JPS62505B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting the degree of fatigue of a photoreceptor in an electrophotographic copying machine.

In an electrophotographic copying machine, since charging and exposure are repeatedly performed on one photoreceptor, the photoreceptor becomes fatigued, and this fatigue is caused by an increase in the rate of darkening or an increase in residual potential. This results in a decrease in the image density and contrast of the copy. Therefore, it is necessary to detect the degree of fatigue of the photoreceptor and, when it reaches a limit, to replace the photoreceptor. This degree of fatigue is a function of the number of copies, so it is possible to detect the degree of fatigue by cumulatively counting it. However, it is also affected by the amount of exposure, copy size, amount of charge, etc., so the amount of change in each of these can be counted and cumulatively. The degree of fatigue must be calculated based on the fatigue level. Further, if the photoreceptor is replaced, the next fatigue level of the photoreceptor cannot be detected unless the cumulative count is reset.

The present invention aims to solve the above problem, and the figures show an embodiment thereof.

1 is an integration counting circuit whose set terminal 2
It has a built-in memory that does not reset even when the power is turned off. The memory is reset only when there is an input to the reset terminal 3. Set terminal 2
The pulse applied to the photosensitive member 4 is the largest factor in fatigue of the photoreceptor 4. It may be only proportional to the number of copies, but it is preferable that it is corrected by each of the above-mentioned variations.

The output of the integration counting circuit 1 is input to the comparison circuit 6 together with the output of the program circuit 5. This program circuit 5 is set with conditions obtained through experiments in advance. The comparison circuit 6 compares the output of the integration counting circuit 1 and the output of the program circuit 5, and outputs corresponding outputs to the plurality of output terminals 1.
Give it to one of 1 to 14. This output terminal 11-1
The voltage generator 7 connected to 4 is connected to which output terminal 1
Depending on whether there is an input from 1 to 14, a voltage of a corresponding value is supplied to the developing electrode 8. _L1〜
L4 is a light emitting diode connected to each of the output terminals 11 to 14, and displays the degree of fatigue of the photoreceptor 4 in stages.

A reset pushbutton switch 10 is connected to the reset terminal 3 of the integration counting circuit 1 via an AND gate 9, and the other input terminal of the AND gate 9 is connected to the output terminal 14 of the comparator circuit 6.
It is connected to the.

Next, the operation of the device will be explained.

A number of pulses proportional to the number of copies are supplied to the set terminal 2 of the integrating counting circuit 1, and the pulses are integrated by the integrating counting circuit _1.
The comparison circuit 6 produces an output at the output terminal 11, and the voltage generator 7 supplies the developing electrode 8 with a voltage V1 until the voltage _V1 is reached. Further, the light emitting diode _L1 lights up to indicate that the photoreceptor 4 has a sufficient life remaining.

When the cumulative value of the number of copies exceeds X ₁ , the comparator circuit 6 begins to generate an output at the output terminal 12,
Until the count value by the integration counting circuit 1 reaches X ₂ ,
Continue in that state. As a result, the voltage generator 7
is a value greater than V ₁ , as shown in Figure 2.
A voltage of V ₂ is supplied to the developing electrode 8 to compensate for performance deterioration due to fatigue of the photoreceptor 4. Further, the light emitting diode _L2 connected to the output terminal 12 lights up to indicate that the fatigue level of the photoreceptor 4 has reached the second stage.

As described above, as the number of copies increases, the voltage applied to the developing electrode 8 is increased to V ₃ , V _{4 ,} etc., but the stage is reached where it is no longer possible to compensate for the performance deterioration. When it reaches , the photoreceptor 4 must be replaced. Reaching this stage can be known by the light emission of the light emitting diode _L4 indicating the final stage. In other words, when the number of copies exceeds X ₃ , the comparator circuit 6
An output appears at the output terminal 14 of , the voltage applied to the developing electrode 8 becomes V ₄ , and the light emitting diode L ₄
lights up. The output of the output terminal 14 is supplied to the AND gate 9, but since the reset pushbutton switch 10 is turned off, the integration counting circuit 1 is not reset.

When the reset pushbutton switch 10 is pressed when the photoconductor 4 is replaced, an input is given to the reset terminal 3 of the integration counting circuit 1.
is reset, and the next fatigue level of the photoreceptor 4 is counted again from zero.

If the reset push button switch 10 is operated in conjunction with the attachment and detachment of the photoreceptor 4, erroneous operation will not occur and it will be easier to perform repairs, etc.
Even if the photoreceptor is attached or detached before its life has expired, malfunction will not occur due to the action of the AND gate 9. In the case where the photoreceptor 4 is built in the drum and is fed out sequentially after use, a reset signal is issued in response to a photoreceptor feeding command.

Note that if the light emitting diodes L ₁ to _{L 4} are of different colors, the fatigue stage of the photoreceptor 4 becomes clear. Further, only the final stage may be displayed using one light emitting diode, or a lamp may be used instead of the light emitting diode.

As described above, the present invention integrates the amount that increases cumulatively as the number of copies increases, and uses this as the fatigue level of the photoreceptor to change the control amount in the copying process. Since the reset signal is obtained by replacing the photoconductor,
There is no risk of accidentally resetting the photoconductor during use, and since the reset signal is obtained via an AND gate that does not turn on unless the count value exceeds a certain level, the photoconductor can be reset even when the count value does not exceed a certain level. In other words, when it is attached and detached for repair, inspection, cleaning, etc. rather than replacement, it will not be reset by mistake.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of the present invention, and FIG. 2 is a graph showing the relationship between the number of copies and the developing voltage. 1... Integration counting circuit, 2... Set terminal, 3...
...Reset terminal, 4...Photoconductor, 5...Program circuit, 6...Comparison circuit, 7...Voltage generator, 8
...Development electrode, 10...Push button switch for reset, _L1 , _L2 , _L3 , _L4 ...Light emitting diode.

Claims (1)

[Claims] 1 Cumulatively increasing as the number of copies increases,
A counter that integrates one or more types of changes that cause fatigue to the photoconductor, and compares the output of the counter with a set value to change the control amount in the copying process, thereby reducing fatigue of the photoconductor. In an electrophotographic copying machine equipped with a control device that compensates for image quality deterioration due to 1. A fatigue level detection device for a photoconductor of an electrophotographic copying machine, characterized in that a reset signal for the counter is obtained based on an AND condition with an output signal of a switch linked to the operation.