| 摘要 |
PURPOSE:To rapidly obtain an accurate measure value, by calculating the measured value of the quantity of incident light on the basis of the electric signal from a photoelectric converter part and correcting the error due to internal parts and the error of spectral sensitivity on the basis of both of a calibration reference value and a correction factor. CONSTITUTION:Incident light enters a photodiode 2 through a filter 3 correcting the spectral sensitivity of the photodiode 2 to standard relative luminosity and is converted to an electric signal by a photoelectric converter circuit 1. Said signal is converted to a digital signal by an A/D converter circuit 4 to be applied to a CPU 9 and brightness is calculated. At this time, when the output of the circuit 4 is a predetermined level or more, an over judge circuit 5 is operated. A key operation part 6 has both functions as a calibration reference value input means for calibrating a measured value containing the inherent error due to internal parts and a correction factor input means for correcting the error of spectral sensitivity generated corresponding to the color temp. of a light source. A selection circuit 8 selects an operation program from PROM 7 corresponding to the set mode determined by the operation of the operation part 6 and a result is displayed on internal and external displays 12, 13 respectively.
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