ILLUMINANCE SENSOR CHIP, ILLUMINANCE SENSOR, EQUIPMENT AND METHOD FOR MEASURING ILLUMINANCE

摘要

PROBLEM TO BE SOLVED: To provide a technology for measuring the illuminance reflecting the quantity of visible light advantageously from the view point of cost. SOLUTION: The illuminance sensor chip comprises a first semiconductor layer, and a second semiconductor layer joining with the first semiconductor layer. When light impinges on the joining part of the first and second semiconductor layers through the second semiconductor layer, the illuminance sensor chip outputs an electric signal corresponding to the quantity of light impinging on the joining part. Thickness of the second semiconductor layer is set at 2-4 μm, for example, so that the peak sensitivity wavelength in the spectral sensitivity characteristics with reference to the output level of the electric signal falls within the wavelength range of visible light (e.g. 580-600 nm). The second semiconductor layer is constituted as silicon semiconductor and the illuminance sensor is constituted as a phototransistor having an npn junction.