JP3120117B2 - Photoconductor image quality improvement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the image quality of an organic or amorphous silicon photosensitive member in an image forming apparatus such as an electrophotographic copying machine, a laser printer, and a facsimile.

[0002]

2. Description of the Related Art Photoreceptors in conventional image forming apparatuses such as electrophotographic copying machines include organic and amorphous silicon-based photoreceptors.
From the viewpoint of productivity and cost, other amorphous silicon photoconductors
(Se photoconductor, a-Si photoconductor, etc.) are widely used.

However, since the organic photoreceptor uses a resin having a surface hardness of about ²⁰ to 50 kg / mm ² , the friction resistance is low and abrasion occurs at 1 to 5 μm / 10,000 sheets. For this reason, various countermeasures are used to increase the mechanical durability of the organic photoreceptor, and one example is to use an amorphous carbon film as a protective layer.

[0004] The amorphous carbon film is obtained from a hydrocarbon gas such as methane, ethane, propane, butane, ethylene, butadiene or the like, and if necessary, hydrogen, oxygen, nitrogen, fluorine or the like. Plasma CVD, light C
A uniform thin film is formed on the photoconductor by a manufacturing method such as a VD method or a sputtering method.

Further, since the organic photoreceptor has a glass transition temperature of about 100 ° C., the substrate temperature at the time of forming the amorphous carbon film needs to be about room temperature in consideration of the temperature rise. There is. For this reason, a-Si (amorphous-silicon) photoconductor (1500 to 2000
kg / mm ² ), but the surface hardness is lower,
From mm ² , it can be manufactured up to about 2000 kg / mm ² .

However, those having a high surface hardness have a low light transmittance, and a semiconductor laser (780) for a light source of a digital copying machine is used.
(nm) light may be insufficient. Usually 500
A material having a hardness of 〜1500 kg / mm ² is used, but the mechanical durability of about 200,000 to 300,000 sheets is sufficiently provided.

On the other hand, in an image forming apparatus using an electrophotographic system, a charging charger 10, a transfer charger 11, and a separation charger are provided around a photoreceptor 1 as illustrated in FIG.
A corona discharger is used for 12 etc.

In addition to the above, 13 is a charge removing lamp, 14 is a developing device, 15 is a fixing device, 16 is a light source (semiconductor laser) for image exposure, and 17 is a paper feeding device. The other heater 2, the cleaning device 18, and the cleaning jig 19 are members related to the present invention, and their functions will be described later in detail.

[0009] These corona dischargers produce corona products such as ozone O ₃ and nitrogen oxides NO _x during operation. These corona products are oxidized on the surface of the photoreceptor because discharge energy and gas and moisture in the air act on the photoreceptor to convert them into hydrophilic compounds such as nitrogen compounds, aldehyde groups and carboxyl groups. In addition, the surface resistance of the photoreceptor is reduced due to the attachment of a compound and the absorption of moisture by atmospheric moisture, thereby causing image deletion.

The phenomenon of image deletion has a greater effect on corona discharge when an AC or minus DC voltage is applied to the corona discharger, resulting in a greater influence. By the way, there are two types of the image flow, one of which is a phenomenon in which the corona product attached to the corona discharger accumulates on the photoreceptor while the image forming apparatus is stopped, and the image is lost in a belt shape. In this case, the humidity is generated from about 30 to 40%.

On the other hand, when the photoreceptor is used for a long time, the corona product remaining without being removed by the toner cleaning device 5 (see FIG. 4) absorbs moisture in the atmosphere. Occur.

[0012] These image bleeding phenomena occur in almost all photoreceptors. In particular, the surface hardness of the photoreceptor is large.
A hydrophilic oxide is easily formed by ozone or the like, and is easily formed on the protective layer 1-3 of the photosensitive layer formed on the conductive support 1-1 of the photosensitive member 1 shown in FIG. This is presumed to be because the surface hardness of the photoreceptor is large and the formed low-resistance layer is hard to be polished.

[0013]

As described above, the phenomenon of image deletion tends to occur on a friction-resistant photosensitive member having a large surface hardness. However, the organic photoreceptor has almost no problem because it is easily worn, but the same problem occurs when a resin having high hardness is used.

That is, an amorphous carbon film having high hardness is formed on the protective layer.
When the overcoat is performed as (1-3 in FIG. 2), in an environment of a temperature of 20 to 25 ° C. and a humidity of 40 to 60% RH, 500 to 1000
When a sheet is copied, or when the sheet is left for about 5 to 10 hours, image deletion occurs, and the image deletion tends to be more remarkable on the facing surface of the corona discharger.

As means for improving the image deletion, many proposals have been made to heat the photoreceptor from the outside or inside to evaporate the absorbed moisture and use it.

The temperature required to improve (eliminate) the image deletion is usually 35 to 45 ° C. on the surface of the photoreceptor, but an amorphous carbon film having high wear resistance is used as the protective layer 1-3. In the photoreceptor, the toner cleaning device 5 and the developing device 14 shown in FIG. 4 do not remove most of the attached corona product. The corona product is accumulated so that it cannot be eliminated in a short time, and it is necessary to raise the temperature temporarily in order to eliminate the image flow in that portion in a short time.

As described above, a photoreceptor having high abrasion resistance is liable to cause an image flow, and a countermeasure such as heating of the photoreceptor is necessarily required. In addition, if the device is continuously operated at a temperature that can be eliminated in a short time, the image density may be reduced, fine images may be lost, or the temperature may be increased due to softening of toner, change in characteristics, change in characteristics of the photoconductor, or the like. There is also danger.

An organic photoreceptor, particularly an amorphous silicon photoreceptor (a-Si photoreceptor) reacts with silicon Si and oxygen O to form hydrophilic silicon dioxide SiO _2, and generates corona. Since an object also adheres to the image, the image is liable to flow, and there is almost no cleaning effect on the corona product.

Since this image deletion is generated by absorbing moisture in the atmosphere, a heating and drying method for the photosensitive member has been proposed as described above. However, initially the temperature is 35-40
℃ was effective, but as the number of uses increased, the temperature decreased to 50 ° C.
Unless the temperature is increased to about 60 ° C., there is a problem that a sufficient effect cannot be obtained.

Another problem is that the sharpness of the image is reduced due to corona products accumulated on the photoreceptor.

It is an object of the present invention to provide an image quality improving method for preventing image deletion on a photosensitive member according to such a situation.

Accordingly, an object of the present invention is to provide a uniform image which is always uniform without losing even a minute image like a dot pattern, and to prevent the occurrence of image deletion even under high humidity or a sudden change in humidity. Is to do.

[0023]

According to the present invention, there is provided a method for improving image quality of a photoreceptor, comprising: a photoreceptor having a protective layer made of an amorphous carbon film; a heating source built in the vicinity of the surface of the photoreceptor;
An image forming apparatus comprising: a cleaning device mainly composed of activated carbon fibers and including a cleaning member that is in direct contact with a photoconductor, wherein the cleaning device and the heating source are operated in combination during copying. Features.

[0024]

According to the image quality improving method of the present invention, the control unit copies the photoconductor cleaning device having the cleaning unit mainly made of activated carbon fiber and the heating source built in the vicinity of the surface of the photoconductor. By operating the medium together, the corona product adhered to the surface of the photoreceptor is removed, and it is possible to prevent image deletion caused by the corona product.

[0025]

FIG. 1 is a block diagram showing a control system for implementing a method for improving the image quality of a photosensitive member according to the present invention. In FIG. 1, reference numeral 1 denotes a photosensitive member, which has a heater 2 built therein as a heating source in a circle near the surface thereof. The heater 2 is a planar heater whose temperature rises quickly. Although it depends on the size of the body and the thickness of the conductive support 1-1 (described later with reference to FIG. 2), generally, a heater of about 30 to 100 W may be used. Although the embodiment employs a built-in heater type in order to heat the photosensitive member quickly and uniformly, an external heater may be used because the thermal efficiency is low, though it is poor.

Reference numeral 3 denotes a temperature sensor for detecting and managing the surface temperature of the photoconductor 1, and a sensor using a thermistor, infrared rays, or the like is used. This temperature sensor is placed in contact with the photoreceptor or is set at a distance of about 1 to 5 mm. 4 is a power switch of the heater 2 and
It is also a power switch of the drive device 6 for operating the cleaning device 18. Reference numeral 7 denotes a drive unit for a drive motor 8 for the photoconductor, and 9 denotes a control unit of the control system block,
Becomes, in the photosensitive member surface temperature phase diagram shown in FIG. 3 (2), the standby state of the set temperature T ₀ of the photosensitive member 1 (A)
When the copying is possible (B), ON / OFF control of the heater is performed according to the heating timing chart shown in FIG. 3A, and the cleaning device 18 is operated together with the heater 2 during copying.

FIG. 2 is a schematic sectional view showing an example of the structure of the surface of the photosensitive member 1 used in this embodiment. As shown in the figure, an organic photosensitive layer 1-2 is formed on a conductive support 1-1, and then a protective layer 1-3 made of an amorphous carbon film (hereinafter referred to as an aC film). The conductive support 1-
A low-resistance undercoat layer 1-4 can be formed between the layer 1 and the organic photosensitive layer 1-2. Further, even if the organic photosensitive layer 1-2 is a single layer, the charge generation layer (CGL) 1-
2a and a charge transport layer (CTL) 1-2b.

Here, the protective layer 1-3 made of the aC film is used.
Is formed by a vacuum film forming method such as a plasma CVD method, a photo CVD method, and a sputtering method.
From the relation of the glass transition temperature of 2, the substrate temperature condition in the film forming apparatus must be suppressed to about room temperature. Therefore, in order to satisfy the characteristics as an electrophotographic photoreceptor, the transmittance of short-wavelength light is reduced. Therefore, the analog-type image forming apparatus using visible light is more suitable for a digital image forming apparatus using long-wave light. I have.

The protective layer (a-C film) 1-3 formed on the organic photosensitive layer 1-2 has a hardness of several tens to 2,000 kg / mm ² by changing the film forming conditions. Although it is possible to use the one of which is about 500 to 1500 kg / mm ² , it is optimal to satisfy the mechanical properties.

The aC film may be a single layer or a laminate of two or more layers as described above, but the film thickness is not particularly limited as long as it satisfies electrophotographic characteristics. However, when the film thickness is small, scratches are easily formed, and when the film thickness is too large, the residual potential rises, deteriorating image quality characteristics.
Approximately 4 to 2 μm is optimal.

Although the volume resistance and the relative dielectric constant satisfying the electrophotographic characteristics cannot be largely changed by changing the film forming conditions, the volume resistance and the relative dielectric constant for obtaining stable image quality are respectively different. 10 ⁹ to 10 ¹⁴ Ω · cm, 3 to 6 is optimal.

Although it is possible to dope an impurity element to improve the electrical characteristics and mechanical characteristics of the aC film, the effect of improving the environmental characteristics is small.

Returning to FIG. 1, the operation of the heating temperature control method will be described.

[0034] In normal image flow, the power switch 4 by the switch control signals S ₁ from the control unit 9 so as to heat to a temperature of about 35 to 45 ° C. by the heater 2 incorporated in the photosensitive member 1, FIG. 3 (1 and oN / OFF control as), if the detected managing surface temperature signal S ₂ of the photosensitive member by a temperature sensor 3, no practical problem.

However, the charger 10 shown in FIG.
The photoreceptor 1 is located in the portion of the remarkable image flow generated under the corona discharger such as the transfer charger 11 and the separation charger 12.
Can be solved by increasing the surface temperature of the. However, the glass transition temperature of the photosensitive layer 1-2 (see FIG. 2) is as low as 100 to 120 ° C., and the temperature cannot be set too high due to various factors such as thermal fatigue of the photoconductor and softening of the toner.

Therefore, in this embodiment, as shown in FIG. 3B, in the standby state (A), the temperature 50 to 60 ° C., which is higher than the normal heating set temperature T ₀ of the photosensitive member 1 by 15 to 35 ° C. Set to ° C.

That is, in order to obtain a higher quality image than the first copy, the high temperature is applied by turning on the main switch (not shown) of the image forming apparatus (point a in FIG. 3 (2)). This is because it is necessary to evaporate the moisture adsorbed on the photoreceptor surface during 1 to 5 minutes from when the copying is possible (point b in FIG. 3B). For this purpose, higher heating of the photoconductor than usual is required.
In the case of a cylinder having a thickness of 1 mm, when the temperature of the heater 2 as the heating source is 100 ° C., the surface temperature of the photosensitive member 1 is reduced by 5 to 1.5 minutes.
It is possible to reach 0 ° C.

Incidentally, the protective layer 1-3 shown in FIG.
The aC film is hard as in the case of the a-Si layer, so that the adhered corona product is difficult to be removed. However, since the a-Si layer is ozone, a hydrophilic SiO ₂ film is formed on the surface thereof, so that the humidity is low. Once the moisture is absorbed, even if the temperature is raised to about 50 ° C. or 60 ° C., the image deletion is not sufficiently eliminated. Therefore, it is necessary to always heat the photoconductor even when the image forming apparatus is stopped. However, since the aC film is hardly deteriorated by corona products, the image deletion can be eliminated by heating the photoconductor when necessary.

Next, samples for several types of photoreceptors
1, Sample-2, Comparative Example-1, and Comparative Example-2 will be described respectively.

Sample-1 An undercoat layer 1-4 of about 2 μm in which TiO ₂ (Ishihara Sangyo) is dispersed in a polyamide resin on an aluminum cylinder having a diameter of 80 mm, a length of 340 mm, and a thickness of 1 mm. 0.15μm dispersed charge generation layer (CGL) 1
-2a, about 28μ dispersed stilbene compound in polycarbonate resin (Panlite, C-1400, Teijin Chemicals)
A function-separated organic photoreceptor in which m charge transport layers (CTL) 1-2b were laminated was prepared.

The organic photoreceptor is set in a plasma CVD apparatus, the conductive support 1-1 is not heated, C ₂ H ₄ gas is used as a source gas, a reaction pressure is 0.02 Torr, and an RF power (13.56 MHz) is 100.
W, Knoop hardness approx.
/ Mm ^2, a thickness of about 1.2 [mu] m, 90-92% 780 nm for transmittance, and overcoated with a-C film having a dielectric constant from 3 to 3.2, to prepare a sample.

As an experimental machine for checking the characteristics of the photosensitive member,
A 60 W planar heater 2 was installed as a heating source of the photoconductor at a distance of about 1 mm from the inner wall of the photoconductor 1. A digital electrophotographic copying machine using a 780 nm semiconductor laser as a light source was prepared. The temperature sensor 3 for temperature control was installed so that the photosensitive member was in contact with a portion not related to an image.

The surface temperature of the photoreceptor sample reached about 60 ° C. in about 2.5 minutes after the main switch was turned on, and after 4 minutes, 42 to 4
The heating source was set to 5 ° C. And 22-25
In an environment of 60 ° C and 60% to 70% RH, 5,000 sheets / day, 20
Copying was performed every 10,000 sheets, and every 2500 sheets were evaluated for each item of surface potential, image density, resolution, sharpness, and appearance characteristics of the photoconductor in the experimental machine.

As a result, even if the copying machine was left for about 15 hours after the completion of the copying, there was no image deletion, and an image having good sharpness was obtained.
In addition, although scratches occurred in the aC film, the number of occurrences was so small that the initial gloss was maintained as a whole. Although this scratch is likely to appear in a halftone image, it was at a practically acceptable level.

As described above, the flow of the image on the surface facing the corona discharger was also suppressed, even when the number of copies was increased and the first sheet was left for about 15 hours, and the stability of the image quality was confirmed.

[0046] Sample -2 organic photosensitive member on at C ₂ H ₄ gas reaction pressure 0.01 Torr, RF
Under the conditions of a power of 150 W and a film formation rate of 140 mm / min, an aC film having a Knoop hardness of about 1100 kg / mm ² , a film thickness of about 6500 mm, a transmittance of 780 nm of 95%, and a dielectric constant of 4 to 4.5 is overcoated. A sample was prepared.

The experimental machine used was the same as that of Sample-1.
Approximately 1.5 minutes after the main switch is turned on, the temperature reaches 50-52 ° C,
The heating source was set so that the temperature became 40 to 43 ° C after 2.5 minutes.
Then, in an environment of 22 to 25 ° C. and 60 to 70% RH, 4000
100,000 copies were made at the rate of sheets / day, and the same characteristics as Sample-1 were checked every 1000 to 2000 sheets.

As a result, even when left for about 15 hours after the completion of copying, there was no image deletion and an image with good sharpness was obtained. Although the number of scratches on the aC film was higher than that of sample-1, no concentration occurred, and the gloss of the aC film was well maintained and scratch marks on the halftone image were almost conspicuous. No, it was confirmed that good quality images were maintained.

Comparative Example 1 An organic photoreceptor overcoated with the same aC film as Sample-1 was used as a sample. The surface temperature of the photoreceptor sample is 3 to 3.5 minutes after the main switch is turned on, and is 40 to 42 minutes.
The heating source was set to be ° C.

Various characteristics were checked in the same manner as in Sample-1. As a result, almost 15 hours after the completion of copying, no image deletion was observed on the image. Although the width of the corona discharger (charging charger) was narrow at the portion corresponding to the facing surface, image deletion was confirmed. This symptom continued to about 10 or more copies, and almost disappeared in 20 or more copies.

Comparative Example 2 About 2.5 μm of a-
A C film was formed. a-C film has Knoop hardness of about 1300-1700kg
/ Mm ² , the transmittance at 780 nm was 50 to 55%, and the relative dielectric constant was 2.9 to 3.0.

This was mounted on the same experimental machine as Sample-1. When the heating source is not operated, and when the temperature reaches about 60 ° C in about 2.5 minutes after the main switch is turned on, the heating source is turned off, and 30,000 copies are made by each method.
The evaluation shown in Sample-1 was performed.

As a result, in both cases, the residual potential in the experimental apparatus was increased to 380 to 400 V in the initial image, and the image density was reduced, and the reproducibility of the halftone image was also reduced.
However, the character image had good sharpness.

With respect to image deletion, when the heating source was not operated, the signs began to appear between 500 to 1000 copies, resulting in an impractical image. After leaving 4,000 sheets for 15 hours, the image flowed. However, only a few scratches occurred and there was no problem in mechanical properties.

On the other hand, when heating was performed only at the start, the number of sheets up to the image deletion was increased, but the signs began to appear even at 2,000 sheets. 15 hours after the end of 4000 sheets, the first image of the start had a heating effect, no image deletion occurred, and the following was repeated.

Regarding the scratches, as in the case without the heat source, only a few thin scratches were present, and there was no problem in mechanical durability.

Next, an embodiment of the image quality improving method according to the present invention will be described with reference to FIGS. 5 and 6 in addition to FIGS.

As already described in detail, the corona product deposited on the aC film forming the protective layer 1-3 of the photoreceptor is different from the amorphous silicon (a-Si) film, By using the cleaning member described above, the cleaning member can be removed satisfactorily.

The condition of the cleaning member is that the surface layer of the photoreceptor is not adversely affected (scratch, etc.). The cleaning efficiency is high. The corona product once removed adheres to the photoreceptor very little. There is high uniformity of cleaning and good heat resistance.

The cleaning member satisfying the above conditions includes:
For example, if activated carbon fibers used in deodorization, filters, water purification, etc. are used, corona products can be satisfactorily removed.

The activated carbon fibers are mainly produced from raw materials such as cellulose-based and polyacrylonitrile-based fibers, phenolic resin, and pitch (coal, petroleum). In particular, polyacrylonitrile-based activated carbon fibers are excellent. The activated carbon fibers have a diameter of about 10 to 20 μm, and may be in the form of a felt, mat, fabric, tow, or the like.

FIG. 4 shows an arrangement of a cleaning device 18 using the activated carbon fiber as a cleaning jig 19, and FIG. 1 shows a power switch 4 and a drive device 6 of a drive control system.

FIG. 5 is a perspective view of each example of the cleaning jig 19.
FIG. 5A shows a roller shape, FIG. 5B shows a blade shape, and a belt shape (not shown) may be used. In FIG. 5A, a cleaning member 19-2 made of the activated carbon fiber is disposed on a peripheral surface of a cylindrical rotary support 19-1. As shown in FIG. Rotational contact with the body removes corona products. Further, in FIG. 5 (2), the cleaning member 19-2 made of the activated carbon fiber is disposed on the fixed type support 19-3, and although not shown in FIG. The contact surface 19-2a of the member 19-2 is fixedly contacted to remove the corona product accompanying the rotation of the photoconductor.

As the shape of the above-mentioned activated carbon fiber, a felt-like or mat-like sheet of activated carbon fiber has good air permeability and high absorption efficiency of ozone and nitrogen oxides by corona discharge. When the cleaning jig 19 is formed, a good cleaning member 19-2 is obtained. For example, the roller-shaped support 19-1 shown in FIG.
19-1 can use aluminum, paper tube, plastic, etc., and should not be particularly limited.

Activated carbon fibers are brittle compared to raw materials,
Of course, it can be used alone as a cleaning member. However, when used for a long time, a protective layer can be coated on the outermost surface in contact with the photoreceptor. The protective layer is preferably a nonwoven fabric made of a fiber such as polypropylene or polyester and having good air permeability and a coarse mesh. 0.3-0.5
A sheet having a thickness of about mm is used by stacking one to three times.

In FIG. 4, the cleaning jig 19 incorporated in the cleaning device 18 controls the controller 9 while the image forming apparatus is operating.
As a result, the drive device 6 constantly contacts the photoreceptor to remove corona products on the surface of the photoreceptor. As a result, the corona product that could not be removed by the toner cleaning device 5 or the developing device 14 is removed by adding the cleaning device 18 so that the corona product adhering to the photoconductor is sequentially removed, and the surface of the photoconductor is always cleaned. The state is maintained.

The aC film as the protective layer is 1000 to 1500 kg /
Although those having a size of about mm ² are used, in the image forming apparatus, they are rubbed by the developer, the cleaning blade, the copy paper, etc., so that they are flawed and worn. When the number of flaws increases and corona products enter the flaws,
The cleaning ability of the cleaning jig 19 is reduced, and the image flow becomes a base. Otherwise, when the cleaning member 19-2 locally causes a poor contact with the photoconductor 1 for some reason, the photoconductor is cleaned, which is also a base for image deletion. . Therefore, in the present invention, the heating source (heater) 2 for thermally drying the photoreceptor is used together with the operation of the cleaning jig 19 to cope with a change in humidity and to effectively remove corona products.

The image deletion occurs because the corona product absorbs moisture and lowers the resistance.
Either the corona product or the moisture may be removed. The corona product is removed by the cleaning jig 19, but the moisture is most efficiently dried by the heating source (heater) 2.

As described above, the heating temperature of the surface of the photoreceptor is usually in the range of 35 to 45 ° C. In this temperature management, the controller 9 sets a temperature range of 35 to 40 ° C. based on the surface temperature signal S ₂ detected by the temperature sensor 3. The reasons are as follows: (1) Since the cleaning member 19-2 is used together, good results can be obtained without increasing the temperature as in the case of using the a-Si photoconductor. (2) When the temperature is increased, In the case of an organic photoreceptor, the image density may be reduced, and the reproducibility of a minute image such as a dot pattern may be reduced. (3) Because the temperature is low, there is no need to worry about melting of the toner. If the temperature is lower than 35 ° C., the effect on image deletion is insufficient.

In the state without the cleaning jig 19, the degree of improvement is deteriorated due to the accumulation of corona products, and the same level of resolution is obtained when the photosensitive member temperature is not increased as compared with the case with the cleaning jig. Cannot be obtained. Further, the image density is reduced, and it is difficult to obtain a very good image quality as a whole.

Next, Examples 1 to 2 of several kinds of organic photosensitive members and cleaning members and Examples 3 to 5 of an amorphous silicon photosensitive member will be described.

Example 1 An undercoat layer 1-4 of about 2 μm in which TiO ₂ (Ishihara Sangyo) was dispersed in a polyamide resin on an aluminum cylinder having a diameter of 80 mm, a length of 340 mm, and a thickness of 0.6 mm, and a trisazo pigment were added. 0.15 μm charge generation layer dispersed in polyester resin (CG
L) 1-2a, and a functionally separated organic photosensitive layer comprising a charge transport layer (CTL) 1-2b of about 28 μm in which a stilbene compound is dispersed in a polycarbonate resin (Panlite, C-1400, manufactured by Teijin Chemicals). I prepared my body.

The organic photoreceptor was set in a plasma CVD apparatus, the temperature of the support was set to room temperature, and a film thickness of about 1.2 μm and a Knoop hardness of about 1000 to 13 were obtained using a 100% C ₂ H ₄ gas source gas.
An aC film having a thickness of 00 kg / mm ² and a light transmittance of 90% (780 nm) was laminated.

The photoreceptor thus obtained was mounted on a digital copier experimental machine using a 780 nm semiconductor laser as a light source.

Activated carbon fibers in the form of felt (fine guard felt, FE2) are used as the cleaning member 19-2 for cleaning.
00, Toho Rayon), a polyester non-woven fabric (R-275, Mitsui Petrochemical) was selected as the protective layer, activated carbon fiber and non-woven fabric were overlapped, and triple-wrapped in a 15 mm diameter plastic cylinder, A cleaning jig 19 was prepared in which only the portion in contact with the body was made of double nonwoven fabric.

As a heating source of the photoconductor, a space between the inner wall of the aluminum substrate of the photoconductor and the inner wall of 1.5 mm is provided, and a cylindrical panel heater of 60 W is attached. The temperature sensor 3 is in light contact with the non-image portion of the photoconductor 1. It was installed in such a form.

As a test method, 22 to 24 ° C., 70 to 75% RH
In this environment, a paper-passing test was performed for 4,000 sheets / day for 10 days to check the sharpness, resolution, surface potential, etc. This check is performed for heating source (heater) 2 (surface temperature 4
0 to 42 ° C.), three methods in which both the cleaning device 18 was operated at the same time, only the cleaning device was operated, and both the heater 2 and the cleaning device 18 were turned off.

Table 1 shows the results.

[0079]

[Table 1] ：: No problem in practical use ×: No practicality-: Not checked.

While the surface of the photosensitive member was slightly scratched during the running of 40,000 sheets, the gloss of the amorphous carbon film was not lost, and good results were obtained in both the check method and the check method.

Example 2 The surface of an organic photoreceptor produced by the same method as in Example 1 and used for about 400,000 sheets and having innumerable scratches on the entire surface was cleaned with pure water, activated carbon fiber or the like. It was fully dried and mounted on a digital copier experimental machine.

The image quality was checked in the same manner as in Example 1.

However, regarding the method (3), 30 ° C., 35 ° C.,
The temperature of the photoconductor was set at 45 ° C and 50 ° C, and the effect of the temperature was confirmed.

Table 2 shows the results.

[0085]

[Table 2] ：: No problem in practical use Δ: Signs of image deletion are seen ×: No practicality −: Not checked

In the case of a photosensitive member having considerable scratches, the corona product enters the scratches and the cleaning effect of the cleaning jig becomes insufficient, causing a problem in practical use.

In the above method, if the temperature is 35 ° C. or more,
Although image deletion can be prevented, when the temperature reaches 50 ° C., the image density is significantly reduced from the initial stage, and the reproducibility of the image is reduced. Therefore, a good range of the image is appropriately between 35 ° C and 45 ° C.

Is only in the initial stage, and
Signs of image deletion occur at 00 sheets.

Example 3 An amorphous silicon-based photosensitive member in which an a-Si photosensitive layer was laminated to an aluminum cylinder having a diameter of 80 mm, a length of 340 mm, and a thickness of 3 mm to a thickness of about 28 μm was prepared using a C ₂ H ₄ gas as a raw material. Amorphous carbon film
(a-C film Knoop hardness: about 1250 kg / mm ² ) A test photoconductor was prepared by laminating about 1.2 μm.

This photoreceptor was mounted on an experimental machine (+ charged) of a digital copying machine using a 780 nm semiconductor laser as a light source.

Activated carbon fibers in the form of felt (fine guard felt, FE) are used as the cleaning member 19-2 for cleaning.
-300, Toho Rayon), a polyester non-woven fabric (R-275, Mitsui Petrochemical) was selected as the protective layer, activated carbon fiber and non-woven fabric were superimposed and triple-wrapped in a 15 mm diameter plastic cylinder. A cleaning jig 19 was prepared in which only the portion in contact with the body was made of nonwoven fabric.

As a heating source for the photoconductor, 100
A cylindrical panel heater of W was attached, and the temperature sensor 3 was installed in such a manner as to lightly contact the non-image portion of the photoreceptor 1.

As a test method, the environment was set at 25 ° C. and 80% RH.
And a 50,000-sheet passing test was performed at a rate of 4,000 sheets / day to check the image quality.

The surface temperature of the photoreceptor is controlled between 42 ° C. and 45 ° C. When both the heating source (heater) 2 and the cleaning device 18 are operated simultaneously, only the cleaning device, the heater 2 and the cleaning device 18 are used. This was performed when both devices were turned off. The rotation speed of the cleaning jig 19 was set to about 50 rpm.

The image quality was evaluated in five steps, 5 was equivalent to the initial quality, 0 was the worst (image was not output), and 4 or more was judged to be within the practical level.

FIG. 6 shows the results of image quality (0, 1 to 5) with respect to the number of copies (× 10 ³ ) at this time. In FIG. 6, there is no deterioration in image quality, and there is no sign of quality deterioration in 32,000 sheets. When the cleaning jig is replaced with 40,000 sheets, the image quality almost disappears in about 50 sheet passing runs. Recovered. This is considered to be due to contamination of the member (corona product adhered toner adhered). Is not practical with 500 sheets. It should be noted that the gloss of the photoreceptor was not different from that of the initial stage even when only a few scratches occurred. The surface voltage of the photoreceptor in the apparatus was good with almost no change at 50,000 sheets.

Example 4 Using the same experimental machine and the same photosensitive member as in Example 3, the temperature of the photosensitive member was set from 30 ° C. to 55 ° C., and the image quality was checked in the same manner. The measurement environment is 25 ° C. and 80% RH.

The number of checks was 10,000 each.
Further, both the cleaning device and the heating source were operated from the beginning.
The results are shown in Table-3.

[0099]

[Table 3]

From the results in Table 3, a proper image is from 35 ° C to 50 ° C.
It is obtained in the range of ° C. If the temperature is 35 ° C or less, the effect is poor and 50
If the temperature is higher than ℃, the quality of the toner deteriorates and there is a problem in handling.

Example-5 The same experimental machine and the same photosensitive member as in Example-3 were used, the temperature of the photosensitive member was set at 40 ° C., the measurement environment was 22-24 ° C., and the measurement environment was 50-55.
A paper passing test of 30,000 sheets was performed in an environment of% RH, and image quality at normal temperature was checked. However, the cleaning jig of the cleaning device was attached to only half of the plastic cylinder, and the effect of the presence or absence of the cleaning jig was compared.

Table 4 shows the results.

[0103]

[Table 4]

Even when the test photoreceptor is subjected to a paper passing test in a normal humidity environment, the image quality tends to gradually decrease.
However, when the photosensitive member was always cleaned with the cleaning jig, there was almost no deterioration in image quality.

After 30,000 sheets had been printed, the entire surface was wiped off and dried, and an image was taken. As a result, a uniform image was obtained and no deterioration of the amorphous carbon film was observed.

[0106]

As described above, the method for improving image quality of a photoreceptor according to the present invention is intended to remove a corona product adhering to a photoreceptor obtained by laminating an amorphous carbon film on an a-Si photoreceptor. By using the dedicated cleaning device and the heating source of the photoconductor together, the accumulation of corona products can be suppressed over a long period of time in all environments, and good image quality can be provided without image deletion.

Further, since the surface temperature of the photoreceptor can be kept low, a change in the characteristics of the photoreceptor is small, and no adverse effects such as softening of the toner and a change in the electric characteristics occur.

[Brief description of the drawings]

FIG. 1 is a control system block diagram for implementing the present invention.

FIG. 2 is a schematic cross-sectional view of a configuration example on a surface portion of a photoconductor used in the present invention.

FIG. 3 is a diagram showing a heater ON / OFF timing chart and a photoconductor surface temperature state.

FIG. 4 is a diagram showing a configuration of a peripheral portion of a photoconductor according to the present invention.

FIG. 5 is a perspective view showing each example of a cleaning jig in a cleaning device according to the method for improving image quality of a photoreceptor of the present invention.

FIG. 6 is a graph showing test results of the number of copies and the image quality according to the image quality improving method for a photoconductor of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoreceptor, 1-1 ... Conductive support, 1-2 ... Photosensitive layer,
1-2a: charge generation layer (CGL), 1-2b: charge transport layer (CT
L), 1-3: protective layer (a-C film), 1-4: undercoat layer,
2 ... heater, 3 ... temperature sensor, 4 ... power switch, 5 ... toner cleaning device, 6, 7 ... drive device, 8 ... drive motor, 9 ... control unit (CPU),
10 ... Charge charger, 11 ... Transfer charger, 12
... separation charger, 13 ... static lamp, 14 ... developing device, 18 ... cleaning device, 19 ... cleaning jig, 19-
1, 19-3: Support, 19-2: Cleaning member.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 15/00 303 G03G 21/00 350 G03G 21/00 370-540 G03G 5/00-5/16

Claims (2)

(57) [Claims] 1. A sensor having a protective layer comprising an amorphous carbon film.
A light source, a heating source built in near the surface of the photoreceptor,
It is composed mainly of activated carbon fiber and is directly
Cleaning device with a cleaning member
An image forming apparatus, wherein the cleaning is performed during copying.
Image quality improvement process of the photosensitive member, wherein Rukoto is used together operate the unit and said heat source. 2. A photoconductor heating source incorporated in a photoconductor,
Having a protective layer consisting of an amorphous carbon film on the organic photosensitive layer
For photoconductors, set the heating temperature of the photoconductor to a temperature range of 35 ° C to 45 ° C.
At the surrounding photoconductor surface temperature, non-
In the case of a photoreceptor having a protective layer composed of an amorphous carbon film,
Set the heating temperature of the body to a temperature range of 35 ° C to 50 ° C, respectively.
Image quality improvement process of the photosensitive member according to claim 1, characterized in that a temperature.