JP2748459B2 - Pressure absorbing device in ink jet recording apparatus and manufacturing method thereof - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device (hereinafter, referred to as a damper) for absorbing pressure of ink generated by acceleration of a carriage in an ink jet recording apparatus.

2. Description of the Related Art In an ink jet recording apparatus, when a carriage moves, a pressure is generated in the flow path in proportion to the product of the acceleration of the carriage, the length of the flow path from the tank to the head, and the specific gravity of the ink. When this pressure is transmitted directly to the nozzles, the ink droplets change and the recording becomes unstable. Conventionally, two methods have been implemented as this measure. One is to arrange the flow path at right angles to the moving direction of the carriage. Another method is to provide a damper in the middle of the flow path.

The structure of the conventional bumper, like the actual opening 60-120840,
It consists of a damper base, a damper spring and a flexible damper film. The damper base has an ink inlet connected to the supply pipe and an outlet connected to the supply pipe, and has a smooth flow path connecting the inlet and the outlet on one surface of the damper base. Further, a damper hole branched from the flow path is formed, a damper spring is arranged at a position facing the damper hole, and a flexible damper film is thermally fused to the damper base from above.

[Problems to be solved by the invention]

An object of the present invention is to improve the reliability and stability of the damper by increasing the pressure absorbing capacity of the damper. Specifically, the present invention is stable with respect to a temporal change in temperature and a large external pressure. It is in providing a damper with a certainty.

It is another object of the present invention to provide a damper that is not affected by manufacturing tolerance variations.

[Means for solving the problem]

The pressure absorbing device of the ink jet recording apparatus of the present invention,
A recording head that discharges ink supplied from an ink supply tank as ink droplets from a nozzle is mounted on an inkjet recording apparatus that performs recording while reciprocating in a direction traversing recording paper, while the moving direction of the recording head is To
While moving while facing the wall surface of the pressure absorbing substrate,
In a pressure absorbing device of an ink jet recording apparatus provided with a pressure absorbing film on at least one side of a wall surface of the pressure absorbing substrate, the pressure absorbing film may have a two-layer structure made of different materials.
One side fixed to the pressure absorbing substrate is made of the same material as the pressure absorbing substrate, while the other side is made of a material having a smaller coefficient of thermal expansion than the material of the one side. Further, a grid-like thin plate is provided between the pressure absorbing substrate and the pressure absorbing film. Further, the pressure absorbing substrate is disposed above the ink supply tank position.

In addition, in the method of manufacturing a pressure absorbing device of an ink jet recording apparatus of the present invention, after the step of fixing the pressure absorbing film to the pressure absorbing substrate, a uniform heat treatment is applied to the pressure absorbing film through a heat treatment process. It is characterized by the following.

〔Example〕

1 and 2 show an embodiment of the present invention. FIG. 1 is an exploded perspective view, FIG. 2 (a) is a front view, and FIG. 2 (b) is a plan sectional view.

A damper 6 is provided between supply pipes 4 and 5 for guiding ink from the ink tank 3 to the inkjet head 2 having the nozzle 1 formed therein.
Is provided. The damper 6 is arranged at a right angle to the reciprocating movement direction as shown in the movement diagram in synchronization with the reciprocation of the head 2 in the direction of arrow A.

The damper 6 includes a damper base 7 and a flexible damper film 8. Damper base 7
A smooth flow path 12 connecting an inlet 9 connected to the supply pipe 5, an outlet 10 connected to the supply pipe 4, and a damper hole 11 is formed in a groove on one surface of the damper base 7. Have been. The damper hole 11 is formed to face both surfaces of the damper base 7, the central portion of which is penetrated and connected, and a damper film 8 such as a flexible polyethylene film or a laminated film of polyethylene or nylon is formed thereon. 7 is hermetically sealed by heat fusion.

When the ink jet head and the damper are at rest, the ink is filled up to the middle of the flow path 13 following the damper hole as shown in the figure. Then, a pressure proportional to the product of the acceleration of the flow path, the length of the flow path from the tank to the head, and the specific gravity of the ink is generated. This pressure is
It is absorbed by the compression of the air in the damper hole and the bending of the damper film. Compared with the conventional damper, the damper according to the present invention can improve the pressure absorbing ability by providing the damper holes on both sides and providing two damper films.

Another embodiment for increasing the pressure absorbing capacity of the damper will be described. The pressure absorbing film has a double structure in which films of different materials are stacked, and a surface (back surface) to be welded to the pressure absorbing substrate is the same material as the substrate, and a reverse surface (front surface) has a lower coefficient of thermal expansion than the substrate material. Use a material. After welding the above film to the damper base without bending, leave it at 40 ° C to 100 ° C for 1 hour or more, and use the difference in the coefficient of thermal expansion between the materials to make it suitable for the damper film part covering the damper hole. Causes significant bending. This is because the substrate material has a higher coefficient of thermal expansion, and a force for pulling the film in the direction of the normal line acts on the entire circumference of the hole, so that uniform bending occurs.
On the other hand, when bending is performed during welding, the film cannot be uniformly bent over the entirety and becomes wrinkled, so that the film is less likely to be deformed due to wrinkles and the pressure absorbing ability is reduced. Since the bending of the film caused by the above-mentioned processing occurs uniformly, it is possible to respond to the rapid pressure fluctuation caused by the carriage movement with good responsiveness.

When absorbing and discharging ink by a pump (not shown) from the front of the ink jet head, the damper film bends to the inside of the hole due to a negative pressure inside the damper hole, and is caused by the surface tension of the ink filling the hole. Even if the films attract each other and abrupt pressure fluctuations occur due to the movement of the carriage, the film cannot be deformed if the force is less than this attractive force, and the film is held. For this reason, the pressure generated when the head and the damper are mounted on the carriage or the like and moves as described above cannot be sucked by the bending of the damper film, and the pressure is directly transmitted to the nozzles, the ink particle diameter changes, and recording is performed. Becomes unstable. The force holding the film is given by equation (1).

2TScosθ / d + TLsinθ (1) d: Film interval T: Surface tension of liquid θ: Contact angle S: Area of liquid layer L: Length around liquid layer According to formula (1), the film is held inside the damper hole. The force is better the wider the gap between the films, and in practice it needs to be 2mm or more.

FIG. 3 shows that the damper film 8 has a damper hole 11.
This is another embodiment for preventing stabilization in the apparatus. The damper hole is covered with a net-like member 14 having an appropriate mesh diameter from the damper base, and the damper film is welded from above to prevent the damper film from bending into the damper hole.

FIG. 4 is an embodiment aiming at further improving the reliability and stability of the damper. When the carriage moves in the inkjet recording apparatus, a pressure is generated in the flow path in proportion to the product of the acceleration of the carriage, the length of the flow path from the tank to the head, and the specific gravity of the ink. This pressure is absorbed by the compression of the air inside the damper and the bending of the damper film.However, the above factors mainly cause a sudden increase in pressure or fluctuations in pressure, and the inside of the damper becomes positive, and if this pressure is transmitted directly to the nozzle The ink particle diameter changes, and recording becomes unstable. In order to absorb this pressure more reliably, the damper 6 is installed above the ink tank 3 as shown in FIG. The pressure generated is due to the above factors, and the pressure value in the damper changes due to the fluctuation of the water head value in the ink tank. By setting the difference ι to 8 cm or more, it is possible to absorb pressure fluctuations that can be almost generated.

〔The invention's effect〕

As described above, according to the pressure absorbing device of the ink jet recording apparatus and the method of manufacturing the same according to the present invention, the pressure absorbing film fixed to the pressure absorbing substrate is provided with uniform bending along the film surface, Since the grid-like thin plate is arranged between the pressure absorbing substrate and the pressure absorbing film in the apparatus, even if the ink pressure suddenly fluctuates due to the movement of the carriage, the behavior of the pressure absorbing film is hindered. In addition, since the ink pressure fluctuation is absorbed quickly, the diameter of ink particles ejected from the ink jet head does not vary, so that high quality printing can be realized.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing one embodiment of the pressure absorbing device of the present invention. 2 (a) and 2 (b) are a front view and a plan sectional view of the embodiment shown in FIG. 1, respectively. FIG. 3 is a view showing another embodiment for increasing the pressure absorbing capacity of the damper of the present invention. FIG. 4 is an explanatory view of an embodiment aiming at further improving the reliability and stability of the damper of the present invention. 6 Damper 7 Damper base 8 Damper film 11 Damper hole

Claims (4)

(57) [Claims] A recording head for discharging ink supplied from an ink supply tank from a nozzle as ink droplets;
While mounted on an ink jet recording apparatus that performs recording while reciprocating in a direction traversing the recording paper, while moving in the moving direction of the recording head while opposing the wall surface of the pressure absorbing substrate, the pressure absorbing substrate wall surface In a pressure absorbing device of an ink jet recording apparatus having a pressure absorbing film on at least one side, the pressure absorbing film has a two-layer structure made of a different material, and one side fixed to the pressure absorbing substrate is the same as the pressure absorbing substrate. A pressure absorbing device in an ink jet recording apparatus, wherein the other side is made of a material having a smaller thermal expansion coefficient than that of the one side. 2. A pressure absorbing device in an ink jet recording apparatus according to claim 1, wherein a grid-like thin plate is disposed between said pressure absorbing substrate and said pressure absorbing film. 3. The pressure absorbing device according to claim 1, wherein the pressure absorbing substrate is disposed above the position of the ink supply tank. 4. An ink jet recording apparatus according to claim 1, wherein said pressure absorbing film is fixed to said pressure absorbing substrate, and heat treatment for imparting inward bending to said pressure absorbing film is performed. Manufacturing method of pressure absorbing device.