JP2013083968A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which is light in weigh, having high operability.SOLUTION: The image forming device comprises: heating means for fixing a toner image unfixed on a recording medium; a pressure roller for pressing the heating means; a cleaning blade 76 for cleaning the surface of the pressure roller by bringing one lateral end thereof in contact with the pressure roller; a leaf spring 77 connected to the side of the other lateral end of the cleaning blade which is elastic for biasing the one end of the cleaning blade onto the surface of the pressure roller; a receiving part with a mounting face overlapping with the leaf spring for storing foreign materials shaved off from the surface of the pressure roller by the cleaning blade; and a fixing part for fixing the mounting face of the receiving part and the leaf spring. The length of a fixing part holding shaft including the fixing part, along the lateral direction of the leaf spring, is shorter than the length of a fixing part non-holding shaft excluding the fixing part in the area of the mounting face of the receiving part overlapping with the leaf spring.

Description

  Embodiments described herein relate generally to an image forming apparatus including a fixing device that heats and fixes a toner image transferred onto a sheet.

  A conventional fixing device of an image forming apparatus includes a cleaning unit for removing toner adhering to the surface of a pressure roller in order to prevent unnecessary toner from adhering to a paper surface to be fixed. is there. One end of a cleaning blade provided in the cleaning unit is brought into sliding contact with the pressure roller, and the toner adhering to the surface of the pressure roller when the pressure roller rotates is scraped off and removed.

  The cleaning unit requires a member such as an elastic body for adjusting the load for sliding the cleaning blade on the pressure roller, and a plate for connecting the elastic body and the cleaning blade, which increases the cost. . In order to avoid this, a leaf spring is used, and an elastic body and a plate are unnecessary. However, since such a cleaning unit directly fixes the leaf spring to the case with a screw or the like, the load for sliding the cleaning blade on the pressure roller is different between the portion with and without the screw, and the load is equal. It will be difficult to multiply.

JP 2007-292841 A

  The problem to be solved by the present invention is to provide an image forming apparatus which is inexpensive and can stably perform cleaning of a pressure roller with an appropriate load.

In order to solve the above problems, an image forming apparatus according to an embodiment includes a heating unit that fixes an unfixed toner image on a recording medium, a pressure roller that pressurizes the heating unit, A cleaning blade for cleaning the surface of the pressure roller by contacting one end in the direction, and an elasticity for biasing one end of the cleaning blade against the surface of the pressure roller, connected to the other end in the short direction of the cleaning blade. A plate spring having a mounting surface that overlaps with the plate spring, receiving a foreign object scraped off from the pressure roller surface by the cleaning blade, the mounting surface of the receiving unit, and the plate spring And a fixing part for fixing
In the region of the mounting surface of the receiving portion that overlaps the plate spring, the length of the fixed portion holding shaft including the fixed portion along the short direction of the plate spring is not fixed portion that does not include the fixed portion. It is characterized by being shorter than the length of the shaft.

1 is a perspective view of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of the image forming apparatus according to the embodiment. FIG. 3 is a perspective view of the fixing device according to the embodiment. FIG. 2 is an enlarged schematic diagram of a fixing device according to the embodiment. The disassembled perspective view of the cleaning unit of the embodiment.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the image forming apparatus according to the embodiment.

  As shown in FIGS. 1 and 2, the image forming apparatus includes an image forming apparatus main body 1A that forms the same image as the original on a sheet as a recording medium, and an original conveying unit 22 that conveys the original to the image forming apparatus main body 1A. And a plurality of paper feed cassettes 24 for supplying paper to the image forming apparatus main body 1A, and an operation panel 35 for controlling them. Further, on the side surface of the image forming apparatus main body 1A, an automatic duplex device 29 used for duplex copying is provided so as to be openable and closable so as to be adjacent to the transport unit 19 shown in FIG. Is provided with a manual paper feed unit 32 used during manual paper feed.

  The image forming apparatus main body 1A has a rectangular box shape, and as shown in FIG. 2, an image forming unit 1 is provided therein. The image forming unit 1 forms an electrostatic latent image on the photosensitive drum 2, a charger 5 that charges the photosensitive drum 2 to a predetermined potential, and the photosensitive drum 2 that is charged by the charger 5. An exposure device 4, a rotary developing device 8 </ b> A for supplying color to the electrostatic latent image formed on the photosensitive drum 2 by the exposure device 4 for visualization, and fixed development for supplying black toner for monochrome An apparatus 8B, an intermediate transfer belt 3 that temporarily holds a toner image formed on the photosensitive drum 2 by each of the developing devices 8A and 8B, a cleaner 6a that removes toner adhering to the intermediate transfer belt 3, And a cleaner 6b for removing toner adhering to the photosensitive drum 2.

  The rotary developing device 8A includes a first developing unit 8a that supplies yellow toner, a second developing unit 8b that supplies cyan toner, and a third developing unit 8c that supplies magenta toner. .

  The intermediate transfer belt 3 is stretched between the first to fourth rollers 3 a to 3 d with a predetermined tension, and a portion spanned between the second and third rollers 3 b and 3 c is the portion of the photosensitive drum 2. It is in contact with the outer peripheral surface. A primary transfer roller 12 is disposed above the photosensitive drum 2 so as to press the intermediate transfer belt 3 against the outer peripheral surface of the photosensitive drum 2.

  Further, a conveyance unit 19 is provided inside the image forming apparatus main body 1A. The transport unit 19 transports the paper supplied from the paper feed cassette 24 to the discharge tray 31 via the image forming unit 1, and in the paper transport direction (see arrow A in FIG. 2). A pair of conveyance rollers 9, a registration roller 17, a secondary transfer roller 11, and a discharge roller pair 30 are provided in this order.

  The registration roller 17 temporarily stops the conveyed sheet, corrects the inclination of the sheet with respect to the conveyance direction, adjusts the timing of conveying the sheet to the transfer position of the toner image on the intermediate transfer belt 3, The leading edge of the paper is aligned with the leading edge of the toner image on the intermediate transfer belt 3.

Further, an optical reading device 26 that optically reads a document on the document table 28 is provided on the upper side of the image forming apparatus main body 1A.
The paper feed cassette 24 is provided on the lower side of the image forming apparatus main body 1A, and a predetermined size paper (recording paper) is set therein. Each of the plurality of paper feed cassettes 24 is provided with a pickup roller 7 for taking out paper. The paper taken out by the pickup roller 7 is separated one by one by the paper feed roller 15 and the separation roller 16 and is supplied to the transport unit 19. The paper supplied to the transport unit 19 is transported between the intermediate transfer belt 3 and the secondary transfer roller 11. The secondary transfer roller 11 is electrically attracted from the back side of the sheet, and secondarily transfers the toner image formed on the intermediate transfer belt 3 to the sheet. The sheet on which the toner image is secondarily transferred is peeled off from the intermediate transfer belt 3 and conveyed to a fixing device 13 described later. Thereafter, the toner image is fixed by heating and pressurizing the paper. The sheet on which the toner image is fixed is conveyed to a paper discharge unit.

  A fixing device 13 is provided on the downstream side of the conveyance unit 19 in the sheet conveyance direction. The fixing device 13 is for fixing the toner image transferred onto the paper by heating.

  Hereinafter, the configuration of the fixing device 13 will be described.

  3 is a perspective view of the fixing device 13 according to the embodiment, and FIG. 4 is an enlarged schematic view of the fixing device 13 according to the embodiment.

  As shown in FIG. 3, the fixing device 13 has a metal frame 70. The frame 70 includes first and second frames 71 and 71 and second frames 72 and 72 (supporting means) that are rotatably connected to each other. As shown in detail in FIG. A heating roller (heating means) 13a, a peeling roller 13c, an oil roller 13d, and a cleaning roller 13e are rotatably supported between the frames 71 and 71, and a pressure roller 13b is interposed between the second frames 72 and 72. It is rotatably supported.

  The peeling roller 13c is disposed downstream of the heating roller 13a in the sheet conveyance direction (the direction of arrow A in FIG. 4), and a fixing belt 14 that is a heat-resistant flat belt is hung on the heating roller 13a and the peeling roller 13c. Has been passed. A driving device (not shown) is connected to the peeling roller 13c. By driving the driving device and rotating the peeling roller 13c, the fixing belt 14 can circulate between the heating roller 13a and the peeling roller 13c. It is like that.

  Inside the heating roller 13a, for example, a heating device 27 including a heater or a heating lamp is provided. The heating device 27 is located at the radial center of the heating roller 13a and heats the fixing belt 14 to about 200 [° C.].

  The pressure roller 13b is in pressure contact with the outer peripheral surface of the heating roller 13a via the fixing belt 14, and presses the conveyed paper against the heating roller 13a.

  The oil roller 13 d is in contact with the outer peripheral surface of the fixing belt 14, supplies oil to the surface of the fixing belt 14, and wipes off unfixed toner adhering to the surface of the fixing belt 14.

  The cleaning roller 13e is in contact with the outer peripheral surface of the oil roller 13d, and cleans the oil roller 55 by removing unfixed toner wiped off from the fixing belt 14 by the oil roller 55.

  As shown in FIG. 3, springs 73 and 73 are provided between the first frames 71 and 71 and the second frames 72 and 72. These springs 73, 73 urge the second frames 72, 72 toward the first frames 71, 71, and are heated by pulling a release lever 74 provided on the second frame 72. A gap for removing jammed paper can be formed between the roller 13a and the pressure roller 13b.

  A peeling blade 20 is disposed downstream of the peeling roller 13c in the paper conveyance direction. One end of the peeling blade 20 is abutted against the outer peripheral surface of the peeling roller 13c with a slight gap, so that the paper discharged from the fixing device 13 can be peeled from the fixing belt 14. ing.

  A peeling claw 57 is disposed on the downstream side of the pressure roller 13b in the sheet conveying direction. One end of the peeling claw 57 is abutted against the outer peripheral surface of the pressure roller 13b with a slight gap therebetween, so that the paper on which the image is fixed can be peeled from the pressure roller 13b. ing.

  A cleaning unit 75 is provided in the vicinity of the pressure roller 13b. The cleaning unit 75 is for removing dirt such as the toner 51 adhering to the outer peripheral surface of the pressure roller 13b, and includes a cleaning blade 76, a plate spring 77, a holding case 78 as a receiving portion, and a plate spring 77. A screw 79 as a fixing portion to the holding case 78 is provided.

  FIG. 5 is an exploded perspective view of the cleaning unit 75 of the same embodiment. The arrow indicates the pressing direction.

  As shown in FIGS. 4 and 5, the cleaning unit 75 has a plate spring 77 attached in the short direction of the cleaning blade 76 and is attached with two screws 79 at a portion where the plate spring overlaps the holding case 78. It is configured, and is detachably attached to second frames 72 and 72 (see FIG. 3) as attachment portions to which the holding case 78 can be attached. Although the number of screws 79 is two here, it may be appropriately changed depending on the case.

  Even if the second frames 72 and 72 as the attachment portions pull the release lever 74 to form a gap for removing jammed paper between the heating roller 13a and the pressure roller 13b, the second frame 72 and 72 is pressurized with the cleaning unit 75. The relative position of the roller 13b does not change, and there is an advantage that the position accuracy is maintained.

  Note that the attachment portion to which the holding case 78 is attached may be another portion as long as it is provided in the fixing device.

  The cleaning blade 76 is made of a long member formed in a plate shape, and for example, a urethane plate is used. One end portion in the short direction is bonded to the plate spring 77 with an adhesive or the like, and the other end portion is in contact with the pressure roller 13b by the load of the plate spring 77. Further, a cleaning blade 76 and a holding case 78 are provided on different surfaces of the leaf spring 77, respectively.

  One end portion of the cleaning blade 76 in the short direction is in sliding contact with the outer peripheral surface of the pressure roller 13b, and the pressure roller 13b rotates to scrape dirt such as the toner 51 attached to the surface of the pressure roller 13b. It comes to be able to take.

  The length of the leaf spring 77 in the longitudinal direction is substantially equal to the length of the cleaning blade 76 in the longitudinal direction.

  The holding case 78 overlaps the leaf spring attached to the space 83 for receiving and holding the toner 51 and the like removed from the pressure roller 13 b by screws 79 at both longitudinal ends of the leaf spring 77. And an attachment surface 82. The length in the longitudinal direction of the mounting surface 82 is slightly longer than the length in the longitudinal direction of the leaf spring 77, so that the scraped toner is not missed.

  As shown in FIG. 5, when comparing the lengths of the line segments parallel to the short direction of the leaf spring 77 of the mounting surface 82 provided on the holding case 78, the axial length X including the screw 79 on the line segment. And the axial length Y in other cases. The axis length X of the shaft (or region) including the screw 79 on the line segment that is the fixed portion holding shaft 86 is the axis (or region) that does not include the screw 79 on the line segment that is the fixed portion non-holding shaft 87. Is shorter than the axial length Y.

  In the present embodiment, since the screws 79 are provided in the regions corresponding to both longitudinal ends of the leaf spring 77, the axial length Y of the region that is the central portion in the longitudinal direction of the leaf spring 77 is the region that is the both end portions. Is longer than the axial length X, X. That is, the effective length L is shortened toward the longitudinal center of the leaf spring 77. The effective length L here refers to the distance between the portion where the pressure roller 13b and the cleaning blade are in contact with the tip of the mounting surface 82 on the side of the cleaning blade 76 in the short direction.

  In addition, the effective length of both end portions which are still ends is longer than both end portions of the leaf spring 77. Thereby, it is also possible to prevent the peeling at both ends.

  The sliding contact pressure by the leaf spring 77 of the cleaning blade 76 against the pressure roller 13b is larger at the portion fixed by the screw 79 than at the portion not fixed. Therefore, by changing the length of the effective length, it is possible to contact the outer peripheral surface of the heating roller 13a with a constant pressure over the entire longitudinal direction of the cooling blade 76. Further, it is possible to uniformly clean dirt such as the toner 51 adhering to the outer peripheral surface of the heating roller 13a, and it is possible to prevent the oil on the outer peripheral surface of the pressure roller 13b from being scraped off locally. Therefore, it is possible to prevent the unnecessary toner 51 from adhering to the surface of the paper and the occurrence of unevenness in the image.

  Next, the printing operation of the above-described image forming apparatus will be described.

  First, paper is set in the document transport unit 22 and the copy button on the operation panel 35 is turned on. As a result, the document is conveyed to the document table 28 and an image is read by the optical reading device 26. At this time, the surface of the photosensitive drum 2 is uniformly charged by the charger 5 in parallel. Then, the charged photosensitive drum 2 is exposed according to the read information by the laser beam from the exposure device 4 to form an electrostatic latent image. The electrostatic latent image is sent to the fixed developing device 8B by the rotation of the photosensitive drum 2, and the black toner 51 is supplied from the fixed developing device 8B to be developed. This development processing is a case of a monochrome image. In the case of a color image, the development processing is further performed with color toner by the color rotary developing device 8A.

  The developed toner image is sent onto the intermediate transfer belt 3 by the rotation of the photosensitive drum 2 and is primarily transferred by the primary transfer roller 12. After passing through the transfer region, the photosensitive drum 2 is subjected to light neutralization by a static eliminator (not shown), and the toner remaining on the photosensitive drum 2 is cleaned by a cleaner 6b.

  At this time, the paper taken out from the paper feed cassettes 24, 24 is sent between the intermediate transfer belt 3 and the secondary transfer roller 11, and the toner image on the intermediate transfer belt 3 is secondarily transferred to the paper. When the secondary transfer is completed, the sheet is peeled from the intermediate transfer belt 3 and sent to the fixing device 13. In the fixing device 13, the unfixed toner on the paper is heated and pressed by the heating roller 13a and the pressure roller 13b, and the toner image is fixed on the paper. The series of printing operations is thus completed.

  During the printing operation, oil is supplied from the oil roller 13d to the fixing belt 14 so that unfixed toner on the paper is less likely to adhere to the fixing belt 14. As a result, even if a printing operation is performed on a large number of sheets, the fixing belt 14 is kept clean, so that unnecessary toner is transferred to the surface of the sheet and is prevented from becoming dirty.

  During the printing operation, as shown in FIG. 4, one end of the cleaning blade 76 is in sliding contact with the outer peripheral surface of the pressure roller 13b with a uniform urging force. As a result, dirt such as the toner 51 adhering to the pressure roller 13b is scraped off by the cleaning blade 76, so that the outer peripheral surface of the pressure roller 13b is always kept clean.

  The dirt such as the toner 51 scraped off from the pressure roller 13b is accommodated in the holding case 78 supported by the second frames 72 and 72 via the leaf spring 77, and is removed during the subsequent maintenance. The sheet on which the toner image is fixed is guided by the guide unit 23 and discharged to the outside by the discharge roller pair 30. The sheets discharged to the outside are sequentially stacked on the discharge tray 31.

  In the present embodiment, the number of photosensitive drums has been described as one, but a quadruple tandem may be used.

  In the present embodiment, the cleaning unit 75 for scraping off the toner 51 on the surface of the pressure roller 13b has been described. However, the present invention can also be applied to other cleaners. Examples of other cleaners include a cleaner 6b that removes toner adhering to the photosensitive drum 2 and a cleaner 6a that removes toner adhering to the surface of the intermediate transfer belt 3.

  Further, in the present embodiment, one screw as a fixing portion is disposed at each of both end portions in the longitudinal direction of the leaf spring, but the present invention is not limited to this. The number and arrangement of the screws may be changed. The axial length of the fixed portion holding shaft (or region) 86 may be longer than the axial length X of the fixed portion non-holding shaft (or region) 87.

  According to the present embodiment described above, the use of a leaf spring eliminates the need for an elastic body for pressing the cleaning blade and a plate for transmitting the pressing force, thereby realizing cost reduction.

  Further, by changing the length of the effective length L, it is possible to contact the outer peripheral surface of the pressure roller 13b with a constant pressure over the entire longitudinal direction of the cleaning blade 76. Further, dirt such as the toner 51 attached to the outer peripheral surface of the pressure roller 13b can be uniformly cleaned, and the oil on the outer peripheral surface of the pressure roller 13b can be prevented from being scraped off locally. Therefore, it is possible to prevent the unnecessary toner 51 from adhering to the surface of the paper and the occurrence of unevenness in the image.

  Although an embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

13: Fixing device (heating means)
13b ... Pressure roller 76 ... Cleaning blade 77 ... Plate spring 78 ... Holding case (receiving part)
79 ... fixed portion 82 ... mounting surface 86 ... fixed portion holding shaft 87 ... fixed portion non-held shaft

Claims (2)

Heating means for fixing an unfixed toner image on the recording medium;
A pressure roller for pressing the heating means;
A cleaning blade for cleaning the surface of the pressure roller by bringing one end in a short direction into contact with the pressure roller;
A leaf spring connected to the other end in the short direction of the cleaning blade and having elasticity for urging one end of the cleaning blade toward the surface of the pressure roller;
A receiving portion that has a mounting surface that overlaps the leaf spring, and that contains foreign matter scraped off from the pressure roller surface by the cleaning blade;
A fixing portion for fixing the mounting surface of the receiving portion and the leaf spring;
In the region of the mounting surface of the receiving portion that overlaps the plate spring, the length of the fixed portion holding shaft including the fixed portion along the short direction of the plate spring is not fixed portion that does not include the fixed portion. An image forming apparatus characterized by being shorter than the length of a shaft.   The fixing portion is provided at both longitudinal end portions of the leaf spring, and the attachment surface overlapping the longitudinal center portion of the leaf spring is more than the attachment surface overlapping the longitudinal end portions of the leaf spring. The image forming apparatus according to claim 1, wherein a length of a line parallel to a short direction of the leaf spring is long.

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