| 摘要 |
<p>1,072,240. Electro-optical oscillator circuits. NATIONAL CASH REGISTER CO. Dec. 23, 1965 [Jan. 25, 1965], No. 54521/65. Heading H3T. A variable frequency oscillator comprises a chain of stages each including a photo-sensitive element and a light-emitting element each stage being arranged to transmit a signal with a delay, and a feedback circuit from a selectable point in the chain to cause the circuit to oscillate at a frequency depending upon which point in the chain is selected. In Fig. 1, when electroluminescent element EL2 emits light the photo-conductor PC1 causes EL1 to emit light so that in this manner the luminescent elements of the chain successively emit light. When stage T3 emits light a photoresistor PC2.3 effectively short-circuits EL2, extinguishing luminescent device EL2 and the others in succession. Accordingly a continuous pulse train may be derived from a photo-conductor PC4. By moving switch S2 to select an alternative feedback point the frequency of oscillation may be varied. The individual stages of the chain may be made regenerative. Thus in Fig. 2 (not shown) a photo-conductor is inserted between PC1 and EL1 of each stage and illuminated by EL1 to provide the regeneration. In Fig. 3 (not shown), a photo-conductor (PC7) is connected in parallel with each photo-conductor PC1 (now referenced PC6) and this is illuminated by the associated electroluminescent device to provide the regeneration. In Fig. 4 each stage comprises two electroluminescent devices and two photoconductors, the regenerative feedback occurring between device EL5 and photo-conductor PC12. The light coupling between the stages may be replaced by an electric coupling if (as in Fig. 5) a pair of electroluminescent devices (PC18, PC19) are provided in each stage to receive the output from the luminescent elements and a connection is made between the mid-point of the pair and the mid-point of the succeeding stage.</p> |
