JPS59185376A - Electrophotographic recorder - Google Patents

Abstract

PURPOSE:To reduce the deterioration of picture quality by driving a photosensitive drum at a higher speed than that of the execution of an electrophotographic process by the 2nd charge latent image formation means in the execution of the electrophotographic process by the 1st charge latent image formation means. CONSTITUTION:The photosensitive drum 4, the 1st electrostatic charger 5, a convergent optical transmission body array lens 8, the 2nd electrostatic charger 9, a laser beam scanner unit 10, and a developer 12 are arranged as shown in the figure. If it is defined that the mutual intervals of these arrangement are theta1, theta2, phi1, phi2 and the peripheral speed of the photosensitive drum 4 is V1 in case of the copying process and V2 in case of the print process, dark attenuation times in both processes are made equal when theta2/theta1 V2/V1 phi2/phi1. Although the dark attenuation of a dark part (a part adhering toner) exerts large influence upon the picture quality especially, the extent of the dark attenuation can be made equal by setting up theta2/theta1 V2/V1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an electrophotographic recording apparatus that combines a subject using electrophotographic technology and a laser beam printer.

[Back shell of invention]

In electrophotographic technology, a uniformly charged photosensitive drum is exposed to light to form a charge latent image, and this charge latent image is developed with a developing device to form a toner image. Alternatively, a copying machine can be configured by using a transmitted light image, and a laser beam printer can be configured by scanning a laser beam whose intensity is modulated by an image signal.

However, such multifunction copiers and laser beam printers have different exposure characteristics because the wavelength and light energy of the light generated from each light beam are different, so it is difficult to obtain a high-quality toner image in either case. There are also problems in that the arrangement of component parts is difficult in order to miniaturize the device. In other words, the photosensitive drum of a copying machine is 400 to 6
It is set to have a high sensitivity tray in the wavelength range of 00 nm, but when used as a semi-integrated laser beam printer, the wavelength is in the long wavelength range close to 800 nm, so the sensitivity range of the photosensitive drum is must be sensitized to this region. However, the temperature dependence of the electrical properties of the sensitized photosensitive drum is strong (the dark decay of the surface potential increases, especially at high temperatures. This phenomenon becomes more pronounced as the number of repetitions of the electrophotographic process increases. .

Figure 1 shows the dark decay characteristics of the surface potential after the surface of a selenium photosensitive drum sensitized by Te doping (with a sensitivity of 0.03 mJ 7 m2/V) is charged with a charger to which a constant voltage is applied. . For example, the surface potential after 1 second is 2 between the 1st cycle and the 500th cycle of the electrophotographic process.
At 0°C there is a difference of about 30V, whereas at 40°C V
For C, the difference is about 150 square meters.

For this reason, if the child photographic process is repeated under high temperature conditions, the potential of one station of the charge layer will gradually decrease and the image quality will deteriorate.

Therefore, in order to completely prevent or reduce image quality deterioration due to such dark decay, it is necessary to shorten the dark decay time. To do this, the drive speed of the photosensitive drum should be increased, or the distance from the charging position to the current position should be shortened. distance must be shortened. However, in the former case, the exposure time is also shortened, so
If the sensitivity of the photosensitive drum is constant, it is necessary to increase the exposure energy, and in particular, in the case of a semiconductor laser oscillator, there is a drawback that the lifetime becomes shorter as the output increases.

If the exposure energy is kept constant, it is necessary to further sensitize the photosensitive drum, but in this case, the dark decay time is further promoted, and the effect of preventing the charge layer one-station potential drop is small. In the latter case (reduced distance), there is a drawback that the structures of the copy exposure optical system and the laser beam exposure optical system become complicated. In particular, in order to downsize the device, when a convergent light transmitter array lens is used in the temporary light optical system, the direction of movement of the copied document and the angle of projection of light onto the photosensitive drum are restricted to 90 degrees. Therefore, due to the necessity of arranging the components for this purpose, the device became complicated, and there was a limit to the improvement by shortening the distance.

[Purpose of the invention]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a composite type electrophotographic recording apparatus that completely prevents image quality deterioration due to dark attenuation, which is highly temperature dependent, and in which the arrangement of component parts is simple.

[Summary of the invention]

In order to achieve this object, the present invention includes a photosensitive drum, a driving means for driving the photosensitive drum, first charge latent image forming means arranged sequentially in the driving direction facing the surface of the photosensitive drum, and A first charge layer is formed by the first charge latent image forming means, and a first charge layer is developed by the first charge latent image forming means to form a first toner image. A photographic process and a second electrophotographic process in which a second latent charge image is formed by a second latent charge image forming means and developed to form a second toner image can be selectively carried out. In the electrophotographic recording apparatus, the first charged latent image forming means includes a first charging means and a first optical system for exposing the entire surface of a charged photosensitive drum with a light image from a copy original; The second charged latent image forming means is provided with a second charging means and a second optical system that scans and exposes the surface of the charged photosensitive drum with a spot of a laser beam whose intensity is modulated by an image signal; Furthermore, the driving means is provided with a speed switching means for driving the photosensitive drum at a higher speed when performing the first electrophotographic process than when performing the 20th electrophotographic process, and the present invention provides a document handling method that can increase exposure energy. By arranging the first charge latent image forming means farther from the developing means, it is easier to arrange the second charge #i image forming means closer to the image forming means by means of a laser beam with lower exposure energy. In addition, by increasing the photosensitive drum drive speed when capturing the original by utilizing the amount of exposure energy, an increase in dark decay time is prevented or reduced, and a potential drop in the charge latent image is prevented or reduced. It is.

[Embodiments of the invention]

The following description will be made based on the embodiment shown in FIG.

In FIG. 2, a main body base 1 serves as a basis for supporting components to be described later, and main body covers 2 and 3 constitute a dark box for storing components for electrophotography.

The photoconductive photosensitive drum 4 is rotatably supported, and is rotationally driven in the direction of arrow (A) at a predetermined speed by a driving means such as a motor (not shown). Photosensitive drum 4 of first charger 5
The exposure lamp 6 illuminates a copy document 72 placed on a document table 7 made of a transparent flat plate.

The document table 7 is horizontally driven in the direction of arrow (b) in synchronization with the surface speed of the photosensitive drum 4, and the reflected light image from the copy document 7a is transmitted to the surface of the photosensitive drum 4 via the convergent light transmitting array lens 8. It is projected and exposed. The second charger 9 charges the surface of the photosensitive drum 4 uniformly. The laser beam scanner unit 10 is equipped with a semiconductor laser oscillator and a deflection mirror, and irradiates the surface of the photosensitive drum 4 with a laser beam 11 that is intensity-modulated by an image signal and deflected and scanned.
= Shine. The developing device 12 develops the charge a image formed on the surface of the photosensitive drum by the charging and exposure to form a toner image. The popper 13 stores toner for replenishing the developing device 12. The transfer device 14 applies a transfer bias charge to the back side of the recording paper in order to transfer the toner image formed on the surface of the photosensitive drum 4 onto the recording paper. This is to completely eliminate the transfer bias charge after the transfer is completed. A drum cleaner 16 removes toner remaining on the surface of the photosensitive drum after the toner image is transferred, and an erase lamp 17 performs uniform overall exposure to eliminate charges remaining on the surface of the photosensitive drum. The paper cassette 18 collects the recording paper as described above, and the recording paper taken out from the paper cassette 18 by the pickup roller 19 is conveyed by paper transport rollers driven at the same peripheral speed as the photosensitive drum 4 described above. Ru. The recording paper is brought into contact with the outer periphery of the photosensitive drum 4 while being conveyed, and in this state, a transfer bias charge is applied by the transfer device 14 to transfer the toner image. The fixing unit 5 thermally fixes the toner-1 dust transferred to the recording paper onto the recording paper by a fixing roller 25a, and discharges the recording paper with the toner image fixed to the rollers 2!5.
b is discharged onto the tray 26. The cooling fan 27 circulates the air inside the mounting to suppress the temperature rise. Each control unit has an electronic control circuit, a photosensitive drum drive speed, a charger and exposure optical system to operate, a recording paper transport speed, depending on whether the device is operated as a copying machine or a laser beam printer. control other
Generates an image signal.

In the above configuration, when the apparatus is used as a copying machine, the first charger 5 is operated to uniformly charge the surface of the photosensitive drum 40. The exposure lamp 6 is turned on and the document table 7
is driven. As a result, the surface of the photosensitive drum is exposed to the reflected light image reflected from the copy document 7a, and a charge latent image is formed.

The latent charge image is developed into a toner image by the developing device 12, and this toner image is transferred to the recording paper and then fixed. Hereinafter, this will be referred to as the tM copying process.

When the device is used as a full laser beam printer,
The second charger 9 is activated to uniformly charge the surface of the photosensitive drum 4. A laser beam scanner unit 10 scans and illuminates the surface of the photosensitive drum with a laser beam 11 modulated by an image signal to form dust along the bag. The latent charge image is developed into a toner image by a developing device 12, and this toner image is transferred to recording paper and then fixed. Hereinafter, this will be referred to as the print process.

Next, a technique for equalizing and reducing the amount of dark decay in the above-described copying process and printing process will be described. FIG. 3 shows the photosensitive drum 4, the first charger 5, the convergent light transmitting array lens 8, the second charger 9, and the laser beam scanner unit 10 in the electrophotographic recording apparatus described above. This shows the arrangement relationship of the developing device 12. The mutual spacing between these arrangements is θ7.
θ7. When ψ1゜ψ2 and the driving speed (peripheral speed) of the photosensitive drum 4 is vl in the copying process and ■2 in the printing process, θ, /θ, medium v! /v and key ψ2/ψ1, the dark decay times in both processes become equal. In particular, the dark attenuation in the dark areas (the areas where toner adheres) has a large effect on the image quality, and this is caused by v, /v in θ, /θ1.
.

By setting, the dark attenuation leaves can be made equal. In addition, the second charger 9 and the laser beam scanner unit 11 for carrying out the printing process with small exposure energy are the first charger 5je for the copying process, and the convergent light transmitter array for temporary copying without light. It can be placed close to the developing device 12 (by reducing θ2) without being affected by the placement of the lens 8. Therefore, the moving speed v2 of the photosensitive drum 40518 is slow (
However, the dark decay time (=02÷vt) will never be long. On the other hand, since the copy document table 7 is horizontal, the convergent light transmitter array lens 8 must be swung vertically. 1, the distance θ between the charger 5 and the developer 12 becomes quite large. However, since the exposure energy from the exposure lamp 6 is quite large, the driving speed y of the photosensitive drum 4 can be increased when carrying out the copying process. Therefore, the dark decay time (=θ, ÷v) during the copying process does not become long.Of course, depending on the driving speed of the photosensitive drum 4, the charging capacity of the charger, the current (the visual capacity of household appliances), It is necessary to set all the settings, such as the recording paper conveyance speed, the charging capacity of the transfer device, the static eliminating capacity of the static eliminator, the exposure capacity of the eraser, and the fixing capacity of the fixing unit.If it is necessary to change the capacity, the change can be made using the control unit. 28 TeIII ?J
'1- le.

Normally, the driving speed V of the photosensitive drum 4 is 100 mm in an electrophotographic process using a semiconductor laser oscillator of several mW.
/see (v, equivalent) or less, and is 120 / 300 mm / sec (v, equivalent) in the original copying process. Therefore, θ2/θ1kiv, /v.

By doing so, it is possible to provide a margin for arranging the component parts, and the arrangement of the parts becomes easy.

〔Effect of the invention〕

As described above, according to the present invention, the first charge latent image formation includes the first charging means and the first optical system that exposes the surface of the charged photosensitive drum with a light image from the copy document. A second charging means and a charged photosensitive drum surface k i+! ]l(' A second charge latent image forming means equipped with a second optical system for scanning exposure with a spot of a laser beam whose intensity is modulated by an IJ signal is disposed at a position close to the developing means, m; * Since the photosensitive drum is driven at a higher speed when performing the electrophotographic process using the latent image forming means than when performing the electrophotographic process using the second image forming means, image quality deterioration due to dark decay is reduced. (Moreover, it is possible to provide a composite type electrophotographic recording device in which the arrangement of component parts is simple.

[Brief explanation of the drawing]

FIG. 1 is a dark attenuation characteristic diagram of a photosensitive drum, FIG. 2 is a vertical sectional side view of an electrophotographic recording apparatus showing an embodiment of the present invention, and FIG. 3 is a layout diagram of main components. 4...Photosensitive drum, 5...First charger, 6...Exposure lamp, 7...Original table, 8... Convergent light transmitter array lens, 9...
...Second charger, 10...Laser beam scanner unit, 12...Current e-device, song...
···control unit. Patent attorney Takeshi Kenjibe Yodo 4 @ - Miyako θnu

Claims (1)

[Scope of Claims] 1. A photosensitive drum, a driving means for driving the photosensitive drum, first charge latent image forming means facing the surface of the photosensitive drum and arranged sequentially in the driving direction, and a second photosensitive drum. A first electrophotographic device comprising a latent charge image forming means and a developing means, and forming a first latent charge image by the first latent charge image forming means and developing the same to form a first toner block. and a second electrophotographic process in which a second charge latent image is entirely formed by a second charge image forming means and developed to form a second toner image. In the electrophotographic recording apparatus, the first charge latent 1 original forming means includes a first
and a first optical system that exposes the surface of the charged photosensitive drum with optical recording from a copy document;
The charge latent image forming means includes a second charging means and a second optical system that scans and exposes the surface of the charged photosensitive drum with a laser beam spot whose intensity is modulated by an image signal,
An electrophotographic recording apparatus characterized in that the driving means includes a speed switching means for driving the photosensitive drum at a higher speed when performing the first electrophotographic process than when performing the second electrophotographic process. 2. In claim 1, the arrangement interval between the first charging means and the developing means is set to θ1. The arrangement interval between the second charging means and the developing means is set to 0.2. When the photosensitive drum driving speed when performing the first electrophotographic process is vl, and the photosensitive drum driving speed when performing the second electrophotographic process is v, then v, /
An electrophotographic recording device characterized in that v, Ki θ, and /θ1. 3. An electrophotographic recording apparatus according to claim 1, wherein the first optical system includes a convergent light transmitting array lens.