JPS61156167A - Developing device - Google Patents

Abstract

PURPOSE:To prevent an undesirable condition where a newly supplied developing agent is not mixed with an already existing developing agent and to be directly used for layer thickness control and to improve the quality of a picture, by providing a partitioning member to a developing agent supplying member. CONSTITUTION:A partitioning member 6 is provided in a hopper 2 for storing a developing agent in such a way that the member 6 is contacted with the upstream side peripheral surface of the contacting section C of a front toner supplying roller 5 and the member 6 prevents an undesirable condition where a newly supplied toner dropped from a toner cartridge 3 onto the receiving section 2b of the hopper 2 is directly supplied to the upstream side location U of a doctor blade 7 on a developing sleeve 1 without passing through the toner supplying roller 5. The partitioning member 6 is formed of a fluorine- containing material which is excellent in noncohesiveness so as to prevent adhesion of toner to the member 6. Therefore, an appropriate quantity of toner can be supplied onto the developing sleeve 1 by previously controlling the layer thickness of toner carried by the rotation of the roller 5 to a uniform thickness.

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 non-magnetic one-component developer.

Traditionally, the dry developing methods used for electrophotography and electrostatic recording include methods that use two-component developers containing toner and carrier, and methods that use one-component developers that do not contain 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 mixing ratio of toner and carrier tend to occur, making it difficult to maintain and manage the device and make it more compact. 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 to thin layer thickness in order to uniformly impart sufficient charge to the developer. For this reason,
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. When the layer thickness regulating effect is reduced, it becomes difficult to sufficiently perform the triboelectric charging effect. Therefore, in such a case, if the newly supplied developer, etc. whose charge amount is not yet stable, is not mixed well with the existing developer and is short-circuited and supplied to the layer thickness regulating section, the old and new developer may be There are strong differences in characteristics such as particle size distribution and triboelectricity, and in particular, the triboelectricity of the newly replenished developer is insufficient, and the amount of charge on the thin layer of developer formed on the developer transport body is significant. becomes uneven. As a result, image defects such as fogging, background afterimages, trailing, or streaks occur, and the quality of one image deteriorates.

1-1 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 amount of charge, and stably maintaining high image quality. An object of the present invention is to provide a developing device that can be obtained.

1-1 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. It is equipped with a developer transport body that transports the developer along a circulation path, and a receiving part that mixes the replenished developer with the existing developer. developer supplying means for supplying an appropriate amount onto the developer conveying body through the developer;
a layer thickness regulating member disposed on the downstream side of the developer supplying means with respect to the developer conveying direction, and regulating a layer thickness of the developer being conveyed by bringing a part into pressure contact with the surface of the developer conveying body; and the developer is disposed near the supply section in the developer supply means, and the replenished developer is supplied to the upstream side of the developer layer thickness regulating member in a short circuit without undergoing a mixing action in the receiving section. The invention is characterized in that it has a partition member that prevents the

The following will specifically explain one embodiment of the present invention. 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 one example, it is rotationally driven in the direction of the arrow at a predetermined speed. As shown in FIG. 2, the developing sleeve 1 has an insulating layer 1b made of an insulating material such as chloroprene deposited on the circumferential surface of a sleeve-shaped conductive substrate 18 made of aluminum, etc., and a number of electrodes are further formed on the insulating layer 1b made of an insulating material such as chloroprene. The electrode layer 1c is formed by stacking layers 1c of particles 1c dispersed in an electrically insulated state. In this case, 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 source 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, a hopper 2 for storing developer is formed on the right side of the developing sleeve 1 in the figure. The developer used in this example is a non-magnetic one-component toner that does not contain a carrier made of a single 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 falling toward the receiving portion 2b inside. Inside the receiving portion 2b, there is an agitator 4 that sends the toner toward the surface of the developing sleeve 1 while preventing the toner from agglomerating.
is rotatably arranged.

A toner supply roller 5 that promotes the movement of toner onto the surface of the developing sleeve 1 is disposed on the exit side of the thread collar 2 that supplies toner to the developing sleeve 1 . 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, at the contact portion C, it is preferable that both surfaces move in opposite directions while being in pressure contact.As a result, the toner is sandwiched between both surfaces and is efficiently triboelectrified, and the layer thickness is regulated and the toner is appropriately charged. A single layer of toner having a thickness of about 100 mL is deposited on 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 with a diameter of 25.4 ms is rotated at a speed of 40 Orpm, while the sponge roller 5 with a diameter of 14 mm is rotated at a speed of 80 Orpm, and the ratio of their circumferential speeds is approximately 10: It is set to 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.

Therefore, near the toner supply roller 5 in the hopper 2,
As shown in FIG. 3, the partition member 6.

The distal end thereof is disposed in contact with the upstream circumferential surface of the contact portion C of the toner supply roller 5 . Due to this.

New replenishment toner dropped from the toner cartridge 3 into the receiving portion 2b of the hopper 2 is delivered to a position U on the upstream side of the position on the developing sleeve 1 where a doctor blade, which will be described later, is disposed, without passing through the toner supply roller 5. The inconvenience of direct supply is prevented. The partition member 6 of this example is made of a fluorine-containing material that contains fluorine and has excellent non-adhesive properties (mold releasability). In this case, the fluorine-containing materials include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PF
A), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE), polychlorotrifluoroethylene (CTFE), etc. are suitable.

By forming the partition member 6 from a fluorine-containing material as in this example, toner is prevented from adhering to the partition member 6. Therefore, the layer thickness of the toner conveyed as the toner supply roller 5 rotates can be preliminarily regulated to be uniform, and an appropriate amount can be supplied onto the developing sleeve 1. Further, when the fluorine-containing material and the toner of this example are rubbed, the toner is charged to a positive polarity, so that it is suitable as a developing device for an organic photoreceptor belt or the like that forms a latent image of negative polarity, as described later. Furthermore, since the frictional resistance with the toner supply roller 5 is reduced, the rotational torque of the toner supply roller 5 is reduced, contributing to labor saving of the developing device. Note that the partition member 6 does not necessarily need to be brought into contact with the surface of the toner supply roller 5, and may simply be brought close to its tip so that the desired layer thickness regulation effect can be obtained.

By providing the toner supply roller 5 and the partition member 6 as described above, the new toner replenished into the receiving portion 2b of the hopper 2 is mixed and agitated with the existing toner as the agitator 4 rotates, and then the toner is supplied. It moves following the rotation of the roller 5, and is smoothly transferred to the contact portion C through preliminary layer thickness regulation and frictional charging treatment by the partition member 6. At the contact portion C, the toner transferred between the surfaces of the developing sleeve 1 and the toner supply roller S, which 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. 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 component toner containing neither carrier nor magnetic material, it can be smoothly transported and supplied from the hopper 2 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. As shown in FIG. 3, the doctor blade 7 in this example has a main body 7a made of an elastic member, and one side surface of the main body 7a is made of, for example, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). It is formed by depositing an insulating film 7b made of a fluorine-containing material that forms the partition member 6 described above,
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. Further, the insulating film 7b is provided to prevent toner from sticking and to improve charging characteristics.
By using a fluorine-containing material as in this example, toner adhesion can be more effectively prevented and desired triboelectric charging can be achieved.

By the way, in this case, since the fluorine-containing material is insufficient in terms of wear resistance, the abutment tip 7c tends to wear out as one-layer thickness regulation is implemented over a long period of time, and the layer thickness regulation effect tends to decrease. As described above, a certain decrease in the six-layer thickness regulation effect causes non-uniformity in the charge of the thin toner layer, leading to various image defects. However, in the present invention, the partition member 6 is provided, thereby preventing the inconvenience that new replenishment toner with unstable charge is directly supplied to the upstream side of the doctor blade 7. Therefore, even if the layer thickness regulating effect of the doctor blade 7 decreases, the toner has undergone preliminary frictional charging treatment between the partition member 6 and the toner supply roller 5 and the contact portion C, so that the required amount of charge is maintained. is ensured and the occurrence of image defects is prevented.

Note that the entire layer thickness regulating member may be formed of a fluorine-containing material. In addition to the above-mentioned PFA, materials for the insulating film 7b or the layer thickness regulating member main body 7a include polytetrafluoroethylene (TFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-ethylene. Fluorine-based polymer materials such as copolymers (ETFE) and polychlorotrifluoroethylene (CTFE), and materials containing fluorine-based polymer materials, as well as polyethylene, polypropylene, silicone resins, and other materials that have release properties against toner. High quality materials are preferred.

In addition, in order to improve the wear resistance of these materials, carbon black, carbon fiber, glass fiber, silicate fine powder, S
Additives such as iC fine powder may also be included.

Returning to FIG. 1, an endless organic photoreceptor belt (OPC belt) 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. ) 8 and the surface of the developing sleeve 1 come into contact with each other to form a developing area. The electrostatic latent image formed on the surface of the PC belt 8 through the steps of uniform charging and image exposure at a proper location is conveyed to the development area as the belt rotates.

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 evenly on the entire circumferential surface. Therefore, a thin toner layer having sufficient charge and having 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 electric charge accumulated in the insulating material such as epoxy resin, which is the material of the electrode layer 1c of the developing sleeve 1, is more difficult to remove than in the case of metal, and an efficient charge removal method is required. In the example, the length, material, and mounting position of the static elimination brush 9 are set so that the tip 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 remaining toner whose electrostatic adhesion force has been weakened after the static elimination process is conveyed again to the location of the toner supply means 5 as the developing sleeve 1 rotates, where it is detached from the surface of the developing sleeve 1. Subjected to a new development process. In this example, since the sponge roller 5 as a toner supply roller is rotated while being pressed against the surface of the developing sleeve 1, the residual toner that has been conveyed can be easily and efficiently scraped off from the surface of the developing sleeve 1. That is, the sponge roller 5 is pressed against the developing sleeve 1 and bent, and is in surface contact over a suitable length, and as described above, the sponge roller 5 is supported on the roller 5 at the upstream side with respect to the rotational direction of the roller 5 at the contact portion C. The toner that is conveyed 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 residual toner that has adhered to the surface of the developing sleeve 1. The toner that was scraped off.

As the roller 5 rotates, it is returned to the hopper 2 for reuse.

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 main body 7a of the doctor blade 7 may be made of an elastic magnetic material, and the tip edge portion 7c of the doctor blade 7 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 in detail above, according to the present invention, by providing a partition member in the developer supplying means for supplying the stored developer onto the developer conveying member, the newly replenished developer This prevents the inconvenience of directly controlling the layer thickness without being mixed with the developer. Therefore, even if the layer thickness regulating effect deteriorates due to wear of the single layer thickness regulating member, the charge necessary for development can be charged, and image defects such as streaks and fog may occur due to insufficient charging of the developer. This prevents this and allows stable and high image quality to be obtained. 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.

[Brief explanation of the drawing]

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 according to one embodiment of the present invention, and FIG. 3 is a schematic diagram showing one embodiment of the present invention. FIG. 3 is an explanatory diagram showing main parts. (Explanation of symbols) 1: Developing sleeve 2: Hopper 5: Toner supply roller (sponge roller) 6: Partition member 7: Doctor Blade Patent applicant Rico Co., Ltd.
Masaaki Kobashi - 11th
] Figure 2 Figure 3

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. The developer is provided with a developer conveying body and a receiving part for mixing the replenished developer with the existing developer, and the developer is supplied from the receiving part to the developer in an appropriate amount through a supplying part close to the developer conveying body. A developer supplying means for supplying the developer onto the conveying body, and the developer is disposed downstream of the developer supplying means with respect to the developer conveying direction, and is conveyed with a part pressed against the surface of the developer conveying body. A layer thickness regulating member for regulating the layer thickness of the developer, and a layer thickness regulating member disposed near the supply section in the developer supply means so that the replenished developer does not pass through the mixing action in the receiving section and is disposed in the vicinity of the supply section in the developer supply means. A developing device comprising: a partition member that prevents developer from being supplied upstream of a developer layer thickness regulating member. 2. In the above item 1, the developer supply means includes a supply roller whose surface portion is coated with a flexible material, and the tip of the partition member is close to or in contact with the surface of the supply roller. A developing device characterized by: 3. The developing device according to item 1 or 2 above, wherein the partition member is made of a fluorine-containing material. 4. The developing device according to any one of the above items 1 to 3, wherein at least a portion of the developer layer thickness regulating member in pressure contact with the surface of the developer transporting member is made of a fluorine-containing material.