Absolute type grating ruler and measurement method

Abstract

The invention discloses an absolute type grating ruler and a measurement method thereof. The absolute type grating ruler comprises a parallel light source module, a scale grating, a photoelectric detector and a signal processing module; the scale grating is provided with a basic track and a plurality of coding tracks; the basic track comprises a grating stripe which is inclined relative to the measurement direction; each coding track comprises a plurality of grating stripes which are uniformly and periodically arranged and inclined relative to the measurement direction; each coding track has a different period; parallel light beams emitted by the parallel light source module are radiated to the photoelectric detector after passing through the scale grating; the photoelectric detector is used for collecting arrival light signals and transmitting the measurement electric signals to the signal processing module after converting the arrival light signals to measurement electric signals ; and the signal processing module is used for obtaining measurement values a plurality of the coding tracks after performing processing and analyzing on the measurement electric signals and then obtaining the absolute position measurement value through calculation. The absolute type grating ruler and the measurement method are low in etching difficulty, reduce the manufacture cost, have high measurement accuracy and can be applicable to the grating measurement industry.

Description

technical field [0001] The invention relates to the field of grating ruler measurement, in particular to an absolute grating ruler and a measuring method thereof. Background technique [0002] At present, the commonly used grating rulers can be divided into three types: incremental grating rulers, semi-absolute grating rulers and absolute grating rulers, which are widely used in the CNC machine tool manufacturing industry. The incremental grating scale is the most commonly used high-precision measuring device. It has an absolute zero mark, and the scale grating is equidistantly distributed thereafter. The reading head moves relative to the scale grating, and the Moiré fringes formed by the passing grid will pass through the electrical signal processing to get the distance relative to absolute zero. This measurement mode is simple and easy to implement, but in use, it is difficult to greatly improve the work efficiency because it must be recalibrated every time it returns to...

AI Technical Summary

Problems solved by technology

However, the main disadvantage of the absolute grating ruler is that it is slow in high-precision measurement, and the error rate is high when decoding. Moreover, the distance between the grid lines on the code track of the current absolute grating scale is very small, and the higher the precision required, the grid lines The smaller the spacing needs to be, the greater the production cost, and this method has limitations in the encoding range, which limits the expansion of the measurement range, and the slight manufacturing error of the grating code track will advance or delay individual code tracks. This will eventually cause measurement errors

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