JPS61156169A - Developing device - Google Patents

Abstract

PURPOSE:To prevent an undesirable condition where a thin layer of a developing agent of uneven thickness is supplied for development under the uneven condition and to improve the quality of a picture, by providing a thickness uniformizing member at the downstream side of a thickness controlling member in the developing agent carrying direction. CONSTITUTION:The 1st doctor blade 6 is provided as a thickness controlling member at the downstream side of a toner supplying roller 5 in the direction, in which toner is carried, and the thickness of the toner layer carried by a developing sleeve 1 is controlled. At the same time, the doctor blade 6 frictionally charges the toner layer with necessary electric charges and forms a thin layer of toner. The 2nd doctor blade 7 is provided as a thickness uniformizing member at the downstream side of the 1st doctor blade 6 and the thickness of the toner thin layer is uniformized so as to obtain a toner thin layer which is suitable for development. The 2nd doctor blade 7 is made of a fluorine-containing resin which is excellent in noncohesiveness and, even when streaks, etc., are produced on the surface of the toner layer by toner firmly adhering to the 1st doctor blade 6 or a clogging foreign matter, the streaks, etc., are erased by the 2nd doctor blade 7 and a toner thin layer of a uniform thickness can be obtained stably.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry developing device, and more particularly to a developing device suitable for a developing method using a -component developer.

Conventional dry development methods used for electrophotography, electrostatic recording, etc. include methods that use a two-component developer containing toner and carrier, and methods that use a single-component developer that does not contain a carrier. There is a way. 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, one-component developers that do not have the above-mentioned drawbacks are attracting attention. - When using a component-based developer, it is required to stably form a thin layer of the developer with a uniform thickness in order to uniformly impart sufficient charge to the developer. For this reason 1
Normally, a method is adopted in which a one-layer thickness regulating member is pressed against the surface of the developer transporter and the developer is compressed between them to mechanically regulate the layer thickness. Since the developer is brought into pressure contact with the surface of the developer transporting member, the pressure contact surface tends to wear out over time and the layer thickness regulating effect tends to deteriorate. As a countermeasure for this, if the layer thickness regulating member is made of a material with excellent wear resistance in order to suppress wear, the developer may stick to the pressure contact surface of the layer thickness regulating member or the developer may If paper powder or dust mixed in is caught in the pressure welding part, it becomes impossible to achieve a uniform layer thickness regulation effect. If the layer thickness regulation effect decreases or becomes uneven, the layer thickness cannot be made uniform enough to respond to fluctuations in developer supply amount, etc., and streaks or the like occur in the formed developer thin layer. As a result, image defects such as white stripes occur, and image quality deteriorates.

The present invention has been made in view of the above points, and is capable of constantly forming a thin layer of developer with a uniform layer thickness while imparting the necessary electrical charges, and stably maintaining high image quality. An object of the present invention is to provide a developing device that can be obtained.

In order to achieve the above 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. and a developer transport body that transports the developer along the path.

a developer supply means for storing developer and supplying an appropriate amount of developer onto the developer transport body; The developer is conveyed while being pressed against the surface of the agent conveying body.
a layer thickness regulating member for forming a thin developer layer by regulating the layer thickness of the layer, and a layer thickness regulating member disposed downstream of the layer thickness regulating member to equalize the layer thickness of the thin developer layer being conveyed. It is characterized by having a layer thickness uniformizing member.

The present invention will be specifically described below based on two embodiments. 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 rotationally driven in the direction of arrow A at a predetermined speed. The developing sleeve 1 is as shown in FIG.

An insulating layer 1b made of an insulating material such as chloroprene is deposited on the circumferential surface of a sleeve-shaped conductive substrate 1a made of aluminum, etc., and a large number of electrode particles 1 cm in length are further dispersed thereon in an electrically insulated state from each other. The electrode layer 1c is laminated,
It is configured. In this case, 1. For example, a conductive material such as carbon black is uniformly dispersed and mixed into an insulating material such as an epoxy resin.

By applying this mixed material on the insulating layer lb, it is possible to easily form an electrode layer IC in which a large number of microelectrodes are uniformly dispersed. Metal powders such as copper can also be used as the material for the microelectrodes. 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 possible to support and transport a sufficient amount of developer even if no supporting force such as magnetic force is provided. The conductive substrate 1a is connected to a bias power supply 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.

The developer used in this example, in which a hopper 2 for storing developer is formed, is a non-magnetic one-component toner that does not contain a carrier made of ferromagnetic material.

A replenishment port 2a is formed in the upper part of the hopper 2, and a cartridge 3 filled with toner is installed in the replenishment port 2a, and the hopper 2
New toner is replenished by natural fall. 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 disposed. The toner supply roller 5 is rotatably supported at a position where its surface can be brought into pressure contact with the surface of the developing sleeve 1, and the direction of rotation thereof is preferably the same as that of 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.

In this case, the preferable circumferential speed of the surface of the toner supply roller 5 varies depending on the circumferential speed of the developing sleeve 1, and overall it is preferable to set it to a higher speed than the developing sleeve 1.
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. Further, the material of the surface portion of the toner supply roller 5 is selected in order to efficiently charge the toner by friction.

It is desirable that the triboelectric charging series be separated from the toner.

In this example, the sponge roller 5 has a surface layer 5b made of a flexible material such as polyurethane foam, preferably having a foaming degree of 10 to 100 cells, attached to the surface of the core bar 5a, and the developing sleeve 1 It is disposed so as to be rotatably driven in the same direction as the developing sleeve 1 while being in pressure contact with the surface. In this case, the developing sleeve 1 having a diameter of 25.4 mm is rotated at a speed of 400 rpm, while the sponge roller 5 having a diameter of 14 s+m is rotated at a speed of 800 rpm, and the ratio of their circumferential speeds is as follows.

It is set at approximately 10:11. Incidentally, in order to convey an appropriate 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 better that the flexible material has a higher hardness and a smaller hole diameter.

By providing the toner supply roller 5 as described above, the new toner supplied to the hopper 2 is mixed and agitated with the existing toner as the agitator 4 rotates, and then smoothly follows the rotation of the toner supply roller 5. is transferred to the contact portion C. ° 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 transferred to the surface of the developing sleeve 1. It is attached to.

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, the developer is non-magnetic, containing neither carrier nor magnetic material.
Even if it is component-based toner, it is necessary to transfer it from hopper 2 to developing sleeve 1.
It can be smoothly transported and supplied to the surface.

A first doctor blade 6 as a layer thickness regulating member is disposed on the downstream side of the toner supply roller 5 in the toner conveyance direction, and regulates the layer thickness of the toner carried on the developing sleeve 1 and conveyed. The first doctor blade 6 in this example is made of a material with excellent wear resistance such as steel, and as shown in FIG. The edge portion 6a is evenly pressed against substantially the entire surface of the developing sleeve 1 in the width direction, and the toner is pinched during this time to sufficiently triboelectrically charge the necessary charge. Note that the first doctor blade 6 may have its side abdomen pressed against the surface of the developing sleeve 1.

A second doctor blade 7 as a layer thickness equalizing member is disposed at a position downstream of the first doctor blade 6 and separated by an appropriate length, and the second doctor blade 7 serves as a layer thickness equalizing member. The thickness of the thin layer is made uniform to create a thin toner layer suitable for development.

The second doctor blade 7 of this example has a non-adhesive property (
It is made of an elastic film member made of a fluorine-containing resin, which is a material that has excellent mold releasability (mold releasability) and belongs to the triboelectrification series that triboelectrically charges the toner to a positive polarity. The side surface abdomen 7a of the developing sleeve 1 is pressed evenly over substantially the entire surface of the developing sleeve 1 in the width direction, and is supported in the trailing direction with respect to the toner movement direction. Therefore, even if toner sticks to the first doctor blade 6 or foreign matter gets stuck and streaks occur in the thin toner layer,
Since the second doctor blade 7 maintains a smooth pressure contact surface without toner sticking for a long period of time, it is possible to eliminate streaks and the like and to stably obtain a thin toner layer with a uniform layer thickness. Furthermore, since this example uses an organic photoreceptor belt that forms an electrostatic latent image of negative polarity as described later, it is required to uniformly triboelectrically charge the thin toner layer to positive polarity. By finally applying frictional charging with the blade 7, the charging polarity of the thin toner layer can be made uniform from the frictional charging series, and this requirement can be fully met. still,
Suitable materials for the second doctor blade 7 include, in addition to fluorine-containing resin films, metal elastic bodies, plastic films such as polyester, polyamide, polyimide, and nylon, silicone rubber, urethane rubber, fluororubber, and EP.
There are rubber materials such as DM. Also, the second doctor blade 7
The developing sleeve 1 may be supported in the counter direction and its abdomen or tip edge portion may be pressed against the surface of the developing sleeve 1 with an appropriate pressure.

At a suitable position on the downstream side of the second doctor blade 7 in the rotational movement path of the developing sleeve 1, an endless organic photoreceptor belt (OPC) serving as a latent image carrier is stretched so as to be able to rotate once.
A part of the belt) 8 and the surface of the developing sleeve 1 come into contact with each other,
A developing area is formed. The electrostatic latent image formed on the surface of the OPC belt 8 through the steps of uniform charging and image exposure at a proper location and consisting of negative polarity charges is conveyed to the development area as it rotates. In the development area, a thin toner layer is formed in which a desired polarity of charge is evenly and sufficiently applied due to the cooperative effect of the first doctor blade 6 and the second doctor blade 7, and the layer thickness is reliably made uniform. is carried on the surface of the developing sleeve 1 and transported, and a thin layer of the toner, which has been finished suitable for development, is stably supplied to the electrostatic latent image formed on the oPC belt 8, and the toner is uniformly latent. The image is visualized.

Therefore, it is possible to stably obtain high-quality images without white lines or the like.

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
On the surface, there are a toner supply roller 5 and a first doctor blade 6.
．． Second doctor blade7. and ◯ Due to friction with the PC belt 8 and the like, charges with polarities unnecessary for development tend to accumulate. Since this unnecessary charge causes image defects such as background stains and streaks, it is required to remove it reliably. In particular, the electrode layer 1 of the developing sleeve 1
Charges accumulated in an insulating material such as epoxy resin, which is the material of c, are more difficult to remove than in the case of metals, and an efficient charge eliminating 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 1a of the developing sleeve 1 described above. Thereby, unnecessary accumulated charges on the surface of the developing sleeve 1 are selectively and efficiently removed. In this way, the residual toner whose electrostatic adhesion force has been weakened by the static electricity removal process is conveyed to the location of the toner supply means 5 together with the rotation of the IIi image slipping sleeve.
Here, it is detached from the surface of the developing three 91 and subjected to a new developing process. In this example, since the sponge roller 5 as a toner supply roller is rotated in pressure contact, the remaining toner that has been conveyed is removed from the developing sleeve 1.
easily and efficiently scraped off the surface. 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 toner being conveyed is regulated and adhered to the surface of the developing sleeve 1.

On the downstream side, it has the effect of scraping off residual toner adhering 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.

Next, another embodiment of the present invention will be described based on the main part explanatory diagram of FIG. 4. Incidentally, the same components as those in the above embodiment are given the same reference numerals, and the explanation thereof will be omitted. In this example, as a layer thickness uniformizing member, an elastic layer 11 made of rubber, sponge rubber, urethane foam, etc. is attached to the rotating shaft 11a.
An elastic roller 11 is formed by fixing the doctor blade 11b to a surface layer 11c made of the same material as that used to form the second doctor blade 7 in the above embodiment on the circumferential surface of the elastic roller 11. One elastic roller 11 provided is rotatably supported at a position where its surface can be pressed against the surface of the developing sleeve 1 with an appropriate pressure. In this case, the rotation direction may be the same direction as the developing sleeve 1 or the opposite direction, taking into consideration the balance with other members so that the thickness of the thin toner layer to be imaged during development can be made uniform in the end. Just set it in a suitable direction.

Further, as the material of the surface layer llc, it is preferable to use a fluorine-containing resin suitable when the organic photoreceptor belt 8 is used. The rest of the structure is the same as in the above embodiment. By arranging the elastic rollers 11 such as 0 or more, it is possible to stably obtain the same layer thickness uniformity effect as the second doctor blade 7 in the above embodiment. , it is possible to stably obtain high image quality.

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 using magnetic toner or magnetic carrier. In this case, since magnetic force is set as the driving force for moving the developer, it is also possible to omit the toner supply roller 5. Further, the present invention is also applicable to a rigid drum-type latent image carrier such as a photosensitive drum. Furthermore, the first doctor blade 6 may be made of an elastic magnetic material and may be brought into pressure contact with the surface of the developing sleeve 1 by the magnetic force of a magnet disposed inside the developing sleeve 1.

Effects As described in detail above, according to the present invention, by arranging the layer thickness equalizing member on the downstream side of the layer thickness regulating member in the developer transport direction, the developer can be thinned even though the layer thickness remains non-uniform. The inconvenience of the layer being subjected to development is avoided. Therefore, it is possible to stably develop a thin layer of developer that is sufficiently triboelectrified with the necessary charge and has a uniform layer thickness, and it is possible to obtain high image quality over a long period of time. . It should be noted that the present invention is not limited to the above-mentioned specific examples.
Of course, various modifications are possible within the technical scope of the present invention.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, FIG. 2 is an enlarged sectional view showing the structure of a developing sleeve 1 in one embodiment of the present invention, and FIG. 3 is a schematic diagram showing one embodiment of the present invention. FIG. 4 is an explanatory diagram showing main parts of another embodiment of the present invention. (Explanation of symbols) 1: Developing sleeve 5: Toner supply roller (sponge roller) 6: First doctor blade 7: Second doctor blade 8: Organic photoreceptor belt 11: Elastic roller Patent applicant Rico Co., Ltd. Kazuyoshi Osamu Man
Masaaki Kobashi −□・・／
1 Ri-1-・ Figure 1 2nd construction

Claims (1)

[Scope of Claims] 1. In a developing device that supplies a thin layer of developer to a latent image carrier and visualizes a latent image, a developer that transports the developer along a predetermined path including a development area. a developer supplying means for storing developer and supplying an appropriate amount onto the developer transporting body; and a developer supplying means disposed on the downstream side of the developer supplying means with respect to a developer conveyance direction. a layer thickness regulating member for forming a thin developer layer by regulating the layer thickness of the developer being conveyed by bringing a portion of the developer into pressure contact with the surface of the developer conveying body; and a layer thickness regulating member disposed downstream of the layer thickness regulating member. A developing device comprising: a layer thickness equalizing member that equalizes the layer thickness of the thin developer layer conveyed by the developer. 2. The developing device according to item 1 above, wherein the layer thickness uniformizing member is made of a material that has excellent non-adhesion with developer. 3. The developing device according to item 1 or 2 above, wherein the layer thickness equalizing member is made of a material having a property of triboelectrically charging the developer to a required polarity.