Measuring device for determining extent and direction of relative movement between two objects having modulation section
AssigneeFutaba Denshi Kogyo K.K.
InventorsNorio Kimizuka, Mituyosi Abo
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Abstract
A measuring device is disclosed which is capable of exhibiting increased resolution. The device is constructed to detect a moire fringe produced by two scales as A and B phase signals different in phase by 90.degree. and to convert each of the phase signals into a frequency-modulated signal by means of a carrier of a predetermined cycle to digitally read out the deviation of a phase varied with relative movement between both scales.
Claims5
A measuring device two output signals different in phase by 90.degree. generated from a scale section which generates one signal every unit length movement of an object to be measured, to thereby detect the amount and direction of movement of said object, comprising:
- a light source for radiating a light of constant level;
- a photoelectric transfer section for receiving the light projected from said light source through a scale section which includes a pair of optical scales and for generating two output signals different in phae by 90.degree. due to relative movement of said optical scales;
- a carrier generating section for generating a carrier signal having a frequency higher than that of said two output signals of said scale section;
- a modulation and addition section for carrying out modulation of said two output signals generated from said scale section by means of said carrier signal generated from said carrier generating section and for carrying out addition of at least said output signals to generate a modulated signal containing the amount of movement of said object as a phase component;
- and
- a counting section for counting the number of clocks of a predetermined cycle contained in one cycle of said modulated signal generated from said modulation and addition section.
Dependencies are inferred from the claim text.