LIQUID DEVELOPING METHOD AND LIQUID DEVELOPING APPARATUS

摘要

A method and an apparatus for developing an electrostatic latent image by using a liquid developer in a high concentration. In order to make usable a high concentration liquid developer having a viscosity of 100 to 10,000 mPa.s, a developer layer having a thickness of 5 to 40 mu m is formed on the surface of a developing roller or a developing belt (510) and is brought into gentle contact with the surface of a photosensitive member on which an electrostatic latent image is formed. When mold releasability on the surface of the photosensitive member is not satisfactory, a pre-wet liquid film is formed on the surface of the photosensitive member (10), and the gap between the photosensitive member and the surface of the developing roller, etc, is kept at a gap which is greater than the thickness of the film of the liquid developer but is smaller than the sum of the film thickness of the liquid developer and the film thickness of the pre-wet liquid film so that the pre-wet liquid always exists between both surfaces. A pre-wet liquid having a viscosity of 0.5 to 5.0 mPa.s and a film thickness of not greater than 30 mu m is used for the developer film of the liquid developer containing a toner having a mean particle size of 0.1 to 5.0 mu m in a concentration of 5 to 40 %, and having a viscosity of 100 to 10,000 mPa.s and a thickness of 5 to 40 mu m, and the gap between the photosensitive member and the developing roller, etc, is kept between 5 and 60 mu m. In this way, an extremely satisfactory copy can be obtained. <IMAGE>