SU1228280A1 - Analog-to-digital converter - Google Patents

Description

11228280

The invention relates to high resolution measurement systems, in particular to photoelectric measurement systems, lasts. and angle for gauges and machine tools.

There are known network interpolators j with interpolation coefficient up to 10, at which in sinusoidal sig10

eh

square ra

A built-in photocell creates a starting pulse for the comparator (GDR Patent No. 121178, Cl, G 01 D 5/245, 1978, Swiss Patent No. 531756, Cl. G About G 7/30, 1970). By logical connections and the subsequent fourfold evaluation in the counter, so far 1 practically reaches the maximum interpolation coefficients of 40. However, the disadvantage of these devices is that the very low coefficients are reached with high-resolution measurement systems;

The angle converter is also known - a code containing a sinus-sinus converter, two rectifiers, controllable keys, an integrator, a comparator and a calculator (ed. USSR, USSR No. 409262, cl. G 08 C 9/00, 1971).

The closest is the angle transducer — the code that contains the sine-cosine transducer and adders, as well as the quadrant switch, the comparison device, the voltage transducers — the code and the code — variable for: the same, and also the recording device (ed.St. USSR №209038, cl. G 08 C 9/00, 1966).

However, the known device has insufficient conversion accuracy.

The aim of the invention is to improve the accuracy of conversion with angle measurement systems.

This task for measurement systems containing photodetectors, at the input of which sinusoidal and cosine-like signals take place, is solved, that by adding the output signals of photoreceivers dp each: the quadrant creates linear nagfinding signals in the analog addition circuit 2, 3, 4, 5, and each adder is connected to one voltage converter - frequency 14 - 17, and

five

0

3

0

five

0

five

these voltage converters - frequency 14 - 17 through gates 18-21 controlled according to the quadrants are connected to the frequency-digital converter 8.

In order to ensure the switching of quadrants, it is necessary that the Comparators W and 11 follow the photodetector of the measurement system and through the logic unit 12, consisting mainly of two HE elements and four AND elements, are connected to a vent;

This has a positive effect in such cases of using the path and angle measurement systems, if the measurement systems are required to have high resolution without special dynamic requirements.

Fig. I shows the photodetector signals; Fig. 2 shows an example of a circuit for an analog addition circuit 2, 3, 4 and 5 for creating a linearized characteristic in Fig. 3 — linearized signals on an addition circuit; 4 shows the acquisition of control signals for switching quadrants; FIG. 3 shows a device with four voltage converters — frequency and valve circuits; 6 is a device for frequency-digital conversion.

With photovoltaic measurement systems in the case of scanning measures or rasters, located in the measuring head 1 by photodetectors, sine-wave and cosine-like signals are created, the characteristic which is shown in the diagram of Fig. By adding these signals to photodetectors in analogue addition circuits 2, 3, 4 and 5 with operational amplifiers (Fig. 2) create linearized voltage signals A,

C and D in accordance with the following laws:

-) mi

A ((-K cosoi)) -f% B ($ ((- to coso;) + (-K sinoi)) С S ((-K sino) + (K coso () + 6U.,

about LI

D -S (K sinoi) + (5Ug

Linearized signals in the OB-IB range are shown in FIG. Constant voltage lv | serves (figure 2) zero point (OB) of signals A, B, C

and D and CR3, the value of the voltage is established in each case at S 90, 180, 270 and BDO.

These linearized voltage signals A, B, C and D are supplied to voltage-to-frequency converters 14, 15, 16 and 17. For the necessary switching of quadrants (Fig. 3), one valve 18, 19, 20 or 21 is used. Parallel-connected the valve outputs are fed to a frequency-digital converter 8, in which the frequency f is proportional to the frequency f converted into counting pulses and counted in the counter 9.

Dp interpolation complete sine period and kosinusoidapnyh output signals of photodetectors (4) for performing switching requires four quadrants actuating signal S1, S2, S3 and S4, produced by the comparators 10 and 11 and the logic circuits of known non-interpolated amplified sine and cosine vpsod- signals.

In this case (figure 4), the output values of the comparators 10 and 11 are designated K1 and K2. Comparators are designed in a known manner by operational amplifiers and switch at zero transitions of the amplified signals of photodetectors -K sinoi and -K cos L (Fig.).

Each valve 18, 19, 20, and 21 can be made with one element with two inputs and an open collector, since in this case the comparators 10 and 11 are always switched during the transitions through the zero value of the amplified signals of photo receivers -K coscJ. and K siiic H order

5 most output signals K1 and K2, of which a logical connection 81 K1LK2, 82 KTLK2, 53 K1LK2, 84 K1LK2 in the logic circuit 12 create control signals S1, S2, S3

 and S4 for switching quadrants

(figure 4). These control signals one after another, the valves 18, 19, 20, 21 are opened, and thus to the frequency-digital converter 8

 5, a frequency f is applied, proportional to the linearized voltage signals A, B, C, or D. For converting the voltage-frequency signals A, B, C, D (Fig. 3), for example, hybrid technology converters can be used 10 kHz / iB transforms. linearity of 0.5%.

The valves 18, 9, 20 and 21 are followed by a frequency-digital converter 8 with a constant time of the valve t for counter 9 with a capacity of Z, for example Z 0 ... 39. Fig. 6 details the principle of operation of the frequency-digital converter 8. The device contains a precise channel with a valve 22, a counter-register 23, a valve 24 and an equalizer unit 25, as well as a coarse channel with a direction discriminator — a counter 26, a valve 27 and non-switch 28 coarse channel. These constructive units are followed by an indicator 13.

The control unit 25 of the clock

20

25

thirty

35

The operational node between the outputs of a separate 40 frequency of 100 kHz creates a 1 kHz clock,

These valves can be interconnected.

Converter (fig.Z) contains. measuring head 1, which has a fan valve and a control pulse S5, S6, S7 at the end of the valve opening time. In the switch 28, the coarse rope-receivers for creating sine-45, based on the I kHz clock of the output and cosine-wave output signals. For each quadrant of output signals, an operational amplifier is provided with addition schemes 2, 3, 4, 5 for analog addition of sinusoidal and cosine-like output signals and thereby for their linearization (Fig. 2). These adders 2, 3, 4, and 5 are connected via voltage-frequency converters 14, 15, 16, 17 and gates 18, 19, 20, and 21. Their common output is followed by a frequency-digital converter 8.

a measurement of the duration of the period K1 of the comparator 10 (FIG. 4), which decides whether a coarse cannap or 50 is fed through the valve 24 to the exact channel ..

In the direction discriminator - counter 26, coarse pulses KI and K2 of comparator 10 and 11 are considered correctly by signs. The input magnitude of the exact channel is the frequency f, (0-10 kHz) of the voltage-frequency converters 14, 15, 16, 17.

Comparators 10 and 11 always switch during transitions through the zero value of the amplified signals of photodetectors -K coscJ. and K siiic H order

the most output signals are K1 and K2, of which by the logical connection 81 K1LK2, 82 KTLK2, 53 K1LK2, 84 K1LK2 in the logic circuit 12, the control signals S1, S2, S3 are created

and S4 for switching quadrants

(figure 4). These control signals one after another, the valves 18, 19, 20, 21 are opened, and thus to the frequency-digital converter 8

the frequency f is applied, proportional to the linearized voltage signals A, B, C or D. For example, the voltage-frequency conversion of the signals A, B, C, D (Fig. 3) can be used. use converters of hybrid technology with a conversion factor of 10 kHz / IB and. linearity of 0.5%.

The valves 18, 9, 20 and 21 are followed by a frequency-digital converter 8 with a constant time of the valve t for counter 9 with a capacity of Z, for example Z 0 ... 39. Fig. 6 details the principle of operation of the frequency-digital converter 8. The device contains a precise channel with a valve 22, a counter-register 23, a valve 24 and a control unit 25, as well as a coarse channel with a direction discriminator — a counter 26, a valve 27 and unreclaved - a reader 28 coarse channel. These units are followed by indicator 13.

The control unit 25 of the clock

time of switching the valves and control pulses S5, S6, S7 at the end of the valve opening time. In the switch 28 coarse channel based on the clock frequency I kHz produces

a measurement of the duration of the period K1 of the comparator 10 (Fig. 4), which decides whether a coarse canap is fed to the indicator 13 through the valve 27 or a precise channel through the valve 24 ..

In the direction discriminator - counter 26, coarse pulses KI and K2 of compressors 10 and 11 are counted according to signs. The input value of the exact channel is the frequency f, (0-10 kHz) of the voltage-frequency converters 14, 15, 16, 17

During valve softening

tote f (O to 250 Hz 0; 250 to

 4 ms f, is entered into a 500 Hz 1 register; etc.) Thus, 23 ° At the same time, the content is countable: the incoming interpolation coefficient is a half-value from 0 to 39 according to an hourly period Ы 360 - 200-fold;

2282806

tote f (O to 250 Hz 0; 250 to

,

and

-.kcosd ..fisind

--...... / I ,, j Xi - I

Sind

Claims (1)

ANGLE CODE CONVERTER containing a measuring head with four photodetectors, each of which is connected to the input of the corresponding adder, characterized in that, in order to improve accuracy, the adders in it are connected through voltage-frequency converters to the first inputs of the valves connected by their combined outputs with a frequency-to-digital converter, while the outputs of the photodetectors of the corresponding quadrants through the comparators and the logic unit are connected to the second inputs of the valves, and the output is frequency-digital th converter is connected to the indicator. C <o c s os d Λsend -Bcosd - and si nd SU ... 1228280 FIG. 1