of removing bubbles in an ink jet head according to any one of claims 8 to 11 , wherein an inner diameter of the second outflow path is smaller than an inner diameter of the first outflow path.   The method for removing bubbles of an ink jet head according to any one of claims 8 to 12, wherein the first outflow path and the second outflow path are joined together by a pipe connection portion.   14. The method of removing bubbles in an ink jet head according to claim 13, wherein a check valve is provided in the second outflow path. An inkjet head according to any one of claims 1 to 7;
An ink tank for storing ink to be supplied to the inkjet head;
An ink jet recording apparatus comprising: an ink supply unit that supplies ink in the ink tank to the ink jet head.

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