JPH0741020Y2 - Static eliminator for image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a static eliminator for an image forming apparatus such as a copying machine or a laser printer.

<Prior Art> A copying machine will be described below as an example of the image forming apparatus.

The static eliminator of a copying machine removes electric charges on the surface of the photoconductor drum, and is generally located between the cleaning device and the charging device. It is composed of a proximity conductor having a function of a plate and a function of stabilizing the discharge of the cold cathode discharge tube. By turning on the cold cathode discharge tube, the charge on the surface of the photosensitive drum is removed in advance before the main charging.

However, since the light quantity of the cold cathode discharge tube is almost proportional to the temperature of the tube wall of the cold cathode discharge tube, the light emitting quantity changes depending on the ambient temperature of the place where the copying machine is installed.

Therefore, the light quantity of the cold cathode discharge tube does not depend on the ambient temperature,
In addition, as a mechanism that provides a constant amount of light even when the ambient temperature is low, a technique (described in Japanese Patent Laid-Open No. 60-230618) for supplying heat from the heat roller of the fixing device to the static eliminator by a heat pipe or fan, a proximity conductor heater, etc. Conventionally, a technique of heating with is known.

<Problems to be solved by the invention> However, when the heat pipe as described above is used, the number of parts increases and the price increases accordingly. Further, in the method of sending hot air with a fan, the hot air hits the photosensitive drum, and the sensitivity of the photosensitive drum partially changes. Further, there is a problem that it is difficult to control the temperature by the method of heating the adjacent conductor with the heater.

The present invention has been devised in view of the above circumstances, and an object thereof is to provide a static eliminator for an image forming apparatus capable of quickly stabilizing the light quantity of a cold cathode discharge tube with a simple mechanism.

<Means for Solving Problems> The static eliminator of the image forming apparatus according to the present invention includes a main cold cathode discharge tube and a sub cold cathode discharge tube having different light intensities. A static eliminator for an image forming apparatus in which only the sub-cold-cathode discharge tube is turned off when the total amount of light from the cold-cathode discharge tube exceeds a predetermined value. The discharge tube has a light quantity that is stable and has a light quantity that exceeds the minimum quantity of light necessary for neutralizing the photoconductor drum, and the sub cold cathode discharge tube is set to be smaller than the main cold cathode discharge tube.

<Operation> When the main cold cathode discharge tube and the sub cold cathode discharge tube are lit at the same time and a predetermined time has passed, or when the total amount of light of the main and sub cold cathode discharge tubes exceeds a predetermined value, only the sub cold cathode discharge tube Is turned off.

<Embodiment> An embodiment according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view around a photosensitive drum of a copying machine adopting a charge eliminating device of an image forming apparatus according to the present invention, and FIG. 2 shows changes in light quantity of a main cold cathode discharge tube and a sub cold cathode discharge tube. FIG. 3 is a block diagram showing the electrical construction of the static eliminator of the image forming apparatus according to the present invention.

First, the structure and operation of a general copying machine will be described, and then the static eliminator according to the present invention will be described.

A document placed on a document table (not shown) is illuminated by an exposure lamp (not shown), and its reflected light is reflected by a reflecting mirror,
An optical system (not shown) composed of a lens or the like irradiates the surface of the photosensitive drum 80 uniformly charged by the charging device 20 as reflected light L. The reflected light L forms an electrostatic latent image corresponding to the original on the surface of the photosensitive drum 80, and the electrostatic latent image is converted into a toner image by the developing device 40. A toner image is transferred by the transfer device 50 to the copy paper that has been transferred to the lower part of the photosensitive drum 80 through the transfer system 90, and the copy paper is separated by the peeling device 60 and conveyed to a fixing device (not shown). , Copying is completed.

After the toner image is transferred onto the copy paper, the cleaning device 70 removes the residual toner from the photoconductor drum 80, and the charge removing device 10 removes the residual charge.

Reference numeral 30 is a blank cut lamp for setting a charging area corresponding to the width of the copy paper.

The static eliminator 10 of the image forming apparatus according to the present invention has a main cold cathode discharge tube 11 and a sub cold cathode discharge tube 12, and is installed near the photosensitive drum 80.

The main cold-cathode discharge tube 11 and the sub-cold-cathode discharge tube 12 are static elimination lamps, and when the quantity of light of the main cold-cathode discharge tube 11 becomes stable, the minimum quantity of light necessary for static elimination of the photosensitive drum 80 is exceeded. Has a light amount of
The light quantity of 12 is set to a fraction of the light quantity of the main cold cathode discharge tube 11. However, the wavelength components of both cold cathode discharge tubes 11 and 12 are set to be equal.

Further, the main cold cathode discharge tube 11 and the sub cold cathode discharge tube
12 is a proximity conductor 13 formed by bending a metal plate such as aluminum
Is covered with. This proximity conductor 13 has two cold cathode discharge tubes.
It makes the lighting of 11 and 12 smooth.

In the static eliminator 10 having the above structure, the main cold cathode discharge tube 11 and the sub cold cathode discharge tube 12 are turned on at the same time when a copy command is issued. After that, the sub cold cathode discharge tube 12 is turned off after a predetermined time has elapsed. On the other hand, the main cold cathode discharge tube 11 keeps lighting during copying.

FIG. 2 (a) shows the change of the light quantity with time of the main cold cathode discharge tube 11, that is, the change of the light quantity of the cold cathode discharge tube of the conventional static eliminator with time, and FIG. 2 (b) shows the sub cold cathode discharge tube 12 2 (c) is a graph showing the change in the amount of light of the main cold cathode discharge tube 11 and the sub cold cathode discharge tube 12 with time. The horizontal broken lines shown in (a) and (b) indicate the minimum amount of light necessary to eliminate the charge on the surface of the photosensitive drum 80.

When copying is started, the main cold cathode discharge tube 11 and the sub cold cathode discharge tube 12 are turned on at the same time. Both cold cathode discharge tubes 11 and 12 require a certain amount of time for the light quantity to stabilize,
At time t ₁ when the sum of the light amounts of the cold cathode discharge tubes 11 and 12 exceeds the above-mentioned minimum, image formation becomes possible (see FIG. 2 (c)), and then the sub cold cathode discharge tube 12 becomes It is turned off. Therefore, it is possible to shorten the time until a good image can be formed. That is, it takes time t ₂ before the image can be formed in the conventional case (see FIG. 2 (a)), but in the case of the present invention, the image can be formed in a shorter time than that. become.

The means for turning off the sub cold cathode discharge tube 12 will be described below. 3
One embodiment will be described.

First Embodiment A static eliminator 10 of an image forming apparatus according to the first embodiment has a light amount detection sensor 14, and a main cold cathode discharge tube 11 and a sub cold cathode discharge tube 12 are simultaneously operated by a copy start command. When the light is turned on and the total light quantity of the two cold cathode discharge tubes exceeds a predetermined value, the gate switch 17 is turned off by the signal from the light quantity detection sensor 14 and only the sub cold cathode discharge tube 12 is turned off. (See FIG. 3 (a)).

Second Embodiment A charge eliminating device 10 of an image forming apparatus according to a second embodiment has a temperature sensor 15 for setting the lighting time of the sub cold cathode discharge tube 12. That is, the ambient temperature of the place where the copying machine is installed is detected by the temperature sensor 15, the lighting time of the sub cold cathode discharge tube 12 corresponding to the detection result is set, and the two cold cathode discharge tubes 11 and 12 are set. The sub-cold-cathode discharge tubes 12 are turned on at the same time and after the set time has passed, the sub-cold-cathode discharge tubes 12 are turned off (see FIG. 3 (b)).

Third Embodiment In the static eliminator 10 of the image forming apparatus according to the third embodiment, the lighting time of the sub cold cathode discharge tube 12 is fixedly set by the timer 16, and when this set time elapses, the sub cold cathode. The discharge tube 12 is configured to be turned off (see FIG. 3 (c)).

Although the image forming apparatus has been described as a copying machine in the above embodiment, the charge eliminating apparatus of the image forming apparatus according to the present invention is not limited to this, and can be applied to other image forming apparatuses such as a laser printer. It is a thing.

<Effect of the Invention> According to the static eliminator of the image forming apparatus according to the present invention, two cold cathode discharge tubes, a main cold cathode discharge tube and a sub cold cathode discharge tube, are provided, and after a predetermined time elapses or the main and sub cold cathodes. Since the sub-cold-cathode discharge tube is turned off when the total amount of light of the discharge tube exceeds a predetermined value, the time until a good image can be formed does not depend on the ambient temperature. That is, there is an effect that it is possible to always form an image in a fixed time.

[Brief description of drawings]

FIG. 1 is a schematic view around a photosensitive drum of a copying machine adopting a charge eliminating device of an image forming apparatus according to the present invention, and FIG. 2 shows changes in light quantity of a main cold cathode discharge tube and a sub cold cathode discharge tube. FIG. 3 is a block diagram showing the electrical construction of the static eliminator of the image forming apparatus according to the present invention. 11 …… Main cold cathode discharge tube, 12 …… Sub cold cathode discharge tube.

Claims (1)

[Scope of utility model registration request] 1. A sub-cold cathode discharge tube comprising a main cold cathode discharge tube and a sub cold cathode discharge tube having different light intensities, and when a total amount of light in the main and sub cold cathode discharge tubes exceeds a predetermined value, the sub cold cathode discharge tube is provided. In the static eliminator of the image forming apparatus in which only the cathode discharge tube is turned off, the wavelength components of the main and sub cold cathode discharge tubes are equal, and the main cold cathode discharge tube is necessary for static elimination of the photoconductor drum in a stable light quantity. A static eliminator for an image forming apparatus, wherein the sub cold cathode discharge tube is set to have a light quantity exceeding the minimum light quantity, and the sub cold cathode discharge tube is set to have a smaller light quantity than the main cold cathode discharge tube.