JPS5854389B2 - How to develop an electrostatic latent image - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for developing an electrostatic latent image, and more particularly to a method for developing an electrostatic latent image on a drum-shaped photoreceptor or a rotating photoreceptor that includes an arcuate path as part of its moving path. The present invention relates to a magnetic brush developing method and apparatus for efficiently developing curved surfaces.

In the generally known magnetic brush development method, permanent magnets are arranged at appropriate intervals and polar arrangement in the circumferential direction of a support made of a non-magnetic material such as aluminum or Bakelite. In order to eliminate the step unevenness phenomenon, which is a well-known drawback when using devices of the above-mentioned type, a non-magnetic and electrically conductive material surrounds the permanent magnet and is capable of independent rotation. Using a developing device configured with a sleeve, a developer consisting of toner and iron powder, which are attracted to the permanent magnet or the sleeve by magnetic action, is sequentially guided to the surface of the photoreceptor and brought into contact with the surface of the photoreceptor, thereby forming an electrostatic latent image. is the visible image.

At that time, in any of the above embodiments, the width of the developer that comes into contact with the photoreceptor (generally referred to as being rubbed) is removed.

) must be limited to about 10 to 20.

Such a developing action in the pinching range has no effect on copying machines with slow copying speeds, but presents an undesirable phenomenon in high-speed copying machines.

In other words, the mechanism of development is that while the surface of the photoreceptor is in contact with the developer, the electric charge of the graphic shape (electrostatic latent image) held on the photoreceptor is charged with a polarity opposite to that of the electric charge. This is achieved by electrostatic adsorption of the toner that is floating in the air.

Therefore, when it is desired to carry out faithful development in proportion to the magnitude of the charge possessed by the latent image, the development efficiency largely depends on the contact time between the two.

Therefore, when the conventional developing method described above is applied to high-speed copying, it is of course impossible to provide sufficient contact time between the photoreceptor surface and the developer, and as a result, the finished copy does not match the original. That is the downside of not being faithful.

Furthermore, in conventional developing devices, the rotation speed of the sleeve or magnet support is high (usually about 130 rotations/min with a brush of about 60 to 70φ), and the developer conveyed on such a sleeve is Since the toner is brought into direct contact with the surface of the photoreceptor, it has the disadvantage that a considerable amount of toner powder is scattered by centrifugal force or impact, contaminating the inside of the device.

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 the problem of toner scattering is one of the problems to be considered in the cascade development method.

The present invention eliminates the above drawbacks, has a simple structure, and
An object of the present invention is to provide a developing method and device that can reliably widen the rubbing width of a developer on a photoconductor and can remove toner scattering without the need for other means.
The purpose of this is, firstly, on the path of a rotating photoreceptor including a drum shape, and along the circumferential surface of the drum or along an arc-shaped movement path of a photoreceptor of other shapes. A continuous flow of the developer layer is created along the arcuate path by interaction between a plurality of magnetic elements and a rotatably provided belt surrounding the group of magnetic elements,
It is an object of the present invention to provide a developing method for converting an electrostatic latent image on a photoreceptor into a visible image using the developer layer in a certain range.

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 numeral 210 designates one measuring plate for mounting various elements constituting the developing device.

211 to 215 are permanent magnets (hereinafter simply referred to as magnets).

), and the magnet group can be roughly divided into developer storage side magnets 211 and 212 located at the bottom in the figure, intermediate magnet 213, and developer discharging magnets 214 and 2 located at the top.
It is classified into 15.

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.

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

Further, magnets 212, 213 and 214 are provided along the circumferential surface of the photoreceptor.

216 and 217 are supports which hold the storage and evacuation magnets and which are themselves fixedly provided to the device.

Reference numerals 218 and 219 designate cylinders containing the storage and evacuation magnets, which are configured to rotate independently.

In reality, one cylinder 218 is connected to a suitable driving source, and the rotational force in the direction of the arrow shown in the figure can be transmitted to the other cylinder 219 by a chain.

Reference numeral 220 denotes a guide member formed to have a radius of curvature g equal to the circumferential surface of the photoreceptor, and faces the circumferential surface of the photoreceptor with an appropriate gap therebetween.

Although shown with a gap in the figure, the intermediate magnet 213 is held on its back side (on the opposite side from the photoreceptor).

Reference numeral 221 denotes a belt which surrounds the magnet groups 211 to 215 and the guide member 220 and is provided so as to be able to rotate with the rotation of the cylinders 218 and 219, and is made of a flexible material such as a polyester film. It is made of material.

The linear velocity of the drum and belt is about 1.7 times (200 mm/sec) compared to the linear velocity of the conventional drum and brush, and the linear velocity of the belt is about %~ %(120~80mu/sec
).

Reference numeral 222 denotes a tension roller for tensioning the belt 2 and 21, which is comprised of a plurality of round-shaped cylindrical rollers provided in the longitudinal direction of the shaft so as to prevent the belt from shifting to one side.

Reference numeral 223 denotes a frame capable of accommodating a developer, and is located on a bottom plate 224 that connects the measuring plate 210 and another measuring plate (not shown), and is configured to be freely inserted into and removed from the bottom plate. .

Also, in this case, the frame 22 corresponding to the lowest part of the cylinder 218
Part 3 also serves as a developer spike control.

The entire developing device 2 can also be freely inserted into and removed from a holding plate 225 on the machine main body side.

With this configuration, when a rotational force is applied to the cylinder 218, the other cylinder 219 also begins to rotate, and the belt 221 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 223 is pulled onto the belt 221 due to the strength of the magnetic force of the magnet 211.

The developer moves along 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 220.

Here, even if there is a gap between the flexible belt 221 and the guide member 220 before operation, the magnet 213 attracts the developer, and as a result, the belt 221 is attached to the guide member by the developer. The member is pressed and its movement path is on the radius of curvature of the member.

Subsequently, when the developer reaches the magnet 214, an arcuate developer flow appears between the magnets 212, 213, and 214 and can come into contact with the circumferential surface of the drum 1.

Thereafter, when the developer passes over the magnet 215 and reaches a position out of the reach of the magnetic force, the developer falls on the belt 221 due to its own weight and is stored in the frame 223 again.

By repeating the above-mentioned operations for a time period related to the copying operation, the graphic-shaped electrostatic latent image formed by a known method on the photoreceptor 1 is developed with a large amount of abrasion and a slow flow of developer. It will be possible to do so.

In addition, during the experiment, the flexible belt had a thickness of 5
A polyester film with double-sided matte treatment of 0 micron and 75 micron and a polyester film with double-sided matte treatment of 25 micron are pasted together so that both end surfaces are spiral-shaped, and the photosensitive drum and belt are bonded together. Linear velocity ratio of approximately 1:0.6~
When images were created by the above-mentioned method using a ratio of 1:0.4, good development was obtained.

In addition, since the rotation speed of the belt can be significantly reduced compared to the rotation speed of conventional magnetic brushes, toner scattering (including fine iron powder) can be extremely reduced.
It has been found that 0 copies is less than 1gr.

A belt made of the polyester film can be used even if it is thin, but it is difficult to correct the deviation of the belt if it is less than 50 microns.

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.

Figure 2 shows the cylinder A-A located below in Figure 1.
A cross section is shown.

In the figure, 210 and 210' are measuring plates, 212 is a magnet, 216 is a support, and 218 is a cylinder, as described above.

One of the supports 216 is connected to the holding member 22 via a bearing.
6, and the other end is supported by a loose fit between one end of a shaft 228 fixed to the cylinder 218 via a lid 227' and a hollow portion 229 provided in the support.

The sprocket 230 on the shaft 228 is connected to an appropriate driving source, and the sprocket 230 is fixed on the same axis.
1 is chained to a sprocket (not shown) having a cylindrical shape 219 (see FIG. 1).

232 and 232' are bearings that support the stepped portion of the lid 227 and the shaft 228, and 233 and 233' are felts that shield the inner pieces and outer pieces of the respective bearings.

In the above embodiment, it was explained that the belt could be moved by friction and tension between the belt and the upper and lower cylinders 218 and 219 and the tension roller 222, but in this case, the upper part of the upper cylinder 219 Another roller may be provided in the belt, and the belt may be sandwiched between the roller and the cylinder; [Also, the belt may be constructed so that holes are formed on both sides of the belt and the belt is moved directly by a sprocket. Of course it is good.

Although not directly related to the present invention, the developer may be not only the above-mentioned mixed developer, but also a one-component toner comprising, for example, fine magnetic material appropriately dispersed in toner particles.

As described above, by using the method and apparatus according to the present invention, it is possible to create an image that is faithful to the original even in high-speed copying.

In addition, the simple structure allows the device to be miniaturized, the belt speed can be extremely slowed down, and the relative impact between the photoreceptor and developer can be made extremely small compared to conventional devices, so toner powder Splashing is hardly a problem and maintenance is easy.

You can receive many benefits such as.

In any case, the gist of the present invention is to provide a new and useful method for developing an electrostatic latent image using a continuous flow of developer formed over a certain range of an arcuate portion of a photoreceptor; It is obvious that the invention should not be limited to the one embodiment described above.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing a developing device section according to the present invention. FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1. 1 is a photoreceptor, 2 is the whole developing device, 210 and 210' are measuring plates, 211 to 215 are permanent magnets, 216° and 217 are supports, 218 and 219 are cylinders, 220 are guide members, 22
1 is a flexible belt, 223 is a frame, 224 is a bottom plate, 226
is a holding member, 227°227' is a lid, 228 is a shaft, 2
29 is the hollow part, 230.231 is the sprocket, 232
, 232' are bearings, and 233, 233' are felts.

Claims (1)

[Claims] 1. On the moving path of a rotating photoreceptor including a drum shape, the peripheral surface of the photoreceptor provided close to the drum peripheral surface or an arcuate portion of a photoreceptor of other shape and over a certain range has a curvature equal to g. By rotating a belt made of a flexible material surrounding a guide member having a radius and a magnet element, the magnetic material in the developer to be used is attracted by the magnetic force of the magnet element group. deforming the belt along the shape of the guide member, causing a continuous flow of the developer layer to appear along the arcuate portion, and forming the developer layer in the certain range on the surface of the rotating photoreceptor. A method for developing an electrostatic latent image into a visible image.