JPS6356987B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fur brush type developing device used, for example, in electronic copying machines, electronic printing devices, and the like.

Recently, an economical fur brush type developing device that does not use a carrier (iron powder) has been proposed for electronic copying machines and the like. As shown in Fig. 1, this type of developing device has a long hair body a.
One method uses a fur brush developing roller b to stroke the surface of the photoconductor c, and the other uses a short bristles d as fur and uses a core e as shown in FIG.
There is a method of developing using a fur brush developing roller f which is made soft so that the portion in contact with the surface of the photoreceptor c is bent. However, in the former fur brush developing roller b having long bristles a, the bristles a get worn out after long-term use, the developing bias for preventing fogging is ineffective, and excess toner is released as the fur brush developing roller b rotates. A smoke state is formed, and the uncharged toner causes significant fogging. In order to prevent this, a fog prevention roller g must be added, and the structure becomes complicated.

On the other hand, the fur brush developing roller f which uses the latter short bristles d and has a soft core e has a developing bias voltage i for preventing fogging by fixing the core e and the bristles d with a conductive adhesive h. It becomes possible to apply the voltage. However, the conditions for the antifogging developing bias voltage i to work effectively require that a certain amount of toner be supplied, and that the toner held by the bristles d is sufficiently charged by friction with the bristles d. Must-have. When the amount of toner is large, there is a relationship with the density of the bristles d, but the chance of contact between the toner and the bristles d decreases, the amount of uncharged toner increases, and fogging occurs. Conversely, if the amount of toner is small, the density of development will decrease. Therefore, it is necessary to arrange the toner charging roller j and the toner supply roller k near the fur brush developing roller f, which makes the structure complicated and also increases the rotational speed between the rollers f, j, and k. However, the drawback is that a powerful motor is required, which increases the price.

The present invention has been made based on the above circumstances, and an object of the present invention is to sufficiently charge the toner supplied to the fur brush developing roller with a relatively simple structure, thereby eliminating fog caused by uncharged toner. It is an object of the present invention to provide a fur brush type developing device which can prevent the above problems and obtain a good developing state.

Hereinafter, one embodiment of the present invention will be described based on FIGS. 3 and 4. In FIG. 3, 1 is a developing container communicating with a toner storage box (hopper) 2, and a fur brush developing roller 4 whose part is in contact with the surface of the photoreceptor 3 is housed in the developing container 1. . This fur brush developing roller 4 has a structure in which short bristles 7 are fixed as fur to a soft core (elastic body) 5 via a conductive adhesive 6.
A developing bias voltage 8 for preventing fogging is applied.

Further, a toner replenishment roller 9 is provided at the toner replenishment port of the toner storage box 2, and the toner 10 in the toner storage box 2 is supplied into the developer container 1 as the toner replenishment roller 9 rotates. It's getting old.

Further, at the bottom of the inner wall surface of the developing container 1, a toner made of a substance charged with a polarity opposite to the charged polarity, such as a tetrafluoroethylene (commonly known as Teflon) film, is placed in close proximity to or in contact with the bristles 7 of the fur brush developing roller 4. A forced charging member 11 is attached.

Thus, the toner 10 supplied into the developer container 1 by the toner replenishment roller 9 is conveyed between the fur brush developing roller 4 and the toner forced charging member 11, thereby maintaining the amount of charge required during development. This means that the fogging phenomenon caused by poorly charged toner can be reliably prevented.

FIG. 4 shows the relationship between the time during which the toner is in contact with the toner forced charging member 1 made of tetrafluoroethylene film, that is, the length of the toner forced charging member 11, and the amount of charge on the toner 10 measured by the cyclone measurement method. However, it can be seen that the amount of charge is comparable to the amount of charge (indicated by an x in the figure) of the toner used in two-component development with an iron powder carrier, which is conventionally used in electrophotography. Although the amount of charge varies depending on the characteristics of the toner 10 itself, this comparison was carried out using Toshiba D-100P at 20° C. and 60% PH.

In the above-described embodiment, a tetrafluoroethylene film was used as the toner forced charging member 11, but it may be formed by vapor deposition, coating, or the like. Furthermore, even when a sheet covered with rayon fiber was used instead of tetrafluoroethylene, almost the same results were obtained, although the rise in the amount of charge was slightly worse than that for tetrafluoroethylene.

In addition, it goes without saying that the present invention can be modified in various ways without departing from the gist of the invention.

As explained above, according to the present invention, although the structure is relatively simple and inexpensive, it is possible to sufficiently charge the toner supplied to the fur brush developing roller, and it is possible to sufficiently charge the toner supplied to the fur brush developing roller, and to achieve a good result without fogging due to partially charged toner. Can be developed. In addition, since a film-like toner forcible charging member is used, the rotational torque of the fur brush developing roller can be made smaller than when charging is performed using a cloth or a brush densely seeded with fibers, and a compact motor can be used to achieve downsizing and cost reduction.

Further, the hairs do not fall out and adhere to the photoreceptor, causing image defects. Furthermore, toner does not accumulate and a stable charging effect can be maintained over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a conventional fur brush type developing device, FIG. 2 is a schematic block diagram of a different conventional fur brush type developing device, and FIG. 3 is a schematic diagram showing an embodiment of the developing device of the present invention. The configuration diagram and FIG. 4 are explanatory diagrams showing the relationship between the toner charge amount and the length of the toner forced charging member. DESCRIPTION OF SYMBOLS 1... Developer container, 4... Fur brush developing roller, 10... Toner, 11... Toner forced charging member.

Claims (1)

[Claims] 1. A developing container containing a fur brush developing roller made of flocked short fibers, characterized in that a film-like toner forced charging member is provided on the inner wall of the developing container with which the fur of the fur brush developing roller approaches or contacts. A developing device.