JPH0147792B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device used, for example, in an electronic copying machine, for developing an electrostatic latent image formed on the surface of a photoreceptor.

One of the developing devices for electronic copying machines currently in practical use is one that uses a magnetic brush. This uses a two-component or magnetic one-component method in which a magnetic brush is brought into sliding contact with a photoreceptor, which is an image carrier, and supplies toner or magnetic toner to an electrostatic latent image formed on the surface of the photoreceptor. .

However, the magnetic roller that forms the magnetic brush is expensive and requires a high degree of mechanical precision, and in two-component systems, the carrier itself has a limited lifespan, making it difficult to maintain a constant mixing ratio of carrier and toner. However, there are disadvantages such as the disadvantage that a lot of time and effort is required to maintain the stability of the machine.

Furthermore, recently, a fur brush development method using a fur brush roller has been proposed, but since the developer used here is a non-magnetic toner that does not use a carrier, it charges the toner uniformly and prevents fogging on the image. It is necessary to do so. To do this, conventionally, a bias voltage is applied to the fur brush roller to charge the toner, but the amount of toner charge varies, and furthermore, the amount of toner that can be captured by the fur brush roller exceeds the amount of toner that can be captured by the fur brush roller. When the toner is supplied, the toner is not sufficiently charged by the fur brush and there is a large amount of uncharged toner, and the charged toner eventually scatters, resulting in unavoidable background fog in the image.

This invention was made in view of the above-mentioned circumstances, and its purpose is to supply excess toner to a rotating body, and then rub a toner collecting means, such as a toner collecting mesh, to increase the amount of toner charge. By doing so, it is an object of the present invention to provide a developing device that can prevent background fog in images and obtain stable copied images.

Hereinafter, one embodiment of the developing device according to the present invention will be described in detail with reference to FIGS. 1 to 3 of the accompanying drawings.

FIG. 1 shows the basic configuration of an electronic copying machine, where 1 is the main body. A document mounting table 2 is provided on the upper surface of the main body 1, and is configured to reciprocate by a drive motor 3 provided within the main body 1. A photoreceptor 4 serving as an image carrier that rotates in synchronization with the movement of the mounting table 2 is pivotally supported approximately at the center of the main body 1 . This photoreceptor 4 has a cylindrical base, is provided on the outer peripheral surface of this base, and is made of zinc oxide.
It consists of a photosensitive layer formed with a resin dispersant,
Rotates counterclockwise at a circumferential speed of 80mm/sec. An exposure system 7 consisting of a lamp 5, a convergent light transmitter 6, etc. is provided between the photoreceptor 4 and the original platen 2, and it illuminates the original on the original platen 2 and directs the reflected light to the photoreceptor layer. 4 to form an image of the document. A developing device 8, a transfer device 9, a cleaning device 10, and a charging device 11, which will be described later, are arranged in this order along the clockwise rotational direction of the photoreceptor 4 from this image forming position. The developing device 8 visualizes the latent image of the document formed on the photoreceptor layer 4 by the exposure system 7. The transfer device 9 is for transferring the original toner image formed on the photoconductor 4 onto the copy paper p, and the cleaning device 10 is for removing toner remaining on the surface of the photoconductor 4. Further, at the bottom of the main body 1, there is provided a paper feeding device 14 consisting of a removable cassette 12 for storing copy paper p, and a paper feed roller 13 for feeding the copy paper p. Further, the transfer device 9 includes a transfer belt 17 having an insulating property such as Mylar (trade name), which is stretched between a transfer roller 15 and a plurality of guide rollers 16, 16. The transfer belt 17 is in contact with a part of the outer circumferential surface of the photoreceptor 4, and the transfer belt 17 is provided with a transfer charging device 1 which basically has the same structure as the charging device 11.
8 and cleaning blade 19 are in contact with each other. Further, a fixing device 20 and a delivery roller 21 are provided on the delivery end side of the transfer belt 17.
The copy paper p onto which the image has been transferred is fixed by the transfer device 9 and then transported to the tray 22. Note that 23 is a control device.

The motor 3 is a motor equipped with an exhaust fan, and is designed to exhaust heat generated in the exposure system 7 as the motor rotates to the outside of the main body 1. The photoreceptor 4 is a basic thin-walled aluminum drum with a thickness of 0.8 mm and a diameter of about 80 mm.The outer peripheral surface of the photoreceptor 4 is made of a binder type of zinc oxide-resin dispersant sensitized with a dye such as rose bengal. The body 4 is formed by coating. Further, the cleaning blade 19 described above cleans the transfer belt 17 by scraping off toner and the like adhering to the transfer belt 17.

Next, the developing device 8 will be explained based on FIG. 2. Reference numeral 24 is a developing fur brush roller which is a rotating body of 40φ, for example. It is formed by implanting bristles 28 on the outer peripheral surface of the layer 26 via a conductive adhesive layer 27,
This hair body 28 is connected to the surface of the photoreceptor 4 with a nip width of 8.
mm, and rotate clockwise at a circumferential speed of 150 mm/sec. Further, the bristles 28 are made of special rayon fibers having a length of 0.5 to 1.5 mm and a thickness of 1.5 to 7.0 deniers and treated with copper. A toner supply roller 29 is installed parallel to and in contact with the developing fur brush roller 24 with a nip width of 4 mm.

The toner supply roller 29 is made of a metal material such as aluminum and has a cylindrical body having a diameter of 25 φ and has a satin-finished surface, or a roller whose surface is further coated with Teflon. Further, a rubber blade 30 made of natural rubber is in surface contact with the toner supply roller 29 . Further, the developing fur brush roller 24 is provided with a toner collecting mesh 31 that comes into sliding contact with the bristles 28 and collects undeveloped toner. As shown in FIG. 3, this toner collecting mesh 31 is made of stainless steel wire 31a with a diameter of 0.2 mm.
By braiding, mesh 3 of approximately 1.3mm x 1.3mm is created.
1b... and attached to the holder 32. Furthermore, as the developing fur brush roller 24 rotates, each mesh 31b is formed to become gradually narrower in the direction of movement of the bristles 28 so that the bristles 28 alternately touch the meridian a and the latitude line b. has been done. Further, numeral 33 is a toner supply box containing non-magnetic toner 34, and a blade 35 for stirring the non-magnetic toner 34 is provided inside this box.

Note that the toner 34 has a particle size of 12 to 15 μm,
It had a resistance value of 10 ¹² to 10 ¹⁴ Ωcm, and was made of styrene acrylic resin mixed with carbon.

Further, 36 is the developing fur brush roller 2.
4. A bias power supply (for example, -200V) for applying a bias voltage to the toner supply roller 29 and the toner recovery mesh 31.

Next, the operation of the above embodiment will be explained.
When the electrostatic latent image formed on the surface of the photoreceptor 4 faces the developing device 8 as the photoreceptor 4 rotates, the developing fur brush roller 24 rotating in the direction of the arrow causes the electrostatic latent image to be formed on the surface of the photoreceptor 4. Magnetic toner 34 is supplied and the electrostatic latent image is developed. That is, the non-magnetic toner 34 in the toner supply box 33 is transferred to the developing fur brush roller 2 by the toner supply roller 29.
4 is supplied in excess. That is, the surface of the toner supply roller 29 has a satin finish and is rubbed against the rubber blade 30 as well as the bristles 28 of the developing fur brush roller 24, so that the non-magnetic toner 34 is triboelectrically charged. In this way, the non-magnetic toner 34 is triboelectrically charged.
is excessively supplied to the developing fur brush 24 as the toner supply roller 29 and the developing fur brush roller 24 rotate. Then, the excess undeveloped toner supplied to the developing fur brush roller 24 is scraped off by the toner collecting mesh 31, further promoting the charging of the toner. In this way, a toner layer sufficient for one time development is formed on the fur brush roller 24, and since the toner 34 is charged, the toner 34 is attached to the fur 28 due to electrostatic force. As the fur brush 24 rotates, it faces the photoreceptor 1. The toner 34 adhering to the fur brush 24 adheres to the photoreceptor 1 due to the potential (for example, -450V) of the latent image on the surface of the photoreceptor 1.

Development is performed in this manner.

In the above embodiment, the developing fur brush roller 24 is provided with the toner supply roller 29, but the present invention is not limited to the above embodiment.
As shown in the figure, the developing fur brush roller 24
A toner supply box 33 containing non-magnetic toner 34
The developing fur brush roller 24 may also serve as toner supply. In this case, by rubbing the toner collection mesh 31 on the developing fur brush roller 24, uniform toner supply and toner frictional charging effect can be achieved, and miniaturization can be achieved by eliminating the toner supply roller. It has the effect of being able to

Note that in FIG. 4, the same parts as in FIG. 2 are given the same reference numerals, and their explanation will be omitted.

In this invention, as explained above, since the toner collecting means composed of the mesh member is provided by rubbing on the rotary body, the amount of toner charge is increased, and it is possible to prevent background fogging of images due to uncharged toner. . Moreover, the structure is simple and the developing device can be made smaller.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an electronic copying machine showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional front view of a developing device, FIG. 3 is a front view of a toner collection mesh, and FIG. FIG. 2 is a longitudinal sectional front view showing an example. 4... Photoreceptor (image carrier), 24... Fur brush roller for development (rotating body), 28... Hair body, 3
1... Toner collection mesh (toner collection means).

Claims (1)

[Claims] 1. An apparatus that supplies toner to an electrostatic latent image formed on the surface of an image carrier to develop the electrostatic latent image, which has bristles that rub against the surface of the image carrier,
The toner collection device includes a rotating body that is rotatably supported and is supplied with an excessive amount of the toner, and a toner recovery means that includes a mesh member that rubs against the rotating body and scrapes off the excessively supplied toner from the bristles of the rotating body. A developing device characterized by: