JPH09258573A - Transfer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer device of a fixed brush type capable of realizing an excellent image at a low cost while preventing the image deterioration, the transfer unevenness or the like from occurring prior transferring. SOLUTION: In the case of adopting the fixed transferring electric charge applying member in a brush shape, the device is composed so as to have the brush supporting member 52 for condensing the tip of the brush 50 in contact with the rear side of a transfer material, a transferring belt and the inside face of a transferring drum, in the range narrower than the area where the transfer material P in contact with a photoreceptor 1. In such a case, the device is composed so as to locate the tip part of the brush 50 inside the area L on which the transfer material P comes into contact with the photoreceptor 1, and to make denseness on the tip part of the brush 50 higher than that of the primary brush 50.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device used in an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art Conventionally, conductive or semi-conductive fibers are formed in a brush shape, and the brush is disposed as a transfer charge applying member for the transfer material so as to face the photoconductor so as to sandwich the transfer material. There has been proposed a transfer device for applying a voltage to the transfer device for transferring, and a transfer device incorporating this brush as a transfer means of a transfer belt system or a transfer drum system.

[0003]

However, in the case of using a brush as the transfer charge applying means, when a brush having a wide width is used, the brush is moved from the area where the photoconductor contacts the transfer material in the moving direction of the transfer material. It becomes wider, and as a result,
Charges are also applied from the brush to the back surface of the transfer material in the gap immediately before the contact between the photoconductor and the transfer material, so that pre-transfer discharge occurs, and in particular halftone unevenness due to discharge occurs,
Occurrence of scattering around letters and the like may deteriorate the image. These problems can be solved by narrowing the width of the brush from the contact area between the photoconductor and the transfer material. In that case, the brush density is originally small, and the range for applying the electric charge is narrow, and the brush is applied to the transfer material. The transfer charge generated is likely to be uneven, and as a result, transfer unevenness may be generated particularly in an area image such as a halftone portion or a solid portion. In addition, there is also a problem that since the density is low, it is easily affected by deterioration of durability of the brush and has a short life. In order to improve this problem, the brush density may be increased at the stage of manufacturing the brush, but in this case, there is a new problem that the manufacturing cost increases. The above-mentioned problem is also a problem that occurs when the brush-shaped transfer charge applying member is incorporated into a transfer belt or a transfer drum.

An object of the present invention is to provide a fixed brush type transfer device capable of achieving a high quality image without image deterioration and transfer unevenness at low cost.

[0005]

In order to achieve the above object, according to the present invention, in a transfer device using a brush-like fixed transfer charge applying member, the back surface of the transfer member or the inner surface of the transfer belt or transfer drum is used. The tip of the brush that comes into contact with the brush has a support member for concentrating the brush in a narrower range than the area where the photoconductor contacts the transfer material.

[0006]

According to the structure of the present invention, by concentrating the tip of the brush, the tip of the brush can be easily provided in the region where the photoconductor and the transfer material are in contact with each other, and the density of the brush at the tip is It can be higher than the original brush density.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an overall schematic configuration diagram of an image forming apparatus which is a first embodiment of the present invention. In the figure, a photosensitive drum (1) is rotationally driven in the direction of an arrow a in the figure, and a charging charger (2) for charging the photosensitive drum (1) and a charged photosensitive drum (1) are provided around the photosensitive drum (1). Connected to a print head (3) that exposes an image to a developer, a developing device (4) that visualizes the electrostatic latent image formed on the photosensitive drum (1) as a toner image, and a DC power supply (6) A fixed transfer brush (5), a separation claw (7) for separating the paper from the photoconductor drum (1), a cleaner (8) for removing toner remaining on the photoconductor drum (1), and a photoconductor drum ( An eraser (9) for erasing the residual charge on 1) is arranged.

From the paper tray (10) to the paper feed roller (1
The paper P sent out by 1) is conveyed to the transfer position between the photoconductor drum (1) and the transfer brush (5) after being synchronized with the photoconductor drum (1) by the timing roller (9). To be done. At the transfer position, transfer charges are supplied to the back surface of the paper P by the transfer brush (5), and the toner image on the photosensitive drum (1) is electrostatically transferred onto the paper P by the transfer charges.

The paper P on which the toner image has been transferred is peeled off from the photosensitive drum (1) by the separation claw (7), sent to the conveyor belt (13), and guided from the conveyor belt (13) to the fixing section. The toner is fixed by the fixing roller (14) and discharged to the paper discharge tray (15).

Next, the structure of the fixed transfer brush according to the present invention will be described with reference to FIG.

The brush is formed by fixing the conductive brush thread (50) on the conductive support member (52).
The front end of 0) contacts the back surface of the paper P as one line along the direction orthogonal to the transport direction of the paper P.

More specifically, as shown in FIG. 3 (a), the brush portion is formed by weaving the conductive brush thread (50) into the conductive cloth (51) and then lengthening the brush thread (50). It was cut to have a size of 8 mm. The brush thread (50) has a thickness of 6D (denier), and the density after weaving is 50,000 F (filler) / inch 2. The brush thread (50) has an electric resistance of 10 ⁴ Ω ・
A material was used in which conductive carbon was added to rayon-based resin so as to be cm. The resin may be another resin, and for example, an acrylic resin or a Nylo resin may be used instead of the rayon resin.

As shown in FIG. 3 (b), the cloth (51) constructed as described above is fixed to the concave surface of the support member (52) with a conductive adhesive. The supporting member (52) is made of a conductive material such as aluminum, and the concave surface, that is, the adhesive surface of the brush, has a radius of curvature of 8 m, which is the same as the brush length.
It is processed to be m.

The cloth (51) is attached to the support member (52).
And the brush (5) as shown in Fig. 3 (b).
The tip of 0) can be configured to be concentrated at almost one point (strictly, it is concentrated in a line along a direction orthogonal to the transport direction of the paper P). When the transfer charge is applied to the back surface of the paper P by contacting the back surface of the paper P with the DC power supply described above, the area of the back surface of the paper P to which the transfer charge is applied is concentrated at almost one point. As a result, the transfer charge can be imparted only to the area L where the photosensitive drum (1) and the paper P are in contact with each other, so
It is possible to prevent the occurrence of electric discharge in the gap between the photoconductor drum (1) and the sheet P before the discharge. Further, by adopting a configuration in which the brush tips are concentrated as shown in FIG. 3B, the degree of freedom of the mounting position in the region L where the photosensitive drum (1) and the paper P are in contact can be improved. .

Further, since the brush thread (50) is concentrated at the tip portion, the density of the tip portion can be made much higher than the original brush density, and the transfer charge can be uniformly applied to the back surface of the paper P. , The brush thread (5
0) Even if the transfer charge application capability of one line is slightly reduced, the overall transfer charge application capability can be maintained due to the increased brush density.

FIG. 2 shows an image forming apparatus which is another embodiment to which the present invention is applied. The photosensitive drum (20) is shown in FIG.
Is rotationally driven in the direction of arrow a in the figure, and around it, the charger (21), print head (22), developing device (23), transfer belt (24), cleaner (25),
An eraser (26) and the like are arranged.

The transfer belt (24) is connected to the photosensitive drum (2
0) to drive in the direction of arrow b in synchronism with
A film belt made of VDF (polyvinylidene fluoride) or PC (polycarbonate), or C
A driving roller (37) and a driven roller (38) formed of a rubber belt made of R rubber, urethane rubber, or the like.
Stretched by.

Around the transfer belt (24), the toner image on the photosensitive drum (20) is transferred onto the transfer belt (24).
A fixed transfer brush (35) according to the present invention for transferring to the upper paper P, a DC power source (36) connected to the transfer brush (35), and a separation claw for separating the paper P from the transfer belt (24). (32), a pair of static eliminator chargers (39) and (40) for neutralizing the inner and outer surfaces of the transfer belt (24), and a belt cleaner (4 for cleaning the outer surface of the transfer belt (24).
1), a grounded conductive counter roller (43) and the like which are in contact with the transfer belt (24) of the driven roller (38) are provided. Since the transfer brush (35) has the same structure as the transfer brush (7) of the above-mentioned embodiment, the description thereof will be omitted.

In the above apparatus, the paper tray (28)
The paper P sent from the paper by the paper feed roller (29) is
The guide roller (30) guides the timing roller (31), and the timing roller (31) guides the photosensitive drum (20).
After being synchronized with, the transfer belt (24) is fed between the driven roller (38) connected to the DC power source (42) and the counter roller (43) which is grounded, and is driven by the drive roller (37). Electrostatically adsorbed on the outer surface of the. When the paper P reaches the transfer position between the photoconductor drum (20) and the transfer belt (24), the transfer charge is supplied to the transfer belt (24) by the fixed transfer brush (35) inside the transfer belt (24). , The toner image on the photoconductor drum (20) is the paper P.
Is transferred electrostatically onto the substrate.

The paper P on which the toner image is transferred is conveyed while being attracted to the transfer belt (24), and the separation claw (3
It is peeled off from the transfer belt (24) in 2). Then, the fixing roller (27) is guided by the guide (33) to the fixing unit.
The toner is fixed on the paper and is discharged onto the paper discharge tray (34).

Transfer belt (24) from which the paper P has been peeled off
Has a pair of static elimination charges (39) and (4
0), the outer surface of the belt cleaner (4)
It is cleaned in 1). After that, the sheet is conveyed again to the above-described sheet suction unit.

Also in this embodiment, since the tip of the brush is concentrated at almost one point, the area on the back surface of the transfer belt (24) to which the transfer charge is applied can be concentrated at almost one point. As a result, the transfer charge can be applied only to the region L where the photoconductor drum (20) and the paper P are in contact with each other, so that discharge occurs in the gap between the photoconductor drum (20) and the paper P before the transfer region L. Can be prevented.

The transfer brush shown in FIG. 3 (b) is
It goes without saying that the present invention can be applied not only to the image forming apparatus shown in FIGS. 1 and 2, but also to a so-called transfer drum type color image forming apparatus or an image forming apparatus using an intermediate transfer member.

Also, the structure of the transfer brush is not limited to this. For example, as shown in FIG. 4, a conductive adhesive is applied on a flat support member (62),
Directly thereto, the conductive brush thread (60) may be flocked so that its tip is concentrated at one point in the transfer direction of the transfer target.

In the above-mentioned embodiment, the tip of the brush is arranged to be concentrated at one point, but the present invention is not limited to this, and it is narrower than the area L where the image bearing member and the transferred member are in contact with each other. If the tip of the brush is within the range, a sufficient effect can be achieved although it is slightly inferior to the one concentrated at one point.

[0027]

As described above, according to the present invention, the fixed brush is used as the transfer charge applying member, and the tip of the brush is narrower than the area where the image carrier and the transfer target contact with each other in the moving direction of the transfer target. By concentrating within the range, it is possible to prevent image deterioration due to discharge or uneven transfer charges without increasing the cost.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an image forming apparatus to which the present invention is applied.

FIG. 2 is a schematic view showing another image forming apparatus to which the present invention is applied.

FIG. 3 is an explanatory view of a main part showing a transfer device of the present invention.

FIG. 3 is a main part explanatory view showing a modified example of the transfer device of the present invention.

[Explanation of symbols]

 1, 20 ... Photoconductor drum 7, 35 ... Transfer device 50, 60 ... Brush 51 ... Fabric 52, 62 ... Brush support member

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[Procedure amendment]

[Submission date] July 30, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an image forming apparatus to which the present invention is applied.

FIG. 2 is a schematic view showing another image forming apparatus to which the present invention is applied.

FIG. 3 is an explanatory view of a main part showing a transfer device of the present invention.

FIG. 4 is a main part explanatory view showing a modified example of the transfer device of the present invention.

[Explanation of reference numerals] 1,20 ... Photosensitive drum 7,35 ... Transfer device 50, 60 ... Brush 51 ... Fabric 52, 62 ... Brush support member

Claims (5)

[Claims] 1. A transfer device for transferring a toner image on an image carrier to a transfer material or a transfer medium, wherein the transfer device has a brush-like transfer charge applying member and a tip of the brush is a transfer material or a transfer material. A transfer device comprising: a support member for supporting the transfer charge applying member so that the medium is concentrated within a range narrower than a region in contact with the image carrier; and a means for applying a voltage to the transfer charge applying member. 2. The transfer member according to claim 1, wherein the support member supports the transfer charge applying member such that the tip of the brush is concentrated at one point in the moving direction of the transfer material or the transfer medium. apparatus. 3. The transfer device according to claim 1, wherein the support member has a concave surface at a position facing the image carrier, and the brush is provided on the concave surface. 4. A brush-shaped transfer member for transferring a toner image on an image carrier to a transfer medium, wherein the tip of the brush is concentrated within a range narrower than a region where the image carrier and the transfer medium are in contact with each other. The transfer member is characterized in that the brush is supported as described above. 5. The transfer member according to claim 3, wherein the tip of the brush is supported so as to concentrate on one point in the moving direction of the transfer target.