JPS641042B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnet roll used in a developing device, a cleaning device, etc. of an electrophotographic copying device or an electrostatic recording device.

Generally, in a magnetic brush developing device, a magnet roll is used as a magnetic brush forming means, which is a non-magnetic cylindrical sleeve provided with a permanent magnet roll having a plurality of magnetic poles on the surface. A magnetic developer (a two-component developer consisting of an iron powder carrier and a toner, a one-component magnetic toner, etc.) is attracted and conveyed onto the sleeve by rotation of the sleeve, thereby forming a magnetic brush. By the way, as a developer conveyance method using a magnet roll, there are two methods: a sleeve rotation method in which the internal permanent magnet roll is fixed and the sleeve is rotated, and a magnet rotation method in which the sleeve is fixed and the permanent magnet roll is rotated. No. 54-30045 and Japanese Unexamined Patent Publication No. 54
A dual-rotation system in which the sleeve and the magnet roll are rotated together is known, as shown in No. 68240.

However, as shown in FIG. 1, the conventional magnet roll has side plates 4, 4' fixed to both ends of a non-magnetic cylindrical sleeve 1 (hereinafter simply referred to as sleeve).
The reduced diameter portions 2a and 2b of the rotary shaft 2 holding the permanent magnet 3 are supported through bearings 5 inserted into the side plates 4 and 4', respectively. Therefore, when the magnet roll described above is applied to a dual-rotation system, it is necessary to connect the shaft 6 provided on the side plate 4' and the rotation shaft 2 to separate drive sources. It is also possible to use only one drive source and a transmission mechanism such as gears or pulleys, but there are problems such as an increase in the number of parts and a complicated mechanism, and it is not possible to obtain such a large reduction ratio. Nakatsuta. For example, JP-A-54-126046
38527), when the sleeve and magnet are rotated in the same direction and the developer is conveyed in the opposite direction, the rotation speed of the sleeve must be approximately 1/20 or less than that of the magnet. , Conventional magnet rolls required two drive sources.

An object of the present invention is to provide a magnet roll that can be applied to both rotation systems and that provides an extremely large reduction ratio with a single drive source.

The details of the present invention will be explained below with reference to the drawings.

FIG. 2 is a longitudinal cross-sectional view of the magnet roll of the present invention, and FIG. 3 is a cross-sectional view taken along line A-A in FIG.
Parts that are the same as in the figures are designated by the same reference numerals. Side plates 4, 4'' are attached to both ends of the non-magnetic cylindrical sleeve 1, and the reduced diameter portions 2a and 2b' of the rotating shaft 2 are supported coaxially with the sleeve 1 via bearings 5 on the side plates 4 and 4'', respectively. has been done. An eccentric cam 6 is fixed to the reduced diameter portion 2b', and spur gears 7 (number of teeth Z ₂ ) and 7 (number of teeth Z ₄ ) are rotatably supported on the eccentric cam 6 coaxially therewith. A gear 9 (number of teeth Z ₁ ) that meshes with the spur gear 7 is formed on the inner surface of the protrusion 4''a of the side plate 4''. A cylindrical member 8 is supported on the reduced diameter portion 2b' via a bearing 5, and a spur gear 9' (number of teeth Z ₃ ) that meshes with the spur gear 7' is formed on the inner surface of the cylindrical member 8. It is assumed that this cylindrical member 8 is supported by a fixed part such as a developing device or a main body of a copying machine.

According to the above configuration, when the reduced diameter portion 2a of the rotating shaft 2 is rotated by a drive source (not shown), since the cylindrical member 8 is fixed, the spur gear 7' revolves while rotating. 7 also revolves while rotating in conjunction with the spur gear 7', and the spur gear 9 rotates. This rotation of the spur gear 9 causes the sleeve 1 to rotate.
Therefore, when the rotational speed of the permanent magnet 3 is N _M and the rotational speed of the sleeve 1 is N _S , the ratio i of N _S to N _M can be expressed by the following equation (1).

i=1−Z ₁・Z ₄ /Z ₂・Z ₃ ...(1) In the above equation (1), when i>0, magnet 3 and sleeve 1 rotate in the same direction, while when i<0, magnet 3 and sleeve 1 rotate in the same direction. At this time, the magnet 3 and the sleeve 1 rotate in opposite directions.

For example, in equation (1), Z ₁ = 27, Z ₂ = 21, Z ₃ =
25 and Z ₄ =19, i=+1/43.75. In other words, the magnet and sleeve rotate in the same direction,
N _S :N _M =1:43.75, resulting in an extremely large reduction ratio. Also, in equation (1), Z ₁ = 25, Z ₂ =
19, Z ₃ = 27, Z ₄ = 21, i = -1/
It becomes 42.75. That is, the magnet and the sleeve rotate in opposite directions, and N _S :N _M =1:42.75.

As described above, according to the present invention, it is possible to obtain a magnet roll which can rotate both the sleeve and the magnet using one driving source and can obtain a large reduction ratio.

[Brief explanation of drawings]

Figure 1 is a longitudinal cross-sectional view of a conventional magnet roll.
FIG. 2 is a longitudinal cross-sectional view of the magnet roll of the present invention;
FIG. 3 is a sectional view taken along the line AA in FIG. 2. 1: Non-magnetic cylindrical sleeve, 2: Rotating shaft, 3:
Permanent magnet, 4, 4', 4'': Side plate, 7, 7', 9,
9': Spur gear.

Claims (1)

[Scope of Claims] 1. A permanent magnet member having a plurality of magnetic poles on a surface held by a shaft is disposed inside a non-magnetic cylindrical sleeve, and the shaft is supported coaxially therewith at both ends of the sleeve, In a magnet roll configured such that the sleeve and the permanent magnet member can rotate relative to each other, a first spur gear (having a number of teeth) coaxial with the sleeve is provided at one end of the sleeve. Z ₁ ), and a second spur gear (number of teeth Z ₃ ) coaxial with the shaft and having a different number of teeth than the spur gear is provided on the side of the first spur gear, independently of the magnet roll. An eccentric cam is fixed to the provided fixed part, and an eccentric cam having an axis eccentric with respect to the shaft is fixed to the shaft, and a third spur gear ( A fourth spur gear (number _{of teeth Z 4 , Z 4 < Z 3 ) interlocking} with the spur gear is rotatably supported, A magnet roll characterized in that the third and fourth spur gears are respectively inscribed in the spur gears, and the sleeve is configured to rotate at a lower speed than the permanent magnet member. 2. The number of teeth of each of the spur gears is set so that i expressed as 1- _Z1・_Z4 / _Z2・_Z3 is positive, and the sleeve rotates in the same direction as the permanent magnet member. A magnet roll according to claim 1, characterized in that the magnet roll is configured as follows. 3. The number of teeth of each of the spur gears is set so that i expressed as 1- _Z1・_Z4 / _Z2・_Z3 is negative, and the sleeve rotates in the opposite direction to the permanent magnet member. A magnet roll according to claim 1, characterized in that the magnet roll is configured as follows.