JPS60115972A - Developing device of copying machine - Google Patents

Abstract

PURPOSE:To start preliminary development from the optimum position high in development efficiency by rendering smaller in diameter, one of a pair of magnet rolls nearer to the exposition exposed to light. CONSTITUTION:A pair of magnet rolls 4a, 4b are installed in series opposite to a photosensitive body 3, and the roll 4a nearer to an exposure point alpha is made smaller in diameter. Preliminary development can be started from the optimum point beta high in development efficiency with this roll 4a smaller in diameter without and deviation from said position, and high development performance can be exhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device for a copying machine, and more particularly to a developing device whose developing ability is enhanced by two magnetic rolls and is suitable for high-speed copying.

[Prior art]

In recent years, copying machines have become faster copying machines, and as a result, there is a demand for developing devices with high-speed development capabilities.

In response to such requests, for example, as shown in Figure 1,
Two magnet rolls (la) and (lb) having the same diameter as each other are provided facing the photoreceptor (2), and the area near the exposure irradiation point (α) on the surface of the photoreceptor (2) <(2) After preliminary development is performed using the first magnet roll (1a) provided, main development is performed using the second magnet I roll (lb) provided behind the first magnet roll (1a). There have been proposals to improve the developing ability.

By the way, in order to carry out effective development, C- must be installed on the photoreceptor (2).
) It is known that it is necessary to start development at a proper point (β) separated by a certain distance (Al) from the exposure irradiation point (α) on , since the diameter of the first magnet roll (1a) is large, the arrangement of the first magnet roll (1a) (
- The degree of freedom in the first magnet roll (1
It is difficult to arrange the first red sea bream roll (la) so that the development start position (γ) in a) coincides with the appropriate point (β), and the development start position (γ) does not match the appropriate point (β).
β) to Δ! This is a problem because areas where dark decay has a large contribution and the electrostatic latent image is weak are likely to be developed, resulting in development leakage.

[Purpose of the invention]

Therefore, an object of the present invention is to eliminate the above-mentioned problems of the prior art.More specifically, it is an object of the present invention to start the pre-Iper (1 development) from the appropriate point of development efficiency, thereby achieving high development ability. To provide a developing device for a copying machine that can exhibit the following characteristics.

[Structure of the invention]

That is, the developing device of the copying machine of the present invention is composed of a pair of photoreceptors (two magnet rolls arranged opposite to each other in parallel) and each of which has a different diameter. Of these, the 17th magnet roll provided near the exposure irradiation point of the photoconductor (-) is smaller in diameter than the 2nd magnet roll provided further away, and the photoreceptor of the first magnet roll is Since it can be placed at an appropriate point separated by a predetermined distance from the exposure irradiation point on the body, preliminary development can be performed at an appropriate point with high development efficiency.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a developing device for a copying machine according to the present invention will be described based on embodiments shown in the accompanying drawings.

FIG. 2 shows a developing device according to the present invention. 4a) (4
b), and these magnetic rolls (Aa) (4b
), the first one closest to the exposure irradiation area (α) of the photoreceptor (3)
The mag A roll (4a) is formed to have a smaller diameter than the second red sea bream roll (4b) located further away from this.

The first magnet roll (4a) and the second magnet roll (4b) are configured so that their outer peripheral surfaces rotate twice in the opposite direction to the photoreceptor (3). Inside (second), a plurality of magnets (7) are provided so that the developer (5) forms a magnetic brush (6) by magnetic force. (4b) to the first magnet roll (4
In order to convey the developer (5) to (a), these first and second magnet rolls (4a), (4b) (two upper conveyance magnets (7a), (7b) They are arranged so that the different polarity sides face each other, and the second magnetic roll (4a) is connected from the first magnetic roll (4a) to the second magnetic roll (4a).
A downward conveyance magnet (7c) provided on the first magnet roll (4a) and the second magnet roll (4b) for conveying the developer (5) to b).

(7d) is similarly arranged so that the different polarity sides face each other.

Incidentally, the first red sea bream roll (4a) i2 is provided with a trimmer (8) for adjusting the spikes of the magnetic brush (6) formed by the developer (5) to a predetermined length, ” Near the first magnet roll (4a), a developer (5) is directed toward the second magnet roll (4b).
) is provided, and each of these) 11 is provided.
A housing (10) is provided to prevent the developer (5) from scattering outside the S material (secondly, into the machine).

Therefore, according to Embodiment 1 (2), when the copy button (not shown) is operated, the developer (5) deposited on the bottom of the housing (10) is pierced by the paddle (9) (2). The developer (5) that is supplied with the second magnet roll (4b) and forms the surface magnetic brush (6b) is
The developer (5) is transferred diagonally upward from the upper transport magnet (7b) by the rotational force of the second magnet roll (second) to the vicinity of the upper transport magnet (7b). in,
In addition, since the upper transport magnet (7a) (2) in the first magnet roll (4a) (2) provided at a close distance (d2) (2) is strongly magnetically attracted, the first red sea bream, The developer (5) thus conveyed onto the first flat roll (4a) is transferred to the magnetic blank (6a) again on this surface. The length of the first magnet roll (4) is adjusted by the trimmer (8).
・a) The exposure irradiation point (
α) to the proper point (I9) where the ratio [!1] is reached at a specified distance (! ratio [1]) and after the fine development reaches I1, it reaches the downward conveyance magnet (7c).Here, This developer (5) is
It is conveyed toward the second magnet roll (4b) while being attracted by the downward conveyance magnet (7d) provided on the second magnet roll (4b), and while forming a magnetic brush (6b) on the surface of the second magnet roll (4b). -F direction, the photoreceptor (
3) Rub the surface again 1. Perform the image of the Lord J'lJ. The developer (5) that has reached the terminal end magnet (7e) provided with the second magnet roll (4b) then falls and accumulates on the bottom of the lower housing (5). The developer (5) is blended with the toner supplied as appropriate from the toner supply device, and the preliminary development and main development are repeated again.In this way, the developer (5) flows from the bottom of the housing (lO) to the paddle (9) and the third toner. The second magnet roll (4b), the first red magnet roll (4a), the second magnet roll (4b), and then the second magnet roll (4b) are reliably conveyed through the cycle to the bottom of the transporter (10). Since preliminary development is performed from above the appropriate point (β) using the magnet roll (4a), high developing power can be stably exhibited.

According to this embodiment (2), the conveyance distance (d2) when the developer (5) is conveyed from the first magnet roll (4b) to the first magnet roll (4a) (2) is different from that of the conventional type shown in FIG. Since the conveyance distance is shorter than the conveyance distance (d+)C at , and the conveyance is oblique, there is less influence of gravity, etc., and reliable conveyance can be achieved.

〔Effect of the invention〕

Since the developing device of the copying machine according to the present invention has the above-mentioned configuration, the red sea bream roll closer to the exposure irradiation point has a smaller diameter, so that it is separated from the exposure irradiation point by a predetermined distance. Preliminary development can be performed at an appropriate location (2), high developing power can be exhibited, and a space-efficient developing device can be provided.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a developing device of a conventionally used copying machine, and FIG. 2 is a schematic sectional view of a developing device of a copying machine according to the present invention. Description of symbols (la) (4a)...First magnet roll (1b) (4b)...Second magnet roll (
2++3+...Photoreceptor (5)...Developer (6)...Magnetic brush (7)...
・Magnet (α)...Exposure irradiation point (β)...
... Appropriate point patent applicant Fuji Xerox Co., Ltd. Agent Tomohiro Nakamura Patent Attorney Katsuo Naruse

Claims (1)

[Claims] A pair of magnet rolls are arranged in parallel to face the photoreceptor. A developing device for a copying machine characterized by having a roll diameter (two differences) so that the diameter is smaller than that of a second magnet roll provided at a distance.