JP2010066410A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can reduce the frequency of the occurrence of an abnormal image. <P>SOLUTION: The image forming apparatus includes: a transfer belt 5a for transferring a toner image which is held on a photoreceptor 1 onto transfer paper P and transporting the transfer paper P by electrostatic suction; a fixing unit 7 for fixing the toner image transferred on the transfer paper P that is transported by the transfer belt 5a onto the transfer paper P; and a separating guide plate 70 that is provided between the transfer belt 5a and the fixing unit 7 for guiding the transfer paper P to the fixing unit 7. The separating guide plate 70 is provided with a first member 71 which is arranged close to the transfer belt 5a and a second member 72 arranged apart from the transfer belt 5a and the resistance value of the first member 71 is made higher than that of the second member 72. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  Conventionally, a transfer belt that transfers a toner image onto a transfer paper and electrostatically attracts and conveys the transfer paper, a fixing device that fixes the toner image transferred onto the transfer paper to the transfer paper, and a gap between them are provided. There is also known an image forming apparatus that includes a guide member that guides a transfer sheet to a fixing device.

In this image forming apparatus, the surface resistivity of the transfer belt is 1 × 10 ¹³ to 1 × 10 ¹⁴ Ω, and the resistance value of the guide member is 1 × 10 ¹³ Ω or more. Accordingly, it is possible to prevent peeling discharge when the transfer paper is separated from the transfer belt, to suppress toner scattering to the guide member, and to prevent the transfer paper from leading and trailing edges (see Patent Document 1).
JP 2002-31960 A

However, in the conventional image forming apparatus, since the resistance value of the guide member is a relatively high value of 1 × 10 ¹³ Ω or more, frictional charging is easily caused by contact between the guide member and the transfer paper, and electric discharge occurs. As a result, an abnormal image like a bird's foot may be generated.

  Therefore, if a guide member having a low resistance is used, the following problem occurs in a high temperature and high humidity environment. In a high-temperature and high-humidity environment, the resistance value of the guide member decreases due to moisture, and the resistance value of the transfer belt also decreases. For this reason, a discharge is generated from the guide member to the transfer belt, and a bird's-foot-shaped abnormal image is generated by this discharge.

  SUMMARY An advantage of some aspects of the invention is to provide an image forming apparatus capable of reducing the occurrence frequency of abnormal images.

  In order to achieve the above object, an image forming apparatus according to the present invention transfers image information held on an image carrier onto a transfer paper, and electrostatically attracts and conveys the transfer paper. A fixing device for fixing image information transferred on the transfer paper conveyed by the transfer belt to the transfer paper, and a guide member provided between the transfer belt and the fixing device for guiding the transfer paper to the fixing device; The guide member includes a first member disposed close to the transfer belt and a second member disposed away from the transfer belt, and the resistance value of the first member is the resistance of the second member. It is characterized by being higher than the value.

  According to the image forming apparatus of the present invention, the guide member has the first member disposed close to the transfer belt and the second member disposed apart from the transfer belt, and the resistance of the first member It arrange | positions so that a value may become higher than the resistance value of a 2nd member. Here, in the image forming apparatus, due to the structure, the transfer paper is difficult to contact on the side close to the transfer belt, and the transfer paper is easy to contact on the side far from the transfer belt. For this reason, the guide member has a high resistance value at a portion where the transfer paper is difficult to contact, and has a low resistance value at a portion where the transfer paper is easy to contact. As described above, since the resistance value of the guide member is low at the portion where the transfer paper is easily contacted, frictional charging is difficult to occur, and generation of abnormal images due to frictional charging can be suppressed. In addition, since the guide member has a high resistance on the side close to the transfer belt, it is difficult for the transfer belt to discharge in a high-temperature and high-humidity environment, and abnormal image generation due to discharge to the transfer belt is suppressed. can do. As described above, the occurrence frequency of the abnormal image can be reduced.

  In the image forming apparatus, it is preferable that the first member and the second member are arranged in contact with each other on the surface of the guide member that guides the transfer paper.

  According to this image forming apparatus, the first member and the second member are arranged in contact with each other on the surface of the guide member that guides the transfer paper. For this reason, there is no step or gap between the first member and the second member, and even if the transfer paper contacts the first member and then contacts the second member, a discharge occurs at that time. Is prevented. Therefore, the occurrence frequency of abnormal images can be further suppressed.

  In the image forming apparatus, it is preferable that the second member is a conductive sheet attached on the first member.

  According to this image forming apparatus, since the second member is a conductive sheet affixed on the first member, the guide is affixed by affixing a conductive sheet to an existing guide member or the like. A member can be created, and the occurrence of abnormal images can be suppressed with a simple configuration.

In the image forming apparatus, the conductive sheet is preferably grounded via a resistor. In particular, when the resistance value of the conductive sheet is too low (for example, 1 × 10 ⁴ Ω or less), such a configuration may be taken.

According to this image forming apparatus, the conductive sheet is grounded via the resistor. For example, if a conductive sheet having a resistance value of about 1 × 10 ³ Ω is directly connected to the ground, a current suddenly flows from the guide member to the ground, and as a result, a bird's-foot-shaped abnormal image may occur. is there. However, by connecting the ground via a resistor, it is possible to prevent a current from abruptly flowing from the guide member to the ground, and to further suppress the occurrence frequency of abnormal images. The resistor preferably has a resistance value of 1 × 10 ⁷ to 1 × 10 ⁹ Ω.

In the image forming apparatus, the resistance value of the second member is preferably 1 × 10 ⁷ to 1 × 10 ⁹ Ω.

According to this image forming apparatus, the resistance value of the second member is set to 1 × 10 ⁷ to 1 × 10 ⁹ Ω. For this reason, the occurrence frequency of abnormal images can be most preferably suppressed.

In the image forming apparatus, the resistance value of the first member is preferably 10 ¹² Ω or more.

According to this image forming apparatus, since the resistance value of the first member is 10 ¹² Ω or more, the occurrence frequency of abnormal images can be most preferably suppressed.

  The image forming apparatus according to the present invention can reduce the frequency of occurrence of abnormal images.

  Hereinafter, the present invention will be described based on an embodiment of the present invention, but the present invention is not limited to the embodiment. FIG. 1 is an overall configuration diagram of an image forming apparatus according to the present embodiment. The image forming apparatus includes an image forming apparatus main body A, an image reading apparatus SC, an automatic document feeder DF, and a large capacity sheet feeder LT.

  The image forming apparatus main body A shown in FIG. 1 includes an image forming unit including a photoconductor (image carrier) 1, a charging unit 2, an exposure device 3, a developing device 4, a transfer unit 5, a cleaning unit 6, and the like, a fixing device 7 and a sheet. It is comprised from a conveyance part.

  The paper transport unit includes a paper feed cassette 10, a first paper feed unit 11, a second paper feed unit 12, a paper discharge unit 14, a transport path switching unit 15, a circulation refeed unit 16, and a reverse paper discharge unit 17. Has been.

  The document d placed on the document table of the automatic document feeder DF is transported by the paper feed unit, the image on one or both sides of the document d is read by the optical system of the image reading device SC, and read by the image sensor CCD. It is. The analog signal photoelectrically converted by the image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in the image processing unit 20 and then sent to the exposure apparatus 3.

  In the image forming unit, processes such as charging, exposure, development, transfer, separation, and cleaning are performed.

  In the image forming unit, the surface of the photoreceptor 1 is charged by the charging unit 2, an electrostatic latent image is formed by laser light irradiation from the exposure device 3, and the electrostatic latent image is visualized by the developing device 4, and toner Become a statue. Next, the transfer paper P stored in the paper feed cassette 10 is conveyed from the first paper feed unit 11. The transfer paper P is conveyed in synchronism with the toner image by the second paper feed unit 12 made of registration rollers. Thereafter, after the toner image (image information) is transferred by the transfer unit 5, the transfer paper P is conveyed to the fixing device 7 while being electrostatically adsorbed by the transfer belt 5 a that is a partial component of the transfer unit 5. The The fixing device 7 fixes the image information transferred onto the transfer paper P conveyed by the transfer belt 5a onto the transfer paper P.

  The fixed transfer paper P is discharged out of the apparatus by the paper discharge unit 14. On the other hand, the toner remaining on the photosensitive member 1 is removed by the cleaning unit 6. In the case of double-sided copying, the transfer paper P on which the image is formed on the first surface is sent to the circulation refeed unit 16 by the transport path switching unit 15 and reversed, and the image is again formed on the second surface in the image forming unit. After formation, the paper is discharged out of the apparatus by the paper discharge unit 14. In the case of reverse paper discharge, the transfer paper P branched from the normal paper discharge path is switched back and upside down in the reverse paper discharge unit 17 and then discharged outside the apparatus by the paper discharge unit 14.

  The large capacity sheet feeder LT is connected to the image forming apparatus main body A. The paper feeding device LT includes a paper feeding device main body 30, a first air blowing unit 40, a second air blowing unit 50, a suction conveyance unit 60, and the like, accommodates a large amount of transfer paper P, and transfers it to the image forming apparatus main body A. Paper P is fed one by one. The maximum paper feed capacity of the large capacity paper feeder LT is 10300 sheets.

  The sheet feeder main body 30 includes a sheet feed tray 31, a leading end regulating member 32, a trailing end regulating member 33, and a guide rail 34. The paper feed trays 31 are provided in three stages in the vertical direction, and each paper feed tray 31 is configured to be able to be pulled out from the paper feeder main body 30 by the guide rail 34. The leading edge regulating member 32 regulates the leading edge position of the transfer paper P in the feeding direction, and the trailing edge regulating member 33 regulates the trailing edge position of the transfer paper P in the feeding direction. The trailing edge regulating member 33 has a leading end protruding higher than the stacking height of the transfer paper P and serves to regulate the transfer paper P returned by the suction conveyance unit 60.

  The first air blower 40 and the second air blower 50 blow air from the direction along the feeding direction of the transfer paper P and the direction perpendicular to the transfer paper P. For example, when the transfer paper P is an OHP film, a trace paper, a coated paper with a smooth surface, a paper subjected to processing such as a perforation or a line push, or the like, When the dust is applied to the paper, the transfer paper P is separated by blowing air between the transfer paper P.

  Further, the image forming apparatus according to the present embodiment includes a separation guide plate (guide member) 70 between the transfer belt 5 a and the fixing device 7. The separation guide plate 70 guides the transfer paper P conveyed by the transfer belt 5 a to the fixing device 7. Further, the separation guide plate 70 is connected to the ground and plays a role of releasing the charge of the transfer paper P to the ground.

FIG. 2 is an enlarged view of a main part of the image forming apparatus according to the present embodiment. As shown in FIG. 2, the separation guide plate 70 includes a first member 71 disposed close to the transfer belt 5a, and a second member 72 disposed separately from the transfer belt 5a. The resistance values of the first member 71 and the second member 72 are different from each other, and the resistance value of the first member 71 is higher than the resistance value of the second member 72. Specifically, in the present embodiment, the resistance value of the first member 71 is 1 × 10 ¹² Ω, and the resistance value of the second member 72 is 1 × 10 ⁸ Ω.

  As shown in FIG. 2, the first member 71 and the second member 72 are arranged in contact with each other so as to be flush with each other. That is, the first member 71 and the second member 72 are integrated with each other without a step and without a gap.

FIG. 3 is an enlarged view showing another example of the separation guide plate 70 in the present embodiment. As shown in FIG. 3, the second member 72 may be a conductive sheet affixed on the first member 71. In this embodiment, the resistance value of the conductive sheet is as low as 1 × 10 ³ Ω. For this reason, if the conductive sheet is directly connected to the ground, a current suddenly flows from the separation guide plate 70 to the ground, and a bird's feet-like abnormal image is generated. Therefore, the conductive sheet is grounded via a resistor having a resistance value of 1 × 10 ⁸ Ω. In the example of FIG. 3, the first member 71 has a resistance value of 1 × 10 ¹² Ω, as in the example of FIG.

  Next, conveyance of the transfer paper P in the image forming apparatus according to the present embodiment will be described. First, the transfer paper P stored in the paper feed cassette 10 is conveyed from the first paper feed unit 11 to the second paper feed unit 12, and the second paper feed unit 12 synchronizes with the toner image. Thereafter, the transfer paper P is conveyed to the fixing device 7 side in a state where the toner image is transferred by the transfer unit 5 and electrostatically attracted by the transfer belt 5a.

  As shown in FIG. 2, the transfer paper P is conveyed from the transfer belt 5 a to the separation guide plate 70. Here, as shown in FIG. 2, the transfer paper P is unlikely to contact the first member 71 on the side close to the transfer belt 5a, and easily contacts the second member 72 on the side far from the transfer belt 5a. Therefore, the transfer paper P comes into contact with the second member 72 having a low resistance value, so that frictional charging is difficult to occur and abnormal images due to frictional charging are difficult to occur.

  In the separation guide plate 70, the resistance value of the first member 71 adjacent to the transfer belt 5a is high. For this reason, even if the resistance values of the first member 71 and the transfer belt 5a are lowered in a high-temperature and high-humidity environment, it is difficult for the transfer belt 5a to be discharged, and the occurrence of abnormal images due to the discharge to the transfer belt 5a is suppressed. be able to.

  Furthermore, the first member 71 and the second member 72 are flush with each other. Therefore, even if the transfer paper P comes into contact with the first member 71 and then comes into contact with the second member 72, the first member 71 and the second member 72 have no step and no gap. Therefore, it is possible to suppress discharge due to a step or a gap.

  Then, the transfer paper P is guided by the separation guide plate 70 and reaches the fixing device 7. In the fixing device 7, the toner image transferred on the transfer paper P is fixed on the transfer paper P, and is discharged out of the device by the paper discharge unit 14.

  As described above, according to the image forming apparatus according to the present embodiment, the separation guide plate 70 includes the first member 71 disposed close to the transfer belt 5a and the second member disposed separately from the transfer belt 5a. 72, and the resistance value of the first member 71 is higher than the resistance value of the second member 72. Here, in the image forming apparatus, due to the structure, the transfer paper P is difficult to contact on the side close to the transfer belt 5a, and the transfer paper P is easy to contact on the side far from the transfer belt 5a. For this reason, the separation guide plate 70 has a high resistance value at a portion where the transfer paper P is difficult to contact, and a low resistance value at a portion where the transfer paper P is easy to contact. As described above, since the separation guide plate 70 has a low resistance value at the portion where the transfer paper P is easily contacted, frictional charging is difficult to occur, and generation of abnormal images due to frictional charging can be suppressed. Further, since the separation guide plate 70 has a high resistance value on the side close to the transfer belt 5a, it is difficult for the transfer belt 5a to be discharged in a high-temperature and high-humidity environment, and an abnormality caused by discharge to the transfer belt 5a. Generation of images can be suppressed. As described above, the occurrence frequency of the abnormal image can be reduced.

  Further, since the second member 72 is a conductive sheet affixed on the first member 71, the separation guide plate 70 can be obtained by affixing a conductive sheet to an existing separation guide plate or the like. The generation of abnormal images can be suppressed with a simple configuration.

The conductive sheet is grounded via a resistor. Here, the conductive sheet has a low resistance value of 1 × 10 ³ Ω. For this reason, if the conductive sheet is directly connected to the ground, a current suddenly flows from the separation guide plate 70 to the ground, and as a result, a bird's-foot-shaped abnormal image is generated. However, by connecting the ground via a resistor, it is possible to prevent a current from suddenly flowing from the separation guide plate 70 to the ground, and to further suppress the frequency of occurrence of abnormal images.

  In the separation guide plate 70, the first member 71 and the second member 72 are flush with each other on the surface that guides the transfer paper P. For this reason, there is no step or gap between the first member 71 and the second member 72, and even if the transfer paper P contacts the first member 71 and then contacts the second member 72, It is possible to prevent discharge from occurring. Therefore, the occurrence frequency of abnormal images can be further suppressed.

The resistance value of the first member 71 is 1 × 10 ¹² Ω or more, and the resistance value of the second member 72 is 1 × 10 ⁷ to 1 × 10 ⁹ Ω. For this reason, the occurrence frequency of abnormal images can be most preferably suppressed.

  The image forming apparatus according to the present invention has been described above based on the embodiment. However, the present invention is not limited to this, and modifications may be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the separation guide plate 70 is composed of two members, the first member 71 and the second member 72, but is not limited thereto, and may be composed of three or more members. The image forming apparatus is not limited to that shown in FIG.

1 is an overall configuration diagram of an image forming apparatus according to an exemplary embodiment. 1 is an enlarged view of a main part of an image forming apparatus according to an embodiment. It is an enlarged view which shows the other example of the separation guide plate in this embodiment.

Explanation of symbols

1 Photoconductor (image carrier)
DESCRIPTION OF SYMBOLS 2 Charging part 3 Exposure apparatus 4 Developing apparatus 5 Transfer part 5a Transfer belt 6 Cleaning part 7 Fixing apparatus 10 Paper feed cassette 11 First paper feed part 12 Second paper feed part 14 Paper discharge part 15 Transport path switching part 16 Circulation resupply Paper part 17 Reverse paper discharge part 20 Image processing part 30 Paper feeder main body 31 Paper feed tray 32 Front end regulating member 33 Rear end regulating member 34 Guide rail 40 First air blowing part 50 Second air blowing part 60 Adsorption / conveying part 70 Separation guide plate (Guide member)
71 First member 72 Second member A Image forming apparatus main body CCD line image sensor DF Automatic document feeder LT Paper feeder SC Image reader P Transfer paper d Original

Claims (6)

A transfer belt that transfers image information held on the image carrier onto transfer paper, and electrostatically attracts and conveys the transfer paper;
A fixing device for fixing image information transferred on the transfer paper conveyed by the transfer belt to the transfer paper;
A guide member provided between the transfer belt and the fixing device and guiding the transfer paper to the fixing device;
The guide member includes a first member disposed in proximity to the transfer belt and a second member disposed away from the transfer belt, and the resistance value of the first member is that of the second member. An image forming apparatus, wherein the image forming apparatus is higher than a resistance value. The image forming apparatus according to claim 1, wherein the guide member has the first member and the second member arranged flush and in contact with each other on a surface that guides the transfer paper. The image forming apparatus according to claim 1, wherein the second member is a conductive sheet attached on the first member. The image forming apparatus according to claim 1, wherein the conductive sheet is grounded via a resistor. The image forming apparatus according to claim 1, wherein a resistance value of the second member is 1 × 10 ⁷ to 1 × 10 ⁹ Ω. 6. The image forming apparatus according to claim 1, wherein a resistance value of the first member is 1 × 10 ¹² Ω or more.

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