JPS61203479A - Developing device - Google Patents

Abstract

PURPOSE:To perform invariably proper developer supplying operation by storing the density detection position and supply position of a developer relevantly and carrying out a developer supplying operation sequence according to them. CONSTITUTION:Density signals of respective developers detected by a photodetecting element 403 and a reference signal are inputted to a controller 601 through an amplifier 401, an A/D converter 608, and an input/output port 605. A ROM 602 is stored with the density detection position and supply position of the developers relevantly. The controller 601 controls input/output operation while storing a RAM 603 with necessary data, etc., according to the program, table data, etc., in the ROM 602.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a developing device, and particularly to a developing device equipped with a plurality of developing devices.

[Prior art]

An electrophotographic color printer will be described as an example of an image forming apparatus equipped with a conventional developing device of this type. In these devices.

2. Description of the Related Art Conventionally, a developing device comprising a plurality of developing units has been used, for example, in a copying machine, when developing two colors or when making full-color copies. Among these, a copying machine that performs full-color copying usually requires the number of developing devices for four colors including black.

In the above-mentioned copying machine, when multiple developing devices are arranged in parallel along the outer periphery of the photosensitive (body) drum or insulated drum that develops the electrostatic latent image, it is easier to make copies than in the case of normal black and white copying. Since approximately four times as much space is required, it is difficult and rare to reduce the diameter of the photosensitive drum or insulating drum.

In order to avoid the above-mentioned difficulties, for example,
Japanese Patent No. 93437 and the like propose a method in which a plurality of developing devices are mounted on a rotating gondola and the required developing devices are fixed close to a photosensitive drum or an insulated drum only when necessary. Hereinafter, the type described above will be referred to as a ``rotary developing device''.

Also, regarding the concentration detection of developer such as toner, for example,
Instead of installing one detection device for each developer, one detection device is installed at a predetermined position in the main body of the copying machine, and detection is performed when each developer is placed in that position. Proposals have been made to reduce the size of the developing device by avoiding duplication of detection devices.

As a method of replenishing toner etc. to these developing devices, a method of providing a hopper inside each developing device has been proposed.
If the rotary developing device is downsized, the hopper capacity of each developing device tends to be insufficient.On the other hand, if you try to secure sufficient hopper capacity, each developing device, and therefore the entire rotary developing device, will also become insufficient. There is a possibility that the size will increase and new problems will arise in terms of control.

〔the purpose〕

The present invention has been made in view of the above-mentioned problems, and is provided with a developer replenishing device for replenishing each developer to a developing device having a plurality of developing devices mounted on a rotating body. , the developer concentration detection position and the developer replenishment device are 1
In order to overcome the problem that the positional relationship of each rotating developing unit is different, the developer replenishment operation is appropriately controlled by storing the respective developer concentration detection positions -° and replenishment positions in association with each other. The purpose of the present invention is to provide a developing device that can.

〔Example〕

The present invention will be explained below based on the drawings. FIG. 1 shows an explanatory view of the overall configuration of an electrophotographic color printer as an example of an image forming apparatus equipped with a developing device according to the present invention. Reference numeral 1 denotes a rotary developing device in which a yellow developing device 1Y, a magenta developing device 1M, a cyan developing device 1C, and a black developing device 18K are mounted, respectively.

2 is an external developer (toner) replenishing device, 2Y is a yellow hopper, 2M is a magenta hopper, 2C is a cyan hopper, and 28 is a black hopper.

Regarding the entire sequence of this color printer, first,
A brief explanation will be given using the full color mode as an example. 3
1 is a photosensitive (body) drum that rotates in the direction of the arrow shown in the figure, and the photosensitive body on the drum is uniformly charged by a charger 4. Next, image exposure is performed using laser light E modulated by a yellow image signal of a document (not shown), and an electrostatic latent image is formed on the photosensitive drum 3. After that, an electrostatic latent image is formed on the photosensitive drum 3.

Developing is performed by the yellow developing device 1Y, which is placed in advance at the developing position.

On the other hand, paper feed guide 5a, paper feed roller 6, paper feed guide 5b
The transfer paper that has progressed through is held by the gripper 7 in synchronization with a predetermined timing, and is electrostatically wound around the transfer drum 9 by the contact roller 8 and its opposing pole. The transfer drum 9 rotates in the direction of the arrow in the figure in synchronization with the photosensitive drum 3, and the developed image developed by the yellow developer Y is transferred by the transfer charger 10 in the transfer section. The transfer drum 9 continues to rotate and prepares for transferring the primary color (magenta in FIG. 1).

On the other hand, the photosensitive drum 3 is neutralized by the charger 11, cleaned by the cleaning member 12, and charged by the P+ charger 4.

The next magenta image signal receives the exposure as described above. During this time, the developing device 1 rotates, and the magenta developing device 1M
is fixed at a predetermined image position and performs predetermined magenta development. Subsequently, one or more such processes are performed for cyan and black, respectively, and when the transfer of four colors is completed.

The charges of the four colors on the transfer paper are removed by each charger 13, 14, and the gripper 7 is released.

The image is separated from the transfer drum 9 by the separation claw 15 and sent to the fixing device 17 by the conveyor belt 16, completing a series of full-color print sequences and forming a desired full-color print image.

FIG. 2 is a sectional view of an example of a rotary developing device according to the present invention, and FIG. 3 is a perspective view of a developer (toner) replenishing device. Each developer IY, IM.

1C and 18KFi, respectively, are magnetic brush development type using a two-component developer consisting of a magnetic powder carrier and toner, and a screw 22 a is used to circulate the developer.
+ 22 b , formed by a magnet roller 21 and the like for forming a magnetic brush. 23 is a shutter member for opening and closing the opening 26 for toner replenishment, and when the shutter member is moved to the toner replenishment position (in FIG. 2, the position where the magenta developing device 1M is located), it is fixed on the central shaft 27. The shutter lever 24 is rotated by the cam 25 to open the shutter 23 of the opening 26, making it possible to replenish toner.

On the other hand, 31M in FIG. 3 is a screw for replenishing toner, which is rotationally driven by a motor (not shown).
Transfer the magenta toner in hopper 2M to magenta developer 1M.
2 to the opening 26 (FIG. 2). 31Y, 318, and 31C are the same as above, and repeated explanation will be omitted.

FIG. 4 is an explanatory diagram of the arrangement of the developer concentration detection device according to the present invention, in which one device in FIG. I
One unit is installed for M, IC, and IBK. When each of the above-mentioned developing devices is placed at a predetermined developing position (the position of the yellow developing device 1Y in FIG. 2), both the above-mentioned devices 4a), 1
(b) is connected to complete the concentration detection circuit. In this state, the light beam emitted from the lens lamp 402 is guided to the optical fiber 406 and then to the dichroic mirror 407. The developer 41 passes through the EL glass 408 and is in the non-developing position at the end on the sleeve 21 (Fig. 2.4).
irradiated to 0.

Here, of the light emitted from the lens lamp 402, white light is reflected by the dichroic mirror 407, and near-infrared light is reflected by the developer 410 and scattered. The scattered light.

A portion of the light is focused onto an optical fiber 411 by a SELFOC lens 409, passes through the optical fiber 411 and a filter 404 or 405, and then is irradiated onto a light receiving element sensor 403 such as a photodiode. filter 4
04 is a filter through which only white light is transmitted, and filter 405 is a filter through which only near-infrared light is transmitted, 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 amplifier 401, converted into analog/digital data, and then read by the controller (see FIG. 6, which will be described later). The concentration value of the developer can be determined by calibrating it using the reference signal.

Next, regarding the detection of the amount of toner remaining in each hopper 2Y, 2M, 2G, and 28, a toner sensor using a piezoelectric element is provided inside each of the hoppers, and this detects the amount of developer remaining. ing.

In a rotary developing device equipped with a developer concentration detection device and a developer replenishment device as described above, the relationship between the development position of each developer and the developer concentration detection position and the developer replenishment position is as follows. Since it differs depending on the rotational angular position of the developing device, it is not possible to measure the concentration of the developer and immediately replenish the developer.

5(a) to 5(e) are diagrams showing respective stopping positions of the rotary developing device 1 with respect to the photosensitive drum 3, and when the reference position is determined as shown in FIG. 5(at), the reference position is Each developing device IY, IM, IC, 1 at each rotation angle position of 45°, 135°, 225° and 315° from
The relationship between the developing position in 8, each developer concentration detection position, and each developer replenishment position is shown in FIG. The developing device (e.g., developing device IY in the lb figure) is at the replenishment position, and the developing device located opposite the photosensitive drum 3 (e.g., the developing device 18K in the figure (b)) is the developing device that detects the developing position and developer concentration. The developing device is located at

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.

Next, operation sequence control when using the developer concentration detection device, developer replenishment device, and developer remaining amount detection device as described above will be explained. FIG. 6 shows a block diagram of a control section of an electrophotographic color printer based on this embodiment. 0. ．． 0. ．． 0. . . , Om are developer detection lamps. Each developer hopper drive motor, development drive motor, and other loads necessary for printer control are driven by a load drive circuit 606 via a controller 601 or a random signal via an input/output port 05.

Also, % 111 "t #13, · a, Im are each hopper 2Y, 2M, 2C.

After adjusting the level using the input interface 607 using the developer remaining amount detection signal in the 2BK and other input means necessary for printer control, the signal is input to the controller 601 through the input/output port 05. Reference numeral 604 denotes a display and operation unit that displays the remaining amount of each developer and includes other displays and switches necessary for the printer, and is connected to the controller 601 through an input/output port 05.

The output level of each developer density signal and reference signal detected by the light receiving element cell 403 (FIG. 4(a)) is adjusted by the amplifier 401, and then sent to the analog/digital converter 60.
After being digitally converted by 8, it is input to the controller 601 through the input/output port 05. The controller 601 stores necessary data etc. in the ROM 60 according to the program and table data etc. of the fLOM 602.
Input/output is controlled while storing data in 2.

FIG. 7 is a flowchart showing the concept of sequence processing for controlling the printer body in this embodiment. This sequence basically counts pulses from an encoder (not shown) that rotates in synchronization with the drive motor of the photosensitive drum 3.
The reference position of the transfer drum 90, which is advanced according to this count value and rotates in synchronization with the photosensitive drum 3, is moved.

A shutter disposed on the transfer drum 9 crosses a photo interrupter (not shown).

The count value is reset, and the number of rotations of the transfer drum 9 is also detected. When these count values match the set values set in advance in the ROM 602 (FIG. 6) (step 701), processing based on the set values, such as turning on the developing drive motor, is performed, and as shown in FIG. The described operating sequence proceeds.

FIG. 8 shows an excerpt of only the processes related to development, developer concentration detection, and developer (toner) replenishment operations from the processing in step 702 in FIG. 7 when the printer of this embodiment prints in full color. This is a flowchart that successively explains these operational processing sequences, and the determination of clock coincidence and the like are omitted. Also, Figure 9 shows the current f
This is a timing chart of each process in C regarding the image, developer concentration detection, and developer replenishment.

(Figure a1 is a timing chart example in which full color is printed continuously, figure (b) is a continuous black color, and figure (C) is a timing chart in which full color, black monochrome, and full color are printed continuously.

Next, regarding the case of full-color continuous printing shown in FIG. 9 fa), the flowchart K in FIG. 8 and therefore the sequence will be explained. First, after feeding the first sheet of paper to the printer, in step 801, the developer is moved to the replenishment position for the first color (yellow Y in the case of Figure 8), and the Y toner replenishment flag, which will be described later, is checked. Then, it is determined whether it is necessary to replenish Y) toner (step 802), and if necessary, replenish Y toner and reset the Y toner replenishment flag (step 803). Next, move the developing device 1Y to the developing position for the first color (yellow) again (step 804).
, starts developing the first color (step 805). Then, during the development of the first color, the concentration of the developer in the developing device is detected (step 806). At this time, the developing device 1Y uses the fact that it is at the toner replenishment position of the developing device 1M to determine whether or not it is necessary to replenish the M toner based on the M toner replenishment flag (step 807). Perform replenishment and reset the M toner replenishment flag (step 8)
08).

When the development of the first color (yellow) is completed (step 809), the next step is to move to the development position of the second color (magenta), start development of the second color in the same manner as the first color, and start the development of the second color. The developer concentration of the second color is detected, and if necessary, the third color (cyan) toner is replenished (step 81).
1-815). Below, the third color (cyan) and the fourth color (
Similar processing is performed for black) (step 81).
7 to 827), when the development of the fourth color is completed, jump to step 804 again.

Perform the sequence for the next image and repeat the process.

Next, the concentration detection operation of each developer in each developer IY, IM, 1G, and 18 is performed (steps 806, 812, 818, 8).
Regarding the details of step 24), since the processing is the same for all developing devices, step 82B will be representatively explained. First, in step 829, the lens lamp 402 (FIG. 4) for density detection is turned on, and a reference signal for density detection is read and stored in the fLAM 603 (FIG. 6) (step 830). Next, move the filters 404 and 405 in FIG. 4 to the concentration detection position (Step 831), read the concentration of the developer,
03 (step 832). Here, R
The reference signal and the density signal stored in the AM603 are output again one after another, and the two are compared, and this comparison value is obtained.

Step 834), compared with the standard developer preset for each development 4 in the ROM 602 (FIG. 6);
If it is determined that the developer concentration is lower than the standard developer concentration, a toner replenishment flag indicating that the developer requires toner replenishment is stored in the AM 603 (step 835). Then, the filters 404 and 405 are moved to the reference signal detection position again (step 836), and the lamp 4
When 02 is set to 0FFI, the developer concentration detection operation is completed.

Steps 806, 812, 818, 824
In this case, each development 4 is performed separately.

In this example, the density of each developer and its standard value are compared by finding the difference between the reference signal and the density signal as described above, and comparing this difference with that of the standard developer. If the value is smaller, the concentration is judged to be lower, but instead of 1
For example, it is also possible to divide the density signal by the reference signal to obtain a quotient and make a judgment based on that value. Also, read the reference signal and concentration signal several times each.

It is also possible to store them in the AM 603 and calculate and compare their average values. Furthermore, in this embodiment, the lamp 402 is turned ON only when the developer concentration is detected, considering the lifespan of the lens lamp 402 and the temperature rise due to the lens lamp 402, but these considerations are necessary. If not, the lamp 402 can be kept on all the time.

The above has been explained using the full-color continuous print shown in Figure 9(a) as an example, but in the case of single-color (black in this case) continuous print as shown in Figure 9(b), the development of each image A rotation for toner replenishment is provided between the development and development, and after each development, the developer is moved to the toner replenishment position, toner is replenished if necessary, and then the developer is moved to the development position again. Then, the next image is developed.

In this embodiment, in order to simplify the sequence and improve toner agitation effects, the rotation for replenishment is always performed even if it is detected by developer concentration detection that toner replenishment is not necessary at that time. The developing device is rotated to the replenishment position (at this time, toner is not replenished), but if you want to give priority to the durability of the rotary developing device or the improvement of copying speed, you can replenish toner. The addition of the above-mentioned rotation for the purpose may be omitted.

Also, full color, single color in Figure 9 1c).

The same applies to continuous full-color prints.

Toner replenishment is required for a certain developing device (1 (, A
If the toner replenishment flag is set in M603), the target of the development must be replenished with toner before the development is performed.

Here, when the developing device that requires toner replenishment is at the toner replenishment position during the previous development.

If this is not the case, a rotation for toner replenishment is provided to perform toner replenishment.

In other words, for a developing device that is equipped with a memory related to the angular arrangement of the developer concentration detection position and the toner replenishment position and that performs development, if toner replenishment is required, the toner replenishment must be performed before performing development. However, on the other hand, for a developing device that does not need to perform development, unless it is moved to the toner replenishing position during development with another developing device, it is not necessary to move it to the toner replenishing position and replenish it. Instead, the fact that toner replenishment is required is stored in the memory (that is, the toner replenishment flag is left set).

This is to replenish toner when it is necessary to carry out development.

In the developer concentration detection and developer replenishment sequences described above, control is performed assuming that the concentration detection signals obtained are all correct, but for example, if the lens lamp 402 (Fig. 4) is deteriorated or disconnected, or if the Contamination of fibers 406, 411, filters 404, 405, etc.

Alternatively, due to a disconnection in the transmission path of the signal obtained by the light receiving element sensor 403, a signal different from the original concentration signal may be read. In such a case, if the sequence is continued as it is, the density of the developer will become extremely low, or conversely, the toner will be replenished until it overflows from the developer. In order to avoid the possibility of such a situation, abnormality detection can be performed by the following method.

In FIG. 4, when the lens lamp 402 deteriorates or the optical path from the lamp is contaminated, the intensity of light irradiated to the light receiving sensor 403 also decreases, and the output signal level of the amplifier 401 also decreases. The reference signal and concentration detection signal read by the method shown in FIG. By reading that these signals have become lower than a predetermined value, it is possible to detect the occurrence of deterioration or disconnection of the lamp 402, contamination of the optical path, or the like.

Furthermore, FIG. 10 is a circuit diagram of the concentration detection signal reading section of the developer concentration detection device in FIG. 6. Same figure (b)
The circuit in section 81 is on the same board as the printer main body and control circuits such as the controller 601, and is on a separate board from the circuit in section 81 in the same figure.

Both boards are connected by connectors J1 and J2. Here, when the connector J2 is in an open state, the read signal has a higher value than a normal signal.

Therefore, by reading that this signal has become higher than a predetermined value, it is possible to detect whether or not the connectors j1 and ``2'' are connected.

In this example, the lowest reference signal value and the highest reference signal value that can normally detect the developer concentration are set to 0M6.
02 in advance, and in step 830 in the flowchart of FIG.
AM5Q3 and this reference signal is stored in the RO
Compare and judge whether it is between the upper and lower limits of the M602 setting value, and if it is between them, continue the sequence as it is, but if it is determined that it is outside the range, the sequence will be interrupted and an error (not shown) will be detected. Jumps to the processing routine, disables replenishment of developer, and displays 1 display section 60.
4, and no further print commands will be accepted.

Further, in this embodiment, not only the developer concentration detection means but also the hopper 2Y for each color developer.

Each of 2M, 2G, and 28K is also equipped with a developer remaining amount detection means using a piezoelectric element (not shown). As mentioned above, the developer concentration is detected according to the flowchart shown in FIG. 8, and the developer remaining amount can always be detected regardless of the position of the rotating developer. It may be detected in an interrupt processing routine using an interval timer (not shown), or in steps 803, 808, and 8 in the flowchart of FIG.
14.820.826 may be detected every time the developer is replenished. Combinations of these two detection results are shown in Table 2.

Table 2 In the table above, the circle mark in the developer remaining amount detection column indicates.

It shows that the concentration is appropriate, and the X mark shows that the concentration is low. In addition, ○ and X in the developer concentration detection column each indicate the presence or absence of a remaining amount. In case ■, the detection results for both cars indicate that they are appropriate, so the sequence continues as is.

In case 2, the amount of developer (toner) remaining in the hopper is insufficient, but the developer concentration indicates that development is still possible.
(Fig. 6) gives a preliminary warning of no toner. When the state changes from case ■ to case ■, no new transfer paper is fed, and all of the paper currently inside the printer is At the same time as the transfer paper is discharged, the sequence is terminated, and the display that was "preliminary warning of no toner" is changed to the display of "no toner". here,
The above-mentioned 1 preliminary warning display and the ``toner out'' display may be displayed separately, or a single display may be used to indicate ``preliminary warning'' by blinking, and ``toner out'' by continuously lighting. They may be distinguished as shown.

Next, in the case (2), since the developer concentration is low and there is still toner remaining in the hopper, toner is replenished according to the flowchart shown in FIG. 8 described above.

〔effect〕

As explained above, according to the present invention.

In a developing device having a plurality of developing devices mounted on a rotating body, the positional relationship of each developing device at the time of developer concentration detection and the time of developer replenishment is memorized, and the developer replenishment operation sequence is performed by turning. Therefore, even if the positional relationship between the developing devices is different between the developer concentration detection position and the developer replenishment position.

It is now possible to always maintain an appropriate developer replenishment position.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the overall configuration of an example of an electrophotographic color printer equipped with a rotary developing device according to the present invention, FIG. 2 is a sectional view of an example of the rotary developing device according to the present invention, and FIG. is a perspective view of a developer (toner) replenishing device, FIG. 4 is an explanatory diagram of the arrangement of a developer concentration detection device based on the present invention, and FIGS. 6 is a block diagram of the control unit of the color printer of the embodiment, FIG. 7 is a flowchart of the control sequence shown in FIG. 6, and FIG. 8 is a flow chart of the developer concentration detection and developer replenishment sequence. Flowchart, Figure 9 (a
) to (C) are timing charts of the developer concentration detection and developer replenishment sequences, and FIG. 10 is a circuit diagram of the developer concentration detection device. 1...Rotary developing device IY, IM, IC, 18K...each color developing device 2...
...Developer (toner) supply device 2Y, 2M,
2C, 28K...Developer hopper for each color (external supply device) 3...Photosensitive (body) drum 26...
・Developer supply opening 402...Lens lamp 403...Light receiving element sensor 601...Controller 602...ROM 603...RAM Fig. 2 Fig. 3

Claims (1)

[Claims] A developing device comprising a plurality of developing devices mounted on a rotary body and performing development by rotationally moving each of the developing devices, a replenishing means for replenishing each developing device with each developer, and a developing device in each of the developing devices. A detection means for detecting developer concentration and a storage means for storing the developer concentration detected by the detection means are provided, and the positional relationship of each developing device with respect to the developer concentration detection position and the developer replenishment position and the memory are provided. A developing device characterized in that said developer replenishment operation is controlled in accordance with a developer concentration stored in said means.