Patent ID: 7446863
Filing Date: 2008-11-04
Classification: G01C

Abstract:
1. An automatic collimation device for a surveying apparatus comprising: an imaging device that images a target captured by a telescope and surroundings of the target; a drive unit that rotates the telescope; a light emitting unit that sends light toward the target; a microcomputer electrically connected to the drive unit, and an arithmetic control unit connected to the microcomputer that determines a position of the target based on a difference between a lit image of the target obtained as a result of imaging by the imaging device when the light emitting unit has been turned on and an unlit image of the target obtained as a result of imaging by the imaging device when the light emitting unit has been turned off and controls the drive unit to automatically collimate the target without the need for a horizontal and vertical angle detectors, wherein the arithmetic control unit carries out a correlation operation between the lit image and unlit image so as to determine a position where both images are most coincident, by instructing the microcomputer to operate the drive unit to move the telescope in a direction wherein the brightness of overlapping pixels between the lit image and unlit image increases, and to stop the drive unit when the brightness of overlapping pixels is maximized whereupon the target image is collimated, and determines a position of the target based on a difference between both images at the position where both images are most coincident while the drive unit rotates the telescope, and wherein the correlation operation is carried out while shifting either the lit image or unlit image, and the amount to be shifted during this time is limited to multiple shift distances determined by a control signal transmitted from the arithmetic control unit to the drive unit, wherein the arithmetic control unit iteratively computes different multiple shift distances as said lit and unlit images correlate.