JP2003107894A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which can stabilize image density by suppressing a ripple of developer density. SOLUTION: The image forming device uses a two-component developer consisting of toner and a carrier, has a plurality of developing devices which have developing sleeves (developer carrier) 41 carrying the developer and agitating screws (agitating member) 42 carrying and agitating the developer, an image data counter which counts and integrates image data of an image developed by the developing devices, and a developer detecting means which detects information on toner consumption in the developer by integrating the image data, and supplies toner according to a toner supply signal corresponding to the signal of the detecting means; and developer circulation paths of the developing devices are sectioned into a plurality of blocks, the image data of the respective blocks are integrated to detect the toner variation state of the developer, and the toner is supplied according to the variation quantity.

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 a copying machine or a printer.

[0002]

2. Description of the Related Art FIG. 7 is a schematic cross-sectional view of a conventional color image forming apparatus. The illustrated color image forming apparatus has a digital color image reader section in the upper part and a digital color image printer section in the lower part.

In the reader unit, the original 30 is placed on the original table glass 31, the reflected light image from the original 30 exposed and scanned by the exposure lamp 32 is condensed by the lens 33 on the full color sensor 34, and the color separated image signal is obtained. obtain. The color-separated image signal is processed by a video processing unit (not shown) through an amplifier circuit (not shown) and sent to the printer section. In the printer section, the photosensitive drum 1 as an image bearing member is rotatably supported in the direction of arrow R1.
Around the front exposure lamp 11, corona charger 2, exposure optical system 3, potential sensor 12, four developing devices 4y, 4c, 4
m, 4Bk, on-drum toner detection means 13, transfer device 5, and cleaning device 6 are arranged.

An image signal from the reader unit is input to the laser beam exposure optical system 3, the laser output unit (not shown) converts the image signal into an optical signal, the laser beam is reflected by a polygon mirror 3a, and a lens 3b is used. And a surface of the photosensitive drum 1 through the mirror 3c to be converted into an optical image E which is linearly scanned (raster scan). When forming an image on the printer unit, first, the photosensitive drum 1 is rotated in the direction of the arrow R1, the pre-exposure lamp 11 is discharged, and then uniformly charged by the charger 2, and then the light image E is irradiated for each separated color. Form a latent image.

Next, the latent image on the photosensitive drum 1 is developed by operating a predetermined developing device for each separated color, and an image is formed on the photosensitive drum 1 with toner having a resin base. The developing device is adapted to selectively approach the photosensitive drum 1 according to each separated color by the operation of the eccentric cams 24y, 24c, 24m and 24Bk. Further, the toner image on the photosensitive drum 1 is transferred to the recording material supplied from the recording material cassette 7 to the position facing the photosensitive drum 1 via the transport system and the transfer device 5.

The transfer device 5 includes a transfer drum 5a,
A transfer charger 5b, an attraction charger 5c for electrostatically attracting the recording material, an attraction roller 5g facing the attraction charger 5c, an inner charger 5d,
A recording material carrying sheet 5f made of a dielectric material is integrally stretched in a cylindrical shape in an opening area of a peripheral surface of a transfer drum 5a which has an outer charger 5e and is rotatably supported. A dielectric sheet such as a polycarbonate film is used as the recording material carrying sheet 5f.

As the drum-shaped transfer device, that is, the transfer drum 5a is rotated, the toner image on the photosensitive drum 1 is transferred onto the recording material carried on the recording material carrying sheet 5f by the transfer charger 5b. In this way, a desired number of color images are transferred to the recording material that is adsorbed and conveyed to the recording material carrying sheet 5f to form a full-color image. In the case of the four-color mode, when the transfer of the four-color toner images is completed in this way, the recording material is separated from the transfer drum 5a by the action of the separation claw 8a, the separation push-up roller 8b, and the separation charger 5h, and the heat roller fixing is performed. The paper is discharged to the tray 10 via the container 9.

On the other hand, the post-transfer photosensitive drum 1 is subjected to an image forming process again after the residual toner on the surface is cleaned by the cleaning device 6. When images are to be formed on both sides of the recording material, immediately after discharging the fixing device 9, the conveyance path switching guide 1
9 is driven, and is guided to the reversing path 21a through the paper discharge vertical path 20 and then the recording material is temporarily stopped, and the reversing roller 21b is
When the sheet is fed, the trailing edge of the fed sheet is the leading end and the sheet is ejected in the direction opposite to the fed direction, and the recording material is turned over and stocked in the intermediate tray 22. After that, an image is formed on the other surface by the above-described image forming process.

On the recording material carrying sheet 5f on the transfer drum 5a, the photosensitive drum 1, the developing device and the cleaning device 6 are provided.
Contamination is caused by toner particles adhering to the recording material when the recording material scatters or jams (paper jam), and oil on the recording material sometimes adheres during double-sided image formation. And a backup brush 15 or an oil removing roller 16 facing the fur brush 14 via the recording material carrying sheet 5f and a backup brush 17 facing the roller 16 via the recording material carrying sheet 5f.
After being cleaned by the action of, the image forming process is performed again. Such cleaning is performed at the time of pre-rotation and at the time of post-rotation, and at any time when a jam (paper jam) occurs.

Further, in this example, the transfer drum eccentric cam 25 is operated and the cam follower 5i integrated with the transfer drum 5f is operated to set the gap between the recording material carrying sheet 5a and the photosensitive drum 1 at a predetermined timing. The configuration is such that a predetermined interval can be set. For example, during standby or when the power is off, the gap between the transfer drum and the photosensitive drum can be separated so that the rotation of the photosensitive drum can be independent of the rotation of the photosensitive drum.

In this series of image forming operations, the developing device and the developer concentration control device operate as follows.

That is, the developed image read by the CCD undergoes various processes to form a latent image on the photosensitive drum, and when the electrostatic latent image reaches the developing position, AC / DC superimposition is performed by a developing bias power source (not shown). The developed developing bias is applied to the developing sleeve 41, and the developing sleeve 41 is rotated by a developing sleeve driving device (not shown), and the developing pressure cam 24
The electrostatic latent image is visualized by being pressurized by. At the same time A /
The density level of the D-converted input image signal is counted by a video counter (not shown) for each pixel,
The toner supply amount is determined by the integrated value from the CPU (not shown), and the toner is supplied to the developing device.

When the control for detecting the fluctuation of the image density by the output voltage of the sensor is also used, a predetermined patch latent image for detecting the developer density is formed, and the developing bias power source 9 applies an electric field to the developing sleeve 41. The applied voltage is applied to rotate the developing sleeve 41 by driving the developing sleeve (not shown) to visualize a predetermined patch latent image (P1), and the sensor 13 reads the image density signal.

At the time of normal image formation, a patch image is formed in a non-image area and the developer density is controlled so as to be always constant so that an appropriate image is obtained. The control on the patch image has been performed once every several tens of sheets. As other control means, there are a method using a means for detecting a change in magnetic permeability of the developer and a method of reading a change in the amount of reflected light of the toner and the carrier with an optical sensor.

[0015]

However, with the downsizing and cost reduction of the apparatus, it is necessary to perform control of these methods by a single control rather than using a plurality of them and with high precision. Therefore, the cost of the optical sensor and the magnetic permeability sensor is relatively high. Although the video count for integrating the image data is lower in cost than others, it has not been able to suppress the fluctuation of the image density due to the small absolute amount of the developer, which is an adverse effect of downsizing.

The present invention has been made in view of the above problems, and an object thereof is to provide an image forming apparatus capable of stabilizing the image density by suppressing the ripple of the developer density. is there.

[0017]

In order to achieve the above object, the present invention uses a two-component developer comprising a toner and a carrier, and carries a developer carrying member carrying the developer and a developer carrying body. A plurality of developing devices having a stirring member for stirring,
An image data counter that counts and integrates the image data of the image developed by the developing device, and a developer detection unit that integrates the image data to detect toner consumption information in the developer, and a toner corresponding to the signal In an image forming apparatus that replenishes toner based on a replenishment signal, the developer circulation path of the developing device is divided into a plurality of blocks, and the image data of each block is integrated to detect the toner variation state of the developer, and the variation is detected. It is characterized in that the toner is replenished according to the amount.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1> FIG. 1 is a development view of the developing device. In this embodiment, the inside of the developing device is divided into 10 blocks. The developer in the developing unit circulates in each block while being stirred in the arrow direction.

Explaining starting from block j, the developer circulates in the order of j → i → h → ... → b → a and j. In a to e, the developing sleeve 41 and the stirring screw 42 cause the latent image on the photosensitive drum. The image is circulated in the direction of the arrow while developing (consuming toner), receives toner supply corresponding to the toner consumption at the toner supply port 44, supplements the developer concentration, and repeats circulation while stirring.

In the present embodiment, the developing sleeve is divided into five blocks in FIG. FIG. 2 shows an example of a histogram of image data of a copy image corresponding to the block.

Normally, when a copy image is formed, toner is consumed from the developer on the sleeve as shown in the histogram of FIG. Conventionally, the entire image data is integrated and toner is supplied according to the integrated signal. The present invention divides the developing sleeve into a plurality of blocks, integrates the image data of each block, and integrates the history of the developer reaching the block to grasp the usage status of the developer, The toner is replenished according to the value.

If a plurality of image data of the histogram shown in FIG. 2 are continuously copied, the control is performed as shown in FIG.

In FIG. 3, the developing sleeve is divided into blocks, the developers in the stationary blocks are A to J, and the integrated values of the image data corresponding to blocks a to e on the sleeve are a0 to a0, respectively. When e0 is set, the developer A develops the image data a0 at the time of copying the first sheet, and reaches the block j having the toner supply port 44. Developer A
Since the toner consumption corresponding to a0 has been consumed, the toner is replenished correspondingly.

The developer B is b0 for the first sheet and a for the second sheet.
The image data of 0 is developed and reaches the supply port position j. Since the developer B receives the toner consumption corresponding to a0 + b0 when being conveyed in the blocks a and b, the toner replenishment port 4
4 is reached, toner supply corresponding to that is performed.

Toner replenishment corresponding to the integrated value of the image data shown in FIG. 3 is performed by the developer C on the third sheet and the developer D on the fourth sheet. After the fifth sheet, when the developer is transported,
The whole area of the developing sleeve 41, that is, the entire image area is passed while being developed, and this is performed when the toner supply amount corresponding to the integrated value of all the image data reaches the toner supply port 44.

The division of blocks of the developer can be set so as to move each block for each copy by determining the circulation speed of the developer. As a result, by accumulating the integrated value of the image data of each block along with the movement of the developer, it is possible to accurately grasp the moving toner consumption amount of the developer that has moved for each copy, and the required toner amount is required. Since it can be replenished to the location, the ripple of the developer density in the developing device can be minimized, and the image density can be stabilized even with a small developer capacity.

<Second Embodiment> Next, a second embodiment of the present invention will be described.

In the first embodiment, the developer is divided into blocks in the circumferential direction to suppress the developer concentration fluctuation by simple control so that a stable output image can be obtained. The accuracy is further improved.

FIG. 4 is a diagram showing an image data integrating method in this embodiment. As described in the first embodiment, the developer circulates in the developing device and the developing sleeve 4
The electrostatic latent image is visualized through 1.

The developer in the developing unit divided into 10 blocks circulates in each block while being stirred in the direction of the arrow. Explaining starting from block j, the developer is j → i →
h → ... → b → a and j, and in a to e, the developing sleeve 41 and the stirring screw 42 circulate in the direction of the arrow while developing (toner consumption) the latent image on the photosensitive drum, Replenishment of toner according to the toner consumption is received from the toner supply port 44, and the circulation is repeated while supplementing the developer concentration and stirring. FIG. 4 shows an example vistogram of image data of a copy image corresponding to each block.

Normally, when a copy image is formed, toner is consumed from the developer on the sleeve as shown in the histogram of FIG. Taking the developer on the boundary between the blocks d and e as an example, the developer moves to the boundary between the blocks c and d while forming an image along with the copy operation. That is, as shown in FIG. 4, in order to bring the developer closer to the actual image consumption and improve the accuracy, the image data is integrated in the arrow γ direction which is a combined vector direction of the image advancing direction α and the developer conveying direction β. As a result, it is possible to accurately grasp the toner consumption of the developer.

As shown in FIG. 5, the toner consumption of the developer can be grasped more accurately by increasing the number of blocks rather than the distance of the developer moving per copy. Regarding the method of dividing the number of blocks, if a plurality of blocks are provided for the moving distance per copy, the toner replenishment timing can be synchronized with the developer operating during the copy job. It is possible to supply various toners. That is, as shown in FIG.
The replenishable time per sheet is the developer moving distance, and as shown in FIG. 6, by dividing the block into an integral multiple, the error can be reduced and the fluctuation of the developer concentration can be suppressed. Thus, it is possible to obtain a compact image forming apparatus capable of obtaining a stable output image.

[0034]

As is apparent from the above description, according to the present invention, a two-component developer composed of a toner and a carrier is used, and a developer carrying member carrying the developer and the developer are conveyed. A plurality of developing devices having an agitating stirring member, an image data counter that counts and integrates image data of images developed by the developing devices, and a developing device that integrates the image data to detect toner consumption information in the developer. In an image forming apparatus that has a developer detection unit and supplies toner based on a toner supply signal corresponding to the signal, dividing the developer circulation path of the developing device into a plurality of blocks and integrating the image data of each block. The toner fluctuation status of the developer is detected by the toner supply, and the toner is replenished according to the fluctuation amount, so that the ripple of the developer density can be suppressed and the image density can be stabilized. The effect of wear can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a developing device configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a histogram showing image data integration according to the first embodiment of the present invention.

FIG. 3 is a diagram showing an image data integrating method according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an image data integrating method according to a second embodiment of the present invention.

FIG. 5 is a diagram showing another image data integration method according to the second embodiment of the present invention.

FIG. 6 is a diagram showing toner supply and developer movement distance according to the embodiment of the present invention.

FIG. 7 is a sectional view of a conventional image forming apparatus.

[Explanation of symbols]

41 Development sleeve (developer carrier) 42 Stirring screw (stirring member) 44 Toner supply port

Claims (5)

[Claims] 1. A two-component developer comprising a toner and a carrier, a developer carrying member carrying the developer, and a plurality of developing devices having a stirring member for carrying and stirring the developer,
An image data counter that counts and integrates the image data of the image developed by the developing device, and a developer detection unit that integrates the image data to detect toner consumption information in the developer, and a toner corresponding to the signal In an image forming apparatus that replenishes toner based on a replenishment signal, the developer circulation path of the developing device is divided into a plurality of blocks, and the image data of each block is integrated to detect the toner variation state of the developer, and the variation is detected. An image forming apparatus characterized in that toner is replenished according to the amount. 2. The block of the developing device moves together with the circulation of the developer for each copy, circulates in the circulation path in the developing device, and when reaching the toner replenishment port, the amount of toner corresponding to the integrated signal is reached. The image forming apparatus according to claim 1, further comprising: 3. The image forming apparatus according to claim 1, wherein the block area of the developing device is equal to the moving distance of the developer per copy. 4. The image forming apparatus according to claim 1, wherein the block area of the developing device is an integral multiple of a moving distance of one copy of the developer. 5. The image data is slid and integrated in accordance with the developer circulation speed of the developing device, and when the developer reaches the vicinity of the toner replenishment port, toner is replenished by a toner replenishment signal according to the integrated signal. The image forming apparatus according to claim 1, wherein: