JPH01314267A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent a toner blocking phenomenon arising on the inner wall, etc., of a toner hopper by providing an agitating member which orients toward one side from the other side of the bottom of the toner hopper and travels the almost entire bottom of the toner hopper and a control means changing the moving direction of the hopper whenever it starts. CONSTITUTION:The title device is provided with the agitating member 20 which divides the bottom of the toner hopper 9 with the aid of a recessed part 9b possessing a toner discharge port 15, houses a toner discharge roller 14 blocking the toner discharge port 15 in the recessed part 9b, passes above the recessed part 9b from the one side of the bottom divided by the recessed part 9b and moves to the other side, and the control means changing the moving direction of the agitating member 20 every time when it starts. As a result, a toner 8, adhering to the surface of the toner discharge roller 14 and never falling from the toner discharge port 15 can again be returned to the recessed part 9b by the agitating member 20 even if the toner returns to the toner hopper 9. Thus, the toner never resides in the toner hopper 9 due to a blocking phenomenon resulting from the sticking toner.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to electrophotography in which an electrostatic latent image formed on a photoreceptor is developed using toner particles, the toner is transferred to paper, and the image is fixed by heat, pressure, etc. It is related to the device.

2. Description of the Related Art Conventionally, most electrophotographic devices have been devices that use dry toner, and have been put into practical use as copying machines, laser printers, and the like. This electrophotographic apparatus is a device that applies electrophotographic process technology, and in the electrophotographic process, a developing process is to develop an electrostatic latent image formed on a photoreceptor using toner particles. A device that constitutes a developing process. For example, a developing device that uses a two-component developing method that uses a mixture of toner and carrier as a developer generally uses a developing vat filled with developer and a toner hopper that stores replenishment toner. It is made. The toner in the toner hopper falls into the developing vat by the rotation of the toner supply roll, and is controlled so that the mixing ratio of toner and carrier in the developing vat is always kept constant. The toner filled in the toner hopper decreases as the toner is used, and some of the toner may adhere to the inner wall of the toner hopper, causing toner blocking (solidification), or be deposited in stagnation areas. When toner remains in the toner hopper, the capacity of the toner hopper is substantially reduced. Therefore, various attempts have been made to reduce toner blocking and toner remaining in the stagnation.

Hereinafter, a conventional developing device in an electrophotographic apparatus will be described with reference to the drawings.

FIG. 5 is a side cross-sectional view of a conventional developing device, and FIG. 6 is a perspective view of a part of the main part of the nana hopper of the conventional developing device.

In FIGS. 5 and 6, 1 is a photoreceptor made of a tube made of aluminum or the like, and a photoreceptor layer made of selenium (Se) or organic photoconductor (OPC) is coated on the outer peripheral surface of the tube in the form of a thin film. Reference numeral 2 denotes a charger, which is composed of a charging wire 3 made of tungsten wire or the like, a shield plate 4 made of a metal plate, and a grid plate 5. By applying a high voltage to the charging wire 3, the charging wire 3 causes corona discharge, and the photoreceptor 1 is uniformly charged via the grid plate 4. 6 is an exposure light beam emitted from an optical unit (not shown);
In the case of a copying machine, this is document light, and in the case of a laser printer, it is image data light. In the case of a laser printer, this exposure light beam 6 is controlled by signals from a host computer (not shown), and a desired image is formed on the photoreceptor 1 as an electrostatic latent image. 7 is a developing device, which includes a toner hopper 9 that stores toner 8, and a developing device that stores toner 8 and carrier 10, which is magnetic particles such as iron powder, and after mixing and stirring, transports the toner to developing sleeve 11 to form a magnetic brush. It consists of a bat 12. 13 is a toner hopper lid. 14 is rotatably supported at both ends within the toner hopper 9.
This is a toner discharge roller that supplies a certain amount of toner 8 into the developing vat 12 and closes the toner discharge port 15. 16a and 16b are loop-shaped motion transmitting members such as belts, chains, or ropes. Motion transmission member 16a
, 16b are sprockets 18a, 18 fixed to a rotating shaft 17 whose both ends are supported in parallel with the toner discharge roller 14.
b and the fixed shaft 19. 20 is arranged substantially parallel to the rotating shaft 17, and has both ends connected to the motion transmitting member 16.
This is a shaft-shaped stirring member attached to parts a and 16b. Sprockets 18a, 18b and toner discharge roller 1
4 is rotated by driving a sprocket gear 26 and a toner discharge roller gear 27, respectively, via idler gears 23, 24, and 25 using power from a motor 22 such as a stepping motor disposed on a chassis 21 of the machine body. Furthermore, the toner discharge roller 14 is arranged close to the toner hopper inner wall 9a. Motion transmission members 16a, 16b, rotating shaft 17, sprockets 18a, 1
The 8b1 rotating shaft 19 is attached to move the stirring member 20 along the inner wall of the toner hopper 9. 2
8 is a developer mixer, which is disposed within the development vat 12.

The developer mixer 28 stirs and mixes the toner 8 supplied from the toner hopper 9 through the toner discharge port 15 and the carrier 10, charges the toner, and conveys the toner to the developing sleeve 11.

The transported toner 8 and carrier lO are transferred to the developing sleeve 11
A magnetic brush is formed by the magnetic force of a magnet roller 29 fixed therein, and its height is limited by a doctor blade 30. As the developing sleeve 11 rotates, the magnetic brush comes into contact with the photoreceptor 1 and causes the toner 8 to adhere to the portion of the photoreceptor 1 where the electrostatic latent image is formed, thereby forming a powder image. 31 is a toner concentration sensor for detecting the mixing ratio of toner 8 and carrier 10;
is attached to. 32 is a developing section where development is performed.

Next, the operation of the above configuration will be explained. First, a corona discharge is caused by a charging wire 3 in a charger 2 connected to a high-voltage power source to uniformly charge the surface of the photoreceptor 1 to about -600V to -700V. Next, the photoreceptor 1 is rotated in the direction of arrow A and an exposure beam 6 such as a laser beam is irradiated onto the uniformly charged surface of the photoreceptor 1, and the irradiated portion of the photoreceptor 1 loses its charge. An electrostatic latent image is formed. On the other hand, the carrier 10 and toner 8 in the developing vat 12 are transferred to the developer mixer 28.
is sufficiently frictionally charged and attracted to the magnet roller 29, and is conveyed to the developing section 32 by the rotation of the developing sleeve 11. In this developing section 32, the carrier 10 and the toner 8 form a magnetic brush and come into contact with the photoreceptor 1. At this time, if a potential difference is applied between the developing sleeve 11 and the photoreceptor 1,
The toner 8 adheres to the electrostatic latent image portion on the photoreceptor 1 to form a visible image, and development is completed. Here carrier 10 and toner 8
The mixing ratio with toner is constantly sensed by the toner concentration sensor 31. When the toner 8 adheres to the photoreceptor 1 in the developing section 32 and is consumed, the toner concentration sensor 31 detects the toner in the developing vat 12.
It is detected that the mixing ratio of carrier 10 and toner 8 in the motor 2 is lower than a preset value, and the detection signal is sent to a host computer (not shown), and as shown in FIG.
2 and rotates the toner discharge roller 14 through various gears 23, 24, 25, 26, 27 to open the toner discharge port 1.
5, the toner 8 in the toner hopper 9 is replenished onto the developer mixer 28 in the developing vat 12, and the set mixing ratio is restored to maintain a constant mixing ratio.

Problems to be Solved by the Invention In the conventional developing device configured as described above, the toner 8 in the toner hopper 9 is initially in the state shown by line B in FIG. 5 when it is filled. As the toner discharge roller 14 rotates, the toner 8 in the toner hopper 9 falls into the developing vat and gradually decreases. The toner 8 filled between the toner discharge roller 14 and the toner hopper inner wall 9b is stirred by the stirring member 20 as the motion transmission members 16a and 16b rotate in the direction of arrow C, and the toner 8 is transferred to the toner discharge roller 14 side. 8 is pushed away. This prevents the toner 8 from stagnation, accumulation, and blocking. However, even if the toner 8 on the stirring member 20flll is used up, the toner 8 on the toner discharge roller 14 remains unconsumed due to blocking (as shown in D). Especially when the temperature is 40°C, relative humidity 8
This phenomenon occurred significantly in high temperature and high humidity conditions such as 0%.

Means for Solving the Problems However, the present invention eliminates the above drawbacks by providing a stirring member that runs from one side of the bottom surface of the toner hopper to the other and along almost the entire bottom surface of the toner hopper, and further includes: A control means is provided for changing the moving direction of the stirring member each time the stirring member is activated.

Effect: With the above means, as the toner discharge roller rotates, the toner falls from the toner discharge port, and some of the toner adheres to the surface of the toner discharge roller and returns to the toner hopper.
Alternatively, the toner on the agitation member passes over the toner ejection roller and causes blocking in the toner hopper, but when the moving direction of the toner ejection roller changes, the blocked toner is transported to the toner ejection roller again by the agitation member. It will be done. This can prevent toner blocking that occurs on the inner wall of the toner hopper.

Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a side sectional view showing an embodiment of the electrophotographic apparatus of the present invention, and FIG. 2 is an exploded perspective view of a portion of the toner hopper of the electrophotographic apparatus of the present invention.

In FIGS. 1 and 2, 1 is a photoreceptor, 2 is a charger, and is composed of a charging wire 3, a shield plate 4, and a grid plate 5. 6 is an exposure light beam emitted from an optical unit (not shown). A developing device 7 includes a toner hopper 9 for storing toner 8 and a developing vat 12.

A carrier 10 is mixed with the toner 8 and stirred. The toner 8 and carrier 10 are then conveyed to a developing sleeve 11 to form a magnetic brush. 13 is a toner hopper lid. A toner discharging roller 14 is rotatably supported at both ends within the toner hopper 9, supplies the toner 8 within the toner hopper 9 into the developing vat 12, and closes the toner discharging port 15.

9c is a recess formed on the bottom surface of the toner hopper 9, dividing the bottom surface into two. Further, the recessed portion 9c is formed by the toner discharge roller 1.
It stores 4. Reference numerals 16a and 16b are loop-shaped motion transmitting members such as belts, chains, or ropes. The rotating shaft 19 is supported at both ends so as to be parallel to the toner discharge roller 14 . Sprockets 18a and 18b are fixed near both ends of this rotating shaft 19. The motion transmission members L6a, 16b are sprockets 18a, 18b.
and the fixed shaft 19, and the toner discharge roller 14
The toner discharge roller 14 runs in a direction perpendicular to the axis of the toner discharge roller 14 across the upper part of the toner discharge roller 14 . Here, a rotating shaft or a sprocket may be used instead of the fixed shaft 19. 20
is arranged substantially parallel to the rotating shaft 19, and has both ends connected to the motion transmitting member 16a.

The stirring member attached to 16b has a round bar shape. The sprockets 18a, 18b and the toner discharge roller 14 are connected to a motor 22, such as a stepping motor, disposed on a chassis 21 of the machine body via idler gears 23, 24, and 25. The sprocket gear 26 and toner discharge roller gear 27 are driven by the motor 22, thereby rotationally driving the sprockets 18a, 18b and the toner discharge roller 14. A developer mixer 28 is disposed in the developing vat 12 and stirs and mixes the toner 8 supplied from the toner hopper 9 through the toner discharge port 15 and conveys it to the developing sleeve 29. The conveyed toner 8 and carrier 10 are formed into a magnetic brush by the magnetic force of a magnet roller 29 fixedly arranged inside the developing sleeve 11, and the height thereof is limited by a doctor blade 30.
As the developing sleeve 11 rotates, the magnetic brush comes into contact with the photoreceptor 1 and causes the toner 8 to adhere to the electrostatic latent image portion of the photoreceptor 1 to form a powder image. 31 is a toner concentration sensor for detecting the mixing ratio of toner 8 and carrier 10, and is attached to doctor blade 30. 32 is a developing section where development is performed.

FIG. 3 is a block diagram of the main parts of the circuit of the electrophotographic apparatus of the present invention. In FIG. 3, reference numeral 33 denotes a control device including a microcomputer, and a toner concentration sensor 31 is connected to an input terminal. 34 is a driver for the motor 22, and is connected to an output terminal of the control device 33.

A power source 35 supplies power to the control device 33 and the driver 34.

Next, the operation of the above configuration will be explained. First, a corona discharge is caused by a charging wire 3 in a charger 2 connected to a high-voltage power source to uniformly charge the surface of the photoreceptor 1 to about -600V to -700V. Next, the photoreceptor 1 is rotated in the direction of arrow E and the exposure light beam 6 is irradiated onto the uniformly charged surface of the photoreceptor 1.
The charge disappears from the irradiated area and an electrostatic latent image is formed. on the other hand,
The carrier 10 and toner 8 in the developing vat 12 are sufficiently triboelectrically charged by the developer mixer 28 , attracted by the magnet roller 29 , and conveyed to the developing section 32 by the rotation of the developing sleeve 11 . In this developing section 32, the carrier 10
The toner 8 forms a magnetic brush and contacts the photoreceptor 1.

At this time, when a potential difference is applied between the developing sleeve 11 and the photoreceptor 1, the toner 8 is attached to the electrostatic latent image portion on the photoreceptor 1 to form a visible image, and the development is completed.

The operation of the electrophotographic apparatus of the present invention will be described below with reference to the flowchart shown in FIG. In step a, the mixing ratio of carrier 10 and toner 8 is constantly sensed by toner concentration sensor 31. When the toner 8 adheres to the photoreceptor l in the developing section 32 and is consumed, when the toner concentration sensor 31 detects that the mixture ratio of the carrier 10 and toner 8 in the developing vat 12 is lower than a certain value, step b Proceed to , and determine whether toner replenishment is the first replenishment. If the toner is to be replenished for the first time, the process goes to step C and the motor 22 is rotated in the forward direction. As a result, the driving force of the motor 22 is transferred to various gears 23, 24.
, 25, 26, and 27, the toner discharge roller 14 is rotated, and the toner 8 in the toner hopper 9 is replenished onto the developer mixer 28 in the development vat 12 through the toner discharge port 15. In step d, it is determined whether the toner concentration has been recovered, that is, whether toner replenishment has been completed, and the driving of the motor 22 is maintained until toner replenishment is completed. When toner replenishment is completed, data indicating the rotational direction of the motor 22 is stored in step e, and the process returns to step a to monitor the toner concentration again. If it is determined in step b that the toner replenishment is not the first time, the process proceeds to step f, reads data indicating the rotational direction in which the motor 22 rotated during the previous toner replenishment, and reverses the direction indicated by the data read in step g. Rotate the motor 22 in the direction. Next, in step h, it is determined whether or not the toner in the toner hopper 9 has run out, and if the toner has run out, the image forming operation is finished, and if the toner has not run out, the process proceeds to step i, where the toner density is restored. In other words, it is determined whether toner replenishment has been completed or not, and the motor 22 is kept driven until toner replenishment is completed. When toner replenishment is completed, data indicating the rotational direction of the motor 22 is stored in step j, and the process returns to step a, where the toner concentration is monitored again.

In the developing device of the present invention configured as described above, the toner 8 in the toner hopper 9 is initially in the F state, and simultaneously with the rotation of the toner discharge roller 14, the power of the motor 54 is applied to the rotating shaft 17. The motion transmitting members 16a and 16b are connected to the rotating shaft 17 and the fixed shaft 1 through the sprockets 18a and 18b.
Rotate in a loop between 9. Accordingly, the stirring member 20
G along the entire bottom surface of the toner hopper 9 in a direction perpendicular to the axial direction of the toner discharge roller 14
While crossing the vertical upper part of the toner 8, the toner 8 is agitated and pushed toward the toner discharge roller 14 (in the H direction). As a result, the amount of toner above the toner discharge roller 14 gradually decreases. Since the direction of rotation of the motor 22 is reversed each time the motor 22 starts rotating, toner is not blocked at a specific location within the toner hopper.

In the above embodiment, each time the motor 22 is started, the motor 2
Although the rotation direction of the motor 2 is reversed, the rotation direction of the motor 22 may be reversed after the motor 22 is activated several times.

Effects of the Invention As described above, the present invention divides the bottom surface of a toner hopper by a recess having a toner discharge port, stores a toner discharge roller that blocks the toner discharge port in the recess, and transfers the bottom surface divided by the recess from one side to the other. By providing a stirring member that moves toward the toner by passing over the recess, and a control means that changes the direction of movement each time the stirring member is activated, the toner does not adhere to the surface of the toner discharge roller and fall from the toner discharge port. Even if the toner is returned to the toner hopper, the toner does not accumulate in the toner hopper due to the blocking phenomenon that occurs when the agitation member returns the toner to the recess. Therefore, almost all of the toner stored in the toner hopper can be used, and the toner in the toner hopper is not wasted. Furthermore, since the capacity of the toner hopper is fully used, the interval between toner replenishment can be extended.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing an embodiment of the electrophotographic apparatus of the present invention, FIG. 2 is a perspective view of a portion of the toner hopper, FIG. 3 is a circuit block diagram of the main part, and FIG. 4 shows the same operation. 5 is a side view of the conventional electrophotographic apparatus, and FIG. 6 is a perspective view of the toner hopper portion of the same. l...Photoreceptor 2...Charger 3...
Charged wire 4... Shield plate 5... Grid plate 6.
...Exposure light beam 7...Developing device 8...Toner 9.
... Toner hopper 10 ... Carrier 1
1...Developing sleeve 12...Developing vat 13
... Toner hopper lid 14 ... Toner discharge roller
15... Toner discharge port 9b... Concave portion 16a
, 16b...Motion transmission member 17...Rotating shaft 18
a, 18b... Sprocket 19... Fixed shaft 20
... Stirring member 21 ... Chassis 22 ... Motor 23.24.25 ... Idler gear 26 ... Sprocket gear 27 ... Toner discharge roller gear 28 ... Developer mixer 29 ... Magnet roller 30...Doctor blade 31...Toner density sensor 32...Name of developing department agent Patent attorney Toshio Nakao and one other person Figure 5

Claims (1)

[Claims] A recess is formed in the bottom of the hopper for storing toner so as to divide the bottom, a toner discharge port is formed in the bottom of the recess, and the toner discharge port is closed and rotated to remove the toner adhering to the surface from the discharge port. A toner discharging roller to be discharged is housed in the recess, and a stirring member is provided that moves across the recess from one side of the bottom surface of the hopper to the other and returns to one of the bottom surfaces again, and each time the stirring member is activated. An electrophotographic apparatus characterized in that it is provided with a control means for changing the direction of movement of the electrophotographic apparatus.