RU1772625C - Optronic linear displacement measuring device - Google Patents

Abstract

The invention relates to the field of measurement technology and can be used to measure linear displacements, vibration amplitudes, linear dimensions of parts. The aim of the invention is to improve the accuracy of measurements. The goal is achieved in that an accumulation unit is introduced into the optoelectronic device for measuring linear displacements of objects, and the control unit is provided with an additional output. 1 ill.

Description

The invention relates to measuring technique and can be used to measure linear displacements, vibration amplitudes, linear dimensions of parts.

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

The drawing shows a block diagram of a device.

The optical-electronic device for measuring linear displacements consists of optically coupled optical system 1 for forming interference fringes and a discrete photoconverter 2, the photosensitive layer of which is made in the form of a system of 32 parallel electrically isolated photodetectors, connected in series to the signal processing unit 3, the information input of which connected to the output of the discrete photoconverter 2, block 4 shapers, block 5 account, block 6

accumulation and a display unit 7, a control unit 8, the readout outputs of which are connected to the control inputs of the discrete photoconverter 2, and the first, second and third outputs of the control unit 8 are connected respectively to the first, second and third control inputs of the signal processing unit 3, the third the output of the control unit 8 is also connected to the first control input of the driver unit 4 and the second input of the account unit 5, the fourth output of the control unit 8 is connected to the third input of the account unit 5, the second control input of the unit 4 is connected inen with the first input of the control unit 8 and the first control output of the account unit 5, the third control input of the unit 4 is connected to the second input of the control unit 8 and the second control output of the account unit 5, the fifth additional output of the control unit 8 is the output of the second one h

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a vibrator in the control unit 8 and is connected to the second control input of the accumulation unit 6, the first control input of the accumulation unit b is connected to the first input of the counting unit 5.

The accumulation unit 6 is made in the form of a series-connected adder 9, the first group of inputs of which are the inputs of the accumulation unit 6 and connected to the output of the account unit 5, the first buffer register 10, the first group of outputs of which is connected. To the second group of inputs of the adder 9 and the second buffer register 11, the outputs of which are the outputs of the unit

6 accumulate and are connected to the inputs of the unit

7 of the counter 12, the input of which is the second control input of the accumulation unit 6 and connected to the fifth additional output of the control unit 8, the output of the counter 12 is connected to the control input of the second buffer register 11 with the reset input of the counter 12 and with the input of the second one-shot 14, the first one-shot 13, the input of which was driven by the first control input of the accumulation unit b and connected to the first input of the account unit 5, the output is connected to the control input of the first buffer register 10, the second one-shot 14, the output of which is connected a reset input of the first buffer register 10.

The control unit 8 is made similar to the prototype and contains a clock pulse generator, a counting circuit, a decoder, a code inversion circuit, a matching circuit, a first multivibrator, a second multivibrator, a first NAND circuit, a second NAND circuit, and five single vibrators, and, in contrast from the prototype, the control unit 8 comprises a fifth additional output, which is connected to the output of the second single-vibrator of the control unit. All other communications of the proposed control unit are similar to the control unit in the prototype.

The signal processing unit 3, the shaper unit 4, the account unit 5 and the indication unit 7 in the proposed device are similar in construction to the corresponding units in the device, taken as a prototype.

The device operates as follows.

Two bands, dark and light, are projected from the interference pattern formed by the interference band forming unit 1, which are projected onto a discrete photoconverter 2, at the output of which signals are proportional to the distribution of illumination along the selected area. Distance between extreme

photodetectors of the discrete photoconverter 2 is equal to the period of the interference band.

With linear movements of the controlled object, the interface of the interference bands moves along the photodetectors of the discrete photoconverter 2, as a result of which an electrical signal is generated at its output.

the amplitude of which is proportional to the amount of displacement, and the phase is associated with the spatial position of the photodetector in discrete photoconverter 2.

By fixing the number of the interrogated column of the photoconverter 2, on which there is - the interface of the interference fringes, one can unambiguously determine the amount of displacement

object from the expression:

I-,

where A is the wavelength of the probe radiation;

p - the number of columns of discrete

a photoconverter 2, spanning the width of two adjacent interference fringes;

N is the number of the interrogated column of the discrete photoconverter 2.

The signal taken from all the elements of the column of the discrete photoconverter 2, is fed to the input of the signal processing unit 3, where the LCP is converted to digital

the code that is further used in block 3 to calculate the average value of the information signal during the polling of elements of the discrete photoconverter and comparing the current value of the amplitude

an information signal with an average value calculated and recorded in the buffer registers of block 3 in the previous cycle of interrogating the elements of the discrete photoconverter 2. Rectangular pulses are taken from the output of the signal processing unit 3, moreover, one pulse comes to the period of the interference fringes, and its edges correspond to the time moment in which there is a transition from dark to light strip and vice versa. The rectangular pulses from the output of the signal processing unit 3 are fed to the input of the shaper unit 4, where they are converted into short pulses, the phase of which

tied to the leading and trailing edges of the pulse from the output of signal processing unit 3. The shaper unit 4, depending on the state of the counting unit 5, transmits pulses corresponding to the leading edge

the signal from the output of the signal processing unit 3, or to the rear, and also passes a pulse from the third output of the control unit 8 if the pulse from the output of the signal processing unit 3 has not arrived during the interrogation of the columns of the discrete photoconverter 2. On the trailing edge of the pulse from the third output of the control unit 8, the zeros are counted into the block 5 and the display unit 7 is zeroed.

In the initial state, when the object is not moving, and two strips with maximum and minimum illumination are projected to the receiving part of the discrete photoconverter 2, the pulse from the output of block 4 of the shapers at the moment when the counters in block 5 of the count are already reset to the first input of the counting unit 5 pulse from the third output of control unit 8, the state of the first buffer register 10, the second buffer register 11 and counter 12 are reset to zero by pressing the Reset button (not shown in Fig. 1). Thus, in the initial state, the indications of the indication unit 7 are zero. When the object is displaced, the interference pattern bands move, the direction of which determines the sign, and the number of bands passed through discrete photoconverter 2 determines its magnitude. When the bands move, the columns of the discrete photoconverter 2 from the 1st to the nth are sequentially illuminated and, accordingly, the pulses appear sequentially from the output of the shaper unit 4. The number of pulses received from the fourth output of the control unit 8 to the third input of the counting unit 5 corresponds to the number of polled columns of the photoconverter 2, on which the interface of the interference fringes is located. This number, with the arrival of the pulse at the first input of the counting unit 5, is transmitted to the adder 9 and simultaneously by the pulse generated by the one-shot 13, then the number is written to the buffer register 10 and transferred to the second group of inputs of the adder 9. In the next polling cycle of the elements of the discrete photoconverter 2, from the output of the adder 9, the code of the sum of the numbers received by the first group of inputs of the adder 9 is removed with the code on the second group of inputs coming from the output of the buffer register 10, recorded in the previous cycle of interrogating the elements of a discrete photo educator 2. In the buffer register 10, a pulse from the output of a single-vibrator 13 will record the sum of the numbers of codes for the first and second cycle of polling the elements of the photoconverter 2.

In the next polling cycle, the code of the sum of numbers will be written in the buffer register 10

for three cycles of polling photoconverter 2 elements, etc. Thus, the result of the sum of the codes of numbers during the accumulation time will be written to the buffer register 10,

which is determined by the number of polling cycles of the elements of the photoconverter 2, The average value calculated as the result of dividing the code of the accumulated sum of numbers is taken from the output of the buffer register 10

0 by the number corresponding to the number of polling cycles of the elements of the photoconverter 2 during the accumulation time. From the fifth additional output of the control unit 8 (input of the second one-shot 29, cm,

5, a prototype block diagram) a pulse is taken, the duration of which corresponds to one polling cycle, this pulse is fed to the input of the counter 12, which counts them and expires after the accumulation time

0 there is a pulse at the output, on the leading edge of which the average measurement result is recorded in the buffer register 11, and on the trailing edge, the counters 12 are reset to zero. Single front vibrator 14

5, a short pulse is generated from the output of counter 12 to the edge of the pulse, which resets the state of the buffer register 10 to zero, and thus, the accumulation unit 6 is ready to receive the following information in

0 subsequent accumulation cycle. The number recorded in the buffer register 11 is displayed on the low-order indicators (IIM) of the indicator unit 7 and corresponds to the displacement of the fractional part of the interference band.

The duration of the pulse from the output of the single-vibrator 13 is set longer than the totalization time by the adder 9, and the duration of the pulses from the output of the single-vibrator 14 is set longer than the delay time for the number to be transmitted from the output of the buffer register 11 to the input of the indicators in the indication unit 7. The accumulation time, after which the averaged result of measurements of micromovement is displayed, is set so as to provide the required accuracy and speed of information display, taking into account the possible frequency of oscillations of the controlled object. It is assumed that the controlled object can change its position only once during the accumulation time, i.e. in order to track the position of the object in real time, it is necessary that the pulse repetition rate from the output of the counter 12 be equal to or greater than twice the maximum oscillation frequency of the controlled object.

The circuit of the counting unit 5 is constructed in such a way that it provides an increase in the readings of the high-order indicators in the display unit 7, regardless of the sign of the offset when the number 00 appears after the number 31 at the output of the block 5 and eliminates the increase in the readings of the high-level indicators when the number 00 appears after the number 01. The circuit also allows decreasing the indication of the high-order indicator by 1 when a digit 31 appears after the digit 5 after the number 00. Taking into account that external vibrations lie in the range of 0.1 to 600 Hz and are mainly oscillatory in nature p, and account for reversal circuit constructed with the movable plate, then the measurement error will be reduced compared to the known device, by averaging the measurement results for the TH time (accumulation time). In the known prototype device, the measurement error will be greater, i.e. the measurement result is displayed in each polling cycle of the elements of the photoconverter 2, and the pulse repetition rate corresponding to the duration of one polling cycle is ten or more times the upper frequency of the interference, in which case, the device will display the true position of the object taking into account the effect on it interference, which reduces the accuracy of measurements,

Claims (1)

In the proposed device, the measurement error will be less, because the effect of interference on the controlled object during the accumulation time will be taken into account in each polling cycle, i.e. summed up taking into account the sign, and averaged, which ultimately allows to increase the accuracy of measurements. SUMMARY OF THE INVENTION An optical-electronic device for measuring linear displacements, comprising an optically coupled optical system for forming interference fringes and a discrete photoconverter, the photosensitive layer of which is made in the form of a system of parallel electrically isolated photodetectors, connected in series to the processing unit, connected to the outputs of the photoconverter, the former unit and counting unit, indication unit and unit control, the readout outputs of which are connected respectively to the control inputs of the photoconverter, the first and second outputs are connected respectively to the first and second control inputs processing unit, the third output is connected to the third control input of the processing unit, the second input of the counting unit and the first control input of the shaper unit, the second and third control inputs which are combined, respectively, with the first and second inputs of the control unit and connected to the first and second control inputs of the account unit, the third input of which is connected to the fourth output control unit, characterized in that, in order to increase accuracy, it is provided with an accumulation unit made in the form of a series-connected adder, the first group of inputs of which are the inputs of the unit connected to the outputs of the counting unit, the first buffer register, the first group of outputs connected to the second group of inputs of the adder, and the second buffer register, the outputs of which are the outputs of the block connected to the inputs of the display unit, the first one-shot, the input of which is the first control input of the block Connected to the output of the block, and the output is connected to the control input of the first register, the second one-shot, the output of which is connected to the reset input of the first register, and the counter, the input of which is the second control input block reset, and the output is connected to the control input of the second register, the input of the second one-shot and the counter reset input, and the control unit is made with the fifth output, which is connected to the second control input of the accumulation block.