JP3125478U - Inkjet head cap device - Google Patents

Abstract

An ink ejection surface can be reliably sealed even with a small pressure contact force.
A cap device for an ink jet head according to the present invention is a cap 3 that detachably contacts the periphery of an ink discharge surface of an ink jet head 1 and covers the ink discharge surface in an airtight manner, and has a cap opened. A non-permeable film-like member 4 having elasticity and flexibility is provided on the upper surface side, and the cap 3 is pressed against the head 1 via an ink layer ejected onto the upper surface of the film-like member 4 during pressure purge, Ink is sucked from the nozzle by the negative pressure generated in the nozzle, and the film-like member 4 is sucked and adhered to the ejection surface side of the head 1 to seal the nozzle.
[Selection] Figure 2

Description

  The present invention relates to a cap device for covering an ink discharge surface side of an ink jet head, and more particularly to a device having improved sealing performance against the discharge surface.

  Some ink jet printers have a structure in which an ink ejection surface side where nozzles of an ink jet head are opened is protected by a cap. In this structure, when the ink is ejected, the cap is moved to the standby position, and when the ink is not ejected, the lower part of the head where the nozzle is opened is covered with the cap, so that the area around the nozzle of the head is sealed with the cap and the ink is dried. And nozzle clogging due to drying.

  5A and 5B are diagrams showing a conventional ink jet head provided with a cap. FIG. 5A is a front view, and FIG. 5B is a cross-sectional view taken along the line BB in FIG. In the figure, the lower surface of the head 1 having an ink chamber inside is an ink ejection surface in which a plurality of ink ejection ports (nozzles) are opened. The periphery of the ink discharge surface is surrounded by a rectangular frame-shaped protective plate 2, and a cap 3 having a concave cross section made of an elastic resin such as rubber is pressed against the lower surface of the protective plate 2 so as to be detachable. As a result, the ink discharge surface is sealed to prevent the ink from drying and adhering to the nozzle.

  However, in the conventional cap 3, due to the dimensional accuracy of the members and the cap 3 falling down due to the pressure contact pressure indicated by the arrow at the time of capping, it is actually impossible to ensure a sufficient sealing property. There was a problem that clogging was likely to occur.

  Furthermore, in a line-type ink jet printer in which a large number of heads are arranged, a large force is required for capping on a plurality of heads at the same time, and the strength of the holding member of the cap 3 and the rigidity of the mechanism for separating and attaching are increased. It becomes necessary to take large. For this reason, the apparatus became large and expensive.

  SUMMARY OF THE INVENTION The present invention solves the above-described problems, and it is possible to reliably seal an ink discharge surface of a head even with a small pressure contact force. The object is to provide a cap device.

The cap device for an ink jet head according to claim 1, wherein the ink discharge surface of the ink jet head in which the nozzle is open is hermetically covered with a detachable cap.
A flexible seal that seals the nozzle in close contact with the ink ejection surface by the negative pressure generated in the nozzle when the inkjet head does not eject ink on the upper surface side of the cap facing the ink ejection surface. A stop member is provided.

An ink-jet head cap device according to claim 2, wherein the ink-jet head cap device according to claim 1,
A concave portion is formed on the upper surface of the cap, and a film-like member as the sealing member is provided to cover the concave portion,
The film-like member seals the nozzle by elastically deforming following the shape of the lower surface of the inkjet head including the ink ejection surface by the negative pressure generated in the nozzle when the inkjet head does not eject ink. It is characterized by stopping.

An ink jet head cap device according to claim 3, wherein the ink discharge surface of the ink jet head in which the nozzle is open is hermetically covered with a detachable cap.
A flexible seal that seals the nozzle in close contact with the ink ejection surface by the negative pressure generated in the nozzle when the inkjet head does not eject ink on the upper surface side of the cap facing the ink ejection surface. A stop member is provided,
In a state where the ink ejected from the nozzle onto the sealing member in a state where the ink jet and the cap are separated, the sealing member is brought into contact with the ink ejection surface of the ink jet via the ink. The nozzle is sealed by the sealing member by being drawn into the nozzle by a negative pressure generated in the nozzle when the ink jet head does not eject ink.

  According to the present invention, a sealing member such as a film-like member is attached to the ink ejection surface of the head with an ink layer interposed therebetween, and the ink is sucked into the nozzle by the negative pressure of the head to seal the sealing member. Since the nozzle is sealed by adhering to the ink discharge surface, the evaporation of the ink can be reliably prevented. According to such a structure, the pressure contact force of the cap may be small, and the strength and rigidity of the cap holding member, the drive mechanism for moving the cap, and the like can be reduced, which is suitable for downsizing the entire apparatus. Furthermore, since the structure is such that a flexible sealing member such as a film-like member is deformed by following the shape of the lower surface of the head including the ink ejection surface, and the flatness of the ink ejection surface is improved. There is also an effect that it does not require high accuracy and can be made inexpensive.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
First, with reference to FIGS. 3 and 4, an image forming apparatus 100 provided with an inkjet head 1 as a printing unit that can obtain a useful result by applying the cap device of the present invention will be described.

  As shown in FIG. 3, the image forming apparatus 100 has upper and lower casings 101 and 102 as main bodies. The upper casing 101 includes a belt conveyance unit 103 that is a conveyance unit that conveys the printing paper P in the horizontal direction. The belt conveying unit 103 is provided with a suction fan 105 that is a holding unit for the printing paper P along the lower surface of the upper portion that contacts the printing paper P on the moving endless belt 104. When the endless belt 104 includes a plurality of holes or a plurality of endless belts provided in parallel to each other, the suction fan 105 sucks the printing paper P through these gaps, thereby the endless belt 104. By holding the printing paper P on the belt 104 and moving the endless belt 104, the printing paper P can be conveyed without misalignment. Further, a paper feeding means 106 is provided on the entrance side of the belt conveying means 103, and the stacked printing paper P can be fed into the belt conveying means 103 one by one from the top. Further, printing means comprising four inkjet heads 1 arranged downward at an appropriate interval is provided above the upper portion of the endless belt 104 that contacts the printing paper P. The ink colors of each inkjet head 1 are black, cyan, magenta, and yellow along the conveyance direction of the printing paper P. In addition, a paper discharge unit 107 is provided on the exit side of the belt conveyance unit 103, and the printed printing paper P can be discharged onto a paper discharge table.

  As shown in FIG. 4, the roller of the belt conveying means 103 is provided with a rotary encoder 108 as a conveying position detecting means, and the control means 110 that receives the pulse signal S1 sends a timing signal S2 to each inkjet head 1 of the printing means. And the ink of each color can be ejected onto the printing paper P held and conveyed by the endless belt 104 by the belt conveying means 103 at an appropriate timing.

  The control means 110 performs color separation on the image to be formed and obtains drive data for each color inkjet head 1, and then the belt conveyance means 103 conveys the signal S 1 from the rotary encoder 108 as a reference. By driving each inkjet head 1 corresponding to the position of the printing paper P, the ink of each color is aligned and discharged at an appropriate position on the printing paper P, thereby printing a color image as the original image. It can be reproduced and formed on the paper P.

  In FIG. 3, a paper transport path 111 for double-sided printing is disposed inside the upper casing 101 so as to cover the upper side of the printing unit. The paper conveyance path 111 is a conveyance path that connects the outlet side and the inlet side of the belt conveyance means 103, and a conveyance roller and a conveyance belt are arranged along the path so that the printing paper P can be conveyed. In the paper transport path 111, a switching unit 112 is provided in the vicinity of the exit side of the belt transport unit 103, and a switchback type paper reversing unit 114 is provided in the vicinity of the entrance side via another switching unit 113. ing.

  Therefore, when the printing paper P is printed on both sides, the printing paper P is printed on the surface while being conveyed by the belt conveyance means 103, and then is guided to the paper conveyance path 111 via the switching unit 112, and another switching unit. 113 is guided to the sheet reversing unit 114, and the other switching unit 113 is switched again and then introduced into the sheet conveying path 111 to return to the entrance of the belt conveying unit 103. Finally, the back surface is printed while being conveyed by the belt conveying unit 103. The paper can be discharged to the paper discharge means 107.

  In FIG. 3, second and third sheet feeding units 106 ′ and 106 ″ are provided inside the lower casing 102, and the belt conveying unit 103 is different from the first sheet feeding unit 106. The size of the printing paper P ′, P ″ can be supplied. Reference numeral 110 denotes the control means.

  Next, a specific configuration around the inkjet head, which is a main part of the embodiment of the present invention, will be described with reference to FIGS. 1 and 2. Note that parts that are substantially the same as those in the past are denoted by the same reference numerals as those in the prior art, and members newly added in the present example are denoted by different numerals. FIG. 1A is a front view, and FIG. 1B is a cross-sectional view taken along the line AA in FIG.

  The rectangular parallelepiped cap 3 is formed by opening a recess having a rectangular cross section on the upper surface side thereof. A film-like member 4 serving as a sealing member having elasticity and flexibility is disposed so as to cover both side surfaces of the cap 3 and the openings of the recesses on the upper surface. The material of the fill member 4 is non-permeable so that it does not transmit ink and does not transmit air at the negative pressure generated in the nozzle. The upper surface of the film-like member 4 is in close contact with the head surface protection plate 2 and the ink discharge surface of the head 1 inside the ink layer 5 shown by a black portion in the drawing, and the ink is dried by this adhesion. Protect.

  FIGS. 2A to 2C show a procedure until the above-described nozzle sealing action is obtained. First, as shown in FIG. 2A, the cap 3 is periodically attached to the lower surface of the head 1. In this state, the ink is ejected downward by pressure purge, and the ejected ink is retained on the upper surface of the film-like member 4.

  As shown in FIG. 2B, the cap 3 is raised again while the ink is still in a dry state, and the film-like member 4 comes into contact with the lower surface of the protective plate 2 through the ink layer. Here, in the non-ejection state, the nozzle of the head 1 is kept at a negative pressure due to a water head difference from the supply ink tank.

  As shown in FIG. 2C, the ink is drawn into the nozzle by the suction effect due to the negative pressure, and at the same time, the film-like member 4 moves to the ink ejection surface side. The ink is drawn into the nozzle until the ink between the ink discharge surface and the film-like member 4 runs out. Finally, the film-like member 4 is elastically deformed, and not only the lower surface of the protective plate 2 but also the inner peripheral surface and the head ink. Suction contact with the discharge surface. That is, since the film-like member 4 is made of a flexible elastic material, it deforms following the surface shape of the lower surface of the head and its peripheral portion by the negative pressure generated in the nozzle, and adheres closely to these surfaces without a gap. As a result, it is possible to reliably seal the nozzle and its periphery and prevent ink drying around the nozzle.

  The nozzle sealing procedure described above with reference to FIGS. 2A to 2C is executed by a control unit that controls the entire apparatus in an image forming apparatus including the head 1 as a printing unit. be able to.

  Compared to the conventional case in which a cap having a concave portion is fitted to the ink discharge surface to prevent ink drying at the nozzle as described above, there is no air near the nozzle at the time of non-printing (ink non-discharge state). High anti-drying effect. In addition, since the sealed state is maintained only by the deformation of the film-like member 4 due to the negative pressure, the accuracy of the flatness of the contact surface of the cap 3 and the pressure contact force are not affected. For this reason, the drive mechanism does not require great strength and rigidity, and the entire apparatus can be reduced in size.

(A) is a front view of the inkjet head which attached the cap apparatus of this example, (b) is the sectional view on the AA line of (a). (A), (b), (c) is sectional drawing for effect | action description. 1 is a schematic configuration diagram of an image forming apparatus to which this example can be applied. FIG. 2 is a schematic enlarged perspective view of the vicinity of a printing unit of the image forming apparatus. (A) is a front view of the inkjet head which attached the conventional cap, (b) is sectional drawing in the AA cut line of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet head 2 Head surface protection plate 3 Cap 4 Film-like member as a sealing member

Claims (3)

In a cap device that covers an ink discharge surface of an ink jet head having an open nozzle airtightly with a removable cap,
A flexible seal that seals the nozzle in close contact with the ink ejection surface by the negative pressure generated in the nozzle when the inkjet head does not eject ink on the upper surface side of the cap facing the ink ejection surface. An ink-jet head cap device comprising a stop member. A concave portion is formed on the upper surface of the cap, and a film-like member as the sealing member is provided to cover the concave portion,
The film-like member seals the nozzle by elastically deforming following the shape of the lower surface of the inkjet head including the ink ejection surface by the negative pressure generated in the nozzle when the inkjet head does not eject ink. 2. The cap device for an ink jet head according to claim 1, wherein the cap device is stopped. In a cap device that covers an ink discharge surface of an ink jet head having an open nozzle airtightly with a removable cap,
A flexible seal that seals the nozzle in close contact with the ink ejection surface by the negative pressure generated in the nozzle when the inkjet head does not eject ink on the upper surface side of the cap facing the ink ejection surface. A stop member is provided,
In the state where the ink ejected from the nozzle onto the sealing member in a state where the inkjet and the cap are separated, the sealing member is brought into contact with the ink ejection surface of the inkjet via the ink. The inkjet head is configured such that the nozzle is sealed by the sealing member by being drawn into the nozzle by a negative pressure generated in the nozzle when the inkjet head does not eject ink. Cap device.

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