JP2004216914A - Inkjet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet head which suppresses generation of bubbles in a supply path formed in the ink jet head and does not cause non-ejection.
SOLUTION: The ink liquid supplied from an inflow path 16 flows into each ejection channel 12 through a supply path 14 extending in the direction in which the ejection channels 12 are arranged. The inner wall surface of the inflow path 16 that is continuous with the supply path 14 forms an inclined surface 18 that gradually widens the cross-sectional area of the flow path toward the supply path 14, and the ink liquid flows along the inclined surface 18, Since the flow velocity of the liquid gradually decreases as the cross-sectional area increases, the ink liquid gradually flows into the supply path 14.
[Selection diagram] FIG.

Description

  The present invention relates to an ink jet head of an ink jet recording apparatus that performs required recording on recording paper or the like by ejecting ink liquid from nozzles.

  2. Description of the Related Art Conventionally, an ink jet recording apparatus has been well known as a recording apparatus having a relatively simple configuration and capable of easily performing high-speed printing and high-quality printing. An ink jet head used in this type of ink jet recording apparatus includes, for example, as shown in FIG. 7, a plurality of ejection channels 1 formed of a piezoelectric ceramic or the like and arranged to eject ink liquid from a nozzle as droplets. The actuator includes an actuator 2, an inflow path 3 into which an ink liquid from an ink supply source flows, and a manifold 5 having a supply path 4 for supplying the ink liquid flowing from the inflow path 3 to each ejection channel 1. The ink liquid supplied from the ink supply source to the supply path 4 via the inflow path 3 is introduced into each ejection channel 1 of the actuator 2, and changes the volume of each ejection channel 1 by deformation of the actuator 2, and the volume thereof is changed. At the time of reduction, the ink liquid in the ejection channel 1 is ejected from the nozzle as a droplet, and when the volume is increased, the ink liquid is introduced from the ink supply source into the ejection channel 1 via the inflow path 3 and the supply path 4.

  The supply channel 4 has an inner wall 6 opposed to each of the arranged injection channels 1 at a predetermined interval. The inner wall 6 and the inner wall of the inflow channel 3 continuous with the inner wall 6 are formed. 7, the inner wall surface 6 of the supply passage 4 is formed to have a substantially U-shaped cross section that opens to the injection channel 1 side, as shown in FIG.

  However, in the above-described configuration, when the ink liquid flows into the inflow path 4 from the ink supply source at the time of introduction of the ink liquid, the flow velocity of the ink liquid drops very much when flowing into the supply path 4 from the inflow path 3. Instead, the air flows as it is in the direction of the flow path of the inflow path 3 and violently hits the opening end face 8 of the actuator 2 to generate bubbles. Such bubbles enter each ejection channel 1 of the actuator 2 and cause non-ejection of the ink liquid, which causes a problem that printing cannot be performed.

  SUMMARY OF THE INVENTION The object of the present invention is to solve the above-described problems, and by a simple configuration, suppresses the generation of bubbles in a supply path formed in an inkjet head and does not cause non-ejection. An object of the present invention is to provide an inkjet head.

  In order to achieve the above object, the invention according to claim 1 includes a plurality of ejection channels arranged to eject ink liquid as droplets from a nozzle, an inflow path through which ink liquid flows from an ink inflow port, A supply path for supplying the ink liquid flowing from the inflow path to each ejection channel, wherein the supply path is formed to extend in the arrangement direction of the ejection channels, and an actuator having the ejection channels is provided. The supply path is joined to a manifold having the supply path so as to constitute one side surface of the supply path, and the inflow path is connected to the supply path at one end in the arrangement direction of the injection channels so as to cross the supply path; An inclined surface that gradually widens the cross-sectional area of the flow path toward the supply path is provided on an inner wall surface that is continuous with the supply path, Immediately the supply passage from the inclined surface of, is characterized in that has a shape that extends toward the arrangement direction other end of the injection channel.

  By providing such an inclined surface and gradually increasing the cross-sectional area of the flow path at the boundary between the supply path and the inflow path, the ink liquid flowing into the inflow path from the ink supply source flows into the supply path from the inflow path. In this case, the ink liquid flows along the inclined surface, and the flow velocity of the ink liquid gradually decreases as the cross-sectional area increases, so that the ink liquid flows into the supply path gently. Therefore, when the ink liquid is introduced, the ink liquid that has flowed into the supply path does not violently hit the wall surface, and the ink liquid does not foam, so that the generation of bubbles during the introduction of the ink liquid can be effectively suppressed, and the ink liquid can be effectively suppressed. Non-jetting of the liquid can be effectively prevented.

  According to a second aspect of the present invention, in the first aspect of the invention, the inclined channel is located at an injection channel farthest from the inflow channel among a plurality of the injection channels from the inflow channel. It is inclined in the direction. By inclining the inclined surface in this way, the ink liquid flowing from the inflow channel to the supply channel flows so as to spread in the inclination direction of the inclined surface, and the ink liquid flows to the ejection channel located farthest from the inflow channel. Is also supplied smoothly without foaming.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the supply path is connected below the inflow path with the inflow path facing upward.

  According to a fourth aspect of the present invention, in the third aspect of the invention, the inflow path faces a surface of the actuator which forms one side surface of the supply path.

  According to a fifth aspect of the present invention, in the first aspect of the present invention, a filter is attached to the ink inlet of the inflow path.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein one end of each of the plurality of injection channels is opened at an end face on the manifold side of the actuator, An inner wall surface of the supply passage facing the injection channel has a substantially inverted U-shaped cross section depressed in a direction away from each of the injection channels. By making the inner wall surface of the supply path have such a shape, the bubbles generated and retained in the supply path can be retained at a dent position away from each ejection channel, making it difficult for the bubbles to enter the ejection channel. In addition, non-ejection of ink liquid can be prevented.

  According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the deepest portion of the depression on the inner wall surface of the supply channel is located at a position deviated from the center line of each of the injection channels. By locating the deepest part of the depression at a position shifted from the center line of each injection channel, bubbles staying at the deepest part will stay at a position further away from each injection channel, and the bubbles will be transferred to the injection channel more. By making it difficult to enter, it is possible to more effectively prevent non-ejection of the ink liquid.

  Also, in the invention according to claim 8, in the invention according to any one of claims 1 to 7, the injection channels are provided in a plurality of rows, and the supply path is connected to one end of the plurality of rows of the injection channels in the column direction. A base end portion connected in common and connected to the inflow path, and a branch portion branched corresponding to the other end in each column direction of the plurality of rows of the injection channels, wherein the inclined surface is the base end portion In the above, the shape is formed so as to spread from the inflow path side to the branch portion side. As described above, since a plurality of ejection channels are provided for each row, and the supply paths are formed corresponding to the ejection channels of each row, the volume of the supply path can be reduced, and the ink liquid flowing from the inflow path is inclined. The flow can flow from the surface along the branch portion, and thus can be smoothly supplied to the injection channels of each row. Therefore, it is possible to effectively suppress bubbles from remaining in the supply path when the ink liquid is introduced.

  According to the present invention, a plurality of ejection channels are arranged to eject the ink liquid from the nozzles as droplets, an inflow path into which the ink liquid flows from the ink inflow port, and each of the ejection liquids ejecting the ink liquid from the inflow path. A supply path for supplying to the channel, wherein the supply path is formed to extend in a direction in which the ejection channels are arranged, and an actuator having the ejection channel constitutes one side surface of the supply path. The inflow path is connected to the supply path at one end in the arrangement direction of the injection channels so as to intersect with the supply path, and an inner wall surface of the inflow path that is continuous with the supply path, An inclined surface for gradually increasing the cross-sectional area of the flow path toward the supply path is provided, and the supply path is immediately formed from the inclined surface. Since the ink channel has a shape extending toward the other end in the arrangement direction of the ejection channels, the ink liquid flowing from the ink supply source into the inflow path flows along the inclined surface when flowing into the supply path from the inflow path. Since the flow and the flow velocity of the ink liquid gradually decrease as the cross-sectional area increases, the ink liquid flows into the supply path slowly. For this reason, at the time of introduction of the ink liquid, the ink liquid flowing into the supply path does not violently hit the wall surface and does not foam the ink liquid, so that the generation of bubbles during the introduction of the ink liquid can be effectively suppressed, Non-ejection of the ink liquid can be effectively prevented.

  FIG. 1 is a perspective view showing an embodiment embodying an ink jet recording apparatus provided with an ink jet head of the present invention. The color inkjet printer 21 includes an inkjet type inkjet head 23 that prints by printing four color inks of cyan, magenta, yellow, and black on a printing paper 22 as a printing medium. , A head unit 24 and an ink cartridge 25 as an ink supply source for supplying four colors of ink liquid to the inkjet head 23 are detachably mounted on a carriage 26 together with the head unit 24. .

  A platen roller 27 is rotatably provided opposite to the front surface of the ink jet head 23 in parallel to the reciprocating direction of the ink jet head 23. The ink jet head 23 and the platen roller 27 constitute a printing unit. The carriage 26 is supported by a carriage shaft 29 and a guide plate 54 extending in the reciprocating direction of the ink jet head 23 via a carriage shaft support 28 provided below the carriage 26, and is capable of linearly reciprocating at the time of printing. The pulley 30 is connected to a belt 32 stretched between the pulleys 30 and 31, and is driven by a motor (not shown) to rotate linearly.

  The printing paper 22 is fed from a paper feed cassette (not shown) provided above the rear part of the ink jet printer 21 and is introduced between the ink jet head 23 and a platen roller 27 that is driven to rotate in the direction of arrow 33. Is discharged in the arrow 34 direction. In FIG. 1, the illustration of the paper feed mechanism for these printing papers is omitted.

  A purge device 35 is provided on the side of the platen roller 27 so as to face forward of the reset state position of the inkjet head 23. The ink-jet type ink-jet head 23 solves the problem that a bubble that has accumulated during the initial introduction of the ink liquid or the like or a drop of the ink adheres to the jetting surface may cause jetting failure. There is a purge device 35 for restoring a good injection state. The purging device 35 can cover the inkjet head 23 with a cap 36 provided at a front facing position in a reset state position of the inkjet head 23. When the inkjet head 23 is covered with the cap 36, Defective ink containing air bubbles and the like accumulated inside the inkjet head 23 is sucked by a pump 38 driven by a cam 37 to recover the inkjet head 23. The sucked defective ink is sent to the storage unit 39.

  2 is a perspective view of the inkjet head 23, FIG. 3 is a cross-sectional view of a main part taken along line AA in FIG. 2, FIG. 4 is a cross-sectional view of a main part taken along line BB in FIG. 2, and FIG. is there. The ink jet head 23 will be described with reference to FIG. 2, FIG. 3, FIG. 4, and FIG. 2, 3 and 4, the ink-jet head 23 communicates with the nozzle plate 11 in which a plurality of nozzles (not shown) are formed, and communicates with each nozzle of the nozzle plate 11, and converts the ink liquid into droplets. An actuator 13 having a plurality of ejection channels 12 arranged for ejecting, an inflow path 16 joined to the actuator 13 to allow the ink liquid from the ink cartridge 25 to flow, and supplying the ink liquid to each ejection channel 12 And a manifold 15 having a supply path 14.

  The ink liquid from the ink cartridge 25 flows into the inflow path 16 from the ink inlet 19 of the manifold 15, and the ink liquid flowing into the inflow path 16 flows into the supply path 14. The ink liquid that has flowed into the supply path 14 is supplied into each ejection channel 12 of the actuator 13, and changes the volume of the ejection channel 12 by deforming the actuator 13. When the volume decreases, the ink liquid in the ejection channel 12 is supplied to the nozzle plate 12. Ink is ejected from the nozzle formed in the nozzle 11 as a droplet, and the ink liquid is introduced from the ink cartridge 25 into the ejection channel 12 of the actuator 13 via the inflow path 16 and the supply path 14 when the volume is increased. . In the ink jet head 23, the actuator 13 may be a thermal head type using a heating element instead of the piezoelectric ceramic element, or any other known type. Reference numerals 40 and 41 shown in FIGS. 2 and 3 are mounting members formed on both end portions of the manifold 15 for mounting the manifold 15 to the head unit 24 and holding the actuator 13.

  The ink jet head 23 is inclined at about 45 degrees as shown in FIG. 1 with the nozzle plate 11 down and the manifold 15 up. At this time, the supply path 14 of the manifold 15 continues downward from the inflow path 16 with the inflow path 16 at the top. In addition, the inkjet head 23 can be placed horizontally or vertically downward. However, in the case of horizontal orientation, it is preferable to arrange the supply path 14 below the inflow path 16.

  More specifically, as shown in FIGS. 3 and 4, the ejection channel 12 is arranged in the actuator 13 in every two rows, and the plurality of ejection channels 12 are linearly arranged in each row. Each of the injection channels 12 is open at the end face 42 on the manifold side of the actuator 13. Further, the manifold 15 is provided with a supply path 14 continuous with the inflow path 16, and the supply path 14 extends in the arrangement direction of the plurality of injection channels 12 and is arranged as shown in FIG. 5. An inner wall surface 17 facing each injection channel 12 at a predetermined interval is formed.

  Then, as shown in FIG. 3, an inclined surface 18 that gradually widens the cross-sectional area of the flow path toward the supply path 14 is provided on an inner wall surface of the inflow path 16 that is continuous with the supply path 14. When such an inclined surface 18 is provided, the ink liquid flowing from the ink cartridge 25 into the inflow path 16 flows along the inclined surface 18 when flowing into the supply path 14 from the inflow path 16. Gradually decreases as the cross-sectional area increases, and the ink liquid slowly flows into the supply path 14. Therefore, when the ink liquid is introduced, the ink liquid that has flowed into the supply path 14 does not violently hit the manifold-side end surface 42 of the actuator 13 and does not foam the ink liquid. Generation can be effectively suppressed, and non-ejection of the ink liquid can be effectively prevented.

  The inclined surface 18 is inclined from the inflow path 16 toward the direction in which the injection channel 20 at the end farthest from the inflow path 16 among the plurality of arranged injection channels 12 is located. By inclining the inclined surface 18 in this manner, the ink liquid flowing into the supply passage 14 from the inflow passage 16 flows so as to spread in the inclination direction of the inclined surface 18, and is arranged at a position farthest from the inflow passage 16. It is also supplied smoothly to the injection channel 20 without foaming.

  Further, as shown in FIG. 3, a step 43 for trapping bubbles in the ink liquid is provided on the inclined surface 18 on the ink inlet 19 side. As shown by the imaginary line in FIG. 3, a filter 44 is attached to the ink inlet 19 so as to prevent dust and the like from entering the supply path 14. The filter 44 is located near the ink inlet 19 to which the filter 44 is attached. In this case, fine bubbles in the ink liquid generated in the supply path 14 move and tend to collect, and if the bubbles grown here adhere to the filter 44, the flow of the ink liquid may be obstructed. By providing the stepped portion 18 on the step 18, it is possible to trap minute air bubbles which are going to move to the vicinity of the ink inlet 19 of the inflow path 16 at the stepped portion 43. The blocking of the filter 44 can be prevented, and a good flow of the ink liquid in the inflow path 16 can be secured. Also, the bubbles trapped in the step 43 do not become difficult to move like bubbles forming a meniscus in the minute opening of the filter 44, and the bubbles are supplied to the supply path 14 side by the flow of ink accompanying the ejection or the like. Can be easily moved, and non-ejection due to bubbles can be prevented beforehand.

  Further, as shown in FIG. 4, the inner wall surface 17 of the supply passage 14 has a substantially inverted U-shaped cross section depressed in a direction away from each injection channel 12. By forming the inner wall surface 17 of the supply path 14 in such a shape, bubbles generated and retained in the supply path 14 can be retained at a depressed position away from each injection channel 12, and thus, the bubbles can be It is difficult to enter the ejection channel 12 to prevent non-ejection of the ink liquid. Further, the deepest portion 45 of the depression on the inner wall surface 17 is located at a position shifted from the center line of each of the arranged injection channels 12, and the left and right side surfaces of the inner wall surface 17 connected to the deepest portion 45 It forms an acute angle with the center line of the channel 12 and is tapered so as to narrow toward the deepest part 45. Further, the deepest portion 45 extends in parallel with the arrangement of the injection channels 12. In this way, by locating the deepest portion 45 of the depression at a position shifted from the center line of each injection channel 12, the bubbles staying in the deepest portion 45 are more laterally separated from the extension direction of each injection channel 12. Since the air bubbles stay at the position, the air bubbles are less likely to enter the ejection channel 12, and the non-ejection of the ink liquid can be more effectively prevented.

  FIG. 6 is a bottom view showing another embodiment of the manifold. As shown in FIG. 6, the supply path 14 is connected to the inflow path 16 and one end of each of the injection channels 12 arranged in two rows. The base portion 46 is formed to have a base end portion 46 for connecting the common portions and branch portions 47 and 48 branched corresponding to the other end portions of the injection channels 12 arranged in two rows. May be formed in the base end portion 46 so as to spread from the inflow passage 16 side to the branch portions 47 and 48 side.

  In this case, since the supply path 14 has a shape corresponding to each of the ejection channels 12 arranged in two rows, the volume of the supply path 14 can be reduced, and the ink liquid flowing from the inflow path 16 is From 18, it can flow along the branch portions 47 and 48, and thus can be smoothly supplied to the injection channels 12 of each row. Therefore, it is possible to effectively suppress the bubbles from remaining in the supply path 14 when the ink liquid is introduced.

FIG. 1 is a perspective view illustrating an embodiment of an inkjet recording apparatus according to the present invention. FIG. 2 is a perspective view of an inkjet head of the inkjet recording apparatus of FIG. It is principal part sectional drawing of the AA line in FIG. FIG. 3 is a sectional view of a main part taken along line BB in FIG. 2. FIG. 3 is a bottom view of the manifold in FIG. 2. It is a bottom view of the manifold of other embodiments. FIG. 4 is a diagram showing a conventional example corresponding to FIG. 3. FIG. 5 is a diagram showing a conventional example corresponding to FIG. 4.

Explanation of reference numerals

12 Injection channel 14 Supply path 16 Inflow path 17 Inner wall surface 18 of the supply path 18 Inclined surface 20 Injection channel 23 located farthest from the inflow path Inkjet head 25 Ink cartridge 43 Step 45 Deepest portion 46 Base end portion 47 48 Branch

Claims (8)

A plurality of ejection channels arranged to eject the ink liquid from the nozzles as droplets, an inflow path into which the ink liquid flows from the ink inlet, and an ink channel for supplying the ink liquid flowing from the inflow path to each ejection channel. In an inkjet head including a supply path,
The supply path is formed to extend in an arrangement direction of the injection channels,
An actuator having the injection channel is joined to a manifold having the supply path so as to constitute one side surface of the supply path,
The inflow passage is connected to the supply passage at one end in the arrangement direction of the injection channels so as to cross the supply passage,
On the inner wall surface of the inflow path that is continuous with the supply path, an inclined surface that gradually increases the cross-sectional area of the flow path toward the supply path is provided.
An ink jet head, wherein the supply path has a shape extending immediately from the inclined surface toward the other end in the arrangement direction of the ejection channels.   The ink jet head according to claim 1, wherein the inclined surface is inclined from the inflow path in a direction in which an ejection channel of the plurality of ejection channels that is farthest from the inflow path is located.   3. The ink jet head according to claim 1, wherein the supply path is connected below the inflow path with the inflow path facing upward.   The inkjet head according to claim 3, wherein the inflow path faces a surface of the actuator that forms one side surface of the supply path.   5. The ink jet head according to claim 1, wherein a filter is attached to the ink inlet of the inflow path. One end of each of the plurality of injection channels is opened at an end face of the actuator on the manifold side,
The inner wall surface of the supply passage in the manifold facing each of the injection channels has a substantially inverted U-shaped cross section depressed in a direction away from each of the injection channels. The inkjet head according to any one of the above.   The inkjet head according to claim 6, wherein the deepest part of the depression on the inner wall surface of the supply path is located at a position shifted from the center line of each of the ejection channels.   The injection channel is provided in a plurality of rows, the supply path is connected to one end of the plurality of rows of the injection channels in the column direction in common and connected to the inflow path, and each row direction of the plurality of rows of the injection channels. 8. A branch portion corresponding to the other end portion, wherein the inclined surface is formed so as to extend from the inflow path side to the branch portion side at the base end portion. The inkjet head according to any one of the above.

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