JP3078861B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a copying machine, a printer, etc., which forms an electrostatic latent image on a photosensitive member by projecting recording image light onto the photosensitive member and develops the electrostatic latent image to form a visible image. And an image forming apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus, a latent image is formed on a photoreceptor by exposure to a reference density pattern under predetermined conditions, developed, and the state of the image of the reference density pattern is detected by an optical sensor. Are known (for example, see
-223848, JP-A-3-1180, etc.).

However, the output value greatly varies depending on the eccentricity and surface properties (reflectance) of the photosensitive drum. Also,
Since the output value is used after being subjected to AD conversion, it is desirable for the process condition control to use a region where the S / D characteristic, the resolution and the output characteristic of the element are most advantageous.

Therefore, a method is known in which the drum is rotated so as to cancel the eccentricity of the photosensitive drum, and the average value of the values read at equal intervals on the drum surface is used (Japanese Patent Laid-Open No. Hei 3 (1993) -313).
-29970).

[0005]

Problems to be Solved by the Invention
In the reading method disclosed in Japanese Patent Application Laid-Open No. H11-207, the productivity of copying is reduced during the copying operation. However, even during this copying operation, there is a possibility that the sensor output fluctuates due to a temperature drift or the like due to a rise in internal temperature.

SUMMARY OF THE INVENTION It is an object of the present invention to secure a stable sensor output in accordance with the state of an image forming apparatus without lowering the productivity of image formation.

[0007]

Means for Solving the Problems The present invention relates to a photoconductor (1).
21); charging means (122) for uniformly charging the photoconductor (121); optical means (113A to 113F, 114, 115) for exposing the photoconductor (121) to form an electrostatic latent image on the photoconductor (121) );
And a density detecting means (PSN) for performing density detection by projecting light onto the photoreceptor (121) and receiving reflected light;
The light emission drive value (PWM data) of the density detecting means (PSN) is set such that the density detected by the density detecting means (PSN) at a plurality of points in the moving direction of the photoconductor (121) becomes a set value (4.0 V). First adjusting means for adjusting and setting (400: 3 in FIG. 5); and image form
For forming the operation period, the detection of the set emitting <br/> light drive value by the first adjusting means (400) (PWM data) the light emission drive the concentration detection means (PSN) in the concentration detection means (PSN) concentration changes the set light emission drive values such that the set value (4.0V) (PWM data), the second adjusting means (400: 7, 8 in FIG. 5); characterized in that it comprises a.

The first adjusting means (400) operates at a predetermined timing during an image forming preparation period by the photoconductor (12).
The concentration detecting means such that the concentration detected by the concentration detecting means (PSN) at a plurality of points in the moving direction of 1) becomes a set value (4.0 V).
Adjust and set the emission drive value (PWM data) of (PSN).

[0009] Incidentally, <br/> in parentheses to facilitate understanding, corresponding elements of the code or the corresponding items of the embodiments described below are shown in the drawings and have been appended for reference.

[0010]

According to this, the first adjusting means (400) is provided with a photosensitive member.
The emission drive value (PWM data) of the density detection means (PSN) is adjusted and set so that the density detected by the density detection means (PSN) at a plurality of points in the movement direction of (121) becomes a set value (4.0 V). Therefore, a light emission drive value (PWM data) is set which highly accurately corrects the fluctuation of the detected density of the density detecting means (PSN) caused by the eccentricity and surface property of the photoconductor (121). In addition, the second adjusting means (400) is provided during the image forming operation period.
(400) detecting the concentration of the concentration detection means (PSN) a light emission driving and the concentration detection means (PSN) is the set to be the set value (4.0V) at the set emission drive value (PWM data) Since the light emission drive value (PWM data) is changed, the light emission amount of the density detection means (PSN) can be adjusted without changing the image forming repeat cycle, and the temperature rise and toner scattering accompanying the image forming operation The fluctuation of the detected density of the density detecting means (PSN) caused by the output decrease due to the above can be corrected.

Further , since the light emission drive value (PWM data) set by the first adjusting means (400) is used when the second adjusting means (400) first performs the above-described processing, the density detecting means at that time is used. The reliability of the detected concentration by (PSN) is high, and the reliability of the above-described concentration detection and the adjustment of the light emission amount by the second adjusting means (400) is high.

Further, a second adjusting means capable of performing adjustment in a short time.
Perform the above processing of (400) during the image forming operation period, and
Since the above-described processing of the first adjusting unit (400), which takes a long time, is performed at a predetermined timing in the image forming preparation period, the density detecting unit (PSN) can be used without lowering the copy productivity.
Stable concentration detection can be achieved by.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0014]

FIG. 1 shows a copying apparatus 100 according to an embodiment of the present invention.

The copying apparatus 100 is an original-fixed electrostatic transfer type copying apparatus, and includes an optical system 110, an image forming system 120, a paper feeding system 130, a paper discharging system 140, and the like. The optical system 110 includes a contact glass 111 and an exposure lamp 112 disposed below the contact glass 111,
Mirror 113A, second mirror 113B, third mirror 113C, fourth mirror 113D, fifth mirror 113E, sixth mirror 113F, lens 11
4 and a dust-proof glass 115, and the image forming system 120 includes a photosensitive drum 121 and a charging charger 1 provided around the photosensitive drum 121.
22, eraser 123, developing device 124, pre-transfer charger 126,
Separation charger 127, separation claw 128, pre-cleaning static elimination charger (hereinafter referred to as PCC) 129, and cleaner 12
A, and a transport belt 12B and a fixing device 12C arranged downstream of the photosensitive drum 121. The paper feed system 130 includes a manual feed tray 131, a feed tray 131A, a call roller 132, a paper feed roller 133 provided in the paper feed tray, and a reverse rotation roller 134, a registration roller 135, a guide mylar 136, and various guides and intermediate parts. It consists of rollers and the like. In addition, the manual feed tray 131 feeds the call roller 132, the feed roller 133, and the reversing roller 134 to the feed tray 1.
Shared with 31A. The paper discharge system 140 includes a contact roller 142 and a paper discharge roller 141.

When a document is set on the contact glass 111 and a start instruction is given, the paper feed clutch is turned on, and the call roller of the paper feed table selected at that time sends the recording paper to the paper feed roller. The feed roller is a registration roller for the recording paper.
Send it out to 135. During this time, the optical system 110 scans the original on the contact glass 111, and reflects the reflected light of the original illuminated by the exposure lamp 112 on the first mirror 113A, the second mirror 113B,
The light is guided to the photosensitive surface of the photosensitive drum 121 via the third mirror 113C, the lens 114, the fourth mirror 113D, the fifth mirror 113E, the sixth mirror 113F, and the dustproof glass 115.

The photosensitive drum 121 is rotating clockwise in the figure. The photosensitive surface of the photosensitive drum 121 is uniformly charged by the charger 122 before being reflected by the original 110 from the optical system 110. The latent image area has been formed by the static elimination by the capacitor 123. Therefore, when the latent image area is irradiated with the reflected light of the document, photoelectric conduction is generated according to the intensity of the reflected light, and an electrostatic latent image is formed. This electrostatic latent image is developed by the developing device 124 to become a toner image to which toner adheres according to the density of the document. This toner image is transferred to the recording paper fed from the registration roller 135.
TL125 removes electricity before transfer.

The recording paper fed by the registration roller 135 is brought into close contact with the photosensitive surface of the photosensitive drum 121 by a guide mylar 136, and a toner image is transferred immediately above the transfer charger 126. Immediately thereafter, the recording paper is separated from the photosensitive surface by the separation charger 127. If the separation is insufficient at this time, the recording paper is forcibly separated by the separation claw 128. After separation of the recording paper, the remaining toner is removed from the photosensitive surface of the photosensitive drum 121 by a cleaner 12A, and the recording paper is sent to a fixing device 12C by a conveyor belt 12B. The fixing device 12C includes a fixing roller 12CA and a pressure roller 12CB, and heats the recording paper to which the toner image has been transferred while applying pressure (about 185 ° C.) to fix the toner image. The recording paper on which the toner image has been fixed
Passed to 140. The paper discharge system 140 guides the recording paper to a paper discharge roller 141, and the recording paper is discharged out of the apparatus by the paper discharge roller 141 and the contact / separation roller 142.

When the toner density of the developing device 124 is detected, a toner image of the reference density document 13 provided in advance at the home position of the scanner is formed, and the density is determined by a P sensor PSN provided downstream of the developing device 124. Read by

The components described above are controlled by the electric control system shown in FIG. The electric control system includes a storage unit 410, an optical control unit 420, an AC control unit 430, an operation control unit 440, and the like, with a main control unit 400 at the center.

The main control section 400 includes various sensors 420 such as a P sensor PSN and a temperature sensor provided in each section of the copying apparatus 100.
To control the loads of the solenoids, motors, etc. of each part. The optical control unit 420 controls a lens mode for driving the lens 114.
Control the scanner motor for performing optical scanning and optical scanning.
The C control unit 430 includes heaters for the exposure lamp 112 and the fixing device 12C,
Main motor, development motor, transport motor and paper feed motor
Control the AC load such as The operation control unit 440 operates and
The key operation of the display board 150 is read and the display is controlled.

FIG. 3 shows a main controller 400 and a P sensor PS.
The relationship with N is shown. The P sensor PSN is a light emitting element (LE
D) and a light receiving element (phototransistor SPD). The light emitting side is driven by PWM, and the light receiving side is a resistor R _L
Is inserted and the terminal voltage is AD-converted to obtain V _SG (sensor output reading the background portion of the photoconductor) and V _SP (sensor output reading the reference density pattern 13 of the photoconductor). In this embodiment, V _SG is set to 4.0V.

FIG. 4 shows V vs. PWM output duty.
_{The SG} relationship is shown. Although the inclination is different depending on the sensitivity of the light emitting element and the light receiving element as shown by a portion l in the figure, the output varies as a single sensor.

In the following, FIG. 5, FIG. 6, FIG. 7, FIG.
The contents of the processing of the copying apparatus 100 will be described with reference to the outline of the processing procedure of the main control unit 400 shown in FIGS.

FIG. 5 is a main flowchart of the main control section 400. First, when the power is turned on, initialization (IL) is performed (step 1: the word "step" is omitted in parentheses hereinafter). In the initialization (IL), various ports are set, registers and the like are cleared, output ports are reset, and an abnormality check (EM) for processing at the time of occurrence of an abnormality such as a door open or a jam is performed. Thereafter, a standby mode process (WT) is performed (2). In the standby mode processing (WT), reading of a key input from the operation unit,
Fixing temperature (startup) processing and abnormality check (EM)
And so on. Next, a first adjustment process described later is performed (3),
Copying is enabled (4), and when there is a start instruction (5), pre-copy mode processing (FT) is performed. In the pre-copy mode processing (FT), copy preparation processing such as determination of the drive motor and drum rotation output, setting of a register Nset for the number of copies to be set (NK), and abnormality check (EM) are performed. Next, a level detection process (7) and a second adjustment process (8), which will be described later, are performed, and it is checked whether the overflag OF and the down flag DF set in the level detection process (7) are all 0 (9). If all are 0, the register n (the number of copies that determines the number of times of execution of the level detection process) is set to 0 (10), and the copy mode process (CP) is performed (1).
1). In the copy mode process (CP), a copy process process, a paper transport process, a toner replenishment process, an abnormality check (EM), and the like according to a copy cycle are performed. In the toner supply process, the necessity of toner supply is controlled in accordance with the value of the output of the P sensor PSN determined by the first adjustment process ( 3 ) and the second adjustment process ( 8 ). When the copy mode process (CP) ends (12), the register n and the register C _COPY indicating the number of copies are incremented by one (1).
3, 14), the number of copies (C _COPY ) is the number of sets (Nse
Steps 7 to 15 are repeated until t).
When the number of copies (C _COPY ) becomes equal to the number of sets (Nset) (15), the register C _COPY is set to 0 (16),
A post-copy mode process (LT) is performed (17). In the post-copy mode processing (LT), post-copy processing such as turning off the drum rotation output, paper discharge processing, and abnormality check (EM) are performed, and the request flag for requesting the execution of the first adjustment processing (3) is set to 0 ( 1: perform the first adjustment process, 0: do not perform the first adjustment process) (18). Note that the request flag is set to 1 in the initial setting. Therefore,
In the present embodiment, the first adjustment process (3) is substantially performed only when the power is turned on. Thereafter, the process returns to step 2 and repeats the processes after the standby mode process (WT) (2 to 18-2).

FIGS. 6, 7 and 8 show flowcharts of the level detection processing (7) shown in FIG. Please refer to FIG. First, in this process, check whether the register C _COPY is zero (701), not 0 register n is checked whether a predetermined number n ₀ or more (702), a predetermined number n ₀ or more, or the register C _COPY There check request flag (V _SG flag indicating the read timing end of) it is checked whether the 0 if 0 (703). That is, in the present embodiment, the following level detection processing is executed before the first copy and after every predetermined number n _{0 of} copies.

If the check request flag is 0,
The P sensor PSN is turned on, and the check request flag is set to 1 (704, 705). Then, exposure processing of the reference density pattern 13 is performed (706), V _SG and V _SP are read (707 and 708), the P sensor PSN is turned off, the check request flag is set to 0, and the P
The state set for detecting the sensor PSN concentration is released (709, 710, 711).

Referring to FIG. Data of V _SG is there whether or not to confirm (712). This is a determination process when V _SG and V _SP cannot be read when an abnormality occurs around the process, for example, when the density of the created reference density pattern is abnormally low. Without data V _SG, OF1 (over 1 flag), OF2 (over 2 flag), OF3 (over 3 flag), DF1 (Down 1
Flag, DF2 (down 2 flag) and DF3 (down 3 flag) are set to 0 (713), and buffer 1
(Data buffer of the detected V _SG), a buffer 2 (detected, the last data buffer of V _SG) (detected, the second last, the data buffer of V _SG) and the buffer 3 0
(714), and an adjustment request flag for requesting adjustment of the PWM duty output of the light emitting element (LED) is set to 0 (715).

FIG. 12 shows the _VSG region with respect to the set voltage. The setting voltage is 4.0 V as described above.
And OF1 detects B ₁ (4.15 V or more and less than 4.30 V) and C ₁ (4.15 V) once when the detected V _SG is 4.0 V or more.
This is a flag indicating that the level is at least 30 V and less than 4.40 V). OF2 is a flag indicating that detected V _SG is in 2 times followed by B _1, C ₁ level above 4.0V. OF3 is one time C ₁ when the detected V _SG is 4.0 V or more.
This is a flag indicating that it is at the level. DF1 detects B ₁ (3.85 V or less and 3.70 V or more) and C ₁ (3.70 V or less 3.50 V) once when the detected V _SG is 4.0 V or less.
Greater) is a flag indicating that it is at the level. DF2
Means that B ₁ and C _{1 are} continuously detected twice when the detected V _SG is 4.0 V or less.
This is a flag indicating that it is at the level. DF3 is a flag indicating that detected V _SG is once C ₁ level below 4.0V. The buffers 1 to 3 are configured by the storage unit 410 shown in FIG.

[0030] V _SG is 3.85V greater than 4.15V there are V _SG data in step 712 (FIG. 12 region A) (716,717), OF1, OF2 , OF3,
DF1, DF2, DF3 were set to zero (718), and migrate data from buffer 2 to the buffer 3 (719), to migrate the data in the buffer 1 to buffer 2 (720), shifts the V _SG data in the buffer 1 (721). At the first time, no data exists in the buffers 1 and 2. That is, since the adjustment request flag is not 1 in the area A, the second adjustment processing (8) is not performed.

If V _SG is 4.15 V or more in step 716, DF1, DF2, and DF3 are set to 0 (72).
2) Check if V _SG is 4.30 V or more (72
3) If it is 4.30 V or more, it is further checked whether it is 4.40 V or more (724). If the voltage is equal to or higher than 4.40 V (region D _{1 in} FIG. 12), the adjustment request flag is set to 1 (732), and the routine proceeds to step 718. That is, the second adjusting process (8) performed unconditionally in the region D _1.

[0032] V _SG in step 724 is less than 4.40 (region C ₁ in FIG. 12), OF3 is checked whether 1 (725), the process proceeds to step 732 If it is 1, 1 Otherwise, OF3 is set to 1 (726) and O3
It is checked whether or not F2 is 1 (728). If it is 1, the process proceeds to step 732. If it is not 1, it is further checked whether or not OF1 is 1 (729). If it is 1, OF2 is set to 1. (731) If it is not 1, OF1 is set to 1 (730), and the process proceeds to step 719. That is, in the region C _1, the two consecutive is V _SG in this range, OF3
Is set to 1 (726), and the process proceeds to step 732 in step 725, so that the second adjusting process (8) is performed.

If V _SG is less than 4.30 (region B _{1 in} FIG. 12) at step 723, OF3 is set to 0 (7
27), the process proceeds to step 728 and subsequent steps. That is,
Since when set to 1 in the order of region B ₁ in OF1, OF2 proceeds to step 732, V _SG to the region B ₁ in succession 3 times
Is or, if there is one area B ₁ to have V _SG 2,3 th to B ₁ or C ₁ to V _SG, second adjustment processing (8) is performed.

Referring to FIG. Step 717 (FIG. 7)
If V _SG is 3.85V or less, OF1, OF2, O
F3 is set to 0 (733), and it is checked whether V _SG is 3.70V or less (734). If it is 3.70V or less, it is further checked whether it is 3.50V or less (73).
5). When the voltage is equal to or less than 3.50 V (region D _{2 in} FIG. 12),
The adjustment request flag is set to 1 (732), and the process proceeds to step 718. That is, the second adjusting process (8) performed unconditionally in the region D _2.

In step 735, if V _SG is larger than 3.50 (region C _{2 in} FIG. 12), it is checked whether or not DF3 is 1 (736). If it is 1, the process proceeds to step 732, but it is not 1. And DF3 are set to 1 (737), and D
It is checked whether or not F2 is 1 (739). If it is 1, the process proceeds to step 732. If it is not 1, it is further checked whether or not DF1 is 1 (740). If it is 1, DF2 is set to 1. (742) If it is not 1, DF1 is set to 1 (741), and the process proceeds to step 719. That is, in the region C _2, the two consecutive is V _SG in this range, DF3
Is set to 1 (737), and the process proceeds to step 732 by step 736, so that the second adjustment process (8) is performed.

If V _SG is larger than 3.70 (region B _{2 in} FIG. 12) in step 734, DF3 is set to 0 (7
38), and the process proceeds to step 739 and subsequent steps. That is,
Since when set to 1 in the order of region B ₂ in DF1, DF2 proceeds to step 732, VSG to the area B ₂ three consecutive times
It is or, if there is one region B ₂ to have V _SG 2,3 time the B ₂ or C ₂ to V _SG, second adjustment processing (8) is performed.

FIG. 9 shows a flowchart of the second adjustment processing (8) shown in FIG. In this process, first, it is checked whether or not the adjustment request flag is 1 (81), and if it is 1, it is checked whether the data of the buffer 2 is 0 (8).
2) If the value is 0, the data in buffer 1 is transferred to buffer 2 (83). This is because when V _SG is equal to or less than 3.50 V or equal to or more than 4.40 V, a state in which data in the buffer 2 does not exist can be considered because the adjustment processing is performed by one detection. Next, the value obtained by multiplying the value of PWM by 4.0 V (set voltage) by the average of the buffers 1 and 2 is set as a new PWM value (84). PWM is a duty that determines the current of the light emitting element (LED) and is indicated by 8 bits (0 to 255). The output of the P sensor PSN is also received at the AN port (8 bits: 0 to 25)
5). Further, since the sensor characteristic is linear as shown in FIG. 4, the value of PWM can be obtained by calculation. If not linear, the change in PWM may be obtained based on the largest slope of ΔV _SG / ΔPWM.

When the process of step 84 is completed, the buffers 1 to 3 are set to 0 (85), and the adjustment request flag is set to 0 (86).

As described above, in the second adjustment processing (8), it is determined whether or not the adjustment operation is performed according to the _VSG output value when the reference density pattern 13 is detected. Second adjustment processing (8)
Is executed after the pre-copy mode processing (FT) (6), so that the detection, judgment, and adjustment for the adjustment operation can be performed without any change in the timing of the copy repeat cycle (different for each size) even during the copy operation. Becomes That is, the variation in the output of the P sensor PSN due to a decrease in output due to a temperature rise (temperature drift) or sensor contamination (toner scattering) accompanying the copy operation is corrected.

Next, FIG. 10 and FIG.
4 shows a flowchart of one adjustment process (3). Please refer to FIG. In this process, the photoconductor 121 is divided into six parts (corresponding to eccentricity by a plurality of divisions), each divided part is adjusted at a resolution of 255, and a value obtained by dividing the sum by six is set as a _VSG set value. First, it is checked whether the request flag for executing the first adjustment process (3) is 1 (31). If it is 1 (set to 1 in the initial setting), the bias non-image portion is output (32), the drum drive motor and the neutralizing lamp are turned on (33, 34), and the drum position counter indicating the drum position (1 in the embodiment). ° = 1), the request flag is set to 0, the running flag is set to 1, the check count (the number of executions of the adjustment operation) is set to 0, and the PWM count L / H
(Sum of PWM values adjusted by dividing the photosensitive member into six) is set to 0
And return (35, 36, 3
7, 38, 39). The drum position counter is automatically incremented when the motor is turned on.

If the request flag is 0 in step 31 (step 36 or step 18 in FIG. 5), it is checked whether the running flag is 1 (40), and 1
Then, it is checked whether the check count is 6 (41). If it is not 6, it is checked whether the drum position counter is 60 (42). If it is not 60, the process proceeds to step 45. If it is 60, a PWM check (44) is executed. That is, the PWM check (44) is executed at a timing of 60 ° while rotating the photosensitive drum.

Referring to FIG. 11, the PWM check (4
4) will be described. In this process, the start flag (a flag indicating that one location divided into six parts is being adjusted) is set to 1
(441), and if it is not 1, the drum position counter is set to 1 (442), and the PWM data (PW
The value of MBiT is set to 0 (data for obtaining an output value of 4.0 V) (443), and PWMiT is set.
Is set to 128 (444), the start flag is set to 1 (445), and the routine returns. In addition, PWMBi
T is 128 → 6 because the resolution of PWM is 8 bits.
Change from 4 → 32 → 16 → 8 → 4 → 2 → 1.

At step 441, the start flag is set to 1
(Step 445), it is checked whether the P sensor PSN output (V _SG ) is 4.0 V (446),
If it is not 4.0 V, check if it is larger than that value (4
47). If the P sensor PSN output is less than 4.0 V, P
The value obtained by adding the value of PWMiT to the WM data is used as the new PWM
The data is set to M data (448). And PWMBiT is 1
(449), and if it is 1, the start flag is set to 0 (452), and the end flag (flag indicating the end of adjustment of one location divided into six) is set to 1 (453), The PWM output port is set to 0 and the process returns (454). If the P sensor output is more than 4.0V
The same goes for In Step 449, so, if the value of PWMBiT 1, a value obtained by dividing the value of PWMBiT 2 as the value of the new PWMBiT (450), the PWM output port, set the PWM data calculated in step 448 (451 ), Return.

Referring back to FIG. If the PWM check (44) is completed or the drum position counter is not 60 (42), it is checked whether the end flag is 1 (45). If it is 1, the end flag is set to 0 (46), and the check count is incremented by 1 (4
7) A value obtained by adding the PWM data to the PWM count L / H is set as a new PWM count L / H (48), and the process returns.

At step 41, the check count is 6
(Step 47), that is, when the PWM check (44) is completed over the entire circumference of the photoconductor (for six times), the drum position counter is set to 0 (49),
The value obtained by dividing the PWM count L / H by 6 is used as PWM data (50). Then, the running flag is set to 0 (51), and the bias output, the neutralizing lamp, and the drum drive motor are turned off (52 to 54), and the process returns.

As described above, in the first adjustment processing (3), since the sampling is performed over the entire circumference at equal intervals on the photosensitive member, the fluctuation of the output of the P sensor PSN due to the eccentricity and surface properties of the drum and the drum bearing portion are obtained. Is corrected. Further, the first adjustment processing (3), which has a longer adjustment time than the second adjustment processing (8) that operates with the detection value of one portion of the photoconductor, is performed at a predetermined timing other than the image forming operation (in the embodiment, the first adjustment processing (3)). (After the standby mode processing at the time of turning on the power), the copy productivity (repeat cycle) is not particularly reduced. In states other than the image forming operation,
Since the temperature rise is small and no drift occurs, the adjustment is more accurate than the second adjustment processing (8).

In the present embodiment, in the second adjustment processing (8), six types of flags are used like a counter to count the number of times exceeding the threshold, but individual counters are provided for each. Is also good. In addition, since the P sensor PSN is optical and is affected by surface contamination and the like, an upper limit of the PWM value is set in the second adjustment process (8), and when the upper limit is reached, a warning is displayed. Is also good.

The first adjustment process (3) is performed every time the power is turned on. In addition, when the OF2 or DF2 is set to 1 in the second adjustment process (8), the request flag is set to 1 To perform the first adjustment process (3).

[0049]

According to this, the first adjusting means (400) is
To correct the variation in the detected concentration of the concentration detection means due to the eccentricity and surface properties of the sensitive light body (121) (PSN) with high precision
I can .

Further, the second adjusting means (400) is provided with a density detecting means (PSN) caused by a rise in temperature due to the image forming operation and a decrease in output due to toner scattering without changing the repeat cycle of image formation. correcting the variation of the detected concentration of)
Can be .

Further, the second adjustment means (40
Performs light amount correction by 0) in the image forming operation period, since the relatively adjusted according the first adjusting means time (400) of the light amount correction performed at a predetermined timing of the image forming preparation period,
Density detection means without reducing the productivity of image formation
It can be realized a stable density detection by (PSN).

[Brief description of the drawings]

FIG. 1 is a side view illustrating a schematic configuration of an image forming unit of a copying apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram schematically showing a control system of the copying apparatus shown in FIG.

FIG. 3 shows a main control unit 400 and a P sensor PS shown in FIG.
FIG. 4 is a block diagram showing a relationship with N.

FIG. 4 is a graph showing characteristics of a P sensor PSN.

FIG. 5 is a main flowchart showing a control operation of a main control unit 400.

FIG. 6 is a flowchart showing a level detection process (7) shown in FIG.

7 is a flowchart showing a level detection process (7) shown in FIG.

8 is a flowchart showing a level detection process (7) shown in FIG.

9 is a flowchart showing a second adjustment process (8) shown in FIG.

10 is a flowchart showing a first adjustment process (3) shown in FIG.

FIG. 11 shows a PWM check process (44) shown in FIG.
It is a flowchart which shows.

FIG. 12 is a block diagram showing an area of an output VSG of a P sensor PSN.

[Explanation of symbols]

 100: Copier 110: Optical system 120: Imaging system 130: Paper feed system 140: Refeed system 150: Operation board 13: Reference density original 112: Exposure lamps 113A to 113F: Mirror 114: Lens 115: Dustproof Glass 121: Photoreceptor 124: Developing unit 400: Main control unit (first adjustment unit, second adjustment unit) 410: Storage unit 420: Optical control unit 430: AC control unit 440: Operation control unit PSN: P sensor (density) (Detection means)

Claims (2)

(57) [Claims] A photosensitive member; charging means for uniformly charging the photosensitive member; optical means for exposing the photosensitive member to form an electrostatic latent image on the photosensitive member; and developing the electrostatic latent image with a toner. An image forming apparatus comprising: developing means; and density detecting means for detecting density by projecting light onto the photoreceptor and receiving reflected light, wherein the density detecting means at a plurality of points in the moving direction of the photoreceptor First adjusting means for adjusting and setting a light emission drive value of the density detection means so that the detected density becomes a set value; and, during an image forming operation , the light emission drive value set by the first adjustment means. detected concentration of emitted drive detection means said concentration-detecting means changes said set light emission drive values such that the set value, the second adjusting means; image forming apparatus comprising: a. 2. The image forming apparatus according to claim 1, wherein the first adjusting unit controls the density of the plurality of points in the moving direction of the photoconductor to a set value at a predetermined timing during an image forming preparation period. Adjust and set the emission drive value,
The image forming apparatus according to claim 1 Symbol placement.