JPH11184269A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent image failure due to soil on the back of a transfer material and shearing of transfer. SOLUTION: In the image forming part, a roller 100, a bearing 101 pivotally supporting the roller 100, a hold member (conductive resin member) 102 holding the bearing 101, and a guide plate 103 to which they are attached are made of a conductive material, and an empty space between the roller 100 and guide plate 103 is covered with a light-shield insulation member 104. Because the hold member 102 is conductive, the roller 100 conducts with the guide plate 103 and, likewise the guide plate 103, toner on a photoreceptor drum 71 is not attracted to the roller 100, which prevents image failure. Additionally, because the light-shield insulation member 104 entirely covers the rear of the guide plate 103, toner scatter on the photoreceptor drum 71 can be prevented also when the photoreceptor drum 71 is subjected to discharging exposure from below the guide plate 103, which prevents soil on the guide plate and hence image failure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus suitable for a copying machine, a printer, and a facsimile, for example, for transferring a toner image on a photoreceptor to a transfer material by the cooperation of corona discharge and charge removal exposure. Specifically, a guide plate as a guide member, a roller attached to the guide plate, a bearing fitted to the roller, and a holding member for holding the bearing are made of a conductive material, and a voltage is applied to the roller via the guide plate. By doing so, it is possible to prevent image defects due to transfer deviation, contamination of the guide plate and rollers.

[0002]

2. Description of the Related Art In an image forming apparatus having an image forming section, as shown in FIG. 6, a document image is recorded as a latent image on a charged photosensitive drum 71, and the latent image is formed into a toner image by a developing device. The transfer material (transfer paper) p guided by the guide plate 12 and conveyed along the surface of the photosensitive drum 71 is charged by the transfer pole 74a of the transfer unit 74, and the charge exposing means 110 Then, the toner particles are suction-transferred to the transfer paper p, and thereafter, the transfer paper p is separated from the photosensitive drum 71, and the toner image is fixed. Thus, the toner image can be copied on the transfer paper p.

[0003]

Conventionally, however, the guide plate 12 is charged by the influence of the corona transfer of the transfer section 74. Therefore, the photosensitive drum 7 is
1 is attracted, the toner adheres to the guide plate 12, and an image defect occurs in which the back surface of the transfer paper p becomes dirty.
In order to solve this, a technique has been proposed in which toner is applied to the guide plate 12 so as not to be attracted.

However, when the transfer paper p is made of a material having poor transportability, the transfer paper p adheres to the guide plate 12 to deteriorate the transportability, thereby causing a problem that an image defect due to a transfer deviation occurs.

Accordingly, it is an object of the present invention to propose an image forming apparatus which does not cause image defects due to transfer surface back surface contamination and transfer deviation.

[0006]

In order to solve the above-mentioned problems, in an image forming apparatus according to the present invention, an image forming apparatus is configured to transfer a toner image on a photosensitive member to a transfer material guided to a transfer section. In, a conductive guide plate for guiding the transfer material to the transfer unit, a conductive plate has a conductive roller, a bearing that rotatably holds the roller, holding the bearing,
A holding member attached to the guide plate, wherein the holding member is made of a conductive resin member.

According to this, by making the holding member conductive, the rollers are electrically connected to the guide plate, so that the toner on the photoreceptor is prevented from being attracted to the rollers as in the case of the guide plate, and image defects are generated. Can be prevented.

[0008] In the image forming apparatus according to the invention, the resistivity of the conductive resin member is characterized in that a 10 ² ~10 ^{1 0} Ωcm.

According to this, by restricting the resistivity of the conductive resin member to 10 ² Ω to 10 ¹⁰ Ω, the rollers and the guide plate are efficiently conducted.

In the image forming apparatus according to the present invention, the roller is applied with a voltage via a guide plate.

According to this, since the voltage applied to the guide plate is reliably applied to the rollers, the toner does not adhere to the rollers, so that it is possible to prevent the occurrence of an image defect.

The image forming apparatus according to the present invention is characterized in that the guide plate swings in accordance with the type of the transfer material with the lower portion on the transfer material entry side as a fulcrum.

[0013] According to this, the transfer material whose guide plate is poor in transportability swings, is transported by the rollers, and is surely guided to the transfer portion, so that transfer deviation is prevented and occurrence of image defects is prevented. be able to.

The image forming apparatus according to the present invention has a guide member for guiding a transfer material to the transfer section in order to corona-transfer the toner image on the photoconductor at the transfer section. In the image forming apparatus having the charge removing exposure unit for removing charges, the guide member is a guide plate having a gap, and a light-shielding insulating member is attached to the back side of the guide plate so as to cover the gap. .

According to this, since the gap between the roller and the guide plate is covered with a light-shielding resin member, exposure at the time of transfer is not lost, so that toner scattering on the photosensitive member is prevented, and image defects are prevented. Generation can be prevented. Also, since the light-shielding insulating member is made of an insulating member that covers the guide plate,
By preventing the corona discharge from exerting on the guide plate, it is possible to prevent the toner on the photoconductor from soiling the guide plate, thereby preventing the occurrence of image defects.

[0016]

Next, an embodiment of an image forming apparatus according to the present invention will be described in detail with reference to the drawings. The same parts as those in the related art are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 is a diagram showing an example of a cross-sectional configuration of an image forming section which is a main part of an image forming apparatus according to an embodiment of the present invention. In the present invention, an electrostatic latent image is formed on the surface of the photoconductor,
The electrostatic latent image on the photoreceptor surface is visualized using toner, and the visualized toner is transferred (copied) to the transfer material (transfer paper) guided to the transfer unit by the cooperation of corona discharge and static elimination exposure. In doing so, a roller for guiding the transfer material to the transfer section,
The bearing that holds the roller, the holding member (conductive resin member) that holds the bearing, and the guide plate to which the holding member is attached are each made of a conductive material, and at least a negative voltage is applied to the roller. This is intended to prevent image defects due to transfer deviation, contamination of the guide plate and rollers.

In FIG. 1, a photoreceptor drum 71 for transferring a toner image to a transfer sheet p is provided in an image forming section 70, and a toner image is transferred below the photoreceptor drum 71 to the transfer sheet p. Transfer part 74 having a transfer pole 74a for
And a separation unit 75 having a separation pole 75a for separating the transfer paper p from the photosensitive drum 71.

A support frame 109 is provided below the transfer section 74 and the separation section 75. Inside the support frame 109, transfer processing is performed in cooperation with corona discharge from the transfer pole 74a, and a transfer paper p is formed.
A static elimination exposure unit 110 for improving the separability of the image is provided. The static elimination means 110 is composed of an LED array arranged along the axial direction of the photosensitive drum 71, and the emitted light beam passes through a small opening 111 formed in the bottom of the transfer section 74 and passes through the photosensitive drum 71. Irradiation is performed on the 71 side.

Further, a resist roller 112 is provided on the upstream side of the transfer unit 74 to convey the transfer paper p to the transfer unit 74 and the separation unit 75, and the registration roller 112 passes through the transfer unit 74 and the separation unit 75 on the downstream side. A transport belt 113 is provided for transporting the transfer paper p.

A conductive guide plate 103 having a conductive roller 100 for guiding the transfer paper is disposed upstream of the transfer section 74. The guide plate 103 is formed in a substantially rectangular shape as shown in FIG. 2, and is formed in a curved shape so that the transfer material p smoothly enters and adheres to a predetermined position on the surface of the photosensitive drum 71 as shown in FIG. As shown in FIG. 3, the cylindrical roller 100 is arranged so as to protrude from an opening 103 b formed in a central portion of the guide plate 103.

The guide plate 103 is provided with a guide plate 103 in order to prevent light for static elimination exposure from leaking from a gap between the roller 100 and the guide plate 103 and to prevent charges from the transfer pole 74a from flowing into the roller 100. As shown in FIGS. 1 and 2, a light-shielding insulating member 104 is adhered by an adhesive in this example so as to entirely cover the back side.

As shown in FIG. 3, both ends of the guide plate 103 are bent to form a support portion 103a, and the support portion 103a is attached to the mounting plate portion 1 extending to the side wall of the transfer portion 74.
07 is rotatably mounted around a pin 108. Also, as shown in FIGS. 1 and 3, the guide plate 10
A spring 105 is mounted between the mounting plate 107 and the mounting plate 107 to urge the guide plate 103 toward the photosensitive drum 71. As a result, even if the transfer paper p is thick paper, the guide plate 103 swings in accordance with the thickness of the transfer paper p and the roller 10
The transfer paper p can be smoothly conveyed to the photosensitive drum 71 side by the action of 0.

On the other hand, as shown in FIG. 2, a conductive bearing 101 is fitted to both ends of the roller 100, and is fitted into a mounting portion 102a of a conductive holding member 102. The holding member 102 is a conductive resin member made of a conductive ABS resin, and has a resistivity of 10 ² to 10 ¹⁰ Ωcm. Thus, for example, when a voltage is applied to the guide plate 103, the resistivity is limited, so that the guide plate 1
A voltage can be efficiently applied to the roller 100 via the third roller 03. Then, the holding member 102 is attached and fixed to a predetermined position of the guide plate 103, so that the guide plate 103
The roller 100 is rotatably mounted on the roller.

The operation when a negative voltage (-500 volts) is applied to the guide plate 103 in the image forming section 70 thus configured will be described with reference to FIG. The surface of the photoconductor drum 71 is irradiated with an image, and is reversely developed by a developing unit 73 to be described later to form a toner image. Next, corona charging of the back surface of the transfer paper p by the transfer pole 74a of the transfer unit 74 (FIG. 1) and charge removal exposure of the surface of the photosensitive drum 71 by the charge removal exposure unit 110 are performed to transfer the toner image. The transfer paper p is removed from the photoconductive drum 71 by the neutralization of the back surface of the transfer paper p by 75 (FIG. 1).

At this time, since the roller 100, the bearing 101, the holding member 102, and the guide plate 103 shown in FIG. 2 are all conductive materials, the voltage applied to the guide plate 103 is not applied to the holding member 102, the bearing 101. Roller 100 through
Will be applied.

The back surface of the guide plate 103 is provided on the insulating member 1.
04, the charge from the transfer pole 74a is prevented from flowing into the roller 100, the toner on the photosensitive drum 71 is prevented from adhering to the roller 100, and the transfer in contact with the roller 100 is prevented. The material p can be prevented from being soiled.

Further, by covering the back side of the guide plate 103 with the insulating member 104, the light of the charge eliminating exposure unit 110 is prevented from hitting the photosensitive drum 71 from the gap between the roller 100 and the guide plate 103, and image dust is generated. Can be prevented.

Next, an example of a sectional configuration of the image forming apparatus 20 having the image forming section 70 will be described with reference to FIG. In this example, an image forming apparatus 20 capable of copying images on the front and back (both sides) of a document on the front and back of a transfer sheet p will be described. Further, in this description, a detailed description of the image forming unit 70 is omitted.

As shown in FIG. 5, the image forming apparatus 20 includes an image acquisition unit 31 for reading an image of the original d, and a roller 1.
00 and an image forming section 70 having a guide plate 103. The image acquisition section 31 has an automatic document feeder (ADF) 40 and an image reading section 50.

The automatic document feeder 40 feeds a plurality of set documents d one by one, and places the documents d at predetermined positions.
a, a roller 42b, a roller 43, a reversing roller 44, a reversing unit 45, and a paper discharge tray 46. The image reading unit 50 includes a first platen glass 21, a second platen glass 52, a light source 53, mirrors 54, 55, 56, an imaging optical system 57, a CCD imaging device 58, and an optical drive system (not shown). . The image forming unit 70 includes the photosensitive drum 7
1, charging unit 72, developing unit 73, transfer unit 74, separation unit 7
5. Cleaning unit 76, transport mechanism 77 and fixing unit 78
It is composed of

Here, the function of each unit will be described in order. For example, a plurality of originals d are placed on the original placement unit 41 with the first page of the original facing upward. And
When the rollers 42 a and 42 b are driven, the first sheet of the document d fed through the rollers 42 a and 42 b is conveyed via the rollers 43.

At this time, the light source 53 of the image reading unit 50
The document d is irradiated with light. This reflected light is reflected on mirror 5
Since the light is redirected by 4, 55, and 56, the reflected light is taken into the CCD imaging device 58 via the imaging optical system 57. As a result, an image of the document d is formed on the light receiving surface of the CCD imaging device 58. At this time, the size of the document d is detected by the CCD imaging device 58.

When the original d is placed on the original placing portion 41 with the original d facing down on the platen glass 21, the optical drive system moves along the platen glass 21. Scans the image reading unit 50,
The size and image of the document d are read by the imaging device 58.

The original d is set by the automatic document feeder 40.
Is automatically fed, the periphery of the roller 43 is
In this case, the information of the document is read by the image reading unit 50 in a state where the light source 53 and the mirror 54 are fixed below the second platen glass 52.

When the first page of the document d is read, the winding operation using the roller 43 is performed again via the reversing roller 44, and the image on the back of the document is read by the image reading unit 50. Can be

The original d whose front and back images have been read in this way is again inverted by the reversing roller 44 and is stacked on the paper discharge tray 46 together with the original reading operation in a state where the front surface faces downward. go. The read image information is output to the image writing unit 60.

On the other hand, in this example, the paper feed cassettes 30a and 30a on which two types of transfer papers p having different sizes are stacked respectively.
0b, the selected one of the transfer papers p is fed out and fed to the image forming unit 70. The transfer paper p is conveyed to the photoreceptor drum 71 after being synchronized by the registration rollers 112 at the entrance.

In the image writing section 60, a laser beam corresponding to the image data is transmitted from the laser diode to the photosensitive drum 7.
1, the original d is placed on the photosensitive drum 71.
Is formed. This electrostatic latent image is formed as a toner image on the photosensitive drum 71 after being developed by the developing unit 73. This toner image is copied onto a transfer sheet p by a transfer section 74 provided below the photosensitive drum 71.

In this case, the roller 100 and the guide plate 103
Since a voltage of -500 volts is applied to the roller, the rollers are conveyed without being contaminated with the toner and any transfer material is not attracted to the guide plate, thereby preventing the occurrence of image defects. Further, since the back surface of the guide plate 103 is entirely covered with the insulating member 104, the charge from the transfer pole 74a is prevented from flowing into the roller 100, and the toner on the photosensitive drum 71 adheres to the roller 100. To prevent the transfer material p contacting the roller 100 from being stained. Furthermore, the back side of the guide plate 103 is
By covering the photosensitive drum 71 with the cover 04, it is possible to prevent the light of the charge eliminating exposure unit 110 from hitting the photosensitive drum 71 from the gap between the roller 100 and the guide plate 103, thereby preventing the generation of image dust.

Then, the transfer paper p attracted to the photosensitive drum 71 is separated from the photosensitive drum 71 by the separating section 75. Thereafter, the transfer paper p separated from the photosensitive drum 71 is sent to the fixing unit 78 via the transport mechanism 77, and the toner image is fixed by heat and pressure. As a result, an image of the back surface of the document (second page image) is formed on the transfer paper p.

The transfer paper p on which the toner image has been pressed is conveyed downward through a guide 91 and sent to a reversing unit 93. Next, the transfer paper p sent to the reversing section 93 is again fed upward by the reversing roller 92, and
The image is transferred to the image forming unit 70 again through the reverse conveyance path 94 provided on the image forming unit 70.

In the image forming section 70 where the image formation on the back side of the original d is completed, the toner adhering to the photosensitive drum 71 is removed by the cleaning section 76, and the photosensitive section 71 is charged by the charging section 72. Waiting for the next image formation.

In this state, the transfer paper p is placed with its surface (the surface on which no image is formed) facing upward and the registration roller 6
1 to the image forming unit 70. Image forming unit 7
In the case of 0, an electrostatic latent image on the surface of the document is formed on the photosensitive drum 71 and this electrostatic latent image is developed by the developing unit 73, so that a toner image on the surface of the document is formed on the photosensitive drum 71.

Since this toner image is copied onto the transfer paper p by the transfer section 74, an electrostatic latent image of the first page is formed on the surface thereof. The transfer paper p attracted to the photoconductor drum 71 is separated from the photoconductor drum 71 by the separation unit 75 and then sent to the fixing unit 78 via the transport mechanism 77, where the toner image is fixed by heat and pressure. . As a result, an image (first page image) of the surface of the document can be formed on the transfer paper p.

The transfer paper p on which image formation has been completed on the back and front sides of the transfer paper p is discharged to the outside as it is by the finisher unit 90 in accordance with the output form (operation instruction such as a sorter function). Alternatively, the sheet is reversed again by the reversing section 93 and discharged outside the apparatus by the discharge roller 95. Thus, images on the front and back (both sides) of the document d can be copied on the front and back of the transfer paper p.

In this embodiment, the case where the roller 100 is driven to rotate by the movement of the transfer sheet has been described.
The invention is not limited to this, and the rollers 100 themselves may be driven.

The materials of the roller 100, the bearing 101 and the guide plate 103 are only required to be conductive. For example, a conductive metal or a conductive ABS resin can be used.

Although the case where a conductive ABS resin is used as the material of the holding member 102 has been described, the present invention is not limited to this, and another conductive material may be used.

[0050]

As described above, in the image forming apparatus according to the present invention, in the guide plate for guiding the transfer material to the transfer section, the rollers that conduct with the guide plate are provided, and the guide plate is caused to swing. A light-shielding insulating member for covering a gap between the roller and the guide plate is attached to the back side of the guide plate.

Accordingly, since the rollers are conveyed without being contaminated with the toner and without adhering any transfer material to the guide plate, it is possible to prevent the occurrence of image defects.

Further, by covering the gap between the roller and the guide plate with a light-shielding insulating member, the toner on the photosensitive member can be prevented from scattering even when the photosensitive member is exposed to static electricity from below the guide plate. It is possible to prevent the plate from being stained and prevent image defects from occurring.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an image forming unit according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part of the image forming unit.

FIG. 3 is a perspective view of a main part of the image forming unit.

FIG. 4 is an explanatory diagram when a negative voltage (−500 V) is applied to an image forming unit.

FIG. 5 is a cross-sectional view of an image recording apparatus having an image forming unit.

FIG. 6 is a diagram showing a configuration of a conventional example.

[Explanation of symbols]

 12, 103 guide plate 20 image forming apparatus 70 image forming section 71 photoreceptor drum 74 transfer section 74a transfer pole 75 separation section 75a separation pole 100 roller 101 bearing 102 holding member 102a attachment section 103a support section 103b opening section 104 insulating member 105 spring 110 static elimination exposure means d original p transfer material (transfer paper)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03G 15/00 550 G03G 15/00 550 21/08 21/00 342 (72) Inventor Junichi Hamada 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Corporation

Claims (5)

[Claims] 1. An image forming apparatus for transferring a toner image on a photoreceptor onto a transfer material guided to a transfer unit, comprising: a conductive guide plate for guiding the transfer material to the transfer unit; The guide plate has a conductive roller, a bearing that rotatably holds the roller, and a holding member that holds the bearing and is attached to the guide plate, wherein the holding member is a conductive resin member An image forming apparatus comprising: 2. The conductive resin member has a resistivity of 10 ² -1.
0 ¹⁰ The image forming apparatus according to claim 1, characterized in that it is a [Omega] cm. 3. The image forming apparatus according to claim 1, wherein a voltage is applied to the roller via the guide plate. 4. The image forming apparatus according to claim 1, wherein the guide plate swings in accordance with a type of the transfer material with a lower portion of the transfer material entering side as a fulcrum. 5. A static elimination exposure, comprising: a guide member for guiding a transfer material to the transfer section in order to corona-transfer a toner image on a photoconductor at a transfer section; The image forming apparatus according to claim 1, wherein the guide member is a guide plate having a gap, and a light-shielding insulating member is attached to a back side of the guide plate so as to cover the gap.