JPH0635211A - Production of drum for color image forming device - Google Patents

Abstract

PURPOSE:To provide the process for production of drums which are uniformalized in respective characteristics by handling plural pieces of the drums to be used for a color image forming device as one unit. CONSTITUTION:All the layers with which the drum surfaces are coated are formed by simultaneously dipping plural pieces of the drums 11 into a coating material, then drying the coatings, by which the drums consisting of plural pieces of the drums 11 to be used for the color image forming device as one unit are produced. The base bodies of the drums 11 to be dip coated are preferably subjected to surface roughening by simultaneously subjecting plural pieces of the base bodies to a honing treatment. The coating layers of the drums 11 are exemplified by the coating layers successively laminated with, for example, an under coating layer, charge generating layer and charge transfer layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a drum having a plurality of drums used in a color image forming apparatus as one unit and having uniform characteristics.

[0002]

2. Description of the Related Art In a color image forming apparatus such as a copying machine or a printer, cyan, magenta and yellow color toners and black toner are developed on a drum to form an image. At the time of development, there are a method of developing all the respective colors on the drum and a method of transferring the toner image to the transfer drum for each color. In these methods, only one drum is used. On the other hand, each color is equipped with a drum and a developing device to form an image,
There is also a color image forming apparatus in which a toner image is transferred and superposed on a transfer paper or a transfer belt, and the color image forming apparatus called a tandem type shown in FIG. 1 adopts the same formula. In FIG. 1, four drums 1 are mounted for each color a, b, c, d. Image exposure is performed on the drum by the laser optical unit 2 and development is performed by the developing device 3. The toner images are transferred onto the transfer belt 4, and the toner images of respective colors are sequentially superposed on the belt 4 to form a color image. 5 is a cleaner for wiping off the residual toner, 6 is a charger for charging the drum 1, and 7 is a transfer charger for attaching the toner onto the belt 4. As described above, in the above color image forming apparatus having four drums, it is important that the characteristics of the four drums are uniform. This is because if the characteristics are not uniform, a slight deviation occurs in the toner density of each color, and an accurate color image cannot be formed. Although the initial characteristics of the drum can be adjusted for the time being, it is very difficult to match the fluctuation due to the environment and the fluctuation due to repeated use. Therefore, in order to adjust the development density as much as possible, the development density is constantly adjusted by using the potential sensor 8 for detecting the electrical characteristics of the drum and the drum reflectance sensor 9 for detecting the density of the toner image on the drum shown in FIG. Process control is performed. However, since it is difficult to compensate for a slight deviation, basically the characteristics of the drum must be uniform.

By the way, as a recent method of manufacturing a drum, an organic photosensitive layer or the like is often formed on a substrate by a dip coating method. When a drum is manufactured by a dip coating method, as described in JP-A-59-90667, the paint is circulated in order to maintain the uniformity of the paint, or described in JP-A-58-177175. As described above, in order to diffuse the liquid in the coating tank, a discharge plate is provided at the discharge port, or as described in JP-A-2-131241, in order to keep the viscosity of the coating constant. A method has been proposed in which the viscosity is measured at any time and a solvent is added. However, it is possible to keep the thickness of the coating film uniform, but it is not possible to compensate for the change with time of the paint itself. It was not possible to match even long-term characteristic fluctuations. Therefore, in order to maintain the developing density, as shown in FIG. 1, a sensor and a control device are required for each drum, and a complicated control circuit is required. In the conventional manufacturing of drums, one drum is usually dipped in one coating tank to apply a photosensitive layer and the like, and in a mass production method, a plurality of drums may be simultaneously dipped and applied. The drums were separated into pieces.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art. That is, an object of the present invention is to use a plurality of drums to be used in a color image forming apparatus as one unit to manufacture a drum having uniform characteristics with a simple method.

[0005]

As a result of intensive studies on the drum used in the color image forming apparatus, the present inventor has found that the variation of the color image is caused by the variation of the characteristics at the time of producing the drum. The present invention has been completed by finding that there is no variation in the color image formed by using the produced drums by simultaneously coating a plurality of drums used as one unit in parallel. Came to. That is, according to the present invention, in a method of manufacturing a plurality of drums used in a color image forming apparatus as one unit, for all layers coated on the surface of the drum, the plurality of drums are simultaneously dipped and applied in a paint. Then, the method for producing a drum for a color image forming apparatus is described.

The present invention will be described in detail below. As described above, the present invention is to dry a plurality of drums simultaneously applied by dip coating, and use the produced plurality of drums as one unit in a color image forming apparatus. So first,
The dip coating method of the present invention will be described based on the dip coating apparatus shown in FIG. The four drums 11 are lowered in synchronization with an elevating device (not shown), and the coating tank 1
Each drum 1 when immersed in the paint in 2 and then pulled up
Paint is applied to 1. Paint is supplied from supply pipe 13 to coating tank 1
2 is supplied to the coating tank 12, overflows from the upper end of the coating tank 12 into the tray 14, and is discharged from the discharge pipe 15. It is preferable to circulate the paint by a circulation device, and as mentioned above, an apparatus for maintaining the viscosity of the paint constant is attached to the dip coating device.

In the dip coating apparatus shown in FIG. 2, although four drums 11 are simultaneously dip coated, the drum 1
The number of one and the number of coating tanks 12 may be matched to the number of drums incorporated in the color image forming apparatus used. For example, in a color image forming apparatus that develops cyan and black toners on a drum to form a two-color image, at least two multiples of the drum 11 are dip-coated. In the case of the dip coating device capable of applying the required number of drums or more, only the required number of drums may be applied as one or a plurality of units after production.

The present invention further produces a drum for a color image forming apparatus by repeating the dip coating and drying operations once or twice or more depending on the number of layers coated on the drum surface. . The layer coated on the surface of the drum may have a single-layer structure composed of only a photosensitive layer or a laminated structure. When the coating layer has a laminated structure, in addition to the two layers of the charge generation layer and the charge transport layer,
The drum is coated with three or more layers in which these layers are appropriately combined with an undercoat layer, an intermediate layer, a surface layer, and the like. As a drum for a color image forming apparatus, a drum in which an undercoat layer, a charge generation layer and a charge transport layer are sequentially laminated is used. A known material composition is selected for the coating material forming the above layer according to the function of the layer. For example, the coating material forming the photosensitive layer contains a charge generating material, a charge transporting material, a binder resin and a solvent. To do. It is desirable that the drum, which has been subjected to the dip coating as described above, be placed in a dryer at the same time for each layer to remove the solvent. In some cases, the characteristics of the drum may be deviated unless the drying step is performed at the same time.

On the other hand, when a color image is formed by exposure with a laser beam, when a coherent laser beam is applied to the drum, multiple reflection may occur in each layer and an interference fringe may occur in the image. As one of means for preventing this, as described in Japanese Patent Laid-Open No. 3-64762, the surface of the substrate of the drum is subjected to honing treatment with a specific roughness to roughen the surface and scatter reflected light. There is a way. Also when performing such honing, it is preferable to simultaneously treat a plurality of substrates. As an example of honing, as shown in FIG. 3, while rotating the substrate 21 of the drum on the turntable 22, the water containing the abrasive is compressed by compressed air by the gun 25 connected to the abrasive hose 23 and the air hose 24. There is a process of spraying 21. The abrasive dispersion is circulated and used, but it is a common method to replace the substrate 21 of the drum every time a predetermined number of the substrates 21 are processed. When the drum bases 21 are subjected to a honing process in excess of a predetermined number, the roughness of each base 21 gradually changes due to deterioration of the polishing agent, mixing of impurities, and the like. Preferably.

[0010]

Example An aluminum pipe having a thickness of 1 mm × 84 mmφ × 340 mm was prepared. The maximum roughness of the surface is 0.5
μm, the average interval of the irregularities is 200 μm. This aluminum pipe was processed by the four-cavity honing device shown in FIG. 3 under the following conditions. Honing conditions Abrasive: Alundum # 400 (Showa Denko) Suspension medium: Water Abrasive / suspension medium: 1/4 (weight ratio) Rotation speed of aluminum pipe: 100 rpm Spraying pressure: 2 kg / cm ² Gun movement Speed: 500 mm / min Abrasive-suspension medium exchange: After 10,000 treatments

Next, a type 8 nylon resin (trade name: laccamide, Dainippon Dainippon), in which the honing-treated aluminum pipe (drum 11) was supplied into the coating tank 12 by the four-take dipping coating device shown in FIG. It was applied by dipping in a methanol-butanol mixed solution (paint) manufactured by Ink Co., Ltd. Then, it was naturally dried for 5 minutes, the drum was placed on a pallet capable of placing four simultaneously, and four drums were simultaneously placed in a dryer and dried at 140 ° C. for 10 minutes. Thus, an undercoat layer having a thickness of 1.0 μm was formed. On the other hand, after dissolving 3 parts of polyvinyl butyral resin (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) in 100 parts of cyclohexanone,
The mixture was mixed with 6 parts of X-type metal-free phthalocyanine and dispersed for 6 hours by a sand mill disperser using 1 mmφ glass beads as a dispersion medium. 2. Add 2-butanone to the dispersion.
A 5% concentration charge generation layer coating material was prepared. This coating material was also applied onto the undercoat layer by the four-dip dipping coating device shown in FIG. 2, and the four coating materials were simultaneously placed in a dryer at 100 ° C. and dried for 10 minutes to form a charge generation layer having a thickness of 0.25 μm. . Further, 4 parts of N, N'-diphenyl-N, N'-di (m-tolyl) benzidine was used as a charge transport material and dissolved in 36 parts of chlorobenzene together with 6 parts of polycarbonate Z resin. The obtained paint is applied onto the charge generation layer by the four-coat dipping coating device shown in FIG.
And dried for 1 hour to form a charge transport layer having a film thickness of 20 μm.

With respect to the drum thus produced,
The relationship between the number of honing treatments and the surface roughness is shown in Table 1 below.

[Table 1] As shown in Table 1, since the surface roughness changes little by little as the number of treatments increases, it is the best method to apply the honing treatment at the same time to apply the four treatments without variation.

Regarding the electric characteristics of the drum, not to mention the film thickness of each layer,
The freshness of the paint, the mixing of impurities in the paint, the dispersion state of the pigment, the temperature and humidity at the time of application, the temperature and humidity in the dryer, the concentration of solvent vapor in the dryer, the outside air taken into the application chamber and / or the dryer. It is also affected by temperature and humidity. Therefore, the electrical characteristics of the drum manufactured for each time zone of the day were measured. The results are shown in Table 2 below.

[Table 2]

As shown in Table 2, the sensitivity of the drum manufactured at 1 PM to 4 PM was low (that is, the exposure potential was high), and that of the drum manufactured at 6 PM to 9 PM was also low. On the other hand, from 9 am to 12 pm and 9 pm from PM
The drum produced at 12:00 had higher sensitivity and stable cycle characteristics. This result shows fluctuations within one day, but fluctuations on different days such as seasons may be added. Therefore, in order to make the characteristics of the drums uniform, a plurality of drums are simultaneously manufactured for each unit. There is a need.

[0015]

EFFECTS OF THE INVENTION Since the drum of the present invention is produced by simultaneously dip-coating all the layers coated on the surface of the drum and then drying, the characteristics of each drum are well matched. Therefore, even if these drums are incorporated into a color image forming apparatus as one unit, it is possible to always appropriately control the density of each color, and it is possible to form a good color image.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a conventional color image forming apparatus.

FIG. 2 shows a method for simultaneously dipping multiple drums,
It is a schematic diagram of a dip coating device used in the present invention.

FIG. 3 For simultaneously treating multiple drum substrates,
It is a schematic diagram of a honing processing device used in the present invention.

[Explanation of symbols]

1 ... drum, 2 ... laser optical unit, 3 ...
..Developing device, 4 ... Transfer belt, 5 ... Cleaner, 6 ... Charging device, 7 ... Transfer charging device, 8 ... Potential sensor, 9 ... Drum reflectance sensor, 11・ ・
・ Drum, 12 ... Coating tank, 13 ... Supply pipe, 14
... saucer, 15 ... discharge pipe, 21 ... drum base, 22 ... turntable, 23 ... abrasive hose, 24
... air hose, 25 ... gun.

Claims (2)

[Claims] 1. A method for producing a plurality of drums used in a color image forming apparatus as a unit, wherein all the layers coated on the surface of the drum are simultaneously dipped and coated in the paint. A method for producing a drum for a color image forming apparatus, which comprises drying. 2. The method for producing a drum for a color image forming apparatus according to claim 1, wherein a plurality of bases of the drum are simultaneously roughened by honing.