JP5692505B2 - Liquid ejector - Google Patents

Description

  The present invention relates to a liquid ejecting apparatus that ejects liquid onto, for example, a paper recording medium.

  As an example of a liquid ejecting apparatus that ejects liquid onto a recording medium, an ink jet printer that ejects ink that is liquid onto recording paper serving as a recording medium is known. The ink jet printer includes a liquid ejecting head having a nozzle forming surface on which a plurality of nozzles are formed, and a support member that supports the recording paper in a state of facing the nozzle forming surface of the liquid ejecting head. Then, while the liquid ejecting head and the recording paper are relatively moved, the ink droplets are ejected from the nozzles of the liquid ejecting head toward the recording paper located at the facing position facing the nozzle forming surface, so that the recording paper Characters and figures are recorded in

  By the way, when the recording medium is a paper recording paper, paper dust, which is a kind of dust, is scattered from the recording paper due to vibration of the recording paper during conveyance, contact between the recording paper and another member, or the like. In particular, paper powder tends to scatter due to the behavior of the recording paper as described above from the cut surface of the recording paper in which the paper fibers are forcibly cut. For this reason, if the end of the recording sheet conveyed toward the support member on the downstream side in the conveyance direction collides with a rib provided on the support member, a large amount of paper dust is scattered from the cut surface at the tip. . As a result of the scattered paper dust floating around the recording paper and a part of the paper dust adhering to the vicinity of the nozzle, the flying direction of the ink droplets ejected from the nozzle changes or the nozzle is blocked by the paper dust. Nozzle clogging may occur.

  Therefore, in Patent Document 1, in order to prevent the scattered paper dust from adhering to the nozzles, air is directed toward the oblique forward direction of the carriage with respect to the recording paper by a fan provided in the carriage that moves the liquid ejecting head. The proposal of spraying is made. According to the apparatus described in Patent Document 1, since the carriage moves toward a region where air is blown, that is, a region where scattered paper dust is blown off by air, the paper dust scattered from the recording paper is reduced. Adhesion to the nozzle forming surface is suppressed.

Japanese Patent Laid-Open No. 2003-118095

  By the way, when the recording paper is supported by the support member and conveyed, the recording paper and the support member are charged by friction between the recording paper and the support member. Usually, the nozzle forming surface of the recording head is composed of a metal nozzle plate, and the nozzle plate is grounded. Therefore, the nozzle is caused by a potential difference between the grounded nozzle plate and the charged support member. An electric field is generated between the plate and the support member. For this reason, when the support member is negatively charged, for example, an electric field generated between the support member and the nozzle plate induces paper powder having the same polarity as that of the support member to be adsorbed to the nozzle plate. Electrostatic adsorption occurs. Even if the paper dust scattered from the recording paper is blown once through the above-described air blowing, it is difficult to determine the position of the blown paper dust by the air flow, and the above-described electric field is generated between the support member and the nozzle plate. As described above, a part of the blown paper dust is not a little, but is induced by the electric field and adheres to the nozzle plate. That is, even if paper dust adhesion to the vicinity of the nozzles is suppressed by blowing air, as long as paper dust adheres due to the electric field described above, there is still room for improvement in suppressing printing defects on recording paper. It has become.

  The present invention has been made in view of such circumstances, and an object thereof is to suppress adhesion of such dust to the liquid ejecting head when dust may be generated from the recording medium. An object of the present invention is to provide a liquid ejecting apparatus that can

In order to achieve the above object, a liquid ejecting apparatus according to the present invention includes a support member having a support surface for supporting a recording medium, and a liquid disposed with respect to the surface of the recording medium. A conductive member is provided in a part of the area where the recording medium is supported , and the conductive member is grounded.

  According to the present invention, when the conductive member is grounded, the support surface is charged by friction generated between the recording medium conveyed on the support surface of the support member and the support surface, and the support surface thus charged is charged. And an electric field formed between the grounded conductive member. Then, even if the recording medium may generate dust, the dust scattered from the recording medium due to the contact between the recording medium and the support member during conveyance of the recording medium is between the support surface and the conductive member. And is electrostatically attracted to the conductive member. Therefore, the scattered dust is suppressed from being electrostatically attracted to the liquid ejecting head, and the adhesion of the dust to the liquid ejecting head can be suppressed.

  In the liquid ejecting apparatus according to the aspect of the invention, the support member includes a rib that has the support surface and protrudes toward the liquid ejecting head, and the conductive member is provided on a side surface of the rib.

According to the present invention, the distance between the supporting surface to be charged and the conductive member can be shortened as much as possible, and the scattered dust can be easily electrostatically adsorbed to the conductive member.
In the liquid ejecting apparatus according to the aspect of the invention, an edge portion on the support surface side of the conductive member is separated from the support surface.

According to this invention, for example, when the edge on the support surface side of the conductive member is located on the same plane as the support surface, the recording medium collides with the edge on the support surface side of the conductive member. The problem of dust scattering from the recording medium can be avoided.
In the liquid ejecting apparatus according to the aspect of the invention, the conductive member is provided on the upstream side of the end portion of the grounded member provided on the side where the liquid ejecting head faces the support member in the conveyance direction of the recording medium. .
In the liquid ejecting apparatus according to the aspect of the invention, the liquid ejecting head includes a grounded member that is grounded on a side facing the support member, and the distance between the support surface and the conductive member is the distance between the support surface and the supported member. It is shorter than the distance to the grounding member.

(A) is a schematic diagram which shows schematic structure of the inkjet printer in embodiment, (b) is a partial longitudinal cross-sectional view of a rib and a sheet metal. (A) Schematic diagram showing a state in which the front edge of the recording paper collides with the first rib and paper dust is scattered from the front edge of the recording paper, and (b) is an electrostatic adsorption of the scattered and negatively charged paper powder to the sheet metal. The schematic diagram which shows the state made. (A) is a top view of the 1st rib periphery in another embodiment, (b) is the sectional view on the AA line in FIG. 3 (a).

Hereinafter, an embodiment in which the present invention is embodied in an ink jet printer which is a kind of liquid ejecting apparatus will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1A, the ink jet printer includes a paper feed roller 10, a retard roller 11, a paper feed roller 12, and a paper discharge roller 13 for transporting a recording paper P as a recording medium. Each of these rollers 10, 11, 12, and 13 is formed in a columnar shape, and is disposed so as to be rotatable about its center as a rotation axis.

  The paper feed roller 10 is connected to the paper feed motor M1 and rotated through the drive of the paper feed motor M1 (in FIG. 1A, the power transmission path of the paper feed motor M1 is indicated by a broken line). The retard roller 11 disposed so as to face the paper feed roller 10 is driven to rotate in a state where a constant rotational load is applied by a torque limiting mechanism such as a torque limiter. Then, when the paper feed roller 10 is rotated by the paper feed motor M1, the recording paper P interposed between the paper feed roller 10 and the retard roller 11 is conveyed toward the paper feed roller 12.

  The paper feed roller 12 includes a transport drive roller 12a connected to the paper feed motor M2, and a transport driven roller 12b that is disposed so as to face the transport drive roller 12a and can be driven to rotate. The paper discharge roller 13 includes a paper discharge drive roller 13a connected to the paper feed motor M2 and a paper discharge driven roller 13b that is disposed so as to face the paper discharge drive roller 13a and can be driven to rotate ( In FIG. 1A, the power transmission path of the paper feed motor M2 is indicated by a broken line.

  In the paper feed roller 12 and the paper discharge roller 13, the transport drive roller 12 a and the paper discharge drive roller 13 a are driven to rotate by the paper feed motor M 2, so that the transport driven roller 12 b and the paper discharge driven roller 13 b cooperate with each other. Then, the recording paper P is fed and discharged. A direction in which the recording paper P is conveyed, that is, a direction from the paper feed roller 12 to the paper discharge roller 13 is hereinafter referred to as a conveyance direction.

  Also, above the recording paper P conveyed between the paper feed roller 12 and the paper discharge roller 13, a carriage 20 carrying an ink cartridge is provided so as to be movable in a direction perpendicular to the paper surface, that is, in the scanning direction. Yes. The carriage 20 is connected to the carriage motor M3 via a timing belt, and is reciprocated by driving the carriage motor M3 (in FIG. 1A, the power transmission path of the carriage motor M3 is indicated by a broken line). In addition, a recording head 21 as a liquid ejecting head is mounted on the carriage 20. On the lower surface of the recording head 21, there is provided a metal nozzle plate 22 having a number of nozzle holes (not shown) for ejecting ink droplets downward. The nozzle plate 22 is grounded so as to suppress its charging, and its lower surface functions as a nozzle forming surface.

  A support member 30 that supports the recording paper P is disposed below the recording paper P conveyed between the paper feed roller 12 and the paper discharge roller 13. The support member 30 is formed of an insulating resin material that is negatively charged by friction with the recording paper P being conveyed. The support member 30 includes a main body 30 a, a first rib 31, a second rib 32, and a third rib 33 that protrude from the main body 30 a toward the recording head 21 and are arranged side by side along the transport direction.

  As shown in FIG. 1B, the ribs 31, 32, and 33 are provided integrally with the main body 30a, and the upper surfaces of the ribs 31, 32, and 33 are formed into flat surfaces. The upper surface is a support surface 31a, 32a, 33a that supports the recording paper P in a state of facing the nozzle forming surface. In addition, as shown to Fig.1 (a), it is the area | region above the supporting member 30, Comprising: The edge part of the supporting member 30 in a conveyance direction back (upstream side), and the supporting member 30 in a conveyance direction front (downstream side) Hereinafter, a region sandwiched between the end portions is referred to as a printing region R.

  The main body 30 a is sandwiched between the first ribs 31 and the second ribs 32 and the second ribs 32 and the third ribs 33 at positions facing both ends in the conveying direction of the nozzle plate 22. A second recess 35 is formed. The first and second recesses 34 and 35 are provided with a first absorbent 36 and a second absorbent 37 that can absorb and retain ink. The first absorbent material 36 and the second absorbent material 37 are, for example, porous members such as polyethylene and polyurethane impregnated with a liquid. When borderless printing is performed in which ink is ejected to the outside of the recording paper P, the ink droplets discarded outside the recording paper P land on the first concave portion 34 or the second concave portion 35. The first absorbent 36 and the second absorbent 37 are collected.

  Sheet metal 40 as a conductive member is attached to both side surfaces along the conveying direction of each rib 31, 32, 33. Each sheet metal 40 is provided so as to overlap with each support surface 31a, 32a, 33a in the protruding direction of each rib 31, 32, 33. As shown in FIG. 1 (b), the side edges of the respective support surfaces 31a, 32a, 33a of the respective sheet metals 40 are separated from the respective support surfaces 31a, 32a, 33a, and the respective sheet metals 40 are grounded. .

  In the printer configured as described above, when the recording paper P is printed, first, when the paper feed motor M1 is driven, a plurality of recording papers P are sequentially transported along the transport path. Next, when the recording paper P reaches the printing region R while being supported by the support surface 31 a of the first rib 31, ink droplets are ejected from the nozzle holes of the recording head 21 and printing is performed on the recording paper P. .

  As shown in FIG. 2A, when the front end Pf, which is the end portion on the downstream side in the transport direction, which is the cut surface of the recording paper P, collides with the first rib 31 during transport of the recording paper P, the front end of the recording paper P Paper powder Pd, which is an example of dust, is scattered from Pf. Further, when the recording paper P is conveyed, friction is generated between the recording paper P and the support surface 31a of the first rib 31, and the support surface 31a of the first rib 31 is negatively charged by this friction. Further, the paper dust Pd generated from the recording paper P is also charged by collision or friction with the first rib 31. For this reason, the paper powder Pd scattered by the collision between the first rib 31 and the front end Pf of the recording paper P floats between the first rib 31 and the nozzle plate 22 in a charged state.

  Then, as shown in FIG. 2B, an electric field E1 is formed between the negatively charged support surface 31a of the first rib 31 and the grounded sheet metal 40 (in FIG. 2B, The direction of the electric field E1 is indicated by a thick line of electric force). In addition, an electric field E2 is formed between the negatively charged support surface 31a of the first rib 31 and the grounded nozzle plate 22 (in FIG. 2B, the direction of the electric field E2 is determined by a thin line of electric force). Show).

  Here, the distance between the support surface 31 a of the first rib 31 and the metal plate 40 is shorter than the distance between the support surface 31 a of the first rib 31 and the lower surface of the nozzle plate 22. Therefore, if the sheet metal 40 and the nozzle plate 22 have the same potential, the electric field E1 is stronger than the electric field E2 (E1> E2). For this reason, the paper powder Pdn which is negatively charged by scattering due to the collision with the first rib 31 is the electric field strength of the electric field E1 and the electric field E2 which are dispersed in two directions with the support surface 31a of the first rib 31 as a base point. Is predominantly induced by the strong electric field E1 and electrostatically attracted to the sheet metal 40. Note that the positively charged paper powder Pdp scattered by the collision with the first rib 31 is not attracted to the nozzle plate 22 by either the electric field E1 or the electric field E2, and therefore the nozzle plate 22 and the recording paper P It floats between them or adheres to the recording paper P.

  Thereafter, while the recording paper P is being conveyed, the front end Pf collides with the second rib 32 and the third rib 33 in the same manner as the first rib 31, and paper dust Pd is scattered from the front end Pf. The negatively charged paper dust Pdn is electrostatically adsorbed to the sheet metal 40 attached to the second rib 32 and the third rib 33 in the same manner as described above. In this way, the recording paper P is sequentially printed while being conveyed from the upstream side to the downstream side.

In the above embodiment, the following effects can be obtained.
(1) According to the above embodiment, the electric fields having the base points of the support surfaces 31a, 32a, 33a of the ribs 31, 32, 33 are dispersed by grounding each sheet metal 40. For this reason, even if the paper dust Pd is scattered due to the front end Pf of the recording paper P colliding with each of the ribs 31, 32, 33, the negatively charged paper dust Pdn is predominantly guided toward each sheet metal 40. Therefore, it is possible to suppress the paper powder Pdn from being concentrated and adsorbed on the nozzle plate 22. As a result, ink ejection defects due to nozzle clogging and the like are suppressed.

  (2) The sheet metal 40 is provided on both side surfaces of the ribs 31, 32, 33. Therefore, for example, the distance between each support surface 31a, 32a, 33a and the sheet metal 40 can be shortened and scattered as compared with the case where the sheet metal 40 is disposed below the respective absorbers 36, 37. Thus, the negatively charged paper powder Pdn can be easily electrostatically adsorbed to the sheet metal 40.

  (3) The side edge portions on the support surfaces 31a, 32a, 33a side of the respective sheet metals 40 are separated from the support surfaces 31a, 32a, 33a. Therefore, for example, when the side edge portions of the respective sheet metals 40 on the support surfaces 31a, 32a, 33a side are located on the same plane as the support surfaces 31a, 32a, 33a, the front end Pf of the recording paper P is It is possible to avoid the problem that the paper powder Pd scatters from the front end Pf because it collides with the side edges of the sheet metal 40 on the support surfaces 31a, 32a, 33a side.

  (4) The sheet metal 40 is attached to both side surfaces of the ribs 31, 32, 33. Therefore, compared with the case where the sheet metal 40 is attached only to one side surface of each of the ribs 31, 32, 33, it is possible to increase the adsorption force for electrostatically adsorbing the negatively charged paper powder Pdn to the sheet metal 40. .

  (5) The sheet metal 40 is attached to both side surfaces of the ribs 31, 32, 33. Therefore, since the attachment position of the sheet metal 40 is only on both side surfaces of each of the ribs 31, 32, 33, the work of attaching the sheet metal 40 can be facilitated as compared with the case where the sheet metal 40 is provided on the entire side surface of the support member 30. it can.

The above embodiment may be changed to another embodiment as described below.
-In embodiment, the sheet metal 40 may be embed | buried under each rib 31,32,33. For example, as shown in FIGS. 3A and 3B, the ribs 31, 32, 33 are formed with recesses 51 that are recessed from the support surfaces 31 a, 32 a, 33 a toward the main body 30 a side. In each recess 51, the sheet metal 40 can be inserted into each recess 51 from the support surface 31 a side. In a state where the sheet metal 40 is inserted into the recess 51, the side edge portions on the support surfaces 31 a, 32 a, 33 a side of the sheet metal 40 are in a state of facing outward from the opening side of the recess 51.

-In embodiment, the side edge part by the side of each support surface 31a, 32a, 33a of each sheet metal 40 may be located on the same plane as each support surface 31a, 32a, 33a.
-In embodiment, the sheet metal 40 may be attached only to the side surface of one side of each rib 31,32,33.

-In embodiment, the sheet metal 40 may be attached so that the side surface of each rib 31,32,33 and the side surface of the main body 30a may be straddled, for example.
In the embodiment, the sheet metal 40 covers the support surfaces 31 a, 32 a, 33 a in addition to the side surfaces of the ribs 31, 32, 33 and is attached to both sides of the ribs 31, 32, 33. It may be attached so as to connect.

In the embodiment, for example, a conductive paint may be applied as a conductive member to both side surfaces of each of the ribs 31, 32, and 33.
-In embodiment, you may attach the board | plate material made from a conductive resin as a conductive member to the both sides | surfaces of each rib 31,32,33, for example.

  -In embodiment, each rib 31,32,33 and the main body 30a may be provided separately, and each rib 31,32,33 may be the structure which can move to an up-down direction with respect to the main body 30a. . In this case, each rib 31, 32, 33 is attached to the main body 30a via a movable mechanism that moves each rib 31, 32, 33 in the vertical direction.

  The present invention is embodied as an ink jet printer used for printing. However, the present invention is not limited to this, and the present invention may be applied to a liquid ejecting apparatus that ejects liquid other than ink (however, excluding gas). A liquid droplet means a state of liquid ejected from the liquid ejecting apparatus, and includes liquid droplets that are granular, tear-like, or thread-like. The liquid here may be any material that can be ejected by the liquid ejecting apparatus. For example, it may be in a state in which the substance is in a liquid phase, such as a liquid with high or low viscosity, sol, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, liquid metals (metal melts ) And a liquid as one state of the substance, as well as particles in which functional material particles made of solid materials such as pigments and metal particles are dissolved, dispersed or mixed in a solvent. Further, representative examples of the liquid include ink and liquid crystal as described in the above embodiment. Here, the ink includes general water-based inks and oil-based inks, and various liquid compositions such as gel inks and hot-melt inks. As a specific example of the liquid ejecting apparatus, for example, a liquid containing a material such as an electrode material or a coloring material used for manufacturing a liquid crystal display, an EL (electroluminescence) display, a surface light emitting display, a color filter or the like in a dispersed or dissolved form. It may be a liquid ejecting apparatus for ejecting, a liquid ejecting apparatus for ejecting a bio-organic material used for biochip manufacturing, a liquid ejecting apparatus for ejecting a liquid as a sample used as a precision pipette, a printing apparatus, a microdispenser, or the like. In addition, transparent resin liquids such as UV curable resin to form liquid injection devices that pinpoint lubricant oil onto precision machines such as watches and cameras, and micro hemispherical lenses (optical lenses) used in optical communication elements. A liquid ejecting apparatus that ejects a liquid onto the substrate or a liquid ejecting apparatus that ejects an etching solution such as an acid or an alkali to etch the substrate may be employed. The present invention can be applied to any one of these liquid ejecting apparatuses.

Next, a technical idea that can be grasped from the above embodiment and another embodiment will be additionally described below.
(A) The liquid ejecting apparatus according to claim 2, wherein the conductive member is provided on both side surfaces of the rib.

  (B) The liquid ejecting apparatus according to any one of claims 1 to 3 and the technical idea (A), wherein the conductive member is a sheet metal.

  P: Recording paper as recording medium, 21: Recording head as liquid jet head, 30 ... Support member, 31 ... First rib, 31a, 32a, 33a ... Support surface, 32 ... Second rib, 33 ... Third rib 40 ... Sheet metal as a conductive member.

Claims (5)

A support member having a support surface for supporting the recording medium;
A liquid ejecting head that is disposed so as to face the support member and that ejects liquid onto the surface of the recording medium;
With
With the conductive member is provided in the realm of the recording medium is supported, the conductive member is grounded,
In the transport direction in which the recording medium is transported, the upstream end portion of the conductive member in the transport direction is upstream from the end portion of the grounded member provided on the side where the liquid ejecting head faces the support member. A liquid ejecting apparatus, wherein the liquid ejecting apparatus is located in The support member includes a rib that has the support surface and protrudes toward the liquid jet head,
The liquid ejecting apparatus according to claim 1, wherein the conductive member is provided on a side surface of the rib. The liquid ejecting apparatus according to claim 1, wherein an edge of the conductive member on the support surface side is separated from the support surface. In the transport direction in which the recording medium is transported, the downstream end of the conductive member in the transport direction is located downstream of the end of the grounded member of the liquid ejecting head. The liquid ejecting apparatus according to any one of claims 1 to 3. The liquid ejecting head includes a grounded member that is grounded on a side facing the support member, and a distance between the support surface and the conductive member is shorter than a distance between the support surface and the grounded member. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus.

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