Detection and data processing of linear scale ！

Electronic subdivision and sentenced to the law
The essence of the grating measuring displacement is a standard ruler grating lattice spacing para weighing measurement.High resolution raster ruler general cost is expensive, and makes them.In order to improve the system resolution, need of moire fringe subdivision, the grating ruler (2006) sensor system using electronic subdivision method.When two pieces of grating with small Angle overlap, in a direction perpendicular to the grating groove is roughly will generate moire fringe, with the moving of the grating, moire fringe is moved up and down.Thus the lattice spacing of grating measurement is converted into a number of moire fringe measurement.linear scale
Within a moire fringe width, according to a certain interval placed four photoelectric device can realize electronic division and sentenced to function.For example, the grid line of 50 lines/mm grating ruler, the grating lattice spacing of 0.02 mm, if adopted four subdivision resolution of 5 microns can be got after count pulse, it is common in industry measurement and control has reached a very high precision.Due to the displacement is a vector, that is, to test its size, and to test its direction, so the photoelectric scale signal of at least two different road phase.In order to eliminate common-mode interference, dc component and harmonics, usually adopt composed of low drift op-amp differential amplifier.Obtained by four photosensor 4-way photoelectric signal to two differential amplifier input respectively, two road from differential amplifier output signal phase difference of PI / 2, to get to and count pulse, for the two way signal is plastic, plastic them, first of all, for the square wave duty ratio of 1:1.Then, by comparing the phase of the wave for the discriminant, can wait until the moving direction of the grating ruler.By the other party wave pulse count, can wait until the displacement and speed of the grating ruler.

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