JPH1173031A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the adhesion of an image carrier in the discharge area to a transfer material with simple construction, and prevent the image noise by supporting the transfer material on two or more surfaces, i.e., a contact surface between the transfer material and a guide member and a contact surface the transfer material and a transfer means. SOLUTION: A transfer material 6 is supported on two or more surfaces, i.e., a contact surface between a transfer material 6 and a guide member 7 and a contact surface between the transfer material 6 and a transfer roller 8 at least during the transfer operation. A The adhesion of the transfer material 6 to a photoreceptor drum 1 can be improved in a pre-transfer area and in a transfer area even when there is a small differential feed speed between the transfer roller 8 and a timing roller 4 by pushing up the transfer material 6 by a guide member 7 in the pre-transfer area located in the upstream of the transfer roller 8 of the transfer area where the transfer is achieved. In addition, the area in which the transfer current during the transfer flows is regulated by the insulating guide member 7 in contact with the transfer roller 8. The leak discharge in the pre-transfer area is difficult to generate, and the image noise is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copier, a digital copier, and a printer, and more particularly to a transfer area for transferring a toner image from an image carrier to a transfer material. It relates to improved technology.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, before and after transfer of a toner image from an image carrier (photoreceptor) to a transfer material (paper, etc.) by a transfer means, particularly, an image formed by discharging before and after transfer. Noise easily occurs. In order to avoid this, it has been proposed to perform a transfer operation by guiding the transfer material to be in close contact with the image carrier.
That is, for example, Japanese Patent Application Laid-Open No. 63-195678 discloses a technique in which a guide brought into contact with a photoconductor increases the adhesion between the photoconductor and paper, and Japanese Patent Application Laid-Open No. 3-101776 discloses a transfer roller. Japanese Patent Application Laid-Open No. 4-204564 discloses a method of positioning a photosensitive member and supporting a guide with a roller shaft thereof. To prevent
It is shown that transfer is prevented at the trailing edge of the sheet (however, the transfer means is a transfer wire instead of a transfer roller).

[0003]

However, in the above-described conventional electrophotographic system, Japanese Patent Application Laid-Open No. 63-195
As described in Japanese Patent Application Laid-Open No. 678 and Japanese Patent Application Laid-Open No. 3-101776, a transfer roller that transfers a toner image from an image carrier to a transfer material uses a transfer roller unit and a timing roller unit. Since the difference easily occurs, it is difficult to ensure the close contact between the image carrier and the transfer material in the discharge area of the transfer roller, and the problem of image noise generation has not been completely solved. Also, JP-A-4-204
As disclosed in Japanese Patent Application Publication No. 564-564, in order to maintain the adhesion at the rear end of the sheet after the transfer, it is necessary to drive and control the guide member of the transfer material due to the strength of the paper (transfer material). In addition, the configuration becomes large-scale, which is not suitable for space saving and cost reduction.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. Even if the transfer means is a transfer roller and the transfer roller is fed by the transfer roller, it is possible to use a plurality of transfer materials. Provided is an image forming apparatus that can secure the adhesion between an image carrier and a transfer material in a discharge area by a transfer unit with a simple configuration and prevent image noise from being generated even if there is a problem such as a difference in strain between sheets. The purpose is to do.

[0005]

In order to achieve the above object, the present invention provides an image carrier, transfer means for transferring a toner image from the image carrier to a transfer material, and an image carrier comprising the transfer material. In an image forming apparatus having a guide member for guiding between transfer means, the guide member is disposed so as to be in contact with the surface of the transfer means at least during a transfer operation, and a transfer surface between the transfer material and the guide member is provided. And at least two contact surfaces between the transfer material and the transfer means.

In the above arrangement, the transfer member that is not in close contact with the image carrier in the transfer area is pushed up by the guide member in contact with the transfer means, whereby the adhesion between the image carrier and the transfer material near the transfer means is increased. In particular, the discharge action on the pre-transfer side is eliminated, and the occurrence of image noise is prevented. Further, by positioning the guide member in contact with the transfer means, it is possible to stably hold the transfer material in a limited space near the transfer roller with high accuracy.

Further, the transfer area may be regulated by a guide member. In this configuration, the adhesion between the image carrier and the transfer material in the transfer area can be reliably ensured, and the occurrence of image noise is prevented. In order to regulate the transfer area, the guide member may be sandwiched between the image carrier and the transfer means from the upstream side of the transfer area. As the guide member, an insulating resin film is desirable.

The transfer means may be cleaned by a guide member. In this configuration, unnecessary toner does not adhere to the back surface of the transfer material.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus forms an image by transferring a toner image formed on a photosensitive drum 1 serving as an image carrier to a transfer material such as paper by an electrophotographic method. Brush 2, developing device 3, transfer roller 8 (transfer means),
Cleaners 9 and the like are sequentially arranged. Exposure to the photoconductor drum 1 is performed at point A using polarized laser light or the like. On the upstream side of a transfer area where the photosensitive drum 1 and the transfer roller 8 are in contact with each other, a guide member 5 attached to a fixed frame (not shown) of the apparatus for guiding the transfer material 6 between the photosensitive drum 1 and the transfer roller 8 , And a guide member 7 held by the guide member 5 is disposed. The guide member 7 is in contact with the surface of the transfer roller 8. At least during the transfer operation, the transfer material 6 is supported on at least two surfaces of the contact surface between the transfer material 6 and the guide member 7 and the contact surface between the transfer material 6 and the transfer roller 8. Further, as a transport system of the transfer material 6, a paper feed roller, a timing roller 4, and a paper discharge roller (not shown) are provided.

FIG. 2 is an enlarged view of the transfer roller 8 of the image forming apparatus. By sandwiching the guide member 7 between the transfer roller 8 and the photosensitive drum 1, the transfer area is
And the contact surface of the photosensitive drum 1. Guide member 7
It is preferable to use an insulating resin film (Teflon, nylon, Mylar (trade name), etc.).
The guide member 5 may be a metal material or a resin material. The surface of the transfer roller 8 is formed of a flexible conductive resin or the like.

In the above configuration, the transfer material 6 extruded by the timing roller 4 is supported and conveyed by the guide member 5, the guide member 7, and the transfer roller 8. The toner image developed on the photosensitive drum 1 by the developing device 3 is electrostatically transferred by the transfer current of the transfer roller 8 to the transfer material 6.
Is transferred to The guide member 7 pushes up the transfer material 6 in a pre-transfer area located on the upstream side of the transfer roller 8 with respect to the transfer area where the transfer is performed, so that the feeding speed between the transfer roller 8 and the timing roller 4 is very small. Even if there is a difference, or even if there is a difference in strain between a plurality of transfer materials, the adhesion of the transfer material 6 to the photosensitive drum 1 can be improved in the pre-transfer area and the transfer area. In addition, the area where the transfer current flows during transfer is regulated by the insulating guide member 7 in contact with the transfer roller 8. For this reason, a leak discharge is less likely to occur in the pre-transfer area, and the occurrence of image noise is prevented.

FIGS. 3 to 8 are enlarged views of a transfer roller 8 of an image forming apparatus according to another embodiment. FIG. 3 shows an embodiment in which the transfer material 6 is positioned by the thickness of the guide member 7. The transfer material 6 is supported on two or more surfaces: a contact surface (a) between the transfer material 6 and the guide member 7 and a contact surface (b) between the transfer material 6 and the transfer roller 8. With such a support structure of the transfer material 6, the transfer roller 8 is provided in the same manner as described above.
The guide member 7 that contacts the transfer member 6 pushes up the transfer material 6, and the adhesion between the photosensitive drum 1 and the transfer material 6 increases. Also, the guide member 7
Is in sliding contact with the transfer roller 8 to clean the surface. In this example, the guide member 7 itself can have a function equivalent to the above-described guide member 5.

FIG. 4 shows an embodiment in which the transfer material 6 is positioned based on the amount of protrusion of the guide member 7 from the contact position with the transfer roller 8. FIG. 5 shows a state in which a guide member 7 is integrally attached to a guide member 5 for causing a transfer material 6 to protrude into a transfer area. The leading end of the guide member 7 is brought into contact with a transfer roller 8, and the transfer roller 8 is exposed to light. It is inserted into the vicinity of the position on the upstream side of the position where the body drum 1 contacts.

FIG. 6 shows an embodiment in which a guide member 7 is attached to a guide member 5 ′ provided in two steps in the vicinity of the transfer roller 8, separately from the guide member 5 for guiding the transfer material 6. FIG. 7 shows that the guide member 7 is
2 shows an embodiment in which the contact is made. The guide member 7 is made of a highly flexible material, and is in contact with the photosensitive drum 1 when the transfer material 6 is not passed. When the transfer material 6 is passed, the guide member 7 is pressed by the material. , Comes into contact with the transfer roller 8.

FIG. 8 shows an embodiment in which the guide member 7 is pushed out only when paper is passed by using a solenoid and is brought into contact with the transfer roller 8. The guide member 7 is movably held by a slider 52 with respect to the guide member 51,
2 is a solenoid 53 and a spring 5 provided in a guide member 51.
4 and drives the solenoid 53 only when the paper is passed to push the guide member 7 out. In this configuration, since the guide member 7 is not always in contact with the photosensitive drum 1, contamination of the photosensitive drum 1 is reduced.

In any of the embodiments shown in FIGS. 3 to 8, the transfer region is regulated by the guide member 7 as in the embodiment shown in FIGS. Is not generated, and the generation of image noise is prevented. The configuration in which the guide member 7 is inserted to a position where the transfer roller 8 and the photosensitive drum 1 are in contact with each other can surely maintain the close contact between the transfer material 6 and the photosensitive drum 1 in the transfer area, and The effect is remarkably obtained.

The present invention is not limited to the configuration of the above embodiment, and various modifications are possible. For example, if the transfer unit is a contact type, the transfer unit is not limited to a transfer roller, and may be a transfer brush or the like.

[0018]

As described above, according to the image forming apparatus of the present invention, while having a simple structure in which the guide member that comes into contact with the transfer means is provided, the influence of the transfer of the transfer material by the transfer means, Even if there is a problem such as a difference in strain between the transfer materials, it is possible to reliably ensure the adhesion between the transfer material and the image carrier in the transfer area, and prevent image noise from occurring. In addition, by regulating the transfer area by the guide member, the adhesion in the transfer area can be sufficiently ensured, and the occurrence of image noise can be prevented. Further, if the transfer means is cleaned by the guide member, unnecessary toner does not adhere to the back surface of the transfer material.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged schematic sectional view of a transfer roller portion of the image forming apparatus.

FIG. 3 is an enlarged schematic cross-sectional view of a transfer roller portion of an image forming apparatus according to another embodiment of the present invention.

FIG. 4 is an enlarged schematic sectional view of a transfer roller portion according to still another embodiment.

FIG. 5 is an enlarged schematic cross-sectional view of a transfer roller portion according to still another embodiment.

FIG. 6 is an enlarged schematic cross-sectional view of a transfer roller portion according to still another embodiment.

FIG. 7 is an enlarged schematic cross-sectional view of a transfer roller portion according to still another embodiment.

FIG. 8 is an enlarged schematic sectional view of a transfer roller portion according to still another embodiment.

[Explanation of symbols]

 Reference Signs List 1 photoconductor drum (image carrier) 6 transfer material 7 guide member 8 transfer roller (transfer unit)

Claims (3)

[Claims] 1. An image forming apparatus comprising: an image carrier; transfer means for transferring a toner image from the image carrier to a transfer material; and a guide member for guiding the transfer material between the image carrier and the transfer means. In the above, the guide member is disposed so as to contact at least the surface of the transfer unit at the time of a transfer operation, and the transfer material is contacted with the contact surface between the transfer material and the guide member and the contact between the transfer material and the transfer unit. An image forming apparatus, wherein the image forming apparatus is supported on two or more surfaces. 2. The image forming apparatus according to claim 1, wherein a transfer area is regulated by the guide member. 3. The image forming apparatus according to claim 1, wherein the transfer member is cleaned by the guide member.