摘要:
A photoconductive photosensitive member (2) and a charge retaining medium (1), which face one another at a predetermined interval, are exposed to light while a voltage is applied between them from an external power source (E). The discharge occurring in the exposed areas produces an electrostatic image on the charge retaining medium. In this method, the applied voltage is removed a predetermined time after a shutter (13) is closed so that all the carriers generated in the photosensitive member can be transferred to the charge retaining medium. Accordingly, the quantity of charge corresponding to an exposure quantity is stored in the charge retaining medium irrespective of the kind of the photoconductive member used. If the charge retaining medium or photosensitive member is charged in advance in this case, a positive image can be obtained with the external power source disconnected. Alternatively, the applied voltage may be removed after the photosensitive members are separated from the charge retaining member on which an electrostatic charge image has been formed. In this case, the image is prevented from distortion. On the other hand, if a spacer for keeping the photosensitive member and the charge retaining member in a spaced-apart relation is formed integrally with either the photosensitive member or the charge retaining medium, the discharge gap can easily be kept constant. Further, if the electrode of the photosensitive member or that of the charge retaining medium at a spacer portion is removed, it is effective to prevent dielectric breakdown which may be caused through the spacer.
摘要:
A monolithic sensor (10) is constituted by epitaxially growing a high-resistance compound semiconductor (12) on a low-resistance compound semiconductor (11), and further forming a reflecting dielectric film (13) thereon. The low-resistance compound semiconductor (11) has a large band gap so that the probe light is not absorbed but passes therethrough. The semiconductor (11) has a lattice constant and a coefficient of thermal expansion close to those of the high-resistance compound semiconductor, and a resistivity of smaller than 10 ohm.cm so that it can also be used for an electrode. The high-resistance compound semiconductor (12) has a large band gap so that light of a short wavelength can be used, since a change in retardation increases with the decrease in the wavelength of the probe light. The semiconductor (12) has a large electro-optical constant and a resistivity of greater than 10 ohms.cm. Therefore, a sensor is constituted maintaining good workability and very high surface accuracy permitting less optical deterioration.