JPH0869171A - Electrophotographic printer - Google Patents

Abstract

PURPOSE: To stably form a toner layer and further, to reduce pressing at a low cost, even if toner is deteriorated or the number of printing sheets is increased, in an electrophotographic printer, especially, the toner forming method. CONSTITUTION: This electrophotographic printer is composed of a stirring part provided in a toner tank and stirring the toner, a developing roller 4 forming the toner layer on the roller surface and developing a latent image formed on a photoreceptor drum 1, a recovering roller 6 recovering the toner after the development of the developing roller 4 and a layer thickness regulating part controlling the thickness of the toner layer of the developing roller 4, and a doctor blade 5 for regulating the thickness of the toner layer is made of a plate, and the radius R of a part in contact with the developing roller 4 is set to R>=0.5t with respect to a plate thickness (t) and the dimension of R is 1 to 5 times toner grain diameter ϕt . At the time of forming the toner layer, a prescribed bias voltage is applied between the doctor blade 5 and the developing roller 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic printer, and more particularly to a developing means using non-magnetic one-component toner.

[0002]

2. Description of the Related Art FIGS. 8 and 9 are views for explaining a conventional electrophotographic printing apparatus. FIG. 8 shows an example of the construction of a developing apparatus thereof, and FIG. 9 shows toner at the tip of an L-shaped doctor blade. Shows the behavior of.

In an electrophotographic printing apparatus, as shown in FIG. 8, a latent image is formed on a photosensitive drum 1 by exposing it to a laser beam or the like, and a uniform toner layer thickness is controlled on the latent image. Toner is electrically attached and developed, and this is transferred onto paper (recording paper) by the transfer unit (transfer roller 11).

[0004]

However, the developing roller 4
It is difficult to form a stable toner layer on top, and as the number of printed sheets increases, the agitated toner inside the developing device 3 deteriorates, causing fog or black solid printing. There was a problem of lowering.

Further, since the conventional doctor blade 5 for forming a toner layer uses a thick plate or an L-shaped doctor blade, as shown in FIG. There have also been problems such as toner accumulation and thickening of the toner layer, and reduction of the charge amount. Further, in the case of these doctor blade structures, in order to make the toner layer thin, a high pressure is required by pressing against the developing roller 4, so that the developing roller 4 is distorted and the toner layer thickness varies, There is a problem that parts appear as black streaks on the print. Further, the doctor blade 5 itself has a drawback that it is expensive because it uses a thick plate or is processed into an L shape.

In view of the above drawbacks of the prior art, the present invention makes it possible to stably form a toner layer even when the toner deteriorates or the number of printed sheets increases, and the toner can be formed at a low cost with a low pressure. An object of the present invention is to provide a photographic printing device.

[0007]

FIG. 1 is a diagram for explaining the principle of the present invention. FIGS. 1 (a) and 1 (b) show a case where a doctor blade is manufactured by press working, and FIG. Shows the shape of the doctor blade when pressed, as shown in Fig. 1 (d).
Shows an example of the shape when the doctor blade is manufactured by polishing with a grindstone. The above problems can be solved by the electrophotographic printing apparatus configured as described below.

The doctor blade 5 can be manufactured at a low cost by manufacturing the doctor blade 5 using a punching droop of a press, or by manufacturing the doctor blade 5 by pulling the end of a flat plate through a grindstone formed into a desired shape. Can be manufactured. In the toner layer formation, the space between the doctor blade 5 and the developing roller 4, 0.5 to toner particle diameter phi _t
It should be about 5 times as small as possible to reduce the amount of toner restraint, and it is desirable to use a flat plate to prevent toner accumulation at the entrance of the space. To make it easier for toner to get on the developing roller 4,
The friction coefficient of 4 is 0.3-2. The surface roughness of the developing roller 4 is set to Rz 3 μm or less so that the thin layer of toner is not affected by the unevenness. Apply at least a developing bias (for example, -300 V) or more bias (for example, -400 V) between the doctor blade 5 and the developing roller 4, and
Between the four steps, the toner is developed as if developing the toner layer.

With the above-mentioned means and the combination thereof, the conventional means for forming a toner layer by applying pressure to the doctor blade 5 becomes a means for forming a thin layer with the tip shape of the doctor blade 5. The pressure can also be lowered.

[0010]

Embodiments of the present invention will be described in detail below with reference to the drawings. The above-mentioned FIG. 1 is an explanatory view of the principle of the present invention.
FIG. 7 is a diagram showing an embodiment of the present invention, and FIG.
FIG. 3 shows a configuration example of a developing device section of an electrophotographic printing apparatus of the present invention, FIG. 3 shows a relationship between a friction coefficient of a developing roller and a resin coat film thickness, and FIG. 4 shows a toner layer thickness and a doctor blade. Shows the relationship with the bias voltage ΔV between the developing rollers,
FIG. 5 shows the relationship between the optical density and the bias voltage (ΔV) between the doctor blade and the developing roller, and FIGS.
The relationship between the number of printed sheets and fog is shown in Fig. 6 (a).
FIG. 6 (b) shows the transition of the toner voltage, FIG. 6 (c) shows the transition of the fog, and FIG.
7D shows the toner flow in the doctor blade of the present invention, FIG. 7A shows the transition of the toner layer thickness, and FIG. 7B shows the transition of the print density. 6 (d) shows the transition of the fog density on the photosensitive drum.

In the present invention, the doctor blade 5
Means using a press sag of a press, or by pulling out the end of a flat plate by passing it through a grindstone formed into a desired shape, and when forming a toner layer, a doctor blade 5 and a developing blade. the space between the rollers 4, 0.5 to toner particle diameter phi _t
The amount of restraint of toner is reduced as much as 5 times as much as possible, and a means which is preferably flat so as not to collect toner at the entrance of the space portion and a developing roller for facilitating the toner to ride on the developing roller 4
4 means to make the friction coefficient 0.3 to 2 and the surface roughness of the developing roller 4 to be Rz 3 μm or less so that the thin layer of toner is not affected by the unevenness, and between the doctor blade 5 and the developing roller 4. A developing bias (for example, -300 V) or higher (for example, -400 V) to the doctor blade 5 and developing roller.
The means for facilitating the formation of the toner layer by developing the toner between the four areas, and the combination means are the means necessary for carrying out the present invention. Note that the same reference numerals indicate the same object throughout the drawings.

2 to 7, the structure and operation of the electrophotographic printing apparatus of the present invention, particularly the developing apparatus thereof, will be described below with reference to FIG. FIG. 2 is an explanatory diagram of an embodiment of the developing device according to the present invention. In FIG. 2, reference numeral 1 is an OPC photosensitive drum, which rotates at a diameter of 40 mm and a peripheral speed of 70 mm / s.

First, for the pre-charging, the surface potential of the photosensitive drum 1 is charged to -650V by using the rotating brush 2. The print information forms a latent image by irradiating the photosensitive drum 1 with light according to the information by a laser scanning optical system (not shown). The formed latent image is a non-magnetic one-component developing device 3
Done by The non-magnetic one-component developing device 3 is composed of a developing roller 4, a doctor blade 5, a collecting roller 6, an agitator 7, a paddle 8, a toner bottle 9, and an outer 10. In the developing section, the developing roller 4 in contact with the photosensitive drum 1 rotates in the same direction at about twice the peripheral speed of the photosensitive drum, and the toner formed in a thin layer by the doctor blade 5
A visible image is formed by attaching it to the latent image portion of the photosensitive drum 1. Toner that does not contribute to development is
It is stripped off by the collecting roller 6 rotating in the opposite direction, and returned to the inside of the developing device 3 through the lower part of the collecting roller 6.

On the other hand, the new toner is supplied to the developing roller 4 on the doctor blade 5 side by the rotation of the collecting roller 6,
It is carried to 5 parts of the doctor blade and a toner layer is formed. To replenish the toner, the toner swept from the toner bottle 9 by the outer 10 is carried to the developing roller 4 side while being agitated by the agitator 7, and is collected by the paddle 8 on the collecting roller.
Toner is being efficiently supplied to 6. The toner adhering to the photosensitive drum 1 is attracted to the paper by the transfer roller 11 at the transfer portion, melted by the fixing device 12 and fixed on the paper. The contents of the present invention will be described using the apparatus described above.

First, the doctor blade of the present invention is manufactured by punching (pressing) with a metal plate mold which is generally performed. 1 (a) and 1 (b) are views for explaining the manufacture of a doctor blade by a press working method.

As shown in the figure, there are two types of presses, a male type and a female type, and a metal plate for producing the doctor blade 5 is placed on a male type press platen, and the metal plate is attached to the male plate. Die into the shape of a mold. At this time, the cut surface is sagged to form a smooth arc. The size of the circular arc is determined by the size (clearance) of the male and female press plates shown in FIGS. 1 (a) and 1 (b).

The cross-sectional shape of the doctor blade 5 manufactured by such press working is shown in FIG. 1 (c). Here, in the doctor plate 5 manufactured with clearances 0.01 mm and 0.03 mm at a plate thickness of 0.1 mm, R was sufficiently larger than the plate thickness t, and the L dimension in the figure was 0.013 and 0.028 mm. The particle size of the toner is 8 to 12 μm, which satisfies the shape of the doctor blade 5 in claims 1 to 5. It is also possible to use a grindstone to create the shape of the metal plate end within the scope of the claims,
When a trial was made with 0.1 mm and r of 0.05 mm, a satisfactory doctor blade was obtained. Figure 1 (d) shows the shape and dimensions R of the doctor blade 5 that was prototyped using the above grindstone.
(= 0.1 mm) and r (= 0.05 mm) are shown.

The developing roller 4 of the present invention was manufactured using NBR rubber. FIG. 3 shows the friction coefficient at this time as an experimental value in relation to the urethane resin coat thickness. As shown in the figure, the film thickness of the resin coat is 3-10 μm
In, the coefficient of friction of the developing roller 4 is within the range of 0.3 to 2. As one means for adjusting the friction coefficient of the developing roller 4, the resin coat may be subjected to predetermined tape polishing, or the resin coat may be irradiated with ultraviolet rays.

When the surface roughness of the resin coat is Rz 5 μm or more, thin white spots were found during black solid printing. This is because the toner layer is a thin layer of 10 to 12 μm, and therefore the toner layer becomes too thin at the convex portions on the surface. By the way, when the surface roughness is Rz 3 μm or less, beautiful printing without white spots was obtained.

Next, the toner layer thickness on the developing roller 4 is
FIG. 6 shows that stabilization is achieved by applying a bias voltage to the doctor blade 5. , In FIG. 4, the development bias
The relationship between the potential difference (ΔV) from (-300 V in the figure) and the toner layer thickness is shown. The toner layer thickness is 10 to 12 μm.
In order to do so, a bias voltage (ΔV) of 100 V or more is required between the doctor blade 5 and the developing roller 4 as shown in FIG.

Next, FIG. 5 shows the relationship between the potential difference (ΔV) between the developing roller 4 and the doctor blade 5 and the print density (optical density). Therefore, as is clear from the results of this experiment, the potential difference between the developing roller 4 and the doctor blade 5 must be at least 100 V or more.

Next, FIG. 6 and FIG. 7 show the relationship between the number of printed sheets in continuous printing, the fog density on the drum, and the print density on the paper. Conventional doctor blade (Fig. 9 in this example)
As described above, in the case where the front end of the doctor blade 5 is L-shaped}, the fog increases as the number of printed sheets increases, but the toner layer forming method according to the present invention (here, the doctor blade by press working When used), the print density is stable, and the fog on the photosensitive drum 1 does not increase, and the effect of the present invention is exhibited.

The fog is, as shown in FIG. 6 (a),
As the toner charge amount decreases due to running (increase in the number of printed sheets) (for example, 12.9 μc / g → 7.1 μc / g),
External additives of toner (additives for increasing fluidity, charge amount, for example, silica) decrease (experimental data shows that silica decreases by about 30%), and as a result, As shown in FIG. 6 (b), the toner layer thickness increases from 12 μm to 15.3 μm, and the doctor blade 5
The effective R increases due to the retention of the toner at the tip of the photosensitive drum 1, and as shown in FIG.
Also, the fog on the paper is increased. The fog here means a phenomenon that the toner cannot be completely wiped off on the photosensitive drum 1 and becomes a thin stain, or a similar phenomenon on the paper.

Therefore, in the present invention, the doctor blade 5
The shape of the tip is made flat by the above-mentioned press working or the like so that the retention of the toner at the tip of the doctor blade 5 can be eliminated and the toner layer can be formed without depending on the fluidity of the toner. Figure 6 (d) shows that
The behavior at the tip of the docker blade 5 is schematically shown. With the flat plate structure, the toner flow is improved, and the increase in fog can be suppressed.

FIGS. 7 (a) and 7 (b) show experimental examples of changes in the toner layer thickness and the print density with the increase in the number of printed sheets. It can be seen that the print density is stable by using the doctor blade 5 of the present invention.

Further, as shown in FIG. 7 (c), the transition of the fog density on the photosensitive drum 1 was also found to be stable, and the flattening effect of the tip of the doctor blade 5 according to the present invention is remarkable. Can be said to be

In the above embodiment, the stirring section for stirring the toner provided in the toner tank, the developing roller for forming the toner layer on the roller surface and developing the latent image formed on the photosensitive drum, A doctor blade for regulating the layer thickness of a toner layer in an electrophotographic printing apparatus including a collecting roller that collects toner after development of a developing roller and a layer thickness regulating unit that controls the thickness of the toner layer of the developing roller. Where R of the portion formed of a flat plate and in contact with the developing roller is R ≧ 0.5t with respect to the plate thickness t, and the formed portion of R is 1 to 5 times the toner particle diameter φ _t. Yes, and when forming the toner layer, it has been described as a basic principle to apply a bias voltage between the doctor blade and the developing roller, the above embodiment is just one example, the method of molding the doctor blade. (Pre Processing, drawing with a whetstone: polishing with a whetstone) corresponding to various conditions that are the above-mentioned basic principles, such as the thickness t of the doctor blade, the roughness of the surface of the developing roller, the friction coefficient, and the doctor blade The relationship between the distance L between the tip and the developing roller and the toner particle diameter φ _t , or the material for making the friction coefficient of the developing roller a predetermined value, the material of _the resin coat, the thickness of _the resin coat
_Or means for tape polishing the resin coating, or the means or the like for applying a predetermined bias voltage between the doctor blade and the developing roller, one or, of course, may be constituted by combining a plurality appropriately That is.

[0028]

As described above, according to the present invention, since the toner layer can be stably formed even when the toner deteriorates or the number of printed sheets increases, it is possible to perform printing with high print density and less fog. Moreover, since the doctor blade can also be formed by pressing or drawing (polishing) with a grindstone, there is an advantage that the pressing force can be reduced at low cost.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

FIG. 2 is a diagram showing an embodiment of the present invention (No. 1).

FIG. 3 is a diagram showing an embodiment of the present invention (part 2).

FIG. 4 shows an embodiment of the present invention (part 3).

FIG. 5 is a diagram showing an embodiment of the present invention (No. 4).

FIG. 6 is a diagram showing an embodiment of the present invention (No. 5).

FIG. 7 is a diagram showing an embodiment of the present invention (No. 6).

FIG. 8 is a diagram (part 1) illustrating a conventional electrophotographic printing apparatus.

FIG. 9 is a diagram for explaining a conventional electrophotographic printing device (Part 2).

[Explanation of symbols]

1 photosensitive drum 2 rotating brush 3 non-magnetic one-component developing device, developing device 4 developing roller 5 doctor blade 6 collecting roller 7 agitator 8 paddle 9 toner bottle 10 outer 11 transfer roller 12 fixing device, fixing roller

Claims (33)

[Claims] 1. A stirring unit provided in a toner tank for stirring toner, a developing roller for forming a toner layer on the roller surface to develop a latent image formed on a photosensitive drum, and a developing roller after the developing roller. It comprises a collecting roller for collecting the toner and a layer thickness regulating portion for controlling the thickness of the toner layer of the developing roller. The toner layer thickness regulating portion has a doctor blade for regulating the layer thickness of the toner layer, which is a flat plate. in it is formed, and R of the portion in contact with the developing roller, with respect to the plate thickness t, a R ≧ 0.5 t, and, 1-5 forming part of R is the toner particle diameter phi _t
An electrophotographic printing apparatus, characterized in that a bias voltage is applied between the doctor blade and the developing roller when forming a toner layer. 2. The electrophotographic printing apparatus according to claim 1, wherein the doctor blade has a plate thickness t of 0.08 to 0.25 mm. 3. The electrophotographic printing apparatus according to claim 1, wherein the doctor blade has a doctor blade shape manufactured by press working. 4. The doctor blade according to claim 1, wherein the doctor blade is manufactured by press working and the clearance has a plate thickness t.
0.1 to 0.4 times the electrophotographic printing device. 5. The doctor blade according to claim 1, wherein when the doctor blade is manufactured by press working, and the smooth surface of the doctor blade is brought into contact with a developing roller, the tip of the smooth surface (R surface) of the doctor blade is the developing roller. And the distance L
Electrophotographic printing apparatus which is a 0.5 to 5 times the toner particle diameter phi _t. 6. The doctor blade according to claim 1, wherein the doctor blade is manufactured by press working, and when the smooth surface of the doctor blade is brought into contact with the developing roller, the smooth surface of the doctor blade (R
Distance L tip surface) are separated from the developing roller is 0.5 5 times the toner particle diameter phi _t, and, between the doctor blade and the developing roller, adding at least developing bias voltage higher than the bias voltage An electrophotographic printing device characterized by the above. 7. The doctor blade according to claim 1, wherein the doctor blade is manufactured by press working, and when the smooth surface of the doctor blade is brought into contact with the developing roller, the smooth surface of the doctor blade (R
Electrophotographic printing, characterized in that the distance L at which the front end of the surface) is away from the developing roller is 0.5 to 5 times the toner particle diameter φ _t , and the surface roughness of the developing roller is Rz 3 μm or less. apparatus. 8. The doctor blade according to claim 1, wherein the doctor blade is manufactured by press working, and when the smooth surface of the doctor blade is brought into contact with a developing roller, the tip of the smooth surface (R surface) of the doctor blade is the developing roller. And the distance L
0.5 5 times the toner particle diameter phi _t, and electrophotographic printing apparatus, wherein the friction coefficient of the developing roller is 0.3 or more. 9. The blade according to claim 1, wherein the doctor blade is manufactured by press working, and when the smooth surface of the doctor blade is brought into contact with the developing roller, the tip of the smooth surface (R surface) of the blade is separated from the developing roller. The distance L is 0.5 to 5 times the toner particle diameter φ _t , the surface roughness of the developing roller is Rz 3 μm or less, and the friction coefficient of the developing roller is 0.3 to 2. Electrophotographic printing device. 10. A developing roller for forming a toner layer using a doctor blade manufactured by the press working according to claim 1, wherein the surface roughness of the developing roller is R.
An electrophotographic printing apparatus comprising a developing roller having a surface of the developing roller coated with a predetermined resin and tape-polished so as to have a thickness of 3 μm or less. 11. A developing roller for forming a toner layer using a doctor blade manufactured by the press working according to claim 1, wherein a friction coefficient of the developing roller is 0.
An electrophotographic printing apparatus comprising a developing roller having a resin coating thickness of 3 to 10 μm for coating the surface of the developing roller so as to have a thickness of 3 to 2. 12. A developing roller for forming a toner layer by using a doctor blade manufactured by the press working according to claim 1, wherein the surface roughness of the developing roller is R.
Since z is 3 μm or less and the coefficient of friction is 0.3 to 2,
The thickness of the resin coat coated on the surface of the developing roller is 3
An electrophotographic printing apparatus having a developing roller having a surface of the resin coat of which is about 10 μm and whose surface is tape-polished. 13. A developing roller for forming a toner layer using a doctor blade manufactured by the press working according to claim 1, wherein the surface roughness of the developing roller is R.
Since z is 3 μm or less and the coefficient of friction is 0.3 to 2,
The thickness of the resin coat coated on the surface of the developing roller is 3
An electrophotographic printing apparatus comprising: a developing roller having a thickness of ˜10 μm, a developing roller material being NBR rubber, and the tape-polished resin coating material being urethane resin. 14. A developing roller for forming a toner layer using a doctor blade manufactured by the press working according to claim 1, wherein a friction coefficient of the developing roller is 0.
The electrophotographic printing apparatus is characterized in that the material of the developing roller is NBR rubber and the surface of the developing roller is an ultraviolet-treated developing roller so as to have a size of 3 to 2. 15. The doctor blade according to claim 1, wherein a doctor blade manufactured by the press working and a developing roller having a surface roughness Rz of 3 μm or less are used, and a bias of at least a developing bias voltage or more is provided between the doctor blade and the developing roller. An electrophotographic printing device characterized by applying a voltage. 16. The doctor blade according to claim 1, wherein a doctor blade manufactured by the press working and a developing roller having a friction coefficient of 0.3 to 2 are used, and at least a developing bias voltage or more is applied between the doctor blade and the developing roller. An electrophotographic printing apparatus characterized by applying a bias voltage. 17. The doctor blade according to claim 1, wherein a doctor blade manufactured by the press working and a developing roller having a surface roughness Rz of 3 μm or less and a friction coefficient of 0.3 to 2 are used, and between the doctor blade and the developing roller. An electrophotographic printing apparatus, wherein a bias voltage of at least a developing bias is applied to the device. 18. The electrophotographic printing apparatus according to claim 1, further comprising a doctor blade formed into a predetermined shape by polishing with a grinding stone having a predetermined shape when the doctor blade is manufactured. 19. The doctor blade according to claim 1, wherein the doctor blade is manufactured by polishing a grindstone, and a portion having R ≧ 0.5t and a portion having a plate thickness are smoothly connected with an R shape. An electrophotographic printing apparatus comprising: 20. The doctor blade according to claim 1, wherein the doctor blade is manufactured by polishing a grindstone, and a portion of R ≧ 0.5t and a portion having a plate thickness are smoothly connected to each other in an R shape. An electrophotographic printing apparatus comprising a doctor blade having a radius r <0.5t. 21. The doctor blade according to claim 1, wherein the doctor blade is manufactured by polishing a grindstone, and when the smooth surface of the doctor blade is brought into contact with a developing roller, the tip of the smooth surface (R surface) of the doctor blade is developed. An electrophotographic printing apparatus, wherein a distance L apart from the roller is 0.5 to 5 times the toner particle diameter φ _t . 22. The doctor blade according to claim 1, wherein the doctor blade is manufactured by polishing a grindstone, and when the smooth surface of the doctor blade is brought into contact with a developing roller, the tip of the smooth surface (R surface) of the doctor blade Electrophotographic printing characterized in that the distance L between the rollers is 0.5 to 5 times the toner particle diameter φ _t , and a bias voltage of at least the developing bias voltage is applied between the doctor blade and the developing roller. apparatus. 23. The doctor blade according to claim 1, wherein the doctor blade is manufactured by polishing a grindstone, and when the smooth surface of the doctor blade is brought into contact with a developing roller, the tip of the smooth surface (R surface) of the doctor blade is developed. The distance L away from the roller is
An electrophotographic printing apparatus, characterized in that it is 0.5 to 5 times the toner particle diameter φ _t , and the surface roughness of the developing roller is Rz 3 μm or less. 24. The doctor blade according to claim 1, wherein the doctor blade is manufactured by polishing a grindstone, and when the smooth surface of the doctor blade is brought into contact with a developing roller, the tip of the smooth surface (R surface) of the doctor blade and the developing roller are developed. The distance L between the rollers is
0.5 5 times the toner particle diameter phi _t, and electrophotographic printing apparatus, wherein the friction coefficient of the developing roller is 0.3 or more. 25. The doctor blade according to claim 1, wherein the doctor blade is manufactured by polishing a grindstone, and when the smooth surface of the doctor blade is brought into contact with a developing roller, the tip of the smooth surface (R surface) of the doctor blade The distance L between the rollers is
An electrophotographic printing apparatus, characterized in that it has a toner particle diameter φ _t of 0.5 to 5 times, a developing roller surface roughness of Rz 3 μm or less, and a developing roller friction coefficient of 0.3 to 2. 26. In the developing roller according to claim 1, wherein the toner layer is formed by using a doctor blade manufactured by polishing a grindstone, the surface roughness of the developing roller is Rz 3 μm.
An electrophotographic printing apparatus comprising a developing roller having a surface coated with a resin and tape-polished so as to have a thickness of m or less. 27. The developing roller according to claim 1, wherein the toner layer is formed by using a doctor blade manufactured by polishing a grindstone, and the friction coefficient of the developing roller is 0.3 to 2
Therefore, the electrophotographic printing apparatus is characterized in that the surface of the developing roller is coated with resin, and the developing roller is provided with the resin coating thickness of 3 to 10 μm. 28. The developing roller according to claim 1, wherein a toner layer is formed by using a doctor blade manufactured by polishing a grindstone, and the developing roller has a surface roughness of Rz 3 μm.
The surface of the developing roller is coated with a resin so that the friction coefficient is 0.3 to 2 and the thickness of the resin coating is 3 to 3
An electrophotographic printing apparatus having a developing roller having a thickness of 10 μm and a surface of the resin coat tape-polished. 29. The present roller according to claim 1, wherein the developing roller has a surface roughness of Rz 3 μm, in which the toner layer is formed by using a doctor blade manufactured by polishing a grindstone.
In order to have a friction coefficient of 0.3 to 2 and below, the surface of the developing roller is resin-coated, and the thickness of the resin coating is 3
An electrophotographic printing apparatus comprising: a developing roller having a thickness of ˜10 μm, the surface of the resin coat being tape-polished, the developing roller material being NBR rubber, and the resin coating material being urethane resin. 30. The present roller according to claim 29, wherein a toner layer is formed by using a doctor blade manufactured by polishing a grindstone, and the friction coefficient of the developing roller is 0.3 to 2
Therefore, the material of the developing roller is NBR rubber,
An electrophotographic printing apparatus comprising a developing roller having the surface of the NBR rubber treated with ultraviolet rays. 31. When a toner layer is formed using a doctor blade manufactured by polishing a grindstone and a developing roller having a surface roughness Rz of 3 μm or less, at least a developing roller is provided between the doctor blade and the developing roller. An electrophotographic printing apparatus characterized by applying a bias voltage higher than the bias voltage. 32. When a toner layer is formed by using a doctor blade manufactured by polishing a grindstone and a developing roller having a friction coefficient of 0.3 to 2, at least between the doctor blade and the developing roller. An electrophotographic printing apparatus characterized by applying a bias voltage higher than a developing bias voltage. 33. The doctor blade according to claim 1, wherein when a toner layer is formed using a doctor blade manufactured by polishing a grindstone and a developing roller having a surface roughness Rz of 3 μm or less and a friction coefficient of 0.3 to 2. An electrophotographic printer, wherein a bias voltage of at least a developing bias voltage is applied between the developing roller and the developing roller.