GB1230184A - - Google Patents

Abstract

1,230,184. Electrostatic imaging method. XEROX CORP. Aug. 6, 1968 [Aug. 7, 1967], No. 37508/68. Heading G2H. An electrostatic imaging method comprises the steps of (a) providing an imaging member comprising a supporting substrate, an overlayer of an electrically insulating softenable material containing photo-conductive fracturable material, (b) uniformly electrostatically charging the said member, (c) exposing the said member to a first pattern of actinic radiation, (d) softening the softenable layer, and (e) exposing the said member to a second pattern of actinic radiation, one of the patterns being an imagewise pattern and the other being a uniform pattern. The substrate 11 of the member 10 is preferably conductive to facilitate charging but may be insulative. The softenable layer 12, thickness 0À5-16Á, is of an insulating material which is softenable or soluble in a solvent liquid or vapour or heat. The material 13 is preferably particulate and typically an inorganic or organic photoconductive insulator. In a layered structure, as shown, its thickness is preferably in the range 0-01 to 2À0Á. The material 13 may, however, be dispersed in the material 12 or may be sandwitched between two layers of the same. After charging by corona discharge either positively (preferably to 100-300 volts) or negatively (25-150 volts), the member 10 is imagewise exposed in the range 0-6 f.c.s. In the illuminated areas the surface charge may be considered to have become attached to the layer 13, Fig. 3. On softening the layer 12 by heating, by means of resistance element 18, Fig. 4, the charge held by layer 13 is transferred to the layer 12. After cooling, a uniform exposure is applied in order to transfer the remaining surface charge to the layer 13, Fig. 5, the exposure value being in the range from about 1 to 10 times greater than the imagewise exposure. The latent image is developed by dissolving away the layer 12 to permit charged portions of the layer 13 to migrate in image configuration to the substrate 11. Development may also be effected by softening the layer 12 by vapour or heat. In the above described sequence a positive image is obtained. If the uniform exposure is applied before the imagewise exposure a negative image is obtained.