JPH03231777A - developing device - Google Patents

Abstract

PURPOSE:To maintain good printing quality without requiring a toner concn. control means by providing a means for supplying a developer to the inside of a developing tank at each specified quantity according to the number of photographs to be developed. CONSTITUTION:A toner 21 is agitated with a carrier 22 in a developer box 5 and the toner 21 is electrified negative and the carrier 22 positive. The developer is transported to a part facing a toner recovering roller 16 after the visualization of electrostatic latent images and only the toner 21 is recovered by the voltage impressed on this roller 16. The developer contg. only the carrier 22 is recovered into a developer box 5. The specified toner supply is executed with nearly the specified toner consumption if the toner supplying roller 19 is rotated after the printing by as much as the determined number of sheets is finished; therefore, the toner concn. is kept nearly constant and the toner concn. control means is eliminated. The toner concn. is kept stable and constant in such a manner without requiring the toner concn. control means.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device for developing a latent image formed on a photoreceptor based on image information in an electrophotographic apparatus or the like.

[Prior Art] Conventionally, in this type of developing device that uses a two-component developing method, it is necessary to maintain a constant mixing ratio (toner concentration) of toner, which is a developer, and carrier in order to perform good printing. Therefore, various toner density control means have been devised and utilized.

[Problems to be Solved by the Invention] However, it is difficult to keep the toner concentration stable and constant even if a toner concentration control means is used, and the toner concentration control means is expensive, resulting in an increase in the cost of the developing device. This was a contributing factor.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a developing device that does not require a toner concentration control means while maintaining good print quality.

[Means for Solving the Problems] In order to achieve this object, the developing device of the present invention includes a stirring means for stirring magnetic particles and a developer in a developing tank and charging each other to different polarities, and a magnetic means, a non-magnetic carrier that supports the magnetic particles and the developer and transports them to a latent image forming surface on the photoreceptor; and a developer recovery means that collects only the developer on the carrier after the latent image is developed. a magnetic particle collecting means for collecting the magnetic particles on the non-magnetic carrier into the developing tank; and a means for collecting the collected developer or a new developer according to the number of photographs to be developed. and a developer supply means for supplying a fixed amount of developer into the developer tank.

[Function] In the developing device of the present invention having the above configuration, the magnetic particles and the developer are stirred by the stirring means in the developing tank,
The magnetic particles and the developer are charged with different polarities, and are carried and conveyed by a non-magnetic carrier to a latent image forming surface on the photoreceptor, and the latent image is developed.

After the latent image is developed, only the developer on the carrier is recovered by the developer recovery means, the magnetic particles on the magnetic carrier are recovered into the developer tank by the magnetic particle recovery means, and the The recovered developer or new developer is supplied by a developer supply means into the developer tank in a fixed amount depending on the number of images to be developed.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory diagram showing the configuration of a developing device embodying the present invention.

In the developing box 5 of the developing device 1, a non-magnetic sleeve 13 containing a fixed magnet roll 12 is provided facing the photosensitive tram 11, and a carrier recovery blade] 4 is in contact with the sleeve 13. A developer transport roller 15 having a rotation axis parallel to the rotation axis of the sleeve 13 is provided below the carrier collection blade 14 . A toner collection roller 16 is provided at the top of the sleeve 13 with a slight gap, and this toner collection roller 1
6 is in contact with a toner collection blade 17. Toner 2
A toner supply roller 19, which will be described in detail later, is provided at the lower open end of the toner supply box 18 containing the toner supply roller 1.
Below the toner supply roller 19 is a developer stirring roller 20.
is provided.

FIG. 2 is a schematic diagram showing voltages applied to the photoreceptor drum 11, sleeve 13, and toner collection roller 16. A higher voltage is applied to the toner collection roller 16 than to the photoreceptor drum 11.

Next, the toner supply roller 19 will be described in detail with reference to FIG.

The toner supply roller 19 is cut with a groove 198 extending in the longitudinal direction.

The groove 19a is configured so that the toner from the toner collection box 26 falls, and as the roller 19 rotates in the direction of the arrow, the toner falls into the developer box 5.

If there is not enough toner in the collected toner box 26 to fill the groove 149a, the toner in the toner supply box 18 is configured to make up for the shortage.

Next, the action will be explained.

The toner 21 in the toner supply box 18 is fed into the developer box 5 in fixed amounts by the rotation of the toner supply roller 19. This toner 21 is transferred to the developer stirring roller 20.
The toner is agitated with the carrier 22 in the developer box 5 by the rotation of the developer transport roller 15, and the toner 21 is negatively charged and the carrier 22 is positively charged. This developer (carrier 22+
The toner 21) is transferred to the magnetic roll 1 in the sleeve 13.
The developer is attracted to the surface of the sleeve 13 by the magnetic force of 2, forming a magnetic brush, and as the sleeve 13 rotates in the direction of arrow a, the developer is also transported in the direction of arrow a. in the middle,
After the layer thickness is made constant by the height regulating plate 24, the photosensitive drum 11 rotating in the direction of the arrow is rubbed, and the electrostatic latent image on the photosensitive drum 11 is visualized. Thereafter, the developer conveyed to the opposite portion of the toner collection roller 16 is collected by the toner collection roller 16 due to the voltage applied to the same roller 16 . This toner 21 is peeled off from the toner collection roller 16 by a toner collection blade 17 and collected into a collection toner box 26 .

Further, the developer that has been collected from the toner 21 and spread across the carrier 2 is collected into the developer box 5 by the carrier collection blade 14. Here, if the toner supply roller 19 is rotated after printing a predetermined number of sheets, a constant supply of toner can be performed for approximately constant toner consumption, so the toner concentration can be kept approximately constant. This eliminates the need for toner density control means.

As is clear from the above detailed description, according to this embodiment, an inexpensive developing device 1 can be provided without requiring a toner density control means.

Furthermore, since the toner 21 and the carrier 22 are once completely separated, it is possible to eliminate sleeve ghosts where the previous development pattern appears in the next printing.

Note that the toner collection method may be other than that disclosed in this embodiment, and the collected toner may be directly collected into the toner supply box.

Other changes may be made without departing from the spirit of the invention.

[Effects of the Invention] As is clear from the above detailed description, according to the present invention, an inexpensive developing device can be provided without requiring a toner density control means.

In addition, since the developer and magnetic particles are completely separated,
Sleeve ghost, where the previous development pattern appears in the next print, can also be eliminated.

[Brief explanation of drawings]

1 to 3 show an embodiment embodying the present invention. FIG. 1 is an explanatory diagram showing the configuration of the developing device of this embodiment, and FIG. 2 shows voltage application to each unit. FIG. 3 is an enlarged view of the vicinity of the toner supply roller. In the figure, 1 is a developing device, 5 is a developer box, 11 is a photosensitive drum, 13 is a sleeve, 14 is a carrier collection blade, 16 is a toner collection roller, 1 is a toner supply roller, 20 is a developer stirring roller, 21 is a toner, and 22 is a carrier.

Claims (1)

[Claims] 1. A developing device for developing a latent image formed on a photoreceptor based on image information in an electrophotographic device, etc., which stirs magnetic particles and a developer in a developing tank, a stirring means for charging each other with different polarities; a non-magnetic carrier that includes a magnetic means, carries the magnetic particles and the developer, and transports the magnetic particles and the developer to a latent image forming surface on the photoreceptor; After that, a developer collecting means for collecting only the developer on the carrier, a magnetic particle collecting means for collecting the magnetic particles on the non-magnetic carrier into the developer tank, and a developer collecting means for collecting only the developer on the carrier, a magnetic particle collecting means for collecting the magnetic particles on the non-magnetic carrier into the developer tank, and 1. A developing device comprising: a developer supply means for supplying a fixed amount of developer or new developer into the developer tank in accordance with the number of photographs to be developed.