JPS609795Y2 - Fog removal device for one-component toner development - Google Patents

Description

[Detailed description of the invention] The present invention is a developing device that develops an electrostatic latent image formed on an electrostatic recording paper using a single toner in an electrophotographic device or facsimile, etc., and eliminates fogging that occurs particularly at low humidity. The present invention relates to a device designed to do this.

In the so-called electrostatic latent image transfer method (TESI), which transfers an electrostatic latent image formed on a photoreceptor to electrostatic recording paper, the electrostatic latent image transferred to electrostatic recording paper is When developing with a magnetic brush using magnetic toner, toner fogging occurs in the image area, especially when this area is large (such as a solid black image), making it impossible to obtain a clear image.

There are roughly two types of methods for removing the above-mentioned fog.

Electrostatic recording paper generally consists of a recording layer (dielectric layer) and a base paper (conductively treated).

Fog is removed by setting the surface resistance value of this base paper to at least 10 7 Ω or less in a 65% atmosphere.

The same applies to coated paper such as zinc oxide paper. Another method is to apply a conductive liquid to the base paper of the electrostatic recording paper after transferring the electrostatic latent image on the photoreceptor to the electrostatic recording paper and before the electrostatic recording paper reaches the developing section. It lowers the resistance value of the base paper by impregnating it.

In the former case, electrostatic recording paper, especially base paper, is very susceptible to the surrounding atmosphere.

That is, as shown in the characteristic diagram in Figure 1, the humidity is 20 to 30%.
When the resistance changes, the resistance value of the base paper changes by one to two orders of magnitude.

Further, the resistance value increases as the humidity decreases, and the amount of change in the resistance value also differs depending on the type of paper, especially the type of conductive treatment agent for the base paper.

For this reason, high-quality images can be obtained when developing with a single-component toner at a humidity above normal humidity (60%), but when the humidity drops below 30%, the resistance value of the base paper increases. , fog occurs around solid black areas.

As described above, in general electrostatic recording paper, the resistance value increases at low humidity, so it is difficult to improve the paper alone in order to eliminate fog at low humidity.

Further, although it is possible to lower the resistance value of the base paper (1 (PΩ or less)), the conductive treatment agent becomes expensive, which increases the price of the paper, and the paper itself becomes a special paper.

On the other hand, in the latter case, if the base paper is impregnated with a conductive liquid before development, the conductive liquid will sufficiently reduce the resistance value even in low humidity conditions, making it possible to suppress the occurrence of fogging.

However, it is necessary to slightly impregnate only the surface of the base paper of the electrostatic recording paper with a conductive liquid, which is technically very difficult, and if the liquid adheres to the recording paper of the electrostatic recording paper, the image will not be formed. Disturbed.

Also, it is fine if the conductive liquid is non-volatile, but if a volatile one is used, it will evaporate and adhere to all parts of the machine.

Therefore, various parts are adversely affected.

For example, rust on lenses, photoreceptors, parts, etc.

Therefore, even if a non-volatile conductive liquid were used, it would be technically very difficult, and since the special conductive liquid is required, the price of the machine would be high and consumable crystallization would be required. Become.

Furthermore, it is a developing device using 1 precept toner, and the above 2
In both of the two methods, the ground electrode was in the form of a flat plate, making it difficult to make the contact resistance uniform.

The present invention does not prevent fogging by impregnating the base paper of electrostatic recording paper with a conductive liquid as in the latter case, but instead provides a roller for guiding the recording paper at a position facing the developing roller in the developing section. This guide roller is electrically conductive and grounded to the main body of the apparatus to prevent low humidity fogging.

Further, the present invention provides a guide plate and a brush for guiding the recording paper in close proximity to the guide roller on at least one of the front and rear sides in the direction of movement of the electrostatic recording paper, and makes the guide plate and brush conductive. It's grounded.

An object of the present invention is to prevent fog development with a simple structure.

That is, by providing a guide member in the developing section with a guide roller facing the developing roller, the contact pressure between the base paper of the electrostatic recording paper and the guide roller is always kept uniform, and the contact resistance between the base paper and the main body of the apparatus is reduced. The purpose is to keep the contact resistance value as uniform and low as possible, and in addition, by providing grounding means near the guide roller, the contact resistance value is made lower and more stable.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 is a sectional view showing the structure of the developing section in the present invention.

In the figure, 1 is an electrostatic recording paper on which an electrostatic latent image is formed on the surface (dielectric layer surface) and is sent to the developing section by an appropriate conveyance means, and 2 and 3 are guide plates that guide the recording paper 1 to the developing section. It is.

The guide plate 2 is made of a conductive member, and the guide plate 3 is made of an insulating member.

A holder 5 holding a conductive brush 4 that contacts the base paper of the electrostatic recording paper 1 being fed is fixed to the lower guide plate 2.

The developing section also has a developing roller 6 that rotates in the direction of the arrow, and as the developing roller 6 rotates, one batch of toner 8 stored in the hopper 7 is transferred to the developing area (opposed to the electrostatic recording paper 1). The image is then transported to the area where the image is to be processed and developed.

That is, the developing roller 6 performs magnetic brush development in which magnetic toner in the hopper 7 is attracted to the roller surface by magnetic force and conveyed to a developing area.

A guide roller 9 for guiding the recording paper is provided opposite the developing roller 6 and spaced apart from it.

This guide roller 9 is electrically conductive and is grounded to the main body of the apparatus.

Further, the developing roller 5 and the guide roller 9 may be made of aluminum or stainless steel, but may also be made of rubber, resin, or the like in order to have elasticity.

In this case, at least the roller surface needs to be subjected to conductive treatment.

Further, it is better that the interval between the developing roller 6 and the guide roller 9 be relatively narrow, but it is not preferable to make it extremely narrow because this will prevent the electrostatic recording paper 1 from advancing.

In the apparatus of this example, good results were obtained by using ordinary electrostatic recording paper and setting the above-mentioned interval to about 0.5 mm to 1 mm.

Note that the above-mentioned interval needs to be larger than the height of the toner attracted to the developing roller 6.

Furthermore, 10 is a guide plate that guides the electrostatic recording paper 1 that has passed through the development area to the next step.

Like the guide plate 2, the guide plate 10 is formed of a conductive column member, and has a fixed holder 12 held by a conductive brush 11 that contacts the base paper of the electrostatic recording paper 1 passing therethrough. There is.

The brushes 4 and 11 are grounded via holders 5 and 12, and in order to improve the running properties of the recording paper, it is not preferable to use brushes that are too hard or have a large diameter for each brush.

Preferably, stainless steel fibers and other conductive fibers are made so that each fiber has a diameter of 10 pm or less so that they can make sufficient contact with the recording paper and do not adversely affect running performance. Eliminate the gaps between the fibers and embed them in the aluminum plate holder 5.12.

Furthermore, the smaller the conductivity of the brush, the better, but it is better to avoid a brush with a conductivity of 1000 or more.

In this embodiment, as shown in FIG.
The brush length is set to 10 to 30 mm, and the brush is placed in such a way that it contacts only with the weight of the recording paper so as not to make strong contact with the recording paper.

Furthermore, in order to increase the contact efficiency due to the weight of the recording paper, it is preferable to use relatively rigid conductive brushes 4 and 11.

In the above configuration, when the electrostatic recording paper 1 on which the electrostatic latent image is formed is conveyed in the direction of arrow A, the guide plate 2,
3 and transported to the developing section.

At this time, the base paper of the electrostatic recording paper 1 comes into contact with the guide plate 2 and the conductive brush 4 and is grounded.

The electrostatic recording paper that has passed through the conductive brush 4 then advances between a developing roller 6 and a guide roller 9, and the back base paper portion in the area being developed is uniformly and sufficiently grounded via the guide roller 9. be done.

Furthermore, even after passing between the developing and guide rollers 6.9, the electrostatic recording paper 1 comes into contact with the next conductive brush 11 and guide plate 10, and is sent to the next process.

In the process of developing the electrostatic latent image on the electrostatic recording paper 1,
The guide roller 9 plays a major role in removing fog because the base paper in the developing area is grounded via the guide roller 9 at the shortest distance.

However, since the contact portion between the guide roller 9 and the base paper is a line contact, there may be cases where the contact resistance cannot be made sufficiently low and stable.

Therefore, the present invention provides guide plates 2 and 10 in addition to the guide roller 9.
Since the conductive brushes 4 and 11 are provided, further stabilization can be achieved than with only the guide roller 9, and fogging can be prevented from occurring at low humidity.

That is, the conductive brushes 4, 11, etc. serve to further stabilize the resistance value of the base paper of the electrostatic recording paper 1 at a low level by the guide roller 9.

The device of this example was able to prevent fogging even when the resistance value was on the order of ICPΩ at low humidity.

FIG. 4 is a sectional view showing another embodiment of the present invention.

In FIG. 4, the same parts as in FIG. 2 are indicated by the same reference numerals, and their explanation will be omitted.

The difference between this embodiment and the embodiment shown in FIG. 2 is whether a fixed member is used as the guide plate for guiding the recording paper or whether it is provided movably.

That is, the reference numeral 13 in the figure is a recording paper conveyance belt that is conductive and movable via a drive roller 14.

The belt 13 is grounded to the main body of the apparatus via the drive roller 14.

In this case, it is preferable to make the surface of the belt 13 slightly uneven to increase the coefficient of friction.

Further, in the figure, reference numeral 15 denotes a holder for holding the conductive brush 16 which is in contact with the base paper of the electrostatic recording paper 1 conveyed by the belt 13 and is grounded, and is attached to the main body of the apparatus.

As explained above, according to the present invention, in an apparatus in which an electrostatic latent image formed on a recording medium is developed with a one-shot toner, there are , a conductive brush is provided in contact with the surface opposite to the electrostatic latent image forming surface of the recording medium, and the brush and the guide roller are grounded, so that the opposite surface of the recording medium is not only connected to the guide roller but also the front and rear brushes. This allows good grounding, prevents fogging that occurs in low humidity, and has a very simple structure.

[Brief explanation of the drawing]

Fig. 1 is a characteristic curve diagram showing changes in base paper resistance due to humidity changes in electrostatic recording paper, Fig. 2 is a sectional view showing an embodiment of the fog removal device of the present invention, and Figs. 3 a and b. 4 is a plan view and a side view showing the structure of a conductive brush according to the present invention, and FIG. 4 is a sectional view showing another embodiment of the present invention. 1: Electrostatic recording paper, 2 (10) Ni guide plate, 4 (11,
16): Conductive brush, 6: Developing roller, 8:1 magnetic toner, 9: Guide roller.

Claims (1)

[Scope of utility model registration request] A conductive and grounded guide roller that guides the electrostatic latent image formed on the recording medium to a developing section that develops the electrostatic latent image on the recording medium; A fog removal device for one-command toner development, comprising conductive brushes connected to the surface opposite to the electrostatic latent image forming surface of the recording medium and grounded before and after the guide roller.