Patent ID: 8072583

Claim:
A range-finding device, comprising: a light emitting unit that continuously emits measurement light to be used for distance measurement toward a measurement target object; a light-receiving unit that receives reflected light reflected by the measurement target object; a first calculation unit that repeatedly calculates a distance to the measurement target object over predetermined time intervals by using the reflected light; a display unit at which an update of the distance is displayed each time the distance is calculated by the first calculation unit; a second calculation unit that calculates a distance change between a first distance and a second distance, the first distance being calculated most recently by the first calculation unit and the second distance having been calculated previously by the first calculation unit; a decision-making unit that makes a decision as to whether or not the distance change calculated by the second calculation unit exceeds a threshold value; and a display update control unit that prohibits the update to the first distance on display at the display unit when the distance change exceeds the threshold value and sustains the display of the second distance at the display unit for a duration of a predetermined holding time.