JPH0519501A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To shorten the size of a photosensitive drum and to reduce its cost and the size of a device by confining the length in the drum axis direction of the nonuniform film thickness part at the ends of a photosensitive layer within 20mm. CONSTITUTION:The length 1 in the drum axis direction of the nonuniform film thickness part at the ends of the cylindrical drum 1 of the electrophotographic sensitive body formed with the photosensitive layer 2 on the outer peripheral surface of the cylindrical drum 1 is confined within 20mm. An annular coating head is used in such a case and the coating is executed in accordance with the coating form using a spacer drum, by which the length 1 in the drum axis direction of the nonuniform film thickness part at the ends of the photosensitive layer on the outer periphery of the hollow drum 1 can be confined within 20mm or 0mm. Further, a photosensitive liquid prepd. by dispersing inorg. photosensitive materials, such as zinc oxide and cadmium sulfide, and org. photosensitive materials, such as polyvinyl carbazole and trinitrosolorene, into a high-polymer binder is usable as the photosensitive liquid to be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member in which a photosensitive liquid is applied on the outer peripheral surface of a cylindrical drum.

[0002]

2. Description of the Related Art Various methods such as dip coating, spray coating, blade coating, and roll coating have been adopted as a method for producing an electrophotographic photosensitive member by coating a photosensitive liquid on the outer peripheral surface of a cylindrical drum. Of these, the dip coating is most commonly performed because it has excellent smoothness of the coating film surface and uniformity of the coating film in the general portion.

[0003]

However, in the dip coating method, the cylindrical drum is vertically oriented and immersed in the photosensitive solution tank and then pulled up to deposit the photosensitive solution on the outer peripheral surface of the drum. Therefore, since the sagging occurs from the upper end side toward the lower end side (gravitational direction),
At the uppermost end of the photosensitive layer, as shown in FIG. 5, there was a portion where the film thickness was not uniform. The length of the non-uniform film thickness in the drum axis direction is usually 20 mm or more. Since the non-uniform film thickness does not sufficiently transfer or fix the toner, the non-uniform film thickness portion is not formed. The drum length must be the extra length and the required development area must be secured.
There are problems such as an increase in cost and an increase in the size of the apparatus itself such as a fax machine or a copying machine having the electrophotographic photosensitive member built therein.

Therefore, a main object of the present invention is to reduce the cost and size of the apparatus by reducing the size of the photosensitive drum by reducing or eliminating the nonuniform thickness portion of the photosensitive layer end portion as much as possible. And

[0005]

In the electrophotographic photosensitive member having a photosensitive layer formed on the outer peripheral surface of a cylindrical drum, the drum axial length of the non-uniform thickness portion at the end of the photosensitive layer is solved. It is possible to solve it by keeping it within 20 mm.

[0006]

According to the present invention, the length of the non-uniform thickness portion of the end portion of the cylindrical drum in the axial direction of the drum is set to 20 mm or less by the coating method described later. The device can be downsized.

[0007]

EXAMPLES The present invention will be described in detail below based on examples. As a coating device for obtaining the electrophotographic photosensitive member according to the present invention, for example, a photosensitive drum can be formed on the outer surface of a hollow drum disclosed in, for example, JP-A-61-25149 and JP-A-58-189061. A coating device that continuously coats the liquid with a coating device that supplies the liquid in a ring shape can be used. Figure 3
Shows an example of a coating device according to the latter publication. Reference numeral 1 denotes a conductive hollow drum as an object to be coated, which is exposed on its outer surface by a slide hopper type coating device according to the present invention in the process of pulling up The liquid is applied to form a photosensitive layer.

A ring-shaped coating head 10 is provided on the outer circumference of the hollow drum 1 so as to continuously surround the hollow drum 1. A narrow coating liquid distribution slit 12 having a coating liquid outlet 11 opening to the hollow drum 1 side is horizontally formed in the coating head 10. The slit 12 communicates with the liquid reservoir header 13, and the photosensitive liquid L is supplied to the liquid reservoir header 13 via a supply pipe 14 by a pressure feed pump (not shown). On the other hand, below the coating liquid outlet 11 of the slit 12, there is a liquid slide surface 15 which is formed so as to continuously incline downward and to terminate at a dimension slightly larger than the outer dimension of the hollow drum 1. Has been formed. Further, a lip portion 16 extending downward from the end of the liquid slide surface 15 is formed. A decompression chamber 17 is formed below the lip 16 and is connected to the decompression pump. When the decompression chamber 17 is decompressed, the photosensitive liquid can be surely introduced to the lip portion 16 and the coatability is improved.

In such a coating apparatus, when the photosensitive liquid L is extruded from the slit 12 and flowed down along the liquid slide surface 15 in the process of pulling up the hollow drum 1, the lip portion 1
The photosensitive liquid reaching 6 is applied to the outer surface of the hollow drum 1 with a thickness corresponding to the clearance between the lip 16 and the outer surface of the hollow drum 1.

In the actual coating, the coating head 1 is used.
In addition to 0, in order to prevent coating failure at the end of the hollow drum 1, it is desirable to continuously coat the photosensitive liquid using a spacer drum as described later. That is, as shown in the coating process diagram of FIG. 6, the first spacer drum 2
1, the first hollow drum 1A, the second spacer drum 22,
The second hollow drum 1B is fitted in order, and the third spacer drum 23 and the third hollow drum 1C are brought in from below the second hollow drum 1B.
While being fitted to the second hollow drum 1B, the third spacer drum 23 and the third hollow drum 1C are simultaneously raised, and the first spacer drum 21,
The photosensitive liquid is applied to the outer surfaces of the first hollow drum 1A, the second spacer drum 22 and the second hollow drum 1B. The first spacer drum 21 and the first hollow drum 1A are removed at an appropriate time, for example, when the second hollow drum 1B is coated halfway. The coating is continuously performed on the third spacer drum 23 and the third hollow drum 1C. It should be noted that the coating head 10 and the coating target 1 may be moved relative to each other, and the coating head 10 may be moved. Alternatively, the application may be performed in the process of lowering the application target 1. Also, the spacer drum 2
At the time of applying the photosensitive liquid to the first, the second, and the second, it is possible to reduce the loss of the photosensitive liquid and prevent the sagging of the lower hollow drum 1 by controlling the coating flow rate.

By using the above-mentioned annular coating head 10 and preferably coating in accordance with the coating mode using the above-mentioned spacer drums 21, 22, 23, ..., As shown in FIG. The length l in the drum axial direction of the film thickness non-uniformity region at the end of the layer is within 20 mm,
Alternatively, it can be 0 mm. The taper inclination θ at the edge of the photosensitive layer is 70 ° or more, preferably 85 ° or more. In this case, the coating procedure is as follows. First, in the case where the spacer drums 21, 22, and 23 are not continuously coated, the hollow drum 1 shown in FIG.
In the process of vertical movement of A to 1C, when the end portion of the hollow drum 1 approaches the coating head 10, the pulling speed is slowed down to suppress sagging as much as possible, and coating is performed. Also, preferably, as described above, the spacer drums 21, 22, 23
In the case where the coating is continuously performed including the above, or when the coating is continuously performed just before reaching the end of the hollow drum 1, it is possible to eliminate the non-uniform film thickness region at the end of the hollow drum 1. it can.

Even in the case of dip coating, as shown in FIG. 2, masking 3 is applied to the other end side (the upper end side in the case of dipping) of the hollow drum 1 and dipping in the photosensitive solution is carried out. By the action of the surface tension of the masking 3, it is possible to eliminate the sagging of the adhered photosensitive liquid, and by removing the masking 3 after drying, it is possible to form a photosensitive layer having a stepped edge.

By the way, as the photosensitive solution used in the present invention, an inorganic photosensitive material such as zinc oxide or cadmium sulfide, or an organic photosensitive material such as polyvinylcarbazole and trinitrofluorene dispersed in a polymer binder is used. it can. In the case of the photosensitive layer on the function separation side,
The charge generation layer can be obtained by dispersing an azo pigment, a quinone pigment, a perylene pigment, a phthalocyanine pigment, an anthanthrone pigment or the like in a polymer binder such as polycarbonate. The charge transport layer can be obtained by dispersing a polycyclic aromatic compound, a nitrogen-containing cyclic compound or the like in a polymer binder.

The thickness of the charge generation layer is 0.01 to 1 μ, preferably 0.05 to 0.5 μ, and the thickness of the charge transport layer is preferably 5 to 20 μ. The viscosity of the photosensitive liquid is in the range of 0.5 to 700 cp, preferably 1 to 500 cp.

The cylindrical object to be coated used in the present invention may be aluminum, stainless steel, plastic having a conductive layer formed thereon, or the like.

[0016]

As described above, according to the present invention, the size of the photosensitive drum can be reduced by minimizing or eliminating the unevenness of the film thickness at the edge of the photosensitive layer formed on the outer peripheral surface of the photosensitive drum. As a result, it is possible to reduce the cost and downsize the device.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an electrophotographic photosensitive member according to the present invention.

FIG. 2 is a vertical cross-sectional view of another example of the electrophotographic photosensitive member according to the present invention.

FIG. 3 is a vertical sectional view of an annular coating device.

FIG. 4 is a schematic diagram showing a coating process in order.

FIG. 5 is a longitudinal sectional view of an electrophotographic photosensitive member showing a profile of a photosensitive layer formed by conventional dip coating.

[Explanation of symbols]

1, 1A, 1B, 1C ... Hollow drum, 10 ... Coating head 11 ... Coating liquid outlet 12 ... Slit, 15 ... Liquid slide surface, 16 ... Lip, 21, 22, 23 ... Spacer drum, L ... Photosensitive liquid

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Kudo, 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (72) Inventor Nobuaki Kobayashi, 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company

Claims (1)

Claim: What is claimed is: 1. An electrophotographic photosensitive member having a photosensitive layer formed on the outer peripheral surface of a cylindrical drum, wherein the length in the axial direction of the drum of the non-uniform thickness portion of the photosensitive layer is 20 mm. An electrophotographic photosensitive member characterized by being within the range.