JPH0371173A - Copying machine - Google Patents

Abstract

PURPOSE:To make it possible to form a reference toner image of minimum size required and to suppress the consumption of toner by optionally setting up the measuring position of a sensor in the direction rectangular to the image forming direction of a photosensitive body. CONSTITUTION:An electrostatic latent image corresponding to the half tone image of a seal 25 is formed on the exposure area X2 of the photosensitive drum 3 by stopping an exposure unit 24 on a position Z and exposing the seal 25 and a toner image is formed by developing the latent image in the developing area X3 of a developing unit 6. The toner image is directly carried from the developing area X3 to an area X5 without executing the carriage of copying paper and the driving of a transfer charger 7 and a separating charger 8 in a normally copying process and the density of the image is measured by a measuring sensor 11. The sensor 11 can be moved in the major axis direction of the drum 3 to be the 2nd direction rectangular to the 1st direction to be the rotational direction of the drum 3, so that the density of the toner image in the area X5 can be measured on an optional position in the 2nd direction.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an electrophotographic copying machine, and more specifically, in order to prevent image deterioration, the density of an L/ner image is measured,
The present invention relates to a device for correcting image density.

[Prior art]

In copying machines, charging defects may occur on the photoconductor due to dirt on the charger's charging wire, charging grid, etc. due to long-term use, surface deterioration of the charging wire, or uneven characteristics of the photoconductor. Deterioration of the system's exposure lamp or ξ. Exposure defects may occur due to contamination of the lens or the like.

When these defects occur, the image that is actually copied becomes blurred, or conversely, excess toner is deposited on the copy, resulting in so-called background tearing, which is undesirable.

Therefore, in order to prevent this, the present applicant formed a latent image as a reference on the photoreceptor before copying the original and developed it into a color image, and detected the density of the image. proposed a device that automatically adjusts the voltage value of an exposure lamp based on the density (for example, Japanese Patent Laid-Open No. 63-223762
Publications, etc.).

[Problem to be solved by the invention]

By the way, in order to detect the density of a toner image in a device such as a double series, for example, in the case of a photoreceptor drum, it is necessary to arrange the photoreceptor drums at the central position in the longitudinal direction and face each other. This is generally done using an agricultural sensor.

However, the width of the toner image formed on the photoreceptor drum is the same as the width in the longitudinal direction of the tram. , the toner is completely wasted, which is very uneconomical.

Furthermore, the measured value uses the value at one fixed location as the representative value in the longitudinal direction of the photoreceptor drum to adjust the image density. In some cases, it is not possible to correct the image density in areas other than the measured values.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a copying machine capable of determining the density of a toner image at any position without wasting toner.

[Means to solve the problem]

The copying machine according to the present invention has a first copying machine corresponding to an image scanning direction.
In a copying machine that forms a toner image on a photoconductor that is moved in a direction, the density of the toner image is measured by a sensor, and the image density is adjusted based on the measurement result, the measurement position of the sensor is measurement position setting means for setting an arbitrary position on the photoreceptor in a second direction perpendicular to the first direction; and a second part of the photoreceptor corresponding to the measurement position set by the measurement position setting means. The first invention is characterized by comprising means for forming the reference toner image in a part of the direction, and forming the reference toner image on the photoreceptor in a second direction perpendicular to the first direction. A toner image forming means for arbitrarily setting the width or position, and means for setting the position in the second direction of the reference toner image forming means set by the l-toner image forming means as the measurement position of the sensor. The second invention is characterized by:

[Function] In the copying machine of the first invention, when the measurement position of the sensor is set at a certain position on the photoreceptor in the second direction, a reference toner image is partially formed corresponding to this position, and the density is increased. but'/
J111 is established.

In the copying machine of the second invention, the reference 1 to color images are transferred to the second image on the photoreceptor.
When the reference toner image is formed at a certain width or position in the direction, the measurement position of the sensor is determined corresponding to this reference toner image, and the density is measured.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof. Figure ↑ is a schematic diagram showing the general configuration of a copying machine according to the present invention. Below the document platen glass l is the exposure unit I-24. An optical system 20 including mirrors 22b to 22d, a lens 23, etc. is provided.

The exposure unit 24 includes an exposure lamp 21 and a mirror 22a, which are long in the depth direction of the original platen glass 1, and scans the original M by moving in the direction indicated by the arrow orthogonal to the depth direction of the original platen glass 1 during a copying operation. The light reflected from the document M illuminated by the exposure lamp 21 by the exposure unit 24 is
It is reflected by the mirror 22a and sent in the opposite direction to the direction indicated by the arrow, reflected again in the same direction as the direction indicated by the arrow 221) and 22c, and reflected by the mirror 22d via the condensing lens 23. The photoconductor drive J reaches above 3,
image here.

Further, when measuring the toner image density according to the present invention, the exposure unit 24 is moved and stopped below the main body upper cover 26 provided on the side of the document platen glass 1. . At this stop position Z, the exposure unit 24
is a sticker 25 affixed to the bottom surface of the main body-F section cover 26
to expose. This seal 25 is a gray test char for forming a halftone toner image.

A charger 4 is provided below the optical system 20,
The charging charger 4 uniformly charges the opposing regions xl of the photoreceptor drums 1 and 3''. The driving force of the main motor 210 drives the photoreceptor I/ram 3 through gears 31 and 32 (both second
(see figure), and rotates in the direction of the arrow a, which is the first direction, in synchronization with the movement of the exposure unit 24 in the direction of the arrow.

Photosensitive drum 3 on the downstream side in the drum rotation direction of the area X1
Two exposure areas by the optical system 20 are formed above. The scanning light of the original image by the optical system 20 is guided to this region x 2 via the optical path B described above, thereby forming an electrostatic latent image corresponding to the original image.

Here, the unnecessary inter-image charge other than the electrostatic latent image corresponding to the original image, that is, the charge between the image currently being copied and the image to be copied next, can be removed by using the LED array. It is erased by the eraser 5. The electrostatic latent image is supplied with toner and visualized in a developing area X3, which is a portion facing the subsequent developing device 6, and a toner image reproducing the original image is formed.

On the other hand, the copy paper is moved opposite the transfer charger 7 by a pair of tie guiding rollers 15 in synchronization with the timing at which the I/toner image formed on the photosensitive drum 3 moves from the development area x 3 with the rotation of the tram. (transfer area X4). Here, the toner image is transferred to the copy paper, separated from the photosensitive drum 3 by a separation charger 8, and then conveyed to a fixing device (not shown), where the toner image is fused and fixed onto the copy paper.

After the transfer of the L. toner image, the surface of the photosensitive drum 3 is cleaned of residual toner by a cleaning device 9, and further, the residual charge is erased by light irradiation from an eraser lamp 10, and the drum is prepared for the next development.

Next, a toner image density detection mechanism, which is the gist of the present invention, will be explained. FIG. 2 is a schematic diagram showing the configuration and arrangement of the concentration sensor. The density sensor 11 is located in an area X between the transfer area X4 of the photoreceptor tram 31 and the area where the cleaning device 9 is provided.

A reflective photosensor is used, which is arranged to face the light emitting element 11a and the light receiving element 1.1b. The measured I/toner image will be described in detail later, but first, the exposure unit 24 is stopped at position Z and the sticker 25 is exposed, thereby forming a halftone of the sticker 25 in the exposure area X2 on the photoreceptor drum 3. It is formed by forming an electrostatic latent image corresponding to the image and developing it in the development area X3 of the developing device 6. This 1-toner image can reach the area X5 from the development area χ3 as it is by not carrying out the general feeding of the copy paper in the normal copying process and driving the transfer charger 7 and separation charger 8. , here the concentration is measured by the concentration sensor 11. A drive pulley 44 and a driven pulley 42, which are driven by a motor 40 that can be rotated forward and backward, are provided at positions on the back side and front side of the copying machine from both ends of the photosensitive drum 3, respectively, and the drive pulley 44 and the driven pulley 42 are stretched between these pulleys. The concentration sensor 11 is attached to the wire 41. In other words, in the concentration sensor ■1, the driving pulley 44 is connected to the motor 4.
0, it is movable along a rail (not shown) in the axial direction of the photoconductor tram 3, which is a second direction orthogonal to the first direction, and a 1-ner image of area x 5 is rotated. The density can be measured at any position within the image area.

A lever 47 for setting the home position Y1 of the concentration sensor 11 is provided near the driven pulley 42. When the concentration sensor 11 is at the home position Y1, pressing the lever 47a of the limit 47 , ri plane noto isochi 47 is CPII which will be described later.
The home position detection signal Sp of the density sensor 11 is output to 201.

Further, the motor 40 has a built-in pulse generator, and the pulse generator outputs one pulse signal Pm to the CPU 201 for each predetermined amount of rotation.

FIG. 3 is a Bronnock diagram of the control system, in which the concentration sensor 1
1 is connected to a predetermined port of the CPIJ 201 which controls the copy operation via the A/D converter 203. The output voltage Vd of the concentration sensor 11 is converted into a digital signal by the A/D converter 203 and input to the CPU 201 . FIG. 4 is a graph showing the relationship between the output voltage Vd and the density of the toner image of the density sensor 11. In the sensor 11, the intermediate value of I-toner image density is 0.5, that is, 2.5 for a halftone image. 5 V should be output ↓
It's happening.

Further, a pulse signal Pm emitted from the pulse generator of the motor 40 for moving the concentration sensor 11 and a home position detection signal Sp of the ξ soto isochi 47 are input to the CP[I 201, respectively. There is. The CPU 201 receives the pulse signal Pn+ from the input signal Pn+.
~ value and the home position detection signal Sp, the home position of the concentration sensor 11 and the position in the measurement area are recognized. The motor 40 is connected to a predetermined output port of the CPU 201 via the morph drive circuit 202.
The drive is controlled by the output signal from pυ201.

The other output port of CPII 201 has exposure lamp 2.
1 charging wire 41 and charging wire 42 of the charging charger 4. Developing sleeve 61 of developing device 6. Eraser lamp 1
0. The inter-image eraser 5, main motor 210, etc. are connected. The exposure lamp 21 is connected to the CPLI' 201 via a D/A converter 205 and a power source 204, and the voltage value of the power source 204 is variably set in accordance with the output signal of the CPU 201 to adjust the amount of light. It has become so.

Charging wire 41 and charging grid 421 As shown in the block diagram of FIG.
A predetermined voltage is applied from the output signal number of u201.

In addition, the charging grid 42 is a grid) voltage adjustment circuit 20
It is connected to the CPU 201 via 6. The green node voltage adjustment circuit 206 includes varistors 43a to 43i and a switch 44a between the charged green node 42 and the ground terminal.
~44h are connected in series, and Suinochi 44a
44h are connected in parallel with the varistors 43a to 43h, respectively. Suinochi 44a to 44h are CPU
It is connected to the 8-bit switch control output of 201.

As a result, when the switches 44a to 44h are selectively turned on by the output signal of CPII 20+, the varistors to which the switches are connected are short-circuited. In other words, C
The PU 201 adjusts the grid voltage by selectively turning on the switches 44a to 441[ and changing the overall resistance value of the varistors 4.3a to 43i, and in the area X1 on the photoreceptor drum 3 by the charger 4. The amount of charge is adjusted.

The developing sleeve 61 is connected to the CPII 201 via the 1/8 converter 20B and the bias voltage adjustment circuit 207, and the developing bias voltage applied to the developing sleeve 6I is adjusted in accordance with the output signal of the CPII 201. It has become so.

The eraser lamp IO is connected to the CPt120 via the power supply 209.
1, and its lighting/extinguishing is controlled by the output signal of the CPU 201.

The inter-image eraser 5 is connected to the CPU 201 via the I10 interface 211, and the lighting/extinguishing control of each LHD 1 to 09 (see FIG. 13) making up the eraser is performed. The LHDI-109 are arranged in parallel with a length that allows a margin for the image area I2 of the photoreceptor drum 3, and the image areas LHDI-107 are opposed to each other. In this embodiment, by selectively controlling Llins 3 to 107 to turn on and off, a toner image can be formed in any desired area within the image area.

The main motor 210 is a main motor drive circuit 212]
2 is connected to the CPU 201 via
The drive is controlled by the output signal of 201.

CPLI 201 connects IlA via data bus 214.
It is connected to M 307, and the corresponding 1? Data such as the detection value of the concentration sensor 11 is written to and read from the AM 307.

The CPU 201 also uses a data bus 222. I10
It is connected to the operation panel 2+9 via an interface 221 and a data bus 220, and signals are exchanged with various keys and displays on the operation panel 219.

Furthermore, the CPU 201 is connected via a data bus 218 to an online controller 217, which in turn is connected to an automatic exchange 215 via a local telephone line 216. The automatic exchange 215 is connected to a telephone line (outside &?,) 223. These are for automatically communicating the contents to the service base where maintenance tools are located when an abnormality occurs in the copying machine.

Next, C
A description will be given based on a flowchart showing the control procedure of the PU 210.

FIG. 6 shows the main routine. When the power of the copying machine is turned on, the CPU 201 sets itself to an initial state (step S2).

In the next step S2, an internal timer is scooted. This internal timer determines the time required for the I routine of the main routine, regardless of the processing content in each subroutine described below.

The steno knob S3 performs manual processing of keys 1 to 1 on the operation panel and various defect detectors.

Steps S4 and S5 are a toner image density unevenness check routine and an exposure N adjustment routine for correcting toner image density unevenness when it is detected. The routine is shown in Figures 7 to 9.
The details of the exposure amount adjustment routine are shown in FIGS. 10 to 12, respectively.

In subsequent steps S6 and S7, a copy operation routine and a communication routine with another CPU (not shown) are sequentially called.
When the processing of all subroutines is completed, step S8
After waiting for the internal timer to end, the process returns to step S2.

The length of one routine is used to count various timers used in each subroutine. The various timers determine the end of the timer depending on how many times this I routine has been counted.

7 to 9 show the contents of the toner image density unevenness check routine of the step knob S4. First, in step 5401, the contents of the register (hereinafter referred to as state ■) are set according to the circuit state. Check. State■
Since is set to 1 in the initial setting, the process advances to step 5402 of state I-1 at startup.

Here, whether or not the concentration sensor 11 is at the home position Y is determined based on whether or not the detection signal Sp is input. If the concentration sensor 11 is not at the home position Y, a reverse signal is output to the motor drive circuit 202 to reversely drive the morph 40 in the direction of the arrow f (see FIG. 2), thereby moving the concentration sensor 11 in the direction of the arrow. (step 3406), and the mouth is moved to the home position Y.

5 When the density sensor 11 is placed at the home position YI, the exposure unit 24 of the optical system 20 is moved to position Z, that is, the exposure position of the sticker 25 which is a halftone test chart (steel knob 5403' )
.

In the next step 5404, the signal S, which will be explained next, is converted to D/A.
The output voltage is output to the converter 205 and the output voltage of the power supply 204 is set to 90V corresponding to the reference exposure amount. Table 1 shows the signal S
, ~S, and the output voltage value of the power supply 204 set corresponding to each signal.

Table 1 6 In this embodiment, the output voltage value of the power supply 204 is changed from 90 to 98V at 1V intervals in response to the signal S I-S q.
It can be set in stages. The CPU 201 generates a number (i! (hereinafter, Ex
It is equipped with a counter that counts 1 to 9 (referred to as pSTjiP number), and the count value is updated according to the setting change of Exp-5TEP number.
4, the number <Exp-5TEP is set to 1 as described above, and the signal S is output. In other words, Exp-5TEP
Equation 1 is the standard exposure amount, and the higher the Exp-5TEP number is set, the more the exposure amount, that is, the amount of correction of the light amount increases.

Note that instead of the method of adjusting the voltage value in stages, a method of continuously adjusting the voltage value without any steps may be used.

When the Exp-3TEP number is set in step 5404,
Proceeding to state 1=2, the step knob 5407 starts a timer T that measures the time required to set each device to a state in which a toner image can be created. Then, in step 5408, a signal is output to the main motor drive circuit 212 to drive the main motor 210 and rotate the photosensitive drum 3.

Next, after turning on the inter-image eraser 5 and the eraser lamp 10 (step knob 5409S410), the power supply 204 set to 90V is turned on and the exposure lamp 21 is turned on (step 341.1). Next, use the steno knob 5412 to connect the high voltage transformer 45 and the grid voltage adjustment circuit 20.
6 respectively to turn on Eiden charger 2,
In step 5413, a signal is output to the bias voltage adjustment circuit 207 to apply a predetermined bias voltage to the developing sleeve 61. Here, the inter-image eraser 5 turns on all the LEDs 1 to 109, and the entire image area is erased. As a result, an electrostatic latent image corresponding to the halftone image of the sticker 25 is continuously formed in the exposure area X2 on the photoreceptor drum 3, and is erased in the erase area of the inter-image eraser 5.

In the next state I=3, first, it is determined whether or not the time measurement of the timer T1 has ended (step 5415), and after waiting for this end, in step 3416, the timer T2 that regulates the toner image creation time is started (step 5415). 5416)
. In other words, the time of Kuima T, 8] is the photoconductor tram 3
Although the minimum time required for the area XI charged by the upper charger 2 to reach the erase area of the inter-image eraser 5 is required, charging and erasing are generally not continued until the charging characteristics and sensitivity of the photoconductor tram 3 are stabilized. It is desirable to fatigue the subject to some extent by doing this, and it is preferable to set the time to be approximately one rotation of the photosensitive drum 3.

Now, when timer T2 is started, the next step 5
In step 417, the LEDs 2 to 108 of the inter-image eraser 5 are turned off. In other words, a non-erase area is formed on the photosensitive drum 3 with a width slightly longer than the image area.

Next, timer T2 is activated by the steno knob 5419 in state ■-4.
Waiting for the end, timer T3 is started, and LH02 to LH108 of the inter-image eraser 5 are turned on (sten knobs 3420 to 5422). In other words, timer T
The measurement time 2 is set to the time during which the surface of the photosensitive drum 3 moves by a distance C not shown in FIG. FIG. 13 is a diagram showing the relationship between the toner image 301 for density check, the inter-image eraser 5, and the density sensor 1. The electrostatic latent image formed in the exposure area X2 on the photoreceptor drum 3 is supplied with toner from the developing sleeve 61 by passing through the developing area XI, so that the electrostatic latent image is slightly wider than the image area and has a length of l. A toner image 301 is formed on the photoreceptor drum 3.

By regulating the turn-off time of the inter-image eraser 5 using the timer T2 in this manner, the toner image 301 is not formed to be longer than necessary.

In state I-5, timer T is first set using steno knob 5423.
: Determine the end of l. The time measured by the timer T3 is set to 4 times required for the toner image 301 to move to the area XI facing the density sensor 11.

When the timer 'I'3 finishes counting, the steno knob 5424
After turning off the charger 4, the development bias voltage is stopped, and the exposure lamp 21 is turned off. All the LEDs of the erasure lamp 10 and the inter-image eraser 5 are turned off in sequence (stennob 5425 to 5428). Then, the drive of the main motor 210 is stopped to stop the rotation of the photoreceptor drums J and 3 (steel knob 5429). As a result, the toner image 301 is stopped at a position facing the sensor 11 at 6 degrees, and preparations for measuring the toner image density are completed.

Then, when the stay 1-1 = 6, the motor drive circuit 202
A normal rotation signal is output to the motor 40 to drive the motor 40 in the normal direction of the arrow e (see FIG. 2), and the movement of the concentration sensor 11 in the direction of the arrow g is started. ]).

In the next state T=7, first, it is determined whether or not the pulse signal Pm is input from the pulse generator of the motor 4G (step knob 5433), and when this is input, the count value nL of the internal counter is added (1). step 5434). Then, in step 5435, the pulse signal Pm
When is counted up to 20 times, stay 1□ 1 =
8 (step 5435). This count value 20 is a count value when the density sensor 11 reaches the front end T2 of the image area I.

In step 5437, similarly to the steno knob 5433, the manual input of the pulse signal Pm is checked. When there is an input, 1 is added to n using the steno knob 5438, and then a predetermined area (hereinafter referred to as
The output voltage Vd of the concentration sensor 11 is sequentially written as a signal value obtained by digital conversion by the A/D converter 203 into the output voltage Vd term) via the data bus 214 (step 5439).

Then, in step 5440, it is determined whether the count value n has reached 229 or not. If it has reached 229, the measurement of the toner image density is finished and the process proceeds to step 1-1=9 (step 5441). In other words, count value 21-229
corresponds to the total width Y2 to Y3 of the image area (see FIG. 2), and the measurement of the toner image density Vd of the entire toner image forming area in the longitudinal direction of the photosensitive drum 3 is completed.

In the case of stay) 1=9, first, the motor 40 starts to be driven in reverse, and the concentration sensor 11 starts moving in the home position Y direction (arrow h) (step 5442). When the home position detection signal Sp is inputted manually in step 5443, the drive of the motor 40 is stopped and the process proceeds to state l-10 (step knobs 5444 and 5445).

In state l-10, first, the signal value Vd stored in the Vd term corresponding to the count value n is determined from R111307.
The highest value Vdmax,
In other words, the measurement value of the highest concentration part is selected together with the corresponding count value n1 (step 5446).
).

Next, with the steno knob 5447, the highest value Vdmax is
It is determined whether the value is higher than a reference value Vdo stored in advance in 307 for determining the presence or absence of density unevenness in the toner image. If Vdmax is lower than Vdo, it means that no density unevenness has occurred in the toner image, so state ■ is set to 1 and the process returns to the main routine (
Stenobu 544B).

On the other hand, if Vdmax is greater than or equal to Vdo, it means that density unevenness has occurred in the toner image, so state l-
Proceed to 11 (Stenob 5449).

That is, in this embodiment, the presence or absence of density unevenness is determined based on the highest value among the measured density values. In addition, the density unevenness can also be determined based on the magnitude of the difference between the maximum value and the minimum value, for example.

In step 1=11, a warning display "Cd" indicating that the toner image density is inappropriate is displayed on a predetermined display section of the operation panel 219 (step 5450), and the process then proceeds to state 1-12.

In state l-12, online controller 217
A command is issued to transmit data of "Cd" and measured value Vdmax to (step 5452). As a result, data on the details of the abnormality is transmitted to a service base (not shown) via the telephone line 223, and then the state r is set to 1 and the process returns to the main routine (Stennob 5453).
.

10 to 12 show the contents of the exposure amount adjustment routine in step S5, in which the state number is determined in step 5501 and the state number is processed in the same way as the toner image density unevenness check routine described above. . In this subroutine as well, the state is set to 1 by default, so first, it is determined whether the change of the toner image density unevenness has been completed using the steno knob 5502 of stay 1-1-1, and if it has been completed, the step At step 5503, as described above, it is determined whether there is density unevenness in the toner image based on the comparison result between the measured value Vdmax and the reference value Vdo, and if there is no density unevenness, the process returns to the main routine.

4 On the other hand, if density unevenness occurs, use Stenobu 550.
4, the LED number of the inter-image eraser 5 corresponding to the count value old at the measurement position of Vdmax of the density sensor 11 is calculated.

To adjust the exposure amount in this routine, the sticker 25 is exposed again to actually form a halftone toner image as a test pattern, and the exposure amount is adjusted so that the density of the halftone toner image is lower than the reference value. Therefore, by using the measurement results in the toner image density unevenness routine, the first
As shown in FIG. 4, by forming a toner image 302 only at the measurement position of the highest value Vdmax of density unevenness, toner consumption can be suppressed to a minimum.

FIG. 14 is a diagram showing the relationship between the toner image 302 for the test pattern, the inter-image eraser 5, and the density sensor 11. Assuming that the distance that the density sensor 11 moves with one pulse signal Pm of the motor 40 is 2 u, and the distance of the LED arrangement of the inter-image eraser 5 is 4 mm, the number of the LED that is turned off to form the toner image 302 is nLx is calculated by the following formula.

nLx-2(n+-20)/4 +2Here, let nl2 be the integer part of nLx, ri L con nl, 2-1n L
If 3 = n 12 → 1, then t will be lit, +4
0 is LljDnLl, LED-nl2. l, E.D.
-n It is found as L3. For example, when n is -125,
nLx=54.5, LED, 3 of 53.5455
)) is lit to form a toner image 302. Note that this calculation method is stored in the II station 307.

Now, 1, ET4 number n [, 1, ru, 2, 1.2.
When nl, 31.3 is calculated and LEII is selected, the motor 40 is
is driven in the forward direction to start the movement of the concentration sensor IJ-1,1 from the home position Y1 in the direction of arrow g, and the stay 1.
When I=3, each time the pulse signal Pm from the pulse generator rake of the motor 40 is input, 1 is added to the current value n (steps 3508 and 5509).

Then, the steno knob 5510 indicates that 0 is the maximum value Vdm of the toner image density measured in the toner image density unevenness check routine.
The count value of ax becomes 1, that is, the concentration sensor 11 becomes V
When the measurement position of dmax is reached, the drive of the motor 40 is stopped (steel knob 5511).

In step=l·l=4, the timer T is started and each output means is turned on in order to prepare for toner image formation, similar to the toner image density unevenness check routine described above. That is, the main motor 2]0 is driven, and the inter-image eraser 5. Eraser lamp 10. The exposure lamps 21 are turned on, the charger 4 is turned on, and a developing high speed voltage is applied (Sdenops 3513 to S519).

In addition, at this time, the inter-image eraser 5 erases all LEDs 1 to 1.
09 is turned on, and the light a204 of the exposure lamp 21 is
90V is set based on pSTEP number 1.

Then, when the time measurement of tie '7T is completed in stay 1-1-5, ExpST is
Set the number of EPs to 2. This causes the power supply 204 to
The voltage is increased to V, and the amount of light from the exposure lamp 21 is increased.

Next, start the timer T2, and set the inter-image eraser 5 to 1.
Of the ED, LRD n selected by Stenobu 5504)
l, ], nL2. Turn off riL3 (stenob 5524, 5525).

Then, when the timer 7 T2 finishes counting at the steno knob 5527 in state I=7, the timer T is started from 1 to 1 and the LEDs n Ll, n L2 .
n Turn on L3 (steps 5528, 5529
). That is, all LEDs are turned on again. As a result,
Above the photoconductor drum 1.3 is a wire with a width of three LEDs and a length of C.
An electrostatic latent image is formed at the opposing position of LEl'lnL1 to nL3)1, and by passing through the development area X3, it is developed into a toner image 302 (not shown in 14th 1).

In the stay 1-1-8, first, the steno knob 5531 checks whether the timer T3 has finished counting. At the time when the timer T3 finishes counting, the toner image 302 reaches the area X facing the density sensor H. Then, read the measured value of the concentration sensor 11 using the steno knob 5532, and
・Measurement value, att, Vdmax is Vdo
Determine whether it is less than or equal to. If it is determined that Vd1llax is larger than the reference value Vdo, the next stage 1-
Proceed to 1 = 9. On the other hand, Vdmax is Vd.

If it is below, it means that the light amount of the exposure lamp 21 has been adjusted to an appropriate value, and the process proceeds to stay 1/l-31, which will be described later, and starts the operation of turning off each output means.

8 Now, in stay 1-1 = 9.10.1.1, Exp
-3 The set number of TEPs is increased by one from 2 to 3, and the same processing as in the above stay 1-1 = 6 to 8 is performed. In other words, I! The exposure lamp 21 is turned on at 92V according to xp-3 TEP number 3 to form a toner image 302, and the measured density value Vdmax is compared with the reference value Vdo.
dmax is Vd.

If it is below, proceed to stay 1 l-31 and Vdmax
If it is thicker than Vdo, the process advances to the next state l-12.

Similarly, the measured value Vdmax of the density of the toner image 302
The light intensity of the exposure lamp 21 is increased by sequentially increasing the number of F, 3ne+1.3ne→2,
ne; [1xp-3TEP number).

And stay) 1 = 29 steno knob 5710 judgment,
That is, if it is determined that the measured value Vdmax of the density of the toner image 302 formed with the l1xp-3TEP number set to the highest 9 is greater than the reference value Vdo, it is no longer possible to increase the light intensity of the exposure lamp 21. Since it is possible, stay 1
Proceed to -1-30.

After displaying the warning "Cd-9" on the operation panel 219 indicating that the stay 1-I-30 is in a state where it is not possible to prevent the skin from breaking, and transmitting the content of the warning to the Ri-bis base, stay = Proceed to 31 (Stenob 3713
~5715).

In state l-31, each output means is turned off.

That is, after the charger 4 is turned off in step 3716, the application of the developing bias voltage is stopped, and the exposure lamp 2 is turned off.
1. The total L of the eraser lamp 10 and the inter-image eraser 5 [:
Sequentially turn off the lights D (Sten knob S7] 7-5720).

Then, the drive of the main motor 210 is stopped to stop the rotation of the photoreceptor F ram 3 (steel knob 5721).

In the stays 1 and 1-32, the motor 40 is reversely driven to return the density sensor 11 to the home position Y1 (step knobs 3723 to 5725), and the step knob 5726 is used to set state I to 1 to complete the adjustment of the exposure amount. Return to main routine.

Note that when adjusting the exposure amount described above, the photoreceptor drum 3
Although it is kept rotating during adjustment, it is of course possible to stop it and measure the density of the I/toner image 302.

FIG. 15 shows the relationship between the density of the I/toner image and the copy image.
The seal 25 was exposed to light as shown in Fig. 15 (a).
1 indicates a state in which density unevenness has occurred.

In the graph in the figure, the vertical axis represents the output voltage Vd of the density sensor 11, and the horizontal axis corresponds to the image area in the longitudinal direction of the photoreceptor tram 3. In this figure, the output potential V dmax at the highest part of the convex part of the graph is generated due to charging failure of the charger 4, uneven electrostatic characteristics of the photosensitive drum 3, exposure failure of the optical system 20, or the like. That is, in the charging charger 4, the charging wire 41. It is possible that the charging grid 42 or the stabilizer plate is contaminated, and in the optical system 20, the exposure lamp 21 is deteriorated or contaminated, or the ξshield 2
The lenses 2a to 22d may be contaminated. Here, the appropriate output potential is Vd, and the output potential for background overlap is Vd.

Occurs when it exceeds. For this reason, when you actually copy,
A background overlap 331 occurs on the paper 330.

1 FIG. 15 (bl) shows the state when the exposure amount is adjusted as described above. By increasing the light amount of the exposure lamp 21, Vdmax is set to the reference value set between Vdz and Vd. It is set to be lower than Vdo.As a result, (33
1 can be prevented.

Note that this correction does not eliminate the density unevenness itself, so when copying a halftone image, density unevenness will occur. However, since the character image 332 has a constant density, it is hardly affected, so it is not suitable for general manuscripts with textural damage. Good images can be obtained without any problems when copying.

In addition, in this embodiment, explanation has been given of the content of preventing background fogging by adjusting the exposure amount, but by adjusting the amount of charge on the photoreceptor drum 3 by the charger 4 or the developing bias voltage value. is also possible. In other words, if there is a risk of skin overlapping due to density unevenness, the charging grid 4 should be used to reduce the amount of charge.
By adjusting the grid voltage of 2 or increasing the bias voltage value applied to the developing sleeve 612, the difference between the latent image potential and the bias voltage value can be reduced and the unit area to be developed can be increased. The amount of toner per unit can be reduced,
This can prevent the skin from getting covered.

Furthermore, in this embodiment, toner image formation and density measurement in the density unevenness checking routine are performed over the entire image area, and based on these results, toner image formation and density measurement are performed in the exposure amount adjustment routine. The purpose of this is to detect the highest density part in the image area where there is a risk of background overlap, and correct the overall image density by correcting this part. This is because the present invention is not limited to this method of use; for example, a toner image is formed partially from the time of initial density check measurement, and the density is measured. The image density may be corrected based on this. In other words, in contrast to the conventional problem of correcting image density at positions other than the measurement position using a fixed measurement position, it is possible to change the measurement position and formation area of the toner image each time the measurement is performed, or to perform multiple measurements. This can be dealt with by setting the position and toner image forming area.

Further, in this embodiment, the density sensor is configured to move across the image area, but is not limited to this, and can be moved over the entire image area like an LED for an inter-image eraser. A configuration may also be adopted in which concentration sensor groups are arranged and used selectively.

Furthermore, in this embodiment, an inter-image eraser consisting of a plurality of LEDs is used to partially form the I/ner image, and the LE
D is selectively turned on/off, but instead of this, a plurality of light beams are provided in the exposure optical path leading to the exposure area of the photoreceptor drum, which can partially block the optical path corresponding to the longitudinal direction of the photoreceptor drum. A shutter member made of a plate or an array of liquid crystal shutters may be interposed.

〔effect〕

As described in detail above, in the copying machine of the first aspect of the present invention, when the measurement position of the sensor is arbitrarily set in the direction perpendicular to the image forming direction of the photoreceptor, the reference toner image is formed only in the corresponding area. is automatically formed. Further, in the copying machine of the second invention, when a reference toner image is formed by arbitrarily setting the width or position in a direction perpendicular to the image forming direction of the photoreceptor, the measurement position of the sensor with respect to this reference toner image is is automatically set.

As a result, the reference toner image is not formed in the entire area perpendicular to the image forming direction of the photoreceptor, as in the past, and the reference toner image can be formed in the minimum necessary size, greatly reducing toner consumption. can.

In addition, since the measurement position of the sensor and the formation area of the reference toner image can be changed arbitrarily in the direction orthogonal to the image forming direction of the photoreceptor, by changing and setting these as appropriate, it is possible to It is possible to prevent correction of image density at locations other than the measurement position due to the measurement position being fixed at only one location, and it is possible to measure the density of toner images efficiently and economically. , the present invention has excellent effects.

[Brief explanation of drawings]

5 FIG. 1 is a schematic diagram showing the general configuration of a copying machine according to the present invention,
Fig. 2 is a schematic diagram showing the configuration and arrangement state of the density sensor, Fig. 3 is a block diagram of the control system, Fig. 4 is a graph showing the relationship between the toner image density and output voltage of the density sensor, and Fig. 5
The figure is a block diagram showing the configuration of the charger, Nos. 6 to 1.
Figure 2 is a flowchart showing the control procedure of CPLI, the first
FIG. 3 is a diagram showing the relationship between the toner image for tala degree check, the inter-image eraser and the density sensor, and FIG. 14 is a diagram showing the relationship between the toner image for adjustment and the inter-image eraser and density sensor. Figure 15 is a diagram showing the relationship between the density of a toner image and a copy image. 3... Photosensitive drum 5... Inter-image eraser 11... Agricultural rate sensor 21... Exposure lamp 25... Seal 4... Charger 6... Developing unit 20... Optical System 24...Exposure Unisoto 201...CPU 6

Claims (1)

[Claims] 1. A reference toner image is formed on a photoconductor that is moved in a first direction corresponding to the image scanning direction, the density of this is measured by a sensor, and the image is created based on the measurement results. In a copying machine that adjusts density, the measurement position setting means sets the measurement position of the sensor at an arbitrary position on the photoreceptor in a second direction perpendicular to the first direction; forming the reference toner image on a portion of the photoconductor in the second direction corresponding to the measurement position. 2. A copying machine that forms a reference toner image on a photoconductor that is moved in a first direction corresponding to the image scanning direction, measures the density of this with a sensor, and adjusts the image density based on the measurement result. a toner image forming means for arbitrarily setting the formation width or position of the reference toner image on the photoreceptor in a second direction orthogonal to the first direction; and a reference toner image set by the toner image forming means. A copying machine comprising means for setting a position in a second direction corresponding to an image as a measurement position of the sensor.