JPH0766214B2 - Development device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a developing device using a one-component developer, and more particularly to a developing device suitable for a developing system using a non-magnetic one-component developer. .

2. Description of the Related Art Conventionally, as a dry developing method adopted for electrophotography or electrostatic recording, there are a method using a two-component developer containing a toner and a carrier and a method using a one-component developer containing no carrier. There is. The former method provides a relatively stable and good image, but on the other hand, deterioration of the carrier and variation in the mixing ratio of the toner and the carrier are likely to occur, which makes it difficult to maintain and compact the apparatus. There is.

Therefore, a one-component developer that does not have the above-mentioned drawbacks has attracted attention. In the one-component type developer, a substance corresponding to a carrier is usually contained in the toner. When the magnetic force is used to move the toner, the toner contains a magnetic substance. However, since the magnetic substance is opaque, it is difficult to obtain a clear color image under the influence of the dye in color development. Therefore, especially for color development,
A method using a non-magnetic developer containing no magnetic material is suitable, but in this case, how to smoothly move the developer along a predetermined path becomes a problem.

The present invention has been made in view of the above points, and it is possible to stably obtain a high image quality even when a non-magnetic developer is used, and it is also suitable for color development. The purpose is to provide a device.

In order to achieve the above-mentioned object, the present invention provides a developing device that makes a latent image visible by visualizing a latent image by supplying a latent image bearing member with a thin layer of the developer and supplying the latent image with a predetermined circulation. A developer conveying roller that conveys along the path, and a surface portion made of a flexible porous material, which is in pressure contact with the developer conveying roller and is in a direction opposite to the moving direction of the developer conveying roller at this pressure contact portion. In addition, a developer supply unit that moves and rotates at a speed faster than the developer transport roller, and a developer on the upstream side in the rotation direction of the developer supply unit at the pressure contact portion between the developer transport roller and the developer supply unit. The developer stored in the developer storage means includes a developer storage means provided to store the developer and a layer thickness control means for controlling the layer thickness of the developer on the developer transport roller. By the developer supply means The present invention provides a developing storage device, which is characterized in that the developer is conveyed to and the conveyed developer is frictionally charged at the pressure contact portion.

Hereinafter, specific description will be given based on examples of the present invention. FIG. 1 is a schematic sectional view showing a developing device using a non-magnetic one-component developer as one embodiment of the present invention. First
In the figure, a developing sleeve 1 as a developer carrier is rotatably supported, and in this example, it is rotationally driven in the direction of arrow A at a predetermined speed. The developing sleeve 1 is, as shown in FIG. 2, an insulating layer made of an insulating material such as chloroprene on the peripheral surface of the sleeve-shaped conductive substrate 1a such as aluminum.
Deposited the 1b, are further stacked a large number of electrodes particle 1c ₁ were dispersed in electrically insulated from one another formed by the electrode layer 1c thereon,
It is configured. In this case, for example, an electrically conductive material such as carbon black is uniformly dispersed and mixed in an insulating material such as an epoxy resin, and the mixed material is applied onto the insulating layer 1b, whereby an electrode layer in which a large number of minute electrodes are uniformly dispersed. 1c can be easily formed. Metal powder such as copper can also be used as the material of the microelectrode. In addition, as a dispersion medium material that disperses these in an electrically insulated state from each other, acrylic-based, urethane-based, styrene-based, acrylic-urethane-based,
Although a wide range of materials such as epoxy-silicon or epoxy-Teflon-based materials can be used, it is required that the triboelectrification series for the toner used is separated so that the toner as a developer can be triboelectrically charged efficiently.

As described above, by forming the electrode layer 1c in which the microelectrodes are dispersed as the surface layer of the developing sleeve 1, even when using a one-component toner, it is preferable due to the edge effect that the image density is selectively increased in the line image. It is possible to obtain excellent developing characteristics. In addition, since an insulating material such as an epoxy resin in which a low resistance substance such as carbon black is dispersed as a microelectrode has a better adhesiveness with a toner than a metal or the like, a special material such as a non-magnetic one-component toner is used. It is possible to carry and carry a sufficient amount of a developer which does not involve a carrying force such as a magnetic force.
The conductive substrate 1a is connected to the bias power source 11 at the same potential as that of the charge removal brush 10 described later. Further, the insulating layer 1b is provided in order to maintain the electric field strength suitable for development, and can be omitted if necessary.

In this example, a hopper 2 for storing the developer is formed on the right side of the developing sleeve 1 in the drawing. 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 replenished toward the hopper 2 by natural dropping. In the hopper 2, an agitator 4 that sends out toward the surface of the developing sleeve 1 while preventing toner aggregation is rotatably arranged.

On the outlet side of the hopper 2 that supplies toner to the developing sleeve 1, a toner supply member 5 that promotes the movement of the toner onto the surface of the developing sleeve 1 is provided. The toner supply member 5 is rotatably supported at a position where the surface of the toner supply member 5 can be pressed against the surface of the developing sleeve 1. It is desirable that the toner supply member 5 be driven and rotated in the same direction as the developing sleeve 1. That is, it is preferable that both surfaces of the contact portion C move in opposite directions while being pressed against each other. As a result, the toner is squeezed between both surfaces to be efficiently triboelectrically charged, the layer thickness is regulated, and a toner layer having an appropriate layer thickness is adhered and formed on the surface of the developing sleeve 1. In this case, the preferable peripheral speed of the surface of the toner supply member 5 varies depending on the peripheral speed of the developing sleeve 1, but as a whole, the peripheral speed is set higher than that of the developing sleeve 1, and the surface of the developing sleeve 1 and the toner supplying member 5 are set. It is preferable that the surface rotates while sliding on the surface. However, if the speed is set to an excessively high speed, side effects such as toner scattering, toner sticking in the bearing portion, and toner aggregation in the hopper 2 are promoted, so that it is required to be set within an appropriate range.
It is desirable that the material of the surface portion of the toner supply member 5 is away from the toner by a triboelectric charging series in order to efficiently triboelectrically charge the toner.

In this example, the degree of foaming is preferably the number of cells on the peripheral surface of the core metal 5a.
A sponge roller 5 coated with a surface layer 5b made of a flexible material such as polyurethane foam of 10 to 100 is disposed so as to be rotatable in the same direction as the developing sleeve 1 while being pressed against the surface of the developing sleeve 1. There is. In this case, the diameter is 25.4 mm
While the developing sleeve 1 is rotated at a speed of 400 rpm, the sponge roller 5 having a diameter of 14 mm is rotated at 800 rpm, and the ratio of the peripheral speeds of the two is set to about 10:11.
In order to convey a proper amount of toner to the contact portion C and form a suitable toner thin layer on the surface of the developing sleeve 1, it is preferable that the flexible material has a high hardness and a small hole diameter.

By providing the toner supply member 5 as described above, the toner stored in the hopper 2 and sent out together with the rotation of the agitator 4 moves following the rotation of the toner supply member 5 and smoothly contacts the contact portion C. Be transferred. In the contact portion C, the toner transferred between the surfaces of the developing sleeve 1 and the toner supply member 5 moving in opposite directions is pinched, and at this time, the toner is triboelectrically charged and the toner is transferred to the surface of the developing sleeve 1. It is attached. In this case, the force that causes the toner to follow the rotation of the toner supply member 5 mainly involves an electrostatic force due to friction between the toner and the toner supply member 5. Therefore, even if the developer is a non-magnetic one-component toner containing neither carrier nor magnetic substance, it can be smoothly conveyed and supplied from the hopper 2 to the surface of the developing sleeve 1.

Further, as shown in FIG. 3, a member such as a roller 5c for preventing clogging by toner may be slidably disposed at a proper position on the peripheral surface. As a result, it is possible to avoid a decrease in triboelectric charging efficiency due to clogging of the sponge roller 5.

The toner supply member 5 is provided along the rotation direction of the developing sleeve 1.
A doctor blade 8 is provided on the downstream side of the developing roller 1 to regulate the thickness of the toner layer formed on the surface of the developing sleeve 1 and conveyed along with the rotation of the developing sleeve 1. The doctor blade 8 of this example is formed by applying an insulating film 8b made of a fluororesin such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) to one side surface of a main body 8a made of an elastic member. The tip of the insulating film 8b is pressed against the surface of the developing sleeve 1 to regulate the toner layer thickness. In this case, by bringing the tip edge portion 8c of the doctor blade 8 into contact with the surface of the developing sleeve 1, the layer thickness of the toner can be uniformly regulated over substantially the entire required range in the width direction of the developing sleeve 1. It is possible to stably form a thin toner layer having a uniform thickness. The insulating film 8b is provided to prevent toner from sticking and to improve charging characteristics.By using a fluorine-based material as in this example, toner sticking is more effectively prevented and frictional charging is prevented. Be implemented.

As the layer thickness regulating member, in addition to PFA described above, polytetrafluoroethylene (TFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE), poly Fluoropolymer materials such as chlorotrifluoroethylene (CTFE) and materials containing fluoropolymer materials, and
A material having high releasability from toner such as polyethylene, polypropylene or silicone resin is preferable. Further, these materials may contain additives such as carbon black, carbon fibers, glass fibers, silica fine powder, and SiC fine powder in order to improve wear resistance.

An endless organic photoconductor belt (OPC belt) as a latent image carrier rotatably stretched at an appropriate position on the downstream side of the doctor blade 8 in the rotational movement path of the developing sleeve 1.
A part of 9 and the surface of the developing sleeve 1 are in rolling contact with each other to form a developing area D. The electrostatic latent image formed on the surface of the OPC belt 9 through the steps of uniform charging and image exposure at appropriate places is conveyed to the developing area D along with its rotation. In the developing area D, a thin toner layer whose layer thickness is regulated by the doctor blade 8 and which has been triboelectrically charged with a sufficient charge is used as the developing sleeve 1.
It is carried on the surface of and transported. In this case, since the electrode layer 1c on the surface portion of the developing sleeve 1 is formed of an insulating material such as epoxy resin to which toner easily adheres as described above, a special carrying force for non-magnetic one-component toner or the like is set. Even undeveloped developer can be carried and carried evenly on the entire peripheral surface. Accordingly, a thin toner layer having a sufficient charge and a uniform layer thickness is stably supplied to the electrostatic latent image formed on the OPC belt 9, and the latent image is uniformly visualized.

On the downstream side of the developing area D along the rotation direction of the developing sleeve 1, a charge eliminating brush 10 for removing unnecessary electric charges accumulated on the surface of the developing sleeve 1 is arranged. Development sleeve 1
On the surface, toner supply member 5, doctor blade 8 and OP
Due to friction with the C-belt 9 and the like, there is a tendency that electric charges having a polarity unnecessary for development are accumulated. Since this unnecessary electric charge causes image defects such as background stains and streaks, it is required to surely remove it. In particular, charges accumulated in an insulating material such as an epoxy resin, which is a material of the electrode layer 1c of the developing sleeve 1, are more difficult to remove than in the case of metal or the like, and an efficient charge eliminating means is required. In this example, the length and material of the conductive brush bristles 10a and the mounting position of the static elimination brush 10 are set so that the tip abdomen of the conductive brush bristles 10a can come into contact with the surface of the developing sleeve 1 with an appropriate pressure due to its elasticity. . As a result, the brush bristles 10a can uniformly contact the required area of the surface of the developing sleeve 1 in the width direction, and a good charge removal effect without charge removal unevenness can be obtained. The static elimination brush 10 is the developing sleeve 1 described above.
Is connected to the bias power source 11 at the same potential as that of the conductive substrate 1c. As a result, unnecessary accumulated charges on the surface of the developing sleeve 1 and charges of the residual toner not used for development can be selectively and efficiently removed. Thus, the residual toner, which has been subjected to the static elimination treatment to eliminate the electrostatic adhesive force, is conveyed to the position where the toner supply means 5 is arranged as the developing sleeve 1 rotates, and is detached from the surface of the developing sleeve 1 to be used in a new developing process. To be done. In this example, since the sponge roller 5 as a toner supply member is rotated in a pressure contact state, the residual toner conveyed is easily and efficiently scraped off the surface of the developing sleeve 1. That is, the sponge roller 5
Is in pressure contact with the developing sleeve 1 and is in a surface contact state over a proper length by flexing, and the toner carried and conveyed by the roller 5 on the upstream side with respect to the rotating direction of the roller 5 at the contact portion C is conveyed. Is regulated to adhere to the surface of the developing sleeve 1, but on the downstream side, an effect of scraping off the residual toner adhered to the surface of the developing sleeve 1 is exerted. The scraped toner is returned to the inside of the hopper 2 as the roller 5 rotates, and is reused. Although the non-magnetic one-component toner is used as the developer, the present invention is not limited to this, and the present invention can be applied to a developing device using a magnetic toner.
Further, the present invention can be applied to a drum type latent image carrier having rigidity such as a photosensitive drum. In addition, the doctor blade 8 may be formed of an elastic magnetic material, and the doctor blade 8 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.

Effects As described above in detail, according to the present invention, it is possible to favorably charge the developer conveyed to the pressure contact portion between the developer conveying roller and the developer supply means at the pressure contact portion. In that case, in the present invention, since the surface of the developer supplying means is made of a flexible porous material, the developer can be satisfactorily conveyed to the pressure contact portion through the holes. Furthermore, since the developer supplying means is moved at a speed faster than the developer conveying roller, it is necessary to supply a sufficient amount of developer to the press contact portion with respect to the amount of developer conveyed by the developer conveying roller. It is possible. Further, since holes are provided on the surface of the developer supplying means, it is ensured that the developer accumulated in these holes rubs against the developer carrying roller and is sufficiently frictionally charged. Further, since the surface of the developer supplying means is made of a flexible porous material, the flexibility causes the developer to be pressed against the developer conveying roller, which results in good triboelectrification. Is promoting that. Further, in the present invention, since the layer thickness regulating means is provided, even if a sufficient amount of the developer is conveyed by the developer conveying roller, the layer thickness regulating means regulates the layer thickness to an appropriate amount, thereby achieving high quality. Development can be performed. The present invention is not limited to the above-mentioned specific embodiments, and it goes without saying that various modifications can be made within the technical scope of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic view showing one embodiment of the present invention, FIG. 2 is an explanatory view showing a part of one embodiment of the present invention, and FIG. 3 is a toner supply member 5 in one embodiment of the present invention. It is explanatory drawing which showed the modification of this. (Explanation of symbols) 1: Development sleeve 5: Toner supply member (sponge roller) 8: Doctor blade

Front page continuation (72) Inventor Hidetoshi Yano 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Rybun Kiyomiya 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Kikei Tarumi 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (56) References JP 59-126567 (JP, A) JP 59-231560 (JP, A) ) JP-A-56-14260 (JP, A)

Claims (1)

[Claims] 1. A developing device for supplying a latent image bearing member with a thin layer of the developer to visualize the latent image, wherein the developer is conveyed along a predetermined circulation path including a developing area. The roller and the surface portion are made of a flexible porous material, and while being in pressure contact with the developer transport roller, in this pressure contact portion in a direction opposite to the moving direction of the developer transport roller, The developer supply means that moves and rotates at a high speed, and the pressure contact portion between the developer transport roller and the developer supply means is provided upstream of the developer supply means in the rotational direction of the developer supply means. It has a developer storage means and a layer thickness control means for controlling the layer thickness of the developer on the developer transport roller, and the developer stored in the developer storage means is pressed against the developer by the developer supply means. Developer that has been transported to Frictionally charged at the pressure contact portion, a developing device, characterized in that.