JPS62229164A - Image forming device - Google Patents

Abstract

PURPOSE:To always obtain an image having a desired picture quality by providing a means for controlling automatically the operating state of an image forming means in accordance with the detected value of a parameter, and a means for selecting manually whether an automatic control means is to be operated or not at the time of executing the image forming means. CONSTITUTION:The surface potential of a part of the surface of a drum 47 to which the light beam of a blank exposure lamp 70 is projected is measured as a bright part surface potential, and the surface potential of a part of the surface of the drum 47 to which the light beam of the blank exposure lamp is not projected is measured as a dark part surface potential. First of all, the value of the bright part potential and the dark part potential which can obtain a correct image contrast is set as a target value. The correction of a difference of the bright part potential and a correction of a difference of the dark part potential are executed by an AC electrifier and a primary electrifier, respectively, and whether the surface potential reaches the target value by a control of once or not is not known due to the variation of the atmosphere, deterioration of the electrifier, etc., therefore, when the device is in a prescribed state, the surface potential is measured plural times, and the control of an output of a corona discharge device is also executed by the same times as the measurement.

Description

[Detailed description of the invention] TECHNICAL FIELD The present invention relates to an image forming apparatus.

Conventionally, values of parameters related to image formation are detected 17 and the operating state of an image forming means is automatically controlled according to the detected values. However, in the automatic control mode, there were cases in which a desired image could not be obtained.

SUMMARY OF THE INVENTION In view of the above points, it is an object of the present invention to provide an image forming apparatus that can easily obtain a desired image even when the desired image cannot be obtained using an automatically controlled mote.

That is, means for forming an image on a recording medium, means for detecting parameters related to the image quality of the image formed by the image forming means, and means for detecting parameters related to the image quality of the image formed by the image forming means, and a means for detecting parameters related to the image quality of the image to be formed in order to stabilize the image quality. An image forming apparatus comprising means for automatically controlling the operating state of the image forming means, and means for manually selecting whether or not to operate the automatic control means when the image forming means is executed. On offer.

This makes it possible to always obtain images of desired quality.

Hereinafter, a detailed explanation of the wooden invention will be given with reference to the drawings.
i This is a cross-sectional view 1 of a copying apparatus to which the present invention can be applied.

The surface of the dS drum 47 is made of a three-layer seamless photoconductor using a photoconductor, is rotatably supported on a shaft, and is operated by turning on the copy key. The motor 71 starts rotating in the direction of the arrow.

When the drum 47 rotates by a predetermined angle, the original placed on the original platen glass 54 is illuminated by the illumination lamp 46 which is integrated with the first scanning mirror 44, and the reflected light is transmitted to the first scanning mirror 44 and the first scanning mirror 44. It is scanned by a two-scanning mirror 53. By moving at the speed ratio of the first scanning mirror 44 and the second scanning mirror 53 Fix knee L, the original is scanned while the optical path length in front of the lens 52 is kept constant.

After passing through the lens 52 and the third mirror 55, the reflected light image is formed on the drum 47 at the exposure section.

The drum 47 includes a pre-exposure lamp 50 and a pre-AO charger 51a.
The static electricity is simultaneously removed by the charger 5 lb, and then the charge is corona charged (for example, +) by the charger 5 lb. Thereafter, the drum 47 is irradiated with an illumination lamp 46 at the exposure section, and the nine f-elements are exposed at the slit exposure section.

At the same time, ACXt'i- next and opposite polarity (for example -)
Corona static elimination is performed by a static eliminator 69, and the image is then developed with liquid by a developing roller 65 of a developing device 62 to be visualized as a toner image, and the toner image is transferred by a front transfer band W device 61.

The transfer paper in the upper cassette 10 or the lower cassette 11 is fed into the machine by a paper feed roller 59, and is transferred to the photosensitive drum 47 with accurate timing by a register roller 60.
The leading edge of the latent image and the leading edge of the paper can be aligned in the transfer section.

Next, while the transfer paper passes between the transfer charge B42 and the drum 47, the toner image on the drum 47 is transferred onto the transfer paper.

After the transfer is completed, the transfer paper is transferred to the drum 47 by the separation roller 43.
It is separated from the paper, sent to the conveying roller 41, placed between the hot plate 38 and the press rollers 40, 41, and fixed by pressure and heating. ] 7 and is discharged to the tray 34.

After the transfer, the drum 47 continues to rotate and its surface is cleaned by a cleaning device comprising a cleaning roller 48 and an elastic blade 49, and the process proceeds to the next cycle.

Here, the s-plane potential needle 67 for measuring the surface potential is located on the entire surface 14f.
, are mounted close to the surface of the drum 47 between the lamp 68 and the developing unit 62.

The ill! After turning on the switch, there is a step of pouring the developer onto the cleaning grate 49 while the drum 47 is stopped. Hereinafter, this will be referred to as pre-wetting. This flushes out the toner accumulated near the cleaning grade 49, and also flushes out the toner that has accumulated near the cleaning grade 49 and
This is to give 4 slips. Also, pre-wet time (4 seconds)
Rotate the rear drum 47 and remove the front exposure lamp 50 and front AO!
! There is a step of erasing the residual charge and memory of the drum 47 in the container 51a, etc., and cleaning/cleaning the surface of the drum with a cleaning roller 48 and a cleaning grate 49. Hereinafter, this will be referred to as pre-rotation lNTR. This is drum 4
This is to make the sensitivity of the lens 7 appropriate and to form an image on a clean surface. The pre-wet time and pre-rotation time (number) are automatically changed depending on various conditions (described later).

Further, as a cycle after completing the set number of copy cycles, there is a step of rotating the drum 47 several times to remove residual charges and memory from the paper drum using an AO@electric device 69 or the like, and cleaning the drum surface. Hereinafter, this will be referred to as post-rotation LSTIL. This is to leave the drum 47 electrostatically and physically clean.

FIG. 1 is a plan view of the vicinity of the blank exposure lamp 70 in FIG. 1. The blank exposure lamps 70-1 to 70-5 are
It is turned on when the drum is rotating and not during exposure to erase the charge on the drum surface and prevent excess toner from adhering to the drum. However, since the blank exposure lamp 70-1 illuminates the drum surface corresponding to the surface electrometer 67, it is turned off momentarily when the dark area potential is measured with the surface electrometer 67. Further, in B-size copying, the image area is smaller than A4 or A3 size, so the blank exposure lamp 70-5 is turned on for the non-image area even while the optical system is moving forward.

The lamp 70-0 is called a sharp cut 2y lamp, and has a drum part that is in contact with the separation guide plate 43-1.
Light is irradiated to completely erase the electric charge in the area, preventing toner from adhering to it, and preventing the gap from contaminating the width.

This sharp cut lamp is always on while the drum is rotating.

At each processing position in the copying process of such an electrophotographic copying device, bright areas (areas that reflect a lot of light) and dark areas (areas that reflect a lot of light) of the original are separated.
FIG. 2 shows how the surface potential of the photosensitive drum corresponding to K (portion with little light reflection) changes. What is necessary for the final electrostatic fa image is the surface potential at the zero point in the figure, but the surface potentials in the dark and bright areas there ■ Oit If the ambient temperature of the photosensitive drum 47 increases, O', and also due to aging of the photosensitive drum 47, it changes as shown in Figure 4 (■'@'), and contrast between dark and bright areas cannot be obtained.

A method for compensating for changes in surface potential due to temperature changes or aging will be described in detail below.

First, a surface electrometer as a detection means for detecting surface potential will be explained.

Figure WfJ5 is a side cross-sectional view of the surface electrometer, Figure 6 is a cross-sectional view taken along line xx' in Figure 5, and Figure 7 is a cross-sectional view taken along line xx' in Figure 5.
A sectional view taken along the Y' line and FIG. 8 are a perspective view of a chopper as an intermittent/interrupting means to be described later.

5.6 and 7.8, the outer cylinder is made of brass and has a surface charge detection window 88. 82 is a motor as a driving means for rotating the chopper 83;
8Bit cylindrical chopper with light emitting diode light passing window 9
0 and a potential measurement window 89. 84 is a light emitting diode, 85 is a surface charge measuring electrode, 86 is a preamplifier printed board on which a detection circuit for detecting the output of the electrode 55 is formed, and 87 is a phototransistor.

The surface charge detection window 88 is installed at a position 21CII away from the drum surface so as to face the surface of the drum. A preamplifier printed board 86 for amplifying the voltage detected by the electrode 85 is built-in and integrally formed.

Sensor motor drive signal SMD from a control circuit (not shown)
When is output, the sensor motor 82 is driven, the cylindrical chopper 83 rotates, and the electric charge on the drum surface is transferred to the potential measurement window 8.
9 to the electrode 85.

The potential measurement windows 89 are provided at four locations on the chopper 83 at equal intervals, and four locations are provided at equal intervals exactly between the potential measurement windows 890 of each of the light emitting diode light passing windows 90Fi. Chopper 83 induced by the electrode 85
rotates and interrupts the drum surface and electrode 85 at intervals, resulting in an alternating current voltage. The light from the light emitting diode 84 is received by the phototransistor 87 when the chopper 83 blocks the drum surface and the electrode 85, and the output of the phototransistor 87 is used as a synchronizing signal. 9
Reference numeral 1 denotes a shielding member for preventing light from entering the phototransistor 87 from the outside, and prevents dust, toner, etc. from entering the surface potential needle and adversely affecting measurement.

A variable resistor 92 that adjusts the gain of the surface potential detection output by changing the amplification factor of an amplifier mounted on the printed board 86 can be adjusted through an opening 93 with a driver or the like.

The surface electrometer 67 #'i is slightly longer than the drum 47, and is attached to steel plates 96 and 97 that support the drum etc. by a circular vertical tip 94 and a rear end 95 for positioning. The side plate 97 is removable.

Next, an outline of the surface potential control method will be explained. In this embodiment, in order to detect the drum surface potential in bright and dark areas, the blank exposure lamp 70 is used instead of the document illumination lamp 46 shown in FIG. I am using it. The surface potential of a portion of the drum surface irradiated with light from the blank fog light rung 70 is measured as a bright surface potential, and the surface potential of a portion of the drum surface that is not irradiated with light from the blank exposure lamp is measured as a dark surface potential. .

The target values are set for the bright area potential and the dark area potential that can provide an appropriate image contrast. In this example, the target bright area potential VLO -100V, target 1i
I set VDOf+475VK around tllf. In this embodiment, since the surface potential is controlled by controlling the current flowing through the primary charger and the AC charger, positive charging is performed so that the bright area potential and the dark area potential become the target potentials vt, o, and VDO, respectively. It is assumed that the AC charger reference current In and the AC charger reference current IAO1. In this example, Ip1=350μAIAOI−160μperson.

Explain the control procedure.

The surface potential detected at the first time is the bright area potential Vtt.
and dark area potential MDI, target bright area potentials vt and o, respectively.
% It is determined how much difference there is from the target dark potential vno. The difference voltage is ΔVLI.

If ΔVDI, ΔVLI m VLO−VLI (1) △V
(B-VDO-VDI
(2) The difference in potential in the bright area is corrected by AO Teiden, and the difference in potential in the dark area is corrected by the primary charger, but in reality, AO? ? Fi! When the device is controlled, not only the bright area potential but also the dark area potential is affected. Similarly, when controlling the primary charger, not only the dark potential but also the light potential is affected, so a correction method was adopted that takes both the AC charger and the primary charger into consideration.

Valley The corrected current value ΔIPI of the single-character charger is.

ΔIpx ” a1@Δvf11 + tl*0ΔVL
l (3).

Here, the setting coefficients a1 and α2 are changes in the current value of the primary charger when the surface potential VDpVL is changed, and can be expressed as follows.

On the other hand, the corrected current value ΔM O1 of the AC charger is Δ■10
1 Wβ1″ΔvD!+βf″ΔvL1 (6) Here, the setting coefficients β1 and β2 can be expressed as follows.

Therefore, the positive charger current IP after the first correction.

and AO charger current IAO! is expressed as follows.

(4) (5) From equation (1), here the setting coefficient a1. a2. β1. β2 is determined based on predetermined charging conditions, such as the ambient temperature, humidity, and the condition of the charger. Therefore, due to changes in the atmosphere, deterioration of the charger, etc., the surface potential may change to the target value by uniform control. Since it is not known whether or not this will be reached, the surface potential is measured multiple times when the device is in a predetermined state, and the output of the corona discharge device is controlled the same number of times as the measurements. Since the second and subsequent corrections use the same method as the first correction described above, the positive band after the nth correction [the current value of the vessel and the AOO electric appliance I, fi +
1.ImOH+i can be expressed as follows.

Figures 9a and 9b show changes in the dark potential when the primary charger control current I is corrected three times.

FIG. 9 shows a case where the atj setting calibration coefficient is smaller than the actual coefficient, and FIG. 9 shows a case where the setting calibration coefficient is larger than the actual coefficient.

In this embodiment, the number of corrections was set as shown in the table below.

By setting in this way, it is possible to further stabilize the position on the surface 1z of the photoreceptor and at the same time to minimize the reduction in copy speed.

Also, in state 1, the previous control output current value of the primary charger and AO\iOv is memorized, and the primary charger and A
In state 2, the previous control output current is passed through the photoreceptor to detect and control the surface potential. In the same way, the previous control output current is applied to the photoreceptor, and
The surface potential is detected and the control is performed twice, taking into account the time elapsed since the previous control.

In state 4, a considerable amount of time has passed since the last control, so during the first correction, the reference current IPI e
Flow IAOI and perform 4 rffil control.

In this embodiment, the developing bias voltage is further controlled. A schematic sectional view for explanation is shown in the 10th episode.

This is done in the following way. Immediately before the original fog light, a standard white plate 80 attached to the side of the original table glass 54 is irradiated with W, a nozzle lamp 46 for draft wax light, and the scattered reflected light is transmitted to the mirrors 44, 53, 55 and the lens. The amount of light irradiated onto the drum 47 via the drum 47 via the drum 47 is a single light amount, and the amount of exposure when the lamp 81 moves and actually illuminates the original is changed to the amount of light set arbitrarily by the operator. . The surface electrometer 67 measures the surface i*I potential vL of the portion of the drum 47 irradiated with the scattered reflected light, and calculates the measured value vL.
+100V added to the developing bias voltage wit
shall be.

The developing bias voltage V, the potential of the toner is almost the same as the bias voltage. For example, when the standard bright area potential, that is, the measured value vL is -1100 V, the potential of the toner is Ov, and the toner does not adhere to the drum, so the document pack It is possible to prevent fogging in the ground area and perform stable development at all times, resulting in stable images.

In addition, in this embodiment, a standard white plate 80 corresponding to the white part of a general original is irradiated with a standard amount of light, and when the original is actually exposed, the exposure amount is changed to an arbitrary value set by the operator, so that the background of the original is changed. Even when the drum is colored rather than white, a stable image can be obtained by changing the bright area surface potential of the drum depending on the exposure amount.

As described above, by shining light onto the standard white plate 80 using the original exposure lamp actually used for exposure, the developing bias pressure vH
Since this is determined, the accuracy of the control of the developing bias voltage is increased, and since it is performed just before the original is illuminated by external light, there is no reduction in the copying speed. Furthermore, since the exposure amount of the original is set arbitrarily by the operator during exposure of the original, a stable image can be obtained without fogging even when the background of the original is colored rather than white.

FIG. 11 shows a time chart for performing the image formation and surface potential control described above.

In FIG. 11, INTIL F'i is a counter rotation for erasing the residual charge on the drum and adjusting the sensitivity of the drum, and can always be executed before the copying operation.

0ONTR-N is a drum rotation to bring the drum to a steady state depending on the standing time, and at the same time, the bright area potential Vt and the dark area potential VD are alternately measured every rotation of the drum using a surface electrometer, which will be described later. The surface of the drum is controlled by the potential control circuit to bring the potential of the drum surface closer to the target value. Although the detection of the surface potentials VD and B is performed once per rotation, it is of course possible to perform the detection multiple times.

ORI is the bright area potential vL and the dark area potential V at 0.6 rotations of the drum.
This is the drum rotation that detects D and controls the corona charger.

OR, 2 is used to determine the bias value for the developing roller by measuring the bright area potential with the standard amount of light from the document illumination lamp while the drum rotates just before the start of copying. Always executed when copying starts.

SCFw indicates that the optical system is moving forward. In other words, it shows the actual copying operation.

A circuit for realizing the surface potential control described above will be described below.

FIG. 12 shows a surface potential detection processing circuit that detects and processes the surface position of the photosensitive drum 470, and FIG. 13 shows a circuit that controls the primary charger and AC static eliminator according to the control signal from FIG.
14 is a bias voltage control circuit that controls the developing bias voltage using the control signal from FIG. 12.

13 and 14 are explained in detail in, for example, Japanese Patent Application No. 103037/1983, previously filed by the applicant of the present invention, so a detailed explanation thereof will be omitted here.

In FIG. 12, OTl is a motor control circuit that receives the sensor motor drive signal SMD and controls the rotation of the motor 82, a synchronization signal generation circuit that generates a synchronization signal by a combination of an 0T2i1 light emitting diode 84, and a phototransistor 87, and C10. OT4. is a synchronous clamp circuit that clamps the AC detection signal from the preamplifier circuit PA with the synchronous signal from the circuit OT2. OT5 are each connected to a circuit OT2.
A smoothing circuit smoothes the DC signal from OT3, OT6 is a buffer circuit for receiving a signal from an unspecified Do controller that controls the main body of the copying machine, buffer circuit OT6
The output is input to an 8-bit digital microcomputer OT7 with a built-in .PHI. converter.

OT8 D/A converter and microphone controller O
Convert the output signal from T7 to analog i-. D/A
The output signal of converter OT8 is level-converted by level conversion circuit OT9. The output signal DOO of the circuit OT9 is used as the primary charger control signal and as the (fi No. AOO#'iAO#
[The signal is input to the circuit shown in FIG. 13 as a device control signal. Further, the signal RBO is inputted to the circuit shown in FIG. 14 as a developing roller bias control signal. 0T10 is computer OT7
The light emitting diodes UEDI to LESD6 are activated by the signal from
．． LED-Do.

This is a display circuit that lights up the LED-I)7. Also, 8W1
.

8W2 is a switch for inputting control information to the computer OT7.

The microcomputer OT7 contains a program for carrying out the above-described surface potential control method, and a flowchart of the program execution is shown in FIGS. 15A, B, and Cl.

v, 15 Figure A, B, Onioii (, DC11
An 8-bit digital value is used to control the bander. Similarly, AO and RB are the control digital values for the AO static eliminator developing bias, respectively. Also, DO8A, AO8A
.

R43SA indicates a storage area of the RAM in the microcomputer OT7 in which the digital values Do, AO, and RB are saved.

Step 8 This is a step for setting the initial values of the output and developing bias when the P1 power is turned on. When the copy button is pressed and the main motor drive signal DRMD becomes 1, the process advances to step SP3 (step 8P2). At step SP3, as is clear from the time chart in FIG.
Since VT 1 also becomes 1, the light emitting diode IJDI indicating that the signal DRMD is 1 and the light emitting diode LBD2 indicating that the signal HVTI is 1 are turned on, and the contents of the memory areas AO8A and Do8 are output.

In step 8P4, each of the timing signals DRMD.

'S1 HVTI, Vt, OTP, VDOTP, 'Ffl
LOTP, RBTP (D Check the input, and when each signal is input, proceed to the step where the corresponding processing is performed. When DRAΦ becomes 0, at this time, HVT 1 is also 0, so the light emitting diode IJDI , 2 is turned off at step SP7.Also, DRMD-1teHVT
'l-0 (D is in the rear rotation (L8TR), so the light emitting diode, T, and EDZ are turned off at step 8P5, and step 5-P6 (t'T HVTI, 1) lIA
4D Womi Chio 9 HVTI before DRAiD is OK
When becomes 1, it returns to ■. When DIWD becomes 0, Lgl)1. IJI) 2 is turned off.

Further, when VLOTP is 1 in step SP4, processing is performed in step 8P9, and the light emitting diode LED is
3 is lit. Similarly, each signal V' VnOTP, WzOTP, RBTP chi (D
t e it, 't: h tsure, x step ST'12
．． Processing is performed at 8P13.5PIO, and L1D4.
The relationship between the light emitting diode LEDI~1.131)6 and each program step is as shown in the table below.In other words, the light emitting diode Ll)31. )1 to LEI)6 By checking which light emitting diode is lit, it is possible to know which part of the program in the computer O'l'7 is backed up. In addition, the light emitting diodes L14D1 to TJI) 6 light up after the computer OT7 confirms the input of each signal using software, confirming that signals are actually being input into the computer and that the computer is operating. can. Furthermore, if an indicator is installed to confirm the generation of signals before the input terminal to the computer, the indicators corresponding to each signal can be compared to determine whether the computer is defective or the input control signal is incorrect. It is possible to judge whether

In addition, as shown in step 8P12, the light emitting diode L
ED-Dl turns on when the primary zone control digital value 1) exceeds a controllable value. Also, light emitting diode LE
Lights up when D-D2 digital value 1) 0 becomes less than a controllable value. Similarly, when the AO static eliminator control digital value AC is greater than or equal to a controllable value, LED-D3 lights up, and when it is less than the controllable value, LED-D4 lights up.

Light emitting diode Ll! :D-D5 is step 8P15
As shown in , it lights up when there is no synchronizing signal from the electrometer 67, indicating that the sensor motor is not rotating.

Light emitting diode L18D-D6. LET)-I)7 is the contrast 0ONT as shown in step 5P14.
It lights up when (the voltage difference between the bright area potential vL and the dark area potential VD) becomes 498V or less and 396V or less, respectively. Nao L
L4D-Do is a spare display light emitting diode.

In this way, in this embodiment, the light emitting diode is used to display the abnormal state and the control state.

The last measured vL, VD, and vLO values of 5WI-person and 5WI-BFi in Figure 12 are sent to the microcomputer OT7.
Light emitting diode LFD-DO- from each save area in
This is an on/off switch for displaying 8 bits on LED-D7. When both switches 5WI-A and 5WI-B are off, the above status display is displayed on the light emitting diode LED.
D1-LEI)-D7.

Further, when the switch 8W1-A is off and the switch 5WI-B is on, as shown in step 5P15, the digital value stored in the save area in the computer OT of the bright area potential vL is read out, and the light emitting diode LED- DO～L
Display in 8 bits on ED-D7. Similarly switch 8W
When 1-8 is on and 8W1-B is off, the dark potential vD
is displayed, and when both switches 5WI-A and 5WI-B are on, the standard bright area potential ν" VL is displayed.

The subroutine in FIG. 15 is executed at ED8P, and the subroutine EDSP is at step 8P4.

51P6. SF3 and 5 PIOK are provided, and display is performed using the duration of the signal.

As mentioned above, in this example! The output of the 1st position needle is converted into a digital value by an A/D converter built in the digital computer OT, and the output values of the A/D converter at different timings are stored in the digital computer, and the changeover switch is used to store the output values of the A/D converter at different timings. Each output value is designated, and the output value is digitally displayed using a light emitting diode based on the designation. With this configuration, it is possible to easily check the measured potential by simply switching a switch as a specifying means without using an external measuring device such as a voltmeter, and it is also possible to easily check the potentials generated at different timings. Therefore, it is also possible to diagnose the failure of a device equipped with a potential detection device.

For example, if the negative charger is defective and the output is not sufficient and the other circuits are normal, VL* v, , and υ′ will both be close to OV, so VL, VD , UL
.

If both detected values are near OV, it can be determined that the primary charger is defective. Also, when the AC static eliminator, full-face exposure lamp, original exposure lamp, blank exposure lamp, etc. is defective, vL, VD, and UL are used for each case.

Since this shows a unique value, the location of the failure can be easily discovered.

In addition, the switch 5W2-A is the primary charger and the ACC chip 4.
This switch is used to select whether to control the output of the sensor using the detected surface potential or to a predetermined value regardless of the detected potential.When it is off, the potential is controlled, and when it is on, the predetermined value is controlled. Similarly, when the switch 5W2-B is off, the developing bias voltage is controlled by the detected potential, and when it is on, it is controlled to a predetermined value.

However, when both 5W2-A and 8W2-B are on, as shown in Step 8P15, the value obtained by converting the measured value from the surface electrometer into A4 format is used as the potential measurement display mode, and the value converted to A4 is directly displayed on the light emitting diode LED-I)O-IJD-D7. is displayed.

In this potential measurement display mode, for example, the gain of the output of the surface electrometer 67 is set to vI4! Used when doing I. To adjust the gain, attach a pseudo drum biased to a predetermined voltage to the copying machine instead of the photosensitive drum, and adjust the variable resistor 92 so that the predetermined voltage matches the display value of the light emitting diodes LED-DO to LED-D7. Then start with TotoK. At this time, the signal -RMD is 0, so step SP2. If you keep repeating the process of SF3, you will finally enter the spiritual position measurement display mode.

In this way, the measured potential can be easily checked without using an external measuring device, making adjustment of the electrometer easier. Furthermore, since the display for displaying the status and the display for the measured potential are used together, and the measured potential is displayed only in a specific state, an increase in cost can be kept to a minimum.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a copying apparatus to which the present invention can be applied.
Figure b: A plan view of the vicinity of the blank exposure lamp 70; Figure 2 is a characteristic diagram showing the surface potential of each part of the photosensitive drum; Figure 3:
Figure 4 is a characteristic diagram showing changes in surface potential, Figure 5 is a cross-sectional view of the surface potential meter, Figure 6 is a cross-sectional view taken along line xx' in Figure 5, and Figure 7 is a cross-sectional view of the surface potential meter. is a sectional view taken along the Y-Y' line in Fig. 5, Fig. 8 is a perspective view of the cylindrical chopper, and Figs. 9 a and b.
10A is a schematic cross-sectional view of a copying device related to developing bias control, FIG. 10 is a point detection processing circuit diagram of an original exposure lamp, and FIG. 13 is a charger control circuit diagram. , FIG. 14 is a bias voltage control circuit diagram, and FIG. 15 is a bias voltage control circuit diagram.
FIGS. 15(A) to 15(0) are diagrams showing control flowcharts of the computer OT7. In the figure, 47 is a photosensitive drum, 67 is a surface electrometer, r
, gn■~LED6. IJD-Do to LED-D7 each indicate a light emitting diode. Applicant: Canon Co., Ltd. Engraving of the drawings (no changes to the content) Hand-made New Year's Day = (Method) April 21, 1985 ``1 Commissioner of the Patent Office Black 11 Akira 7j (I, 1985! Ih Ha' [Application No. 243681 No. 2, Name of the invention Image forming device 3, Relationship with the person making the amendment case Special ¥ [Applicant address: 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (+00
) Canon Co., Ltd. Representative Ryuzo Kaku
Part 4. Agent address: Canon Co., Ltd., 3-30-2 Shimomaruko, Ota-ku, Tokyo 146 (telephone: 758-2111). 5. Date of amendment order (shipment date): March 310, 1988. 6. Map subject to amendment. Surface 7, correction details

Claims (1)

[Scope of Claims] Means for forming an image on a recording medium; means for detecting a parameter related to the image quality of the image formed by the image forming means; and means for detecting a parameter related to the image quality of the image formed by the image forming means; The apparatus is characterized by comprising means for automatically controlling the operating state of the image forming means, and means for manually selecting whether or not to operate the automatic control means when the image forming means is executed. image forming device.