JPS6199174A - Method and device for non-contact development - Google Patents

Abstract

PURPOSE:To prevent the scattering of a suspended toner from a developing device to the outside by constituting the device in such a manner that the inflow of air from the upper stream of a developing region is prohibited. CONSTITUTION:The developer P stuck to a rotary sleeve 2 is formed on a developer layer D by a plate 4 for controlling the quantity of the developer and is conveyed to the developing region A. The toner scattered from the layer D by the alternating electric field generated by a bias power source 9 sticks onto a rotary drum type photosensitive body 1, thus developing the electrostatic latent image. A sealing member S1 to close the gap between the body 1 and the upper frame member B of the developing device is provided on the upper stream of the developing area A and therefore the movement of the suspended toner to the outside of the developing device is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides an image carrier in which an image is developed by toner flying from a developer layer on a developer layer carrier in a non-contact state by the action of an electric field. This invention relates to a non-contact developing method and its device. In particular, the present invention relates to a non-contact developing method and device that can prevent floating toner from scattering outside the developing device and contaminating the image forming device.

(Prior Art) Conventionally, an image carrier is in a non-contact state in a developing area, that is, in a steady state where the potential difference between the surface of the image carrier and the developer layer carrier is O. In the non-contact development method, in which the gap between the image carrier and the developer layer is set larger than the thickness of the developer layer, the image is developed by toner flying from the developer layer by the action of an electric field. Compared to a contact development method such as a cascade method or a magnetic brush method in which the toner is developed by contact, the toner is developed as a powder cloud, so it is possible to obtain a good toner image without directionality. However, while toner with a sufficient amount of charge flies from the developer layer due to the action of an electric field and is used for development, toner with a small amount of charge is not used for development and floats, scattering outside the developing device and forming an image. There was a problem that the forming apparatus was contaminated.

For example, the non-contact developing device shown in FIG. 1 will be explained. When the rotating sleeve 2, which is a developer layer carrier, moves in the same direction as the rotating drum type photoreceptor 1 in the development area A,
The developer P filled in the developer reservoir 6 is attached to the rotating sleeve 2 by the magnetic force of the magnet M and is conveyed. The developer P attached to the rotating sleeve 2 is formed into a developer layer by the developer amount regulating plate 4, and is conveyed to the development area A. An alternating electric field is generated in the developing area A by an alternating current bias power supply 9 connected to the rotating sleeve 2, and this alternating electric field causes the toner flying from the developer iD to adhere to the rotating drum type photoreceptor l, causing electrostatic The latent image is developed.

In this development process, toner with a small amount of charge does not return to the developer layer but floats in the air because the alternating electric field becomes weaker as it moves away from the development area. Moreover, this floating toner is scattered outside the developing area A because the movement of the photoreceptor 1 and the developer layer on the rotating drum creates an air flow F that crosses the developing area A in the same direction as these. .

As a result, a problem arises in that the floating toner contaminates the image forming apparatus.

In order to solve the above problem, the present inventor has already developed a technique that can prevent floating toner from scattering by separately forming a flow of air that flows at the same speed in the opposite direction to the flow of air that crosses the development area. (Patent application 1986-13″23)
(See No. 43). Although the above technology has made it possible to significantly reduce the amount of floating toner that scatters outside the developing device, since it requires an additional air flow in the developing area, the developing operation and the configuration of the developing device are significantly reduced. There was a problem that the process became complicated.

(Object of the Invention) In order to solve the above-mentioned conventional problems, the present invention has been made to solve the above-mentioned conventional problems by suppressing the generation of air flow across the development area, without requiring complicated operation, and by preventing floating toner from being developed. This prevents f.
It is an object of the present invention to provide a non-contact developing method and apparatus capable of preventing contamination within an image forming apparatus due to scattering of stray P toner.

(Structure of the Invention) As a result of intensive research to achieve the above object, the present inventor has discovered that
We have obtained the knowledge that the flow of air flowing across the development zone is caused by the rotation of the image carrier and the developer layer carrier, but is significantly influenced by the flow of air flowing in from upstream of the development zone. Ta.

The present invention is based on the above-mentioned knowledge, and provides a non-contact developing method and apparatus for developing an image carrier in a non-contact state with a developer layer in a developing zone, in which air is prevented from flowing in from upstream of the developing zone. A non-contact developing method characterized by suppressing the generation of air flow across the developing area and preventing floating toner from scattering to the outside from the developing device, and its non-contact developing method. It is a device.

That is, the configuration of the first aspect of the present invention is that in a non-contact developing method in which an image bearing member is developed in a non-contact state with a developer layer in a developing area, air is prevented from flowing in from upstream of the developing area. This is a unique non-contact developing method.

According to a second aspect of the present invention, in a non-contact developing device that develops an image carrier with a developer layer in a non-contact state, a gap between the image carrier and the developing device upstream of a development area is sealed. This is a non-contact developing device characterized by being provided with a sealing means.

(Example) The present invention will be explained in detail by way of examples.

2 and 3 are partial schematic sectional views for explaining a first embodiment and a second embodiment of the present invention, and the first embodiment will be explained based on FIG. 2. FIG.

In the figure, reference numeral 1 denotes a rotating drum type photoreceptor, which constitutes an image carrier. Reference numeral 2 denotes a rotating sleeve, which has a magnet body M that is fixed or rotates inside, and is disposed so as to face the outer circumferential surface of the rotating drum type photoreceptor l in the developing area A, and holds the developer Jfjm. It is the body. 3 is a developer hopper in which the toner T to be replenished is stored.
A supply row 28 is provided for supplying developer to the developer reservoir 6.

Reference numeral 4 denotes a developer amount regulating plate, which regulates the thickness of the developer layer formed on the outer periphery of the rotating sleeve 2.

5 is a cleaning blade and 7 is a stirring screw. -9 is an AC bias power supply, which is connected to the rotating sleeve 2 via a protective resistor 10;
An alternating electric field is generated between the photoreceptor 1 and the rotating drum type photoreceptor 1. Note that the rotating drum type photoreceptor 1 and the developer layer are set to move in the same direction in the development area A where they face each other. Although not shown, the movement of the rotating drum type photoreceptor 1 and the developer MiD causes an air flow across the development area A in the same direction as these. B and C
are an upper frame member and a lower frame member of the developing device, which are located above and below the developing area A, respectively. Sl is
This sealing member is made of an elastic material and is attached to the upper frame member B of the developing device.

Sl is a shielding member made of a Mylar plate, which is a non-magnetic material, attached to the lower frame member C of the developing device, and is provided to narrow the gap between the rotating drum type photoreceptor 1 and the lower part of the developing device. The sealing member S1 can prevent floating toner from scattering from the downstream side of the developing area A. The sealing member S1 seals the upper part of the rotating drum type photoreceptor 1 and the developing device by pressing the surface of the rotating drum type photoreceptor 10. It is possible to seal the gap with the frame member B and prevent air from flowing into the developing area A from the gap. Further, since the sealing member S1 is in sliding contact with the surface of the rotating drum type photoreceptor 1, it does not damage the surface of the rotating drum type photoreceptor 1 and does not disturb the electrostatic latent image. It is necessary to use a material that has elasticity and high electrical resistance, and it is also necessary that the electrostatic latent image is not disturbed by frictional charging. It is desirable that it be approximately the same as 1.

From the above, the sealing member is preferably a sponge or velvet-like flocked member.

The first embodiment is constructed as described above, and operates as follows.

Specifically, when the rotating sleeve 2 moves in the same direction as the rotating drum type photoreceptor 1 in the development area A, the developer P filled in the developer reservoir υ6 is attached to the rotating sleeve 2 by the magnetic force of the magnet M. and transported. The developer P attached to the rotating sleeve 2 is formed into a developer layer by the developer amount regulating plate 4, and is conveyed to the development area A. An alternating electric field is generated in the developing area A by an alternating current bias power source 9 connected to the rotating sleeve 2, and this alternating electric field causes toner to fly from the developer layer onto the rotating drum type photoreceptor 1.
The electrostatic latent image is developed.

In this developing process, toner with a small amount of charge floats without reaching the rotating drum type photoreceptor 1.

play. In particular, since the alternating electric field becomes weaker as the distance from the center of the development area A increases, toner with a small amount of charge floats in the air without returning to the developer layer. However, since a sealing member S1 is provided upstream of the developing area A to close the gap between the rotating drum type photoreceptor 1 and the upper frame member B of the developing device, the inflow of air is prevented.

Therefore, since the generation of air flow across the development area A is suppressed, the floating toner is suppressed from being moved out of the developing device, and is used for development together with the developer in the developing device. .

Further, in this embodiment, since the shielding member S2 is provided downstream of the developing area A to narrow the gap between the rotating drum type photoreceptor 1 and the lower frame member C of the developing device, the floating toner flows from the gap to the developing area. It can be prevented from scattering outside A.

As described above, in this embodiment, since the sealing member is provided upstream of the development area A, the inflow of air from the upstream side of the development area A is prevented, and the generation of a flow of air flowing across the development area A is prevented. It is something that can be suppressed. Therefore, the movement of floating toner out of the developing device is significantly reduced.
The toner adheres to the inside of the image forming apparatus and is less likely to cause contamination, making it possible to use the image forming apparatus for a long period of time without having to clean it. Further, since the toner remains in the developing device and is used for development together with the developer in the developing device, wasteful consumption of toner is reduced.

Note that it is of course preferable for the moving speed of the developer layer to be the same as the moving speed of the rotating drum type photoreceptor 1 from the viewpoint of the developing effect. This is also preferable in terms of preventing the occurrence of.

That is, since there is no difference in the moving speed between the developer QD and the rotating drum type photoreceptor 1, the amount of toner required for development can be appropriately supplied from the developer layer to the rotating drum type photoreceptor 1. Furthermore, since the air flow caused by the movement of the developer layer and the rotating drum type photoreceptor 1 is stable without any turbulence, it is possible to prevent floating toner from scattering and spreading outside the developing device. can.

The bias power source may be a combination of an AC power source and a DC power source, which are appropriately selected depending on the development conditions, and preferably a combination of an AC power source and a positive or negative DC power source of about 0 to 1000 V.

The developer may be either a two-component developer consisting of a carrier and toner, one or both of which are magnetic, or a one-component developer consisting only of non-magnetic or magnetic toner.

For example, the two-component developer preferably has the following conditions.

The carrier is preferably spherical magnetic particles, with an average particle diameter of 50 μm or less (preferably 5 to 30 μm) and a resistivity of 1089 cm or more (preferably 1015 Ω or more) under an electric field of 102 to 5 y/cm. It has insulation properties.

On the other hand, the toner is preferably spherical particles containing fine magnetic particles not exceeding 60% by weight (ti is preferably 30% by weight or less when using a color toner), and has an average particle diameter of 20 μm or less (preferably 10 ttm). below), resistivity is 108Ωc under an electric field of 10245v/cm
m or more (preferably 1013 Ω (m or more)). Also, the toner has an average charge amount of 1 to 1.
greater than 3 μC/l (preferably 3-300 μO/2
) is a thing.

Each of the above resistivities is determined by placing particles in a container with a cross-sectional area of o, socm2, tapping them, applying a load of l Ky/cm2 on the packed particles, and applying a load of l Ky/cm2 between the load and the bottom electrode. The voltage that produces an electric field of ~5v/cm is of the order of magnitude. Further, the average particle size was measured as a weight average particle size using Omnicon Alpha (Posh-ROM Co., Ltd. ff) and Co-Nitar Counter (Coulter Co., Ltd.).

Furthermore, in the two-component developer, a fluidizing agent for improving the fluidity and sliding of particles and a cleaning aid for cleaning the surface of the image carrier may be mixed, if necessary.

A preferable non-contact developing method using the two-component developer is as follows:
It is as follows.

That is, to explain the case where the apparatus shown in FIG. The latent image on the surface of the image carrier is developed by applying an oscillating electric field that maintains non-contact with the surface of the drum-type photoreceptor and exerts an electric force that vibrates toner particles and magnetic carrier particles with opposite polarities. This is a non-contact developing method that is characterized by the fact that even when fine particle toner is used, it does not cause fogging in non-image areas, and it is possible to obtain clear images with high reproduction fidelity without image quality deterioration. It is possible.

In the non-contact developing method, the mixing ratio of the two-component developer is preferably the same as in the conventional two-component developer, but since the non-charged toner does not fly, it is possible to increase the ratio of the toner. It is.

The developer layer carrier preferably includes a rotating sleeve and a rotating magnet having a plurality of magnetic poles within the rotating sleeve. The transport speed of the developer layer is preferably faster than the speed of the image carrier, but may be slower if a developer with a large toner content is used. The gap between the developer layer carrier and the image carrier is preferably several tens to 2000 μm. The thickness of the developer layer is determined by the following when no oscillating electric field is applied:
It is particularly preferable to set conditions such that the ears of the magnetic brush do not come into contact with the surface of the image carrier at least in the non-image area, but are close to it.

Preferably, the oscillating electric field is generated by applying an oscillating bias voltage to the rotating sleeve of the developer layer carrier. The bias voltage is a DC voltage of 50 to 600 V that is approximately equal to or higher than the potential of the non-image area, and a DC voltage of 100 V.
Hz to 10 kHz (preferably 1 to 5 kHz
) is preferable.

Furthermore, the development conditions for color development are described in Japanese Patent Application No. 58-23829.
Those described in No. 6 are preferred.

A second embodiment will be explained based on FIG.

The sealing member attached to the upper frame member B of the developing device in the first embodiment is changed to a rotating roller-shaped sealing member S. The second embodiment has the same effects as those of the first embodiment, but in addition, by making the sealing member into a rotating roller shape, it is possible to reduce the sliding resistance with the rotating drum type photoreceptor 1. , which can significantly reduce the effects of triboelectric charging.

Incidentally, the developing conditions are preferably the same as in the first embodiment.

(Experimental Example) The present invention will be explained based on a specific experimental example shown in FIG.

The device shown in FIG. 4 is a partially modified version of the device of the first embodiment shown in FIG. 2, with the following conditions added.

The rotating drum type photoreceptor 1 is an OPO with a diameter of 120φ.
(Organic photoconductor) photoreceptor, used for charging and two-image exposure, maximum potential -500 V, minimum potential -50
It has a potential contrast of (2). The rotating sleeve 2 has a diameter of 30φ and is arranged such that the main magnetic pole is located in the developing area A.
It has a fixed magnet M inside.

Hereinafter, the distance d' between the margin rotating drum type photoreceptor 1 and the rotating sleeve 2 is 0.8 haze. The bias power supply 9 is a power supply in which an AC power supply 9' with a voltage of -2 kV and a frequency of 2 kHz and a DC power supply 9' of -100 V are superimposed, and is connected to the rotating sleeve 2 via a protective resistor of IMΩ. There is.

The developer is a two-component developer made by mixing a 10 μm toner and a 20 μm magnetic carrier made by dispersing ferrite imitation powder in a resin to give a toner solubility of 20%. The developer layer is formed to a thickness of 0.5 by a developer amount regulating plate 4 made of a magnetic material. Further, the sealing member S1 attached to the upper frame member B of the developing device is made of sponge.

Under the conditions set as described above, the developing operation is performed as follows. .

Circumferential speed of rotating drum type photoreceptor 1 is 120 rye, /S
ec, when the rotating sleeve 2 is driven at the same speed as the circumferential speed of the rotating drum type photoreceptor 1, the distance d' between the rotating drum type photoreceptor 1 and the developer layer in the development area A is 0.3 gates, By applying the bias power source 9, toner was ejected from the developer layer, and the latent image on the rotating drum type photoreceptor 1 could be developed well.

Further, even if this developing step was repeated many times, the contamination caused by toner inside the image forming apparatus was slight.

On the other hand, when the sealing member was removed, the inside of the image forming apparatus was significantly contaminated with toner.

(Effects of the Invention) In the conventional non-contact developing method and device for developing an image carrier in a non-contact state with the developer layer in the developing area, in the conventional method, toner with a small amount of charge floating in the developing area is transferred to the developing area. There has been a problem in that the air that flows across the developing area is scattered outside the developing device and contaminates the inside of the image forming device.However, the present invention solves the problem by preventing air from flowing in from upstream of the developing area. , it is possible to suppress the generation of air flow flowing across the development area, and develop an electrostatic latent image as a good toner image without directionality, which is an advantage of the non-contact development method. Preventing a small amount of toner from scattering outside the developing device.1. As a result, it is possible to prevent the toner from contaminating the image forming apparatus.

Further, the apparatus of the present invention can suppress the generation of air flow across the development area only by providing a means for sealing the space between the image carrier and the development device upstream of the development area, The object of the present invention can be achieved with a simple configuration and without requiring special operations.

[Brief explanation of the drawing]

FIG. 1 is a partial schematic sectional view showing a conventional example, FIGS. 2 and 3 are partial schematic sectional views showing an example of an apparatus for carrying out the present invention, and FIG. 9 shows an experimental example. 1: Rotating drum type photoreceptor 2: Rotating sleeve 3: Developer hopper 4: Developer amount regulating plate 5: Cleaning blade 6: Developer reservoir 7: Stirring screw 8: Supply roller 9: Bias power supply 10: Protective resistor
A: Developing area B: Upper frame member of the developing device C: Upper frame member of the developing device D: Developer layer F: Air flow M: Magnet,
Sl, 31': Sealing member S2: Shielding member T:
toner. Patent Deshima person Konishiroku Photo Industry Co., Ltd. agent Patent attorney Haru Yasushi - Figure 1 Figure 2 Figure 3

Claims (5)

[Claims] (1) A non-contact developing method in which an image carrier is developed in a non-contact state with a developer layer in a developing zone, which is characterized by preventing air from flowing in from upstream of the developing zone. (2) The non-contact developing method according to claim 1, wherein the developer layer and the image carrier move in the same direction in the developing area. (3) In a non-contact developing device that develops an image carrier in a non-contact state with a developer layer in a developing zone, a sealing means is provided in the gap between the image carrier and the developing device upstream of the developing zone to seal the gap. A non-contact developing device characterized by: (4) The non-contact developing device according to claim 3, wherein the developer layer and the image carrier move in the same direction in the developing area. (5) A non-contact developing device according to claim 3 or 4, wherein the sealing means is an elastic member.