JPH0519631A - Developing device - Google Patents

Abstract

PURPOSE:To provide a developing device by which development without the unevenness of density is accomplished by regulating the layer thickness of developer on a developing sleeve, which is carried toward a developing area, so that it may be constant and where toner is not welded on the developing sleeve and a developer amount regulating body. CONSTITUTION:In the developing device which performs non-contact development by using two-component developer D consisting of magnetic carrier and toner, a magnetic roller 3 is provided in the developing sleeve 2, and a columnar bar 4 being the developer amount regulating body having rigidity and magnetism, which is pressed to the sleeve 2, is provided. The surface of the sleeve 2 is worked to be a mirror surface after executing sand blast processing, and the surface of the columnar bar 4 is coated with a material which is excellent in releasing property and has low frictional property and heat resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combination of magnetic carrier particles and toner particles in an electrophotographic copying machine.
The present invention relates to a developing device that develops an electrostatic latent image or a magnetic latent image in a non-contact state using a component developer.

[0002]

2. Description of the Related Art Conventionally, in electrophotographic copying machines and the like,
A magnetic brush developing type developing device using a two-component developer is used. This developing device has a developing sleeve, which is a rotatably supported cylindrical developer carrier, having a magnet roller made of a magnet body having a plurality of magnetic poles inside, and toner particles are attached to the surface of the developing sleeve. The developed magnetic carrier is held and conveyed to the development area for triboelectrification control of the toner particles. Although it is widely used as a developing device for performing non-contact development, it is also suitable as non-contact developing for developing in non-contact with the surface of an image carrier.

In the above-mentioned magnetic brush developing type developing device, in order to perform uniform development without density unevenness, it is necessary to make the layer thickness of the developer conveyed to the developing area on the developing sleeve uniform. is there. This is particularly important in non-contact development, together with the fact that the developer layer is formed thin.

Conventionally, the layer thickness of the developer has been regulated by a fixing regulation plate that has been used for a long time, but there is a limit in the mechanical mounting accuracy between the developer carrier and the fixing regulation plate, and the layer thickness is limited. The lower limit is about 0.3 mm. Moreover, in this method, it was difficult to obtain a thin layer during non-contact development. However, various developer layer thickness control devices other than the fixed control plate have been devised to meet the purpose of obtaining a uniform thin layer. In particular, examples suitable for a developing device using a two-component developer include (a) a thin layer on a developing sleeve suitable for non-contact development as disclosed in JP-A-62-191868 and JP-A-62-191869. The technical means for forming the developer layer is disclosed. This is because the tip of the elastic plate supported by the support member is directed in the upstream direction of the movement of the developer on the developing sleeve, and the elastic plate is pressed onto the developing sleeve, so that the elastic plate adheres to the developing sleeve. By controlling the layer thickness of the developer containing the magnetic carrier and the toner to be conveyed, the developer layer thickness can be easily set to a thin layer with higher accuracy than the conventional regulation means.

(B) Further, JP-A-61-189582 and JP-A-6-189582.
In the developing device described in JP-A 2-75563, a solid plate-shaped layer thickness regulating member is provided and a magnetic body is arranged on the back surface thereof, and the regulation plate is indirectly controlled by the attractive force of a fixed magnet body provided in the developer carrying body. It is disclosed that an abdomen or a bent edge is pressed to control the layer thickness.

However, the above-mentioned proposal (a) has drawbacks that it is not suitable for mass production because the durability is short and strict precision is required for mounting the elastic plate. Also (b)
In the above, there is a drawback in that a pressure variation is likely to occur due to a change in the distance between both magnet bodies, and a uniform layer thickness cannot be obtained.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional drawbacks, the present applicant has developed using a rod-like developer amount regulating member having rigidity and magnetism as described in JP-A No. 2-50184. We are proposing equipment. This proposal makes it possible to obtain a uniform developer layer thickness on the developing sleeve.

However, in accordance with the recent demand for high image quality in color copying, as toner particles are made smaller and fixing at low temperature is performed, in the thin layer forming section by the developer amount regulating body of the developer, the thin layer forming section is formed. The toner is softened by the frictional heat in the above, and the toner is apt to be fused to the developing sleeve and the developer amount regulating member, and the amount of the developer conveyed to the developing area is reduced, resulting in a decrease in the density of the copy image. Also, toner adhesion to the developing sleeve,
Although a scraper for cleaning is installed to prevent the carrier from adhering, there is also a problem that the blade is messed up if it is exposed too much due to the surface condition of the sleeve.

The present invention solves the above-mentioned problems, and toner fusion does not occur on the developing sleeve and the developer amount regulating member.
An object of the present invention is to provide a developing device capable of performing development without unevenness in density by regulating the layer thickness of the developer on the developing sleeve to a constant value without causing scratches on the cleaning scraper on the surface of the developing sleeve. .

[0010]

SUMMARY OF THE INVENTION The above object is to provide a developer carrying member having a magnet body fixed inside and having a rigidity for carrying a developer on the surface thereof, and the developing body facing the magnet body. It is provided with a rod-shaped developer amount regulating body made of a material having rigidity and magnetism that regulates the amount of the developer carried by the developer carrying body and regulates the amount of the developer carried by the developer carrying body without contact with the image carrying body. In the developing device, the surface of the developer carrying member is provided with fine irregularities, and then post-processing such as sand blasting with spherical large particles or mirror finishing by superfinishing is performed, and the developer amount regulating member The pressing unit is achieved by a developing device characterized by being coated with a material having a low coefficient of friction, releasing property and heat resistance.

[0011]

【Example】

(Embodiment 1) FIG. 1 is a sectional view of Embodiment 1 of the device of the present invention, in which 1 is rotated in the direction of the arrow and has a photosensitive layer such as Se, CdS or an organic photoconductor on the surface. , A photoconductor drum, which is an image carrier on the surface of which an electrostatic latent image is formed by an unillustrated charger and an exposure device, 2 is a developing sleeve which is a developer carrier made of a non-magnetic material, and 3 is a developing sleeve 2. The developing roller 2 and the magnet roller 3 are a magnet roller which is fixed inside and has a plurality of N and S magnetic poles on the surface in the circumferential direction.
The developing sleeve 2 is fixed to the magnet roller 3
It is rotatable with respect to and rotates in the direction of the arrow in the figure. The N and S magnetic poles of the magnet roller 3 are usually 500 to 1,500.
It is magnetized to have a Gaussian magnetic flux density, and the magnetic force forms a layer of the developer D, that is, a magnetic brush, on the surface of the developing sleeve 2 as described above. 4 is the height of the magnetic brush,
A cylindrical rod, which is a cylindrical rod-shaped developer amount regulating member made of a magnetic material and having a rigidity of 10 ⁴ Kg / cm ² or more, which is provided to regulate the amount. 5 is a housing of the developing device, 6 is a cylindrical rod 4
Is a spring material for allowing the developer D to be conveyed despite the fact that the developer D and the developing sleeve 2 are pressed. Pressed with. 7 and 8 are first and second stirring members, 9 is a supply roller, 10 is a scraper for scraping and cleaning the developer adhering to the surface of the developing sleeve 2 that has passed through the developing zone 12, and 10 is a stirring partition plate. is there.

The toner replenished in the apparatus is sufficiently agitated and mixed with the carrier by the first agitating member 7 and the second agitating member 8 which rotate in the direction of the arrow, and is developed through the supply roller 9 as the upper developer D. It is sent to the sleeve 2.

The first stirring member 7 and the second stirring member 8 are screw-shaped members having a left-handed helix angle which rotate in mutually opposite arrow directions, and are pushed backward by the thrust of the second stirring member 8. The conveyed toner and carrier successively move over the agitating partition plate 11 whose upper edge is slanted downward in the drawing toward the first agitating member 7 side, and are conveyed to the front side of the drawing by the thrust thereof, By the mixing action of the toner and the carrier in the above, a uniform developer D that has been triboelectrically charged is formed, and is adhered in layers on the peripheral surface of the developing sleeve 2 by the supply roller 9 that is sponge-like and rotates in the direction of the arrow.

The developer D used in this embodiment is as follows. As the carrier, a magnetic carrier obtained by heat spheroidizing with fine weight ferrite dispersed in resin at 50 wt% and having a weight average particle size of 50 μm, a magnetization intensity of 30 emu / g and a resistivity of 10 ¹⁴ Ωcm or more is used. Styrene / acrylic resin (Haimer up110 manufactured by Sanyo Kasei) 100 for toner
5 parts by weight, consisting of 10 parts by weight, carbon black (MA-100 manufactured by Mitsubishi Kasei) and 5 parts by weight nigrosine,
Using the non-magnetic particles obtained by the pulverization and granulation method of No. 3, the development was performed under the condition that the toner ratio of the developer D in the 9 parts of the supply roller was 5 wt% with respect to the carrier.
The average charge amount of the toner was 20 μC / g.

In this apparatus, the developing sleeve 2 is made of non-magnetic material such as non-magnetic stainless steel or aluminum.
The surface thereof was subjected to the following treatment in order to prevent the toner D from being fused without deteriorating the transportability of the developer D. First, JI is performed after sandblasting using irregular particles.
Fine irregularities having an Rz value of S of about 0.5 to 3 μm are formed. After that, sand blasting with spherical large particles is performed so that the roughness of the surface becomes a JIS Rz value of 3 to 15 μm, or polishing processing by superfinishing, or mirror finishing using # 8000 rab film, etc. The post-processing was performed.

The cylindrical rod 4 is made of stainless steel having a diameter of 6 mm and having rigidity and magnetism, and the surface thereof is sandblasted to form fine irregularities of about 1 μm in terms of JIS Rz value, and then a primer layer is provided to reduce friction. Fluorine resin (PTFE) with heat resistance and good releasability is 10-100μm
Thickness or coated with polyphenylene sulphide (PPS) paint.

As shown in FIG. 1, the magnet roller 3 is composed of magnets having 12 poles of equal magnetic poles in which N poles and S poles are alternately arranged at equal intervals, but a repulsive magnetic field is generated at a portion in contact with the scraper 10. In order to facilitate the separation of the developer D, one pole is omitted to form 11 poles, and the magnetic flux is included in a fixed state in the developing sleeve 2 and is contained in the developing sleeve 2 at the pressing position of the cylindrical rod 4. The density was 600 gauss. A load of 2 to 6 gf / mm is applied to the cylindrical rod 4 at a position facing the magnetic pole of the magnet roller 3, whereby the cylindrical rod 4 is pressed by the developing sleeve 2 and is attracted and pressed by the magnetized magnetic force. By increasing the pressure, the developing sleeve 2 comes into close contact with the developing sleeve 2 uniformly, and a uniform and even amount of the developer D conveyed of about 7 to 9 mg / cm ² was obtained.

In the developing device as described above, when the surface distance of the developing sleeve 2 to the photosensitive drum 1 is set to 0.5 mm and the electrostatic latent image on the photosensitive drum 1 is developed, it is formed on the surface of the developing sleeve 2. Since the magnetic flux density on the surface of the magnetic brush changes with the rotation of the developing sleeve 2, the magnetic brush moves with the developing sleeve 2 while vibrating, and stably and smoothly passes through the gap with the photosensitive drum 1, At that time, a uniform developing effect is given to the surface of the photoconductor drum 1, and stable development of high toner density is possible.
At that time, a bias voltage having a vibrating AC component is applied to the developing sleeve 2 in order to further prevent fogging and improve the developing effect. The bias voltage is preferably a superimposed DC voltage and an AC voltage, and the DC component prevents fogging, and the AC component gives vibration to the magnetic brush to improve the developing effect. It should be noted that a voltage of 50 to 600 V, which is approximately equal to or higher than the non-image portion potential, is usually used for the DC voltage component and 100 for the AC voltage component.
Frequencies of Hz to 10 KHz, preferably 1 to 5 KHz are used. As a result, only the toner in the developer D on the developing sleeve 2 selectively flies toward and is attached to the electrostatic latent image on the photosensitive drum 1.

The developer D, which has consumed the toner component, has a high carrier ratio, is conveyed by the developing sleeve 2, is separated and collected by the scraper 10, and is mixed again with the developer D having a high toner ratio.

In this way, the developing sleeve 2 and the cylindrical rod 4 were developed so that the toner was not fused and a high-quality image with high density and evenness was obtained.

The present invention can also be used for reversal development. In that case, the DC voltage component is set to a voltage which is substantially equal to or lower than the reception potential of the non-image background portion of the photosensitive drum 1 by 50 to 100V.

(Embodiment 2) FIG. 2 is a cross-sectional view of an essential part showing another embodiment of the present invention, in which the same parts as in FIG. In this embodiment, the same one as in Embodiment 1 is used, but the developing sleeve 2 is rotated in the same direction in the portion facing the photosensitive drum 1. In this case, the cylindrical rod 4 as the developer amount regulating body is arranged at the position shown in FIG. The same developing sleeve 2 as used in Example 1 was used (diameter 30 mm), and the surface of the developing sleeve 2 was subjected to sand blasting using irregular particles to form fine irregularities with an R _Z value of about 1 μm. Then, sandblasting with spherical large particles was applied to obtain an uneven surface having an R _Z value of 7 μm. The magnet roller 3 used has a magnetic flux density of 700 Gauss on the sleeve surface and 8 poles. The cylindrical rod 4 was made of a magnetic material having a diameter of 7 mm, which had been treated in the same manner as in Example 1 and then applied with Teflon coating of 50 μm. It was held between 24 and. The parts of the present embodiment that are not shown in FIG. 2 are configured similarly to the parts of the first embodiment described with reference to FIG. The cylindrical rod 4 is a magnet roller 3 fixed in the developing sleeve 2.
The magnet is magnetized by the magnetic field generated by the magnet, and a pressing force is obtained by its magnetic attractive force. The cylindrical rod 4 has a magnetic attraction force evenly distributed in its longitudinal direction, and the developing sleeve 2 has a magnetic attraction force.
By pressing, it was possible to obtain a very uniform developer layer thickness without toner fusion. Further, even if continuous copying was carried out for a long time, no toner fusion was observed on the cylindrical rod 4 or in the vicinity thereof.

(Embodiment 3) FIG. 3 is a sectional view showing Embodiment 3, and the same portions as those in FIG. 1 are designated by the same reference numerals. This embodiment is an example in which a nonlinear elastic body is used as the pressing member.

The developing sleeve 2 is a cylinder made of non-magnetic stainless steel with an outer diameter of 20 mm, which rotates at 250 rpm in the direction of the arrow.
By sandblasting after super finish to 2μm with R _Z value was a surface state of removing the fine irregularities. Inside the developing sleeve 2, there is a fixed magnet roller 3 with 11 poles, and the maximum magnetic flux density on the surface of the developing sleeve 2 is kept at 600 gauss. The cylindrical rod 4 having rigidity and magnetism is pressed against the developing sleeve 2 at a position facing the magnetic pole of the magnet roller 3. The cylindrical rod 4 was treated in the same manner as in Example 1 and had a PPS coat of 10 μm in diameter and a diameter of 6 m.
Holder 34 attached to the housing 5 with a cylindrical rod of m
The lateral movement is restricted by the non-linear elastic member 36 in the pressing direction. This nonlinear elastic member 36
For example, as shown in FIG. 4, for example, PORON, which is a foamed urethane foam having a characteristic that the repulsive force varies little with respect to the amount of bending in the usage range U, is used. The non-linear elastic member 36 is formed into a plate shape and bonded to two places of the holder 34, and the cylindrical rod 4 is pressed at two points. 2-4gf / m under such conditions
When the pressing force of m was set, the toner fusion did not occur, and the amount of the two components regulated to the developer amount of 7 to 10 mg / cm ² was uniformly distributed over the entire axial direction of the developing sleeve 2. The developer D is transported. Further, in this embodiment, even if no adjusting portion is provided for regulating the amount of developer D to be conveyed,
The above good development conditions were set and maintained. Further, even if continuous copying was carried out for a long time, the toner was not fused to the cylindrical rod 4 or its vicinity.

[0025]

As described above, in the developing apparatus of the present invention, after the surface of the developing sleeve is provided with fine irregularities by sandblasting or the like, the post-processing such as sandblasting with spherical large particles or mirror finishing is performed. . Further, the surface of the developer amount regulating member was coated with a material having a good releasability, low friction and heat resistance. As a result, the toner is not fused to the developing sleeve and the developer amount regulating member, and the scraper for cleaning the developing sleeve surface is not messed up, and the developer layer thickness on the developing sleeve is regulated to a constant value. As a result, it is possible to obtain the excellent effect that it is possible to perform development without density unevenness.

[Brief description of drawings]

FIG. 1 is a sectional view showing a developing device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a second embodiment of the developing device of the present invention.

FIG. 3 is a sectional view showing a developing device according to a third embodiment of the invention.

FIG. 4 is a graph showing a relationship between a bending amount and a load for an example of a non-linear elastic body.

[Explanation of symbols]

1 Photoconductor drum (image carrier) 2 Development sleeve 3 magnet roller 4 Cylindrical rod (developer amount regulator) 6 Spring material 10 scraper 12 Development area 14,24,34 holders 26 Pressing leaf spring 36 Non-linear elastic member D developer N, S magnetic pole

Claims (3)

[Claims] 1. A developer carrying body having a magnet body fixed inside and having a rigidity for carrying a developer on a surface thereof, and a developer carrying body which is pressed against the developer carrying body facing the magnet body, In a developing device provided with a rod-shaped developer amount regulating body made of a material having rigidity and magnetism for regulating the amount of the developer carried on the developer carrying body, the surface of the developer carrying body is made fine by sandblasting or the like. The developing device is characterized by being subjected to post-processing such as sandblasting with large spherical particles or mirror finishing by superfinishing after providing such unevenness. 2. The developing device according to claim 1, wherein the fine irregularities have a surface roughness R _{Z of} 0.5 to 3 μm on a sand blast of irregularly shaped particles. 3. The pressing portion of the developer amount regulator is heat resistant,
The developing device according to claim 1, wherein the developing device is coated with a material having a low coefficient of friction and releasability.