JPS6145258A - Developing device - Google Patents

Abstract

PURPOSE:To prevent the aggregation of a developer at the peripheral part of a supply roller and to form a thin toner layer with uniform layer thickness, and to form an excellent image by providing the supply roller which supplies a developer to a developer conveyor and spouting compressed air out of the roller. CONSTITUTION:The device which layers thinly and supplies a developer to a latent image carrier 8 to develop an image is provided with the developer conveyor 1 which conveys the developer along a specific circulation path, a developer hopper 2, the developer supply roller 5 which has a surface layer 5c of a porous material on the peripheral surface of a cylindrical base 5a with numbers of pores 5b while supported rotatably and supplies a developer from the hopper 2 to the conveyor 1, an air supply means 6 which supplies compressed air into the base 5a, and the layer thickness control member 7 which is pressed against the surface of the developer supply roller partially to control the layer thickness of the developer. Thus, the compressed air is spoutted out of the roller 5 which supplies the developer to the conveyor 1 to prevent the aggregation of the toner at the periphery of the roller 5 and convey even a nonmagnetic developer smoothly to a specific path, thereby forming a uniform thin toner layer.

Description

[Detailed description of the invention] 14 ice! The present invention relates to a developing device using a one-component developer, and more particularly to a developing device suitable for a developing method using a non-magnetic one-component developer.

Traditionally, the dry developing methods used for electrophotography and electrostatic recording include two-component developers containing toner and carrier, and one-component developers that do not contain carrier. There is a method to use. The former method allows relatively stable and good images to be obtained, but on the other hand, carrier deterioration and fluctuations in the mixture ratio of toner and carrier tend to occur, making it difficult to maintain and manage the device and make it more compact. There is.

Therefore, attention is being paid to -component type developers that do not have the above-mentioned drawbacks. - In a component type developer, a substance corresponding to a carrier is usually contained in the toner, and when the toner is moved using magnetic force, a magnetic substance is contained in the toner. However, since magnetic materials are opaque, it is difficult to obtain clear color images during color development due to the influence of the dyes. Therefore, especially for color development, a method using a non-magnetic developer that does not contain magnetic substances is suitable, but in this case, the problem is how to move the developer smoothly along a predetermined path. As a result, various problems arise.

1-■ The present invention has been developed in view of the above points, and is capable of stably obtaining high image quality even when using a non-magnetic developer, and has a suitable application range for color development. The purpose is to provide a wide range of developing devices.

Structure In order to achieve the above-mentioned object, the present invention provides a developing device that supplies a thin layer of developer to a latent image carrier and visualizes a latent image, in which the developer is routed through a predetermined circulation path including a developing area. A developer transport body that transports the developer along the developer, a storage means that stores the developer, and a surface layer made of a porous material is formed on the circumferential surface of a cylindrical base having a large number of holes, and is rotatably supported. a developer supply roller for supplying the developer in the storage means to the developer conveyance body; a gas supply means for supplying pressurized gas into the base; a part thereof being pressed against the surface of the developer conveyance body; The present invention is characterized in that it has a layer thickness regulating member that regulates the layer thickness of the developer that is conveyed.

Hereinafter, the present invention will be specifically explained based on examples. FIG. 1 is a schematic sectional view showing a developing device using a non-magnetic component developer as an embodiment of the present invention. 1st
In the figure, a developing sleeve 1 serving as a developer conveying member is rotatably supported, and in this example, is rotated at a predetermined speed in the direction of the arrow. As shown in FIG. 2, the developing sleeve 1 includes an insulating layer 1b made of an insulating material such as chloroprene on the circumferential surface of a sleeve-shaped conductive substrate 1a made of aluminum, etc., and a large number of electrode particles on top of the insulating layer 1b made of an insulating material such as chloroprene. 1c
The electrode layer 1c is formed by stacking electrode layers 1c that are electrically insulated from each other.

In this case 1, for example, by uniformly dispersing and mixing a tetraelectric material such as carbon black into an insulating material such as an epoxy resin, and coating this mixed material on the insulating layer 1b, an electrode in which many microelectrodes are uniformly dispersed. Layer 1c can be easily formed. Metal powder such as copper can also be used as a material for microelectrode IC processing.

Further, as the dispersion medium material for dispersing these in an electrically insulating state from each other, a wide range of materials can be used, such as acrylic, urethane, styrene, acrylic-urethane, epoxy-silicon, or epoxy-Teflon. In order to efficiently triboelectrically charge the toner as a developer, it is required that the triboelectrification series for the toner used be separated.

As described above, by forming the electrode layer 1c in which microelectrodes are dispersed as the surface layer of the developing sleeve 1, even when using a -component toner, the image density is selectively increased in a line image, which is advantageous due to the edge effect. It is possible to obtain excellent development characteristics. In addition, insulating materials such as epoxy resin in which low-resistance substances such as carbon black are dispersed as microelectrodes have better adhesion with toner than metals, so they can be used as special materials such as non-magnetic component toners. It is also possible to support and transport a sufficient amount of developer that does not involve a supporting force such as magnetic force. The conductive substrate 1a is connected to a bias voltage [10] at the same potential as a static eliminating brush 9, which will be described later. Further, the insulating layer 1b is provided to maintain an electric field strength suitable for development, and can be omitted if necessary.

In this example, it is on the right side in the figure with respect to the developing sleeve 1.

A hopper 2 is formed to store developer. The developer used in this example is a non-magnetic one-component toner. A replenishment port 2a is formed in the upper part of the hopper 2, and a cartridge 3 filled with toner is attached to the replenishment port 2a, and new toner is supplied to the hopper 2 by gravity falling. An agitator 4 is rotatably disposed within the hopper 2 to feed the toner toward the surface of the developing sleeve 1 while preventing agglomeration of the toner.

On the exit side of the hopper 2 that supplies toner to the developing sleeve 1, a toner supply roller 5 that promotes the movement of toner onto the surface of the developing sleeve 1 is rotatably disposed. The toner supply roller 5 has a cylindrical core metal 5a as shown in FIG.
A large number of through holes 5b are formed in localized areas so as to be scattered approximately evenly, and a surface layer 5c made of a porous material is laminated on the circumferential surface of the hole. In order to efficiently triboelectrically charge the toner, it is desirable that the material of the surface layer 5c has a triboelectrification range far away from that of the toner. Further, the pore diameter is preferably small in order to form a thin toner layer suitable for development as described later.

In this example, as shown in FIG.
The number of foamed cells is preferably 10 on the circumferential surface of the core bar 5a.
A sponge roller on which a surface layer 5c made of a flexible material such as polyurethane foam and the like having a thickness of about 100 mm is adhered thereto is employed. The core metal 5 is rotatably supported.
An air pipe 6 that introduces and discharges pressurized gas into the core metal 5a is disposed in the center of the core bar 5a, extending in the axial direction. This air pipe 6 has a slit-shaped discharge port 6a bored along the axial direction.
A is held in such a manner that it faces a toner reservoir S where toner aggregation is likely to occur, which will be described later. Therefore, by discharging air from the discharge port 6a of the air pipe 6, the air can be passed through the rotating sponge roller 5 to the toner reservoir S, and toner aggregation can be efficiently prevented. Moreover, this air flow prevents the sponge roller 5 from clogging, and can stably exhibit the effect of smoothly supplying toner to the developing sleeve 1. Furthermore.

Since a relatively small amount of air is passed around the toner supply roller 5, toner aggregation is prevented not only in the toner reservoir S but also in other areas within the hopper 2. still,
The air pipe 6 is omitted and a relatively large amount of air is directly supplied to the core metal 5.
A similar effect can be obtained even if the structure is introduced within a.

The toner supply roller 5 configured as described above is preferably supported at a position where its surface can be brought into pressure contact with the surface of the developing sleeve 1, and is preferably driven and rotated in the same direction as the developing sleeve 1. That is, in the contact portion C, it is preferable that both surfaces move in opposite directions while being in pressure contact with each other. As a result, the toner is sandwiched between both surfaces and efficiently triboelectrically charged, and the layer thickness is regulated, so that a single layer of toner having an appropriate thickness is adhered to the surface of the developing sleeve 1. However, even if the toner supply roller 5 is disposed in a non-contact state with respect to the developing sleeve 1, it is possible to supply toner to the developing sleeve 1, and it is possible to use toner with high charging efficiency or to provide a separate suppressing member. By using a method in which a single layer of toner is deposited and formed, the same effect as in the case of contact can be obtained. Further, the preferred circumferential speed of the surface of the toner supply roller 5 varies depending on the circumferential speed of the developing sleeve 1, but in general, it is set to a higher speed than the developing sleeve 1, and the surface of the toner supply roller 5 is set on the surface of the developing sleeve 1. It is preferable to rotate while slidingly contacting each other. However, if the speed is set too high, there will be side effects such as toner scattering, toner sticking to the bearing, and promotion of toner aggregation within the hopper 2, so it is required to set the speed within an appropriate range.

In this example, the sponge roller 5 described above is arranged so as to be able to drive and rotate in the same direction as the developing sleeve 1 while being in pressure contact with the surface of the developing sleeve 1. In this case, the diameter is 25.
The developing sleeve 1 with a diameter of 4 m is rotated at a speed of 400 rp+n, whereas the toner supply roller 5 with a diameter of 14 mm is rotated at a speed of 80 Orpm, and the ratio of the peripheral speeds of the two is as follows.
It is set to approximately 10:11. By providing the toner supply roller 5 in this manner, the toner stored in the hopper 2 and sent out with the rotation of the agitator 4 moves following the rotation of the toner supply roller 5 and smoothly reaches the contact portion C. be transported. In this case, the force that causes the toner to follow the rotation of the toner supply roller 5 mainly involves electrostatic force caused by friction between the toner and the toner supply roller 5. Therefore, even if the developer is a non-magnetic toner containing neither carrier nor magnetic material, it can be smoothly transferred from the hopper 2 to the surface of the developing sleeve 1 as the toner supply roller 5 rotates. At the contact portion C, the toner transferred between the surfaces of the developing sleeve 1 and the toner supply roller 5 that move in opposite directions is pinched, and at this time, it is frictionally charged and the toner is applied to the surface of the developing sleeve 1. attached. Note that when the surface 15c of the toner supply roller 5 is formed of a flexible material as in this example, the higher the hardness of the flexible material, the more efficiently the toner can be triboelectrically charged and the toner can be uniformly attached to the surface of the developing sleeve 1. .

Along the rotational direction of the developing sleeve 1, on the downstream side of the toner supply roller 5, there is a doctor blade that regulates and thins the layer thickness of the toner layer that is formed on the surface of the developing sleeve 1 and is conveyed as the sleeve rotates. 7 are arranged. The doctor blade 7 of this example is formed by covering one side of a main body 7a made of an elastic member with an insulating film 7b made of a fluororesin such as PFA (perfluoroalkoxy resin). The tip end thereof is brought into pressure contact with the surface of the developing sleeve 1 via the insulating film 7b to regulate the layer thickness of the toner.

In this case, by bringing the tip edge portion 7c of the doctor blade 7 into contact with the surface of the developing sleeve 1, the toner layer thickness can be uniformly regulated over substantially the entire required range in the width direction of the developing sleeve 1. It becomes possible to stably form a thin toner layer with a uniform thickness. In addition, the insulating film 7b is provided to prevent toner from sticking and improve charging characteristics. By using a fluorine-based material as in this example, it is possible to more effectively prevent toner from sticking and reduce friction. Charging is performed.

The toner whose movement toward the downstream side is regulated by the doctor blade 7 is returned between the toner supply roller 5 and the doctor blade 7 on the upstream side, and moves toward the developing sleeve 1 side as the toner supply roller 5 rotates. It merges with the toner to form a toner reservoir S.

In this toner reservoir S, toner aggregation tends to occur, which has an adverse effect on the formation of a thin toner layer with a uniform layer thickness. Therefore, in this example, in order to prevent this toner aggregation, air is discharged from the toner supply roller 5 toward the toner reservoir S as described above. Incidentally, if a stirring member such as a separate agitator is provided in the toner reservoir S, it is possible to more reliably prevent toner from sticking.

A portion of an endless organic photoreceptor belt (OPC belt) 8 as a latent image carrier is rotatably stretched at a suitable position on the downstream side of the doctor blade 7 in the rotational movement path of the developing sleeve 1. The surfaces of the developing sleeve 1 come into contact with each other to form a developing area.

The OPC belt 8 undergoes uniform charging and image exposure processes at the appropriate location.
The electrostatic latent image formed on the surface of the drum is conveyed to the development area along with its rotation. In the developing area, a thin layer of toner whose layer thickness is regulated by a doctor blade 7 and which has been sufficiently triboelectrically charged is carried on the surface of the developing sleeve 1 and conveyed.

In this case, since the electrode layer 1c on the surface of the developing sleeve 1 is made of an insulating material such as epoxy resin to which toner easily adheres as described above, a special supporting force for non-magnetic component toner is set. It is possible to evenly carry and convey the developer that is not used on the peripheral surface evenly. Therefore, a thin toner layer with a uniform layer thickness is stably supplied to the electrostatic latent image formed on the OPC belt 8, and the latent image is uniformly visualized.

On the downstream side of the developing sleeve 1 in the rotational direction of the developing area, a static eliminating brush 9 is disposed to remove unnecessary charges accumulated on the surface of the developing sleeve 1. Developing sleeve 1
Due to friction with the toner supply roller 5, doctor blade 7, OPC belt 8, etc., electric charges with a polarity unnecessary for development tend to accumulate on the surface. This unnecessary charge.

Since it causes image defects such as background stains and streaks, it is required to remove it reliably. In particular, the charges accumulated in the insulating material such as epoxy resin, which is the material of the electrode layer 1c of the developing sleeve 1, are more difficult to remove than in the case of metal scraps, and an efficient charge removal means is required. In this example, the length, material, and mounting position of the static elimination brush 9 are set so that the tip abdomen of the conductive brush bristles 9a can come into contact with the surface of the developing sleeve 1 with appropriate pressure due to its own elasticity. . Thereby, the brush bristles 9a can uniformly contact the surface of the developing sleeve 1 over a required area in the width direction, and a good static elimination effect without uneven static elimination can be obtained.

The static eliminating brush 9 is connected to the bias power supply 10 at the same potential as the conductive base 1c of the developing sleeve 1 described above. Thereby, unnecessary accumulated charges on the surface of the developing sleeve 1 and charges of residual toner that has not been subjected to development can be selectively and efficiently removed. Thus, the remaining toner, which has lost its electrostatic adhesion after the static elimination process, is conveyed to the sponge roller 5 as the developing sleeve 1 rotates, where it is easily scraped off from the surface of the developing sleeve 1.

That is, the sponge roller 5 is pressed against the developing sleeve 1 and is in surface contact with the developing sleeve 1 over an appropriate length, and the sponge roller 5 is supported by the roller 5 at the upstream side of the contact portion C with respect to the rotational direction of the roller 5 as described above. The conveyed toner is regulated and adhered to the surface of the developing sleeve 1, but on the downstream side, it has the effect of scraping off the remaining toner adhered to the surface of the developing sleeve 1. The scraped toner is returned to the hopper 2 as the roller 5 rotates and is reused.

In the above embodiments, a non-magnetic component toner is used as the developer, but the present invention is not limited to this and can be applied to a developing device that uses magnetic toner. Further, the present invention is also applicable to a rigid drum-type latent image carrier such as a photosensitive drum. Furthermore, the doctor blade 7 may be made of an elastic magnetic material and may be appropriately pressed against the surface of the developing sleeve 1 by the magnetic force of a magnet disposed inside the developing sleeve 1.

As described in detail above, according to the present invention, by providing a supply roller for supplying developer to a developer conveying member and discharging pressurized gas from inside the roller, Agglomeration of the developer can be prevented, and even non-magnetic developer that cannot be moved using magnetic force can be smoothly transported along a predetermined path. Therefore, even in a developing device that uses -component non-magnetic toner, a thin toner layer suitable for development with a uniform layer thickness and the necessary charge can be stably formed and supplied, and high image quality can be obtained over a long period of time. becomes possible. It should be noted that the present invention is not limited to the specific embodiments described above, and it goes without saying that various modifications can be made within the technical scope of the present invention.

For example, the pressurized gas discharged from the toner supply roller 5 is not limited to air, and various other gases may also be used. Further, the present invention is also applicable to a system in which development is performed by simply bringing the latent image carrier and the developer conveying member close to each other without contacting them.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a part of one embodiment of the present invention. FIG. 3 is a perspective view showing the core bar 5a, and FIG. 4 is a perspective view showing the core metal 5a.
FIG. 2 is a schematic cross-sectional view showing essential parts of an example. (Explanation of symbols) 1: Developing sleeve 5: Toner supply roller Sa: Core bar 5b: Through hole 5c: Surface layer 6: Air pipe 6a: Discharge port Patent applicant Ricoh Co., Ltd. - Figure 2

Claims (1)

[Claims] 1. In a developing device that supplies a thin layer of developer to a latent image carrier and visualizes a latent image, the developer is conveyed along a predetermined circulation path that includes a developing area. A surface layer made of a porous material is formed on the circumferential surface of a cylindrical base having a developer transport body, a storage means for storing developer, and a cylindrical base having a large number of holes, and is rotatably supported. A developer supply roller that supplies the developer of the means to the developer transport body, a gas supply means that supplies pressurized gas into the base, and a part of the developer is brought into pressure contact with the surface of the developer transport body and is conveyed. A developing device comprising: a layer thickness regulating member that regulates the layer thickness of a developer. 2. The developing device according to item 1 above, wherein the developer supply roller is a sponge roller whose surface layer is made of polyurethane. 3. In the above item 1 or 2, the gas supply means is disposed within the base body and opened toward an upstream region of the layer thickness regulating member with respect to the rotational direction of the developer conveying body. A developing device characterized by being a discharge pipe equipped with a discharge port.