JPS5931165A - Ink sucking apparatus of ink jet head - Google Patents

Abstract

PURPOSE:To make the negative suction force in an ink jet head constant to prevent the generation air bubbles in the head, by sucking the ink of the ink jet head after the residual ink in a suction chamber is discharged. CONSTITUTION:When a piston 12 is pushed down to a direction A, ink remaining in a suction chamber 17 is sucked by slight negative pressure generated by the movement of a contact part 15 to an elastic sheet and discharged to a discharge chamber 18 through a discharge hole 12A. By this mechanism, the volume of the suction chamber 17 is made constant in the succeeding negative pressure generating process and negative suction force due to volume expansion is made constant. In the next step, when the piston 12 is further pushed down, ink is sucked from an ink jet nozzle through the suction port 21 in the suction chamber 17 to be emitted and restored.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink suction device for a Sarel inkjet head used in an inkjet printer, and more particularly to an ink suction device for an inkjet head that reduces fluctuations in negative pressure suction force.

Conventionally, in the ink suction device of an inkjet head, if the initial space in the cylinder is too small, the negative pressure suction force of the ink becomes too large, and the dissolved air in the ink becomes bubbles and accumulates in the nozzle and filter section. However, it has the disadvantage that it tends to cause ejection failure.

Furthermore, even if the initial space inside the cylinder is made larger, the sucked ink replaces the air inside the cylinder and occupies the initial space, so the initial space becomes substantially smaller and the negative suction pressure of the ink increases. This will cause bubbles to be generated within the inkjet head. Fig. 1 shows a conventional example, and 1 is an inkjet head, which consists of subtanks la and lb that store ink supplied from main tanks 2a and 2b of different colors, and an inkjet nozzle (not shown) built into each subtank. Eject ink.

3 is a cap attached to the ink ejection end of head 1;
In addition to sealing the tip of the inkjet nozzle to prevent ink from drying and leaking, the suction pump 4 and suction tube 5
Connected by a + 5 b. When negative pressure is generated by the suction pump 4, the cap 3 is opened to open the tank la,
Suction of different color ink from lb. Here suction pump 4
The piston 6 moves downward against the outer wall 5, which is a cylinder, and sucks ink through the tubes 5a5b.The sucked ink is discharged downward from the discharge hole 7 and the check valve 8 when the piston 6 moves upward. . The check valve 8 closes the discharge hole 7 when the piston is moving downward, and opens the discharge hole 7 when the piston moves upward, so that the ink can be suctioned and discharged. 9A,
9 It is fitted to the piston 6 with B'fdOIJing, eliminating the gap between the cylinder and the piston 6.

In this case, ink accumulates in the ink suction chamber 10VC, the volume of the suction chamber 10 decreases, and during the next piston lowering operation, the suction negative pressure increases E7, so that the molten air of the ink is generated as bubbles in the ink. Become.

Also, even if the O-ring 9B slightly separates from the cylinder inner wall when the piston returns, the inside of the cylinder will instantly become atmospheric pressure.
If the negative pressure is large, a backflow of ink containing air bubbles to the inkjet nozzle occurs. When air bubbles are generated in this way, it becomes impossible to restore normal ejection from the nozzle.

SUMMARY OF THE INVENTION The present invention aims to eliminate the above-mentioned drawbacks, and aims to provide a suction device for an inkjet head that can always maintain a constant negative pressure suction force for ink and always restore normal ejection.

The present invention will be explained below based on drawings of embodiments.

FIG. 2 shows an embodiment of the present invention, and the same parts as in FIG.

Reference numeral 11 denotes a cylinder, which has a female threaded part 14 that is screwed into a male threaded part 13 formed on the circumferential surface of the piston 12, and an O-ring 9A for closing the cylinder and piston is attached above the cylinder. The threaded threads 13, 14 have the function of preventing sudden movement of the piston 12 relative to the cylinder 11. At the tip of the piston 12, as shown in the figure, a disc-shaped abutting part 15 having a larger diameter than the piston shaft is formed. This contact part 1
5, the inner wall of the cylinder 11 A11 moves within the interior 16A of the elastic sealing member 16 which is slidable in the direction opposite to A.

The outer diameter of the contact portion 15 is slightly smaller than the inner diameter of the inside 16A of the seal member, and when the piston 12 is pushed down in the direction A, the contact portion 1
The cylinder 11 and the piston 12
and an ink suction chamber J formed by the elastic seal member 16
7 is maintained at atmospheric pressure.

The suction chamber 17 and the ink discharge chamber 18 at the bottom of the cylinder, which is always at atmospheric pressure, are located in the gap between the inner wall of the cylinder and the elastic seal member 16, ink discharge hole 12A of the piston, ink discharge hole 16C of the elastic seal member 16, The piston push-up member 19 communicates with the piston through the communication hole 19A and the like.

The push-up member 19 pushes down the piston 12 and the elastic seal member 1 as shown in FIG. 3 by the elastic force of the spring 20.
6 to IR as shown in the second diagram. In the state shown in FIG. 2, the piston 12 is in the uppermost position, that is, in the initial position where the contact portion 15 is in contact with the upper inner wall protrusion 16D of the elastic seal member 16. The suction chamber 17 and the discharge chamber 18 are in communication with each other through the ink discharge hole 12A as described above.

Next, the operation of the embodiment having the above configuration will be explained. first,
When the piston 12 is pushed down in the direction A from the state shown in Fig. 2,
The ink remaining in the suction chamber 17 and generated is suctioned by a slight negative pressure generated by the movement of the contact portion 15 with respect to the elastic seal 16, and is discharged into the discharge chamber 18 through the discharge hole 12A and the like. As a result, in the next negative pressure generation process,
The volume of the suction chamber 17 is kept constant, and the negative pressure suction force due to volume expansion is kept constant. The lower end surface 15A of the contact portion 15 is
When the lower end of the elastic seal member 16 comes into contact with the inner wall protrusion 16BIC, the elastic seal member 16 also moves down in the direction A,
The pressure inside the suction chamber 17 is made negative. At this time, the degree of negative pressure increases until the seal member 1 16 changes the suction openings following the suction tubes 5a and 5b from closed to open, but before this 1 suction opening changes from closed to open, the elastic seal member 16
comes into contact with the push-up member 19 and receives a return force from the spring 20. When the piston 12 is further pressed down in this state, ink is sucked from the inkjet nozzle into the suction chamber 17 through the suction port 21, the meniscus in the nozzle is normalized, and ejection is restored. When the piston 12 is released from the state shown in FIG. 3, the elastic seal member 16 is pushed up by the spring 20 and rises in close contact with the piston, causing the suction port 21 to change from open to closed while maintaining negative pressure. The operation time of the piston is only a few seconds, and the space inside the cylinder is not filled with ink. Thereafter, the elastic sealing member 16 and the piston 12 are raised by the force of the spring 200, and while contracting the volumetrically expanded suction chamber, the sucked ink is transferred to the discharge chamber 1 through the ink discharge hole 12A16C, etc.
Discharge at 8.

The opening of the ink discharge hole 16C1 and the communication member 19A is large, and the ink can be discharged easily compared to the gap between the piston and the seal member.

Further, a part of the piston 12 is a threaded portion, and the rotational displacement of the piston can be easily varied in vertical motion.As explained above, according to the present invention, the negative pressure suction force of the inkjet head can be kept almost constant. To provide an ink suction device for an inkjet head that prevents the generation of bubbles in the inkjet head due to an increase in the negative pressure suction force caused by the ink remaining after suction, and ensures ejection recovery.jJ
? I can do it.

[Brief explanation of drawings]

Fig. 1...Explanatory diagram of the conventional example Fig. 2...Explanatory diagram of the embodiment of the present invention (initial 1υ1 state) Fig. 3...Explanatory diagram of the conventional example ,? '4 Chomen 1
Figure (suction state) 1... Inkjet head 11... Cylinder 12... Piston 16... Elastic seal member 17... Ink suction chamber exit Applicant: Canon Co., Ltd. ←,” Procedural amendment (voluntary) September 14, 1980 Director of the Patent Office Kazuo Wakasugi 1 Indication of the case 1981 Patent Application No. 127956 2
Name of invention Ink for inkjet head @! +Relationship with Apparatus 3 and the person making the amendment 111 Patent applicant Location 3-30-2 Shimomaruko, IJI-ku, Tokyo Name (100) Canon Co., Ltd. Representative Nagaku Ryu Sanbu 4 Agent Location (7) 146 Tokyo 3-30-2 Shimomaruko, Ota-ku, Tokyo
5. Column 6 of the detailed description of the invention in the specification to be amended, content of the amendment 0 Delete "The push-up member 19 pushes up..." from lines 1D to 16 on page 5 of the specification. oFIA Specification, page 7, line 9 to line 1D, "by the force of the spring 20" is deleted.

Claims (1)

[Claims] An ink suction device for an inkjet head, characterized in that the ink from the inkjet head is sucked after the residual ink in the suction chamber is discharged.