JPH01197785A - Electrophotographic recorder - Google Patents

Abstract

PURPOSE:To prevent fogging and dirt caused by toner adhering onto a place except a latent image part by providing an opposite electrode which removes the toner adhering onto the non-latent image part of a photosensitive body by the action of an electric field in the way of opposing to the photosensitive body. CONSTITUTION:After being electrified in a negative potential by an electrifying means, the photosensitive body 1 is exposed to a prescribed image pattern through an exposing means; then, the exposed part becomes the latent image part 9, and the unexposed part becomes the non-latent image part 10. Thereafter, the photosensitive body 1 reaches to the part opposite to the sleeve 42 of a developing means 4. The toner 11, adhering onto the sleeve 42 on the means 4 is electrified in negative; and reaches to the part opposite to the photosensitive body 1, that is, the developing means 4. Toner 11 adheres onto the latent image part 9 and forms a toner image on the means 4. However, in the toner 11, there is the toner belongs to the non-latent image part 10 like the toner 11a. Then, the toner is carried to the part opposite to the opposite electrode 5, the toner 11a is made to adhere onto the electrode 5 by the electric field between the electrode 5 and the non-latent image part 10, and is removed from the non-latent image part 10.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrophotographic recording device used in copying machines, etc. The present invention relates to an electrophotographic recording apparatus equipped with a means for removing toner.

[Prior art and its problems] Conventionally, electrophotographic recording devices such as copying machines have used various developing methods such as the magnetic brush method, powder cloud method, and jumping developing method. Toner is attached onto the electrostatic latent image formed on the photoreceptor, and a toner image corresponding to the electrostatic latent image is formed on the surface of the photoreceptor.

However, some of the toner that adheres to the photoreceptor may adhere to areas other than the latent image area due to various reasons such as vibration of the photoreceptor or developing device, insufficient charging of the toner, and disturbance of the developing electric field. be. Therefore, the toner adhering to areas other than the latent image area is transferred to the recording medium and causes fogging and staining, which causes deterioration in the quality of the transferred image.

[Object of the Invention] Therefore, an object of the present invention is to prevent fogging and staining caused by toner adhering to areas other than the latent image area, and to improve the quality of transferred images.

[Means for Solving the Problems] The present invention is characterized by a photoconductor on which an electrostatic latent image is formed, and a photoconductor that is disposed to face the photoconductor, and that applies pre-charged toner to the latent image area of the photoconductor. a developing means to be deposited on the toner; a transfer means provided downstream of the developing means to face the photoreceptor and for transferring the toner adhered to the photoreceptor onto the recording medium; and between the developing means and the transfer means. The image forming apparatus further includes a counter electrode that is provided to face the photoreceptor and removes toner adhering to a non-latent image area of the photoreceptor by the action of an electric field.

[Example 1] As shown in FIG. 1, a photosensitive drum 1 as a photosensitive member was
It consists of a photosensitive layer 1a and a conductive layer 1b, and the conductive layer 1b
is grounded. Around the photoreceptor 1, charging means 2. Exposure means 3゜Development means 4. Counter electrode 5.
Transfer means 6. Cleaning means 7. A static eliminating means 8 is provided, and the photoreceptor 1 is moved by an arrow A by a drive mechanism (not shown).
It is designed to rotate in one direction. After the photoreceptor 1 is charged by the charging means 2, an electrostatic latent image of a predetermined pattern is formed through the exposure means 3. In this embodiment, the latent image shown in FIG. The potentials of the portion 9 and the non-latent image portion 10 are set to -100V and -700V, respectively. Note that FIG. 2 is a diagram illustrating the principle of the present invention, and parts unnecessary for explaining the principle are omitted.

The developing means 4 includes a toner container 41. The sleeve 42 is made up of a magnet roller 4-3 and a doctor blade 44, and a toner container 41 contains magnetic toner 11. The sleeve 42 is made of a conductive material such as aluminum, and a bias voltage v1 is applied thereto to form a developing electric field between the sleeve 42 and the latent image portion 9 of the photoreceptor 1. Note that the sleeve 42 is rotated in the direction of arrow A2 by a drive mechanism (not shown). This bias voltage v1 is applied to the toner 11 attached to the sleeve top 42.
It also has a function as a charging means for charging the voltage, and in this embodiment, it is set to Vl--600V. The magnet roller 43 is fixedly disposed inside the sleeve 42.

The counter electrode 5 has a sleeve shape and is made of a conductive material such as aluminum. The counter electrode 5 has
A bias voltage v2 is applied, so that a non-latent image area 10 is formed between the counter electrode 5 and the non-latent image area 10 of the photoreceptor 1.
An electric field is applied to remove the toner that has adhered to it. In this embodiment, the bias voltage v2 is set to -300V, and the counter electrode 5 is rotated in three directions indicated by arrows by a drive mechanism (not shown). A magnet roller 12 is fixedly disposed inside the counter electrode 5 . Reference numeral 13 denotes a scraping member for removing toner adhering to the counter electrode 5, the tip of which is in contact with the outer peripheral surface of the counter electrode. 14 is a collection container for collecting the toner removed by the scraping member 13, and 15 is a recording medium such as recording paper.

Next, the second operation will be explained.

In FIG. 1, the photoreceptor 1 is first charged to -700V by the charging means 2, and then rotated in the direction of arrow A1 to a position facing the exposure means 3.
through which a predetermined image pattern is exposed. As a result, as shown in FIG. 2, the exposed portion of the photoreceptor 1 exhibits conductivity, and negative charges in the exposed portion leak through the conductive layer 1b. As a result, the exposed portion of the photoreceptor 1 becomes a latent image portion 9 (second illustration), and the unexposed portion becomes a non-latent image portion 10 (second illustration). At this time, the potential of the latent image section 9 becomes 1100V, and the potential of the non-latent image section (non-exposed section) 10 (shown in the second diagram) becomes 1700V. Thereafter, the photoreceptor 1 further rotates and reaches a portion facing the sleeve 42 of the developing means 4.

In the developing means 4, the toner 1 attached to the sleeve 42
1 is the bias voltage Vl (-600
V), it is negatively charged.

This toner 11 is conveyed by rotating the sleeve 42 in the direction of arrow A2, and after being regulated to a predetermined layer thickness by a doctor blade 44 (shown in the first figure), the toner 11 is transferred to a portion facing the photoreceptor 1, that is, a developing portion. leading to.

As shown in FIG. 2, in the opposing part (developing part) between the photoreceptor 1 and the sleeve 42, the potential of the sleeve 42 is -600V due to the bias voltage v1, and the potential of the latent image part 9 is -100V, The potential of the non-latent image portion 1o is 1700V. Therefore, the negatively charged toner 11 adhering to the sleeve 42 adheres to the latent image part 9 due to the developing electric field formed between the sleeve 42 and the latent image part 9, forming a toner image. In this developing section, the toner 11 is theoretically prevented from adhering to the non-latent image section 10 due to the above-mentioned potential relationship, but there are various types of toner 11 such as toner 11a. Non-latent image area 1 depending on the cause
There are some things that stick to 0.

After that, these toners 11 (including toner 11a)
As the photoreceptor 1 further rotates, the photoreceptor 1 is transported to a portion facing the counter electrode 5 . The potential of the counter electrode 5 is -300V due to the bias voltage v2, and the potentials of the latent image area 9 and the non-latent image area 1o are each -100V, similar to the aforementioned developing area.

-700V. Therefore, the non-latent image portion 10 of the toner 11 (negatively charged) adhering to the photoreceptor 1
The toner 11a (negatively charged) attached to the counter electrode 5 is made to adhere to the counter electrode 5 by an electric field formed between the counter electrode 5 and the non-latent image section 10, and is removed from the non-latent image section 10. Thereafter, as shown in FIG. 1, the toner 11a attached to the counter electrode 5 is transported by the rotation of the counter electrode 5 in the direction of arrow A3, scraped off by the scraping member 13, and collected in the toner collection tray 14. Ru.

Note that the toner 11 adhering to the latent image portion 9 does not adhere to the counter electrode 5 and is stably held in the latent image portion 9 due to the above-described potential relationship.

As the photoreceptor 1 is further rotated, the toner 11 adhering to the latent image portion 9 reaches a portion facing the transfer means 6 and is transferred onto the recording medium 15 via the transfer means 6.

Thereafter, as the photoreceptor 1 is further rotated, the toner 11 remaining on the surface is removed by the cleaning member 7, and then the charge is removed by the charge removing means 8, and the photoreceptor 1 reaches the portion facing the charging means 2 again.

The toner 11a attached to the non-latent image area 10 is removed by the counter electrode 5 before being conveyed to the transfer means 6, and only the toner 11 attached to the latent image area 9 is left in the area facing the transfer means 6. is conveyed, so a latent image portion 9 is formed on the recording medium 15.
Only the toner 11 attached to the non-latent image area 10 is transferred, and the toner 11a attached to the non-latent image area 10 is not transferred. Therefore, a high quality transferred image is formed on the recording medium 15 without fogging or staining.

FIG. 3 shows a second embodiment, in which substantially the same members as in the first embodiment described above are given the same reference numerals. In this embodiment, the developing means 1
04, and has a configuration in which a counter electrode 105 is disposed above the electrode 04, and the configuration is rotated by 180 degrees from that of the first embodiment described above. Note that photoreceptor 1. Developing means 1
The direction of rotation of the sleeve 142 and the counter electrode 105 in No. 04 is the same as in the first embodiment.

In the developing means 104, a doctor blade 144 is disposed below the sleeve 142, and an opening 141a of the toner container 141 opens toward the counter electrode means 105.

The inner electrode 1o5 (sleeve-shaped) is located directly above this opening 141a, and the scraping member 1o5 is located directly above this opening 141a.
53 is disposed inside the opening 141a. Note that the magnet roller 113 is fixedly disposed within the counter electrode 105.

Therefore, the toner 11a that has been removed from the non-latent image area and adhered to the counter electrode 105 is scraped off by the toner scraping member 153 due to the rotation of the counter electrode 1°5 in the direction of arrow A3, and falls into the toner container 141. Then, it will be subjected to development again.

In each of the above-mentioned embodiments, the set potentials of the non-latent image area, the latent image area, and the bias voltages Vl and V2 satisfy the following condition: potential of the non-latent image area<Vl<V2<potential of the latent image area. If so, it can be changed as appropriate.

Furthermore, in each of the above-mentioned embodiments, an example was explained in which the present invention was applied to an electrophotographic recording apparatus using a negative charge reversal development method, but it can also be applied to various development methods. In this case, the set potentials of the non-latent image portion, the latent image portion, and the bias voltages Vt and V2 may be set so that the potential of the latent image portion<V2<V l <the potential of the non-latent image portion.

[Effects of the Invention] As described above in detail, according to the present invention, the toner attached to the non-latent image area of the photoreceptor is transported to the transfer unit by the opposing electrode provided between the developing means and the transfer means. This eliminates fogging and stains and improves the quality of transferred images.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the schematic configuration of the first embodiment, and FIG.
The figure is a diagram illustrating the principle, and FIG. 3 is a sectional view showing the schematic configuration of the second embodiment. 1...Photoreceptor, 4.104...Developing means, 5.105...Counter electrode, 6...Transfer means, 9...・Latent image area, 10... Non-latent image area. 11.11a... Toner. that's all

Claims (1)

[Scope of Claims] A photoreceptor on which an electrostatic latent image is formed; a developing means provided to face the photoreceptor and for attaching pre-charged toner to the latent image portion of the photoreceptor; A transfer means is provided downstream of the developing means to face the photoreceptor and transfers the toner adhering to the photoreceptor onto a recording medium, and the photoreceptor is provided between the developing means and the transfer means. An electrophotographic recording apparatus comprising: a counter electrode that is disposed to face the photoreceptor and removes toner adhering to a non-latent image area of the photoreceptor by the action of an electric field.