JPS61156168A - Developing device - Google Patents

Abstract

PURPOSE:To prevent excessive accumulation of developing agent at a layer thickness controlling member in the downstream side area for the direction, in which the develop ing agent is carried, and to improve the quality of a picture, by providing an opening near the front end of the layer thickness controlling member. CONSTITUTION:The downstream side area A of a doctor blade 6 is communicated with the upstream side area A of the doctor blade 6, by piercing rectangular openings 7 at regular intervals along the front edge section 6a2 of the main body 6b, composed of an elastic member, of the doctor blade 6 provided at the downstream side of a toner supplying roller 5 of a developing sleeve 1 in the rotating direction of the sleeve 1. If the front edge section 6a2 is pressure-contacted with the surface of the developing sleeve 1 and toner thickness control is performed, the toner is accumulated in the downstream side area A and, when the toner is accumulated to a certain degree, the toner is automatically returned to the upstream side area A through the openings 7. Thus excessive accumulation of the toner is prevented. Therefore, undesirable conditions, where the charging control of the toner is deteriorated and solidified mass of accumulated toner is carried together with the formed toner thin layer caused by the excessive accumulation of toner in the downstream side area A, can be prevented.

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.

Traditionally, dry developing methods used for electrophotography, electrostatic recording, etc. use two-component developers containing toner and carrier, and one uses one-component developers that do not contain carrier. There is a way. The former method is.

Although relatively stable and good images can be obtained, 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.

Therefore, one-component developers that do not have the above-mentioned drawbacks are attracting attention. - When using a component-based developer, 1. In order to uniformly impart a sufficient charge to the developer, it is required to stably form a thin layer of the developer with a uniformly thin layer thickness. One of the methods is to mechanically regulate the layer thickness by pressing the tip end corner of the 1-layer thickness regulating member against the surface of the developer transporter and squeezing the developer between them. Near the tip of the member, on the surface of the pressure contact part on the downstream side in the developer conveyance direction,
Developer that has passed through the pressure contact area tends to accumulate. If this accumulation of developer is left unattended, it will be difficult to obtain the desired amount of triboelectric charge in the thin layer of developer that is formed, and the developer will grow into lumps, which will be transported to the developing position and imaged. cause defects.

1-Ki The present invention has been made in view of the above points, and is capable of constantly forming a thin layer of a developer with a uniform layer thickness and provided with a necessary amount of charge, thereby stably obtaining high image quality. The purpose of the present invention is to provide a developing device that can.

SUMMARY OF THE INVENTION 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 consists of a developer conveying body that conveys along a path, a developer supplying means for storing developer and supplying an appropriate amount of developer to the developer conveying body, and a plate-like member held at one end and having an opening near the tip. It is characterized by having a layer thickness regulating member which is bored and presses the tip corner portion against the surface of the developer transporting member to regulate the layer thickness of the developer being transported.

The following is a detailed explanation based on five embodiments 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 this example, is rotationally driven in the direction of arrow A 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 coated on the circumferential surface of a sleeve-shaped conductive substrate 1a made of aluminum or the like, and a large number of electrode particles on the insulating layer 1b. 1c, which are electrically insulated from each other, are laminated to form an electrode layer 1G. In this case, for example, by uniformly dispersing and mixing a conductive material such as carbon black into an insulating material such as an epoxy resin, and coating this mixed material on the insulating layer lb, an electrode layer in which a large number of microelectrodes are uniformly dispersed. 1c can be easily formed. 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 also possible to support and transport a sufficient amount of developer that does not involve a supporting force such as magnetic force.

Note that the conductive substrate 1a is connected to a bias power source 11 at the same potential as a static elimination brush 10, which will be described later. Also, insulating layer 1
b is provided to maintain an electric field strength suitable for development, and can be omitted if necessary.

In this example, there is one for each developing sleeve 1, on the right side in the figure.

A hopper 2 is formed to store developer. The developer used in this example is a nonmagnetic 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 it is desirable that the toner supply roller 5 be driven and rotated in the same direction as 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 preferred peripheral speed of the surface of the toner supply roller 5 varies depending on the peripheral speed of the developing sleeve 1, and it is generally preferable to set it to a higher speed than the developing sleeve 1, but if it is set to an excessively high speed, , it is required to be set within an appropriate range because it causes side effects such as toner scattering, toner sticking on the bearing, and promotion of toner aggregation within the hopper 2. It is desirable that the material of the surface portion of the toner supply roller 5 has a frictional charging line distant from the toner in order to efficiently frictionally charge the toner.

In this example, the sponge roller 5, which has a surface layer 5b made of a flexible material such as polyurethane foam, preferably having a foaming degree of 10 to 100 cells, is adhered to the circumferential surface of the core bar 5a. The developing sleeve 1 is disposed so as to be able to be driven and rotated 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 developing sleeve 1 with a diameter of 25.4 mm is rotated at a speed of 400 rpm, while the sponge roller 5 with a diameter of 14+n+ is rotated at 80 Orpm, and the ratio of their circumferential speeds is about 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.

By providing the toner supply roller 5 as described above, the new toner replenished into the hopper 2 is 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 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.

Thus, along the rotational direction of the developing sleeve 1.

A doctor blade 6 as a layer thickness regulating member is disposed on the downstream side of the toner supply roller 5, and as shown in FIG. A thin layer of toner is formed by controlling the thickness of a single layer of toner carried on the surface and conveyed. In the doctor blade 6 of this example, an open lower portion is bored in the vicinity of the tip surface 6a1 of the doctor blade 6, which communicates the downstream region A and the upstream region B of the doctor blade 6. As shown, the distance ΔQ from the tip edge portion 6a of the main body 6b made of one elastic member is preferably about lam.
An appropriate number of rectangular open lowers are bored at equal intervals along the edge line L at the position. The edge portion 6a at the tip of the doctor blade formed in this way is connected to the developing sleeve 1.
By applying pressure evenly over almost the entire width of the surface, the toner layer thickness can be regulated uniformly over almost the entire area and sufficient frictional electrification can be achieved, creating a thin toner layer with a uniform layer thickness and a desired amount of charge. It becomes possible to form stably. That is, by bringing the leading edge portion 6a2 into contact with the surface of the developing sleeve 1 with a required pressure to regulate the layer thickness, there is a tendency for toner to accumulate in the downstream area A as shown in FIG. Then, since the toner is automatically returned to the upstream area B through the open lower door, further accumulation of toner is prevented. Therefore, excessive toner is present in the upstream area A.
This prevents problems such as deterioration of toner charge control and transport of accumulated toner lumps following the formed toner thin layer, and creates a toner thin layer with a uniform layer thickness and a desired charge amount. is stably formed. Incidentally, the opening lowers provided at the tip of the doctor blade may be a suitable number of circular holes as shown in FIG. 5, or a single rectangular opening extending along the edge line L as shown in FIG. between loa′
may be drilled.

At a suitable position on the downstream side of the doctor blade 6 in the rotational movement path of the developing sleeve 1, an endless organic photoreceptor belt (OPC belt) as a latent image carrier is rotatably stretched.
A part of the developing sleeve 8 and the surface 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 a suitable 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 toner layer of M desired thickness, which is uniform in both layer thickness and charge amount, is stably conveyed by the doctor blade 6 provided with the open lower roller, which is formed without contaminating lumps of accumulated toner. and here,
It is 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 6, OPC belt 8, etc., charges with a polarity unnecessary for development tend to accumulate on the surface. Since this unnecessary charge causes image defects such as background stains and streaks, it is required to remove it reliably. In particular, it is more difficult to remove charges accumulated in an insulating material such as epoxy resin, which is the material of the electrode layer 1c of the developing sleeve 1, than in the case of metal, 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. Thus,
After the static electricity removal process, the remaining toner whose electrostatic adhesion has been weakened is conveyed to the toner supplying means 5 as the developing sleeve 1 rotates, where it is detached from the surface of the developing sleeve 1 and used for new development. submitted to the process. In this example, since the sponge roller 5 as a toner supply roller is rotated in a pressure contact state, 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 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.

Next, another embodiment of the present invention will be described based on the main part explanatory diagram of FIG. 7. 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, two doctor blades 11.1 are used as layer thickness regulating members.
The doctor blades 12 on the downstream side are formed of a fluorine-containing resin, for example, which has excellent non-adhesion with toner to prevent toner from sticking, and the doctor blades 12 on the downstream side are formed of a fluorine-containing resin, for example, which has excellent non-adhesion with toner, and The side doctor blade 11 is made of an elastic material with excellent wear resistance so that sufficient frictional electrification is always carried out. Only the upstream doctor blade 11 has an opening 13 in the vicinity of its tip 11a similar to that in the above embodiment. This is the downstream doctor blade 12
This is because toner is supplied with the layer thickness regulated in advance, so excessive load is rarely applied, and there is little risk of toner accumulating in the downstream area C. Therefore, the blade 12 may also be provided with an opening. The other parts are configured the same as in the above embodiment.

Therefore, the toner supplied onto the developing sleeve 1 by the toner supply roller 5 is first subjected to layer thickness regulation by the doctor blade 11. At this time, since the opening 13 is provided, accumulation of toner in the downstream area A is prevented as in the above embodiment, and the desired triboelectric charging effect is exhibited. The toner whose layer thickness has been regulated by the doctor blade 11 is regulated again by the doctor blade 12 on the downstream side, so that the toner is thin enough to have a uniform layer thickness without streaks, etc., and has sufficient electrostatic charge, making it suitable for development. The development area D (first
(see figure). In this case, the toner whose movement is restricted by the blade 12 on the downstream side tends to accumulate between the two blades, that is, in the area A, as shown by the two-dot chain line, but it is smoothly transferred to the upstream area B of the blade 11 through the opening 13. This prevents excessive accumulation.

Furthermore, since the fluorine-containing resin frictionally charges the toner to a positive polarity, the toner thin layer finally formed by the doctor blade 12 is uniformly charged to a positive polarity, and as in this example, the toner thin layer is uniformly charged to a negative polarity. This is advantageous when using an organic photoreceptor belt 8 for forming images. Note that the number of doctor blades to be disposed is not limited to two, and three or more may be disposed in multiple stages along one circumferential surface of the developing sleeve. In this case, as in this example.

If the doctor blade on the most downstream side is formed of a fluorine-containing resin and at least the other doctor blades are provided with an opening at the tip, the doctor blade on the most downstream side can handle the charging including the thickness and polarity of the thin toner layer. It is possible to optimally finish the image and use it for development.

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 port roller 5. Further, the present invention is also applicable to a rigid drum-type latent image carrier such as a photosensitive drum. Furthermore, in the embodiment shown in FIG.

The doctor blade 6 is made of an elastic magnetic material and the developing sleeve 1 is
The distal end edge portion 6a of the doctor blade 6 may be appropriately pressed against the surface of the developing sleeve 1 by the magnetic force of the magnet disposed inside.

Effects As detailed above, according to the present invention, by providing an opening near the tip of the one-layer thickness regulating member, excessive amount of developer in the downstream region of the layer thickness regulating member with respect to the developer conveying direction is prevented. Accumulation can be prevented. Therefore, it is possible to always stably form a thin layer of developer that is charged with a desired charge and has a uniform layer thickness without the inclusion of developer lumps, etc., and it is possible to obtain high image quality over a long period of time. I can do it. It should be noted that the present invention is not limited to the above specific embodiments,
Of course, various modifications are possible 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 explanatory diagram showing the structure of a sleeve 1 in one embodiment of the present invention, and FIG. 3 is a schematic diagram of one embodiment of the present invention. FIGS. 4 to 6 are explanatory views showing modified embodiments of the doctor blade 6 in one embodiment of the present invention, and FIG. 7 is an explanatory diagram showing another embodiment of the present invention. FIG. (Explanation of symbols) 1: IIL image slip sleeve Toner supply roller (sponge roller) 6.11.12: Doctor blade 7.7', 13
: opening

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 of developer to the developer transporting body; and a plate-like member held at one end and having an opening formed near the tip. A developing device comprising: a layer thickness regulating member that brings a corner portion into pressure contact with the surface of the developer transporting member to regulate the layer thickness of the developer being transported. 2. In the above item 1, a plurality of layer thickness regulating members are provided, and at least one of the layer thickness regulating members other than the layer thickness regulating member disposed on the most downstream side with respect to the developer conveyance direction is provided. A developing device characterized in that the opening is formed near each tip of the member. 3. The developing device according to item 2 above, wherein at least a portion of the layer thickness regulating member disposed on the most downstream side that is in pressure contact with the developer conveying member is made of a fluorine-containing resin.