JPS59170866A - Copying machine - Google Patents

Abstract

PURPOSE:To control the condition of image formation securely even in continuous copying operation by detecting a surface state corresponding to a dark part between images during continuous image formation and controlling the condition of the image formation. CONSTITUTION:When the continuous copying operation starts, a potential sensor 7 measure a light part potential. Then, a blank exposure lamp 6 is turned off when an optical system is inverted, and the sensor 7 measures a dark part potential. The measured surface potentials of the light and dark parts are processed by a potential control circuit 19 to generate control data to be outputted to an electrifier, etc., so that both potentials approximate target values respectively. Then, the control data is outputted to a high voltage unit 20 and the light part potential and dark part potential are adjusted to approximate the target values respectively. Thus, the dark part potential is measured at intervals of one image during the inversion of the optical system in continuous copying operation to control the condition of image formation properly.

Description

TECHNICAL FIELD The present invention relates to a copying apparatus, and particularly to a copying apparatus that detects surface conditions such as latent image potential of a photoreceptor and controls image forming conditions based on the detection results.

Prior art This type of conventional copying apparatus performs controlled rotation prior to copying operation, and then measures the potential of the latent image on the photosensitive drum for each bright area and dark area, and adjusts the charging conditions so that the potential approaches the target value. The system was configured to determine the exposure and development bias conditions based on the determination. However, in modes where image formation is performed continuously under fixed conditions, such as continuous copying, the image forming conditions determined during control rotation are continuously used as is, making it difficult to cope with fluctuations in image conditions. There were drawbacks.

However, if the controlled rotation is performed every time one document is scanned, there is a drawback that the time required for the copying operation becomes longer.

OBJECTS The present invention has been made in view of the above points, and an object of the present invention is to provide a copying apparatus that can perform reliable image formation even during continuous copying without increasing the time required for copying.

Embodiments From the following, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 shows a schematic configuration of a copying apparatus according to the present invention.

The photosensitive drum 1 is composed of, for example, three layers, an insulating layer, a photoconductive layer, and a conductive layer from the surface, and is driven by a driving means (not shown) and rotated by a ladle T3-machine body (not shown). Supported. Around the photosensitive drum 1, in the rotational direction, there are a primary charger 2, a secondary charger 3, a full-surface exposure lamp 4-1, a potential sensor 7, a developing roller 5 of a developer, a transfer charger 28, a pre-static charge remover, A charging device 29 is arranged. Further, a blank exposure lamp 6 is arranged on the L side of the secondary charger 3 to form dark and bright potentials.

The entire surface of the photosensitive drum 1 is uniformly charged by the primary charger 2, and the image of the original 10A illuminated by the original exposure lamp 11 is mirrored by the primary charger 2. The photosensitive drum 1 is exposed through steps 12 and 13. At this point, the secondary charger 3
The charge is removed according to the image of the original document, and toner is developed by the developing roller 5 after the entire surface is exposed by the full-surface exposure lamp 4.

As will be described later, a bias pressure is applied to the developing roller 5, and the positive tone of the image is adjusted by jumping development. Subsequently, the transfer (1) electric device 28 is activated, and the transfer to the transfer paper is stopped.

During the copying operation, the document exposure lamp 11 and mirrors 12, 13 are moved from the position indicated by the symbol X to the position Y 16 by a drive means (not shown) to scan the document 10A. Further, a known white marker plate 10B is provided near position X (home position), and by scanning this stopper-shaped white plate 10B, the bright area potential, which will be described later, is measured.

゛The signal from the upper level sensor 7 is inputted via the potential measurement circuit 18 to the potential control circuit 19 constituted by a microcomputer or the like, where it is subjected to predetermined processing. The output of the potential amount ti11 circuit 19 is input to a high voltage unit (?
The output of this high voltage unit 2o is input to the primary charger 2, the secondary charger 3, the developing roller 5, the transfer charger 28, and the original exposure lamp 11, and each charge amount, developing bias, and exposure amount are controlled by the potential control i11. It is determined by the control of the circuit 19.

Next, the operation of the following configuration will be explained in detail with reference to FIGS. 2 and 3.

, 1TJZ shows the operation of the optical system when performing continuous copying.

First, when starting a continuous copy operation, the bright area potential is measured.

Here, first, at position X in FIG.
2.13 The static ′? A TII image is formed on the photosensitive drum 1''. High brightness potential V due to strong exposure
St- and the dark potential vO when the lamp is turned off on the photosensitive drum.
Form into two. This latent image potential is measured by the potential sensor 7, and the measurement result is input to the potential control circuit 198 via the potential measuring circuit 18.

Next, as shown by the arrow R in FIG. 2, the original exposure lamp 11
, mirror] 2.13 is moved to position Y, and the photosensitive drum 1 is irradiated with reflected light from the document 10A.

At this time, when the optical system is reversed at position Y as indicated by the symbol Q in FIG. 2, the blank exposure lamp 6 is turned off and the dark area potential is measured. This dark area potential is measured by the potential sensor 7 in the same way as the bright area potential.

The surface potentials of the bright and dark areas measured as described above are processed in the potential control circuit 19, and a high voltage circuit (20) is applied so that the bright area potential and the dark area potential approach the Ll mark 1, respectively. Control data to be output to the subsequent charger, document exposure lamp 11, and developer is formed through the steps 1 to 1.

For example, when controlling the amount of charge, Δ11−αlΔ
■o1α2ΔVS l−ΔI2−βlΔVo +f32
According to the two equations of AVs L, find the primary current (1) and secondary current (2) to be passed through the primary and secondary chargers 2.3. In the old model, ΔI1. Δ■2 is the change, Δ■o, Δ■ko, and the light area potential and lltf measured in series.
14th place [] deviation amount of target price, α engineering, α2, βl,
-β2 is a control coefficient.

The control data obtained in the above manner is the high pressure knee.
, and is output to the primary charger 2 and the secondary charger 3.
The voltage applied to A is also determined, and the bright area potential V! , and the dark potential VD are turned on five times so that they approach the target values.

In the period S in Fig. 2, the optical system is reversed to the J position (position The electrostatic latent image is developed with toner by the developing roller 5, and the toner on the photosensitive drum 1'' is transferred to a transfer sheet (not shown) by the transfer charger 28, and the first original copying operation is completed.

Subsequently, the same operation as scanning the second image, scanning the third image, etc. is repeated, but at this time, each time the optical system is reversed, the dark area electron is measured as shown by the symbol Q. The image forming conditions are controlled in the same manner as described above.

As described above, by measuring the dark area potential for every three images when reversing the optical system during continuous copying, accurate control of image forming conditions becomes possible. Especially in the case of continuous copying (in this case, the dark area potential is measured when the optical system is reversed, so there is no need to measure the bright and dark area potentials before scanning as in the conventional case). The required I#S interval for rotation can be shortened.

In the above embodiment, the bright area potential is measured only immediately before scanning the 1st image [-1, but as shown by the symbol P in FIG. Meibe Den I 17 A
jl+ may also be determined.

Further, in the embodiments described above, a configuration was exemplified in which the amount of charge was controlled based on the bright area and dark area potentials, but it may also be configured to control the exposure area by the document exposure lamp 11 or the developing bias. Of course.

In addition, in the following embodiments, the optical system is moved to scan a document or a standard white plate. Of course, the present invention can also be applied to a copying apparatus that scans an original image.

As is clear from the above description, the present invention provides an image forming apparatus that measures the surface condition of a photoreceptor and controls the image forming conditions based on the measurement results. The system uses a configuration that detects the surface condition depending on the dark area between the image and the image, and controls the image forming conditions according to the surface condition, so even during continuous copying, reliable image formation is possible without increasing the operation time. An excellent copying apparatus capable of controlling conditions can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a copying apparatus according to the present invention, and FIGS. 2 and 3 are explanatory diagrams each explaining the operation of the copying apparatus according to the present invention. 1... Photosensitive drum 2... Primary charger 3...
・Secondary charger 4...Full exposure lamp 7...
Potential sensor IOA...Original 10B...Standard white plate 11...Original exposure lamp 28...Transfer charger

Claims (3)

[Claims] (1) In an image forming apparatus that measures the surface condition on a photoreceptor and controls image forming conditions based on the measurement results, the surface condition corresponding to the dark area between images is detected during continuous image formation, and the A copying apparatus characterized in that image forming conditions are controlled according to the state. (2) The copying apparatus according to claim 1, wherein the dark area potential is measured immediately after the optical system or document table moves backward during continuous image formation. (3) A standard white plate is placed near the scanning start position of the optical system or document table, and the image forming conditions are determined by the bright area potential of the electrostatic latent image formed on the photoreceptor by the reflected light from this standard white plate. 3. The copying apparatus according to claim 2, wherein the copying apparatus controls: