SU1216683A1 - Transducer - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure forces, pressures, accelerations, torques and other physical quantities. The goal is to increase measurement accuracy. The device contains a polarization-optical system 3, comprising a polarizer 4, a phase-shifting plate 5, a sensitive element 6, analyzers 7 and 8 and photodetectors 9, 10 connected to the inputs of amplifiers II and 12, switches 13 and 14, filters low frequencies 15-18, adders 19 and 21, circuits 22-24. Comparison, current regulators 25 and 26, generator 27 square voltage pulses. The device allows the workers to pass them (modulated by the measurement of i-iv.oproduction P) of the light pulses from the emitter 1 of the light and the reference (unmodulated) from the emitter 2 of the light along the same light-guiding fiber channels the difference in the levels of the reference pulses, which is due to different variations in the channel transmission, but not dependent on P, to exclude the difference in the levels of the working pulses. 3 il. (L с. О: 05 00 О5

Description

The transmitter is related to the measurement technique and can be used to measure forces, pressures, accelerations, torques and other physical quantities.

The aim of the invention is to improve the measurement accuracy.

FIG. 1 is a block diagram of a converter; Fig 2 - static light characteristics of the working channels; Fig, 3 is a temporary diagram of the operation of the Converter,,

The measuring transducer (hereinafter referred to as the transducer) contains (FIG. 1) two emitters 1 and 2 of light, a polarization-optical system 3 including a polarizer 4, a phase-shifting plate .5, a sensitive element -6, analyzers 7 and 8 and photodetectors .9 and 0, The planes of the polarization of the polarizer 4 and the analyzers; 7 and 8 are made with the direction of the mechanical pan and the sensing element (with the direction of the measured action P in the fig, 1 angles 145, The angle between the polarization planes of the polar rizator 4 and analyzer 7 rsven 90 °, and the polarization planes of the polarizer 4 and the analyzer are 8 - O °, the direction of the axis of the highest speed of the phase-shifting plate 5 is parallel to the direction of the measured effect P (indicated further for the multiplicity by one P symbol), the outputs of the photodetectors 9 and 10 are connected with inputs of amplifiers 11 and 12 that have adjustable gains, and the outputs of these amplifiers are connected to the inputs of analog switches 13 and 14. The outputs of analog switch 13 are connected to the inputs of filters I5 and 16 low frequencies, and the inputs of analog switch and 14 - to the inputs of the filters 17 and 18 of the low frequencies. The output of the low-pass filter 15 is connected to the first inputs, and the low-pass filter 17 is connected to the second inputs of the adder 19 and the subtractor 20, the output of the low pass filter 16, the keys to the first inputs, and the output of the low pass 18 to the second the inputs of the adder 21 and the comparison circuit 22. The outputs of the adders 19 and 21 are connected to the first inputs of the comparison circuit 23 and 24, respectively.

the second inputs of which are connected are: -size reference voltage Uori, the outputs of comparison circuits 23 and 24 are connected to the control inputs of the current regulators 25 and 26 of the emitters 1 and 2 of the light. From generator 27, rectangular voltage pulses arrive at the second control input of current regulator 25 and the inputs of analog switches 13 and 14, and through the phase inverter 28 to the second input of current regulator 26. The output of the comparison circuit 22 is connected to the second input of the amplifier 11 and through the inverter 29 to the second input of the amplifier 2. The signal at the code of the subtractor 20 is the output signal of the converter.

The light fluxes F and F from the emitters 1 and 2 of the light, respectively, are directed through the fiber optic channels 30 and 31, the polarization-onti system 3 and the fiber optic

channels 32 and 33 to photo detectors 9

and 10 in such a way that f passes

through the floor 4, and it passes,

The converter works as follows

The supply voltage through the current regulators 25 and 26 is supplied by the emitters 1 and 2 of the light, the control signal from the generator 27 square-wave pulses, stepping on

the current regulator 25 directly, and the current regulator 26 through the phase inverter 28, allows you to occupy the emitters I and 2 of the light alternately. The pulses of the luminous flux F, from the emitter 1 of the light, passed through the polarizer 4, become linearly polarized. In the phase-shifting plate 5, the luminous note splits into two flat polarized components,

The zero plane of one of the components is parallel, and the other is perpendicular to direction P, and the phase difference is o (((j of these components is equal to 90 on the code of plate 5).

Similar transformations occur with the light beam c. the sensitive element 6, if it is loaded, with the difference that the magnitude of the phase shift LSh is proportional to

P, and the sign Do; depends on the sign of Р, / The total phase shift, created by the phase-shift plate and the elastic element, is equal to С / о ЛЫ.

31216683

If Р О, then н Л (Х О, and svetoko up

The TOI and o, g fluxes on the upper lines of the analyzers are equal in magnitude, and their levels correspond to the steepest sections of the dependence of the light fluxes on o (figure 2).

If P is not equal to O and varies with time, then Do {also becomes not equal to O and changes proportionally to P. In this case, the light fluxes at the outputs of analyzers 7 and 8 receive increments of Lf and φf proportional to Lo and different in sign. The total light fluxes F and F are then expressed by the ratios

.-

%, g-% 1, .g (2)

The total light fluxes f and f are fed to photo-detectors 9 and 10 and are converted into them into pulses of photo-flows 1 and I, the difference of which in a certain range of their changes is proportional to the change in P.

Pulses of light flux f; that are phase-shifted with respect to pulses of the light flux Φ on the ISC, enter the polarization-optical system, polarizer 4 is mine, and therefore remain unpolarized. As a result, the light fluxes corresponding to the luminous flux f and f at the outputs of the analyzers 7 and 8 do not depend on the change in P.

If the transmission of the polarization-optic system 3 and the optical fiber channels 32 and 33 for light pulses YAR, 2. /, And FT are the same, then they are equal in size and produce at the outputs of photodetectors 9 and 10 the same 3 M pulses of photo streams to 1 g g

Synchronous pulses of photo streams It 1 ii2. and shifted relative to them 180 ° synchronous pulses of photo-fluxes and 1 2., g are fed to the inputs of amplifiers I and 12. Electric signals from the outputs of these amplifiers in Bi-sch pairwise synchronous pulses of electric voltage U ,, and 41. - g , 1 - gt. The inputs of the analog switches 13 and 14 are received. During the arrival of pulses U and, and, corresponding to the pulses of the light emitter 1, the inputs of analog

switches 13 and 14 are connected to filter inputs by a control pulse from generator 27

15 and 17 low frequencies, and during the arrival of the pulses, g, 1 and ig, g

to the inputs of filters 16 and 18 of low frequencies. Timing diagrams of the pulses and ,, и, д, и, т, Uz, 3 are presented in Fig.3.

In that time interval, when P is zero (part of the time diagram in Fig. 3), the pulses and and are equal in Velcck. Their spread

the value obtained by the subtracting device 20 is zero.

If P becomes different from zero (section aB of the timeline, then action P causes changes

levels of light fluxes T,, IF, according to the ratios of CO and (2. This ultimately leads to inequality of impulses and, proportional to P (graphs and,, and., and, and 1 in the plot AB of the time diagram). lix difference at the output of the subtracting circuit 20, proportional to P, is the output signal Ug ,,,, of the converter.

If at this time, under the influence of external influences, the transparency of the light guide channels has changed, and

these changes are equal in magnitude, and have different signs, then this leads

k differ in m sign of changes in the levels of light flux φ, and, consequently, in the appearance of the difference between the corresponding pulses U, i, and Up (. raffics Uj and Uj.i on the time

chart). At the same time, this leads to an increase in the difference between the pulses Ц and and the GS P 1F k and, - plot of the time diagram) and the appearance of the output signal increment .uUg ,,,;

those. the occurrence of the offset of the initial UCM reading (plot & t from the graph U yx in the timing diagram). This offset is eliminated in the converter as follows. Stress and

and -i transmitted via analog switches 13 and 14 to filters

16 and 18 N11ZHNICH frequencies, and from the outputs of the latter to the inputs of the comparison circuit 22, create an unbalance voltage Up on its output. This voltage is applied to the second input of amplifier 11, and through the inverter 29 to the second input of amplifier 12. Thus, the gain factors of amplifiers II and 12 are changed so that the difference of the pulses U.i and g, g. at their outputs it becomes zero again. In doing so, the offset of the initial reading of the converter becomes equal to zero. Thus, the effect of changes in the propagation of the light guide channels on the display of the NIN transducer is eliminated.

At the same time, the pre-vibrating body circuit maintains the initial level of the pulses and j and g, g. This is accomplished by summing the NIN signals obtained from the outputs of the low-frequency filters 16 and 18 in the adder 2I. The sum signal Ucc is equalized in the comparison circuit 24, with the olor signal dart- In the case of a change in the magnitude of the sum signal Ucc of the output of the comparison circuit 24, a difference signal of a certain sign arises, which is fed to the input of the current regulator 26. The current regulator 26, depending on the sign of the difference signal, changes the power of the emitter so that the difference signal at the output of the comparison circuit 24 becomes zero again. Thereby, the levels of photocurrent, 1 and F are stabilized in the event that, under the influence of external influences, the transmission of the light guide channels changes in one direction.

The conversion coefficient of the converter is stabilized as follows. ;

The signals from the outputs of the low-pass filters 15 and 17 are summed in the adder 19. Their sum U is fed by the input of the comparison circuit 23, where the difference signal is compared with the reference voltage Uon and is applied to the current regulator 25, which changes depending on the sign of the difference signal It does not supply the light emitter 2 in such a way that the difference signal becomes equal to zero. At the same time, the voltage Uci is kept at a constant level equal to Uon by the most constant conversion factor of the converter.

The proposed polarization-optical system design and structural circuit for signal processing

received from it, allows, in contrast to the known, to carry out the passage of workers (i.e. modulated by measured exposure P) light pulses from the emitter 1.light and reference light (i.e. non-modulated by exposure P) light pulses from the radiator 2 lights on the same fiber optic channels and use the difference in the levels of the reference impulses; arising from a different change in channel transmission, but not dependent on P, to eliminate the difference in the levels of working pulses, arising for the same reason. At the same time, with this design of the polarization-tto-optical system, in contrast to the known construction, the appearance of differences in the levels of working light pulses in the conductive fiber channels is excluded, since a series of working pulses are supplied through one supply channel. The same can be said about the series of reference pulses.

Claims (1)

Invention Formula A measuring transducer containing two emitters of light, associated respectively with two current regulators, so that the first input of the first regulator is directly connected, and the first input of the second regulator with the help of an inverter - with the output of the generator, a polarized-optical system consisting from successively placed polarizer, phase-shifting plate, sensing element and analyzer, two photodetectors connected respectively to the inputs of amplifiers, a source of reference voltage and a low filter are often , in order to improve accuracy, it is equipped with four optical fiber channels, three low-pass filters, three comparison circuits, two adders, a second inverter, a subtractor, and two analog switches. whose first inputs are connected respectively to the outputs of the amplifiers, the second inputs to the generator output, the first outputs to the inputs of the first and second, and the second outputs to the inputs the third and fourth low pass filters, while the output of the first low pass filter is connected to the pen "- and the output of the second low-pass filter — with the second inputs of the first adder and the subtractor; the output of the third low-pass filter is connected with the first inputs, and the output of the fourth low-pass filter — with the second inputs of the first comparison circuit and the second adder; The second adders are connected respectively to the first inputs of the second and third comparison circuits, the second inputs of which are connected to the source of the reference voltage, and the outputs of the latter, respectively, to the second inputs the first and second current controllers, while the amplifiers are tunable with adjustable gain and the regulating input of the first amplifier is connected directly, and the regulating input of the second amplifier with the help of the second inverter - with the output of the first comparison circuit, with Thereby, the light sources are optically coupled to the respective receivers via the optical fiber channels: the first light source through the successively installed polarizer, the phase-shifting plate, the sensing element and the analyzer, and the second light source through the successively installed sensory element and the analyzer. Phgg Lpf Uu, 0 Utt 0 needles o  one 0 Compiler A.Ekonomov Editor V.Ivanova Tehred S.Mngunova Proofreader I.Erdeyi Order 996/53 Circulation 778 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035 Moscow, Zh-35, Raushsk nab., 4/5 Branch ShSh Patent, Uzhgorod, Proektna St., 4 fig.E