JPS6111794B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to printing for inkjet printers comprising a plurality of pump chambers connected to a liquid reservoir, the pump chambers communicating with one or more output channels. Regarding the head.

[Conventional technology]

In conventional devices or printers of the type described above, liquids such as ink are typically transferred from a reservoir to a movable printing head via a flexible tube. . The print head moves at high speed and is significantly accelerated or decelerated at the beginning or end of its travel. Therefore, interruptions in operation are unavoidable when using conventional fluid reservoirs that move with the print head along the recording medium. The reason for this is that the printing head moves quickly, causing a vigorous agitation of the liquid, which in turn entrains air into the liquid. In inkjet printers, a condition for functioning as a printing head is that absolutely no air be present in the liquid, so the problematic liquid reservoir described above cannot be used. Furthermore, there is no means for slowing down the movement of the liquid.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION It is an object of the present invention to improve a printing head as described above, which makes it possible to supply liquid to the printing head without the use of flexible tubes, and to provide an ink supply even when the printing head moves rapidly. The purpose is to reliably prevent air from entering the system.

[Means for solving problems]

According to the present invention, the above-mentioned object includes a plurality of pump chambers having an opening above a recording medium, a branch passage connected to each pump chamber, and a common ink passage connected to the branch passages. In addition to being structurally integrated with the ink reservoir to be supplied to the
A filter having capillary properties is disposed at least in a portion between the liquid reservoir and the portion connecting the liquid reservoir and the ink passage, so that air can be prevented from entering the ink passage, and the filter can be used to prevent air from entering the ink passage. This is achieved by being able to move around.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a structural layout diagram of a recording apparatus having a print head according to the present invention, and FIG. 2 is a schematic partial cross-sectional view of the print head according to the present invention, both of which show only the parts necessary for explaining the present invention.

FIG. 1 shows an inkjet printer having a casing 10. FIG. A printing head 11 is provided within the casing 10 and is integrated with a liquid reservoir 12. The pump chamber 13 of the printing head 11 has a piezoelectric crystal (not shown) and an ink channel 14 which opens into a capillary nozzle 15 through which the droplets are directed onto the recording medium, e.g. It is injected onto paper tape 16. The paper tape 16 runs on a rotating drum 17. The paper tape 16 is pulled out from the supply roll 18, passes through a pressure roll 19, a rotating drum 17, and a paper guide 20, and is wound onto a reel 21.

The printing head 11 is fixed on a support 22, which is movably arranged on the shaft 23. Print head 11 can be moved along drum 17 by a drive, not shown.

An embodiment of the print head 11 and liquid reservoir 12 is shown in FIG. Liquid 24 is filled into liquid reservoir 12 through an opening in its upper part, which opening is then closed by plug 25 . The plug 25 is the air passage 2
I have 6. The liquid 24 is led from the liquid reservoir 12 to the pump chamber 13 of the printing head 11 via an ink channel 27 and a branch channel 28 derived from the ink channel 27.

A passageway 27 formed inside the printing head communicates with the liquid 24 of the liquid sump 12 through a hole 29 provided in the bottom 30 of the liquid sump 12. A support ring 31 is housed in the hole 29, and a filter 32 is placed on the support ring 31.

Filter 32 is made of a porous material, which can be formed from a foamed material such as foam rubber or spongy plastic. The pore size of this porous material is chosen such that the pores form capillaries for the liquid 24. The capillary part of this filter is always filled with liquid, which means that no air can pass through the filter 32 and reach the channel 27. The capillary forces are so large that no air can pass through the filter 32 into the passage 27, even if the filter is in direct contact with air for a long time. Prolonged exposure of the filter to air occurs, for example, when an inkjet printer is moved from one location to another. Additionally, when the amount of liquid in the reservoir is low and the print head is accelerated at high speeds, the filter can sometimes become empty.

FIG. 3 shows another configuration of the liquid reservoir 12. In this structure of the liquid reservoir 12, the filter is not located in the hole 29 as shown in FIG.
It is filled throughout. It is also possible for this filter to be installed in only a portion of the liquid reservoir 12. In such a configuration, the filter is quite long in the vertical direction, and when the filter is filled with the recording medium, the static pressure of the liquid acts,
It acts to transport the recording medium through the hole 29a and further through the common ink passage 27 to each pump chamber. With this configuration, the liquid reservoir will not become completely empty as is the case with the configuration shown in FIG.

In the configuration shown in FIG. 3, the filter 32 is connected to the liquid reservoir 1.
2 becomes a very effective damper of liquid movement within the 2.
Furthermore, the pores in the filter 32 can be made larger than the pores in the filter in the case of FIG. Therefore, the filter 3 can be removed without the risk of passing air through the filter into the ink passage 27.
Materials suitable for 2 can be selected relatively freely.

〔Effect of the invention〕

According to the present invention, by structurally integrating the print head with the liquid reservoir, there is no need for flexible tubes or the like to connect the print head and the liquid reservoir.
In addition, a filter having capillary properties is placed at least in a portion between the liquid reservoir and the connection between the ink passage of the printing head and the liquid reservoir, so that the recording medium is allowed to pass through, but the air is allowed to pass through the capillary holes of the filter. Since air is prevented from entering the ink passage, the inkjet is smoothly ejected from the pump chamber to the outside, and good recording can be performed.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a printer equipped with the printing head of the invention, FIG. 2 is a partial sectional view of the printing head of the invention, and FIG. 3 is a partial sectional view of another example of the printing head of the invention. . 11...Printing head, 12...Liquid reservoir, 13
... Pump chamber, 15 ... Capillary nozzle, 16 ... Paper tape, 24 ... Liquid, 27 ... Ink passage, 2
8...branch passage, 32...filter.

Claims (1)

[Claims] 1. A liquid reservoir and structure for supplying ink to the pump chambers, comprising a plurality of pump chambers having openings above the recording medium, branch passages connected to each pump chamber, and a common ink passage connected to the branch passages. and a filter having capillary characteristics is disposed at least in a portion between the liquid reservoir and a portion connecting the liquid reservoir and the ink passage to prevent air from entering the ink passage. 1. A printing head for an inkjet printer, characterized in that the printing head is configured to be able to move on a recording medium, and to be able to move on a recording medium.