JPH02116876A - Developing device - Google Patents

Abstract

PURPOSE:To supply toner to a developer properly by providing a toner supplementing rotary member and an opening position for the border surface of a developer between a 1st chamber which contains a developer and has a developing sleeve rotating while a magnetic field operates and a 2nd chamber which contains toner. CONSTITUTION:The partition member 22 which has the opening part 15 is provided between the 1st chamber 11 forming a circulation system for the developer with a developing sleeve 13 which has a two-component and rotates while a magnetic field is made to operate and the 2nd chamber 12 which contains the toner, and the rotary member 16 which supplements toner is provided above the opening part 15. When the toner concentration decreases and the developer capacity decreases, the border surface of the circulated developer moves back and toner T conveyed by the rotary member 16 made of an elastic body is supplied to the part; when the border surface of the developer moves forth, the border surface of the developer at the opening part of the partition plate stays at the partition member opening part and the supply of the toner T is stopped. Consequently, the toner is supplied properly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device for an image forming apparatus, and in particular, develops using a two-component developer of magnetic carrier and toner, and reduces the amount of water consumed by the development. This invention relates to a developing device that is configured to supply toner and perform development.

[Background of the invention]

A developing device that performs development using a two-component developer generally consists of a developing sleeve, an agitating section, and a portion of toner. It is transported to a development area facing the image carrier, and develops the electrostatic latent image on the image carrier. After the toner is consumed by development, the developer adheres to the circumferential surface of the developing sleeve, is conveyed, and circulates to the stirring section.

The conditions for good development with a two-component developer are that the content ratio of toner in the developer (toner concentration) must be maintained within a certain range, and the magnetization of the developer in the stirring section must be detected. The toner density is indirectly detected by developing a standard latent image formed on a photoreceptor and measuring its reflection density.

The method of detecting toner concentration by measuring the density of a developed standard latent image is indirect and does not necessarily indicate the toner ratio in the developer.

Furthermore, toner concentration measurement by detecting the magnetization of the developer has a problem in that the detection results are unstable.

Further, in the developing device, consumed toner is replenished from a portion of the toner based on the measurement results of toner density, but this inevitably complicates the toner supply mechanism and its control.

[Problem that the invention seeks to solve]

Development methods using two-component developers are roughly classified into the following three types.

(a) Two-component magnetic brush development method This is a conventional and common development method in which a brush-shaped developer spike is formed by magnetic force at a location facing the photoreceptor on the circumferential surface of the developing sleeve. This is a developing method in which the photoreceptor is brought into sliding contact with the photoreceptor bearing the latent image.

(b) Two-component non-contact development method JP-A-59-181362, JP-A-60-176
This is a developing method disclosed in Japanese Patent No. 069, etc., in which a thin layer of developer is formed on the circumferential surface of a developing sleeve, and the developing method is performed without contacting the photoreceptor.

(c) One-component non-contact developing method using a two-component developer For example, in the developing method described in Japanese Patent Application Laid-Open No. 60-42768, only toner is placed on the developing area facing the photoreceptor having a latent image on the developing sleeve. This is a developing method in which the film is attached to and transported to the surface of the film and developed.

Regarding the toner concentration in the developer in the stirring section, (b) and (c) above have a particularly large tolerance compared to (a), and even if the concentration is not maintained within a very strict range, it can still be maintained in a good condition. It is clear that development will take place. Also (a
), the allowable toner concentration range can be expanded by making the carrier particles microscopic.

The present invention is a developing device in which the toner concentration in the stirring section is controlled without using toner concentration detection means and toner replenishment means based on the toner concentration detection means that have been studied in various ways in the past. It is an object of the present invention to provide a developing device that is suitable for the developing method b) and (c), does not require complicated control, and has a simple structure for toner replenishment.

[Means for solving problems]

The above object includes: a first chamber containing a two-component developer consisting of a magnetic carrier and toner and forming a circulation system for the developing sleeve and the developer; a second chamber containing the toner; It has a partition member having an opening between the chambers and a rotating member located above the opening to replenish the toner, while the toner is supplied in a layered manner on the developer,
This is achieved by a developing device characterized in that an interface between the developer and the toner is set near the opening position.

[Effect]

The present invention was basically made by focusing on the fact that although the toner is consumed in the developer, the magnetic carrier in the developer is not, and that changes in toner concentration correspond to changes in the amount of developer. It is.

That is, the developing device has a first chamber that forms a circulation system that generates a conveying force by magnetic force and rotation of the developing sleeve, and conveys and circulates the developer in the stirring section from the bottom to the top of the developing area. is separated from the second chamber containing toner by a partition plate and communicated with by a partial opening of the partition plate, and the interface of the developer having an appropriate toner concentration is near the position below the opening of the partition plate. It is set as shown in . Toner concentration control is achieved by: When the toner concentration decreases and the developer capacity decreases, the interface of the circulating developer recedes, toner is supplied to that area, and the amount of developer in the first chamber where the circulation system is located increases. When the developer interface moves forward, the developer interface located at the opening of the partition plate stays at the opening of the partition member, and the supply of toner is stopped.

In order for this toner supply/stop to work effectively, it is preferable that the following conditions are satisfied.

(1) The interface of the circulating developer is stable and the developer does not diffuse into the second chamber containing toner.

Alternatively, the toner does not diffuse indefinitely within the first chamber.

(2) The opening position of the partition member is configured to be sensitive to changes in developer capacity.

The following means are effective in preventing the developer from spreading into the second chamber containing the toner (1).

(1-1) Since the magnetic carrier has a higher density (heavier) than the toner, for example, as shown in the cross-sectional view of FIG. It is located above the room 11.

(1-2) For example, if a rotary member made of an elastic body is installed in the opening, the toner T conveyed by the rotary member is scraped off by a scraper, and the toner is supplied little by little to the convection part. without disturbing the interface.

(1-3) For example, as shown in FIG. 2(a), a magnetic force is applied to prevent the developer from spreading from the opening 15 into the second chamber 12 containing the toner T. For example, a permanent magnet 14 provided inside the developing sleeve 13
There is no problem even if it is due to Note that it is preferable that the direction of the magnetic field in the opening 15 be horizontal rather than vertical because the interface of the developer is uniformly formed in the opening. For this purpose, the permanent magnet 14 is fixed and placed at the position shown in the figure.
, an S pole is provided.

(1-4) As shown in FIG. 2(C), the shape of the partition member tip 22a is such that the developer circulating in the direction of the arrow is tilted so that it returns to the first chamber by the protruding partition member 22; The shape and structure are such that the developer material is prevented from flowing into the second chamber 12 that accommodates the toner T from the opening 15.

(1-5) A protrusion is provided at the end of the partition member 22 adjacent to the second chamber side to accommodate the toner T from the opening 15.
A concave structure can also be used to reliably prevent developer from flowing into the chamber.

(1-6) Furthermore, when the developing device is removed from the main body of the image forming apparatus, it is provided in the opening for the purpose of preventing the developer from flowing back into the second chamber due to the developing device being overturned, etc. The rotating member is configured to be able to move its position and close the opening except when toner T is being replenished.

On the other hand, the following means is effective in making the interface position (2) highly sensitive to the toner concentration of the developer.

(2-1) For example, as shown in FIG. 2, in order to sensitively replenish toner, the partition member 22 is
The opening 15 is installed higher and has a smaller cross-sectional area at the interface.
Provided for.

(2-2) The concern that reducing the cross-sectional area of the opening 15 may cause the developer to become clogged and prevent toner replenishment can be avoided by making the developer spikes stand up using magnetic force. Furthermore, this problem can be solved by applying a repulsive magnetic field to make the ears stand taller.

Such a repulsive magnetic field is also effective in preventing developer clogging. In particular, the developer regulating portion formed by the regulating plate 23 is easily clogged with developer, and the circulation of the developer is likely to be disrupted.

In FIG. 2(a), the permanent magnet 14 is fixed and the opening 15 is
The magnetic field is horizontal to the developer sleeve 1.
When the regulation plate 2 is also used to scrape off the developer attached to the plate 3.
3 shows the configuration of a repulsive magnetic field for preventing clogging. In the embodiment described later, the magnet in the developing sleeve 13 is fixed, but the present invention is not limited to this, and a structure in which the permanent magnet 14 rotates in addition to the sleeve rotation can also be used.

When a permanent magnet rotates, ζN and S poles are arranged alternately.
400 to 2 per minute using magnetic rolls with 16 to 16 poles
Use at 000 rpm. The direction of rotation may be the same as or opposite to that of the sleeve.

In FIG. 2(b), an elastic plate 8A such as a rubber plate, a resin plate such as Mylar, or a phosphor bronze plate is provided at the tip of the stirring member 18 to more effectively pump up the toner T in the chamber 2 and open the opening. 15.

〔Example〕

An embodiment of the invention is shown in FIG.

FIG. 1 is a sectional view of a main part of an embodiment of the present invention, in which reference numeral 11 houses a developer layer, agitates the developer layer, charges it to a developing area E, and transports toner T. Room 1, 12
is a second chamber which is provided adjacent to the first chamber 11 and accommodates the toner T; 13 is a developing sleeve made of a non-magnetic or weakly magnetic material such as stainless steel or aluminum; and 14 is a developing sleeve which rotates in the direction indicated by the arrow. is a permanent magnet provided inside the developing sleeve 13 and having a plurality of magnetic poles in the circumferential direction;
5 is located between the first room 11 and the second part N12.
22a is the tip of the partition member 22 that corresponds to the circulating flow of developer, which will be described later. 16 is a rotary member that serves both to transport the toner T and close the opening 15, which will be described later. When the developing device is in operation, the opening 15 is at rest as shown in FIG. 1(a), while when the developing device is in operation, the opening 1 is closed as shown in FIG.
5 and rotates clockwise to convey the toner T supplied from the second chamber 12 to the first chamber 11.

Reference numeral 17a indicates a rod-shaped member 17b made of a non-magnetic material, which is installed approximately in the center of the first chamber 11 in parallel with the axis of the developing sleeve 13, and 18 is an elliptical stirring plate which is provided near the developing sleeve 13 and rotates. A stirring rod that stirs the toner T rotates in the direction of the arrow. 19 is a casing, 30 is an image carrier that carries an electrostatic latent image developed by this developing device on its surface, and E is a developing area where the development is performed.

The rotary member 16 is driven and rotated by the actuating device shown in FIG. 1(c) and FIG. 1(d), or is used as a shielding member to open and close the opening 15.

In FIG. 1(c), reference numeral 16a denotes a rotating shaft that is integrated with the rotating member 16, and 40 is a U-shaped support that rotatably supports the rotating shaft 16a on the outside of both side walls of the casing 19. The metal fittings 41 are support bins for pivotally fixing the support metal fittings 40 to both side walls of the casing 19, and the support metal fittings 40 are tension pins 41 stretched between the spring hook pins 42 on one side wall surface of the casing 19. It is urged counterclockwise by a spring 43 and comes into contact with a stop bin 44 to stop.

Gl is a gear fixed to the end of the rotating shaft 16a and is integral with the rotating member 16; G2 is an idler rotatably supported by the support bin 41 meshing with the gear Gl; and G3 is The drive gear G3 is a drive gear rotated by the power of the image forming apparatus main body, and the drive gear G3 is installed at a fixed position in the apparatus main body.

When the developing device is not attached to the main body of the image forming apparatus or is not set in a predetermined position, the support fitting 40 occupies a position rotated counterclockwise as shown in FIG. 1(C). Then, the rotating member 16 moves to the right as shown in FIG. 1(a) to close the opening 15. In this case, the idler G2 is naturally not in a position to mesh with the drive gear G3.

When the developing device is slid on the developing garage 50 and moved in the direction of the arrow, the supporting metal fitting 40 comes into contact with the regulation bin 51 of the main body of the device and rotates clockwise as shown in FIG. 1(a), and at the same time the idler G2 meshes with drive gear G3.

As a result, the rotating member 16 moves to the left as shown in FIG. 1(b) to open the opening 15, and the idler 62, start rotating clockwise via gear Gl.

Therefore, the toner T conveyed to the opening 15 by the stirring member 18 adheres to the circumferential surface of the rotating member 16, and is supplied to the first chamber 11 by scraping with a scraper 19a protruding from a part of the casing 19. .

FIG. 1(e) shows an example of the rotary member 16 that is considered suitable for practical use, and FIG. ) is a roller with a corrugated peripheral surface, and (c) is a porous roller, and (d) is a sponge-like roller, both of which are made of easily moldable synthetic resin material and are highly abrasion resistant and flexible. A sex roller is used. It may also be a fur brush like (e).

Since this embodiment is constructed as described above, the developer layer is stirred by the rotation of the developing sleeve 13 and the rotation of the elliptical stirring plate 17b, while the rod-shaped member 17 is fixedly positioned.
It is conveyed in the direction of the arrow shown by the solid line below a, and circulates through the upper side of the rod-shaped member 17a. The rod-shaped member 17a is not limited to a rod, but may also be a rotating non-magnetic rod or brush having unevenness. Through this circulation, the developer can supply the charged toner T to the development area E. At the opening 15 on the upstream side of the circulating flow of the developer, a developer layer is formed by the magnetic force from the developing sleeve. That is, the combination of gravity and the magnetic force of the permanent magnet 14 completely prevents the developer from spreading into the second chamber 12 and forms an interface with the toner.

When the toner T in the developer layer is consumed, the interface of the developer layer recedes, and the toner T flows into the first chamber 1 through the opening 15.
1, and appropriate toner replenishment is performed.

In this way, it is possible to obtain a developing device with a simple structure that can perform agitation of the developer layer and appropriate toner replenishment.

The carrier particles are magnetic particles that have been subjected to heat spheroidization treatment and have an average particle size of 60 μm, magnetization of 30 amu/g, and resistivity of 10" Ωc+m or more, in which 70% by weight of fine ferrite is dispersed in a resin. Using non-magnetic particles with a particle size of 5 μm, development was carried out using the apparatus shown in FIG. 1 under conditions such that the toner particle ratio in the developer solution in the first chamber 11 was 10% by weight with respect to the developer. At this time, a non-magnetic metal plate was used as the regulating plate 23.The average charge amount of the toner was 7 μc/g.

The conditions for the image carrier 30 in this case were that it was an OPC photoreceptor, its peripheral speed was 90+im/sea, the highest potential of the electrostatic image formed on the image carrier 30 was -500V, and the lowest potential was -100V.

The diameter of the sleeve 13 is also 30 mm, but its rotation speed is 75.
r.

p-ml, the maximum magnetic flux density of the magnetic pole facing the development area E of the magnet body 4 is 900 Gauss and the other 800 Gauss, and the thickness of the developer layer consisting of carrier and toner before entering the development area E is 0. 4 mm, and the bias voltage applied to the sleeve 13 has a DC voltage component of -200V and an AC voltage component of 2KHz.

It was set to 800V. In this embodiment, the gap between the sleeve 13 and the image carrier 30 is 0.6 m+*, and the two-component developer layer on the sleeve 13 is not in contact with the surface of the image carrier 30.

The image was developed under the above conditions, transferred to plain paper by corona discharge, and fixed by a heat roller fixing device with a surface temperature of 140°C. The resulting image on the recording paper was free from edge effects and fog. The image was extremely clear with high density, and even though we subsequently produced 50,000 sheets of recording paper, we were able to obtain an image that remained stable and unchanged from beginning to end.

〔Effect of the invention〕

As explained above, in the toner concentration control method of the present invention, there is a first chamber that accommodates developer and forms a circulation system with a rotating developing sleeve while applying a magnetic field, and a second chamber that accommodates toner. It consists of a chamber and a partition member between the chambers, and the interface of the developer is set to have the opening position, so that the developer can be accessed with an extremely simple structure that does not require complicated control. This provides an excellent effect of providing an inexpensive developing device in which toner can be replenished appropriately.

[Brief explanation of the drawing]

FIG. 1 is a sectional view and a main part diagram of the developing device of the present invention, and FIG.
The figures are a sectional view and a diagram of main parts of a conventional developing device. 11... First chamber 13... Developing sleeve 15... Opening 16a... Rotating shaft 19a... Scraper 40... Support fitting 43... Tension spring G2... Idler

Claims (3)

[Claims] (1) A developing sleeve that has a two-component developer consisting of a magnetic carrier and toner and rotates while applying a magnetic field, a first chamber that forms a circulation system for the developer, and a second chamber that has toner.
a partition member having an opening between the chamber and the room, and a rotating member located above the opening and replenishing the toner;
A developing device, wherein toner is supplied in a layered manner on the developer, and an interface between the developer and the toner is set near the opening position. (2) The developing device according to claim 1, wherein the rotating member opens and closes the opening as the developing device is attached to and detached from the main body of the image forming apparatus. (3) The developing device according to claim 1, wherein the rotating member opens the opening when the developing device is in operation and closes it when the developing device is not in operation.