JPS6127569A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent an uneven discharge by executing a discharge by impressing an alternate voltage between an induction electrode and a discharge electrode which have placed a dielectric of an optical penetrability between them, and generating an electric field for leading selectively positive and negative ions generated in the vicinity of the discharge electrode, onto a photosensitive body. CONSTITUTION:A photosensitive body 1 is formed by laminating a photoconductive material 3 and an insulating layer 4 on a conductive material substrate 2. A discharge device 15 provided on its vicinity consists of a transparent dielectric 16 of mica, glass, etc., a transparent induction electrode 17 of SnO2, etc., and a discharge electrode 18, and an alternate voltage power source 19 is connected between the induction electrode 17 and the discharge electrode 18. A bias is impressed to the conductive material substrate 2 and the discharge electrode 18 by a power source 20. When a voltage of the alternate voltage power source 19 is raised, a discharge is generated in the vicinity of the discharge electrode 18, sufficient ions of positive and negative are generated evenly. This ion is extracted selectively by controlling the bias voltage 20, and the surface of an insulator 4 is electrostatically charged evenly to a desired value of a specified polarity. In this way, a good image which is not influenced by an uneven discharge is obtained.

Description

[Detailed Description of the Invention] Lord Jiaohang! The present invention relates to an image forming apparatus, and particularly to an electrophotographic apparatus that forms an electrostatic latent image on a photoreceptor and repeatedly uses the photoreceptor after development and transfer.

Traditionally, the Carlson method involves the process of charging, image exposure, and development to form an image, or the 42nd Japanese Patent Publication, which involves the process of secondary charging, image exposure, secondary charging, and development. -23910 Publication, Special Publication No. 43-24
In electrophotographic apparatuses such as the NP method described in Japanese Patent No. 748, corona discharge apparatuses that perform corona discharge by applying a high voltage to a wire with a wire diameter of about 0.1 mm are widely used. However, such a corona discharge device has the disadvantage that the wire is thin and easily damaged, and furthermore, dirt on the wire causes uneven discharge, resulting in non-uniform charging and/or neutralization of the photoreceptor, which significantly impairs image quality. was there. In particular, compared to negative charging, discharge unevenness has a more significant effect on images in secondary charging in which simultaneous exposure is performed. At present, no definitive solution has been obtained regarding this problem.

SUMMARY OF THE INVENTION In view of the above-mentioned points, it is an object of the present invention to provide an image forming apparatus that can form good images by eliminating the influence of discharge unevenness.

11 11 According to the present invention, in an image forming apparatus having a discharge means and an image exposure means, the discharge means has an induction electrode and a discharge electrode facing each other with a dielectric interposed therebetween, and there is a gap between the two electrodes. It has at least one discharger that generates a discharge from the discharge electrode by applying an alternating voltage, and further includes selectively ionizing positive or negative ions or both of the positive and negative ions generated near the discharge electrode of the discharger. An image forming apparatus is provided, which has means for generating an electric field that acts in a direction that guides the light onto the photoreceptor, and in which the dielectric is made of a light-transmitting material. An image can be formed.

Figure 1 shows an image forming apparatus according to an embodiment of the present invention, taking an electrophotographic apparatus as an example. It has a surface insulating layer, is rotatably supported, and rotates in the direction of rotation shown by the arrow in the figure. A discharger 5 is provided around it to perform primary charging for forming an electrostatic latent image. The discharge polarity is positive when the photoconductive layer of the photoreceptor 1 is of N type, and negative when it is of P type. The electrophotographic apparatus further includes, simultaneously with the original image exposure using the original image exposure light 14,
A discharge device 15 to be described later that generates a secondary discharge consisting of a DC corona discharge or an AC corona discharge of opposite polarity to the above-mentioned secondary corona discharge, or a combination of both, and a light source 8 for full-surface exposure are arranged. . A developing device 9 for developing the electrostatic latent image formed on the photoreceptor l, a transfer corona discharger lO1 for transferring the developed image onto the transfer material 11, and a developer remaining on the transfer detection photoreceptor l. Cleaning means 13 and the like are arranged to remove the.

The photoreceptor 1 has a photosensitive layer made of copper-doped cadmium sulfide and a binder resin on an aluminum cylinder, and the surface thereof is covered with an insulating resin layer such as polyethylene terephthalate.

The steps for obtaining an image copy using the electrophotographic apparatus having the above configuration are as follows.

As the photoreceptor 1 rotates in the direction of the arrow, the surface of the photoreceptor 1 is uniformly charged by a discharger 5 for -order charging.

Next, the surface of the photoreceptor 1 is subjected to original image exposure using the original image exposure light 14, and at the same time, static electricity is removed using a discharger 15, which will be described later. A high-contrast electrostatic latent image is formed. The electrostatic latent image formed in this manner is visualized, that is, developed, in the developing device 9 by, for example, sleeve development. Then, a transfer material 11 is superimposed on this developed image, and the transfer corona discharger 10 is
After the transfer is completed, the transfer material 1.1 is separated from the photoreceptor 1 and fixed by a fixing device (not shown) to obtain a copy. On the other hand, the residual agent on the surface of the photoreceptor 1 after the transfer is completed is removed by the cleaning means 13. Then, an electrostatic latent image is subsequently formed on the photoreceptor 1.

Next, a discharger (indicated by 15 in FIG. 1) used for secondary charging in an embodiment of the present invention will be described.

FIG. 2 is a sectional view of a discharge device for secondary charging used in the image forming apparatus of the present invention.

A discharger 15 is arranged with respect to the photoreceptor l, which is a charged and charged object. The discharge vessel 15 includes a transparent dielectric material 16 such as mica, glass, or polyester, and a transparent induction electrode 1 such as Sn02.
7. It has a discharge electrode 18. Alternating voltages are applied between the induction electrode 17 and the discharge electrode 18 by an alternating voltage power source 19.

Note that the alternating voltage is not limited to a sinusoidal waveform, but may be a pulse waveform.

Here, in the present invention, the discharge electrode 18 is an electrode exposed to the air, and means an electrode in which an electric field is concentrated at this electrode portion.

On the other hand, as mentioned above, the photoreceptor l has the photoconductor 3 and the insulator 4 on the conductor base 2, and a bias voltage is applied from the bias power supply 20 between the conductor base 2 and the discharge electrode 18. is applied.

This bias voltage is not limited to direct current, but may be biased alternating current so that specific ions can be extracted.

Next, a method of static elimination or charging will be described below. Induction electrode 17
An alternating voltage is applied from an alternating voltage power supply 19 between the discharge electrode 18 and the discharge electrode 18, thereby generating a discharge near the discharge electrode 18. At this time, sufficient positive and negative ions are generated evenly near the discharge electrode 18. These positive and negative ions are selectively extracted by a bias voltage applied between the discharge electrode 18 and the conductive base 2 to make the surface of the insulator 4 of the photoreceptor 1 have a specific polarity and a desired value. It can be charged evenly.

In this explanation, the charging of the photoreceptor l has been explained as an example, but the photoreceptor l can be neutralized by grounding either the discharge electrode 18 or the induction electrode 17, or by applying alternate voltages as a bias voltage. can do. In this case, it is desirable to arrange the discharge electrode 18 and the photoreceptor l close to each other in order to improve the static elimination efficiency.

The alternating voltage applied between the induction electrode 17 and the discharge electrode 18 is not necessarily a so-called AC voltage, but may be a rectangular wave voltage or a pulse voltage.

In this embodiment, a case has been described in which a DC voltage is applied to the discharge electrode 18 to generate an electric field that moves ions onto the photoreceptor l, but this voltage may also be applied to the induction electrode 17.

Further, the power source 20 may be a direct current or a pulsating current as long as it can pull the ions generated near the discharge electrode 18 toward the photoreceptor l.

Here, since the dielectric 16 and the induction electrode 17 of the discharge vessel 15 are made of a transparent material, the discharge vessel 15 has a characteristic property of transmitting light, which is not found in conventional discharge vessels of this type. It can also be applied to parts of the electrophotographic process that require charging or neutralization and exposure (including image exposure) at the same time. Moreover, 1. The action of the alternating electric field generated in the vicinity of the discharge electrode 18 repels charged objects and also has the effect of brushing off objects attached to the surfaces of the discharge electrode 18 and the dielectric 16, thereby preventing uneven discharge due to dirt on the discharge electrode 18. Uniform charge removal and charging can be obtained.

4 to 9 show the configuration of the discharge device 15. FIG. 4 and 7 show the case where there is only one discharge electrode 18, and the material of the discharge electrode 18 is, for example, Ni or W.

For example, in the configuration shown in FIG. 4, the width of the discharge electrode 18 is set to 1 mm or less. Alternatively, as shown in FIGS. 5 and 8, a plurality of discharge electrodes 18 may be provided, and light may be passed between them. To obtain a similar effect, the discharge electrode 18 may be configured as shown in FIGS. 6 and 9 for transmitting light.
Although it is possible to use Sn02 itself, it is not preferable in terms of wear resistance of the electrode due to discharge.

Note that there is no problem in using S n02 for the induction electrode 17 because there is no wear of the electrode due to discharge1 ,
Preferably, by setting it to 200 to 2.07zm,
Compared to conventional corona dischargers, stable and uniform discharge can be obtained at all times even at a significantly lower voltage (for example, 2 KVpp or less), and abundant ions are generated around the discharger 15.
When such a thickness is used, the thickness is insufficient in terms of strength. In this case, as shown in FIGS. 7, 8 and 9, a reinforcing member 21 made of a transparent material may be added to the back surface.

Further, by selecting an appropriate material, it is possible to give the reinforcing member 21 or the dielectric 16 the characteristic of a filter that cuts out the light components of the harmonics in a specific region.

FIG. 1θ shows an embodiment of the present invention relating to an electrophotographic apparatus for forming images using a photoreceptor 1 (see FIG. 3) having no insulating layer on the surface of the photoconductive layer 3. FIG. A discharge device 15-1 removes static electricity from the photoreceptor l and exposes the entire surface to light.
Next charging by discharge device 15-2, followed by image exposure 14
As a result, an electrostatic latent image is formed. The electrostatic latent image thus formed is developed by the developing device 9, and the developed image is transferred to the transfer paper by the action of the transfer charger 15-4. Before this transfer, pre-transfer charging and simultaneous exposure are performed to facilitate the transfer. The present invention is also applicable to the pre-transfer charger 15-3 for this purpose, or the above-mentioned discharger 15-1 for simultaneous discharge and full-surface exposure.

Further, in this embodiment, other dischargers having the configuration shown in FIG. 2 are used, but in these, the dielectric 16 does not need to be transparent; The corona dischargers 5 and 10 may also be replaced with dischargers of this type in the embodiment. Furthermore, in the embodiment shown in FIG. 1 as well, the discharger for simultaneous charge removal and full-surface exposure shown in FIG. 10 may be used as the charge removal device; A discharger for simultaneous exposure may also be used.

[First Standal Difference] As explained above, according to the present invention, good image formation is performed without being affected by discharge unevenness.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a sectional view of a discharge vessel used in the image forming apparatus according to an embodiment of the present invention. FIG. 3 is a sectional view of another photoreceptor used in an image forming apparatus. FIGS. The 1θ diagram is a sectional view of an image forming apparatus according to another embodiment of the present invention. Explanation of symbols Dielectric 1...-16 Induction electrode...@17 Discharge electrode...18 Discharge device am 11a e l 5 Figure 1 Figure 2 Figure 3 Figure 4 Figure 7 Figure 5 Figure 8 Figure 9 Figure 61. 1 Figure 10 9

Claims (1)

[Scope of Claims] An image forming apparatus having a discharge means and an image exposure means, wherein the discharge means has an induction electrode and a discharge electrode facing each other across a dielectric, and alternately applies a voltage between the two electrodes. , has at least one discharger that generates discharge from the discharge electrode, and further includes selectively directing positive, negative, or both of the positive and negative ions generated near the discharge electrode of the discharger onto the photoreceptor. An image forming apparatus comprising: means for generating an electric field that acts in a guiding direction; and the dielectric body is made of a light-transmitting material.