JPH03166562A - Image forming device - Google Patents

Abstract

PURPOSE:To form an image without ground stain, superior in image density and reproductivity of low contrast by carrying out idling, impressing charge for a longer time than the specified time, and increasing light quantity of an exposure lamp when stopping time is long. CONSTITUTION:After the finishing of the copying, a stoping time counter 10 is activated, and if this value is, for example, within ten hours, a normal image formation process is carried out at the next copying. On the other hand, if the counter value exceeds ten hours, a charger control circuit 14 is activated by a signal from the stopping time counter 10, an electrifying charger 2 is turned ON for two seconds which is a longer time than the normal idling, and a motor driver 15 is activated to drive a photosensitive body drum 1. An eraser 8 is also activated for approximately two seconds. Then, charge and light fatique equal to two rotations of the photosensitive body drum 1 is given. Thus, a good image quality can always be obtained.

Description

Detailed Description of the Invention [Industrial Field of Application] This field relates to an image forming apparatus that applies a charge to an organic photoreceptor using a scorotron charger and then irradiates a light image, particularly for image formation on a photoreceptor. The present invention relates to an image forming apparatus characterized by process control.

[Conventional technology]

In an electrophotographic image forming apparatus, an image forming process of charging, exposure, development, transfer, separation, cleaning, and static elimination is performed on a photoreceptor.

By the way, by executing this image process, the photoreceptor becomes fatigued, and the charging ability and the sensitivity of the photoreceptor deteriorate. As a result, background smudges may occur, and image density may change. There was a problem in that low contrast reproducibility fluctuated and good images could not be obtained unless process conditions were reset for each copy.

The above-mentioned problem occurred due to the influence of variations in the photoreceptor, especially when deterioration over time progressed or when environmental changes occurred.

In addition, the charging ability and sensitivity of the photoreceptor deteriorate due to a long resting time of the photoreceptor. FIG. 2 is a potential characteristic diagram of the photoreceptor, including a conductive layer, a charge generation layer. The graph shows how the charging ability of a transparent organic photoreceptor with a charge transport layer and the sensitivity of the photoreceptor deteriorate as the rest time increases, converted into potential. That is, since the black potential V is the potential of the image area of the photoreceptor, a decrease in this means that the charging ability is decreasing, and the white potential VL is the potential of the non-image area. Therefore, an increase in this value means that the sensitivity of the photoreceptor is deteriorating.

In order to deal with such photoreceptor deterioration, the following techniques have been proposed.

l) When the main switch is turned on, the photoreceptor is charged and exposed, and after idling, the image forming process is executed.

2) Measure the photoreceptor potential before starting copying, and repeat the above image forming process after reaching a predetermined value.

3) Depending on the pause time, the developing bias for the next copy is changed according to the number of copies.

In addition, as a technique related to the conventional example, Japanese Patent Application Laid-Open No. 1983-1986
3021, JP 55-101959, JP 56-32152, JP 56-32153
Publication number. JP-A No. 63-250666 and the like can be mentioned.

[Problem to be solved by the invention]

Among the above conventional techniques, in 1), if the photoconductor is initialized frequently, a new problem arises in which fatigue progresses due to idling, and although the charging ability is recovered to some extent,
Since the sensitivity of the photoreceptor is not recovered, there are problems such as background smearing and low contrast reproducibility are not improved.

FIG. 3 is a potential characteristic diagram of the photoreceptor when it is idling, and when one hour has passed after stopping the image forming process, the photoreceptor is rotated twice and the charger and eraser are activated, and it is idling. VD, VL of
This shows the transition of From this figure, it can be seen that the charging ability is improved by idling the photoreceptor after one hour of rest, but the sensitivity is not improved.

In addition, in 2), the photoconductor potential is detected and controlled until it reaches a predetermined value, and then the image forming mode is started, which is reasonably stable, but since the first copy takes time, the copy speed is The problem was that it fell off.

Furthermore, in 3), the background smear is improved by changing the developing bias according to the copy, but not only is the image density not improved, but there is a problem that the amount of change in density becomes large due to the change in the developing potential.

It should be noted that FIG. 4 is a characteristic diagram showing the relationship between the exposure lamp voltage and the vL potential, and it can be seen that by increasing the lamp voltage, the value (■) decreases, in other words, the photoreceptor sensitivity increases.

The present invention has been made in view of this background,
The purpose is to eliminate the drawbacks of the above-mentioned conventional technology, and to form an image that can always obtain good image quality by responding to fluctuations in the charging ability and sensitivity of the photoreceptor without reducing copy speed. The goal is to provide equipment.

[Means to solve the problem]

The above object is to provide a pause time measuring means for measuring the pause time after the completion of image formation in an image forming apparatus that applies a charge to an organic photoconductor using a scorotron charger and then irradiates a light image, and a pause time measuring means for measuring the pause time after image formation, and a copy count. When the measured value by the counting means and the rest time measuring means exceeds a predetermined value, and when the measured value by the charger control means for extending the charge application time of the charger and the rest time measuring means also exceeds a predetermined value. If the values measured by the motor control means for idling the organic photoreceptor and the rest time measuring means exceed a predetermined value, the light intensity of the exposure lamp is set to be higher until the count value of the copy number counting means reaches a predetermined value. This is achieved by providing a lamp voltage control means for controlling the lamp voltage.

[Effect]

When copying is started after a certain period of time has passed after the completion of image formation, a charge is applied to the photoconductor for a longer period than normal (within a certain period of time) before the start, and the photoconductor is idled before copying is started. Until copying, the amount of exposure applied to the photoreceptor is set to be higher than the normal value.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram of the control of the image forming apparatus according to the present invention, in which 1 is an organic photoreceptor (hereinafter referred to as a photoreceptor drum), 2 is an electrostatic charger, 3 is a contact glass 5 on which a document 4 is placed, An exposure illumination system includes an exposure lamp 6, an imaging lens 7, etc., 8 is an eraser, and 9 is a static elimination lamp; only the portions of the image forming unit that are relevant to the present invention are shown.

Further, 10 is a pause time counter (pause time measuring means) for counting the time during which the copy operation is paused, 11 is a sheet number counter (copy sheet counting means) for counting the number of copies, and 12 is a lamp voltage control circuit (lamp voltage 13 is a power supply for the exposure lamp 6; 14 is a charger control circuit (charger control 1,000 steps); 15 is a motor driver (motor control means); 16 is a drive motor for the photosensitive drum 1; l7 is a control means; 18 is potential detection means.

The potential detection means 8 is for detecting the potential of the reference black portion and the reference white portion on the photoreceptor drum 1, and is provided near the photoreceptor drum 1 on the downstream side of the eraser 8.

After the copying operation is completed, a downtime counter 1o is activated, and if this value is within 10 hours, a normal image forming process is executed during the next copying. On the other hand, if the counter value exceeds 10 hours, the charger control circuit 14 is operated by the signal from the rest time counter 10, and the charger 2 is turned on for 2 seconds, which is longer than during normal idling. The motor driver 15 is also operated to drive the photosensitive drum 1. Note that the eraser 8 is also operated for about 2 seconds. Charge and optical fatigue are applied to the photosensitive drum 1 for two revolutions. Next, during copying, the lamp voltage control circuit 12 is operated prior to copying, the exposure lamp voltage is increased by two steps, and the original 4 on the contact glass 5 is irradiated with light.

As explained with reference to FIGS. 3 and 4, idling prevents deterioration of the charging ability, and increasing the lamp voltage compensates for deterioration of photoreceptor sensitivity. Further, at this time, the charging charger 2 is also turned on for a longer time than a predetermined time to further improve the efficiency of preventing deterioration of the charging ability.

Further, the image forming apparatus according to the present invention not only forms an image but also forms a reference black portion on a photoreceptor. Detects the voltage of the reference white area and activates the charger. A control system is adopted that controls the exposure lamp voltage to always maintain a predetermined potential, but the charger 2 is controlled (VO stability control) and the exposure lamp 6 is controlled according to the reference pattern potential. i (VL stability system 'a> is being implemented.

That is, the charger control circuit 1 is output from the control means 17 in response to the reference pattern potential detected by the potential detection means l8.
4 and the lamp voltage control circuit 12.

By controlling in this manner, image quality is stabilized over the long term.

In addition, by using a self-control type charger called a scorotron charger, it is possible to prevent the charging ability from decreasing at a constant idling time without changing the idling time, regardless of the fatigue state of the photoreceptor over time. be.

〔Effect of the invention〕

As explained above, according to the present invention, when the downtime becomes long, idling. Since the charge was applied for a longer time than the specified time and the light intensity of the exposure lamp was increased, the photoreceptor potential became stable, there was no background smudge, and the image density and
An image forming apparatus with excellent low contrast reproducibility can be provided.

In addition, the reference potential is detected under the above conditions when the pause time is longer than a predetermined value, and the charger is adjusted based on this. Since the exposure lamp is controlled, it is possible to provide an image forming apparatus that can maintain stable image quality over a long period of time without instructing the control conditions after increasing the lamp voltage by two steps, for example. .

[Brief explanation of the drawing]

FIG. 1 is a control conceptual diagram of an embodiment of the image forming apparatus according to the present invention, FIG. 2 is a potential characteristic diagram depending on the rest time of the photoreceptor, and FIG.
The figure is a potential characteristic diagram of the photoreceptor during idling, and FIG. 4 is a characteristic diagram showing the relationship between exposure lamp voltage and vL potential. DESCRIPTION OF SYMBOLS 1... Photoreceptor, 2... Charger, 6... Exposure lamp, 10... Pause time counter, 11... Number of sheets counter, 12... Lamp voltage control circuit, 14...
・Charger control circuit, 15...Motor driver, 1
6... Drive motor, 17... Control means, 18...
Potential detection means. Fig. 2 Fig. 3 Resting time Fig. 4 Exposure lamp voltage (△VLP)

Claims (2)

[Claims] (1) In an image forming apparatus that applies a charge to an organic photoreceptor using a scorotron charger and then irradiates a light image, there is a downtime measuring means that measures the downtime after image formation is completed, and a number of copies. a charger control means for extending the charge application time of the charger when the measured value by the rest time measuring means exceeds a predetermined value; If the values measured by the motor control means for idling the organic photoreceptor and the rest time measuring means exceed a predetermined value, the light intensity of the exposure lamp is set to be high until the count value of the copy number counting means reaches a predetermined value. An image forming apparatus comprising: lamp voltage control means. (2) In claim 1, when the measured value by the pause time measuring means exceeds a predetermined value, the reference black portion or the reference white portion formed under each condition of charge application time, exposure lamp light amount, and photoreceptor idling. An image forming apparatus comprising a control means for controlling a charger voltage and an exposure lamp voltage based on a detected potential so that a photoreceptor always has a predetermined potential.