JP2006159664A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing peeling of ink from a recording medium due to a spur and retransfer of ink to the recording medium.
In an image forming apparatus having means for transporting a sheet material and an image forming section for forming an image on the sheet by ejecting ink droplets onto the sheet material during the transport process, the sheet material is transported to the image forming section. A restraining means that is on the downstream side in the direction and contacts the image forming surface of the sheet material and applies a restraining force of the posture of the sheet material when the sheet material is transported, and prevents adhesion between the sheet material contact portion of the restraining means and the ink component Release agent applying means for applying the releasing agent to the restraining means. Furthermore, you may provide the cleaning member which can wipe off the deposit | attachment adhering to the sheet | seat material contact of a restraining means.
[Selection] Figure 1

Description

  The present invention relates to an image forming apparatus, and more particularly to an ink jet recording apparatus that performs recording by ejecting ink onto a recording medium.

  As a conventional image recording apparatus, an image recording medium is intermittently conveyed in a sheet-like image recording unit, and an image is recorded by ejecting ink droplets with a predetermined width in a direction perpendicular to the conveying direction at each conveyance stop. There is an ink jet recording apparatus.

  FIG. 5 is a schematic cross-sectional view of a printing unit of an image forming apparatus that is conventionally seen. In FIG. 5, the recording medium 201 is fed from the direction of the arrow K, is gripped between the sub-scanning roller 202 and the pinch roller 203 pressed against the sub-scanning roller 202, and the platen 206 in the downstream direction is rotated by the rotation of the sub-scanning roller 202. It is conveyed to the side.

  The platen 206 is disposed so as to planarly support the recording medium 201 conveyed by the sub-scanning roller 202 with its upper surface 206a. The main scanning rail 221 is arranged so that its axial direction is perpendicular to the conveying direction of the recording medium 201 and is above the platen 206 and parallel to the upper surface 206a.

  The carriage 222 is inserted into the main scanning rail 221 and is connected to a linear movement drive mechanism (not shown) and can move in the direction perpendicular to the paper surface, that is, the main scanning direction. The carriage 222 has an ink jet recording head 223 therein, and is configured such that its ink discharge surface faces the upper surface 206a of the platen 206. While the carriage 222 moves in the main scanning direction, the ink discharge surface and the recording are recorded. The distance from the medium 201 is maintained with high accuracy as long as the recording medium 201 is corrected in posture by the platen 206.

  The carriage 222 receives an electrical signal from the main body control unit via a cable (not shown), transmits the electrical signal to the recording head, and discharges ink. When an ejection signal is received during the main scanning movement of the carriage 222, a band-like image having a width corresponding to the ejection nozzle row of the recording head is formed on the recording medium 201 on the platen 206.

  The paper discharge roller 224 is on the downstream side in the conveyance direction of the recording medium 201 with respect to the platen 206, and the height of the highest portion of the peripheral surface thereof and the height of the upper surface 206a of the platen 206 are set to be substantially the same. A spur-like rotating body (hereinafter referred to as a “spur”) 211 is configured as a rotating body in which a plurality of protrusions with sharply protruding tips are arranged on the circumference thereof, and is slightly pressed against the uppermost portion of the peripheral surface of the paper discharge roller 224. It is comprised so that.

  The recording medium 201 that has passed through the platen 206 is gripped by the paper discharge roller 224 and the spur 211, restrains the recording medium 201 from floating from the upper surface 206 a of the platen 206, and is applied by the sub-scanning roller 202 and the pinch roller 203. The recording medium 201 is transported with a transport force weaker than the transport force. A spur-like rotating body is disclosed in Patent Document 1.

Conventionally, in an image recording apparatus that uses ink containing a dye as a molten component, both the dye component and the solvent component of the ink penetrate into the recording medium 201 relatively quickly, and the recording medium 201 receives the ink on the platen 206. If there is a predetermined time or more until the intermittent conveyance until reaching the spur 211, most of the ink has penetrated into the inside of the recording medium 201, so that the surface of the recording medium 201 is almost dried and the recording medium Even when the protrusions of the spur 211 come into contact with the ink receiving surface 201, there was almost no ink peeling or contact marks.
JP 2004-106978 A

  In recent years, printing speed has been increased, and the time from when ink is received by the recording medium on the platen until reaching the spur is shortened by improving the conveyance speed of the recording medium and the head main scanning speed. In some cases, the ink receiving surface comes into contact with the spur before the ink dries.

  In such a case, the ink may be peeled off from the recording medium by a spur, or the ink attached to one end of the spur may be retransferred to the recording medium after one revolution of the spur. In addition, image recording apparatuses using pigment inks mainly composed of pigments have been developed for image fastness, but the pigment hardly penetrates inside the recording medium, and only the surface layer of the recording medium. Until the pigment is fixed, the surface layer of the recording medium is in a sticky state and the surface rubbing resistance is very weak. Furthermore, the time required for the pigment to dry and fix on the surface of the recording medium is a dye. Longer than system ink.

  Even when the above pigment ink is used, the pigment on the recording medium is peeled off from the recording medium by a spur, or the pigment adhering to one end of the spur is retransferred to the recording medium after one revolution of the spur. In addition, the pigment is deposited on the peripheral protrusion of the spur, and due to the stickiness of the deposited pigment, the ink layer on the new image surface is repeatedly peeled off from the recording medium. In the above case, dot marks are continuously formed on the recorded image in the transport direction, and the image quality is extremely deteriorated.

  Accordingly, an object of the present invention is to provide an image forming apparatus that can prevent the ink from being peeled off from the recording medium by the spur and the retransfer of the ink to the recording medium.

  The present invention relates to an image forming apparatus having a means for conveying a sheet material and an image forming unit for forming an image on the sheet by ejecting ink droplets on the sheet material during the conveying process. A restraining means that is in the downstream side of the sheet and contacts the image forming surface of the sheet material, and applies a restraining force of the posture of the sheet material when the sheet material is conveyed, and adhesion between the sheet material contact portion of the restraining means and the ink component And a release agent applying means for applying a release agent to be prevented to the restraining means.

  According to the above, since the release means is always applied to the recording medium restraint means represented by a spur that is arranged on the downstream side of the recording unit and contacts the ink receiving surface, it is possible to prevent adhesion and accumulation of ink and recording. Peeling of the ink layer on the medium and reverse transfer of the ink from the restraining means to the recording medium can be prevented, and the image quality can be maintained.

  FIG. 1 is a schematic perspective view showing an embodiment of the present invention. In FIG. 1, a recording medium 101 that is a sheet material is fed from the direction of the arrow K and is gripped between the sub-scanning roller 102 and pinch rollers 103, 104, and 105 that are pressed against the sub-scanning roller 102, and the sub-scanning roller 102. Is conveyed to the image forming unit side including the platen 106 and the recording head 123 in the downstream direction.

  The platen 106 is disposed so as to planarly support the recording medium 101 conveyed by the sub-scanning roller 102 with its upper surface 106a. The main scanning rail 121 has an axial direction perpendicular to the conveyance direction of the recording medium 101 and is disposed above the platen 106 and parallel to the upper surface 106a.

  The carriage 122 is inserted into the main scanning rail 121 and is connected to a linear movement drive mechanism (not shown) and is movable in the directions of arrows L and R, that is, the main scanning direction. The carriage 122 has an ink jet recording head 123 therein, and is configured so that the ink discharge surface thereof faces the upper surface 106a of the platen 106. While the carriage 122 moves in the main scanning direction, the ink discharge surface and the recording are recorded. The distance from the medium 101 is maintained with high accuracy as long as the recording medium 101 is corrected in posture by the platen 106.

  In addition, the carriage 122 receives an electrical signal from the main body control unit via a cable (not shown), transmits the signal to the recording head, and ejects ink. When an ejection signal is received during the main scanning movement of the carriage 122, a band-like image having a width corresponding to the ejection nozzle row of the recording head is formed on the recording medium 101 on the platen 106.

  The paper discharge roller 124 is on the downstream side in the conveyance direction of the recording medium 101 with respect to the platen 106, and the height of the highest portion of the peripheral surface thereof and the height of the upper surface 106a of the platen 106 are set to be substantially the same. Preferably, the restraining means, which is a spur 111 to 115, is configured as a rotating body in which a plurality of protrusions with sharply protruding tips are arranged on the circumference thereof, and is supported rotatably around the elastic shafts 116 to 120, respectively. It is configured to be slightly pressed against the uppermost portion of the peripheral surface of the paper discharge roller 124 by the reaction force of the bending of each elastic shaft.

  FIG. 2 is a front view seen from the axial direction of the spur. In FIG. 2, for the pigment ink, one blade edge angle of each spur seen from the axial direction affects the degree of pigment ink adhesion to the blade edge, and in experiments, a relatively sharp angle is good. As shown in the figure, good results were obtained at around 30 ° to 35 °.

  FIG. 3 is a cross-sectional view showing a cross-sectional shape in the plate thickness direction of one cutting edge in the spur. As shown in FIG. 3, in this embodiment, 110 parts obtained by half-etching the plate thickness are formed and made sharper. This is based on an experimental result that the sharper the ink adhesion is minimized.

  The recording medium 101 that has passed through the platen 106 is held by the paper discharge roller 124 and the spurs 111 to 115, restraining the recording medium 101 from floating from the upper surface 106 a of the platen 106, and the sub-scanning roller 102 and the pinch rollers 102 and 103. , 104 is used to transport the recording medium 101 with a transport force weaker than the transport force applied.

  FIG. 4 is a cross-sectional view showing a state in which the release agent applying means and the cleaning member are arranged adjacent to the spur. In FIG. 4, the release agent application means, preferably oil application rollers 131 to 135, is composed of a porous elastic body on its peripheral surface, and impregnates silicone oil as an example of a release agent that makes it easy to peel off the adhesive substance. ing. As the material of the oil application rollers 131 to 135, for example, Rubycell manufactured by Ozu Sangyo Co., Ltd. is suitable. When the recording medium is held by the spurs 111 to 115 and the paper discharge roller 124, the peripheral surfaces of the oil application rollers 131 to 135 are arranged so as to barely contact the protrusions on the peripheral surfaces of the spurs 111 to 115. The roller shafts 136 to 140 are rotatably held.

  When the spurs 111 to 115 are rotated as the recording medium 101 is conveyed, the oil application rollers 131 to 135 that are in contact with the spurs 111 and 135 are also rotated to transfer the oil that is impregnated and held to the spurs 111 to 115.

  If the viscosity of the silicone oil is too low, it will ooze out to surrounding components, and if the viscosity is high, it will be difficult to transfer to the spurs 111 to 115, so that a result of 300 cs to 10000 cs is obtained. Yes. If the viscosity increases to some extent, it becomes difficult to impregnate the porous elastic body constituting the oil-coated roller at room temperature. Therefore, during the impregnation operation, the oil is heated and the impregnation operation is performed by decreasing the apparent viscosity.

  In the present embodiment, the cleaning members 141 to 145 further have a spur 111 on the downstream side in the rotation direction from the contact portion with the recording medium 101 with respect to the rotation direction of the spurs 111 to 115 when the recording medium 101 moves in the printing direction. It arrange | positions so that it may contact with -115.

  The cleaning members 141 to 145 are rotatably supported around the rotation center shafts 146 to 150, and can be driven to rotate by contacting the spurs 111 to 115. The cleaning members 141 to 145 are composed of a nonwoven fabric or a porous elastic body.

  In consideration of durability, the cleaning members 141 to 145 cannot deny the possibility that the ink adheres to the blade edge of the spur coated with oil. In addition, the edge of each spur can be cleaned, and durability can be improved from the viewpoint of maintaining image quality. With the above configuration, it is possible to apply or clean oil as a release agent to the spurs 111 to 115 with a simple configuration.

It is a schematic perspective view which shows embodiment of this invention. It is the front view seen from the axial direction of a spur. It is sectional drawing which shows the cross-sectional shape of a plate | board thickness direction about one blade edge | tip in a spur. It is sectional drawing which shows the state which has arrange | positioned the mold release agent application means and the cleaning member adjacent to the spur. It is a schematic sectional drawing of the image formation part of the conventional image recording apparatus.

Explanation of symbols

123 Recording Heads 111-115 Spurs 131-135 Oil Application Rollers 141-145 Cleaning Member

Claims (7)

In an image forming apparatus having a means for transporting a sheet material and an image forming unit that forms an image on the sheet by ejecting ink droplets onto the sheet material in the transport process,
A restraining unit that is on the downstream side in the sheet material conveyance direction with respect to the image forming unit, contacts the image forming surface of the sheet material, and applies a restraining force of the posture of the sheet material when conveying the sheet material;
A release agent application means for applying a release agent for preventing adhesion between the sheet material contact portion of the restraint means and the ink component to the restraint means;
An image forming apparatus comprising: The restraining means is a rotating body having a rotating function that rotates as the sheet material is conveyed, and the release agent coating means is in contact with a part or all of the locus of the rotating surface of the generally restraining means. 2. The image forming apparatus according to claim 1, wherein the release agent is applied at the contact position. The image forming apparatus according to claim 2, wherein the release agent coating unit has a function of being rotated by contact with the rotating restraining unit. The release agent applying means holds the liquid release agent by capillary action and transfers the release agent to the restraining means by bringing the sheet material contact portion of the rotating restraining means into contact with the applying means. The image forming apparatus according to claim 1, wherein a release agent is applied. 5. The image forming apparatus according to claim 4, wherein the release agent applying means is made of a porous elastic material and a material capable of impregnating a liquid release agent. The image forming apparatus according to claim 1, wherein the restraining unit is a spur-like rotating body having a plurality of sharp protrusions on a peripheral surface. It further comprises a cleaning member that can contact the sheet material contact of the restraining means independently of the release agent application means and can wipe off the deposits attached to the sheet material contact of the restraining means. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.