| 摘要 |
912,321. Cathode-ray tubes. AGFA A.G. March 26, 1959 [March 27, 1958], No. 10686/59. Addition to 902,384. Class 39 (1). [Also in Group XL (b)] Apparatus as described in the parent Specification for controlling a beam of light utilizing the change in the refraction index of a medium (a colloid or solubilized system) consequent upon a change in the concentration of the medium when subjected to an electric field, is characterized by the use of an alternating potential to create the electric field, means being provided for adjusting the alternating potential so that, in the absence of a controlling influence, a symmetrical alternating current (i.e. a current having equal positive and negative amplitudes) flows through the medium. The invention ensures that no change of concentration takes place and no control of the light is effected in the absence of a controlling influence. The apparatus illustrated comprises an image intensifier or image converter for controlling light 18 by radiation 17, e.g. visible light, infra-red rays, ultra-violet rays, X-rays or electrons. Located between electrodes 1 and 8 are a solution 6, which may be a colloidal solution, a membrane 3, a colloidal solution 5 divided into elemental sections by insulating portions 4, an electrode 2 and a radiation responsive semi-conductor 7. In accordance with the invention, the electric field for operating the aparatus is supplied by an alternating potential 10 which is applied via oppositely connected rectifiers 15 and 16 and resistors 11 and 12 which are adjusted so that, in the absence of radiation 17, a symmetrical alternating current flows. Preferably, electrode 2 is made opaque to prevent the controlled light 18 from influencing semiconductor 7. Electrode 8 is a thin metal layer transparent to radiation 17; where the radiation is electrons, the layer may be replaced by a wire gauze. Where the semi-conductor 7 does not exhibit a rectifying characteristic, reference is made to the inclusion of a rectifier in the apparatus in the form of a blocking layer located either between electrode 8 and layer 7 or between layer 7 and electrode 2. |
