Abstract: An ink for a liquid electrophotographic color printing system is optimized to reduce the lowering of image density due to wash-off, to obtain a stable over-toned color, and to have a wide reproducible color gamut. The ink includes a plurality of toners for yellow (Y), magenta (M) and cyan (C), each toner being provided in a respective one of a plurality of developing devices, and each toner having a pigment (p) for forming an image having a predetermined color, a binder (b) for binding the pigment on printing paper, a charge controller for imparting electrical properties on the toners, and a stabilizer. A carrier transfers the toners from the developing devices to a photoreceptor belt during development. The blending ratio (b/p) of the binder (b) to the pigment (p) of each toner for yellow (Y), magenta (M) and cyan (C) satisfies the following expressions: b/pyellow(Y)=5±1; b/pmagenta(M)=7±1; and b/pcyan(C)=8±1.

Abstract: A developing unit of a liquid electrophotographic printer includes a developing roller, for forming a development gap with a photoreceptor web where developer is filled and developing an electrostatic latent image formed on the photoreceptor web, a squeegee roller installed at the rear end of the developing roller for closely pressing the photoreceptor web to squeegee surplus developer, and a cleaning mechanism for removing toner particles of the developer adhering to a surface of the squeegee roller using an electrical force. Since the toner particles adhering to the squeegee roller are removed, contamination of a developed image is prevented and a clean image can be printed.

Abstract: A development apparatus of a liquid electrophotographic printer includes a photoreceptor web having an image area where an electrostatic latent image is formed and a non-image area at both sides of the image area. A development roller is installed to correspond to the image area to which a development electrical potential of a predetermined level is applied, in which developer is supplied to the electrostatic latent image. A squeegee roller removes developer remaining on the photoreceptor web, and an air injection nozzle is installed adjacent to both ends of the development roller. The air injection nozzle injects air to move developer remaining on the photoreceptor web from the non-image area to the image area so that a boundary line between the image area and the non-image area is prevented from being developed due to a difference in electrical potential therebetween.

Abstract: In a liquid electrophotographic imaging system including a photoreceptor medium, a laser scanning unit scans light onto the photoreceptor medium to form an electrostatic latent image on a photoreceptor surface of the photoreceptor medium. A development unit develops an image on the photoreceptor surface corresponding to an electrostatic latent image formed by the laser scanning unit with toner carried by a liquid carrier. A cabinet encloses the photoreceptor medium, the laser scanning unit, and the development unit to prevent the carrier in a gaseous state after being used during development from escaping to the outside. In the laser scanning unit including a light emitting unit, a beam deflector deflects and scans the light emitted from the light emitting unit. A housing encloses the light emitting unit and the beam deflector and has a transparent window through which the light scanned by the beam deflector passes.

Abstract: A liquid image forming apparatus includes a rotation speed detection portion provided at one side of the image drying roller for detecting a rotation speed of said image drying roller. A speed comparison portion determines whether the image drying roller is rotating at normal speed by comparing the rotation speed of the image drying roller, detected by the rotation speed detection portion, with a predetermined range of a reference rotation speed. A controlling portion makes the heating roller heat the image drying roller to a reference temperature to vaporize the liquid carrier absorbed by the image drying roller, when it is determined from a signal from the speed comparison portion that the image drying roller does not maintain the regular speed. Thus, the toner image in a damp state, which is vulnerable to damage due to friction before being dried, can be protected and a quality printed material can be obtained.

Abstract: A roller separating device automatically separates a pressure roller from a heat roller when the rollers are unable to rotate or when a fixing operation is not in progress. The roller separating device includes an idle gear engaged with a pressure roller gear, a cam driving gear engaged with the idle gear, an electronic clutch fixed to a cam shaft to which a cam is also fixed. The electronic clutch is detachably coupled to the cam driving gear. The cam is driven by a driving force of a power gear and the electronic clutch couples/uncouples the driving force to the cam. When the electronic clutch is actuated, a driving force of the cam driving gear is transferred to the cam to move a pressure roller support frame so that the pressure roller is separated from the heat roller. When the electronic clutch is inactuated, the pressure roller support frame returns to its normal position by an elastic force of a spring so that the pressure roller contacts the heat roller.

Abstract: An image forming apparatus includes a plurality of image forming units, each unit developing a latent image formed on a respective photosensitive drum with a respective color toner to form an image on a sheet of paper. The image forming apparatus includes an exposing optical device for projecting light on the photosensitive drums, a first movable mirror for reflecting the light along a first optical path and a second movable mirror for reflecting the light reflected from the first movable mirror to a selected photosensitive drum along a second optical path. The first and second movable mirrors move so that the optical path lengths are constant irrespective of the position of the selected photosensitive drum. Latent images, each having a uniform size, are formed on the photosensitive drums.

Abstract: An image forming apparatus includes a plurality of image forming units each having a photoconductive drum for forming a latent image and a developing device for developing the latent image, for providing different-color developed images, an exposing device for projecting light according to image information, and a plurality of mirror members for controlling the optical passage of the exposing device so as to expose a selected photoconductive drum without shifting the exposing device, thereby simplifying the apparatus and allowing for a stable drive.