SU1735711A1 - Device for displacement measuring - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to improve the measurement accuracy by improving the temperature stability of the circuit stabilizing the sensitivity of the device. The light source generates a flux of radiation that is modulated by the intensity of the measuring grid 3, the indicator grids 7-10, extended reference lines 4 and 5, windows 11-13 when moving the movable element 2 relative to the fixed element. Signals are removed from the four-quadrant photodetector. At the output of the first differential amplifier, a signal is generated associated with the amount of movement of the moving element 2. At the output of the second differential amplifier, a two-pole signal is formed, the sign of which is associated with the displacement of the moving element 2 relative to the middle position. signals proportional to the power of the radiation flux generated by the light source. The components associated with the dark currents are subtracted in the third differential amplifier. The radiation power regulator maintains the sensitivity of the device unchanged. 3 il. "W fe

Description

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

The purpose of the invention is to improve the measurement accuracy by improving the temperature stability of the stabilization circuit and the sensitivity of the device.

Figure 1 shows the functional diagram of the device; figure 2 - constructive implementation of the fixed and movable elements; on fig.Z - time diagrams of signals generated at the outputs of individual nodes of the device.

The device contains optically coupled light source 1, a movable element 2 with an applied measuring grid 3 and two extended reference lines 4 and 5, a fixed element 6 with applied indicator grids 7-10 shifted one relative to the other by half the grid period on a fixed element 6 has two windows 11 and 12 optically connected with two extended strokes 4 and 5 of reference, and an additional window 13, the width of the additional window 13 is equal to the period of strokes of the measuring grid 3, lens 14, four-quadrant Photodetector 15 with photosensitive pads 16-19, first differential amplifier 20 and first adder 21, whose inputs are connected to photosensitive pads 17 and 18, second adder 22, differential amplifier 23, whose inputs are connected to photosensitive pads 16 and 19, third differential amplifier 24, the inputs of which are connected to the outputs of the first 21 and second 22 adders, the radiation power regulator 25, the input of which is connected to the output of the third differential amplifier 24, the output of the power regulator 25 is connected to 1 Source of light.

The device works as follows.

The light source 1 generates a radiation flux directed to the movable element 2. When moving the movable element 2 relative to the fixed element 6, the output of the photosensitive pads 17 and 18 of the four-quadrant photoreceiver 15 generates electrical signals shifted by 180 ° relative to one another 7 and 8 are one relative to the other half of the lattice period.

The signals from the photosensitive pads 17 and 18 are fed to the inputs of the first differential amplifier 20, at the output of which a measuring signal is formed.

The transfer of the image of the indicator gratings 7 and 8 to the surface of the photosensitive pads 17 and 18 of the four-quadrant photodetector 15 is performed by a lens 14.

Image of measuring grid

3 are built on the additional window 13. However, when moving the measuring grid

3 At the output of the photosensitive sites 16 and 19, the alternating electrical signal is not generated, since the width of the additional window is 13 times the measurement period.

5 lattices 3.

When combining extended strokes

4 and 5 beginnings with windows 11 and 12 at the output of the second differential amplifier 23 a signal is generated, the sign of which

0 is associated with the displacement of the movable element 2 relative to its average position.

Signals proportional to the power of the radiation flux transmitted through measuring grid 3, indicator grids 7 and 8, extended reference lines 4 and 5, windows 11 and 12, and additional window 13 are formed at the output of the first 21 and second 22 adders.

The signal generated at the output of the first adder 21 is larger than the signal generated at the output of the second adder 22, since the radiation fluxes that passed through the indicator grids 7 and 8 are larger than the radiation fluxes that passed through the windows 11 and 12, the additional window 13, due to the fact that the indicator grating 7 and 8 suffered several periods.

At the output of the third differential amplifier 24, a signal is formed that is proportional to the opal power of the radiation flux, which is supplied to the radiation power regulator 25. The signal generated at the output of the third differential amplifier 24 is theoretically independent of temperature,

5, since it does not contain a component proportional to the magnitude of the reverse currents passing through the photosensitive pads 16-19, which are subtracted in the third differential amplifier 24.

0Signal taken from controller 25

The radiation power is fed to the light source 1, maintaining the sensitivity of the device unchanged.

Claims (1)

The use of the device permits an increase in the measurement accuracy by improving the temperature stability of the circuit for stabilizing the sensitivity of the device. Apparatus of the Invention A device for measuring displacement, comprising an optically coupled light source, a movable element with an applied measuring grid and two extended reference lines located on opposite sides of the measuring grid, a stationary element with two indicator gratings displaced halfway apart from each other. grids, two windows optically connected with two extended lines of origin are deposited on the fixed element, four-square photopr The second and third photosensitive platforms of which are optically connected with the indicator grids. The first and the fourth are with two windows coated on the fixed element, the first differential amplifier and the first adder, whose inputs are connected to the second and third photosensitive sites of the four-quadrant photoreceiver, the second differential amplifier and the second adder, the inputs of which are connected to the first and fourth photosensitive areas of the four-quadrant photocurrent five 0 five A third differential amplifier, a radiation power controller, the output of which is connected to a light source, characterized in that, in order to improve the measurement accuracy by improving the temperature stability of the device’s sensitivity stabilization loop, an additional window optically attached to the fixed element and the fourth photosensitive areas of the four-quadrant photodetector, the window length is equal to the length of the bar of the measuring grid, the window width is a multiple of the period of strokes measuring lattice, the side of the window is parallel to the lines of the measuring grid, extended reference points are applied so that the end of one extended reference line coincides with the beginning of another extended reference line, the inputs and output of the third differential amplifier are connected respectively to the outputs of the first and second adders and the input power control radiation. | 5G W s - UE. U 25 l Uh Phia.1 U16 LAAALLA l №7 CHLAAAAL / L L A V v U16 shz X V U21 X Uz3