JP2007057628A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a separation pawl by which a rotating body can be hardly scratched. <P>SOLUTION: The image forming apparatus includes: the rotating body such as an image carrier 102 with which paper P comes into contact; the separation pawl 32 abutting on the rotating body for separating the paper P from the rotating body; and a driving means for rotating the separation pawl 32. By such constitution, the separation pawl is worn uniformly, so that the increase of the abutting area on the rotating body is restrained, and additive or paper powder hardly intrudes in between, and the rotating body is hardly scratched. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus having a separation claw capable of making it difficult to damage a rotating body.

  2. Description of the Related Art There is an image forming apparatus provided with a separation claw for the purpose of separating a sheet electrostatically attracted to an image carrier after the toner image formed on the image carrier, which is a rotating body, is transferred to the paper. . A plurality of separation claws are provided in a direction parallel to the rotation axis of the image carrier, and the tip is in contact with the image carrier.

The separation claw has a pointed shape like a cone or a quadrangular pyramid so that additives and paper dust may not enter between the separation claw and the image carrier and damage the image carrier. . In the case of a quadrangular pyramid, the ridge line is in contact with the image carrier and the surface is not in contact. (For example, see Patent Document 1 and Patent Document 2). When the separation claw comes into contact with the image carrier, the additive or paper dust enters the contact surface, and the additive or paper dust damages the surface of the image carrier, and a normal image is formed by the scratch. Because it becomes impossible.
Japanese Patent No. 2841639 (FIG. 4) Japanese Patent No. 3356235 (FIGS. 17 and 18)

  However, since the separation claw is in contact with the rotating image carrier, the ridge line gradually wears, and the contact area with the image carrier increases. As a result, additives and paper dust enter between the separation claw and the image carrier, and in some cases, the surface of the image carrier may be damaged by adhering to the contact portion, and a normal image can be formed. It will disappear.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus having a separation claw that can make it difficult to damage a rotating body.

  In order to achieve the above object, an image forming apparatus of the present invention includes a rotating body that contacts a sheet, a separation claw that contacts the rotating body and separates the sheet from the rotating body, and rotates the separation claw. And a driving means.

  The image forming apparatus according to the present invention includes a rotating body that contacts a sheet, a separation claw that separates the sheet from the rotating body, the separation claw that is in contact with the rotating body, and does not contact the rotating body. The separation claw set having the separation claw in the retraction position and the separation claw in the separation claw set are moved to the retraction position, and the separation claw in the retraction position is abutted. Drive means for moving to the contact position.

  The image forming apparatus includes a separation claw set having the separation claw at a position in contact with the rotating body and the separation claw at a retracted position not in contact with the rotating body, and the driving unit includes: A configuration in which, among the separation claws of the separation claw set, the separation claw in the contact position is moved to the retracted position, the separation claw in the retracted position is moved to the contact position, and the separation claw is rotated. You can also

  Further, the separation claw is a cone, and the angle at which the drive means rotates the separation claw by one drive is an angle that cannot be divided by 360 degrees, or the separation claw is a pyramid, The driving means is configured to rotate so that the ridge line of the separation claw contacts the rotating body, the rotating body is configured to be an image carrier, or the rotating body is a toner transferred to the paper. The image forming apparatus includes a fixing roller provided in a fixing device that fixes an image on the paper, and the driving unit drives the separation claw every time an image is formed on the paper. The means may drive the separation claw when the image forming process is performed a predetermined number of times, or the driving means may be a solenoid.

  According to the image forming apparatus of the present invention, since the separation claw is in contact with the rotating body that contacts the paper, and the separation claw is rotated by the driving unit, the separation claw is uniformly worn, so the rotating body An increase in the contact area with the toner can be suppressed, the additive and paper powder are less likely to enter, and the rotating body is less likely to be damaged.

  The separation claw has a separation claw set in which the separation claw located at the contact position with the rotating body and the separation claw located at the position retracted from the rotation body. The drive means moves the separation claw located at the contact position to the withdrawal position. By adopting a configuration in which the separation claw in the retracted position is moved to the contact position, the amount of wear of each separation claw can be reduced and an increase in the contact area can be suppressed. It is hard to get in and scratches on the rotating body are difficult.

  The separation claw has a separation claw set in which the separation claw located at the contact position with the rotating body and the separation claw located at the position retracted from the rotation body. The drive means moves the separation claw located at the contact position to the withdrawal position. By moving the separation claw in the retracted position to the contact position and rotating the separation claw, an increase in the contact surface between the rotating body and the separation claw is further suppressed, and the rotating body is damaged. It becomes difficult.

  Since the separation claw has a conical shape, and the angle of the separation claw that the drive means rotates by one drive is an angle that cannot be divided by 360 degrees, the side surface portion of the cone contacts the rotating body evenly. The increase in the contact area between the rotating body and the separation claw is suppressed, and the rotating body is hardly damaged. Further, the additive and paper dust that adhere when the separation claw comes into contact with the rotating body can be dropped by vibration during rotation or movement.

  The separation claw is a pyramid and the driving means rotates the separation claw so that the ridge line of the separation claw contacts the rotating body, thereby suppressing an increase in the contact area with the rotating body due to wear of the ridge line of the separation claw. As a result, the rotating body is hardly damaged.

  Next, the paper feeding device of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a sheet feeding device of the present invention and an image forming apparatus to which the sheet feeding device is connected. The image forming apparatus 100 is a monochrome digital copier, and includes an image reading unit, an image processing unit (not shown), an image forming unit, a paper feeding unit, a fixing device 180, and a paper discharging unit.

  A document placing plate 101 is provided on the upper part of the image forming apparatus 100, and a document D to be copied is placed thereon. The image reading unit includes an exposure lamp 110 that irradiates the document D, a mirror 111 that moves integrally with the exposure lamp 110, roof mirrors 112 and 113 that move half the moving distance of the mirror 111, an imaging lens 114, and a CCD 115. It is configured. The image reading unit reads the image data by irradiating the document D while the exposure lamp 110 moves, and the reflected light is guided by the two roof mirrors 112 and 113 and the imaging lens 114 and is connected to the CCD 115. Image.

  The image forming unit has an image carrier 102 that is a drum-like rotating body on which a latent image is formed on the surface, and the image carrier 102 is arranged in the order of operation along the outer peripheral surface of the image carrier 102. Toner is transferred to a latent image formed on the surface of the image carrier 102, a charging device 103 that charges the surface substantially uniformly, an exposure unit that writes an electrostatic latent image on the surface of the image carrier 102 A developing device 104 that forms a toner image, a transfer device 105 that transfers the toner image carried by the image carrier 102 to the paper P, and a cleaning device 106 that cleans the surface of the image carrier 102 after the transfer. ing.

  In forming an image, first, the charging device 103 applies a predetermined surface charge to the image carrier 102 by corona discharge. The image data read by the CCD 115 is subjected to necessary processing such as A / D conversion in the image processing unit, and then conveyed to the exposure unit. The digitized image data is superimposed on the laser beam at the exposure unit and scanned by the polygon mirror 116. The scanned laser light is reflected by the roof mirrors 117 and 118, and the surface of the image carrier 102 is exposed through the fθ lens 119, the cylindrical lens 120, and the angle adjustment mirror 121.

  The predetermined surface charge applied to the image carrier 102 is reduced by the exposure of the laser beam according to the exposure amount, and as a result, the electrostatic latent image corresponding to the image information data is converted into the image carrier 102. Formed on top. The electrostatic latent image is visualized by the developer toner supplied from the developing device 104 and becomes a toner image.

  A paper feeding unit including paper feeding units 140, 150, and 160 is disposed below the image forming apparatus 100. The paper feed units 140, 150, and 160 are arranged so as to overlap in the vertical direction, and different sizes of paper P are stored in the paper feed units 140, 150, and 160. Alternatively, different types of paper P may be stored in the form of high-quality paper or glossy paper.

  When the operator inputs an image print command from an operation unit (not shown), the image forming apparatus 100 selects the paper feed units 140, 150, and 160 in which the optimal size paper P is stored. Alternatively, if the operator explicitly specifies a paper feed unit from the operation unit, the image forming apparatus 100 selects the paper feed unit.

  For example, if the sheet P stored in the sheet feeding unit 140 is selected by the image forming apparatus 100, the sheet feeding unit 141 feeds the uppermost sheet P by a frictional force, and the feed roller 143 and the separation unit 142. However, only the uppermost sheet is sent out to the conveyance path 170.

  The sheet P is conveyed on the conveyance path 170 in the direction of the image carrier 102, temporarily stopped by the registration roller 172, and skewing is corrected. After the skew is corrected by the registration roller 172, the toner image is timed and sent between the image carrier 102 and the transfer device 105. In the transfer device 105, the toner image formed on the surface of the image carrier 102 is transferred to the paper P, and is transported to the fixing device 180 by the transport device 173 of the paper P and subjected to fixing processing.

  The fixing device 180 includes a heating roller 181 and a pressure roller 182. The unfixed toner on the paper P is sandwiched in the nip between the heating roller 181 and the pressure roller 182, and is melt-pressed to form a stable toner image on the paper. Form on P. The sheet P that has been fixed is guided by the discharge guide roller 174 and placed on the discharge tray 175.

  A separation claw unit 30 is provided between the transfer device 105 and the cleaning device 106 in the image forming unit. Since the sheet P on which the toner image has been transferred by the transfer device 105 is in contact with the image carrier 102, it is separated from the image carrier 102 by the separation claw unit 30.

  FIG. 2 is an enlarged view around the separation claw unit. The separation claw unit 30 is fixed to the bottom of the cleaning device 106 by an L-shaped fixing member 31. A separation claw 32 and a separation claw holder 33 are provided on the image carrier 102 side of the separation claw unit 30.

  When the contact area between the separation claw 32 and the image carrier 102 is increased, additives and paper powder easily enter the contact surface, which damages the surface of the image carrier 102. A scratch formed on the image carrier 102 causes a defective image. For this reason, it is preferable that the separation claw 32 and the image carrier 102 are made of a material having a high hardness that is resistant to wear, not a surface contact but a line contact. However, in that case, depending on the material of the separation claw 32 such as a metal separation claw, the image carrier 102 may be damaged. For this reason, in this embodiment, the separation claw 32 uses a resin having a high hardness such as polyimide amide, and has a tip formed in a cone.

  The shape of the distal end portion of the separation claw 32 is not limited to a cone, and may be any structure that can make line contact with the image carrier 102, such as a polygonal pyramid such as a triangular pyramid or a quadrangular pyramid.

  The separation claw 32 is provided in the separation claw holder 33 so as to be able to advance and retreat with respect to the image carrier 102 as indicated by an arrow a. The rotating shaft 34 is provided in parallel with the rotating shaft of the image carrier 102, and a plate 35 for advancing and retracting the separation claw 32 is attached. The plate 35 moves as indicated by the arrow b by the rotation of the rotating shaft 34. A plurality of separation claws 32, separation claw holders 33, and plates 35 are provided in a direction parallel to the rotation shaft 34 of the image carrier 102.

  When the leading end of the sheet P passes through the transfer device 105, the rotation shaft 34 is rotated clockwise in the drawing by a driving unit such as a solenoid (not shown). The plate 35 provided on the rotating shaft 34 also moves clockwise and pushes the rear end portion of the separation claw 32 protruding from the separation claw holder 33. Then, the separation claw 32 moves forward, and the tip comes into contact with the image carrier 102. At this time, as will be described later, the separation claw 32 rotates slightly around its axis.

  The sheet P stuck to the image carrier 102 is separated from the image carrier 102 by the separation claw 32 in contact with the image carrier 102.

  When the leading end portion of the paper P is separated, the driving unit rotates the rotary shaft 34 in the opposite direction, that is, counterclockwise. As a result, the plate 35 is separated from the rear end of the separation claw 32, and the separation claw 32 is retracted by the coil spring in the separation claw holder 33 and separated from the image carrier 102.

  FIG. 3 is a view showing a structure inside the separation claw holder. The separation claw holder 33 is hollow, and the separation claw 32 is inserted therethrough. The separation claw 32 has a flange 36, and a coil spring 37 is provided between the flange 36 and the inner wall of the separation claw holder 33. Further, a saw-tooth joint 38 made up of face ratchets 38a and 38b is provided on the rear end side of the separation claw 32. The face ratchets 38a and 38b are both cylindrical, and the separation claw 32 is inserted therethrough. The face ratchet 38 a is fixed to a protrusion 39 provided in the separation claw holder 33, and the face ratchet 38 b is fixed to the separation claw 32. Further, it is urged to rotate by a spring (not shown), and can be rotated by one pitch of the teeth of the face ratchet 38a, 38b.

  When the plate 35 pushes the rear end of the separation claw 32, the separation claw 32 moves forward. As the separation claw 32 moves forward, the coil spring 37 is compressed, and at the same time, the face ratchet 38b fixed to the separation claw 32 approaches the face ratchet 38a. When the teeth of the face ratchet 38b hit the teeth of the face ratchet 38a, the face ratchet 38b moves along the teeth of the face ratchet 38a, and the separation claw 32 rotates accordingly. When the plate 35 is separated from the separation claw 32, the separation claw 32 is retracted by the coil spring 37 and returns to the state shown in FIG. At this time, the face ratchet 38b is rotated by one pitch by a spring or the like (not shown). As a result, the meshing of the face ratchets 38 a and 38 b is shifted, and the separation claw 32 can be rotated also when the separation claw 32 comes into contact with the image carrier 102 next time.

  In this way, the separation claw 32 changes its contact position every time it comes into contact with the image carrier 102, so that the tip of the separation claw 32 is less worn. The rotation angle of the separation claw 32 can be changed according to the number of teeth of the face ratchets 38a and 38b. As the number of teeth decreases, the rotation angle increases, and as the number of teeth increases, the rotation angle decreases.

  When the tip of the separation claw 32 is a polygonal pyramid such as a quadrangular pyramid, the number of teeth is set so that the ridge line portion is always in contact with the image carrier 102. For example, in the case of a quadrangular pyramid, the rotation angle is set to 90 degrees.

  FIG. 4 is an enlarged view around the separation claw unit according to the second embodiment of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals, and differences from the first embodiment will be mainly described.

  The separation claw 32 is formed of polyimide amide or the like as in the first embodiment, and the tip has a shape such as a cone or a polygonal pyramid. The separation claw 32 is inserted into the separation claw holder 33, and the rear end of the separation claw 32 is fixed to a rotating member 40 having a built-in one-way clutch.

  The rotating member 40 is provided with a rotating plate 41 for rotating the separation claw 32. The rotation plate 41 is configured not to rotate more than a predetermined angle by a stopper or the like (not shown), and this angle becomes the rotation angle of the separation claw 32. The release plate 42 is attached to the rotary shaft 34 and is used to release the contact of the separation claw 32 with the image carrier 102. The release plate 42 contacts the lower surface of the rotary plate 41 as the rotary shaft 34 rotates. .

  The separation claw holder 33 is attached to a shaft 43 provided in parallel to the rotation axis direction of the image carrier 102 so as to be rotatable. A torsion spring 44 is provided between the separation claw holder 33 and the rotation member 40.

  FIG. 5 is a perspective view showing the structure of the separation claw unit of the second embodiment of the present invention. When the rotating shaft 34 is rotated in the direction of arrow c by a driving means such as a solenoid (not shown), the distal end portion of the release plate 42 is lifted up and engaged with the rotating plate 41. By continuing to lift after the contact, the rotating plate 41 also rises and the rotating member 40 rotates. The separation claw 32 fixed to the rotation member 40 is rotated in the direction indicated by the arrow d by the rotation of the rotation member 40. The release plate 42 continues to lift the rotation plate 41 even after the rotation plate 41 is rotated to a predetermined angle. Therefore, the separation claw holder 33 rotates about the shaft 43, and the tip end portion of the separation claw 32 moves downward to be released from the image carrier 102.

  If the tip of the separation claw 32 is a cone, the predetermined rotation angle of the rotating plate 41 can be set to a value that cannot be divided into 360 degrees, such as 7 degrees or 11 degrees. By doing so, since the side surface portion of the cone is in contact with the image carrier 102 evenly, the separation claw 32 is evenly worn and the contact area with the image carrier 102 does not increase, so that paper dust or the like does not easily enter. Therefore, the image carrier 102 is hardly damaged.

  When the rotating shaft 34 rotates in the direction opposite to the arrow c, the engagement between the release plate 42 and the rotation plate 41 is released. Thereby, the separation claw holder 33 returns to the position shown in FIG. 5, and the tip of the separation claw 32 comes into contact with the image carrier 102. At the same time, the rotating member 40 is returned to the original position by the torsion spring 44. Since there is a one-way clutch between the rotation member 40 and the separation claw 32, the separation claw 32 does not rotate when the rotation member 40 returns to the original position.

  FIG. 6 is a side view showing the structure of the third embodiment of the present invention, and FIG. 7 is a top view of the third embodiment of the present invention. The separation claw holder 33 is attached to the shaft 43 in a rotatable state, and the separation claw 32 is inserted therethrough. There is a protrusion 45 at the lower part of the separation claw holder 33, and the release plate 42 contacts. The release plate 42 is brought into contact with the protrusion 45 by driving means (not shown), and the rear portion of the separation claw holder 33 is lifted, so that the separation claw holder 33 rotates about the shaft 43 and the tip of the separation claw 32 is moved downward. It moves and leaves the image carrier 102.

  As shown in FIG. 7, two separation claws 32 communicate with one separation claw holder 33 to constitute a separation claw set. A displacement cam 47 supports the rear end portion 46 of the separation claw 32. The displacement cam 47 is fixed to a shaft 49 via a link mechanism 48, and the shaft 49 is moved in the left-right direction as indicated by an arrow by a driving means such as a solenoid (not shown).

  In FIG. 7, the left separation claw 32 is in a position where it abuts against the image carrier 102, and the right separation claw 32 is in a retracted position where it does not abut. When the shaft 49 moves to the right in this state, the displacement cam 47 also moves to the right. Then, the right separation claw 32 moves forward and moves to a contact position where it comes into contact with the image carrier 102, and the left separation claw 32 moves backward by the coil spring 50 and moves to a retreat position where it does not contact the image carrier 102. Such an operation is performed every time the image forming process is performed once.

  A configuration in which the saw-tooth joint of the first embodiment is provided in the separation claw holder 33 of the third embodiment or a rotation member of the second embodiment is also possible. By doing so, the separation claw 32 rotates each time the separation claw 32 moves to the contact position, so that the tip part of the separation claw 32 is less worn and the additive and paper powder are less likely to enter. The carrier 102 is not easily damaged.

  In the present invention, the separation claw is provided not only on the image carrier 102 but also on a rotating body that requires separation of the paper P, such as the heating roller 181 of the fixing device 180 and the intermediate transfer member of the color image forming apparatus. It is possible.

  Further, in the first to third embodiments, the separation claw 32 is rotated each time image formation is performed, but the separation claw 32 is rotated when the image forming process is performed a predetermined number of times. It may be.

1 is a diagram illustrating a configuration of a sheet feeding device of the present invention and an image forming apparatus to which the sheet feeding device is connected. FIG. It is an enlarged view around a separation claw unit. It is a figure which shows the structure inside a separation claw holder. It is an enlarged view of the separation claw unit periphery of the second embodiment of the present invention. It is a perspective view which shows the structure of the separation nail | claw unit of 2nd Example of this invention. It is a side view which shows the structure of 3rd Example of this invention. It is a top view of 3rd Example of this invention.

Explanation of symbols

32 Separation claw 100 Image forming apparatus 102 Image carrier 180 Fixing apparatus 181 Heating roller P Paper

Claims (10)

A rotating body in contact with the paper,
A separation claw for separating the paper from the rotating body;
An image forming apparatus comprising: a driving unit configured to rotate the separation claw; A rotating body in contact with the paper,
A separation claw for separating the paper from the rotating body;
A separation claw set having the separation claw at a position that contacts the rotating body, and a separation claw set having the separation claw at a retracted position that does not contact the rotating body;
Drive means for moving the separation claw in the contact position to the retreat position and moving the separation claw in the retraction position to the contact position among the separation claws of the separation claw set. An image forming apparatus. The image forming apparatus includes a separation claw set having the separation claw at a position in contact with the rotating body and the separation claw at a retracted position not in contact with the rotating body,
The drive means moves the separation claw in the contact position to the retreat position among the separation claws of the separation claw set, moves the separation claw in the retraction position to the contact position, and the separation claw The image forming apparatus according to claim 1, wherein the image forming apparatus is rotated. The separation claw is a cone;
The image forming apparatus according to claim 1, wherein an angle at which the driving unit rotates the separation claw by one driving is an angle that cannot be divided by 360 degrees. The separation claw is a pyramid;
The image forming apparatus according to claim 1, wherein the driving unit rotates the ridge line of the separation claw so that the ridge line contacts the rotating body.   The image forming apparatus according to claim 1, wherein the rotating body is an image carrier.   The image forming apparatus according to claim 1, wherein the rotating body is a fixing roller provided in a fixing device that fixes the toner image transferred onto the sheet to the sheet.   The image forming apparatus according to claim 1, wherein the driving unit drives the separation claw every time an image is formed on the paper.   The image forming apparatus according to claim 1, wherein the driving unit drives the separation claw when an image forming process is performed a predetermined number of times.   The image forming apparatus according to claim 1, wherein the driving unit is a solenoid.

Images