Patent ID: 8625082

Claim:
A distance measurement device for measuring distance from an object having a non-planar or curved contoured surface by irradiating a laser beam to the object, comprising: a laser light source for radiating pulse laser beam; a light source drive unit for controlling driving operation of the laser light source; a receiving unit for receiving pulse laser beam generated at the object by reflecting the pulse laser beam having been radiated from the light source; a counting unit for counting an amount of pulses of the pulse laser beams received at the receiving unit; a timing signal addition unit for generating an addition pulse signal by combining the pulse laser beam having been received at the receiving unit with a start pulse signal indicating a start timing of a distance measuring operation, and notifying the light source drive unit of a drive timing; a calculating unit for obtaining time required for transmission of a predetermined amount of pulses of laser beam reflected at the object from the start pulse signal in accordance with the predetermined amount of pulses from the start pulse signal having been counted at the counting unit, wherein the calculating unit is further arranged to calculate distance between the distance measurement device and the object by dividing the time required for transmission of a predetermined amount of pulses of laser beam by the predetermined amount of pulses, and by subtracting a delay time within circuit for obtaining reciprocating propagation time of laser beam radiated from the light source via the object, and by converting the reciprocating propagation time into distance between the light source and the object, and an interval of radiating pulses from the laser light source changes according to the distance between the laser light source and the object.