Ranging apparatus, ranging method, and opto-electric conversion circuit

Abstract

A ranging apparatus 1 comprises a laser light emitter 3 for emitting pulsed laser light, a reflected light receiver 4 for receiving reflected light, a distance computer 10 for finding the distance from the elapsed time until the reflected light is received, and a distance display 8 for displaying this distance. The distance computer 10 has a counter 11 for counting the frequency when the reflected light satisfies a specific condition, a table production component 12 for producing a frequency distribution table corresponding to distance by adding up the counts, a distance determiner 13 for determining as the distance to the object of measurement the point when the frequencies in the frequency distribution table exceed a threshold, and a distance selector 15 for selecting a specific distance when a plurality of distances are determined, and displaying this distance on the distance display 8. As a result, when a plurality of distances are calculated, these distances can be appropriately displayed, improving the flexibility and functionality.

1 - 42 . (canceled)  
   
   
       43 . An opto-electric conversion circuit in which an avalanche photodiode is used, 
 wherein this opto-electric conversion circuit comprises: a reverse bias voltage regulating component for regulating the reverse bias voltage applied to the above-mentioned avalanche photodiode; a current measurement component for measuring the current flowing to the above-mentioned avalanche photodiode;    a reference reverse bias voltage detecting component for regulating the above-mentioned reverse bias voltage and detecting the reverse bias voltage at which a specific current flows to the above-mentioned avalanche photodiode (reference reverse bias voltage); and    a reverse bias voltage setting component for adjusting the reverse bias voltage applied to the above-mentioned avalanche photodiode during opto-electric conversion to a voltage obtained by multiplying the above-mentioned detected reference reverse bias voltage by a specific ratio.    
   
   
       44 . A laser ranging apparatus which measures the distance to an object of measurement by radiating laser light toward the object of measurement and measuring the time differential between the point when the laser light is radiated and the point when the laser light reflected back from the object of measurement is received, wherein the circuit for detecting the receipt of laser light reflected back from the object of measurement has the opto-electric conversion circuit according to  claim 43 .  
   
   
       45 . The ranging apparatus according to  claim 44 , wherein the above-mentioned reverse bias voltage setting component is actuated before the start of every measurement or every time the power to the apparatus is switched on.