JP2013237498A - Sheet transport device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a noise occurring when a detection lever returns to its original posture after a sheet passes therethrough, from a posture changed by the sheet transported thereto to push the same, with respect to a sheet transport device and an image forming apparatus.SOLUTION: When a detection nail 312 returns to a first posture after a sheet passes therethrough, from a second posture changed by a sheet pushing the same, the detection nail 312 and a light shielding plate 313 linked thereto by a shaft 311 return to a third posture from a fourth posture, for the light shielding plate 313 to hit a receiving member 330. A noise generated when the light shielding plate 313 hits the receiving member can be reduced by forming the receiving member 330 in a cantilevered shape to reduce its rigidity.

Description

  The present invention relates to a sheet conveying device and an image forming apparatus.

  A paper conveyance device that conveys a sheet includes a detection lever that changes its attitude when pressed by a sheet passing through a conveyance path, and detects the passage of the sheet by detecting a change in the attitude of the detection lever with an optical sensor. Detection structures are known (see Patent Documents 1, 2, and 3).

Japanese Patent Laid-Open No. 11-343048 JP 2005-096902 A JP 2007-297141 A

  An object of the present invention is to reduce a sound when a detection lever is pushed by a conveyed sheet and the posture is changed, and then the sheet passes and returns to the original posture.

Claim 1 includes a transport unit that transports the paper and a detection member that detects that the paper has been transported, and the detection member includes:
A first member that changes the posture between a first posture that is in non-contact with the paper and a second posture that rotates in contact with the conveyed paper, and a third posture corresponding to the first posture A second member that changes the posture between the first posture and the fourth posture corresponding to the second posture, and a connecting member that connects the first member and the second member to change the posture of the first member and the second member. A detection member that receives force in a direction in which the first member and the second member are in the first posture and the third posture, respectively, in a state where the first member is not in contact with the paper,
A detector for detecting whether the second member is in the third posture or the fourth posture;
A structure that weakens the rigidity with respect to the abutting of the second member, which receives the abutting of the second member that has changed from the fourth attitude to the third attitude and maintains the second member in the third attitude. A sheet transporting device comprising a receiving member.

  According to a second aspect of the present invention, in the paper conveying apparatus according to the first aspect, the receiving member has a cantilever shape in which grooves are formed on both sides.

  According to a third aspect of the present invention, in the paper conveying apparatus according to the first aspect, the receiving member includes a contact member that contacts the second member and a spring member that supports the contact member.

  According to a fourth aspect of the present invention, in the paper conveying apparatus according to the first aspect, the receiving member has a relatively soft elastic body on the relatively hard receiving surface and contacting the second member. And

Claim 5
A transport unit for transporting paper;
An image forming unit that transfers the toner image onto a sheet that has been conveyed by forming a toner image;
A fixing unit that is disposed downstream of the image forming unit in the sheet conveyance direction, heats and pressurizes the sheet that is further conveyed after receiving the transfer of the toner image, and fixes the toner image on the sheet;
A detection unit that is disposed downstream of the fixing unit in the sheet conveyance direction and detects that the sheet has been conveyed;
The detection unit is
A first member that changes the posture between a first posture that is in non-contact with the paper and a second posture that rotates in contact with the conveyed paper, and a third posture corresponding to the first posture A second member that changes the posture between the first posture and the fourth posture corresponding to the second posture, and a connecting member that connects the first member and the second member to change the posture of the first member and the second member. A detection member that receives force in a direction in which the first member and the second member are in the first posture and the third posture, respectively, in a state where the first member is not in contact with the paper,
A detector for detecting whether the second member is in the third posture or the fourth posture;
A structure that weakens the rigidity with respect to the abutting of the second member that receives the abutting of the second member that has changed from the fourth attitude to the third attitude and maintains the second member in the third attitude. An image forming apparatus including a receiving member.

  According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect, a heat shield member that is spaced apart from the receiving member and is disposed at a position closer to the fixing unit than the receiving member, blocks heat transmitted from the fixing unit to the receiving member. It is characterized by having.

  According to the sheet conveying device of the first aspect and the image forming apparatus of the fifth aspect, the sound when the second member hits the receiving member is reduced.

  According to the sheet conveying apparatus of the second aspect, it is possible to reduce the sound without adding another member.

  According to the paper transport device of the third and fourth aspects, the sound reduction effect is further enhanced.

  According to the image forming apparatus of the sixth aspect, the life of the detector can be extended.

1 is a schematic configuration diagram of a copying machine as an embodiment of the present invention. FIG. 2 is a cross-sectional view of a fixing device and a discharge device in the copying machine shown in FIG. 1. It is an external appearance perspective view of the discharger which showed the outline in FIG. It is an external appearance perspective view of the discharger which showed the outline in FIG. It is the perspective view which removed the upper frame and the discharge roll of the discharger, and showed the lower frame and the detector. FIG. 6 is an enlarged view of a portion in the vicinity of the photoelectric sensor in FIG. 5. It is sectional drawing of the part of a detection nail | claw when a detection member exists in the attitude | position shown in FIG. 5, FIG. It is sectional drawing of the part of a light-shielding plate when a detection member exists in the attitude | position shown in FIG. 5, FIG. It is the perspective view which showed the lower frame and the detector. FIG. 10 is an enlarged view of a portion in the vicinity of the photoelectric sensor in FIG. 9. It is sectional drawing of the part of a detection nail | claw when a detection member exists in the attitude | position shown in FIG. 9, FIG. It is sectional drawing of the part of a light-shielding plate when a detection member exists in the attitude | position shown in FIG. 9, FIG. FIG. 4 is an enlarged view showing only the lower frame of the lower frame in the vicinity of the photoelectric sensor, with the photoelectric sensor and the like removed. FIG. 5 is a cross-sectional view of the lower frame corresponding to the detection claw and showing only the lower frame with the detection claw and the like removed. It is a figure which shows the 1st modification of a receiving member. It is a figure which shows the 2nd modification of a receiving member.

  Embodiments of the present invention will be described below.

  FIG. 1 is a schematic configuration diagram of a copying machine as an embodiment of the present invention.

  The copying machine shown in FIG. 1 incorporates an image forming apparatus as an embodiment of the present invention and a paper conveying apparatus as an embodiment of the present invention.

  The copying machine 1 includes a document reading device 10 and an image forming device 20. The document reading apparatus 10 is installed on the image forming apparatus 20 with a frame 30 spaced from the image forming apparatus 20.

  The document reading device 10 is provided with a document sheet tray 11 on which documents S are stacked. The documents S placed on the document sheet tray 11 are sent out one by one and are transported on a transport path (not shown) inside the document reader 10. In the course of the conveyance, characters and images recorded on the conveyed document are read by the document reading optical system 13 placed under the document reading plate 12 made of transparent glass. The document S from which characters and images have been read is further transported on the transport path and discharged onto the document discharge table 14.

  Further, the document reading apparatus 10 has a hinge extending in the depth direction in the drawing on the right side in the drawing, and the document paper tray 11 and the document discharge table 14 are integrally lifted around the hinge as a rotation center. Under the raised position, the document reading plate 12 extends.

  In this document reading device 10, when only one document is placed downward on the document reading plate 12 instead of placing the document on the document paper tray 11, the document reading optical system 13 is moved forward from the rear side in the figure. To read the characters and images from the original on the original reading plate 12.

  Further, the document reading apparatus 10 is provided with an operation panel 15 on the left side in the drawing. The user can input various setting contents such as an image output format and the number of copies such as double-sided printing or single-sided printing by operating the operation panel 15. From the document reading device 10, a setting signal indicating the setting content input through the operation panel 15 is input to the image forming device 20.

  Further, from the document reading device 10, an image signal obtained by reading characters and images of the document by the document reading optical system 13 is input to the image forming device 20.

  The image forming apparatus 20 forms an image based on the input image signal as follows.

  The image forming apparatus 20 includes a control unit 21 that controls the movement of each component in the image forming apparatus 20. Setting signals and image signals input from the document reading apparatus 10 are input to the control unit 21 of the image forming apparatus 20. The image forming apparatus 20 forms an image based on the input setting signal and image signal under the control of the control unit 21.

  Two sheet trays 31 are accommodated in the lower part of the image forming apparatus 20. In these sheet trays 31, sheets P having different dimensions are stored in a stacked state for each sheet tray 31. Each paper tray 31 is configured to be freely drawn out for replenishing paper P.

  Of these two paper trays 31, for example, the paper P is picked up by the pickup roll 32 from the paper tray in which the paper P having a size suitable for the size of the document or a size set in the setting signal is stored. Sent out. The fed paper P is separated one by one by the separating roll 33, the separated single paper P is conveyed upward, and the leading edge of the paper P reaches the standby roll 34. The standby roll 34 plays a role of adjusting the subsequent transport timing and sending out the paper P. The standby roll 34 adjusts the subsequent transport timing of the paper P that has reached the standby roll 34. And further conveyed.

  The image forming apparatus 20 includes a photoreceptor 22 that rotates in the direction indicated by the arrow A above the standby roll 34. Around the photosensitive member 22, a charger 23, an exposure unit 24, a developing unit 25, a transfer unit 26, and a cleaner 27 are provided.

  The photosensitive member 22 has a cylindrical shape, holds charges by charging, and discharges the charges by exposure to form an electrostatic latent image on the surface.

  The charger 23 charges the surface of the photoreceptor 22 to a certain charging potential.

  Further, the image signal obtained by the document reading apparatus 10 as described above is input from the control unit 21 to the exposure device 24. The exposure device 24 outputs exposure light modulated in accordance with the image signal. The photoreceptor 22 is exposed to the exposure light, and an electrostatic latent image is formed on the surface of the photoreceptor 22.

  Further, the photosensitive member 22 is exposed to exposure light to form an electrostatic latent image on the surface, and then developed by the developing unit 25. The developing device 25 includes a toner storage portion 25a, a toner supply path 25b, and a developing roll 25c. In the developing unit 25, the toner stored in the toner storage unit 25a is sent to the vicinity of the developing roll 25c through the toner supply path 25b. Then, the development is performed by supplying the toner to the photosensitive member 22 by the developing roller 25 c, and a toner image is formed on the surface of the photosensitive member 22.

  Here, the standby roll 34 sends out the paper P so that the toner image on the photosensitive member 22 reaches the position in accordance with the timing when the toner image reaches the position facing the transfer unit 26. The toner image on the photosensitive member 22 is transferred to the fed paper P under the action of the transfer device 26.

  The toner remaining on the photoconductor 22 after the transfer of the toner image is removed from the photoconductor 22 by the cleaner 27.

  A combination of the photosensitive member 22, the charger 23, the exposure unit 24, the developing unit 25, the transfer unit 26, and the cleaner 27 corresponds to an example of the image forming unit referred to in the present invention.

  The sheet P to which the toner image has been transferred proceeds further in the direction of arrow B, and is heated and pressed by the fixing device 100 to form an image composed of the fixed toner image on the sheet P.

  The sheet P that has passed through the fixing device 100 proceeds in the direction of arrow C toward the discharge device 200, and is further sent in the direction of arrow D by the discharge device 200 to be discharged onto the discharge table 28.

  Here, the image forming apparatus 20 is an apparatus capable of forming images on both sides of the paper P. When images are formed on both sides of the sheet P, the sheet P on which the image is formed only on the first side of the sheet P as described above is discharged by the ejector 200 in the directions of arrows C and D in the rear end of the sheet. Is transported to the reverse position where it enters the ejector 200. Thereafter, the ejector 200 reverses the paper transport direction in the arrow E direction opposite to the arrow D direction at the reverse position, and the paper P is drawn in the arrow E direction. The drawn paper P now proceeds in the direction of arrow F, and is further transported in the directions of arrows G and H by the transport roll 35 and reaches the standby roll 34 again. When the paper roll P reaches the standby roll 34 again, the paper P is turned upside down. Then, the standby roll 34 sends out the paper P in a posture in which the second surface opposite to the first surface on which the image has already been formed is directed to the photosensitive member 22 side. Thereafter, an image is formed on the second surface in the same manner as the image formation on the first surface. The paper P on which images are formed on both sides in this manner is then discharged onto the paper discharge tray 28.

  Further, the image forming apparatus 20 is configured such that the rear panel 29 covering the fixing device 100 and the discharge device 200 is rotated and opened in the direction of arrow I around the fulcrum 29a. When the paper P is jammed between the fixing device 100 and the discharge device 200, the rear panel 29 is opened by the user. Then, the user inserts his / her hand from the lower side of the document reading apparatus 10 into the opening that appears when the rear panel 29 is opened, and removes the jammed paper P.

  FIG. 2 is a cross-sectional view of the fixing device and the discharging device in the copying machine shown in FIG. The fixing device 100 includes a heating roll 101 and a pressure roll 102. The heating roll 101 has a cylindrical shape provided with a heat source 101 a therein, and the circumferential surface of the cylindrical pressure roll 102 is pressed against the circumferential surface of the heating roll 101. The paper that has advanced in the direction of arrow B and has reached the fixing device 100 is guided by the paper guide 103 to the contact portion between the heating roll 101 and the pressure roll 102. The sheet is sandwiched between the heating roll 101 and the pressure roll 102 at the contact portion.

  The heating roll 101 and the pressure roll 102 rotate in the direction of arrow J while being in contact with each other. For this reason, the paper guided to the contact portion is sandwiched between the heating roll 101 and the pressure roll 102 at the contact portion and proceeds toward the discharger 200. At that time, an image composed of a fixed toner image is formed on the sheet by being heated by the heating roll 101 and pressurized by the pressure roll 102.

  The fixing device 100 further includes a frame 100 a that rotatably supports the heating roll 101 and the pressure roll 102, and a cover 104 that covers a contact portion between the heating roll 101 and the pressure roll 102. The cover 104 is rotatably attached to the frame 100a at a fulcrum 104a. The cover 104 is closed so as to block the upper part of the first transport path 20a in a state where the cover 104 is in contact with the protruding portion 100a_1 protruding above the pressure roll 102 of the frame 100a. The tip is pushed up. Further, the fixing device 100 includes a fixing device side guide rib 100a_2 that guides the sheet to the discharge device 200 on the first transport path 20a. A plurality of the fixing device side guide ribs 100a_2 are arranged in the paper width direction (direction perpendicular to the paper surface of FIG. 2). When the cover 104 is closed, the tip opposite to the fulcrum 104a side enters between the fixing device side guide ribs 100a_2.

  The discharger 200 also includes a lower frame 201 that serves as a lower guide in the second transport path 20b that passes through the discharger 200, an upper frame 202 that serves as an upper guide, and a discharge that feeds paper. And a paper roll 203. Further, the ejector 200 includes a detector 300 that detects that the sheet has been conveyed.

  The detector 300 includes a rotatable shaft 311 extending in a direction perpendicular to the paper surface of FIG. 2 and a detection claw 312 fixed to the shaft 311. When the leading edge of the paper reaches the detector 300, the detection claw 312 rotates together with the shaft 311 in the direction of being lifted by the leading edge of the paper, and the rotation of the shaft 311 is detected photoelectrically as will be described later. Thereby, it is detected whether or not the sheet has reached the position of the detector 300.

  The detector 300 plays a role of confirming that the apparatus is operating normally by monitoring the arrival of the sheet at the timing at which the sheet should arrive. The sheet detection result by the detector 300 is notified to the control unit 21 (see FIG. 1). If the paper does not arrive at the timing when the paper should arrive, it means that an abnormal condition such as paper jam has occurred in the middle. Be notified.

  The image forming apparatus 20 has a single-sided printing mode for forming an image only on one side of a sheet and a double-sided printing mode for forming an image on both sides of a sheet. The distinction between the single-sided printing mode and the double-sided printing mode is set by operating the operation panel 15 shown in FIG. 1, and is transmitted to the control unit 21 (see FIG. 1) as one of setting signals. In the double-sided printing mode, the discharge roll 203 reverses the rotation direction while conveying the paper on which the image is formed on one side (first side) of the paper in the direction of arrow D, and moves the paper in the direction of arrow E. Transport to. The detector 300 also plays a role in determining the rotation inversion timing at this time. That is, the elapsed time after the detector 300 detects the leading edge of the sheet is measured, and the sheet is reversed when the trailing edge of the sheet reaches the branch point 20d and the cover 104 is closed again.

  Further, the discharger 200 includes a presser piece 204 that is pressed from above so that the sheet discharged on the sheet discharge table 28 floats and does not hinder the discharge of the next sheet discharged.

  The presser piece 204 is rotatable about its upper end, and is rotated by the paper discharged by the discharge roll 203 so as to open the paper path. After exiting, the posture returns to the illustrated state and the rear end of the sheet is pushed downward. As a result, a discharge path for the next sheet is secured.

  When the sheets are sequentially discharged onto the sheet discharge table 28, a large number of sheets may be stacked on the sheet discharge table 28. The discharger 200 is a detection piece for detecting that a predetermined amount of sheets are stacked on the sheet discharge table 28 in order to avoid the amount of sheets exceeding a predetermined amount from being stacked on the sheet discharge table 28. 205 (see FIG. 3). The detection piece 205 is rotatably supported at the rear end side. When the sheets are stacked on the paper discharge table 28, the front end of the detection piece 205 is lifted, and when the paper is lifted to a specified position, the paper is placed on the paper discharge table 28. In order to avoid further stacking, the operation of the apparatus is temporarily stopped, and the user is notified to remove the paper from the paper discharge tray 28.

  In the following, the description will focus on paper conveyance.

  The sheet that has been fixed on the first surface by the fixing device 100 and has passed through the fixing device 100 pushes up the cover 104 that closes the upper portion of the first transport path 20a and proceeds in the direction of arrow C, and the detection claw. 302 is pushed up to advance in the direction of arrow D on the second transport path 20b. When the leading edge of the paper is sandwiched between the paper discharge rollers 203, the paper is then further conveyed in the direction of arrow D by the paper discharge rollers 203. In the single-sided printing mode, the paper is discharged as it is onto the paper discharge tray 28.

  In the double-sided printing mode, the paper on which the image is formed only on the first side is conveyed in the direction of arrow D by the paper discharge roll 203 as in the single-sided printing mode, and the trailing edge of the paper is the branch point 20d. , The rotation of the paper discharge roll 203 is reversed, and the paper advances this time in the direction of arrow E. The cover 104 is prevented from entering the first transport path 20a that has passed immediately before, and is guided to the upper surface of the cover 104. And is conveyed in the direction of arrow F on the third conveyance path 20c. The third transport path 20c is a path that reaches the standby roll 34 (see FIG. 1) and joins the first transport path 20a. When the sheet is conveyed along the third conveyance path 20c, the front and back are reversed, and the second surface on which the image is not formed is oriented toward the photosensitive member 22 (see FIG. 1). This sheet is sent out by the standby roll 34 as in the case of image formation on the first surface. Thereafter, an image is formed on the second surface in the same manner as in the case of image formation on the first surface. In this way, the paper on which images are formed on both sides is discharged onto the paper discharge tray 28.

  3 and 4 are external perspective views of the discharger outlined in FIG. Here, FIG. 3 shows a state where the paper has not reached the detector 300 (see FIG. 2), and FIG. 4 shows that the paper has reached the detector 300 and the detection claw 312 (see FIG. 2) is rotating. Indicates the state.

  3 and 4, the detector 300 is substantially hidden by the upper frame 202 of the ejector 200, but this detection is performed when there is no paper (FIG. 3) and when the paper is passing (FIG. 4). The posture of the light shielding plate 313 that blocks the photoelectric sensor 320 (see FIGS. 5 and 6) that constitutes the detection member 310 of the container 300 is changed.

  FIG. 5 is a perspective view showing the lower frame and the detector with the upper frame and the discharge roll removed from the ejector. FIG. 6 is an enlarged view of a portion in the vicinity of the photoelectric sensor in FIG. FIGS. 5 and 6 show the state when there is no sheet. The sheet advances in the direction of arrow C shown in FIG. 5, and is further discharged in the direction of arrow D (see also FIGS. 1 and 2).

  The detector 300 includes a detection member 310, a photoelectric sensor 320, and a receiving member 330 formed on a part of the lower frame 201. Further, below the receiving member 330, a heat shield member 340 that is also a part of the lower frame 201 is provided at a position separated from the receiving member 330.

  In addition to the shaft 311 and the detection claw 312 fixed to the shaft shown in FIG. 2, the detection member 310 further includes a light shielding plate 313 fixed to the shaft 311. Here, the shaft 311 corresponds to an example of the connecting member according to the present invention, and the detection claw 312 and the light shielding plate 313 correspond to examples of the first member and the second member, respectively, according to the present invention. Both the detection claw 312 and the light shielding plate 313 are fixed to the shaft 311 and rotate integrally. Here, the posture of the detection claw 312 when not in contact with the paper is the first posture according to the present invention, and the posture of the detection claw 312 when rotating in contact with the conveyed paper is the present invention. This corresponds to each example of the second posture. In addition, each posture of the light shielding plate 313 when the detection claw 312 is in the first posture and the second posture corresponds to an example of each of the third posture and the fourth posture.

  Here, the detection claw 312 and the light shielding plate 313 constituting the detection member 310 are in their respective positions when the detection claw 312 is not in contact with the paper due to its own weight (the first position and the third position in the present invention). )). Therefore, when the detection claw 312 rotates after the detection claw 312 rotates in contact with the conveyed paper, the detection claw 312 and the light shielding plate 313 rotate by their own weight, and the detection claw 312 is not in contact with the paper. (The first posture and the third posture in the present invention).

  Here, an example is described in which the detection claw 312 and the light shielding plate 313 are subjected to forces in their respective orientations when the detection claw 312 is under its own weight and the detection claw 312 is not in contact with the paper. However, the present invention is not limited to this, and instead of relying on its own weight or assisting its own weight, forcibly with a torsion spring or the like, toward the posture in a state where the detection claw 312 is not in contact with the paper. You may give power.

  Here, an example is described in which both the detection claw 312 and the light shielding plate 313 are fixed to one shaft 311 and the detection claw 312 and the light shielding plate 313 are integrally rotated by the same angle. However, in the present invention, the first posture of the first member (the detection claw 312 in the example shown here) corresponds to the third posture of the second member (the light shielding plate 313 in the example shown here), and the first It is only necessary that the second posture of the member corresponds to the fourth posture of the second member. That is, the connecting member that connects the first member and the second member does not need to rotate the first member and the second member integrally. For example, in this connecting member, the first member rotates 30 degrees from the first attitude to the second attitude, and the second member rotates 15 degrees from the third attitude as the first member rotates. You may connect a 1st member and a 2nd member so that it may rotate and it may become a 4th attitude | position.

  Returning to the present embodiment, the description will be continued.

  The photoelectric sensor 320 includes a light emitting unit 321 that generates light and a light receiving unit 322 that receives light emitted from the light emitting unit 321. The light emitting unit 321 and the light receiving unit 322 face each other with a space therebetween. When the light shielding plate 313 is in the posture shown in FIGS. 5 and 6, the light shielding plate 313 enters between the light emitting unit 321 and the light receiving unit 322 so that the light emitted by the light emitting unit 321 enters the light receiving unit 322. Blocking.

  FIG. 7 is a cross-sectional view of the detection claw when the detection member is in the posture shown in FIGS. 5 and 6.

  FIG. 7 shows the detection claw 312 when it is not in contact with the paper, as in FIGS. 5 and 6. The detection claw 312 is in a posture that blocks the second transport path 20b (see also FIG. 2) through which the paper passes.

  FIG. 8 is a cross-sectional view of the portion of the light shielding plate when the detection member is in the posture shown in FIGS. 5 and 6.

  FIG. 8 shows the posture of the light shielding plate 313 when the detection claw 312 is not in contact with the paper, as in FIGS. 5 and 6. The light shielding plate 313 enters between the light emitting unit 321 and the light receiving unit 322 of the photoelectric sensor 320 (see FIGS. 5 and 6) and is in a posture to be abutted against the receiving member 330. When the light shielding plate 313 rotates toward the posture shown in FIG. 8, the receiving member 330 receives the abutment of the light shielding plate 313 and maintains the light shielding plate 313 in the posture shown in FIG. Is responsible.

  Further, the heat shield member 340 is provided below the receiving member 313 and at a position separated from the receiving member 313. The heat shield member 340 is located on the fixing device 100 side of the receiving member 330, and has a role of blocking the heat of the fixing device 100 from being transmitted to the receiving member 330. The photoelectric sensor 320 is disposed immediately above the receiving member 330. The photoelectric sensor 320 is relatively weak against heat, and if high heat is transmitted, it may cause erroneous detection or deterioration.

  In the present embodiment, a heat shield member 340 is provided at a position on the fixing device 100 side of the receiving member 330. The structure is such that the heat of the fixing device 100 is not easily transmitted to the photoelectric sensor 320, and erroneous detection and deterioration of the photoelectric sensor 320 are avoided.

  9 is a perspective view showing the lower frame and the detector, as in FIG. 5, and FIG. 10 is an enlarged view of a portion near the photoelectric sensor in FIG. FIGS. 11 and 12 are cross-sectional views of the detection claw and the light shielding plate, respectively, when the detection member is in the posture shown in FIGS. 9 and 10.

  9 and 10 are in a state in which the detection member 310 is rotated as compared with FIGS. 5 and 6. That is, the detection claw 312 is pushed by a sheet of paper (not shown) that has been conveyed, and is in a posture that opens the second conveyance path 20b as shown in FIG. Accordingly, the light shielding plate 313 also rotates from the posture shown in FIGS. 5 and 6 and is in a posture retracted from between the light emitting unit 321 and the light receiving unit 322 of the photoelectric sensor 320 as shown in FIG.

  When the light shielding plate 313 is rotated to this posture, the light emitted from the light emitting unit 321 is received by the light receiving unit 322, whereby the detection claw 311 is pushed by the paper, that is, the paper reaches the position of the detector 300. Is detected.

  FIG. 13 is an enlarged view of the lower frame in the vicinity of the photoelectric sensor, with only the lower frame removed by removing the photoelectric sensor and the like, and FIG. 14 is a portion of the lower frame corresponding to the light shielding plate. FIG. 5 is a cross-sectional view showing only the lower frame with the detection claw and the like removed.

  The receiving member 330 that receives the abutting of the light shielding plate 313 (not shown here) is formed as a part of the lower frame 201 and has a cantilever shape in which grooves 331 are formed on both sides thereof.

  When the detection claw 312 is pushed by the paper and rotates to the posture shown in FIG. 11, the light shielding plate 313 rotates to the posture shown in FIG. After that, when the paper leaves the detection claw 312, the detection claw 312 rotates from the posture shown in FIG. 11 to the posture shown in FIG. 7 due to the weight of the detection member 310. 8 to the posture shown in FIG. 8, and the light shielding plate 313 strikes the receiving member 330. A sound is generated with this abutment.

  In this embodiment, the receiving member 330 is formed in a cantilever shape with grooves 331 formed on both sides as shown in FIG. 13, and the rigidity of the receiving member is weakened. Has been reduced.

  In the case of the receiving member 320 of this embodiment, the rigidity of the receiving member 320 is weakened only by changing the shape of a part of the lower frame 201 such that grooves 331 are formed on both sides without adding new parts. Reduction is achieved.

  FIG. 15 is a diagram illustrating a first modification of the receiving member.

  The illustrated arrow indicates the movement of the light shielding plate.

  The receiving member 530 shown in FIG. 15 includes a contact member 531 that comes into contact with the light shielding plate and a spring member 532 that supports the contact member 531.

  The receiving member 530 shown in FIG. 15 requires a new part addition, unlike the receiving member 330 shown in FIG. 13, but it is possible to further effectively reduce the sound when the light shielding plate hits. .

  FIG. 16 is a diagram illustrating a second modification of the receiving member.

  The illustrated arrow indicates the movement of the light shielding plate, as in the arrow of FIG.

  The receiving member 630 shown in FIG. 16 has a structure in which a soft elastic body 632 made of, for example, rubber or the like is attached to a hard receiving surface 631, and the light shielding plate is directly attached to the elastic body 632. It is hit.

  In the case of this receiving member 630, a new part called an elastic body 632 is required. However, the receiving member 630 having this configuration can further effectively reduce the sound generated when the light shielding plate is abutted.

  Here, the image forming apparatus for forming a monochromatic image shown in FIGS. 1 and 2 has been described as an example, but the present invention can be applied to an image forming apparatus for forming a color image as it is. In addition, the sheet conveying apparatus of the present invention is not only applied to the image forming apparatus, but can be widely applied to apparatuses having a mechanism for conveying a sheet even if it is not an image forming apparatus.

DESCRIPTION OF SYMBOLS 1 Copier 10 Document reading apparatus 20 Image forming apparatus 20a 1st conveyance path 20b 2nd conveyance path 20c 3rd conveyance path 20d Branch point 28 Discharge stand 100 Fixing device 200 Discharge device 201 Lower frame 202 Upper frame 203 Paper discharge roll 204 Pressing piece 205 Detection piece 300, 302 Detector 310 Detection member 311 Shaft 312 Detection claw 313 Light shielding plate 320 Photoelectric sensor 330, 530, 630 Receiving member 321 Light emitting portion 322 Light receiving portion 331 Groove 340 Heat shielding member 531 Contact member 532 Spring Member 632 Elastic Body

Claims (6)

A transport unit for transporting paper;
A detection unit for detecting that the paper has been conveyed,
The detection unit is
A first member that changes its posture between a first posture that is in non-contact with the paper and a second posture that rotates in contact with the conveyed paper; a third member corresponding to the first posture; A second member that changes a posture between a posture and a fourth posture corresponding to the second posture, and the first member and the second member connected to each other to connect the first member and the second member; A connecting member for changing the posture, and when the first member is not in contact with the paper, the first member and the second member exert forces in the directions of the first posture and the third posture, respectively. The received detection member;
A detector for detecting whether the second member is in the third posture or the fourth posture;
The abutment of the second member that receives the abutment of the second member that has changed from the fourth posture to the third posture and maintains the second member in the third posture. And a receiving member having a structure that weakens the rigidity of the sheet conveying device.   2. The paper conveying apparatus according to claim 1, wherein the receiving member has a cantilever shape in which grooves are formed on both sides.   The sheet conveying apparatus according to claim 1, wherein the receiving member includes a contact member that contacts the second member and a spring member that supports the contact member.   The paper conveying apparatus according to claim 1, wherein the receiving member has a relatively soft elastic body on the relatively hard receiving surface and is in contact with the second member. A transport unit for transporting paper;
An image forming unit that transfers the toner image onto a sheet that has been conveyed by forming a toner image;
A fixing unit that is disposed downstream of the image forming unit in the sheet conveyance direction, heats and pressurizes the sheet that is further conveyed after receiving the transfer of the toner image, and fixes the toner image on the sheet;
A detection unit that is disposed downstream of the fixing unit in the sheet conveyance direction and detects that the sheet has been conveyed;
The detection unit is
A first member that changes its posture between a first posture that is in non-contact with the paper and a second posture that rotates in contact with the conveyed paper; a third member corresponding to the first posture; A second member that changes a posture between a posture and a fourth posture corresponding to the second posture, and the first member and the second member connected to each other to connect the first member and the second member; A connecting member for changing the posture, and when the first member is not in contact with the paper, the first member and the second member exert forces in the directions of the first posture and the third posture, respectively. The received detection member;
A detector for detecting whether the second member is in the third posture or the fourth posture;
The abutment of the second member that receives the abutment of the second member that has changed from the fourth posture to the third posture and maintains the second member in the third posture. An image forming apparatus comprising: a receiving member having a structure that weakens the rigidity of the image forming apparatus.   The thermal insulation member which is spaced apart from the said receiving member and is arrange | positioned in the position near the said fixing part rather than this receiving member, and interrupts | blocks the heat | fever transmitted to this receiving member from this fixing part is provided. Image forming apparatus.

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