SU1658379A1 - Photoelectric shaft-position-to-number converter - Google Patents

Abstract

This invention relates to automatic regulation and can be used to match rotary type sensors and actuators with control computers. The purpose of the invention is to increase the speed and simplify the converter. To do this, a photoelectric transducer of the shaft rotation angle into a code containing an annular light source, a measuring disk, a modulation diaphragm, M photodetectors, N optically transparent scratches are located on the measuring disk, W ± 1 optically transparent scratches are located on the modulation diaphragm, M is entered - subtractive blocks, M amplifiers-limiters and encoder. The goal is achieved by generating signals from photodetectors at the output of summing-subtracting blocks of shorter duration than at the output of photodetectors. 3 il.

Description

The invention relates to the field of automatic regulation and can be used to match the sensors and actuators of the rotary type with control computers.

The purpose of the invention is to increase the speed and simplify the converter.

FIG. 1 shows a structural diagram of a photoelectric converter of the angle of rotation of the shaft into a code; in fig. 2 — relative positioning of the code scale scratches, modulation diaphragm risks, and photodetectors; in fig. 3 - timing diagrams that show the operation of the converter.

The photoelectric transducer of the shaft rotation angle into the code contains shaft 1, bearing 2, measuring disk 3 on which N optically transparent scratches 4 are applied, modulation diaphragm 5 on which N ± 1 optically transparent scratches are applied 6. ring source 7 of light, M

photodetectors 8, M summing-subtracting blocks 9, each of which is made in the form of operational amplifier 10 and registers 11-15, M amplifiers-limiters 16, the encoder 17 and the output 18.

FIG. Figure 2 shows a fragment of the projection of the measuring disc 3 and modulation diaphragm 5 and the aperture of the photodetectors of the converter, in which the number of scratches of the measuring disc 3 is limited by the number N 33 in terms of their graphic representation (in real converters this number can reach several thousand hours). On this fragment, the total number of photodetectors M is equal to eight, their designations are additionally assigned indices in accordance with the output code of the transducer, and risks 4 of the measuring disk 3 and risks 6 of the modulation diaphragm 5 coinciding with the apertures of the photodetector 8-0, 8-1. 8-2 ....

oh ioo

GO

AND

The indices of the respective photodetectors 8 are assigned, for example, the risk 6-1 of the modulation diaphragm 5, which coincides with the photodetector 8-1.

All angles are measured relative to the OS axis in a clockwise direction. The angular position of the troughs 4 and the photodetectors 8 is determined by the angular position of the straight line segments passing through center 0 and the middle of the corresponding risers 4, 6 and the photodetectors 8.

In the diagram, the middle of the zero photodetector 8-0 lies on the axis of the op-amp and therefore its angular position is zero, and the angular positions of the photodetectors 8-1, 8-2, 8-3 ..., being evenly spaced around the circumference, are respectively

about 1P and 0 2I about t 2L

 fc-2 -m- # -3 m; -

The same values of the angular positions have the risks of 6-0, 6-1, 6-2 ..., as coinciding with the corresponding photodetectors 8-0, 8-1, -8-2 ..,

In the transducer under consideration, the measurement of the angular position of the input shaft 1 is determined by the angular position of the zero risk 4-0 of the measuring disk. At the same time, a rough reading of the measured angle a corresponds to the number of angular periods of the followings of the measuring disk 3 of the crc 3 contained in the angle limited by the 4–0 measuring disk 3 and the measuring disk 3 closest to the axis 4 And then the number of fractions of the period a p contained in the angular position of the risks 4 of the measuring disk 3 closest to the axis of the control variable.

Photoelectric Converter angle of rotation of the shaft in the code works as follows.

FIG. 2, the position of the measuring disk 3 corresponds to the zero angle of rotation of the input shaft 1, since the middle of its zero risks 4-0 coincides with the axis of the shelter. In this case, the risk of a 4–0 measuring disk coincides with the risk of a 6–0 modulation diaphragm.

Measuring disk 3 contains N rejects 4, and the modulation diaphragm 5 N-1 is evenly spaced around the circumference 6, and therefore, if the risks coincide, 4-0 measuring disk 3 and risks 6-0 modulation diaphragm 5 of the next risk 5 of measuring disk 3 lags behind from the following risks 6 modulation diaphragm 5 on the value of L, equal to the difference

0

five

the angular periods of the following remarks 4 and 6 of the modulation diaphragm 5 and the measuring disk 3, and the last lagging behind the risks 4 of the measuring disk 3 from the last risks 6 of the modulation diaphragm 5 (already coinciding with its risk of 4-0) is the following of the risks of the measuring disk 4 3a p. But the number of scratches 6 of the modulation diaphragm 5 unambiguously determines their angular position fi and therefore the value of the lag of the scratches 4 of the measuring disk 3 from the modulation diaphragm 5 corresponding to them according to the number of changes varies linearly from zero to or n when changing the angular position of fl from zero to 2n and in the general case, taking into account that

2 what an -. is defined as

N 0R ft

V 2p - L- 7 2l: N

If the risks of a 4-0 measuring disk 3 coincide with a risk of 6-0 modulation 5 diaphragm bis taking into account the angular positions of scratches 6-1, 6-2, 6-3 ... the lag of risks 6-1, 6-2, 6-3 ... the modulation diaphragm 5 is

0 Vi-bL vp-2-2-) 2NM NM Widths 4 of the measuring disk 3 and scratches 6 of the 5 V modulation diaphragm are the same and equal to y, i.e.

d

2n

N-M

as a result, as shown in Figure 2, with the coincidence of scratches 4-0 of the measuring disk 3 and 6-0 of the modulation diaphragm 5, risk 4-1 concerns risks 6-1, the gap between risks 4-2 and 6- 2 is

the value (5, the gap between risks 4-3 and 6-3 is 2d, etc.

Thus, at zero angle a of the input shaft 1 of the converter, only the risks of 4-0 and 6-0 have their area of overlap,

and the light flux from the ring source 7 passes through these risks 4-0 and 6-0 and enters the input of the photodetector 8-0. In this case, an electrical signal Uo is excited at the output of the photodetector 8-0, and there are no signals at the outputs of the remaining photoreceivers Ui,, Cs ... (in the diagram of Fig. 3, these signals are positive). In the absence of signals Ui and U on the subtracting inputs of summing and subtracting unit 9, the signal Do goes through unit 9, the normalizing limiting amplifier 16 and to the zero input of the encoder 17, where it is converted into a digital code of zero value.

When turning the input shaft 1 at an angle

Op.,

a, equal to - i.e. on the M-th part of the period M

the following of the scratch 4 of the measuring disk 3, and equal in turn to the width of the d of the 4 of the measuring disk 3 and of the 6 of the modulation diaphragm 5. risk 4-0 ahead of the risk of 6-0 by d, risks 4-1 and 6-1 are the same, risk 4-2 lags behind risks 6-2 d, risk 4-3 lags behind risks 6-3 by 2 6, etc., as a result of which the luminous flux from source 7 passes through risks 4-1 and 6-1 and is fed to the input of the photodetector 8-1, and its output signal Ui, through block 9 and the amplifier 16, forms the digital code of a single value at the output of the encoder 17. Similarly, when turning the shaft 1 at an angle

2 - risks 4-2 and 6-2 coincide and output

M

signal U2 photodetector 8-2 generates digital an

A code equal to two, a corner 3 - corresponds to M

There is a digital code of three, etc. In general, when the angle of rotation

,, On

shaft 1 is not a multiple of the value - occurs

M

partial overlapping of one of the treads 4 of the measuring disk 3 and one of the tines 6 of the modulation diaphragm 5, corresponding to two adjacent photodetectors 8, and at their outputs signals appear that are less than the maximum values. In this case, the output digital code is generated over the larger of the output signals of the photoreceivers 8 oo, the results of their comparison in the summing-subtracting blocks 9, for which these signals are sent to their summing and subtracting inputs with the same coefficients of their transmission over all inputs. So, for example, if the input angle a

closer to

lies in the range from - to 2 -

MM

meaning

From, M

overlapping area

4-1 and 6-1 are larger than the overlap area of 4-2 and 6-2, then a greater luminous flux passes to the input of the photodetector 8-1 than to the input of the photoreceiver 8-2 and therefore the output signal Ui of the photoreceiver 8 will be greater than signal 1) 2 photodetectors 8-2.

The signal U is fed to the summing input of the block 9-1 and to the subtracting input of the block

9-2, and signal 1) 2 - to the subtracting input of the block 9-1 and the summing input of the block 9-2. Since there are no signals Do and Kz, the output signal of the block 9-1, as the difference

between the signals Ui and U2. will be positive, and the output signal of block 9-2, as the difference between the signals U2 and Ui - negative. The positive signal from the output of block 9-1 is normalized by amplifier 16-1 and

0 is encoded by encoder 17 into a single output code value.

Thus, regardless of the angle of rotation of the shaft 1, its value is uniquely encoded with a digital code with an error.

Claims (1)

Formula of Invention Photoelectric Converter the angle of rotation of the shaft into a code containing successively located and optically connected annular light source, measuring disc, modulation diaphragm and M photodetectors located evenly around the circumference, on the measuring disk there are N optically transparent scratches located evenly around the circumference, on the modulation diaphragm there are located N ± 1 optically transparent Risk is located evenly around the circumference, characterized in that, in order to increase speed and simplify the converter, M summing-subtracting blocks, M amplifiers-limiters and encoder are entered into it, the angular size b of optically transparent risks is chosen from the ratio 40 d (1 - 1.5) 360 N-M the output of each photodetector is connected to the summing input of the corresponding summing-subtractive unit, the first subtractive input of which is connected to the output of the previous photoreceiver by location, the second subtractive input is connected to the output of the subsequent positioning photoreceiver, the outputs of the summation-subtracting blocks are connected through appropriate amplifiers with the inputs of the encoder, the outputs of which are transforming outputs 18 1 ( G, 6 FIG. 2 Fig.z