JPH0455329Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a transfer drum of an electrophotographic copying machine.

Conventional technology An electrophotographic technique in which a transfer paper is wrapped around a transfer drum equipped with a film, a corona discharge is generated from the inside of the film, and the toner image on an adjacent photoreceptor drum is transferred onto the transfer paper by the electric charge of the transfer drum. Copying machines are already known.

The film attached to the transfer drum of a copying machine as mentioned above is made of a single layer, and its two typical constituent materials are (1) polyester film and (2) high dielectric film. I can give it to you.

Problems to be solved by the invention However, (1) polyester film has the advantage of being high in strength and difficult to deform; In order to obtain the amount, the potential must be increased. As a result, if you want to make solid areas look good when making multicolor copies, you need to increase the potential and also increase the potential difference with the photoreceptor for each copy in multiple copies, but in low-density image areas, peeling discharge occurs. This results in poor transfer. Therefore, in order to prevent peeling discharge, the potential has to be lowered, which has the disadvantage that a transfer current for optimum transfer cannot be applied. In addition to this, the transfer efficiency varies depending on the environmental conditions, and there are disadvantages in that peeling discharge is likely to occur in a low humidity environment.

(2) High dielectric films have higher transfer efficiency for the opposite reason to polyester films, but they have low strength and are easily deformed.
It had drawbacks such as transfer omission, which made it difficult to put it into practical use.

The purpose of this invention is to eliminate the drawbacks of the conventional transfer drum as described above, and to create a film that has high strength and is not easily deformed, has a large capacitance, has good transfer efficiency, and is free from peeling discharge. To provide a transfer drum that does not cause transfer defects.

Means for Solving the Problems In order to achieve the above-mentioned object, this invention has a film attached to a transfer drum that is composed of a base layer made of a polyester film and a high dielectric material coated on the base layer. It is characterized in that it is formed with a body layer, specifically, a polyvinylidene fluoride layer.

Function: Due to the structure of the attached film, the transfer drum as described above maintains high strength, has a large capacitance, can increase the amount of charge, and is less likely to cause peeling discharge.

Embodiment In FIG. 1, reference numeral 1 indicates a transfer drum, which is composed of a drum frame 2 and a film 3 mounted thereon, and is provided with a clamper 4.

As shown in FIG. 2, the film 3 is formed of a base layer 5 made of polyester film and a polyvinylidene fluoride layer 6 coated thereon. In the figure, 7 represents a charger, 8 represents a photosensitive drum, and 9 represents a transfer paper. Also 10,
Reference numeral 11 indicates positively charged toner and negatively charged toner on the surface of the photoreceptor drum 8, respectively.

The capacitance of the film 3 will be described. The capacitance C1, C2 of each layer 5, 6 is C1=ε1
It is given by S1/α1, C2=ε2S2/α2. Here ε1, ε
2 is the dielectric constant, S1 and S2 are the areas, and α1 and α2 are the film thicknesses.

By the way, in the case of this example, the film thicknesses of both layers α1,
Both α2 are 50μ, ε1 is 3, and ε2 is 9.

On the other hand, the combined capacitance of both layers 5 and 6, ie, the capacitance C of the film 3, is given by 1/C=1/C1+1/C2.

Using the above formula, when we calculate the ratio of the capacitance of a film with a thickness of 100μ made only of conventional polyester to the capacitance of film 3, assuming both areas are the same, it becomes 2:3. It can be seen that the film of the above example has a capacitance 1.5 times that of the film shown in FIG.

Next, the mechanical strength of the film 3 will be described. The tensile elastic modulus of the polyester film forming the base layer 5 is usually about 40,000 kg/
cm ² , and the coefficient of polyvinylidene fluoride forming the high dielectric layer 6 is approximately 14000 Kg/cm ² . On the other hand, the tensile elastic modulus required is approximately 25,000, taking into account the force applied when a thick material such as a postcard is wrapped as a transfer paper, and the force due to twisting.
Kg/ ^cm2 . However, from the above, since the film 3 has a composite coefficient of 27000 kg/cm ² , the film 3 is placed on the drum body 2.
It can be seen that it has sufficient mechanical strength to prevent deformation.

Effects of the invention This invention is as described above, and since the film attached to the transfer drum is formed of a polyester film and a polyvinylidene fluoride coating layer, the film will not be dented or deformed. Since there is no transfer, there is no risk of transfer failure, and the capacitance is large, so a large amount of charge can be taken. Therefore, the transfer rate is particularly good for multi-colored solid areas, and it can be peeled off even in a low humidity environment. This has the advantage of not causing transfer defects due to discharge.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the invention, and FIG. 2 is a sectional view of a portion of the same during use. 1... Transfer drum, 2... Drum body, 3...
Film, 4... Clamper, 5... Base layer, 6
...High dielectric layer.

Claims (1)

[Scope of utility model registration request] A transfer drum of an electrophotographic copying machine that wraps a transfer paper around a transfer drum equipped with a film, generates corona discharge from the inside of the film, and uses the electric charge to transfer the toner image on the photoreceptor drum adjacent to the transfer drum onto the transfer paper. A transfer drum for an electrophotographic copying machine, wherein the film is formed by coating a polyvinylidene fluoride layer on a polyester film.