JPH0363673A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the local irregularities in an image by varying an air blowing quantity in accordance with the circumferential speed of a photosensitive drum. CONSTITUTION:When the circumferential speed of the photosensitive drum 2 is switched stepwise to a low speed, the revolving speed of a fan 8 is made low in accordance with the circumferential speed of the drum 2 and an air quantity to a potential sensor 5 gets small, so that air from an aperature part 6a does not strongly blow to the drum 2 and the local stripe, etc., of the image is not formed. As the circumferential speed of the drum 2 increased, the revolving speed of the air blower 8 is adjusted to a high speed. Since the air quantity to the sensor 5 is increased even when the irregularity of ambient air becomes large, dust is stopped from entering from the aperture part 6a and the contamination of the sensor 5 is prevented. Thus, the local irregularities in the image and the contamination of the sensor are prevented by making the internal pressure and the external pressure of the sensor 5 equal or making the internal pressure higher than the external pressure in accordance with the circumferential speed of the drum 2.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention provides an image forming apparatus in which the circumferential speed of a photoreceptor drum can be freely switched, which does not cause local image disturbance and can prevent sensor contamination. Regarding.

[Prior art]

FIG. 3 is a schematic vertical cross-sectional view of an image forming apparatus such as a copying machine, which is the background of the present invention.

The photosensitive drum 52 of the image forming apparatus 51 is rotationally driven by a motor (not shown), and the circumferential speed of the photosensitive drum 52 can be arbitrarily switched.

A cleaning device 5 is provided around the photoreceptor drum 52.
3. Charger 54. SELFOC lens array 55 and I
The J image devices 56 are arranged in this order.

An image forming apparatus is provided between the charger 54 and the SELFOC lens array 55, and is provided with a potential sensor 57 for detecting the surface charge of the photoreceptor drum 52 given by the charger 54.

Further, in the vicinity of the developing device 56, there is an image forming device equipped with a reflective optical sensor 58 that detects the density of the attached toner.

The SELFOC lens array 55 is for forming an image of the light reflected by the document 6o out of the light emitted from the light R59 on the surface of the photoreceptor drum 52.

The potential sensor 57 is configured to have an opening 611 facing the photoreceptor drum 52, as shown in FIG.

Then, the scattered toner, paper powder, debris, etc. are
In order to prevent the potential sensor 57 from entering from the contact point h and contaminating the potential sensor 57, a certain amount of air is sent into the potential sensor 57 via the blower vibro 2, and the air is blown out from the opening 61m. The pressure inside the tank 57 is made higher than the external pressure.

The distance between the potential sensor 57 and the photosensitive drum 52 cannot be increased due to its sensitivity.

[Problem to be solved by the invention]

On the other hand, if the amount of air sent to the potential sensor 57 is too large, the air blown out from the opening 6h will locally disrupt the flow of air, causing uneven charging, temperature, and dirt, and as a result, the formed II image will be affected. This causes "streaks" etc.

On the other hand, if the air volume is too small, it will not be possible to prevent the above-mentioned dust from entering, and the potential sensor 57 will become dirty.

In the conventional image forming apparatus 51, the amount of air blown is set constant. For this reason, when the circumferential speed of the photoreceptor drum 52 is switched and changed due to a change in magnification, etc., the effect of changing the flow of air around the photoreceptor drum 52 is dealt with. I couldn't do that.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming apparatus that does not cause local image disturbances even when the peripheral speed of a photoreceptor drum is arbitrarily changed and can prevent sensor contamination. It is.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a sensor which can freely switch the circumferential speed of a photoreceptor drum, has an opening facing the photoreceptor drum, and detects the state of the surface of the photoreceptor. In an image forming apparatus that blows air into the photoreceptor drum, the amount of air blown is changed according to the circumferential speed of the photoreceptor drum so that the internal pressure of the sensor and the external pressure of the sensor are equal or the internal pressure of the sensor is higher than the external pressure of the sensor. The image forming apparatus is configured as an image forming apparatus characterized by the following.

[Effect]

In this image forming apparatus, the amount of air blown into the sensor is changed according to the circumferential speed of the photoreceptor drum, and the internal pressure of the sensor is changed.

For example, when the circumferential speed of the photoreceptor drum is gradually switched to a low speed, the amount of air blown is also reduced accordingly.

Therefore, the air blown out from the opening of the sensor does not hit the photosensitive drum too strongly, so that local image disturbances do not occur.

Further, when the circumferential speed of the photosensitive drum is changed stepwise to the original normal speed or high speed, the amount of air blown is adjusted accordingly so as to be normal or large.

Therefore, even if the air around the photoreceptor drum becomes more turbulent due to an increase in the circumferential speed of the photoreceptor drum, the amount of air sent into the sensor increases, so dust does not enter through the opening, and the This prevents the sensor from becoming dirty.

〔Example〕

Hereinafter, embodiments embodying the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.

In addition, the following example is an example embodying the present invention,
It is not intended to limit the technical scope of the present invention.

FIG. 1 is a block diagram of the amount of air *m sent into the potential sensor of an image forming apparatus according to an embodiment of the present invention.

In FIG. 1, a photosensitive drum 2 of this image forming apparatus 1 is shown.
is rotationally driven by a motor 3, and the circumferential speed of the photosensitive drum 2 is switched as necessary by a control section 4 comprising a microcomputer CPυ or the like.

A potential sensor 5 for detecting the surface charge of the photosensitive drum 2 is provided near the photosensitive drum 2 .

The potential sensor 5 has an opening 6 facing the photoreceptor drum 2.
．． It is configured with

Then, the scattered toner, paper powder, dust, etc. are removed from the opening 6.
．． In order to prevent air from entering the potential sensor 5 from contaminating the potential sensor 5, air is sent into the potential sensor 5 via a blower vibrator 7 to make the pressure inside the potential sensor 5 equal to or higher than the external pressure. There is.

A blower 8 that sends air to the blower vibrator 7 is connected to a control unit 4 via a drive transistor T and a buffer circuit B.
It is connected to the.

The rotational speed of the blower 8 is changed according to the circumferential speed of the photoreceptor drum 2, and the amount of air sent to the blower vibrator 7 is changed.

For example, when the circumferential speed of the photoreceptor drum 2 is switched to a low speed in stages, the rotational speed of the blower 8 is also switched to a low speed accordingly.

Therefore, the amount of air sent to the potential sensor 5 decreases and the opening 6
Since the air blown out from the photoreceptor drum 2 does not hit the photoreceptor drum 2 too strongly, no local image streaks or the like are formed on the photoreceptor drum 2.

Further, when the circumferential speed of the photosensitive drum 2 is changed stepwise to the original normal or high speed, the rotation speed of the blower 8 is also adjusted to the normal or high speed.

Therefore, even if the turbulence of the air around the photoreceptor drum 2 increases due to an increase in the peripheral speed of the photoreceptor drum 2, the amount of air sent to the potential sensor 5 increases, thereby preventing dust from entering through the opening 61. I can do it.

Therefore, the potential sensor 5 is prevented from becoming dirty.

In this embodiment, the case of preventing contamination of the potential sensor 5 has been described, but the amount of air blown to prevent contamination of other sensors, such as the reflective optical sensor 58 shown in FIG. 3, can be similarly controlled. You may also do so.

〔Effect of the invention〕

According to the present invention, the circumferential speed of the photoreceptor drum can be freely changed, and the sensor has an opening facing the photoreceptor drum and detects the state of the surface of the photoreceptor, and air is sent into the sensor. In the image forming apparatus, the air blowing amount is changed according to the circumferential speed of the photoreceptor drum so that the internal pressure of the sensor and the external pressure of the sensor are equal to each other or the internal pressure of the sensor is higher than the external pressure of the sensor. Equipment is provided.

Therefore, even if the circumferential speed of the photoreceptor drum is arbitrarily changed, local image disturbance does not occur, and the sensor is also prevented from becoming dirty.

[Brief explanation of drawings]

FIG. 1 is a block diagram of controlling the amount of air sent into the potential sensor of an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view showing an example of the potential sensor, and FIG. 3 is a back volume control of the present invention. Schematic diagram of the bound cross section of the image forming apparatus [code clarification]

Claims (1)

[Scope of Claims] 1. The peripheral speed of the photoreceptor drum can be freely switched, and the sensor has an opening facing the photoreceptor drum and detects the state of the surface of the photoreceptor; In an image forming apparatus that blows air, the amount of air blown is changed according to the circumferential speed of the photoreceptor drum so that the internal pressure of the sensor and the external pressure of the sensor are equal or the internal pressure of the sensor is higher than the external pressure of the sensor. Features of the image forming device.