JPH09218584A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device capable of maintaining a high-image quality and appropriately feeding a carrier. SOLUTION: A developer feeding means 100B for feeding the developer to this device is provided with a carrier feeding part 110B for carrying while feeding the carrier, a toner feeding part 120B for holding and feeding the toner, and a developer mixing/stirring chamber 130B for containing the carrier and the toner to be fed. Then, the carrier and the toner fed to a developer mixing/ stirring chamber 130B or the like are mixed and stirred by a mixing/stirring means 135, thereafter developing units 31B, 32Y, 33M and 34C are replenished respectively. The excess developer in each developing unit 31B, 32Y, 33M and 34C is discharged to a recovering part 200.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine or a laser printer.
The present invention relates to a developing device of an image forming apparatus that stores a two-component developer including a toner and a carrier.

[0002]

2. Description of the Related Art Conventionally, for example, in a dry copying machine, etc.,
A developing device that visualizes, that is, develops an electrostatic latent image on the surface of a photoconductor with a two-component developer including a carrier and a toner is often used. In this type of developing device, the toner is consumed by the developing operation, while the carrier remains in the developing device without being consumed. Therefore, as the stirring frequency of the carrier stirred with the toner in the developing device increases, the toner sticks to the surface and deteriorates, and the charging performance of the developer gradually decreases.

Therefore, a device for replenishing the developing device with a carrier and toner to suppress the deterioration of charging performance is disclosed in, for example, Japanese Patent Laid-Open No. 59-100471. In the disclosed device, the excess developer in the developer tank due to the replenishment of the carrier and toner overflows from the developer discharge port on the wall of the developer tank and is discharged to the waste developer container. It is configured to be. By repeating the replenishment and discharge in this manner, the deteriorated developer in the developing tank is replaced with the newly supplied toner and carrier, thereby maintaining the charging performance and suppressing the deterioration of the copy image quality. there were.

[0004]

However, in the above-mentioned conventional apparatus, the carrier and the toner are suddenly supplied into the developing tank without mixing and agitating them, so that the admix becomes insufficient, resulting in fog, dirt, and Density unevenness has occurred.

Further, in the above-mentioned conventional apparatus, since a constant amount of carrier is always supplied regardless of the deterioration state of the developer, when the supply amount of the carrier is smaller than the consumption amount of the toner, the developer is insufficiently charged. Further, when the supply amount of the carrier is larger than the consumption amount of the toner, the disadvantage that the discharged carrier becomes excessive occurs.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a developing device capable of maintaining high image quality and appropriately supplying carriers.

[0007]

In order to achieve the above object, a developing device of the present invention comprises a carrier supply section for supplying a carrier, a toner supply section for supplying a toner, and a carrier supplied from the carrier supply section. And a plurality of developer supplying means provided with a chamber for accommodating the toner supplied from the toner supply section corresponding to the developing device, and a chamber for accommodating the carrier and toner mixes and agitates the carrier and toner. ,
By the stirring means, the supplied carrier and toner are mixed,
The developer is replenished to the developing device after stirring, and the developer supplying means is configured to move as the developing device moves.

Further, each of the developing units is provided with a detecting means for detecting the deterioration of the developer consisting of toner and carrier, and a carrier supply control section for controlling the carrier supply amount from the carrier supply section according to the deterioration detection signal. As a result, it is possible to maintain high image quality and to appropriately supply carriers.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an electrophotographic full-color image forming apparatus equipped with a plurality of movable two-component developing apparatuses, and FIG. 2 is a schematic configuration diagram in each developing device of the developing apparatus.

The surface of the electrostatic latent image carrier 1 is uniformly charged with a negative polarity by the charger 15. Next, the laser exposure device 13 performs image exposure corresponding to the first color, for example, a BLACK image, and the BLA is formed on the surface of the electrostatic latent image carrier 1.
An electrostatic latent image corresponding to the CK image is formed. Developing device 3
Has a rotational movement type configuration, and before the tip of the electrostatic latent image corresponding to the BLACK image reaches the developing position, B
The first developing device 31B for the LACK development is rotationally moved to a position facing the electrostatic latent image carrier 1. Then, the magnetic brush in the developing unit rubs the electrostatic latent image on the latent image carrier 1 to form a BLACK toner image on the electrostatic latent image carrier 1.

The developing device 3 includes developing devices 31B, 32Y and 33.
Equipped with M and 34C. Developing sleeve 3 in each developing unit
Reference numeral 01 includes a fixed magnet, and is driven and rotated with a predetermined developing interval kept between the magnet and the peripheral surface of the electrostatic latent image carrier 1. The developing sleeve 301 may be in contact with the electrostatic latent image carrier 1.

A regulating member 3 is provided on the surface of the developing sleeve 301.
03 is contacted. The regulating member 303 has rigidity and magnetism, and is pressed against the developing sleeve 301 with a predetermined load without a developer intervening, or is arranged with a predetermined space between the developing sleeve 301 and the developing sleeve 301. Such,
There are various things. Developer agitating and conveying members 305 and 306 for supplying the developer to the developing sleeve 301 are provided. The pair of developer stirring and conveying members 305 and 306 has a screw structure extending in the axial direction of the developing sleeve 301. The screw arranged in the developer stirring / conveying member 305 and the screw arranged in the developer stirring / conveying member 306 are
They rotate in opposite directions, convey and circulate the developer, and send the two-component developer in a state where the toner and the carrier are sufficiently stirred and mixed to the developing sleeve 301.

The magnet rollers 307 contained in the developing sleeve 301 are arranged at equal intervals with N poles and S poles alternately, and are composed of 8-pole magnets having the same magnetic force. In addition, in order to form a repulsive magnetic field at the portion where the magnet roller 307 is in contact with the scraper, and one pole is omitted to make 7 poles in order to facilitate the peeling of the developer, a structure is provided in which the magnet roller 307 is fixed inside the developing sleeve 301. Is also good. Two developer stirring and conveying members 305 and 306
Is a developer stirring member that rotates in mutually opposite directions and also serves as a conveying member that conveys the developer, and by the thrust of the stirring screw, conveys the developer that is replenished from the replenishment port 310 while stirring, The developer is applied in layers on the peripheral surface of the developing sleeve 301. The developer on the surface of the developing sleeve 301 has a dual structure of the non-magnetic material and the magnetic material provided facing the magnetic poles of the magnet roller 307.
03 forms a uniform layer of developer. The developer layer formed in a uniform length develops the latent image on the peripheral surface of the electrostatic latent image carrier 1 in the developing area to form a toner image.

On the other hand, the transfer material 20 such as paper or a transparent sheet is sent out from the first paper feed tray 26 or the second paper feed tray 27 by the feed rolls 28 or 29. The transfer material 20 is once the registration roll 2
After the front end is stopped at 5, it is sent to the transfer drum 5 at a predetermined timing. The transfer material 20 is a suction device 51.
And is electrostatically held on the transfer drum 5 by the opposing roll 53, and the electrostatic latent image carrier 1 is conveyed to the opposing transfer area as the transfer drum 5 rotates. Therefore, the transfer material 20 comes into close contact with the BLACK toner image on the electrostatic latent image carrier 1, and the operation of the transfer device 55 causes the BLACK toner image to be transferred. The transfer drum 5 is rotated while holding the transfer material 20 for the next step.

After the transfer of the BLACK toner image onto the transfer material 20, the electrostatic latent image carrier 1 is then subjected to cleaning pretreatment, if necessary, and then the cleaning device 17
As a result, the BLACK toner remaining on the surface is scraped off, and the charge remaining on the surface is removed by the charge removing device 19.

Next, the electrostatic latent image carrier 1 enters the operation of the image forming process for the second color, for example, YELLOW. The surface of the electrostatic latent image carrier 1 is uniformly charged to a negative polarity by the charger 15, and the laser exposure device 14 performs YELLOW.
Image exposure corresponding to the image is performed, and an electrostatic latent image of a YELLOW image is formed on the surface of the electrostatic latent image carrier 1. After the developing device 3 finishes forming the BLACK toner image,
The second developing device 32Y, which executes the ELLOW development, is switched so as to face the electrostatic latent image carrier 1.
The electrostatic latent image corresponding to the LLOW image is developed with a YELLOW magnetic brush. Then, the transfer material 20 held on the transfer drum is conveyed again to the transfer area as the transfer drum 5 rotates, and by the action of the transfer device 55, the BLA is transferred.
The YELLOW toner is multi-transferred onto the CK toner.

The electrostatic latent image carrier 1 which has completed the transfer of the YELLOW toner is processed in the same manner as in the BLACK image forming step.
The residual toner on the surface is cleaned and the residual charge is removed. On the other hand, the transfer material 20 that has finished transferring the YELLOW toner is held on the transfer drum 5 for the next step, for example, image formation of MAGENTA for the third color. The process, and finally the fourth color, CYAN image forming process is prepared. Last C
In the YAN image forming process, the transfer material 20 is conveyed differently from the third color conveying process. That is, the transfer material 20 after the transfer of the fourth color is separated from the transfer drum 5 by the peeling static eliminator 57 and the peeling fingers (not shown) at the tips of the transport guide members 59, and the fixing device 60 fixes the multiple toner image on the transfer material. After that, it is carried out of the image forming apparatus.
After the transfer material has been separated, the surface of the transfer drum 5 is discharged by the discharging device 54, and then the cleaning device 56 is used.
Then, the surface is cleaned and the next supply of the transfer material 20 is awaited.

When the image forming operation is repeated as described above, the toner in the developer accommodated in the developing tank 309 in the developing device is gradually consumed, and the ratio of the toner to the carrier, that is, the toner concentration decreases. To do. Therefore, a toner concentration sensor (not shown) is provided in the developing tank 309 to detect a change in toner concentration. Then, in response to the toner concentration detection signal, the control device performs feedback control so that the toner concentration falls within an appropriate range required for development, and the toner is supplied from the replenishing port 310 of the toner replenishing section to the developing tank 309 in the developing device. It

On the other hand, the carrier in the developer in the developing tank 309 is not consumed by the development. However, the surface and the like are gradually contaminated and deteriorated due to the effects of being stirred with the toner in the developing tank 309, the magnetic force of the mag roll, and the contact with the electrostatic latent image carrier 1.
Deterioration of the carrier does not give a predetermined charge amount to the toner, resulting in deterioration of image quality. Therefore, it is necessary to replace the deteriorated carrier which is not consumed in the developing device with a new carrier.

Next, the construction of the developing device according to the present invention and the operation of replacing the developer will be described with reference to FIGS. Figures 3 and 4
FIG. 3 is a schematic view of a developing device. In a full-color image forming apparatus using a developing device 3 that employs a rotational movement method, a developer supplying device 100 (B, Y, M, C) is provided in the developing device 3, and the developer is provided close to the developing device 3. Collection part 2
00 is provided.

Since the respective developer supply devices 100 have the same structure, the first developer supply device 100B for supplying the developer to the first developing device 31B will be described. The developer supply device 100B includes a carrier supply unit 110B, a toner supply unit 120B, and a developer mixing and stirring chamber 130B. The carrier supply unit 110B stores a carrier, and the toner supply unit 120B stores BLACK toner. Then, the carrier and toner are supplied to the developer mixing and stirring chamber 130B from the carrier supply unit and the toner supply unit. The developer mixing / stirring chamber 130B incorporates a mixing / stirring unit 135 such as a screw and a paddle, and mixes and stirs the supplied toner and carrier. The developer supply device 100 configured as described above includes a toner supply unit 12 that stores BLACK toner in the toner supply unit.
First developer supply device 100B having 0B, toner supply unit 12 that stores YELLOW toner in the toner supply unit
A second developer supply device 100Y having 0Y, a toner supply unit 1 for storing MAGENTA toner in the toner supply unit 1
A third developer supply device 100M having 20M, and a toner supply unit 120 that stores CYAN toner in the toner supply unit.
A fourth developer supply device 100C having C is provided, and inside the development device 3, for example, a first developing device 31B and a first developer supplying device 100B, a second developing device 32Y and a second developing device are provided. The developer supply device 100Y, the third developing device 33M and the third developer supply device 100M, and the fourth developing device 34C and the fourth developer supply device 100C are arranged in a pair.

For example, the developer supply device shown in FIG.
First developer supply device 100 corresponding to the developing device 31B of
The case where B has moved to the developing position is shown. The toner (BKACK toner) corresponding to the first developing device 31B is stored in the toner supply unit 120B of the first developer supply device 100B. A carrier is stored in the carrier supply unit 110B. Then, a fixed amount of toner and a carrier are supplied to the developer stirring chamber 130B in response to a detection signal from a toner concentration detector provided in the first developing device 31B. In the developer mixing and stirring chamber 130B, the carrier and the B
The LAC toner is mixed and stirred by a mixing and stirring means.

The first developing device 31B, the second developing device 32Y, the third developing device 33M, and the fourth developing device 34 of the developing device 3.
C rotates and moves inside the developing device 3, and the first developing device 31
At the time of development, B is rotationally moved to a development position facing the electrostatic latent image carrier 1 to perform development, and non-development second, third, and fourth
The developing device rotationally moves to a non-developing position which is not opposed to the electrostatic latent image carrier 1. Then, during development in which the developing device 31B faces the electrostatic latent image carrier 1, the first developing device 31B is replenished with the mixed and stirred toner and carrier from the developer mixing and stirring chamber 130B. The developer collecting section 200 is arranged at a position facing the fourth developing device 34C. And
The deteriorated developer discharged from the fourth developing device 34C is collected.

The image forming apparatus rotates the developing device 3 in response to the next image forming process. Here, the developing device 3 shown in FIG. 4 shows a case where the developing device 3 shown in FIG. 3 is rotated clockwise by 90 degrees. That is, the electrostatic latent image carrier 1
The developing device 31B, which is supported by the position opposed to the developing device 31B and was in the developing operation, ends the developing operation and rotationally moves to the non-developing position that is not facing the electrostatic latent image carrier 1. Along with this, the second developing device 32Y is rotationally moved to the position of the third developing device 33M, the third developing device 33M is moved to the position of the fourth developing device 34C, and the fourth developing device 34C is electrostatically moved. The latent image carrier 1 is rotatably moved to and supported by a position facing the latent image carrier 1, and the developing operation can be started if necessary.

Here, the developing device 34C facing the electrostatic latent image carrier 1 at the time of development is replenished with the mixed and stirred toner and carrier from the developer mixing and stirring chamber 130C. That is, the developer in the developer mixing / stirring chamber 130C of the fourth developer supply device 100C is stored in a state in which the amount of the carrier and the toner to be replenished controlled by the control device are sufficiently mixed and stirred. , The developer that is sufficiently mixed and stirred is supplied to the first developing device 34C. At this time, the third developing unit 33M confronts the deteriorated developer collecting section 200, and discharges the deteriorated developer in the developing unit 33M to the collecting section 200.

As described above, each of the developing devices 31B and 3B
2Y, 33M, and 34C are in the developing position facing the electrostatic latent image carrier 1 as the developing device 3 rotates,
The developer is supplied. In this way, the developer supplied from the developer supply device to each of the developing devices is supplied to the developer mixing / stirring chambers 130B, 130Y, 130, respectively.
Since the carrier and the toner are mixed by M and 130C and sufficiently mixed and stirred by the stirring means, they are replenished in an optimal state without fog, dirt, density unevenness, etc. due to insufficient admixture, and good image quality can be maintained.

Next, an embodiment in which the replenishment of the carrier is controlled according to the deterioration state of the carrier to adjust the toner concentration of the developer in each developing device will be described with reference to FIG. In the developer supply device 100 according to this embodiment, the shutter 1 is provided at the supply port (not shown) of the carrier supply section 110 to the developer mixing / stirring chamber 130.
50 is provided to open and close the supply port. A toner detection signal from the toner concentration sensor 40 provided in each developing device is transmitted to the carrier replenishment controller 400. In the carrier replenishment control unit 400, the developing device
In this drawing, the deterioration state of the carrier of the first developing device 31B is determined. The carrier replenishment controller 400 uses the shutter 1
An opening / closing signal is transmitted to the solenoid 160 that executes opening / closing of 50. That is, the carrier replenishment control unit 400 determines carrier deterioration, transmits a signal for opening and closing the shutter 150 to the solenoid 160 depending on the deterioration condition, and adjusts the supply of the carrier to the developer mixing and stirring chamber 130B.

Further, in this embodiment, the toner density sensor is used as the carrier deterioration detecting means, however, the deterioration of the developer may be detected by other environmental sensors, the print number counter or the like. As described above, in this embodiment, since the supply amount of the carrier supplied to each developing device is controlled so that the toner concentration is within the proper range, the toner concentration does not decrease. Further, it is possible to prevent excessive discharge due to excessive supply of carriers.

[0029]

According to the present invention, the carrier and toner of the two-component developer supplied to the developing device are replenished in a state where both are sufficiently mixed and stirred, and therefore, fog, dirt, uneven density, etc. due to insufficient admixing. Can be prevented, high image quality can be maintained, and proper supply of carriers can be achieved. Further, by replenishing the carrier depending on the deterioration state of the developer, it is possible to prevent excessive carrier discharge when the carrier supply amount is larger than the toner consumption amount.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a full-color image forming apparatus according to the present invention.

FIG. 2 is an explanatory diagram of a configuration of a developing device.

FIG. 3 is a partially enlarged explanatory view of the developing device.

FIG. 4 is an explanatory view of each developing device when the developing device shown in FIG. 3 is rotated 90 degrees clockwise.

FIG. 5 is a schematic view showing an embodiment of another developing device.

[Explanation of symbols]

1 electrostatic latent image carrier, 3 developing device, 5 transfer drum, 13 laser exposure device, 15 charging device,
17 cleaning device, 19 static eliminator, 20 transfer material, 25 registration roll, 26, 2
7 paper feed trays, 28, 29 delivery rolls, 3
1B 1st developing device, 32Y 2nd developing device, 33
M third developing device, 34C fourth developing device, 40
Toner concentration detection sensor, 51 Opposite roll, 53
Adsorption device, 54 static eliminator, 55 transfer device,
56 transfer cleaning device, 57 peeling static eliminator, 5
9 conveyance guide member, 60 fixing device, 100 developer supplying device, 110 carrier supplying part, 115
Supply port, 120 toner supply section, 130 developer mixing and stirring chamber, 135 mixing and stirring means, 150 shutter, 160 solenoid, 200 deteriorated developer collecting section, 301 developing sleeve, 303 regulating member,
305 developer stirring / transporting member, 306 developer stirring / transporting member, 307 magnet roll, 309 developing tank, 310 developer replenishing port, 400 carrier replenishing controller.

Claims (3)

[Claims] 1. An image forming apparatus comprising: a developer supply unit that replenishes a developer including a toner and a carrier to a developing unit; and a recovery unit that collects the developer including the toner and the carrier discharged from the developing unit. In the developing device, the developer supply unit includes a carrier supply unit that supplies a carrier, a toner supply unit that supplies toner, and a room that stores the carrier supplied from the carrier supply unit and the toner supplied from the toner supply unit. A developing device having a chamber for storing the carrier and the toner, which has a mixing and stirring means for mixing and stirring the carrier and the toner, and configured so that the supplied carrier and the toner are mixed and stirred, and then supplied to the developing device. . 2. The developing device according to claim 1, wherein a plurality of developer supplying means are provided in correspondence with the developing device, and move with the movement of the developing device. 3. The developing device comprises a detection means for detecting deterioration of the developer, and a carrier supply control portion for outputting a carrier supply amount adjustment signal to the carrier supply portion in response to a detection signal from the detection means. 1. The developing device according to 1.