JP3032649B2 - Electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus for performing automatic image quality compensation control for maintaining the density of a copied image in an initial state based on the sensor output of a pickup sensor for automatic image quality compensation.

[0002]

2. Description of the Related Art Generally, an electrophotographic apparatus transfers toner adhered to an electrostatic latent image formed on a photoreceptor by exposing a document image to a transfer sheet, and heats and melts the transferred toner to fix it on the transfer sheet. By doing so, a copy image is obtained. The density of the copied image has a close relationship with the amount of toner adhered to the photoreceptor, and the amount of exposure of the original image, which is a factor that determines the amount of toner, depends on the contamination, deterioration, and temperature of the copy lamp. It is easy to change due to change or the like.

[0003] Therefore, an electrophotographic apparatus forms a toner patch on a photoreceptor by an exposure amount when a predetermined lamp voltage is applied to a copy lamp, and determines the state of the toner patch by an automatic image quality compensation such as a reflection type photo sensor. An automatic image quality compensation control for detecting the sensor output using a pickup sensor and adjusting the exposure amount based on the sensor output so that the toner amount is constant is performed.

Incidentally, the above optical pickup sensor, like the above-described copy lamp, changes its absolute output value due to dirt, deterioration, temperature change, etc., and therefore requires a calibration operation to correct the amount of change in the absolute output value. It is. Therefore,
A conventional electrophotographic apparatus has two optical pickup sensors as a sensor for density measurement and a sensor for monitoring, and as shown in FIG. 30, a change amount K ₁ · K at two points on a high density side and a low density side. ₂ by the monitor sensor, the initial sensor outputs A and B
The calibration is performed by feeding back to the concentration measuring sensor so that

[0005]

However, in the above-described conventional electrophotographic apparatus, since the sensor for density measurement and the sensor for monitoring are composed of separate optical pickup sensors, a high-precision error occurs due to an output error between the two sensors. In addition to the difficulty in correction, there is a problem that the structure is complicated and the cost is increased by the monitor sensor, the correction circuit, and the like.

In addition, when the sensor output of the density measuring sensor and the monitor sensor is fluctuated due to eccentricity and uneven rotation of the photosensitive member, or uneven formation of the photosensitive layer of the photosensitive member, stable automatic image quality is obtained. There is also a problem that compensation control becomes impossible.

[0007]

Means for Solving the Problems Claims 1 to 3
In order to solve the above-mentioned problem, the electrophotographic apparatus of the present invention sets the density of a copied image to a predetermined value by an automatic image quality pickup sensor that outputs a sensor output corresponding to a toner amount of a toner patch formed on a photoconductor. , And has the following features.

That is, in the electrophotographic apparatus according to the first aspect, the marking provided on the photosensitive member is detected by the photosensitive member position detecting means, and the same photosensitive member is identified based on the detection result.
The position is determined as a predetermined position to be a sensor detection position and a toner patch forming position on the photoconductor, and the sensor output of the drum bare surface at the predetermined position of the photoconductor and the position formed at the predetermined position on the photoconductor. It is characterized in that this is performed by maintaining the ratio of the toner patch to the sensor output at a predetermined value .

[0009] In addition, the electrophotographic apparatus according to claim 2, the sense of
Detecting markings formed on the optical body and the markings
Photoconductor position detecting means, and the detected marking position
Storage means for storing a sensor output for one rotation of the drum surface of the photoconductor starting from a predetermined position of the photoconductor determined based on the above, and a formation position of a toner patch formed on the photoconductor is stored in the predetermined position. Detection based on the position and the formation
A reading unit that reads a sensor output of the drum surface corresponding to the position from the storage unit; a sensor output of a toner patch formed at an arbitrary position of the photoconductor; and a sensor of the drum surface corresponding to the toner patch forming position. The automatic image quality compensation control is performed by maintaining the ratio with the output to a predetermined value .

According to a third aspect of the present invention, there is provided an electrophotographic apparatus, comprising: a sensor output for one circumference of a drum surface of a photoconductor starting from a predetermined position of the photoconductor; and a reference toner patch formed on the photoconductor at a predetermined density. Storage means for storing a sensor output for one rotation of the photoconductor drum starting from the predetermined position; a sensor output of a drum surface corresponding to a formation position of a toner patch formed on the photoconductor and a reference toner patch; Reading means for reading a sensor output from the storage means, wherein the ratio of the sensor output of the toner patch formed at an arbitrary position of the photoconductor to the sensor output of the drum surface corresponding to the formation position of the toner patch, to maintain the calculated value calculated by multiplying the correction values calculated from the sensor output of the corresponding reference toner patch on the formation position of the patch to a predetermined value It is characterized in that the automatic image quality compensation control is performed Te.

[0011]

According to the first to third aspects of the present invention, the absolute value of the output of the pickup sensor for automatic image quality compensation changes due to dirt, deterioration, temperature change, etc., and the sensor output obtained from the drum surface and the toner patch is initialized. Even when the sensor output is lower than the sensor output in the state, the rate of change (change rate) of the sensor output of the drum surface and the sensor output of the toner patch is the same.

Therefore, when only the absolute value of the output of the pickup sensor for automatic image quality compensation changes, the ratio of the sensor output obtained from the drum surface and the toner patch in the initial state to the drum surface after the output absolute value changes. And the ratio of the sensor output obtained from the toner patch has the same value, and the difference between the two ratios occurs only when the toner amount changes due to factors other than the automatic image quality pickup sensor.

[0013] Thus, an electrophotographic apparatus according to claim 1 to claim 3, even if obtaining the sensor output by a single automatic image quality compensation pickup sensors, it is possible to perform accurate automatic image quality compensation control, The structure can be simplified and the cost can be reduced.

According to the first aspect of the present invention, the predetermined position of the photoconductor is specified by detecting the marking formed on the photoconductor by the photoconductor position detecting means.
Automatic image quality compensation control is performed based on the ratio of sensor outputs obtained from the same predetermined position. Therefore, in addition to the above effects, the electrophotographic apparatus according to the first aspect of the present invention provides a stable automatic image sensor even when the sensor output of the automatic image quality compensation pickup sensor is fluctuated due to, for example, eccentricity or uneven rotation of the photoconductor. Image quality compensation control is possible.

According to the second aspect of the present invention, the photosensitive member is
The formed marking is detected by the photoconductor position detecting means.
This allows the specified position of the photoreceptor to be specified
In comprises a storage means for storing the sensor output of the photoreceptor drum sober one rotation originating the predetermined position, automatic image quality compensation based on the ratio of the sensor output obtained from any position of the photosensitive member Control is performed. Therefore, in the electrophotographic apparatus according to the second aspect , in addition to the above effects, the sensor output is obtained from an arbitrary position of the photoconductor, so that local fatigue of the drum surface of the photoconductor can be prevented, and the eccentricity and rotation of the photoconductor can be prevented. Even when the sensor output of the automatic image quality compensation pickup sensor fluctuates due to unevenness or the like, stable automatic image quality compensation control can be performed.

According to the third aspect of the present invention, the sensor output for one rotation of the drum surface of the photoconductor starting from a predetermined position of the photoconductor and the reference toner patch formed on the photoconductor at a predetermined density are provided. A storage unit for storing the sensor output for one rotation of the drum of the photoconductor starting from the predetermined position; calculating a ratio of the sensor output obtained from an arbitrary position of the photoconductor from the sensor output of the reference toner patch; Automatic image quality compensation control is performed based on a calculated value calculated by multiplying the corrected correction value. Therefore, in the electrophotographic apparatus according to the third aspect , in addition to the above-described effects, the sensor output is obtained from an arbitrary position of the photoconductor, so that the local fatigue of the drum surface of the photoconductor can be prevented, and the eccentricity and rotation of the photoconductor can be prevented. Even if the sensor output of the pickup sensor for automatic image quality compensation is fluctuated due to unevenness or unevenness in the formation of the photosensitive layer of the photosensitive member, more stable automatic image quality compensation control is possible.

[0017]

[Embodiment 1] An embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 8, the electrophotographic apparatus according to this embodiment has a transparent document table on the upper surface of the copying machine main body 1, and the document table is provided with a document to be copied. And an original cover 26 that supplies the original to the original mounting table. An optical system 2 is provided below the document table. The optical system 2 irradiates light to the document placed on the document table, and a reflected light from the document. It has a plurality of reflecting mirrors 4, 5, 6, and 7, which are guided on the photoreceptor 21, as indicated by a dashed line, and a zoom lens 8 disposed on the optical path.

A standard white plate 5 used for automatic image quality compensation control is located outside the image area on the side of the tip of the optical system 2.
3 are provided. A photoreceptor 21 to which the above-described reflected light is irradiated is disposed below the optical system 2, and a charger 2 for charging the photoreceptor 21 is provided around the photoreceptor 21.
2. Developing unit 23 for attaching toner to photoconductor 21, transfer unit 24 for transferring the toner image formed on photoconductor 21 to transfer paper, and static eliminator 25 for removing charge of photoconductor 21
And so on.

On the side where the transfer paper is supplied to the photoreceptor 21, a paper feed unit comprising a registration roller 31 for setting the supply timing of the transfer paper and a plurality of paper feed cassettes capable of accommodating the transfer paper of each size. 30 are provided. Also,
On the side where the transfer paper is unloaded from the photoreceptor 21, a belt-shaped transport device 32 for mounting and transporting the transfer paper, a fixing unit 33 for heating and melting the toner transferred to the transfer paper, and a copy image are provided. A plurality of discharge trays 34 and the like on which the formed transfer paper can be placed in a plurality of sheets are provided. Further, below the photoreceptor 21, an intermediate tray 36, a paper feed roller 38, and a reversing unit 3 used for duplex copying or composite copying are provided.
7 is provided via a paper transport path 35.

As shown in FIG. 7, the above-described electrophotographic apparatus has a master CPU 40 also serving as a control device for the electrostatic latent image forming means, and a slave CPU 41 for controlling the optical system 2 and the like. It is controlled by a control system. The slave CPU 41 is a ROM
44, a rotary encoder (R) for detecting the rotation speed of the motor 18 according to a program stored in advance.
E) A signal from 45 and a signal from a home position sensor (not shown) are received, the rotation of the motor 18 is controlled via a driver 46, and the image is transferred to the registration roller 31 of FIG. A signal for instructing the paper supply timing is transmitted.

The master CPU 40 includes a charging unit 50, a copy lamp lighting circuit 43 for outputting a lamp voltage for setting the amount of light of the copy lamp 3, and a pickup sensor for automatic image quality compensation having a light emitting element 51 and a light receiving element 52. A certain toner amount detection sensor 54 is connected. Then, the toner amount detection sensor 54 detects a toner patch detection value from a toner patch formed on the photoconductor 21 in the measurement mode, and also detects a drum surface detection value from a drum surface of the photoconductor 21 on which no toner patch is formed. The master CPU 40 detects the A / A
Output to the D conversion port.

Further, the master CPU 40 has a ROM
42 and a RAM (not shown) are connected.
Reference numeral 42 denotes a slave CPU command routine for outputting an operation signal and the like to the slave CPU 41 based on signals from various key switches and sensors (not shown), and toner patches on the low density side and the high density side in the initial state. Initial state detection routine for detecting the detection value and the drum surface detection value, the ratio between the toner patch detection value and the drum surface detection value, and the toner patch detection value and the drum surface detection on the low density side and high density side before copying. Various programs such as a compensation control routine for performing automatic image quality compensation control based on the ratio with the value are written. In the RAM, a detection value storage area used when the initial state detection routine and the compensation control routine are executed is formed.

The operation of the electrophotographic apparatus having the above configuration will be described.

First, after the assembly at the factory is completed, the initial state detection routine shown in FIG.
The detected toner patch value and the detected drum surface value on the low density side and the high density side in the initial state are detected.

That is, when the initial state detection routine is executed, as shown in FIG. 10, energization of the light emitting element 51 is started at a predetermined voltage and current, and as shown in FIG. The light having the corresponding amount of light is emitted from the light emitting element 5.
1 to the photosensitive layer 21a located at the outermost periphery of the photosensitive member 21. The light applied to the photosensitive layer 21a is
The light receiving element 52 is reflected in two directions and receives the reflected light.
Outputs a sensor output M1 of a voltage corresponding to the amount of received light. The sensor output M1 is input to an A / D conversion port of the master CPU 40, as shown in FIG. 7, and is converted from an analog value to a digital drum surface detection value M1 by an A / D converter (not shown). After the conversion, it is stored in a detection value storage area of a RAM (not shown) via the master CPU 40 (S1).

Next, as shown in FIG.
The reflector 4 and the like are moved out of the image area of the tip portion, and a predetermined lamp voltage is applied to the copy lamp 3. The copy lamp 3 emits light in the direction of the standard white plate 53 with an amount of light corresponding to the applied lamp voltage.
Then, the photosensitive member 21 is exposed through the reflecting mirrors 4.5, 6.7 to form an electrostatic latent image on the photosensitive member 21. Then, the electrostatic latent image on the photoreceptor 21 becomes a low-density toner patch by attaching toner when the toner amount corresponding to the exposure amount passes through the developing unit 23 (S2).

When a low-density toner patch is created, as shown in FIG. 9, light of an amount corresponding to the above-described predetermined amount of current is transmitted from the light emitting element 51 to the toner patch 59 on the photosensitive member 21.
Is irradiated. The light applied to the toner patch 59 is reflected toward the light receiving element 52, and the light receiving element 52 that has received the reflected light outputs a sensor output M2 of a voltage corresponding to the amount of received light.
Is output. The sensor output M2 is input to the A / D conversion port of the master CPU 40, as shown in FIG. 7, and is converted from an analog value to a digital toner patch detection value M2. (S3).

Thereafter, the copy lamp 3 is turned off,
Alternatively, a high-density toner patch is created on the photoconductor 21 by reducing the lamp voltage (S4). Then, the sensor output M3 of the toner patch is detected by the light emitting element 51 and the light receiving element 52, converted into a digital toner patch detection value M3, and stored in the detection value storage area of the RAM (S5).

Next, when copying is performed by an electrophotographic apparatus, a compensation control routine shown in FIGS. 1 to 3 is executed prior to copying. When the compensation control routine is executed, as shown in FIG. 9, energization of the light emitting element 51 is started at a predetermined voltage and current, and light having a light amount corresponding to the amount of energization is exposed from the light emitting element 51. The photosensitive layer 21a of the body 21 is irradiated. The light receiving element 52 that has received the reflected light from the photosensitive layer 21a outputs a sensor output m1 of a voltage corresponding to the amount of received light, and this sensor output m1 is, as shown in FIG. Is converted into a digital drum surface detection value m1, and then stored in the detection value storage area of the RAM via the master CPU 40 (S11).

Next, as shown in FIG.
The reflector 4 and the like are moved out of the image area of the tip portion, and a predetermined lamp voltage is applied to the copy lamp 3. The light emitted by the copy lamp 3 with the light amount corresponding to the lamp voltage is reflected by the standard white plate 53 and then reflected by the reflecting mirrors 4.5,.
The photosensitive member 21 is exposed to light via the lines 6 and 7, an electrostatic latent image is formed on the photosensitive member 21, and a low-density toner patch is formed on the photosensitive member 21. Thereafter, as shown in FIG. 9, the sensor output m2 of this toner patch is detected by the light emitting element 51 and the light receiving element 52, and is converted into a digital toner patch detection value m2. It is stored (S12).

Next, the copy lamp 3 is turned off,
Alternatively, a high-density toner patch is formed on the photoconductor 21 by reducing the lamp voltage. Then, the sensor output m3 of the toner patch is detected by the light emitting element 51 and the light receiving element 52, is converted into a digital toner patch detection value m3, and is stored in the detection value storage area of the RAM (S13).

When the storage of the drum surface detection value m1 and the toner patch detection values m2 and m3 is completed, the ratio K between the toner patch detection value M2 and the drum surface detection value M1 stored in the initial state detection routine is stored. Is calculated (S14), and the ratio L between the toner patch detection value M3 and the drum surface detection value M1 is calculated (S1).
5). Subsequently, the ratio M between the toner patch detection value m2 and the drum surface detection value m1 stored in S12 and S13 is calculated (S16), and the ratio N between the toner patch detection value m3 and the drum surface detection value m1 is calculated. Is calculated (S1
7).

At this time, as shown in FIG.
1 and a toner amount detection sensor 5 including a light receiving element 52
4, the absolute output value changes due to contamination, deterioration, temperature change, etc., and the drum surface detection value m1 (sensor output m1) and the toner patch detection value m2 · m3 (sensor output m2 · m)
Even if 3) is lower than the drum surface detection value M1 (sensor output M1) and the toner patch detection values M2 and M3 (sensor outputs M2 and M3) in the initial state, the detection values of the detection values m1, m2, and m3 The ratios (change rates) of the change amounts K ₁ and K ₂ with respect to M 1, M 2 and M 3 are the same. Therefore, when only the output absolute value of the toner amount detection sensor 54 changes, as shown in FIG.
1 and the ratio K · L obtained from the toner patch detection values M2 · M3 and the ratio M · N obtained from the drum surface detection value m1 and the toner patch detection values m2 · m3 have the same value ΔI ₁ · ΔI ₂ , The difference between the ratio K · L and the ratio M · N occurs only when a factor other than the output absolute value such as the amount of exposure by the copy lamp 3 changes.

When the ratios K, L, M, and N are obtained by performing the above-described steps S14 to S17, it is determined whether or not the ratio K and the ratio M on the low concentration side are equal (S1).
8). If the two ratios K and M are not equal, N
S20 is executed as O, and it is determined whether or not the ratio K is larger than the ratio M (S20). If it is determined that the ratio K is larger, the lamp voltage of the copy lamp 3 is increased. As a result, the density of the toner patch is reduced (S22). On the other hand, when it is determined that the value is not a large value, the lamp voltage of the copy lamp 3 is reduced, so that the density of the toner patch is increased (S21).

When the density of the toner patch is changed by executing the above S21 or S22, the changed toner patch detection value m2 is detected by the toner amount detection sensor 54 and stored in the detection value storage area of the RAM ( S2
3) A ratio M between the toner patch detection value m2 and the drum surface detection value m1 is calculated (S24). After this, S1
8 is re-executed, and it is determined whether or not the ratio K is equal to the changed ratio M (S18). By repeatedly executing S18 and S20 to S24 until both ratios KM become equal. The lamp voltage of the copy lamp 3 on the low density side is set to a value that matches the density in the initial state.

Next, in S18, when it is determined that the ratios KM are equal, S19 is executed as YES, and it is determined whether or not the ratios LN on the high concentration side are equal (S19). If the two ratios L and N are not equal, S25 is executed as NO, and it is determined whether or not the ratio L is greater than the ratio N (S2).
5). If the ratio L is determined to be larger than the ratio N, the lamp voltage of the copy lamp 3 is increased to lower the density of the toner patch (S
27) If it is determined that the value is not a large value, the lamp voltage of the copy lamp 3 is decreased to increase the density of the toner patch (S26).

Thereafter, the changed toner patch detection value m3 is detected by the toner amount detection sensor
The detected value is stored in the detected value storage area of M (S28), and the ratio N between the detected toner patch value m3 and the detected drum surface value m1 is calculated (S29). And S19 is executed again,
Until both the ratios L · N become equal, S19 and S25-
By repeatedly executing 29, the lamp voltage of the copy lamp 3 on the high density side is set to a value that matches the density in the initial state.

When the lamp voltage is set to the optimum value by the above automatic image quality compensation control, a copy mode is subsequently executed, and as shown in FIG. Charged to a predetermined potential by 22. Then, by moving the optical system mounting table on which the optical system 2 is installed in the direction A, the original (not shown) covered by the original cover 26 is sequentially illuminated from the leading end by the copy lamp 3 from the leading end. The reflected light is transmitted through the optical system 2 to the photosensitive member 21.
And an electrostatic latent image is formed on the photoconductor 21.

When copying is performed using the automatic document feeder 27 disposed above the copying machine main body 1, the drums 29a and 29b and the like are used in the document feed path 28 of the automatic document feeder 27. While the original is being conveyed, the original is sequentially irradiated from the leading end by the copy lamp 3 through slits (not shown) provided at two places of the original conveying path 28, and the reflected light from the original is irradiated with the photosensitive member 2 in the same manner as described above.
Exposure to 1.

When an electrostatic latent image is formed on the photosensitive member 21,
Subsequently, the electrostatic latent image is developed with the toner supplied from the developing unit 23 to form a toner image. Thereafter, transfer paper (not shown) is fed to the registration roller 31 from a paper supply unit 30 provided with a plurality of paper supply cassettes and the like, and is temporarily stopped by the registration roller 31 as necessary. Supplied to

The toner image on the photosensitive member 21 is transferred onto the supplied transfer paper by the transfer unit 24. Thereafter, the transfer paper is peeled off from the photoreceptor 21 and is conveyed to the fixing unit 33 by the conveyance device 32, where the toner image is fixed on the transfer paper.
Is discharged. On the other hand, in the case of the composite copy and the duplex copy, the transfer paper discharged from the fixing unit 33 is transferred to the paper transport path 35.
To the intermediate tray 36 for composite copying.
On the other hand, in the case of double-sided copying, the sheet is inverted and then discharged to the intermediate tray 36 by the reversing unit 37.
Then, after a plurality of transfer papers are accumulated in the intermediate tray 36, the transfer papers on the intermediate tray 36 are sequentially fed from the uppermost one by the feed roller 38 and sent to the photoconductor 21,
Copying is subsequently performed.

As described above, the electrophotographic apparatus of this embodiment is
Automatic image quality compensation control is performed based on the ratio KLNM between the toner patch detection values M2, M3, m2, m3 and the drum surface detection values M1, m1.
M · N is not affected by changes in the absolute output value of the toner amount detection sensor 54. Therefore, the electrophotographic apparatus can obtain the toner patch detection values M2, M3, m2, m3 and the drum bare surface detection values M1, m1 with a single toner amount detection sensor 54, thereby simplifying the structure and reducing the cost. Has become possible.

In this embodiment, the detected toner patch values M2, M3, m2 on the low density side and the high density side are used.
· Ratio KL between m3 and drum surface detection value M1 · m1
Although the automatic image quality compensation control is performed based on M · N, the control method is not limited to this. That is, when the automatic image quality compensation control is performed with the low density side ratio K · M, the effect on image fog is high, and the high density side ratio L
When the automatic image quality compensation control is performed with N, the effect of reducing the density is high. Therefore, depending on the purpose of use, the ratio K / L / M / N of one of the low density side and the high density side
Thus, the automatic image quality compensation control may be performed.

Further, in the present embodiment, the drum surface detection value M1 · m1 is obtained from an arbitrary point on the photosensitive member 21. However, the present invention is not limited to this, and as shown in FIG. Alternatively, the drum surface detection values M1 · m1 obtained from the entire circumference of the photoconductor 21 may be averaged.

That is, when obtaining the drum surface detection value M1 and the toner patch detection values M2 and M3 in the initial state, an initial state detection routine shown in FIG. 5 is executed. And
For example, assuming that the time required for the drum of the photoconductor 21 to make one revolution is t (s) and the number of times of data acquisition is x (times),
At each t / x (s), the drum surface detection values M1 at a plurality of locations of the photoconductor 21 are taken in by the toner amount detection sensor 54 (S31), and the total number of obtained drum surface detection values M1 is taken as x. By dividing by
The drum surface detection value M1 is averaged (S32). Then, S2 to S5 of the initial state detection routine shown in FIG.
1 and toner patch detection values M2 and M3.

Thereafter, a compensation control routine shown in FIG. 6 is executed, and every t / x (s),
The drum surface detection values m1 at a plurality of locations of the photoconductor 21
(S33), and the obtained drum surface detection value m
By dividing the sum of 1 by the number of times x taken in, the drum surface detection value m1 is averaged (S3).
4). Thereafter, by executing S12 to S29 of the compensation control routine shown in FIGS. 1 to 3, the averaged drum surface detection value m1 and the averaged toner patch detection value m2 · m
3 and the toner patch detection values M2, M3, m2, m
Automatic image quality compensation control is performed on the basis of the ratio K.L.M.N of 3 and the averaged drum surface detection value M1.m1.

Thus, when the averaged drum surface detection value M1 · m1 is used, as shown in FIG. 13, the sensor output of the toner amount detection sensor 54 is caused by, for example, the eccentricity of the photoconductor 21 or uneven rotation. Even when the variation is caused by the drum position, the drum surface detection value M1 · m
By averaging 1, it is possible to perform stable automatic image quality compensation control.

Embodiment 2 Another embodiment of the present invention will be described below with reference to FIGS. The same components as those described in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The electrophotographic apparatus according to this embodiment is similar to the apparatus shown in FIG.
As shown in FIG. 17 and FIG.
A drum position detecting sensor (photosensitive member position detecting means) 57 connected to the master CPU 40 is also provided. The toner amount detection sensor 54 and the drum position detection sensor 57 disposed near the toner amount detection sensor 54
Has light emitting elements 51 and 55 and light receiving elements 52 and 56, and as shown in FIG.
Is connected to the master CPU 4 via NOT circuits 58, 58 and the like.
0, which is connected to the output terminal, and is turned on and off by the master CPU 40. Also,
The light receiving element 52 of the toner amount detection sensor 54 is connected to an input terminal of an A / D conversion port of the master CPU 40,
The sensor output is proportional to the amount of received light, and the light receiving element 56 of the drum position detection sensor 57 is
It is connected to the input terminal of the master CPU 40.

The toner amount detection sensor 54 and the drum position detection sensor 57 are, as shown in FIG.
As shown in FIG. 19, one of the toner amount detection sensors 54 is disposed close to the photoconductor 21.
Is provided so as to obtain a sensor output of a portion of the photosensitive layer 21a where the toner patch 59 is formed. The other drum position detection sensor 57 is
Position marking formed on the non-photosensitive layer 21b
(Marking) It is provided at a position where 60 is detected.
The master CPU 4 to which the toner amount detection sensor 54 and the drum position detection sensor 57 are connected.
In the case of 0, the automatic image quality compensation control is performed by the fixed position initial state detection routine shown in FIG. 15 and the fixed position compensation control routine shown in FIG. Other configurations are the same as those of the first embodiment.

The operation of the electrophotographic apparatus having the above configuration will be described.

First, after assembly at the factory is completed, FIG.
By executing the fixed-position initial state detection routine shown in (1), the low density and high density toner patch detection values and the drum surface detection values in the initial state are detected.

That is, when the home position initial state detection routine is executed, light is emitted from the light emitting element 55 of the drum position detection sensor 57 to the photosensitive member 21 as shown in FIG.
The light reflected from the photoconductor 21 is received by the light receiving element 56. The amount of light received by the light receiving element 56 sharply decreases (OFF state) when the reflected light from the drum position marking 60 formed on the photoconductor 21 is received.
The ON / OFF signal from the light receiving element 56 is input to 40. Therefore, the master CPU 40
By monitoring the ON-OFF signal input from the CPU, the marking position indicated by the drum position marking 60 is detected (S41).

When the marking position is detected, the portion of the toner patch 59 formed immediately after the detection is set as a predetermined position,
The state of the drum surface of the photoconductor 21 at this predetermined position is detected by the toner amount detection sensor 54 as a sensor output M1. The sensor output M1 is input to an A / D conversion port of the master CPU 40 as shown in FIG. 16 and is converted from an analog value to a digital drum surface detection value M1 by an A / D converter. It is stored in a detection value storage area of a RAM (not shown) via the master CPU 40 (S42).

When the storage of the drum surface detection value M1 is completed, the marking position is detected again by the drum position marking 60 and the drum position detection sensor 57 (S43). Then, after a low-density toner patch is formed at a predetermined position on the photoconductor 21, the state of the toner patch is detected by the toner amount detection sensor 54, and is stored in the detection value storage area of the RAM as a toner patch detection value M2. (S44). Further, the marking position is detected by the drum position marking 60 and the drum position detection sensor 57 (S45). After a high density toner patch is formed at a predetermined position on the photoconductor 21, the state of the toner patch is determined by a toner amount detection sensor. 54, and stored in the detection value storage area of the RAM as the toner patch detection value M3 (S46).

Next, when copying is performed by the electrophotographic apparatus, a fixed position compensation control routine shown in FIG. 14 is executed prior to copying. That is, when the compensation control routine is executed, as shown in FIG. 18, after the marking position is detected (S51), the same position as the predetermined position of the photoconductor 21 specified by the above-described fixed position initial state detection routine is detected. The drum surface detection value m1 at the predetermined position is stored (S5).
2). Thereafter, similarly, the detection of the marking position (S5)
3), low density toner patch detection value m at a predetermined position
2 (S54), detection of the marking position (S5)
5), high-density toner patch detection value m at a predetermined position
3 is stored (S56), and then the compensation control routine (S14 and S2) shown in FIGS.
The lamp voltage is adjusted by the same operation as in 9) (S)
57). The subsequent operation is the same as the operation described in the first embodiment.

As described above, the electrophotographic apparatus of this embodiment is
Automatic image quality compensation control is performed based on the ratio between the detected toner patch values M2, M3, m2, m3 and the drum surface detection values M1, m1, and the toner patch detection value M2, Since M3 · m2 · m3 and the drum surface detection value M1 · m1 can be obtained,
The structure can be simplified and the cost can be reduced.

The electrophotographic apparatus according to the present embodiment includes a drum position marking 60 and a drum position detecting sensor 57.
Thus, a specific position of the photoconductor 21 is set as a predetermined position, and the toner patch detection value M obtained from the predetermined position is set.
Automatic image quality compensation control is performed based on the ratio of 2.M3.m2.m3 to the drum surface detection value M1.m1. Therefore, as shown in FIG. 20, even when the sensor output of the toner amount detection sensor 54 fluctuates due to, for example, eccentricity or rotation unevenness of the photoconductor 21, this electrophotographic apparatus can operate at points a and b, for example. , C, etc., it is possible to perform stable automatic image quality compensation control by specifying a predetermined position.

Embodiment 3 FIGS. 21 to 25 show still another embodiment of the present invention.
This will be described below. The same components as those described in the second embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the electrophotographic apparatus according to the present embodiment, the drum position detecting sensor 57 connected to the master CPU 40 together with the toner amount detecting sensor 54 is arranged as shown in FIG. And a configuration arranged above the developing unit 23. The master CPU (reading means) 40 to which the toner amount detection sensor 54 and the drum position detection sensor 57 are connected is connected to the reference position initial state detection routine shown in FIG. The automatic image quality compensation control is performed by a reference position compensation control routine shown in FIG.
Is connected to a clock, a timer, a counter (not shown), and the like used when executing the above-described routines. Other configurations are the same as those of the second embodiment.

The operation of the electrophotographic apparatus having the above configuration will be described.

First, after the assembly at the factory is completed, FIG.
By executing the reference position initial state detection routine shown in (1), the toner patch detection value in the initial state and the drum bare surface detection value for one rotation of the drum of the photoconductor 21 are detected.

That is, when the reference position initial state detection routine is executed, the photosensitive member 21 is rotated (S61), and when the drum position detection sensor 57 is turned on (S62), the light emitting element 55 of the drum position detection sensor 57 is turned on. From photoreceptor 21
Is irradiated to the light receiving element 5
6 to receive light. The amount of light received by the light receiving element 56 sharply decreases (OFF state) when the reflected light from the drum position marking 60 formed on the photoconductor 21 is received.
-OFF signal is input. Therefore, the master CPU 4
0 detects the marking position indicated by the drum position marking 60 by monitoring the ON-OFF signal input from the light receiving element 56 (S63).

When the marking position is detected, the master C
The counter or the like connected to the PU 40 operates (S6).
4) The marking position is set as a reference position (predetermined position), and the state of the drum bare surface for one rotation of the drum of the photoconductor 21 from this reference position is detected by the toner amount detection sensor 54 as a sensor output M1. The sensor output M1 is input to an A / D conversion port of the master CPU 40, is converted from an analog value to a digital drum surface detection value M1 by an A / D converter, and is not shown via the master CPU 40. It is stored in the detection value storage area of the RAM (storage means) (S65). At this time, the drum surface detection value M1 for one rotation of the drum is stored in the RAM corresponding to the count number of the counter operated in S64.
Is stored in the detected value storage area.

When the storage of the drum surface detection value M1 is completed, the counter is reset, and a toner patch is formed at an arbitrary position on the photosensitive member 21 (S66). After that, the state of the toner patch is detected by the toner amount detection sensor 5.
4 and a toner patch detection value M2 of R
It is stored in the detected value storage area of the AM (S67). Further, the reference position is detected by the drum position marking 60 and the drum position detection sensor 57, and the number of counts from this reference position to the toner patch formed in S66 is counted by the counter, so that the formation position of the toner patch is determined. It is detected (S68).

Then, the master CPU 40
A drum surface detection value corresponding to the count number counted in S68 is read from the drum surface detection value M1 for one rotation of the drum stored in the detection value storage area of M, and this value is used as the toner patch formation position. Is stored in the detection value storage area of the RAM as the drum surface detection value M1a (S
69).

Next, when copying is performed by an electrophotographic apparatus, a reference position compensation control routine shown in FIGS. 21 and 22 is executed prior to copying. That is, when the compensation control routine is executed, the photoconductor 21 is rotated (S71),
The drum position detection sensor 57 is turned on (S72).

Then, after the marking position is detected (S73), a counter or the like connected to the master CPU 40 is operated (S74), and the marking position is set as a reference position. The state of the drum surface in the circumference is detected as the sensor output m1. Then, the sensor output m1 is converted into a digital drum surface detection value m1, and then stored in the detection value storage area of the RAM via the master CPU 40 (S75). At this time, the drum surface detection value m1 for one rotation of the drum is stored in the detection value storage area of the RAM in correspondence with the count number of the counter operated in S74.

When the storage of the drum surface detection value m1 is completed, the counter is reset, and a toner patch is formed at an arbitrary position on the photosensitive member 21 (S76). After that, the state of the toner patch is detected by the toner amount detection sensor 5.
4 and R as a toner patch detection value m2.
It is stored in the detected value storage area of the AM (S77). Further, the reference position is detected by the drum position marking 60 and the drum position detection sensor 57, and the number of counts from this reference position to the toner patch formed in S76 is counted by the counter, so that the formation position of the toner patch is determined. It is detected (S78).

Then, the master CPU 40
A drum surface detection value corresponding to the count number counted in S78 is read from the drum surface detection value m1 for one rotation of the drum stored in the detection value storage area of M, and this value is used as the toner patch formation position. Is stored in the detection value storage area of the RAM as the drum surface detection value m1a at (S
79).

When the storage of the toner patch detection value m2 and the drum surface detection value m1a is completed, the ratio K between the toner patch detection value M2 and the drum surface detection value M1a stored by the above-described initial state detection routine is calculated. (S80), and the ratio M between the toner patch detection value m2 and the drum surface detection value m1a is calculated (S8).
1). Next, it is determined whether or not the ratio K and the ratio M are equal to adjust the lamp voltage (S82). If the two ratios K and M are not equal, NO is determined as S
83 is executed to determine whether or not the ratio K is greater than the ratio M (S83). If the ratio K is determined to be greater, the lamp voltage of the copy lamp 3 is increased. The density of the toner patch is reduced (S8
5). On the other hand, if it is determined that the value is not a large value, the lamp voltage of the copy lamp 3 is reduced to increase the density of the toner patch (S84).

When the density of the toner patch is changed by the execution of S84 or S85, the counter is reset, and the toner patch is formed again at an arbitrary position on the photosensitive member 21. Then, the state of the toner patch is detected by the toner amount detection sensor 54, and is stored in the detection value storage area of the RAM as the changed toner patch detection value m2 (S86). Further, the formation position of the toner patch is detected (S87), and the drum surface detection corresponding to the count number counted in S87 from the drum surface detection value m1 for one rotation of the drum stored in the detection value storage area of the RAM. The value is read, and this value is stored in the detection value storage area of the RAM as the drum surface detection value m1a at the toner patch formation position (S88). Next, a ratio M between the toner patch detection value m2 and the drum bare surface detection value m1 is calculated (S89).

Thereafter, S82 is executed again, and it is determined whether or not the ratio K is equal to the changed ratio M (S82).
Until the two ratios K · M become equal, S82 to S89 are repeatedly executed, so that the lamp voltage of the copy lamp 3 is set to a value that matches the density in the initial state.

As described above, the electrophotographic apparatus of this embodiment is
A drum surface detection value M1 · m1 for one rotation of the drum is stored in a detection value storage area of a RAM (not shown), and a toner patch detection value M2 · m2 and a drum surface detection value M1a · m1a corresponding to a toner patch formation position are stored. The automatic image quality compensation control is performed based on the ratio. Accordingly, the toner patch detection value M2 · m2 is detected by the single toner amount detection sensor 54.
In addition, since the drum surface detection value M1 · m1 can be obtained, the structure can be simplified and the cost can be reduced.

Further, in the electrophotographic apparatus of this embodiment, the toner patch detection value M 2 · m 2 obtained at an arbitrary position on the photosensitive member 21 by the drum position marking 60, the drum position detection sensor 57, a counter (not shown), and the like. , Drum surface detection value M1 corresponding to the toner patch formation position
The automatic image quality compensation control is performed on the basis of the ratio of a.m1a. Therefore, this electrophotographic apparatus is similar to that of FIG.
As shown in FIG. 5, even when the sensor output of the toner amount detection sensor 54 fluctuates due to, for example, eccentricity or rotation unevenness of the photoconductor 21, the toner patch detection value M2 at any point a or b may be detected. M2 and drum surface detection value M
By making the ratios K · M to 1a · m1a equal, stable automatic image quality compensation control can be performed.

Embodiment 4 FIGS. 26 to 29 show still another embodiment of the present invention.
This will be described below. Note that the same components as those described in the third embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The electrophotographic apparatus according to the present embodiment is different from the electrophotographic apparatus described in the third embodiment in that the reference position initial state shown in FIG. In the detection routine, correction for unevenness in the formation of the toner image caused by unevenness in the formation of the photosensitive layer 21a of the photosensitive member 21 is performed. That is, in the reference position initial state detection routine, the state of the toner patch is detected, and the state of the reference toner patch (hereinafter, referred to as a halftone patch) formed at a predetermined density over the entire circumference of the drum of the photoconductor 21 is also determined. The amount is detected by the amount detection sensor 54. The halftone patch is created by controlling the lamp voltage of the copy lamp 3, for example. Other configurations are the same as those of the third embodiment.

The operation of the electrophotographic apparatus having the above configuration will be described.

First, after the assembly at the factory is completed, FIG.
By executing the reference position initial state detection routine shown in (1), the toner patch detection value in the initial state, the halftone patch detection value for one rotation of the drum of the photoconductor 21 and the drum surface detection value are detected.

That is, when the reference position initial state detection routine is executed, the same operation as that of the initial state detection routine shown in the third embodiment is performed, and the state of the drum surface for one rotation of the drum is changed to the drum surface detection value. M1 is stored in a detection value storage area of a RAM (not shown) (S61 to S6).
5).

When the storage of the drum surface detection value M1 is completed, the counter is reset, and a halftone patch is formed at a predetermined density over the entire circumference of the drum of the photosensitive member 21 (S91). After the marking position is detected (S92), a counter or the like connected to the master CPU (reading means) 40 is operated (S93), and the marking position is set as a reference position (predetermined position). The state of the halftone patch for one rotation of the drum of the photoconductor 21 is detected by the toner amount detection sensor 54 as a sensor output H1. The sensor output H1 is input to an A / D conversion port of the master CPU 40, and is converted from an analog value to a digital halftone patch detection value H1 by an A / D converter. Not RAM (storage means)
(S94). At this time, the halftone patch detection value H1 for one rotation of the drum is set to S93.
RA corresponding to the count number of the counter operated by
It is stored in the M detection value storage area.

When the storage of the halftone patch detection value H1 is completed, the counter is reset and a toner patch is formed at an arbitrary position on the photosensitive member 21 (S6).
6). The subsequent operations shown in S67 to S69 are the same as the operations in the initial state detection routine shown in the third embodiment.
Then, the halftone patch detection value corresponding to the count number counted in S68 is read from the halftone patch detection value H1 for one rotation of the drum stored in the detection value storage area of the RAM by the master CPU 40,
This value is stored in the detection value storage area of the RAM as the halftone patch detection value H1a at the toner patch formation position (S95). Further, the halftone patch detection value at the above-described reference position is read by the master CPU 40, and this value is used as a halftone patch reference value H1o as a reference value for calculating a change rate of the halftone patch described later. Is stored in the detected value storage area (S
96).

Next, when copying is performed by the electrophotographic apparatus, a reference position compensation control routine shown in FIGS. 26 and 27 is executed prior to copying. That is, when the compensation control routine is executed, the same operation as that of the compensation control routine described in the third embodiment is performed, and the operation corresponds to the count number counted in S78 from the drum surface detection value m1 for one rotation of the drum. The drum surface detection value to be read is called, and this value is stored in the detection value storage area of the RAM as the drum surface detection value m1a (S71 to S79).

Then, the master CPU 40
The halftone patch detection value corresponding to the count number counted in S78 is read from the halftone patch detection value H1 for one rotation of the drum stored in the detection value storage area of M, and this value is used as the toner patch value. The halftone patch detection value H1b at the formation position is stored in the detection value storage area of the RAM (S101).

The above-described toner patch detection value m2, drum surface detection value m1a, and halftone patch detection value H1b
Is completed, the ratio K between the toner patch detection value M2 and the drum surface detection value M1a stored by the above-described initial state detection routine is calculated (S102). Further, the toner patch detection value m2 and the drum surface detection are calculated. Value m1
The ratio M to a is calculated (S103). The above ratio K
M (calculated value) is a ratio (M2 / M1a) between the toner patch detection value M2 · m2 and the drum surface detection value M1a · m1a.
And m2 / m1a), the halftone patch detection values H1a and H1 for correcting the unevenness of toner image formation
b divided by the halftone patch reference value H1o, the change rate of the halftone patch (correction value, H1a / H1
o and H1b / H1o). As described above, by multiplying the ratio between the toner patch detection value M2 · m2 and the drum surface detection value M1a · m1a by the change rate of the halftone patch, more stable automatic image quality compensation control can be performed. .

Next, in order to adjust the lamp voltage, the same operation as in the compensation control routine shown in the third embodiment is performed, and the density of the toner patch is changed (S82 to S82).
85), the counter is reset, and the toner patch is formed again at an arbitrary position on the photoconductor 21. Then, the state of the toner patch is stored in the detection value storage area of the RAM as the changed toner patch detection value m2 (S8).
6). Further, the formation position of the toner patch is detected (S
87), a drum surface detection value corresponding to the count number counted in S87 is read from the drum surface detection value m1 for one rotation of the drum stored in the detection value storage area of the RAM, and this value is used as a toner patch. Is stored in the detection value storage area of the RAM as the drum surface detection value m1a at the formation position (S88).

Further, the halftone patch detection value H1 for one rotation of the drum stored in the detection value storage area of the RAM.
The halftone patch detection value corresponding to the count number counted in S87 is read out, and this value is used as the halftone patch detection value H at the toner patch formation position.
1b is stored in the detection value storage area of the RAM (S1
04). Next, a ratio M between the toner patch detection value m2 and the drum bare surface detection value m1a is calculated (S10).
5).

Thereafter, S82 is executed again to determine whether the ratio K is equal to the changed ratio M (S82).
S82-88, S10 until both ratios KM become equal.
By repeatedly executing steps 4 and 105, the lamp voltage of the copy lamp 3 is set to a value that matches the density in the initial state.

As described above, the electrophotographic apparatus of this embodiment is
A drum surface detection value M1 · m1 and a halftone patch detection value H1 for one rotation of the drum are stored in a detection value storage area of a RAM (not shown), and a toner patch detection value M2 · m2 is obtained.
Drum bare surface detection value M corresponding to toner patch formation position
Automatic image quality compensation control is performed based on a value calculated by multiplying the ratio of 1a · m1a by the change rate (correction value) of the halftone patch. Accordingly, the toner patch detection value M2 · m2, drum surface detection value M1 · m1, and halftone patch detection value H1 can be obtained by the single toner amount detection sensor 54, so that the structure can be simplified and the cost can be reduced. It has become.

Further, in the electrophotographic apparatus of this embodiment, the toner patch detection value M2 · m2 obtained at an arbitrary position on the photoconductor 21 by the drum position marking 60, the drum position detection sensor 57, a counter (not shown), and the like. , Drum surface detection value M1 corresponding to the toner patch formation position
The automatic image quality compensation control is performed based on a calculated value obtained by multiplying the ratio of a · m1a by the change rate (correction value) of the halftone patch. Therefore, in this electrophotographic apparatus, as shown in FIG. 29, the sensor output of the toner amount detection sensor 54 is fluctuated due to, for example, eccentricity or uneven rotation of the photosensitive member 21 or uneven formation of the photosensitive layer 21a of the photosensitive member 21. , For example, any a
More stable automatic image quality compensation by equalizing the ratio K · M calculated from the toner patch detection values M2 · m2, the drum surface detection values M1a · m1a, and the halftone patch detection values H1a · H1b at points b and b. It is possible to perform control.

[0092]

[Effect of the Invention] electrophotographic apparatus of the invention of claim 1, as described above, the markings provided on the photosensitive member is detected by the photosensitive member position detection means, based on the detection result, the
The same position of the photoconductor is determined as a predetermined position to be a sensor detection position and a toner patch formation position on the photoconductor, and a sensor output of a drum bare surface at the predetermined position of the photoconductor, The automatic image quality compensation control is performed by maintaining the ratio of the toner patch formed at the predetermined position to the sensor output at a predetermined value.

Thus, even when the sensor output is obtained by a single pickup sensor for automatic image quality compensation,
Since the automatic image quality compensation control can be performed accurately, there is an effect that the structure can be simplified and the cost can be reduced.

Further, the predetermined position of the photoconductor is specified by detecting the marking formed on the photoconductor by the photoconductor position detecting means, and based on the ratio of the sensor output obtained from the same predetermined position. Automatic image quality compensation control is performed, so even if the sensor output of the automatic image quality compensation pickup sensor fluctuates due to, for example, eccentricity or uneven rotation of the photoconductor, stable automatic image quality compensation control can be performed. It has the effect of coming out.

The electrophotographic apparatus according to the second aspect of the present invention
As described above, the marking formed on the photoconductor and the
Photoconductor position detecting means for detecting the marking,
Storage means for storing a sensor output of the drum sober one round of the photosensitive member which starting from the predetermined position of the photosensitive member is determined based on the marking positions, the formation position of the toner patch formed on the photoreceptor , Based on the predetermined position
Reading means for detecting the sensor output of the drum surface corresponding to the formation position from the storage means , and detecting the sensor output of the toner patch formed at an arbitrary position of the photoconductor and corresponding to the formation position of the toner patch. In this configuration, the automatic image quality compensation control is performed by maintaining a ratio of the sensor output of the drum surface to a predetermined value to a predetermined value .

Thus, similar to the first aspect, the structure can be simplified.
The effect is that simplification and cost reduction are possible.
You. Furthermore, since automatic image quality compensation control is performed based on the ratio of the sensor output obtained from an arbitrary position of the photoconductor,
In addition to preventing local fatigue of the drum surface of the photoconductor, stable automatic image quality compensation control is performed even when the sensor output of the automatic image quality pickup sensor is fluctuated due to, for example, eccentricity or rotation unevenness of the photoconductor. The effect is that it is possible.

Further, the electrophotographic apparatus according to the third aspect of the present invention
As described above, the sensor output for one rotation of the drum surface of the photoconductor starting from the predetermined position of the photoconductor and the photoconductor starting from the predetermined position of the reference toner patch formed on the photoconductor at a predetermined density Storage means for storing the sensor output of one rotation of the drum, and reading out the sensor output of the drum surface and the sensor output of the reference toner patch corresponding to the formation position of the toner patch formed on the photoconductor from the storage means. Means for detecting the ratio of the sensor output of the toner patch formed at an arbitrary position on the photosensitive member to the sensor output of the drum bare surface corresponding to the toner patch forming position, the reference toner corresponding to the toner patch forming position. automatic image quality compensation control is performed by maintaining the calculated value calculated by multiplying the correction values calculated from the sensor output of the patch to a predetermined value It is formed.

Thus , similar to the first aspect, the structure can be simplified.
The effect is that simplification and cost reduction are possible.
You. Further, a sensor output for one round of the drum surface of the photoconductor starting from a predetermined position of the photoconductor and a drum 1 of the photoconductor starting from the predetermined position of a reference toner patch formed at a predetermined density on the photoconductor. Storage means for storing the sensor output for the circumference, based on a calculation value calculated by multiplying a ratio of the sensor output obtained from an arbitrary position of the photoconductor by a correction value calculated from the sensor output of the reference toner patch. The automatic image quality compensation control is performed to prevent local fatigue and the like of the drum surface of the photoconductor, and to provide a pickup sensor for automatic image quality compensation due to, for example, eccentricity and rotation unevenness of the photoconductor or uneven formation of the photosensitive layer of the photoconductor In this case, the automatic image quality compensation control can be performed more stably even when the sensor output has a fluctuation.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a part of a compensation control routine in an electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a part of a compensation control routine.

FIG. 3 is a flowchart showing a part of a compensation control routine.

FIG. 4 is a flowchart of an initial state detection routine.

FIG. 5 is a flowchart of an initial state detection routine for performing an averaging process.

FIG. 6 is a flowchart of a compensation control routine for performing an averaging process.

FIG. 7 is a block diagram of an electrophotographic apparatus.

FIG. 8 is a schematic configuration diagram of an electrophotographic apparatus.

FIG. 9 is an explanatory diagram illustrating a state of a toner amount detection sensor.

FIG. 10 is a circuit diagram of a toner amount detection sensor.

FIG. 11 is a graph showing the relationship between sensor output and reflectance.

FIG. 12 is a graph showing a relationship between a change rate and a reflectance.

FIG. 13 is a graph showing a relationship between a drum position of a photoconductor and a sensor output.

FIG. 14 is a flowchart of a home position compensation control routine.

FIG. 15 is a flowchart of a home position initial state detection routine.

FIG. 16 is a block diagram of an electrophotographic apparatus.

FIG. 17 is a schematic configuration diagram of an electrophotographic apparatus.

FIG. 18 is a circuit diagram of a toner amount detection sensor and a drum position detection sensor.

FIG. 19 is an explanatory diagram illustrating a state of a photoconductor.

FIG. 20 is an explanatory diagram illustrating a relationship between a drum position of a photoconductor and a sensor output.

FIG. 21 is a flowchart showing a part of a reference position compensation control routine.

FIG. 22 is a flowchart showing a part of a reference position compensation control routine.

FIG. 23 is a flowchart of a reference position initial state detection routine.

FIG. 24 is a schematic configuration diagram of an electrophotographic apparatus.

FIG. 25 is an explanatory diagram illustrating a relationship between a drum position of a photoconductor and a sensor output.

FIG. 26 is a flowchart showing a part of a reference position compensation control routine.

FIG. 27 is a flowchart showing a part of a reference position compensation control routine.

FIG. 28 is a flowchart of a reference position initial state detection routine.

FIG. 29 is an explanatory diagram showing a relationship between a drum position of a photoconductor and a sensor output.

FIG. 30 is a graph showing a relationship between sensor output and reflectance in a conventional electrophotographic apparatus.

[Explanation of symbols]

Reference Signs List 21 photoconductor 40 master CPU (reading means) 41 slave CPU 43 copy lamp lighting circuit 44 ROM 51 light emitting element 52 light receiving element 53 standard white plate 54 toner amount detection sensor (pickup sensor for automatic image quality compensation) 55 light emitting element 56 light receiving element 57 drum Position detection sensor (photoconductor position detection
58 ) NOT circuit 59 Toner patch 60 Drum position marking (marking)

Continuation of the front page (72) Inventor Jun Morimoto 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-63-261374 (JP, A) JP-A-4-42181 (JP) , A) JP-A-4-97184 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/00 303 G03G 15/08 115

Claims (3)

(57) [Claims] 1. An electrophotographic apparatus for performing automatic image quality compensation control for maintaining the density of a copied image at a predetermined value by an automatic image quality compensation pickup sensor that outputs a sensor output corresponding to the toner amount of a toner patch formed on a photoconductor. In the above, a marking provided on the photoconductor is detected by a photoconductor position detecting means, and based on a detection result, the same position of the photoconductor becomes a sensor detection position on the photoconductor and a formation position of a toner patch. and determines as the position, the automatic image quality compensation control, the photosensitive member and the sensor output of the drum sober at the predetermined position of a predetermined value the ratio of the sensor output of the toner patches formed on the predetermined position of the photosensitive member An electrophotographic apparatus characterized in that the electrophotographic apparatus is carried out by maintaining the temperature. 2. An electrophotographic apparatus for performing automatic image quality compensation control for maintaining the density of a copied image at a predetermined value by an automatic image quality compensation pickup sensor that outputs a sensor output corresponding to the toner amount of a toner patch formed on a photosensitive member. , A marking formed on the photoconductor, a photoconductor position detecting means for detecting the marking, and a drum surface of the photoconductor starting from a predetermined position of the photoconductor determined based on the detected marking position A storage unit for storing a sensor output for one rotation; detecting a formation position of a toner patch formed on the photoconductor with reference to the predetermined position; and detecting a sensor output of a drum surface corresponding to the formation position. Reading means for reading out from the storage means, wherein the automatic image quality compensation control comprises the steps of: And Sir output, an electrophotographic apparatus which comprises carrying out by maintaining the ratio of the sensor output drum sober corresponding to the formation position of the toner patch at a predetermined value. 3. An electrophotographic apparatus for performing automatic image quality compensation control for maintaining the density of a copied image at a predetermined value by an automatic image quality compensation pickup sensor that outputs a sensor output corresponding to the toner amount of a toner patch formed on a photoconductor. A sensor output for one round of a drum surface of the photoconductor starting from a predetermined position of the photoconductor, and a drum of the photoconductor starting from the predetermined position of a reference toner patch formed at a predetermined density on the photoconductor. Storage means for storing sensor outputs for one round; reading means for reading from the storage means sensor outputs of the drum bare surface and reference toner patches corresponding to the formation positions of the toner patches formed on the photoreceptor; The automatic image quality compensation control comprises: a sensor output of a toner patch formed at an arbitrary position on the photoreceptor; Maintaining at a predetermined value a calculated value obtained by multiplying the ratio of the sensor output of the drum surface corresponding to the formation position to the correction value calculated from the sensor output of the reference toner patch corresponding to the formation position of the toner patch. An electrophotographic apparatus characterized by being performed by: