JP2529601Y2 - Transfer device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device of an image forming apparatus such as a color copying machine of a superimposed transfer system.

Prior Art As a color copying machine using an electrostatographic process,
As shown in the figure, blue, green,
The light images of the color-separated original 3 are exposed through the red color separation filters 2B, 2G, 2R and the yellow filter 2Y to form four types of latent images, and the respective latent images are arranged around the photosensitive drum 1. Yellow, magenta, cyan and black developing units 4Y, 4M, 4
The toner images of four colors obtained by developing with C, 4BK are fed to the transfer drum 5 rotating at the same linear speed in synchronization with the photosensitive drum 1 and fed to the position A from the feeder 6. The transfer paper is superimposed and transferred onto the wound transfer paper S by the action of the transfer charger 7, and after the transfer is completed four times, the transfer paper is separated from the transfer drum 5 by the separation claw 8 at the part B, and 2. Description of the Related Art A color copying machine of a so-called color division image superimposing transfer system in which a color copy is obtained by fixing is well known.

As shown in FIG. 6, the transfer drum includes the annular portions 10 at both ends of the drum and one connecting portion 11 for connecting them.
And a frame made of metal such as aluminum, and a front edge and a rear edge in the drum rotation direction are held by the connecting portion 11 of the frame, and the side edge is formed on the outer peripheral surface of the frame. A dielectric flexible transfer film 12 abutted along and wound around the frame.
Thus, a structure having a clamper 13 which is formed in a hollow cylindrical shape and has a connecting portion 11 of the frame body and which grips the leading end of the transfer paper S fed by the paper feeding unit 6 is widely used. As the transfer film 12, for example, a film of polyester or polyvinylidene fluoride having a thickness of about 75 to 150 μm is generally used, and the transfer paper S fed from the paper feeding unit is gripped at its tip by the clamper 13 and charged. The toner is electrostatically attracted to the transfer film 12 charged by the charger 14 and adheres to the transfer drum 5 without shifting, and rotates integrally with the transfer drum, and the four-color toner images overlap without shifting. It is transferred together.

In the transfer device having the above-described configuration, it is important that the transfer film and the transfer paper, and the transfer paper and the photosensitive drum are in close contact with each other at the transfer portion without any gap. When the transfer paper is exposed to a humid atmosphere, it undulates in various ways depending on the degree of humidity, and when it is wound onto a flat transfer film and wound, there is a partial gap between the front surface of the transfer film and the back surface of the transfer paper. Air accumulates. In this case, the transfer paper is attracted to the transfer film,
There is no problem if the transfer drum and the photoreceptor drum come into close contact with each other at the transfer section, so that the air is extruded to the periphery and escapes, but if the surface of the transfer film is a glossy surface, the area around the area where air is trapped The surface of the transfer film and the back side of the transfer paper are tightly adhered to each other by electrostatic force without any gap.Even if the transfer unit is pressed against the peripheral surface of the photoreceptor drum, air does not escape to the surroundings and an air layer remains. Since it acts on the transfer paper via the air layer, a missing transfer occurs in that portion, resulting in a blank copy.

As a measure to prevent this phenomenon, JP-A-62-79485 discloses that the surface of the transfer film on the transfer paper support side is roughened,
A structure in which the transfer film and the transfer paper come into contact with each other only at the protruding portion of the rough surface to reduce the attraction force, so that when the transfer paper is adsorbed on the transfer film, the air accumulated during the transfer can easily escape from the surroundings. Has been proposed.

It has been proposed by the present applicant in Japanese Utility Model Application No. 64-000148 that the surface roughness of the rough surface should be 10 to 30 μHmax.

By this method, the white spot phenomenon caused by the air remaining between the transfer film and the transfer paper can be prevented,
In a high-temperature, high-humidity environment, the electrostatic attraction force between the transfer paper and the transfer film is significantly weakened. In particular, the rear end of the transfer paper is a transfer paper carrying the unfixed toner image by the transfer paper itself, its own weight, and centrifugal force. The paper is easily separated from the surface of the transfer film. In this case, the rear end of the transfer paper comes into contact with a nearby member around the transfer drum, and a so-called rear end image rubbing phenomenon occurs.

The reason for the decrease in the electrostatic attraction force is that when the surface roughness of the transfer film is 10 to 30 μHmax, the shape of the surface is usually like a sine curve when viewed in cross section, and the transfer paper and the transfer film Because the area occupancy of the actual contact surface is small, the surface resistance of the transfer film is reduced due to the moisture absorption of the transfer film surface in a high-temperature, high-humidity environment. It is conceivable that the paper escapes toward the edge of the paper. In addition, the surface resistance of the transfer film surface at high temperature and high humidity can be reduced especially when a considerable number of copies are made, because nitric oxide (NOx) adsorbs to the surface of the transfer film that has been roughened over time. It is thought to be easier.

FIG. 4 shows the result of measuring the occurrence rate of rubbing of the rear end screen of a relatively thick 110 kg paper (the paper thickness is usually about 80 μm) by variously changing the area ratio of the transfer paper contact concave portion. According to this figure, even when the thickness of the contact protrusion area is set to 20% or more, the occurrence rate of the trailing edge image rubbing is 0.1% even for relatively thick 110 kg paper.
%, Which is very small.

Problems to be Solved by the Invention The present invention has been made in view of the above-mentioned problems of the transfer device of the image forming apparatus in which the surface of the transfer film (transfer material support) of the transfer drum is roughened. Even when the surface of the transfer material support adsorbs nitric oxide over time, the required electrostatic attraction force is maintained between the transfer material support and the transfer material, and the transfer material support surface is roughened. It is an object of the present invention to provide a transfer device capable of preventing not only partial transfer omission or transfer failure due to this, but also preventing a trailing edge image rubbing phenomenon.

Means for Solving the Problems In order to solve the above problems, the present invention provides a transfer device of an image forming apparatus in which a transfer material contact surface of a transfer material support of a transfer drum is roughened. The contact surface with the material is processed to a surface roughness of 10 to 30 μHmax, and the convex surface that actually contacts the transfer material on the contact surface occupies 20% or more and 80% or less of the entire contact surface. It is characterized by having.

It is desirable that the concave portion on the rough surface communicates to the outside in a state where the maximum size transfer material is adsorbed on the transfer material support.

Function As described above, the convex portion of the contact surface of the transfer material support with the transfer material has an area occupancy of 20% or more and 80% or less of the entire contact surface. While eliminating
In a high-temperature, high-humidity environment, the surface of the transfer material and the support of the transfer material are easily absorbed by absorbing moisture, particularly nitric oxide over time, and the surface resistance of the transfer material and the support of the transfer material is reduced. Even if the electrostatic attraction force per unit area of the contact area decreases, the contact area ratio is as large as 20% or more. Therefore, the static area per unit area of the rough surface contact part and non-contact part is combined. The electroadhesive force is increased, and the transfer material sufficiently adheres to the transfer material support even in a high-temperature, high-humidity environment, a good image is formed, and the occurrence of rubbing of the rear end image is prevented.

Also, if the concave portion of the rough surface is communicated to the outside while the maximum size transfer material is adsorbed on the transfer material support, the transfer material is in a wavy state due to moisture absorption, and between the transfer material support and the transfer material support. Even if air is interposed, the air can easily escape to the outside, and transfer defects and white spots due to poor adhesion due to bubbles can be prevented.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a view of a transfer film 12 of an embodiment in which the present invention is applied to the transfer device described above with reference to FIG.

The front end in the rotation direction of the transfer film 12 when attached to the drum is adhered to the surface of the connecting portion of the frame by means not shown. In addition, a relief hole 15 is provided in that portion for the nail of the clamper 13 to bite.

Area surrounded by chain lines in the diagram of the surface of the transfer film 12
Reference numeral 12a denotes a contact area of the maximum size (for example, A3 size) transfer paper used in this image forming apparatus, and the surface roughness is
It has a rough surface of 10 to 30 μHmax.

Outside the contact area 12a of the transfer paper of the maximum size, an outer peripheral portion 12b of a slight width supported by the frame is provided.

In this embodiment, to form a rough surface having a surface roughness of 10 to 30 μHmax, regardless of sandblasting or the like, as shown in FIG. 1 and FIG. The minute grooves 17 are formed in parallel in the horizontal direction to have a rough surface. By doing so, it is possible to increase the area ratio at which the protrusions of the uneven surface are in close contact with the transfer paper.

The V-shaped groove extends slightly outward from the edge of the contact area of the maximum size transfer paper indicated by a chain line in FIG. Therefore, even when the transfer paper is waving due to moisture absorption or the like, and air partially accumulates between the transfer film 12 and the transfer paper δ,
It is easily extruded out of the range of the transfer paper, thereby preventing transfer failure and white spots due to bubbles.

FIG. 3 is a view showing another embodiment of the transfer film. In this embodiment, fine V-shaped grooves are provided in parallel in the longitudinal direction, and the front and rear ends thereof are in contact with the transfer sheet of the maximum size. It extends slightly outward.

In addition, although not shown, a V-shaped groove is provided on a grid,
It is also possible to provide at an angle. It is also possible to use a U-shaped groove instead of the V-shaped groove.

Note that if the surface of the transfer film that is in contact with the transfer paper outside the transfer paper contact area is subjected to a treatment such as a glossy surface treatment or a coating of a hydrophobic substance that does not easily lower the surface resistance of the transfer film, the transfer paper contact surface is not affected. The charge leakage to the outside of the transfer paper contact area of the contact surface is prevented, the electrostatic attraction force is maintained, and the effect of preventing the rear end image rubbing is further ensured.

As a means for preventing a decrease in the electrostatic attraction force between the transfer sheet and the transfer paper, covering the transfer sheet abutment area on the surface of the transfer sheet with the ozone and NOx removal substance film is also effective. By doing so, the NO of that surface
The adsorption of x is reduced, and the effect of preventing the reduction of the surface resistance of the derivative sheet prevents the transfer failure from occurring even in a high-temperature and high-humidity environment, and also prevents the trailing edge of the image from being rubbed.

Effects As described above, according to the present invention, even if the transfer paper is in a wavy state under a high-temperature and high-humidity environment, the air accumulated between the transfer film and the transfer film can easily escape to the surroundings by making the transfer film rough. In addition, image defects such as white spots are prevented, and the area occupancy of the convex portion of the rough surface that contacts the transfer paper is set to 20% or more and 80% or less. To prevent the trailing edge image from rubbing.

[Brief description of the drawings]

FIG. 1 is a plan view showing the surface of the transfer material support according to the embodiment of the present invention, FIG. 2 is an enlarged sectional view taken along line 2-2 in FIG. 1, and FIG. FIG. 4 is a plan view showing the surface of the transfer material support of the embodiment, FIG. 4 is a curve diagram showing the relationship between the transfer paper contact convex area ratio and the trailing edge image rubbing rate based on actually measured data, and FIG. FIG. 6 is a cross-sectional view showing the overall configuration of an example of a color image forming apparatus using the same. FIG. 6 is a perspective view showing the configuration of the transfer drum. 1 photosensitive drum 5 transfer drum 10 transfer drum frame 12 transfer film (transfer material support) 12a maximum contact area of transfer paper 12b outer peripheral part 17 V-shaped fine Groove 15 Transfer paper (transfer material)

Claims (2)

(57) [Scope of request for utility model registration] A transfer material support comprising a dielectric flexible film wound around a drum-shaped body, and toner images of different colors sequentially formed on a photoreceptor are sequentially superimposed and transferred onto a transfer material. In the transfer device of a color image forming apparatus, the contact surface of the transfer material support with the transfer material is 10 to 30 μHmax.
Of the contact surface, and the convex surface that actually contacts the transfer material on the contact surface is 20% of the entire contact surface.
A transfer device having an occupancy of at least 80% and not more than 80%. 2. The transfer member according to claim 1, wherein the recess on the contact surface communicates with the outside of the transfer material contact area in a state where the transfer material having the maximum size is adsorbed on the transfer material support. Transfer device.