JPH031180A - Adjusting method for toner concentration detecting means - Google Patents

Abstract

PURPOSE:To correct dirt before an abnormality display is made by irradiating a photosensitive body ground nearby a toner image with light when toner density is detected and detecting its reflected light and adjusting the toner concentration detecting device automatically according to the detected value. CONSTITUTION:At timing right after the start of concentration measurement, a position on the upstream side of a reference pattern formation area on a photosensitive drum 2 faces a sensor PSEN and at the position, charges are erased by a erasure sensor 3 and no toner sticks even when toner passes through the development part 5, so the sensor PSEN detects the light reflection factor of the surface of the photosensitive drum 2. Then the toner concentration detecting device is adjusted automatically according to the value. Thus, the automatic adjustment is made before the abnormality display is made and dirt can be corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for adjusting a toner concentration detection device of a copying machine.

[Conventional technology]

First, in a copying machine, a reflective photosensor (toner density sensor) is installed downstream of the developing device, facing the photoreceptor, and detects the density of the toner image of the reference density pattern formed on the photoreceptor. , and perform various process controls.

By the way, if the toner concentration sensor becomes dirty due to adhesion of toner, accurate toner concentration information cannot be obtained. Therefore, measures are taken to prevent the sensor from becoming dirty, such as creating an air current using a fan and blowing it onto the sensor section. but,
Since this sensor detects the toner image while facing the photoconductor, the above-mentioned measures alone will cause the sensor to become dirty.

Therefore, the following proposals have been made so far.

That is, Japanese Patent Application Laid-Open No. 63-27867 discloses a technique for displaying an abnormality on an abnormality display means when a detected value of a portion without a toner image is outside a predetermined range.

Further, Japanese Patent Laid-Open No. 59-53869 proposes a technique that makes no adjustment necessary by utilizing the difference between the detected value of a portion without a toner image and the detected value of a toner image.

[Problem to be solved by the invention]

Among the above-mentioned conventional techniques, the former has a problem in that the adjustment means is a manual one using a variable resistor, and automatic adjustment cannot be performed, so that maintenance is inevitable.

Furthermore, the latter cannot cover the reduction in output due to dirt. For example, if the detected value of the part without toner image is 4V, the normal toner image output is about 0.5■, and the difference is 3.5■
However, if 4V drops to 3V, no matter what the output value of the toner image is, the difference will become smaller than 3.5V, making control impossible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for adjusting a toner concentration detection device that can perform automatic adjustment to correct dirt before displaying an abnormality, and can accurately detect an abnormality.

[Means to solve the problem]

The above purpose is to adjust a toner density detection device that forms a toner image of a reference density pattern on a photoreceptor in advance prior to image formation, and detects the toner density of this toner image with a toner density sensor consisting of a reflective photosensor. This is achieved by detecting the surface density of the photoreceptor near the toner image at the same time as detecting the toner density, and automatically adjusting the toner density detection device based on the detected value.

[Effect]

When detecting toner concentration, light is irradiated to the surface of the photoconductor near the toner image where there is no toner image, and the reflected light is detected. If the value is outside a predetermined range, the toner concentration detection device is automatically adjusted. Contamination can be corrected by performing the following steps.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a type of copying machine embodying the present invention.
This will be explained with reference to the figures. Briefly speaking, this copier is
Copying machine body and ADF (automatic document feeder) 60. Sorter 70. Automatic double-sided processing unit 80. It consists of a group of optional units such as a supply IE unit. The paper feed system that supplies recording sheets has five stages. That is, the first paper feeding system and the second paper feeding system are provided in the main body of the copying machine, and the third paper feeding system is a second paper feeding unit and a third paper feeding system including a fourth paper feeding system and a fifth paper feeding system. The paper feed unit is connected to the copier main body. 21, 22, 23 and 24 are the first
These are cassettes provided in the paper feeding system, the second paper feeding system, the third paper feeding system, and the fourth paper feeding system, and 25 is a tray of the fifth paper feeding system.

A contact glass 1 on which a document is placed is provided at the top of the copying machine body, and an optical scanning system 30 is installed below it.
It's gone. The optical scanning system 30 includes an exposure lamp 31.
．． First mirror 32. Second mirror 33, third mirror 34.
Lens 35. A fourth mirror 36, a slit 37, etc. are provided. When performing document reading scanning, a first carriage carrying an exposure lamp 31 and a first mirror 32, a second mirror 33, and a third mirror 34 are used so that the optical path length does not change.
and a second carriage carrying the same are mechanically scan driven at a relative speed of 2:1.

This scanning direction, that is, the sub-scanning direction is the left-right direction in FIG. 1, and the sub-scanning start position of the scanning system is at the left end. A reference density pattern PP is arranged at an image reading position near the sub-scanning start position of the scanning system, specifically at a position adjacent to the left of the left end of the lower surface of the contact glass 1. This reference density pattern P
P is a sheet formed with a black pattern having a predetermined light reflectance, and has a length of about 20 mm in the sub-scanning direction.

The lens 35 is a zoom lens, and its magnification can be changed by driving a motor.

Therefore, the light emitted from the exposure lamp 31 is transmitted to the image reading surface (
reference density pattern PP or original), and is reflected by the first mirror 32. Second mirror 33. Third mirror 34. lens 35
．． An image is formed on the photosensitive drum 2 via the fourth mirror 36 and the slit 37.

Around the photosensitive drum 2, there are a main charger 3, an eraser 4. Developing cartridge 5. Toner image sensor PSEN
, a transfer charger 7, a separation charger 8, a cleaning unit 9, etc. are arranged.

The image reproduction process will be briefly explained. The surface of the photosensitive drum 2 is uniformly charged to a predetermined high potential by the discharge of the main charger 3. The charge in the part that is not used for image reproduction is
It is erased by the eraser 4. When the charged surface of the photoreceptor drum 2 is irradiated with reflected light from a document, the potential of that portion changes (decreases) depending on the intensity of the irradiated light. The photosensitive drum 2 rotates in the direction shown by the arrow in the figure, and in synchronization with this, the optical scanning system 30 sequentially scans the document surface, so that the density (light reflectance) of the document image is reflected on the surface of the photosensitive drum 2 A potential distribution corresponding to the distribution, that is, an electrostatic latent image is formed.

When the portion on which the electrostatic latent image is formed passes near the developer cartridge 5, the toner in the developer cartridge 5 is attracted to the surface of the photoreceptor 2 according to the potential distribution, thereby developing the electrostatic latent image. A visible image corresponding to the electrostatic latent image is formed on the photoreceptor drum 2.
formed on top. - On the other hand, recording sheets are fed from one of the five paper feed systems selected in synchronization with the progress of the copy process. This recording sheet is fed through the registration rollers 27 at a predetermined timing so as to overlap the surface of the photosensitive drum 20.

Then, the visible image (toner image) on the photoreceptor drum 2 is transferred to the recording sheet j side by the transfer charger 7, and the recording sheet to which the visible image has been transferred is separated from the photoreceptor drum 2 by the separation charger 8. do. The separated recording sheet is conveyed to a fixing device 12 by a conveyor belt 11. After passing through the fixing device 12, the toner image on the recording sheet is
The image is fixed onto the recording sheet by the heat in the fixing device 12.

The recording sheet that has been fixed is discharged to the sorter 70 or the automatic duplex unit 80 through a predetermined paper discharge path.

In this example, the length of the photosensitive drum 2 in the axial direction (direction perpendicular to the paper surface), that is, the maximum recording width, is approximately the same as the length of the short side of A3 size paper. Therefore, when recording an image smaller than A3 size, such as B4 size,
The remaining area other than the image forming area of 4 sizes is wasted. The remaining area remains at a high potential even after exposure, so if that area is developed as it is, a large amount of toner will adhere there.

In that case, a large amount of toner is wasted and the burden of cleaning increases.

Therefore, the charges in the area other than the image forming area are usually removed by the eraser 4 located upstream of the developer cartridge 5.
It is erased as shown in Figure 3. The eraser 4 is a rod-shaped device in which a large number of light emitting elements are arranged in a line along the entire length of the photoreceptor drum 2 in the axial direction, and erases part or all of the electric charge on the photoreceptor drum 2. can. For example, if the size of the image forming area is 84 size, when the eraser 4 faces the image forming area, all the light emitting elements in the 84 size area of the eraser 4 are turned off, and all the light emitting elements outside of the 84 size area are turned on. When exposed to light from the light emitting element, the charge is erased.

The reference density pattern PP has a length corresponding to the ASR size in the axial direction of the photoreceptor drum 2, and is arranged at the center of the photoreceptor drum 2 in the axial direction. As shown in FIG. 23, the electrostatic latent image formed on the photoreceptor drum 2 during the reading scan of the reference density pattern PP is located in the reference pattern forming area slightly in front of the image forming area. When forming a toner image of a standard density pattern on the photoreceptor drum 2, when the standard pattern forming area faces the eraser 4, all the light emitting elements in the area corresponding to the ASR size of the eraser 4 are turned off, and the standard density is set. Prohibit pattern erasure.

FIG. 2 shows a specific configuration of the developer cartridge 5.

The developer cartridge 5 will be explained with reference to the figures shown in FIGS. 3, 4, 5, 6, 7, 8, and 9.

FIG. 2 is a perspective view of the entire developing cartridge 5. FIG. Second
Referring to the figure, the case end plate 11 of the developer cartridge 5
1 is provided with a U-shaped handle 112. 2, the developer cartridge 5 is attached to the photoreceptor drum 2 from the front side in FIG.
It can be attached to and detached from the main body of the copying machine by pulling it in and out in the axial direction. When attaching and detaching, the developer cartridge 5 is supported by grasping the handle 112. On the copying machine main body side, there is a guide rail 1 arranged along the axial direction of the photoreceptor drum 2.
13 are provided. By sliding the developer cartridge while engaging the guide rail 113 with a downward guide groove 115 formed integrally with the upper case 114 of the developer cartridge, the direction of movement of the developer cartridge when installing and removing it is correct. Regulated. To position the developer cartridge with respect to the photosensitive drum 2, with the developer cartridge 5 inserted into the copying machine main body, the positioning hole 116 provided in the case of the developer cartridge is inserted into the positioning fixing pin 117 on the copying machine main body, as will be described later. Insert the rear end 118 of the support shaft of the developing sleeve into the positioning hole 1 on the copying machine main body side.
19, respectively. The positioned developer cartridge is held at its mounting position by engaging a hook 112a provided at the base of the handle 112 with a retaining protrusion on the copying machine main body side.

FIG. 3 shows an enlarged view of the developer cartridge 5 shown in FIG. Referring to FIG. 3, a non-magnetic developing sleeve 121 containing a fixed magnet group 120 is provided on both end plates of the developing cartridge case. Developer stirring impeller 122. A developer conveying screw 123 made of a spiral strip and a toner replenishing rod 124 having a plurality of parallel vertical grooves 124a on the circumferential surface are each rotatably supported.

A cylindrical case 125 formed on the shoulder of the developer cartridge 5 houses a toner cartridge 126 having a cylindrical body. At both end plates of the toner cartridge 126, a toner replenishment bar 127 is provided at the center of the toner cartridge 126, and the toner supply bar 127 is rotatably supported at both ends. Toner supply bar 127
The rear shaft end of the toner cartridge protrudes from the end plate of the toner cartridge, and as shown in FIG. 4, an engaged member 128 having a sawtooth piece 128a is fixed to the protruding end.

When the toner cartridge 126 is inserted and attached to the developer cartridge 5, the engaged member 128 engages with the engaging member 129 on the developer cartridge side and becomes integrated in the rotational direction.

The engaging body 129 is fixed to the inner end of a shaft 131 of a gear 130 that is mounted on the outer surface of the case of the developer cartridge.

The gear 130 is connected via an intermediate gear 132 to a gear 133 fixed to the shaft end of the toner supply rod 124 .

Gears 134 and 135 are fixed to both shaft ends of the developer stirring impeller 122, and one gear 134 has a gear 136 fixed to one end of the toner conveying screw.
The other gear 135 has a gear 138 fixed to the shaft end of the developing sleeve 121 via an intermediate gear 137.
They mesh with each other. The gear 134 is provided with a knob 139 for manually rotating the developer stirring impeller 122. Each of the gears described above is arranged on the outer surface of the case end plate of the developing cartridge. When the developer cartridge is installed in the copying machine main body, the gears 133 and 138 mesh with the drive gears G1 and G2 on the copying machine main body, respectively, and the gears 130, 132 to 138 are driven to rotate in the direction of the arrow in the figure. Ru.

In FIG. 3, the height of the magnetic brush on the developing sleeve 121 is regulated to a predetermined height by a blade 140 fixed to the developing cartridge case 114. The excess developer scraped off by this blade 140 moves the developer conveying plate 141 to the right in the figure, and as shown in FIG.
1a and falls onto the developer stirring impeller 122.

The developer at one end of the transport plate 141 is
From the hole 143 formed in 41, the conveying screw 123
The developer that falls on one end is transported toward the other end by the transport screw 123, and the receiver is placed in the tray 1.
The developer is returned to one end of the developer stirring impeller 122 from the outlet 145 provided at the end of the developer. A developer conveyance unit 146 consisting of a second conveyance plate 141 containing a toner conveyance screw 123 and a tray 144 is fixed at both ends to the case of the developer cartridge, so that the developer conveyance unit 146 is arranged above the developing sleeve 121 and the developer stirring impeller 122. is supported by

In FIG. 3, the toner supply rod 124 is connected to the hot spring 150.
It is arranged so as to close the lower opening 151 of. A supply rod 124 is provided on both inner surfaces of the lower opening 151 of the hopper 150.
Elongated elastic members 152 and 153 are provided that contact the circumferential surface of. These elastic members 152, 153 are
Made of synthetic resin material. At the top of the hopper 150,
A feeler 154 is swingably provided. The feeler 154 is supported in a cantilevered manner by one end plate of the hopper 150, and as shown in FIG. 8, a boss 156 of an arm 156a is fixed to the outer end of a shaft 155.

The feeler 154 is given a swinging characteristic by the elasticity of a relatively weak spring 158, and the arm 156a is attached to the lever 15.
It is lightly pressed against one end 159a of 9 from below. A bottle 160 is fixed to the other end 159b of the lever 159, and the bottle 160 is pressed against a cam 130a integrated with the gear 130 by the force of a spring 61 acting on the lever 159. The lever 159 is supported by a rod 162 on the outer surface of the end plate of the developer cartridge case.

In FIG. 6, a toner supply port 165 is provided in a part of the cylindrical peripheral wall of the toner cartridge 126, and both end plates 166 and 16 of the toner cartridge 126 are provided with a toner supply port 165.
7 have radial protrusions 166a and 16, respectively.
6c is provided.

A grip tube 166b is integrally formed on one end plate 166, and a lid tube 168 is screwed into it.

Insert the toner cartridge 126 into the case 125 with the protrusion 166a aligned with the groove 125a (FIG. 2) formed on the inner peripheral wall of the cartridge case 125,
With the protrusion 166a completely inserted into the groove 125a,
When the cartridge 126 is rotated counterclockwise in FIG.
are the upper opening of the hopper 150 and the opening 1 of the shirt plate 170.
It communicates via 70a. In this case, the protrusions 166a and 167a engaged with the groove 125a can rotate along a circumferential groove provided in the case 125 and continuous with the groove 125a.

The shirt shirt plate 170 is made of a plastic molded body having reinforcing ribs on its inner surface, and as shown in FIG. 7, protrusions 171 to 174 projecting in the longitudinal direction are integrally provided at both end corners of the shirt shirt plate 170. . These protrusions 171 to 174 are loosely fitted into arcuate grooves (not shown) provided on the inner surface of both ends of the case 125, and are inserted into the opening 1 of the shirt flap plate 170.
10a supports a shutter plate 170 rotatably along the inner wall surface of the case 121 within a range of positions where the upper opening of the hopper is closed and opened.

When the toner cartridge 126 is inserted into the case 125, one protrusion 167a of the cartridge 126 faces the opening of the notch 170b of the shutter Fi 170 within the case, while the protrusion 166 of the end plate 166 of the cartridge faces the opening of the notch 170b of the shutter Fi170.
c faces the right edge 172a of the protrusion 172 of the shirt shirt plate 170. In this state, when the grip tube 166b of the toner cartridge 126 is grasped and rotated counterclockwise in FIG.
First, remove the toner cartridge 1.
26 supply port 165 and opening 170a of shirt shirt plate 170
When the cartridge 126 is rotated further, the shirt flap plate 170 opens at its final position! 7
0a coincides with the upper opening of the hopper 150.

When removing the toner cartridge 126 from the case 125, rotate the toner cartridge 126 clockwise from the state shown in FIG.
The projection 166c pushes the side edge 172a of the projection 172 of the shutter plate 170, rotates the shutter Fi 170 in the same direction, and closes the upper opening of the hopper 150. The cartridge 126 has protrusions 166a and 167a that are connected to the case 12.
It rotates to a position where it matches the groove 125a of No. 5, and is pulled out in the axial direction at that position. Therefore, when the toner cartridge 2.6 is removed from the case 125, the shutter plate 170 closes the opening of the hopper 150.

Referring again to FIG. 2, a light shielding plate 41 is arranged above the developer cartridge 5. As shown in FIG. This light shielding plate 41 is placed in the optical path of the toner color sensor C3EN in a state where the developer cartridge 5 is correctly installed at a predetermined position in the main body of the copying machine. The toner color sensor C3EN includes three sets of transmission type optical sensors each including a light emitting diode and a phototransistor, and is fixed to a guide rail 113 on the copying machine main body side. Four developing cartridges 5 are prepared, each loaded with black toner, blue toner, green toner, and sepia toner. Different light shielding plates are installed. Therefore, the state of the 3-bit electrical signal output from the toner color sensor C3EN changes depending on the toner color in the installed developing cartridge.

FIG. 10 shows an operation board arranged on the top surface of the main body of the copying machine shown in FIG. Referring to FIG. 10, this operation board includes a number of key switches Kl.

K2. 3. 4a, 4b, 5. 6a, 6b,
7. 8. 9a, 9b, 9c, 10, Kll
, 12a, 12b, K13. KC, KS, #, K
l and KT and a number of indicators DI, Dg, Ds,
D4. Ds, Ds, Dg.

Dd, I)p, Dt, De1, etc. are provided.

The various typical key switches provided on the operation board will be briefly explained.

K1 is a key for specifying the operation mode of the sorter 70, and by operating this key, one of the fixed (two-tray use) mode, sort mode, and stack mode can be specified.

K3 is a key for specifying the operation mode of the automatic document feeder 60, and by this operation, one of manual document setting mode, ADF mode, and 5ADF mode can be specified.

K4a and 4b are keys for specifying the front and back margin positions, respectively. 6a, 6b, 9a, 9b and 9c are used to specify the copy magnification.

K7 is used to specify double-sided copy mode.

K8 and Kll are used to specify the document size and paper feed system selection, respectively.

KIO is a numeric keypad and is used for specifying the number of copies, etc.

K12a and K12b are used to specify copy density.

KC is the clear/stop key, and the numeric keypad KIO
This is used to clear the number of copies specified and to instruct to stop the copy operation.

KS is a key for instructing to start printing.

A brief explanation of typical displays provided on the operation board will be given below.

The DI is a 7-segment, 2-digit numerical display, and in normal operation mode, it displays the set copy number when in standby mode.
The number of copies is displayed while copying.

Dg displays the copy density setting state.

Ds displays the paper size, paper orientation, and selected paper feed system for each paper feed system.

D4 is a 7-segment, 3-digit numerical display that displays the copy magnification in units of 1% in the normal operation mode.

Ds displays the specified document size.

Ds is an indicator that displays an abnormality in the sorter, Dg is an indicator that displays an abnormality in paper feeding, Dd is an indicator that displays the cover open state, and Dp is an indicator that displays no recording paper.

Dt is an indicator that lights up when toner runs out. Dem is an abnormality indicator, which lights up when a serious abnormality that should be handled by a service person occurs, but if an abnormality in the surface density of the photoreceptor drum is detected in toner detection processing, which will be described later, the indicator Dem blinks.

Del displays the color of the toner loaded in the developer cartridge 5. In other words, the toner color is black.

For blue, green, and sepia, B, , G, and S are displayed brightly in the symbols, respectively.

FIG. 11 shows an outline of the electric circuit configuration of the copying machine shown in FIG. 1. Referring to FIG. 11, the main control board 200 includes:
Microprocessor 210. Read-only memory (R
OM)220. Read/write memory (RAM) 230. Parallel I10 baud 24O, serial I10 baud) 25
0. A/D (analog/digital) converter 260
and a timer 270. This main control board 200 includes an operation board 310 (see FIG. 10), an optical system control board 320. Lamp control board 3303 Heater control board 340. High voltage power supply unit 350° automatic document feeder 60. Sorter 701 double-sided processing device 80. Paper feed unit 360. Drivers 370, 380 and signal processing circuit 390 are connected.

The optical system control board 320 controls the electric motor M1 for scanning drive of the optical scanning system 30 and the electric motor M2 for adjusting the magnification of the zoom lens.

The lamp control board 330 controls the light amount of the exposure lamp 31 of the optical scanning system 30.

The heater control board 340 controls the temperatures of the fixing heater HTI provided in the fixing device 12 and the drum router HT2 built in the photosensitive drum 2.

The high voltage power supply unit 350 includes the main charger 3, the bias electrode 5a of the developer cartridge 5, and the transfer charger 7.
and generates high voltage power to be applied to each of the separate chargers 8.

Various AC loads (400) are connected to the driver 370, and various DC loads (400) are connected to the driver 380.
10) is connected to the signal processing circuit 390, and various sensors (420) are connected to the signal processing circuit 390.

Specifically, typical AC loads 400 include a main motor that drives the photoreceptor drum 2, etc., a motor for the developer cartridge, and a W! These are a feeding fan motor and a cooling fan motor. Typical examples of the various DC loads 410 are a cleaning control solenoid, a registration roller control clutch, a separation claw control solenoid 2 eraser 4° total counter, a toner replenishment control solenoid, and an oil replenishment control solenoid.

Furthermore, typical sensors 420 include a timing pulse generator that generates pulses synchronized with the rotation of the main motor, a toner image sensor PSEN, a toner color sensor C3EN, and a recording device near the registration roller 27. Registration sensor that detects paper.

These are a paper size sensor and a paper presence/absence sensor provided in each paper feeding system.

FIG. 21 shows a specific circuit for the toner concentration sensor PSEN. Referring to FIG. 21, PSEN is composed of a light emitting diode and a phototransistor, and the anode of the light emitting diode is connected to a power supply line (+5V), and the cathode is connected to a light emitting diode lighting circuit. The light emitting diode lighting circuit includes a reference voltage circuit consisting of R, ZD, a D/A converter DAC, /'+, R1
, R3.

It is composed of a constant current circuit made of Trl. The DAC is connected to data buses D0 to D7 of the main control board 200, and by writing digital data to the DAC, the current of the light emitting diode can be set, thereby changing the amount of light emission and adjusting the output of the phototransistor. The DAC divides the reference voltage applied to the OUT terminal according to the digital data written through D0 to D, and outputs V RE
Output to F terminal. The constant current circuit causes a current proportional to the voltage at the VIIEF terminal to flow through the light emitting diode. The light emitting diode of PSEN is turned on/off by digital data written to the DAC. When on, a predetermined value determined by adjustment is given as digital data, and when off, it is "0".
give. The output terminal or emitter of the phototransistor is connected to the analog input port Pi of the main control board 200.
It is connected to the input terminal of the A/D converter 260 in the main control board 200 via n.

FIG. 22 shows the relationship between the density of the toner image formed on the photosensitive drum 2 and the output voltage of the sensor PSEN that detects the image density. Referring to FIG. 22, it can be seen that the output level of the sensor PSEN decreases as the image density increases. Furthermore, it can be seen that the correlation between the image, image density, and the output level of PSEN changes depending on the color of the toner used.

FIG. 12(a) shows a part of the memory map of the main control board 200 and the same figure (bl, (C1 has FGPSE and FGP
An explanatory diagram of the SEI area is shown, Fig. 13 shows an outline of the processing contents of the soil control board, Fig. 14, Fig. 15
6, FIG. 17, FIG. 18, FIG. 19, and FIG. 20 show in detail some of the processes included in the process of FIG. 13.

First, refer to FIG. 13. When the power is turned on, CPU initialization processing in step SAI is first performed. In this process, the state of the main control board 200 itself is initialized. That is, read/write memory (RAM) 2
Clears the contents of 30, initializes various mode settings, and resets the output boat. Next, the initial setting process of step SA2 is performed. In this process, the states (operation modes) of various boards and devices connected to the main control board 200 are initialized, and the copying machine is set to its initial state. It also sets the mode and count value of the timer 270.

In step SA3, standby mode processing is performed.

At this point, the copying operation is stopped and the copying machine is in a standby state. In this process, the following process is performed. First, the states of signals applied to various input ports are read and the results are stored in the memory 230. Next, output control data groups stored in the RAM 230 in advance are output to output ports associated with each data.
Control devices connected to that output boat. Furthermore, the status of various input ports read in advance and stored in the RAM 230 is determined, and the presence or absence of an abnormality is checked. If there is an abnormality, predetermined abnormality processing is executed. If there is no abnormality, the status of other input ports is determined and, for example, input from the operation board 310 is processed.
A mode switch (D
The state of the IP switch (not shown) is determined, and the content of subsequent processing is determined according to the result. Next, it is determined whether there is key human power or not, and if there is key human power, processing is performed in accordance with that key human power. For example, in normal operation mode, if there is an input from the numeric keypad KIO,
Stores the numerical value associated with the pressed key in the copy number register. Further, when input from the magnification adjustment keys 6a, 6b, etc. is received, a magnification adjustment instruction signal is sent to the optical system control board 320.

Further, the display data stored in the RAM 230 in advance is output to a predetermined output boat at a predetermined timing, and the data is displayed on various displays on the operation board 310. The data to be displayed is switched depending on the state of the mode switch.

If normal operating mode is specified, display D
1 displays the number of copies, and display D4 displays the copy magnification.

If copying is not possible or if the print start key KS is not turned on, the standby mode processing described above is repeatedly executed (step 5A31). Copying is not possible if, for example, the fixing temperature is outside a predetermined range or if some abnormality is detected.

When the print start key KS is pressed in the copy-enabled state (step 5A3-2), the pre-copy mode process of step SA4 is executed. In this processing, as processing immediately before starting the copying process, a pre-copying cleaning process for the photosensitive drum to start driving the main motor, a paper feeding process, etc. are performed.

When step SA4 is completed, copy mode processing of step SA5 is executed. At this point, the copy process is actually executed. This process includes copy process processing,
This includes paper transport processing, toner replenishment processing, abnormality check processing, etc. In the copy process, various process elements are controlled on/off at predetermined timings synchronized with output pulses from a timing pulse generator that generates pulses corresponding to the amount of rotation of the main motor. If a plurality of copies are to be made continuously, the copy mode process of step SA5 is repeatedly executed (step 5A5-1).

When the copy mode process of step SA5 is completed for the final copy, the copy mode process of step SA6 is executed. In this process, the paper on which the copied image has been transferred is ejected, the photosensitive drum is cleaned after copying, and so on. When the paper discharge is completed (step 5AG-1), the process returns to the standby mode process of step SA3 and the above process is repeated.

The density check process for creating a toner image of the base medium density pattern PP on the photosensitive drum 2 is included in the copy process process of the copy mode process SA5.

The contents of this process are shown in FIG. This will be explained with reference to FIGS. 17 and 23.

This process is executed while referring to the contents of the timing pulse counter T2 that counts the output pulses of the timing pulse generator.

When the timing pulse counter Tp reaches 85, check the flag Fpm (step 5E1) oFpo
+ is 1" (step 5E2), the eraser 4 is controlled so that charges only outside the A S RH region are erased (step 5E3). In this example, the flag Fpn+ is set for the copy process. 1 out of 10 times “
It is set to "1" and reset to "0" at other times.

When the timing pulse counter Tp reaches 106 (step 5E4), the eraser 4 is controlled to erase charges in the entire area (full width) (step 5E5).
). Note that even when Tp is less than 85, the setting is made so that the entire width of the charge is erased.

Therefore, when the content of Tp is between 85 and 106, charge erasure in the reference pattern forming area is prohibited, so that a toner image corresponding to the reference density pattern PP is formed in that area. In this example, the content of counter Tp is 8.
The timing between 5 and 106 corresponds to approximately 20 mm of length on the photoreceptor drum surface.

However, since the flag Fp is set to 1'' once every 10 times in the copying process, the toner image of the standard density pattern is actually formed on the photoreceptor drum every 10 times.
Only once per copy.

When the timing pulse counter TJ) reaches 125 (step 5E6), the flag Fpa+ is checked (step 5ET). When Fp- is “engine”, the sensor PS
Turn on the EN light emitting diode and set the flag F pon to “
1” (step 5E8), flag F per
Set to l” and start the 3m5ec timer (
Step 5E9). As a result, from now on, the interrupt processing INTT3 shown in FIG. 14 is executed every 3m5ec.

When the timing pulse counter Tp reaches 1038 (step 5RIO), the light emitting diode of the sensor PSEN is turned off and the flag F pon is reset to O'' (step 5EII).

Next, the timer interrupt processing INTT3 shown in FIGS. 14, 15, and 16 will be explained.

In this process, the flag F pcr is first checked (
Step 5BI), the flag F per is set to '1' when step SE8 in FIG. 17 is executed.
If pcr is "1", then the flag F-- pon is checked (step 5B2). This flag F pan also
It is set to "1" in step SE8 of FIG.

If the flag F pon is 11", the process of step SB3 is executed. In this process, the data obtained by A/D converting the output signal level of the sensor PSEN is processed. is stored in register DBINF shown in FIG.

Then, in step SB3, each register WDVSG?
, WDVSG6. WDVSG5. WDVSG4. WDV
, SG3. WDVSG2. Wl) VSGl, WDVSP
8. WDVSP? , WDVSP6°WDVSP5. W.D.
VSP4. WDVSP3. WDVSP2. WDVSPI
and the contents of DBINP in register WDV, respectively.
SG8. WDVSG? , WDVSG6. WDVSG5.
WDVSG4. WDVSG3. WDVSG2.
WDVSGl, WDVSP8. WDVSP? ,
WDVSP6゜WDVSP5. WDVSP4.
WDVSP3. WDVSP2 and WDVSP
Transfer to I in order.

Therefore, when the process of step SB3 is repeated, register WDVSG8. WDVSG? , WDVSG6. W.D.
VSG5. WDVSG4. WDVSG3. WDVSG2
．． WDVSGI, WDVSP8. WDVSP7. WDV
SP6. WDVSP5, WDVSP4. WDVSP3.
Latest, past 16 for WDVSP2 and WDVSPI
The data obtained from each batch of sampling is stored. Note that in this example, one piece of sampling data is composed of 8 bits.

Next, check the counter CNchv (step 5
B4). This counter CNchv detects the switching of the output level of sensor PSEN from Vsg to Vsp (24th
(see figure).

Initially, CNchv is 0, so the next step S85
Proceed to. Then, the latest sampling data, namely D
The contents of BINP are compared with a fixed value Vch. This value V
As shown in FIG. 24, eh corresponds to an intermediate level between the normal Vsg level and Vsp level.

Here, the voltages Vsg and Vsp correspond to the light reflectance of the surface of the photoreceptor drum and the light reflectance of the toner image of the reference density pattern formed on the photoreceptor drum, respectively.

Immediately after the start of density measurement, a position upstream of the reference pattern forming area (see FIG. 23) on the photosensitive drum faces the sensor PSEN.

At that position, the charge is erased by the eraser 4 and toner does not adhere even after passing through the developing section, so the sensor PSEN detects the light reflectance of the surface of the photoreceptor drum 2 at that timing. In that case, the output level of sensor PSEN is usually about 4V. Therefore, D.B.
Since INF>Vch, the counter CNchv is cleared to 0 in step 5BII.

While DBINF>Vch, this timer interrupt processing I
Every time NTT3 is executed, counter C is set in step 5BII.
Since Nchv becomes O, the process advances to step SB5 after step S84.

When DBINP:5Vch is reached, the counter CNchv is incremented in step SB6, and the next step S
Proceed to B7s When CNchv≧3, that is, DB
After sampling is performed three times after INF≦Vch, the process advances to step SB8.

In step SB8, the data buffer (register WDV
SG8~WDVSGI and WDVSP8~WDVSP
The oldest 8 data out of the 16 sampling data existing in I), that is, the cash register, 1WDVsG8~
The average value is calculated using the contents of WDVSGI. The calculation result is stored in the Vsg average value register M_vsg.

Further, the calculation result is stored in a predetermined display register, and the average value of Vsg is displayed on the display D1.

However, it is actually displayed when that display mode is selected by the DTP switch.

Next, the process proceeds to step SB9, where the contents of the register M_vsg and the fixed value Vch are compared. Since the average level corresponding to the light reflectance of the photoreceptor surface is normally stored in the register Mvsg, Mvsg > Vch. In this case, step 5B19 is executed and counter CNe5l is cleared. Due to the occurrence of some abnormality, Mvsg < Vch
If this happens, it is considered abnormal and the next step 5BIO
Execute. In this process, the abnormality flag F amp is set to “
1" and flags Fpct and F pon to "
0', the sensor PSEN is turned off, and the counter CNe5l is incremented in step 5B20.

If this abnormality occurs continuously in X-output (step 5B)
21), step 5B22 is executed. Flag Fau
tl is for remembering that automatic adjustment has been executed, and if it has already been adjusted (if Fautl = 1), execute step 5B25 and display the abnormality indicator Dew.
will be displayed blinking. If Fautl=0, then 1. Step 5
Set Fautl and Faut2 to 1 in B23.24. Flag Fout2 instructs execution of automatic adjustment, and is checked in the flow shown in FIG. 20, which will be described later.

Step 5I after the value of counter CNchv becomes 3
After executing step 34, the process proceeds to step 5B12. Then, the contents of the counter CNcvsL are decremented.

The counter CNcvst contains the following information when starting concentration measurement.
1G is set as the initial value.

When the result of decrement is O (step 5B13)
That is, after the value of the counter CNchv reaches 3, the timer interrupt process INTT3 is executed 16 times, and the process advances to the next step 5B14. In that case, the 16 Vsp data obtained through 16 samplings are stored in registers WDVSG8 to WDVSG I and WDVSP8 to W
DVSP IC stored.

In step 5B14, the flag F pcr is reset to "0" to set the end of the concentration measurement process.

In the next step 5B15, the new past 8 existing in the 8-byte buffer registers WDVSP8 to WDVSPI is
The average value is calculated using the zumbling data of each batch, and the result is stored in the register M vsp as the Vsp average value.
Store in. Further, the average Vsp value is stored in a predetermined display register, and the average value of Vsp is displayed on the display D4. However, it is actually displayed in the above D.
This is the case when the display mode is selected by the IP switch.

Next, the process proceeds to step 5B16, where the contents of the register Mvsp and the fixed value Veii are compared. The fixed value Vew is set to a relatively high level compared to the normal Vsp level. Therefore, if there are no special abnormalities,
Since Mvsp < Vea+, the next step 5B
17 toner replenishment control is executed, and further step 5B1
Proceed to B and set the toner replenishment prohibition flag Ftdl, Ft
d2, )ner supply flag F tri, Ftr2
, Ftr3 and the abnormality flag F emp are reset to 01.

The contents of the toner replenishment control in step 5B17 above are explained in the 18th step.
Referring first to FIG. 18, FIG. In this process, first, output information from the toner color sensor C3EN is determined to identify the toner color in the developer cartridge. i! ! If the other result is black toner (step SF l
) , compare the contents of Mvsg with a value 8 times the contents of Mvsp (step SF 2 ), Mvsg >
8 ・If Mvsp, set toner replenishment request flag Ftr to 0"
If not, the flag Ftr is set to 1'' (step 5F3).Similarly, if the identification result is blue toner (step 5F4), the contents of Mvsg are Contents 2.
It is compared with the double value (step 5F5).

If Mvsg>2.2・Mvsp, reset the toner replenishment request flag Ftr to "0" (step 5F6); otherwise, set the flag Ftr to 1" (step 5F3). If the identification result is green toner ( Step SF 7), compare the contents of Mvsg with twice the value of the contents of Mvsp (Step 5F8). Mvsg>2
- If Mvsp, reset the toner replenishment request flag Ftr to "0" (step 5F6), otherwise set the flag Ftr to "l" (step 5F3). Also, if the identification result is sepia toner (step 5F6), set the flag Ftr to "l" (step 5F3). SF
9) , change the contents of Mvsg to 1.8 of the contents of Mvsp.
Compare with double value (Step SF 10) e Mvs
g > 1.8 ・If Mvsp, toner replenishment request flag F
tr is set to O” (step 5F6), otherwise the flag Ftr is set to 16 (step 5F6).
F3).

When the toner replenishment request flag Ftr is set to ``1'', the toner replenishment solenoid is energized at a predetermined timing for a predetermined period of time, and the toner in the toner cartridge 126 is replenished into the hopper 150. Stationary replenishment takes place (not shown). When this quantitative replenishment is completed, the flag Ftr is reset to "01".

That is, in this example, the ratio between the light reflectance of the surface of the photosensitive drum 2 and the light reflectance of the toner image of the reference density pattern formed on the dual photosensitive drum 2 is determined in a binary manner. Performs on/off control of quantitative replenishment. This type of developer concentration control is not affected by dirt on the detection surface of the toner image sensor PSEX, variations in the positional relationship between the sensor PSEN and the photoreceptor drum 2, and so on, so that stable control can be achieved.

Next, the processing procedure will be explained with reference to FIG. In this process, first, the contents of Mvsg are compared with fixed values VA and VB (step SGl, step 5G2
). These fixed values are values for determining whether Mvsg is appropriate, that is, within a normal range, and VA is the upper limit value and VB is the lower limit value. In this example, V
A is 4.5V.

VB is set to a value corresponding to the voltage of 3.

If Mvsg>VA or Mvsg<V13, it is considered that there is an abnormality, and the process proceeds to step SG8 where the counter CN is
Increment em2. If this abnormality occurs continuously on X collection (step 5G15), step 5G16
is executed. This step is similar to step 5B22 and subsequent steps in FIG. 14, and if the flag Fautl=1, step 5G19 is executed and the abnormality indicator Dew is displayed blinking.

If flag F autl =0, step 5G17.
At step 18, Fautl and Faut2 are set to 1 and execution of automatic adjustment is instructed.

If VB≦Mνsg≦VA, the process advances to step 5G20 and the counter CNem2 is cleared. Next step S
Proceed to G3 and compare Mvsg and -Mvsp. Here, K is a coefficient set depending on the toner color, and in this example, it is set to 4 for black toner. In the case of black toner, in this example, Mvsg=8・Mv
It is controlled so that sp. Therefore Mvsg
<K-Mvsp, it is quite different from the target state, and it is considered that the concentration of the developer is quite low.

When Mvsg < K-Mvsp, step SG4
Then, check the toner end (empty) check flag Fcte. Fcte is 0 in the initial state
”, so in that case, proceed to step SG5 and F
Set cte to "1". Furthermore, in step SG6, the contents of the register Mvsp are stored in the register PAν3p, and in step SG7, the toner end counter CNte is stored.
Set 1 to .

After this, when the process of FIG. 19 is executed again, the flag Fc
Since te is "1", the process advances to step SG9 after step SG4.Furthermore, the flag Fpcr is set to "1" at a predetermined timing once in ten copy operations, and as shown in FIG. When you execute step 5B14 of
”, toner supply control (SB17)
is performed only once in ten copy operations. In other words, when it is determined that the developer concentration is low and toner is replenished, step SG9 is executed after toner is replenished and after copying for 10 sheets has been performed.

In step SG9, the previous value of Mvsp stored in the register PAvsp and the current value of Mvsp are compared. If PAvsp>Mvsp, that is, if the developer concentration does not increase even after toner replenishment, the content of the toner end counter CNte is incremented (step 5GIO). Then, the contents of the counter CNte are compared with a predetermined value N (step SG
l 1), when CNte>N'(Na3), the display Dt is lit to indicate that the replenishment toner is used up (
Step 5G12).

If P Avsp > Mvsp before CNte > N, proceed to step 5G13 and set the flag Fctθ to “
The toner end counter CNte is reset to 0' and cleared to O in step 5G14.

If Mvsp>Vex at step 5B16 in FIG. 14, the process proceeds to FIG. 16. This will be explained with reference to FIG.

First, in step SDI, the toner replenishment prohibition flag Ftdl is set.
Check. If F Ldl is 1″, the 14th
Proceed to step 3810 in the diagram. If FLdl is “0”,
Next, check the toner replenishment request flag FLr2 (
Step 5D2).

If F_Lr2 is "0", then check the toner replenishment request flag F_tri (step 5D3), F_Lr2.
If rl is 0', set it to “l” (step 5
D7) Proceed to step SD6 and change the contents of Mvsp to PAv.
sp and set the toner replenishment request flag Ftr to “l”
, and proceed to step 5BIO in FIG. If F tr l is “l” in step SD3, register P
The contents of Avsp and Mvsp are compared (step 5D4). If PAvsp≦Mvsρ, proceed to step SD5 and set the flag F Lr2 to 1″.
In step SD6, the contents of M vsp are further changed to PAvsp.
Then, the toner replenishment request flag Ftr is set to "1" and the process proceeds to step 5BIO in FIG. If PAvsp > Mvsp in step SD4, step SD9
The process proceeds to step 5BIO of FIG. 14, where the flags FtrL and Ftr2 are reset to "0".

If the flag Ftr2 is l'' in step SD2, the process proceeds to step SD8, where PAvsp and Mvsp are compared.If PAvsp > Mvsp, the process proceeds to step SD9, where the flags Ftrl and FLr2 are reset to 0'', as shown in FIG. Proceed to Step 5 BIO.

If PA and vsp≦Mvsp in step SD8, the toner replenishment request flag Ftdl is set to “1” in step 5oto.
, and proceed to step 5BIO in FIG.

At step SB2 in FIG. 14, the flag F pon is set to “O”.
If so, the process proceeds to the process shown in FIG. Note that this process is executed after the density measurement starts and before the reference density pattern (toner image) is found.
This is the case when the flag F pon is reset when P=1038), that is, when a toner image of the reference density pattern is generated on the photoreceptor drum but cannot be detected.

This will be explained with reference to FIG. First, store the maximum value FFh (hexadecimal display) in the Vsg display register, display that Vsg is abnormal on the display DI (step 5CI), and then check the toner replenishment prohibition flag Ftd2 ( Step 5C2).

If F td2 is 11, immediately proceed to step 5B in Figure 14.
Proceed to IO.

If the flag Ftd2 is "0", the process advances to step SC3 and the toner replenishment request flag Ftd3 is checked. If the flag F Lr3 is "01", set it to "11" (Step 5C4),) Set the toner replenishment request flag FLr to "
1'' (step 5C6) and proceed to step 5BIO in FIG.

If the flag F Lr3 is "1" in step SC3, the toner replenishment prohibition flag Ftd2 is set to "1" (step 5C5), and the toner replenishment request flag Ftr is set to 1.
'', step 5C6), and proceed to step 5BIO in FIG.

The process shown in FIG. 15 is a process of monitoring whether an abnormality occurs continuously when an abnormality is detected in step SB2. Toner is replenished up to two times, but if an abnormality occurs three times in a row, toner is not replenished thereafter.

Further, the process shown in FIG. 16 is executed when the toner image of the reference density pattern can be detected, but the detected pattern density is too low. In this process, toner is replenished when it is determined that the toner is light (first time), and when the toner is not darker than the previously detected density at the second check timing, toner is replenished again and the third check is performed. If the density does not become darker than the previously detected density at the timing, that is, if an abnormality is detected three times in a row, it is assumed that there is a complete abnormality and toner replenishment is prohibited.

FIG. 20 shows the contents of the automatic adjustment process that is executed when the flag Fout2=1. This will be explained with reference to FIG. Although this process (TUNING) is different from INTT3, it is executed by a similar interrupt process using a 3 ms timer.

First, when it is determined in step SHI that Faut2=1 and further in step SH2 that the PSEN detection portion is determined to be a non-image area, an adjustment operation is executed. The non-image area can be determined based on, for example, the time elapsed since the exposure of the original was completed.

At step SH3, the flag Faut3 is checked. In the initial state, Faut3 is O,
Here, if FauL3=0, proceed to step S H4
Set ut3 to 1, and in step SH5 PSE
The amount of light emitted from the N light emitting diodes is initialized.

That is, the value of digital data D given to the DAC that determines the amount of light emission and the amount of change ΔD during adjustment are set to 128. This value was determined because the DAC is 8 bits, and is half the maximum value (256/2).

Then, PSEN is turned on by writing D to the DAC. When step S H3 is executed at the next timing, Faut3 is 1, so step S H
Proceed to step 6. In steps 2 and 2, the output of PSEN is sampled and stored as Vsg (since a non-image area is detected, its value is Vsg).

When a predetermined number (N in this case) of data is collected, the average value is calculated and stored in the MVsg (steps SH7, 8, 9,
10). Next, in step 5HII, the change in D Δ
Reduce D to 1/2. Further, in step 5H12, if ΔD is smaller than 1, it is impossible to change it any more, so step 5H17 is determined to be the end of the adjustment.
Proceed to and test the value of MvsB.

If the value of Mvsg is within the range of the target value ±α, it is assumed that the adjustment has been completed normally, and the process proceeds to step S H18.
Faut2. Reset Fout3 to 0 and clear counters CNem1+CNem2 to 0. Next, the process proceeds to step 5H19 and PSEN is turned off by writing O to the DAC. Of course, the adjusted data D is R
It is saved in AM. In step Sfi17, if Mvsg is outside the above range, it is determined that PSEN has been turned on because it cannot be adjusted for three cycles), and it is determined that PSEN is broken, and an abnormality is displayed in step SH20.
After blinking, proceed to steps 5H18 and 19.

If ΔD is 1 or more, steps S H12 to 5H1
Proceed to step 3 to determine whether M vsg matches the target value.

If they match, it is assumed that the adjustment has been completed normally and proceed to step 5.
Proceed to H18, 5H19. If it still does not match the target value, it is determined whether Mvsg and the target value are large or small in step 5H14. If it is larger than the target value, in step S H15, D is subtracted by ΔD and written to the DAC. As a result, the current of the light emitting diode of PSEN decreases, and Vsg decreases. Conversely, if this is smaller than the target value, D is increased by ΔD in step 5H16 and written to the DAC.

By changing D in this way, Vsg is automatically adjusted to the target value.

Note that the RAM 230 in the main control board 200 is backed up by a battery, and the adjustment values are stored therein, so that the adjustment values are not lost even if the power to the copying machine is turned off.

〔Effect of the invention〕

As explained above, according to the present invention, the toner concentration sensor is made automatically adjustable, and the automatic adjustment is performed to correct dirt before displaying an abnormality. Therefore, the frequency of maintenance is reduced. It is possible to provide a method for adjusting a toner concentration detection device that is capable of detecting toner concentration that is not easily affected by dirt.

[Brief explanation of drawings]

Figure 1 is a front view showing the inside of a type of copying machine for carrying out the present invention, and Figures 2 and 3 are a developing car, respectively.
The perspective view and longitudinal cross-sectional view of the IJ screw, and FIGS. 4, 5, 6, and 7 respectively show the internal drive system, developer conveyance unit, toner cartridge, and shutter plate of the developer cartridge shown in FIG. 8 is a perspective view showing a part of FIG. 4 in detail, FIG. 9 is a longitudinal sectional view of one end of the toner cartridge, and FIG. 1O is a plane showing the operation board of the copying machine shown in FIG. 11 is a block diagram showing an outline of the electric circuit configuration of the copying machine shown in FIG. figure. Fig. 14, Fig. 15, Fig. 16, Fig. 17, Fig. 18,
19 and 20 are flowcharts showing the general processing procedure of the main control board in FIG. 11, FIG. 21 is an electric circuit diagram showing the toner image sensor, and FIG. 22 is the relationship between the output level of the sensor and the image density. FIG. 23 is a timing chart showing the relationship between the process control timing and the position of the electrostatic latent image on the photosensitive drum, and FIG. 24 is a waveform chart showing the signal waveform output from the sensor. 1... Contact glass, 2... Photosensitive drum (charge carrier), 3... Main charger, 4... Eraser, 5... Developer cartridge (developing means), 7...
Transfer charger, 8... Separation charger, 12...
Fixing device, 21-24...Paper feed cassette, 25...Paper feed tray, 30...Optical scanning system (exposure means), 31.
. . . Exposure lamp, 41 . . . Light shielding plate, 60 . Developing sleeve, 122...Developer stirring impeller, 123...
...Developer conveyance screw 124...Toner supply rod (
toner supply means), 125... case, 126...
Toner cartridge, 127... Toner supply bar, 2
00...Main control board (electronic control means), C3EN・
. . . Toner color sensor (color detection means), PP . . . Reference density pattern (reference pattern), PSEN . . . Toner image sensor (optical detection means) DI to D5. Ds, Dg, Dd
, Dp, Dt, Dcl...display device, Den...display device (abnormality display means). Figure 8 Figure 1O KIC) GS Funeral Figure 12 Hanging figure Figure 15 Figure 16 Figure 21 Figure 22

Claims (1)

[Claims] In a method for adjusting a toner density detection device, in which a toner image of a reference density pattern is previously formed on a photoreceptor before image formation, and the toner density of this toner image is detected by a toner density sensor consisting of a reflective photosensor. A method for adjusting a toner density detection device, characterized in that the background density of a photoconductor near a toner image is detected simultaneously with density detection, and the adjustment of the toner density detection device is automatically executed based on the detected value.