Light wave distance meter

A light wave distance meter comprising:

• a distance measuring light-emitting unit that includes a light-emitting element and emits a distance measuring light by driving the light-emitting element;
• a light-receiving signal generating unit including a light-receiving element that receives a reflected light from a measurement target and transmits a light-receiving signal;
• and
• a control arithmetic unit that computes a distance to the measurement target based on the light-receiving signal, wherein
• the distance measuring light-emitting unit further comprises:
• a reference signal generator configured to transmit a reference frequency signal, which is a continuous signal of a predetermined reference frequency;
• a frequency divider configured to generate a first modulation signal modulated with a first frequency using the reference frequency signal and a second modulation signal modulated with a second frequency which is adjacent to the first frequency, and to generate a first pulse modulation signal by pulsing the first modulation signal and a second pulse modulation signal by pulsing the second modulation signal;
• a phase shifter configured to generate a third pulse modulation signal by shifting the first pulse modulation signal by time equivalent to 2π·n−π/2 or 2π·n+π/2, and a fourth pulse modulation signal by shifting the second pulse modulation signal by time equivalent to 2π·n−π/2 or 2π·n+π/2;
• and
• a light emission driving unit configured to drive the light-emitting element based on the first pulse modulation signal, the second pulse modulation signal, the third pulse modulation signal and the fourth pulse modulation signal, and to alternately emit, by time division, a first distance measuring light based on the first pulse modulation signal, a second distance measuring light based on the second pulse modulation signal, a third distance measuring light based on the third pulse modulation signal, and a fourth distance measuring light based on the fourth pulse modulation signal, wherein
• the light-receiving signal includes:
• a first intermittent light-receiving signal corresponding to the first distance measuring light;
• a second intermittent light-receiving signal corresponding to the second distance measuring light;
• a third intermittent light-receiving signal corresponding to the third distance measuring light;
• and
• a fourth intermittent light-receiving signal corresponding to the fourth distance measuring light, wherein
• the control arithmetic unit executes an error determination control to acquire a shift signal generated by shifting at least a phase of any one of the first to fourth intermittent light-receiving signals by 2π·n−π/2 or 2π·n+π/2, and compares the phase of the shift signal and the phase of the intermittent light-receiving signal at least between either the first frequencies or between the second frequencies, and executes a control to match the center position between the first intermittent light-receiving signal and the third intermittent light-receiving signal, and the center position between the second intermittent light-receiving signal and the fourth intermittent light-receiving signal.