JPH0784432A - Processing unit for electrophotography - Google Patents

Abstract

PURPOSE:To provide a processing unit for electrophotography where a photoreceptor is hardly electrostatically charged to be positive at the time of assembly and at the time of physical distribution and image defect caused by memory is not found. CONSTITUTION:In the processing unit for electrophotography where either or both of an electrostatic charging member 3 and a cleaning member 2 are arranged to abut on the periphery of an electrophotographic photoreceptor 11; powder consisting of a substance whose electrostatic charging column level is positioned on a more positive side than a substance existing on the surface of the photoreceptor intervenes between either or both of the member 3 and the member 2 and the photoreceptor 4. Therefore, the image defect caused by the memory is not found, so that the processing unit for electrophotography suitable for an electrophotographic printer is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process unit for electrophotography equipped with a process member.

[0002]

2. Description of the Related Art Electrophotographic process units are generally
The electrophotographic photosensitive member is formed by forming a coating of a photoconductor on a cylindrical support, and a charging member, a developing member, a cleaning member, and the like are arranged around the electrophotographic photosensitive member. By the way, these process members may be pressed against the surface of the photoconductor. For example, the case where the charging member is directly brought into pressure contact as the charging device, and the edge of the plate-shaped rubber blade is brought into press contact as the cleaning device, and the like.

In the process unit having such a form, frictional electrification is caused by rubbing against the process member with which the photoconductor is in contact during the manufacturing / assembling process and the physical distribution process up to the user. Cause

Here, in general, the photosensitive member side is likely to be positively charged due to the relationship between the material forming the photosensitive member surface and the process member. Generally, an organic photoconductor is used as a photoconductor for such a process unit from the viewpoint of cost, and since these organic photoconductors generally do not have electron transport ability, when the surface is positively charged, , Electrons as counter charges tend to be easily trapped in the photoconductor. Among organic photoconductors, an oxytitanium phthalocyanine pigment (hereinafter abbreviated as TiOPc), which is particularly useful as a material having high sensitivity in a long wavelength region, has a drawback that negative charges are easily trapped. When such a photoreceptor is used in the process unit as described above and is positively charged by contact with the process member, a memory is generated by the trapped negative charge, and a black stripe corresponding to the contact width of the process member appears in the image. Or there is a problem that white lines appear.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks and to provide an electrophotographic process unit in which the photosensitive member is less likely to be positively charged during assembly and distribution and which does not cause image defects. .

[0006]

That is, the present invention provides an electrophotographic process unit in which one or both of a charging member and a cleaning member are arranged in contact with the periphery of an electrophotographic photosensitive member. A process for electrophotography, characterized in that, between one or both of the members and the photoconductor, a powder composed of a substance having a charge sequence level located on the plus side of the substance present on the surface of the photoconductor is interposed. It is a unit.

The present invention is also the electrophotographic process unit, wherein the substance present on the surface of the photoreceptor is a polycarbonate resin which may be modified.

The present invention is also the electrophotographic process unit wherein the photosensitive layer contains oxytitanium phthalocyanine.

The organic photoreceptor using TiOPc has a charge transport layer composed of a resin and a charge transport material on the surface, and a T layer below the charge transport layer.
A general structure is one in which charge generation layers mainly composed of iOPc are stacked.

On the other hand, the process members that come into contact with the photosensitive member include, for example, a direct charging member and a cleaning member, both of which are often made of a rubber-based elastic body, particularly urethane rubber.

Further, the electric charge generated by the frictional electrification by the photosensitive member and the process member is determined by the charge series level of the material,
Polycarbonate resin, which is a general material for forming the surface of the photoconductor, is likely to be positively charged by rubbing with urethane rubber. However, by interposing a powder of a material, which is the positive side in the charging sequence level with polycarbonate, between the process member and the surface of the photoconductor, the surface potential of the photoconductor during rubbing is lowered, resulting in an image The memory that causes a defect can be reduced.

Since TiOPc has a high sensitivity in a long wavelength region, it has come to be widely used as a photosensitive material for electrophotographic printers whose market is expanding in recent years. However, according to the study by the present inventors, it was found that TiOPc has a drawback that the trap level of the minus carrier is deep and the memory when it is positively charged is large.

Therefore, the present invention is particularly useful for applying TiOPc to a photoreceptor in the form of the process unit.

Next, a specific embodiment of the present invention will be described.

The support of the photosensitive member may be basically any one as long as it can be formed into a cylindrical shape, but metal, particularly aluminum is preferable.

The photosensitive layer provided on the support is not particularly limited, but the present invention works effectively in the case of a photosensitive layer mainly containing an organic material, and a plurality of layers are laminated. The configuration is general. TiOP on the support
A charge generation layer containing c as a main component is provided, and a charge transport layer made of a charge transport material and a resin such as polycarbonate is provided. An intermediate layer or the like may be appropriately provided between the support and the charge generation layer. These films may be formed by known means.

Next, FIGS. 1 and 2 are conceptual diagrams showing examples of the electrophotographic process unit of the present invention.

In FIG. 1, 2 is a blade-shaped cleaning member, 3 is a corona charging member, 4 is a photoconductor, and 1 is a process unit including them.

In FIG. 2, 2 is a similar cleaning member, 4 is a photoconductor, 6 is a direct charging member that is pressed against the photoconductor, 7 is a developing device that does not contact the photoconductor, and 5 is provided with them. It is a process unit. The cleaning member may take the form of a roller, a brush, or the like, in addition to the blade-like form shown here. Further, the form of the direct charging member may take the form of a blade, a brush or the like, in addition to the roller form shown here.

According to the present invention, the powder which becomes positive on the charging line level with polycarbonate is brought into contact with the photoconductor and the photoconductor in the process unit, that is, one or both of the cleaning member and the direct charging member. By interposing it between them, the photosensitive member is less likely to be positively charged. Examples of the powder material used in the present invention include polymethylmethacrylate and polyamide resin. Spherical particles of 10 μm or less are preferable in consideration of frictional resistance and scratches on the photoreceptor. As a method of interposing the powder between the photoconductor and the contact member, the powder is dispersed in a solvent that does not dissolve itself and applied to the contact member, or the powder is directly applied to the contact member. Method etc. are mentioned.

[0021]

EXAMPLES Next, the present invention will be described with reference to examples. Example 1 A photoconductor having the following constitution was prepared. -Support: 30Φ, 254 mm, 0.75 mm thick aluminum cylinder. A photosensitive layer was formed by sequentially laminating and coating layers having the following constitution. Conductive coating layer: Mainly composed of tin oxide and titanium oxide powder dispersed in phenol resin. Film thickness 20μ
m. Undercoat layer: Mainly composed of modified nylon and copolymer nylon. The film thickness is 0.7 μm. Charge generation layer: TiOPc (however, the diffraction angle 2θ ± 0.2 ° in the X-ray diffraction spectrum of CuKα is 9.
The crystals mainly have crystals having strong peaks at 0 °, 14.2 °, 23.9 ° and 27.1 °) dispersed in butyral resin. The film thickness is 0.2 μm. Charge transport layer: The following compound (A) as a charge transport material,
(B), the following compounds (C) and (D) as a binder resin

[0022]

[Chemical 1]

(A) / (B) / (C) / (D) = 5.6
A mixture of monochlorobenzene and dichloromethane mixed and dissolved to give a ratio of /2.4/9.5/0.5 was applied. The film thickness is 25 μm.

After the driving gears and bearings were attached to both ends of the photoconductor thus prepared, the charging, developing and cleaning members were incorporated into an integrated process unit. The charging member is a direct charging roller mainly composed of urethane rubber, and the cleaning member is a plate blade mainly composed of urethane rubber. Since the developing device is not in contact with the photoconductor, the description is omitted.

However, a liquid in which 20 parts by weight of polymethyl methacrylate (MD series manufactured by Toray Industries, Inc.) (which is on the positive side in the charging line with polycarbonate) is dispersed in methanol is used for the plate blade of the cleaning member and the direct charging roller of the charging member. Was applied.

After the assembly, it was rotated at 30 rpm for 60 seconds, and after standing for 5 seconds, the surface potential was changed to Model 344 manufactured by Trek.
It was measured with a surface potential meter.

One day after this test, the process unit was mounted on a laser beam printer (LBP-LX, manufactured by Canon) and the image was evaluated.

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1. This photoconductor was incorporated into a process unit as in Example 1. However, on the plate blade of the cleaning member and the charging roller of the charging member (on the negative side in the charging line with polycarbonate)
A solution prepared by dispersing 20 parts by weight of polyethylene (manufactured by Asahi Kasei Kogyo Co., Ltd., Suntech LD) in methanol was applied.

The surface potential was measured and the image was evaluated in the same manner as in Example 1.

Example 2 A photoconductor was prepared in the same manner as in Example 1. This photoconductor was incorporated into a process unit as in Example 1. However, the plate blade of the cleaning member and the charging roller of the charging member were coated with a solution of 20 parts by weight of a polyamide resin (SP-500 manufactured by Toray Industries, Inc., SP-500 on the positive side in the charging column with polycarbonate) dispersed in methanol.

Surface potential measurement and image evaluation were performed in the same manner as in Example 1.

Comparative Example 2 A photoconductor was prepared in the same manner as in Example 1. This photoconductor was incorporated into the same process unit as in Example 1. However, nothing was applied to the plate blade of the cleaning member and the charging roller of the charging member. Surface potential measurement and image evaluation were performed in the same manner as in Example 1.

Example 3 A photoconductor was prepared in the same manner as in Example 1. However, the binder resin used in the charge transport layer is the following compound (E)

[0034]

[Chemical 2]

Change to (A) / (B)
/(E)=5.6/2.4/10. This photoconductor was incorporated into a process unit as in Example 1. The polyamide resin (SP-500) was applied to the plate blade of the cleaning member and the charging roller of the charging member as in Example 2.

The surface potential was measured in the same manner as in Example 1 to evaluate the image.

Example 4 A photoconductor was prepared in the same manner as in Example 1. However, the mixing ratio of the materials used in the charge transport layer is (A) / (B) /
(C) = 5.6 / 2.4 / 10. This photoconductor was incorporated into a process unit as in Example 1. The polyamide resin (SP-500) was applied to the plate blade of the cleaning member and the charging roller of the charging member as in Example 2. In the same manner as in Example 1, the surface potential was measured and the image was evaluated. The results of the above Examples and Comparative Examples are summarized in Table 1.

[0038]

[0039]

As described above, this process unit is suitable for use in electrophotographic printers in particular because it provides a memory-free image due to the photoconductor contact member.

[Brief description of drawings]

FIG. 1 is a schematic side view of an example of an electrophotographic process unit of the present invention.

FIG. 2 is a schematic side view of an example of an electrophotographic process unit of the present invention.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location G03G 21/00 21/18 (72) Inventor Yama ▲ saki ▼ 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hideyuki Ainoya 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Hidetoshi Hirano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Within

Claims (3)

[Claims] 1. In an electrophotographic process unit in which one or both of a charging member and a cleaning member are arranged in contact with the periphery of an electrophotographic photosensitive member, one or both of the charging member and the cleaning member and the photosensitive member are provided. A process unit for electrophotography, characterized in that a powder consisting of a substance having a charge series level on the plus side of the substance existing on the surface of the photoconductor is interposed between the two. 2. The substance existing on the surface of the photoreceptor is a polycarbonate resin which may be modified.
The described electrophotographic process unit. 3. The electrophotographic process unit according to claim 1, wherein the photosensitive layer contains oxytitanium phthalocyanine.