JPH07171971A - Ink jet device and pump therefor - Google Patents

Abstract

PURPOSE:To prevent generation of fixing of ink in a pump occurring due to thickening of viscosity of the ink during standby of the pump. CONSTITUTION:A pump comprises a cylinder 103 and a piston 105 for generating a pressure change for discharging an ink from a discharge opening of an ink jet head into an inner space to be formed by fast contact with the cylinder 103. When the piston 105 is at a standby position, the fast contact of the cylinder 103 and the piston 105 is released.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head having a pump for discharging ink from the ink jet head in order to maintain or recover ink jet from the ink jet head in a good state. The present invention relates to a device and a pump for the inkjet device.

[0002]

2. Description of the Related Art Conventionally, a plunger pump has been used mainly as a unit, for example, as a pump which is an ink discharging means mounted in a recovery system of an ink jet recording apparatus. In this pump, the contact sealing surface of the piston that reciprocates in the cylinder with the cylinder is always in close contact with the inner surface of the cylinder.

[0003]

In such a conventional ink jet recording apparatus, the ink adhering to the contact seal surface of the piston sometimes thickens after being left for a long period of time. Since the pressure is constantly applied to the contact seal surface of the piston so as to be in close contact with the cylinder, the thickened ink may cause the piston to firmly adhere to the inner surface of the cylinder. As a result, when the pump is driven after being left for a while, the pump is firmly fixed more than the driving energy generated by the driving source, the operation of the device cannot be performed, and there is no choice but to repair the product. there were. This will significantly reduce the reliability of the device, so in general, deal with the driving force of the drive source as being larger than necessary so that the pump unit can be driven even in such a fixed state. The method of doing has been taken. However, in such a countermeasure, not only is extra energy wasted when the pump is not stuck, but the extra energy mainly appears as noise, which is a problem.

In particular, when a water-resistant ink is used, the above-mentioned problems are more likely to occur because the content of non-volatile components is relatively large.

An object of the present invention is to provide an ink jet apparatus having a highly reliable pump which does not cause the above-mentioned problems and a pump for the ink jet apparatus.

[0006]

An ink jet device of the present invention that achieves the above-mentioned object has an ink jet having a pump for discharging ink from an ejection port of the ink jet head and a member for mounting the ink jet head. In the apparatus, the pump has a cylinder and a piston that causes a pressure change for discharging ink from the discharge port in an internal space formed in close contact with the cylinder, and when the piston is in a standby position, It is characterized in that the close contact between the cylinder and the piston is released.

Also, the ink jet device pump of the present invention is an ink jet device pump for discharging ink from an ejection port of an ink jet head, wherein the pump is a cylinder and an internal space formed in close contact with the cylinder. And a piston that causes a pressure change for discharging ink from the ejection port, and when the piston is in the standby position, the close contact between the cylinder and the piston is released.

[0008]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a perspective view showing the main part of the ink jet device according to the present invention. In FIG. 2, the carrier 2
On 03, a head cartridge 202 in which an ink jet head (recording head) 200 constituting a recording unit and an ink tank 201 are connected is mounted. One end of the carrier 203 on the recording head 200 side has a lead screw 21 rotatably attached to the chassis 1.
3 is slidably fitted in the axial direction. A guide is arranged at the other end of the carrier 203, and the guide is slidably fitted in the guide rail 2 formed on the chassis 1 in parallel with the axial direction of the lead screw 213. The carrier 203 is configured to be able to reciprocate in the axial direction with the rotation of the lead screw 213 while keeping its posture always constant.

As shown in FIG. 2, the lead screw 213
The lead screw gear 257 fixed to the left end of the pinion gear 256 is meshed with the pinion gear 256 fixed to the output shaft of the carrier motor 255. Further, as shown in FIG. 3, the lead pins 209 attached to the carrier 203 are fitted into the guide strips 268 that are spirally formed on the lead screw 213 at a predetermined pitch. Therefore, as the carrier motor 255 is driven in the forward and reverse directions, the lead screw 2
When 13 rotates, the carrier 203 reciprocates.
Incidentally, FIG. 3 is an enlarged cross-sectional view showing the carrier bearing portion according to the present invention.

In this ink jet device, the recording head 200 is driven in synchronization with the reciprocal movement of the carrier 203 to eject ink in accordance with a recording signal, thereby performing one-line recording on the recording material 3. The recording head 200 includes an ejection port for fine ink, an ink path communicating with the ejection port, and an energy generation unit for generating energy used for ejecting ink from the ejection port. Examples of the energy generating means include an electromechanical converter such as a piezo element, a means for irradiating electromagnetic waves such as a laser onto ink to generate heat, or an electrothermal converter such as a heating element for generating heat energy. Among these, the recording head provided with the thermal energy generating means can perform high-resolution recording because the ejection ports can be arranged at a high density. Among them, the recording head provided with the electrothermal converter is easy to be made compact, and the technological progress and the improvement of reliability in the recent semiconductor field are remarkable.
This is advantageous because the advantages of C technology and micro processing technology can be fully utilized, high-density mounting is easy, and the manufacturing cost is low.

When one line is recorded by scanning the carrier 203, the recording material 3 is conveyed by one line by the conveying means and the next line is recorded.
Is carried by a rotary pair of the transport roller 4 and the pinch roller 8 that is in pressure contact with the transport roller 4, and a rotary pair of the discharge roller 7 and the spur 6 that is in contact with the discharge roller 7. This will be specifically described. The recording material 3 having a recording surface facing the ejection opening surface of the recording head 200 is conveyed by a pinch roller 8 to a conveying roller 4.
Then, the paper is fed to the recording position by a necessary amount by rotating the feeding roller 4 by the paper feeding motor 5 as necessary. After recording, the recording material 3 is pressed against the discharge roller 7 by the spur 6 and is discharged and conveyed outside the apparatus by the rotation of the discharge roller 7. The conveyance roller 4 and the discharge roller 7 are driven by the paper feed motor 5,
The transmission of the driving force is performed by the reduction gear train 15.

FIG. 4 is an exploded perspective view showing the left end portion of the lead screw 213 including a clutch mechanism for transmitting the driving force of the carrier motor 255 to the recovery system via the lead screw 213. An initial lock 258, a clutch plate 260, a clutch gear 259, and a return spring 261 are arranged at the left end of the lead screw 213.

The initial lock 258 is fixed to the lead screw 213. The clutch gear 259 is fitted to the lead screw 213 so as to be slidable in the axial direction, and part of the clutch gear 259 enters the inside of the initial lock 258. That is, the clutch gear 259 is formed with projections 262 at two asymmetrical positions on the circumference, and the projections 262 are fitted in the recesses 263 formed in the initial lock 258 in the same phase as the projections 262 so as to be axially movable. I am fit.

A flange 267 is provided on the end surface of the clutch gear 259 on the lead screw gear 257 side.
Trigger teeth 259 a for giving a rotation trigger to the control gear 102 are formed on 67. A gear is formed on the outer periphery of the control gear 102, and when the lead screw 213 is incorporated into the recovery system plate 271, it is in a position where it meshes with the clutch gear 259 on the lead screw 213. However, during the recording operation, the control gear 102 does not mesh with the clutch gear 259 because a part of the outer peripheral gear, which is partly cut away, faces the clutch gear 259. A side gear 102h having several teeth is formed on the side surface of the cut-out portion of the gear. This side gear 102h
Engages with the trigger teeth 259a of the clutch gear 259 to give a rotation trigger to the control gear 102.

FIG. 5 is a perspective view showing a recovery system unit according to the present invention. In FIG. 5, a cap 101 that caps the ejection port surface of the recording head 200, and a negative pressure inside the cap 101 ejects ink from the ejection port.
A pump unit 150 sucking through 01 and sending out to the waste ink absorber, and further, the cap 101 is moved back and forth with respect to the ejection port surface, and the pump unit 1
A cam for transmitting a driving force to 50 and for operating a wiping mechanism for wiping the ink adhering to the ejection port surface,
Control gear 102 of the transmission mechanism section including a gear mechanism
Etc. are configured. And the control gear 10
The rotational driving force of the carrier motor 255 is transmitted to the motor 2 through the clutch gear 259 described above.

FIG. 1 is a sectional view showing a pump unit according to the first embodiment of the present invention. The pump unit 150 of this embodiment has a plunger pump configuration as shown in FIG. The pump according to this embodiment includes a cylinder 103
And a piston that causes a pressure change for discharging ink from the ejection port of the recording head in an internal space that is formed in close contact with the cylinder, and a piston that is in close contact with the shaft portion of the piston and the cylinder. Pump seal 1 provided
10 and. The piston according to this embodiment has a shaft 104.
And the elastic member 105 loosely fitted to the shaft, the shaft 104 and the elastic member 10 are provided for convenience.
5 is called a piston. The cylinder 103 and the plunger 104 are made of polyoxymethylene (POM), and the piston 105 and the pump seal 110 are made of silicon rubber.

A plunger 104 is provided inside the cylinder 103 with the cap 101 covering the ejection port of the recording head 200.
A negative pressure is generated inside the piston 105 attached to the recording head 200 by the reciprocating motion of the piston 105.
1 and ink is sucked through the ink suction port 103a,
The ejection function is restored or maintained in a good state. The reciprocating motion of the piston 105 is given by the rotation of the stroke gear 106 having the projection 106a that fits with the lead groove 104a provided in the plunger 104. Further, the rotational force of the stroke gear 106 is given by meshing with the control gear 102 described above, and as a result, the rotational driving force is transmitted from the carrier motor 255.

The cap 101 can be brought into and out of contact with the recording head 200, and its operation is performed by the cam of the control gear 102 described above. Generally, the cap is made of an elastic material having low gas permeability and excellent ink resistance, and in this embodiment, it is made of chlorinated butyl rubber. The pump seal 110 is an elastic seal member that is in close contact with both the inner circumference of the cylinder 103 and the outer circumference of the plunger 104 and is provided to realize a closed space inside the pump. The cap lever 107 is a member that relays between the cap 101 and the inside of the cylinder 103, and is provided with an ink flow path. Also, the ink flow path is
The cap lever seal 108 and a stainless steel (SUS) steel ball 109 seal the airtightness between the ink suction port 103a of the cylinder and the contact surface 101a of the cap 101 with the recording head.

In the present embodiment, as shown in the enlarged view of FIG. 1, the diameter of a part 103c of the inner circumference of the cylinder 103 is made larger than the other parts so that the piston 105 is in the top dead center during standby. The outer circumference of the piston 105 and the inner circumference of the cylinder 103 are prevented from contacting each other. Of the inner circumference of the cylinder 103, the diameter of the portion 103c is 5.3 mm and the diameter of the other portions is 4.
It is set to 9 mm. As a result, the piston 105 and the cylinder 103 almost never come into contact with each other when the pump is on standby and left, so that they are not fixed by the ink.

FIG. 6 is a partially enlarged sectional view showing a cylinder of a pump unit according to the second embodiment of the present invention. In the present embodiment, the roughness of the surface of the large diameter portion 103c of the inner circumference of the cylinder 103 described in the first embodiment is increased. The roughness of the large diameter portion 103c of the inner circumference of the cylinder 103 is 100S, and the roughness of other portions is 0.8S. As a result, the ink is present in the valleys of the unevenness of the portion 103c, and the amount of the ink in the uneven ridges that may come into contact with the cylinder 103 is reduced.

FIG. 7 is a partially enlarged sectional view showing a cylinder of a pump unit according to the third embodiment of the present invention. In this embodiment, a groove 103b is provided as an example of a recess in the large diameter portion 103c of the inner circumference of the cylinder 103 described in the first embodiment. The depth of the groove 103b is 0.3 to 0.5 at the deepest part.
It is set to mm. As a result, the ink on the inner surface of the cylinder is guided to the groove by the capillary force, so that the cylinder and the piston hardly come into contact with each other via the ink, and the sticking can be further prevented.

In each of the above embodiments, the cylinder 103
When the ink repellent treatment was applied to the portion 103c having a large inner diameter, the ink was less likely to remain in this portion, so that a further effect could be obtained. Here, as an ink repellent agent, a water repellent fluororesin "CYTOP"
(Asahi Glass Co., Ltd.) was used.

Further, in each of the above embodiments, the diameter of the piston shaft 104 when the piston 105 is in the standby position is made smaller than that of the other portions, so that the piston shaft 104 and the seal member 110 are in close contact with each other. When they were opened, they were not fixed by the ink, and more favorable results were obtained.

[0025]

According to the present invention, when the piston of the pump is in the standby position, the close contact between the cylinder and the piston is released. Therefore, even if the pump is left unused for a long period of time, the cylinder and the piston are not exposed to the ink. It will not stick. Therefore, according to the present invention, it is possible to obtain a highly reliable inkjet device and inkjet pump.

[Brief description of drawings]

FIG. 1 is a sectional view showing a pump unit according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a main part of the inkjet device according to the present invention.

FIG. 3 is an enlarged sectional view showing a carrier bearing portion according to the present invention.

FIG. 4 is an exploded perspective view showing a left end portion of a lead screw including a clutch mechanism according to the present invention.

FIG. 5 is a perspective view showing a recovery system unit according to the present invention.

FIG. 6 is a partially enlarged sectional view showing a cylinder according to a second embodiment of the present invention.

FIG. 7 is a partially enlarged sectional view showing a cylinder according to a third embodiment of the present invention.

[Explanation of symbols]

 1 Chassis 2 Guide Rail 4 Conveyor Roller 5 Paper Feed Motor 101 Cap 102 Control Gear 103 Cylinder 104 Plunger 105 Piston 110 Pump Seal 200 Inkjet Head 201 Ink Tank 203 Carrier 213 Lead Screw 255 Carrier Motor 259 Clutch Gear

Claims (14)

[Claims] 1. An ink jet apparatus having a pump for discharging ink from an ejection port of an ink jet head and a member for mounting the ink jet head, wherein the pump is a cylinder and an interior formed in close contact with the cylinder. And a piston that causes a pressure change for discharging ink from the discharge port in the space,
An ink jet device, wherein the cylinder and the piston are released from contact when the piston is in a standby position. 2. The ink jet apparatus according to claim 1, wherein a diameter of an inner wall of the cylinder corresponding to the standby position is larger than that of other portions. 3. The ink jet apparatus according to claim 2, wherein the surface roughness of the inner wall of the cylinder corresponding to the standby position is larger than that of other portions. 4. A recess is provided in an inner wall of the cylinder corresponding to the standby position.
Inkjet device. 5. The inner wall of the cylinder corresponding to the standby position is ink repellent.
Inkjet device of either. 6. The ink jet apparatus according to claim 1, wherein the ink jet head has an energy generating unit that generates energy used for ejecting ink from the ejection port. 7. The ink jet apparatus according to claim 6, wherein the energy generating means is an electrothermal converter that generates heat energy as the energy. 8. A seal member is provided between the shaft of the piston and the cylinder so as to be in close contact with them,
The ink jet apparatus according to claim 1, wherein when the piston is in the standby position, the contact between the shaft of the piston and the seal member is released. 9. A pump for an inkjet device for discharging ink from a discharge port of an inkjet head, wherein the pump discharges ink from the discharge port into a cylinder and an internal space formed in close contact with the cylinder. A pump for an ink jet device, comprising: a piston that causes a pressure change, and when the piston is in a standby position, the close contact between the cylinder and the piston is released. 10. The ink jet apparatus pump according to claim 9, wherein the diameter of the inner wall of the cylinder corresponding to the standby position is larger than that of other portions. 11. The ink jet apparatus pump according to claim 10, wherein the surface roughness of the inner wall of the cylinder corresponding to the standby position is larger than that of other portions. 12. The pump for an inkjet apparatus according to claim 10, wherein a recess is provided in an inner wall of the cylinder corresponding to the standby position. 13. The ink-repellent inner wall of the cylinder corresponding to the standby position.
12. A pump for an inkjet device according to any one of 12. 14. A seal member is provided between the shaft of the piston and the cylinder so as to be in close contact therewith, and when the piston is in the standby position, the shaft of the piston and the seal member are in close contact with each other. 10. The ink jet apparatus pump according to claim 9, wherein the pump is opened.