JPH0459145B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to an on-demand inkjet printer. In particular, the present invention relates to an ink jet printer equipped with a nozzle cap for protecting ink jet nozzles and preventing clogging.

<Prior art> Conventionally, this type of device is constructed as shown in the cross-sectional views of FIGS. (Dot chain line) It is pressed against the head 1 to protect the nozzle and prevent clogging. Purging operations such as filling the ink flow path in the head up to the nozzle 2 and removing trapped air bubbles are performed by pressurizing the ink cartridge etc. in Fig. 5 and pouring out the ink in the ← direction. In the figure, nozzle cap 4
This is done by suctioning with a pump 12 through a pipe 9 communicating with the ink and flowing the ink in the ← direction.

One problem with conventional devices of this type is that when the nozzle cap 4 is pressed against the head 1, air tends to be pushed through the tip of the nozzle 2, especially when the impact of the pressing is strong. The second problem is that in the case of nozzle cap 4 in Fig. 6, pump 12
Due to the suction, the space inside the nozzle cap 4 becomes negative pressure, and if the nozzle cap 4 is separated from the head 1 without waiting for the negative pressure to be released, air bubbles will be drawn into the nozzle 2 due to the impact. . The third problem, and the most difficult one, is that for the reasons mentioned above, air is forced in from the tip of the nozzle 2, or in the case of Fig. 6, the space inside the nozzle cap 4 or the pump 12. The air in the pipe 9 that communicates with the nozzle 2, and the air portion 7 at the tip of the meniscus 3 that is normally formed in the nozzle 2, expands when the nozzle cap 4 is placed against the head 1 and the temperature rises during rest or long-term storage. The pressure causes the meniscus 3
This overcomes the surface tension of the ink and pushes the ink back toward the cavity. For the reasons mentioned above, the next time you try to print, ink will not be ejected due to the forced air.

<Purpose> The present invention is intended to solve such problems, and its purpose is to prevent the ink from flowing into the head of the meniscus in the nozzle caused by pressure fluctuations in the cap chamber, without impeding the moisturizing effect of the nozzle. An object of the present invention is to provide an inkjet printer that reliably prevents backtracking.

<Structure> The inkjet printer of the present invention includes a head provided with at least one ink ejection nozzle, a nozzle cap that covers the nozzle and forms a cap chamber between the nozzle and the head, and a pipe connected to the cap chamber. and a damper chamber that communicates with the damper chamber and includes a flexible member that absorbs pressure fluctuations within the cap chamber.

<Example> Fig. 1 is a sectional view for explaining an example of the present invention, in which 4 is a nozzle cap, 5 is a cap holder that holds the nozzle cap 4, and 6 is a cap holder that is bonded or heat-sealed to the cap holder 5. It is a flexible member affixed by, etc. Nozzle cap 4 and
The boundary with the cap holder 5 and the attachment part between the flexible member 6 and the cap holder 5 are completely sealed to prevent the tip of the nozzle 2 from coming into direct contact with the outside air. The flexible member 6 is optimally made of a thin material such as rubber, a polymer material, or a metal film, and can be attached mechanically as well as by adhesion or thermal fusion.

Because of this structure, even if the space inside the nozzle cap 4 or the space 7 in the mechanical part becomes a negative pressure state or a pressurized state due to pressing or separation of the nozzle cap 4 or a rise in temperature, the chain line As shown, the flexible member 6 bends to absorb pressure fluctuations in the space formed between the nozzle cap and the head, so that the meniscus 3 is not affected.

FIG. 2 shows a streamlined version of the previous embodiment by forming a thin wall portion 8 in a part of the nozzle cap 4, and the operation is the same.

In FIG. 3, 9 is a pipe communicating with the inside of the nozzle cap 4, 10 is a case body connected to the pipe 9, and 6 is a flexible member attached to the case body 10 by adhesive, heat-sealing, or mechanically. It is. Each member is nozzle 2
is completely sealed to prevent direct contact with outside air.
Furthermore, by applying the previous embodiment, it is also possible to integrate the case body 10 and the flexible member 6.

By adopting such a structure, pressure fluctuations generated by bending the flexible member 6 as shown by the chain line are absorbed, and the meniscus 3 of the nozzle is not affected.

This embodiment is effective when it is not possible to attach the flexible member 6 directly to the nozzle cap 4 or cap holder 5, but if this is applied, it can be used to attach the flexible member 6 to the nozzle cap 4 or the cap holder 5. Can be installed anywhere. That is, an example thereof is shown in FIG.

<Effects> As described above, according to the present invention, by providing a damper chamber that communicates with the cap chamber via a pipe and includes a flexible member that absorbs pressure fluctuations within the cap chamber, it is possible to increase the flexibility of the cap itself. Compared to the case where a flexible member is attached to absorb pressure fluctuations, the area of the flexible member can be increased regardless of the size of the cap, so the ability to absorb pressure fluctuations can be increased. This can more reliably prevent the ink meniscus from retreating into the head. Furthermore, the flexible member is usually a thin film-like material that bends easily, but if such a film-like member is attached to the cap, water vapor will pass through it, making it impossible to maintain the moisturizing effect of the cap on the nozzle area. . However, in the present invention, the damper chamber is provided so as to communicate with the cap chamber via a pipe, so that pressure fluctuations within the cap chamber can be absorbed while maintaining the original effect of the cap. Furthermore, by providing the damper chamber separately from the cap, there is an effect that both the damper chamber and the cap can be easily manufactured.

By communicating the suction pump with the cap chamber through the damper chamber, that is, by providing a damper chamber in the middle of the pipe connecting the cap and the suction pump, the pulsating flow caused by the suction pump can be smoothed out in the damper chamber. , it becomes possible to transmit stable suction force to the cap side.

This has the remarkable effect of making it possible to perform constant suction without variation in the amount of suction.

In addition, by providing a damper chamber in the middle of the pipe that connects the nozzle cap and the suction pump, the sucked ink can be held in the damper chamber, so the ink in the damper chamber also acts as a moisturizing means for the nozzle, and is absorbed into the cap. To moisturize a nozzle without providing a moisturizing means or separately providing a liquid tank for moisturizing the nozzle in communication with a cap.

[Brief explanation of the drawing]

1, 2, 3, and 4 are sectional views for explaining one embodiment of the nozzle cap of an inkjet printer of the present invention, and FIG.
FIG. 6 is a sectional view for explaining a nozzle cap of a conventional inkjet printer. DESCRIPTION OF SYMBOLS 1... Head, 2... Nozzle, 3... Meniscus, 4... Nozzle cap, 5... Cap holder, 6... Flexible member, 9, 11... Tube, 10...
...Case body, 12...Pump.

Claims (1)

[Scope of Claims] 1. A head provided with at least one ink ejecting nozzle, a nozzle cap that covers the nozzle and forms a cap chamber between the head and the nozzle cap, and a suction device that communicates with the nozzle cap via a pipe. An inkjet comprising: a pump, and a damper chamber provided with a flexible member for absorbing pressure fluctuations in the cap chamber is provided in the middle of a pipe connecting the nozzle cap and the suction pump. printer.