| 摘要 |
PROBLEM TO BE SOLVED: To provide a light quantity measuring instrument which is capable of improving measurement accuracy by controlling measurement sensitivity for each color of red, green, and blue, even when the light quantities of a plurality of color light beams emitted from a light source and having an energy difference are measured by one photosensor and to provide a projection type display device including the light quantity measuring instrument.SOLUTION: The light quantity measuring instrument includes an optical semiconductor, an amplifying element, a resistance unit, an A/D converter, and a control part. The optical semiconductor receives a plurality of color light beams radiated from a light source in a time division manner. The amplifying element receives the plurality of color light beams, to convert a photoelectric current flowing in the optical semiconductor into a voltage. The resistance unit switches a gain for converting the photoelectric current inputted to the amplifying element into the voltage for each of the plurality of color light beams. The A/D converter converts the voltage outputted by the amplifying element from an analog signal to a digital signal. The control part controls the resistance unit, so that an output level corresponding to light of each color from the A/D converter becomes almost constant. |
