JPS6289077A - Developing device - Google Patents

Abstract

PURPOSE:To make it possible to keep the thickness of a toner layer on a perforated electrode member and the density of picture images uniformly over a long period by providing a blade to the perforated electrode member without contacting it. CONSTITUTION:Developer sent into a sleeve 16 is carried from an end to another end in axial direction by the rotation of a screw 12, and after arriving at another end of a developing device 1, returned to a carrying screw 11 by gravity. Thus, developer is circulated between the lower part of a container 10 and the inside of a perforated electrode sleeve 16. In this movement, developer in the lower part of the container 10 is carried to the inside of the electrode sleeve 16, and electrostatically charged sufficiently by the action of a magnet, etc., and deposited on the outer face of the perforated electrode sleeve 16 and receives the action of a non-contact blade 14. Consequently, the toner layer having uniform thickness is formed and faces a photosensitive body 2. At this point of time, the developer sticks to an electrostatic latent image formed on the photosensitive body 2 and changes the latent image to a visible image.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device for developing a latent image such as an electrostatic latent image formed on an image carrier, and particularly relates to a two-component non-contact developing device.

11. Conventionally, in the so-called mesh development method using a metal mesh, etc., when the metal mesh is fixed, it is not possible to recover the developer (hereinafter also referred to as toner) that is not consumed during development, and the toner is There is a disadvantage that the image is contaminated by splashing and spilling, and on the other hand, there is a disadvantage that the size of the apparatus increases even if the device is moved. In any case,
Since the toner and carrier are stirred and conveyed by separate means, the apparatus becomes complicated and large, which is a problem. In order to solve this problem, a developing device is constructed in which a perforated electrode plate is configured as a rotatable endless carrier, a developer is deposited through this, and a latent image on the latent image carrier is developed with the deposited developer. Although this method has been proposed, there is a problem in that the amount of precipitation of the developer is not constant and tends to be non-uniform, resulting in unevenness in the developed image.

The present invention solves the above-mentioned drawbacks in a developer device using an endlessly movable perforated electrode plate, and makes the thickness of the developer formed on the perforated electrode plate uniform.

It is an object of the present invention to provide a developing device that does not cause density unevenness in images.

According to the present invention, a developer holding member holds a developer containing a nonmagnetic toner capable of retaining a charge and magnetic carrier particles having a particle size larger than that of the toner.

The outside of the developer holding member is provided so as to be able to move endlessly while sliding against the developer, and has a large number of openings that are larger in diameter than the toner particles and smaller than the carrier particles. a perforated electrode member for depositing only toner particles to the outside, and a means for depositing the precipitated toner particles onto a latent image while maintaining non-contact between the perforated electrode plate and an original image carrier to be developed at a development position; , there is provided a developing device characterized by having a blade member provided upstream of the developing position in the moving direction of the perforated electrode plate and spaced apart from the outside of the perforated electrode plate. , the thickness of the toner particles becomes uniform due to the action of the blade.

Actual JL Example FIG. 1 shows a photographic image forming apparatus equipped with a developing device 1 according to the present invention. FIG. 1 shows a cross-sectional view of the developing device of this embodiment, and FIG. A diagram is shown.

The image forming apparatus has a photosensitive drum 2 which is an image bearing member, a latent image is formed on the surface of the drum by means provided around the drum, and the PpJ image is developed by the developing bag 21t according to the present invention. be. A corona charger 3, a developing device 1, a transfer separation charger 4, a pre-clean static eliminator 5, and a cleaning means 6 are provided around the photosensitive drum 2 for image formation. Position δ of the arrow indicated by reference numeral 7
The photosensitive drum 2, which has uniformly received the pre-exposure light, is uniformly charged by the corona charger 3, and then subjected to image exposure at the position indicated by the arrow 8, whereby the charges on the photosensitive drum 2 are reduced. It disappears as it is exposed to light, forming an electrostatic latent image. This latent image is developed by a developing device 1 according to the present invention, and the developed image is transferred by a transfer charger 4 onto a transfer paper conveyed by a roller 9. The transferred toner image is fixed onto the transfer paper by a fixing device (not shown).

After the transfer, the photosensitive drum 2 is subjected to the action of the pre-clean static eliminator 5, and then residual toner is removed by the cleaning means 6, in preparation for the next image formation.

Next, the developing bag M1 of the present invention will be explained in detail. The developer bag ml has a container 10 in which developer is stored in the lower part. The developer is a two-component developer containing toner particles and magnetic carrier particles.

A perforated electrode member 16 is provided inside the container 10 . In this embodiment, the perforated electrode member 16 is a perforated electrode sleeve made of conductive metal and endlessly movable in the direction of the arrow (rotatable by the drive gear 23). The perforated electrode sleeve 16 has a large number of minute openings, which may be in the same or opposite direction to the moving direction of 2, and the opening diameter is larger than the particle size of the toner particles and smaller than the particle size of the carrier particles. For example, in order to satisfy this, an SU with an outer diameter of 20 mm and a thickness of 0°4 mm is used.
Using S, holes with a diameter of 100 μm or less were formed in a lattice shape with an interval of 300 μm using a Co2 laser. This processing is not limited to the use of a laser, but may also be performed by etching or electric field etching. The toner used has an average particle size of about 10 JLm, while the carrier particles have a particle size of about 200 Bm.

The container 10 has an opening 15 through which the outer surface of the perforated sleeve 16 faces the photosensitive drum 2 .

A conveyance screw 11 is provided at the lower inside of the container 10 . The conveying screw has a spiral member on a shaft that rotates in the direction of the arrow, and also functions to convey the developer in the axial direction. On the other hand, a developing screw 12 is provided inside the perforated electrode sleeve 16 .

As understood from FIG. 2, the spiral conveying screw 1
1 and the developing screw 12 are formed as an integral screw, and the conveying screw and the screw 12 are rotated in the direction of the arrow in FIG. 1 by the drive gear 22. As a result, the developer is conveyed to the right in FIG. 2, and is sent upward, ie, into the interior of the sleeve 16, by the screw 24 at the right end.

The developer sent into the sleeve is conveyed from one axial end to the other end in the direction of the arrow in FIG. After reaching the other end, it returns to the conveying screw 11 due to the masticating force. In this manner, developer circulates between the lower portion of container 10 and the interior of perforated electrode sleeve 16.

A magnet 13 is provided outside the perforated electrode sleeve 16 on the upstream side of the portion facing the photoconductor 2 (with respect to the rotational direction of the sleeve 16), and this magnet 13 forms a magnetic brush extending from the developing screw 12. The magnetic brush reaches the perforated electrode sleeve 16, contacts it, and rubs it. That is, the rotation of the developing screw 12 and the perforated electrode sleeve 16 forcibly rubs the perforated electrode sleeve 16, the carrier particles, and the toner particles. This rubbing gives sufficient charge to the toner,
Moreover, the carrier moves toward the perforated electrode due to the magnetic attraction of the magnet 13, and the toner particles are accordingly transferred to the perforated electrode sleeve 1.
The toner is deposited on the outer surface of the perforated electrode sleeve 16 through the minute openings 6, and a layer of toner is formed there.

A blade 14 is provided on the downstream side of the magnet 13 to face the outer surface of the perforated electrode sleeve 16, and the tip of the blade 14 is applied with a predetermined pressure ftdtl from the outer surface of the perforated electrode sleeve 16.
It's been a while. This distance flfid is 204m or more, 2
00pm or less is preferable, and below 20ILm,
The toner layer pressure is too thin and sufficient image density cannot be obtained.
If the length exceeds 4 m, the uniformizing effect of the blade cannot be obtained, and density unevenness will occur in the image. The material of the blade 14 may be any material as long as it has good surface properties and precision, and its thickness is appropriately selected by those skilled in the art so as not to excessively press the toner against the perforated electrode sleeve 16. In this way, the blade 14 serves to regulate the thickness of the toner layer formed by deposition and uniformly coat the perforated electrode tube with the deposited toner.

The perforated electrode sleeve 16 and the photosensitive drum 2 have a diameter of 100 to 50
By alternating voltage applied between them at a distance of 0 gm, the toner, once formed as a thin toner layer by the precipitation, flies back and forth between the photosensitive drum 2 and the outer surface of the perforated electrode sleeve 16, and Develop the upper electrostatic latent image with very little fog. Since this developing process is basically the same as that described in Japanese Patent Publication No. 58-32375, detailed explanation will be omitted.

In operation, the perforated electrode sleeve 16. The conveyance screw 11 and the screw 12 rotate in the directions of the arrows, and the developer in the lower part of the container 10 is transferred to the perforated electrode sleeve 16.
The toner is transported into the interior of the photoreceptor, is sufficiently charged by the action of the magnet 13, and deposits on the outer surface of the perforated electrode sleeve 16, and is formed into a single layer of uniform thickness by the action of the non-contact blade 14. Opposed to 2. Here, the developer adheres to the electrostatic latent image formed on the photoreceptor 2 and visualizes the latent image.

When the developing device N1 according to the present invention was actually configured and operated, it was confirmed that no density unevenness appeared during image formation on up to 10,000 sheets, and that initial image density uniformity was maintained.

As explained above, according to the present invention, since the blade is provided in a non-contact manner with respect to the perforated electrode member (sleeve), the uniformity of the thickness of the toner layer on the perforated electrode member can be maintained. Can be done 1
Image intensity can be made uniform over a long period of time.

[Brief explanation of drawings]

FIG. 1 shows a cross-sectional view of a developing device and an image device using the developing device according to an embodiment of the present invention. FIG. 2 shows a longitudinal sectional view of the developing device shown in FIG. Brief explanation of symbols 2...Image carrier 12...Developing screw 13...Magnet 14...Blade 16--Perforated electrode member Fig. 1

Claims (1)

[Scope of Claims] A developer holding member that holds a developer containing non-magnetic toner capable of retaining a charge and magnetic carrier particles having a particle size larger than that of the toner, and an external surface of the developer holding member that is rubbed against the developer. a perforated electrode member that is provided so as to be endlessly movable, has a large number of openings larger than the particle size of the toner particles and smaller than the carrier particles, and allows only the toner particles to be deposited to the outside by rubbing against the developer; and a means for adhering the deposited toner particles to the latent image while keeping the perforated electrode plate and the image bearing member to be developed in non-contact at the development position; A developing device comprising a blade member provided upstream and spaced apart from the outside of the perforated electrode plate.