JP2699968B2 - Copier - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of transporting a developer between a photoreceptor and a plurality of developing rolls while forming a magnetic brush on the surface of each developing roll. The present invention relates to a copying machine using a developing device for performing development. 2. Description of the Related Art Conventionally, as a developing device in a copying machine of this kind, 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. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate the need for the developer to be conveyed to the back side of the developing roll and to reduce the number of magnets incorporated in the developing roll in the developing device in the whisper mode. Accordingly, it is an object of the present invention to provide a copying machine having a developing device in which the diameter of the developing roll is reduced and a large number of developing rolls are arranged on the photosensitive member so that the developing performance can be improved. That is, according to the present invention, a plurality of developing rolls in which a magnet is fixedly arranged and all rotate in the same direction as a photoreceptor, and a developer is scooped up on the developing rolls And a developer transfer magnet roll disposed between the developing roll and the paddle and having a magnet fixedly disposed therein, and supplied from the paddle through the magnet roll. A developing device in which a developing agent descends sequentially between a photoreceptor and a plurality of developing rolls while forming a magnetic brush on the surface of each developing roll. Of the developer roll on the uppermost side of the developing roll and the portion of the developer conveying magnet roll adjacent to the rear side of the developing roll. The magnetic poles of the magnets facing each other and having different magnetic poles are disposed, and the magnetic pole of the magnet disposed at the lowermost side of the upper developing roll among the plurality of developing rolls is disposed at the upper side. A magnet arranged at a position shifted to the photoconductor side from the lowermost point of the developing roll, and arranged at an uppermost position shifted to the photoconductor side from the uppermost point of the adjacent lower developing roll and at the most upstream side in the rotation direction. The relationship between the magnetic poles and the magnetic poles that are initially arranged downstream of the magnetic poles and are different
This is a copier disposed so as to face a 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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a copying machine according to the present invention will be described in detail with reference to an embodiment 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. [0013] Then, the developer 3 scooped up by the paddle 4 is conveyed by the developer conveying magnet roll 5 to the magnet N ₃ located on the rear upper portion of the upper developing roller 2a, and then above the developing roll 2a The magnets S ₂ , N ₂ , S ₁ , N ₁ provided on the developing roller 2 b and the magnets N ₂ ,
It is guided by S ₂ , N ₁ , S ₁ , and N ₃ and descends between the photoreceptor 1 and each of the developing rolls 2a and 2b. At this time, the developer 3
Is dropped off from the surface of the roll 2a after passing through the magnet N1 disposed on the upstream side shifted from the lowermost point of the upper developing roll 2a toward the photoconductor _1, and hardly falls to the rear side of the roll. . And the developer 3 that falls
Denotes a photosensitive member higher than the uppermost point on the lower developing roll 2b.
Magnet N arranged on the most upstream side at the upper side shifted to the side
₂ and to drop to a position between the different magnetic <br/> Tsu preparative S ₂ of magnetic poles is first disposed on the downstream side, the upper developing roller 2b by the magnetic force lines due to its two magnets N _2, S ₂ It is transported smoothly in sequence. 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. 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 an explanatory sectional 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; [Description of Signs] 1 ... Photoconductor, 2a, 2b ... Developing roll, 3 ... Developer, 4
... Paddle, 5 ... Magnet roll for transporting developer.

Claims (1)

(57) [Claims] A magnet is fixedly disposed inside, a plurality of developing rolls all rotating in the same direction as the photoconductor, a paddle for scooping and supplying the developer to the developing roll, and a paddle disposed between the developing roll and the paddle. And a developer transfer magnet roll in which a magnet is fixedly disposed. The developer supplied from the paddle through the magnet roll passes between the photoconductor and the plurality of development rolls. What is claimed is: 1. A copying machine having a developing device in which development is performed by sequentially descending while forming a magnetic brush on a surface, wherein a back portion of an uppermost developing roll among a plurality of developing rolls of the developing device and the developing roll The magnetic poles of the magnet which are opposite to each other and have different magnetic poles are arranged at the portion of the developer conveying magnet roll close to the back surface of the magnet. In addition, the magnetic pole of the magnet disposed at the lowermost side of the upper developing roll among the plurality of developing rolls is disposed at a position shifted to the photoconductor side from the lowermost point of the upper developing roll. And the uppermost point of the adjacent lower developing roll
At a position between the magnetic pole of the magnet arranged on the most upstream side in the rotational direction on the upper side shifted to the photoconductor side and the magnetic pole of the magnet which is first arranged downstream of the magnetic pole and has a different relationship between the magnetic poles A copying machine characterized by being arranged to face each other.