JP2992370B2 - 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 section having a developer carrier opposed to a latent image carrier, a toner hopper section storing toner to be supplied to the developing section, and a toner hopper section. An opening of a small hole formed and through which the toner to be supplied to the developing unit passes, and an agitator for stirring the toner in the toner hopper and supplying the toner to the developing unit through the opening. The present invention relates to a developing device provided.

[0002]

2. Description of the Related Art A developing device of the above type is well known and is used in an image forming apparatus such as a copying machine and a printer.
In a developing device of this type, a device using a toner cartridge as a toner hopper is also known.
When the toner cartridge is stored, the toner may aggregate and lose its fluidity. When the toner cartridge in which the toner is aggregated is set in the developing device and started to be used, the starting torque becomes extremely large when the agitator is to be rotated. For this reason, a large load is applied to the agitator, the joint with the drive unit, and the drive unit itself, and these parts may be damaged.

Conventionally, this problem has been dealt with firstly by devising the shape of the agitator, secondly by increasing the strength, and thirdly by having the user shake well before mounting.

[0004]

In this case, if the third user is thoroughly urged to shake well before mounting, the above-mentioned problem can be almost completely solved. Nor can we expect this work to be 100% done. In addition, there is a limit in devising the shape of the first agitator because the agitator is used for supplying toner, and when the agitator is disposable with the second strength being increased, the material cost is reduced. Limited by cost. Furthermore, even if the strength is increased, there is a problem that the capability of the drive motor needs to be reviewed.

In a developing device in which an agitator is slidably in contact with an opening of a toner hopper portion such as a toner cartridge to supply toner to a developing portion, when the agitator is rotated to supply toner, an elastic member at the tip of the agitator is used. Is pressed against the inner wall of the cartridge body, so that the drive torque of the agitator is unavoidably increased to some extent.

[0006] The present invention solves the above-mentioned conventional problems,
It is an object of the present invention to provide a developing device that can reduce the starting torque of the agitator when setting a toner cartridge and the driving torque of the agitator when supplying toner.

[0007]

In order to achieve this object, the present invention provides a developing unit having a developer carrier opposed to a latent image carrier, and a toner storing toner to be supplied to the developing unit. A hopper portion, and an opening formed in the toner hopper portion and having a small hole through which the toner to be supplied to the developing portion passes. The toner hopper portion is configured to stir the toner, and the opening portion is formed in the developing portion. A developing device provided with an agitator for replenishing toner via the toner agitator, the agitator including a toner agitating member for agitating the toner, and a toner conveying member provided at a tip end side of the toner stirring member. The toner conveying member is a brush provided so as to be in sliding contact with the opening.

[0008]

FIG. 1 is an overall schematic view showing an example of a developing device according to the present invention. In FIG. 1, this embodiment is a developing device 7 using a two-component developer, and a developing roller 16 disposed inside a developing device main body 7a so as to face a photoconductor 4 as a latent image carrier, A developing unit 15 having a toner supply roller 17 for supplying toner to the developing roller 16 and a doctor for regulating a layer thickness of a magnetic brush formed on the developing roller 16
And a toner cartridge 18 serving as a toner hopper for storing toner. In the toner cartridge 18, a cartridge body 20 storing the toner,
An opening 19 communicating with the developing unit 15 formed in the cartridge main body 20 and an agitator 21 for stirring the stored toner and supplying the toner to the developing unit 15 are provided.

The toner cartridge 18 is separate from the developing device main body casing 7a, and the toner cartridge 18 is filled with toner in an assembly line in advance. Therefore, even in the developing device 7 using the two-component developer, the toner can be easily filled, which is advantageous in that the toner is not scattered as compared with the method of supplying the toner to the toner hopper of the developing device main body.

As shown in FIG. 3, the developing device 7 has an opening 19 that communicates with the developing portion 15 of the toner cartridge 18.
Are provided with small holes 32, and small holes 32 are formed in the small hole plate 31 at appropriate intervals. Then, a toner conveying member of the agitator 21 described later is slidably brought into contact with the small hole plate 31 to supply toner to the developing unit 15.

The agitator 21 includes a toner transport brush 33 serving as a toner transport member that contributes to transport the toner.
And a toner stirring plate 29 as a toner stirring member that contributes to stirring of the toner, and the toner is conveyed by the elastic force of the brush. As the toner conveying brush 33, for example, a brush material SUS31
6, a wire diameter of 12 μm, a flocking pitch of 0.2 pitch, and a flocking density of 100 F / mm are used.

The developing device 7 having such a configuration is advantageous in terms of image quality and torque as compared with the developing device using a polyester film for the toner transport plate of the agitator proposed by the applicant of the present invention. The differences will be explained in detail from experimental data.

As shown in FIGS. 1 and 2, the developing device 7 uses a polyester film having a thickness of 0.1 mm as the small hole plate 31, and a small hole 32 having a diameter of 0.7 mm is formed in the small hole plate 31. Thirty-three are formed. Toner transport brush 33
Is the above brush material SUS316, element wire diameter 12 μm,
The experiment was conducted using a hair transplant pitch of 0.2 pitch and a hair transplant density of 100 F / mm, and using a 0.075 mm-thick polyester film as the toner transport plate.

In an apparatus using a toner transport plate, a polyester film is formed between the inner wall of the cartridge body 20 and the small hole plate 3.
Since the toner was replenished by being rubbed inside 1, the toner was supplied to the developing unit 15 in an agglomerated state and accumulated in the C portion of the developing unit 15. As a result, the developer and the toner are not sufficiently mixed, and the toner concentration on the sleeve of the developing roller 16 does not increase even when the toner is supplied. That is, as shown by D in the graph of FIG. 3, the toner density G was lower than the toner density G calculated from the toner replenishment amount, and the toner tracking ability was deteriorated. Further, the toner that has been agglomerated must be finely classified before the developer is triboelectrically charged, so that the charging ability is low, and toner scattering and background contamination are likely to occur.

On the other hand, in the apparatus using the toner conveying brush 33, the replenished toner is finely classified, and is repelled and dropped onto the stirring roller 34.
The toner density is close to the calculated toner density G as shown by E in the graph of FIG. Furthermore, since the replenishment toner is finely classified without toner aggregation, the toner is sufficiently charged by friction of the developer and has a charging ability, so that toner scattering and background contamination do not occur. In addition, the toner in the toner cartridge 18 is not agitated by the toner transport brush 33,
9, the toner can be surely stirred.

Further, comparing the two with respect to the torque,
As shown in the graph of FIG. 4, the toner transport plate has a strong stiffness, and thus has a weight of 1.7 kgfcm, whereas the toner transport brush 33 has a weight of 1.0 kgfcm. Therefore, a small motor can be used for driving the agitator, which is effective for reducing the size and labor of the apparatus.

In this embodiment, the developing device using the toner cartridge in the toner hopper portion has been described. However, the present invention can also be applied to an apparatus having no toner cartridge and incorporating the toner hopper portion in the developing device main body.

[0018]

According to the above construction, even if the agitator is brought into sliding contact with the opening required for toner transport, the transport member at the tip of the agitator is formed in a brush shape, so that torque during rotation of the agitator can be reduced. It can also prevent toner scattering and background contamination. Further, since the stirring of the toner in the toner cartridge is performed not by the brush but by the toner stirring member, the toner can be surely stirred.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram showing an example of a developing device according to the present invention.

FIG. 2 is a perspective view showing an opening of the toner cartridge.

FIG. 3 is a graph showing the toner densities of the developing device of the present invention and the conventional developing device.

FIG. 4 is a graph showing the magnitude of torque in the developing device according to the present invention and the conventional developing device.

[Explanation of symbols]

 4 Photoconductor 7 Developing Device 18 Toner Cartridge 21 Agitator 29 Toner Stirring Plate 32 Small Hole 33 Toner Conveying Brush

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-181769 (JP, A) JP-A-2-116875 (JP, A) Fully open 48-37646 (JP, U) Fully open 49-1 96953 (JP, U) JP 42-16598 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 15/08-15/09

Claims (1)

(57) [Claims] A developing unit having a developer carrier opposed to the latent image carrier; a toner hopper unit storing toner to be supplied to the developing unit; and a developing unit formed on the toner hopper unit. And a toner agitator that stirs the toner in the toner hopper and replenishes the toner through the opening to the developing unit. Wherein the agitator includes a toner stirring member for stirring toner, and a toner conveying member provided at a tip end side of the toner stirring member, and the toner conveying member is provided so as to slide on the opening. A developing brush.