JPS5854391B2 - Genzozai no Mawarikomioboshi Uruyounishita Genzosouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for developing an electrostatic latent image, and more particularly, to a device for developing an electrostatic latent image on a drum-shaped photoreceptor or a rotating photoreceptor that includes an arc-shaped path as a part of its moving path. The present invention relates to a developing device that efficiently develops on a curved surface portion and prevents developer from going around.

In the generally known magnetic brush development method, a developing device is constructed by arranging permanent magnets with appropriate spacing and polar arrangement in the circumferential direction of a support made of a non-magnetic material such as aluminum or Bakelite. Alternatively, a non-magnetic and electrically conductive sleeve may be provided to surround the permanent magnet and allow it to rotate independently, in order to eliminate the unevenness phenomenon which is a well-known drawback when using devices of the aforementioned type. Using a developing device, a developer consisting of toner and iron powder adsorbed on the permanent magnet or sleeve by magnetic action is sequentially guided to the surface of the photoreceptor and brought into contact with it to form an electrostatic latent image. There is.

In this developing method, the developer conveyed on the sleeve is mechanically brought into contact with the surface of the photoreceptor, so a considerable amount of toner powder is scattered due to centrifugal force or impact, contaminating the inside of the device. be.

Of course, the scattering of toner powder due to the impact is caused by the relative speed between the photoreceptor and the developer, but in order to produce good halftones, which is a characteristic of magnetic brush development, the developer on the sleeve One of the factors is that the spike (thickness of the developer on the sleeve) is increased and the contact depth is increased so that development can be performed on soft areas.

It is well known that this problem of toner scattering is one of the problems to be considered in the cascade development method.

The present invention eliminates the above-mentioned drawbacks and provides a new developing device that can prevent toner scattering and developer from getting around.

According to the present invention, a plurality of permanent magnets consisting of a developer supply magnet and a developer discharge magnet are provided close to the circumferential surface of a rotating photosensitive drum, and surround these permanent magnet groups and themselves. A developer conveying belt made of a flexible material is disposed so as to be able to rotate facing the photosensitive drum to constitute a conveying means, and during operation, the peripheral surface of the photosensitive drum is moved by interaction between the permanent magnet and the conveying belt. A developing device configured to allow a continuous flow of the developer layer to appear over a certain range, and to form an electrostatic latent image formed on the surface of the photosensitive drum into a visible image using the developer layer in the certain range, A direction within the conveyor belt and away from the permanent magnets with respect to the developer layer in the certain range so that the developer can be received and transferred in cooperation with the permanent magnets on the developer supply side and the developer discharge side. Another permanent magnet is attached to each of the permanent magnets, and each of the permanent magnets is made shorter than the permanent magnets on both sides, which have a length sufficient to cover the image width on the surface of the photosensitive drum, thereby preventing the developer from going around. I tried to get it.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a schematic diagram of the developing device section. In the figure, 1 is a drum-shaped photoreceptor whose surface is coated with a photoconductive insulating layer made of amorphous selenium, zinc oxide, cadmium sulfide, etc., and is connected to an appropriate drive device so that it can rotate as shown by the arrow. It is connected.

2 shows the entire developing device.

Reference numerals 210 and 210' designate one side plate for mounting various elements constituting the developing device.

On the inside of these side plates 210, 210', as shown in FIG. 4, ferls 211, 211' are provided to completely prevent the developer from going around into the conveyor belt by the magnet arrangement described later. It is something to do.

This will be explained in more detail later.

212 to 216 are permanent magnets (hereinafter simply referred to as magnets).

), and if the magnet group is broadly divided, in the figure (1
) a developer supplying magnet 212 located below and a related developer trapping prevention magnet 213; (2)
They are classified into an intermediate magnet 214, and (3) a developer discharging magnet 215 located above and a related developer trapping prevention magnet 216.

These magnets are spaced apart so that they can exert a magnetic field effect on each other so that a continuous flow of developer can be formed.

The magnets 213 and 216 for preventing developer from getting around are the first magnets.
Although only one of each is shown in the figure, it goes without saying that a plurality of them may be provided.

When a plurality of developer wrap prevention magnets are disposed in this manner, they are placed far away from the developer supply magnet 212 and the developer discharge magnet 215 along the circumferential surface of the support.
It is desirable to gradually shorten the axial length of the support as shown in FIG.

Further, the magnetic pole arrangement of the magnet group maintains a different polarity alternating arrangement of N poles and S poles.

Furthermore, magnets 212, 214 and 215 are provided along the circumferential surface of the photoreceptor.

Supports 217 and 218 hold the magnets on the supply side and the discharge side, and are themselves fixedly provided to the device.

Reference numerals 219 and 220 designate cylindrical sleeves that contain the supply-side and discharge-side magnet groups, but are constructed so that they can rotate independently.

In reality, one sleeve 219 is connected to a suitable drive source, and the rotational force in the direction of the arrow shown in the figure can be transmitted to the other cylindrical sleeve 220 by means of a chain.

Reference numeral 221 denotes a guide member formed to have a radius of curvature substantially equal to the circumferential surface of the photoreceptor, and faces the circumferential surface of the photoreceptor with an appropriate gap in between.

Further, although shown at intervals in the figure, the intermediate magnet 214 is held on its back side (on the opposite side from the photoreceptor).

Reference numeral 222 denotes a belt which surrounds the magnet groups 212 to 216 and the guide member 221 and is provided so as to be able to rotate with the rotation of the cylindrical sleeve 219 and 2200 rotations, and is made of a flexible material such as a polyester film. It is made of synthetic material.

The linear velocity of the drum and belt is about 1.7 times (200rnll/sec) and about 1/2 of the linear velocity of the belt compared to the linear velocity of the conventional drum and brush. 2-1/3 (120-80mm
/sec).

Reference numeral 223 denotes a tension roller for tensioning the belt 222, which is comprised of a plurality of circular-shaped rollers arranged in the longitudinal direction of the shaft so as to prevent the belt from shifting to one side.

Reference numeral 224 denotes a frame capable of accommodating a developer, and is located on a bottom plate 225 that connects the side plate 210 and the other side plate 210' (see FIG. 2), and is configured to be able to be inserted into and removed from the bottom plate 225. It is.

Further, in this case, a portion of the frame 224 corresponding to the lowermost part of the sleeve 219 also serves to restrict the spikes of the developer.

The entire developing device 2 is also designed to be able to be freely inserted into and taken out from a holding plate 226 on the machine main body side.

With this structure, when a rotational force is applied to the sleeve 219, the other circular sleeves 220 also begin to rotate, and the belt 222 rotates as shown by the arrow due to friction.

On the other hand, with this operation, a portion of the developer stored in the frame 213 is pulled onto the belt 222 due to the strength of the magnetic force of the magnet 213.

The developer is exposed to the lines of magnetic force obtained by the group of magnets,
As the belt moves, it is deflected, passes through the magnet 212, and reaches the intermediate portion, that is, a portion of the guide member 221.

Here, even if there is a gap between the flexible belt 222 and the guide member 221 before operation, the magnet 214 attracts the developer, and as a result, the belt 222 is attached to the guide member by the developer. The member is pressed down and its movement path is on the radius of curvature of the member.

Subsequently, when the developer reaches the magnet 215, an arc-shaped developer flow appears between the magnets 212, 214, and 215 and can come into contact with the surface of the photoreceptor drum 10.

Thereafter, when the developer passes over the magnet 216 and reaches a position out of the reach of its magnetic force, it falls on the belt 222 due to its own weight and is stored in the frame 224 again.

By repeating the above-mentioned operation for a time period related to the copying operation, the graphic-shaped electrostatic latent image formed on the photoreceptor drum 1 by a known method is rubbed with a large amount and with a slow developer flow. This means that it can be developed.

In addition, during the experiment, the flexible belt had a thickness of 5
A polyester film having double-sided matte treatment of 0 micron and 75 micron and a polyester film having double-sided matte treatment of 25 micrometer are pasted together so that both end surfaces are spiral-shaped, and the photoreceptor drum 1 The linear velocity ratio between the belt 222 and the belt 222 is approximately 1.
:0.6 to 1:0.4 and created an image using the above method. As a result, good development was obtained, and the rotation speed of the belt was lower than that of the conventional magnetic brush. Since the amount of toner can be reduced in any way, toner scattering (including fine iron powder) can be extremely reduced.B4 size 2000
Although it is possible to use a thin belt made from the above-mentioned polyester film, which is known to have less than 1gr for 0 copies, it is difficult to correct the deviation of the belt when it is 50 microns or less.

Further, the film surface does not necessarily need to be matted on both sides as described above, and may be treated on only one side, which contributes to the conveyance of the developer.

In place of the polyester film, which is a non-magnetic and flexible material, we used a belt made of a magnetic material made by electroforming, such as a nickel alloy, and it was proven that good development could be achieved in the same manner as above. ing.

FIG. 2 shows a cross section taken along line A-A through the central axis of the cylindrical sleeve 219 located below FIG.

In the figure, reference numerals 210 and 210' denote opposing side plates, and felts 211 and 211' that are thick enough to contact both side edges of the conveyor belt 2220 are attached to the inner surfaces of the side plates.
This completely prevents the developer carried along with the belt from getting around to the back side of the belt from both side edges of the belt.

In the above embodiment, it was explained that the belt 222 is moved by friction and tension between the belt, the upper and lower cylindrical sleeves 219, 220, and the tension roller 223, but in this case, the upper cylindrical Another roller may be provided above the cylindrical sleeve 220, and the belt may be sandwiched between the roller and the cylindrical sleeve.

Note that the apparatus of the present invention can obtain the same excellent effects regardless of the components of the developer.

As described above, the present invention provides, in addition to a developer supply magnet and a developer discharge magnet, a further magnet arranged in the direction away from the magnet so that the developer can be received and transferred in cooperation with these magnets. By providing a magnet and making this additional magnet shorter than the developer supply and discharge magnets, it is possible to prevent the developer from running around.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of the developing device section according to the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, FIG. 3 is a surface development view of one of the supports, and FIG. FIG. 2 is a schematic elevational view of the developing device section of FIG. 1... Photosensitive drum, 2... Developing device, 210° 210'... Side plate, 211, 211'
... Felt, 212 ... Magnet for developer supply, 213 ... Magnet for preventing developer from getting around, 214 ... Intermediate magnet, 215 ... ...
- Magnet for developer discharge, 216...Magnet for preventing developer from getting around, 217, 218...Support,
219.220... Cylindrical three 7.221.
...Guide member, 222...Belt.

Claims (1)

[Claims] 1. A developer supply magnet is provided inside one of two rotating sleeves arranged close to the circumferential surface of the rotating photosensitive drum and spaced apart in the rotational direction of the photosensitive drum, and a developer discharge magnet is provided inside the other. A developer guide member having a radius of curvature substantially the same as that of the photosensitive drum is disposed between the circumferentially rotating sleeve in close proximity to the circumferential surface of the photosensitive drum, and the photosensitive drum and the developer are disposed between the circumferentially rotating sleeve. A developer transport belt is passed between the developer guide member and the developer guide member, and during development, due to the interaction between both magnets and the transport belt, a continuous developer is distributed over a constant width and a constant length on the circumferential surface of the photosensitive drum. In a developing device that forms a layer flow and develops an electrostatic latent image on the surface of the photosensitive drum with the developer layer into a visible image, the developer supplying magnet is disposed inside the one rotating sleeve. A magnet for preventing developer from getting around is provided on the upstream side as seen in the developer transport direction, and a magnet for preventing developer from getting around is provided inside the other rotating sleeve as seen from the developer discharge magnet on the downstream side as seen in the developer transport direction. A magnet for preventing entrapment is provided, and the length of both of the developer entrapment prevention magnets in the axial direction of the rotating sleeve is shorter than the length of the developer supply and discharge magnets in the axial direction of the rotating sleeve. A developing device that can prevent developer from getting around.