JP2011140237A - Liquid ejecting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent liquid droplets from turning into mist, the liquid droplets being ejected from a liquid ejecting head toward a region deflected from an object to be treated. <P>SOLUTION: A liquid ejecting apparatus includes a liquid ejecting head 12 for ejecting liquid droplets from a nozzle opening of a nozzle plate 17, a scanning mechanism for scanning the liquid ejecting head 12 in a head-scanning direction, a conveying mechanism for conveying an object 6 to be treated, a platen 5 for defining a position to the liquid ejecting head 12 by supporting the object 6 to be treated with its back side, which is electrically insulated from the environment, an absorbing member 16 provided on the platen 5 for absorbing the liquid droplets ejected toward a region deflected from an object 6 to be treated, and a potential difference-generating means 20, 21, 22 for generating a potential difference between at least one member of the absorbing member 16 and a member adjacent to the absorbing member and the nozzle plate 17. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid ejecting apparatus that ejects liquid droplets from a nozzle opening of a liquid ejecting head toward an object to be processed.

  A typical example of a conventional liquid ejecting apparatus is an ink jet recording apparatus provided with an ink jet recording head for image recording. As other liquid ejecting apparatuses, for example, an apparatus having a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an electrode material (conductive paste) used for forming an electrode such as an organic EL display, a surface emitting display (FED), etc. ) An apparatus equipped with an ejection head, an apparatus equipped with a bioorganic matter ejection head used for biochip production, an apparatus equipped with a sample ejection head as a precision pipette, and the like.

  An ink jet recording apparatus, which is a typical example of a liquid ejecting apparatus, is used for many printing including color printing in recent years because noise during printing is relatively low and small dots can be formed with high density. .

  Such an ink jet recording apparatus generally includes an ink jet recording head mounted on a carriage and reciprocally moved in the width direction (head scanning direction) of a recording medium such as recording paper (processing object), and the recording medium as a head. And a feed mechanism that moves in a direction (feed direction) perpendicular to the scanning direction, and is further arranged to face the recording head and supports the recording medium conveyed by the feeding mechanism from the back surface with respect to the recording head. A platen for defining the position of the recording medium is provided.

  In this ink jet recording apparatus, printing is performed by ejecting ink droplets from a recording head to a recording medium in accordance with print data. The recording head mounted on the carriage can discharge, for example, black, yellow, cyan, and magenta inks, so that not only text printing with black ink but also the discharge ratio of each ink can be achieved. By changing it, full-color printing is possible.

  When printing is performed on the entire surface of the recording medium without leaving a margin at the edge of the recording medium using this ink jet recording apparatus (so-called four-edge-less printing), there is a margin for displacement of the recording medium and the carriage. Considering this, printing is performed on an area slightly larger than the size of the recording medium.

  That is, in order to perform printing without leaving a margin at the left and right side edges (edges extending in the feeding direction) of the recording medium, the scanning range of the recording head during printing is outside the side edges of the recording medium. It is possible to set up to a position that deviates.

  Further, when printing is performed without leaving a margin at the front and rear edges (edges extending in the head scanning direction) of the recording medium, the printing medium deviates to the front side from the front edge at the start of printing. The area up to the area is designated as the print target area, and at the end of printing of the recording medium, the area up to the rear side of the trailing edge of the recording medium is designated as the print target area.

  The ink droplets ejected toward the area outside the recording medium are absorbed by an absorbing member (sponge, bell eater, etc.) disposed on the back side of the recording medium so as to face the recording head.

JP 2002-86757 A

  As described above, when printing is performed without leaving a margin at the edge of the recording medium, the ink droplets are ejected from the edge of the recording medium to a region outside the front and rear or left and right. There is a problem that the ink mist that wraps around the back side of the recording medium adheres to the edge of the back surface of the recording medium and stains the recording medium. In particular, it is a problem when performing double-sided printing on a recording medium or when printing on a recording medium that uses both sides, such as a postcard. In addition, the mist ink smudges the interior of the machine, causing malfunction due to adhesion of the ink mist to an electric circuit or a linear scale, and depositing on the ink cartridge to contaminate the user's hand.

  In general, a feeding mechanism for feeding a recording medium in a feeding direction includes rollers that are arranged to face each other so as to sandwich and feed the recording medium. One of the opposed rollers is a driving roller having a structure in which alumina is baked on the surface of the metal roller to improve the frictional force, and the other roller is a driven roller made of plastic.

  In general, contact / peeling between these rollers and the recording medium, rubbing with the next recording medium when the recording medium is supplied from the auto sheet feeder, contact with a structural member in the recording medium supply path, etc. Thus, the recording medium is charged when it is sent to the printing area. If the recording medium is charged in this way, the above-described ink mist tends to adhere to the back surface of the recording medium.

  In order to solve such a problem, a method of providing a discharging means such as a discharging brush for discharging the charged recording medium is also conceivable. In this case, the installation position of the discharging means is necessarily a pair of rollers. Therefore, the distance from the feed mechanism to the printing area is longer than that of the feed mechanism. For this reason, problems such as deterioration in the feeding accuracy of the recording medium and floating of the recording medium are likely to occur. Further, there is also a problem in that paper dust or the like is generated by rubbing a recording medium such as paper with a static elimination brush and adheres to the nozzle, thereby deteriorating ink droplet ejection performance.

  In addition, in order to meet the recent demand for higher image quality, the size of ink droplets ejected from a recording head is becoming smaller and smaller. Since the speed of small-sized ink droplets decreases rapidly due to the viscous resistance of air, the ink droplets ejected from the recording head toward the area outside the recording medium may mist without reaching the absorbing member There is.

  The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to prevent mist formation of liquid droplets ejected from a liquid ejecting head toward a region outside the object to be processed. An object of the present invention is to provide a liquid ejecting apparatus that can perform the above-described operation.

  In order to solve the above-described problem, a liquid ejecting apparatus according to the present invention includes a nozzle plate in which a nozzle opening is formed, and causes a pressure fluctuation in the liquid in a pressure chamber communicating with the nozzle opening to cause a liquid from the nozzle opening. A liquid ejecting head that ejects droplets, a scanning mechanism that causes the liquid ejecting head to scan in the head scanning direction, and an object to which a liquid droplet ejected from the liquid ejecting head is applied is orthogonal to the head scanning direction. A feed mechanism that feeds in the feed direction, and a position of the workpiece with respect to the liquid jet head that is disposed opposite to the liquid jet head and supports the workpiece to be transported by the feed mechanism from its back surface A platen that is electrically insulated from the surroundings, and on the back side of the object to be processed and facing the liquid jet head An absorbing member that is provided on the platen in a region and absorbs droplets discharged toward the region that is removed from the object to be processed; at least one of the absorbing member or a member adjacent to the absorbing member; and the nozzle plate And a potential difference generating means for generating a potential difference between them.

  Preferably, the potential difference generating means applies a voltage to at least one of the absorbing member and a member adjacent to the absorbing member to ground the nozzle plate.

  Preferably, the potential difference generating means grounds at least one of the absorbing member and a member adjacent to the absorbing member, and applies a voltage to the nozzle plate.

  Preferably, the member adjacent to the absorbing member has a conductive portion extending along the head scanning direction and a conductive portion extending along the feed direction.

  Preferably, the member adjacent to the absorbing member has a lattice shape.

  Preferably, the absorbing member includes a conductive material.

  Preferably, the absorbing member is foamed by mixing a conductive material into polyethylene or polyurethane.

  Preferably, the absorbing member is obtained by plating a polyethylene or polyurethane foam with a conductive material.

  Preferably, the absorbing member contains an electrolyte liquid.

  Preferably, the electrolyte liquid is a liquid ejected from the liquid ejecting head.

  Preferably, the apparatus further includes holding means for holding the workpiece to be processed in an electrically floating state.

  Preferably, the holding means includes an insulating material provided on at least a surface of each member that contacts the object to be processed.

  Preferably, the absorbing member is disposed so as not to contact the object to be processed, and a member adjacent to the absorbing member is disposed so as not to contact the object to be processed.

  Preferably, the potential difference generating means generates an electric field in a direction in which droplets are ejected from the liquid ejecting head.

  In order to solve the above-described problem, a liquid ejecting apparatus according to the present invention includes a nozzle plate in which a nozzle opening is formed, and causes a pressure fluctuation in the liquid in a pressure chamber communicating with the nozzle opening to cause a liquid from the nozzle opening. A liquid ejecting head that ejects droplets, a scanning mechanism that causes the liquid ejecting head to scan in the head scanning direction, and an object to which a liquid droplet ejected from the liquid ejecting head is applied is orthogonal to the head scanning direction. A feed mechanism that transports in the feed direction, and a liquid that is disposed on a back surface side of the object being processed and is opposed to the liquid jet head, and is discharged toward a region that is out of the object to be processed An absorbing member that absorbs droplets; and a potential difference generating unit that generates a potential difference between at least one of the absorbing member or the member adjacent to the absorbing member and the nozzle plate. To have.

  As described above, according to the liquid ejecting apparatus of the present invention, the potential difference is generated from the nozzle opening by generating a potential difference between at least one of the absorbing member or the adjacent member and the nozzle plate by the potential difference generating means. In addition, the Coulomb force acting toward the absorbing member acts on the charged droplets, so that mist formation of the droplets ejected from the liquid jet head toward the area outside the object to be processed is reliably prevented. can do.

1 is a perspective view illustrating a schematic configuration of an ink jet recording apparatus as an embodiment of a liquid ejecting apparatus according to the invention. FIG. 9 is another perspective view showing a schematic configuration of an ink jet recording apparatus as an embodiment of the liquid ejecting apparatus according to the invention. The figure which expanded and showed the platen of the ink jet type recording apparatus shown in FIG.1 and FIG.2, and its periphery. FIG. 3 is an enlarged cross-sectional view of a potential difference generating unit and its periphery of the ink jet recording apparatus shown in FIGS. 1 and 2. FIG. 3 is a diagram showing a state of lines of electric force generated by a potential difference generating unit of the ink jet recording apparatus shown in FIGS. 1 and 2. The figure which expanded and showed a part of FIG. Sectional drawing which showed the modification of embodiment shown in FIG. The top view which showed the other modification of embodiment shown in FIG. Sectional drawing which showed the modification shown in FIG. Sectional drawing which showed the other modification of embodiment shown in FIG.

  Hereinafter, an ink jet recording apparatus as an embodiment of a liquid ejecting apparatus according to the present invention will be described with reference to the drawings.

  The ink jet recording apparatus according to the present embodiment is an ink jet recording apparatus in which the pressure generating element provided corresponding to the pressure chamber communicating with the nozzle opening causes pressure fluctuations in the ink in the pressure chamber to eject ink droplets from the nozzle opening. A recording head (a type of liquid ejecting head) is provided. As the pressure generating element, for example, a piezoelectric vibrator can be used.

  1 and 2 are perspective views showing a schematic configuration of the ink jet recording apparatus according to the present embodiment, and FIG. 3 is an enlarged view of a platen of the ink jet recording apparatus and its periphery. In FIG. 1, reference numeral 1 denotes a carriage. The carriage 1 is guided by a guide member 4 via a timing belt 3 driven by a carriage motor 2 and is reciprocated in the axial direction of the platen 5. Yes. The platen 5 supports the recording paper 6 (a kind of object to be processed) from the back surface thereof and defines the position of the recording paper 6 with respect to the recording head 12.

  The carriage 1, the carriage motor 2, the timing belt 3, and the guide member 4 constitute a scanning mechanism that scans the ink jet recording head 12 together with the carriage 1 in the head scanning direction.

  The ink jet recording head 12 has a plurality of pressure chambers 12 b communicating with the plurality of nozzle openings 12 a, and is mounted on the side of the carriage 1 facing the recording paper 6. An ink cartridge 7 that supplies ink to the recording head 12 is detachably mounted on the carriage 1.

  A cap member 13 is arranged at a home position (right side in FIG. 1) which is a non-printing area of the ink jet recording apparatus, and the recording head 12 mounted on the carriage 1 has moved to the home position. Sometimes, it is configured to be pressed against the nozzle forming surface of the recording head 12 to form a sealed space with the nozzle forming surface. A pump unit 10 for applying a negative pressure to the sealed space formed by the cap member 13 is disposed below the cap member 13.

  In the vicinity of the printing area side of the cap member 13, a wiping means 11 having an elastic plate such as rubber is disposed so as to be able to advance and retreat in the horizontal direction with respect to the movement trajectory of the recording head 12. When reciprocating toward the member 13 side, the nozzle forming surface of the recording head 12 can be wiped off as necessary.

  The ink jet recording apparatus according to the present embodiment further includes a feeding mechanism that intermittently conveys the recording paper 6 on which printing processing is performed by the recording head 12 in a feeding direction orthogonal to the head scanning direction.

  As shown in FIG. 3, the feed mechanism is opposed to each other to feed paper rollers 14 a and 14 b that are disposed opposite to each other to sandwich the recording paper 6 and feed it onto the platen 5, and to each other to discharge the printed recording paper 6. Disposed paper discharge rollers 15a and 15b are provided. The paper supply roller 14a and the paper discharge roller 15a are driven rollers, and the paper supply roller 14b and the paper discharge roller 15b are drive rollers.

  As can be seen from FIG. 3, the platen 5 has a plurality of ink receiving vertical openings 5 c, 5 d, 5 e, 5 f extending in a direction parallel to the paper feeding direction (feeding direction) F, and head scanning perpendicular to the paper feeding direction F. A plurality of ink receiving lateral openings 5a and 5b extending in the direction are formed.

  Of the plurality of ink receiving vertical openings 5c, 5d, 5e, and 5f, the pair of ink receiving openings 5c are arranged so that the left and right ends of the A3 size recording paper 6 pass directly above, respectively. The openings 5d are arranged so that the left and right ends of the B4 size recording paper 6 pass directly above, and the pair of ink receiving openings 5e allows the left and right ends of the A4 size recording paper 6 to pass right above. The pair of ink receiving openings 5f are arranged so that the left and right ends of the B5 size recording paper 6 pass right above each other.

  Further, the plurality of ink receiving lateral openings 5a and 5b include a paper feeding side ink receiving opening 5a arranged on the paper feeding side and a paper discharging side ink receiving opening 5b arranged on the paper discharging side.

  In each of the ink receiving openings 5a, 5b, 5c, 5d, 5e, and 5f, an absorbing member 16 that absorbs the ink ejected from the recording head 12 is disposed.

  In the present embodiment, the absorbing member 16 includes a conductive material, and is formed by foaming, for example, by mixing a conductive material such as carbon into polyethylene or polyurethane. Alternatively, the absorbing member 16 can be formed by applying a conductive material to a foamed material of polyethylene or polyurethane by plating.

Further, the absorbing member 16 can be provided with conductivity by containing an electrolyte aqueous solution such as NaCl, KCl or water. Even when only water is contained, CO ₂ or the like in the atmosphere is taken in and becomes a conductive electrolyte.

  As a simpler method, the ink itself can be used as the electrolyte. In this case, before performing the first borderless printing, the ink droplets are ejected from the recording head 12 to the absorbing member 16 while slowly scanning the carriage 1 so that the ink droplets do not become mist without the recording paper 6. Ink can be contained in the absorbing member 16 to impart conductivity.

  As shown in FIG. 4, the ink jet recording apparatus according to the present embodiment grounds the power supply 20 and its wiring 21 for applying a positive voltage to the conductive absorbing member 16 and the nozzle plate 17. Wiring 22. The power supply 20 and the wirings 21 and 22 constitute a potential difference generating unit that generates a potential difference between the nozzle plate 17 and the absorbing member 16.

  By applying a positive voltage to the absorbing member 16 and grounding the nozzle plate 17 by this potential difference generating means, a positive charge is induced in the absorbing member 16 as shown in FIGS. A negative charge is induced in As a result, electric lines of force from the absorbing member 16 toward the nozzle plate 17 are generated as indicated by arrows in FIGS. 5 and 6.

  In addition, when negative charges are induced in the nozzle plate 17, negative charges are also induced in the ink meniscus portion of the nozzle openings 12a. This amount of charge can be easily calculated using the parallel plate capacitor equation. The ink droplet is discharged from the nozzle opening 12a with a negative charge corresponding to the area of the nozzle opening 12a, and the electric field generated between the nozzle plate 17 and the absorbing member 16 generates a Coulomb force in the direction of the absorbing member 16. receive.

  In this way, the ink droplets ejected from the nozzle opening 12a are subjected to the Coulomb force in the direction of the absorbing member 16, and therefore when ink droplets having a small size are ejected toward the area protruding from the edge 6a of the recording paper 6. In addition, the ink droplet can surely reach the absorbing member 16. As a result, it is possible to reliably prevent the ink droplets ejected toward the area outside the recording paper 6 from becoming mist. For this reason, even when printing is performed without leaving a margin on the edge 6a of the recording paper 6, it is possible to prevent the ink mist from adhering to the back edge of the recording paper 6 and the inside of the machine from being damaged by the ink mist. .

  Further, when the resistance of the recording paper 6 decreases due to moisture or the like, the recording paper 6 has conductivity, and one end of the recording paper 6 is grounded to the ground (Gnd), the absorption applied with a voltage is applied. An electric field is generated between the member 16 and the recording paper 6, and no electric field is generated between the recording paper 6 and the nozzle plate 17. For this reason, sufficient charges are not induced in the nozzle plate 17 and the ink droplets, and the above-described mist prevention effect by the potential difference generating means cannot be sufficiently exhibited.

  Therefore, as a modification of the above embodiment, it is preferable to provide holding means for holding the recording paper 6 being processed in an electrically floating state. Preferably, the holding means includes insulating members 18a and 18b provided on at least the surfaces of the members, for example, the paper feed rollers 14a and 14b, which are in contact with the recording paper 6 being processed as shown in FIG.

  By thus holding the recording paper 6 being processed in an electrically floating state by the holding means 18a and 18b, the recording paper 6 simply acts as a dielectric. Here, as shown in FIG. 7, the distance between the nozzle plate 17 and the recording paper 6 is L1, the distance between the recording paper 6 and the surface of the absorbing member 16 is L2, and a voltage of 3 kV is applied to the power source 20. In this case, for example, if L1 = 2.0 mm and L2 = 1.0 mm, the potential of the recording paper 6 is about 2 kV. Therefore, sufficient charge can be induced in the nozzle plate 17 and the ink droplets regardless of the presence or absence of the recording paper 6.

  As another modification of the above-described embodiment, as shown in FIGS. 8 and 9, a lattice member 23 made of a conductive material is disposed adjacent to the upper surface of the absorbing member 16, and the lattice member 23. Alternatively, a positive voltage can be applied from the power supply 20. The grid member 23 has a conductive portion 23a extending along the head scanning direction and a conductive portion 23b extending along the feed direction.

  In the case of this modification, it is not always necessary to make the absorbing member 16 conductive, and the absorbing member 16 can be formed of, for example, a sponge or a bell eater. Alternatively, as in the embodiment shown in FIG. 4, the absorbing member 16 can be used as a conductive member, and a voltage can be applied to both the grid member 23 and the absorbing member 16.

  In this modification, the ink mist attracted to the lattice member 23 side adheres to the surface of the lattice member 23 and flows down on the absorption member 16 or directly adheres to the absorption member 16.

  As another modification of the above embodiment, the direction of the electric field generated by the potential difference generating means can be reversed. That is, as shown in FIG. 10, not the nozzle plate 17 but the absorbing member 16 may be grounded, and a positive voltage may be applied to the nozzle plate 17 by the power source 20. Alternatively, the nozzle plate 17 may be grounded and a negative voltage may be applied to the absorbing member 16.

1 Carriage 5 Platen 6 Recording paper (object to be processed)
12 Inkjet recording head (liquid jet head)
14a, 14b Paper feeding roller 16 Absorbing member 17 Nozzle plate 18a, 18b Insulating material 20 Power source 21, 22 Wiring 23 Grid member

Claims (14)

A liquid ejecting head that has a nozzle plate in which a nozzle opening is formed, causes a pressure fluctuation in a liquid in a pressure chamber communicating with the nozzle opening, and discharges droplets from the nozzle opening;
A scanning mechanism for scanning the liquid ejecting head in a head scanning direction;
A feed mechanism for transporting a workpiece to which droplets ejected from the liquid jet head are applied in a feed direction perpendicular to the head scanning direction;
A platen disposed opposite to the liquid ejecting head and supporting the object to be processed conveyed by the feeding mechanism from the back surface thereof, and defining a position of the object to be processed with respect to the liquid ejecting head, from the surroundings A platen that is electrically isolated;
Absorbing member that is provided on the platen in a region facing the liquid ejecting head on the back side of the object to be processed and that absorbs liquid droplets discharged toward the region outside the object to be processed When,
A liquid ejecting apparatus comprising: a potential difference generating unit configured to generate a potential difference between at least one of the absorbing member or a member adjacent to the absorbing member and the nozzle plate.   The liquid ejecting apparatus according to claim 1, wherein the potential difference generating unit applies a voltage to at least one of the absorbing member and a member adjacent to the absorbing member to ground the nozzle plate.   The liquid ejecting apparatus according to claim 1, wherein the potential difference generating unit applies a voltage to the nozzle plate by grounding at least one of the absorbing member and a member adjacent to the absorbing member.   4. The member adjacent to the absorbing member has a conductive portion extending along the head scanning direction and a conductive portion extending along the feeding direction. 5. The liquid ejecting apparatus according to 1.   The liquid ejecting apparatus according to claim 4, wherein the member adjacent to the absorbing member has a lattice shape.   The liquid ejecting apparatus according to claim 1, wherein the absorbing member includes a conductive material.   The liquid ejecting apparatus according to claim 6, wherein the absorbing member is formed by foaming by mixing a conductive material into polyethylene or polyurethane.   The liquid ejecting apparatus according to claim 6, wherein the absorbing member is obtained by applying a conductive material to a foamed material of polyethylene or polyurethane by plating.   The liquid ejecting apparatus according to claim 6, wherein the absorbing member contains an electrolyte liquid.   The liquid ejecting apparatus according to claim 9, wherein the electrolyte liquid is a liquid ejected from the liquid ejecting head.   The liquid ejecting apparatus according to claim 1, further comprising a holding unit configured to hold the object to be processed in an electrically floating state.   The liquid ejecting apparatus according to claim 11, wherein the holding unit includes an insulating material provided on at least a surface of each member that contacts the object to be processed. The absorbing member is disposed so as not to contact the object to be processed,
The liquid ejecting apparatus according to claim 1, wherein a member adjacent to the absorbing member is disposed so as not to contact the object to be processed.   The liquid ejecting apparatus according to claim 1, wherein the potential difference generating unit generates an electric field in a discharge direction of a droplet from the liquid ejecting head.

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