JP4135224B2 - Inkjet recording device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet recording apparatus that performs required recording on recording paper or the like by ejecting ink from nozzle holes.
[0002]
[Prior art]
This ink jet recording apparatus removes bubbles generated in the ink in the recording head, removes dust and ink that is drying, and after newly installing or replacing an ink cartridge as an ink supply source, An ink suction means is provided for introduction into the inside.
[0003]
This ink suction means is generally configured to move the piston in the casing and suck the ink in the recording head by the negative pressure generated in the pump chamber.
[0004]
[Problems to be solved by the invention]
As described above, in the case of using a piston, when the piston moves forward, a negative pressure is generated to suck ink from the recording head through the cap. However, when the piston moves backward, a positive pressure is generated. End up. This positive pressure sends air to the recording head, so that air may enter the ejection channel of the recording head and make ejection impossible.
[0005]
In order to reduce this, it is possible to suppress the generation of positive pressure as much as possible by stopping the piston at the limit of the suction hole in the casing and closing the suction hole immediately when the piston moves backward after moving the piston forward. Conceivable. However, in order to stop the piston accurately, there is a problem that high precision is required for processing and assembly of parts.
[0006]
The present invention has been made to solve the above-described problems, and is intended to reliably suppress the positive pressure from acting on the recording head through the cap and to prevent the ejection failure.
[0007]
[Means for Solving the Problems and Effects of the Invention]
In order to achieve the above object, an ink jet recording apparatus according to claim 1, wherein a recording head having a plurality of ejection channels for ejecting ink from the nozzle holes as droplets and the nozzle hole surface of the recording head are provided. An ink jet recording apparatus comprising: a cap capable of contact and separation; and an ink suction means comprising a pump for sucking ink in the ejection channel through the cap, wherein the pump has a suction hole connected to the cap. And two pistons movable within the casing, a variable capacity pump chamber connected to the suction hole is formed between the two pistons, and the pump chamber communicates with the outside. A discharge hole is formed in the casing at an interval in the moving direction of the piston, and the two pistons Drive means for driving each of the caps, and of the two pistons, the one piston is closer to the suction hole in the casing, and the other piston is closer to the discharge hole in the casing. The drive means is in close contact with the two pistons so that the suction cap covers the nozzle hole surface in a state where the two pistons are in close contact with each other. The other piston is moved in a direction away from the one piston to open the suction hole and stop the discharge hole between the suction hole and the discharge hole at a position where the suction hole is closed, Next, the one piston is moved in the direction of closing the suction hole, and at the same time, the other piston is moved to a capacity of the pump chamber. The piston is moved in the same direction as the one piston so as to be held or enlarged, and the one and the other pistons are stopped at a position where both the suction hole and the discharge hole between the suction hole and the discharge hole are closed. Then, while the other piston is stopped, the one piston is moved in the direction to open the suction hole to further expand the capacity of the pump chamber, and the one piston is moved to the suction hole. Stop at the position to be opened, and then release the cap from the nozzle hole surface and open the discharge hole in a direction away from the one piston while the other piston is stopped. Move to position.
[0008]
With this configuration, a negative pressure is generated in the pump chamber between the two pistons by relative movement of the two pistons, and ink is sucked from the recording head through the cap. The positive pressure generated when one piston moves in the direction of closing the suction hole can be avoided by moving the other piston in the direction of maintaining or expanding the capacity of the pump chamber. Therefore, unlike the conventional case, air does not enter the ejection channel of the recording head and cannot be ejected.
[0009]
Also, when the pump chamber between the two pistons is moved closer to the suction hole and suction is moved closer to the discharge hole, the discharge is executed with a small stroke, and when one piston moves toward the other piston, As described above, the positive pressure generated when the other piston moves in the direction of closing the suction hole can be avoided by moving the other piston in the direction of maintaining or expanding the capacity of the pump chamber. .
[0010]
Further preferably, the drive means includes a cap and a cam that is rotatably provided with a cam follower that drives the two pistons, so that the cap is brought into contact with and removed from the recording head. It is possible to reliably synchronize the operation of moving the pistons relative to each other and to reliably prevent the positive pressure from acting on the recording head through the cap.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view showing an embodiment of an ink jet recording apparatus according to the present invention. The color ink jet recording apparatus 21 includes four recording heads 23 that eject four color inks of cyan, magenta, yellow, and black as droplets. The recording heads 23 are integrally provided as a head unit 24. Along with this head unit 24, an ink cartridge 25 as an ink supply source for supplying four colors of ink to the recording head 23 is detachably mounted on the carriage 26.
[0012]
A recording medium transport roller 27 is rotatably provided in parallel with the reciprocating direction of the recording head 23 so as to face the front surface. The carriage 26 is supported by a carriage shaft 29 extending in the reciprocating direction of the recording head 23 and a guide plate 54 via a carriage shaft support portion 28 provided at the lower portion of the carriage 26, and is bridged between pulleys 30 and 31. The pulley 30 is connected to the belt 32 and is driven to rotate by a motor (not shown) so as to be reciprocated linearly. The recording medium 22 is introduced between the recording head 23 and the recording medium transport roller 27 and is recorded by ink droplets ejected from the recording head 23.
[0013]
FIG. 2 is a cross-sectional view of the main part of the head unit 24. The recording head 23 is made of piezoelectric ceramics, has a plurality of ejection channels 1, and ejects ink as droplets from the nozzle holes of the front surface 11. The manifold 4 is joined to the rear surface of the recording head 23, and the ink introduced from the ink cartridge 25 is supplied to each ejection channel 1. The recording head 23 ejects ink in the ejection channel 1 as droplets from the nozzle holes formed in the nozzle hole surface 11 by deformation of the piezoelectric ceramic constituting one side of the ejection channel 1. In the recording head 23, the actuator may be a thermal head type using a heating element instead of piezoelectric ceramics, or other known types. A cover 5 covers the recording head 23.
[0014]
Further, as shown in FIG. 1, on the side of the roller 27, facing the front of the reset state position of the recording head 23, the wiper device 12 that wipes the ink suction device 10 and the nozzle hole surface 11 of the recording head 23. A protective cap device 13 is provided for covering the nozzle hole surface 11 of the recording head 23 and preventing the nozzle hole surface 11 from drying when recording is not performed. The ink suction device 10 and the wiper device 12 are provided. The protective cap device 13 constitutes a recovery maintaining unit for recovering and maintaining the ejection function of the recording head 23.
[0015]
The ink suction device 10 includes a suction pump 15, a suction unit 16, a waste ink tank 17, and a cam 18, and is configured to drive the suction pump 15 and the suction unit 16 via a cam 18 from a power transmission mechanism (not shown). ing. Then, the suction unit 16 covers the nozzle hole surface 11 of the recording head 23, generates a negative pressure by the suction pump 15, sucks defective ink including bubbles in the supply path 3 and the ejection channel 1, and the like from the ink cartridge 25. The recording head 23 is recovered by sucking new ink. The sucked defective ink is sent to the waste ink tank 17.
[0016]
FIG. 3 is a cross-sectional view of the ink suction device 10 and the wiper device 12. The ink suction device 10 will be described in detail with reference to FIG.
[0017]
The suction unit 16 includes a suction cap 41 that tightly covers the ejection nozzle hole surface 11 of the recording head 23, a moving body 42 that supports the suction cap 41 at the tip, and a storage unit that supports the moving body 42 so as to be slidable. 43, and the suction cap 41 can be moved in the direction of approaching and separating from the recording head 23. The moving body 42 urges the suction cap 41 toward the recording head 23 by a coil spring 44 in a compressed state. The suction cap 41 has a suction recess 45 that faces the ejection nozzle hole of the recording head 23, and the suction recess 45 communicates with the internal space of the moving body 42 through a through hole 46 that passes through the suction cap 41. Yes. An ink discharge hole 48 is provided in the bottom wall surface 47 of the internal space, and a suction tube 49 extending from the suction pump 15 is connected thereto.
[0018]
The rear end portion of the moving body 42 has a cam follower 51 that engages with an inner surface of a protrusion 50 that is provided in an annular shape on one side surface of the cam 18 as a driving means. Therefore, according to the rotation position of the cam 18, the suction cap 41 can be moved to the suction position where the recording head 23 is covered and the standby position where the suction cap 41 is separated from the recording head 23 according to the rotation of the cam 18.
[0019]
The cam 18 is rotatably supported by a shaft 55 supported by bearings 52 and 53 of the frame of the color inkjet recording apparatus 21. The cam is also configured as a gear in a tooth row 56 provided on the outer periphery, and is rotated by a power transmission mechanism (not shown) meshed with the tooth row 56.
[0020]
The suction pump 15 includes a casing 57, a first piston 58, a second piston 59, a first drive shaft 60, a second drive shaft 61, and bearings 62 and 65 that are slidably disposed therein. The casing 57 has a cylindrical shape, and has a suction hole 63 connected to the suction tube 49 on the side wall surface and a discharge hole 64 opened to the waste ink tank 17 at an interval in the sliding direction of the piston. The casing 57 has a first piston 58 and a second piston 59 made of rubber slidably disposed in the axial direction of the casing 57. The first piston 58 has a first drive shaft 60. The second drive shaft 61 is attached to the second piston 59. The first piston 58 is located on the discharge hole 64 side, and the second piston 59 is located on the suction hole 63 side. The second drive shaft 61 is slidably supported by a bearing 62 provided in the axial direction inside the first drive shaft 60, and the first drive shaft 60 is slidably supported by a bearing 65. As shown in FIG. 4, the first drive shaft 60 is provided with a ridge 66 on the outer periphery thereof, and an inner surface of a bearing 65 having a substantially U-shaped cross section is provided with a groove 67 in the axial direction. 66 is slidably disposed in the groove 67. For this reason, the first drive shaft 60 can slide in the bearing 65 in a state in which rotation with respect to the bearing 65 is prevented. Further, the bearing 62 provided in the columnar space in the first drive shaft 60 has a long hole 68 that opens in the cam 18 direction and is long in the axial direction, and the tip of the second drive shaft 61 is inserted into the long hole 68. Since the second sliding pin 69 fixed to the shaft slidably penetrates, the second drive shaft 61 slides within the first drive shaft 60 in a state in which the rotation with respect to the first drive shaft 60 is prevented. Can move. Therefore, the second drive shaft 61 can be supported and moved in a state in which the rotation is prevented with respect to the bearing 62 via the first drive shaft 60.
[0021]
The first sliding pin 70 is also fixed to the tip of the first drive shaft 60 in a state of protruding toward the cam 18. The first sliding pin 70 and the second sliding pin 69 are engaged with a first cam groove 71 and a second cam groove 72 provided on one side surface of the cam 18. Therefore, when the cam 18 rotates, a change in the distance between the rotation center of the cam 18 and the cam grooves 71 and 72 occurs at the positions of both sliding pins 70 and 69, and in response to this change, the first piston 58 and the first piston 58 The two pistons 59 can move in the casing 57, respectively.
[0022]
The wiper device 12 includes a rubber wiper blade 73 and a moving body 74 that supports the wiper blade 73. The movable body 74 is supported by the frame of the color inkjet printer 21 so as to be movable in parallel with the suction cap 41, and the rear end thereof is engaged with the groove of the cam 18. Therefore, the wiper blade 73 can move between the protruding position protruding into the moving path of the recording head 23 and the standby position retracted from the moving path of the recording head 23 by the rotation of the cam 18.
[0023]
The suction operation by the ink suction device 10 will be described in detail with reference to FIGS.
[0024]
When the cam 18 is located at the starting point, as shown in FIG. 5, the pistons 58 and 59 of the suction pump 15 are in close contact with each other to make the volume of the pump chamber 76 substantially zero. Further, the discharge hole 64 is located in the vicinity of both the pistons 58 and 59, while the suction cap 41 is located at a standby position away from the nozzle hole surface 11 of the recording head 23. When the cam 18 is driven to rotate, the pistons 58 and 59 move while being in close contact with each other, and as shown in FIG. 6, the space between the pistons is placed near the suction hole 63 and the suction cap 41 is placed on the nozzle hole surface. 11 to the suction position covering 11. After the suction cap 41 comes into close contact with the nozzle hole surface 11, the second piston 59 remains stationary at the cam rotation angle position A shown in FIG. 12, and the first piston 58 widens the distance from the second piston 59. (FIG. 7), the volume of the pump chamber 76 between the pistons 58 and 59 is enlarged, and the suction hole 63 opens into the pump chamber 76. Therefore, the ink in the ejection channel 1 is sucked through the suction cap 41 and the suction tube 49 into the pump chamber 76 having a negative pressure. This suction operation is performed until the cam rotates to an angle B and stops at an intermediate position between the suction hole 63 and the discharge port 64 shown in FIG.
[0025]
Then, after this state is continued until the rotation angle C, the second piston 59 moves in the direction of closing the suction hole 63 until the angle D, and at the same time, the first piston 58 also maintains the volume of the pump chamber 76 between both pistons. As a result, it moves in the same direction at the same speed, closes the suction hole 63, and stops the suction operation (FIG. 8). The first piston 58 may move at a slightly higher speed than the second piston 2 to enlarge the volume of the pump chamber 76. At this time, the suction cap 41 is in close contact with the recording head 23, but when the second piston 59 closes the suction hole 63, the pump chamber is not compressed, so that no positive pressure is generated and positive pressure is applied to the recording head. There is no action.
[0026]
With the above operation, the first piston 58 is stopped at a position where the discharge hole 64 is still closed. While the first piston 58 is stopped, the second piston 59 moves in the direction of enlarging the pump chamber 76 from the rotation angle E to F, and opens the suction hole 63 (FIG. 9).
Then, since the volume of the pump chamber 76 is larger than the previous suction, the ink is sucked from the recording head with a large suction force. Thus, the previous suction is introduced with a small suction force so that the ink is not bubbled, and after a certain amount of ink is filled, it is introduced with a large suction force.
[0027]
Thereafter, when the suction cap 41 begins to move away from the nozzle hole surface 11 of the recording head, only the first piston 58 moves in the direction of expanding the pump chamber 76 at the rotation angle G, and the discharge hole 64 is opened (FIG. 10). . The ink remaining in the suction cap 41 is sucked by the negative pressure of the pump chamber 76 generated at this time. The second piston 59 starts to close the suction hole 63 at the rotation angle H (FIG. 11), compresses the pump chamber 76, and discharges ink in the pump chamber from the discharge hole 64. Then, the second piston 59 comes into close contact with the first piston 58 and returns to the initial state.
[0028]
In the above description, in the drawing, the second piston 59 reciprocates with the position adjacent to the suction hole 63 as the top dead center, but this is not necessarily required. That is, as apparent from the above description from the rotation angle C, when the second piston 59 returns, the first piston 58 also returns in the same direction, so regardless of the positional accuracy between the second piston 59 and the suction hole 63, Positive pressure is not generated in the pump chamber, and high-precision component processing and assembly are not required.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of an ink jet recording apparatus of the present invention.
FIG. 2 is a cross-sectional view of a main part of a head unit of the ink jet recording apparatus of FIG.
3 is a cross-sectional view of an ink suction device and a wiper device of the ink jet recording apparatus of FIG. 1. FIG.
4 is a cross-sectional view of main parts taken along line AA in FIG. 3;
FIG. 5 is an explanatory diagram of the operation of the suction pump.
FIG. 6 is an explanatory diagram of the operation of the suction pump.
FIG. 7 is an explanatory diagram of the operation of the suction pump.
FIG. 8 is an explanatory diagram of the operation of the suction pump.
FIG. 9 is an explanatory diagram of the operation of the suction pump.
FIG. 10 is an explanatory diagram of the operation of the suction pump.
FIG. 11 is an explanatory diagram of the operation of the suction pump.
FIG. 12 is an explanatory diagram of the operation of the suction pump and the suction cap.
[Explanation of symbols]
1 Ejection Channel 10 Ink Suction Device 15 Suction Pump 18 Cam 23 Recording Head 41 Suction Cap 58 Piston 59 Piston 63 Suction Hole 64 Discharge Hole

Claims (2)

A recording head having a plurality of ejection channels for ejecting ink as droplets from the nozzle holes, a cap that can contact and detach from the nozzle hole surface of the recording head, and the ink in the ejection channels through the cap In an ink jet recording apparatus comprising an ink suction means comprising a pump for sucking,
The pump has a casing having a suction hole connected to the cap, and two pistons movable in the casing, and a variable capacity pump chamber connected to the suction hole between the two pistons. And a discharge hole communicating the pump chamber with the outside is formed in the casing at an interval in the moving direction of the piston,
Drive means for driving the two pistons and the cap, respectively;
Of the two pistons, the one piston is located closer to the suction hole in the casing, and the other piston is located closer to the discharge hole in the casing.
The drive means closely contacts the suction cap so as to cover the nozzle hole surface in a state where the two pistons are closely contacted and positioned near the suction hole, and then the one piston is stopped. , Moving the other piston away from the one piston to open the suction hole and stop the discharge hole between the suction hole and the discharge hole at a position where it is closed, And the other piston is moved in the same direction as the one piston so as to maintain or expand the capacity of the pump chamber, and the one and the other pistons. Is stopped at a position where both the suction hole and the discharge hole between the suction hole and the discharge hole are closed, and then the other piston is stopped. The one piston is moved in a direction to open the suction hole to further expand the capacity of the pump chamber, and the one piston is stopped at a position to open the suction hole. While moving away from the nozzle hole surface, the other piston is moved to a position to open the discharge hole in a direction away from the one piston while stopping the one piston.
An ink jet recording apparatus.   2. The ink jet recording apparatus according to claim 1, wherein the driving unit includes a cam that is provided rotatably with the cap and a cam follower that drives the two pistons.

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