JP2935926B2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation of charging a developer into a developing tank in a developing device of an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art As a conventional method of replacing a developer in a developing device, Japanese Patent Application Laid-Open No. 61-39061 discloses a method in which a toner concentration sensor provided in the developing device detects the absence of the developer being collected. When the detection is reached, the detection signal is used as a developer collection end signal, and the operation of the developer collection rotation system is stopped. At the same time, the developer supply device is operated,
A method of supplying a required amount of new developer into a developing device is disclosed.

[0003]

In the above-mentioned prior art, a supply device and the like are driven until a required amount of developer is supplied when a new developer is supplied into the developing tank.

Since the supply time is determined in consideration of variations in the supply and the state of the developer, the supply time is set to be slightly longer than the time required for actually supplying the developer.

For this reason, during the supply operation of the developer, the user is not touched by the image forming apparatus, and the extra driving time is lost even after the supply of the developer is completed, resulting in a dead time for a service person or the like. Work efficiency has deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a developing device which can save time after supply of a new developer. In addition, it is possible to transport the supplied developer evenly.
It is intended to provide an imaging device.

[0007]

As shown in FIG. 1, according to the present invention, a roller 4 and a roller 5 are rotatably provided in a developing tank 2, and a toner density for detecting the toner density in the developing tank 2 is used. A sensor 8 and a developer supply means 30 for supplying new developer to the developing tank 2; and a roller for driving the rollers 4 and 5 and the developer supply means 30 when a new developer is supplied and the toner density reaches a predetermined density. And a developer supply control device 33 for stopping the operation. Then, in order to transport the supplied developer evenly, the transport screw 2 is used.
2 and the stirrer 23 are provided coaxially, and a transfer path 26 is formed outside the transfer screw 22. An opening 26a is formed in the transfer path 26 from one side in the longitudinal direction to the other side.
6, the opening 26a is enlarged from one side in the longitudinal direction to the other side.

[0008]

In the means for solving the above problems, the developer has not yet reached the vicinity of the toner density sensor 8 immediately after the start of the supply of the developer, so that the toner density sensor 8 hardly outputs.
As the developer is supplied, the toner density increases, and finally the toner density becomes the toner density at the time of development, and thereafter becomes stable. Therefore, the reference value previously stored in the control device 33 and
The output of the toner density sensor 8 is compared to obtain a predetermined density.
At this point, the developer supply means 30 and the rollers 4 and 5
To stop.

Then, the sheet is conveyed by the conveying screw 22.
The developer to be transported moves in the transport path 26 from the front side to the back side in the B direction.
Sent to. At this time, the opening 26a of the transport path 26
Less developer overflows from one side and goes to the other side
And the distribution of developer becomes uniform in the longitudinal direction.
Become.

[0010]

FIG. 1 is a control block diagram of a developing device showing an embodiment of the present invention, FIG. 2 is a sectional view of the same developing device, FIG. 3 is a side sectional view of the same developing device, and FIG. FIG. 5 is a graph showing the output characteristics of the toner density sensor, and FIG. 6 is a graph showing the transition of the output of the toner density sensor when a new developer is supplied.

FIG. 2 shows a developing device in the image forming apparatus of this embodiment. 1 is a photosensitive drum, 2 is a developing tank, 3 is a toner hopper, 4 is a magnet roller, 5 is a stirring roller, 7
Is a sink plate, 8 is a toner concentration sensor, 9 is a doctor, 10
Denotes a toner supply roller, and 11 denotes a toner conveying screw.

Then, as shown in FIG.
Replenishing tank 20 for supplying developer and developer D in developer tank 2
Transport means 21 for transporting the
Is composed of a conveying screw 22 for conveying the developer D from one side in the longitudinal direction of the developing tank 2 to the other side, and a stirrer 23 for circumferentially stirring the developer D on the other side in the longitudinal direction.

As shown in FIG. 2, the transport means 21 is disposed immediately below the opening 2a of the developing tank 2 and obliquely above the stirring roller 5, and as shown in FIG. A transport screw 22 on one side of a transport means 21 is provided in a carry-in cylinder 24 protruding from the developing tank 2.

The conveying screw 22 is provided with a spiral plate mounted on a rotating shaft 25. The agitator 23 is formed of an agitator having a sectional shape as shown in FIG. The developing shaft 2 is mounted on the developing tank 2 and the carry-in tube 24 so that both ends of the rotating shaft 25 are rotatably supported.

Here, the replenished developer D is gradually advanced from the near side to the deep side of the developing tank 2 by the transport screw 22. However, since the entire developer D cannot be transported, the developing tank 2 , The developer distribution in the developing tank 2 becomes a mountain-like shape offset to the near side, and the developer D
Is higher on the near side and lower on the far side.

If the density of the developer D is not uniform, the image may be uneven. Therefore, in order to make the density uniform, re-stirring must be performed to some extent, and the efficiency is poor with the transport screw 22 alone.

Therefore, a developer conveying path 26 is formed outside the conveying screw 22, and an opening 26 a of the conveying path 26 is formed.
Are increased from the front side in the longitudinal direction to the back side.

The transfer path 26 is formed in a U-shape, and the transfer screw 2 is formed so that the opening 26a thereof is directed upward.
2 is provided so as to cover the periphery.

The wall of the conveying path 26 opposite to the direction of rotation of the conveying screw 22 gradually becomes lower from the near side to the far side.

A discharging screw 27 for discharging the deteriorated waste developer D from the developing tank 2 is disposed below the stirring roller 5 in the developing tank 2. It is housed in a carry-out cylinder 28 protruding from the tank 2 and both ends are rotatably supported.

The developer replenishing tank 20 is arranged on the front side of the developing device, and contains a supply screw and the like. Then, it is connected to the carry-in cylinder 24 via a pipe 20a,
The carry-in cylinder 24 and the developer replenishing tank 20 are opened and closed by a shutter (not shown) so that they can communicate with each other only when necessary.

A discharge port 30 is formed in the carry-out tube 28, and the discharge port 30 is connected to a collection container 31. The outlet 30 is usually closed with a cap or the like. The collection container 31 is disposed on the front side of the developing device similarly to the developer replenishing tank 20, and can be easily removed from the image forming apparatus main body.

As the toner density sensor 8, a magnetic permeability sensor is used. The toner density sensor 8 detects the amount of the carrier in a certain volume around the detection surface facing the inside of the developing tank 2, converts the amount into a voltage, and outputs the voltage. As shown in FIG. 4, the output voltage gradually decreases as the toner density increases.

The magnet roller 4, the stirring roller 5, the conveying screw 22 and the discharging screw 27 are used.
Is rotationally driven via a gear and a belt by a driving device 32 such as a motor disposed on the other side of the image forming apparatus main body, which is the other side of the developing device.

When a new developer is supplied, when the toner density reaches a predetermined density, the motor of the drive unit 32 and the developer supply means 29 are stopped so that the driving of the rollers 4, 5 and the developer supply means 29 is stopped. A developer supply control device 33 composed of a microcomputer for controlling the drive is provided on the main body side.

As shown in FIG. 1, the controller 33 controls the toner density sensor 8 corresponding to the toner density appropriate for the developing process.
And the reference voltage V ₀ storage means 35 stored in advance, and comparing means 36 for comparing the output voltage from the reference voltage V ₀ and the toner density sensor 8, the reference voltage V ₀ output voltage of the toner density sensor 8 And a stopping means 37 for stopping the developer supply means 29 and the driving device 32 when it is determined that the temperature has reached the predetermined value.

In the above configuration, when the old waste developer D is discharged and replaced with a new developer D, the discharge screw 2 is used.
When the driving device 32 is rotated by the driving device 32, the waste developer D in the developing tank 2 moves in the direction A on the front side by the rotation of the screw 27, drops from the discharge port 30 of the discharge tube 28, It is led.

Next, when a new developer D is supplied, the rollers 4 and 5 and the conveying screw 22 are driven and the shutter is opened, and the developer D flows from the developer supply tank 20 into the carry-in cylinder 24.

The developer D transported by the transport screw 22 is transported in the transport path 26 from the near side to the far side B direction.

Further, the amount of the developer D overflowing from the opening 26a of the transport path 26 is small at the near side and increases toward the back side, so that the distribution of the developer D is not biased toward the near side, and special stirring is performed. It is possible to supply the powder uniformly without the necessity. Then, the developer D is filled in the developing tank 2 by the stirring roller 5.

However, the transport screw 22 moves the developer D from the near side of the developing tank 2 to the opposite deep side, and the transport efficiency is excellent. However, if the transport screw 22 is extended to the front end. In this case, the developer D always moves in the direction B, the height of the developer D in the developing tank 2 becomes uneven, the toner density varies, and the copy image quality deteriorates.

To prevent this, a stirrer 23 is provided on the back side. This does not have the ability to transport in the B direction,
Since the agitating property in the radial direction is better than that of the transport screw 22, the developer D transported to the far side by the transport screw 22 is diffused in the radial direction by the agitator 23, and the level of the developer D is kept uniform as a whole. be able to.

By the way, since the developer has not yet reached the vicinity of the toner density sensor 8 immediately after the start of the supply of the developer, only the air exists around the detection surface, and the toner density sensor 8 detects the air. Since air has no magnetism, it is detected as toner and is detected as over toner. That is, as shown in FIG. 6, the output voltage is an output close to 0V. When the developer starts to reach the detection surface, the output gradually increases, and finally, the output becomes the reference voltage V ₀ (V) corresponding to the used developer at the time when the supply of the developer is completed, and is stabilized thereafter.

Therefore, the storage means 35 of the controller 33
The comparison unit 36 compares the output voltage of the toner density sensor 8 with the reference voltage V ₀ stored in the storage unit. When the sensor output reaches V ₀ , the stop unit 37 causes the developer supply unit 29 and The transport screw 22 and the like are stopped.

Accordingly, even when the supply of the developer is completed, the time for driving the developer supply means 29 and the like can be omitted, and the efficiency of the developer supply operation can be improved. it can.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention.

[0037]

As is apparent from the above description, according to the present invention, when a new developer is supplied, the driving of the roller and the developer supply means is stopped when the toner concentration reaches a predetermined concentration. The time for driving the developer supply means and the like after the supply is completed can be omitted, and the efficiency of the operation of supplying the developer can be improved. Then, the supplied developer overflows from the opening of the transport path, but the amount of the developer decreases on one side of the transport path and increases toward the other side. And can be supplied uniformly. In addition,
The developer that has not fallen into the developing tank from the opening is
The developer is accumulated on the other side because it is stirred in the circumferential direction
No, developed on the transport screw and the shaft of the agitator
The developer can be prevented from being transported, and the developer
It is possible to prevent the shaft from sticking due to insertion.

[Brief description of the drawings]

FIG. 1 is a control block diagram of a developing device showing an embodiment of the present invention.

FIG. 2 is a sectional view of the developing device.

FIG. 3 is a side sectional view of the developing device.

FIG. 4 is a sectional view of the agitator.

FIG. 5 is an output characteristic diagram of the toner density sensor.

FIG. 6 is a diagram showing an output transition of a toner density sensor when a new developer is supplied.

[Explanation of symbols]

 2 Developing tank 4 Magnet roller 5 Stirring roller 8 Toner density sensor 29 Developer supply means 33 Developer supply control device

Claims (1)

(57) [Claims] 1. A conveying screw for conveying a developer supplied to a developing tank from one side in a longitudinal direction to another side, and a stirrer for stirring the developer in a circumferential direction on the other side in the longitudinal direction are coaxial. A transport path is formed outside the transport screw corresponding to the transport screw, and an opening is formed in the transport path from one side in the longitudinal direction.
The developing device is formed so as to extend toward the side of the conveying path to the end of the transport path , and the opening is enlarged from one side in the longitudinal direction to the other side.