JPH09106188A - Copying machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the developing performance by arranging a magnet roll for developer conveyance, having magnets arranged fixedly internally, between a developing roll and a paddle. SOLUTION: The magnet roll 5 for developer conveyance is arranged which carries a developer 3 to above the developing roll 2a. The developer 3 which is scooped up by the paddle 4 is carried to a magnet N3 positioned above and behind the developing roll 2a. Thus, the developer 3 is supplied directly to the back part of the developing roll 2a with the magnetic force between the magnets in opposite-polarity relation, so the need for the back conveyance of the developer 3 by plural developing rolls 2a and 2b is eliminated and it is not necessary to arrange the magnets behind the developing rolls 2a and 2b; and the diameters of the developing rolls 2a and 2b are designed small and 3-5 developing rolls can be arranged at the 3-o'clock and 9-o'clock positions of a photoreceptor 1, thereby improving the developing performance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine using a developing device for carrying a developer between a photoconductor and a plurality of developing rolls while forming a magnetic brush on the surface of each developing roll for developing. It is about.

[0002]

2. Description of the Related Art Conventionally, as a developing device in a copying machine of this type, as shown in FIGS.
The set positions of the developing rolls 2a and 2b are the positions of 3 o'clock or 9 o'clock of the clock with respect to the photoconductor 1 and the developing rolls 2a and 2b.
A developing device in a so-called "with mode" in which the developer rotates in the same direction as the photoreceptor 1 performs a flow of the developer 3 conveyed while forming a magnetic brush on the surfaces of the developing rolls 2a and 2b. 3a is less disturbed and its transport is smoother, the developer is less deteriorated by the collision of the developers 3 and the like, and there is no development of the back surface dirt.
In addition, it has features such as uniform reproduction of a wide area image.

However, in this type of developing device, the developer 3 picked up by the paddle 4 in the device rises on the back surface of the developing rolls 2a and 2b, and wraps around above the developing roll 2a located above. Photoreceptor 1
And between the developing rolls 2a and 2b. For this reason, the transportability of the developer 3 is poor, and it is difficult to select the magnetic pole and magnetic force of the developing rolls 2a and 2b or to select the interval between the two developing rolls 2a and 2b. In addition, since the developer 3 is conveyed to the back of the developing rolls 2a and 2b, the number of magnets incorporated in the developing rolls 2a and 2b increases. For example, as shown in FIG. Seven magnets are required, and eight magnets are required for the lower developing roll 2b.
2b was required, and as a result, it was difficult to improve the developing performance by arranging a large number of developing rolls at the 3 o'clock or 9 o'clock position of the photoconductor 1.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to develop a with-mode developing device by eliminating the backside conveyance of the developing roll for the developer and reducing the number of magnets incorporated in the developing roll. It is an object of the present invention to provide a copying machine having a developing device in which the roll has a small diameter and a large number of developing rolls are arranged on the photosensitive member to improve the developing performance.

[0005]

That is, according to the present invention, a plurality of developing rolls in which magnets are fixedly arranged and which are all rotated in the same direction as the photoconductor, and the developer is scooped up and supplied to the developing rolls. The developer, which is provided between the paddle and the developing roll and the paddle, and in which the magnet is fixedly arranged, for conveying the developer, the developer being supplied from the paddle through the magnet roll. Is a copying machine having a developing device in which development is performed by sequentially descending between a photoconductor and a plurality of developing rolls while forming a magnetic brush on the surface of each developing roll. Of the uppermost developing roll and the part of the developer-conveying magnet roll close to the rear face of the developing roll, facing each other between the two parts. In addition, the magnetic poles of the magnets having different magnetic poles are arranged, and the magnetic pole of the magnet arranged at the lowermost side of the upper developing roll among the plurality of developing rolls is the uppermost developing roller. The magnetic pole of the magnet, which is arranged at a position deviating from the lower point to the photoconductor side and is arranged on the most upstream side in the rotation direction on the upper side of the adjacent lower developing roll, and is first arranged on the downstream side of the magnetic pole The copying machine has a developing device disposed so as to face the position between the magnetic pole of the magnet.

According to this copying machine, the magnet roll in the developing device applies the developer to the developing roll set at the top of the plurality of developing rolls. Since the sheet is directly conveyed in this way, the back side conveyance by a plurality of developing rolls can be eliminated, and the magnet on the back side of each developing roll can be omitted.

Further, in the above-mentioned developing device, the magnet on the back side of the developing roll can be omitted, and the difficulty in selecting a magnetic pole or the like is reduced. Since the developer is arranged in a specific positional relationship, the developer hardly falls between the photoreceptor and the plurality of developing rolls to the back side of the developing roll, and a magnetic brush is formed on the surface of each developing roll. The developer is conveyed smoothly and sequentially, so that the developing performance in the case where a plurality of developing rolls are provided can be surely improved.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The copying machine of the present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings.

FIG. 3 and FIG. 4 show a developing device in a copying machine according to an embodiment of the present invention. In this developing device, a pair of upper and lower developing rolls 2a and 2b are disposed at 3 o'clock of the timepiece of the photoreceptor 1, similarly to the conventional developing device shown in FIG. Both the developing rolls 2a and 2b rotate in the same direction as the photoconductor 1, and the developer 3 wraps around above the upper developing roll 2a, and a magnetic brush is formed on the surfaces of the photoconductor 1 and the developing rolls 2a and 2b. A developing device of a so-called whisper mode (with mode) for performing development while descending while forming, and a paddle 4 for scooping up the upper developing roll 2a and the developer 3 and supplying them to the respective developing rolls 2a and 2b. Between them, there is provided a developer transport magnet roll 5 for transporting the developer 3 picked up by the paddle 4 to an upper portion of the upper development roll 2a.

The position of the developer transported by the developer transport magnet roll 5 with respect to the upper developer roll is preferably the upper position of the upper developer roll 2a as shown in this embodiment, but is not limited to this.

In this embodiment, as shown in FIG. 4, the magnet incorporated in the magnet roll 5 for transporting the developer is a portion of the developing roll 2a which is close to the back of the developing roll 2a on the side of the magnet roll 5 as shown in FIG. N over
Are two arranged in the order of ₁ → S _1. As shown in FIG. 4, the magnet incorporated in each of the developing rolls 2a and 2b is N ₃ from the upper rear surface on the developer conveying magnet 5 side to the lower front surface on the photoconductor 1 side for the upper developing roll 2a. The five developing rolls 2b are arranged in the order of → S ₂ → N ₂ → S ₁ → N ₁ , and N ₂ → S ₂ →
Five are arranged in the order of N ₁ → S ₁ → N ₃ .

In this embodiment, one magnetic pole S ₁ of the magnet in the developer conveying magnet roll 5 is mutually connected to one magnetic pole N ₃ of the magnet disposed on the upper rear surface of the upper developing roll 2a. They are arranged so as to face each other and have a relationship of different magnetic poles. Further, a magnet (N ₁ ) disposed at the lowermost part of the upper developing roll 2a
Is disposed at a position shifted to the photosensitive member 1 side from the lowermost point of the developing roll 2a, and the uppermost magnet (N) disposed at the uppermost side of the adjacent lower developing roll 2b.
₂ ) and the next upper magnet (S ₂ ) provided below the magnet (N ₂ ) on the photoconductor 1 side.

Then, it is scooped up by the paddle 4.
The developer 3 thus obtained is a magnet roll for carrying the developer.
5 is located above the rear surface of the upper developing roll 2a.
Magnet N_ThreeTo the upper development roll
Each magnet S provided on 2a _Two, N_Two, S₁, N₁as well as
Each magnet N provided on the lower developing roll 2b_Two,
S _Two, N₁, S₁, N_ThreeGuided to the photoconductor 1 and each development
It descends between the rolls 2a and 2b. At this time, the developer 3
Is the photoconductor more than the lowest point in the upper developing roll 2a.
Magnet N arranged on the upstream side deviated to the 1 side₁Go through
Later, it fell off the surface of the roll 2a and fell to the back side of the roll.
Almost never. Then, the developer 3 that falls is
Arranged on the most upstream side of the upper side of the lower developing roll 2b
Magnet N_TwoAnd first placed downstream of
Magnet S_TwoSince it falls to a position between
Gunet N_Two, S_TwoDeveloping roll 2b
It is transported smoothly over the top.

Therefore, according to this embodiment, as is apparent from a comparison between FIG. 1 and FIG. 3, there is no need to transport the developer 3 to the back of each of the developing rolls 2a and 2b. 4 as is apparent from the comparison between FIG., each developing roller 2a, the rear side of the 2b, i.e., in the developing roller 2b and between the lower the magnet N ₃ and N ₁ above the developing roller 2a in FIG. 4 Magnets N ₂ and N ₃
And the number of magnets that need to be provided on each of the developing rolls 2a and 2b is reduced.

[0015]

As described above, according to the copying machine of the present invention,
Between the developing roll in the developing device and a paddle for supplying a developer to the developing roll, a developer transport magnet roll in which a magnet having a specific magnetic pole is fixedly provided is provided, and the developing roller set at the uppermost position is provided. Since the developer is directly supplied to the back of the roll by the magnetic force between the magnets having different magnetic poles, there is no need to transport the back of the developer by using multiple developing rolls. improves.

Further, since the developer is no longer conveyed on the back side of the developing roll, it is not necessary to dispose a magnet on the back side of each developing roll, and the diameter of the developing roll is designed to be small. Or 3 to 9 o'clock
As many as five developing rolls can be provided, and the developing performance can be improved. In addition, since the magnet is arranged in a specific positional relationship between the upper developing roll and the lower developing roll among the plurality of developing rolls, the magnet is supplied via the developer conveying magnet roll. The developer is transported smoothly and almost without falling to the back side between the photoreceptor and the plurality of developing rolls, thereby reliably improving the developing performance when the plurality of developing rolls are arranged. it can. By eliminating the need for transporting the back surface and improving the developer transportability, it is possible to reduce the difficulty in selecting the magnetic pole and magnetic force of each developing roll and selecting the interval between the developing rolls. it can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional explanatory view showing a conventional developing device.

FIG. 2 is an explanatory diagram showing an arrangement of magnets in each developing roll of FIG.

FIG. 3 is an explanatory sectional view showing a developing device of the copying machine according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an arrangement of magnets in each developing roll of FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoconductor, 2a, 2b ... Developing roll, 3 ... Developer, 4
... Paddle, 5 ... Magnet roll for transporting developer.

Claims (1)

[Claims] 1. A plurality of developing rolls, each having a magnet fixedly arranged therein, which rotates in the same direction as the photosensitive member, a paddle for picking up and supplying the developer to the developing rolls, and the developing roll and the paddle. And a developer-conveying magnet roll in which a magnet is fixedly arranged inside, and the developer supplied from the paddle through the magnet roll is a photosensitive member and a plurality of developing rolls. A copying machine having a developing device for performing development by sequentially descending while forming a magnetic brush on the surface of each developing roll, wherein the back surface of the uppermost developing roll of the plurality of developing rolls of the developing device is used. And a portion of the developer-conveying magnet roll close to the back surface of the developing roll, the magnets facing each other and having different magnetic poles. Of the plurality of developing rolls, the magnetic pole of the magnet disposed at the lowermost side of the upper developing roll is located closer to the photoconductor than the lowest point of the upper developing roll. Between the magnetic pole of the magnet, which is disposed at the shifted position and is disposed on the uppermost side in the rotation direction on the upper side of the adjacent lower developing roll, and the magnetic pole of the magnet which is first disposed downstream of the magnetic pole. A copying machine characterized by being arranged so as to face the position of.