Laser range finding device and distance measurement method thereof

Abstract

A distance measurement method for use in a laser range finding device to measure a distance between the laser range finding device and a target is disclosed. The method comprises the following steps. A laser signal is sent to the target in a first time point. A reflected laser signal reflected by the target is then received. A digital signal having a plurality of signal values ranging from 0 to N is obtained by sampling the reflected laser signal with a sampling signal, wherein N is an integer larger than two. A maximum signal value among the signal values is obtained. The distance is calculated according to the first time point and a second time point where the maximum signal value is generated.

1 . A distance measurement method for use in a laser range finding device to measure a distance between the laser range finding device and a target, comprising:
 transmitting a laser signal to the target at a first time point;   receiving a reflected laser signal reflected by the target;   generating a digital signal by sampling the reflected laser signal and creating a plurality of different non-zero magnitude values for the digital signal that are each associated with a time for the received reflected laser signal and have a magnitude that corresponds to a magnitude of the received reflected laser signal at the associated time; and   calculating the distance between the laser range finding device and the target based on the generated digital signal.   
     
     
         2 . The method of  claim 1 , wherein:
 the digital signal is generated based on one reflected laser signal.   
     
     
         3 . The distance measurement method of  claim 1 , wherein:
 the digital signal is a signal with eight bits per data value.   
     
     
         4 . The distance measurement method of  claim 1 , wherein:
 the digital signal is a signal with more than one bit per data value.   
     
     
         5 . The distance measurement method of  claim 1 , wherein:
 the digital signal is generated by sampling the reflected laser signal with a sampling signal.   
     
     
         6 . The distance measurement method of clam  1 , wherein:
 the generated digital signal has a waveform that is similar to a waveform of the received reflected laser signal.   
     
     
         7 . A laser range finding device for measuring a distance between the laser range finding device and a target, comprising:
 a transmitter that transmits a laser signal to the target at a first time point;   a receiver that receives a reflected laser signal reflected by the target;   an analog-to-digital converter that samples the reflected laser signal and generates a digital signal by sampling the received reflected laser signal and creating a plurality of different non-zero magnitude values that are each associated with a time for the received reflected signal and have a magnitude that corresponds to a magnitude of the received reflected laser signal at the associated time such that the generated digital signal has a waveform that is similar to a waveform of the received reflected laser signal; and   a processing unit that calculates the distance between the laser range finding device and the target based on the generated digital signal.   
     
     
         8 . The laser range finding device of  claim 7 , wherein the transmitter comprises:
 a laser diode; and   a driving circuit that controls the laser diode to transmit the laser signal to the target.   
     
     
         9 . The laser range finding device of  claim 7 , wherein the receiver comprises:
 an avalanche photodiode that receives the reflected laser signal reflected by the target;   a signal amplifier that amplifies the reflected laser signal received by the avalanche photodiode; and   a filter circuit that performs a noise filtering to the amplified reflected laser signal.   
     
     
         10 . The laser range finding device of  claim 7 , further comprising:
 a memory unit in communication with the processing unit, the memory unit stores the digital signal; and   a control circuit in communication with the processing unit, the control circuit receives a trigger signal from the processing unit so as to drive the transmitter to transmit the laser signal and activate the analog-to-digital converter.   
     
     
         11 . The laser range finding device of  claim 7 , further comprising:
 a displaying unit coupled to the processing unit for displaying the distance between the laser range finding device and the target calculated by the processing unit.   
     
     
         12 . The laser range finding device of  claim 14 , wherein:
 the digital signal is a signal with more than one bit per data value.   
     
     
         13 . The laser range finding device of  claim 7 , wherein:
 the digital signal is a signal with eight bits per magnitude for the plurality of different non-zero magnitude values.   
     
     
         14 . The laser range finding device of  claim 7 , wherein:
 the analog-to-digital converter samples the reflected laser signal with a sampling signal to generate the digital signal.   
     
     
         15 . The laser range finding device of  claim 7 , wherein:
 the analog-to-digital converter generates the digital signal based on one reflected laser signal.   
     
     
         16 . A distance measurement method for use in a laser range finding device to measure a distance between the laser range finding device and a target, comprising:
 transmitting a laser signal to the target at a first time point;   receiving a reflected laser signal reflected by the target;   generating a digital signal having a plurality of signal values by sampling the reflected laser signal, the signal values range from 0 to N where N is a positive integer greater than two; and   calculating the distance between the laser range finding device and the target based on the generated digital signal.   
     
     
         17 . The method of  claim 16 , wherein:
 the digital signal is generated based on one reflected laser signal.   
     
     
         18 . The distance measurement method of  claim 16 , wherein:
 the digital signal is a signal with more than one bit per data value.   
     
     
         19 . The distance measurement method of  claim 16 , wherein:
 the digital signal is generated by sampling the reflected laser signal with a sampling signal.   
     
     
         20 . The distance measurement method of  claim 16 , wherein:
 the generated digital signal has a waveform that is similar to a waveform of the received reflected laser signal.