JP3461422B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a contact type charging roller.
The present invention relates to an image forming apparatus such as a facsimile apparatus, a printing apparatus, a copying apparatus or the like, which forms an image on a photoconductor with a contact member of a roller.

[0002]

2. Description of the Related Art In recent years, an image forming apparatus employing a contact charging system in which a contact type charging member such as a charging roller or a charging belt is brought into contact with a photosensitive member to charge the photosensitive member to form an image has been used. . In this contact charging type image forming apparatus, the charging efficiency of the contact charging member greatly changes due to the following reasons (1) and (2).

(1) The lower the surface temperature of the contact charging member, the lower the charging efficiency. That is, the charging efficiency changes due to the surface temperature of the contact charging member. (2) The charging efficiency decreases as the surface of the contact charging member becomes dirty. That is, the charging efficiency changes due to the dirt on the surface of the contact charging member.

In order to suppress the fluctuation of the charging efficiency of the contact charging member due to the cause of the above (1), when the high voltage output is controlled to a constant voltage, the charging voltage changes with a constant applied voltage. The temperature in the vicinity of the charging member or its contact type charging member is detected by a temperature detecting means such as a thermistor, and the voltage applied to the contact type charging member is corrected based on the detected temperature, and the charging voltage of the contact type charging member is corrected. Is to be constant.

Further, if the charging roller becomes soiled with time other than the temperature shown in (1) above, the charging efficiency will decrease. The fluctuation of the charging efficiency of the contact charging member due to the above (1) cause. There is. As a result, an image that is good at the beginning may cause a “background smeared image” due to a decrease in the potential of the photoconductor over time.

Generally, most of the dirt on the charging roller is toner. By cleaning the charging roller with a cleaning member of the charging roller in a predetermined manner, it is possible to prevent the potential of the photosensitive member from decreasing with time. As described above, in the contact-type charging and transfer, since the sensitivity and the characteristics of the contact-type charging member and the contact-type transfer member are changed by the dirt of the toner, it is necessary to always treat them so as not to be dirty.

[0007]

However, the above-mentioned cleaning member is mainly a system using a member such as a pad or a blade from the viewpoint of the shape and the occupied area, and if the cleaning operation is excessively performed by such a cleaning member. However, there is a problem that the charging roller is scraped off and wear deterioration is caused at an early stage. Therefore, if the cleaning operation is suppressed, the problem described in (2) above occurs.

[0008] The present invention has been made in view of the above, the cleaning of the contact member of the contact charging member in the image forming apparatus is performed without excess or deficiency to be able to print in a stable image forming condition To aim.

[0009]

In order to achieve the above object, the present invention provides a storage means for storing the sum of image data in the effective image area in the main scanning direction and the sub-scanning direction and a contact with the photoconductor. a row <br/> Nau means an image forming operation by the contact member of the formula charging member, a cleaning means for cleaning said contact member at the high voltage output or the cleaning member, based on the value stored in the storage means There is provided an image forming apparatus including a cleaning operation correction unit that corrects the cleaning operation interval and the cleaning operation time of the cleaning unit at a predetermined time interval.

Further, a storage means for counting and storing the image forming operation time and the image forming operation number and the transfer sheet size, the image forming <br/> moving due to contact members of the contact charging member to the photosensitive member Means for performing the operation, a cleaning means for cleaning the contact member with a high-voltage output or a cleaning member, and a cleaning for correcting the cleaning operation interval and the cleaning operation time of the cleaning means based on the count value stored in the storage means. It is preferable that the image forming apparatus includes a motion correcting unit.

Furthermore, the toner density detection means for detecting the toner concentration at the time of image forming operation, storage means for storing the toner concentration detected by the unit, by contact members of the contact type charging member to the photosensitive member means for forming an image operation, a cleaning means for cleaning said contact member at the high voltage output or the cleaning member, a cleaning operation interval and the cleaning operation time of the cleaning means on the basis of the toner density stored in the storage means It is preferable that the image forming apparatus includes a cleaning operation correcting unit for correcting.

[0012] The image forming apparatus according to the present invention, stores the sum of the image data in the main scanning direction and the sub scanning direction effective image area, the high voltage output or cleaning the contact member of the contact charging member in contact with the photosensitive member Since the cleaning operation interval and the cleaning operation time for cleaning with the member are corrected based on the above sum value, the toner consumption amount is calculated from the sum value of the number of image data, and the optimum cleaning is performed according to the toner consumption amount. The contact member can be cleaned with the operation interval and the cleaning operation time, and the contact member can be cleaned without excess or deficiency to perform printing under stable image forming conditions.

Further, it counted and stored the image forming operation time and the image forming operation number and the transfer sheet size, cleaning operation of the contact member of the contact charging member in contact with the photosensitive member to clean the high voltage output or the cleaning member If the interval and the cleaning operation time are corrected based on the above count values, the optimum cleaning operation is performed according to the contamination of the contact member estimated from the image forming operation time, the number of image forming operations, and the use conditions of the transfer paper size. The contact member can be cleaned with the interval and the cleaning operation time, and the contact member can be cleaned without excess or deficiency to perform printing under stable image forming conditions.

Furthermore, and detects and stores the toner concentration at the time of image forming operation, the cleaning operation interval for cleaning the contact member of the contact charging member in contact with the photosensitive member at the high voltage output or a cleaning member cleaning operation time the If the correction is performed based on the toner concentration, the contact member can be cleaned at the optimum cleaning operation interval and cleaning operation time according to the contamination of the contact member estimated from the usage condition of the toner concentration during the image forming operation. Therefore, the contact member can be cleaned without excess or deficiency and printing can be performed under stable image forming conditions.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 2 is a diagram showing a schematic configuration around a photoconductor of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a diagram showing a circuit configuration of write control and drive control of the image forming apparatus according to the embodiment of the present invention. FIG. 4 is a diagram showing a circuit configuration for detecting the toner consumption amount of the image forming apparatus according to the embodiment of the present invention. Figure 5
FIG. 6 is a diagram showing a relationship between multi-valued data and a toner adhesion amount in the image forming apparatus according to the embodiment of the present invention. Figure 6
FIG. 6 is a timing chart diagram of a cleaning operation in the image forming apparatus according to the embodiment of the present invention.

As shown in FIG. 2, by cleaning the charging roller 2 with the cleaning pad 4 which is a cleaning member,
The decrease in the potential of the photoconductor 1 is prevented. In addition, the transfer roller 3
Is arranged under the photoconductor 1 so as to press the transfer paper fed by the registration roller 7 against the photoconductor 1, and a voltage having a polarity opposite to that of the toner on the photoconductor 1 is applied. Therefore, the toner on the photoconductor 1 is transferred to the transfer paper by the action of the electrostatic force based on the voltage of the transfer roller 3. A contact / separation mechanism for contacting / separating the charging roller 2 with respect to the photoconductor 1 is performed by turning on / off a solenoid, a motor, or the like.

Further, it is provided with a developing unit 5, a toner sensor 6, a cleaning blade 8, a charge eliminating section 9 and the like, and the operation thereof is common to that of a normal image forming apparatus, and therefore its explanation is omitted. It should be noted that the cleaning operation of the transfer roller 3 may be performed, but in the following description, the description of the processing will be omitted for convenience.

In the writing and drive control of this image forming apparatus, as shown in FIG.
Although the processing is performed based on the data of AM12, this processing is the same as that of a normal image forming apparatus, and the description thereof will be omitted.

Further, this image forming apparatus is provided with means for counting the number of image data when handling the image data, and by this means, the amount of toner adhering to the photoconductor from the developing device can be predicted.

As shown in FIG. 4, the toner consumption amount of this image forming apparatus is detected by using the conversion table of the RAM 20. The relationship between image data (multi-valued data) and toner consumption is not linear.

For example, as shown in FIG. 5, the multivalued data "0001" does not correspond to 1/16 dot. Therefore, as shown in FIG. 4, the input multivalued data (code data) is converted into toner consumption data by a conversion table stored in the RAM 20. Also, since the amount of toner adhesion (consumption) differs depending on the toner concentration, R
A conversion table for converting the toner consumption amount for each toner density is stored in the AM 20, and the CPU of the system control controls to select a plurality of conversion tables stored in the RAM 20.

Multivalued data is converted into toner consumption data by the conversion table of the RAM 20, latched by the first stage flip-flop (FF) 21, and the toner consumption data is sent to the adder (Adder) 22. The adder 22 calculates the sum of the input toner consumption data and the remaining toner consumption data of the previous time, sends the resulting data to the flip-flop (FF) 23 of the next stage, and the counter (C
outer) Send a carry signal to C1.

The adder 22 has a performance according to the input toner consumption data (multivalued data level). For example, if the toner consumption data has 3 to 4 values, 2+
2 bits (bits), 3 + 3 bits (5-8 values), 4 + 4 bits (9-16 values (bi)
t) respectively. That is, the size of the adder 22 is determined according to the number of bits of the input data.

For example, when the toner consumption data is 4-bit data "0000-1111", when the adder 22 adds the toner consumption data and outputs a carry signal, the counter C1 is incremented by "+1". That is, the carry signal from the adder 22 is counted to obtain the total toner consumption amount.

This counter is composed of n counters C1 to Cn.
And the FGATE signal is O (indicating the effective image area).
Only in the N state, the carry signal from the adder 22 counts up and the FGATE signal is cleared in the OFF state. The outputs of the counters C1 to Cn are latched in a flip-flop (FF) 24 at the end of the FGATE signal, and the latched data is stored in the CPU of the system controller.
Reads. The same result can be obtained for the data input to the RAM 20 whether it is code data or binary data of "0000" or "1111".

The toner consumption data (toner consumption area) read from the flip-flop (FF) 24 is represented by upper 8 bits. For example, if the image data is A3 size (42
In the case of 0 × 297), the total number of dots is calculated by the following equation. 420 x (400 / 25.4) x 297 x (400/2
5.4) = 30935582 (dots)

Then, 30935582 indicates "1 11
01 1000 0000 1010 0001 11
10B ”, and its upper 8 bits“ 1 1101 1
00 "(0 ecH).

Next, the total sum of the image data is obtained by the following equation. However, each end 2 mm is excluded. (420-2-2) x (400 / 25.4) x (297
-2-2) × (400 / 25.4) = 30228285
(Dot)

Then, 30228285 indicates "1 11
00 1101 0011 1111 0011 11
01B ”and its upper 8 bits“ 1 1100 1
10 "(0e6H).

Since the toner consumption data has already been converted at the time of counting up, the data "0e6H" means that the toner is attached to the entire surface of A3.
(However, excluding 2 mm from the end)

Then, as shown in FIG. 6, the CPU of the system control unit carries out the cleaning operation at the timing of the post-processing (indicated by the one-dot chain line frame in the figure) based on the toner consumption data. In other words, the degree of dirt on the charging roller differs depending on the amount of toner attached to the photoconductor. Therefore, in the cleaning operation, the charging roller and the cleaning pad (cleaning pad) are driven and cleaning is performed at the timing when no voltage is applied to the charging roller. The pads are brought into contact with each other to remove the toner adhering to the charging roller.

That is, the RAM 20 counts the storage means for storing the sum of the image data in the effective image area in the main scanning direction and the sub scanning direction, the image forming operation time, the number of image forming operations, and the transfer paper size. It functions as a storage unit for storing and a storage unit for storing the toner concentration detected by the unit. Further, the toner sensor 6 functions as a toner density detecting means for detecting the toner density during the image forming operation.

The charging roller 2 and the developing unit 5 are also provided.
The transfer roller 3 functions as a unit for performing image forming operation and image transfer operation on the photoconductor 1 by the contact members of the contact type charging member and the contact type transfer member. Further, the cleaning pad 4 functions as a cleaning means for cleaning the charging roller 2 as a contact member with a high voltage output or a cleaning member.

The CPU of the system control unit is the RAM 2
Cleaning operation correction means for correcting the cleaning operation interval and cleaning operation time of the charging roller 2 by the cleaning pad 4 at predetermined time intervals based on the value stored in 0, and the cleaning pad based on the count value stored in the RAM 20. Cleaning operation correction means for correcting the cleaning operation interval and the cleaning operation time of the charging roller 2 by means of No. 4, or the cleaning operation interval and the cleaning operation time of the charging roller 2 by the cleaning pad 4 based on the toner density stored in the RAM 20. And fulfills the function of cleaning operation correction means for correcting

As described above, the contact type charging device and the like are in contact with the photoconductor after the cleaning process, but toner is slightly attached to the surface of the photoconductor after the cleaning process, and the toner is attached to the charging roller and the like. I often do it. Therefore, if the amount of image data in the image forming operation is large, the amount of toner used will be large, and the charging roller will be contaminated with toner early even with the same number of image forming times.

Therefore, in the image forming apparatus of this embodiment, the number of image data using toner is detected by the image information, and the cleaning operation interval and the cleaning operation time of the charging roller and the transfer roller are determined by the integrated value of the number of image data. Since the correction is performed, a stable image forming condition can be obtained by performing a cleaning operation for the charging roller and the transfer roller without excess or deficiency.

FIG. 1 is a flow chart showing a cleaning operation time correction process in the image forming apparatus according to the embodiment of the present invention. In this process, in step (indicated by "S" in the figure) 1, it is determined whether or not the cleaning request flag is "ON". If the cleaning request flag is "ON", a cleaning operation request has already been issued, and the process is returned. Wait for the end of the forming operation (because the cleaning operation is performed as post-processing after the end of the image forming operation), and then "ON"
If not, the process proceeds to step 2 to judge whether the drive motor is "ON", and if not "ON", the process returns and "O"
If "N", the process proceeds to step 3, the motor ON counter is incremented by "+1", and the process proceeds to step 4.

In step 4, the FGATE signal is "ON".
Then, it is determined whether or not it is turned "OFF". This FGA
The TE signal is a signal indicating an image area, and when the signal turns from "ON" to "OFF", the writing of one image area is completed. FGA is judged by this judgment in Step 4.
If the TE signal does not change from "ON" to "OFF", the process returns.

At the judgment of step 4, the FGATE signal is "O".
When "N" is changed to "OFF", the process proceeds to step 5 and the number of image data is read. For example, A3 whole surface is solid 0E6h
(230) Further, the process proceeds to step 6 and the image data number is added to the total image counter, the process proceeds to step 7 and it is judged whether or not the motor ON counter is over "300 seconds (s)". If not, the process returns. , Then go to step 8.

At step 8, the total image counter is set to "230.
0 seconds (s) ”or more is determined, and if so, the process proceeds to step 14, the cleaning timer setting time, which is the cleaning operation time, is corrected to“ 15 seconds (s) ”, and the process proceeds to step 12. Then, the motor ON counter and the total image counter are reset to "0", the process proceeds to step 13, the cleaning quest flag is set to "1" (that is, "ON"), and the process returns.

The total image counter is determined to be "2" by the judgment in step 8.
If it does not exceed "300 seconds (s)", proceed to step 9 to determine whether or not the total image counter reaches "1000 seconds (s)", and if so, proceed to step 15 to determine the cleaning operation time. The set time of a certain cleaning timer is corrected to “10 seconds (s)”, the process proceeds to step 12 to reset the motor ON counter and the image total counter to “0” respectively, and the process proceeds to step 13 to set the cleaning risquest flag to “ 1 "(that is," ON ") and return.

At the judgment of step 9, the total image counter is "1".
If it does not exceed 000 seconds (s), step 10
Then, it is judged whether the total image counter is "500 seconds (s)" or more, and when it is judged, the process proceeds to step 16 and the cleaning timer set time which is the cleaning operation time is set to "4 seconds (s)". Correction, and proceed to step 12 to reset the motor ON counter and the image total counter to "0" respectively, proceed to step 13 to set the cleaning quest flag to "1" (that is, "ON"), and then return. To do. Then, when the cleaning operation is completed, the cleaning request flag is reset.

FIG. 7 is a flow chart showing the correction processing of the cleaning operation interval in the image forming apparatus of this embodiment. In this process, it is determined in step (indicated by "S" in the figure) 21 whether the cleaning request flag is "ON",
If it is "ON", the cleaning operation request has already been generated, and the process returns and waits for the end of the image forming operation (because the cleaning operation is performed in the post-processing at the end of the image forming operation). Go ahead and judge whether the drive motor is "ON". If it is not "ON", return to "ON".
If so, proceed to step 23, and set the motor ON counter to "+
1 ”and proceed to step 24.

At step 24, the FGATE signal becomes "O".
It is determined whether the "N" has turned to "OFF". This F
The GATE signal is a signal indicating an image area, and when "ON" changes to "OFF", the writing of one image area is completed. F is judged in this step 24
If the GATE signal does not change from "ON" to "OFF", the process returns.

When the FGATE signal changes from "ON" to "OFF" in the judgment of step 24, the routine proceeds to step 25, where the number of image data is read. For example, A3 full solid 0
It becomes E6h (230). Further, the process proceeds to step 26, the number of image data is added to the total image counter, and step 2
In step 7, it is determined whether or not the total image counter is "1500" or more, and when it is determined in step 28, it is determined whether or not the motor ON counter is "200 seconds (s)" or more. If not, return is made, and if so, go to step 29.

If the total image counter does not exceed "1500" in the determination in step 27, step 32
Then, it is judged whether or not the motor ON counter has reached "400 seconds (s)" or more. If not, the process returns, and if it does, the process proceeds to step 29.

In step 29, the set time of the cleaning operation interval of the cleaning timer is corrected to "2 seconds (s)", and step 30
In step 31, the motor ON counter and the total image counter are reset to "0", and in step 31, the cleaning quest flag is set to "1" (that is, "ON") and the process returns. In this way, finer correction can be made by further increasing the number of division steps and independently setting the cleaning timer value.

In this way, the toner consumption is calculated from the sum of the number of image data, and the contact member of the charging roller and the transfer roller is set at the optimum cleaning operation interval and cleaning operation time according to the toner consumption. Since the contact member is cleaned, the contact member can be cleaned without excess or deficiency to prevent the contact member from being worn and deteriorated at an early stage, and printing can be performed under stable image forming conditions.

Next, even in the same apparatus, the usage pattern of each user is greatly different, and the number of times image formation is performed in a series of image forming operations varies, and the size of the transfer paper used even with the same number of times of image formation. The time during which the photoconductor and the charging roller are in contact with each other and rotating is significantly different.

That is, even if the same number of sheets is fed, the driving time of the photoconductor differs depending on the paper feeding position and the transfer paper discharging position, so that the rotation time of the charging roller (contact time with the photoconductor) changes.
Further, the ratio of the image area and the non-image area varies depending on the size of the transfer paper even with the same photoconductor driving time, so that the degree of contamination of the charging roller changes. Therefore, in the image forming apparatus, the cleaning operation may be corrected according to the number of image formations, the image forming operation time, and the operation mode. Next, the processing will be described.

FIG. 8 is a flow chart showing another correction process of the cleaning operation in the image forming apparatus of this embodiment. This processing is step (indicated by "S" in the figure) 4
In step 1, it is determined whether the cleaning request flag is "ON". If the cleaning request flag is "ON", a cleaning operation request has already been issued, and the process returns and waits for the end of the image forming operation. (Because it is done in post-processing), then "ON"
If not, proceed to step 42 and turn on the drive motor.
If it is not "ON", it returns,
If "ON", the routine proceeds to step 43, where the motor ON counter is incremented by "+1" and the routine proceeds to step 44.

At step 44, the FGATE signal is "O".
It is determined whether the "N" has turned to "OFF". This F
The GATE signal is a signal indicating an image area, and when "ON" changes to "OFF", the writing of one image area is completed. F is judged in this step 44
If the GATE signal does not change from "ON" to "OFF", the process returns.

When the FGATE signal is changed from "ON" to "OFF" in the judgment of step 44, the process proceeds to step 45 to increment the paper passing counter by "+1", and to step 46, whether the paper passing size is A3 or B4. If it is A3, the process proceeds to step 47, increments the A3 counter by "+1" and proceeds to step 48, and if B4, proceeds directly to step 48.

In step 48, it is judged whether or not the motor ON counter has become "300 seconds (s)" or more. If not, the routine proceeds to step 56, in which it is judged whether or not the sheet passing number counter has become "60 sheets" or more. If not, the process returns, and if it does, the process proceeds to step 55 to correct the set time of the cleaning timer to “4 seconds (s)”, and step 5
Go to 2.

When the motor ON counter is "300 seconds (s)" or more in the judgment of step 48, it proceeds to step 49 and it is judged whether or not the paper passing counter is "40 sheets (s)" or more. If so, the routine proceeds to step 55, where the set time of the cleaning timer is corrected to "4 seconds (s)", and the routine proceeds to step 52.

If it is determined in step 49 that the number of passed sheets counter does not exceed "40 sheets", the process proceeds to step 50 to determine whether the A3 counter has exceeded "20 sheets", and if so, step 55. In step 52, the cleaning timer setting time is corrected to "4 seconds (s)", and the flow advances to step 52.
In addition, the A3 counter is "20 sheets" according to the determination in step 50.
If not, go to step 51 to correct the cleaning timer setting time to "2 seconds (s)", and go to step 52.

In step 52, the motor ON counter and the number of passed sheets are reset to "0", the process proceeds to step 53 to reset the A3 counter to "0", and the process proceeds to step 54 to set the cleaning risquest flag to "1". "
(That is, "ON") and return.

In this manner, the cleaning toner of the cleaning device is cleaned depending on the contamination of the contact member between the charging roller and the transfer roller, which is estimated from the use conditions of the image forming operation time, the number of image forming operations, and the transfer paper size. Since the contact member can be cleaned at the optimum cleaning operation interval and cleaning operation time according to the estimated usage amount, the contact member can be cleaned without excess or deficiency to prevent the contact member from being worn and deteriorated early. In addition, printing can be performed under stable image forming conditions. It should be noted that the ON / OFF of the drive motor and the sheet passing size may be managed according to the data of the sheet feeding port and the discharging port.

Next, even under the same image forming conditions, the toner consumption greatly changes depending on the toner density in the developing unit. That is, the amount of toner scattered from the developing unit varies depending on the toner concentration during the image forming operation, and the amount of toner attached to the photoconductor greatly changes under the same image forming conditions except for the toner concentration. Therefore, when the high toner density is maintained and when the low toner density is maintained, the toner density adhering to the charging roller or the transfer roller greatly changes.

Therefore, since the toner consumption amount changes as a result of the output of the toner concentration detecting means for controlling the toner concentration, the toner concentration is sampled at a predetermined interval and the cleaning operation is corrected based on the result. Good to do. Next, the processing will be described.

FIG. 9 is a flow chart showing still another correction process of the cleaning operation in the image forming apparatus according to the embodiment of the present invention. In this process, the cleaning request flag is "ON" in step (indicated by "S" in the figure) 61.
If it is “ON”, a cleaning operation request has already been generated, and the process returns and waits for the end of the image forming operation (because the cleaning operation is performed as post-processing at the end of the image forming operation). If it is not "ON", the process proceeds to step 62 to judge whether the drive motor is "ON". If it is not "ON", the process returns. If "ON", the process proceeds to step 63 and the motor ON counter is set to "+1". Then, the process proceeds to step 64.

At step 64, the FGATE signal becomes "O".
It is determined whether the "N" has turned to "OFF". This F
The GATE signal is a signal indicating an image area, and when "ON" changes to "OFF", the writing of one image area is completed. F is judged by this judgment in step 64.
If the GATE signal does not change from "ON" to "OFF", the process returns.

If the FGATE signal does not change from "ON" to "OFF" in the judgment at step 64, the process returns.
If so, the flow advances to step 65 to read the data from the toner density detecting means, and the flow advances to step 66 to judge whether the toner density data is "6% wt" or more, and "6% w"
If "t" or more, the process proceeds to step 77 to set A = "5", proceeds to step 69, adds the value of A = "5" to the density counter, and proceeds to step 70.

If the toner concentration data is not "6% wt" or more in the determination of step 66, the process proceeds to step 67, it is determined whether the toner concentration data is "4.5% wt" or more, and "4. If it is 5% wt or more, proceed to step 76 A
= “4” is set, the process proceeds to step 69, the value of A = “4” is added to the density counter, and the process proceeds to step 70.

If the toner density data is not "4.5% wt" or more in the judgment of step 67, the process proceeds to step 68 to set A = "3", and the process proceeds to step 69 to set A = "3" to the concentration counter. Value is added and the process proceeds to step 70.

In step 70, it is judged whether or not the motor ON counter has become "300 seconds (s)" or more. If not, the process returns. If it does, the routine proceeds to step 71, where the density counter becomes "200" or more. If yes, the process proceeds to step 79, the cleaning timer setting time is corrected to "8 seconds (s)", and the process proceeds to step 74.

At the judgment of step 71, the density counter is set to "2.
If it is not "00" or more, it proceeds to step 72 to judge whether or not the concentration counter is "100" or more, and if it is, it proceeds to step 78 to set the cleaning timer to "4 seconds (s)". Correction to step 74.

At the judgment at step 72, the density counter is set to "1".
If it does not exceed "00", the routine proceeds to step 73, the cleaning timer setting time is corrected to "2 seconds (s)", and the routine proceeds to step 74. In step 74, the motor ON counter and the density counter are each reset to "0", the process proceeds to step 75, the cleaning quest flag is set to "1" (that is, "ON"), and the process returns.

In this way, the contact member is cleaned at the optimum cleaning operation interval and cleaning operation time according to the contamination of the contact member of the charging roller and the transfer roller estimated from the usage condition of the toner density during the image forming operation. Therefore, the contact member can be cleaned without excess and deficiency to prevent the contact member from being worn and deteriorated at an early stage, and printing can be performed under stable image forming conditions.

[0070]

As has been described in the foregoing, according to the image forming apparatus according to the present invention, it can be printed in a stable image forming condition the cleaning of the contact member of the contact charging member is performed without excess or deficiency.

[Brief description of drawings]

FIG. 1 is a flowchart showing a cleaning operation time correction process in an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration around a photoconductor of an image forming apparatus according to an embodiment of the present invention.

FIG. 3 is a diagram showing a circuit configuration of write control and drive control of the image forming apparatus according to the embodiment of the present invention.

FIG. 4 is a diagram showing a circuit configuration for detecting a toner consumption amount of the image forming apparatus according to the embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between multi-valued data and a toner adhesion amount in the image forming apparatus according to the embodiment of the present invention.

FIG. 6 is a timing chart of a cleaning operation in the image forming apparatus according to the embodiment of the invention.

FIG. 7 is a flowchart showing a cleaning operation interval correction process in the image forming apparatus according to the embodiment of the present invention.

FIG. 8 is a flowchart showing another correction process of the cleaning operation in the image forming apparatus according to the embodiment of the present invention.

FIG. 9 is a flowchart showing still another correction process of the cleaning operation in the image forming apparatus according to the embodiment of the present invention.

[Explanation of symbols]

1: photoconductor 2: charging roller 3: Transfer roller 4: Cleaning pad 5: Development unit 6: Toner sensor 7: Registration roller 8: Cleaning blade 9: Static eliminator 10: CPU 11: ROM 12, 20: RAM 21,23,24: Flip-flop (FF) 22: Adder C1 to Cn: Counter

Continuation of the front page (56) Reference JP-A-7-49603 (JP, A) JP-A-7-261625 (JP, A) JP-A-8-110684 (JP, A) JP-A-8-62934 (JP , A) JP-A-7-128956 (JP, A) JP-A-8-63076 (JP, A) JP-A-8-146794 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) G03G 15/02 G03G 21/14

Claims (3)

(57) [Claims] 1. A storage means for storing the sum of the image data in the main scanning direction and the sub scanning direction effective image area, the line image forming operation by the contact member of the contact type charging member to the photosensitive member < a cleaning means, a cleaning means for cleaning the contact member with a high-voltage output or a cleaning member, and a cleaning operation interval and a cleaning operation time of the cleaning means at predetermined time intervals based on the value stored in the storage means. An image forming apparatus comprising: a cleaning operation correcting unit that corrects 2. A storage means for counting and storing the image forming operation time and the image forming operation number and the transfer sheet size, the image forming operation due to the contact member of the contact charging member to the photosensitive member
And a cleaning means for cleaning the contact member with a high-voltage output or a cleaning member, and a cleaning operation for correcting the cleaning operation interval and the cleaning operation time of the cleaning means on the basis of the count value stored in the storage means. An image forming apparatus comprising: a correction unit. 3. A toner density detection means for detecting the toner concentration at the time of image forming operation, storage means for storing the toner concentration detected by said means, by contact members of the contact type charging member to the photosensitive member means for forming an image operation,
A cleaning unit that cleans the contact member with a high-voltage output or a cleaning unit, and a cleaning operation correction unit that corrects the cleaning operation interval and the cleaning operation time of the cleaning unit based on the toner concentration stored in the storage unit. An image forming apparatus characterized by the above.