JP4890933B2 - Fixing apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus such as a copying machine and a printer provided with the fixing device, and more particularly to a wiring routing method inside the fixing device.

  In a conventional image forming apparatus, a predetermined electrostatic latent image in which charging is partially attenuated by irradiating a laser beam from an exposure unit onto an image carrier such as a photosensitive drum uniformly charged by a charging unit. After an image is formed and toner is attached to the electrostatic latent image by a developing unit to form a toner image, the toner image is transferred onto a recording medium using a transfer unit, and unfixed toner is heated and pressurized by a fixing device. Then, an image forming process for making a permanent image is executed.

  A configuration of a conventional fixing device is shown in FIG. The fixing device 15 includes an upper housing 15a and a lower housing 15b. The upper housing 15a stores a heating roller 20a that rotates clockwise in the figure, and the lower housing 15b counterclockwise. The rotating pressure roller 20b is accommodated. A heater 21 is built in the heating roller 20a, and the pressure roller 20b is pressed against the heating roller 20a with a predetermined pressure by an urging means (not shown). The heating roller 20a and the pressure roller 20b constitute a fixing roller pair 20 that fixes unfixed toner on the paper P passing through the fixing nip portion N.

  The sheet P on which the toner image has been transferred by the transfer roller (not shown) proceeds to the left in FIG. 8 and is carried into the fixing device 15 from the upstream opening 22a and passes through the fixing nip N of the fixing roller pair 20. To do. At this time, the toner image on the paper P is made a permanent image by being heated and pressurized at a predetermined temperature and pressure. Thereafter, the paper P is conveyed to the outside of the fixing device 15 from the downstream opening 22b, and is discharged to the outside of the image forming apparatus by a discharge roller (not shown). A fixing approach guide 23 is provided in the upstream opening 22 a, and the leading edge of the paper P is guided to the fixing nip portion N along the guide surface 23 a of the fixing approach guide 23.

  If the fixing device 15 as described above is detachable from the main body of the image forming apparatus, the jam processing when the paper is jammed around the fixing device 15 becomes easier. In that case, power is supplied to the electronic components such as the heater 21 in the heating roller 20a and the thermistor (not shown) for detecting the surface temperature of the heating roller 20a, or the electronic components and the image forming apparatus main body are connected to each other. In order to transmit and receive control signals between them, a wiring member (hereinafter referred to as a wire harness) and a drawer connector, which are integrally assembled components such as an electric wire and its connection terminals, as described in Patent Document 1. A method for simplifying the electrical connection between the fixing device 15 and the image forming apparatus main body is used.

  Conventionally, since the wiring path of the wire harness is provided separately from the fixing device main body, a separate wiring space is required, which hinders space saving of the image forming apparatus. In addition, there is a problem that the wire harness is caught by the peripheral member when the fixing device is attached / detached, and the attaching / detaching operation cannot be performed smoothly. On the other hand, when the wire harness is wired in the fixing device main body, it is possible to save space, but there is a possibility that the electrical resistance changes due to the heat radiation from the heating roller or the coating on the surface is melted.

  Accordingly, a method has been proposed in which the wire harness is prevented from being caught when the fixing device is attached and detached, and the wiring space of the wire harness can be omitted. For example, Patent Document 2 discloses a harness guide for holding the wire harness. There is disclosed a fixing device in which an L-shaped concave portion formed with is provided on the outer peripheral portion of the fixing housing, and the wire harness of the thermistor can be wired along the outer peripheral surface of the fixing housing.

However, in the method of Patent Document 2, since it is necessary to form a harness guide and an L-shaped concave portion, the shape of the fixing housing becomes complicated. Further, since the L-shaped recess is formed in the upper part of the fixing housing relatively close to the heating roller, it is difficult to completely block the influence of heat radiation from the heating roller. Further, since the wire harness is exposed to the outside, the wire harness may be damaged when the fixing device is attached or detached.
JP-A-6-318003 Japanese Patent Laid-Open No. 2004-199094

  SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a fixing device capable of protecting a wire harness from heat radiation of a heating roller, saving space, and facilitating attachment / detachment operations, and an image forming apparatus including the same. And

  In order to achieve the above object, the present invention accommodates and conveys a fixing roller pair comprising a heating roller incorporating a heater, and a pressure roller pressed against the heating roller with a predetermined pressure. A housing having openings formed on the upstream side and the downstream side in the direction, and a fixing approach guide that guides a recording medium that is conveyed and protrudes from the opening on the upstream side of the housing to the nip portion of the fixing roller pair And a wire harness serving as a path of electric power or an electric signal necessary for the operation of the heater and the electronic components inside the apparatus, and forming a wiring path of the wire harness on the back side of the fixing entrance guide It is characterized by that.

  According to the present invention, in the fixing device configured as described above, the fixing approach guide protrudes on the pressure roller side of the opening.

  According to the present invention, in the fixing device configured as described above, a cover member that covers the wiring passage is provided.

  According to the present invention, in the fixing device configured as described above, the wiring passage is provided with a heat insulating layer on an inner surface of the fixing roller opposite side.

  According to the present invention, in the fixing device having the above-described configuration, the heat insulating layer is a hollow portion formed integrally with a cover member that covers the wiring passage.

  According to the present invention, in the fixing device configured as described above, the fixing approach guide and the wiring passage are integrally formed with the housing.

  The present invention also provides an image forming apparatus provided with the above-described fixing device in a detachable manner.

  According to the first configuration of the present invention, since the wiring path of the wire harness can be secured using the empty space on the back side of the fixing approach guide, the fixing device can be reduced in weight and space can be saved with a simple configuration. be able to. Further, since the housing and the fixing approach guide are interposed between the fixing roller pair and the wire harness, the influence of heat radiation from the heating roller can be suppressed.

  Further, according to the second configuration of the present invention, in the fixing device of the first configuration, since the fixing passage guide is protruded on the pressure roller side, the wiring passage is also formed on the pressure roller side. The distance from the heating roller to the wire harness can be increased, and the influence of heat radiation from the heating roller can be more effectively suppressed.

  According to the third configuration of the present invention, in the fixing device having the first or second configuration, the cover member that covers the wiring path is provided, so that the wire harness is covered with the wiring path and the cover member and is externally provided. Therefore, the wire harness can be protected more effectively.

  According to the fourth configuration of the present invention, in the fixing device having the first or second configuration, the heat insulating layer is provided on the inner surface of the fixing roller pair side in the wiring passage, so that the radiation is emitted from the fixing roller pair. The influence of heat can be suppressed more reliably.

  According to the fifth configuration of the present invention, in the fixing device according to the fourth configuration, the hollow portion formed integrally with the cover member that covers the wiring passage is used as the heat insulating layer, so that heat is radiated from the fixing roller pair. It is possible to reduce the number of parts and the number of assembly steps.

  According to the sixth configuration of the present invention, in the fixing device having any one of the first to fifth configurations, the fixing approach guide and the wiring passage are integrally formed with the housing of the fixing device, so that the number of parts and Assembly man-hours can be further reduced.

  Further, according to the seventh configuration of the present invention, since the fixing device having any one of the first to sixth configurations is detachably mounted, there is no possibility that the wire harness is caught by the peripheral member. Thus, the image forming apparatus can smoothly perform the jamming operation around the fixing device and can suppress the deterioration of the wire harness due to the heat of the fixing roller pair.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing the internal structure of an image forming apparatus equipped with a fixing device of the present invention. In an image forming apparatus (for example, a printer) 100, when performing an image forming operation, a photosensitive drum 5 that rotates clockwise in the drawing is uniformly charged by a charging unit 4, and an exposure unit (laser scanning unit) based on document image data. Etc.) An electrostatic latent image is formed on the photosensitive drum 5 by the laser beam from 7, and a developer (hereinafter referred to as toner) is attached to the electrostatic latent image by the developing unit 8 to form a toner image.

  The toner is supplied to the developing unit 8 from the toner container 9. The image data is transmitted from a personal computer (not shown) or the like. Further, a static elimination device (not shown) for removing residual charges on the surface of the photosensitive drum 5 is provided on the downstream side of the cleaning device 19.

  A sheet is conveyed from the sheet feeding cassette 10 or the manual sheet lay 11 via the sheet conveying path 12 and the registration roller pair 13 toward the photosensitive drum 5 on which the toner image is formed as described above, and the transfer roller 14. The toner image formed on the surface of the photosensitive drum 5 is transferred onto the sheet by (image transfer unit). The sheet on which the toner image has been transferred is separated from the photosensitive drum 5 and conveyed to the fixing device 15 to fix the toner image. The sheet that has passed through the fixing device 15 is conveyed to the upper part of the apparatus by the sheet conveying path 16 and is discharged to the discharge tray 18 from the discharge roller pair 17.

  FIG. 2 is a side sectional view of the fixing device according to the first embodiment of the present invention, and FIG. 3 is a perspective view of the fixing device of the first embodiment viewed from the back side. Portions common to FIG. 8 of the conventional example are denoted by the same reference numerals and description thereof is omitted. The fixing device 15 is supported on the left and right fixing rails 26a and 26b, and an image is obtained by pulling out or inserting the fixing rails 26a and 26b together with the fixing device 15 in parallel to the sheet conveyance direction (left and right direction in FIG. 1). It can be detached from the forming apparatus 100 (see FIG. 1). A drawer connector 27 connected to a connector (not shown) on the apparatus main body side is disposed in the lower housing 15b.

  In the fixing device 15 of the present embodiment, a wiring passage 24 is provided in a space on the back surface side of the fixing approach guide 23 formed integrally with the lower housing 15 b, and the drawer connector 27 and the inside of the fixing device are provided along the wiring passage 24. A plurality of wire harnesses 25 for electrically connecting electronic components are wired. A plurality of harness guides 28 are provided in the wiring passage 24, and the wire harness 25 is bundled by the harness guide 28 and held so as not to hang down. In FIG. 3, the wire harness 25 is not shown.

  By adopting this configuration, it is possible to secure the wiring path 24 without using a separate member or complicating the shape of the housing by utilizing the empty space on the back surface side of the fixing approach guide 23, so that the weight of the fixing device can be reduced. Space saving can be realized with a simple configuration. Further, since there is no possibility that the wire harness is caught by the peripheral members when the fixing device is attached or detached, the fixing device can be pulled out and inserted smoothly.

  Further, as shown in FIG. 2, since the wiring passage 24 is provided outside the lower housing 15b, the distance from the fixing roller pair 20 to the wire harness 25 can be increased, and the fixing roller pair 20 and the wire harness 25 Since the lower housing 15b and the fixing approach guide 23 are interposed between them, the influence of heat radiation from the heating roller 20a can be suppressed. As the material of the upper and lower housings 15a and 15b and the fixing approach guide 23, PET (polyethylene terephthalate) containing glass fiber or the like is used. In order to keep the wire harness 25 as far as possible from the heating roller 20a, it is preferable to provide the harness guide 28 along the upstream side (the right side in FIG. 2) in the sheet conveyance direction in the wiring path 24.

  4 is a side sectional view of a fixing device according to a second embodiment of the present invention, and FIG. 5 is a perspective view of the fixing device of the second embodiment as viewed from the back side. In the present embodiment, a cover member 30 that covers the opening of the wiring passage 24 is provided, and the wire harness 25 is held in a wiring passage 24 that is formed in a cylindrical shape by the lower housing 15 b and the cover member 30. Other configurations are the same as those of the first embodiment.

  With this configuration, since the wire harness 25 is not exposed to the outside, the wire harness 25 can be more effectively protected when the fixing device 15 is pulled out and inserted. Moreover, even if the wire harness 25 falls off from the harness guide 28, there is no possibility that the wire harness 25 will hang downward by the cover member 30, so that it is possible to reliably prevent the peripheral member from being caught.

  FIG. 6 is a side sectional view of a fixing device according to a third embodiment of the present invention. In the present embodiment, a heat insulating material 31 is attached along the inner wall surface of the wiring passage 24 on the pressure roller 20b side. Other configurations are the same as those of the second embodiment.

  With this configuration, the lower housing 15b and the heat insulating material 31 are interposed between the fixing roller pair 20 and the wire harness 25, and the influence of heat radiated directly from the heating roller 20a or through the pressure roller 20b is affected. It becomes possible to suppress more reliably. Therefore, compared with the structure of 2nd Embodiment, the change of the electrical resistance of the wire harness 25 and the melt | dissolution of surface coating | cover can be prevented more effectively. As the heat insulating material 31, a heat insulating material made of an inelastic material such as glass fiber material or ceramic, or a heat insulating material made of an elastic material such as polyester sponge or urethane rubber is used.

  FIG. 7 is a side sectional view showing another configuration example of the fixing device according to the third embodiment. In FIG. 7, the cover member 30 has an L-shaped cross section, and a hollow portion 32 is provided in a portion along the inner wall surface of the wiring passage 24 on the pressure roller 20 b side. The hollow portion 32 plays the role of a heat insulating layer instead of the heat insulating material 31, thereby effectively suppressing the influence of heat radiation from the fixing roller pair 20 as in the configuration of FIG. Moreover, since the hollow part 32 is integrally formed with the cover member 30, compared with the structure of FIG. 6 which arrange | positions the heat insulating material 31, it becomes possible to reduce a number of parts and an assembly man-hour.

  In each of the above embodiments, the heating roller 20a is arranged in the upper housing 15a and the pressure roller 20b is arranged in the lower housing 15b. However, the arrangement of the heating roller 20a and the pressure roller 20b is reversed. May be. However, in order to keep the wiring passage 24 away from the heating roller 20a, it is preferable to arrange the heating roller 20a in the upper housing 15a. Further, in the case of a vertical conveyance type image forming apparatus in which the heating roller 20a and the pressure roller 20b are arranged substantially horizontally and the sheet is conveyed from below to above, the fixing entry guide 23 and A wiring passage 24 may be provided.

  In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in each of the embodiments described above, the fixing approach guide 23 is integrally formed with the lower housing 15b. However, the fixing approach guide 23 may be attached as a separate member as shown in FIG. Further, a housing in which the upper housing 15a and the lower housing 15b are integrally formed and provided with openings on the upstream side and the downstream side may be used as the housing of the fixing device. Furthermore, when the cover member 30 is provided as in the second and third embodiments, the harness guide 28 is not necessarily provided.

  Although the image forming apparatus configured to pull out the fixing device 15 horizontally in the sheet conveyance direction has been described here, the method for attaching and detaching the fixing device is not limited to this, and may be configured to be attached and detached in the vertical direction, for example. . The present invention is not limited to a printer, but can be applied to other types of image forming apparatuses such as monochrome and color copiers, digital multi-function peripherals, and facsimiles. It can be suitably used for an image forming apparatus.

  The present invention includes a fixing roller pair composed of a heating roller having a built-in heater, and a pressure roller pressed against the heating roller with a predetermined pressure, and accommodates the fixing roller pair and is disposed upstream and downstream in the conveying direction. A housing in which an opening is formed, a fixing intrusion guide that protrudes from an opening on the upstream side of the housing and guides a conveyed recording medium to a nip portion of a fixing roller pair, a heater, and an electronic component inside the apparatus In the fixing device provided with a wire harness serving as a path of electric power or an electric signal required for the operation of the wire harness, a wiring path of the wire harness is formed on the back surface side of the fixing approach guide.

  As a result, the wiring path of the wire harness can be secured by using the empty space on the back side of the fixing entrance guide that is separated from the fixing roller pair by the housing, so that damage to the wire harness due to heat radiation from the heating roller is suppressed. In addition, a fixing device capable of realizing weight reduction and space saving can be provided simply and at low cost. Further, when the fixing approach guide and the wiring path are provided on the pressure roller side, the distance between the heating roller and the wire harness can be increased, and the influence of heat radiation can be more effectively suppressed.

  Moreover, since the cover member which covers a wiring channel | path so that a wire harness is not exposed outside is provided, a wire harness can be protected more effectively.

  In addition, since the heat insulating layer is provided in the wiring passage, the influence of heat radiated from the fixing roller pair can be more reliably suppressed. If this heat insulating layer is formed as a hollow portion and formed integrally with a cover member that covers the wiring passage, the number of parts and the number of assembly steps can be reduced, which contributes to the cost reduction of the fixing device.

  Further, since the fixing approach guide and the wiring passage are integrally formed with the housing, the fixing device can be simply configured with the number of parts and the number of assembly steps further reduced.

  Further, since the fixing device of the present invention is detachably mounted on the image forming apparatus, the deterioration of the wire harness due to the heat of the fixing roller pair can be suppressed, and there is no possibility that the wire harness is caught by the peripheral member. The image forming apparatus can easily handle peripheral jams.

These are side cross-sectional views showing the internal structure of an image forming apparatus equipped with the fixing device of the present invention. FIG. 3 is a side sectional view of the fixing device according to the first embodiment of the present invention. FIG. 2 is a perspective view of the fixing device of the first embodiment as viewed from the back side. These are side surface sectional drawings of the fixing device concerning a 2nd embodiment of the present invention. These are the perspective views which looked at the fixing device of 2nd Embodiment from the back surface side. These are side surface sectional drawings of the fixing device which concerns on 3rd Embodiment of this invention. These are side surface sectional drawings which show the other structural example of the fixing device of 3rd Embodiment. FIG. 6 is a side sectional view of a conventional fixing device.

Explanation of symbols

15 Fixing device 15a Upper housing (housing)
15b Lower housing (housing)
20 Fixing Roller Pair 20a Heating Roller 20b Pressure Roller 21 Heater 22a Upstream Opening 22b Downstream Opening 23 Fixing Approach Guide 24 Wiring Path 25 Wire Harness 26a, 26b Fixing Rail 27 Drawer Connector 28 Harness Guide 30 Cover Member 31 Heat Insulating Material (Insulation layer)
32 Hollow part (heat insulation layer)
100 printer

Claims (6)

A fixing roller pair comprising a heating roller having a built-in heater and a pressure roller pressed against the heating roller with a predetermined pressure;
A housing that houses the fixing roller pair and has openings formed on the upstream side and the downstream side in the transport direction;
A fixing intrusion guide that protrudes on the pressure roller side of the opening on the upstream side of the housing and guides the conveyed recording medium to the nip portion of the fixing roller pair;
In the fixing device comprising the heater and a wire harness that is a path of electric power or an electric signal necessary for the operation of the electronic components inside the device,
Fixing along said longitudinal direction of the housing on the back face of the entry guide to form the wire passage of the wire harness, the paper conveying direction upstream side of the plurality of harness guiding the wiring passage for retaining a bundle of the wire harness A fixing device provided along a longitudinal direction of the housing at a position close to an inner wall surface of the housing . The fixing device according to claim 1, further comprising a cover member that covers the wiring path . The fixing device according to claim 1 , wherein the wiring passage is provided with a heat insulating layer on an inner surface of the fixing roller opposite side . The fixing device according to claim 3 , wherein the heat insulating layer is a hollow portion formed integrally with a cover member that covers the wiring passage . The fixing entrance guide and the wiring passage, fixing device according to any one of claims 1 to 4, characterized in said housing and being integrally formed. An image forming apparatus comprising the fixing device according to claim 1 detachably.

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