JPH0254945B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a developing device in an image forming apparatus such as a copying machine or an electrostatic printer that uses electrophotography.

Structure of conventional example and its problems A magnetic brush type is currently in practical use as a developing device for a copying machine using dry toner. In this method, a magnetic brush using a one-component or two-component developer is brought into sliding contact with a photoreceptor, which is an image carrier, and magnetic toner or non-magnetic toner is supplied to the electrostatic latent image formed on the surface of the photoreceptor. It is something to do. However, the magnetic rollers that form the magnetic brush are expensive and require a high degree of mechanical precision, and in the case of two components, the carrier itself has a limited lifespan, making it difficult to maintain a constant mixing ratio of the carrier and toner. However, there are disadvantages such as the fact that the machine is unstable, and it requires a lot of time and effort to maintain the stability of the machine. Therefore, recently, in order to eliminate the above-mentioned drawbacks, a one-component development method that does not use a carrier has been proposed. The basic configuration of most of them uses the developing device shown in FIG. In Figure 1,
1 is a developing roller, 2 is a non-magnetic toner, 3 is a hopper, 4 is a blade, and 5 is a photoreceptor. The developing roller 1 is made of a metal material with an uneven surface, and non-magnetic toner 2 is supplied from a hopper 3, coated with the toner on the surface of the developing roller 1, and conveyed while rotating in the direction of the arrow. Next, the non-magnetic toner 1, which is charged to a predetermined polarity by a blade 4 in sliding contact with the developing roller 1, flies when it faces the electrostatic latent image on the photoreceptor 5, thereby performing development. Further, the open end portion 4a of the blade 4 is located on the downstream side with respect to the rotational direction of the developing roller 1, and furthermore, the open end portion side is provided downward. Therefore, during copying, toner particles larger than a predetermined particle size are generated due to coagulation and crosslinking of the toner particles, and remain between the blade 4 and the developing roller 1. As a result, in the toner on the developing roller 1, streak-like toner coating unevenness occurs in the circumferential direction of the developing roller 1 where the coarse toner was present. Therefore, there was a drawback that image unevenness occurred.

OBJECTS OF THE INVENTION The present invention solves the conventional problems, and aims to provide a developing device that is inexpensive, does not require highly accurate adjustment, and has high image quality.

Structure of the Invention The developing device of the present invention includes a moving body made of zinc oxide, selenium, etc. on which an electrostatic latent image is formed, a hopper having a toner supply port at one end and storing non-magnetic toner, and a toner supply port. A toner carrier provided at a position facing the moving body with a certain gap therebetween, and a toner carrier located upstream from the position facing the moving body and downstream from the toner supply port with respect to the moving direction of the toner carrier. An elastic blade made of rubber, resin, metal, etc., which is in sliding contact with the surface of the toner carrier at a position and whose open end faces downward on the upstream side with respect to the moving direction of the toner carrier, and between the blade and the toner hopper. The structure consists of a blade protection plate located at the top of the blade and having a length that covers the open end of the blade.

DESCRIPTION OF EMBODIMENTS FIG. 2 shows a developing device according to a first embodiment of the present invention, and is an example in which the developing process of a copying machine is used.

In FIG. 2, reference numeral 6 denotes a photosensitive drum which is a moving body, and is provided by coating a photosensitive material 8 such as zinc oxide, selenium, OPC, etc. on the surface of a base 7 made of, for example, Al. 9 is a charger, and photosensitive drum 6
The photosensitive material 8 on the photosensitive drum 6 is charged by applying a negative corona in the case of zinc oxide and a positive corona in the case of selenium from the high-voltage DC power supply 10 depending on the photosensitive material 8 . 11 is an optical section that projects a pattern light image onto the photosensitive drum 6;
It forms a latent image. 12 is a non-magnetic insulating toner, and 13 is a hopper containing the toner 12, which has a toner supply port 14 at one end. 15
is a developing roller which is a toner carrier, for example
The surface 15a of a metal roller made of SUS, Al, etc. is formed into an uneven shape. Further, the developing roller 15 is provided at the supply port 14 of the hopper 13 and at a position facing the photosensitive drum 6 with a certain gap therebetween. A blade 16 is made of an elastic member such as rubber, resin, or metal. Further, the blade 16 is provided in sliding contact with the surface 15a of the developing roller upstream from the opposing position of the photosensitive drum 6 and the developing roller 15 and downstream from the supply port 14 with respect to the moving direction of the developing roller. . Furthermore, the open end 16a of the blade 16 is located upstream with respect to the moving direction of the developing roller 15, and the open end 16a side is provided facing downward. A blade protection plate 17 is provided between the blade 16 and the hopper 13 and has a length that covers the open end 16a of the blade 16.
This is to prevent the blade 16 from being applied to the developing roller 15, thereby making the pressing force of the blade 16 constant.

The operation of the developing device of the first embodiment configured as described above will be explained below.

In FIG. 2, zinc oxide is used as the photosensitive material 8 of the photosensitive drum 6 to make the operation easier to understand. A high negative voltage is applied to the charger 9 by a high voltage DC power supply 10, and the entire surface of the photosensitive drum 6 is negatively charged by corona discharge. Next, a pattern light image is projected onto the negatively charged photosensitive drum 6 by the optical section 11 to form a latent image. During this time, the toner 12 in the hopper 13 acquires a positive triboelectric charge due to friction between gravity and the developing roller 15 and pressure between the blade 16 and the developing roller 15, and forms a toner coating on the developing roller surface 15a. be done. At this time, the toner 12 is restrained on the developing roller surface 15a by physical adhesion and electrostatic attraction of the charges on the toner 12. Next, the negatively charged latent image on the photosensitive drum 6 is transferred to the developing roller 1.
When facing the positively charged toner 12 on the photosensitive drum 5, the toner 12 flies onto the photosensitive drum 6 and can perform development. Further, in this embodiment, the open end 16a of the blade 16 is located upstream with respect to the rotational direction of the developing roller 15, and the open end 16a side is provided downward. Therefore, during copying, the toner 12 coagulates,
Even if coarse toner exists due to the crosslinking phenomenon,
The toner falls toward the supply port 14 due to gravity and the return force of the blade 16 in the direction of the arrow. As a result, coarse toner does not remain between the blade 16 and the developing roller. Therefore, since streak-like toner coating does not occur in the circumferential direction of the developing roller 15, high-quality image development can be performed. In addition, this embodiment has the advantage that non-contact development can be performed using non-magnetic insulating toner, so that colorization is possible. In this embodiment, a developing roller is used as the toner carrier, but a belt may also be used.

Effects of the Invention The developing device of the present invention is capable of triboelectrically charging the toner and uniformly coating the toner on the toner carrier by sliding the blade into contact with the toner carrier, so it is inexpensive and eliminates the problem of high-precision adjustment. It's gone. Further, by locating the open end of the blade on the upstream side with respect to the moving direction of the toner carrier and by providing the open end side facing downward, it is possible to uniformly coat the toner on the toner carrier. Furthermore, since a blade protection plate whose tip has a length that covers the open end of the blade is provided between the blade and the toner hopper, the gravity of the toner is not applied excessively to the blade, and therefore the toner carrier of the blade The pressing force against the roller remains constant, making it possible to develop high-quality images without image unevenness.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a conventional dry-type developing device using one-component toner, and FIG. 2 is a partial cross-sectional view of a developing device according to an embodiment of the present invention. 6... Moving body, 12... Toner, 13... Hopper, 14... Toner supply port, 15... Toner carrier, 16... Blade, 16a... Open end, 1
7...Blade protection plate.

Claims (1)

[Claims] 1. A movable body on which an electrostatic latent image has been formed, a hopper having a toner supply port at one end and containing non-magnetic toner, and a hopper located at the toner supply port portion and facing the movable body with a certain gap therebetween. a toner carrier disposed at a position in which the toner carrier slides in sliding contact with the surface of the toner carrier at a position upstream from a position facing the moving body and downstream from the toner supply port with respect to the moving direction of the toner carrier; an elastic blade having an open end facing downward on the upstream side with respect to the moving direction of the toner carrier; and a blade having a length that is located between the blade and the toner hopper and has a tip that covers the open end of the blade. A developing device having a protection plate.