JPS63144374A - Developing device - Google Patents

Abstract

PURPOSE:To obtain a high quality free from an uneven image density and fogging by stirring efficiently a developer, by providing a developer stirring means in the vicinity of a developer stirring and carrying means and a magnetic field generating means. CONSTITUTION:A stirring means 18 is provided with plural pieces of plate- shaped blades 18b in the radial direction on the peripheral surface of a shaft 18a, provided adjacently to a developer carrying and circulating pole S3 in the vicinity of upper and lower screws 8, 9 being carrying means, and a magnet roller 72 being a magnetic field generating means, and rotated in the direction as indicated with an arrow. A toner replenished into a developer storing part 4 from a toner replenishing port 16 is stirred and carried by the screw 9 of the lower side and mixed and dispersed, combined with a developer on a sleeve 71, which has ended the development of a latent image holding body A and has been returned and carried into the developer storing part 4, and mixed and stirred by the stirring means 18. That is to say, the developer is mixed sufficiently, and the concentration of the developer which is brought to coating onto the sleeve 71 is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Industrial Field of Application] (The invention relates to a developing device that develops a latent image on the surface of a latent image carrier using a dry developer.

[Conventional technology]

Hitherto, various types of electric WI image developing apparatuses have been proposed and put into practical use, but all of them have advantages and disadvantages.

For example, in a developing method using a two-component developer, when an image area of a latent image is developed with the developer applied to the developing roller E, the toner in the developer is mixed with the developer applied to the developing roller. I only use a few percent of it. This is extremely inefficient considering the structure of the developing device.

This is because, in order to obtain a predetermined development density, it is safe to apply a constant amount of developer onto the developing roller each time the developing roller rotates, with a uniform toner concentration. For this reason, the structure of the developing device has become larger and more complicated.

Of course, attempts have been made to improve the development efficiency in this type of development system as well. For example, the present applicant
No. 60, No. 55-133058, No. 56-705
He proposed an improved method in 60 Gin and put it into practical use (Canon model NP8500). According to this, it was possible to increase the development density and to improve the development efficiency. However, it still has almost 10% in the image area.
In order to achieve a development efficiency close to 0%, it is not possible to achieve a development efficiency close to 0%.

In terms of development efficiency - L, the L component development method is better than 2.
Superior to component development methods. Among them, the developing method or developing device of JP-A-54-43037, which was previously filed by the present applicant, is "developing roller (sleeve)" 2.10
A thin toner layer of 0 pL or less F is formed, and the toner coated on the sleeve can be used for development in the image area with a development efficiency close to 100%. For this reason, the structure of the developing device could be downsized and simplified for practical use.

This is less than 100g of toner t'1 on the developing roller.
This was a success because it was possible to form a layer. However, this development method uses magnetic toner as the toner, and in order to make magnetic toner magnetic, a magnetic substance must be added to the toner, which is used to heat-fix the developed image transferred to the transfer paper. Poor fixing properties during printing, due to the addition of magnetic material to the developer itself (magnetic material is usually black)
There are problems such as poor color reproduction.

For this reason, as a method for forming a single layer of non-magnetic toner, there is a method of using a cylindrical brush made of soft bristles like a beaver's t-shirt and coating the toner with a shield, or a method of applying toner to a cylindrical brush with soft hair like a beaver's t-shirt, or
A method has been proposed in which a developing roller made of H-fiber is coated with a doctor blade.

However, when an elastic blade is used as a doctor blade for the F-HhM1 brush, it is possible to regulate the toner value, but uniform application is not achieved, and simply rubbing the fiber brush on the developing roller does not allow the toner to be applied properly. 1? Since the '7' market was not allocated, there were problems such as fogging.

Therefore, the present applicant has created a developing device that is completely different from the various conventional systems described above, using non-magnetic toner and magnetic particles, and providing a magnetic particle restraining member opposite to the toner carrier to control the direction of movement of the surface of the toner carrier.

A magnetic brush of magnetic particles is formed upstream of the magnetic particle restraining member by the magnetic force of the magnetic field generating means, the magnetic brush is restrained by the magnetic particle restraining member, and small magnetic particles containing non-magnetic toner are formed on the toner carrier surface. We have already proposed a method for forming a thin brush-like magnetic adsorption layer (Japanese Unexamined Patent Application Publication No. 58-14
No. 3380). Then, the toner carrier and the latent image carrier are made to face each other, and the gap between the latent image carrier and the toner carrier is increased so that the toner thickens (toner carrier By applying an alternating electric field, the Ppi
A method for obtaining a positive or negative non-magnetic toner developed image corresponding to a PPf image pattern on the surface of an image carrier has been put to practical use.

This is because in the development area, a thin brush-like magnetic absorbing layer of magnetic particles containing non-magnetic toner on the toner retaining member side is formed to be longer than the gap length between the latent image retaining member and the toner retaining member. 1 is elongated by the magnetic field applied to the developing section and rubs against the surface of the latent image carrier, and the non-magnetic toner contained in the brush-like magnetic adsorption layer of the magnetic particles is moved between the toner carrier and the latent image carrier. By generating the reciprocating movement, the latent image on the latent image holding body side becomes positive with non-magnetic toner corresponding to the latent image pattern.
1! It is an image that is developed as an i-image or as a negative.

As a result, the developing device-V can be extremely thick, compact, and simple, and a color developed image with good color properties can be obtained using non-magnetic toner. In particular, a solid image is obtained during two-component magnetic brush rubbing development.

[Problem that the invention seeks to solve]

- Among the various developing devices mentioned above, the last one is particularly recommended as it has excellent developing characteristics, but it also requires consistently high developed image properties such as high quality, high density, and good gradation. There is a desire to develop something that lasts long and has high durability and reliability that can be applied to high-speed image forming apparatuses.

[j
target

2. Structure of the Invention [Means for Solving the Problems] The present invention uses the developer i and 1 made of toner and magnetic particles as the developer 11! In a developing device that develops the surface of a latent image holding member, the magnetic field contained in the developer stirring/transporting means and the developer carrying member arranged at −FT with respect to the developer carrying member in the developing container. It is characterized in that a stirring means is disposed near the generating means.

[For production]

By providing means for stirring the developer in the vicinity of the developer stirring/transporting means disposed above and below the developer carrying member and the magnetic field generating means included in the developer carrying member in the developer container, the developer can be stirred. is efficiently stirred, making it possible to obtain high quality images without uneven density or fog.

[χ Example]

FIG. 1 is a cross-sectional view of a developing device showing an embodiment of the present invention. In FIG.
It is an electrophotographic photoreceptor, static recording dielectric material, etc. in the form of a belt or sheet, and is driven in plane movement at a predetermined speed in the direction of the arrow.
A latent image is formed by an image forming process device (not shown), and developed as a visible image by a developing device B.

In the developing device B, reference numeral 1 denotes a developer container, and the interior thereof is separated by a partition wall 2 into a storage section 3 for replenishing non-magnetic toner, and a developer storage section (developer container) for storing a developer made of non-magnetic toner and magnetic particles. It is divided into 4 parts. The toner stored in the toner storage unit 3 and the developer in the developer storage unit 4 are omitted from the diagram for convenience.

The replenishment toner in the toner storage section 3 is sequentially transported toward the partition walls 2 by rotating the pair of toner transport members 6I and 62, and is replenished into the developer storage section 4 from the toner replenishment section 116. .

The above toner conveying member 6I/6. are arranged on the front half side (near the partition wall 2) and the rear half side of the toner storage section 3, and in this example, both are crank-shaped rods made by bending a bar, and the shaft portions 6a, 6a are It is rotated around the center in the direction of the arrow.

7 is a non-magnetic developing sleeve as a developer carrying member disposed in the developer storage section 4, and the left oblique side surface of the development sleeve 71 is exposed to the outside through an opening provided in the developer storage section 4. The developing device B is positioned and held by the supporting member so that the external surface 7 of the developing sleeve 71 faces the latent image holder A surface with a predetermined small gap therebetween. . The opposing portion a between the latent image holder A and the developing sleeve 71 is a developing section.

Reference numeral 72 denotes a multi-pole magnet roll as a magnetic field generating means inserted and built into the developing sleeve 7□. The roll of this example has N! It is a permanent magnet roll in which six magnetic poles, N3, S, and -N3, are magnetized alternately as N poles and S poles at predetermined position intervals.

This magnet roll 72 is fixedly supported at both ends and does not rotate, and the outer developing sleeve 7□ is driven to rotate around the fixed roll 72 in the direction of the arrow at a predetermined circumferential speed.

8 and 9 are the developing sleeve 7,
Screw shafts serving as developer stirring and conveying means are arranged vertically and vertically in parallel with the arrows, and are each driven to rotate in the direction of the arrow.

Reference numeral 17 denotes a developer circulation regulating member provided between the upper and lower parts 7, 8, and 9, and 10 and 14 indicate developer provided on the circumferential surface of the developing sleeve 71, facing the upper and lower parts of the developer storage section 4. The circulation area designating member 11/13 is a magnetic member for preventing the stored developer from flowing and leaking toward the latent image holder A from the gap between the bottom surface of the developer storage section 4 and the lower surface of the developing sleeve 7□. (Magnet) 12 has a predetermined small gap on the upper surface side of the developing sleeve 71 with its lower side against the north surface of the developing sleeve in order to regulate the layer thickness of the developer formed on the peripheral surface of the developing sleeve 71. These are non-magnetic blades arranged facing each other.

15 is a sensor that detects the concentration of the developer (mixing ratio of toner and magnetic particles) in the developer storage section 4; the output of this sensor is input to a control circuit (not shown), and +iii toner conveying member 6□ in toner storage section 3 ・
The rotational drive of 62 is controlled.

the multi-pole magnet roll 7 as magnetism generating means;
Regarding each magnetic pole, the N1 pole is located as a developer application rod at a position substantially facing the non-magnetic blade 12 as a developer layer thickness regulating member.

The N2 pole is a developing pole and is located at a position facing the developing section a, that is, the surface A of the latent image carrier. The Sl pole is located at an open position between the N1 pole and N2J4i as a developer transport pole. S2
The pole and the N3 pole serve as developer leakage prevention rods, and are located at positions facing the aforementioned magnetic member 13-11 provided on the bottom surface of the developer storage section 4, respectively. The S3 pole serves as a developer transport circulation pole and is located at an open position between the N1 pole and the N3 pole.

In the figure, 18 is a stirring means which is the main part of the present invention.
In the illustrated embodiment, as shown in FIG. 2, a plurality of flat blades 18b are provided on the circumferential surface of a shaft 18a in the radial direction.

The stirring means 18 is provided close to the above developer transport circulation pole S3 in the vicinity of the upper F screws 8 and 9 as developer stirring and transport means and the magnet roll 72 as a magnetic field generating means. Rotate in the direction of the arrow in Figure 1. Further, the stirring means 18 preferably includes the developing sleeve 7I.
A position within 2 to 3 mm from the surface of the container is provided so that it can be stirred.

When the developing device rL is in operation, the developing sleeve 71. Screw 8
9 are each rotated at a predetermined speed, and an alternating voltage is applied between the developing sleeve 7 and the latent image holder A by a bias power source S.

By the rotation of the screw 8119, the developer in the developer storage portion 4 is agitated upward in the longitudinal direction of the developing sleeve 71, and a substantially uniform mixing ratio of toner and magnetic particles is obtained near the developing sleeve 7I. Unevenness in each portion of the developing sleeve 71 in the longitudinal direction is removed.

The screws 8 and 9 rotate in the directions of the arrows, so that the developer in the developer storage section 4 is separated from the developer near the upper screw 8 and the developer near the lower screw 9, respectively. The helical blades of the two lower screws 8 and 9 are arranged in opposite directions so as to be conveyed in the opposite direction to the longitudinal direction.

The movement of the developer in the developer storage section 4 on the cross section of the developer storage section is caused by the rotation of the developing sleeve 71, the screw 8.
9, the magnetic field of the magnet roll 72, and the developer 1m regulating member 17. Due to the presence of the circulation area designating members 10 and 14, the stirring means 18, the frictional force between the developing sleeve 7I and the developer, the gravity of the developer, etc., a cyclical fluid movement as shown by the white arrow in FIG. 1 is achieved. And this cyclic flow movement of the developer,
Sufficient tripo is imparted to the toner by stirring or the like due to the flow along the screws 8 and 9.

The developer in the vicinity of the surface area of the developing sleeve 71 facing into the developer reservoir of the developer storage section 4, that is, the developer consisting of magnetic particles and non-magnetic toner, is magnetized by the magnetic force of the magnet roll 72 in the sleeve 7I. The developer is adhered and held as a brush adsorption layer, and is conveyed toward the developer circulation regulating member 10 as the developing sleeve 7I rotates, and the magnetic brush of the developer is restrained by passing through the surface F of the member 10.

Next, it reaches the non-magnetic blade 12 position, and in the process of passing through the non-magnetic blade 12 position δ, the layer thickness is regulated, and it becomes a thin layer of developer consisting of a small amount of magnetic particles and non-magnetic toner, and passes through the developing section atl. .

In the process of passing through the developing section a, the developing sleeve 7 is
, the brush-shaped magnetic particles contained in the developer layer on the side are formed longer than the facing gap length between the surface A of the latent image carrier and the developing sleeve 71, or the latent particles are expanded by the electric field of the developing section a. By rubbing the image holder A side and reciprocating the toner between the sleeve 71 side and the latent image holder A side, the toner corresponds to the latent image pattern on the latent image holder A side. The toner transfers and adheres to the surface of the latent image holding member A, and the toner development of the latent image on the surface A of the latent image holding member is performed sequentially.

The developer layer on the side of the developing sleeve 7I that has been subjected to development and has passed through the developing section a is held as it is on the disk surface of the sleeve 7 by the magnetic field of the magnetic poles S2 and N3 within the developer storage section 4 due to the subsequent rotation of the developing sleeve 71. The developer is transported back and mixed with the developer in the developer storage section 4 again.

As the toner in the developer in the developer storage section 4 is consumed in developing the latent image, the mixing ratio with the magnetic particles gradually decreases. The degree of the decrease is detected by the sensor 15, and the detected information is input to the control circuit (not shown). When the degree of decrease reaches a predetermined allowable lower limit, the signal causes the toner conveying members 61 and 62 in the toner storage section 3 to rotate. As a result, the toner in the toner storage section 3 is sequentially introduced into the developer storage section 4 from the toner replenishment port 16 and replenished.

The replenished toner is taken into the developer in the developer storage unit 4 and mixed uniformly and quickly throughout the developer. This toner replenishment causes the toner portion of the developer in the developer storage unit 4 to be mixed. When the sensor 15 detects that the ratio has increased to a predetermined allowable increase, the toner transport member 6. -62's rotational drive is stopped. As a result, the mixing ratio of the toner to the magnetic particles of the developer in the developer storage section 4 is always kept substantially constant.

That is, the toner supplied into the developer storage section 4 from the toner supply port 16 is stirred and conveyed into the existing developer by the lower screw 9 while moving in the axial direction, and is mixed and dispersed. Then, the developer moves over the developing sleeve 7, and its circulation is regulated between the circulation regulating member 17, the magnetic pole S3, and the stirring member 18, and after developing the latent image holder A, it enters the developer storage section 4. The sleeve 7, the developer on the upper side, and the developer conveyed by the screw 9 are mixed and stirred by the stirring means 18, and some of the developer flows in the direction of the screw 8 and some of the developer on the upper side. The layer thickness is regulated by flowing toward the non-magnetic blade 12 side through the lower surface of the circulation regulating member IO, and is held on the developing sleeve 7□ and conveyed to the developing section a, where it is used for developing a latent image.

The developer conveyed in the direction of the screw 8 is conveyed in the axial direction of the screw 8 in the opposite direction to the screw 9, and a portion of the developer is conveyed toward the sleeve and a portion toward the screw 9. When the developer is moved in the axial direction by the screw 8, the developer on the surface of the sleeve 7 is made almost uniform in the axial direction.

The circulation regulating member 17 regulates the circulating conveyance of the developer near the magnetic pole S3 on the sleeve 7 side.

It serves as a guide plate for screw 8 or 9,
It also contributes to stabilizing the agitation and conveyance of the developer. Further, on the opposite side of the sleeve 7 □, there is a gap between the developer container l and the sleeve 7 □, which also serves to guide a portion of the developer circulated by the screw 8 toward the screw 9 .

As mentioned above, the stirring means 18 is located near the S3 pole, and by rotating in the direction of the arrow in the figure, it separates the developer that has been used for development and whose toner concentration has decreased, and the developer that has been kept at a constant concentration and that has not yet been developed. It was confirmed that mixing with the developer that has not been subjected to this process was performed efficiently. In other words, as is clear from the movement of the developer (white arrow) in Figure 1, the developer that has gathered at the S3 pole due to magnetic force or gravity is stirred all at once, and the mixing of the developer is improved. This was carried out sufficiently, and the concentration of the developer coated on the sleeve 7 could be stabilized.

C. Detailed Description of the Invention As described above, the present invention provides a stirring means in the vicinity of the developer stirring/transporting means disposed above and below the developer carrying member and the magnetic field generating means included in the developer carrying member. By providing this, the developer on the sleeve, which has a reduced toner concentration after development, and the developer in the developer storage section, whose developer concentration is kept approximately constant, are efficiently mixed, and the developer is effectively mixed. It has become possible to obtain high-quality developed images with consistent image density without image unevenness using a compact device.

[Brief explanation of the drawing]

:iS1 is a cross-sectional view of an embodiment of the developing device of the present invention, and FIG. 2 is a perspective view of a stirring member. A is the WI (holding body), B is the developing device, 7I is the developer carrying member (developing sleeve), and 72 is the magnetic field generating means (magnet).
, troll), 8 and 9 are developer stirring/conveying means, 17 is a circulation regulating member, and 18 is a stirring means.

Claims (1)

[Claims] (1) In a developing device that develops the surface of a latent image carrier by carrying a developer consisting of toner and magnetic particles on a developer carrying member, the developer is placed above and below the developer carrying member in a developer container. A developing device characterized in that a stirring means is disposed near a stirring/transporting means and a magnetic field generating means included in a developer carrying member.