JPS6023868A - Electrophotographic device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electrophotographic apparatus that uses an insulating belt to convey and transfer transfer paper.

[Prior art] In an electrophotographic device such as a copying machine that forms an image using an electrostatic electrophotographic process, a toner image formed on a photoreceptor is transferred by applying a transfer charge to a transfer paper via an insulating belt. There are things that can be transferred onto paper.

This transfer method has advantages such as no transfer errors, but on the other hand,
It has the following drawbacks.

That is, if the transfer charge is small, the toner image on the photoreceptor will not be sufficiently transferred to the transfer paper. Furthermore, if there is too much transferred charge, peeling discharge occurs, and the charge distribution becomes non-uniform, resulting in missing transferred images and uneven transfer.

Therefore, it is difficult to set and control the amount of transferred charge, and there is a problem in that it is not possible to respond to changes in various parts over time (for example, deterioration of the insulating belt).

[Objective] It is an object of the present invention to solve the above-mentioned problems and provide an electrophotographic apparatus that can appropriately control the amount of transferred charge by controlling the amount of transferred charge based on the transfer state of a toner image. .

[Configuration] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing the main parts of an embodiment of the present invention.

In the figure, ■ is a contact glass on which the original PA is placed, and marks are placed on the contact glass 1 at predetermined locations where the original is not placed to form a pattern used for transfer charge amount control and toner density control, which will be described later. A is attached.

2 is an optical system that optically scans the original PA in the direction of arrow A;
Reference numeral 3 denotes a mirror that irradiates the drum photoreceptor 4 with the output light of the optical system 2.

A charger 5 uniformly charges the surface of the drum photoreceptor 4. Since the drum photoreceptor 4 is rotating in the direction of arrow B, an electrostatic latent image is formed on the surface of the drum photoreceptor 4 by the output light of the optical system 2, and this electrostatic latent image is developed with toner by the developer 6. Ru.

7 is an endless insulating belt.

It is moved once in the direction of arrow C by rollers 11.9 and 10 at the same speed as the circumferential speed of drum photoreceptor 4.

Reference numeral 11 denotes a transfer charger that supplies transfer charges to the transfer paper. The transfer paper fed in the direction of the arrow from a paper feed section (not shown) is supplied with a transfer charge while it is positioned on the transfer charger 11, whereby the toner image on the drum photoreceptor 4 is transferred to the transfer paper. Thereafter, the transfer paper is conveyed in the direction of arrow E and guided to a fixing section (not shown), where one henna image is fixed.

I2 is a cleaner that removes the toner remaining on the drum photoreceptor 4, 13 is a static eliminator that removes the charge on the surface of the drum photoreceptor 4, and 14 is a cleaner that removes the toner remaining on the insulating bell 1-7. be.

On the other hand, as shown in FIG. 2, the electrostatic latent image corresponding to the mark H is developed to form a pattern MP, and the density of this pattern is detected by the density detector 15. Also,
This pattern MP is transferred onto the insulating belt 7 by the transfer charger 11, and this transferred pattern MP'
The concentration of is detected by the concentration detector 16.

FIG. 3 illustrates the concentration detector 15. As shown in FIG. In this way, this embodiment uses a reflective photoelectric conversion element.

Further, the concentration detector 16 also has a similar structure.

FIG. 4 illustrates the control system. In the figure, detected values of density detectors 15 and 16 are applied to a comparison calculation control section 23 via amplifiers 21 and 22 as developed density Dd and transfer density De, respectively.

The comparison calculation control unit 23 calculates the transfer rate Re expressed by the following equation.
Calculate.

e Re = □ d Then, this transfer rate Re is compared with a set transfer rate set in advance, and if the transfer rate Re is smaller than this set transfer rate, the output voltage of the high voltage power supply section 24 for the transfer charger II is is increased by a predetermined value. Note that the maximum allowable value of the output voltage of the high-voltage power supply section 24 is set to prevent transfer charges from becoming excessive.

Further, the density of the toner that is finally transferred to the transfer paper needs to be equal to or higher than a predetermined value. In this case, the toner replenishment clutch 25 is turned on for a predetermined period of time to replenish toner and increase the toner concentration in the developer. Note that the on time of the toner replenishment clutch 25 may be changed based on the deviation of the developer density.

With the above configuration, when the operator places the original PA at a predetermined position on the contact glass 1 and presses the start key of the copying machine, the mark N is first read by the optical system 2 before the original P^, and then the original PA is read by the optical system 2, and an electrostatic latent image corresponding to these is formed on the surface of the drum photoreceptor 4, which rotates in synchronization with the operation of the optical system 2, and the developing device 6
It is developed with

When the drum photoreceptor 4 rotates to a position where the pattern MP faces the density detector 15, the comparison calculation control section 23 activates the density detector 15 and inputs the developed density Dd.

Then, when the drum photoreceptor 4 has rotated to a position where the pattern MP faces the transfer charger 11.

The comparison calculation control section 23 operates the high voltage power supply section 24 to supply power to the transfer charger 11 to transfer the pattern onto the insulating bells 1 to 7.

Then, when the insulating belt 7 moves to a position where the pattern transferred to the insulating belt 7 corresponds to the density detector 16, the comparison calculation control unit 23 activates the density detector 16 to determine the transfer density Do. input.

Then, the comparison calculation control unit 23 calculates the transfer rate Re and compares it with the set transfer rate, and also compares the development density Dd with the set development density, and executes control based on the respective comparison results. .

Note that the toner image corresponding to the original document PA is transferred to the transferred transfer paper at a predetermined timing, and is transported to the fixing section. Further, the pattern transferred to the insulating belt 7 is removed by the cleaner 14.

By the way, as the concentration detector 16 mentioned above, a transmission type photoelectric conversion element is used when the insulating belt 7 is transparent.

Furthermore, in the embodiment described above, the mark M is used to form the pattern M
Although P is formed, the pattern formation is not limited to this. For example, the charger 5 may apply only the charge for the pattern to the drum photoreceptor 4, or a filter or the like may be inserted in the exposure path from the mirror 3 to the drum photoreceptor 4 to form the pattern.

Note that the comparison calculation control section may be a main body control section that controls the entire copying machine, and the key to the pattern is the drum photoreceptor 4.
It may be formed anywhere as long as it is the upper non-image forming area.

[Effects] As explained below, according to the present invention, a predetermined pattern is formed on the non-image forming area of the photoreceptor, and the transfer charge is determined based on the density during development and the density after transfer. Since the amount is controlled, the amount of transferred charge can always be maintained at an appropriate value, and uneven transfer can be prevented. Furthermore, since the toner density in the developing device is controlled by the density during development, there is an advantage that the density of the image after transfer can be made appropriate.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, FIG. 2 is a front view illustrating a pattern formed on a drum photoreceptor, and FIG.
The figure is a sectional view showing an example of a concentration detector, and FIG. 4 is a block diagram showing an example of a control system. l...Contact glass, 2...Optical system, 3...
Mirror, 4... Drum photoreceptor, 5... Charger, 6... Developer, 7... Insulator belt, 11...
Transfer charger, 15.16...Concentration detector, 23.
...Comparison calculation control section, 24...High voltage power supply section, 25...
・Toner replenishment clutch, N mark, liver pattern. 49- Figure 7 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] In an electrophotographic device that transfers a toner image on a photoreceptor to a transfer paper by applying an electric charge to the transfer paper via an insulating belt,
a pattern forming means for forming a predetermined pattern as an electrostatic latent image on a non-image forming area on the photoreceptor; a first density detecting means for detecting the density of the developed pattern; and a first density detecting means for detecting the density of the developed pattern; A second density detection means for detecting the density of the pattern is provided, and the transfer charge amount is controlled based on the detection value of the first density detection means and the detection value of the second density detection means, and the transfer charge amount is controlled based on the detection value of the first density detection means and the second density detection means. An electrophotographic apparatus characterized in that toner density is controlled based on a detection value of a density detection means.