JPH065423B2 - Electrophotographic liquid reversal developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a liquid developing apparatus for developing an electrophotographic photosensitive member on which an electrostatic image is formed, and in particular, reversal development of a lithographic printing plate on a metal plate support. The present invention relates to a liquid developing device suitable for

(B) Conventional technology and its problems A toner image is formed on a printing plate material having an organic photoconductive compound layer by an electrophotographic method, and after fixing, the non-image area other than the toner image forming area is an alkaline aqueous etching solution. The planographic printing plate obtained by etching with
No. 7162, No. 38-6961, No. 41-2426
No. 46-39405, JP-A-50-19509.
No. 54-19803, No. 54-134632,
It is disclosed in patent publications such as 54-145538, 55-105244, and 56-146145, and is well known. These printing plates are manufactured as follows. That is, a styrene / maleic anhydride copolymer, a vinyl acetate / crotonic acid copolymer, a vinyl acetate / maleic anhydride copolymer, a phenol resin, an acrylic or methacrylic acid having an acid value, which is soluble in an alkaline aqueous solution as a binder. A resin or the like is used, and these are mixed with an organic solvent and an organic photoconductive compound, and coated on a conductive metal substrate such as an aluminum plate to prepare a photoreceptor, that is, a printing plate material. Corona charging, exposure, toner development,
Fixing is performed to obtain a toner image on the printing plate material. Further, the toner image is used as a resist layer, and the non-image portion other than the toner image is removed by etching with an alkaline aqueous etching solution, so that the hydrophilic metal substrate is exposed in the non-image portion,
A lithographic printing plate having an ink-receptive toner image portion can be formed.

The toner used for image formation may be a so-called dry toner, but a liquid toner by a liquid developing method is far preferable in order to obtain a printed matter having excellent resolution. Further, since the toner is used as a printing plate, the toner is hydrophobic and ink-receptive, and needs to have adhesiveness to a printing plate material that can withstand printing, and further resist when etching with an alkaline aqueous etching solution. Must have sex.

Therefore, in the printing plate as described above, it is necessary that the thin lines of several tens of microns be reproduced well by the liquid developing method to the extent that they have resist properties. Needless to say, as in the case of a general electrophotographic photosensitive member, fogging, halo, snoring, edge effect, etc. should not actually occur.
Further, from one surface of the liquid developing device, the roller, the developing electrode,
It is also necessary that the printing plate and the like are not contaminated with liquid toner and difficult to clean.

When a negative image is obtained by exposing such a printing plate with a laser beam such as a He-Ne laser or a semiconductor laser, a liquid reversal developing device as shown in FIG. 2 is used. That is, toner particles having a positive charge are dispersed in the developer 8, and the positively charged photoconductor 12 has the charge in the exposed portion disappeared or reduced by image exposure. A developing bias voltage is applied between the upper electrode plate 2 and the lower electrode plate (bottom plate) 21 by the developing bias power source 10.
In particular, the lower roller 42 of the feed roller pair and the lower roller 62 of the squeezing roller pair are metal rollers, and a developing bias voltage is reliably applied by forming a closed circuit as shown in FIG. 2 through the frame of the developing device. You can When the development is performed in this manner, the toner adheres to the charged portion (exposed portion) of the photoconductor lower than the bias potential, and so-called reversal development proceeds. However, the reversal developing device shown in FIG. 2 has a serious drawback. That is, the toner particles adhere to the lower electrode plate 21, the lower feed roller 42, the lower squeeze roller 62, the frame (not shown) of the developing device, and the like, and the toner becomes lumps. This means that extra toner particles are consumed and the toner particles clump up again in the developer 8
When it is subsequently developed, it mechanically adheres to the non-image area of the photoconductor 12 to cause stains. Obviously, a great deal of time and labor is required for maintenance in order not to cause this problem.

(C) Object of the Invention An object of the present invention is to provide a liquid reversal developing device which does not have the above-mentioned drawbacks, and prevents the electrophotographic photosensitive member from being contaminated due to toner lumps, and is a component of the developing device. It is an object of the present invention to provide a liquid reversal developing device in which toner particles are prevented from adhering and sticking to facilitate maintenance.

(D) Configuration of the Invention The above object of the present invention is an electrophotographic liquid reversal developing device for carrying and developing in a developing solution while facing the electrostatic latent image surface of the electrophotographic photosensitive member to a developing electrode, A developing unit inclined in one direction, an insulating diaphragm roller pair provided near the outlet of the developing unit, and a feed roller pair provided near the inlet of the developing unit, and the feed roller and the vicinity of the pair of aperture rollers. This is achieved by an electrophotographic liquid reversal developing device characterized in that a developing bias closed circuit is constituted by an electrophotographic photosensitive member being conveyed in a pair or in the vicinity thereof and the developing electrode.

FIG. 1 is a schematic sectional view showing a liquid reversal developing device of the present invention.

In FIG. 1, the developer supply unit 1 is a pump (not shown).
Is a portion for continuously supplying the developing solution 8 in the developing solution container 9. The developing electrode plate 2 may be made of any material, for example, any metal as long as it is a good electric conductor. Reference numeral 3 denotes a guide plate forming a bottom plate, 4,5 a feed roller pair, 6.7 a diaphragm roller pair, and 10 a developing bias power source. Bottom plate 3
A developing chamber is formed by the developing electrode 2 that forms a top plate and is opposed to it with a predetermined gap therebetween, and a side plate (not shown). The electrophotographic photosensitive member 12 is carried into the developing chamber by the feed roller pairs 4.5 with the surface of the electrostatic latent image facing upward, transported along the bottom plate 3, and the developing solution adhering is squeezed by the diaphragm roller pair 6.7. Taken out.

In this apparatus, by appropriately selecting the inclination of the bottom plate 3 and the distance between the developing electrode 2 and the photoconductor 12 (or the bottom plate 3), the developer 8 does not overflow from the high side at all or slightly overflows. It is supposed to do. Generally, the bottom plate has an inclination of 30
It is preferably not more than 5 degrees and not more than 5 to 20 degrees. Since the developing section is inclined, the feed roller pairs 4 and 5 are not substantially contaminated by the developing section 8. Therefore, the lower roller 4 of the feed roller pair is a metal roller. Therefore, even if the developing bias voltage is applied to the photoconductor 12 by configuring the developing bias closed circuit as shown in FIG. 1, the liquid toner does not adhere to and deposit on the feed roller pair 4.5. Of course, without using the lower metal roller 4,
The feed roller pair is an insulative roller pair 4.5 (for example, a rubber roller pair), and a bias closed circuit is formed in the vicinity of the front or rear of the feed roller pair 4.5 by a bias feeder such as a metal roller or a metal piece. You may The squeezing roller pair 6 and 7 is made of an insulating material such as rubber or elastic plastic, and is biased by a metal roller or a metal piece in the vicinity of the front or rear of the squeezing roller pair 6 and 7 as shown in FIG. Make up the circuit. Preferably, after the squeezing roller pair 6 and 7 (on the side opposite to the developing portion), the metal plate 11 having a needle-like shape slides on the metal plate support surface of the photoconductor 12. The developer does not adhere to the back surface of the photoconductor 12 that has passed through the pair of aperture rollers 6 and 7, and the metal piece 11 has a small area and its tip is rubbed by the metal plate support, so that the liquid toner Adhesive deposits are significantly reduced.

It is necessary to set the distance between the metal roller and the bias feeder of the metal piece forming the developing bias closed circuit before and after the developing unit so as to be shorter than the length of the photoconductor 12 in the developing direction. That is, the developing bias closed circuit is not formed when the electrophotographic photosensitive member 12 does not exist, but is formed when the photosensitive member 12 enters the developing chamber, and a bias voltage is applied to the photosensitive layer of the photosensitive member 12, so that it is good. Reversal development proceeds.
Next, even if the end of the photoconductor 12 separates from the feed roller pair 4.5 or the bias feeder in the vicinity thereof, the bias voltage is applied to the front portion of the photoconductor 12 by the bias feeder near the aperture roller pair 6.7. Therefore, a uniform developing bias voltage is applied over the entire surface of the photoconductor 12 and a good negative image is formed.

The developed photoconductor 12 is subsequently transported to processes such as drying, fixing, elution and gumming. Further, on the right side of FIG. 1, a plate supply section, a charging section, and an image exposure section are provided.

In the above description, the photoconductor 12 is positively charged, the developer 8
In the above description, the positive charge was applied and the voltage applied to the developing electrode 2 was positive, but it goes without saying that reversal development in which both are negative may be used.

〔The invention's effect〕

The liquid reversal developing device of the present invention can prevent toner particles from adhering to the constituent elements of the device due to the developing bias voltage, and also does not cause stains on the photoconductor due to toner particle lumps.
Further, toner particles are not consumed and maintenance is easy.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of the electrophotographic liquid reversal developing apparatus of the present invention, and FIG. 2 is a schematic sectional view showing the conventional apparatus. 1 Developer Supply Unit 2 Developer Electrodes 3 and 21 Bottom Plates 4 and 5 Feed Roller Pair 41 and 42 Feed Roller Pair 6.7 Aperture Roller Pair 61 and 62 Aperture Roller Pair 8 Developer 9 Developer Container 10 Development Bias Power Supply 11 Bias Power Supply 12 Electrophotographic photoreceptor

Claims (1)

[Claims] 1. An electrophotographic liquid reversal developing device which conveys and develops an electrostatic latent image surface of an electrophotographic photosensitive member in a developing solution while facing the electrostatic latent image surface to a developing electrode, and a developing section inclined in one direction and An electron having a feed roller pair provided near the entrance of the developing section and an insulating diaphragm roller pair provided near the exit of the developing section, and being transported in the vicinity of the feed roller pair or near the diaphragm roller pair. An electrophotographic liquid reversal developing device characterized in that a photographic photoreceptor and the above-mentioned developing electrode constitute a developing bias closed circuit.