JP4375375B2 - Image forming apparatus - Google Patents

Description

  The present invention includes a conveyance roller and a press roller that is pressed against the conveyance roller, and includes a sheet conveyance mechanism that nips and conveys a sheet at a pressure contact portion between the conveyance roller and the press roller by rotation of the conveyance roller. The present invention relates to a forming apparatus.

An image forming apparatus such as a facsimile machine or a copying machine includes a conveyance roller and a press roller pressed against the conveyance roller, and conveys the sheet by nipping the sheet at the pressure contact portion between the conveyance roller and the press roller by the rotation of the conveyance roller. Some have a paper transport mechanism.
JP 2002-220133 A

  In the image forming apparatus provided with the above-mentioned paper transport mechanism, the press roller is assembled in a state of being pressed against the transport roller installed in the paper transport path in the image forming apparatus. However, depending on the arrangement and arrangement of parts in the image forming apparatus, this press roller may need to be assembled in the back where it is difficult to reach, and conventionally, the parts required for the assembly are separate. Therefore, there is a problem that the efficiency of the work of assembling the press roller by combining the parts is not very good.

  On the other hand, the press roller is in pressure contact (nip) with the transport roller. If paper clogging occurs at the nip part of the press roller, The nip must be released. Therefore, it is necessary to provide a nip release mechanism on the press roller. However, if the number of parts required for assembling the press roller is increased by providing this nip releasing mechanism, the efficiency of the assembling operation of the press roller may be further reduced.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus including a paper transport mechanism that can improve the efficiency of press roller assembly work.

In order to solve the above-mentioned problem, the invention according to claim 1 of the present application includes a conveyance roller and a press roller pressed against the conveyance roller, and a pressure contact portion between the conveyance roller and the press roller by rotation of the conveyance roller. An image forming apparatus provided with a paper transport mechanism for transporting paper in a nip, comprising a press roller assembly comprising the press roller, a shaft that supports the press roller, and a fixture that supports the shaft. The press roller assembly can be incorporated into the image forming apparatus by attaching and fixing the pair of attachments to the main body frame of the image forming apparatus, and the press roller assembly includes the press roller assembly, The shaft that supports the press roller is pressed against the conveying roller, and the press roller is pressed against the conveying roller. A nip release lever for releasing the pressure contact between the press roller and the conveying roller and separating the elastic member, and one end of the nip release lever is rotatably attached to the shaft. The state is a horizontal state, and when the other end is lifted upward from the horizontal state and rotated about the shaft, it rides on a guide portion provided on the fixture, and the shaft resists the elastic force of the elastic member. The press roller and the conveying roller are lifted to release the pressure roller and move away to release the nip state .

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the nip release lever is moved to the fixture by the elastic force of the elastic member when the nip state is released. It is characterized in that a locking mechanism for preventing an operation to return to is provided .

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the rising from the nip state of the nip release lever to a position where the operation of returning to the nip state by the locking mechanism is prevented. The angle is configured to be less than 90 degrees .

According to a fourth aspect of the present invention, in the image forming apparatus according to the first, second, or third aspect , the nip release lever is a part of the sheet conveyance path in a nip state where the press roller is pressed against the conveyance roller. It is configured to form a portion .

According to the invention described in claim 1 of the present application, it is provided with a press roller assembly including a press roller , a shaft that supports the press roller, and a fixture that is supported by the shaft, and the press roller assembly includes: By attaching and fixing a pair of attachments to the main body frame of the image forming apparatus, it can be incorporated into the image forming apparatus. The press roller assembly has a shaft that supports the press roller on the conveying roller side. An elastic member that presses and presses the press roller against the transport roller to bring it into a nip state, and a nip release lever that releases and separates the press roller from the transport roller, and one end of the nip release lever pivots on the shaft The nip state is in a horizontal state, and the other end is lifted upward from the horizontal state to rotate the shaft. Abutting part that lifts the shaft against the elastic force of the elastic member when released as a center and lifts the shaft against the elastic force of the elastic member to release the press roller and the conveying roller to separate and release the nip state It is the structure provided with. Therefore, since the press roller assembly has a nip releasing mechanism having a nip releasing lever, the nip releasing mechanism is provided by assembling the press roller assembly, and the assembling work to the image forming apparatus is performed. At the same time, a nip release mechanism that can reliably release the nip even when the force to operate the nip release lever is small can be easily realized, and the operability of the nip release can be improved .

According to the invention described in claim 2 of the present application, the locking mechanism for preventing the nip release lever from returning to the nip state by the elastic force of the elastic member when the nip state is released. Therefore, it is possible to stop the press roller in the nip release state, and it is possible to improve convenience when processing such as a paper jam at the press contact portion between the press roller and the transport roller.

According to the invention described in claim 3 of the present application, the rising angle from the nip state of the nip release lever to the position where the operation of returning to the nip state by the locking mechanism is prevented is less than 90 degrees. Therefore, even if you forget to return the nip release lever to the nip position and attach another part or cover member to the upper part of the nip release lever, the nip release lever is automatically pushed by another part or cover member. Therefore, the image forming apparatus can prevent problems such as part catches and failures.

According to the invention described in claim 4 of the present application, since the nip release lever is formed so as to form a part of the sheet conveyance path in the state of being in the nip position pressed against the press roller, the component can be configured with a simple configuration. The image forming apparatus can protect the sheet conveyed by a part of the sheet conveying path constituted by the nip release lever without increasing the number of points.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing an image forming apparatus provided with a paper transport mechanism according to an embodiment of the present invention. First, a schematic overall configuration of the image forming apparatus will be described with reference to FIG. The image forming apparatus to which the present invention is applied may be any one of a copier, a facsimile machine, a printer, or a so-called multifunction machine having these functions as long as the image forming apparatus has a paper transport mechanism. . The image forming apparatus 1 shown in FIG. 1 is configured integrally by arranging a reading unit 2 on the upper side and a recording unit 3 on the lower side. The reading unit 2 includes an automatic document feeder (hereinafter referred to as “ADF device”) 4 attached to one end of the upper part of the apparatus main body, and an image reading device that reads an image of a document installed below the ADF device 4. (Not shown). The recording unit 3 includes an image recording device 5 disposed on the side of the image reading device, a paper feed cassette 6 and a recording paper discharge tray 7 disposed on the lower side of the image recording device 5. An operation panel 8 is attached to the front surface of the image recording apparatus 5. On the other hand, on the side of the ADF device 4, an upper cover 10 is installed that is attached to the upper portion of the main body cover 9 of the image recording device 5 so as to be freely opened and closed. The upper surface of the upper cover 10 is a document discharge tray 10a on which the document discharged from the ADF device 4 is placed, and a document supply tray 11 on which the document to be supplied to the ADF device 4 is placed above it. It is attached.

  In this image forming apparatus 1, the originals set on the original supply tray 11 are separated one by one and taken into the ADF apparatus 4, and after the image of the original is read by the image reading apparatus, it is sent to the original discharge tray 10 a. It is supposed to be discharged. On the other hand, the paper stored in the paper feed cassette 6 is fed to the image recording device 5, and after recording on the paper is performed by the image recording device 5, the paper is transferred to the recording paper discharge tray 7. It is supposed to be discharged.

  FIG. 2 is a perspective view showing a state in which the upper cover 10 of the image recording apparatus 5 is opened, and FIG. 3 is a side sectional view showing an internal configuration of the image recording apparatus 5. As shown in these drawings, an intermediate cover 12 that can be opened and closed in the vertical direction is provided in the image recording apparatus 5 with a shaft portion 12a provided at one end as a fulcrum. FIG. 3 shows a state in which the intermediate cover 12 is opened. A process unit 13 is disposed below the intermediate cover 12. The process unit 13 is configured by combining the developing unit 14 and the photosensitive unit 15. The developing unit 14 and the photosensitive unit 15 can be attached and detached in units with the intermediate cover 12 opened.

  The developing unit 14 includes a toner chamber 19 that stores toner, a developing roller 20 that supplies toner to the photosensitive drum 16 described below of the photosensitive unit 15, and a toner supply roller 21 that supplies toner to the developing roller 20. ing. The photoconductor unit 15 includes a photoconductor drum 16 that transfers toner onto paper, a casing 34 that houses the photoconductor drum 16, and a charging roller 18 that charges the surface of the photoconductor drum 16 to a negative potential. Further, a slit 34a is opened in the upper surface portion of the housing 34, and the optical writing means described below is inserted.

  A sheet conveyance path 31 formed on an inner guide 30 that forms the lower side wall of the process unit 13 is provided below the developing unit 14. The conveyance downstream side of the sheet conveyance path 31 communicates between the photosensitive drum 16 of the photosensitive unit 15 and the transfer roller 17. A conveyance roller 32 is installed at the entrance of the sheet conveyance path 31, and a press roller 33 is attached to the conveyance roller 32 in a pressure contact state. As will be described in detail below, the press roller 33 is configured as a press roller assembly 40 together with other parts assembled together with the press roller 33, and the press roller assembly 40 is integrated into the process unit 13 as one unit. To be assembled.

  In addition, a fixing unit 22 is installed on the downstream side of the process unit 13. The fixing device unit 22 includes a heat roller 23 and a press roller 24 disposed to face the heat roller 23. On the other hand, an LED head 27 as an optical writing unit is installed at a position directly above the photosensitive unit 15 of the intermediate cover 12. The LED head 27 has an LED head array 28 having a large number of light emitting portions arranged in a line along the width direction of the conveyed paper, and condenses the light from the LED head array 28 on the photosensitive drum 16. And a condensing lens 29. Although not shown in detail, with the intermediate cover 12 closed, the condensing lens 29 of the LED head 27 is inserted into the slit 34a of the housing 34 of the photoconductor unit 15 to the photoconductor drum 16 side. It is designed to protrude.

  A procedure for recording an image on a sheet in the image recording apparatus 5 configured as described above will be briefly described. The LED head 27 causes the LEDs on the LED head array 28 to emit light based on image information read by the image reading device or image information received by communication means (not shown) included in the image forming device 1. The condensing lens 29 forms an image of the light emitting point of the LED on the photosensitive drum 16, whereby an electrostatic latent image is formed on the photosensitive drum 16. On the other hand, the toner supplied from the toner chamber 19 of the developing unit 14 to the photosensitive drum 16 via the toner supply roller 21 and the developing roller 20 adheres to the electrostatic latent image on the photosensitive drum 16. A toner image is formed, and the toner image is transferred onto the sheet conveyed through the sheet conveyance path 31 by the conveyance roller 32 and the press roller 33. The sheet on which the toner image has been transferred is sent between the press roller 24 and the heat roller 23 of the fixing unit 22, and the toner transferred on the sheet is heated and melted by the heat roller 23 to be fixed as a permanent image. . The sheet on which the toner has been fixed is discharged from the image recording apparatus 5 by a discharge roller 25 and a press roller 26 arranged on the downstream side of conveyance of the fixing unit 22.

  Next, the press roller assembly 40 provided in the image forming apparatus 1 will be described. FIG. 4 is a plan view showing the press roller assembly 40. As shown in the figure, the press roller assembly 40 includes a press roller 33, a shaft 41 that supports the press roller 33, a pair of fixtures 50 and 50 that support the shaft 41, and a nip between the press roller 33. The nip release lever 45 is configured to be provided. The press rollers 33 are resin-made cylindrical members, and a plurality of the press rollers 33 are arranged along the conveyance width direction of the conveyance rollers 32. A cylindrical rod-shaped shaft 41 is inserted through each press roller 33. A nip releasing lever 45 formed in a substantially rectangular plate shape along the longitudinal direction is attached to the shaft 41. The nip release lever 45 includes a shaft insertion hole 46a formed in a plurality of projecting attachment portions 46 formed to protrude from one side 45a in the longitudinal direction facing the shaft 41 side, and a shaft inserted into the shaft insertion hole 46a. 41 is rotatably attached around 41.

  FIG. 5 is a partially enlarged perspective view of the inside of the image recording apparatus 5 with the developing unit 14 removed, as viewed from above, and a view of the sheet conveyance path 31 with the press roller assembly 40 assembled as viewed from above. . FIG. 6 is a schematic side view (partially sectional view) of the fixture 50 and the nip release lever 45 of the press roller assembly 40. As shown in these drawings, a pair of fixtures 50 that rotatably support the end portion of the shaft 41 includes a main body portion 51 formed in a substantially rectangular box shape, and one end in the longitudinal direction of the main body portion 51. The shaft support portion 52 is provided. The shaft support portion 52 supports the shaft 41 so that the axial direction thereof is in a horizontal direction perpendicular to the longitudinal direction of the main body portion 51. The shaft insertion portion 52a into which the shaft 41 is inserted, and the shaft insertion hole 52a. The cover part 52b which covers the upper surface side of the shaft 41 provided inside is provided. As shown in FIG. 6, the shaft insertion hole 52a has a vertically long cross-sectional shape. In addition, a guide part 53 made of a semicircular arc-shaped curved surface along the upper surface of the shaft 41 is formed on the upper surface of the cover part 52b, and the end of the guide part 53 on the main body part 51 side is perpendicular to the cover part 52b. An upright plate-like locking piece 54 is formed. On the other hand, a protruding contact portion 47 is formed at a position corresponding to the guide portion 53 on the one side 45 a of the nip release lever 45. The contact portion 47 comes into contact with and rides on the guide portion 53 when the nip release lever 45 is rotated as described below.

  On the other hand, as shown in FIG. 4, a flat collar portion 55 projects from the side surface (longitudinal side surface) 51 a of the main body 51 of the fixture 50, and the fixture 50 is attached to the collar portion 55. An insertion hole 55a for inserting a screw 37 to be fixed to a main body frame 35 described below of the image recording apparatus 5 is formed. Further, a small projection 56 is formed on the side surface of the end portion of the main body 51 opposite to the shaft support portion 52 for positioning when the fixture 50 is fixed to the main body frame 35.

  Next, a procedure for assembling the press roller assembly 40 having the above configuration will be described. First, as shown in FIG. 4, the shaft 41 is inserted into each press roller 33 and the shaft insertion hole 46 a of the nip release lever 45, and both ends of the shaft 41 are connected to the shaft support portions 52, 50 of the fixtures 50, 50. 52. In this state, as shown in FIG. 5, the small protrusions 56 of the fixtures 50 are inserted into the insertion holes 36 a formed in the side wall portion 36 of the main body frame 35 of the image recording apparatus 5. In this state, the attachment tool 50 is attached to the main body frame 35 by fastening and fixing the screw 37 inserted into the insertion hole 55a of the collar portion 55 to a screw hole (not shown) provided in the bottom surface portion 38 of the main body frame 35. Fix it. Further, as shown in FIG. 5, a shaft presser plate 39 made of an elastic metal plate is prepared, and the lower surface near the tip of the shaft presser plate 39 is elastically contacted with the upper side surface of the shaft 41, and in the vicinity of the root portion. Is fixed on the bottom surface portion 38 of the main body frame 35 with screws 39a, so that the shaft 41 is elastically moved downward by the shaft pressing plate 39. As a result, the press roller 33 is mounted and fixed in a state of being pressed against the transport roller 32 (see FIG. 3) disposed below the press roller 33.

  When the press roller 33 is in pressure contact with the transport roller 32, the nip release lever 45 falls in a substantially horizontal state above the paper transport path 31 on the downstream side of the transport of the shaft 41 as shown in FIGS. At the nip position. In this state, as shown in FIG. 6, the shaft 41 that is springed downward by the shaft pressing plate 39 is positioned in the lower part of the vertically long shaft insertion hole 52 a. At this time, the lower surface of the nip release lever 45 is disposed above the bottom of the paper transport path 31 (the upper surface of the inner guide 30) with a predetermined gap therebetween. Thus, the lower surface of the nip release lever 45 (specifically, the lower surface of the reinforcing rib 45b formed on the nip release lever 45) is configured to form a part of the upper portion (ceiling surface) of the paper transport path 31.

  In the image forming apparatus 1, the press roller 33 and the parts to which the press roller 33 is assembled are integrally configured as a press roller assembly 40, so that the fixture 50 can be attached to the main body frame 35 (image forming apparatus 1) of the image recording apparatus 5. The press roller 33 can be assembled simply by mounting and fixing to the main body). Therefore, it becomes easy to perform the assembling work and the detaching work of the press roller 33, and the work efficiency is improved. In addition, since the pair of fixtures 50, 50 are configured to be fixed to the main body frame 35 by fastening one screw 37, the press roller 33 can be more easily assembled and the press roller 33 can be securely attached. It becomes possible to fix to. Further, since the press roller assembly 40 is integrally provided with a nip release lever 45 for releasing the nip of the press roller 33, the nip release mechanism can be installed by assembling the press roller assembly 40, and the nip release is performed. Assembling work of the press roller 33 having the mechanism can be easily performed.

  Here, the nip releasing operation of the press roller 33 will be described. FIG. 7 is a diagram for explaining the procedure of the nip releasing operation. As shown in FIGS. 5 and 6 above, when the nip release lever 45 falls from the nip position where the shaft 41 has fallen to the downstream side of the conveyance of the shaft 41 and the nip release lever 45 is turned upward by putting a finger on the nip release lever 45, FIG. As shown, the abutment portion 47 of the nip release lever 45 abuts on and rides on the guide portion 53 of the fixture 50. At that time, the shaft 41 inserted into the shaft insertion hole 52 a of the nip release lever 45 is lifted upward against the elastic force of the shaft pressing plate 39 as the nip release lever 45 is lifted by rotation. . As a result, the press roller 33 is separated from the conveying roller 32 and the pressure contact (nip) is released.

  As described above, when the nip release lever 45 rotates around the shaft 41, the nip release lever 45 rides on the guide portion 53 provided on the fixture 50, thereby lifting the shaft 41 and releasing the nip of the press roller 33. The nip release lever 45 can be caused by force, and the nip can be reliably released even if the force for operating the nip release lever 45 is small, so that the nip release operability can be improved.

Further, in this press roller assembly 40, a locking mechanism for locking the nip release lever 45 to the fixture 50 at the nip release position (the shaft 41 is pushed downward (conveying roller 32 side) by the elastic force of the shaft pressing plate 39). A locking piece 54 is provided as a locking mechanism that prevents the nip release lever 45 from returning to the nip position . As a result, the raised nip release lever 45 is brought into contact with and locked by the locking piece 54 at the nip release position shown in FIG. 7, so that the press roller 33 can be stopped in the nip release state where it is lifted upward. it can. Therefore, it is possible to improve convenience when processing such as a paper jam at the nip portion of the transport roller 32 and the press roller 33 is performed. Further, as shown in the figure, the nip release lever 45 locked by the locking piece 54 has its nip position (as shown in FIGS. 5 and 6, the nip release lever 45 is located on the downstream side of the conveyance of the shaft 41. The rising angle (rotation angle around the shaft 41 from the horizontal position ) from a substantially horizontal state (see paragraph 0029) above the sheet conveyance path 31 is configured to be less than 90 degrees. Therefore, even if the nip release lever 45 is forgotten to be returned when the nip release operation is performed and the developer unit 14 is mounted as it is, the nip release lever 45 is pushed at the bottom of the developer unit 14. Thus, it is automatically returned to the nip position shown in FIG. Accordingly, it is possible to prevent the occurrence of troubles and failures such as the catching of parts.

  In addition, as described above, when the press roller 33 is in the nip state, the nip release lever 45 is configured to form a part of the paper transport path 31, so that the paper transport path can be simplified without increasing the number of parts. The paper transported 31 can be protected by a part of the paper transport path 31 configured by the nip release lever 45.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims, the specification, and the drawings. Is possible. It should be noted that any shape, structure, and material not directly described in the specification and drawings are within the scope of the technical idea of the present invention as long as the effects and advantages of the present invention are exhibited. For example, the specific shapes and the like of the fixture 50 and other components provided in the press roller assembly 40 are not limited to those shown in the above embodiment, and other shapes and the like can also be used. In addition, as the transport roller to which the press roller included in the press roller assembly of the present invention is pressed, any transport roller that transports the paper installed in the image recording apparatus may be installed in another part of the paper transport path. The conveyance roller may be used.

1 is a perspective view illustrating an overall configuration example of an image forming apparatus including a paper transport mechanism according to an embodiment of the present invention. It is a perspective view which shows the state which opened the upper cover of the image recording device. It is a sectional side view which shows the detailed structural example inside an image recording device. It is a side view which shows the structural example of a press roller assembly. It is a partial expansion perspective view which shows the attachment state of a press roller assembly. It is a schematic side view which shows a press roller assembly, and is a figure which shows the state which has a nip release lever in a nip position. It is a schematic side view which shows a press roller assembly, and is a figure which shows the state which has a nip release lever in a nip release position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Reading part 3 Recording part 4 Automatic document feeder (ADF apparatus)
5 Image Recording Device 8 Operation Panel 9 Main Body Cover 10 Upper Cover 10a Document Discharge Tray 11 Document Supply Tray 12 Intermediate Cover 13 Process Unit 14 Developer Unit 15 Photosensitive Unit 16 Photosensitive Drum 17 Transfer Roller 18 Charging Roller 19 Toner Chamber 20 Developing roller 21 Toner supply roller 22 Fixing unit 23 Heat roller 24 Press roller 25 Discharge roller 26 Press roller 27 LED head 30 Inner guide (bottom of paper conveyance path)
31 Paper transport path 32 Transport roller 33 Press roller 35 Main body frame 36 Side wall portion 37 Screw 38 Bottom surface portion 39 Shaft retainer plate 40 Press roller assembly 41 Shaft 45 Nip release lever 46 Mounting portion 46a Shaft insertion hole 47 Contact portion 50 Mounting tool 51 Main body portion 52 Shaft support portion 53 Guide portion 54 Locking piece (locking mechanism)

Claims (4)

A conveying roller, and a press roller which is pressed against the conveying roller, an image forming apparatus having a sheet conveying mechanism for conveying by nipping the sheet by the press-contact portion of the conveying roller and the press roller by the rotation of the conveying roller ,
A press roller assembly comprising the press roller, a shaft that supports the press roller, and a fixture that supports the shaft;
The press roller assembly can be incorporated into the image forming apparatus by fixing the pair of attachments to the main body frame of the image forming apparatus.
The press roller assembly includes: an elastic member that presses a shaft that supports the press roller toward the transport roller and presses the press roller against the transport roller to form a nip state; and the press roller and the transport roller A nip release lever that releases and separates the pressure contact,
One end of the nip release lever is rotatably attached to the shaft, the nip state is in a horizontal state, and the other end is lifted upward from the horizontal state and rotated about the shaft as the center. A contact portion that rides on a guide portion provided on the tool and lifts the shaft against the elastic force of the elastic member to release the press roller and the conveying roller to be separated and release the nip state; An image forming apparatus having a configuration . The image forming apparatus according to claim 1 .
An image is provided, wherein the fixture is provided with a locking mechanism that prevents the nip release lever from returning to the nip state by the elastic force of the elastic member when the nip state is released. Forming equipment. The image forming apparatus according to claim 2 .
An image forming apparatus , wherein a rising angle from the nip state of the nip release lever to a position where the operation of returning to the nip state by the locking mechanism is prevented is less than 90 degrees. The image forming apparatus according to claim 1, 2 or 3 .
An image forming apparatus, wherein the nip release lever forms a part of a sheet conveyance path in a nip state in which the press roller is pressed against the conveyance roller.

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