JPH0844159A - Contact electrifying device - Google Patents

Abstract

PURPOSE:To maintain electrifying characteristic stable over a long term and to stabilize image quality by providing an optimum roller cleaning means matched with the film strength of a surface layer constituting an electrifying roller and its combination. CONSTITUTION:An electrophotographic device using a contact electrifying system where electrification processing is performed in contact with a photoreceptor drum 101 is equipped with the electrifying roller 102 constituted so that the adhesive strength of a surface layer 203 and an intermediate layer 202 being a layer under the layer 203 may be >=4 which is an evaluation point in an X cut tape method regulated by JIS standard K5400, and the roller cleaning member 210 abutting on the roller 102 and cleaning the surface of the roller 102.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact charging device for charging a photosensitive member in an electrophotographic apparatus such as a copying machine, a facsimile, a laser printer, and more specifically, a charging roller is brought into contact with the photosensitive member to make it uniform. The present invention relates to a contact charging device that charges a battery.

[0002]

2. Description of the Related Art Conventionally, a photosensitive layer on the surface of a photoconductor (a drum-shaped or belt-shaped photoconductor) is uniformly charged by a charging means, and image light is irradiated on the photosensitive layer to form an electrostatic latent image on the surface. However, an electrophotographic apparatus using an electrophotographic process in which a normal powdery toner is adhered to visualize the electrostatic latent image, and then the image forming step of electrostatically transferring the electrostatic latent image onto recording paper is repeated is known. On the street.

Inorganic photoelectric materials such as selenium, cadmium oxide, and zinc oxide are known as photoelectric materials used as the photosensitive layer. In addition, recently, many organic compounds have been used for the photosensitive layer.

In an electrophotographic process using such a photoconductor, as means for charging the photoconductor,
A corona discharge method, which is a non-contact charging method for uniformly charging the surface of the photoconductor, is often used. In this corona discharge method, a high voltage is applied to a tungsten wire of about 30 to 100 μm called a corona wire for discharging. However, it is known that the air around the corona wire is ionized to generate a large amount of undesirable gases such as ozone and nitric oxide. When ozone or the like has a high concentration, it not only harms the human body, but also adversely affects the characteristics of the photoconductor and its components.

In recent years, due to reasons such as image quality improvement,
The photoconductor has become an organic photoconductor (OPC) for negative charging, but in the conventional corona discharge method, ozone gas is remarkably generated when a negative discharge is performed. Further, although the ozone concentration discharged outside the machine is being more strictly regulated by safety standards in Japan and abroad, the corona discharge method has a limit in reducing the ozone generation amount during charging.

Therefore, in contrast to the above corona discharge method,
A contact-type charging device (hereinafter, referred to as a contact charging device) that performs a charging process by bringing a charging member such as a charging roller, a charging blade, or a charging brush into contact with the surface of the photoconductor.
Is used. This contact charging device has the advantages that the voltage applied to the charging member is as small as about 1 to 2 kv and the amount of ozone generated is very small. In particular, the use of a charging roller as the contact member stabilizes the contact state with the photoconductor more than the charging blade or the charging brush, and thus has been widely used in recent years.

However, since the charging roller is in direct contact with the photoconductor, toner, paper dust, etc. on the surface of the photoconductor are likely to adhere. Therefore, the image quality is deteriorated due to the toner or the like adhering to the charging roller, for example, white spots or the like are generated due to a decrease in the charging potential corresponding to the adhering position. As a means for solving this, for example, a method of contacting a cleaning roller made of a felt material or a cleaning member such as a cleaning pad with the charging roller to remove the deposits on the charging roller is disclosed in JP-A-2-301777. "Image forming device"
Is disclosed in.

[0008]

However, according to the technique using the conventional cleaning member, the cleaning member is simply applied to the surface of the charging roller without considering the matching with the film strength of the surface layer of the charging roller. Since they are provided in contact with each other, the side surface of the cleaning by the cleaning member damages the surface of the charging roller,
There is a problem that stable charging characteristics may not be obtained in the long term. In particular, when the above damage progresses, damage to the lower layer may occur, which causes a problem of image deterioration.

Further, when only the charging roller is used without using the cleaning member, it is necessary to replace the charging roller or take it out for cleaning when the surface of the charging roller is soiled by a predetermined amount or more. As a result, the charging roller replacement period or cleaning interval is relatively short, which is not convenient.

The present invention has been made in view of the above, and provides an optimum cleaning means that matches the film strength of a surface layer constituting a charging roller and a combination thereof, and has stable charging characteristics even in the long term. The purpose is to maintain the image quality and stabilize the image quality.

Further, the present invention has been made in view of the above, and in a contact charging device using only a charging roller without using a cleaning member, stable charging characteristics can be maintained for a long time, and image quality can be improved. It is intended to stabilize the charging efficiency of the charging roller and improve the convenience of the charging roller replacement period or cleaning interval.

[0012]

In order to achieve the above object, a contact charging device according to a first aspect of the present invention comprises a charging roller formed by laminating a plurality of members having different functions, and a surface of the charging roller. In a contact charging device having a cleaning member for cleaning the surface of the charging roller, the adhesion strength between the surface layer and the intermediate layer, which is the lower layer, is 4 or more by the X-cut tape method defined by JIS K5400. The configuration is

In the contact charging device according to the second aspect, the cleaning means is a cleaning pad or a cleaning roller made of a felt material.

A contact charging device according to a third aspect of the present invention is a contact charging device having a charging roller formed by laminating a plurality of members exhibiting different functions, and a cleaning member for cleaning the surface of the charging roller. In the charging roller, the adhesion strength between the surface layer and the intermediate layer below the surface layer is JIS K54.
The X-cut tape method defined by No. 00 has an adhesion strength of 8 or more, and the cleaning means has a surface made of a grinding member.

In the contact charging device according to the fourth aspect, the grinding member of the cleaning means is emery paper.

A contact charging device according to a fifth aspect of the present invention is a contact charging device having a charging roller formed by laminating a plurality of members exhibiting different functions, and a cleaning member for cleaning the surface of the charging roller. In the charging roller, the adhesion strength between the surface layer and the intermediate layer below the surface layer is JIS K54.
The X-cut tape method defined by 00 has an adhesion strength of less than 4 and the cleaning means is a brush-like member.

A contact charging device according to a sixth aspect of the present invention includes a contact charging device having a charging roller formed by laminating a plurality of members exhibiting different functions and having no cleaning means for cleaning the surface of the charging roller. In the apparatus, the charging roller is
The adhesion strength between the surface layer and the intermediate layer, which is the lower layer, is evaluated by the X-cut tape method defined by JIS standard K5400.
It has the following adhesion strength.

[0018]

In the contact charging device of the present invention (claim 1), the adhesion strength between the surface layer and the intermediate layer below it is relatively large (evaluation point 4 or more by the X-cut tape method defined by JIS K5400). The durability of the charging roller is improved by using the charging roller and the cleaning means in combination with the cleaning roller.

The contact charging device of the present invention (claim 2)
In order to improve the durability of the charging roller, the surface of the charging roller is cleaned by using a cleaning means made of a felt material or a cleaning means composed of a cleaning roller.

Further, the contact charging device of the present invention (claim 3)
Is a charging roller that has the highest adhesion strength between the surface layer and the intermediate layer that is the lower layer (evaluation point of 8 or more by the X-cut tape method specified in JIS K5400), and a cleaning unit that has a grinding member on its surface. When used in combination, the durability of the charging roller is improved.

The contact charging device of the present invention (claim 4)
By using the emery paper as the grinding member of the cleaning means to clean the surface of the charging roller, the durability of the charging roller is improved.

The contact charging device of the present invention (claim 5)
Is a charging roller having a relatively weak adhesion strength between the surface layer and the intermediate layer which is the lower layer thereof (evaluation point is less than 4 by the X-cut tape method specified in JIS K5400), and cleaning of the brush-like member on the charging roller. When used in combination with the means, the durability of the charging roller is improved.

Further, the contact charging device of the present invention (claim 6)
Uses the charging roller with the weakest adhesion strength between the surface layer and the intermediate layer below it (evaluation point 2 or less by the X-cut tape method specified in JIS K5400), and does not use cleaning means. This improves the durability of the charging roller. Also, due to friction with the surface of the photoconductor, the surface of the charging roller is gradually peeled off, so that the surface is always cleaned.
Less dirt, longer charging roller replacement period,
It also eliminates the need for cleaning.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing the main configuration of an electrophotographic apparatus using the contact charging device of the present invention. In the figure, 101 is a photosensitive drum on which an electrostatic latent image is formed, and 10
Reference numeral 2 is a charging roller that contacts the photosensitive drum 101 to perform charging processing, 103 is image light such as reflected light of a document or laser light, 104 is a developing device that attaches toner to an electrostatic latent image on the photosensitive drum 101, Reference numeral 105 denotes a registration roller for conveying the recording sheet conveyed from a sheet feeding section (not shown) at the timing of the image on the photosensitive drum 101, and 106.
Is a transfer charger that transfers the toner image on the photoconductor drum 101 to a recording sheet, 107 is a separation charger that electrically separates the recording sheet that is in close contact with the surface of the photoconductor drum 101,
Reference numeral 108 denotes a cleaning device that removes and collects residual toner on the surface of the photosensitive drum 101, and 109 denotes the photosensitive drum 10.
It is a quenching lamp for removing the residual potential of No. 1 and restoring the initial level. In FIG. 1, functional units normally required in other electrophotographic processes are omitted.

A basic image forming operation in the electrophotographic apparatus configured as described above will be described. The surface of the photosensitive drum 101 is uniformly charged to a high potential by supplying a DC voltage from the power pack to the charging roller 102 in contact with the photosensitive drum 101. Shortly thereafter,
When the image light 103 is applied to the surface of the photosensitive drum 101,
The potential of the irradiated part decreases. Since the image light 103 has a distribution of the amount of light according to the black / white of the image, the image light 10
By the irradiation of 3, the potential distribution corresponding to the recorded image, that is, the electrostatic latent image is formed on the surface of the photosensitive drum 101.

The portion on which the electrostatic latent image is formed is the developing device 10.
After passing 4, the toner adheres according to the level of the potential, and a toner image is formed by visualizing the electrostatic latent image. The recording paper is conveyed by the registration roller 105 to the portion where the toner image is formed at a predetermined timing, and overlaps with the toner image. After the toner image is transferred onto the recording paper by the transfer charger 106, the recording paper is transferred to the photosensitive drum 101.
Is separated by a separation charger 107. The separated recording paper is conveyed through the conveyance path. Then, after being thermally fixed by a fixing unit (not shown), it is discharged to the outside of the machine. After the transfer process is finished, the surface of the photoconductor drum 101 is cleaned by the cleaning device 108, and the quenching lamp 109 erases the residual electric charges to prepare for the next image forming process.

In the above electrophotographic apparatus, since the charging roller 102 is used instead of the usual corona discharge type charging charger, the ozone generation thereof is reduced by 40 to 60% as compared with the charging charger. If it is desired to further reduce the generation of ozone gas, a transfer belt or a transfer roller may be used instead of the transfer charger 106.

Next, the structure of the charging roller 102 and its charging system will be described with reference to FIG. In the figure, 201 is a cored bar, which is made of a conductive material such as SUS (stainless steel) material, steel + plated material, and Al (aluminum bar) material. The core metal 201 includes an intermediate layer 202 and a surface layer 2.
03 is provided. The intermediate layer 202 has a wall thickness of 1 to
About 4 mm of medium resistance elastic body such as epichlorohydrin rubber or synthetic rubber such as silicon rubber, ethylene propylene rubber, nitrile rubber, norbornene rubber is used, and conductive powder (for example, carbon black) is used in these synthetic rubbers. Or metal powder). In addition, as these characteristics, volume resistance is 1
0 ⁵ Ω · cm or less, preferably 10 ³ Ω · cm or less, rubber hardness (JIS · A) 20 to 45 degrees, preferably 25 to
40 degrees is commonly mentioned.

Further, the surface layer 2 is provided on the outer peripheral surface of the intermediate layer 202.
03 has a layer thickness of 3 to 25 μm, preferably 4.5 to 12 μm
It is made of the following materials. As the material of the intermediate layer 203, synthetic rubber in which epichlorohydrin rubber, lumiflon and silica are dispersed and mixed, or lumiflon in which tin oxide is dispersed and mixed, nylon, cellulose or the like is used. The volume resistance of the surface layer 203 is
10 ⁵ to 10 ¹³ Ω · cm, preferably 10 ⁶ to 10 ¹² Ω
・ Cm is good. Further, it is desirable that the volume resistance from the intermediate layer 202 to the surface layer 203 has a conductivity of about 10 ⁶ to 10 ¹² Ω · cm.

Further, both ends of the cored bar 201 are connected to the bearing 20.
4 is loosely fitted and is rotatably supported. Further, the bearing 204 is urged by a spring 205 to press the charging roller 102 against the photosensitive drum 101 with a predetermined pressure. The mechanism for press-contacting the charging roller 102 and the photosensitive drum 101 is not limited to this, and the charging roller 102 is brought into contact with the photosensitive drum 101 so that the driving force of the photosensitive drum 101 is
Other mechanism may be used as long as it is configured to rotate the charging roller 102 by friction with 02. In addition, the power supply receptacle 206 is provided on one end surface of the charging roller 102.
Are provided so as to make contact with each other, and a power supply 207 for applying a voltage is connected to the power supply receptacle 206.
Further, 210 is a roller cleaning member for contacting the charging roller 102 to remove adhered matter on the roller surface. Specifically, the pad member 301, the emery paper 401, the bristle brush 501, and the felt roller 701, which will be described later, are provided. Equivalent to.

In the above structure, the charging roller 102
Is supplied with voltage from the power supply 207, the application timing of which is controlled by the control means (not shown), to the core 201 via the power supply receptacle 206. By this power feeding, the core metal 201 → the intermediate layer 202 → the surface layer 203 → the photosensitive drum 1
A current flows to 01, and the photosensitive drum 101 is charged. The power supply system is not particularly limited to this form as long as the above current path can be obtained. For example, the power source 207 may be connected to the spring 205 and the bearing 204 may be made of a conductive member.

Next, a method for measuring the material strength of the surface layer 203 which becomes the contact charging portion with the photosensitive drum 101 and the adhesion strength between the surface layer 203 and the lower layer (intermediate layer 202) will be described. This measurement method is based on "JIS standard K5400,
"8.5.3 X-cut tape method" (hereinafter referred to as "X-cut tape method") is applied. That is, as shown below, the X-cut tape method is originally a measuring method provided to measure the adhesiveness of a coating material, and is known as a method for testing a coated flat plate. In the present invention, this X-cut tape method is applied for evaluation of the charging roller 102.

[About X-cut tape method] (1) Summary An X-shaped cut (X-cut) that penetrates the coating film on the test piece and reaches the bare surface with a cutter knife,
Stick cellophane adhesive tape on it and peel it off.
Examine the superiority or inferiority of adhesion to the base material or coating film. It should be noted that the following regulations are JIS regulations revised for evaluation of the charging roller 102. (2) Apparatus and materials (a) Test piece The charging roller 102 itself is used. (B) Cutter knife specified in JIS K5400 (c) Cellophane adhesive tape specified in JIS K5400 (d) Eraser specified in JIS S6050 (3) Operation (a) Using a cutter knife in the center of the test piece , Cut at an angle of 30 degrees to each other and make a cut with a length of about 40 mm reaching the substrate as shown in FIG. Further, the cut is made by using a steel ruler (or if it has elasticity and follows the curved surface of the charging roller 102 to a certain degree, the blade edge of the cutter knife is 35 to 4 with respect to the coated surface).
Hold at a constant angle in the range of 5 degrees and pull at a constant speed for about 0.5 seconds. (B) Next, as shown in Fig. 8 from above the two intersecting cuts, attach cellophane adhesive tape so that the length of the adhesive portion is about 50 mm, and rub it with an eraser to completely tape the coating film. To adhere to. For this adhesion, the entire surface of the adhesive portion of the tape is rubbed with an eraser evenly, and when there are bubbles, the eraser is used to crush the bubbles. (3) Evaluation The peeling state of the X-cut portion when the tape is peeled off is visually observed, and the evaluation score shown in FIG. 9 is obtained and compared with the evaluation score specified in the product standard of the sample. (4) Prescribed conditions of product standards Designated layer Intermediate layer 202 (conductive layer), surface layer 203

Next, the charging roller 102 shown in FIG.
The specific manufacturing conditions of the configuration and the evaluation thereof will be described for each example. [Embodiment 1] In the charging roller 102, the core 201 is made of SUS material (φ8 × length 341 mm), and the intermediate layer 202 is made of epichlorohydrin rubber (thickness 3 mm × length 300 m).
m), the surface layer 203 is a synthetic rubber in which epichlorohydrin rubber, lumiflon and silica are dispersed and mixed (layer thickness: 8.
8 μm). In addition, the intermediate layer 202 to the surface layer 20
The volume resistance between 3 is 10 ¹¹ Ω · cm. Further, as a method of applying the surface layer 203 to the intermediate layer 202, the intermediate layer 2
02 is adhered to the cored bar 201 or fixed by a method such as press fitting, then the surface of the intermediate layer 202 is polished and the surface layer 203 is applied by air spray, and then 100-2
A product dried at a temperature of 00 ° C, preferably around 150 ° C for 30 minutes is used.

Next, the charging roller 1 configured as described above.
No. 02 was evaluated by the above-mentioned X-cut tape method. As a result, it was confirmed that slight peeling occurred in the X-cut portion, but the intermediate layer 202 was not exposed and an evaluation point of 8 was obtained. Further, the charging roller 102 is incorporated into an actual machine, and a roller cleaning member 210 (levels 1 to 1 below) is installed.
3) was brought into contact with the charging roller 102 to perform a running evaluation test under the following test conditions. The results are shown in Table 1.

(Test conditions) -Photoconductor: OPC-Photoconductor linear velocity: 120 mm / sec-Charging roller: φ14 × 300-Charging applied voltage: -1500 V-Paper size: A4-Development method: Dry 2 components-Cleaning Method: Counter blade (Fig. 1
reference)

Level 1 roller cleaning member: pad member 301 made of polyethylene felt material (see FIG. 3) Level 2 roller cleaning member: Emery paper (JIS1000)
401 (see FIG. 4) -Level 3 roller cleaning member: Teflon bristle brush 501 (see FIG. 5) (contacts the roller when the bristles are long enough to contact the belly) -Level 4 roller cleaning member: none

[0038]

[Table 1]

From the above running test results, the charging roller 102 having an evaluation point of 8 by the X-cut tape method had the merits of level 2> level 1> levels 3 and 4. It should be noted that, as shown in FIG. 6, the absence of streaks on the rollers means that the streaks generated are uneven streaks on the charging roller 102 due to the contact of the roller cleaning member 210. It is different from the streak. Therefore, the white stripe on the image and the corresponding position on the charging roller are black stripes. Also, in the first embodiment, the pad 30
1 instead of the felt roller 701 as shown in FIG.
Even if the charging roller 102 is brought into contact with the charging roller 102, the same effect as described above can be obtained.

[Embodiment 2] The structure of the charging roller 102 is substantially the same as that in Embodiment 1, the surface layer 203 is made of nylon (trade name: CM8000, manufactured by Toray Industries, Inc.), and the intermediate layer 202 is used.
The volume resistance of the surface layer 203 is 10 ¹² Ω · cm. The charging roller 102 was similarly evaluated by the X-cut tape method. As a result, no peeling occurred and an evaluation point of 10 was obtained. Further, the same running evaluation test as in Example 1 was performed. The results are shown in Table 2.

[0041]

[Table 2]

From the above running test results, it can be seen that the charging roller 102 having an evaluation point of 10 by the X-cut tape method had merits and demerits of level 2> level 1> levels 3 and 4.

Here, the evaluation results by the X-cut tape method will be considered. In the charging roller 102 (lumiflon + hydrin + silica) of Example 1, only the tip of the X-cut portion is peeled off, and this is the portion cut by the cut, that is, the bond with the surrounding surface layer 203 is broken. The surface layer 20 means that only the sloping part has peeled off.
It can be said that the adhesive force (coupling force) of 3 is strong. Further, since the peeling does not reach the underlying intermediate layer 202 only at the tip, it can be said that the adhesive force between the intermediate layer 202 and the surface layer 203 is strong. This is because even if the connection with the surroundings is broken, it will not peel off.

Further, a strong member is suitable as the roller cleaning member 210 for cleaning the surface of the charging roller 102 having a large material strength of the surface layer 203. For example, as the felt material, organic resin fiber or inorganic fiber is used. Is effective. Examples of the organic resin fiber include polyethylene, polypropylene, polyester, polyurethane, polyamide, cellulose, cellulose acetate, polyvinyl acetate, and PTFE. On the other hand, as the inorganic fiber, glass fiber, carbon fiber, iron fiber or the like can be used. Further, the strength of the roller cleaning member 210 is increased, and
It was confirmed that the effect is obtained even if the surface of the charging roller 102 is ground. As this grinding member, emery paper (paper file, a general one of JIS 800-1400) is suitable.

[Embodiment 3] Here, the surface layer 203 of the charging roller 102 is made of Lumiflon in which tin oxide is dispersed and mixed. Further, the volume resistance of the intermediate layer 202 to the surface layer 203 is set to 10 ¹² Ω · cm. Then, the strength of the charging roller 102 was evaluated by the X-cut tape method.
As a result, peeling occurred in most of the X-cut portion where the tape was stuck, and the intermediate layer 202 was also exposed in some places, and the evaluation score was 2. Further, this charging roller 102 was subjected to a running evaluation test under the same conditions as in Example 1 above, and the results shown in Table 3 below were obtained.

[0046]

[Table 3]

From the above running test results, the charging roller 102 having an evaluation point of 2 according to the X-cut tape method is inferior and inferior in level 4> level 3> level 1> level 2.

Here, the evaluation of the X-cut tape method of Example 3 will be considered. Charging roller 102 of Example 3
Most of the X-cut portion of (Lumiflon / tin oxide) has been peeled off, so the adhesive force (coupling force) between the surface layers 203.
It can be said that the adhesive force between the intermediate layer 202 and the surface layer 203 is weak because the adhesive strength is weak and the intermediate layer 202 is exposed.
Therefore, such a charging roller 102 (Example 3)
The roller cleaning member 21 that reduces damage
0 is suitable, and a brush with a small contact pressure is preferable. In addition, at the level of evaluation point 2 by the X-cut tape method,
Those who don't attach any roller cleaning member more than the bristle brush (the charging roller 102 contacts only the photosensitive drum 101)
Can be said to be good.

In the above result, the reason that level 4> level 3 is that the surface layer 203 of the charging roller 102 of the third embodiment is
This is because the surface layer 203 is gradually removed due to contact with the photosensitive drum 101, and the surface layer 203 is always cleaned. At this time, on the photosensitive drum 101,
Although the scraps and the like of the surface layer 203 are attached, they do not affect the image quality, and the image quality can be stabilized as compared with the white spots and the like caused by the dirt on the charging roller.

[0050]

As described above, according to the contact charging device of the present invention (claim 1), the adhesion strength between the surface layer and the intermediate layer as the lower layer is relatively high (JIS K540).
(Evaluation score is 4 or higher by the X-cut tape method specified by 0) The charging roller and the cleaning means are used in combination, so that the durability of the charging roller is improved and the charging characteristic is stable in the long term. It is possible to maintain the image quality and stabilize the image quality.

The contact charging device of the present invention (claim 2)
Uses a cleaning pad or cleaning roller made of felt material to clean the surface of the charging roller, which further improves the durability of the charging roller and maintains stable charging characteristics in the long term. , The image quality can be stabilized.

Further, the contact charging device of the present invention (claim 3)
Is a charging roller that has the highest adhesion strength between the surface layer and the intermediate layer that is the lower layer (evaluation point of 8 or more by the X-cut tape method specified in JIS K5400), and a cleaning unit that has a grinding member on its surface. Since they are used in combination, the durability of the charging roller is improved, stable charging characteristics are maintained over a long period of time, and the image quality can be stabilized.

Further, the contact charging device of the present invention (claim 4)
Uses an emery paper as a grinding member of the cleaning means to clean the surface of the charging roller, further improving the durability of the charging roller, maintaining stable charging characteristics for a long time, and stabilizing the image quality. Can be planned.

A contact charging device of the present invention (claim 5)
Is a charging roller having a relatively weak adhesion strength between the surface layer and the intermediate layer which is the lower layer thereof (evaluation point is less than 4 by the X-cut tape method specified in JIS K5400), and cleaning of the brush-like member on the charging roller. Since the charging roller is used in combination, the durability of the charging roller is improved, stable charging characteristics are maintained for a long time, and the image quality can be stabilized.

Further, the contact charging device of the present invention (claim 6)
Has the weakest adhesion strength between the surface layer and the intermediate layer below it (evaluation point 2 or less by the X-cut tape method specified in JIS K5400), and uses no cleaning means. ， The durability of the charging roller is improved,
It is possible to maintain stable charging characteristics over the long term and stabilize image quality. In addition, the surface of the charging roller is gradually peeled off due to friction with the surface of the photoconductor and is always in a cleaning state, so that dirt is reduced, the replacement period of the charging roller is extended, and cleaning is not necessary. The property is improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a main configuration of an electrophotographic apparatus using a contact charging device of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of a charging roller of the present invention and a charging system thereof.

FIG. 3 is an explanatory diagram illustrating a configuration of a contact charging device according to a first exemplary embodiment.

FIG. 4 is an explanatory diagram showing a configuration of a contact charging device according to a second exemplary embodiment.

FIG. 5 is an explanatory diagram showing a configuration of a contact charging device according to a third exemplary embodiment.

FIG. 6 is an explanatory diagram showing streaks on rollers in a running evaluation test.

FIG. 7 is an explanatory diagram showing another configuration example of the contact charging device according to the first exemplary embodiment.

FIG. 8 is an explanatory diagram showing how to attach a tape according to the X-cut tape method.

FIG. 9 is a chart showing criteria of evaluation scores according to the X-cut tape method.

[Explanation of symbols]

 101 Photoreceptor Drum 102 Charging Roller 202 Intermediate Layer 203 Surface Layer 210 Roller Cleaning Member 301 Pad Member 401 Emery Paper 501 Hair Brush 701 Felt Roller

Claims (6)

[Claims] 1. A contact charging device comprising a charging roller formed by laminating a plurality of members exhibiting different functions and a cleaning member for cleaning the surface of the charging roller, wherein the charging roller has a surface layer and its surface layer. A contact charging device, characterized in that the adhesion strength to an intermediate layer as a lower layer is a rating point of 4 or more by an X-cut tape method defined by JIS K5400. 2. The contact charging device according to claim 1, wherein the cleaning unit is a cleaning pad or a cleaning roller made of a felt material. 3. A contact charging device having a charging roller formed by laminating a plurality of members exhibiting different functions and a cleaning member for cleaning the surface of the charging roller, wherein the charging roller has a surface layer and its surface layer. The adhesion strength with the lower intermediate layer is an adhesion strength of 8 or more in the X-cut tape method defined by JIS K5400, and the cleaning means has a surface made of a grinding member. Charging device. 4. The contact charging device according to claim 3, wherein the grinding member of the cleaning means is emery paper. 5. A contact charging device comprising: a charging roller, which is formed by laminating a plurality of members exhibiting different functions; and a cleaning member for cleaning the surface of the charging roller, wherein the charging roller has a surface layer and its surface layer. The contact charging device is characterized in that the adhesion strength to the lower intermediate layer is an adhesion strength of less than 4 according to the X-cut tape method defined by JIS K5400, and the cleaning means is a brush-like member. . 6. A contact charging device having a charging roller formed by laminating a plurality of members exhibiting different functions, and having no cleaning means for cleaning the surface of the charging roller,
The contact charging device, wherein the charging roller has an adhesion strength between a surface layer and an intermediate layer, which is a lower layer thereof, of an evaluation point of 2 or less by an X-cut tape method defined by JIS K5400.