JPH0477771A - Electrophotographic developing device - Google Patents

Abstract

PURPOSE:To set the linear pressure of both regulation members to be weak and to reduce the abrasion of a developer supply member and a supply regulation member by providing the supply regulation member which regulates and electrostatically charges developer supplied to the developer supply member and the regulation member which regulates and electrostatically charges the developer supplied to a developer carrier. CONSTITUTION:By giving the difference of potential between a coating roll 24 and a supply roll 23, toner 25 is carried to the supply roll 23, regulated and electrostatically charged by a supply regulating blade 27. Next, by controlling an electric field and the ratio of a circumferential speed between the supply roll 23 and a developing roll 22, the required toner 25 is carried to the developing roll 22 from the supply roll 23 by the splashing thereof. Then, by the regulating blade 29, the toner 25 carried to the developing roll 22 is electrostatically charged to a desired value and the layer thickness of the toner is more uniformized extending over the whole area in the width direction thereof. At this time, the linear pressure of the blade 29 is set to be about <=100g/cm and the abrasion of the developing roll 22 or the regulating blade 29 is reduced.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an electrophotographic developing device.

(Prior Art) Conventionally, in an electrophotographic recording device, a charged photosensitive drum is irradiated with a light source to form an electrostatic latent image on its surface, and toner is attached to the electrostatic latent image for development. After that, the toner image is transferred to a recording medium.

The above-mentioned development is performed by a developing device disposed opposite to the photosensitive drum.

FIG. 2 is a sectional view of a conventional electrophotographic developing device. In the figure, 1 is a toner storage tank, 2 is a non-magnetic one-component toner stored in the l/toner storage tank 1, and 3 is a stirring member. , 4 is a toner carrier, that is, a developing roll, which rotates at a predetermined speed, and 5 is a coating roll, which is a porous elastic roll that is in contact with the developing roll 4 and rotates in the same direction.

The developing roll 4 and the application roll 5 are frictionally charged due to their relative rotation, and the toner 2 adheres to the surface of the developing roll 4 (1). The toner 2 rubs against the surface of the regulating blade 6 made of an elastic thin metal plate and the developing roll 4 to form a toner layer of a predetermined thickness, and the toner layer is applied to the surface of the photosensitive drum 7. It is supplied and becomes a visible image.

The toner 2 remaining on the surface of the developing roll 4 is collected into the toner storage tank 1 by the collection blade 8.
(JP 60-53975, JP 62170987
(see publication).

In this case, since the non-contact development method is used in which the toner 2 on the developing roll 4 is flown onto the surface of the photosensitive drum 7 which is opposed to each other with a gap, the toner 2 does not come into direct contact with the non-image area. Clear images without fog can be obtained. On the other hand, it is not possible to increase the distance between the photosensitive drum 7 and the developing roll 4, which is approximately 100 to 300 microns, and the toner layer to be formed on the developing roll 4 must be made thinner accordingly.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional electrophotographic developing device, the toner 2 is lightly attached to the developing roll 4 without being overwhelmed, and the toner 2 has an appropriate amount of charge. However, since the proportion of the oppositely charged toner 2 (positively charged toner in reverse development) is small, it is necessary to reduce wear on the developing roll 4 and the regulation blade 6. The thickness of the upper toner layer cannot be reduced.

That is, the only parameters that can be considered for controlling the toner layer thickness and toner charge amount are the surface roughness of the developing roll 4 and the linear pressure of the regulating blade 6, but if the surface roughness of the developing roll 4 is 1 μnRz or less In this case, the sensitivity of the toner conveyance amount to the surface roughness becomes high, and variations in surface roughness during manufacturing cannot be absorbed. Furthermore, in the case of a surface that is rough to some extent, it is difficult to thin the toner layer even if the linear pressure of the regulating blade 6 is increased to its elastic limit.

Therefore, the surface roughness of the developing roll 4 is 1 to 5 μmR.
z, which increases the manufacturing cost of the valve.

Furthermore, if the linear pressure of the regulating blade 6 is increased, the wear of the developing roll 4 and the regulating blade 6 increases, and the toner 2 is subjected to strong force and sticks to the developing roll 4.
Not only does the density of the recorded image decrease and image quality deteriorate, but the amount of charge on the toner 2 increases, and a large electric field is required to fly the toner 2 from the developing roll 4 to the photosensitive drum 7. Become. Therefore, if the developing bias potential is set higher than the surface of the photosensitive drum 7 to force the toner 2 to fly, background fog will occur.

On the other hand, if the linear pressure of the regulating blade 6 is weakened, the toner layer becomes thicker, and the friction between the toner 2 and the regulating blade is reduced, and the toner charge amount becomes small and uneven, resulting in reverse polarity]
・The proportion of ner increases.

As described above, it is difficult to make the toner 2 a thin layer, keep the toner charge amount within an appropriate range, and reduce the ratio of toner of opposite polarity.

The present invention solves the above-mentioned problems of the conventional electrophotographic developing device, makes the toner a thin layer, keeps the toner charge amount within an appropriate range, and reduces the proportion of toner of opposite polarity. The purpose is to provide developing equipment.

(Means for Solving the Problems) For this purpose, the electrophotographic developing device of the present invention includes an electrostatic latent image carrier that rotates while forming an electrostatic latent image, and a microscopic image carrier that forms an electrostatic latent image and rotates. A developer carrier that rotates while supporting a non-magnetic one-component developer, which is opposed to each other at a distance; The developer supply member has a developer supply member that supplies a developer to the body, and an application member that rotates in contact with the developer supply member and supplies the developer to the developer supply member, and the developer is supplied to the application member, The developer is supplied to the electrostatic latent image carrier via the developer supply member and the developer carrier.

Further, a regulating member that regulates and charges the developer supplied to the developer carrying member, and a supply regulating member that regulates and charges the developer supplied to the developer supplying member are provided. . A power source is provided to apply an electric field between the developer carrying member and the developer supplying member, and the toner is caused to fly from the developer supplying member to the developer carrying member.

The developer that does not contribute to development on the developer carrier is scraped off by a scraping member.

The linear pressure of the above regulating member and the above supply regulating member is both 10
It may also be from g/cm to 10h/c+a.

(Function) According to the present invention, the electrostatic latent image bearing member rotates while forming an electrostatic latent image as described above, and the electrostatic latent image bearing member is opposed to the electrostatic latent image bearing member with a minute interval, and is not A developer carrier that rotates while carrying a magnetic one-component developer, and a developer that rotates while facing the developer carrier with a minute gap and supplies the developer to the developer carrier. It has a supplying member, and a coating member that rotates in contact with the developer supplying member and supplies the developer to the developer supplying member, and the developer is supplied to the coating member, the developer supplying member, and the developer carrier. is supplied to the electrostatic latent image carrier via the electrostatic latent image carrier. In this case, the toner is moved by flying between the developer supply member and the developer carrier, and between the developer carrier and the electrostatic latent image bearing member 1u.

Further, a regulating member that regulates and charges the developer supplied to the developer carrying member, and a supply regulating member that regulates and charges the developer supplied to the developer supplying member described in 1. The developer that does not contribute to development on the developer carrier is scraped off by a scraping member.

The linear pressure of the above regulating member and the above supply regulating member is both 10
It may be from g/cIll to 100 g/cm.

By setting the linear pressure of the regulating member weak in this way,
It is possible to eliminate wear of the developer supply member and the supply regulation member, and furthermore, it is possible to prevent toner from sticking to the developer supply member.

Further, since an electric field is generated between the developer carrier and the developer supply member, only negatively charged toner can be selectively transported to the developer carrier. That is, oppositely charged developer is not supplied to the developer carrier.

Furthermore, since the developer on the developer carrier is once again rubbed by the regulating member pressed against the developer carrier, the charging of the developer is made uniform at an appropriate ratio, and records with good resolution and no background fog can be obtained. I can do it. At this time, the linear pressure of the regulating member is set to be weak, so that wear of the developer carrier and the regulating member and toner sticking to the developer carrier are prevented.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of an electrophotographic developing apparatus showing an embodiment of the present invention.

In the figure, 21 is an electrostatic latent image carrier, ie, a photosensitive drum, and an electrostatic latent image is formed on its surface through a charging process and an exposure process (not shown).

Reference numeral 22 denotes a developer carrier, that is, a developing roll, which is opposed to the photosensitive drum 21 with a small distance therebetween, and rotates in the direction of the arrow.

Reference numeral 23 denotes a developer supply member, that is, a supply roll, which is opposed to the developing roll 22 at a small distance, and rotates in the direction of the arrow. Further, 24 is a coating member, that is, a coating roll, which is placed in contact with the supply roll 23 and rotates in the same direction.

Then, the non-magnetic one-component toner 25 is conveyed to the surface of the developing roll 22 by the friction. 26 is a coating roll 24
This is a coating power supply that generates an electric field between the supply roll 23 and the supply roll 23 and causes the toner 25 to adhere from the coating roll 24 to the supply roll 23.

Reference numeral 27 denotes a supply regulating member made of a plate-shaped elastic body, that is, a supply regulating blade, whose abdominal surface is brought into pressure contact with the supply roll 23 to regulate the toner layer pressure and charge the toner layer. Reference numeral 28 denotes a power supply, which generates an electric field between the developing roll 22 and the supply roll 23 and causes the toner 25 on the developing roll 22 to fly from the supply roll 23 . Reference numeral 29 denotes a regulating member, that is, a regulating blade, whose abdominal surface is brought into pressure contact with the developing roll 22 to further charge the toner 25 conveyed to the developing roll 22.

30 is a developing power supply, which connects the developing roll 22 and the photosensitive drum 2.
1, an electric field is generated between the developing roll 22 and the photosensitive drum 2.
1 Make Hetner 25 fly. Further, 31 is a collection blade that collects residual 1-toner 25 remaining on the surface without contributing to the development of the electrostatic latent image into the toner storage tank 32, and the toner 25 in the toner storage tank 32 is removed from the toner storage tank 32. They are placed in pressure contact to prevent leakage.

Reference numeral 33 denotes a scraping member, that is, a scraping plate, which is disposed so that its tip abuts against the developing roll 22, and is configured to scrape off the toner 25 remaining on the developing roll 22 and return it to the storage tank 32.

The developing roll 22 and the supply roll 23 are made of aluminum pipes with a mirror finish (diameter 20mm, surface roughness 3μmRz).
After high-temperature alkali etching, hard alumite treatment is used. The coating roll 24 is a stainless steel shaft coated with a conductive sponge roll.

The toner 25 is made by dispersing a carbon blank pigment and a polarity control agent in various thermoreversible resins such as styrene resin, and has an average particle size of about 101 nm. The supply regulating blade 27 and the regulating blade 29 are made of stainless steel (Sus304-csp) and have a thickness of 2.
00 μm, the collecting blade 21 removes the polyester film, and the scraping blade 33 removes the polyester film with a thickness of 2 μm.
s (JISA rubber hardness 70'') urethane rubber is used.

Next, the operation of the electrophotographic developing apparatus of the present invention will be explained.

First, the toner 25 in the toner storage tank 32 is
4 to the coating roll 24. Then, the toner 25 attached to the application roll 24 is charged by the frictional force between the application roll 24 and the supply roll 23. Further, an electric field is generated by creating a potential difference between the application roll 24 and the supply roll 23, and the toner 25 is
is conveyed to the supply roll 23, regulated and charged by the supply regulation blade 27.

At this time, in the conventional toner layer forming method, unless the linear pressure of the supply regulating blade 7 is set to 150 g/cm or more, reversely charged toner will cause fogging of the recorded image and a reduction in resolution. In the case of this embodiment, the linear pressure of the regulating blade 29 is set to about 100 g/cva or less, and the developing roll 22
This reduces the wear of the regulating blade 29 and the developing roll 22.
This prevents the toner 25 from sticking. However, if it is too weak, supply regulation and charging will not be possible, so at least 10g
/cm or more is necessary. Note that the amount of toner 25 conveyed to the supply roll 23 at this time is greater than the amount of toner 25 conveyed to the development area because the linear pressure of the supply regulating blade 27 is weakened.

The electric field between the supply roll 23 and the development roll 22,
Toner 25 is conveyed to the developing roll 22 in an amount necessary for the developing area calculated by the circumferential speed ratio (usually about 0.9 cm/cj considering development and transfer efficiency).

That is, in order to control the magnitude of the electric field, the supply roll 2
3 and the developing roll 22, or both rolls 22
．． What is necessary is to increase the potential difference applied between 23 and 23. however,
In order to prevent the thickness of the toner layer on the supply roll 23 from coming into contact with the development roll 22, the distance between the supply roll 23 and the development roll 220 must be at least about 100 μ-. Furthermore, if the potential difference between both rolls 22 and 23 is increased, the gap between the supply roll 23 and the developing roll 22 can be widened, but since a discharge phenomenon occurs,
It needs to be below the level of

Furthermore, by slowing down the peripheral speed of the supply roll 23,
The amount of toner 25 that flies to the developing roll 22 can be adjusted. Note that in this embodiment, the supply roll 23
and the circumferential speed of the developing roll 22 are equal.

As described above, since the supply roll 23 and the developing roll 22 are in a non-contact state, only the negatively charged toner 25 is conveyed to the developing roll 22. The toner 25 conveyed to the developing roll 22 is charged to a desired value by the regulating plate 29, and the thickness of the toner layer is made more uniform over the entire width direction. At this time, the linear pressure of the regulating blade 29 is set to be weaker than that of the supply regulating blade 27 to prevent the toner 25 from accumulating near the contact area between the developing roll 22 and the regulating blade 29. After that, the undeveloped toner 25 is collected by the collection blade 31.
The toner 25 returns to the toner storage tank 32 through the toner storage tank 32, and all of the toner 25 on the developing roll 22 is scraped off by a scraping blade 33. Without this scraping blade 33, the toner 25 remaining on the developing roll 22 would be removed from the supply roll 22.
3, electrical discharge occurs and the surfaces of the supply roll 23 and the developing roll 22 are damaged.

In the developing device having the above configuration, the linear pressure of the supply regulating blade 27 is 70 g/cm, and the linear pressure of the regulating blade 29 is 50 g/cm.
/cm, the distance between the surface of the supply roll 23 and the surface of the developing roll 22 is 0.3 rtm, and the voltage of the supply power source 2B is 900.
ν, power supply of coating type 1fI26 to 200V, development voltage tJ3
0 voltage is 700V, and the surface potential of the photosensitive drum 21 is 18V.
00V, process speed (in this experiment, where the developing roll 22 and the photosensitive drum 21 are at the same speed, the photosensitive drum 2
The image was printed on 10,000 sheets of A4 size recording paper at a moving speed of 100 mm/s. As a result, when the image was visually viewed, the scattering of the toner 25 and the generation of agglomerated toner were so small that they could be virtually ignored, and a very good image could be obtained.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

For example, in this embodiment, the rotation direction of the supply roll 23 and the rotation direction of the developing roll 22 are the same, but the supply roll 23
The direction of rotation of the developing roll 22 may be reversed. However, the rotation direction of the application roll 24 is the same as that of the supply roll 2.
The supply regulating blade 27 is rotated in the same direction as the rotation direction of 3.
It is installed between the upstream side of the contact point between the coating roll 24 and the supply roll 23 and the downstream side of the point of closest approach between the supply roll 23 and the developing roll 22.

(Effects of the Invention) As described in detail above, according to the present invention, there is provided a regulating member that regulates and charges the developer supplied to the developer carrier, and a developer supplied to the developer supply member. Since a supply regulating member is provided that regulates and charges the developer, by setting the linear pressure of the regulating member and the supply regulating member weakly, wear of the developer supplying member, developer carrier, and supply regulating member can be eliminated. Furthermore, it is possible to prevent the toner from sticking to the developer supply member and the developer carrier.

Further, since an electric field is generated between the developer carrier and the developer supply member, only negatively charged toner can be selectively transported to the developer carrier. That is, oppositely charged developer is not supplied to the developer carrier.

Furthermore, since the developer on the developer carrier is once again rubbed by the regulating member pressed against the developer carrier, the charging of the developer is made appropriate and uniform, and records with good resolution and no background fog can be obtained. I can do it.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an electrophotographic developing device showing an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional electrophotographic developing device. 21... Photosensitive drum, 22... Developing roll, 23...
... supply roll, 24 ... application roll, 25 ... toner, 26 ... application power supply, 27 ... supply regulation blade, 28 ... supply power supply, 29 ... regulation blade, 3
0...Development power supply, 3I...Collection blade, 32...
- Toner storage tank, 33... scraping blade. Characteristics Applicant: Oki Electric Industry Co., Ltd.

Claims (2)

[Claims] (1) (a) An electrostatic latent image carrier that rotates while forming an electrostatic latent image; (c) a developer supplying member that rotates while supporting the developer; and (c) a developer supply that rotates while facing the developer carrier at a small distance and supplies the developer to the developer carrier. (d) an application member that rotates in contact with the developer supply member and supplies developer to the developer supply member; and (e) regulates the developer supplied to the developer carrier. (f) a supply regulating member that regulates and charges the developer supplied to the developer supply member; and (g) an electric field between the developer carrier and the developer supply member. and (h) a scraping member for scraping off developer that does not contribute to development on the developer carrier. (2) The electrophotographic developing device according to claim 1, wherein the linear pressure of the regulating member and the supply regulating member are both 10 g/cm to 100 g/cm.