JPS5933915B2 - magnetic brush phenomenon device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic plan development device used in a dry type (electrostatic transfer type) electrophotographic copying machine.

A typical example of a conventional magnetic plan developing device of this type is shown in FIG.

To explain this, 1 is a cylindrical rotatable sleeve made of non-magnetic material, inside which a main pole 2 and sub-poles 3, 4, and 5 made of fixed permanent magnets are arranged. ing. The main pole 2 is a magnetic pole for forming a magnetic brush for toner development of an electrostatic latent image formed on the surface of the photosensitive drum 6, and the permanent magnet used for this is generally used on the surface of the sleeve 1. A magnetic flux density of about 600 to 800 Gauss is used. Also,
The sub-electrodes 3, 4, and 5 are prepared by mixing a carrier made of iron powder and a toner made of carbon and resin powder into the main electrode 2.
These are magnetic poles for transporting and ejecting the component-based dry developer □, and these have a magnetic force equal to or slightly weaker than that of the main pole 2. The sleeve 1 is suitably adapted to be rotationally driven in the direction of arrow F by a rotational drive mechanism (not shown). Also,
Reference numeral 8 denotes a developer tip regulating blade, which is located on an extension of a line connecting the center of rotation of the sleeve 1 and approximately midway between the main pole 2 and the sub-pole 3, and whose tip is 4 mI from the outer peripheral surface of the sleeve 1.
They are attached to the fixed part, that is, the housing 9, at a certain distance from each other.

The housing 9 has the main pole 2, sub-poles 3, 4, 5 inside.
A blade 10 for scraping off the developer 7 remaining on the surface of the sleeve 1 after development, an impeller 11 for stirring the supplied developer 7, etc. are housed, and the upper part is for supplying the developer. A hopper 12 is provided.
The developer 7 accumulated at the bottom of the housing 9 is conveyed from the sub-pole 3 to the main pole 2 as the sleeve 1 rotates in the direction of arrow F. On the way, the developer tip regulating blade A certain amount or more of the developer is scraped off by the magnetic brush 8, and a magnetic brush 13 with tips of the same height is formed at the position of the main pole 2.

However, in such a conventional magnetic brush developing device, when it is desired to convert the developer 7 in the housing 9, the hopper 12 must be removed and the developing device main body must be turned over, which is troublesome, and the workability is reduced. was extremely bad. The present invention provides a magnetic brush developing device that solves such conventional problems. Hereinafter, the present invention will be explained based on illustrated embodiments. In FIG. 2, 20 is a sleeper made of a non-magnetic material (for example, a brass pipe with a diameter of 60 mm) similar to that explained in FIG. Rotationally driven in the direction of arrow F. Inside this sleeve 20, a cylindrical fixed body 21 made of a non-magnetic material is arranged concentrically, and on the outer circumference of the fixed body 21 there are a plurality of (five in the drawings) forming developer transport magnetic poles. ) are fixed at predetermined intervals, forming a fixed permanent magnet group.
Here, the permanent magnet 22 is arranged with the N pole facing the side surface of the photosensitive drum 27 so that the straight line connecting the N pole and the S pole is horizontal or almost horizontal. A main magnetic pole for image development is formed. The permanent magnet 22 has a magnetic flux density of 700 to 1500 on the surface of the sleep 20.
Gauss magnets are preferred, and anisotropic strontium ferrite magnets or rare earth magnets may be used, for example. On the other hand, the permanent magnet 23 forms a sub-pole for conveying the developer 28 to the main pole formed by the permanent magnet 22, which is approximately 40 degrees counterclockwise with respect to the main pole. They are arranged at angular intervals of 80 degrees. The magnetic flux density of the permanent magnet 23 on the surface of the sleeve 20 of the sub-pole is preferably 500 Gauss or more, and as the permanent magnet 23, for example, an anisotropic barium ferrite magnet or an anisotropic strontium ferrite magnet can be used. Further, the permanent magnets 24 and 25 are sub-magnetic poles that serve to attract the developer 28 stirred by the impeller 29 to the outer periphery of the sleeve 20.
It is formed by a permanent magnet 24 among them. The auxiliary magnetic poles are arranged at angular intervals of 1000 to 160 mm in the counterclockwise direction with respect to the main magnetic pole formed by the permanent magnet 22. Incidentally, the magnetic flux density on the surface of the sleeve 20 of the sub-pole formed by the permanent magnets 24 and 25 is 1
00 to about 500 Gauss, and therefore, as the permanent magnets 24 and 25, an isotropic barium ferrite magnet or a so-called plastic magnet in which magnetic powder is dispersed in a synthetic resin can be used. Additionally, anisotropic strontium ferrite magnets, anisotropic barium ferrite magnets, etc. may also be used, but in this case, the magnetic pole end face is attached to the sleeve 2.
It is necessary to separate it somewhat from the inner surface of 0. In addition, the permanent magnet 26
forms a sub-magnetic pole for guiding the developer that has been developed with the main pole into the housing 30, and is approximately 902 mm in the clockwise direction from the upper part of the fixed body 21, for example, the main magnetic pole formed by the permanent magnet 22. They are placed at angular intervals. The magnetic flux density on the surface of the sleeve 20 of the sub-pole formed by the permanent magnet 26 is preferably 500 Gauss or more, and an anisotropic barium ferrite magnet or an anisotropic strontium ferrite magnet can be used as the permanent magnet. 31 is a blade made of rubber or the like for scraping off developer remaining on the surface of the sleeve 20 after development;
It is located on the downstream side of the sub magnetic pole formed by the permanent magnet 26 with respect to the rotation direction of the permanent magnet 26 .

Reference numeral 32 denotes a hopper for supplying developer provided at the upper part of the housing 30.

Reference numeral 33 denotes a phenol resin or the like having a substantially triangular prism shape, which constitutes a developer tip regulating means that is removably attached to the bottom of the housing 30 located directly below the sleeve 20 from the outside with screws 34a and 34b. The developer regulating member is made of a non-magnetic material, and its tip (upper part) has a tapered chevron-shaped portion that projects upward through a hole 35 formed at the bottom of the housing 30, that is, in the direction of the sleeve 20, Its tip is 3~3mm from the surface of the sleeve 20.
They are about 6 fish apart.

A perspective view of the developer regulating member 33 is shown in FIG. The developer regulating member 33 is located approximately in the middle between extensions of straight lines connecting the rotation center of the sleeve 20 and the sub magnetic poles formed by the permanent magnets 23 and 24, and 6 counterclockwise to the main magnetic pole to be formed.
It is effective to arrange them at angular intervals of 00 to 99 degrees. Further, as seen in FIG. 2, the angle θ between the right side slope of the chevron-shaped portion of the developer regulating member 33, that is, the surface on the side that receives the transported developer, and the bottom surface of the housing 30 is 150. In this embodiment, the developer regulating member 33 is
It also serves as an opening/closing lid for developer discharge. That is, when it is desired to discharge the developer 28 inside the housing 30 for exchanging the developer, the screws 34a and 34b are removed and the developer regulating member 33 is removed. Then, when the sleeve 20 is rotated in the direction of arrow F, the permanent magnets 24 and 25
Since the magnetic flux density on the surface of the sleeve 20 of the sub magnetic pole formed in is as small as 100 to 500 Gauss as described above, the developer 28 can be easily discharged from the hole 35 of the housing 30. . In the magnetic brush developing device configured as described above, the same two-component dry developer as described in the conventional example shown in FIG. When the rotational torque of the sleeve 20 was measured with an amount of L ~ 60t/tai, the length was 26
0u! In the case of the sleeve, it was 2.8k9.

This is a significant reduction compared to the 7 to 8 kg per person mentioned in the previous conventional example. FIG. 3 is a side sectional view of another embodiment of the present invention, in which the same components as those described in the embodiment of FIG. 2 are given the same reference numerals.

The embodiment of FIG. 3 includes a permanent magnet 22' corresponding to 22 in FIG. 2, and a permanent magnet 24 corresponding to 24 and 25 in FIG.
'', and three permanent magnets such as permanent magnet 26' corresponding to 26 in Fig. 2 are used, and they are embedded in a fixed body 21'' made of non-magnetic material corresponding to 21 in Fig. 2. The entire structure is cylindrical.

Note that the sub magnetic pole formed by the permanent magnet 24'' is 1 point counterclockwise with respect to the main magnetic pole formed by the permanent magnet 22'.
The developer regulating member 33 connects the center of rotation of the sleeve 20 with the main magnetic pole and the sub magnetic pole formed by the permanent magnets 22' and 24', respectively. They are disposed approximately halfway between the extension lines of the connecting straight lines, for example, at angular intervals of 400 to 99 angles in the counterclockwise direction with respect to the main magnetic pole formed by the permanent magnet 27. In this case, the distance between the tip of the chevron-shaped portion of the developer regulating member 33 and the surface of the sleeve 20 is set to 3 to 611 as in the embodiment shown in FIG. right side slope and housing 30
The angle θ formed with the bottom surface is 135. Further, the magnetic flux densities on the surface of the sleeve 20 of the main magnetic pole, the sub magnetic pole, and the sub magnetic pole formed by the permanent magnets 22', 24', and 26'' are respectively 700 to 1500 Gauss and 100 to 500 Gauss.
Gauss, 500 Gauss or more, and the same permanent magnet materials as explained in FIG. 2 can be used.

In the case of the embodiment shown in FIG. 3, the unit length of the sleeve 20 is 26 f/C! using the two-component dry developer described above. !
L~607/(177!) was inserted and the rotational torque of the sleeve 20 was measured, and the required torque was 31 < g-? A significantly reduced result was obtained compared to 8 kg one man.

Of course, also in the embodiment shown in FIG.
The developer 28 in the housing 30 can be easily discharged to the outside through the hole 35 when the housing 30 is removed.

As is clear from the above embodiments, the present invention is applicable to O electrostatic latent image developing magnetic poles (permanent magnets 22, 22 in the above embodiments).
(equivalent to the main magnetic pole formed by)
Therefore, the electrostatic latent image formed on the surface of the photosensitive drum is developed in the lateral direction (horizontal or substantially horizontal direction).

o A developer tip regulating means (corresponding to the developer regulating member 33 in the same embodiment) is detachably attached from the outside so that the hole formed in the bottom of the housing located below the sleeve can be opened and closed. As a result, the developer in the housing can be discharged to the outside through the hole in the bottom of the housing without turning over the main body of the developing device, thereby significantly simplifying the work of replacing the developer.

In this case, in particular, as described in the previous embodiment, the developer transport magnetic pole (permanent magnet 24 in the same embodiment,
25, 24') on the sleeve surface is smaller than the magnetic flux density on the sleeve surface due to the electrostatic latent image developing magnetic pole (preferably,
When the magnetic flux density on the sleeve surface due to the electrostatic latent image developing magnetic pole is 700 to 1500 Gauss, the magnetic flux density on the sleeve surface due to the developer conveying magnetic pole is 100 to 500 Gauss.
Let it be Gaussian.

), the developer carrier easily separates at that part, so by rotating the sleeve, the developer in the housing falls under its own weight from the hole to the lower part of the housing, making it easier to discharge.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of the main part of a conventional magnetic brush developing device, FIGS. 2 and 3 are side sectional views of the main part showing an embodiment of the present invention, and FIG. 4 is a developer used in the present invention. It is a perspective view of an example of a regulation member. 20... Sleeve, 21, 2V... Fixed body, 22, 27, 23, 24, 24'', 25, 26,
2C...Permanent magnet, 27...Photosensitive drum, 28...Developer, 30...Housing, 32...For developer supply Hotsupaichi 33・
...Developer regulating member, 34a, 34b...
・Screw, 35... hole.

Claims (1)

[Scope of Claims] 1. A rotating sleeve, a magnetic pole for developing an electrostatic latent image and a magnetic pole for transporting a developer formed with a permanent magnet fixedly disposed within the rotating sleeve, A magnetic brush developing device comprising a developer tip regulating means for regulating spikes of developer brought from the developer conveying magnetic pole part to the electrostatic latent image developing magnetic pole part as the developer rotates. The electrostatic latent image developing magnetic pole is disposed laterally so as to face a side surface of the photosensitive drum, and the developer transporting magnetic pole is located near the surface of the developer tip regulating means on the side that receives the transported developer. and the magnetic flux density on the surface of the rotating sleeve of the magnetic pole for carrying the developer is made smaller than the magnetic flux density on the surface of the rotating sleeve of the magnetic pole for developing the electrostatic latent image, and The means is configured to allow a hole formed at the bottom of the housing, the upper part of which is provided with a developer supply part and which accommodates the rotating sleeve and the developer therein, to be closed and opened, and to allow the upper part to be opened and closed by the rotating sleeve. It is detachably attached to the bottom of the housing so as to face the outer peripheral surface of the sleeve with a predetermined gap, and when the hole is opened by the developer tip regulating means, the developer in the housing is discharged to the outside through the hole. 1. A magnetic brush developing device characterized in that it is configured to enable. 2. In the description of claim 1, the developer tip regulating means is a chevron having a substantially triangular prism shape such that the angle formed between the surface on the side that receives the developer being conveyed and the bottom surface of the housing is an obtuse angle. The device is characterized in that it is configured to include a member, and that the angle-shaped member is inserted from below into a hole formed in the bottom of the housing, and is detachably attached to the bottom of the housing from the outside with screws. Magnetic brush developing device.