JPH08286491A - Developing device and process cartridge - Google Patents

Abstract

PURPOSE: To always stably obtain an excellent image, by dividing a detection member into plural parts in the lengthwise direction, providing a transporting member capable of moving toner to all divided locations in the lengthwise direction, and correcting an unevenness in distribution of toner that occurs at the time of continuing passing small size papers. CONSTITUTION: In the vicinity of a developing sleeve 3, two pieces of detection members 2 are placed in parallel therewith. The respective detection members 2 are independently connected to a detection circuit, and detect the change of capacitance by the toner 6 namely, the toner quantity, so as to enable them to detect the state, even if the partiality occurs in the toner 6 by successively using transfer materials of much narrower than the usable maximum size transfer material. Moreover, in the adequate vicinity of the developing sleeve 3 and the detection member 2, a screw 1 for transporting is disposed in the axial direction of the developing sleeve 3 in rotatable forward and backward by a motor. Then, the device is composed so that the toner 6 is transported to the toner lacking region by rotating the screw 1 when the signal indicating the toner lacking is detected from one side of the detection members 2.

Description

Detailed Description of the Invention

[0001]

[Object of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrostatic copying machine and a printer, and more particularly to a developing apparatus therefor.

[0002]

BACKGROUND OF THE INVENTION After uniformly charging a photosensitive layer on the surface of an image carrier, an electrostatic latent image is formed on the charged surface, and then toner is applied to the latent image to form a toner image. An image forming apparatus that transfers the toner image onto a transfer material such as paper and then fixes and fixes the transferred toner image onto the transfer material is well known.

FIG. 8 is a schematic side view schematically showing a typical example of such an image forming apparatus. To briefly describe this, the surface photosensitive layer of the rotating cylindrical image carrier 10 having an axis extending in the direction perpendicular to the paper surface is uniformly charged by the primary charging means 11, and the exposing surface 11 is exposed on this charged surface. An image signal is projected from this to form an electrostatic latent image.

When the latent image reaches the developing portion where the developing device 13 is opposed by the rotation of the image carrier 10, the toner 6 in the hopper 7 of the developing device causes the developer layer thickness regulating member 4 to move.
The toner image is formed by being applied to the latent image on the image carrier through the developing sleeve 3 having the toner layer regulated to have a predetermined thickness.

When the toner image reaches the transfer portion where the image carrier 10 and the transfer means 16 are arranged to face each other, the transfer material 14 stored in the cassette or the like by this time is fed by the paper feed roller 1.
The sheet is discharged and conveyed by 5 and supplied to the transfer portion. At the same time, a transfer bias is applied to the transfer means, and the toner image on the image carrier is transferred to the transfer material.

Then, the transfer material carrying the toner image reaches the fixing device 17, the toner image is fixed and fixed on the transfer material, and is discharged out of the apparatus. Further, a part of the toner not transferred to the transfer material at the time of transfer is removed by the cleaning blade provided in the cleaning device 20, and the image carrier is ready for the next image forming step.

In such an image forming apparatus, it is necessary to confirm in the developing device that the toner amount necessary for image formation is present in the hopper. A detection means is usually provided.

FIG. 6 is a side sectional view of a developing device for detecting the remaining amount of the capacity detection type. The toner 6 in the hopper 7 is shown in FIG.
However, it is assumed that the toner is supplied from the developing sleeve 3 having the toner of the layer thickness regulated by the developer regulating member 4 to the image carrier (not shown). A stirring rod 5 is provided in the hopper 7.
Is rotatably provided, and by this operation, the toner in the hopper is successively conveyed toward the developing sleeve.

In the vicinity of the developing sleeve 3, a rod-shaped conductive detecting member 2 is arranged parallel to the developing sleeve 3. Development sleeve 3
Since the electrostatic capacity between the detecting member 2 and the detecting member 2 changes depending on the amount of toner existing in this portion, the remaining toner amount can be detected by detecting the change in the electrostatic capacity.

Since such a toner remaining amount detecting means has a simple structure, is small in size, does not occupy a space, and is advantageous in terms of cost, in particular, the image carrier, the primary charging means arranged in the vicinity thereof, and the developing device It is often used in a cartridge-type image forming apparatus in which some of the cleaners and the like are integrated into a cartridge and are detachably mounted in the main body of the image forming apparatus.

At the same time, the toner in the developing device is not always consumed uniformly when viewed in the longitudinal direction of the developing sleeve. For example, a small transfer material is often used and one of the toners in the longitudinal direction of the developing sleeve is used. If only the deviated portion is used continuously, as shown in "FIG. 7", there may occur a situation in which only the toner in the portion close to the use side is consumed and the toner in that portion runs short.

The above-mentioned stirring rod is expected to be able to evenly distribute the toner in the longitudinal direction in order to cope with such a situation, but a large transfer material such as A2 or A3 size can be used. In the case of such a device, the stirring function of the stirring rod cannot follow and the above situation cannot be avoided.

If the uneven distribution of the toner as shown in FIG. 7 occurs, the change in the electrostatic capacity between the developing sleeve 3 and the detection member 2 does not occur, and the warning is not issued. However, there is a problem in that there is a toner shortage, and image defects such as white spots in the image and uneven density occur.

When such a situation occurs, it is necessary for the operator of the apparatus to take out the developing device and give vibration to it to make the distribution of the toner in the longitudinal direction uniform, but such means is troublesome. Not only that, there is a possibility that the leaked toner may contaminate the fingers and the vicinity thereof.

The present invention has been made in view of the above situation, and even if the uneven distribution of the toner as described above occurs in the developing device, the uneven distribution of the toner can be detected without fail. It is an object of the present invention to provide an image forming apparatus capable of constantly correcting and correcting to obtain a good image.

[0016]

Configuration of the Invention

In order to achieve the above object, according to the present invention, a conductive detecting member is arranged in parallel with a developing sleeve in a developing device, and an AC bias is applied to the developing sleeve. At this time, in the developing device that detects the amount of residual toner in the developing device by the change in the voltage induced in the detection member, a plurality of the detection members are arranged in the longitudinal direction, and the toner is discharged in the vicinity of the detection member. An image forming apparatus including a toner moving unit that can move in any of the longitudinal directions and a driving unit that moves the toner moving unit to a side where no toner exists when the uneven distribution of the toner in the developing device is detected. Developing device (1), or
In the above-mentioned (1), there is provided an image forming apparatus in which a plurality of toner moving means are arranged in the longitudinal direction, and each moving means can independently move the toner in the developing device in any of the longitudinal directions. The developing device (2) or the image carrier and at least the developing device are integrally formed into a process cartridge detachably mountable to the main body of the image forming apparatus, and the developing device is one of the above (1) or (2). The process cartridge (3) of the image forming apparatus, which is a developing device.

With this structure, uneven distribution of toner in the developing device can be effectively prevented, and a high-quality image can always be formed stably.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS "FIG. 1" is a side sectional view of a developing device according to the present invention, and "FIG. 2" is a plan view of the same. In FIG. 1, parts corresponding to those of the developing device shown in FIGS. 6 to 8 are designated by the same reference numerals, and description thereof will be omitted.

As is apparent from FIG. 2, the developing sleeve 3
In the vicinity, parallel to this, two detection members 2 are shown in the figure.
Is provided. Each detection member is individually connected to a detection circuit (not shown), and the change in electrostatic capacity due to toner, and accordingly the amount of toner present in that portion, is detected individually. Even if the toner is biased as described above by using a transfer material that is much narrower than the maximum usable transfer material, the state can be detected.

As shown in FIG. 1, the developing sleeve 3,
At a suitable place near the detecting member 2, the conveying screw 1 is arranged in the axial direction of the developing sleeve so as to be capable of forward and reverse rotation by a motor (not shown). Therefore, when the toner shortage signal is output from one of the detection members, the screw 1 is rotated in a predetermined direction in response to this, and the toner can be conveyed to the toner shortage portion to eliminate this.

FIG. 3 is a flow chart showing the operation of the developing device as described above, and FIG. 3 shows an example in which the remaining amount is detected after the printing operation.

When the power is turned on, the image forming apparatus goes into a standby state. Printing is performed by the print start signal, and when this is finished, the remaining toner amount detection is started. The remaining amount is detected by applying an AC voltage to the developing sleeve 3 and comparing whether the voltage induced in the conductive detecting member 2 is a preset value or less.

It is assumed that two detecting members 2 are arranged as described above, and when both detecting members are judged to have toner, the standby state is changed.

When both the detection members determine that there is no toner, a toner-out warning is issued. At this time, in the case shown in the drawing, the standby state is restored, but it is of course possible to stop the apparatus until toner is replenished.

When either one of the detecting members detects the absence of toner, the conveying screw 1 is operated so as to convey the toner in that direction, and the remaining amount is detected. As a result, the standby state is returned to when both toners appear to have toner. If no toner is not eliminated as a result of the remaining amount detection, the above-described toner conveyance may be repeated.

As described above, by using this apparatus, even if the toner in the developing device is consumed in a biased manner, the toner is conveyed in the consumed direction, and the toner can always be uniformly distributed in the longitudinal direction of the developing portion. Therefore, it is possible to prevent image deterioration such as white spots in the image, improve the usage efficiency of the toner, and it is not necessary for the operator to directly subject the developing device to processing such as vibration, so that contamination by the toner is also preferably avoided it can.

The means for conveying the toner in the developing device is not limited to the above-mentioned conveying screw, and it is needless to say that any suitable means such as a caterpillar-like conveying member and a vibrating conveying member can be used. .

FIG. 4 shows another embodiment of the present invention, and is a plan view showing the relationship between the developing sleeve of the developing device and the detecting member. The same parts as those of the apparatus of the above-described embodiment are designated by the same reference numerals, and the description thereof will be omitted unless necessary.

In this apparatus, the detection member 2 is divided into three pieces in the longitudinal direction, and the presence or absence of toner is individually detected. Further, it is assumed that the transport screw is also divided into two screws 1a and 1B on the same axis so that the screws can individually rotate forward and backward.

As in the case of the apparatus of the above-described embodiment, it is easily understood that when the toner is biased to one side in the developing device, the bias of the toner can be eliminated in the same manner as the apparatus of the embodiment. It will be possible. In this case, as shown in (a) and (b) of FIG.
The intended purpose can be achieved by rotating 1b in the same direction.

Although the toner is biased toward one side of the image area as described above, it tends to occur when a small-sized transfer material is placed on the side where the toner is consumed on the basis of one side. It is well known that an original may be placed in the central portion of the image area by a copying machine or the like to form an image with the central reference.

As described above, when images are continuously formed on an extremely narrow sheet such as an envelope with reference to the center, as shown in FIG.
As shown in c, only the toner in the central portion of the developing device is consumed, and image defects such as white spots may occur in this portion.

Even in such a case, in the illustrated apparatus, since the detection member 2 is divided into three parts, it is possible to accurately detect the lack of toner in the relevant portion. Further, as described above, the conveying screw is also divided into two as shown by reference numerals 1a and 1b, and can be individually rotated forward and backward, so that each screw is rotated in the opposite direction and is indicated by an arrow in FIG. By moving the toner existing on both sides to the central portion as described above, the toner distribution can be made uniform, and the occurrence of the image defect as described above can be prevented.

FIG. 5 shows the present invention in which an image carrier and at least one image forming member arranged around the image carrier are integrally formed into a cartridge, which is detachably mounted on the main body of the image forming apparatus. 2 is an example applied to a process cartridge that does.

In the illustrated cartridge, the image carrier 10, the primary charging means 11, the developing device 13, and the cleaning device 18 are integrally formed. The developing device 13 is provided with a developing sleeve 3, a detecting member 2 which is divided into a plurality of parts, and a screw 1 for uniformizing the eccentric toner.
The operation is similar to that of each of the above-described embodiments.

[0036]

As described above, according to the present invention,
In the developing device of the image forming apparatus, in which a conductive detecting member is disposed in the vicinity of the developing sleeve, and the remaining toner amount is detected by a change in voltage induced in the detecting member due to a change in the toner amount, By dividing the detection member into a plurality of parts in the longitudinal direction and providing a conveying member capable of moving the toner in any of the longitudinal directions,
It is possible to effectively eliminate the uneven distribution of toner in the developing device, which is caused by continuing the image formation at the uneven portion in the image area.
It is possible to prevent the occurrence of image defects such as white spots in the image and uneven density.

Further, by providing a plurality of conveying members that can move the toner so that they can be individually operated, even if uneven distribution of the toner occurs in any part of the image area, the uneven distribution is eliminated and the image is corrected. It is possible to secure a uniform distribution of toner in the area.

Furthermore, by making the developing device of the process cartridge in which the image bearing member and at least the developing device are integrated into one cartridge, the component parts can be easily replaced and maintainability is improved. Can be improved.

[Brief description of drawings]

FIG. 1 is a side sectional view of a developing device showing an embodiment of the present invention.

FIG. 2 Same as above

FIG. 3 is a flowchart showing the same operation.

FIG. 4A is a plan view showing an operation mode of another embodiment.

FIG. 4 (b) is a plan view showing another mode of the above operation.

FIG. 4 (c) is a plan view showing still another mode of the same operation.

FIG. 5 is a side sectional view showing still another embodiment of the present invention.

FIG. 6 is a side sectional view of a known developing device.

FIG. 7 Same as above

FIG. 8 is a schematic side view showing the configuration of a known image forming apparatus.

[Explanation of symbols]

 1 Carrying Screw 2 Conductivity Detection Member 3 Developing Sleeve 5 Stirring Bar 6 Toner

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[Procedure amendment]

[Submission date] April 4, 1996

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a side sectional view of a developing device showing an embodiment of the present invention.

FIG. 2 Same as above

FIG. 3 is a flowchart showing the same operation.

FIG. 4 is a plan view showing an operation mode of another embodiment.

FIG. 5 is a side sectional view showing still another embodiment of the present invention.

FIG. 6 is a side sectional view of a known developing device.

FIG. 7 Same as above

FIG. 8 is a schematic side view showing the configuration of a known image forming apparatus.

[Explanation of Codes] 1 Conveying screw 2 Conductivity detecting member 3 Developing sleeve 5 Stirring bar 6 Toner

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Kazumi Yamauchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Hideki Matsumoto 3-30 Shimomaruko, Ota-ku, Tokyo No. 2 Canon Inc.

Claims (3)

[Claims] 1. A conductive detecting member is disposed in parallel with a developing sleeve in a developing device, and when an AC bias is applied to the developing sleeve, the voltage remains in the developing device due to a change in voltage induced in the detecting member. In a developing device for detecting the amount of toner, a plurality of the detecting members are arranged in the longitudinal direction, and a toner moving means capable of moving the toner in any of the longitudinal directions in the vicinity of the detecting member, and a developing device. A developing device for an image forming apparatus, comprising a driving means for moving the toner moving means to a side where no toner exists when the uneven distribution of the toner inside is detected. 2. A method according to claim 1, wherein a plurality of toner moving means are provided in the longitudinal direction, and each moving means can independently move the toner in the developing device in any of the longitudinal directions. Developing device for image forming apparatus. 3. An image carrier and at least a developing device are integrally formed into a process cartridge detachably mountable to the main body of the image forming apparatus, and the developing device is "claim 1" or "claim 2".
The process cartridge of the image forming apparatus, which is any one of the developing devices.