JPS5814877A - Electrostatic copier - Google Patents

Abstract

PURPOSE:To elevate an image quality, and also to make a titled copier small- sized, by placing a light source for emitting both 2 kinds of light pectrums, at least in a front position of a main charger, in a state that a photosensitive body can be irradiated. CONSTITUTION:As for a light source 13 placed between a main charger 3 and a cleaning device 12, for instance, a 2 color light emission diode of red and green is used, and when copying of the first time is executed, red light is given uniformly by red light emission of the light source 13 before a photosensitive body 1 is charged by the main charger 3. In order to charge the photosensitive body 1 uniformly, it is necessary to set the potential of the photosensitive body before charging, to zero, therefore, green light is irradiated to the photosensitive body 1 simultaneously from the light source 13. In this way, for instance, as to the same original, a difference of the potential of a latent image between the first time and the next time and thereafter is reduced, and in case of copying of the next time and thereafter, the quantity of red light emission is controlled so that the red light is weakened or is not emitted.

Description

[Detailed description of the invention] The present invention relates to electrostatic copying machines.

Conventionally, as is well known, in an electrostatic copying machine, when carrying out an electrophotographic process, the photoreceptor is first uniformly charged and then partially or completely discharged by imagewise exposure to visible light. An electrostatic latent image is created on a photoreceptor, and this latent image is developed with a visible electrostatic marking material such as toner to obtain a visible copy image.

In order to obtain high-quality copies using such a process, the stability of the photoconductive properties of the photoreceptor and its repeatability are important factors.

It is known that many factors are related to the stability of photoreceptors. A particularly important factor is the variation in photosensitivity properties.

This variation in photosensitive characteristics is closely related to the fatigue of the photoreceptor. For example, between the first copying after a pause and the next copying, when other bias conditions are held constant, the so-called charge change, There is a significant difference in the direction of the

This difference naturally affects the image quality of the copies. For example, in the first copy, a high-density image with a dirty background is obtained, and in the next copy, the photoreceptor is fatigued due to exposure during the first copy, resulting in an overall low-density image. Such a difference in image quality tends to be particularly large between the first and next images.

Focusing on this phenomenon, in order to eliminate the difference in image quality between the first copy and subsequent copies, attempts have been made to average the image quality by making the photoreceptor fatigued during the first copy. and achieved results.

A specific example of the method described in -J2 is, for example, irradiating a SeAS-based photoreceptor with a red light spectrum.

On the other hand, in an electrostatic copying machine, after completing one electrophotographic process and before starting the next electrophotographic process, the potential of the photoreceptor can be effectively attenuated to remove residual charges on the photoreceptor. Irradiation with a spectrum of light is practiced.

A specific example of the above method is to irradiate the photoreceptor with a green light spectrum.

By the way, in conventional copying machines, for example,
- As stated in Publication No. 148444, the above 2
The light sources that emit each of the different light spectra, that is, the briftchy lamp and the static elimination lamp, are arranged individually around the photoreceptor drum, which takes up space and is an obstacle to downsizing the copying machine. It has become.

The present invention has been made in view of these circumstances, and it is an object of the present invention to provide an electrostatic copying machine that can be made smaller while improving image quality. The present invention will be explained in detail below.

The electrostatic copying machine according to the present invention has a light source that emits both a light spectrum that can fatigue the photoreceptor and a light spectrum that can effectively attenuate the photoreceptor potential, at least at a position in front of the main charger. , is characterized in that it is arranged in a position that allows it to irradiate the photoreceptor.

To explain an embodiment, the figure shows an example of an electrostatic copying machine according to the present invention.

Since the basic structure of the copying machine is the same as that of a commonly known electrostatic copying machine, only the names of the parts will be mentioned.

Reference numeral 1 indicates a photoreceptor drum, and when a high arsenic selenium alloy photoreceptor is used, for example, it is particularly susceptible to the influence of past lighting history and time, so the image quality due to the light source installed according to the present invention is The adjustment effect is noticeable.

4- An indicator arrow 2 indicates the rotation direction of the photosensitive drum 10.

Below, the members or process units arranged around the drum I in the order of its rotational direction will be listed.

Reference numeral 3 is a main charger for charging the photoreceptor, reference numeral 4 is an unnecessary part static elimination lamp that removes electricity from unnecessary parts according to the size of the transfer paper, reference numeral 5 is an exposure section, reference numeral 6 is a developing drum that supplies toner, reference numeral 7 is is a guide board for supplying transfer paper, code 8
9 is a transfer charger, 9 is a separation charger, 10 is a conveyor belt that conveys the transfer paper after transfer, and 11 is a transfer belt.
Reference numeral 12 indicates a static elimination charger, and 12 indicates a cleaning device.

Incidentally, among the above members, the light source 13 according to the present invention is disposed between the main charger 3 and the cleaning device 12.

As this light source 13, for example, a red/green two-color light emitting diode is used.

In this copying machine, when copying for the first time, the light source 13 is turned on before the photoreceptor is charged by the main charger 3.
Red light is uniformly given by the red light emitted by. For subsequent copying, the amount of light emitted is weakened or controlled so that no light is emitted. The reason for this is that, for example, the purpose of red light irradiation is to reduce the difference in latent image potential between the first and subsequent copies of the same document, so if the photoreceptor can be especially fatigued during the first time, the image quality can be adjusted. This is because it is possible.

Further, as described above, as a condition for uniformly charging the photoreceptor, it is necessary to set the photoreceptor's potential to zero before charging, so that the light source 13 simultaneously irradiates the photoreceptor with green light. This green light irradiation is always performed for each copy.

The above-mentioned emission control of the red light and green light is performed according to a control signal from a control section equipped with the copying machine.

It should be noted here that the red light must be emitted when copying after the photoreceptor has recovered from fatigue, and the red light must be emitted when copying is performed after the photoreceptor has recovered from fatigue. It is controlled so that the light is emitted at a time corresponding to the first copying when performing copying. For example, when the main switch is turned on, and even after the main switch is turned on, if it is not in use, a timer or the like is used to measure the time, and the light is emitted when copying is performed after a certain period of time has elapsed.

In the present invention, since the light source j3 is used which emits light at a location where two types of light spectra can be regarded as the same, it is possible to create an electrostatic copying machine that is more compact than in the past, which is advantageous.

[Brief explanation of drawings]

The figure is a configuration diagram of main parts of an electrostatic copying machine according to the present invention. 3...Main charger, J3...Light source. 7-

Claims (1)

[Claims] In an electrostatographic copier having a photoreceptor that exhibits a varying dark decay rate due to fatigue between the first copy and subsequent copies in an electrophotographic process, the light spectrum that can fatigue the photoreceptor and the photosensitive An electrostatic copying machine characterized in that a light source that emits a light spectrum that can effectively attenuate body potential is arranged at least in front of a main charger in a position that allows it to irradiate a photoreceptor.