JP2009298076A - Head covering device of inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the head covering device of an inkjet printer, which can prevent a printing quality from lowering by preventing dusts from adhering to the nozzle arranging plane of a print head. <P>SOLUTION: The head covering device 1 is used on the inkjet printer equipped with the print head arranged with nozzles 9 for jetting ink droplets against the surface DA of a relatively moving material to be printed D. The head covering device 1 is equipped with a covering body 4 for hermetically covering the front of the nozzle arranging plane 5A of the print head 5 and a gas pump 14 for sending gas in the space K ahead the nozzle arranging plate 5A covered with the covering body 4 and, in addition, an ink passing hole 20 for passing ink droplets jetted from the nozzles 9 therethrough is formed in the covering body 4 and is so constituted as to keep the interior of the space K ahead the nozzle arranging plane 5A at positive pressure by sending the gas therein by driving the gas pump 14. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a head cover device that covers a print head of an inkjet printer that prints by ejecting ink droplets onto the surface of a relatively moving substrate.

  Conventionally, as this type of inkjet printer, for example, the one described in Patent Document 1 below is known. In such an ink jet printer described in the literature, a print head is disposed at a side position of a conveyor that conveys an object to be printed, and a plurality of nozzles are arranged side by side on the front surface of the print head. In this inkjet printer, dot printing is performed by ejecting ink droplets from nozzles onto the surface of a substrate to be conveyed.

JP 2002-86807 A

  By the way, in a field where a cardboard box is handled as a substrate to be printed, a large amount of dust, mainly paper dust generated from the cardboard box, is scattered. Further, ink dripping from the nozzles often remains on the nozzle arrangement surface of the print head of the ink jet printer, and dust such as paper dust tends to adhere to the remaining ink and harden. Such a solidified product of ink and dust may grow to a position in front of the nozzle, obstructing the flight of the ink or blocking the nozzle itself. When ink ejection is obstructed in this way, the print quality is degraded and accurate printing cannot be performed. For example, when printing a QR code, a missing dot occurs in a part of the printing, which causes a serious problem that it cannot be read as a target QR code.

  The present invention has been made in view of the above-described conventional problems, and is a head cover for an ink jet printer that can prevent deterioration in print quality by preventing dust from adhering to the nozzle arrangement surface of the print head. The purpose is to provide a device.

  In order to achieve the above object, a head cover device for an ink jet printer according to the present invention includes a print head nozzle arrangement of an ink jet printer including a print head in which nozzles for ejecting ink droplets are arranged on the surface of a relatively moving substrate. An ink passage that includes a cover body that covers the front of the surface in a sealed manner and a gas pump that sends gas into the front space of the nozzle arrangement surface that is covered by the cover body, and allows ink droplets ejected from the nozzle to pass therethrough. A hole is formed in the cover body, and gas is fed by driving the gas pump so as to hold the inside of the front space of the nozzle arrangement surface at a positive pressure.

  Further, in the above configuration, the cover body is formed in a box shape that accommodates the entire print head.

  In each configuration described above, the opening edge of the ink passage hole on the downstream side in the printing material movement direction is arranged at a position farther from the printing material than the opening edge on the upstream side of the printing material movement direction.

  Furthermore, in each of the above-described configurations, the cover body includes a peripheral frame member that is disposed so as to surround the nozzles of the print head, and a lid member that is provided on the peripheral frame member and covers the front of the nozzle so as to be openable / closable. It consists of.

  According to the head cover device of the ink jet printer according to the present invention, the gas is fed into the cover body covering the front side of the nozzle arrangement surface of the print head in a sealed manner, and the front space of the nozzle arrangement surface is maintained at a positive pressure. Therefore, the gas in the front space flows out of the cover body from the ink passage hole. Accordingly, external dust or the like does not flow into the front space from the ink passage hole. Thereby, the adhesion of dust to the nozzle arrangement surface can be prevented. As a result, it is possible to prevent a decrease in print quality of the ink jet printer.

  In addition, when the cover body is formed in a box shape that accommodates the entire print head, dust can be prevented from adhering not only to the nozzle placement surface but also to the entire print head, and the entire print head is mechanically protected. be able to.

  In the case where the opening edge of the ink passage hole on the downstream side in the movement direction of the printed material is arranged at a position farther from the printed material than the opening edge on the upstream side in the movement direction of the printed material, the printed material contacts the cover body. However, it does not contact the opening edge of the ink passage hole on the downstream side in the moving direction of the substrate. Therefore, it is possible to prevent paper dust generated from the printing material and dust attached to the printing material from entering the ink passage hole.

  Further, when the cover body includes the peripheral frame member and the lid member, the front of the nozzle can be opened by moving the lid member covering the front of the nozzle. As a result, the print head can be maintained.

The best embodiment of the present invention will be described with reference to the drawings. The embodiment described below is merely an example embodying the present invention, and does not limit the technical scope of the present invention. FIG. 1 is an external view of an ink jet printer including a head cover device according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram including a partial cross section of the ink jet printer.
In each figure, the ink jet printer according to this embodiment includes a print head 5 in which a large number of nozzles 9, 9, 9,... Are arranged in a column on the nozzle arrangement surface 5A. The print head 5 sprays ink droplets J (see FIG. 7) onto a printing surface (example of surface) DA of a cardboard box (example of material to be printed) D that is placed on the conveyor C and moves in the direction of arrow E. It is like that. The ink jet printer further includes a drive unit 6 connected to the print head 5 and a head cover device 1 that accommodates the print head 5 and the drive unit 6 as a whole. The drive unit 6 is equipped with a piezoelectric element that is an ink ejection drive source. The number of nozzles 9 provided on the nozzle arrangement surface 5A of the print head 5 depends on the required print font size, and is, for example, about 32 to 500. The print head 5 is arranged so that the ink ejection direction (the direction of arrow F in FIG. 2) is directed in a direction (arrow E direction) substantially perpendicular to the conveyance direction (arrow E direction) of the conveyor C.

  The head cover device 1 accommodates the print head 5 and the drive unit 6 and covers the cover body 4 in a hermetically sealed manner, and air (gas gas) in the space K in front of the nozzle arrangement surface 5A of the print head 5 covered with the cover body 4. Example) is provided with a gas pump 14 for feeding in. The cover body 4 includes a casing portion 2 formed in a rectangular box shape having a front opening, and a front cover portion 3 sealed to the front opening of the casing portion 2.

As shown in FIGS. 3 to 6, the front cover 3 is attached to the peripheral frame member 17 and the peripheral frame member 17 arranged so as to surround the periphery of the nozzles 9 of the print head 5. And a lid member 19 that covers the front of the door so as to be opened and closed. A support member 18 that supports the lid member 19 from the back surface is interposed between the peripheral frame member 17 and the lid member 19.
The peripheral frame member 17 includes a base portion 40 that has a head mounting opening 38 and is formed in a rectangular frame shape. A plurality of female screw holes 39 are formed around the head mounting opening 38 in the base portion 40. Further, on the left and right side portions of the base portion 40, ridge portions 36 and 37 projecting outward in the left and right directions are formed. A fixing plate member 16 extending to the back is attached to the back surface of the peripheral frame member 17.

  The lid member 19 is exemplified as a stainless steel plate formed in a rectangular shape in front view. However, the material and shape of the lid member 19 are not particularly limited. In the lid member 19, an ink passage hole 20 through which the ink droplet J ejected from the nozzle 9 passes is formed in a vertically long slit shape. The front surface of the lid member 19 has an upstream surface 21 on the upstream side in the cardboard box moving direction (arrow E direction) and a downstream surface on the downstream side in the cardboard box moving direction, with a stepped portion 29 extending vertically through the ink passage hole 20. 22 and divided. The upstream surface 21 is a surface protruding forward (arrow F direction) from the downstream surface 22. As a result, the opening edge 24 on the downstream side in the cardboard box movement direction in the ink passage hole 20 is arranged at a position farther from the passing position of the cardboard box D than the opening edge 23 on the upstream side in the movement direction. A corner portion on the most upstream side in the cardboard box moving direction on the front surface of the lid member 19 is an inclined surface portion 27 cut out in a tapered shape. Further, both side portions of the lid member 19 are bent portions 25 and 26 which are bent inward from the rear. A locking protrusion 30 that protrudes further inward is formed at the upper end of the bent portion 25, and a locking protrusion 31 that protrudes inward is also formed at the upper end of the bent portion 26. The lateral width of the lid member 19 (FIG. 5, etc.) shown in this embodiment is, for example, 55 mm. However, the width of the lid member according to the present invention is not limited to the dimension of 55 mm.

  The support member 18 is also formed in a rectangular frame shape having a head mounting opening 34, and a plurality of screw holes 35 are provided around the head mounting opening 34. The front surface of the support member 18 is an upstream surface 32 that supports the back portion of the upstream surface 21 of the lid member 19, and a downstream surface 33 that is in a retracted position from the upstream surface 32 and supports the back portion of the downstream surface 22 of the lid member 19. It is divided into and. The material and shape of the peripheral frame member 17 and the support member 18 are not particularly limited, but here, for example, a molded body made of polyacetal copolymer is exemplified.

  In assembling the front cover 3, the support member 18 is mounted on the mounting surface 41 on the front surface of the peripheral frame member 17, and screws 42, 42, 42,... Passed through screw holes 35, 35, 35,. The support member 18 is fixed to the peripheral frame member 17 by screwing (see FIG. 8) into the female screw holes 39, 39, 39,. Then, the fixing plate member 16 of the peripheral frame member 17 is inserted along the inner surface of the casing part 2, and the support member 18 and the peripheral frame member 17 are arranged in a state of sealing the front opening of the casing part 2. . Then, the fixing plate member 16 is screwed to the casing portion 2, and the peripheral frame member 17 is fixed to the casing portion 2. At this time, the print head 5 is located in the head mounting openings 34 and 38 of the peripheral frame member 17 and the support member 18. Subsequently, the lid member 19 is manually disposed above the peripheral frame member 17, the bent portions 25 and 26 of the lid member 19 are applied to the back surfaces of the protrusions 36 and 37 of the peripheral frame member 17, and the lid member 19 is directed downward. Slide to. Among them, the locking projections 30 and 31 come into contact with the upper ends of the ridges 36 and 37, and the lid member 19 is locked. As a result, the front surfaces of the peripheral frame member 17 and the support member 18 are covered with the lid member 19. At this time, the nozzles 9, 9, 9,. Further, a space (an example of a front space) K is formed in front of the nozzle arrangement surface 5A of the print head 5, that is, between the back surface of the lid member 19 and the nozzle arrangement surface 5A.

  And the casing part 2 of the head cover apparatus 1 is being fixed to the support | pillar 11 via the support rods 28 and 28. FIG. The casing portion 2 is connected to a wiring tube 10 that houses a power line and a signal line. Moreover, the piping 8 for air is connected to the casing part 2 via the flexible joint 7, for example. The air pipe 8 is provided with a flow meter 12, a flow rate adjustment valve 13, a gas pump 14, and a filter 15.

  In the head cover device 1 of the ink jet printer configured as described above, air is sucked from the filter 15 and filtered by driving the gas pump 14. The filtered air is depressurized by the flow rate adjusting valve 13 to be adjusted to a predetermined flow rate, and is sent into the cover body 4 from the flexible joint 7. The air volume detected by the flow meter 12 is about 50 L / min and is a positive pressure. Then, as shown in FIG. 7, the air in the cover body 4 passes through the side of the drive unit 6 and wraps around the front of the print head 5, passes through the ink passage hole 20 through the space K, and covers the cover. It flows out to the front of the body 4. Thereby, dust M such as paper dust floating around the ink jet printer cannot enter the cover body 4 from the ink passage hole 20. Accordingly, the dust M does not reach the space K in front of the nozzle arrangement surface 5A, and naturally the dust M does not adhere to the nozzle arrangement surface 5A. As a result, since the ejection of the ink droplet J from the nozzle 9 is not disturbed by the dust M, this ink jet printer can maintain high print quality.

  On the other hand, during printing, the cardboard box D placed on the conveyor C moves and passes in front of the print head 5. In this case, the distance between the printing surface DA of the moving cardboard box D and the nozzle 9 of the print head 5 is set to a relatively short distance of, for example, 5 mm or less in consideration of preferable print quality. Then, ink droplets J are ejected from the nozzles 9, 9, 9,... To the target printing position of the printing surface DA of the cardboard box D, and characters and figures (for example, QR codes) of a predetermined font are printed. . In this case, the speed of the ink droplet J is, for example, 10 m / sec at the initial speed. In this case, the flow velocity of the air flowing out from the ink passage hole 20 is adjusted by operating the flow rate adjusting valve 13 while checking the print quality printed on the cardboard box D. That is, the flow rate of the air ejected from the ink passage hole 20 may be a speed that does not affect the ink flight direction, that is, does not impair the print quality.

  And since the nozzle arrangement | positioning surface 5A is covered with the cover member 19 of the cover body 4, it cannot be overemphasized that contact | abutting of the cardboard box D to 5A of nozzle arrangement | positioning surfaces can be prevented. Further, since the opening edge 24 of the ink passage hole 20 is disposed at a rear position farther from the cardboard box D than the opening edge 23 on the upstream side in the cardboard box moving direction, even if the cardboard box D is the upstream surface 21 of the lid member 19. The cardboard box D does not come into contact with the opening edge 24 of the ink passage hole 20 even if it is in sliding contact with the ink passing hole 20. Accordingly, it is possible to avoid a situation in which paper dust or the like enters the space K from the ink passage hole 20 due to the contact of the cardboard box D. Furthermore, since the corner portion on the most upstream side in the cardboard box moving direction on the front surface of the lid member 19 is an inclined surface portion 27 cut out in a taper shape, even when the cardboard box D collides with the lid member 19, the cardboard box D It is hard to be damaged.

  The lid member 19 has its bent portions 25 and 26 mounted on the protrusions 36 and 37 of the peripheral frame member 17 so as to be slidable up and down, so that the front of the nozzle arrangement surface 5A can be opened and closed, as shown in FIG. As described above, the front of the nozzle arrangement surface 5A can be opened by sliding the lid member 19 upward. This is convenient because the print head 5 can be easily maintained. 8 shows the appearance when the ink jet printer and the head cover device 1 are used for one month, and countless dusts M, M, M,... Adhere to each surface. On the other hand, the dust M did not adhere to the nozzle arrangement surface 5A of the print head 5 covered with the lid member 19, and the dust M also adhered to the front surface of the lid member 19 near the ink passage hole 20 very little. In addition, the print quality was not deteriorated.

In the above embodiment, an example in which the head cover device is applied to an ink jet printer other than the piezo element driving type has been described. However, the head cover device of the present invention is not limited thereto, and the ink jet printer other than the piezo element driving type is used. It is applicable to.
In the above, an example in which the print head of the ink jet printer is fixedly arranged and the substrate is moved is shown. However, the printhead is fixedly arranged and the printhead is moved, and both the printhead and the substrate are moved. Needless to say, it can also be applied to moving objects.
The ink passage hole 20 is not limited to the shape of the above-described vertically long slit, and may be formed in a shape and size that do not hinder the ejection of ink droplets from the nozzle according to the number and arrangement of the nozzles. .

In addition, the cover body 4 is configured in a box shape that accommodates the entire print head 5 and the drive unit 6. Is also possible.
In addition, as an aspect of opening and closing the lid member with respect to the peripheral frame member, a slide type in which the bent portions 25 and 26 slide on the ridge portions 36 and 37 is exemplified above, but a hinge is used instead. A lid swinging type or a lid attaching / detaching type may be used.
The gas fed into the cover body is not particularly limited as long as it does not damage the work environment or the apparatus. In addition to the above-mentioned air, for example, nitrogen can be used.

1 is an external view of an inkjet printer including a head cover device according to an embodiment of the present invention. It is a schematic block diagram including the partial cross section of the said inkjet printer. It is a front exploded view of the front cover part of the head cover device. It is a plane exploded view of the front cover part of the head cover device. It is a rear view of the lid member of the front cover part. It is a top view of the said front cover part. It is operation | movement explanatory drawing of the said inkjet printer. It is an external view which shows the state which opened the cover member of the said head cover apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Head cover apparatus 2 Casing part 3 Front cover part 4 Cover body 5 Print head 5A Nozzle arrangement surface 9 Nozzle 14 Air pump 17 Peripheral frame member 19 Lid member 20 Ink passage hole 23 Open edge 24 Open edge D Cardboard box (printed material)
DA Print surface (front)
E Arrow J Ink drop K Space (front space)

Claims (4)

A cover body that covers the front of the nozzle arrangement surface of the print head in a sealed manner in an inkjet printer including a print head in which nozzles that eject ink droplets are arranged on the surface of the substrate to be moved relative to each other, and the cover body. A gas pump that sends gas into the front space of the nozzle arrangement surface, and an ink passage hole that allows ink droplets ejected from the nozzle to pass through is formed in the cover body, and the nozzle is arranged by sending gas by driving the gas pump. A head cover device for an ink jet printer, characterized in that the inside of the front space of the surface is held at a positive pressure. The head cover device for an ink jet printer according to claim 1, wherein the cover body is formed in a box shape that accommodates the entire print head. 3. The head cover of an ink jet printer according to claim 1, wherein an opening edge on the downstream side in the direction of movement of the substrate in the ink passage hole is disposed at a position farther from the substrate than the opening edge on the upstream side in the direction of movement of the substrate. apparatus. The cover body includes a peripheral frame member provided to surround the nozzles of the print head, and a cover member that is provided on the peripheral frame member and covers the front of the nozzle so as to be openable and closable. The head cover apparatus of the inkjet printer as described in any one of these.

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