JPH096107A - Developing device - Google Patents

Abstract

PURPOSE: To accelerate a color imaging speed by shortening the time required for recovering developer and made to be long because of the localization of the developer and accelerating the switching operation of developing. CONSTITUTION: A developing slit by shutters 6 and 7 is provided between a developer container 1 and a developer carrier 10. By arranging the developing slit inclinedly according to the localization of the developer, the equal quantity of developer can be attached to the carrier 10. Therefore, the developer is uniformly supplied and uniformly eliminated in the longitudinal direction in accordance with the rotation of the carrier 10. Besides, the developer can be eliminated from a developing part immediately after the developing is finished and it is not mixed with the developer of the other color. Since the developer can be eliminated from the developing part immediately after the developing is finished, the developing can be quickly switched. Besides, time required for the developing is shortened and the color imaging speed is accelerated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of supplying a developer in a developing device of a dry electrophotographic multicolor image forming apparatus.

[0002]

2. Description of the Related Art In a dry electrophotographic image forming apparatus, a developing device is a device for developing a developer on an electric latent image formed on a photoconductor. The multicolor image forming apparatus has a plurality of developing devices and develops the developers of respective colors one after another.

The developing method includes a method of developing the developer in a non-contact manner and a method of developing the developer in contact with the photoconductor. There are a method of retreating and moving from the body, a method of retreating and moving the photoconductor by fixing the developing device, and a method of collecting the developer in the developing device at the end of development.

In particular, the method of recovering the developer inside the developing device at the end of development does not move the developing device or the photoconductor, so that the development can be switched with a low load.

However, this method has a drawback that the time required to switch the development is longer than that of other methods because the operation of collecting the developer is performed every time. Further, there is a drawback that the developer recovery time in the longitudinal direction of the developing device varies depending on the bias of the developer in the developing device.

Japanese Utility Model Publication No. 6-35240 discloses a device having a shutter for stopping the supply of the developer to the developing section by the above method. This means that the shutter is closed after the development is completed. Further, there is JP-A-5-53438 as a means for uniformly transporting the developer into the container by using the developer detecting means.
Further, JP-A-4-90575 discloses that the opening degree of a communication opening can be adjusted between a developer supply section and a developer transport section in order to uniformly supply the developer from the developer supply section to the developing container. There is.

[0007]

In the method of recovering the developer into the developing device at the end of the development, if the developer is biased in the developing device, the developer recovery time in the longitudinal direction of the developing device is unsatisfactory. Since it was uniform, it took time to switch to development of another color. Further, even if the developer supply amount is made uniform on the developing supply container side as in Japanese Patent Laid-Open No. 4-90575, the developer on the developing roll must be made uniform until it is finally supplied to the developing roll. Unevenness cannot be eliminated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a developing machine in which the time for collecting the developer in the longitudinal direction of the developing device is uniform and the development can be switched quickly.

If the amount of the developer supplied to the developing section of the developing device is uniform in the longitudinal direction, the developer can be collected in almost the same time. Therefore, the development can be switched in consideration of the developer recovery time.

[0010]

A feature of the present invention is that the developer flows uniformly in the longitudinal direction between a stirring roll that conveys the developer from the developer container to the developer carrying member and the developer carrying member. This is because a developer regulating means having an inclination is provided. Furthermore, it has a drive means which drives the said regulation means.

By having the detecting means for detecting the inclination of the developer, the flow rate of the developer to the developer carrying member can be regulated to a desired amount.

[0012]

In the developing device, there is a developer reservoir that temporarily stays before the developer is conveyed from the developer container and adheres to the developer carrier. In the method of collecting the developer inside the developing device at the end of the development, the developer is supplied to the developing section until the developer in the developer reservoir is used up.

In the present invention, in order to prevent the amount of the developer in the developer reservoir from becoming non-uniform, a developer regulating means having an inclination according to the bias of the developer is arranged to regulate the flow rate of the developer, Make sure that the developer is uniformly accumulated in the developer reservoir. For example, the opening of the regulating means at the portion where the developer accumulates quickly may be narrowed.

Further, at least one driving means for moving the regulating means is prepared, and the driving means is driven according to the bias of the developer. Providing a detecting means for detecting the bias of the developer allows the developer to be uniformly accumulated in any developer.

[0015]

EXAMPLES First, in a developing device of a dry electrophotographic apparatus,
How the developer is supplied and developed will be described. FIG. 2 is a perspective explanatory view of a developing device using a two-component developer.

The developer 2 is transported from the developer container 20 and consumed. After that, the developer not used for the development is collected in the developer container 20 by the collecting magnet roll 11 as the collecting means, and together with the developer 2 replenished from the toner container 1, the stirring means 4 (blades, paddles, By the friction with the screw), sufficient charging for developing the developer is performed. The charged developer is conveyed by the developer conveying means 5 to the side of the developing magnet roll 10 which is a developer carrier, and at this time, it contacts the developing magnet roll 10 through the shutter 6. The flow rate of the developer on the developing magnet roll 10 is regulated by the doctor blade 8.
A uniform developer layer is formed on the developing magnet roll 10. This developer layer is close to the photoconductor and is used for development.

As described above, the developer not used for the development is collected by the collecting magnet roll 11, scraped off by the scraper 12, and returned to the developer container 20.

By the way, the excess developer regulated by the doctor blade 8 stays in the developer reservoir 9 which is a space in front of the doctor blade. When the supply of the developer from the developer container is stopped and the developing magnet roll is rotated to consume the developer, the accumulated developer passes through the doctor blade 8 and is consumed.

The operation of collecting the developer adhering to the developer carrying member inside the developing device is called an ear cutting operation. The developing device of the multicolor image forming apparatus using the method of performing the cutting operation after the completion of the development stops the supply of the developer from the developer container after the desired development process is completed, Also consumes the developer and then eliminates the developer on the developing roll so that development cannot be performed in the developing section.

In the conventional developing device, the shutters 6 and 7 which are the developer regulating means are constituted by members which are parallel to the longitudinal direction. In this method, when the developer is biased in the longitudinal direction of the developing device, for example, when the amount of the developer conveyed over the wall of the developer container is small as shown in FIG. 3 and as shown in FIG. In the case where the amount of the developer is large and the developer is sufficiently filled and conveyed to the upper part of the lower shutter 6 which is the developer regulating means, the amount of the developer staying behind the doctor blade 8 is different. For this reason, the developer collection time is different, and it is necessary to make a blank space between the papers by more than the difference in the collection time to eliminate the image loss, which is a drawback that the development cannot be switched immediately.

An embodiment of the present invention will be described below with reference to FIG. A feature of the present invention is that the developer passing through the slit is provided between the developing magnet roll 10 and the developer transporting means 5 in the developer container by providing an inclination in the slits provided in the shutters 6 and 7 as developer regulating means. That is, the flow rate can be made uniform and the development can be switched more quickly.

First, at the time of non-development, the developer transport means 5 (transport screw, transport blade, transport paddle, transport roll, etc.) behind the slit is basically stopped, and the developer is passed through the slits provided in the shutters 6, 7. Avoid spillage. Before the start of development, slits are opened at the opening width and position suitable for each developer. The stirring means 4 and the developer conveying means 5 on the developer container side behind the slit are rotated to supply the developer to the developing magnet roll 10. After that, the developing magnet roll 10 and the collecting magnet roll 11 are rotated,
Start development.

At the end of the development, the stirring means and the developer conveying means on the side of the developer container are stopped, the development is continued while consuming the developer behind the doctor blade, and the developer is cut off immediately after the completion of the development. To Therefore, the opening / closing timing and the opening degree of the slits provided in the shutters 6 and 7 must be made appropriate.

As for the rotation start timing of the stirring means 4 and the developer transport means 5, it is appropriate to start rotation about 1 to 2 seconds earlier than the start of development because the developer must be present in the developing section at the start of development. . Because doctor blade 8 in about 1 second
This is because the developer can be replenished to the position of the rear developer reservoir 9. As a matter of course, if the developer can be replenished in the developer reservoir 9 before the doctor blade 8 for a shorter time, the rotation may be started immediately before the development is started. You may start rotating early enough.

Although the rotation stop timing of the stirring means 4 and the developer transport means 5 depends on the amount of the developer in the developer reservoir 9, it is considered appropriate to stop the rotation about 1 second earlier than the completion of the development. This is because the developer in the developer reservoir 9 is consumed in about 1 second. Needless to say, if the recovery time for removing the developer from the developer reservoir 9 in front of the doctor blade 8 is longer, the rotation may be stopped as soon as the recovery time for stopping the development, and there is no problem in color mixture of the developers. For example, the rotation may be stopped later than the end of development.

First, the one in which the shutter as the developer regulating means is fixed to the developing device will be described. The feature of the first embodiment is that the shutters 6, 7 which are the developer regulating means.
The upper end of the lower shutter 6 is inclined. Conventionally, the restriction wall of the lower shutter 6 is provided substantially horizontally, so that the flow rate of the developer to the developer reservoir 9 is different depending on the amount of the developer in the developer container 20 as described above. Therefore, by empirically knowing the unique characteristics of the developing device and the developer, the restriction wall is raised at the position where a large amount of developer accumulates,
At a position where a small amount of water is stored, the height of the shutter 6 on the lower side is set lower. This makes the pressure of the developer equal when the developer exceeds the regulation wall, and makes the amounts almost equal.
In this case, the upper surface of the regulation wall is simply made straight, but it is better to make it curved according to the degree of accumulation of the developer.

The height of the upper surface of the restriction wall is empirically determined as described above, but it may be set as follows. First, the developer regulating means between the developer container and the developer carrier is temporarily closed. Next, the developer agitating means and the conveying means are moved to check the bias of the developer. Next, the position of the upper surface of the developer on the developer regulating means side is measured. Thereafter, the temporarily closed developer regulating means is opened, and the position of the upper surface of the regulating means is set lower than the position of the upper surface of the developer by about 5 mm. For example, if the upper surface position of the regulating means is made equal to the upper surface position of the developer, the developer does not flow into the developer reservoir. Further, if the upper surface position of the regulating means is lower than the upper surface position of the developer by 10 mm or more, the flow amount of the developer tends to become non-uniform in a small developing device, which is not suitable. This is not the case with a large-capacity developing device. The slits provided in the developer regulating means are formed on at least one developer regulating plate. The simplest configuration is that the upper surface of the developer regulation wall rising from the bottom surface of the developer container is horizontally arranged, and a movable developer regulation plate is prepared above the regulation wall, and fixed to the developer regulation plate with screws or the like. There is one in which the regulating member is formed integrally with the developing device.

The characteristic of the second embodiment is that the upper shutter 7
The lower end of is inclined. Conventionally, the upper shutter 7 has almost no purpose of limiting the developer. The flow rate of the developer can be limited by individually setting the upper and lower intervals (slit intervals) using the upper shutter 7. For example, since the developer flowing pressure is high at a position where the developer is large, the slit interval is relatively narrow, and at the position where the developer is small, the developer flowing pressure is small, so the slit interval is relatively large. The best slit spacing is about 5 mm, but it varies depending on the configuration of the developing device and the fluidity of the developer. However, when the slit interval is 2 mm or less, the amount of developer flowing is extremely limited, which is not suitable. When using 2 mm or less, it is necessary to sufficiently prepare the developer on the developer container 20 side behind the slit.

This slit is composed of at least one developer regulating plate as described above. The simplest configuration is that the lower surface of the developer regulating wall extending downward from the upper surface of the developer container is arranged horizontally, and a movable developer regulating plate is prepared below the regulating wall, and fixed with screws or the like. In some cases, the developer regulating member is molded integrally with the developing device.

In this embodiment, since the developer cannot be developed unless the developer has passed over the lower shutter 6 and supplied,
At least the upper surface of the lower shutter 6 must be lower than the upper surface of the developer. When the flow rate of the developer is low at a certain position, the flow rate of the developer tends to increase if the upper shutter 7 is raised to widen the slit width, but the flow rate of the developer slightly increases because it cannot pass the lower shutter 6. In many cases. In this case, the lower shutter 6 has to be lowered to increase the flow rate.

The restricting means shown in the first and second embodiments is
Although each of them may be used alone, the outflow pressure and the outflow amount of the developer can be made equal by combining both.

The opening degree is set so that the flow rate of the developer is substantially constant, so that it is wide enough to prevent the developer from sticking and does not open wide at random. In the case of a two-component developer, the width is set to about 2 mm to 10 mm, preferably 3 mm to 5 mm. The width of the one-component magnetic developer is set to about 1 mm to about 6 mm, preferably about 3 mm.

As another embodiment, there is a method of adding a moving guide and a driving means for opening and closing the slit by moving the shutter to open and close the slit and limit the flow rate of the developer. For example, the developer is moved by the stirring means and the conveying means in the developing container, but since the bias of the developer varies depending on the rotation direction and the rotation speed,
There is a suitable arrangement of restricting means at the start and end of development. By using the drive means as described above,
It can be arranged appropriately.

As for the opening timing of the slit, there is a method of opening the slit in response to the start of the exposure signal of each printed image, in addition to the method of driving at the start of development or corresponding thereto. This is to adjust the opening timing of the slit in consideration of the start time of each printing signal and the time from the exposure position to the developing position. For example, during normal standby, it is made horizontal as shown in FIG. 5, and the slits are driven as shown in FIG. 6 according to the inclination of the developer.

The closing timing of the slit depends on the amount of the developer remaining in the developer reservoir, and is empirically set before the end of development based on the amount. If the amount is extremely small, the developer will be collected immediately if the slit is closed almost at the same time as the development is completed, but if the amount is large, it will take a long time until the developer is collected even if the slit is closed. The fact that the ear-cutting time is long means that the ear-cutting can be completed almost at the same time as the development is completed by closing the slit in advance for that time. Actually, the amount of developer in the developer reservoir changes depending on the bias of the developer and the opening degree, so the cutting time differs partially.Therefore, the slitting time is equal to the shortest cutting time before the end of development. Close. Although it depends on the configuration of the developing device and the process speed, the slit is generally closed before the development is completed for about 1 second.

The arithmetic unit for determining the opening / closing of the slit inputs the printing medium, the printing color, the number of printed sheets, the printing start position, the printing end position, etc. from the printing information and determines the opening / closing timing. In addition, the opening / closing timing is determined based on the rotation control information such as the developing magnet roll and the transport roll from the print control information.

By providing a developer sensor for detecting the developer inside the developing device, the deviation of the developer can be grasped finely. The developer sensor includes a sensor for detecting the presence or absence of the developer, a sensor for detecting the amount of the developer, a sensor for detecting the toner concentration in the developer, and the like. By mounting the developer sensor on at least one side, the inclination of the developer to be judged can be known from the position of the sensor. It is desirable to attach two or more developer sensors because the amount and inclination of the developer can be comprehensively determined by using a plurality of developers. For example, as shown in FIG. 6, the developer can be installed on the left and right ends of the developer container to know the overall inclination.

The developer sensor has a magnetic permeability of the developer, a pressure,
What is detected based on the optical transmittance is used. Any one of them is converted into an electric signal, and a desired drive is performed by comparison with a reference voltage. For example, when the developer accumulates in front of the optical sensor and light cannot be received, it is detected that there is a large amount of the developer and the drive for narrowing the slit is performed.

The slit is constructed as follows. FIG.
As shown in Fig. 7, those made of plates having a uniform thickness and width in the longitudinal direction, those made of rods, columnar shapes with concave surfaces as in Fig. 7, and the axial center being slanted as in Fig. 8. Cylindrical shape,
There is a cylindrical shape with a hole as shown in FIG. The cylindrical shape or the cylindrical shape has a concave surface or a hole formed obliquely with respect to the rotation axis, and it is desirable that the number thereof is plural. With the cylindrical shape, the amount of the developer can be adjusted by rotating the rotating shaft. Further, in the shape as shown in FIG. 9, the left side in the figure opens downward. Therefore, it can be applied when there is little developer on the left side. On the contrary, when there is a large amount of developer on the left side, the cylinder is rotated half a turn so that the left side opens upward.

The following methods are available as driving means for opening and closing the slit.

As a method of opening and closing the slit by using magnetic force, there is a method of opening and closing by rotating a fixed angle using a stepping motor. There is also a method of preparing a stopper that serves as a slit receiving member for preventing the opening of an extra slit and opening and closing the slit by a motor or an electromagnet. In this method, since magnetic force is used to open and close the slit, the developer easily attaches to the opening / closing means that generates magnetic force. Therefore, a seal member is required around the slit opening / closing means to prevent the developer from adhering. The above motors and electromagnets are driven according to the output of the arithmetic unit.

As another embodiment, there is a method of preventing the developer from leaking at an unnecessary time by closing the developing slit which is the developer regulating means after the developing process is completed and the developer is collected. As a result, it is possible to prevent image defects due to toner loss or the like.

There is also a method in which the unit containing the developer container and the unit containing the developing magnet roll are separately provided. According to this method, the developer can be easily replaced by removing the developer container unit, and the spill of the developer at the time of separation can be prevented by closing the slit.

Further, in the above-described embodiment, the description has been made on the constitution in which the two rotating members of the stirring means and the developer conveying means are arranged in the developer container, but the developer conveying means has the function of the stirring means. Alternatively, only the transporting means may be arranged.

As the developer, a two-component dry developer has been described above, but a one-component magnetic developer may be used.

The developing magnet roll and the collecting magnet roll do not have to be individual units. For example, a magnet roll and a non-magnetic sleeve including the magnet roll may be used.

[0047]

As described above, according to the present invention, the supply of the developer to the developing roll can be made uniform, and the time required for the recovery of the developer becomes uniform, so that the switching time of the development can be shortened. Color printing can be speeded up.

[Brief description of drawings]

FIG. 1 is one of embodiments of a developing device of the present invention.

FIG. 2 is a perspective explanatory view of a conventional developing device.

FIG. 3 is a cross-sectional explanatory diagram when a developer container contains a small amount of developer.

FIG. 4 is an explanatory cross-sectional view when a developer container contains a large amount of developer.

FIG. 5 is a perspective view illustrating the developing device according to the present exemplary embodiment when the developing device is stopped.

FIG. 6 is a perspective view illustrating the developing device according to the present exemplary embodiment when driven.

FIG. 7 shows an example of a developer regulating means used in this embodiment.

FIG. 8 shows an example of a developer regulating means used in this embodiment.

FIG. 9 shows an example of a developer regulating means used in this embodiment.

[Explanation of symbols]

1 ... Toner container, 2 ... Developer, 3 ... Developer sensor, 4 ...
Agitating means, 5 ... Developer conveying means, 6, 7 ... Shutter, 8
... doctor blade, 9 ... developer reservoir, 10 ... developing magnet roll, 11 ... recovery magnet roll, 12 ... scraper, 20 ... developer container.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Kumada 1-1-1 Higashitaga-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Electric Appliances Division, Taga Headquarters (72) Inventor Katsumi Mikami Hitachi, Ibaraki 1-1-1, Higashitaga-cho, Higashi-shi, Hitachi, Ltd. Electric Appliances Division, Hitachi, Ltd. (72) Inventor, Shoji Takeya 1-1-1, Higashi-Tagacho, Hitachi, Ibaraki Hitachi Ltd., Electric Appliances Division, Hitachi Ltd. In headquarters

Claims (7)

[Claims] 1. A developer container, which uses a dry developer containing a magnetic carrier or magnetic powder and has a stirring means for storing and stirring the developer and a conveying means for conveying the developer after stirring, and an electric container. A developer carrier that faces the latent image carrier that forms the latent image and carries the developer, and the developer is carried to the developer carrier by the carrying means in the developer container, and the latent image carrier is developed. In a developing device of an electrophotographic multicolor image forming apparatus having a collecting unit that collects the developer that has not been used for development in the developer container, the developing device is provided between the conveying unit and the developer carrier. A developing device, comprising: a developer regulating means having a slit for restricting a flow, wherein the slit of the developer regulating means is inclined in accordance with the bias of the developer in the developer container. 2. A dry developer containing a magnetic carrier or magnetic powder, and a stirring means for accommodating and stirring the developer, and a developer container having a conveying means for conveying the developer after stirring. A developer carrying body facing the latent image carrying body that forms an electric latent image and carrying a developer, and a carrying means in the developer container carry the developer to the developer carrying body and develop it on the latent image carrying body. In a developing device of an electrophotographic multicolor image forming apparatus having a collecting unit that collects the developer that has not been used for development in the developer container, between the conveying unit and the developer carrier, A developing device, characterized in that a developer regulating means having a slit for restricting a flow is provided, and a width of the slit of the developer regulating means is varied depending on a bias of the developer in the developer container. 3. The developing device according to claim 1, wherein the developer regulating means is movable, and at least one driving means for adjusting the opening of the developer regulating means is provided. 4. The developing device has at least one detecting means for detecting the amount of the developer, and the inclination of the regulating means inside the developing device changes according to the deviation of the developer. The developing device according to claim 3. 5. A developing device, characterized in that the developer regulating means is closed after completion of the developing process. 6. A developer container and a developer carrier are separate bodies,
A developing device, characterized in that the developer regulating means is closed at the time of separation. 7. The developing device according to claim 1, wherein the conveying means has a function of the stirring means, and only the conveying means is provided in the developer container.