JPS63177161A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the image density of an output image form decreasing even if where is a developing device to which a developer can not be supplied by providing a control means which corrects a developing bias voltage applied to a developing means and a primary high voltage applied to an image carrier to corrected values. CONSTITUTION:A decrease in developer concentration is divided into plural stepwise ranges according to constant data in advance, and corrected values of developing bias voltages or primary high voltages corresponding to the respective ranges are stored previously in a ROM 602. Then even if the developer concentration of each developing device drops, a developer is not supplied immediately, and the developing bias voltage or primary high voltage is corrected during the use of a developing device only when the developer concentration of the developing device to which a developer can not be supplemented decreases according to the position relation of an angle of rotation in continuous copying operation. Consequently, even if there is the developing means to which the developer can not be supplemented from a developer supplementing means during the execution of the sequence of image formation, the image density of an output image does not decrease and the image has high quality.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to an image forming apparatus, and in particular, for example, #i
In this specification, a multicolor electrophotographic copying device t as a color image forming device will be described. do.

1 4 6, 'This type of multicolor electrophotographic copying apparatus is structured so that, for example, two colors can be developed, a three-color Buddhist utensil-L color copy, or a full-color copy can be obtained.1 Normally, within the main body of the apparatus, there is a photoreceptor drum formed with a fairly large diameter that serves as an image carrier, and three drums disposed along the outer peripheral surface of the photoreceptor drum in close proximity to the outer peripheral surface of the photoreceptor drum. ~An image form *fj! consisting of various equipment including 4 developing devices! l
The structure has the following. Each of the above-mentioned developing units stores six separate developers of yellow Y, magenta M, cyan C, black BK, etc., and the developer of each color is used to form images on each photoreceptor drum. This system converts the electrostatic latent image of original image information into a visible image. In the multicolor electrophotographic copying apparatus having the above-mentioned configuration, four developing units must be disposed near the outer peripheral surface of the photoreceptor drum. Compared to a single-color electrophotographic copying device that only requires one developing device nearby, more than four times the internal space for the developing device is required, and the diameter of the photoreceptor drum is also smaller than that of a single-color electrophotographic copying device. It is necessary to make the diameter considerably larger than that currently available in other copying machines, and it is inevitable that the machine as a whole will become larger and the cost will increase due to the larger size. As a countermeasure to avoid this problem, a multicolor electrophotographic copying device equipped with a so-called rotary developing device was proposed (Japanese Patent Publication No. 50-93437).
The outline of the proposal is that a rotary developing device 21, that is, a substantially cylindrical housing that holds four developing devices and is rotatably supported, is disposed near the outer circumferential surface of the photoreceptor drum. The electrostatic latent image formed on the photoreceptor drum is sequentially developed by a developing device that is brought to a developing position facing the outer circumferential surface of the photoreceptor drum by rotating the housing. Please refer to the above publication for details).

By the way, even in the case of a multicolor electrophotographic copying machine equipped with a rotary developing device having the above-mentioned configuration, it is possible to miniaturize the entire device and create a lower cost device! To achieve this, it becomes necessary to downsize the housing, and this downsizing of the housing inevitably leads to downsizing of each developing unit. In a multicolor electrophotographic copying machine in which the rotary developing device is miniaturized in this way, each developing unit is separately provided from each developing device. A developer replenishment device is required to replenish the developer to the container, but since the development position is different from the above-mentioned development position in that the developer is supplied from the developer replenishment device to each developing device. Depending on the mutual positional relationship between the rotating developing units, even if an attempt is made to replenish developer to other developing units that are not at the developing position during image copying in which each developing unit is stopped only at the developing position, If there is a developing device that does not stop at the developer replenishment position, developer cannot be replenished to the developing device.

Therefore, in order to meet the modern trend of increasing the speed of image copying, we have developed an image copying method that can also be used to replenish developer for developing devices that cannot be replenished with developer. A sequence of image copying is continuously executed until the number of sheets of transfer material reaches a predetermined number, and a sequence is added each time the number of sheets of transfer material reaches a predetermined number of sheets, replenishing the developer from the developer replenishing device to the developing device. is thought about. However, with this method, if the amount of waste consumed when copying a predetermined number of images is higher than normal, the concentration of the developer in the developing device will drop significantly. Therefore, a problem arises in that only an output image with reduced density can be obtained.

Therefore, the present invention was devised to solve the above-mentioned problems, and its purpose is to prevent the replenishment of developer from the developer replenishment device while executing the sequence of copying one image. To provide an image forming system [1] capable of obtaining a high-quality image without significantly lowering the image density of an output image even if there is a developing device that cannot handle the image.

F! 1. The above objects are achieved by an image forming apparatus according to the present invention. In summary, the present invention provides an image carrier on which electrostatic latent images of multiple colors corresponding to original image information are formed, and an electrostatic latent image formed on the image carrier adjacent to the image carrier. a plurality of developing means that are movable in circulation to a developing position for image visualization and each holding a different color developer; An image forming apparatus comprising a developer replenishing means for replenishing developer of a different color to each developing means, the developer for detecting the concentration of the developer remaining in each of the developing means. Concentration detection means is provided to store reference concentration value data of the developer held in each of the plurality of developing means, and to store the reference density value data of the developer detected by the developer concentration detection means in the plurality of development means. A developing bias voltage and a primary high voltage when there is a developing means whose density value has not reached the reference density (1) and image formation is continued without replenishing the developing means with developer from the developer replenishing means. storage means for storing correction value data is provided, and the developer density value detected by the detection means does not reach the reference density value and the developer cannot be replenished without interrupting image formation. The image forming apparatus is characterized in that, when there is a developing means, a control means is provided for correcting the developing bias voltage applied to the developing means and the primary high voltage applied to the image carrier to the correction value.

1. An embodiment of the present invention will be described below using the Ij4 plane.

FIG. 1 shows an image forming apparatus according to an embodiment of the present invention.
As is clear with reference to the figure, one side of the device main body 100 (
A transfer material conveyance system I is provided extending from the right side in FIG. A latent image forming section (2) provided in the vicinity of the latent image forming section (2), a developing means (i.e., a rotary developing device (2)) disposed close to the latent image forming section (2), and a rotary developing device (2) located close to the rotary developing device (2). ! 11
The developer replenishment T stage, that is, the developer replenishment device 2
It is broadly divided into. The transfer material transport system I described above includes a transfer material transport system tray lot, 10, which is detachable from an opening formed on one side (right side in FIG. 1) of the apparatus main body 100.
2, paper feed rollers 103 and 104 disposed approximately directly above the trays 101 and 102, and these paper feed rollers 1
03° 104 and provided with paper feed rollers 6, and paper feed guides 5a and 5b provided with paper feed rollers 6, and paper feed guides 5a and 5b provided near the paper feed guide 5b and arranged near the outer peripheral surface from the upstream side to the downstream side in the rotational direction. 8. Contact roller 8. A gripper 7 is provided with a charger 14 for separating the transfer material, a separation claw 15, and a transfer charger 10 on the inner circumference side. A transfer drum 9 that is rotatable in the direction of the arrow in FIG.
6, and an apparatus main body 10 disposed close to the terminal end side of the conveyor belt means 16 in the conveying direction and extending outside the apparatus main body 100.
It consists of a discharge tray 10 that can be attached to and detached from the printer 0 and a fixing device 17 that is adjacent thereto.

The latent image type I & part (2) is arranged so that its outer circumferential surface is in contact with the outer circumferential surface of the transfer drum 9, and rotates in the direction of the arrow in FIG. A charger for static elimination 11.A charger for neutralization 11.A charger for removing static electricity is provided near the outer peripheral surface of the photoreceptor drum 3 in the rotational direction I of the photoreceptor drum 3: from the flow side to the downstream side. and image exposure means such as a laser beam scanner and image exposure reflection means such as a polygon mirror for forming an electrostatic WI image on the outer peripheral surface of the photosensitive drum 3.The rotary developing device m A casing that can rotate freely once (hereinafter referred to as a "rotating body")
Visualize the electrostatic WI image (i.e., Yellow developer IY, magenta developer 1M, cyan developer IC, and black developer
The developer replenishing device 2 has:
are yellow hoppers 2Y that are arranged adjacent to each other and hold 1σ developers of each color separately, which are submerged and supplied from the outside.
, magenta hopper 2M, cyan hopper 2C, and black hopper 28.

First, the entire sequence of the image forming apparatus having the above-described configuration will be briefly described using a full color mode as an example. When the photoreceptor drum 3 described above rotates in the direction of the arrow in FIG. 11, the photoreceptor on the photoreceptor drum 3 is uniformly charged by the primary charger 4. As shown in FIG. - When the photoreceptor is uniformly charged by the charger 4, image exposure is performed by the laser beam E modulated by the yellow image signal of the original (not shown), and the electrostatic charge is generated on the photoreceptor drum 3. A latent image is formed, and the electrostatic latent image is developed by the yellow developing device IY, which has been placed in advance at a developing position by the rotation of the rotating body 1.

On the other hand, paper feed guide 5a, paper feed roller 6, paper feed guide 5b
The transfer material conveyed via the gripper 7 is held by the gripper 7 at a predetermined timing.

It is electrostatically wound around the transfer drum 9 by the contact roller 8 and the electrode facing the corresponding contact roller 8 . The transfer drum 9 rotates in the direction of the arrow in FIG.
The image is transferred by the transfer charger 10 at the portion where the outer peripheral surface of the image is in contact with the outer circumferential surface of the image data. The transfer drum 9 continues to make one revolution for m times in preparation for transferring the next color (magenta in FIG. 1).

On the other hand, the photosensitive drum 3 is neutralized by the static eliminating band "#L device 11" and cleaned by the cleaning means 12, and then charged again by the primary charger 4, and is then charged by the next magenta image signal. image exposure.

The rotary developer 9211 rotates while an electrostatic latent image is formed on the photoreceptor drum 3 by the magenta image signal by the image exposure, and fixes the magenta developer LM at the predetermined development position described above. Perform magenta development of
Subsequently, the above-described process was also carried out for cyan and black colors, respectively.

When the transfer of the four colors is completed, the four-color sequential image formed on the transfer material is neutralized by each charger 13, 14, the grip of the transfer material by the gripper 7 is released, and the transfer material is It is separated from the transfer drum 9 by the separation claw 15,
The image is sent to the fixing device 17 by the conveyor belt 16, a series of full-color print sequences are completed, and a desired full-color print image is formed.

FIG. 2 shows the structure of a rotary developing device according to an embodiment of the present invention, and FIG. 3 shows the structure of a developer (toner) replenishing device. To explain the configuration of the apparatus in more detail, each of the developing units IY, I
M and IC1IBK are developing devices each employing a magnetic brush development method using a two-component developer consisting of a magnetic powder carrier and toner, and each of the developing devices has a screen for circulating the developer: It is equipped with L-22a, 22b, a developing sleeve 21 for forming a magnetic brush, and the like.

A central shaft 27 that rotatably supports the rotary body I is disposed at the center of the rotary body l, and an outer circumferential portion of the central shaft 27 is provided with water flowing from each of the hoppers. An annular cavity 28 is formed to temporarily accommodate developer, and a cam 25 fixed to the central shaft 27 is provided within the annular cavity 28 . Further, within the annular cavity 28, four movable shutter levers 24 are provided at approximately equal intervals, and these four shutter levers 24 communicate with each of the above-mentioned current GT devices. When the position of the opening 26 of the developer introduction path coincides with the position of the cam 25 due to the rotation of the rotating body 1, it comes into contact with the cam member 25 and the bent opening 26 is closed by the cam member 25. The shutter member 23 is released.

As mentioned above, the shutter member 23 opens and closes the opening 26 for toner replenishment, and allows each of the developing devices to move to the toner replenishing position (in FIG. 2, the position where the magenta developing device IM is located). When it moves, the shutter lever 24 is rotated by a cam 25 fixed on the central shaft 27, and the shutter 23 of the opening 26 is released, making it possible to replenish toner.

In FIG. 3, to describe the structure of the developer replenishing device 2 in more detail, the developer replenishing type W12 described above has one end communicating with each of the hoppers 2Y, 2M, and 2C128, and the other end thereof. Screws 31Y, 31M, and 31C131BK whose sides communicate with the annular cavity 28
Each of these screws is rotatably driven by a motor (not shown), and when the developing device reaches the position of the magenta developing device IM shown in FIG. It is designed to deliver the drug.

FIG. 4 shows the structure of a developer concentration detection means, that is, a developer concentration detection device according to an embodiment of the present invention.

As is clear from FIG. 4, the developer concentration detection device according to one embodiment of the present invention includes a photo/electrical conversion signal processing circuit (
&) and an optical signal supply that supplies an optical signal to the optical/electrical conversion signal processing circuit (a)! 'ff1(b).

The aforementioned optical/electrical conversion signal processing circuit (a) is connected to the device main body 1.
One unit is installed on the 0G side, and the optical signal supply ff1(b)
are provided to each of the developing devices IY, LM, and IC1IBK, respectively. The optical/electrical conversion signal processing circuit (a
)teeth.

A lens lamp 402, filters 404 and 405, an operational amplifier 401, a negative feedback resistor connected to the operational amplifier 401, and a light receiving element such as a photodiode connected to the inverting input terminal of the operational amplifier 401. On the other hand, the optical signal supply section (b) includes an optical fiber 406 . which receives the optical signal given from the lens lamp 402 . Guicroic mirror 4
07, EL glass 408, the developing sleeve 2 provided through the EL glass 408 and the microscopic mirror 407
SELFOC lens 409° SELFOC lens 40 which receives the optical signal scattered by the developer 410 attached to 1
It consists of an optical fiber 411 that receives an optical signal applied via 9 and supplies it to the light receiving element sensor 403. @
The developer density nail detection device detects the photo/electrical conversion signal processing circuit (a
) and an optical signal supply section (b) are connected to complete the concentration detection circuit. In the above state, the light beam emitted from the lens lamp 402 is transmitted through the optical fiber 406.
Guicroic mirror 407. EL glass 40
The light passes through B and irradiates the developer 410 at the non-developing position at the end of the developing sleeve 21 (FIGS. 2 and 4). Here, of the light emitted from the lens lamp 402, white light is reflected by the guichroic mirror 407, and near-infrared light is reflected by the developer 410 and scattered. A part of the scattered light is focused onto an optical fiber 411 by a SELFOC lens 409, passes through the optical fiber 411, passes through a filter 404 or 405, and is then irradiated onto a light receiving element sensor 403 such as a photodiode. Ru.

The filter 404 is a filter that allows only white light to pass through, and the filter 405 is a filter that allows only near-infrared light to pass through, and is switched in synchronization with a predetermined timing by a position disk and a solenoid (not shown). , a reference signal can be obtained by the light transmitted through the filter 404, and a developer concentration signal can be obtained by the filter 405. The output level of the signal obtained by the light receiving element sensor 403 is adjusted by the RL amplifier 401, and after being converted into a digital signal by an analog/digital converter, the signal is sent to a control means, that is, a control controller 601.
The concentration value of the developer, which is read in (t & Figure 6), is
It can be determined by calibrating with the reference signal marked #.

In a rotary developing device equipped with a developer concentration detection device and a developer replenishment device as described above, the development position of each developer and the relationship between the developer concentration detection position and the developer replenishment position are set in advance. Since the difference depends on the rotation angle position of the developing device with respect to the reference position (home position) of the rotary developing device, it is not possible to measure the concentration of the developer and immediately replenish the developer.

FIGS. 5(a) to 5(e) show the rotary developing device 211, respectively.
This figure shows each stop position with respect to the photoreceptor drum 3, and if the reference position is determined as shown in FIG. 5(a),
Each rotation angle from the reference position t is 45@, 135°, 22
Each developer IY, LM, at 56 and 315° positions
The relationship between the Ic and IBK development positions, each developer C claw detection position, and each developer replenishment position is shown in FIG. 5(b) to
(e) and as shown in Table 1.

Table 1 As is clear from the above-mentioned contents, in FIG. 5, at a certain angular position, the lower developing device (for example, developing device IY in FIG. The developing device located opposite to the developing device 3 (for example, developing device IBK in FIG. 3B) is the developing device located at the developing position and the developer concentration detection position. That is, for a certain developing device, a position rotated 90 degrees before the developing position and the developer concentration detection position is the developer replenishment position.

1'61 As is clear from Table 1 mentioned above, when full-color continuous copying is performed using developing units IY, IM, Ic, and IBK for four colors, all developing units IY, IM,
Ic and IBK always move to the developer replenishment position. However, in the case of a mode in which there is an unused developing device, for example, when performing continuous copying using developing devices IY, IM, and IC for three colors, for development: 111M, when developing device IY is used, However, regarding developer IC, developer I
The developer replenishment position is when M is developed, but since the developer IY does not perform development with the developer IBK, simply moving the developers IM and lc to the positions required for development will not work. Since the developer lY cannot be stopped at the developer replenishment position described above, the yellow developer cannot be replenished in this state. Therefore, during the continuous copying sequence in the three-color mode using the developing devices ty, IM, and IC, the developing device 1Y is always stopped at the developer replenishment position described above after the development by the developing device 1c.
It is also possible to replenish the yellow developer at the position and then move the developer IY to the development position to develop the electrostatic latent image corresponding to the yellow image signal. The copying speed will be slowed down accordingly. In view of such facts, the present invention has the following features.

In order to increase the copying speed as much as possible, if the developing device does not stop at the developer replenishment position while other developing devices are performing development at the developing position, even if the developer concentration decreases to some extent. , Continuous copying is performed on the transfer material for a minimum predetermined number of sheets as it is, and after adding a developer replenishment sequence to the developing device which was not able to replenish developer during the continuous copying, continuous copying is performed again. I decided to do this. In this embodiment, the concentration of the toner in the developer in each developing device is controlled so that it does not become less than 15% at all times, and the :Il of the developer at this time is 3.
It is experimentally known that the amount of developer consumed per copying of one sheet of A4 size transfer material at 0g is about 0.3g. However, the addition of the developer replenishment sequence is not limited to the above-mentioned number of copies; for example, it may be 5 copies, 20 copies, or The number of copies may be changed depending on the copy size, or the developer replenishment sequence may be added after all the required set number of copies have been made.

FIG. 6 shows the configuration of a control system of an image forming apparatus according to an embodiment of the present invention. In FIG. The drive motor, developer drive motor, and other loads required for printer control are input from the controller 601.
It is driven by a drive command signal given to the load drive circuit 606 via the mountain capotro 05. Input means 1. ．．
1z, 1,, see, 1m are each hopper 2Y, 2M, 2
It is necessary for inputting the developer remaining amount detection signal in C and 2BK and for other printer control, and the signal input by each of these input means has its signal level adjusted by the input interface 607. The 0 display and operation unit 604, which is later input to the controller 601 via the input/output port 05, is equipped with displays and switches that indicate whether there is a remaining amount of each developer and other information necessary for the printer. , is connected to the controller 601 via the input/output port 05.

The aforementioned light receiving element sensor 403 (Fig. 4(a)(a))
The density signal and reference signal of each developer detected in the above-mentioned increase I&! The output level is adjusted at 31401, converted into a digital signal by an analog/digital converter 608, and then input to the controller 601 via the input/output port 05. The controller 601 operates according to the program, table data, etc. stored in advance in the storage means, ie, ROM 602.
Predetermined control is executed while storing necessary data etc. in the RAM 603.

FIG. 9 shows characteristics of image density D (Macbeth value) with respect to contrast potential V (surface potential of photosensitive drum 3 corresponding to developing bias voltage) applied to an image forming apparatus according to an embodiment of the present invention. - indicates D characteristic value data;
The data shown in Fig. 9 can be obtained in advance by some means such as experimentation, and based on such data, the decrease in developer concentration can be divided into several ranges in advance, and the decrease in the developer concentration can be divided into several ranges. The correction value of the corresponding developing bias voltage or primary high voltage is stored in advance in the ROM 602 (6th
(Fig.), and when the developer concentration in each developing device decreases, the developer is not refilled immediately and continuous copying is being performed. Only when the developer concentration of the first fI base, which cannot be developed, is lowered, the above-mentioned development bias voltage or primary high voltage is corrected when the developing device is used.

7114 is a flowchart showing the processing operation of the 8 control system shown in FIG. 6 above. This sequence is basically a counter built into the controller 601 that is obtained by counting pulses from an encoder (not shown) that rotates in synchronization with a drive motor that drives the photoreceptor drum 3. The reference position of the transfer drum 9, which is advanced according to numerical values and is rotating in synchronization with the photoreceptor drum 3, is set by a photo interrupter (not shown) on the transfer drum 9.
By crossing the shutter member 23 disposed above,
This is detected by the photointerrupter, and by this detection, the total a value is reset and it is also detected how many times the transfer drum 9 has rotated.

When these counted values match the setting values previously stored in the ROM 602 shown in FIG. The operating sequence described with reference to FIG. 1 proceeds.

In FIG. 4A, the controller 601 performs the steps 702 shown in FIG. , input/output capo) 605. By driving the developer drive motor via the load drive circuit 60B, the developer ty is moved to a replenishment position for yellow developer (hereinafter referred to as "Y toner") (step 801), and a Y toner replenishment flag, which will be described later, is set. Check to determine whether it is necessary to replenish the Y toner (step 802), and when it is determined that it is necessary,
Input/Output Portro 05. By driving the developer hopper drive motor via the load drive circuit 606, the developer IY is replenished with Y toner, and the Y) toner replenishment flag is reset (step 803), in addition to step 801 described above. 803 may be omitted depending on the case. When the processing operations of steps 801 to 803 are completed, the input/output port) 605. Load drive circuit 60
6 to move the developing device IY to the developing position as shown in FIG. 1 (step 804), and based on the data as shown in FIG. After making corrections as described later based on the correction value data regarding the voltage and primary high voltage created and stored in the ROM 602 (step 805)
, the developing device IY starts developing the electrostatic latent image corresponding to the yellow image signal formed on the photoreceptor drum 3 (
step 806 ), along with this, the controller 601
is output from the amplifier 401 and A/D converted! 1608
．． The signal input through the input/output port 05 is taken in, and the concentration of the developer in the developing device IY is detected during the development in step 806 (step 807).As described above, the developing device IY When developing is being performed, since the developing device IM is at the developer toner replenishment position, it is necessary to determine whether or not it is necessary to replenish magenta developer (hereinafter referred to as rM toner) using the M toner replenishment flag. 808), if it is determined that it is necessary, replenishes M toner in the same manner as in step 803, and resets the M toner replenishment flag (step 8
09) When the development using the first color Y toner by the development zty started in step 806 is completed (step 810), development using the second color M toner is performed in the same manner as in step 804. After moving the developer s1M to the development position and returning the developer bias voltage and the primary crid bias voltage applied to the grid of the negative charger 4 to the normal values when performing development using the M toner, M) Start developing with the developer and detect the developer concentration in the developing device 1M, and if it is determined that it is necessary during the concentration detection, step 803
, 809, cyan developer (hereinafter referred to as "C toner") is replenished to the developing device 1C (steps 811-816), and the second color by the developing device IM started in step 813. When the development using the M toner is completed (step 817), the third color C toner is completed (step 817).
In order to carry out development using toner, the developing device tC is moved to the development position, and as in step 812, the development bias voltage and the primary high voltage are set to normal values when carrying out development using C toner. After returning, development with the C toner is started and the developer concentration in the development atC is detected (steps 818 to 821).The cyan C toner of the third color aperture is used by the developer IC started in step 820. When the development is completed (step 822), the controller 601 determines whether or not the Y toner replenishment counter i1, which will be described later, has reached a predetermined reference value (step 823).
), when it is recognized that the value of the Y toner replenishment counter has not reached the predetermined reference value as a result of this judgment, the process moves to step 804, and the sequence for the next image copying is executed, and steps 804 to 804 are performed. The processing operations up to step 823 are repeated.

The processing operations from step 804 to step 823 described above are repeatedly executed, and when it is determined that the value of the Y toner replenishment counter has reached a predetermined reference value, step 823) is executed, Y) for toner replenishment. In this sequence, the developing device IY is moved to the Y toner replenishment position 21 (developing device W1 when developing with the developing device BK) (step 824), and the Y toner is replenished by ss as described above. After resetting the Y replenishment flag and the Y toner replenishment counter (step 825), step 80
Move to 4.

Each developing device IY, I carried out in the above-mentioned processing operation
Concentration detection operation of developer in M and Ic (step 807,
The details of steps 814 and 821) are the same for all developing devices, so steps 827 to 84
The process described in 1 will be representatively explained. The controller '5601 drives the lens lamp 402 for density detection by outputting a drive command signal to the load drive circuit 606 via the input/output port 05.

(Step 827) From the input means to the input interface 6
07. Read the reference signal for concentration detection given through the input/output port 05 and store it in the RAM 603 (FIG. 6) (step 828), step 82
After the reference signal is stored in the RAM 603 in step 8, the filters 404 and 405 shown in FIG. 4 are moved to the density detection position (step 829), and the developer at the developing position shown in FIG. The concentration of the developer in the container is read in the same manner as in step 828 and stored in the RAM 60.
3 (step 830), the controller 60
1 in step 828. RAM60 at step 830
Step 831) reads out the reference signal and concentration signal stored in Step 3 again and performs a comparison operation between the two. (step 832), and if it is determined that the above difference A1 is lower than the J-type standard setting data, the toner information indicating that toner replenishment is required for each of the 8 developing units is determined. It is checked whether the replenishment flag has already been set (step 833). If the toner replenishment flag described above is already set in step 833, this means that the developing device requires toner replenishment by 1m%. However, due to the p4 rotational positional relationship between this developing device and other developing devices, the developing device can remain at the toner replenishment position when other developing devices other than this developing device are at the above-mentioned developing position. Therefore, it is impossible to replenish toner! It shows that it is an island. Therefore, in step 805 described above.

Since it becomes necessary to correct the developing bias voltage and the primary high voltage, the developing bias voltage and the primary high voltage are stored in the ROM 602.
Read out the correction f1 data of the next high voltage, and from this data,
Supplementary correction values for the developing bias voltage and the primary high voltage are determined according to the difference value obtained in step 831, and are stored in the RAM 603 (step 836). A replenishment counter for counting the number of sheets of material is counted (step 837). As described above, when this replenishment counter reaches an arbitrary set value in step 823, a toner replenishment sequence for the developing device is executed. That's what happens.

On the other hand, if it is determined in step 832 that the difference value is higher than the standard value, the replenishment flag is reset (step 835), and if it is recognized in step 833 that the replenishment flag is not set, the replenishment flag is set. (
Step 834) and then proceed to step 836.

# When moving from step 832 to step 835, it indicates that toner replenishment is being performed normally, so set the normal values of the developing bias voltage and primary high voltage (step 838). ), the replenishment counter is reset (step 839), the filter 4° 4.405 is moved to the reference signal detection position again (step 840), the driving of the lamp 402 is stopped, and a series of developer density detection operations are performed. finish.

In addition, in order to compare the density of each developer with its standard value data, in this embodiment, as described above, first, the difference I1 between the reference signal and the density signal is calculated, and this difference I1 is compared with the standard value data. If it is smaller than that of the developer, it is determined that the density has become low, but instead of this, for example, it is also possible to divide the density signal by a reference signal to obtain a quotient, and make a judgment based on that value. Furthermore, it is also possible to read each of the (above) & quasi-signal and the density signal several times and store them in the RAM 603, and then calculate and compare the average values of each.

The above explanation is for the case of performing development in so-called 3-color mode using Y toner, M toner, and C toner, but the same sequence as in the 3-color mode described above can also be used in other modes. Toner can be replenished. In other words, when a developing device that requires toner replenishment is at the above-mentioned toner replenishing position while another developing device is performing development, toner replenishment is performed using this position. The output image density is adjusted by correcting the developing bias voltage or primary high voltage as described above without replenishing toner for at least a predetermined number of copies of images on the material, and then the sequence is performed again for toner replenishment. Just do it like this.

As explained above, according to the present invention, if the detected concentration value of the developer does not reach the pre-stored reference concentration value and the image is developed without interrupting the image formation. When there is a developing means for which agent replenishment cannot be performed, the developing bias voltage applied to the developing means and the primary high voltage applied to the image carrier are corrected to pre-stored correction values. Even if some developing means cannot be replenished with developer from the developer replenishing means during execution of the formation sequence, the image density of the output image will not drop significantly and a high-quality image can be obtained. It is possible to provide an image forming apparatus that can

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a sectional view of a rotary developing device according to an embodiment of the present invention. FIG. 3 is a perspective view of a developer (toner) replenishing device according to an embodiment of the present invention. FIG. 4 is an explanatory diagram of the arrangement of the developer concentration detection type according to one embodiment of the present invention. FIGS. 5(a) to 5(e) show the rotary developing device. It is a stop position explanatory diagram of. FIG. 6 is a block diagram of a control system of an image forming apparatus according to an embodiment of the present invention. FIG. 7 is a flowchart of a control sequence in the control system illustrated in FIG. 6. FIG. 8 is a flowchart showing the developer concentration detection and developer replenishment sequence in the sequence shown in FIG. 7. FIG. 9 shows the V-
It is a figure showing a D characteristic curve. lTwo-rotation developing device, IY, LM, Ic, IBK: Developing device for each color 2: Developing device (toner) replenishment device 2Y, 2M, 2C128K: Hopper for each color developing device (external replenishment type r1) 3: Photosensitive (body) drum 26: Developer supply opening 402: Lens wrap 403: Light receiving element sensor 601: Controller 602: ROM 603: RAM Copper 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 (Part 1) Figure, l'iI of chu and [λ in 'tF' Figure 9 V-O curve procedure amendment (method) April 1980 280

Claims (1)

[Claims] 1) An image carrier on which electrostatic latent images of multiple colors corresponding to document image information are formed, and a developer that converts the electrostatic latent images formed on the image carrier in proximity to the image carrier into a visible image. a plurality of developing means that are movable in circulation to different positions and each holding a different color of developer; An image forming apparatus is provided with a developer replenishing means for replenishing developers of different colors, and a developer concentration detecting means is provided for detecting the concentration of the developer remaining in each of the developing means. , storing reference density value data of the developer held in each of the plurality of developing means;
Among the plurality of developing means, there is a developing means in which the concentration value of the developer detected by the developer concentration detecting means does not reach the reference concentration value, and the developing means is supplied with the developer from the developer replenishing means. A storage means is provided for storing correction value data of a developing bias voltage and a primary high voltage when image formation is continued without replenishing the developer, and the developer concentration value detected by the detection means is set to the reference value. When there is a developing means in which the density value has not been reached and developer cannot be replenished without interrupting image formation, the developing bias voltage applied to the developing means and the primary high voltage applied to the image carrier are An image forming apparatus comprising: a control means for correcting the correction value to the correction value.