COLOR RENDERING PROPERTY CONTROL DEVICE FOR HIGH PRESSURE SODIUM VAPOR LAMP

摘要

PURPOSE:To measure simply color rendering property of a high pressure sodium vapor lamp by obtaining luminescence energy ratio of the lamp in two wave length ranges. CONSTITUTION:The light from a high pressure sodium vapor lamp 10 passes through a filter 1 with transmission band with wave length 590nm at center and half value width of 5nm and received by a photoelectric transducer element. Its output I1 is sent to a divider 6. On the other hand the light from the lamp 10 passes through a filter 3 with transmission bands which have lambda1-lambda6 wave lengths as centers with half value width of 5nm by 5nm interval in the range of 560-585nm and received by photoelectric transducer elements d1-d6. Their outputs are inputted to a maximum value detector 6, and the maximum value I2 is sent to a divider 6, where the ratio I2/I1 is calculated. The ratio is compared by a comparator 7 with a reference voltage V0 generated by a reference voltage generator 8. If V0 is set at the same level as that which makes the value of I2/I1 at 100, the average color rendering index for I2/I1 that is larger than V0 exceeds 80 and the display element becomes ON. Accordingly the color rendering property is measured simply.