JPH0519632A - 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. 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 a developer amount regulating body having rigidity and magnetism, which is pressed to the sleeve 2, is provided. After the surface of the sleeve 2 is worked so that the roughness may be Rz value 0.2-1.5mum by sand blast processing by irregular small particles first, it is worked so that the surface roughness may be within the range of Rz value 5-10mum by the sand blast processing by globular large particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of mixing magnetic carrier particles and toner particles in an electrophotographic copying machine.
The present invention relates to a developing device for developing 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 composed of a magnetic carrier and a toner is used. This developing device has a developing sleeve, which is a cylindrical developer carrier, which is rotatably supported and has a magnet roller formed of a magnet body having a plurality of magnetic poles inside. Toner particles are attached to the surface of the developing sleeve. The developed magnetic carrier is held and conveyed to the developing area for triboelectrification control of toner particles. Although it is used, it is also suitable for non-contact development in which the development is carried out in non-contact with the surface of the image bearing member, so that it is used despite the need to control the amount of toner particles with respect to carrier particles.

In the above-mentioned magnetic brush development type developing apparatus for non-contact development, in order to perform uniform development without density unevenness, the layer thickness of the developer conveyed to the developing area on the developing sleeve is small, And it is necessary to make it uniform. This is especially important in non-contact development.

Conventionally, the layer thickness of the developer has been regulated by a fixing regulation plate which has been used for a long time. However, there is a limit to the mechanical attachment 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, it was difficult to obtain a uniform and uniform thin layer by this method. However, various developer layer thickness regulating devices other than the fixed regulating 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-like layer thickness regulating member is provided and a magnetic body is disposed on the back surface thereof, and the attracting force of a fixed magnet body provided inside the developer carrying member indirectly regulates the regulating plate. It is disclosed that the abdomen or the bent edge is pressed to control the layer thickness.

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

[0007]

In order to solve the above-mentioned conventional drawbacks, the present applicant has developed using a rod-shaped 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 softens due to frictional heat in the developing process, and the toner is apt to fuse to the developing sleeve, which reduces the amount of developer conveyed to the developing area, lowers the density of copy images, and cleans the developing sleeve. There was a problem such as causing scratches on the scraper.

The present invention solves the above problems, no toner fusion occurs on the developing sleeve, and no scraping occurs on the scraper for cleaning the developing sleeve.
An object of the present invention is to provide a developing device capable of performing development without density unevenness by regulating the layer thickness of the developer on the developing sleeve to a constant value.

[0010]

SUMMARY OF THE INVENTION The above object is to provide a two-component developer containing a magnetic carrier and a toner, which has a magnet body fixed inside and has a rigidity for carrying the developer on the surface. A developer carrier and a rod-shaped developer amount made of a material having rigidity and magnetism, which is pressed against the developer carrier so as to face the magnet body and regulates the amount of the developer carried on the developer carrier. In a developing device equipped with a regulating body, the surface of the developer carrying body is roughened to have a JIS Rz value of 0.2 to 1.5 μm by sandblasting with irregular particles, and then the sandblasting with spherical large particles is used.
It is achieved by a developing device characterized by being processed to have a z value of 5 to 10 μm.

[0011]

1 is a cross-sectional view of one embodiment 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 a charger (not shown) and an exposure device, 2 is a developing sleeve which is a developer carrier made of a non-magnetic material, and 3 is the inside of the developing sleeve 2. The developing roller 2 and the magnet roller 3 constitute a developer carrying carrier, which is a magnet roller fixedly provided on the surface of the magnet roller and having a plurality of N and S magnetic poles 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 having a rigidity of 10 ⁴ Kg / cm ² or more, which is provided to regulate the amount, is a housing of the developing device, and 6 is a cylindrical rod 4.
Is a spring material for allowing the developer D to be conveyed despite the pressing of the developer sleeve 2 and the developing sleeve 2, and the cylindrical rod 4 has a constant load with the developer D intervening with respect to the developer sleeve 2. Pressed with. Reference numerals 7 and 8 are first and second stirring members, 9 is a supply roller, 10 is a scraper for scraping off and cleaning the developer on the surface of the developing sleeve 2 that has passed through the developing zone 12, and 11 is a stirring partition plate.

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 arrow direction, and is developed as the upper developer D via the supply roller 9. 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 pass over the stirring partition plate 11 whose upper edge is slanted downward in the drawing and move to the first stirring member 7 side, where it is conveyed to the front side of the drawing by its thrust force. By the mixing action of the toner and the carrier in the above, a uniform developer D 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 arrow direction.

The developer D used in this embodiment is as follows. As the carrier, a magnetic carrier which is 50 wt% of fine-grained ferrite dispersed in a resin, has a weight-average particle size of 50 μm, has a magnetization intensity of 30 emu / g, and has a resistivity of 10 ¹⁴ Ωcm or more and is subjected to heat spheroidization. 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, 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 cylindrical rod 4 is made of stainless steel having a diameter of 6 mm and having rigidity and magnetism. The developing sleeve 2 is made of a non-magnetic material such as non-magnetic stainless steel or aluminum, and the surface thereof is not subjected to the conveyance of the developer D and is subjected to the following treatment in order to prevent toner fusion. did. First, the surface roughness is 0.2-1.5μ in terms of JIS Rz value, after being subjected to treatment such as sandblasting using irregular particles.
Fine irregularities are formed to m. After that, in order to remove minute projections generated when the fine irregularities are formed, sandblasting with spherical large particles is performed to obtain the Rz.
The value was 5 to 10 μm. By this process, the minute protrusions are reduced, the toner is not fused, and the developer D is sufficiently conveyed to achieve uniform development.

As shown in FIG. 1, the magnet roller 3 is composed of magnets of 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 peeling of the developer D, one pole is omitted to make 11 poles, and the magnetic flux is contained in the developing sleeve 2 in a fixed state, and the magnetic flux at the pressing position of the cylindrical rod 4 on the surface of the developing sleeve 2. 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 0.7 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 thus changed changes with the rotation of the developing sleeve 2, the magnetic brush moves with the developing sleeve 2 while vibrating, and
It passes through the gap between 12 photosensitive drums 1 stably and smoothly,
At this time, a uniform developing effect is given to the surface of the photoconductor drum 1, and stable development with a high toner density is possible. At this time, in order to further prevent the occurrence of fogging and improve the developing effect, a bias voltage having an alternating component that vibrates in the developing sleeve 2 is applied between the developing sleeve 2 and the base body of the photosensitive drum 1 which is grounded by a bias power source (not shown). Has been done. The bias voltage is preferably a superimposed voltage of DC voltage and AC voltage. The DC component prevents fogging from occurring and the AC component gives vibration to the magnetic brush to improve the developing effect. A voltage of 50 to 600 V, which is substantially equal to or higher than the non-image portion potential, is used for the direct current voltage component, and a frequency of 100 Hz to 10 KHz, preferably 1 to 5 KHz is used for the alternating voltage component. 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 in the developing area 12, has a high carrier ratio and is conveyed by the developing sleeve 2 and separated and collected by the scraper 10.
It is again mixed with the developer D having a high toner ratio.

In this way, the toner was not fused on the surface of the developing sleeve 2, and the development was carried out so as to obtain a high density and high quality image without unevenness.

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

(Comparative Test) The inventors prepared (A), (B) and (C) in which the surface of the developing sleeve was subjected to the following three types of surface treatments together with the above-mentioned Example (D).

(A) Roughness of JIS R _Z value of 0.2 to 0.5 μm is processed by sand blasting with amorphous particles.

[0023] (B) processing the roughness of 1~3μm at R _Z value of JIS by sandblasting by irregular particles.

(C) After being processed to have a roughness of 1 to 3 μm according to JIS R _Z value by sandblasting with irregular-shaped particles, buffing is performed to a roughness of 0.3 to 0.5 μm.

The developing sleeves (A) (B) (C) (D)
The test was conducted under the same conditions as those of the present example except that they were replaced with those described above.

(D) After sandblasting with irregular-shaped particles to a roughness of JIS R _Z value of 0.2 to 1.5 μm, sandblasting with spherical large particles, 5 to 10
Processed to a roughness of μm. (Example) As a result, the following evaluations were obtained.

(A) The transportability of the developer was slightly inferior to that of the example, but was relatively good. However, when a check was performed after continuous copying of about 8000 copies, toner fusion was recognized in the vicinity of the cylindrical rod 4. In addition, there was a change in the amount of developer conveyed.

(B) The developer transportability was better than in the examples. However, when a check was performed after continuous copying of about 5000 copies, remarkable fusion of toner was found on the entire surface of the developing sleeve and in the vicinity of the cylindrical rod 4. In addition, the scraper 10 also had a crack. (C) The developer transportability was poor as compared with the examples, and only development with low image density was performed.

(D) No abnormality was found after continuous copying of 8,000 copies.

[0030]

As described above, in the developing device of the present invention provided with the developer amount regulator having rigidity and magnetism, the surface of the developing sleeve is provided with fine irregularities by sandblasting with irregular small particles. After that, sandblasting with spherical large particles was performed. As a result, the toner is not fused to the surface of the developing sleeve, the scraper for cleaning the surface of the developing sleeve does not become messed up, and the layer thickness of the developer on the developing sleeve is regulated to a constant value to prevent uneven density. The excellent effect that development can be performed was obtained.

[Brief description of drawings]

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

[Explanation of symbols]

 1 photoconductor drum (image bearing member) 2 developing sleeve (developer bearing member) 3 magnet roller 4 cylinder rod (developer amount regulating member) 6 spring material 10 scraper 12 developing area 14 holder D developer N, S magnetic pole

Claims (1)

Claim: What is claimed is: 1. A developer carrying body containing a two-component developer comprising a magnetic carrier and a toner, having a magnet body fixed inside, and carrying the developer on the surface thereof. A rod-shaped developer amount regulating member made of a material having rigidity and magnetism, which is pressed against the developer bearing member so as to face the magnet body and regulates the amount of the developer carried on the developer bearing member. In a developing device for developing in a non-contact manner with an image carrier, the surface of the developer carrier is subjected to JI
After the roughness of S of Rz is 0.2 to 1.5 μm, it is sandblasted with large spherical particles to give Rz of 5 to 10
A developing device characterized by being processed to a roughness of μm.