JP2003156936A - Developing device, processing cartridge and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent maldistribution of toner in the longitudinal direction of a toner container. SOLUTION: The maldistribution of toner is detected by having a multiple number of serial residue detection means (FA and PA) installed in the longitudinal direction of the toner container and agitating is intensified according to necessity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic type or electrostatic recording type image forming apparatus such as a copying machine or a laser printer, and a process cartridge.

[0002]

2. Description of the Related Art An image forming apparatus such as a printer forms a latent image by selectively exposing a photosensitive drum, which is an image carrier, which is uniformly charged, to form a latent image. To visualize the image, and transfer the toner image to a recording medium to record an image. In such an apparatus, the toner must be replenished every time the toner runs out, but this toner replenishment work is not only troublesome, but it may be contaminated. Further, maintenance of each member can be performed only by a specialized service person, and this is often inconvenient for the user.

Therefore, by using a process cartridge in which the photosensitive drum, the developing device, the cleaning member, and the like are integrated into a unitary structure, when the user runs out of the toner by mounting the cartridge in the main body of the device or the photosensitive drum. It has been put into practical use that parts can be replaced when they reach the end of their service life and are easily maintained.

In recent years, in image forming apparatuses, the capacity of process cartridges has been increasing as the number of prints has increased. In such a cartridge, it is desirable to have a means for sequentially notifying the remaining amount of the cartridge so that the user can easily predict when to replace the cartridge.

As a means for sequentially detecting the remaining amount of toner,
A pair of electrodes are arranged at a predetermined interval with the toner contained therebetween,
There is a method of detecting the remaining toner amount by measuring the electrostatic capacitance between the electrodes. The electrostatic capacitance between the electrodes is large when the remaining amount of toner is large, and becomes smaller as the amount of toner decreases.

Further, as a means for sequentially detecting the remaining amount of toner, a detection member in which a pair of electrodes are arranged at a predetermined interval is arranged in the toner accommodating portion, and the capacitance between the electrodes of the detection member is measured. By doing so, there is a method of detecting the remaining amount of toner in the toner containing portion. The capacitance of the detection member is
When the amount of remaining toner in the toner container is large, the contact area between the detection member and the toner is large, so the electrostatic capacity is also large, and as the remaining amount of toner decreases, the contact area with the toner decreases and the electrostatic capacity also decreases. .

The stirring member is a sheet made of polyethylene terephthalate, polyphenylene sulfide or the like fixed to a rotary shaft extending in the longitudinal direction inside the toner container, and is usually driven and rotated in synchronization with the development to form a toner container. The toner inside is stirred and supplied to the developing device.

[0008]

However, with the recent increase in the capacity of process cartridges, uneven distribution of toner in the longitudinal direction of the container cannot be ignored. That is, when the process cartridge is mounted in the main body, it is tilted in the longitudinal direction, or a large amount of small size paper is printed by the main body whose paper feeding reference position is one side reference in the longitudinal direction. Toner may be unevenly distributed in the longitudinal direction inside the container by printing a large amount of an uneven image. If you continue printing with toner unevenly distributed, only one side will be out of toner.However, conventional toner remaining amount detection means detected only the remaining amount of toner in the entire longitudinal direction. It was dead.

In order to eliminate uneven distribution of the toner in the container, the stirring force such as stirring speed may be increased.
In the case of a large-capacity cartridge, if strong stirring is always performed, deterioration of the toner is promoted and problems such as low density occur.

Therefore, an object of the invention of the present application is to detect uneven distribution of toner in the longitudinal direction in the toner container and enhance agitation as necessary, thereby avoiding adverse effects such as low density.
To make the toner supply to the developing process uniform.

[0011]

To achieve the above object, the invention of the present application is directed to a developing means for developing an electrostatic latent image on an electrostatic latent image carrier, and a developer provided for the developing means. A developer accommodating container for accommodating the developer, a developer remaining amount detecting unit disposed in or near the developer accommodating container for detecting the amount of developer in the developer accommodating container, and a developer in the developer accommodating container. In a developing device having a stirring means for stirring, at least two developer remaining amount detecting means are arranged in the longitudinal direction, and when it is determined that the developer is unevenly distributed in the longitudinal direction, the stirring means is provided. The developing device is characterized by increasing the stirring power of.

With such a structure, it is possible to detect uneven distribution of toner in the longitudinal direction in the toner container and enhance agitation as necessary, and to carry out the development process without adverse effects such as low density. The toner supply can be made uniform.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is a schematic configuration diagram of the image forming apparatus used in the present embodiment. The scanner unit 1 including a laser, a polygon mirror and a lens system scans and outputs laser light modulated according to an image signal. The laser light is reflected by the folding mirror 11 and irradiated on the photosensitive drum 2 which is an image carrier. Then, the photosensitive drum 2 is uniformly charged by the primary charger 3 composed of a charging roller,
An electrostatic latent image is formed on the surface by irradiation with laser light. This electrostatic latent image is developed as a toner image by the toner 41 in the developing device 4 and visualized. on the other hand,
The recording material 7 stored in the cassette 71 is the paper feed roller 7
The toner is supplied to the registration roller 73 in synchronism with the formation of the latent image on the photosensitive drum 2. And this recording material 7
Is conveyed to a transfer charger 6 composed of a transfer roller in synchronization with the tip of the latent image formed on the photosensitive drum 2 by the registration roller 73, and the toner image is transferred to the recording material 7 by the transfer charger 6. To be done. The recording material 7 to which the toner image has been transferred has the toner image permanently fixed by the fixing device 8, and is finally discharged to the outside of the apparatus. The photosensitive drum 2
The toner remaining on the top is removed by a cleaning device 5 using a cleaning blade made of an elastic blade.

The details of the present invention will be specifically described below with reference to FIG.

The remaining toner amount is detected by measuring the electrostatic capacities C and C'of the detecting members 9 and 9'arranged at two positions in the toner containing portion 42 in the longitudinal direction. Since the toner has a higher dielectric constant than air, the electrostatic capacitance of the detection member increases in proportion to the contact area with the toner when the toner 41 contacts the surface of the detection member. The toner remaining amount in the entire container can be calculated by averaging the electrostatic capacities of the two detection members, and the toner bias in the storage unit can be calculated by taking the difference between the electrostatic capacities of the two detection members.

The detection members 9 and 9'are not particularly limited in terms of electrode pattern, manufacturing method, etc., but in the present embodiment, two electrodes are formed in the manner of forming a wiring pattern on a printed circuit board as shown in FIG. 91a and 91b are arranged on the surface of the substrate 92 at a predetermined interval, and a protective layer 93 made of PET, Teflon (registered trademark) resin or the like is provided for preventing leakage.
What was coated was used. Since the electrostatic capacity of the detection member is proportional to the area on the surface of the detection member with which the toner is in contact, the cross-sectional shape of the toner storage portion and the shape of the detection member can be obtained by performing conversion based on an appropriate correlation curve. The remaining toner amount can be sequentially calculated regardless of the above.

The stirring member 43 is a sheet made of polyethylene terephthalate, polyphenylene sulfide, or the like fixed to a rotary shaft extending in the longitudinal direction inside the toner container, and is usually driven and rotated in synchronization with the development and inside the toner container. The toner is stirred and supplied to the developing device.

When toner is unevenly distributed in the longitudinal direction of the container such as printing a large number of images whose printing rate is biased in the longitudinal direction, stirring is enhanced, that is, stirring speed is increased, stirring time is extended, and development is stopped. It is possible to eliminate uneven distribution of toner by, for example, performing only a stirring operation.

Actually, printing was carried out by using the developing device having the following constitution, and the effect was confirmed. (1) As a conventional example, stirring is always performed at a predetermined speed in synchronization with the developing sleeve. (2) As a reference example, the stirring speed is constantly set to 150% and stirring is performed in synchronization with the developing sleeve. (3) In the present embodiment, the stirring speed is 150% only when the difference between the left and right amounts of the remaining toner is 10% or more of the total remaining amount.
Other than that, stirring is carried out at the normal stirring speed in synchronization with the developing sleeve.

As a result of continuous printing on the small size paper using the main body of which the reference position for paper feeding is the one side reference in the longitudinal direction, the developing device having the above-mentioned structure produced a blank on one side at about 12 k sheets. In the case of (2), a low density occurred around 15 k.
In the case of (3), white spots were formed on the entire surface after printing about 20 k, and the remaining toner amount was 40 g, which was almost uniformly used up. Moreover, there was no adverse effect such as low density.

As described above, the uneven distribution of toner in the longitudinal direction inside the toner container is detected, and if necessary, the agitation is strengthened, so that the toner can be uniformly supplied to the developing process without adverse effects such as low density. I was able to

(Second Embodiment) A feature of the present embodiment is that a detection member for detecting the remaining amount of toner includes a pair of electrode plates arranged above and below with a toner accommodating portion interposed therebetween in a longitudinal direction 2. It has been set up in several places. Further, a stirring member for stirring the toner in the storage portion mainly in the longitudinal direction is provided.

In the toner remaining amount detecting means having the above structure, the electrostatic capacitance between the pair of electrode plates arranged above and below the toner containing portion is increased in proportion to the amount of toner in the toner containing portion between the electrode plates. To do. Since the electrode plate may be a general conductive plate, the structure is simple and the cost is low. Further, by providing a stirring member that stirs in the longitudinal direction inside the accommodating portion, it is possible to more efficiently make the longitudinal direction uniform, so that deterioration of the toner can be further reduced.

The toner residual detecting means and the stirring means according to the present invention will be described with reference to FIG.

To detect the remaining amount of toner, a pair of electrode plates 9 are arranged one above the other with a toner accommodating portion 42 on one side in the longitudinal direction interposed therebetween.
The measurement is performed by measuring the electrostatic capacitance C94 of the electrodes 4a and 94b and the electrostatic capacitance C95 of the pair of electrode plates 95a and 95b that are vertically arranged with the toner containing portion 42 on the other side in the longitudinal direction sandwiched therebetween. Since toner has a higher dielectric constant than air, the presence of toner between the electrode plates increases the capacitance between the electrode plates in proportion to the amount of toner. The total amount of toner remaining in the container is C94 between the two electrode plates.
And C95 can be summed, and the deviation of the toner in the accommodating portion can be calculated by taking the difference between the electrostatic capacitances C94 and C95 between the two sets of electrode plates.

The electrodes are not particularly limited in shape and material as long as they are electrically conductive. However, by forming at least one of the pair of electrodes in a plate shape, the detection range can be widened and high-accuracy sequential measurement can be performed. It is possible to carry out a residual inspection.

As the stirring means, two stirring means are provided in this embodiment. The first stirring unit 43 is the same as that of the first embodiment, and stirs the toner in the toner container and supplies the toner to the developing unit. The second stirring means 44 mainly stirs the toner in the toner storage portion in the longitudinal direction. As the second stirring means, a ladder-shaped stirring member made of a resin such as ABS or polystyrene is provided on the bottom surface of the toner container, and is reciprocated in the longitudinal direction by a driving means (not shown).

The uneven distribution of toner is efficiently eliminated by operating the second stirring only when uneven distribution of toner occurs in the longitudinal direction inside the container, such as when printing a large number of images with uneven printing ratio in the longitudinal direction. It is possible.

Actually, as in the first embodiment, the print test was conducted under a high temperature and high humidity environment in which the toner is apt to be unevenly distributed under more severe conditions. In the configuration of the first embodiment, there is a case where the density is slightly reduced from about 18 k at a level that does not cause any problem in practical use, whereas in the configuration of the present embodiment, about 20 k is printed until a white spot appears. The density never decreased.

As described above, the agitating member for agitating the toner in the accommodating portion in the longitudinal direction is provided, the uneven distribution of the toner in the longitudinal direction in the toner accommodating container is detected, and the agitation in the longitudinal direction is performed as necessary. As a result, the toner deterioration can be further reduced, and even in a high temperature and high humidity environment, there is no adverse effect such as low density, and the toner can be uniformly supplied to the developing process.

(Third Embodiment) A feature of this embodiment is that the charging member according to the present invention is applied to a process cartridge in which a photosensitive drum, a developing device, and a cleaning device are integrated into a unit. Where it is.
When the process cartridge has reached the end of its life due to lack of toner, drum life, etc., the user can replace the process cartridge by himself or herself, and maintenance-free operation can be realized without causing stains due to toner replenishment work.

As the capacity of the process cartridge increases, the problems of uneven distribution of toner inside the container and toner deterioration due to agitation cannot be ignored. Toner remaining amount detecting means according to the present invention in the process cartridge,
By applying the toner stirring means, it is possible to make the toner supply to the developing process uniform without any adverse effect such as low density due to toner deterioration.

The process cartridge used in this embodiment will be described below with reference to FIG. The process cartridge 10 includes a photosensitive drum 2, a charging roller 3, a developing device 4, and a cleaning device 5 as a unit, and these components are assembled in the cartridge in a predetermined mutual arrangement relationship. The cartridge is designed so that it can be inserted into and installed in a predetermined portion in the main body of the image forming apparatus in a predetermined manner, and conversely can be removed from the main body of the apparatus.

It is obvious that the same effect can be obtained by using the toner remaining amount detecting means and the toner stirring means in the container similar to those in the first or second embodiment. is there.

[0036]

As described above, according to the invention of the present application, the developing means for developing the electrostatic latent image on the electrostatic latent image carrier, and the developer used for the developing means are accommodated. And a developer remaining amount detecting means disposed in or near the developer container for detecting the amount of the developer in the developer container, and stirring the developer in the developer container. In a developing device having a stirring unit, at least two developer remaining amount detecting units are arranged in the longitudinal direction, and when it is determined that the developer is unevenly distributed in the longitudinal direction, the stirring of the stirring unit is performed. With a developing device that is characterized by increasing the force, it is possible to detect uneven distribution of toner in the longitudinal direction inside the toner container and enhance agitation as necessary, and to proceed to the development process without adverse effects such as low density. The toner supply could be made uniform.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a developing device according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of the image forming apparatus main body according to the first embodiment of the invention.

FIG. 3 is a diagram illustrating a developer remaining amount detection member according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a developing device according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a process cartridge according to a third embodiment of the present invention.

[Explanation of symbols]

4 Developing device 9 Remaining developer amount detection member 42 toner container 43 Stirrer 44 Second stirring member 94a, b Remaining developer amount detection member 95a, b developer remaining amount detecting member

Claims (7)

[Claims] 1. A developing means for developing an electrostatic latent image on an electrostatic latent image carrier, a developer container for containing a developer to be supplied to the developing means, and inside or near the developer container. And a stirring means for stirring the developer in the developer container, the developer remaining amount detecting means for detecting the amount of developer in the developer container, and the stirring means for stirring the developer in the developer container. A developing device, characterized in that at least two detecting means are arranged in the longitudinal direction, and when it is judged that the developer is unevenly distributed in the longitudinal direction, the stirring force of the stirring means is strengthened. 2. The developer remaining amount detecting means according to claim 1, wherein the developer remaining amount detecting means is arranged in or near the developer container, and at least a pair of electrodes are arranged at a predetermined interval, and between the electrodes. 2. The developing device according to claim 1, further comprising a circuit for measuring the electrostatic capacity of the developing device. 3. The developer stirring means according to claim 1, which is a stirring means for stirring the developer by rotating or reciprocating a stirring member extending in the longitudinal direction inside the developer container, wherein the developer is unevenly distributed in the longitudinal direction. 2. The developing device according to claim 1, wherein when it is determined that the stirring member is operating, the operating speed of the stirring member is increased. 4. The developer stirring means according to claim 1, which is a stirring means for stirring the developer by rotating or reciprocating a stirring member extending in the longitudinal direction in the developer container, wherein the developer is unevenly distributed in the longitudinal direction. The developing device according to claim 1, wherein, when it is determined that the stirring member is operating, the operating time of the stirring member is lengthened. 5. The developing device according to claim 1, further comprising a plurality of developer stirring means, wherein at least one stirring means enhances the stirring force when it is determined that the developer is unevenly distributed in the longitudinal direction. Developing device. 6. An image forming apparatus comprising the developing device according to claim 1. 7. An image forming apparatus main body in which at least an electrostatic latent image carrier and developing means for visualizing an electrostatic latent image formed on the electrostatic latent image carrier with a developer are integrated. A process cartridge detachable from the process cartridge, comprising: the developing device according to claim 1.