JPS6239406Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an electrophotographic copying apparatus, and more particularly to a copying apparatus incorporating a member for forming fine irregularities on the surface of an electrophotographic photoreceptor.

The conventionally used electrophotographic copying machines are
Typically, as shown in FIG. 1, a static elimination charger 2, a main charger 3, an optical system 4, a developing section 5, a transfer charger 6, a separation charger 7, a cleaning blade 8, are provided around the photoreceptor 1. A fur brush 9 is provided. To obtain a copy using such an apparatus, first, the surface of the photoreceptor 1 is charged by the main charger 3, and an electrostatic latent image is formed by irradiating a light image (image exposure) with the optical system 4. , a visible image is created by developing with the toner from the developing section 5, and then this toner image is transferred to an image receiving paper (plain paper, etc.) 10 by the action of a transfer charger 6 and a separation charger 7, and is further heat-fused. This is accomplished by employing fixing means such as pressure fixing. In addition, in FIG. 1, the conveyance roller for moving the image receiving paper 10 is omitted.

After the transfer step, the photoreceptor is cleaned (by using the cleaning blade 8 and fur brush 9), neutralized (by the use of the neutralizing charger 2), and subjected to a copying operation starting from the charging step again.

By the way, in order to improve cleaning performance in such copying operations, fine powder of solid lubricant (low surface energy substances such as Teflon, polyethylene, polypropylene, zinc stearate, etc.) is often added to the developer or a fur brush. A means for adding or supplying the photoreceptor to the surface of the photoreceptor via the photoreceptor 9 is employed. This method has been adopted because it is known that when coated on the surface of the photoreceptor, it reduces frictional resistance, has a cleaning effect, and prevents scratches on the surface of the photoreceptor. be.

However, if this fine powder solid lubricant, which is a substance with low surface energy, becomes attached or excessively attached to the surface of the photoreceptor, it may prevent the toner from sitting on the electrostatic latent image when the toner is developed. As a result, especially when excessive low surface energy substances adhere to the surface of the photoreceptor, undesirable conditions such as white streak-like disturbances occur in the image. Therefore, in order to obtain high-quality copied images, care must be taken to prevent at least an excessive amount of low surface energy substances from remaining on the surface of the electrophotographic photoreceptor. The solid lubricants (low surface energy substances) as described above include (i) amorphous selenium or selenium-based (Se-Te, Se-As, Se-
(ii) organic photoconductive materials, although they do not cause such crystallization, It has been recognized that the life of the photoreceptor is shortened.

In view of this situation, the inventors of the present invention have repeatedly researched and considered an electrophotographic copying device that can produce a large number of high-quality copies and have a long photoreceptor life.
It has been found that the above-mentioned disadvantages do not occur if fine irregularities are formed on the surface of the photoreceptor under specific conditions. This idea was completed based on this knowledge.

The object of this invention is to provide an electrophotographic copying apparatus that can produce a large number of good copies by mechanically providing fine irregularities on the surface of a photoreceptor. Other purposes of this invention, although incidental, are to remove low surface energy substances (solid lubricants) attached or excessively attached to the surface of the photoreceptor;
Alternatively, it is an object of the present invention to provide an electrophotographic copying apparatus that can produce a large number of high-quality copies by preventing excessive adhesion of the substance.

That is, the electrophotographic copying apparatus of this invention is characterized by having a built-in metal roller whose surface is provided with minute irregularities so as to be arbitrarily pressed against the surface of the photoreceptor.

However, in the case of zinc oxide photoreceptors, the particle size distribution of the zinc oxide used therein has been selected to form fine irregularities on the surface of the photoreceptor, and the roughness of the surface protective layer has been set to 0.1 to 10S ( Attempts have also been made to modify the surface of the photoreceptor (Japanese Patent Publication No. 55-6217, Japanese Patent Application Laid-Open No. 53-92133, etc.), but these attempts are not intended to improve transfer separability and edge effects. Moreover, the photoreceptors using these methods are only inorganic photoreceptors, and there are problems such as image disturbance during development, as intended by the present inventors.
Of course, no consideration is given to extending the life of the photoreceptor.

Hereinafter, this invented device will be explained in more detail with reference to the accompanying drawings (FIGS. 2 to 5). As can be easily understood from a comparison between FIG. 2, which shows the main parts of the device according to this invention, and FIG. 1, which shows the main parts of a conventional copying device, in this device, the , a metal roller 11 with fine irregularities on its surface contacts (in other words,
(being forced) metal roller 1
1 is disposed within the copying machine.

The diameter of the metal roller 11 varies depending on the amount of internal space available in a particular copying device, and is determined as appropriate, but the length must be equal to or approximately equal to the length of the photoreceptor 1. Further, various shapes of the unevenness formed on the surface of the metal roller 11 can be considered, for example, as shown in FIG. 3.

FIG. 3 1 shows a roller with numerous minute rectangular projections 111 formed on the surface of the roller, and the length l, width w ₁ and height h ₁ of these rectangular projections 111 are shown in FIG. As can be seen in Figure 1, it is appropriate that l = about 1 to 5 mm, w ₁ = about 5 to 15 μm, and h ₁ = about 0.2 to 2 μm, respectively.

FIG. 3 2 shows a roller with numerous minute cylindrical protrusions 112 formed on the surface of the roller.
The height of the protrusion 112 _h2 is approximately 0.1 to 0.5 mm.
and warp r are about h ₂ = 0.2 to 2 μm, r =
Approximately 5 to 10 μm is appropriate.

3. In FIG. 3, countless thin continuous protrusions 113 are formed in a lattice pattern on the roller surface, and here, the length of the interval between the protrusions 113 and adjacent protrusions in the same direction is 0.1 to 0.5 mm. The height h ₃ and width w ₃ of the protrusion 113 are h ₃ =0.2 to 2, respectively.
μm, w ₃ =about 5 to 15 μm is appropriate.

As can be understood from the description of these three examples, the height of the unevenness formed on the surface of the photoreceptor 1 is at most 2.
It is about μm. By pressing these metal rollers 11 against the surface of the photoreceptor 1, countless fine line-like or dot-like irregularities are formed on the surface of the photoreceptor.

In the explanation so far, unevenness is formed on the surface of the drum-shaped photoreceptor 1, but when the photoreceptor is belt-shaped (sheet-like photoreceptor), as shown in FIG. made roller 11 and rubber roller 12
The photoreceptor 1 may be made into a pair and passed between the two rollers 11 and 12 so that the surface of the photoreceptor layer is in contact with the metal roller 11 to form irregularities on the surface of the photoreceptor 1. The photoreceptor in this device may be either inorganic or organic.

Further, the circumferential speed of the drum-shaped photoreceptor 1 and the circumferential speed of the metal roller 11 (or the moving speed of the belt-shaped photoreceptor and the circumferential speed of the metal roller 11) may be made equal; It is advantageous to shift them. By doing so, fine line-like or dot-like unevenness with a smaller area is formed on the surface of the photoreceptor. Further, the low surface energy material gradually deposited on the surface of the photoreceptor (a significant amount of this low surface energy material is transferred to the receiving paper 10) is transferred to a metal roller 11. Therefore, there is an advantage that the harmful effects of low surface energy substances as described above are eliminated.

Metal roller 1 pressed against the surface of the photoreceptor
The pressure in step 1 cannot be determined unconditionally depending on the surface material, thickness, etc. of the photoconductive layer (photosensitive layer) constituting the photoreceptor, but it must at least destroy the photoconductive layer or cause it to peel off. It must not drip or expose the support or intermediate layer (layer provided between the conductive support and the photoconductive layer) in the photoreceptor.

In this devised device, the metal roller 11 having an uneven surface is pressed against the surface of the photoreceptor 1, and the metal roller 11 is incorporated into the device. It does not necessarily mean that the rollers 11 must be in contact with each other. It is desirable that this contact be made intermittently or as needed.

Attempts have already been made and proposed by the present inventors to achieve the object of this invention by forming numerous fine line-like or dot-like irregularities of minute area on the surface of the photoreceptor (in particular, (Gan Sho 55-48910).
However, at that stage, the unevenness is formed on the surface of the photoreceptor outside the device, so the unevenness is only created once, and the lifespan of the photoreceptor is determined by how it is formed. (For example, if the unevenness is shallow, the life of the photoreceptor tends to be short.) It is also conceivable to provide an abrasive brush (for example, a metal wire brush made of tungsten, molybdenum, nickel, stainless steel, etc., a fiber brush made of carbon fiber, nylon, etc.) in place of the metal roller 11 according to this invention. In such a case, it would be difficult to adjust the life of the brush and the degree of unevenness formed on the surface of the photoreceptor, and it is fully expected that polishing scum would adhere to the inside of the apparatus.

By using the above-mentioned specific metal roller 11,
On the surface of the photoreceptor, countless irregularities in the form of "fine lines or dots of minute area" are formed, and the shape of the irregularities is preferably in the form of fine lines. When the unevenness is in the form of a thin line, the directionality of the unevenness may be random, but it may be in the same direction, perpendicular to the rotational direction of the photoreceptor drum, or in an oblique direction in between, preferably in the perpendicular direction. It is. Even when the irregularities are not linear but dotted, they may be oriented with a certain regularity as described above, or they may be oriented in random directions.

Normally, the unevenness is measured using a Sloan surface roughness meter, and is expressed as the average value of the unevenness pattern measured using a 25 μm head on the measuring part. The degree of unevenness formed by this device is determined by the surface shape of the metal roller 11, the pressure, the photoconductive layer (inorganic photoconductive layer, organic photoconductive layer), the circumferential speed of the photoreceptor, and the circumference of the metal roller. Depth 0.2 to 4 μm, pitch 4 to 9 mm, although it naturally depends on speed differences and other factors.
Preferably, 0.1 to 0.5 mm is appropriate. When the pitch of the unevenness exceeds 9 μm, the unevenness appears on the image and causes background smudge. Note that this value of 9 μm is almost the same as the average particle size of toner particles in commonly used developers, and therefore, it depends on the type of toner used (difference in toner particle size). It may also be considered to vary the pitch of the unevenness.

As described above, when the electrophotographic copying apparatus of this invention is operated, countless irregularities of minute area are formed on the surface of the photoreceptor, and low surface energy substances and other unnecessary products are deposited on the surface of the electrophotographic copying apparatus. In some cases, the toner particles are transferred to a metal roller provided with the toner particles, so that adhesion to the surface of the photoreceptor is significantly restricted, and the phenomenon of slipping of the toner particles hardly occurs.
Low surface energy substances and other unnecessary products transferred to the metal roller can be easily removed by wiping the roller surface with absorbent cotton, a soft cloth, or the like. In addition, the formation of irregularities on the photoreceptor surface increases the surface area of the photoreceptor surface, which reduces the amount of low surface energy substances deposited per unit surface area of the photoreceptor during unit copying operation time. It is connected to what it brings.

Furthermore, in this device, a member (metal roller 11) that makes the surface of the photoconductor uneven is built into the copying device, and can be used constantly or as needed (for example, to prevent excessive adhesion of low surface energy substances to the surface of the photoconductor). It is possible to form unevenness on the surface of the photoreceptor (just before the photoreceptor is used, etc.), and since this device uses a metal roller to form the unevenness on the surface of the photoreceptor, no polishing scum is produced. Therefore, the copying device does not get dirty, and in addition, the degree of unevenness formed on the surface of the photoreceptor can be easily adjusted using the metal roller.

Since the electrophotographic copying device according to this invention has such many advantages, by using this device, not only can a large number of high-quality copies be obtained, but also the life of the photoreceptor can be greatly extended. It becomes like this.

Next, examples will be shown.

Example 1 On Al-deposited polyester film (conductive support) A charge carrier generating layer with a thickness of about 0.2 μm is formed by applying and drying a solution of 3 parts by weight of the pigment (charge carrier generating substance) represented by and 1 part by weight of polyvinyl butyral (binder resin) dispersed or dissolved in a solvent. and on top of this 1 part by weight of a pigment (charge carrier transfer substance) represented by 1 part by weight of a polycarbonate resin dispersed or dissolved in tetrahydrofuran is coated and dried to form a charge transfer layer approximately 20 μm thick. Created a photographic photoreceptor.

This photoreceptor was transferred to a dry two-component type electrophotographic copying machine (a developer using a Teflon coated carrier and a Tetron fur brush is used) as shown in Fig. 3.
It was assembled with the metal roller shown in Figure 2 to create a device with the structure shown in Figure 2. continue,
Continuous image formation is performed by a normal copying process while keeping the metal roller 11 in contact with the photoreceptor 1 from beginning to end. I checked the degree of image distortion. The results were as shown by curve a in Figure 5, and more than 20,000 high-quality copies with no black lines or other problems were obtained. This tendency was the same even when the metal roller 11 shown in FIGS. 2 and 3 was used.

For comparison, when we performed continuous image formation in the same way as above without installing the metal roller, the result was as shown by curve b in Figure 5, and vertical white streaks appeared in the black part of the image from around the 8000th copy. Phenomena such as the appearance of thin lines or breakage of thin lines were observed.

The vertical axis in Figure 5 represents the degree of ear marks (development where vertical white lines appear in the black part of the image or thin lines break), and the smaller the value, the stronger the tendency. There is.

Example 2 A copying device as shown in FIG. 2 was made in the same manner as in Example 1, except that the photoconductive layer was replaced with an approximately 60 μm thick Se-Te alloy layer (Te content: 10% by weight). Continuous image formation was performed. The results were almost the same as in Example 1.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional electrophotographic copying apparatus, FIG. 2 is a schematic diagram of an electrophotographic apparatus according to the present invention, and FIG.
The figure shows three examples of metal rollers, Figure 4 is a schematic diagram of a pair of devices consisting of a metal roller and a rubber roller used to provide unevenness on the surface of a belt-shaped photoreceptor, and Figure 5 is a continuous 3 is a graph showing measurement results of an image formation test. 1... Photoreceptor, 2... Static elimination charger, 3...
...Main charger, 4...Optical system, 5...Developing section, 6...Transfer charger, 7...Separation charger, 8...Cleaning blade, 9...
Fur brush, 10...image receiving paper, 11...metal roller, 12...rubber roller.

Claims (1)

[Scope of utility model registration request] An electrophotographic copying device that includes a built-in metal roller that has fine irregularities on its surface so that it can be arbitrarily pressed against the surface of a photoreceptor.