JPH0573656U - Charger - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a charger having a simple configuration, which is less susceptible to environmental influences such as temperature and humidity, and which is capable of stable operation. [Structure] The charger 10 is arranged so as to face a photosensitive drum 16 formed by applying a photosensitive member 14 on the surface of a cylindrical conductor 12. In the charger 10, a high electric resistance body 20 is arranged on the surface of an insulating substrate 18, and the high electric resistance body 20 is arranged on the surface of the high electric resistance body 20.
In, the electrodes 22 are arranged so as to form a stripe shape. Further, an insulator 24 is arranged on the surface of the electrode 22.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a charger used for charging a charge receptor such as a photoconductor in an electrophotographic image forming apparatus or the like.

[0002]

[Prior Art]

 Conventionally, in an electrophotographic image forming apparatus or the like, a corotron charger 80 as shown in FIG. 4 is generally used as a charger for charging a photoreceptor. The corotron charger 80 is configured by surrounding the discharge wire 82 with a shield case 84, and is disposed so as to face a photosensitive drum 89 configured by providing a photoconductor 86 on the surface of a conductor 88. There is. In this corotron charger 80, when a high voltage is applied to the discharge wire 82, corona discharge is generated between the discharge wire 82 and the photoconductor 86. Then, the ions generated by this corona discharge flow into the photoconductor 86, thereby charging the photoconductor 86.

A proximity type charger 90 as shown in FIG. 5 has also been proposed for the purpose of further downsizing the charger and reducing the amount of ozone generated. This proximity type charger 90 is configured by attaching a high electrical resistance body 92 having a high surface resistance of about 10 ⁶ to 10 ⁸ Ω to an electrode 91. The high electric resistance 92 and the photoconductor 94 are opposed to each other so that the gap between the conductor 96 and the photoconductor drum 89 formed by providing the photoconductor 94 on the surface is 0.3 to 1.0 mm. It is arranged. In this proximity type charger 90, when a high voltage is applied to the high electric resistance body 92, corona discharge is generated between the high electric resistance body 92 and the photoconductor 94. Then, the ions generated by this corona discharge flow into the photoconductor 94 to charge the photoconductor 94.

[0004]

[Problems to be solved by the device]

 However, in the former corotron charger 80, since the distance between the discharge wire 82 and the photosensitive member 86 is large, the ions may flow to other than the photosensitive member 86, and the ratio of being effectively used is small. It was Therefore, it is necessary to apply a higher voltage to the discharge wire 82 in order to sufficiently charge the photoconductor 86, and as a result, there is a drawback that the amount of ozone harmful to the human body increases.

Further, in the latter proximity type charger 90, the amount of ozone generated is reduced, but when the resistance value of the resistor 92 is lowered in order to increase the amount of charge on the surface of the photoconductor 94, When spark discharge occurs due to the influence of temperature, humidity, etc., it takes a certain amount of time to raise the voltage of the charger 90 again. That is, the corona discharge generated between the high electric resistance body 92 and the photoconductor 94 is stopped until the voltage of the charger 90 rises to a voltage sufficient to cause the discharge, so that the photoconductor 94 is stopped. An uncharged portion is formed on the surface of the sheet, and as a result, an image with good image quality cannot be obtained. When the DC voltage applied to the high electric resistance 92 is increased in order to increase the amount of charge on the surface of the photoconductor 94, the ions generated by corona discharge are excessively concentrated on the photoconductor 94 and ions of the same polarity are generated. This causes a shift to a so-called streamer mode, which is considered to be caused by the repulsion of the toner, which causes a problem that the charge distribution on the surface of the photoconductor 94 becomes island-shaped.

For these reasons, in the proximity type charger 90, there are contradictory factors between the generation of stable corona discharge and the increase of the charge amount, and uniform and stable charging is performed. Therefore, there is a drawback that it is very difficult to set the environment.

The present invention has been made in order to solve the above-mentioned problems, and provides a charger having a simple structure, being less susceptible to environmental influences such as temperature and humidity, and capable of stable operation. The purpose is to

[0008]

[Means for Solving the Problems]

 In order to achieve this object, the charger of the present invention is provided with a high electric resistance member disposed in the vicinity of a charge acceptor and in contact with the high electric resistance member, and supplies a voltage to the high electric resistance member. An electrode for producing a potential difference between the high electrical resistance and the charge acceptor, and by applying a voltage to the electrode, the high electrical resistance and the charge acceptor are separated from each other. Is a charger that ionizes the molecules present in the above and charges the charge acceptor with the generated ions, wherein the electrodes are formed in stripes on the high electrical resistance body.

The electrodes may be arranged on the charge acceptor side of the high resistance body.

An insulator may be arranged on the surface of the electrode.

[0011]

[Action]

 In the charger of the present invention having the above structure, the high electric resistance is generated by supplying a voltage to the high electric resistance through the electrode to generate a potential difference between the high electric resistance and the charge acceptor. Ions are generated between the charge acceptor and the charge acceptor. The ions are attracted to the charge acceptor and charge it. At this time, the electrodes are formed in stripes on the high electric resistance body.

[0012]

【Example】

 An embodiment in which a charger embodying the present invention is mounted on a process unit used in a laser printer will be described below with reference to the drawings.

First, the configuration of this embodiment will be described.

As shown in FIGS. 1 and 2, the charger 10 according to the present embodiment is arranged so as to face a photosensitive drum 16 formed by applying a photosensitive member 14 on the surface of a cylindrical conductor 12. Has been done. In this charger 10, a high electric resistance body 20 is arranged on the surface of an insulating substrate 18, and an electrode 22 is formed on the surface of the high electric resistance body 20 so as to form a stripe shape in the high electric resistance body 20. It is configured by arranging. Further, an insulator 24 is arranged on the surface of the electrode 22. Aluminum having a film thickness of 1 μm or less is preferably used for the electrode 22, and silicon dioxide is preferably used for the insulator 24. The conductor 12 is grounded and the electrode 22 is connected to a voltage generator 26. As the high electric resistance body 20, titanium oxide or tantalum nitride having a surface resistance of 10 ⁶ to 10 ⁸ Ω and a film thickness of 1 μm or less is preferably used. Then, the charger 10 and the photosensitive drum 16 are arranged such that the interval between the high electric resistance body 20 and the photosensitive body 14 constituting them is 0.3 to 1.0 mm. At this time, the charger 10 and the photosensitive drum 16 are arranged so that the high electric resistance body 20 and the photosensitive body 14 face each other.

Next, the operation of the charger thus configured will be described.

The voltage generator 26 applies a voltage to the electrode 22. This voltage is held at -1.6 kV so that the surface potential of the photoconductor 14 is about -700V.

When a voltage is applied to the electrode 22, a corona discharge is generated between the high electrical resistance body 20 that constitutes the charger 10 and the photoconductor 14 that constitutes the photosensitive drum 16. When this corona discharge occurs, air or the like existing between the charger 10 and the photosensitive drum 16 is ionized to generate ions. Here, the negative ions are attracted to the photoconductor 14 and negatively charge the photoconductor 14. At this time, when the charger 10 is viewed from the side of the photosensitive drum 16 as shown in FIG. 2, the high electric resistance body 20 and the insulating body 24 are alternately appearing, and corona discharge is caused by the high electric resistance body 20. Is generated between the photoconductor 14 and the photoconductor 14, the ions are not excessively concentrated on the photoconductor 14 even if the voltage applied to the electrode 22 is set high in order to increase the surface potential of the photoconductor 14. Stable and uniform charging can be performed without shifting to the mode.

As shown in FIG. 3, the charger 10 having the above-described configuration is mounted on the process unit 1 used in a laser printer (not shown). Then, the photosensitive drum 16 charged by the charger 10 as described above rotates in the direction of arrow a. Next, a laser beam 30 emitted from a laser light emitting element (not shown) is applied to the surface of the photoconductor 14 according to an image such as a character or a figure to be formed, so that an electrostatic latent image is formed on the photoconductor drum 16. It is formed. At this time, the surface potential of the photosensitive member 14 drops to about −100 V only in the irradiated portion. Then, the toner 34 contained in the toner case 32 is conveyed to the developing area by the developing sleeve 36, and the electrostatic latent image on the photosensitive drum 16 is visualized. When the photosensitive drum 16 further rotates, the surface of the photosensitive drum 16 comes into contact with the transfer roller 40 via the paper 38, so that the toner 34 attached to the surface of the photosensitive drum 16 is transferred to the paper 38. At this time, since the photoconductor 14 is uniformly charged by the charger 10, it is possible to form a high quality image on the paper 38.

The sheet 38 after the transfer is fixed and discharged by a fixing unit (not shown). On the other hand, the toner 34 remaining on the photosensitive drum 16 without being transferred to the paper 38 is scraped off by the cleaning blade 42 and stored in the waste toner case 44.

The present invention is not limited to the embodiments described herein, and various modifications can be made without departing from the spirit of the invention. That is, in the present embodiment, an example using a linear electrode is shown, but without being limited to this, any shape of electrode may be used. Further, the voltage applied to the electrodes may be any value up to about -4 kV. Further, although a photosensitive drum is shown as an example of the charge acceptor, a paper-like medium that is electrically charged by ions may be used without being limited to this.

[0021]

[Effect of the device]

 As is clear from the above description, according to the charger of the present invention, the simple configuration of forming the electrodes in stripes on the high electric resistance body does not affect the environment such as temperature and humidity. Therefore, it becomes possible to stably charge the charge acceptor.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of an embodiment embodying a charger of the present invention.

FIG. 2 is a front view showing a state when the charger of this embodiment is viewed from the photosensitive drum side.

FIG. 3 is a cross-sectional view showing the configuration of a process unit including the charger of this embodiment.

FIG. 4 is an explanatory diagram illustrating a configuration of a conventional corotron charger.

FIG. 5 is an explanatory diagram illustrating a configuration of a conventional proximity charger.

[Explanation of symbols]

 10 Charger 14 Photoreceptor 20 High Resistor 22 Electrode 24 Insulator 26 Voltage Generator

Claims (3)

[Scope of utility model registration request] 1. A high electrical resistance body disposed in the vicinity of a charge receptor, and a high electrical resistance body which is provided in contact with the high electrical resistance body and supplies a voltage to the high electrical resistance body, It has an electrode for generating a potential difference between the charge acceptor, and when a voltage is applied to the electrode, the molecules existing between the high electric resistance and the charge acceptor are ionized and generated. In the charger which charges the charge acceptor with ions, the electrode is formed in a stripe shape on the high electric resistance body. 2. The charger according to claim 1, wherein the electrode is arranged on the charge acceptor side of the high resistance body. 3. The charger according to claim 2, wherein an insulator is arranged on the surface of the electrode.