JPS5870256A - Developing device - Google Patents

Abstract

PURPOSE:To suppress the developing of non-picture parts effectively by interrupting the supplying of a developer from a supplying roll to a developing roll in conformity with the timing of the non-picture parts in order to prevent developing of the non-picture parts on an image holding body. CONSTITUTION:A sleeve roll 1 for developing, a supplying roll 2 for supplying a developer to the roll 1, stationary magnets 3 disposed in the roll 2, a regulating member 4 for the thickness of the developer, a one-component developer 5 having insulating and magnetic characteristics, a developer 6 coated thinly on the surface of the roll 1, a stationary magnet 7 disposed in the roll 1, a developer hopper 8, and a photosensitive drum 9 are provided. In a developing gap (a), the toner layer 6 is not in contact with a photosensitive drum 9, and the toner is moved back and forth in the void in the developing position by the bias from an AC biasing power source 10, whereby developing is accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device in a IIb7 image forming apparatus such as an electrophotographic copying machine.

In conventional electrophotographic copying machines, the shadow of the leading edge of the document, etc.
I117gI appears at the leading edge of the copy paper, and not only does it spoil the aesthetic appearance of the background of the copy paper, but also a black band appears at the leading edge of the copy paper, contaminating the conveyance path after development, causing stains, and dirt. When entering the device P, the fixing row 2 may be contaminated, causing an offset phenomenon. Another drawback is that non-image areas between images are developed, resulting in excessive toner consumption.

As a method for preventing this, a method is conventionally known in which an electrostatic a image forming a black band on a photoreceptor is erased using IIjt. However, this method F1jt has drawbacks such as requiring improvements in the science and reflected light, and in that the rise of the light and sound from the light source is insufficient, resulting in fogging.

Furthermore, conventionally, there are five methods for intentionally stopping development and performing black erasure. One method is to move a regulating member that regulates the layer thickness of the developer closer to the environmental roller @ to reduce the toner thickness and prevent development, but this movement of the regulating member is undesirable in terms of machine stacking. Also, it is difficult to remove a single layer of toner from the roller surface.Also, there is a method of stopping the rotation of the IJ4 intermittent roller and not performing the #4 image, but the current method is
The load fluctuation of aI itself is undesirable because it leads to failure of the optical system. Furthermore, there is a method in which development is prevented by shifting the #i development polarity to restrict blistering in the 3J image area, but this method also provides only an insufficient effect of stopping development. Further, none of the above-mentioned conventional techniques can pass ON-OFF operation with a sharp visual image.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional drawbacks, an object of the present invention is to provide a developing device that performs so-called black erasure, which effectively suppresses the development of the non-ij image portion on the holder.

The present invention uses the method of erasing the latent image as described above as the black erasing method described above, and uses a developing roller having a developing roller and a supply roller that supplies the developing roller to the developing roller. With the device configuration, by stopping the supply of developer to the filter row 2 at the point corresponding to the black belt (non-image S), the latent image corresponding to the black belt is not visualized (visualized), thereby producing a black image. This is for erasing. 2 of the present invention
This roller configuration has the advantage that the developing roller can continue to rotate because the developer does not adhere to the Fi image filling roller. In addition, sharp ON-OFF of the soul J in the boundary area between the &1iii4J1 capital and the non-image area is also possible.

Embodiments of the present invention will be described in detail below based on the present invention.

FIG. 1 shows an outline of the lump m device of the present invention. 1 is a supply roller that supplies developer to Genhaku Sleeve 0-2-12 developing roller 1, and 3 is a supply roller? A solid magnet placed in the 1 circle, developer applied to the voice wood thin layer of the image forming sleeve roller #i and a solid magnet placed in the iA image sleeve roller 1), 8tlJ's own hopper, 9Fi photosensitive drum as an image carrier. It should be noted that in the main output of 1 ott, the toner layer 6 is not in contact with the photosensitive drum 9, and the toner layer 6 is moved back and forth at the position h3Am by the above-mentioned alternating bias, and the toner layer 6 is tonerized.

As shown in FIG.
By applying a bias, a thin layer of developer is coated on the developing roller 1 to form a developer layer 6, which is developed at a distance of about 551 m on the photosensitive drum 9. When the developer has an IIL charge of negative polarity, it is applied from the supply roller 2 to the filler roller 1 in the direction of the electric field due to the connection to the bias power supply 11 in the figure. As shown, the switch of the supply bias power supply 11 shown in Figure 1 is connected to B in accordance with the tiling of the non-l1i part, and the switch of the supply bias power supply 11 in Figure 2 is connected to B.
(Turn on B to stop the coating from the supply roller to the IJfJIQ-ler, and virtually apply jAw onto the photosensitive drum.
The non-g1 part is erased by creating a part that is not marked. Note that the horizontal axis in FIG. 2 indicates the position on the drum.

Also, as shown in Part 2-Middle ■, non-l! The rotation of the supply row 2- is stopped in accordance with the timing of 1I4as and the rotation of the supply row 2- is substantially i.
Try not to make it look like A. In carrying out the above, the time sequence shown in Fig. 3 is carried out, taking into account the rotation time of 7t from the coating section to the developing section of the developer. σ−2
-2 or developing roller 1F! 5 methods are shown in which blackening is performed on the non-iiiIw portions by stopping the application of toner to the developing roller using a structure in which the magnet does not have three prongs.

Figure 5 (II) I (b) is another embodiment of the present invention. As shown in FIG. 5(a), a magnetic material is used for the thickness regulating member 4 on the supply roller 2, and the magnetic 'fM (
When the above-mentioned member 1111J member 4 is located at the point N-8), the developer becomes brush-like and can be applied to the developing roller 1. As shown in FIG. When the magnet is rotated to set the magnetic pole N (also #is) directly under the above-mentioned regulating member, the thickness of the coating is significantly reduced and becomes a thin layer, so the developing roller! This means that the developer will not be supplied to Ito, and it will essentially be non-I.
IT's part is not developed.

As described in detail above, in the present invention, the dust Q from the supply roller is
Since the supply of developer to the j1a-lar is stopped depending on the non-self-extracting area, it is possible to achieve effective black erasure.

[Brief explanation of the drawing]

FIG. 1 is a sectional view and a clear view of a developing device to which the present invention is applied. In tuna, 11-00 machine roller round 2...supply low? -13,7... solid magnet, 4@-
Fist...'g4 Imager thickness regulating member, 5...Yu...Insulating magnetic component developer, 9 bites...Meeting, photosensitive doshi^, 10...
...Represents an alternating bias power supply, 11... Represents an alternating bias power supply. Exit jllA Nakayanon Co., Ltd. Figure 5 (0) Line 5 Figure Cb)

Claims (1)

[Claims] (1) - A developing roller carrying a thin layer of component developer;
In a developing device using a supply roller that supplies a lump 9 agent to the roller, in order to prevent the non-wIJ image area on the suspended holding member from becoming a dust mound, the developer is not supplied from the supply roller to the development roller. An on-site device characterized in that the supply is continuously cut off in accordance with the timing of the non-iIk1g1 portion. (2) A developing device according to claim 1, characterized in that the bias polarity of the upper two mechanical rollers and the supply roller is switched in accordance with the timing of the non-9 part. (6) A claim in which the TRF image is stopping the rotation of the supply loan in accordance with the timing of non-*S! ! The developing device according to item 1. (4) The above supply low 2 is adjusted according to the timing of the non-image area.
The developing device according to claim 1, characterized in that the magnetic position of the magnetic field generating means within - is changed. (5) The developing gI device according to claim 1, wherein the a-pole position of the magnetic field generating means in the developing roller is changed in accordance with the timing of the non-image area.