JPH0351157Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a print head for an inkjet recording device, and relates to a print head that has an improved ink tank that supplies ink at a constant liquid pressure.

Prior Art Inkjet recording devices generally have the advantage of being extremely low noise and capable of high-speed recording, as well as being able to use inexpensive plain paper and not requiring complex processing such as development and fixing. Furthermore, the small-diameter dots and reduced dot spacing enable high-resolution image recording, and are also effective for recording kanji characters, figures, etc.

Regarding inkjet recording heads (hereinafter referred to as print heads) of inkjet recording apparatuses, several systems have been developed and put into practical use.

For example, as shown in Japanese Patent Publication No. 53-12138,
An inkjet recording method called an on-demand method has been developed in recent years and is attracting attention. This is an inkjet recording device that ejects ink droplets from a nozzle by changing the volume of a pressure chamber each time an electrical pulse is applied to a print head in response to an electrical signal for recording.

The feature of this on-demand method is that ink is ejected only when needed in response to image signals, eliminating the need for a system to collect unnecessary ink, resulting in low ink consumption and high reliability. In addition, the recording device itself can be made small, lightweight, and inexpensive. Another feature is that a large number of channels can be easily mounted on one print head, resulting in high resolution and high-speed printing performance, and color printing is also easy.

Furthermore, Japanese Patent Publication No. 54-35936 discloses an on-demand type inkjet recording device that has put the above method into practical use. This method uses a method in which multiple nozzles are mounted within one print head.

1 and 2 are schematic diagrams of the structure of an inkjet recording head, showing a sectional view and a plan view, respectively.

In the figure, a plurality of nozzles 1, a plurality of pressure chambers 2 each communicating with the nozzles 1, and the pressure chambers 2 are shown.
The parts 1, 2,
3 are arranged in the same plane.

Recording ink flows from ink tank 6 to filter 5
The ink is then supplied to the common ink chamber 3 of the print head through an ink supply pipe 4. The common ink chamber 3 is branched into a plurality of pressure chambers 2 communicating with a plurality of nozzles 1 corresponding to pixels in the vertical direction of the image. Further, a piezoelectric transducer 7 electrically connected to an electronic pulse generator 8 that outputs pulses based on a print signal is adhered to a part of the wall of each pressure chamber 2. The piezoelectric transducer 7 is a suitable flexible plate that can be bent inward into the pressure chamber 2 when it receives an electric signal from the generator 8, and is made of, for example, a piezoelectric crustal, and the piezoelectric transducer 7 has a conductive thin film that bends the pressure chamber 2. Glued to the outside wall.

In this method, the piezoelectric transducer 7 is suddenly bent inward into the pressure chamber 2 by an electric signal from the electronic pulse generator 8, and the resulting rapid decrease in the volume of the pressure chamber 2 causes the ink inside to become particles. The ink is ejected from the nozzle 1 as small ink droplets, and is caused to fly and reach the opposing recording paper to achieve dot recording.

Ink stored in the common ink chamber 3 flows into the pressure chamber 3 to compensate for the decrease in ink in the pressure chamber 2 due to ink droplet ejection. Furthermore, the decrease in ink in the common ink chamber 3 is replenished by deformation of the flexible membrane 9 forming a part of the wall of the common ink chamber 3 and by supplying ink from the ink tank 6.

The flexible membrane 9 is bonded to cover the opening of the common ink chamber 3 of the print head to form a flexible upper wall and seal the ink inside the chamber 3.

Further, the volume of the common ink chamber 3 is made sufficiently large relative to the amount of change in volume of the pressure chamber 2.

The common ink chamber 3 and the flexible membrane 9 are configured to be filled with ink and absorb the return pressure of ink caused by deformation of the pressure chamber 2 during ink ejection. That is, in a multi-nozzle type print head, a pressure wave generated from the pressure chamber of one channel spreads to the pressure chamber of another channel via a common ink chamber, and the ink droplets of the other channel are ejected. The common ink chamber 3 and the flexible membrane 9 can prevent such pressure waves from going around, although so-called channel interaction, which deteriorates the characteristics, occurs.

However, since the flexible membrane 9 of the common ink chamber 3 of the print head is conventionally made of a thin film of polypropylene, polyethylene, polyvinylidene chloride, etc., it is extremely easy to tear, and in order to bond these thin films, special treatment is required for the print head. , for example, is attached by adhesion using a silane coupling treatment, but there is a risk of ink leakage, and it is also difficult to replace.

There are also examples in which a metal plate is used in place of the flexible membrane 9, but due to its lack of flexibility, it cannot sufficiently absorb changes in ink volume, resulting in unstable ink pressure within the print head. becomes. Therefore, the internal pressure between the ink pressure chambers 2 between the nozzles 1 and the common ink chamber 3, that is, between the channels, is not stable, so that the flying state of the ink droplets ejected from the nozzles 1 differs from one nozzle to another. Summarizing the drawbacks of the conventional method: Because it is a thin film of plastic, it is easily torn and the adhesive peels off, making it difficult to replace and the workability of adhesion is poor, resulting in high labor costs.

Purpose of the invention The present invention aims to provide an inkjet recording head that can accurately absorb internal pressure fluctuations in a common ink chamber of a print head and eject stable ink droplets.

Structure of the invention In the present invention, a rubber plate forming at least a part of a common ink chamber of a print head (inkjet recording head) is attached to a print head substrate. A common opening provided in the chamber is closed with a removable rubber plate, a portion of the rubber plate covering the opening is formed into a thin film shape for absorbing ink pressure fluctuations in the common ink chamber, and a peripheral edge of the rubber plate is formed. This is achieved by an inkjet recording head characterized in that the common ink chamber is formed in a thick shape so that the common ink chamber can be sealed tightly by closely fixing the inkjet recording head to the recording head base at the periphery of the opening.

Embodiment FIG. 3 is an exploded perspective view schematically showing an example of the configuration of a printing head according to the present invention.

20 is a print head substrate, and 21 is a print head side plate which has grooves for pressure chambers and a plurality of grooves for nozzles that eject ink at the tip 21a, formed on the side that contacts the head substrate 20. Piezoelectric transducer elements 21b corresponding to the number of channels (the number of nozzles) are provided on the side surface of the head side plate 21 (the front side in the figure) on the side surface of the pressure chamber for each nozzle, and an opening 21c for a common ink chamber is provided. . The head substrate 20 and the head side plate 21 are closely joined as shown in the figure to form the head main body.

22 is an elastic rubber plate that covers the opening 21c of the head side plate 21, and contains butadiene, isoprene,
It may be integrally molded of butyl, silicone, fluorine rubber, etc., or may be formed by laminating urethane, acrylic rubber, etc. to ink-resistant rubber. The flexible surface 22a of the rubber plate 22 has a shape corresponding to the opening 21a of the print head 21,
In this example, it is formed with a slight bulge toward the front, and has elasticity that can appropriately absorb changes in pressure corresponding to changes in volume of the pressure chamber in order to fulfill the function of the flexible membrane described above. Further, the peripheral edge of the rubber plate 22 has sufficient thickness and elasticity to withstand strong tension when attached to the print head substrate 21 and maintain airtightness.

23 is a pressure bonding plate for attaching and fixing the peripheral portion of the rubber plate 22 to the printing head side plate 21 and the head substrate 20 with uniform pressure, and is provided with a hole 23a corresponding to the flexible surface 22a of the rubber plate 22; It is made from thin sheets of stainless steel, Kovar, aluminum, etc.

If these members are fastened together with a plurality of bolts 24 and nuts 25, the rubber plate 2
The flexible surface 22a of No. 2 functions as a flexible membrane that absorbs pressure fluctuations in the common ink chamber of the print head substrate 21, and since the material used therefor is elastic rubber, it is difficult to break and is not made of conventional rubber. Since there is no need for pre-processing or bonding work required when using a flexible membrane, installation and removal are extremely easy, and the assembly of the print head and the replacement of the flexible membrane are extremely efficient. becomes.

Note that even if the print head has a multilayer structure, or if the same print head substrate has head side plates on both sides and two common ink chambers are provided, a plurality of common ink chambers may be formed. The present invention can also be applied to other print heads.

Effects of the invention The present invention uses a rubber plate to attach a flexible membrane that has excellent performance and durability to absorb pressure fluctuations in the common ink chamber, and can be attached and detached using a fastening member. An inkjet that has the effect of absorbing ink pressure fluctuations due to elastic expansion and contraction, and has a flexible membrane that prevents ink leakage and is easy to replace.In other words, it is hard to break, does not tangle ink, is easy to replace, and has good workability and requires less man-hours. This made it possible to provide print heads for recording devices.

[Brief explanation of the drawing]

1 and 2 are a sectional view and a plan view, respectively, showing a schematic diagram of a print head, and FIG. 3 is a perspective view of the print head according to the present invention. 21...print head board, 21a...nozzle,
21b...piezoelectric conversion element, 21c...opening, 2
2...Rubber plate, 22a...Flexible surface (rubber plate), 2
3...Crimp plate, 23a...hole, 24...bolt,
25...Natsuto.

Claims (1)

[Claims for Utility Model Registration] (1) A common opening provided in a common ink chamber that supplies ink to each ink flow path of a plurality of nozzles is closed with a removable rubber plate, and A portion covering the opening is formed in the form of a thin film for absorbing ink pressure fluctuations within the common ink chamber, and a peripheral portion of the rubber plate is closely fixed to a recording head substrate around the opening, thereby making it possible to seal the common ink chamber. An inkjet recording head characterized in that it is formed in a thick wall shape. (2) The inkjet according to claim 1, wherein the peripheral edge of the rubber plate can be screwed and fixed to the peripheral edge of the opening of the recording head substrate together with the rigid pressure bonding plate. Record head.