JP3024811B2 - 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 a developing device used in an image forming apparatus such as an electrophotographic copying machine or a printer.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine or a printer, an electrostatic latent image formed on a photosensitive drum is
It is developed by a developing device. The developing device generally has a developing device in which a developer including a carrier and a toner is stored, and the toner in the developer is supplied to the photosensitive drum by the developing device. The electrostatic latent image is developed. A toner cartridge containing toner to be replenished into the developing device is mounted on the developing device, and the toner in the toner cartridge is supplied to the developing device by, for example, a spiral conveyor. The spiral conveyor extends long along the axial direction of the photosensitive drum in the developing device, and removes toner in the toner cartridge.
The toner is supplied to the developing device while being conveyed in the axial direction of the photosensitive drum, so that the toner is uniformly distributed in the axial direction of the photosensitive drum.

Further, the developing device is provided with a toner concentration sensor for detecting the amount of toner contained in the developer with respect to the carrier, that is, the toner concentration.
When the toner concentration detected by the toner concentration sensor reaches the lower limit of the proper range, the spiral conveyor is driven, and the toner in the toner cartridge is supplied to the developing device. Then, even when the spiral conveyor is driven, the toner density does not increase, and when it reaches a predetermined value lower than the lower limit of the appropriate range, the toner empty indicator is operated. This notifies that no toner remains in the toner cartridge. In this case, a plurality of continuous developing operations are prohibited at the same time, so that only one developing operation can be performed.

[0004]

In such a developing device, in the initial state where the developing operation has never been started,
The developing device contains a developer initially set to a predetermined toner concentration (for example, 4.5%). Then, the developing operation is started in a state where the toner cartridge filled with the toner is mounted in the developing device. In such an initial state, if a developing operation in which a large amount of toner is consumed is continuously performed, the toner concentration in the developing device will be rapidly reduced. Therefore, the toner density in the developing device becomes lower than an appropriate range. When such a state is detected by the toner density sensor, the spiral conveyor is driven, and the toner in the toner cartridge is supplied to the developing device. . However, in the initial state in which the developing operation has never been performed, no toner is transported into the spiral conveyor that has become longer in the axial direction of the photosensitive drum. It takes a relatively long time to be supplied and attain the proper concentration.
For this reason, even though the spiral conveyor is driven, the toner is not properly supplied into the developing device. Therefore, although the toner concentration in the developing device does not immediately rise, a large amount of toner is continuously consumed, and as a result, the toner concentration reaches the lower limit value at which the toner empty indicator should be operated. As a result, even though a large amount of toner is present in the toner cartridge, the toner empty indicator is operated, and thereafter, there is a problem that the developing operation of a large number of sheets cannot be performed continuously. Such a problem also occurs when toner in the spiral conveyor is discharged by maintenance.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to reliably prevent a toner empty display from malfunctioning even when a continuous developing operation is performed in an initial state or after maintenance. It is an object of the present invention to provide a developing device which can be used.

[0006]

According to the present invention, there is provided a developing apparatus comprising:
A developing device that develops the electrostatic latent image formed on the surface of the optical drum with the toner contained therein, a toner cartridge containing the toner to be replenished in the developing device, and a toner in the toner cartridge In the axial direction of the photosensitive drum
The toner conveying device for supplying the developing vessel while transporting along a toner density sensor for detecting a toner concentration in the developer in the developing vessel, the toner transporter on the basis of the output of the toner density sensor A toner empty indicator for notifying that no toner is present in the toner cartridge; a means for controlling the toner empty indicator based on the output of the toner density sensor; and In the initial state where the developer is set
Before the developing operation is started , the developing device is driven so that the toner inside the developing device is consumed .
Rutotomoni makes the toner transporter and and means for controlling, based on an output of the toner density sensor,
Thereby, the above object is achieved.

[0007]

In the developing device of the present invention, the developer is contained in the developing device.
In the initial state where
Until the developing device is driven,
Toner in the developer is consumed is adhered to the photosensitive drum surface, at the same time, the toner transporter is controlled in, DOO
The toner is sequentially supplied from the toner cartridge by the toner transporter based on the output of the toner density sensor that detects the decrease in the toner density . When the toner concentration in the developer reaches the appropriate range, the supply of the toner by the toner transporter is stopped. In such a state, since the toner remains in the toner supply device , the developing device
Becomes possible.

[0008]

The present invention will be described below with reference to examples. The developing device of the present invention is used, for example, in an electrophotographic copying machine. As shown in FIG. 1, the developing device includes a photosensitive drum.
It has a developing device 20 which is arranged on the side of 10 and contains a developer composed of a toner and a magnetic carrier. An image is exposed on the surface of the photoreceptor drum 10 in a state charged by a charging device to form an electrostatic latent image. Then, the electrostatic latent image on the photosensitive drum is developed with toner by the developing device of the present invention, and the toner image is transferred onto recording paper. The toner remaining on the surface of the photosensitive drum 10 to which the toner image has been transferred is scraped off by a cleaning blade of a cleaning device.

In the developing unit 20, a predetermined amount of toner and a carrier are stored in advance so as to have a predetermined toner concentration. The developing device 20 includes a developing roller 22 disposed in the housing 21 so as to face the photosensitive drum 10, a stirring roller 23 disposed farther from the photosensitive drum 10 with respect to the developing roller 22, The stirring roller 23
And a supply roller 24 disposed on the far side of the photosensitive drum 10. The developing roller 22, the stirring roller 23, and the supply roller 24 are respectively
Are parallel to the axial direction. A partition plate 26 is disposed in a central portion of the housing 21 above the stirring roller 23 so as to cover the stirring roller 23.

The developer accommodated in the housing 21 passes below the partition plate 26 and is conveyed to the developing roller 22 while being stirred by the supply roller 24 and the stirring roller 23, and a part of the developer is By 22, it is conveyed to the photosensitive drum 10. The developer toner conveyed by the developing roller 22 adheres to the electrostatic latent image formed on the photosensitive drum 10 and develops the electrostatic latent image with the toner. The developer not conveyed on the peripheral surface of the developing roller 22 is conveyed above the supply roller 24 through the partition plate 26.

On the upper surface of the housing 21 of the developing device 20, a toner density sensor 25 is disposed. The toner concentration sensor 25 detects the toner concentration of the developer conveyed on the partition plate 26, and outputs a higher potential as the toner concentration decreases.

A spiral conveyor 30 is disposed above the supply roller 24 in the developing device 20 as a toner transporter. As shown in FIG. 2, the spiral conveyor 30 has a supply roller parallel to the axial direction of the photosensitive drum 10.
A cylindrical casing 31 extending parallel to 24 except for the base end
And a spiral 32 rotatably arranged in the casing 31, and a toner supply motor 33 connected to a base end of the spiral 32 to rotate the spiral 32. On the base end of the spiral conveyor 30, a toner cartridge 40 is mounted. The toner cartridge 40 is detachable from the base end of the spiral conveyor 30. A portion of the casing 31 facing the supply roller 24 is provided with a toner supply port 31a (see FIG. 1) whose size is gradually increased from the base end side to the tip end side.

The toner in the toner cartridge 40 is sequentially transferred to the casing 31 by the rotation of the toner supply motor 33 and the rotation of the spiral 32 in the casing 31.
An opening 31 provided in the casing 31
The developer is supplied sequentially from a into the developing device 20.

The output of the toner density sensor 25 attached to the housing 21 of the developing device 20 is input to a toner controller 50 as shown in FIG. The motor 33 is controlled. The toner controller 50 drives the toner supply motor 33 when the toner density detected by the toner density sensor 25 reaches the lower limit of the appropriate range, and the toner density detected by the toner density sensor 25 falls within the appropriate range. When the upper limit is reached, the driving of the toner supply motor 25 is stopped.

The output of the toner controller 50 is also provided to a toner empty display 60, and the toner density sensor 25
The toner empty indicator 60 is controlled in accordance with the output of. The toner controller 50 is operated when the toner concentration in the developing device 20 reaches a predetermined value lower than the lower limit of the appropriate range even though the toner supply motor 33 is driven. This notifies that no toner remains in the toner cartridge 40.

Further, the toner controller 50 is set to an initial state in which the developing operation is not performed and the initially set developer is not consumed, or a state in which continuous development is possible such as a state in which maintenance is completed. The toner supply motor 33 of the developing device 20 and the spiral conveyor 30 is driven.
In this case, the photosensitive drum 10 is also driven to rotate without being exposed. These driving operations are continued until the output of the toner density sensor 25 reaches an appropriate range.

The operation of the developing device of the present invention having such a configuration will be described. In an initial state in which the toner in the initially set developer in the developing device 20 is not consumed, the developing device 20 and the photosensitive drum are so disposed that the toner in the developing device 20 is consumed.
The ram 10 is driven, and the spiral conveyor 30 is controlled based on the output of the toner density sensor 25. Feeling
The light drum 10 is not exposed for image formation. By driving the photosensitive drum 10 and the developing device 20, the developer in the developing device 20 is sequentially attached to the surface of the photosensitive drum 10 and consumed.

When the toner in the developing device 20 is sequentially consumed,
The toner density in the developing unit 20 decreases, and the toner density sensor
The output of 25 reaches the lower limit of the proper range for the toner concentration in the developer . In such a state, the toner controller 50
The toner motor 33 in the spiral conveyor 30 is driven. As a result, the toner in the toner cartridge 40 is sequentially conveyed by the spiral conveyor 30. However, since the toner does not initially exist in the casing 31 of the spiral conveyor 30, the toner in the toner cartridge 40 is supplied to the developing device. Until the inside of the developing unit 20 is reached, the toner in the developing unit 20 is sequentially consumed. However, in this case, since the control of the toner empty display lamp 60 is not performed, even if the toner concentration in the developing device 20 is significantly reduced,
The toner empty indicator 60 is not operated. Then, when the toner is transported into the developing device 20 by the spiral conveyor 30, the toner concentration in the developing device 20 increases, and when the toner concentration detected by the toner concentration sensor 25 reaches the upper limit of the appropriate range, The driving of the toner supply motor 33 is stopped.

In this case, if the toner remains in the casing 31 of the spiral conveyor 30, the toner is immediately supplied to the developing unit 20 by driving the toner supply motor 33. Is stopped in a short time.

At the time of such control, the photosensitive drum
In an electrophotographic copying machine in which a cleaning blade for cleaning the surface of the photoconductor drum 10 is always in sliding contact with the surface of the photoconductor drum 10, the developing device 20 drives the photoconductor drum.
10 The toner attached to the surface is removed and collected by the cleaning blade. Further, in the case of an electrophotographic copying machine in which the cleaning blade is in sliding contact with the photosensitive drum 10 only at the time of image formation, in such a control, the cleaning blade is used to collect the toner adhered to the photosensitive drum 10. It is slid on the photosensitive drum 10. When the electrophotographic copying machine is in an initial state, toner is attached when the toner is scraped off by the cleaning blade. As a result, there is no risk that the tip of the cleaning blade will be rolled up by the sliding contact with the photosensitive drum 10 thereafter.

By performing such control,
The developing device 20 is in a state in which a developer having an appropriate toner concentration is stored, and the spiral conveyor 30 is also filled with toner. Therefore, in such a state, the development in which the amount of toner required for one development is about 20% of the image forming area is continuously performed, and a large amount of toner is consumed. Even if the toner concentration drops sharply, when the toner supply motor 33 of the spiral conveyor 30 is rotationally driven, the spiral conveyor
The toner in the casing 31 in 30 is immediately supplied to the developing device 20, and the toner concentration in the developing device 20 is immediately increased. Therefore, the toner empty indicator 60
There is no risk of being operated incorrectly.

The above-described consumption of toner by driving the developing device 20 and the control of supply of toner to the developing device 20 by the spiral conveyor 30 are performed, for example, even when maintenance is completed.

In the above embodiment, a developing device using a two-component developer composed of a carrier and a toner has been described. However, the present invention relates to a one-component developer composed of only a toner. The present invention can be applied to a developing device to be used.

[0024]

As described above, according to the developing device of the present invention, the toner transporter and the toner empty indicator are controlled based on the output of the toner sensor. In a state where continuous development is possible, the control in which the toner in the developing device is consumed and the toner is supplied by the toner conveying device is performed.
The toner remains in the toner transporter. Therefore, even if continuous development is performed thereafter, the toner is immediately supplied into the developing device, so that a time lag of toner transport by the toner transport device does not occur, and erroneous control of the toner empty indicator is reliably performed. Is prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a developing device of the present invention.

FIG. 2 is a perspective view of a main part thereof.

[Explanation of symbols]

 10 Photoconductor drum 20 Developing unit 22 Developing roller 25 Toner density sensor 30 Spiral conveyor 31 Casing 32 Spiral 33 Toner supply motor 40 Toner cartridge 50 Toner controller 51 Toner empty display

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G03G 15/08-15/095 G03G 15/00 303 G03G 21/00 510

Claims (1)

(57) [Claims] A developing device for developing an electrostatic latent image formed on a surface of a photosensitive drum with toner stored in the developing device; a toner cartridge storing toner to be replenished in the developing device; Transfer the toner in the toner cartridge to the shaft of the photosensitive drum.
A developing unit in the toner conveying unit supplying the while transporting along the direction, and a toner density sensor for detecting a toner concentration in the developer in the developing vessel, the toner conveying based on the output of the toner density sensor and means for controlling the vessel, the toner empty indicator notifying that the toner in the toner cartridge is not present, and means for controlling the toner empty display on the basis of the output of the toner density sensor, wherein the developing unit In the initial state where the developer is set
When the developing device is driven so that the toner inside the developing device is consumed before the developing operation is started ,
And a means for controlling the toner transporter based on the output of the toner density sensor.