JP6544113B2 - Image forming device - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus.

  For example, in the image forming apparatus described in Patent Document 1, the sheet conveyance direction is switched by swinging and displacing a sheet guide portion such as a switching guide.

JP 2007-106544 A

When an image is formed on a sheet coated with a sticking adhesive on the back surface of a label sheet, tack sheet or the like, an electrophotographic image forming apparatus is likely to cause conveyance failure of the sheet.
That is, in the electrophotographic image forming apparatus, the developer transferred onto the sheet is pressurized while being heated by the fixing device, so that the adhesive coated on the back side may sometimes protrude from the end of the sheet. When the sticking out adhesive is solidified in a spherical shape and adheres to the sheet guiding portion, the lump of the adhesive becomes an obstacle to sheet conveyance, and easily causes sheet conveyance failure.

  An object of the present invention is to suppress the occurrence of sheet conveyance failure due to adhesion of an adhesive to a sheet guide portion in an electrophotographic image forming apparatus.

  In the present application, an electrophotographic image forming section (5) having a fixing device (5B) for heating and pressing a developer transferred onto a sheet, and a case (3) for housing the image forming section (5) A movable guide (21) for guiding conveyance of the sheet discharged from the image forming unit (5), the first position for guiding the sheet in the first conveyance direction, and the second for guiding the sheet in the second conveyance direction A movable guide (21) displaceable between two positions and a fixed guide (23) immovable relative to the housing (3), wherein the movable guide (21) guides in the first transport direction And a fixed guide (23) for guiding the conveyance of the sheet conveyed and conveyed, and extends from the movable guide (21) toward the fixed guide (23) and integrally with the movable guide (21) A displaceable cover portion (25) for transporting at least a part of the fixed guide portion (23) Comprising covering portion for covering the sheet side to the (25).

  That is, the above-described “sheet conveyance failure” is likely to occur when the sheet guiding portion is configured by “a plurality of protrusions (rib-like protrusions) extending in the sheet conveyance direction”. This is because the rib-like protrusion has a small contact surface with the sheet, and the sticking out adhesive is likely to be spherically solidified.

  And in the present invention, “extends from the movable guide portion (21) toward the fixed guide portion (23), displaces integrally with the movable guide portion (21), and at least one of the fixed guide portions (23) A cover (25) for covering the sheet from the side of the sheet to be conveyed.

  For this reason, in the portion (hereinafter referred to as a connecting portion) in the sheet transport path where the movable guiding portion (21) is changed to the fixed guiding portion (23), the cover portion (25) is a sheet relative to the fixed guiding portion (23). It becomes a "step shape" located on the side.

  That is, the above-mentioned "step shape" is a fixed guiding portion in the conveying direction of the sheet conveyed in the first conveying direction, that is, the sheet conveyed from the movable guiding portion (21) side toward the fixed guiding portion (23) side. (23) The side has a step shape separated from the “sheet to be conveyed” by the cover portion (25).

  For this reason, since the above-mentioned "step difference shape" does not become a wall (scissors) which obstructs conveyance of a sheet, the area of the part of the cover (25) facing the sheet to be conveyed (hereinafter, the area of the cover (25) Even if the size of the sheet is increased, there is no hindrance to sheet conveyance.

  Therefore, in the present invention, since the area of the cover portion (25) can be increased, it is possible to suppress that the sticking out adhesive is solidified in a spherical shape. As a result, in the electrophotographic image forming apparatus, it is possible to suppress the occurrence of sheet conveyance failure due to the adhesive adhering to the sheet guide portion.

  Incidentally, the reference numerals in the parentheses of the respective means and the like are an example showing the correspondence with the specific configuration and the like described in the embodiments described later, and the present invention is shown by the reference numerals in the parentheses of the respective means and the like It is not limited to the specific configuration.

FIG. 1 is a schematic view of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 3 is a detailed cross-sectional view of the movable guide portion 21 and the fixed guide portion 23 and the like in the image forming apparatus 1 according to the embodiment of the present invention. FIG. 3 is a detailed cross-sectional view of the movable guide portion 21 and the fixed guide portion 23 and the like in the image forming apparatus 1 according to the embodiment of the present invention. FIG. 3 is a detailed perspective view of the movable guide portion 21 and the fixed guide portion 23 and the like in the image forming apparatus 1 according to the embodiment of the present invention. FIG. 3 is a detailed cross-sectional view of the movable guide portion 21 and the fixed guide portion 23 and the like in the image forming apparatus 1 according to the embodiment of the present invention. It is a perspective view of top cover 3B grade | etc.,. FIG. 2 is a front view of the movable guide portion 21 in the image forming apparatus 1 according to the embodiment of the present invention. FIG. 2 is a control system block diagram of the image forming apparatus 1 according to the embodiment of the present invention.

  The “invention embodiment” described below shows an example of the embodiment. That is, the invention-specifying matters and the like described in the claims are not limited to the specific means and the structures and the like shown in the following embodiments.

  In the present embodiment, as shown in FIG. 1, the present invention is applied to an image forming apparatus 1 having a first discharge unit 3A and a second discharge unit 10. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In addition, the arrow etc. which show the direction attached to each figure are described in order to make it easy to understand the relationship of each figure. The present invention is not limited to the directions given in the respective drawings. At least one member or part described with at least the reference numeral is provided except in the case where “plurality”, “two or more”, etc. are described.

First Embodiment
1. Overview of image forming apparatus (see FIG. 1)
The second discharge unit 10 according to the present embodiment is attached to the image forming apparatus 1 vertically above the discharge port 2. An electrophotographic image forming unit 5 is accommodated in a housing 3 on the lower side in the vertical direction with respect to the second discharge unit 10 and the discharge port 2.

  The image forming unit 5 includes a transfer unit 5A, a fixing unit 5B, and the like, and forms an image on a sheet. The transfer device 5A includes a process unit 5C, a photosensitive drum 5D, a transfer roller 5E, and the like, and transfers the developer onto the sheet. The fixing device 5B includes a heating roller 5F and a pressure roller 5G, and applies pressure while heating the developer.

  On the upper surface side in the vertical direction of the housing 3 and below the second discharge unit 10 in the vertical direction, a main body discharge tray that constitutes the first discharge unit 3A is provided. A sheet on which an image is formed is placed on the main body discharge tray, that is, the first discharge unit 3A.

  The first discharge unit 3A is a portion from which the sheet is discharged when the second discharge unit 10 does not operate. When the second discharge unit 10 operates, the sheet is discharged to at least one paper discharge tray among the plurality of paper discharge trays 11 to 13.

  The second discharge unit 10 has a plurality of paper discharge trays 11 to 13. The plurality of sheet discharge trays 11 to 13 are arranged in the vertical direction. The second discharge unit 10 discharges the sheet to any one of the plurality of paper discharge trays 11 to 13 in accordance with the discharge setting previously set by the user.

  The switching flappers 14A and 14B are sheet guiding portions for guiding a sheet to any one of the paper discharge trays 11 to 13. The stack sensors 14C to 14E are movable bodies for detecting the number of sheets (stacking height) discharged to the sheet discharge trays 11 to 13.

  A movable guide portion 21 and a fixed guide portion 23 are provided on the sheet conveyance path in the housing 3 and on the downstream side of the fixing device 5B in the sheet conveyance direction. The movable guide unit 21 guides the conveyance of the sheet discharged from the image forming unit 5. The movable guide portion 21 can be displaced between a first position (see FIG. 2) for guiding the sheet in the first transport direction D1 and a second position (see FIG. 3) for guiding the sheet in the second transport direction D2. It is.

  The fixed guiding unit 23 is stationary with respect to the housing 3 and guides the conveyance of the sheet guided and conveyed in the first conveying direction D1 by the movable guiding unit 21. That is, the first conveyance direction D1 according to the present embodiment is a direction from the fixing device 5B toward the first discharge portion 3A via the movable guide portion 21 and the fixed guide portion 23.

  The second conveyance direction D2 according to the present embodiment is a direction from the fixing device 5B toward the second discharge unit 10 via the movable guide unit 21. That is, the second discharge unit 10 is provided downstream of the movable guide unit 21 in the second conveyance direction.

2. Details of Movable Guide Portion, Fixed Guide Portion, etc. As shown in FIG. 2, a cover 25 is provided at the first transport direction forward end of the movable guide 21, that is, at the end of the movable guide 21 at the fixed guide 23 side. Is provided. The cover 25 is a portion extending from the end toward the fixed guide 23.

  The cover 25 is displaced integrally with the movable guide 21 and covers at least a part of the fixed guide 23 from the side of the sheet to be conveyed when the sheet is conveyed in the direction of the first conveyance direction D1. “Cover from the side of the sheet to be conveyed” means to “cover from the side of the fixed guide 23 facing the sheet to be conveyed (in the present embodiment, from the lower side in the vertical direction)”.

  As shown in FIG. 4, the fixed guide portion 23 according to the present embodiment is configured to have a plurality of strip members 23A. As shown in FIG. 5, each of the belt-like members 23A is a belt-like member in which a portion facing the sheet to be conveyed extends along the first conveyance direction D1.

  In the present embodiment, the width dimensions of the respective strip members 23A are not the same. Specifically, the width dimension of the strip-shaped members 23A on the width direction both end sides of the sheet to be conveyed is smaller than the width dimension of the other strip-shaped members 23A. The width direction refers to a direction (horizontal direction in the present embodiment) orthogonal to the conveyance direction and the thickness direction of the sheet to be conveyed.

  Each band-shaped member 23A according to the present embodiment, that is, the fixed guide portion 23, is formed as a separate component from the top cover 3B of the housing 3 as shown in FIG. Integrated into 3.

  That is, the fixed guide portion 23 is made of resin different from the housing 3. Specifically, at least a portion of the fixed guide 23 in contact with the sheet is made of fluorocarbon resin or polyacetal (POM). The top cover 3B is made of acrylonitrile butadiene styrene (ABS).

  As shown in FIG. 6, the top cover 3B has a plurality of ribs 3C formed in a wall plate shape. The ribs 3C are integrally formed with the top cover 3B. As shown in FIG. 4, each strip member 23A is inserted between adjacent ribs 3C and fixed to the top cover 3B by an elastic locking portion such as a snap fit.

  As shown in FIG. 5, the cover 25 is configured to have a plurality of extending parts 25A. The extension portions 25A extend from the movable guide portion 21 toward the strip members 23A. A plurality of movable guides 21 are provided, and the movable guides 21 are arranged in series in the width direction.

  That is, the plurality of strip members 23A and the plurality of extending portions 25A are arranged in parallel with respect to the first conveyance direction D1. Further, the covering portion 25 covers the fixed guiding portion 23 such that each of the plurality of extending portions 25A overlaps with each of the plurality of strip members 23A. For this reason, in the present embodiment, the number of extending portions 25A corresponds to the number of strip members 23A.

  In the present embodiment, as shown in FIG. 7, the plurality of strip members 23A and the plurality of extension portions 25A are integrally formed of resin (in the present embodiment, ABS) and integrated. Therefore, the plurality of strip members 23A are swung and displaced about the central axis L1 by one actuator 31 (see FIG. 8).

  As shown in FIG. 1, a pair of switchback rollers 27 is provided on the side of the fixed guide 23 from the end of the cover 25, that is, on the side of the sheet discharge outlet 2. The pair of switchback rollers 27 are rollers for feeding the sheet on which the image is formed on one surface in the reverse direction of the sheet conveyance direction to the re-conveying path L2.

  The re-conveying path L2 is a sheet conveying path for guiding the sheet discharged from the image forming unit 5 to the entrance side of the image forming unit 5 again. That is, the sheet placed on the sheet feeding tray 6 is fed to the pair of registration rollers 7 by the pickup roller 6A.

  The pair of registration rollers 7 sends the sheet to the image forming unit 5 at a preset timing after adjusting the attitude of the sheet. The sheet conveyed via the re-conveying path L2 is also sent to the image forming unit 5 after its posture is adjusted by the pair of registration rollers 7.

  A trailing end detection unit 32 is provided on the exit side of the fixing device 5B. The rear end detection unit 32 detects whether the rear end of the fixed guiding unit 23, that is, the conveyance direction rear end of the sheet conveyed to the first discharge unit 3 </ b> A has passed through the rear end detection unit 32.

  As shown in FIG. 8, a rotational force is supplied from an electric motor to the switchback roller 27 and the like. The control unit 30 controls the rotation of the switchback roller 27, that is, the rotation of the electric motor. The control unit 30 controls the rotation direction of the switchback roller 27 (electric motor) using the detection result of the rear end detection unit 32.

  Specifically, when forming an image on both the front and back sides of the sheet, the control unit 30 first sets the movable guide portion 21 in the state shown in FIG. 3 and then rotates the electric motor to rotate the sheet. The sheet is conveyed in the direction from the forming unit 5 to the sheet discharge outlet 2.

  Next, the control unit 30 reverses the electric motor when a preset time has elapsed from the time when the rear end detection unit 32 detects the rear end of the sheet in which the image is formed on the front side in the conveyance direction. Thus, the transport direction of the sheet transported in the first transport direction D1 is reversed before the rear end in the transport direction passes the front end of the cover 25.

  Then, when the sheet on which the image is formed on the back surface is discharged to the first discharge unit 3A, the control unit 30 maintains the movable guide unit 21 in the state illustrated in FIG. When the sheet on which the image is formed on the back surface is discharged to the second discharge unit 10, the control unit 30 displaces the movable guide unit 21 to the state shown in FIG.

3. Characteristics of the image forming apparatus according to the present embodiment The “sheet conveyance failure” by the adhesive for sticking is the sheet guide portion “a plurality of protrusions (rib-like protrusions) extending along the sheet conveyance direction”. It is easy to occur when it is configured. This is because the rib-like protrusion has a small contact surface with the sheet, and the sticking out adhesive is likely to be spherically solidified.

  In the present embodiment, “the sheet side which extends from the movable guide 21 toward the fixed guide 23, is displaced integrally with the movable guide 21, and at least a part of the fixed guide 23 is conveyed. Is provided with a cover 25 ".

  Therefore, in the portion of the sheet conveyance path where the movable guide portion 21 is changed to the fixed guide portion 23 (hereinafter referred to as a connecting portion), the “step shape” in which the cover 25 is positioned on the sheet side with respect to the fixed guide portion 23 It becomes.

  That is, in the “step shape”, the fixed guiding portion 23 side covers the sheet conveyed in the first conveying direction D1, that is, the sheet conveyed from the movable guiding portion 21 side to the fixed guiding portion 23 side. The step shape is such that the sheet is separated from the sheet conveyed by the unit 25.

  For this reason, since the above-mentioned "step difference shape" does not become a wall (堰) which obstructs conveyance of a sheet, the area (henceforth the area of cover 25) of a portion of cover 25 facing the sheet to be conveyed is mentioned. Even if it is larger, it does not hinder the sheet conveyance.

  Therefore, in the present embodiment, since the area of the cover 25 can be increased, it is possible to suppress that the sticking out adhesive is solidified in a spherical shape. As a result, in the electrophotographic image forming apparatus 1, it is possible to suppress the occurrence of sheet conveyance failure due to the adhesive adhering to the sheet guide portion.

  By the way, provisionally, each of the movable guide portion and the fixed guide portion has a comb-tooth shape configured by a plurality of protrusions, and the above-mentioned "connection portion" has the "protrusions of the movable guide portion and the protrusions of the fixed guide portion In the configuration in which they are alternately arranged, a large gap is generated between the ridges of the movable guide and the ridges of the fixed guide.

For this reason, with the above configuration, there is a possibility that the end portion of the sheet fits into the gap when the sheet passes through the connecting portion, and therefore, there is a high possibility that the sheet conveyance failure occurs.
On the other hand, in the present embodiment, since the cover portion 25 is provided, the end portion of the sheet can be prevented from being fitted into the gap. Therefore, it is possible to suppress the occurrence of the sheet conveyance failure at the connecting portion.

  Furthermore, in the present embodiment, at the time of double-sided printing, the sheet in which the image is formed on the front side is reversed in the sheet conveyance direction before the rear end in the conveyance direction passes the front end of the cover 25. As a result, at the time of double-sided printing, it is possible to suppress the occurrence of sheet conveyance failure at the connecting portion.

(Other embodiments)
In the above-mentioned embodiment, although covering part 25 was constituted having a plurality of extension parts 25A, the present invention is not limited to this, for example, one strip plate shape which is extended in the cross direction Cover part 25 may be constituted by a part.

  Although fixed guide part 23 concerning the above-mentioned embodiment was constituted having a plurality of strip members 23A, the present invention is not limited to this, and one strip plate member which extends in the width direction The fixed guiding unit 23 may be configured in the following manner.

  The fixed guide portion 23 according to the above-described embodiment is formed as a separate component from the top cover 3B of the housing 3 and then assembled and fixed to the top cover 3B to be integrated with the housing 3. It is not limited to this.

  That is, for example, the top cover 3B and the fixed guide portion 23 may be integrally molded. That is, if the area of the portion of the fixed guide 23 in contact with the sheet is increased, it is possible to suppress the occurrence of the “sheet conveyance failure” due to the sticking adhesive.

  In the embodiment described above, a plurality of movable guide portions 21 are provided, and the movable guide portions 21 are arranged in series in the width direction, and each of the plurality of extension portions 25A is a plurality of strip members 23A. Although the cover part 25 has covered the fixed guide part 23 so that it may overlap, this invention is not limited to this.

  In the above embodiment, the present invention is applied to the image forming apparatus 1 having the switchback roller 27, that is, the image forming apparatus 1 capable of double-sided printing, but the application of the present invention is not limited to this.

  Although the direction of rotation of the switchback roller 27 (electric motor) is controlled using the detection result of the rear end detection unit 32 in the above embodiment, the present invention is not limited to this. That is, for example, after the rotation of the pair of registration rollers 7 is stopped, the direction of rotation of the switchback roller 27 (electric motor) on the basis of the time when the rotation is resumed, that is, the sheet is fed into the image forming unit 5 May be controlled.

  In the above-described embodiment, the first discharge unit 3A is provided on the downstream side in the first conveyance direction D1, and the second discharge unit 10 is provided on the downstream side in the second conveyance direction D2. It is not limited to this.

  Furthermore, the present invention is not limited to the above-described embodiment as long as it conforms to the spirit of the invention described in the claims.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 2 ... Ejection slot 3A ... 1st discharge part 3 ... Case 3B ... Top cover 3C ... Rib 5 ... Image formation part 5A ... Transfer device 5C ... Process unit 5D ... Photosensitive drum 5B ... Fixing device 5F ... Heating roller 5G ... Pressure roller 6 ... Feeding tray 6A ... Pickup roller 7 ... Registration roller 10 ... Second discharge section 21 ... Movable guiding section 23 ... Fixed guiding section 23A ... Band member 25 ... Covering section 25A ... Extension section 27 ... switch back roller 30 ... control unit 31 ... actuator 32 ... rear end detection unit

Claims (8)

An electrophotographic image forming unit having a fixing unit that applies pressure while heating the developer transferred onto a sheet;
A housing for housing the image forming unit;
A movable guide unit for guiding conveyance of the sheet discharged from the image forming unit, between a first position for guiding the sheet in the first conveyance direction and a second position for guiding the sheet in the second conveyance direction. A displaceable movable guide,
A fixed guiding unit immovable with respect to the housing, the fixed guiding unit guiding the conveyance of the sheet guided and conveyed in the first conveyance direction by the movable guidance unit;
A covering portion extending from the movable guiding portion toward the fixed guiding portion and displaced integrally with the movable guiding portion, the covering portion covering at least a part of the fixed guiding portion from the side of the sheet to be conveyed Equipped with and
The fixed guiding unit is configured by including a plurality of strip members in which a portion facing the sheet to be conveyed extends along the first conveying direction.
The cover portion is configured to have a plurality of extension portions extending from the movable guide portion toward the respective strip-shaped members,
Further, the plurality of strip members and the plurality of extension portions are arranged in parallel with respect to the first conveyance direction . Wherein the plurality of such extension portion respectively overlap to each of the plurality of belt-shaped member, the image forming apparatus according to claim 1, wherein the cover portion is characterized in that it covers the fixed guide portion. A switchback roller configured to reverse a conveying direction of a sheet having an image formed on one side thereof, the switchback roller being provided on a side of the fixed guide portion from a tip end of the cover portion;
A rear end detection unit provided on the exit side of the fixing unit and detecting whether or not the rear end in the sheet conveyance direction conveyed to the fixed guide side has passed;
The control unit controls the rotation of the switchback roller using the detection result of the rear end detection unit, and reverses the sheet conveyance direction before the rear end of the sheet conveyance direction passes through the front end of the cover unit. the image forming apparatus according to claim 1 or claim 2, characterized in that a control unit. The image forming apparatus according to any one of claims 1 to 3 , wherein the fixed guide portion is made of a resin different from the case. 5. The image forming apparatus according to claim 4 , wherein at least a portion of the fixed guide portion in contact with the sheet is made of a fluorocarbon resin. 5. The image forming apparatus according to claim 4 , wherein at least a portion of the fixed guide portion in contact with the sheet is made of polyacetal. A first paper discharge unit provided downstream of the fixed guide unit in the sheet conveyance direction and on which the sheet on which an image is formed is placed;
A plurality of paper discharge trays provided on the downstream side of the second transport direction, in which a plurality of paper discharge trays on which the sheet on which an image is formed is placed are arranged in the vertical direction; 7. An image forming apparatus according to any one of items 1 to 6 . Wherein the housing, an image forming apparatus according to claim 5 or 6, characterized in that it is made of acrylonitrile butadiene styrene.