JPH0310517Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a developing device in an image forming apparatus such as an electrophotographic copying machine or a printer using electrophotographic technology.

[Prior art]

FIG. 1 is a block diagram of a conventional dry two-component type developing device that detects the volume of developer and controls toner density.

A magnet roll 3 is placed on the surface of the developing sleeve 2.
The developer 4 is adhered by the magnetic attraction force of the photoreceptor 1, and after regulating the adhered developer 4 to a constant height by the regulating member 9, the developer 4 is rubbed against the surface of the photoreceptor 1 to perform development. After development, the developer 4 on the developing sleeve 2 is separated from the developing sleeve 2 by the partition plate 11, stirred by the stirring roll 6, and sent to the developing sleeve 2 again.

Initially, the toner concentration of the developer 4 is at a predetermined concentration, but since only the toner is consumed during development, the toner concentration gradually decreases, and it becomes necessary to replenish the toner. At this time, in order to maintain the toner concentration, an electrostrictive vibrator 8 is installed on the side of the development hopper 5 to detect the volume of the developer 4, and the volume of the developer 4 is constantly detected. An electrical signal is sent to the toner replenishing section to operate the toner replenishing roll 7 and replenish the toner 10. That is, the volume of the developer 4 changes depending on the toner concentration,
When the toner concentration increases, the volume increases, and conversely, when the toner concentration decreases, the volume decreases, so when the developer 4 has reached the surface of the electrostrictive vibrator 8, the toner replenishment signal is in a stopped state. When the volume of the developer 4 decreases due to toner consumption and there is no more developer 4 on the surface of the electrostrictive vibrator 8, a toner replenishment signal is issued.

The above operations are repeated, and the toner concentration of the developer is kept constant during development.

[Problems with conventional technology]

The above-mentioned developing device that detects the volume of the developer and controls the toner concentration is effective in keeping the toner concentration of the developer constant, but the electrostrictive vibrator for detecting the volume and the toner replenishment signal are This requires a power source for driving the toner replenishment roll, an electric circuit, etc., and is unavoidably expensive in terms of cost.

[Purpose of invention]

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide a developing device that has an extremely simple configuration and is capable of controlling toner density at low cost.

[Key points of the idea]

In order to achieve the above object, the present invention includes a developing hopper, a magnetic brush roll that carries and conveys the developer in the developing hopper on its surface, and a magnetic brush roll that faces the surface of the magnetic brush roll at a predetermined distance. A regulating member is provided to regulate the layer thickness of the developer carried on the surface of the magnetic brush roll, and an opening is provided at a position where toner to be replenished is accommodated and the developer blocked by the regulating member is retained. A toner hopper is provided in the opening, and a position that closes the opening as the amount of developer staying there increases, and a position where the developer is conveyed by the magnetic brush roll as the amount of developer staying there decreases. a toner replenishing roll that rotates in a driven manner and is movable between a position where toner is replenished from the toner hopper to the developing hopper, and the toner replenishing roll moves the toner from the toner hopper to the developing hopper according to the amount of developer staying therein. The present invention is characterized in that the toner concentration of the developer is kept substantially constant by controlling the supply of toner into the hopper.

[Example of idea]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 2 and 3 are block diagrams of a developing device showing an embodiment of the present invention.

In FIG. 2, a developing device is provided adjacent to a photoreceptor 1 that is rotatably provided in a clockwise direction. The developing device includes a developing hopper 12 and a toner 18 provided above the developing hopper 12 for replenishment.
Toner hopper 1 which stores the toner and has an opening at the bottom.
9, and a replenishment roll 17 which is provided in the opening and is movable into and away from the opening to replenish the toner 18 in the toner hopper 19 to the developing hopper 12. Developer 15 is in the developing hopper 12.
It has a developing sleeve 13 which is rotatably supported by the magnetic attraction force of a magnet roll 14.

The replenishment roll 17 has a cylindrical shape with a developing width, and the surface is made of porous or uneven sponge.
It is made of acrylic fiber or the like (see Figure 4 a, b).

Further, the regulating member 16 is provided at the lower opening of the toner hopper 19, and regulates the layer height of the developer 15 adhering to the developing sleeve 13.

The operation of the developing device configured as above will be explained.

The developer 15 is deposited on the surface of the developing sleeve 13 by the magnetic attraction force of the magnet roll 14, and after the layer height of the deposited developer 15 is regulated by the regulating member 16, the developer 15 is deposited on the surface of the photoreceptor 1. transported to. An electrostatic latent image corresponding to the original is formed on the surface of the photoreceptor 1 by an image exposure means (not shown).
As the developer 15 is rubbed, it is visualized by toner and development is performed. The developer 15 is applied to the photoreceptor 1
After passing through the surface, it is further conveyed by the developing sleeve 13, temporarily accumulates in front of the regulating member 16, and is stirred by the magnetic force of the magnet roll 14 and the action of the regulating member 16 and the developing sleeve 13, and the regulating member 16, the developer 15 is regulated to a constant layer height, and the developer 15 is again applied to the photoreceptor 1 by the developing sleeve 13.
transported to the surface. In this way, the developing operation is performed continuously.

Here, although the toner concentration of the developer 15 is initially at a predetermined concentration, since only the toner is consumed during development, the toner concentration gradually decreases, and along with this, it becomes necessary to replenish toner. When the toner concentration decreases, the developer 15 in front of the regulating member 16
As the amount of accumulated water decreases, the replenishment roll 17 moves downward due to its own weight and comes into contact with the developer 15 on the developing sleeve 13, and the flow of the developer 15 due to the rotation of the developing sleeve 13 and the replenishment roll are further reduced. The supply roll 17 rotates due to its own weight, and the toner 18 in the toner hopper 19 falls and is replenished (see FIG. 2).

As toner replenishment progresses, the amount of developer 15 that accumulates before the regulating member 16 also increases. As the amount of accumulated developer 15 increases, the replenishment roll 17 is gradually pushed upward, and when the amount of accumulated developer 15 reaches a certain amount, the flow of the developer 15 at the part that contacts the replenishment roll 17 stops. When the toner is used up, the toner becomes stagnant, and the rotation of the replenishing roll 17 is stopped and toner replenishment is also stopped (see FIG. 3).

As the toner is consumed again by development, the amount of developer 15 accumulated in front of the regulating member 16 begins to gradually decrease, and the supply roll 17 also gradually moves downward, causing the amount of developer 15 on the developing sleeve 13 to gradually decrease. When reaching the flow point, the supply roll 17 begins to rotate,
At the same time, toner supply is also started. By repeating the above operations, the toner concentration of the developer 15 can be maintained within a certain range.

That is, toner is replenished by rotating the replenishment roll 17 according to the amount of developer 15 adhering to the developing sleeve 13, that is, using the amount of developer 15 accumulated in front of the regulating member 16 and the flow at that time. , controls the toner density of the developer 15.

[Effect of idea]

As described above in detail, the developing device of the present invention can control the toner concentration of the developer with an extremely simple and inexpensive configuration.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional dry two-component type developing device, Figs. 2 and 3 are block diagrams of a developing device showing an embodiment of the present invention, and Figs. 4 a and b are external views of the supply roll. FIG. 1... Photoreceptor, 2, 13... Developing sleeve,
3, 14... Magnet roll, 4, 15... Developer, 5, 12... Development hopper, 6... Stirring roll, 7... Toner supply roll, 8... Electrostrictive vibrator, 9, 16... ...Regulating member, 10, 18... Toner, 17... Supply roll, 19... Toner hopper.

Claims (1)

[Scope of utility model registration request] A developing hopper, a magnetic brush roll that carries and conveys the developer in the developing hopper on its surface, and a magnetic brush roll that is disposed facing the surface of the magnetic brush roll with a predetermined interval and carried on the surface of the magnetic brush roll. a regulating member that regulates the layer thickness of the developer; a toner hopper that contains toner to be replenished and has an opening at a position where the developer blocked by the regulating member is retained; As the amount of developer increases, the opening is closed, and as the amount of developer remaining decreases, the flow of developer carried by the magnetic brush roll rotates and the toner is transferred from the toner hopper into the developer hopper. a toner replenishment roll that is movable between a replenishing position and a replenishing position, and the toner replenishment roll controls the replenishment of toner from the toner hopper into the developer hopper according to the amount of the staying developer. A developing device characterized by keeping the toner concentration of the developer substantially constant.