JPH0266583A - Electrostatic image forming device - Google Patents

Abstract

PURPOSE:To obtain high quality of an image as a copy by impressing an appropriate voltage value of an electrifier according to the temperature of a photosensitive body without measuring dark attenuating amount during continuous image forming operation. CONSTITUTION:After signals from a surface potential sensor 6 and a thermister 12 are data-processed in a microcomputer CPU, they are written on a storing element 11 which can be read and written at any time. The microcomputer CPU sends a signal to a high voltage power source circuit 10 through a control circuit 9. The high voltage power source 10 adjusts a voltage which is applied to the electrifier 3 according to the signal from the microcomputer CPU, or controls the voltage to be turned on/off. In such a way, the voltage value of the electrifier corresponding to the temperature of the photosensitive body can be impressed on the electrifier during image forming process, based on the data written on the storing element. Therefore, failure in copying, etc. does not occur, and a high quality image such as a copy can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to control of the voltage value of a charger that applies charge to the surface of a photoreceptor in an electrostatic image forming apparatus.

[Prior art]

For example, in a conventional copying machine, a charger applies a charge to the surface of the photoreceptor of an electrostatic image forming device, and a surface potential sensor is installed to measure changes in the surface potential over time (III attenuation amount) when the device starts up. The voltage output value of the high-voltage power supply was controlled using a control circuit, and the surface potential near the developing device was controlled to be constant.

The reason why it is necessary to measure the potential on the surface of the photoreceptor only when the apparatus starts up as described above is because the measurement of the amount of dark decay cannot be performed during continuous copy processing in principle.

[Problem to be solved by the invention]

In conventional electrostatic image forming devices such as copying machines, when continuous processing such as continuous copying is performed, the temperature of the photoreceptor surface increases and the charging characteristics of the photoreceptor change, so the appropriate voltage to be applied changes. Problems such as copying occurred, but as described above, since the amount of dark attenuation could not be measured during continuous processing, it was not possible to perform appropriate voltage control in response to temperature changes as described above.

The present invention has been made to solve the problems of the prior art described above.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a memory element that can be read and written at any time, and a memory element that corrects the number of processed sheets and the amount of dark attenuation that occurs between the surface potential measurement position of the photoreceptor and the developing device according to the temperature of the photoreceptor. a data writing means for writing the charger voltage value; a data updating means for updating the data written by the data writing means according to a certain rule in accordance with the number of sheets to be processed; and a data writing means for writing the data written to the storage element. The electrostatic image forming apparatus is constructed as an electrostatic image forming apparatus, further comprising voltage determining means for obtaining a charger voltage value corresponding to the temperature of the photoreceptor during image forming processing.

[Function] Since the structure is as described above, the data of the charger voltage value corrected for the amount of dark attenuation occurring between the photoreceptor surface potential measurement position and the developing device depending on the photoreceptor temperature and the number of sheets processed can be read and written at any time. is written to a storage element that can be used.

Further, the data updating means updates the data in the storage element according to a certain rule according to the number of processed sheets.

Therefore, a voltage value of the charger corresponding to the temperature of the photoreceptor can be applied to the charger during the image forming process based on the data written in the memory element.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention applied to a copying machine will be described below with reference to the accompanying drawings to provide an understanding of the present invention. It should be noted that the following examples are examples embodying the present invention, and are not intended to limit the technical scope of the present invention.

FIG. 1 is a block diagram of a charger voltage adjustment device in an electrostatic image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a flowchart showing a charger voltage adjustment procedure in the electrostatic image forming apparatus. , (al is the main routine, (b
) to f81 are subroutines, Figure 3 is a graph showing the relationship between charger voltage and surface potential, Figure 4 is a graph showing an example of the amount of dark decay of surface potential, and Figure 5 is the number of copies and charger voltage according to temperature. FIG. 3 is a schematic diagram of an example of a data table of a storage element when a value is written.

First, the configuration of this embodiment will be explained with reference to the block diagram shown in FIG.

The photosensitive drum 1 is rotationally driven by a motor (not shown). A cleaning device 2.
Charger 3. SELFOC lens array 4 and developing device 5
are arranged in this order.

A surface potential sensor 6 is provided between the charger 3 and the SELFOC lens array 4 for detecting the surface charge on the photosensitive drum l given by the charging S3.

A thermistor 12 is provided near the developing device 5 to detect the temperature of the photoreceptor.

The SELFOC lens array 4 is for forming an image of the light reflected by the document 8 out of the light emitted from the light source 7 on the surface of the photosensitive drum 1.

(8) from the surface potential sensor 6 and thermistor 12
% is data processed by the microcomputer CPU and then written to the memory element 11 which can be read and written at any time. The microcomputer CPU sends a signal to the high voltage power supply circuit 10 via the jti control circuit 9, and the high voltage power supply circuit 10 adjusts the voltage applied to the charger 3 or controls the voltage on/off in accordance with the signal from the microcomputer CPU. .

Next, the control procedure for the charger 3 by the microcomputer CPU will be explained with reference to FIG.

In the following explanation, SL, S2. ... indicates the number of the processing procedure (step).

First, turn on the power in the main routine shown in Figure 2 fa+.
If N is selected (31), the process waits until the fixing temperature becomes constant (S2). When the fixing temperature becomes constant, the data writing step (S3), which is a data writing means, is performed.
FIG. 2 (Data write subroutine processing of C1 is performed.

That is, the photoreceptor temperature T is measured by the thermistor 12 (
S31). Next, in order to perform the step (S32) of calculating the charger voltage value with the dark attenuation amount corrected, the dark attenuation distortion correction subroutine processing of tel in FIG. (the so-called number of durable sheets) and the corrected charger voltage value obtained in step S32 of the dark decay amount correction are written in the memory element 11 for each temperature measured in S31 (S33). In this case, if the data to be written to the memory element 11 is written in stepwise temperature values as shown in FIG. 5, if the current photoconductor temperature is in the data table, the temperature, copy number, and charge Write the device voltage value. If the current photoreceptor temperature is not in the data table, the temperature, number of copies, and charger voltage value are written after performing predetermined arithmetic processing to match the data table.

This completes the data writing subroutine process (S34
), so return to the main routine again.

Here, the dark decay distortion correction subroutine processing is shown in Figure 2 (
e), will be explained using FIGS. 3 and 4.

First, in 5321, as an initial operation, the drive source for the photosensitive drum 1, the high-voltage power supply circuit 10 for the charger 3, and other various lamp 9 cleaning devices, static eliminators, etc. are started.

Next, at 8322, the high voltage power supply circuit 10 is activated to apply voltage 1 to the charger 3. As a result, the photoreceptor drum 1
The potential E formed on the surface of is measured when the photoreceptor drum 1 rotates and passes the surface potential sensor 6 (
S323).

Next, change the charger voltage to 5322.532
Similar to the procedure in step 3, measure the corresponding surface potential E2.53
24.5325) At the same time, the photosensitive drum 1 is stopped (S325), and the voltage V applied to the charger 3 is
,,V2 are stored in the microcomputer CPU,
Surface potentials E, , E, measured by the surface potential sensor 6
The microcomputer CP also receives a signal from the same sensor.
Stored in U.

In this state, the rotation of the photosensitive drum 1 is stopped for Δ seconds.

The length of Δ in seconds is set to the time required for the surface portion of the photosensitive drum 1 to rotate from the position facing the surface potential sensor 6 to the developing section 5' of the developing device 5. There is. Therefore, after the waiting time Δ has elapsed, the surface potential sensor 6 measures the surface potential E of the same part again, so that the part whose surface potential was El passes through the surface potential sensor 6 and then reaches the developing area. A potential E3 similar to that reached at 5' is measured (3326, 5327).

At this point, the microcomputer CPU calculates the difference between the charger voltages (2) and (1) that have already been obtained, and the surface potentials E2 and El1.
The ratio B and △ to the difference between the dark decay amount A=E2-
E, is calculated (S 328). As shown in FIG. 3, the ratio B represents the ratio of the change in surface potential to the change in the charger voltage (the slope of the straight line l).

Therefore, let Eo be the potential corresponding to the charge desired to be obtained in the developing section 5'. The voltage ■2 applied to the charger 6 necessary to generate is Va − (Eo +
A) /B ... Calculated by (1) (S329)
.

Figure 4 shows an example of the dark attenuation characteristic as described above. In the example shown, linear attenuation is assumed, but if the attenuation is in a curved manner, such a curved It is sufficient to make appropriate corrections according to the formula.

Furthermore, the relationship between the charger voltage and the surface potential shown in Figure 3 is as follows:
Although it is assumed that the thing is in a proportional state, if the actual thing is not in a proportional state, the coordinates (E+V+), (El, V
The Y-intercept with line iii IYM (surface potential axis) passing through 2) can be found from ■l=■x, El, and El, and used in the calculation of equation (1).

In the above embodiment, the voltages V, , V2 were applied to two different positions on the surface of the photoreceptor drum 1, but once the electricity is removed by the light source 7, charges are applied to the same place by rotating the photoreceptor drum 1 once. You can ride it. Furthermore, by eliminating the charge with the light #7, toner is prevented from adhering to the charge for dark decay M detection.

Naturally, it is also possible to set the location where such charges are placed outside the image forming area.

With the above, the dark attenuation il correction subroutine processing is completed (S
3210).

In FIG. 2(a), the data writing step (S3
) is completed, the copy standby state (S4) is entered, and when the copy start switch (not shown) is pressed, the copy starts (S5) L and the copy processing step (S.6
)I do.

FIG. 2(b) shows a copy processing subroutine for carrying out this copy processing.

That is, the photoreceptor temperature T at this time is measured by the thermistor 12 (361).

Next, the measured photoconductor temperature T is compared with the temperature in the temperature table already written in the memory element 11 (S62).
. At this time, if the measured photoreceptor temperature T matches the temperature T & of the temperature table already written in the memory element 11 as shown in (1) by the broken line arrow in FIG. A voltage Va is applied to the device 3. If the photoreceptor temperature T does not match the temperature in the temperature table already written in the memory element 11 (case (3) indicated by the solid arrow in FIG. 5), two values close to the measured photoreceptor temperature data (a
An example of a copy voltage determining means is to search for the 211I data + 11 and the b-th data (2) (S63), and then calculate the charger voltage by proportionally distributing the 211I data according to the temperature (364). This is it.

Then, in step S65, a voltage of 0 or more is applied to the charger 3 to apply the voltage determined by the proportional distribution.
When the copy process ends (366), the process returns to the main flow.

In the main flow of Fig. 2 1111, the copy processing step (
At the end of S6), if further continuous copying is required, the process returns to the copy processing step (S6) to perform continuous copying, and if continuous copying is not necessary, the process advances to the next step (S7).

The next step of data writing S8 is performed based on a time schedule arbitrarily set in advance, such as immediately after the completion of the copy processing step S6 and the continuous copy step S7, or after a certain waiting time thereafter.

This data writing step is S81 of S8 shown by the number in parentheses in the flow of FIG. 2(C). S82, Figure 2 (e
) flow of 3821. −． 582107 Figure 2 fc)
It consists of steps 383 and 384 of the flow of S31. of the data writing step S3 mentioned above. S32,5
321. ..., 33210S33. This step is performed in exactly the same manner as step S34.

Next, in the main flow of Fig. 2 ta+, the power is turned OFF.
When it is F (39), the data update subroutine shown in FIG. If it remains the same, the process returns to the standby step S4, and the process is repeated.

Here, Fig. 2 (Processing of data update subroutine of di)
SIO) will be explained step by step.

In the processing (S10) of the data updating subroutine for performing the data updating means, the data table from the 0th position of the storage element 11 when the number of copies and charger voltage values are written for each temperature as shown in FIG. That is, data is searched (from l-0) and updating is started (3101). When the difference between the current count value N of the number of copies and the count value Ni of the number of copies in the first data table becomes larger than a predetermined predetermined number A, that is, N.

When the data is older than the current data (S10
2) Search for two new data, for example, the third and pth data shown in the data table of FIG. 103). Based on these two new data, the first charger voltage vL to be updated is determined by proportional distribution based on temperature (3104).

Then, the process advances to the next step (3105), and the data of the next number is examined in the same way until the final number i=n of the temperature table (S106).

Note that if the value of N-N work is smaller than the value of the constant number of sheets A, the data is new and there is no need to update it.
03, skip steps 3104 and perform step 3105.

Since the data that serves as the basis for updating the data as described above has been created to some extent during the shipping adjustment and installation adjustment, there is no inconvenience that the updated data cannot be calculated due to too little basic data.

As described above, when the data update is completed (S107), the process returns to the main flow shown in FIG. 2(a), and the battery power is turned off (311).

It should be noted that the calculation method using the proportional allocation of 564.3104 may be arbitrarily selected without any problem in using an approximate calculation formula that is more suitable for the actual situation.

Further, regarding the data updating method, although a rule based on the number of copies up to now is used as a standard, it may be arbitrarily selected based on a calendar or the like.

〔Effect of the invention〕

According to the present invention, the number of sheets to be processed and the charger voltage value corrected for the amount of dark attenuation occurring between the surface potential measurement position of the photoconductor and the developing device are written in a memory element that can be read and written at any time and in the memory element for each photoconductor temperature. a data writing means; a data updating means for updating the data written by the data writing means according to a certain rule in accordance with the number of sheets to be processed; There is provided an electrostatic image forming apparatus comprising voltage determining means for obtaining a charger voltage value corresponding to the temperature of the photoreceptor.

Therefore, during continuous image forming processing, an appropriate charger voltage value can be applied to the charger according to the photoreceptor temperature without measuring the amount of dark attenuation, so that good image quality such as copying can be obtained. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a charger voltage adjustment circuit in an electrostatic image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a flowchart showing a charger voltage adjustment procedure in the electrostatic image forming apparatus. (al is the main routine, (b) ~
(el is a subroutine, Figure 3 is a graph showing the relationship between charger voltage and surface potential, Figure 4 is a graph showing an example of the amount of dark decay of surface potential, and Figure 5 is a graph showing the number of copies and charger voltage value by temperature. It is a schematic diagram of an example of a data table of a memory element when written. [Explanation of symbols] 1... Photosensitive drum 2... Cleaning device 3... Charger 4...
SELFOC lens array 5...Developing device 6...Surface potential sensor 7...Light source 9...Control circuit 10.
...High voltage power supply circuit 11...Memory element 12...
Thermistor CPU...Microcomputer 20...Electrostatic image forming device. Figure 1

Claims (1)

[Scope of Claims] 1. A memory element that can be read and written at any time, and a charger voltage corrected for the number of sheets to be processed and the amount of dark attenuation that occurs between the surface potential measurement position of the photoreceptor and the developing device, which is applied to the memory element according to the temperature of the photoreceptor. data writing means for writing a value; data updating means for updating the data written by the data writing means according to a certain rule in accordance with the number of sheets to be processed; and data writing means for writing an image based on the data written to the memory element. An electrostatic image forming apparatus comprising voltage determining means for obtaining a charger voltage value corresponding to the photoreceptor temperature during a forming process.