JPH04366976A - Image forming device - Google Patents

Abstract

PURPOSE:To remove-developer sticking to a grid electrode without damaging the grid electrode of a scorotron electrifier by applying an AC voltage to the grid electrode. CONSTITUTION:At the time of cleaning the grid electrode 12b, the electrode 12b is connected to an AC power source 16 by a switch 14, and the high AC voltage is applied thereto from the AC power source 16, so that the developer sticking to the electrode 12b comes to a powder cloud state. In the vicinity of the electrode 12b, an air flow generating means for generating an air flow, for example a fan 17, is provided. At the time of cleaning the electrode 12b, this fan 17 rotates to generate an air flow in the vicinity of the electrode 12b, so that the developer in the powder cloud state sticking to the electrode 12b is removed from the electrode 12b by the air flow.

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 such as a copying machine, a printer, or a facsimile machine using a scorotron charger having a grid electrode.

0002

2. Description of the Related Art Conventionally, in an image forming apparatus using a scorotron charger having a grid electrode, during image forming operation, an image carrier consisting of a photoreceptor is rotated by a motor and uniformly charged by the scorotron charger. ,
This photoreceptor is subjected to image exposure using an exposure means to form an electrostatic latent image, and this electrostatic latent image is developed with a developer using a developing device to make a developed image by attaching toner to the electrostatic latent image. Thereafter, this developed image is transferred to a transfer material from a paper feeder by a transfer device and fixed by a fixing device. and,
After the image transfer, residual toner on the photoreceptor is removed by a cleaning device, and the photoreceptor is neutralized by a static eliminator, thereby making the photoreceptor reusable.

[0003] Furthermore, Japanese Patent Laid-Open No. 136751/1983 discloses a method of shaking off foreign matter adhering to the grid electrode in a scorotron charger used in an image forming apparatus by vibrating the grid electrode with an ultrasonic vibrator. What was done is listed.

0004

[Problems to be Solved by the Invention] In the above-mentioned image forming apparatus, the developer floats in the apparatus due to scattering of the developer from the developing device or scattering of the developer during the above-mentioned image forming process. A problem arises in that the inside of the apparatus is contaminated by the developer. In particular, the problem arises that the floating developer adheres to the grid electrode of the scorotron charger, degrading the charging performance of the scorotron charger.

FIG. 3 shows the surface potential of the photoreceptor normally charged by the scorotron charger in the width direction of the photoreceptor in the image forming apparatus, and FIG. The surface potential of a photoreceptor charged by a scorotron charger when attached to an electrode is shown in the width direction of the photoreceptor. As can be seen from FIGS. 3 and 4, when the photoreceptor is normally charged by the scorotron charger, the surface is charged uniformly in the width direction, and when the developer adheres to the grid electrode of the scorotron charger, The surface is charged unevenly in the width direction.

Furthermore, in the method described in Japanese Patent Application Laid-open No. 136751/1984, since the grid electrode is vibrated by an ultrasonic vibrator, there is a risk that the grid electrode may be damaged.

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks and to provide an image forming apparatus capable of removing developer attached to a grid electrode of a scorotron charger without damaging the grid electrode.

[0008]

Means for Solving the Problems To achieve the above object, the invention of claim 1 provides an image forming apparatus that charges an image carrier with a scorotron charger having a grid electrode, in which an alternating current voltage is applied to the grid electrode. According to a second aspect of the present invention, there is provided an image forming apparatus in which an image bearing member is charged by a scorotron charger having a grid electrode, and the image bearing member is cleaned by a cleaning device. The image carrier is equipped with a voltage applying means for applying a predetermined voltage to the image carrier.

[0009]

In the first aspect of the invention, an alternating current voltage is applied to the grid electrode of the scorotron charger by the alternating current voltage applying means, and the developer adhering to the grid electrode becomes a powder cloud and is removed from the grid electrode.

Further, in the invention of claim 2, a predetermined voltage is applied to the image carrier by the voltage applying means, and the developer adhering to the grid electrode becomes a powder cloud and adheres to the image carrier from the grid electrode. It is later removed by a cleaning device.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention. This embodiment is an electrophotographic image forming apparatus, and during an image forming operation, an image carrier 11 consisting of a photoreceptor drum is rotated by a motor and uniformly charged by a scorotron charger 12. An electrostatic latent image is formed on the body drum 11 by image exposure by an exposure means. Further, as is well known, this electrostatic latent image is developed with a developer by a developing device and becomes a developed image by adhering toner, and the developed image on the photoreceptor drum 11 is fed from a paper feeding device by a transfer device. The image is transferred to a paper transfer material and fixed by a fixing device. After the image transfer, residual toner on the photoreceptor drum 11 is removed by a cleaning device, and the photoreceptor drum 11 is neutralized by a static eliminator.
becomes reusable.

The scorotron charger 12 is composed of a corona discharge electrode 12a made of a corona discharge wire, a grid electrode 12b, and a casing 12c.
2a is disposed within the casing 12c. The casing 12c has an opening at a portion facing the photoreceptor drum 11, and the grid electrode 12b is installed in this opening. A high DC voltage is applied to the corona discharge electrode 12a from a high voltage power source 13, and the photosensitive drum 11 is grounded. The switch 14 is controlled by the control unit to selectively connect the grid electrode 12b to either the DC power source 15 or the AC power source 16.

During the image forming operation, the grid electrode 12b
is connected to a DC power source 15 by a switch 14, and a predetermined DC voltage is applied from the DC power source 15, and the corona discharge electrode 12a uniformly charges the photoreceptor drum 11 by performing corona discharge via the grid electrode 12b.

Grid electrode 12b during non-image formation
The cleaning is performed, for example, when the power switch is turned on or every time a specific number of images are formed. When cleaning the grid electrode 12b, the grid electrode 12b is connected to the AC power supply 16 by the switch 14, and the grid electrode 12b is connected to the AC power supply 16 by the switch 14.
A high AC voltage is applied to the grid electrode 12b, and the developer attached to the grid electrode 12b becomes a powder cloud. An airflow generating means for generating an airflow, such as a fan 17, is installed near the grid electrode 12b. When cleaning the grid electrode 12b, the fan 17 rotates to generate an airflow near the grid electrode 12b, and the developer that has adhered to the grid electrode 12b and has become a powder cloud is removed from the grid electrode 12b by the airflow. The grid electrode 12b is thereby cleaned.

FIG. 2 shows another embodiment of the invention. In this embodiment, in the above embodiment, the switch 18 is controlled by the control section to connect the photoreceptor drum 11 to the ground point and the DC power supply 1.
9, and instead of removing the developer that has adhered to the grid electrode 12b and become a powder cloud using the fan 17, it is removed using the cleaning device 20. The other parts are constructed in the same manner as in the above embodiment. The cleaning device 20 includes, for example, a fur brush 20a and a cleaning blade 20b, and the DC power source 19 generates a polar DC voltage that attracts the developer.

During the image forming operation, the photosensitive drum 11 is connected to the ground point by the switch 18, and operates in the same manner as in the above embodiment.

Grid electrode 12b during non-image formation
The cleaning is performed, for example, when the power switch is turned on or every time a specific number of images are formed. When cleaning the grid electrode 12b, the grid electrode 12b is connected to the AC power supply 16 by the switch 14, and a high AC voltage is applied from the AC power supply 16, and the grid electrode 12b is
The developer attached to b becomes a powder cloud. At this time, the photoreceptor drum 11 is connected to the DC power supply 19 by the switch 18, and a DC voltage with a polarity that attracts the developer is applied from the DC power supply 19, and the developer adhered to the grid electrode 12b and becomes a powder cloud. The grid electrode 12b is cleaned by adsorbing the agent. Grid electrode 1
The developer adsorbed onto the photoreceptor drum 11 from 2b is conveyed by the photoreceptor drum 11 as it rotates, and is removed from the photoreceptor drum 11 by the cleaning device 20.

[0018]

[Effect of the invention] As described above, according to the invention of claim 1,
In an image forming apparatus that charges an image carrier with a scorotron charger having a grid electrode, an AC voltage applying means for applying an alternating voltage to the grid electrode is provided, so that the developer attached to the grid electrode of the scorotron charger is powdered. It can be removed from the grid electrode in a cloud state, and the grid electrode will not be damaged because it will not vibrate.

According to the second aspect of the invention, in the image forming apparatus, the image bearing member is charged by a scorotron charger having a grid electrode, and the image bearing member is cleaned by a cleaning device. Since the voltage application means for applying a predetermined voltage is provided, the developer attached to the grid electrode is turned into a powder cloud by applying a voltage to the image carrier by the voltage application means, and the developer is made to adhere to the image carrier from the grid electrode. It can be removed by a cleaning device.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

FIG. 2 is a schematic diagram showing another embodiment of the invention.

FIG. 3 is a diagram showing the surface potential of a photoreceptor normally charged by a scorotron charger in the width direction of the photoreceptor in the image forming apparatus.

FIG. 4 is a diagram showing the surface potential of the photoreceptor charged by the scorotron charger in the width direction of the photoreceptor when developer adheres to the grid electrode of the scorotron charger in the image forming apparatus.

[Explanation of symbols]

11 Photosensitive drum 12 Scorotron charger 12b Grid electrode 14, 18 Switch 16 AC power supply 17 Fan 19 DC power supply 20 Cleaning device

Claims (2)

[Claims] 1. An image forming apparatus that charges an image carrier with a scorotron charger having a grid electrode, the image forming apparatus comprising an AC voltage applying means for applying an AC voltage to the grid electrode. 2. An image forming apparatus in which an image bearing member is charged by a scorotron charger having a grid electrode and the image bearing member is cleaned by a cleaning device, comprising a voltage applying means for applying a predetermined voltage to the image bearing member. An image forming apparatus comprising: