Distance measuring device

A distance measuring device that measures a distance to an object using a round-trip time of light in a background light environment in which a quantity of background light fluctuates periodically, the distance measuring device comprising:

• a light emitter including a light source that radiates light to a measurement target range;
• a solid-state image sensor that includes a plurality of pixels included in a plurality of pixel groups capable of being exposed independently, and causes the plurality of pixels to perform photoelectric conversion of reflected light from the object within an angle of view of radiation light from the light emitter, the plurality of pixels being arranged in a matrix;
• a light emission and exposure controller that (i) instructs a light emission timing and a light emission period of the light source to the light emitter, (ii) instructs, to each of the plurality of pixel groups in the solid-state image sensor, an exposure timing and an exposure period for obtaining pixel signals of types corresponding to a time difference between the radiation light and the reflected light due to a round-trip time of light, and (iii) intermittently exposes the plurality of pixels by exposing each of the plurality of pixel groups at a different exposure time in at least two cyclic exposure periods in a light quantity fluctuation cycle period of the background light according to the exposure timing and the exposure period without changing total cyclic exposure periods, the pixel signals of the types corresponding to the time difference between the radiation light and the reflected light;
• and
• a signal processor that calculates a distance value of the object of which an image is formed by the solid-state image sensor, according to pixel signals of at least two adjacent pixels exposed at the different exposure times for each of the plurality of pixel groups in the solid-state image sensor, the pixel signals corresponding to the time difference,
• wherein the light emission and exposure controller causes the light emitter to intermittently radiate the light in at least two emission periods within the light quantity fluctuation cycle period.