JPH012084A - electrophotographic equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention develops an electrostatic latent image formed on the surface of a drum having a photosensitive layer on the surface with toner, and after the transfer, the residual toner on the drum is removed. The present invention relates to an electrophotographic apparatus of a type in which toner is removed by a cleaning member, and particularly to an electrophotographic apparatus of the above type in which a positioning member provided on a toner supply member for the drum, a cleaning member, a charger, etc. is brought into abutment against the drum.

[Conventional technology]

Generally, in an electrophotographic device, a charger is installed around a photoconductive electrophotographic photoreceptor drum, and an image exposure section (a light spot containing image information using an intermittent scanning laser beam, intermittent light from a liquid crystal shutter array, an LED array, etc.) A developing device, a transfer device, a cleaning device, a static eliminating exposure device, etc. are arranged according to a predetermined electrophotographic process. FIG. 4 shows an example of this, in which an electrophotographic photosensitive drum 1 rotating in the direction of the arrow is charged by a charger 2 and subjected to image exposure by an optical section 3. In the developing device 4, the magnetic toner 5 adheres to the surface of a cylindrical toner supply body 7 due to the action of the magnetic body 6, and is conveyed to the developing section 9 with its thickness regulated by a doctor blade 8. The toner image on the photosensitive drum developed in the developing section is transferred onto transfer paper 13 by transfer charger 12 . The remaining toner that has not been transferred at this transfer section is removed from the photosensitive drum by a cleaner blade 14.

In such an electrophotographic apparatus, the photosensitive drum is comprised of a metal cylindrical body with a photosensitive layer provided either directly or via an intermediate layer such as a barrier layer or a conductive layer.

In the above-mentioned electrophotographic apparatus, in the developing process,
When attaching toner particles according to the electrostatic charge image on the surface of the photoreceptor drum, the distance between the toner supply body holding the toner particles and the photoreceptor drum is important, and this distance is as follows:
Each part of the photoreceptor drum and toner supply body must be uniform. If this gap is too wide, it becomes difficult for toner to develop, resulting in a decrease in image density, while if it is too narrow, excess toner tends to stick to it.
Images with thin lines may become thicker, or toner may adhere to areas that should not be developed, causing background fog.

Especially in the case of the so-called jumping development method,
As described in Japanese Patent Application Laid-open No. 4-42141 and Japanese Patent Application Laid-Open No. 55-18659, the influence of the variation in the distance between the photosensitive drum and the toner supply body due to the rotation of the photosensitive drum is large.
-Must be kept in good condition.

In addition, in the cleaning process, when cleaning the surface of the photoreceptor drum of toner that was not transferred in the transfer process, the contact pressure with cleaning members such as rubber blades and wire brushes is important, and this contact pressure is always constant. There must be. For this purpose, the distance between the cleaning member holder and the photosensitive drum must always be constant. If the pressure is too high, damage such as scratches is likely to occur on the photoreceptor drum, while if the pressure is too low, poor cleaning will occur and the image will be stained.

Furthermore, in the charging process, the distance between the charging wire and the photosensitive drum is important, and this distance must always be kept constant. If this distance is large, the amount of charge on the photosensitive drum will be small, and if the distance is small, the amount of charge will be large, so in either case, the image density will change.

As a means of solving the above-mentioned problems, the toner supply body and the photoconductor drum can be connected by abutting the toner supply body of the developing device, the cleaning member of the cleaner, or the positioning member provided on the charger against the photoconductor drum. and the contact pressure between the cleaning member and the photoreceptor drum,
It is also known to keep the distance between the charging wire and the photosensitive drum constant.

However, even such a method has several drawbacks, such as unevenness and staining of the image and poor durability, leaving many practical problems.

[Problem that the invention seeks to solve]

It is an object of the present invention to solve the above-mentioned problems in an electrophotographic apparatus equipped with a developing device, a cleaning device, or a charging device using a positioning member, to always form sharp and stain-free images, and to The purpose is to extend the life of the drum.

[Means for solving problems]

That is, the electrophotographic apparatus of the present invention includes an electrophotographic photoreceptor having a photosensitive layer on a support with an intermediate layer interposed therebetween, and a positioning member disposed at an end of the photoreceptor. The intermediate layer has a harder hardness than the support, and the positioning member is disposed in direct contact with the exposed portion of the intermediate layer at the end of the photoreceptor.

The present invention will be explained in detail below.

The positioning member in the present invention means a roller that rotates simultaneously with the photoreceptor drum, a stationary spacer, or the like.

2 and 3 (a), (b), and (c) are diagrams respectively showing the relationship between the toner supply body and the photosensitive drum of the developing device having a roller abutment as a positioning member, and the same reference numerals as in FIG. 4 are shown. indicate the same thing. First, in FIG. 2, l is a photosensitive drum, 7 is a cylindrical toner supply body, 11 is a photosensitive layer formed on a metal support, 15 is a roller pivotally supported on the toner supply body, and the diagonal line in the figure The portion C indicated by the arrows indicates the surface portion of the photosensitive drum 1 that is hit by these rollers. This is a method of hitting the roller directly onto the metal support, but in this case, due to repeated use of the photoreceptor drum, ■ The metal support is easily scraped, ■ If the metal support is particularly thin, it may become deformed. The disadvantage is that it is easy to cause

In either case, the distance between the toner supply body 7 and the photosensitive layer 11 changes, resulting in changes in image quality and image density.

Further, if metal powder generated by scraping of the metal support is present on the photosensitive layer, the surface of the photosensitive layer may be scratched, or it may leak during application of high pressure during toner development, causing image defects.

(2) can be prevented by using a metal support with sufficiently high hardness, but the cylindrical metal support used for electrophotographic photosensitive drums generally requires high surface and dimensional accuracy, so the cylindrical material is cut. It is often processed and served.

Therefore, it is necessary that the metal material has a certain degree of machinability, and for this reason, it is necessary to use a support that is soft enough to be cut by rubbing against the positioning member.

Next, in FIG. 3(a), in order to eliminate the above-mentioned drawbacks, a protective film 16, which is harder than the support, is provided at the end of the support l that is in contact with the rollers.

In this case, it is conceivable that the protective film is formed by coating a curable resin or the like, but its drawbacks include (1) that the production process of the photosensitive drum is complicated; Furthermore, it is difficult to coat such a narrow area with uniform thickness and precision. Specifically, for example, as shown in FIG. 3(b), the protective film 16 may penetrate into the photosensitive layer 11, Alternatively, as shown in FIG. 3(c), a gap may occur between the photosensitive layer 11 and the photosensitive layer 11. In the case of (b), ■ the protective film invades the image area of the photosensitive layer;
■If the photosensitive layer is a solvent-coated type, it will be attacked by the solvent when forming a protective film. There are drawbacks such as: Also, in the case of (C) ■
There are disadvantages in that the gap between the photosensitive layer and the protective film is clogged with toner or paper dust, which stains the image area and changes the distance between the donor donor 7 and the photosensitive layer 11.

Although the developing device has been described above, similar problems exist in cleaning devices and charging devices that have other positioning members.

However, according to the present invention, the above-mentioned problems can be solved.

Similar to FIGS. 2 and 3, FIG. 1 is a diagram showing the relationship between a toner supply body of a developing device having a roller abutment and a photosensitive drum, respectively. A photosensitive layer 11 is provided on a cylindrical metal support 1 with an intermediate layer 17 interposed therebetween. On the other hand, the distance between the toner supply body 7 and the photosensitive layer is such that the roller 1 supported on the toner supply body in the intermediate layer is
It is kept constant by hitting 5.

This intermediate layer is mainly formed of a curable resin containing pigment, and since its hardness is greater than that of the metal support, it will not be scratched even if it is hit by a roller during repeated use.

In addition, since this intermediate layer is coated over the entire surface of the support, it is possible to eliminate the complexity of the manufacturing process and the instability of the film thickness associated with edge coating as in the example shown in FIG. 3 mentioned above.

Furthermore, when the photosensitive layer is formed by coating, the same apparatus type can be used for the intermediate layer coating process and the photosensitive layer coating process, making continuous production possible, which is particularly suitable.

In addition, when the thickness of the support is made thinner for the purpose of reducing the weight and cost of the photoreceptor drum, the mechanical strength becomes weaker.
Distortion due to abutting rollers is likely to occur, but the presence of the intermediate layer of the present invention has the effect of preventing this.

Although materials such as aluminum, copper, and stainless steel are used as the metal support, the present invention is particularly effective in the case of aluminum or an aluminum alloy.

As mentioned above, the support for electrophotographic photoreceptors is often made by cutting a cylindrical material in order to improve dimensional accuracy (in that case, it is preferable to use aluminum or aluminum alloy, which has some workability). This is because it is common.Specifically, AI!7Mn alloy (classification code 300
0 series), AI! -Mg-3t alloy (classification code 6000
(number system) is suitable.

As the curable resin forming the intermediate layer, epoxy resin,
Common materials such as phenol resin, urethane resin, acrylic resin, cyclic rubber, melamine resin, and alkyd resin can be used. The intermediate layer of the present invention further contains a pigment.

The following three effects can be cited as effects of including pigments. ■The curable resin that is the main component of the intermediate layer generally has a low molecular weight, so the viscosity during application is low and it is difficult to obtain a sufficient film thickness.
Further, there is a problem that the coating film tends to sag in the direction of gravity, resulting in uneven film thickness. By dispersing the pigment therein, the viscosity increases and it becomes thixotropic, thereby eliminating the above-mentioned drawbacks. (2) Including pigments such as metal powder and metal oxide has the effect of increasing the hardness of the intermediate layer. (2) The intermediate layer can be made conductive by selecting a conductive pigment. This makes it possible to cover defects in the metal support, which produces important effects in terms of simplifying the structure of the drum and making it easier to manufacture.

Therefore, in order to make such an electrically conductive intermediate layer, the pigment contained in the intermediate layer is preferably electrically conductive, and more preferably, it is a pigment that can impart hardness.

Examples of such materials include tin oxide, zinc oxide, titanium/indium oxide, carbon fiber, iron powder, silicon carbide, etc., but they are not limited to these single materials. A pigment whose surface is coated with a conductive substance may also be used.

Pigments and resins are processed using ball mills, sand mills, roll mills,
Dispersion can be performed using a common dispersion means such as a homogenizer.

When applying the thus obtained intermediate layer paint onto a cylindrical metal support, coating methods such as dip coating, spray coating, spinner coating, bead coating, blade coating, and curtain coating may be used. The resin is coated to both ends or one end of the support using a solvent, and the resin is heated and cured according to the curing conditions of the resin used.

It becomes difficult to impart strength. If the thickness is 50 μm or more, it becomes difficult to form a uniform coating film, and the surface smoothness tends to be lost due to uneven shrinkage during curing.

The photosensitive layer provided on the intermediate layer may be formed by vacuum evaporation of chalcogenide compounds such as selenium, arsenic selenide, selenium-tell-arsenic alloy, silicon, germanium, phthalocyanine pigments, cadmium sulfide, ram, etc.
Or, silicon, germanium, etc. formed by CVD method, or as another example, phthalocyanine pigment.

A charge generation layer is formed by coating a charge generation substance such as a dibenzpyrenequinone pigment or an azo pigment together with a binder resin if necessary, and a charge transport substance such as a hydrazone compound, a pyrazoline compound, a stilbene compound, an oxazole compound, or a thiazole compound. Examples include a functionally separated photosensitive layer in which a charge transport layer is laminated by coating together with a binder resin if necessary.

The present invention is advantageous in that the photosensitive layer formed by coating can be manufactured in the same process as the intermediate layer.

A barrier layer having barrier and adhesive functions can also be provided between the intermediate layer and the photosensitive layer. The barrier layer is casein and polyvinyl alcohol.

Nitrocellulose, polyamide, polyurethane.

It can be formed from gelatin, etc.

The thickness of the barrier layer is 0.1 to 5 μm, preferably 0.1 to 5 μm.
A suitable thickness is 5 to 3 μm.

Example 1 As a metal support, AI! Alloy (AIl-Mn system, J
IS designation number 3003) with an outer diameter of 80 mm and a wall thickness of 0.9 mm.

A cylindrical piece with a length of 350 mm was prepared.

The surface is mirror-finished.

Next, a coating for the intermediate layer was prepared as follows.

10 parts (by weight, the same applies hereinafter) of titanium oxide powder (manufactured by Titan Kogyo Co., Ltd.) whose surface is coated with conductive tin oxide and 10 parts of titanium oxide powder (manufactured by Sakai Kagaku) were mixed with a phenol resin (trade name: Niblyophen J325). ; Manufactured by Dainippon Ink ■) 17
3 parts of methanol and 10 parts of 2-methoxyethanol, and then dispersed in a sand mill.

Apply this paint by dipping from the top to the bottom of the base,
A coating film of 20 μm was formed by heat curing for 30 minutes.

This intermediate layer coating film and the support AI! When the hardness of the alloy was measured using the Rockwell hardness test method, Af was M2S,
The intermediate layer coating was M130.

The photosensitive layer was formed as follows.

Copolymerized nylon (product name CM-8000, manufactured by Toshi ■) 5
A solution of 50 parts of methanol and 50 parts of n-butanol was applied onto the intermediate layer by dip coating to form a barrier layer having a thickness of 0.6 μm.

Next, 10 parts of a disazo pigment with the following structural formula were added, 6 parts of cellulose acetate butyrate resin (product name: CAB-381; manufactured by Eastman Chemical), and 60 parts of cyclohexanone.
The mixture was dispersed in a sand mill for 20 hours. 100 parts of methyl ethyl ketone was added to this dispersion, which was applied onto the barrier layer by dip coating, and dried by heating at 100° C. for 10 minutes.
A charge generation layer was formed with a coating weight of 1 g/d.

Next, 10 parts of a hydrazone compound having the following structural formula and a styrene-methyl methacrylate copolymer resin (trade name: M
10 parts of S200 (manufactured by Nippon Steel Chemical Co., Ltd.) were dissolved in 60 parts of monochlorobenzene to prepare a coating solution, which was dip-coated onto the charge generation layer, left to stand for 10 minutes, and dried by heating at 100°C for 1 hour to form a coating solution with a thickness of 18 μm. A charge transport layer was formed.

The barrier layer, charge generation layer, and charge transport layer were not coated up to a distance of 12 mm from the upper and lower ends of the support, respectively, so that the intermediate layer was exposed.

For comparison, a photoreceptor was prepared in the same manner as in the above example except that no intermediate layer was provided.

These photosensitive drums are used in a plain paper copier (Canon NP).
-3225) for evaluation. In this copying machine, in the developing process, the roller 1 is
The photosensitive layer 11 and the toner supply body 7 are held at a gap of 300 μm via the intermediate layer 17 and the photosensitive layer 17, and jumping development is performed. .

The hardness of this roller material is M2S in terms of Rockwell hardness.
Met.

Under these conditions, A4 size transfer paper aooo.

When we examined how the image condition changed by passing a sheet through and producing one image, we found that the photoreceptor drum of the example had 3 images.
Even after passing 0,000 sheets, high-quality images that were no different from the initial images were obtained. Furthermore, when the photosensitive drum was observed, there was almost no collapse of the intermediate layer film at the portion that hit the rollers.

On the other hand, with the comparative photoreceptor without an intermediate layer, image fogging and lack of sharpness and resolution began to become noticeable around 15,000 sheets, and as the number of sheets increased, this tendency gradually became more noticeable, and the density difference at the front nine of the back of the image also increased. Appeared. In addition, when observing the photosensitive drum after the end of durability, the part of the support An that hits the rollers is shaved off, and the depth is 50mm on the back side.
It was 70 μm at 1 μm on the near side. This is thought to be the cause of fogging and unevenness in the front.

In addition to the above examples, an intermediate layer made of a combination of pigment and cured resin as shown in the table was provided, and photosensitive drums were similarly created and evaluated. Image obtained.

3 Carbon fiber Epoxy resin 1
35〃4 Conductive ZnO phenolic resin 12
5 [Effects of the Invention] According to the present invention, even if the positioning member provided on the toner supply body, the cleaning member, or the charger member is brought into contact with the photosensitive drum having the metal support, the positioning member does not hit. Scratches and scrapes on parts.

There is no occurrence of image unevenness or staining due to dents, etc., and the durability of the drum is significantly improved.

[Brief explanation of drawings]

1 to 3 are diagrams showing the arrangement relationship between a photosensitive drum and a positioning member, and FIG. 4 is a side sectional view illustrating an electrophotographic apparatus.

Claims (3)

[Claims] (1) In an electrophotographic apparatus including an electrophotographic photoreceptor having a photosensitive layer on a metal support via an intermediate layer and a positioning member disposed at an end of the photoreceptor, the hardness of the intermediate layer is An electrophotographic apparatus characterized in that the positioning member is larger than the support and is disposed in direct contact with an exposed portion of the intermediate layer at an end of the photoreceptor. (2) The electrophotographic apparatus according to claim 1, wherein the intermediate layer is formed mainly of a curable resin. (3) Claim 1 in which the intermediate layer contains a pigment
The electrophotographic device described in Section 1.