JPS58130365A - Developing device - Google Patents

Abstract

PURPOSE:To obtain picture images free from fogs and uneven densities and to prevent the scattering of toners by providing a toner recovering member so as to face a developing sleeve, and recovering the toners when there are no latent images on a latent image carrying body. CONSTITUTION:The toners stuck on a developing sleeve 1 are difficult to separate therefrom and generate vaious problems. A rotating body 8 as a toner recovering member is provided so as to face the sleeve 1, and a scraper 9 in one body with a blade 4 is brought into contact with said body. While there are no latent images on a latent image carrying body 6, for example, in the stage of preliminary rotation or the like, the bias of the polarity reversed from the polarity of the electric charge possessed by toners 7a is applied upon the body 8 by a DC power source 11 whereby the tonrs 7a are recovered to the body 8. When there are latent images, the body 8 is grounded. Therefore, the toners on the sleeve 1 are thoroughly exchanged, whereby the deterioration is decreased and the toner of the insufficient specific charge that can lead to fogs are removed. Thus, the picture images free from fogs and uneven densities are obtained and the scattering of the toners is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention applies a one-component magnetic developer (hereinafter referred to as toner) onto a developing device, particularly a developer supporting member having a magnetic field generating means inside, using a thickness regulating member, and The present invention relates to a developing device that visualizes a latent image by making a support member face a latent image carrier.

FIG. 1 shows a conventional example of this type of developing device, in which a developer supporting portion (hereinafter referred to as 'sleeve') 1 is inserted into a toner container 3 by a shaft 2 so that a portion thereof appears outside. It is rotatably supported.

4 is a thickness regulating member (hereinafter referred to as a blade) attached to the toner container 3 with a gap β between it and the sleeve 1; 5.
54 is a magnet arranged so as not to move within the sleeve 1, and 6 is a latent image carrier such as a photosensitive drum in electrophotography or an insulating drum in electrostatic recording, which is supported rotatably in the direction of the arrow by a shaft 6a. A latent image forming means (not shown) is arranged around it.

In the configuration described above, when the sleeve 1 rotates in the direction of the arrow, the toner 7 supplied onto the sleeve stands up along the line of magnetic force between one magnet 51 in the sleeve and the blade 4, and this spikes at the tip of the blade. A toner layer 7a having a uniform thickness is formed on the sleeve 1 by cutting at the edge portion.

When this toner 1fj7a is transferred to a position facing the latent image carrier 6, it stands up along the lines of magnetic force of the other magnet 5- in the sleeve 1, and contacts the latent image carrier 6 or the toner and latent The latent image becomes a visible image as it flies through the gap α attracted by the image charge.

However, a1#! on the latent image carrier 6! When the amount of toner on the sleeve 1 is small and the toner consumption on the sleeve 1 is low, the same toner remains attached to the sleeve 1 and moves while rotating on the sleeve, so that the charge of the toner increases due to the friction. This charge increases the mirroring force with the sleeve and prevents the toner from leaving the sleeve. 'In this case, a highly charged toner layer is formed on the sleeve, and the toner that falls on top of that toner layer becomes toner to toner friction, so that the charge of the toner becomes small. If the charge is small, the toner will not fly to the latent image carrier 6, resulting in a decrease in visible image density, uneven development, generation of ghosts, and the like. Further, a large load is applied to the stacked toner, causing deterioration of the toner.

Therefore, in the past, a toner scraping member was brought into contact with the sleeve 1, but it was not possible to sufficiently prevent uneven development and the occurrence of ghosts, and the toner adhering to the soil was forcibly scraped off with strong force. This has the disadvantage of causing toner deterioration.

SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device that can eliminate the above-mentioned drawbacks and at the same time prevent background fogging and toner scattering.

Hereinafter, two embodiments of the developing device of the present invention will be described with reference to the drawings. FIG. 2 is a schematic diagram showing the first embodiment, in which a rotating body (a conductor such as A/, 8U8, etc.) 8 as a toner collecting member is placed between the sleeve 1 and the semicircular recess 3a formed in the toner container 3. A gap r is provided, a blade 4 is disposed opposite the sleeve 1 immediately in front of the rotating body, and the tip of a scraper 9 integrated with the blade 4 is brought into contact with the rotating body 8.

Now, when a latent image is not formed on the latent image carrier 6, such as when the latent image carrier 6 is rotated forward or backward, or between paper feeds (during blur/exposure), etc., the sequence of the image forming apparatus is changed. A relay or lunoid (not shown) is actuated by a signal (a signal for forward rotation, backward rotation, plastic exposure, etc. of the latent image carrier), the switch 10 is turned on to the fixed contact 10a, and the rotating body 8 is connected to the rotating body 8 by the DC power supply 11. A bias having a polarity opposite to that of the charge possessed by the toner 7 is applied. Therefore, the toner that is regulated by the blade 4 and applied to the sleeve 1 in a uniform thin layer is attracted by the bias charge of the rotating body 8, flies through the gap rt''M, and is collected by the rotating body. # When a latent image is formed on the image carrier 6, the switch 10 is switched to the fixed contact 10b and the rotating body 8t is knee-grounded.For this reason, one revolution The body 8 is no longer able to suction and collect the toner from above the sleeve 1, and the toner Jfll coated on the sleeve 1 in a uniform thin layer is removed.
A is transferred to a position opposite to the latent image carrier 6 and subjected to development.

FIG. 3 shows a second embodiment, in which when no latent image is formed on the latent image carrier 6, the switch 12 is switched to the fixed contact 10- by the sequence signal, and the rotary body 8 is A bias having a polarity opposite to that of the charge held by the toner 7 is applied from the DC power supply 13 to collect the toner, and when a latent image is formed on the latent image carrier 6, the switch 12 is switched to the fixed contact IQb and rotated. This embodiment does not apply a bias having the same polarity as the electric charge of the toner 7 to the body 8 from the DC power supply 14 to collect the toner, and the same effect as in the first embodiment can be obtained.

FIG. 4 shows a third embodiment, in which when a latent image is not formed on the latent image carrier 6, a lever mechanism (not shown) is actuated by a sequence signal, and the rotating body 8 is moved closer to the sleeve 1. After that, I collected the toner and went back to work.

When no latent image is formed on the image carrier 6, the lever mechanism described above moves the rotating body 81 away from the sleeve 1 to collect toner.

In order to prevent the rotary body 8 in each of the above embodiments from decreasing its toner collecting ability due to adhesion of collected toner,
As shown in FIG. 2, the tip of the scraper 9 is configured to come into contact with the rotating body 8 to scrape off toner from the rotating body. In any case, the toner adheres to the rotating body 8 with a weak force, so even if it is scraped off with the scraper 9, it is unlikely to deteriorate. Alternatively, a gap of about 250 μm may be provided between the rotating body 8 and the scraper 90 so that the scraper does not come into contact with it. Furthermore, by arranging a magnet within the rotating body 8, the ability to collect toner from above the sleeve can be increased.

As described above, the present invention provides a developer recovery member opposite to the developer on the developer support member that is transferred to a position facing the latent image carrier, and when there is no # image on the latent image carrier, The developer collection member mentioned above is now 1#! Since the developer is collected from the developer support member and the developer is not collected from the developer support member when there is a latent image on the IW iron carrier, the developer in the developer support member can be replaced easily. If this is done sufficiently, the load on the developer on the developer support member is reduced, and deterioration of the developer is reduced, and the developer that has insufficient specific charge and causes fog is removed from the developer support member. As a result, it is possible to obtain a fog-free visible image with sufficient image density without causing density unevenness or ghosting. Further, since the developer that is about to fly away from the developer container is also collected by the developer collection member, effects such as being able to prevent stains due to developer scattering can be obtained.

[Brief explanation of the drawing]

@ Figure 1 is a front view showing an outline of a conventional developing device, Figure 182 is a front view showing an outline of the first embodiment of the developing device of the present invention,
FIGS. 3 and 4 are front views showing essential parts of the 2% third embodiment. 1 is a sleeve, 2 is a shaft, 3 is a toner container, 4 is a blade s, 51 to 54 are magnets, 6 is a latent image carrier, 7 is a toner percentage
8r1 rotating body, 9 is a scraper, 1°/12Fi changeover switch, 11-13/14 is a DC power supply. Figure 2 Figure 3 Figure 4 Figure 4

Claims (5)

[Claims] (1) A one-component magnetic developer is applied by a thickness regulating member onto a developer support member that has a magnetic field generating means inside, and the latent image is visualized by making the developer support member face the latent image carrier. In the developing device, a developer collecting member is provided opposite to the developer on the developer support member that is transferred to a position facing the latent image carrier, and when there is no latent image on the latent image carrier, The developer is collected from the developer support member by the developer collection member, and the developer is not collected from the developer support member when there is a latent image on the +11 image carrier. developing device. (2) When there is no latent image on the latent image carrier, a bias with the opposite polarity to the charge possessed by the developer is applied to the developer collection member, and when there is a latent image on the latent image carrier, the developer is The developing device according to claim (1), wherein the collecting member is grounded. (3) When there is no latent image on the latent image carrier, applying a bias having the opposite polarity to the charge possessed by the developer to the developer collecting member;
2. The developing device according to claim 1, wherein when a latent image is present on the latent image carrier, a bias having the same polarity as the charge possessed by the developer is applied to the developer collecting member. (4) When there is no latent image on the latent image carrier, move the developer collecting member closer to the developer supporting member, and when there is a latent image on the latent image carrier, move the developer collecting member closer to the developer supporting member. The developing device according to claim (1), which is located away from the developer supporting member. (5) The scope of claims (1) in which the developer collecting member is a rotating body, and the developer scraping member is placed close to or in contact with the rotating body.
), (2), (3) or (4).