JPH0618373Y2 - Development device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a developing device arranged in an image forming apparatus such as an electrophotographic copying machine, and more specifically, a two-component mixing system including a carrier and a toner. The present invention relates to a developing device in which an appropriate amount corresponding to the capacity of the developing device can be charged when the developer is charged into the housing of the developing device, and the initial setting of the developer amount can be easily performed.

(Prior Art) Generally, a developing device disposed opposite to an image bearing member such as a photoconductor drum includes a housing for containing a developer and a stirring member for stirring the developer contained in the housing. And a developing roller for supplying the developer uniformly dispersed by the stirring member to the image carrier.

In a developing device that uses a two-component mixed developer composed of toner and carrier, it is necessary to keep the toner concentration of the developer constant. Therefore, a sensor for detecting the toner amount of the developer has conventionally been provided in the housing. For example, a level sensor is arranged. This level sensor is mounted on the wall of the housing, and when the toner inside the housing is consumed by the operation of the electrophotographic copying machine and the developer amount falls below a predetermined level, the level sensor detects the decrease in the developer. The toner concentration in the housing is kept constant by replenishing the toner in the housing.

By the way, in operating the electrophotographic copying machine, when a predetermined amount of developer is put into the housing to initialize the developer amount, the appropriate amount of the developer in the housing is
The capacity of the housing, the capacity of the stirring member disposed in the housing, the amount of the developer adhered to the developing roller, and the like are determined. Therefore, the proper mounting position of the level sensor mounted on the wall surface of the housing is also naturally determined. It will be decided. The allowable range of the optimum mounting position of the level sensor is narrow, and if the mounting position of the level sensor deviates from the optimum mounting position, various inconveniences occur.

For example, when the mounting position of the level sensor is lower than the optimum mounting position of the wall surface of the housing, the developer is always contained in the housing in a smaller amount than the proper amount. Is strongly received, the developer may be sent to one side of the housing, and the developer may be biasedly accommodated in one side of the housing. When the developer is biasedly accommodated in the housing in this way,
There is a possibility that a small amount of developer adheres to one side portion of the developing roller in the width direction, resulting in poor density in image formation. When the electrophotographic copying machine is installed with a slight inclination, this tendency of density defect is particularly remarkable.

When the mounting position of the level sensor is higher than the optimum mounting position of the wall surface of the housing, the developer is contained in the housing in an amount larger than an appropriate amount, so that the stirring by the stirring member becomes insufficient, and Bias is also likely to occur.

Therefore, in general, the level sensor is mounted at the optimum vertical position on the wall surface of the housing. When the developer is put into the housing up to the position of the level sensor, conventionally, the developer is put into the housing little by little from the upper opening of the housing while the developing device is operated, and the level sensor At the time when the level was detected, the introduction of the developer was stopped.

In other words, when the developing device is stopped, the specific gravity of the developer that is being stirred by the stirring member is different from the specific gravity of the developer when it is stopped. Since the level of the developer in the housing is different from the level of the developer in the housing when the developing device is in operation, it is necessary to inject the developer into the housing while operating the developing device.

However, in such a method in which a small amount of the developer is charged into the housing, there is a drawback that it takes time to charge the developer, and more than a predetermined amount of the developer may be charged in the housing in some cases. There is a drawback that it is difficult to accurately add a predetermined amount of developer.

On the other hand, a container containing a predetermined amount of developer is prepared in advance so that the developer can be stored in the housing up to the level position of the level sensor provided in the housing. It is also conceivable that a predetermined amount of the developer is put into the housing from the container by setting the above-mentioned condition. However, even in this case, the specific gravity of the developer in the container and the specific gravity of the developer in the housing when the developing device is operating are different, and due to variations in each member during manufacturing of the electrophotographic copying machine, for example, Even if a predetermined amount of the developer is loaded into the housing due to the variation in the amount of the developer attached due to the magnetic strength of the magnet, the level of the developer does not actually match the position of the level sensor.

Further, for example, Japanese Patent Application Laid-Open No. 55-53373 proposes a developing device in which the position of a level sensor provided on a wall surface of a housing can be moved up and down. According to this configuration, after the predetermined amount of the developer is put into the housing, the level sensor can be arranged in the housing so that the level sensor is located at the developer level in the housing.

(Problems to be solved by the invention) However, according to the above configuration, the mounting position of the level sensor in the housing is not the optimum mounting position of the level sensor in the developing device, but the inside of the housing as described above. Since it is adjusted to the level of the developer put in, the following inconvenience occurs.

That is, when the amount of the developer introduced into the housing is small, the developer is agitated too much by the agitating member provided in the housing. Therefore, as described above, the developer is easily sent to one side of the housing by the stirring member, which may cause a density defect in image formation. Further, when the amount of the developer charged in the housing is large, there is a drawback that the stirring by the stirring member tends to be insufficient.

The present invention solves the above-mentioned drawbacks, and an object of the present invention is to provide a level sensor at an optimum position of a housing and to put the developer into the housing up to the level of the level sensor. To provide a developing device capable of always accurately and relatively easily introducing an appropriate amount of developer into a housing regardless of variations in each device of an electrophotographic copying machine when performing initial setting. is there.

(Means for Solving the Problems) A developing device of the present invention is a developing device which is arranged to face an image bearing member so as to develop an electrostatic latent image formed on the image bearing member with a developer. And a housing for accommodating the developer therein, a level sensor provided in the housing for detecting the level of the developer accommodated in the housing, and a position lower than the position of the level sensor. In the housing, a developer discharge port, and an opening / closing member that is arranged to open and close the developer discharge port and is opened / closed based on the detection result of the level sensor. The purpose is achieved.

(Embodiment) An embodiment of the present invention in an electrophotographic copying machine will be described below with reference to the drawings.

As shown in FIG. 2, the electrophotographic copying machine includes a document placing table 20 provided on an upper part of the machine body, a paper feeding device 21 provided on one side of the machine body, and a paper feeding device 21 provided at a substantially central part of the machine body. A photosensitive drum 22, which is an image bearing member, a charging unit 23 for charging the photosensitive drum 22, an exposure unit 24 having an optical system, and an electrostatic latent image formed on the photosensitive drum 22 as toner. The developing device 25 of the present invention for developing, the transfer device 26 for transferring the toner image developed by the developing device 25 to the recording paper P sent from the paper feeding device 21, and the toner transferred to the recording paper P. A fixing device 27 for fixing the image on the recording paper P is provided.

The operation of the copy image formation of the electrophotographic copying machine will be described. When the original is placed on the original placing table 20, the original placing table 20 moves. Meanwhile, the exposure unit
An electrostatic latent image corresponding to the original is formed on the photosensitive drum 22 which is exposed by 24 and is uniformly charged by the charging device 23. Then, the electrostatic latent image is toner-developed by the developing device 25, and the toner image is transferred to the recording paper P sent from the paper feeding device 21. After that, the recording paper P is separated from the photosensitive drum 22 by the separating device 26, and then the toner image is fixed on the recording paper P by the fixing device 27. After fixing, the recording paper P is guided to the paper discharge roller 29 and discharged to the storage unit 30. On the other hand, after the transfer, the residual toner remaining on the photosensitive drum 22 is removed by the cleaning device 31.

Next, the developing device 25 of the present invention will be described in detail.

The developing device 25 includes a housing 1 containing a developer,
An agitating member 7 for agitating the developer contained in the housing 1, and a developing roller 8 disposed in the housing 1 for attaching the developer to the photosensitive drum 22.
And have. A toner hopper 33 is provided on the upper side of the housing 1, and a developer recovery box 34 is provided on the lower side of the housing 1 at a position below a developer discharge port 4 described later.
Is provided.

The stirring member 7 is composed of a pair of stirring rollers 7a and 7b whose rotation directions are opposite to each other, and both of the stirring rollers 7a and 7b are driven by a drive motor.

At a predetermined position on the wall surface 10 of the housing 1, a level sensor 3 including a pressure-sensitive sensor capable of detecting the level of the developer contained in the housing 1 and a photo sensor is attached. The mounting position of the level sensor 3 is the height of the optimum amount of the developer accommodated in the housing 1 when the developing device 25 is driven. As shown in FIG. 1, a circular developer discharge port 4 is formed on the bottom surface 11 of the housing 1. On the lower surface of the bottom surface 11 of the housing 1, rails 12, 12 having an L-shaped cross section, which project in a direction opposite to each other, are provided in parallel with the developer discharge port 4 interposed therebetween. Below the bottom surface 11 of the housing 1, an opening / closing member 5 for opening / closing the developer discharge port 4 is arranged. The opening / closing member 5 has a closing plate portion 50 formed in a flat plate shape capable of closing the developer discharge port 4, and an operation piece portion 51 integrally extending downward from the closing plate portion 50. . The closing plate portion 50 has an opening 52 which has the same shape as the developer discharge port 4 and which can be aligned with the developer discharge port 4 by moving the closing plate portion 50. The closing plate portion 50 of the opening / closing member 5 is arranged below the developer discharge port 4 so as to be movable laterally along the housing bottom surface 11 with both side edges thereof engaged with the rails 12, 12. And a state in which the developer discharge port 4 is closed by the closing plate portion 50 by moving the opening / closing member 5 to the side,
The state in which the developer discharge port 4 and the opening 52 are aligned and the developer discharge port 4 is opened can be switched. On one side of the opening / closing member 5 in the moving direction, a solenoid 6 as an opening / closing driving means is attached to the bottom surface 11 of the housing, and the tip of the plunger 60 protruding from the solenoid 6 and the operation piece portion 51 of the opening / closing member 5 are provided. Are connected. A tension spring 53 is provided between the housing bottom surface 11 and the opening / closing member 5 on the other side of the opening / closing member 5 in the moving direction.

The solenoid 6 is driven based on the output of the level sensor 3, and when the level sensor 3 detects that the level of the developer contained in the housing 1 is equal to or higher than a predetermined level, the pulling spring 53 pulls the pulling spring 53. When the level sensor 3 detects that the level of the developer accommodated in the housing 1 is at a predetermined level by driving the solenoid 6 in the direction of retracting the plunger 60 against the force, the solenoid 6 is moved to the solenoid 6. It is designed to turn off electricity. When the solenoid 6 is driven to move the opening / closing member 5 to the solenoid 6 side, the opening of the opening / closing member 5
When the developer discharge port 4 is opened so that 52 coincides with the developer discharge port 4 and the solenoid 6 is de-energized, the opening / closing member 5 is pulled by the pulling spring 53, thereby developing the developer. The agent discharge port 4 is closed by a closing plate portion 50 of the opening / closing member 5.

FIG. 3 is a block diagram showing a control system for opening / closing the opening / closing member 5 of the present invention. In the figure, reference numeral 41 is a control unit using, for example, a microcomputer, the output of the level sensor 3 is given to the control unit 41, and the output of the control unit 41 drives the rotation of the developing roller 8. The operation display 43 is provided to confirm that the motor 9, the solenoid 6, and the level sensor 3 have detected the level of the developer.

The operation of the developing device 25 having such a configuration will be described with reference to the flow chart shown in FIG.

When a main switch of the electrophotographic copying machine is turned on after a larger amount of the developer than the reference amount is put into the housing 1, the drive motor 9 is turned on, and the developer supplied into the housing 1 is stirred by the stirring roller 7a. , 7b. Since the housing 1 contains a large amount of developer that exceeds the position of the level sensor 3, the control unit 41 turns on the solenoid 6 when the level sensor 3 detects the large amount of developer. The solenoid 6 for a predetermined time. By this operation, the developer discharge port 4 is opened for a predetermined time, and the developer in the housing 1 is discharged and collected in the collecting box 34 below. If the level sensor 3 detects the developer again after a predetermined time, the solenoid 6 is further driven for a predetermined time.

When the developer in the housing 1 is discharged from the developer discharge port 4 and the developer reaches a predetermined level, the level sensor 3 detects this predetermined level state, and the solenoid 6 is driven after a predetermined time elapses. Stop. Then, the opening / closing member 5 is pulled by the pulling force of the pulling spring 53.
Is moved, the developer discharge port 4 is closed by the opening / closing member 5, the drive motor 42 is turned off, and the rotation of the developing roller 8 is stopped. This completes the initial setting operation of the developer.

Although the solenoid 6 is used as the driving means of the opening / closing member 5 in the above-described embodiment, the detection result of the level sensor 3 is displayed on the display unit 43. The developer may be opened and closed to discharge the developer until the developer reaches a predetermined level. The developer discharge port 4 may be provided on the wall surface 10 of the housing 1 at a position below the level sensor 3.

(Effect of the Invention) As described above, according to the present invention, when a large amount of the developer is put in the housing in advance, the level of the developer can be detected by the level sensor. Excessive developer can be discharged to the outside of the housing through the developer discharge port until the developer level is almost at the level sensor position.

Therefore, if the level sensor is provided at a predetermined position of the housing, the developer specified by the level sensor can be accurately injected into the housing regardless of variations among the electrophotographic copying machines. Because you can
The initial setting of the amount of developer is easy, and there is no possibility that an image with poor density is formed due to lack of developer and stirring of toner and carrier fails due to excess developer as in the conventional case. Moreover, since the developer supply amount can be adjusted simply by opening and closing the opening / closing member, the operation for supplying a predetermined amount of developer can be performed relatively easily.

[Brief description of drawings]

1 is a perspective view from the bottom side of the housing of an electrophotographic copying machine showing an embodiment of the present invention, FIG. 2 is a sectional view of the electrophotographic copying machine, FIG. 3 is a block diagram of its control system, FIG. FIG. 4 is a flow chart for explaining the operation of the developing device of the present invention. 1 ... Housing, 3 ... Level sensor, 4 ... Developer discharge port, 5 ... Opening / closing member, 6 ... Driving means, 7 ... Stirring member, 10 ... Housing wall surface, 22 ... Image carrier .

Claims (3)

[Scope of utility model registration request] 1. A developing device disposed opposite to an electrostatic latent image formed on an image bearing member so as to develop the electrostatic latent image with the developer, the developing agent being housed inside. A housing; a level sensor provided in the housing for detecting the level of the developer housed in the housing; a developer discharge port provided in the housing at a position lower than the position of the level sensor; An opening / closing member which is arranged to open and close the developer discharge port and is opened and closed based on a detection result of the level sensor. 2. The opening / closing member opens a developer discharge port when the level sensor detects a developer of a predetermined level or higher, and the developer discharge port when the level sensor detects a developer of a predetermined level. The developing device according to claim 1, wherein the developing device is operated so as to close the outlet. 3. The developing device according to claim 2, wherein the opening / closing operation means of the opening / closing member is a solenoid.