JPH01319063A - Image forming device - Google Patents

Abstract

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

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an image forming apparatus such as a copying machine, and more particularly to an image forming apparatus that forms an electrostatic latent image on an image carrier using two types of exposure means. .

(Prior Art) Conventionally, this type of device uses a light source to form an image of an image on a photoreceptor such as a photoreceptor drum.

The first plate consists of a document table 9, a reflecting mirror, an optical lens, etc.
Exposure means, laser, LED array, LC as a light source
A device equipped with a second exposure means using a D array or the like is known. That is, in the above-mentioned apparatus, in addition to the analog function of copying a document image using the first exposure means, the second exposure means is used to perform border erasure and masking within the copy image area.

Perform trimming, etc., and even add arbitrary characters.

It has a digital function for writing additional information such as characters, page number, date, etc.

By the way, in such a so-called analog-digital copying machine,
Normally, since a regular development method (a method in which development is performed using a developer with a polarity opposite to that of the photoreceptor) is used, when writing is performed using the second exposure means, the first exposure means A portion of the light is blocked, and the blocked area is exposed by background scanning (a method of scanning areas other than the area corresponding to the image) using the second exposure means to form characters on the image carrier.

A latent image of a character or the like is formed.

In this case, in order to obtain a microscopic image with uniform density, the latent image potential VLI on the surface of the photoreceptor due to exposure irradiation from the first exposure means and the latent image potential VLI on the surface of the image carrier due to exposure irradiation from the second exposure means are required. It is necessary that the potential VL2 is substantially the same.

(Problems to be Solved by the Invention) However, in such conventional examples, when an organic electrophotographic photoreceptor consisting of a conductive substrate, a charge generation layer, and a charge transport layer is used as a photoreceptor, charge buildup occurs due to repeated use. Abrasion of transport layer and CT material.

Repeated fatigue of the CG material may cause a decrease in the sensitivity of the photoreceptor.

For photoreceptors that have experienced such a decrease in sensitivity,
When each of the above exposures is performed at the initially set exposure amount, a deviation occurs in the latent image potentials VLI and VL2 on the surface of the photoreceptor, and if this deviation exceeds a permissible range, developer fogging occurs in the non-image area, causing the image to deteriorate. The problem was that it became difficult to distinguish between the two.

To solve this problem, we installed a potential sensor that detects the potential on the surface of the photoconductor, and by adjusting the exposure amount based on the signal obtained by this potential sensor, the potential of the latent image on the surface of the photoconductor is constantly maintained. Devices have also been devised in which the temperature is maintained constant. However, in such a device, a circuit must be provided to control the latent image potential on the surface of the photoreceptor, which poses the problem of complicating the device configuration and increasing device cost. are doing.

In addition, as a device that can adjust the latent image potential without performing such complicated control, each of the first and second exposure means is provided with an exposure amount adjustment means, and the exposure amount of each exposure means is adjusted as necessary. An apparatus in which the amount of exposure can be adjusted has been devised, but with this apparatus, the adjustment work for each exposure means is complicated, and it is difficult to suppress the latent image potential due to each exposure within the above-mentioned allowable range. There are some problems with this.

Therefore, the present invention has been made to solve the problems of the prior art described above, and its purpose is to provide a simple structure while forming a latent image by exposure using two types of exposure means. Another object of the present invention is to provide an image forming apparatus capable of forming a clear image without fogging by reducing the difference in latent image potential due to each exposure.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides two types of exposure for exposing a uniformly charged photoreceptor to form a latent image on the photoreceptor. In an image forming apparatus equipped with means,
It is characterized in that the exposure amount of one of the exposure means is freely adjustable, and the exposure amount of the other exposure means is changed in a predetermined relationship based on the amount of change in the exposure amount of the negative exposure means.

(Function) In the present invention having the above configuration, when the sensitivity decreases due to the use of the photoreceptor and the exposure amount of one adjustable exposure means is changed, the exposure amount of the other adjustable exposure means is changed. Since the exposure amount changes in a predetermined relationship based on the amount of change in the exposure amount of one of the exposure means, there is no need to adjust the two types of exposure means separately.

Furthermore, when such an adjustment is made, the exposure amount of each exposure means can be changed according to the sensitivity of the photoreceptor, so that the latent image potential on the surface of the photoreceptor during each exposure can always be approximately equal. I can do it.

(Example) The present invention will be explained below based on illustrated embodiments.

FIG. 1 shows a schematic configuration of an embodiment of an image forming apparatus according to the present invention. In the figure, reference numeral 1 denotes a photosensitive drum, which is a laminated type organic electrophotographic photosensitive member in which a charge generation layer and a charge transport layer are sequentially laminated on the surface of a cylindrical aluminum cylinder. Around this photosensitive drum l,
A means for forming an image by a known electrophotographic method is placed at a predetermined position d.
It is located in. That is, 2 is a primary charger that uniformly charges the photosensitive drum 1, 3 is a developer that uses toner to visualize the latent image formed on the drum 1 by each of the exposure means mentioned above, and 4 is a developer that A transfer charger that transfers the toner image on the photosensitive drum 1 onto a transfer paper (not shown); 5 a charger that separates the transfer paper from the photosensitive drum 1; and 6 a cleaner that removes residual toner on the surface of the photosensitive drum 1. , 7 are pre-exposure lamps for eliminating static electricity from the photosensitive drum 1.

An illumination lamp L for illuminating the original P is provided above the photosensitive drum L, and the reflected image light is transmitted to the photosensitive drum 1 via mirrors 8, 9, 10, and 11.
The first exposure means E1 serves as one of the exposure means. Note that a shutter 13 driven by a solenoid or the like is provided between the final stage mirror 11 and the photosensitive drum 1 to block the reflected light.

This light (shell lamp L is connected to the lamp regulator 14, lamp 1/Gyu 1/-Y 14) is connected in sequence to D/
A converter 15. The microcomputer 16 and the storage circuit 17 control the exposure amount as described later.

On the other hand, on the left side of the photosensitive drum 1 in the figure, the first exposure-L stage E
A second exposure means E2 is provided as another exposure means for removing static electricity from the surface of the photosensitive drum 1 before and after exposure of the original according to No. 1, and for forming arbitrary characters, characters, etc. in the copied image. The exposure means E2 includes a laser unit 18 that outputs a laser beam in accordance with an image signal, and a mirror 19 that guides the laser beam to the photosensitive drum 1.

The 1/- laser unit 18 is connected to a laser driver circuit 20, and the laser driver circuit 20 is connected to the D/A converter 15.

In the above configuration, when forming a desired composite image, the following operations are performed.

First, in order to form an image of the document P, the illumination lamp L is turned on, and the image light reflected by the document P is transmitted to the mirrors 8, 9,
10.11 and the imaging lens 12 onto the photosensitive drum 1, and a latent image corresponding to the original image is formed on the drum 1.

Then, the shutter 10 is driven to block the image light of the document P, and a laser beam from the laser unit 18 is irradiated onto the light-blocked area of the photosensitive drum 1 to expose it in the shape of a character pattern or vice versa. The above manuscript P on 1
A 'fiI image corresponding to arbitrary characters, characters, etc. is formed in the latent image corresponding to the character.

Thereafter, the synthesized latent image on the photosensitive drum 1 is visualized as a toner image by a developing device 3, transferred and separated by a separation band 4.
, 5, the toner image is transferred onto the transfer paper through a transfer 1 separation step. Further, the image on the transfer paper is fixed by a fixing device (not shown), so that a stable composite image can be obtained.

Here, the exposure amount of the illumination lamp L and 1/- user unit 18 constituting each of the exposure means El and E2 is
Is there a mark for each so that there is no difference in EI? If the latent image potential due to the exposure of the illumination lamp L is VLI and the latent image potential due to the exposure of the laser unit 18 is VL2, then the potential of one note on the surface of the photosensitive drum 1 V=- For 650V, VL1=VL2=-15
Illumination lamp L and laser unit 1 so that the voltage is 0V.
The exposure amount of 8 is adjusted and each set value is stored in the storage circuit 17.

If each exposure is performed under the conditions set in this way, a clear composite image can be obtained, but if copying is performed repeatedly, the surface of the photosensitive drum 1, which is an organic photoreceptor, will be exposed to the transfer paper,
Scraping occurs due to rubbing with the cleaner 6, and the sensitivity of the drum 1 decreases due to deterioration of the CG material and CT material, and it may become impossible to obtain a proper image under the initially set exposure conditions.

In that case, the exposure amount of the illumination lamp L and the laser unit 18 may be adjusted so as to obtain an appropriate image, but in this embodiment, it is not necessary to adjust the exposure amount of the illumination lamp L and the laser unit 18 separately. In order to avoid the hassle and the difficulty of adjusting the rain exposure value without variation, the laser unit of the second exposure means E2 is set so as to follow the change in the exposure amount of the illumination lamp L of the first exposure means E1. The structure is such that the exposure amount of 18 is changed.

That is, first, a constant α representing a change in exposure amount in the first exposure and a constant β representing a change in exposure amount in the second exposure are input into the storage circuit 17 in advance.

Then, when the exposure amount of the illumination lamp L is changed by ΔVH, the exposure amount of the laser unit 18 is changed by the storage circuit 17.
The microcomputer 16 controls the light emission amount of the laser unit 18 based on the exposure amount change ΔVH of the illumination lamp L so that it changes according to the following equation (1) stored in the microcomputer 16. In this case, in order to calculate the exposure amount change ΔVH, the voltage applied from the lamp regulator 14 to the illumination lamp is used.

α: Relationship between potential and exposure amount during first exposure (lamp L) β: Relationship between potential and exposure amount during second exposure (laser 22) 18) A: Current second exposure value A′: New Second exposure value ΔvH calculated from the first exposure value: Change in exposure amount in the first exposure Here, regarding a specific method for adjusting the exposure amount of the illumination lamp L and the laser unit 18, the This will be explained with reference to a flowchart.

First, by pressing a service switch (not shown), the operation section (not shown) of the copying machine is switched from the copying mode, which is the state where copying is performed, to the service mode, that is, the copying machine is stopped.
The memory circuit 17 is made accessible from the operating section. Then, in step ■, the rank key (
When the first exposure address, that is, the exposure address by the illumination lamp L is inputted using the (not shown), the first exposure address and the current exposure amount (AC input voltage to the illumination lamp L) are displayed on the operation unit. , In order to compensate for the decreased sensitivity caused by the repeated action of one photosensitive drum in step (2), a value larger than the exposure amount currently displayed is input to the first exposure address. Note that step ■■ is operated by the user.

In step (2), the first exposure value inputted by the rank key is stored in the storage circuit 17, and in step (2) this first exposure value and each flight previously stored in the storage circuit 17, that is, VL= -150V, α, and β are used to determine the second exposure amount relative to the first exposure amount, that is, the amount of light emitted by the laser unit 18. Then, the second exposure value calculated by equation (1) in step (2) is stored in the memory circuit 1.
7, and then the operating section switches from the service mode to the copy mode.

As described above, in this embodiment, since there is no need to separately adjust the exposure amount of the illumination lamp and the laser unit 18, it is easy to adjust the shading of the image, and furthermore, the exposure amount of the laser unit 18 can be easily adjusted. changes in accordance with the change in the exposure amount of the illumination lamp L, thus preventing fogging before and after exposing the original by the first exposure, and fogging or thinning of the image when writing characters etc. by the second exposure, thereby forming a clear composite image. be able to.

Further, since there is no need to provide a sensor for detecting the surface potential of the photoreceptor and a complicated control circuit as in the conventional example, there is also the effect that the cost of the apparatus can be kept low.

In this embodiment, a laser unit is used as an exposure means for writing arbitrary characters, but in addition to this, an LED array and an LCD that are driven according to image signals are used.
A configuration using an array or the like may also be used.

(Effects of the Invention) In the present invention having the above configuration and operation, when the exposure amount of one exposure means is adjusted, the exposure amount of the other exposure means is also adjusted. There is no need to adjust the exposure amount separately, which simplifies the adjustment work.

Furthermore, since the exposure amounts of both exposure means are varied while maintaining a constant relationship, it is possible to prevent variations in the latent image potential on the surface of the photoreceptor, and as a result, fogging in non-image areas and thinning of the image in the copied image can be prevented. It is possible to prevent this and obtain a clear composite image.

Furthermore, since there is no need to detect the potential on the surface of the photoreceptor using a potential sensor, etc., and control the potential to always keep it constant, the device configuration becomes simpler and costs can be reduced, among other benefits. It is something that plays.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention, and FIG. 2 is a flowchart showing a procedure for determining a second exposure value in the embodiment. Explanation of symbols 1... Photosensitive drum (photosensitive member) 16... Microcomputer 17... Memory circuit 18... Laser unit El... First exposure means (one exposure means) E2...・
Second exposure means (other exposure means) L... illumination lamp

Claims (3)

[Claims] (1) In an image forming apparatus equipped with two types of exposure means for exposing a uniformly charged photoreceptor to form a latent image on the photoreceptor, the exposure amount of one of the exposure means can be freely adjusted. An image forming apparatus characterized in that the exposure amount of the other exposure means is changed in a predetermined relationship based on the amount of change in the exposure amount of the one exposure means. (2) Among the two types of exposure means, one of the exposure means is an analog exposure means that forms a latent image by forming a light image of the document on a photoreceptor, and the other exposure means is a laser.
A digital exposure means having a light emitting means such as an LED array or an LCD array, and by exposure of the digital exposure means,
Claim 1, characterized in that unnecessary charges on the surface of the photoreceptor are removed before and after exposure of the original image by the analog exposure means, and arbitrary characters, characters, etc. are added to the copied image.
The image forming apparatus described above. (3) The image forming apparatus according to claim 1 or 2, wherein the photoreceptor is an organic electrophotographic photoreceptor in which a conductive substrate, a charge generation layer, and a charge transport layer are laminated.