JPS6243664A - Image forming device - Google Patents

Abstract

PURPOSE:To adjust the atmosphere on the surface of a photosensitive body and in a corona charger and to prevent images from becoming disordered by heating an dust-removed air flow by heat generated by a heat fixing device and performing corona discharging while blowing the air flow into the corona charger. CONSTITUTION:An electrostatic latent image formed on a photosensitive body 7 which is charged electrostatically by the corona charger 2 advance is developed by a developing device 12 and the transfer image on transfer paper is fixed by the fixing device 18. The fixing device 18 has a fixing roller 28 for heating and a pressure roller 29 for pressure application provided in a frame body 27, and heaters 28a and 28b are arranged in the roller 28. The air flow B is blown to the surface of the photosensitive body 1 through an opening bored in the top surface of the case of the charger 2. An air guide member is composed of a duct 26 and external air is sucked by an air fan 25 and blown in the charger 2 through a filter 24 to flow out along the photosensitive body 1. A part of the duct 26 is provided right above the fixing device 18 and the air flow becomes a hot wind, which is blown into the charger. Consequently, images are prevented from becoming disordered.

Description

Detailed Description of the Invention A. Purpose of the Invention [Industrial Field of Application] [Unpublished] η relates to an image forming apparatus such as an electrophotographic copying machine, and particularly relates to the surface of a photoreceptor drum which is an image bearing member thereof. Corona to give static charge to F? Regarding tF electric appliances.

[Conventional technology]

In the image forming apparatus described in L, in order to obtain a good image, it is necessary for the corona charger to apply a uniform load to the surface of the photoreceptor. No.

However, when the drum 1 of the photoreceptor rotates, a drum wind M is generated as shown in FIG. 2, and the scattered developer and minute foreign matter floating inside the image forming apparatus are blown into the charger 2. It adheres to the corona wire 2a, preventing uniform discharge.

Therefore, as shown in FIG. 3, the filter 24 is
The air flow N from which dust has been removed is blown into the corona charger 2 to prevent the wire 2a from becoming contaminated.

When this method is used, harmful charging reaction products remaining in the corona charger 2 can also be blown out to the outside, so that relatively good images can be obtained.

[Problem that the invention seeks to solve]

The above-mentioned charging reaction products are generated by gaseous charging reactions such as ozone, ammonium nitrate, and various ions generated during corona discharge, and because they are hydrophilic, the charged reaction products remain near the surface of the photoreceptor. The reaction product absorbs moisture and covers the surface of the photoreceptor, making the charge applied by the corona charger unstable, causing the latent image to become distorted and causing image disturbances called image deletion, making it impossible to obtain a clear image. Ta.

The adhesion of this charged reaction product to the surface of the photoreceptor cannot be completely prevented by the air flow N shown in FIG.

The present invention aims to solve this problem.

Summary: Structure of the Invention [Means for Solving the Problems] The present invention develops an electrostatic Wi image formed on an image bearing member charged in advance by a corona charger, and transfers the developed image to a transfer material. In an image forming apparatus that thermally fixes the transfer material, the dedusted air stream is heated by heat generated in the heat fixing device and is blown into the corona charger to perform corona discharge. This is an image forming apparatus with features.

[For production]

The dedusted outside air is heated by the heat generated by the fixing device and is blown onto the surface of the photoreceptor through the corona charger, so that harmful ozone and hydrophilic charging reaction products that are filled in the corona charger are removed along with fine dust to the outside of the corona charger. By forcefully drying the hydrophilic charged reaction product that has absorbed moisture while blowing it away, the atmosphere on the photoreceptor surface and inside the corona charger is adjusted, and a high-quality image without image deletion can be obtained.

〔Example〕

Hereinafter, details of the present invention will be explained using specific examples with reference to the drawings.

FIG. 1 shows the main parts of an example of an image forming apparatus to which the present invention can be applied.

l is a photoreceptor as an image carrier, which rotates in the direction of arrow A;
As it rotates, it is first uniformly charged by the corona charger 2 6
Next, the reflected light image of the document 0 illuminated by the illumination light source 3 is reflected on the mirrors 4 to 6. An image is formed on a photoreceptor l via a lens 7 and mirrors 8 to 10, and a latent image corresponding to the light image is formed.

Next, the non-image area exposure lamp 11 is turned on, illuminating the outside of the imaging exposure range of the photoreceptor l which is further rotating, and short-circuiting and extinguishing the primary charge. The formed latent image is developed by a developing device 12, and the obtained toner image is transferred by the action of a corona charger 16 onto a transfer paper fed from a paper feeding device (not shown) via a registration roller 13 and a guide 14. be done. After the transfer, the transfer paper is separated from the photoreceptor 1 by the separation charger 17, sent to the fixing device 18 by the conveyor 15, the toner image is fixed on the transfer paper, and the paper is ejected onto the paper ejection tray by the paper ejection rollers 19 and 2o. Ru.

On the other hand, the toner remaining on the photosensitive drum l is removed by the cleaner 2.
2, and is discharged into a waste toner collection container (not shown) located at the upper front side of the drawing. Further, unnecessary charges remaining on the photoreceptor l are removed by illumination light from the illumination device 2123. The photosensitive drum 1 is then charged again by the charger 2, and the above process is repeated.

The fixing device 18 includes a fixing roller 28 for heating and a pressure roller 29 for applying pressure within a frame 27. Heaters 28a and 28b are disposed within the fixing roller 28, and the surface temperature of the fixing roller is detected by a temperature detection means 30, and is generally controlled to a surface temperature of tao''c to 200°C.

As a specific example of applying the present invention to the above-mentioned known configuration, the upper surface of the case of the corona charger 2 has an opening extending in the longitudinal direction over the entire corona charging area, and the air flow B passes through the opening. Sprayed onto the surface of the body.

The air flow guiding member is configured as a duct 26, and outside air is sucked into the duct by a blower fan 25 disposed in the duct, and the air is removed from dust through a filter 24 provided at the suction port and blown into the corona charger 2. and flows out along the photoreceptor l.

The above-mentioned duct 26 is partially disposed in the vicinity of the fixing device 18 so that it can be sufficiently heated by heat radiation, convection, etc. from the fixing device 18, and the air flow passing through the duct 26 is arranged to conduct heat. The structure is such that the corona charger 2 is heated and turned into warm air that is blown into the corona charger 2. In order to increase heat absorption efficiency, heat exchange fins 26a are installed on the wall of the duct 26 facing the heat fixing device.
may be formed.

As a result of experiments based on this configuration, we found that the corona zone
The airflow blowing inside has a temperature of about 5
0″0φ wind speed approx. 1.5m/sφ air volume approx. 0.54mj/s
A good image with no image blurring was obtained in the in.

C. Effects of the Invention I- As explained above, by blowing hot air into the corona charger using the heat dissipated by the fixing device, ozone and other substances that remain in the corona charger and have a negative effect on images can be removed. By discharging the charged reaction product and forcefully drying the hydrophilic charged reaction product that has absorbed moisture, it is possible to prevent image disturbance called image flow 11'.

In addition, the simple structure of installing the air flow guide duct near the fixing device does not require heating energy, which has the effect of making it possible to reduce the cost.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing an example of an electrophotographic apparatus to which the present invention is applied, and FIG. 2 is a vertical sectional view of a corona charger for explaining a conventional example. l... Image-bearing photoreceptor, 2... Corona charger, 18.
...Heat fixing device, 24...Dust removal filter, 25...Blower, 26...Duct.

Claims (1)

[Claims] (1) In an image forming apparatus that develops an electrostatic latent image formed on an image bearing member pre-charged by a corona charger, transfers the developed image to a transfer material, and heat-fixes the transfer material, dust removal is performed. An image forming apparatus characterized in that the air flow is heated by heat generated in a heat fixing device and is blown into the corona charger to perform corona discharge.