Auto focusing mechanism of surveying instrument

Abstract

The invention is able to detect that a focusing lens is positioned on a focusing position surely and quickly. In a step for moving the focusing lens 21b by a motor 41 along an optical axis of a collimation optical system, an object image following collimation of a telescope 20 is converted into an electric signal by a line sensor 24, and an output signal from the line sensor 24 is converted into a digital signal by an A / D converter 27 and stored in a RAM 28, and the frequency of the electric signal by the output from the line sensor 24 is monitored in a microcomputer 3 based on data stored in the RAM 28. In a step wherein the position of the focusing lens 21b is changed, when a specific frequency correlated with the position of the focusing lens 21b is detected, the distance from the telescope 20 to a staff 1 is determined based on the output signal from the line sensor 24 by assuming that the focusing lens 21b is positioned approximately on the focusing position, and the focusing lens 21b is positioned on the focusing position from the distance and the position of the focusing lens 21b by the output from a position sensor 5.

Description

technical field [0001] The present invention relates to an automatic focus mechanism of the measuring machine, which is installed on a measuring machine such as an electronic level with a telescope for parallelizing the scale, and can automatically align the focus of the telescope with the scale. Background technique [0002] As an automatic focus mechanism installed on an electronic level, for example, there are Figure 10 , Figure 11 mechanism shown (see Patent Document 1). The automatic focus mechanism is installed on the telescope 20 as a horizontal correction optical system, and the telescope 20 has an automatic compensation mechanism 22 of an objective lens 21a, a focusing lens 21b, a horizontal correction axis, a beam splitter 23, a focus plate 20a, and an eyepiece 20b, This automatic focus mechanism has a stepping motor 41 for moving the focus lens 21b along the optical axis of the horizontal optical system, a drive circuit 4 for controlling the driving of the step...

AI Technical Summary

Problems solved by technology

[0008] That is, in the case of processing the output signal of the line sensor 24, if an arithmetic process of calculating the pitch of the pattern on the scale is performed based on erroneous data or data with a low signal level, errors in distance measurement results, Or the problem of deterioration of ranging accuracy

[0009] As a result, autofocus, which is a process for automatically focusing the telescope 20 on the scale, fails, so that the processing time of autofocus becomes longer, the operation efficiency is reduced, or the precision of autofocus is deteriorated to cause measurement failure. Results are badly affected

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