JPS59188674A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate an uneven discharge due to contamination of a corona discharge wire, and to execute a uniform discharge extending over a long period of time by operating a means for feeding a clean air into a corona discharge means synchronously with a rotation of an image carrier. CONSTITUTION:A laser light 3 modulated in accordance with a picture signal is made incident to a drum 1, and an electrostatic latent image is formed on the surface of the drum by a corona discharger 4. A clean air passes through a duct 17 and a laser optical path 14 and is fed into the whole area of the discharger 4 by a fan blower 15. An operation of a blower motor synchronizes with a rotation of the drum 1, it is prevented that a powder dust and a foreign matter floating in the air adhere to the discharge wire, and a uniform corona discharge can be executed extending over a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus having a corona discharge means that prevents foreign matter from adhering to a corona discharge wire and thereby causing discharge bugs.

Generally, a corona discharger is used as a corona discharge means for an image bearing member in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus.

A corona discharger applies a high voltage of several KVf to its corona discharge wire to cause a corona discharge to charge or remove static electricity from an image carrier, etc., but this corona discharge also has a dust collection effect. I also have it.

For this reason, dust in the air, scattered toner in electrophotographic devices that use powder developers, and developer vapor in electrophotographic devices that use liquid developers react with corona ions to generate corona ions. Objects adhere to the corona discharge wire. A corona discharge wire soiled in this manner has a reduced discharge efficiency, causes uneven discharge, and causes image stains.

On the other hand, it is known to actively introduce air into the corona discharger to prevent foreign matter from adhering to the discharge wire. A fan propeller or the like is used as a means for guiding this air.

Possible methods for operating the fan/blower include operating at the same time as the main power of the device body is turned on, or operating at the same time as corona discharge.

However, when the fan/blower is activated at the same time as the main power of the device is turned on, the device is in a so-called standby state, and even if the power is turned on, the operation of the photosensitive drum as an image carrier, the roller discharger, etc. is stopped. The state may continue for a long time, resulting in wasted power consumption.

In addition, when operating simultaneously with corona discharge, the fan/blower is located far away from the corona discharger, so corona discharge will occur before clean air reaches the corona discharger, causing floating air to occur. Since corona discharge occurs with dust particles in the air already attached to the corona discharge wire, the effect is insufficient even if clean air is sent.

The present invention has been made in view of the above-mentioned points, and provides an image forming apparatus having a corona-free discharge means that can eliminate discharge bugs caused by contamination of the corona discharge wire and can perform uniform corona discharge over a long period of time. The purpose is to

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view schematically showing a laser beam printer as an example of the image forming apparatus of the present invention.

Reference numeral 1 denotes a photosensitive drum as an image carrier, which is rotated in the direction of arrow A by a driving means (not shown). The surface of the photosensitive drum 1 is uniformly and positively charged by a charger 2. Next, a laser beam 6 modulated according to an image signal is applied to the drum 1, and a DC corona discharger 4 removes the positive charge from the portion where the laser beam is applied. By uniformly irradiating the drum surface with the second pump 5, a contrast in surface potential is obtained, and an electrostatic latent image is formed on the photosensitive drum surface. Note that instead of the DC static elimination described above, AC static elimination using an AC:yrona discharger may be performed.

The electrostatic latent image is visualized by the developer in the developing device 6. Meanwhile, the transfer paper P placed in the paper feed cassette 9 from the paper feed section is sent to the surface of the sheet by the roller 10, and transferred to the transfer paper 11. A negative corona is applied from the back side of the transfer paper P to transfer the toner image on the drum surface. The transfer paper P is guided by a belt to a drying/fixing section 12 and then discharged onto a paper discharge tray 15.

Also, remove toner remaining on the drum surface by cleaning f-f.
The photosensitive drum is removed by the radar 18, and the photosensitive drum is reused.

Next, the blowing means for blowing clean air into the corona discharger 4 will be explained.

In this embodiment, as shown in FIG.
A ventilation means is provided at the top of the. The ventilation means of No. 2 are a fan blower 15, a filter 16, and an outside air intake duct 17.
It is composed of The arrangement of the filter 16 and the fan/blower 5 can be replaced with each other, and by considering the shape of the duct 17, the amount of clean air taken in from outside the device can be controlled. The clean air is sent to the entire corona discharge line of the corona discharger 4 through the duct and the laser beam path box.

The ON and OFF operations of the fan-proar motor are synchronized with the rotation of the photosensitive drum, as shown in the timing chart of FIG. Rotation of the photosensitive drum generally starts slightly before the start of corona discharge and stops slightly after the stop of corona discharge. By operating the fan/blower motor in synchronization with the rotation of the motor, corona discharge occurs after the corona discharge wire is covered with clean air.

For example, the following cases can be considered as a method of synchronizing the operation of a fan, blower, etc. with the rotation of the photosensitive drum.

The photosensitive drum drive and fan-blower drive are performed by ACC.
If there is a mortar, the fan/blower is driven by the AC power source for driving the photosensitive drum.

In addition, if the photosensitive drum is driven by an AC motor and the fan/blower is driven by a DC motor, turn on the AC power source for driving the photosensitive drum, activate means such as a relay, and turn on the DC power source for driving the fan/blower. , 0FFL.

If the photosensitive drum is driven by a DC motor and the fan/blower is driven by a DC motor, the power source for driving the photosensitive drum is changed in the same way as described above. - Drive the blower.

In this way, clean air can be delivered to the corona discharge wire by a simple method of synchronizing the operation of the fan-blower, etc., which is a means for blowing clean air, with the rotation of the photosensitive drum as an image carrier without setting new timing. By spraying the wire, it is possible to prevent dust and foreign matter floating in the air from adhering to the corona discharge wire, and to perform uniform corona discharge over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the image forming apparatus of the present invention, and FIG.
The figure is a timing chart showing the respective operations of the photosensitive drum, corona discharger, and fan/proar motor. In the figure, 1 is a photosensitive drum, 2.4.8.11 is a corona discharger, 15 is a fan-blower, 16 is a filter,
17 represents a duct. Applicant Canon Co., Ltd.

Claims (1)

[Scope of Claims] An image forming apparatus comprising an image bearing member, a corona discharge means for applying corona discharge to the image bearing member, and a blowing means for blowing clean air to the corona discharge means, the blowing means as described above. An image forming apparatus characterized in that the image forming apparatus operates in synchronization with the rotation of an image carrier.