SU905636A1 - Photoelectric angle pickup - Google Patents

Description

(54) PHOTOELECTRIC CORNER SENSOR

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The invention relates to a measurement technique and can be applied to measure rotation angles with an accuracy of the order of units of arcseconds or their fractions, for example, in astronomical at-. borostroenii.

Known angle sensors ,. containing a light source, movable and fixed circular scales, a reflective system, a photodetector and a Tl reading device

However, the known sensors contain a point source of light, which requires the installation of a parabolic reflector that allows all the divisions of the gratings to be illuminated uniformly.

The closest in technical essence and the achieved result to the invention is a photoelectric angle sensor containing coaxially mounted annular lighting, two disks with identical raster paths applied on the periphery, one of which is designed to be fixed on the object to be monitored and

rotatably inserted, a reflective system, a photodetector, and an electronic logic unit connected to the output of the photodetector2.

A disadvantage of the known device is low accuracy caused by the accumulation of errors arising from the failure of electronic circuits during unplanned short-term power outages and surges of supply voltages, etc.

10 It is possible to take into account the accumulated error only by a constant calibration of the electronic logic unit by setting the zero point of the sensor, which is unacceptable when measuring the angle of rotation, which the long time varies within one revolution. The known photoelectric sensor has a small angle measurement range. Since discs are marked with different tracks with the same number of elements, then for recording the angle of rotation per unit angular second of chiolo elements on each disk must be more than one million. This has been a significant increase in disk size.

The purpose of the invention is to improve the accuracy and expand the range of measurements of the angle of rotation.

The goal is achieved by the fact that the sensor is equipped with an additional pair of disks and an additional photodetector mounted coaxially with the first pair of disks on the opposite side of the RING illuminator, one of the additional disks is mounted for rotation on the common axis with the corresponding disk of the first pair, the second additional disk is fixed on the fixed the basis, the number of elements of the raster tracks of the additional pair of disks differs by one from the number of elements of the raster boxes of the first pair of disks, the output is additionally photodetector

connected to the second input of the electronic unit.

The drawing shows a diagram of the device ....

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The photoelectric angle sensor contains an annular illuminator 1, mounted coaxially with disks 2 and 3 with identical raster tracks printed on the periphery, one of which 3 is designed to be fixed on the object to be monitored 4, and the other 2 is rotatably mounted, a reflective system 5 allowing collect the entire light flux transmitted from the annular illuminator 1 through the disks 2 and 3 to the photo receiver 6, the optical axis of which coincides with the optical axis of the reflection system 3 and with the axes of disks 2 and 3 electronically unit 7 connected to the output of the photodetector 6, an additional pair of disks 8 and 9 and additional photodetector 10 mounted coaxially with the first pair of discs 2 and 3 from the opposite side of the annular illuminator 1, one of the additional disks

8 is mounted rotatably on a common axis 11 with a corresponding disk 2 of the first pair, the second additional disk 9 is fixed on the fixed base 12, the number of elements of the raster tracks of the additional pair of disks 8 and

9 is different from the number of elements of the raster tracks of the first pair of disks 2 and 3, the output of the additional photodetector 10 is connected to the second input of the electronic logic unit 7.

The proposed angle photoelectric sensor contains two identical channels.

each of which consists of two pairs of disks 2, 3 and 8, 9, reflective cells 5 and 13 and photodetectors 6 and 10, and the ring illuminator 1 and the electronic logical unit 7 are common to both channels.

Each of the channels works as follows.

The light from the annular illuminator 1 passes through the mating elements of the raster tracks of both disks 2, 3 and 8, 9 and reflective systems S and 13 is projected onto photodetectors 6 and 10. In each pair of disks during rotation of one disk 2, 8 relative to the other 3, 19 the signal from the output of photodetectors 6 and 10 is modulated. Since the number of elements of raster tracks of the first pair of disks differs by one from the number of elements of the raster track of an additional pair, then for one complete rotation of the rotating disks, N pulses from one channel and N -1 from another channel enter the input of the electronic logic unit 7, respectively. channel.

Thus, at the input of the electronic unit 7, two time verse scales are obtained: one with the number of pulses N, and the other with the number of pulses N -1. The beginning and end of each of these scales are formed by the zero points of the corresponding channels (not shown).

Formed two time scales contain M (M -1) possible combinations, at any of which only one of the pulses of each channel coincides in time in the electronological unit 7, and which of the pulses in the count of the soundpad depends on the angle between the zero points both channels.

To obtain samples of the rotation angle, the electronic logic unit 7 records the coincidence in time of pulses of the 1CD channel vi time points at which the rotating disks 2, 3 and 8, 9 pass zero-points, and also counts the number of pulses from the signals of zero-points to pulse coincidence.

Claims (2)

1. USSR author's certificate number 396545, cl. Gr 01 B 11/26, 1973. 2. USSR Author's Certificate No. 462О66, cl. GI O1 In 11/26, 1975. (prototype). ; j y