| 摘要 |
PURPOSE:To make it possible to correct automatically a photoelectric element with a high precision in a simple circuit constitution by storing sensitivity differences among plural photoelectric elements as digital signals and converting them to analogue signals and feeding back these analogue signals. CONSTITUTION:Photoelectric elements 1 and 2 which detected detection light 3 having the same light quantity convert detection light 3 to currents I1 and I2 respectively, and these currents are converted to voltages V1 and V2 by voltage- current converter circuits 4 and 5, and difference voltage V3 between them is obtained by voltage differential amplifier 6. This voltage is converted to digital signals and is stored in storage circuit 8 as information of sensitivity error by sensitivity correction start signal 11. This information is converted to analogue voltage V4 and is converted to current I3 by current-voltage converter circuit 10; however, relation I3=I2-I1 is obtained by arranging conditions of respective circuits. Then, when this current is fed back, I1+(I2-I1)=I2 is true, thus correcting lement 1 for element 2. |
