JPH0527579A - Development device - Google Patents

Abstract

(57) [Abstract] [Purpose] A developer having sufficient triboelectric charge due to the restriction of the developer on the developer carrier by the restriction member without the plastic deformation of the developer restriction member or the fusion of the developer. The objective is to stably obtain a high-quality image with uniform density and no fog by developing by forming a uniform thin layer with. The elastic blade 4 is supported by a swingable magnetic support holder 42, and the pressing force of the blade 4 against the developing sleeve 3 is controlled by operating and releasing the electromagnet 12 that attracts the holder 42. A regulating attitude in which the middle portion of the sleeve 4 is abutted to regulate the developer 7 on the sleeve 3;
It is possible to select a cleaning posture in which the leading edge is brought into contact with the developer and the developer remaining on the sleeve 3 after development is removed. [Effect] The developer 7 on the sleeve 3 can be well regulated without the plastic deformation of the blade 4, the reduction of the contact pressure to the sleeve 3, the fusion of the developer 7 to the sleeve 3 and the generation of agglomerates. An image having the desired performance can be obtained by development.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used for developing and visualizing a latent image formed on an image bearing member in image formation utilizing an electrophotographic system or the like.

[0002]

2. Description of the Related Art In an image forming apparatus utilizing an electrophotographic method, a latent image formed on an image carrier is developed by a developing device to be visualized as a toner image. A developing device that uses a dry one-component developer is known.

Conventionally, various developing devices using a one-component developer (toner) have been proposed and put into practical use. As a mechanism for imparting a triboelectric charge to a one-component developer, a triboelectric charging between developers or a triboelectric charging between a developer and a developer carrier has been proposed.
Regardless of which mechanism is adopted, it is desirable to form the developer in a thin layer on the surface of the developer carrier for imparting triboelectric charge. However, it is difficult to form a thin layer of the developer on the surface of the developer carrier, and many developing devices stop forming a relatively thick developer layer.

As a conventionally known method for forming a thin layer of a one-component developer, for example, JP-A-54-43037 has been proposed and put into practical use. However, this relates to the formation of a thin layer of a magnetic developer in which magnetic particles are internally added, and not the formation of a thin layer of a non-magnetic developer. Magnetic developers have problems that they have poor heat fixing properties on transfer paper and that they are poor in color reproducibility when used as color developers.

As a method for forming a thin layer of a one-component non-magnetic developer, a soft fiber such as a beaver hair is made into a cylindrical fiber brush, which is used as a developer carrying member, and the developer is further formed thereon. Has been proposed, and a method of applying it by a doctor blade or the like on a developer carrying member whose surface is made of fibers such as velvet has been proposed.

However, in these methods, it is difficult to apply the developer uniformly, or the triboelectric charge is insufficiently applied to the developer, so that uneven image density and fogging are likely to occur. There is a problem.

As shown in FIG. 7, one-component non-magnetic developer 7
Developing sleeve 3 installed in a developing container 2 containing
A rubber plate on which the developer 7 is supplied and carried by the developer supply roller 5 made of an elastic roller brought into contact with the developer, and the carried developer 7 is elastically brought into contact with the developing sleeve 3. A method of forming a thin layer of the developer 7 on the developing sleeve 3 by regulating the elastic blade 4 made of a metal plate or the like has been proposed and put into practical use in Japanese Patent Publication No. 63-16736.

In such a method for forming a thin developer layer, the elastic blade 4 is developed by applying the triboelectric charge to the developer 7 and forming a uniform thin developer layer by the triboelectrically charged developer 7. It is determined by the contact state with the sleeve 3. In this case, the developer 7 is triboelectrically charged by the contact with the elastic blade 4 and the developing sleeve 3 and is given an electric charge. Therefore, if the contact pressure of the elastic blade 4 with the developing sleeve 3 is increased, the charge can be sufficiently applied to the developer 7.

[0009]

However, when the contact pressure of the elastic blade 4 with the developing sleeve 3 is increased, excessive pressure is applied to the developer 7 at the contact portion, and the developing sleeve 3
The fusion of the developer 7 onto the surface of the developer 7 causes uneven coating. Therefore, even if both the formation of a uniform thin developer layer on the developing sleeve 3 and the provision of sufficient triboelectric charge of the developer 7 due to the restriction of the elastic blade 4 are opposed to each other. It was difficult to realize together.

Further, a rubber material such as urethane-based or silicone-based rubber which is generally used as the elastic blade 4 easily causes plastic deformation with time in a state of being in contact with the developing sleeve 3, and therefore, the elastic blade 4 with time. There has been a problem that the contact pressure on the developing sleeve 3 is lowered, and the triboelectric charge application to the developer 7 is lowered.

Further, a developing device using the non-magnetic one-component developer 7 having the above structure is provided near the photosensitive drum 1 of the multi-color image forming apparatus as shown in FIG.
When applied to a plurality of developing devices such as M and 3Y, during the developing operation of one of the developing devices, the surface of the developing sleeve of the developing device that is not performing the other developing operation is exposed to the photosensitive drum 1. When the developer is present on the surface of the photosensitive drum 1 facing each other, the developer existing on the surface adheres to the image formed on the photosensitive drum 1 by the above-described developing operation, causing a problem of color mixing. Conventionally, in this type of multi-color image forming apparatus, since a developing device using a two-component developer in which magnetic particles are mixed is used as the developing devices 3C to 3Y, the developer on the surface of the developing sleeve by magnetic means is used. It could be solved by the recovery mechanism of However, it is extremely difficult to collect the developer on the surface of the developing sleeve 3 facing the photosensitive drum 1 in the developing device using the non-magnetic one-component developer 7 as in the present configuration, and therefore, as a developing device for multi-color image formation. When applied, there is a problem that color mixing occurs in the image on the photosensitive drum 1.

The object of the present invention is to control the developer carried on the developer carrying member by the developer restricting member elastically abutting against the developer carrying member, and to plastically deform and develop the restricting member. There is no decrease in contact pressure to the agent carrier, no fusion of the developer to the developer carrier, no generation of aggregates, and sufficient frictional charge is given to the developer on the developer carrier by regulation. It is an object of the present invention to provide a developing device capable of forming a uniform thin developer layer, which makes it possible to stably obtain a high-quality image with uniform density and no fog during development.

[0013]

The above object can be achieved by the developing device according to the present invention. In summary, the present invention regulates the developer by elastically abutting the middle portion of the developer regulating member to a developer carrier carrying the developer contained in the developing container. In a developing device that conveys the developer to a developing unit facing the image carrier by rotating the developer carrier while forming a thin layer of the developer on the carrier, the pressing force of the regulating member is used. A control means is provided, and by controlling the pressing force of the developer carrying body by the control means, the regulation of contacting the middle of the regulating member with the developer carrying body to form a thin layer of the developer. The contact position of the restriction member with respect to the developer carrying member is selected between the position and the cleaning position in which the tip end of the restricting member is brought into contact with the developer carrying member to clean the developer carrying member. With a developing device characterized by making it possible That.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing an embodiment of the developing device of the present invention. As shown in FIG. 1, the main developing device is provided so as to face the photosensitive drum 1 of the image carrier that rotates in the arrow A direction. The photosensitive drum 1 is composed of a photosensitive member or the like having an organic photoelectric layer provided on a conductive substrate, and an electrostatic latent image is formed on the surface thereof by an electrostatic recording unit (not shown).

The developing device includes a developing container 2 containing a one-component non-magnetic developer (non-magnetic toner) 7, a developing sleeve 3 of a developer carrier installed in the developing container 2, and a developer regulating means. The elastic blade 4, the supply roller 5 of the developer supplying means, and the feeding member 6 of the developer conveying means are provided.

The developing container 2 has an opening extending in the longitudinal direction at right angles to the surface of the drawing at a position facing the photosensitive drum 1, and the developing sleeve 3 is rotatably disposed in this opening. . The developing sleeve 3 is rotationally driven in the direction of arrow B by a drive source (not shown). On the surface of the developing sleeve 3,
In order to ensure the retention of the developer 7, irregularities having a pitch of 0.5 to 5 μm are formed.

The supply roller 5 is arranged behind the developing sleeve 3 on the side opposite to the photosensitive drum 1 side, and is rotatably installed so as to elastically contact the developing sleeve 3 at the contact portion S. The supply roller 5 comes into elastic contact with the developing sleeve 3 to peel off the undeveloped developer on the developing sleeve 3 and to newly supply the developer 7 in the developing container 2 onto the developing sleeve 3 to carry it. It is for making it.

The elastic blade 4 is arranged at a position downstream of the contact portion S of the developing sleeve 3 in the rotational direction so as to form the contact portion T with the developing sleeve 3. According to this embodiment, as shown in FIG.
By supporting one end of the elastic blade 4 on a support holder 42 made of a magnetic material attached to the side wall of the developing container 2 or the like, the elastic blade 4 is swingably installed around a shaft 43. As the pressing force control means of 4,
The electromagnet 12 is provided at a position corresponding to the support holder 42 of the developing container 2, and the abutting member 13 is provided at a position opposite to the electromagnet 12 side of the support holder 42.

At the time of development, the pressing force control means operates the electromagnet 12 to attract the support holder 42 to the electromagnet 12 at the time of development, thereby causing the elastic blade 4 to center on the shaft 43 and the development sleeve 12 as shown in FIG. The regulating attitude in which the elastic blade 4 hits the developing sleeve 3 so that the elastic blade 4 presses the developing sleeve 12 strongly and the elastic blade 4 forms the contact portion T midway near its tip end. Attitude control. As a result, the developer 7 carried on the developing sleeve 3 is regulated by the elastic blade 4 and imparted with triboelectric charge while passing through the position of the elastic blade 4 in contact with the abdomen in the regulating posture. It is applied in a thin layer on the developing sleeve 3.

Further, the pressing force control means releases the operation of the electromagnet 12 to release the support holder 4 as shown in FIG.
By stopping the attraction of No. 2, the pressing force of the elastic blade 4 on the developing sleeve 12 is weakened, and the elastic blade 4 is swung in the direction away from the developing sleeve 12 about the shaft 43 by its elasticity, and the support holder 42 is moved. At the position where the elastic blade 4 is brought into contact with the abutting member 13, the attitude of the elastic blade 4 is controlled to the cleaning attitude in which the elastic blade 4 is brought into contact with the developing sleeve 3 at the edge thereof. As a result, the surface of the developing sleeve 3 is cleaned by the elastic blade 4 while passing through the position of the elastic blade 4 in contact with the edge in the cleaning position, and the developer remaining on the developing sleeve 3 is stripped and removed. To be done.

As an example, an elastic blade 4 made of silicone rubber having a rubber hardness of 60 ° is attached to a developing sleeve 3 having an outer diameter of 16 mm.
When using, the contact pressure of the elastic blade 4 to the developing sleeve 3 is such that the contact width of the elastic blade 4 to the developing sleeve 3 at the time of development is 0.5 to 2 mm, preferably about 1 mm ( (Approx. 20 g / cm in contact pressure), the contact width is 0.01 to 1 mm, preferably 0.05 to 0.3 when not developed.
It is necessary to set so that the frictional charge of the developer 7 on the developing sleeve 7, the thin layer formation and the developing sleeve 7 are set to be mm.
It was good for peeling off the developer remaining after development.

From the above, according to the developing device of this embodiment,
Plastic deformation of elastic blade 4, developing sleeve 3 of developer 7
There is no decrease in contact pressure to the developing sleeve 3 for the developer 7.
When the developing blade 3 is peeled off from the developing sleeve 3 by the elastic blade 4 and the developing agent on the developing sleeve 3 is regulated, the developing agent 7 is not adhered to the developing sleeve 3. It is possible to form a thin developer layer having a uniform triboelectric charge. Therefore, a high-quality image having a uniform density and no fog can be stably obtained by the development using the developer 7.

As the elastic blade 4, polyisoprene, butadiene-styrene copolymer, polybutadiene,
Isobutylene-isoprene copolymer, butadiene-acrylonitrile copolymer, ethylene-propylene copolymer, chlorosulfonated polyethylene, acrylic ester copolymer, polyurethane, organic polysiloxane, perfluoropropene, vinylidene fluoride copolymer, etc. Rubber elastic members, single layers of elastic metal members such as Ni, SUS, Al, phosphor bronze, etc., or polyamide, polyimide, polyamide imide, polyether imide, polyether ether ketone, polyphenylene sulfide, liquid crystal polymer, etc. It is composed of laminated composite layers.

It is preferable that the rubber elastic member or the like used for the elastic blade 4 is specifically selected from the triboelectric charging series suitable for charging the developer 7 to a desired polarity.
For example, in order to negatively charge a developer containing polyester as a resin component, it is preferable to use a material obtained by laminating polyamide on urethane rubber for the elastic blade 4. If a conductive rubber in which metal particles and the like are dispersed is also used for the elastic blade 4, it may be effective against aggregation and solidification of the developer 7 due to excessive triboelectric charging.

The developer feeding member 6 is rotatably installed in a portion inside the developing container 2 behind the supply roller 5 and rotates in the direction of arrow D to supply the one-component non-magnetic developer 7 in the developing container 2. It is designed to be conveyed to the roller 5. Supply roller 5
A barrier 8 having an open central portion is provided between the feeding member 6 and the feeding member 6. The barrier wall 8 prevents the developer 7 from being excessively conveyed to the supply roller 5 by the feeding member 7, and also causes the developer 7 sent to the supply roller 5 to be developed by the supply roller 5.
It is designed to merge with the developer that has been peeled off. The combined developer is carried on the supply roller 5 and conveyed again to the contact portion S with the developing sleeve 3.

Below the developing sleeve 3, there is provided a seal member 9 for closing a gap with the developing container 2. Further, a bias power source 10 for applying a developing bias is provided between the photosensitive drum 1 and the developing sleeve 3, and the developing sleeve 3
The developer 7 on the supply roller 5 is located between the supply roller 5 and the supply roller 5.
A bias power supply 11 for applying a bias for adhesion to the photosensitive drum 1 is provided.

The developer 7 formed as a thin layer on the developing sleeve 3 is conveyed to the developing section facing the photosensitive drum 1 by the rotation of the developing sleeve 3, and the electrostatic latent layer formed on the photosensitive drum 1 there. The image is electrostatically transferred to visualize the electrostatic latent image as a toner image. The toner image thus formed on the photosensitive drum 1 is transferred onto a recording material such as paper at a transfer portion of the image forming apparatus, and then the recording material is fixed on the recording material and then transferred outside the image forming apparatus. Is discharged to.

The developing method of the developing device of this embodiment is as follows.
For example, the method described in JP-B-58-32375, that is, an alternating voltage in which a DC voltage is superimposed between the photosensitive drum 1 and the developing sleeve 3 is applied as a developing bias to expose the developer layer formed on the developing sleeve 3 to light. A so-called non-contact developing method of transferring to the electrostatic latent image on the drum 1 can be used,
Alternatively, a contact development method may be used.

On the surface of the developing sleeve 3, a resin layer containing conductive particles such as flaky, fibrous and powdery metallic materials, metal oxides, graphite and carbon black is applied and formed. Can be kept. In order to reduce the resistance value on the surface of the developing sleeve 3 to prevent the accumulation of charges on the surface of the developing sleeve 3 and to improve the developability in the non-contact development, the volume resistivity of the surface of the developing sleeve 3 should be 10%. It is preferable to keep it at ⁴ Ωcm or less, and it is preferable that the resin used for the above resin layer has a high ability to impart a triboelectric charge to the developer 7, and therefore a resin having a triboelectric charge series different from that of the developer 7 is used. It is preferable. For example, polyisoprene, butadiene-as used for the elastic blade 4
Styrene copolymer, polybutadiene, isobutylene-isoprene copolymer, butadiene-acrylonitrile copolymer, ethylene-propylene copolymer, chlorosulfonated polyethylene, acrylic ester copolymer, polyurethane, organic polysiloxane, perfluoropropene,
Vinylidene fluoride copolymer, polyamide, polyimide,
Polyamideimide, polyetherimide, polyetheretherketone, polyphenylene sulfide, liquid crystal polymer and the like are preferable. These are appropriately selected according to the polarity of the triboelectric charge to be applied to the developer 7. For the same reason, a charge control agent equivalent to the one internally added to the developer may be added to these resins and used for forming the above resin layer. Lubricating powder may be added to the resin in order to improve the cleaning ability when cleaning the developing sleeve 3 during non-development and prevent fusion of the developer 7 to the developing sleeve 3.

FIG. 4 is a sectional view showing a pressing force control means for an elastic blade in another embodiment of the developing device of the invention. In this embodiment, the support holder 41 supporting the elastic blade 4 is fixedly installed in the developing container 2 so that the elastic blade 4 is installed non-rotatably, and the elastic blade 4 is not rotated.
An electromagnetic solenoid 14 is provided between the developing container 2 and the elastic blade 4 as a pressing force control means.

The elastic blade 4 is in a cleaning position in which the tip edge of the elastic blade 4 is in contact with the developing sleeve 3 while being supported by the support holder 41, and is in this cleaning position during normal non-developing. The electromagnetic solenoid 14 is used for the developing container 2
By fixing the rod 1 to the rod 2 by inserting it between the container 2 and the elastic blade 4 and operating during development.
By extending 4a toward the elastic blade 4, the pressing force of the elastic blade 4 against the developing sleeve 3 is increased,
The elastic blade 4 is posture-controlled so as to form the contact portion T in the middle of the elastic blade 4 such that the elastic blade 4 hits the developing sleeve 3 in a restricted posture.

Also in this embodiment, the developer 7 carried on the developing sleeve 3 is regulated by the elastic blade 4 which is in abutting contact with the elastic sleeve 4 in the regulating posture, and the developing blade is in the cleaning posture by the elastic blade 4 which is in abutting contact with the edge. Since the developer remaining after development on 3 is peeled off and removed, there is no plastic deformation of the elastic blade 4 and reduction of the contact pressure of the developer 7 on the developing sleeve 3, and the developer 7 on the developing sleeve 3 is not removed. A high-quality image with uniform density and no fogging by development by forming a thin developer layer on the developing sleeve 3 in which each developer 7 has a sufficient triboelectrification charge and is free from fusing and aggregation. Can be stably obtained.

In the above embodiment, the means for controlling the pressing force of the elastic blade 4 by the electromagnetic force using the electromagnet 12 or the electromagnetic solenoid 14 is shown. However, the pressing force control means may be a spring force or a repulsive force of a permanent magnet. It can also be constituted by the mechanical means used. Further, the elastic blade 4 is provided by the pressing force control means
By swinging, the pressing force of the elastic blade 4 against the developing sleeve 3 is controlled to adjust the contacting posture.
As shown in FIG. 3, the elastic blade 4 is lowered by a pressing force control means (not shown) via a support holder 42 which is attached to the developing container 2 so as to be movable up and down, so that the elastic blade 4 abuts against the developing sleeve 3 and abuts against the developing sleeve 3. Figure 6
Conversely, as shown in FIG. 5, the elastic blade 4 may be raised in the same manner to bring the elastic blade 4 into edge contact with the developing sleeve 3 to be in the cleaning posture. Alternatively, instead of moving the elastic blade 4 up and down as described above, it may be moved left and right. As long as the pressing force of the elastic blade 4 can be controlled to control the contacting position of the elastic blade 4 to the developing sleeve 3 between the restricting position and the cleaning position, the elastic blade 4 can be operated freely. Further, as an operation sequence, it is possible to temporarily set the developer restriction state during non-development to remove foreign matters such as paper dust accumulated on the elastic blade 4 during the cleaning operation.

Although the case where a non-magnetic one-component developer is used as the developer 7 has been described, the present invention is not limited to this, and the present invention is also applicable to the case where a magnetic one-component developer or a two-component developer is used. Needless to say.

Further, as shown in FIG. 8, the developing device of the present invention is suitable for a plurality of developing devices such as developing devices 3C, 3M and 3Y arranged in the vicinity of the photosensitive drum 1 of a multi-color image forming apparatus. Applicable.

[0036]

As described above, in the developing device of the present invention, the developer carried on the developer carrying body is elastically abutted, so that the developer carried on the developer carrying body is regulated. By providing a pressing force control means for the member to control the pressing force of the regulating member against the developer carrying member, a regulating attitude for regulating the developer contacting the developer carrying member midway of the regulating member. And a cleaning posture in which the tip edge of the regulating member is brought into contact with the developer carrying body to clean the surface of the developer carrying body, the contact posture of the regulating member with respect to the developer carrying body can be selected. There is no plastic deformation of the member, reduction of contact pressure to the developer carrier, fusion of developer to the developer carrier, and formation of agglomerates, and sufficient friction on the developer carrier due to regulations. It is possible to form a uniform thin developer layer while imparting an electrostatic charge, High quality images are not uniform and fog density at development can be stably obtained by Les.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing a state in which an elastic blade is controlled to a regulated posture by a pressing force control means provided in the developing device of FIG.

FIG. 3 is a sectional view showing a state in which the elastic blade is similarly controlled in a cleaning posture.

FIG. 4 is a sectional view showing a pressing force control means of an elastic blade in another embodiment of the developing device of the invention.

FIG. 5 is a cross-sectional view showing a method of controlling the elastic blade to a restricted posture according to the present invention.

FIG. 6 is a sectional view showing a method of controlling the elastic blade to a cleaning posture.

FIG. 7 is a cross-sectional view showing a conventional developing device.

FIG. 8 is a sectional view showing a multi-color image forming apparatus to which the developing device of the present invention can be preferably applied.

[Explanation of symbols]

1 photosensitive drum 2 Development container 3 Development sleeve 4 elastic blade 5 supply rollers 12 Electromagnet 13 Abutting member 14 Electromagnetic solenoid 42 Support holder

Claims (2)

[Claims] 1. The developer carrying member is regulated by elastically abutting a middle portion of a developer regulating member to a developer carrying member carrying a developer housed in a developing container to regulate the developer. In a developing device that conveys the developer to a developing section facing the image carrier by rotating the developer carrier while forming a thin layer of the developer on the developer, a pressing force control unit for the regulating member is provided. And a regulating attitude for controlling the pressing force of the regulating member against the developer carrying member so that the middle portion of the regulating member is brought into contact with the developer carrying body to form a thin layer of the developer. And a cleaning posture in which the leading edge of the regulation member is brought into contact with the developer carrying body to clean the developer carrying body, the posture in which the regulation member is brought into contact with the developer carrying body can be selected. And a developing device. 2. The developing device according to claim 1, wherein the developer is carried on the developer carrier by being supplied by a supply roller elastically abutting on the developer carrier.