JP4844876B2 - Transfer device and image forming apparatus - Google Patents

Description

  The present invention relates to a transfer device used in an image forming apparatus such as a printer, a copying machine, or a facsimile, and an image forming apparatus having the transfer device.

2. Description of the Related Art Known image forming apparatuses such as printers, copiers, and facsimile machines that form images on paper perform measures against high voltages in the apparatus body.
For example, Patent Document 1 discloses a printer that protects a paper detector from static electricity by surrounding the paper detector with a stainless-earthed buffer plate that reduces a recording paper feeding load, thereby escaping the static electricity of the recording paper with the buffer plate. Disclose.

JP 2000-62281 A

  However, in the above-described conventional example, only static electricity generated by paper feeding is released, and no consideration is given to the applied high voltage.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a transfer device and an image forming apparatus that can eliminate problems caused by a high voltage application member to which a high voltage is applied.

In order to achieve the above object, the first feature of the present invention is that a roll part facing the image carrier, a shaft part provided at an end of the roll part, and supporting the shaft part, A bearing portion formed in a rounded shape in contact with the shaft portion, a high voltage application portion to which a high voltage is applied, and a conductive function that is set to a predetermined potential and guides the recording medium to the roll portion When the high voltage application unit becomes an abnormal voltage when the high voltage application unit is disposed nearer to the shaft and to the high voltage application unit than the conductive functional member , the high voltage application unit and the high voltage application unit The transfer apparatus includes a metal member that generates a discharge with the high-voltage application unit so that the discharge does not occur with the conductive functional member. Therefore, since it is possible to prevent the discharge from occurring between the high voltage application section and the conductive functional member, it is possible to eliminate the problem that the function of the conductive functional member varies due to the discharge.

Preferably, the metal member is arranged such that no combustible material is located between the metal member and the high-voltage application unit . Therefore, combustion or melting of combustible materials due to discharge can be prevented.

  Preferably, the apparatus further includes adjusting means for adjusting the ease of occurrence of discharge between the metal member and the high-voltage applying member.

  Preferably, the metal member has a sharper tip than the conductive functional member.

  Preferably, the metal member has a needle shape.

  Preferably, the metal member is grounded independently. Therefore, the potential of the metal member can be stabilized at the ground level, and it is possible to reliably prevent discharge from occurring between the high voltage application member and the conductive functional member.

A second feature of the present invention resides in an image forming apparatus having the transfer device described above.

  ADVANTAGE OF THE INVENTION According to this invention, the malfunction which arises with the high voltage application member to which the high voltage was applied can be eliminated.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 includes an image forming apparatus main body 12, an image forming unit 14 is mounted in the image forming apparatus main body 12, and a discharge unit 16 is provided on the upper portion of the image forming apparatus main body 12. For example, a two-stage sheet feeding unit 18 is disposed below the image forming apparatus main body 12.

  Each paper feed unit 18 has a paper feed cassette 20 in which paper is stored and paper feed rolls 22a and 22b. The paper loaded in the paper feed cassette 20 is registered by the rotation of the paper feed rolls 22a and 22b. It is conveyed to the roll 24.

  Further, on the downstream side of the registration roll 24, an image carrier 28 and a transfer device 36 of a process cartridge 46, which will be described later, are provided facing each other, and a fixing device 40 is provided further downstream thereof.

  Accordingly, the sheet fed from the sheet feeding cassette 20 of the sheet feeding unit 18 by the sheet feeding rolls 22a and 22b is temporarily stopped by the registration roll 24, and is timed between the image carrier 28 and the transfer device 36. The developer image is transferred therethrough, and the transferred developer image is fixed by the fixing device 40 and discharged to the discharge portion 16 by the discharge roll 26.

The image forming means 14 is of an electrophotographic type, and includes an image carrier 28 made of a photoconductor, a charging device 30 made of, for example, a charging roll for uniformly charging the image carrier 28, and charging by the charging device 30. An optical writing device 32 that writes a latent image on the image carrier 28 by light, a developing device 34 that visualizes the latent image of the image carrier 28 formed by the optical writing device 32 with a developer, and development A transfer device 36 to transfer a developer image by the device 34 to a sheet, a cleaning device 38 to clean the developer remaining on the image carrier 28, and a developer image on the sheet transferred by the transfer device 36. For example, a fixing device 40 composed of a pressure roll and a heating roll. The optical writing device 32 is composed of, for example, a scanning type laser exposure device, traverses a process cartridge 46 described later, and forms a latent image on the image carrier 28. The cleaning device 38 includes a cleaning blade 42 that comes into contact with the image carrier 28 and a developer recovery unit 44 that stores the developer scraped off by the cleaning blade 42.
The optical writing device 32 may use an LED or a surface emitting laser as another embodiment.

Next, the process cartridge 46 and the transfer device 36 will be described in detail.
In FIG. 2, the structure of the process cartridge 46 and the transfer device 36 is shown.
In the process cartridge 46, the image carrier 28, the charging device 30, the developing device 34, and the cleaning device 38 are integrated, and these can be replaced as a unit. The process cartridge 46 is provided with an opening / closing lid 29 outside the image carrier 28. The opening / closing lid 29 is positioned so as to cover the image carrier 28 when the process cartridge 46 is not attached to the image forming apparatus main body 12, and the image carrier when the process cartridge 46 is attached to the image forming apparatus main body 12. When the image carrier 28 appears on the outer surface of the process cartridge 46 and the process cartridge 46 is attached to the image forming apparatus main body 12, as shown in FIGS. The holder 28 and the transfer device 36 face each other.

  The developing device 34 is divided into a developer container 50 for storing a developer and a developing unit 52. The developer container 50 has an agitator (developer stirring member) 54 disposed therein. The agitator 54 has a flexible stirring plate 56 such as PET (polyethylene terephthalate). When the amount of toner in the developer container 50 decreases, the stirring plate 56 becomes the inner wall of the developer container 50. , The developer is agitated and conveyed to the developing unit 52 side.

  In the developing section 52, a developing roll (developer carrier) 58 having a magnet roll disposed therein is disposed. The developing roll 58 faces the image carrier 28 at, for example, the lower part of the image carrier 28, and the opposed part is a development position. A predetermined voltage is applied to the developing roll 58. The developing unit 52 communicates with the developer container 50 through a developer supply port 60, and the developer is conveyed from the developer supply port 60 to the developing unit 52.

  The blade device 62 includes a developing blade 64 and an attachment portion 66. The developing blade 64 is made of an elastic resin such as polyurethane or silicone rubber and is disposed in the developing unit 52. One end of the developing blade 64 is fixed to the developer container 50 via an attachment portion 66. The attachment portion 66 is made of sheet metal, and one end of the developing blade 64 is fixed to the attachment portion 66 by hot melt or the like. Further, the developing blade 64 is elastically deformed and is in contact with the developing roll 58 in front of the other end. The developing blade 64 regulates the layer thickness of the developer on the developing roll 58, and the development in which the layer thickness is regulated. The latent image on the image carrier 28 is developed at the development position of the agent.

  The process cartridge 46 includes a conductive member 68 formed of a film-like sheet on the upstream side in the sheet conveying direction at a position where the image carrier 28 faces the transfer device 36 when the process cartridge 46 is mounted on the image forming apparatus main body 12. Have. The conductive member 68 is formed of a sheet having substantially the same length in the axial direction of the transfer roll 76 and the image carrier 28 of the transfer device 36. Although not shown, a voltage equal to the voltage applied to the developing roll 58 is applied to the conductive member 68 by a circuit branched from the circuit for applying the voltage to the developing roll 58. By providing the conductive member 68 in this way, scattered toner generated during development can be electrically attached onto the conductive member 68, and contamination of the image forming apparatus main body 12 due to the scattered toner can be prevented. The conductive member 68 is covered with an insulating film 70 on the transfer device 36 side (outside the conductive member 68) over the entire length in the longitudinal direction. By doing so, it is possible to prevent the conveyed paper from contacting the conductive member 68 and causing a leak between the conductive member 68 and the transfer device 36 via the paper.

Next, the transfer device 36 according to the embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 2 to 5, the transfer device 36 according to the embodiment of the present invention extends, for example, in a combustible roll 74 facing the image carrier 28 and in the longitudinal direction of the roll 74. It has a transfer roll 76 having a boss portion 72, a shaft portion 73 made of a conductive material extending from the boss portion 72, and a bearing member 78 made of a conductive material that rotatably supports the shaft portion 73. . The transfer device 36 includes a guide 80 made of an insulating material, having support portions 84a and 84b on the left and right of the transfer roll 76 and the bearing member 78, and slidably holding the guide member 78 in a state of surrounding the bearing member 78. Are attached to the bearing member 78 and the guide 80, respectively, and have a spring (elastic member) 82 that urges the bearing member 78 and the transfer roll 76 in a direction to push out the image carrier 28 side. The bearing member 78 is engaged with the left and right support portions 84a and 84b of the guide 80, and is slidable along the support portions 84a and 84b. Although not shown, a predetermined voltage having a polarity opposite to the voltage applied to the developing roll 58 and the conductive member 68 is applied to the bearing member 78.

  Further, the transfer device 36 is made of an insulating material, has a cap 88 that contacts the boss 72, engages the guide 80 so as to cover the bearing member 78, and prevents the shaft 72 from coming off from the bearing member 78. ing. The cap 88 is brought into contact with the protrusions 86 a and 86 b provided on the support portions 84 a and 84 b of the guide 80, and the boss portion 72 so as to contact the transfer roll 76 with the bearing member 78. A shaft fixing portion 92 for supporting and fixing is provided. Therefore, as shown in FIG. 3, the transfer roll 76 is mounted on the bearing 79 as shown in FIG. 4 by mounting the cap 88 after the shaft 73 of the transfer roll 76 is placed on the bearing 79 provided on the bearing member 78. Supporting and fixing to the member 78, the transfer roll 76 can be prevented from falling off the bearing member 78 and the guide 80. The transfer roll 76 and the bearing member 78 are biased in the direction of the image carrier 28 by a spring 82. However, since the cap 88 is attached, the transfer roll 76 and the bearing member 78 are imaged from a predetermined position. It does not jump out to the carrier 28 side.

  The transfer roll 76 is provided with a step so that the diameter of the boss portion 72 is larger than the diameter of the shaft portion 73, and the bearing member 78 has a boss at the semicircular portion on the image carrier 28 side of the shaft portion 73. It is located so as to fit inside the portion 72 in the radial direction. Therefore, the bearing member 78 does not jump out to the image carrier 28 side from the boss portion 72. This makes it possible to increase the distance from the bearing member 78 to the conductive member 68 of the process cartridge 46, thereby preventing leakage that may occur due to a potential difference between the conductive member 68 and the bearing member 78. And transfer failure and development failure can be prevented.

  As shown in FIG. 3, the end 94 of the bearing member 78 on the side of the image carrier 28 and the end 96 of the cap 88 on the side of the image carrier 28 have a rounded shape, that is, an R shape. . As a result, electric charges are not concentrated on a part of the bearing member 78 or the cap 88, and leakage that may occur between the bearing member 78 and the conductive member 68 can be prevented more reliably.

  Also, below the guide 80, a plate-like metal chute (conductive functional member) 98 having a surface on which the sheet slides is provided on the process cartridge 46 side. As shown in FIG. 5, the chute 98 is grounded, for example, to a ground provided in the image forming apparatus main body 12, guides the paper between the image carrier 28 and the transfer device 36, and discharges the static electricity of the paper. Remove (miss).

  Further, the transfer device 36 includes a needle-like metal member 100 having an acute point near the shaft portion 73 (and the bearing member 78). The metal member 100 is grounded independently of the other members, and the distance A between the shaft portion 73 (and the bearing member 78) is larger than the distance B between the chute 98 and the shaft portion 73 (and the bearing member 78). It has been shortened. That is, when the bearing member 78 becomes an abnormal voltage, the metal member 100 has the shaft portion 73 (and the bearing member 78) so that no discharge occurs between the shaft portion 73 (and the bearing member 78) and the chute 98. ) To generate a discharge.

  The shaft 73 (and the bearing member 78) may be discharged between the metal when the applied voltage with respect to the distance from the portion where the charge of the metal is concentrated is about 1 KV / mm or more. When the standard voltage (when printing on paper) applied to the bearing member 78 is about 7 KV and the distance B is about 8 mm, the metal member 100 is arranged so that the distance A is about 7.2 mm. . Thus, by setting the distance A to about 0.9 times the distance B, the metal member 100 is discharged even when a standard voltage and a maximum specification voltage (when printing on OHP or the like) are applied to the bearing member 78. Without generating, when the bearing member 78 becomes an abnormal voltage, discharge is generated between the shaft portion 73 (and the bearing member 78).

  Here, since the roll portion 74 of the transfer roll 76 is not located between the shaft portion 73 (and the bearing member 78) and the metal member 100, even if the metal member 100 generates a discharge, it is melted or burned by the discharge. There is nothing to do.

In addition, the metal member 100 may be provided with a variable power source 104 via an open / close switch 102. The variable power source 104 charges the metal member 100 from, for example, 0 V to a predetermined potential when the open / close switch 102 is closed. That is, by adjusting the output of the variable power source 104, it is possible to adjust the ease of occurrence of discharge between the shaft portion 73 (and the bearing member 78) and the metal member 100.
In addition to the chute 98, when there is a metal in the image forming apparatus main body 12 that may be discharged between the shaft 73 and the bearing member 78, the metal member 100 is more than the metal in the shaft 73 and the bearing. Located near the member 78.

1 is a cross-sectional view of an image forming apparatus according to an embodiment of the present invention. It is sectional drawing which shows the structure of a process cartridge and a transfer apparatus. It is sectional drawing containing the partial side view which shows a mode that the transfer apparatus was decomposed | disassembled. It is sectional drawing containing the partial side view which shows a transfer apparatus. It is a schematic diagram which shows the positional relationship of a transfer roll, a chute | shoot, and a metal member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 28 Image carrier 30 Charging apparatus 34 Developing apparatus 36 Transfer apparatus 38 Cleaning apparatus 46 Process cartridge 58 Developing roll 72 Boss part 73 Shaft part 74 Roll part 76 Transfer roll 78 Bearing member 80 Guide 82 Spring 84a, 84b Support Portions 86a and 86b Protrusions 88 Caps 90a and 90b Engaging portions 92 Shaft fixing portions 94 (bearing member) end portions 96 (cap portion) end portions 98 Chute 100 Metal member 102 Open / close switch 104 Variable power source

Claims (7)

A roll unit facing the image carrier;
A high voltage to which a high voltage is applied, comprising: a shaft portion provided at an end of the roll portion; and a bearing portion that supports the shaft portion and is formed in a rounded shape in contact with the shaft portion. An application unit;
A conductive functional member that is set to a predetermined potential and guides the recording medium to the roll unit ;
The high-voltage application unit and the conductive function when the high-voltage application unit is located at an abnormal voltage , facing the shaft portion and closer to the high-voltage application unit than the conductive functional member. A metal member that generates a discharge with the high-voltage application unit so as not to generate a discharge with the member;
A transfer device having Wherein the metal member is a transfer apparatus according to claim 1, wherein the combustible material is disposed so as not located between said high pressure application unit. Said metal member and said transfer device according to claim 1 or 2, wherein further comprising an adjusting means for adjusting the resulting ease of discharge between the high voltage applying unit. Wherein the metal member is a transfer device according to any one of claims 1 to 3 having a sharp tip than the conductive member. Wherein the metal member is a transfer device shape according to any one of claims 1 to 4 is acicular. Wherein the metal member is independent transfer device according to any one of claims 1 to 5 is the installation. An image forming apparatus comprising the transfer device according to claim 1 .

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