SU1310633A1 - Device for measuring linear displacements - Google Patents

Abstract

This invention relates to a measurement technique. The aim of the invention is to improve the accuracy of the formation of the reference signal due to the increase in the signal-to-noise ratio. The light source 1 forms beam beams directed to the main and additional diffraction gratings 4.5j657j8.9 applied to the mobile and stationary elements 2,3. Additional diffraction gratings 6, 7, 8, 9 are deposited with a linearly varying spatial frequency. Photoreceivers 10, 11, 12, 13 installed in the zone of forming the first-order diffraction maxima convert the radiation flux into electrical signals converted by the measuring unit. pulses, the number of which is related to the magnitude of the linear displacement of the movable element 2. The photodetectors 14 and 15, installed in the zone of formation of diffraction max. 1 {first order order, convert the radiation flux into an electrical signal s that are amplified and detected by amplifiers, threshold detectors. The adder and the differential amplifier form the sum and difference signals. The delta signal is gated by the AND element and inverted or not inverted by the controlled inverter, the control signal of which is generated by the movement direction detection unit. The shaper forms a pulse signal of origin of the reference, 1 hp f-ly. 3 il. with S DO С5 WITH WITH 7 phi 1

Description

The invention relates to a measurement technique and can be used to measure linear movements of various objects.

The aim of the invention is to increase the accuracy of the origin of the reference signal by increasing the signal-to-noise ratio.

FIG. 1 shows a functional diagram of the optical-mechanical part of the device; in fig. 2 - functional diagrams of the measuring unit and the unit for starting the reference signal; in fig. 3 - timing diagrams of signals generated at the outputs of individual nodes of the device.

The proposed device contains optically coupled light source 1 mobile and stationary elements 2 and 3 with a main diffraction grating 4 and 5 applied to each of them with a constant spatial frequency and additional diffraction gratings 6-9 with a linearly varying spatial frequency, grating 6 and 7 are offset with respect to diffraction gratings 8 and 9, the main phototransducer, made in the form of photodetectors 10-13, optically coupled to the main diffraction gratings 4 and 5, an additional photoconversion A camera, made in the form of photodetectors 14 and 15, optically connected with additional diffraction gratings 6.7 and 8, 9, measuring unit 16, consisting of an information pulse extraction unit 17, whose inputs are connected to photodetectors 10-13, a node 18 determining the direction of movement, the inputs of which are connected to the outputs of the information pulse output unit 17, the block 19 of the reference signal, which consists of amplifiers 20 and 21, the inputs of which are connected to the photoreceivers 14 and 15, the threshold detectors 22 and 23, the inputs of which

The signals from the outputs of amplifiers 20 and 21 are detected by threshold detectors 22 and 23, which do not transmit noises and pickups, and are directed to the outputs of amplifiers 20 and 21, adder 24 and differentials of adder 24 and differential amplifier 25, whose inputs the amplifier 25. The adder 24 forms connected to the outputs of the threshold detectors 22 and 23 of the element I, the inputs of the measurement gate, and the differential amplifier 25 a differential signal supplied to the input of the element 26 And, the second input of which receives a signal from the output of the adder 24.

then connected to the output of the adder 24 and the differential amplifier 25, element 26 And, controlled by the inverter 27, the information input of which is connected to the output of element 26 And, and the control input connected

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to the output of the node 18 for determining the direction of movement, the driver 28, the input of which is connected to the output of the controlled inverter 27.

The photodetectors 14 and 15 are located in the zone of formation of the first-order diffraction maxima of the additional diffraction lattice currents of 6.7 and 8.9.

The proposed device works as follows.

The light source 1 forms beam beams directed to the main and additional diffraction gratings 4–9 applied to the moving and stationary elements 2 and 3.

When moving the movable element 2 relative to the fixed element 3 at the output of the photodetectors 10-13, signals are formed that are shifted relative to each other by 90.

The signals taken from the photodetectors 10-13, are fed to the inputs 17 of the information pulses, 5 included in the measuring unit 16.

Depending on the direction of movement of the movable element 2 relative to the fixed element 3, pulses are formed at one of the outputs of the section 17 of the injection of informational impulses, the number of which is related to the linear displacement of the movable element 2.

. The direction of movement is fixed by the movement direction determination unit 18.

When combining additional diffraction gratings 6.7 and 8.9 at the output of the photoreceivers 14 and 13, the signals are shifted in phase relative to each other, which are amplified by amplifiers 20 and 21, included in block 19 of the reference signal.

The signals from the outputs of the amplifiers 20 and 21 are detected by the threshold detectors 22 and 23, which do not let through noise and pickup, and are directed to the inputs of the adder 24 and the differential amplifier 25. The adder 24 forms

d the adder 24 and the differential amplifier 25. The adder 24 forms

the measurement strobe, and the differential amplifier 25 is a difference signal, which is fed to the input of element 26 I, the second input of which receives a signal from the output of the adder 24.

The probed element 26 AND the difference signal is fed to the information input of the controlled inverter 27, the control input of which receives a signal from the output of the node 18 for determining the direction of travel.

On the leading edge of the signal taken from the output of the controlled inverter 27, the driver 28 generates a short pulse of the reference signal, which arrives at the output of the unit for the selection of the signal of the reference signal.

When the moving direction of the moving element 2 changes relative to the stationary element 3, an inverted control signal is generated at the output of the movement direction determination unit 18, which invert the inverted difference signal from the output of the differential amplifier 25 at the output of the controlled inverter 27 on the falling edge of the signal taken from the output of the controlled inverter 27.

The use of the proposed device allows to form the origin signal with high accuracy regardless of the direction of displacement. object.

Claims (2)

1. A device for measuring linear displacements containing an optically coupled light source, moving and stationary elements, each of which has a main grating with a constant spatial frequency of the strokes and an additional grating with a varying spatial frequency of the strokes, the main and additional photoconverters optically connected taken with the main and additional gratings, the measuring unit, the inputs of which are connected to the main phototransducer, including the node for determining the direction of the variable The unit is allocated and a signal of origin, the input of which is connected to an additional photovoltaic converter, characterized in that, in order to increase the accuracy of the formation of the signal of origin, each of the additional arrays is made in the form of two diffraction gratings with a linearly varying spatial frequency shifted relative to friend, additional photoconverter. is located in the zone of formation of the diffraction maxima of the first order of additional gratings. 2. The device according to claim 1, characterized in that the additional phototransducer is made in the form of two photodetectors, the unit for selecting the start signal is made in the form of an adder, a differential amplifier whose inputs are connected to photodetectors, an element whose inputs are connected to the output of the adder and a differential amplifier controlled by an inverter, the information input of which is connected to the output of the element I, and the control input is connected to the output of the node determining the direction of movement of the driver, the input of which is li ne to the output of the controlled inverter. Om15 -AND 2 nJ: gz - h; | рL. I Phil 2 if i f  Xj 7 . L H-f 27 Editor L. Povhan Compiled by T. Aisin Tehred A. Kravchuk, Proofreader L, Patay Order 1879/36 Edition 678 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 28 - / mH fiez