JPH0722684Y2 - Transfer device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a transfer device of an image forming apparatus such as an overlay transfer type color copying machine.

2. Description of the Related Art As a color copying machine using an electrostatographic process, as shown in FIG. 2, color separation filters 2B, 2G, 2R and yellow filter 2Y for blue, green and red are sequentially formed on one photoconductor drum 1 to perform color separation. The four types of latent images are formed by exposing the formed light image of the original 3 to the latent images, and the latent images are arranged around the photosensitive drum 1 in the yellow, magenta, cyan, and black developing units 4Y, 4M, 4C. ,Four
The four-color toner images obtained by developing with BK are fed to the transfer drum 5 which is in contact with the photoconductor drum 1 and rotate at the same linear velocity in synchronism with each other. After the transfer is completed four times, the transfer paper is separated from the transfer drum 5 by the separating claw 8 on the rotated transfer paper S by the action of the transfer charger 7, and is fixed by the fixing device 9. A color copying machine of a so-called color-separated image superposition transfer system, which obtains a color copy by using the color copying machine, is well known.

As the transfer drum, as shown in FIG. 3, a frame body made of metal such as aluminum, which is composed of annular portions 10 at both ends of the drum and one connecting portion 11 for connecting them, and a drum rotating member. The front end edge and the rear end portion in the direction are held by the connecting portion 11 of the frame body, and the side end edge portions are brought into contact along the outer peripheral surface of the frame body to be in contact with the frame body and the dielectric flexible body is wound. Clamper which is formed in a hollow cylindrical shape with the property transfer film 12 and holds the leading end of the transfer sheet S fed from the sheet feeding section 6 to the connecting section 11 of the frame body.
A structure having 13 is widely used. As the transfer film 12, for example, a polyethylene terephthalate film (trade name: Mylar) having a thickness of about 75 to 150 μm is generally used, and the transfer paper S fed from the paper feeding section has its leading end gripped by the clamper 13 and charged. The transfer film 12 charged electrostatically by the charger 14 is electrostatically attracted to the transfer drum 5 so as to be in close contact with the transfer drum 5 without being displaced and to rotate integrally with the transfer drum, so that the four color toner images are not displaced from each other. Transferred overlaid.

In the transfer device having the above structure, it is important that the transfer film and the transfer paper and the transfer paper and the photoconductor drum are in close contact with each other without a gap in the transfer section. When the transfer paper is exposed to a high-humidity atmosphere, it undulates to various extents depending on the degree of humidity or by drying, and when it is adsorbed on a flat transfer film and wound around it, the surface of the transfer film and the back surface of the transfer paper Air is partially collected between and. In this case, there is no problem if the air is extruded to the surroundings because the transfer paper is attracted to the transfer film and the transfer drum and the photoconductor drum are in close contact with each other at the transfer portion. If the surface of the transfer film is smooth, the area around the area where the air is trapped will adhere closely to the surface of the transfer film and the back surface of the transfer paper due to the electrostatic force, and even if the transfer section is pressed against the peripheral surface of the photosensitive drum. The air does not escape to the surroundings and an air layer remains, and the transfer charger acts on the transfer paper via the air layer in the transfer section, so that a transfer omission occurs at that portion, resulting in a blank copy.

As a measure for preventing this development, in JP-A-62-79485, the surface of the transfer film on the transfer paper support side is made rough so that the transfer film and the transfer paper contact only at the protrusions on the rough surface. There is proposed a configuration in which the suction force is weakened so that when the transfer paper is sucked onto the transfer film, the air accumulated during the transfer paper is easily released from the surroundings.

According to this publication, good results are obtained when the transfer paper support surface side has a roughness of about 0.2 to 5 μ, and the surface roughness is 5 μ.
In the case above, although the effect of letting air escape is recognized, clogging by the toner increases in the concave and convex portions of the surface,
This is not suitable because it adheres to the back surface of the transfer paper and contaminates it.

However, recently, the number of types of paper used in copiers has increased, and it is necessary to be able to use ordinary paper. Some papers have a large hygroscopic property and have a large wavy shape or curl. Further, it is also performed to intentionally add water to adjust the humidity for the purpose of adjusting charging characteristics and the like. Under such circumstances, the above-mentioned roughness of about 0.2 to 5 μm cannot achieve the purpose of sufficiently releasing air depending on the type of paper.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of a transfer material support having a surface roughness of a level that has been conventionally proposed, the present invention can be used even when a normal paper is used in a high humidity condition in the rainy season. Another object of the present invention is to provide a transfer device that can obtain a uniform copy without white spots even when intentionally humidity-controlled paper or paper with curl or waviness is used.

Means for Solving the Problems The present invention is characterized in that the transfer material support has a surface roughness of 10 to 30 μHmax in order to achieve the above object.

Action By increasing the surface roughness of the transfer paper support to 10 to 30 μHmax, the suction force between the transfer paper support and the transfer paper becomes smaller than before, so that the transfer paper with wavy due to humidity and dryness Even when a curled transfer paper is used, the air layer can escape more quickly, and the transfer paper adheres to the transfer paper support over the entire surface, eliminating transfer omissions and obtaining an image without white spots. .

Further, since the unevenness becomes large, it is possible to perform sufficiently uniform transfer even if foreign matter such as toner or paper powder is slightly clogged in the recess. As a result, it is possible to perform uniform transfer on curled paper and corrugated paper even at high speed and during multiple transfer.

Example 45 kg of transfer paper (normally used as transfer paper) was used and left for 3 hours under the environmental conditions of a rainy season at a temperature of 30 ° C. and a humidity of 90%. The transfer material support made of various polyethylene terephthalate films was fed to a transfer device mounted on a transfer drum of an actual copying machine, wound around the transfer drum, and transferred.

As the surface roughness of the transfer material support becomes larger, the contact area between the transfer paper and the transfer material support becomes smaller, the adsorption force becomes weaker, and the air between the transfer material in the wavy state and the transfer material support becomes smaller. Is easy to come off.

When the surface roughness increases, the toner enters between the irregularities, but within the range of the above roughness, the cleaning device (reference numeral 15 in FIG. 2) provided along the transfer drum prevents the toner entering the recess. It turns out that it can be removed without difficulty.

In addition, similar experiments were carried out on papers of various thicknesses. As a result, apart from small size papers such as official postcards that are particularly thick and strong, general papers often used for ordinary copying. For the transfer material support surface roughness of 30 μHm
It was confirmed that an image without white spots can be obtained even when the paper is rough to about ax and is wavy due to humidity.

As a result of the above, as shown in FIG. 1, it is appropriate to set the surface roughness of the transfer material support 12 to 10 to 30 μHmax. Reference numeral 16 in the drawing denotes a clamp claw escape hole of the clamper 13.

Further, even if the transfer paper conveyance speed is increased, no particular problem occurs, and it is possible to prevent the transfer speed from decreasing when the number of superposing steps is 4, 6, or the like.

Effect As described above, according to the present invention, when plain paper is heated and humid,
Alternatively, under various humidity control conditions, when used as a transfer paper in a copying machine using a transfer drum, a transfer omission due to waving of the paper does not occur, and a good image without whiteout can be obtained, It is possible to cope with an increase in the transfer paper conveyance speed and an increase in the number of transfer stages.

[Brief description of drawings]

FIG. 1 is a perspective view showing a transfer material support according to an embodiment of the present invention,
FIG. 2 is a side sectional view showing the overall structure of an example of a copying machine having a transfer device to which the present invention is applied, and FIG. 3 is a perspective view showing the structure of the transfer drum. 1 ... Photosensitive drum, 5 ... Transfer drum, 10 ... Transfer drum frame ring part, 11 ... Transfer drum frame connection part, 12 ...
Transfer film (transfer material support), 13 ... Clamper (transfer material tip gripping means), 15 ... Transfer drum cleaning device

Claims (1)

[Scope of utility model registration request] 1. A metal frame body comprising annular parts at both ends of a drum and one connecting part connecting these and extending in the axial direction, and a front end edge and a rear end part in the drum rotation direction. A hollow cylinder formed by a transfer material support body made of a dielectric flexible film, which is held by the connecting portion of the frame body and whose side edges are wound around the frame body along the outer circumferential surface of the frame ring portion. And a transfer material tip gripping means at the connecting portion of the frame body, and a transfer drum which is in contact with the photoconductor drum and rotates at the same peripheral speed in synchronization, and the tip is gripped by the gripping means. Color image formation in which toner images of different colors sequentially formed on the photosensitive drum are sequentially superposed and transferred to the transfer material suction-supported by the transfer material support by a transfer charger provided inside the transfer drum. A transfer device for an apparatus, wherein the transfer material support surface is a rough surface. In the transfer device being characterized in that the 10~30μHmax the surface roughness of the transfer material support.