JPH05100529A - Image forming device - Google Patents

Abstract

PURPOSE:To provide the image forming device where a thin layer of toner can be formed with an even thickness of the layer and without variation in quantity of electrification in image formation utilizing photosensitive toner. CONSTITUTION:A roller 20 is provided in a pressurized contact with a conductive substrate 13 between a toner thin layer forming part (vicinity of sleeve 11) and an exposure part (vicinity of an exposure device 14). Voltage of the same polarity as the electrifying polarity of the toner is impressed to the roller 20, and the surface of the roller is coated by fluororesin, etc., to reduce mechanical sticking force with the toner. Because the thickness and the quantity of the electrification is not even in the toner thin layer formed by the sleeve 11, it is smoothed out by pressure force of the roller 20, and furthermore, while the electrification quantity is made even by impressing the voltage to the roller 20, the toner with high dark conductivity is stuck to the roller 20 and eliminated by the blade 21. Thus, unevenness and fogging of an image can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus,
In particular, it relates to an image forming apparatus using a photosensitive toner.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic method, there is a method in which a photoconductive photoconductor is used to form an electrostatic latent image on the photoconductor and the electrostatic latent image is developed with toner. Aside from this,
There is a method in which charging and exposure are performed using a photoconductive toner to form a charged toner group and a non-charged toner group, and then the toner of either group is transferred to form an image. In the latter method using a photosensitive toner, a thin layer of charged toner is usually formed on a conductive substrate, and the thin layer of the photosensitive toner is imagewise exposed to form a charged image on the toner thin layer. After that, the non-charged toner group is electrostatically transferred to a transfer medium such as copy paper.

FIG. 3 is a schematic view of a conventional apparatus used for forming an image using a photosensitive toner. In the apparatus shown in the figure, the photosensitive toner is contained in the toner container 10 together with a magnetic carrier such as ferrite. The photosensitive toner is charged by being agitated with the carrier in the toner container 10. The charged toner forms a magnetic brush with the magnet 12 on the sleeve 11 on which the magnet 12 is fixedly arranged. The sleeve 11 is applied with a voltage of the same negative polarity as the polarity of the charging of the toner (negative polarity in this case), and is installed in a state of facing the grounded drum-shaped conductive substrate 13. Then, the sleeve 11 moves in the A direction,
The conductive substrate 13 is adapted to rotate in the B direction. The magnetic brush is brought into sliding contact with the conductive substrate 13 so that the negatively charged toner forms a thin layer on the conductive substrate 13. The thin layer of toner thus formed rotates as the conductive substrate 13 rotates, and is exposed by the exposure device 14 at a predetermined position, whereby an electrostatic latent image is formed on the thin layer of toner. It is formed. In the figure, the toner irradiated with light is L,
The unirradiated toner is indicated by D. Here, the light-irradiated-polarity toner becomes conductive with reduced electric resistance, and a part of its charge disappears through the grounded conductive substrate 13. The thin toner layer on which the electrostatic latent image is formed is conveyed to the area facing the transfer roller 15. Transfer roller
A voltage of negative polarity is applied to 15. Here, the transfer sheet 16 is conveyed between the conductive substrate 13 and the transfer roller 15,
At this time, toner (L) that has been irradiated with light and has lost its charge
Is injected with a positive charge from the conductive substrate 13 and the transfer sheet 16
The toner (D) that has been transferred to the toner and is not irradiated with light is not transferred.

[0004]

When an image is formed using a photosensitive toner, the uniform formation of a thin toner layer on the conductive substrate 13 is a major factor in determining the quality of the resulting image. .. However, in the above-described device, since the charged toner is formed into a magnetic brush shape by the sleeve 11 and rubbed against the conductive base 13, a thin layer of toner is formed. However, there is a problem in that the layer thickness is not uniform and the image becomes uneven. Further, since the photosensitive toner is charged by friction with the carrier, the charge amount varies, and the low-charged toner is transferred even when not irradiated with light, causing fog. There was also a problem. SUMMARY OF THE INVENTION It is an object of the present invention to solve such a problem and to provide an image forming apparatus capable of forming a thin toner layer having a uniform layer thickness and no variation in charge amount.

[0005]

In order to achieve the above object, the image forming apparatus of the present invention forms a thin photosensitive toner layer on a conductive substrate and exposes the thin toner layer to form an image. In the image forming apparatus, a roller is provided between the toner thin layer forming portion and the toner thin layer exposing portion, the roller being in pressure contact with the conductive substrate and being applied with a voltage having the same polarity as the toner charging polarity. ing. A plate-like member for cleaning toner may be pressed against the roller, and a release agent such as fluorine may be applied to the surface of the roller.

[0006]

By doing so, the toner thin layer formed on the conductive substrate by being charged becomes uniform by being pressed against the roller. Further, a voltage having the same polarity as the toner charging polarity is applied to the roller, and the contact charging with the roller eliminates the uneven charging of the toner thin layer. Further, the abnormal toner having a high dark conductivity is injected with a charge and adheres to the roller to be removed. Therefore, a thin toner layer having a uniform layer thickness and a uniform charge amount can be obtained, and image unevenness and fog can be reduced.

[0007]

Embodiments of the present invention will now be described with reference to the drawings.
explain. FIG. 2 shows a schematic diagram of an image forming apparatus embodying the present invention. In the figure, a roller 20 is provided between the toner thin layer forming portion (the position of the sleeve 11) and the exposure portion (the position of the exposure device 14) in pressure contact with the conductive substrate 13. Roller 20 is C
The toner is rotating in the same direction, and a voltage having the same polarity as the charging polarity of the toner is applied.

FIG. 1 shows an enlarged view of the portion of the roller 20. The thin toner layer formed in the vicinity of the sleeve 11 does not have a uniform layer thickness as described above, and its charge amount also varies. Roller 20 provided in pressure contact with conductive substrate 13
Causes the toner thin layer to be pressed into contact, so that the toner thin layer is smoothed and the layer thickness becomes uniform. In addition, a voltage is applied to the roller 20, whereby charges are applied to the toner and the charge amount becomes uniform. Further, the toner having high conductivity, that is, so-called dark conductivity, which is not irradiated with light, is attached to the roller 20 by the voltage of the roller 20 and removed. A blade 21 for scraping off the abnormal toner attached to the roller 20 is installed so as to come into pressure contact with the roller 20, and the scraped toner is collected in a collecting container 22. In addition, the surface of the roller 20 is coated with fluorine or the like in order to reduce the mechanical adhesive force with the toner.

[0009]

As described above, according to the present invention,
The toner thin layer, which is charged and formed on the conductive substrate and has a non-uniform amount of charge, has a uniform layer thickness by being pressed against the roller. Further, since a voltage is applied to the roller, the variation in charging is eliminated by coming into contact with the roller. Further, the abnormal toner having a high dark conductivity is injected with a charge and adheres to the roller to be removed. Therefore, a toner thin layer having a uniform layer thickness and a uniform charge amount can be obtained, and image unevenness and fog can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a roller provided in an image forming apparatus embodying the present invention.

FIG. 2 is a schematic diagram of an image forming apparatus embodying the present invention.

FIG. 3 is a schematic diagram of a conventional image forming apparatus.

[Explanation of symbols]

 10 Toner Container 11 Sleeve 12 Magnet 13 Conductive Substrate 14 Exposure Device 15 Transfer Roller 16 Transfer Sheet 20 Roller 21 Blade 22 Collection Container

Claims (3)

[Claims] 1. An image forming apparatus for forming a photosensitive toner thin layer on a conductive substrate and exposing the toner thin layer to form an image, the toner thin layer forming section and the toner thin layer. Between exposed parts,
An image forming apparatus comprising: a roller which is in pressure contact with the conductive substrate and to which a voltage having the same polarity as the toner charging polarity is applied. 2. The image forming apparatus according to claim 1, wherein a plate-like member for cleaning toner is pressed against the roller. 3. The image forming apparatus according to claim 1, wherein the surface of the roller is coated with a release agent such as fluorine.