JPH04174462A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the adhesion of nitrogen oxide onto a photosensitive drum and prevent the occurrence of image slur, by providing a convection fan in the vicinity of the photosensitive drum, and stopping exhaust when an image formation process is not conducted, and blowing air to the photosensitive drum by actuating the convection fan, and blowing away ozone gas that is in the vicinity of the photosensitive drum. CONSTITUTION:A convection fan 13 is provided at a position where it blows air against a photosensitive drum 1. The fan 13 does not work during an image formation process, and it is actuated at the time of the stoppage of a main motor 25 driving the drum 1 after the completion of the image formation process. As a result, ozone around a photosensitive body can be scattered, and the adhesion of nitrogen oxide generated by the function of ozone, onto the photosensitive body is prevented, so an image flow phenomenon easy to be generated in a high humidity environment is prevented beforehand, and a quality image can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an image forming apparatus such as an electrophotographic apparatus or an electrostatic printer, and particularly relates to an improvement in air convection control within the apparatus.

"Prior Art" The configuration of a conventional general image forming apparatus is as follows. It has a photoconductive photoreceptor drum, has a primary charger that uniformly charges the photoreceptor drum, and has an optical device that irradiates image light to form a charge density array called an electrostatic latent image,
It has a developing device for supplying a powder developer (referred to as toner) that converts an electrostatic latent image into a visible image using charged powder, and transfers the powder from the photoreceptor to the transfer material, which is the final image output medium. It has a transfer charger as a transfer device for transferring a body image, and further has a fixing device for fixing a powder image on a transfer material to the transfer material. It also includes a cleaning device for removing powder remaining on the photoreceptor after the transfer process.

With the above configuration, the image forming process is performed in the order described above, and finally the transfer material with the image fixed thereon is discharged.

In addition to these basic components, there are various auxiliary devices for practical use, such as a paper feeding device that feeds the transfer material to the transfer charger, a conveyance device that conveys the transferred transfer material to the fixing device, etc. It is being Furthermore, since most charging devices used in image forming devices such as photocopiers utilize high-pressure discharge, they generate ozone 03 gas, so they must be equipped with an exhaust device. There is.

"Problem to be Solved by the Invention" In the conventional example, a discharge device such as a primary charger, a transfer charger, etc. installed around the photosensitive drum is used, but when discharging, the discharge device is in normal operation for charging the intended purpose. In this case, ozone gas is adsorbed and decomposed by an ozone filter installed in the exhaust path by an exhaust fan installed inside the machine.

However, due to limitations in the device configuration, the suction mechanism of the exhaust fan may not be perfect, resulting in ozone gas remaining inside.

The remaining ozone generates nitrogen oxide NOx, which is adsorbed on the photosensitive drum. Paper particles loose from the transfer paper also adhere to the photosensitive drum, and if a high humidity environment is added to the mixed state of these particles, moisture is likely to be adsorbed (and a conductive path is formed on the surface of the photosensitive drum). It has been empirically known that the formation of

For this reason, when the machine is restarted after being left unused for a long time after stopping the machine, the electrostatic latent image is disturbed along the conductive path formed on the photosensitive drum, causing a disturbance called "image deletion" on the transfer paper. Produces an image phenomenon.

"Means for Solving the Problem" According to the present invention, a convection fan is installed near the photosensitive drum, and when the image forming process is not performed, exhaust is stopped and the convection fan is operated to blow air onto the photosensitive drum. By blowing away the ozone gas near the photosensitive drum, it is possible to prevent nitrogen oxides from adhering to the photosensitive drum and prevent image deletion.

Conventionally, even when it was not possible to sufficiently prevent "image deletion" by suction alone, "image deletion" can be prevented because a strong diffusion effect is brought about by a convection fan.

If the convection fan operates during the image forming process, it is undesirable because it will hinder the uniformity of charging in the primary charging process, so it is stopped during the image forming process.

The first aspect of the present invention is an image forming apparatus that has a photoconductive photoreceptor and includes a member including a charger for performing an electrophotographic process along the photoreceptor. An image forming apparatus comprising: an air convection device that blows air toward the body; and a control device that operates when the drive device that drives the photoreceptor is stopped, and causes the air convection device to blow air to the photoreceptor. It is a device.

A second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the air convection device also serves as an exhaust device for sucking air from the photoreceptor side during the image forming process.

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

FIG. 1 is a schematic diagram of an electrophotographic apparatus which is an embodiment of the present invention.

During a copying operation, the photosensitive drum 1 rotates in the direction of the arrow shown in the figure, the ζ pre-exposure device 12 uniformly irradiates the photosensitive drum 1 to eliminate static electricity, and the - wide charger 2 uniformly charges the photosensitive drum 1. Next, light emitted from the optical device 5 hits the document placed on the document table 17, and the reflected light passes through the interior of the optical device 5 as shown in the figure and is image-exposed onto the photosensitive drum 1, forming an electrostatic latent image. The electrostatic latent image is developed by developer 3.
The image is visualized using toner. The toner image carried on the photosensitive drum 1 is transferred by a transfer charger 4 onto a transfer paper 16 that passes through a paper feed guide 11, is synchronized with a registration roller 10, and is conveyed along a transfer guide 9. The transfer paper that has passed through the transfer area is transferred to a fixing device 7 by a conveyor belt 8.
The image is conveyed to the point where it is fixed by the fixing device 7, and then discharged outside the machine. Further, untransferred toner on the photosensitive drum 1 passes through a cleaning device 6 and is removed.

The inside of the exterior cover 21 is partitioned between the optical device 5 and the image forming section below it by a partition wall 22, and an exhaust passage 24 is provided between the cleaning device 6 and the partition wall 23 continuing to the top surface of the cleaning device 6 and the partition wall 22. The exhaust passage 24 communicates via the ozone filter 14 with an exhaust fan 15 whose discharge port communicates with the outside.

A characteristic feature of the present invention is that it includes a convection fan 13. The convection fan 13 is provided at a position to blow air onto the photosensitive drum 1. The convection fan 13 does not operate during the image forming process, but operates when the main motor 25 that drives the photosensitive drum 1 is stopped after the image forming process is completed.

The drive device of the photosensitive tram 1 and the main motor 25 are coupled by a power transmission device (schematically shown) 26. Note that the power transmission device 26 is coupled to other rotating members so as to be interlockable. The control device 27 controls the main motor 25, the exhaust fan 15, and the convection fan 13, the functions of which will be explained with reference to a time chart below.

FIG. 2 shows an example of the configuration of the convection fan 13. That is, five small propellers are arranged side by side at a length that almost matches the width of the photosensitive drum 1 in the axial direction.

The propeller is rotated by a motor. Zenmi, opponent lecture fan 13
is not limited in its format; the photosensitive drum 1
As long as it blows air over the entire width of the
For example, a cross-flow fan having approximately the same length as the photosensitive tram 1 may be used.

FIG. 4 is a time chart showing the operation timing of the main motor 25 that drives the photosensitive drum 1 and the convection fan 13. When the piezoelectric power source is not turned on to the electrophotographic apparatus, the main motor 25, exhaust fan 15, and convection fan 13
has stopped. When the main switch is operated to turn on the main power at time t1, the convection fan 13 starts rotating. As a result, even if there is ozone, nitrogen oxide, or paper dust remaining during the previous copying operation, and the outer periphery of the photosensitive drum 1 absorbs moisture, it dries and diffuses the debris around the photosensitive drum 1, allowing the paper to dry. Blow away the powder. When the normal operation is stopped, the convection fan 13 is in a rotating state, and the exhaust fan 15 and the main motor 25 are in a stopped state. At time t2, the start button of the device is pressed, the convection fan 13 stops, and the main motor 25 and the exhaust fan 15 synchronized with the main motor 25 start. As a result, ozone is generated by each of the chargers 2 and 4 in the machine and is exhausted. At time t3, image formation ends, and as soon as the main motor 25 and exhaust fan 15 stop, convection fan 1
3 starts. As a result, ozone and the like around the photosensitive drum 1 are blown away, and minute foreign matter such as paper dust on the photosensitive drum 1 is removed. When the main switch is turned off at time t4, the convection fan 13 stops.

Although FIG. 4 shows the case of 8 individual copies (one copy), continuous output depends on the operation of the main motor in exactly the same way.

By installing the convection fan 13 as described above and operating it in the sequence described above, it is possible to prevent the occurrence of "image deletion".

"Other Embodiments" FIG. 3 is a schematic diagram of the vicinity of a photosensitive drum of an electrophotographic apparatus showing features of another embodiment.

The convection fan 13' is provided to partition the exhaust passage 24, and the air passage regulating plate 18 extends between the partition wall 22 between the optical device 5 and the vicinity of the primary charger 2, and its width in the direction perpendicular to the plane of the paper in FIG. The length is approximately the same as the length of the primary charger 2. Other structural members are the same as in the first embodiment. However, the exhaust fan provided in the embodiment is not installed in this embodiment.

In this embodiment, the convection fan 13' is a propeller-type electric axial flow fan that can switch the suction direction by forward/reverse rotation of a drive motor, and is electrically controlled. When air is sucked in from the direction and discharged outside the machine via the ozone filter 14 (hereinafter referred to as
Depending on the situation, a mode (hereinafter referred to as an exhaust mode) or a case where outside air is sucked in and blows air onto the photosensitive drum 1 (hereinafter referred to as an inflow mode) is selected depending on the situation.

That is, during image formation, the exhaust mode is selected, and when image output ends and the main motor that drives the photosensitive drum 1 stops, the mode shifts to the inflow mode.

5 shows a time chart showing the timing of the main motor 25 and the convection fan 13'.When the main power is not turned on to the electrophotographic apparatus, the main motor 25 and the convection fan 13' are stopped.At time tl, the main motor 25 and the convection fan 13' are stopped. When the main power is turned on by operating the switch, the convection fan 13' enters the inflow mode, and the drawn outside air is discharged from the convection fan 13', hits the air passage regulating plate 18, changes direction, and is blown onto the photosensitive drum 1. As a result, even if there is ozone, nitrogen oxide, or paper dust remaining during the previous copying operation, and the outer periphery of the photosensitive drum 1 absorbs moisture, it is dried and the gas and paper dust around the photosensitive drum 1 are blown away. When the convection fan 13' is in the inflow mode, the main motor 25 for driving the photosensitive drum 1 is stopped.When the start button is pressed at time t2, the convection fan 13 goes into the exhaust mode and reverses, and the main motor 25 for driving the photosensitive drum 1 is stopped. The motor 25 rotates.As a result, the ozone around each charger arranged around the photosensitive drum 1, especially the wide charger 2, is removed by the convection fan 1.
3', ozone is removed by an ozone filter 14, and the ozone is discharged outside the machine. When the copying ends at time t3, the main motor 25 stops and the convection fan 13' returns to the inflow mode. When the main switch is turned off at time t4, the convection fan 13' stops.

With the above configuration and sequence, the ozone around the photosensitive drum can be exhausted and diffused to prevent "image deletion" from occurring.

Although a separate exhaust fan is not provided in this example, it may be desirable to install an exhaust fan depending on the shape and length of the air path, and this example does not limit the system to systems without an exhaust fan. Needless to say.

Further, although a planar plate is used as the shape of the air path regulating plate, it is also effective to use a shape that does not inhibit the flow of air toward the photosensitive drum, for example, a curved plate curved into a streamlined shape.

[Effect of the invention 1 As described above, by carrying out the present invention and installing a convection fan in the image forming apparatus and operating it while the photoreceptor is stopped, ozone around the photoreceptor can be diffused, and the ozone generated by the action of ozone can be diffused. This prevents nitrogen oxides from being adsorbed onto the photoreceptor, thereby preventing image blurring that tends to occur in high-humidity environments and providing high-quality images.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an image forming apparatus embodying the present invention, FIG. 2 is a front view of a convection fan used in Embodiment 1, FIG. 3 is a longitudinal sectional view of another embodiment, and FIG. A time chart in the first embodiment, and FIG. 5 is a time chart in the second embodiment. 1...Photosensitive drum 2...-wide charger 13°13'
・・Convection fan 18・・′ Air path regulation plate. Go to EP-

Claims (1)

[Claims] 1. In an image forming apparatus that has a photoconductive photoreceptor and is provided with a member including a charger for performing an electrophotographic process along the photoreceptor, 1. An image forming apparatus comprising: an air convection device for blowing air toward the photoreceptor; and a control device for operating the air convection device when a drive device for driving the photoreceptor is stopped to blow air toward the photoreceptor. 2. The image forming apparatus according to claim 1, wherein the air convection device also serves as an exhaust device for sucking air from the photoreceptor side during the image forming process.