SU1415035A1 - Time interval-to-displacement converting device - Google Patents

Abstract

The invention relates to a measurement technique and can be used to automate the processes of monitoring and measuring displacements. In order to improve the conversion accuracy by eliminating errors associated with the instability of the output voltage and frequency of the pulse generator, the reference voltage and changes in the dielectric constant of the medium, the device contains three diode-resistor circuits consisting of output diode optocouplers 2, 8, diode 5, resistors 3, 6, 9, 11 with connected capacitive sensor 4, supporting 7 and compensating 10 capacitors, which form two bridge nonlinear circuits. On exits mos

Description

four

Si

from 01

Voltage circuits are formed by the voltage proportional to the volt-second capacitance ijtaAH of the capacitive dat- ing process ijHKa 4, and the reference voltages that are integrated by the integrator 12 alternately. The driver of 14 pulses of constant duration that controls the resistor of the capacitance sensor - a 4 and a compensating capacitor 10, using optocouplers 2 and 8, are triggered from the null organ 13 at the moment of zero output zero, the voltage of the instructorpaTOpa 12. The maximum voltage of the integrator 12 formed by integrating the reference voltage over time determined my pulse duration shaper 14 decreases linearly during the time interval, dependent on the present value of volt-second area process discharge the capacitive sensor 4. Thus, the product of the time interval for the volt-second area remains constant. At the same time, the duration of the time interval formed at the inverse output of the shaper linearly depends on the displacement. 1 il.

15

:one

: The invention relates to a measuring technique and can be used to automate processes (monitoring and measuring displacements, i. The purpose of the invention is to increase the accuracy of 5 1) by eliminating the error associated with the instability of the outputs 5 | : one voltage and frequency of the generator 1-1 pulses, the reference voltage and changes in the dielectric constant of the medium.

I The drawing shows the block diagram of the device.

; The device contains a Pulse generator 1, a diode optocoupler 2, a resistor 3j capacitive sensor 4, a diode 5, a resistor b, a reference capacitor 7, a diode optocoupler 8, a resistor 9, a compensating capacitor 10, a resistor P, an integrator 12, a comparator 13, forming - rover 14 pulses; constant duration, the output bus 15 and 16 zero potential.

The output of the pulse generator 1 is through diode 5 and the output diodes of optocouplers 2 and 8 are connected to resistors 3, 6, 9 and 11, which are connected to the inputs of integrator 12. The code of integrator 12 through comparator 13 is connected to the input of shaper 14 of pulses of constant duration.

The device works as follows.

When the power is turned on, the output of the comparator 13 is set to one of the extreme values of the voltage

20

thirty

five

five

0

0

one or another polarity, for example, positive. Shaper 14 pulses of a constant duration are triggered by a positive voltage level, and pulses with a duration t are generated at its outputs. At the same time, the input diode of the optocoupler 2 is turned on and the input diode of the optocoupler 8 is turned off. The resistance of the recharge circuit of the capacitive sensor 4 is shunted by the small reverse impedance of the input diode of the optocoupler 2. With the equal shoulders of the bridge circuits and the appropriate choice of constant time of recharge of the capacitive sensor 4, the reference and compensating capacitors 7 and 10, the voltage at the output of the bridge circuit formed by the diode 5, the input diode of the optocoupler 8 and the resistors 9 and 11, is determined by the expression

Voi (GO); (one)

where Vfn is the maximum voltage

capacitive sensor 4, the reference and compensating capacitors 7 and 10, determined by the output voltage of the pulse generator 1;

f is the pulse frequency of the generator 1; R - recharge resistance

chains;

C is the capacity of the compensating capacitor 10;

GO capacitance reference capacitor 7.

The voltage V at the output of the bridge circuit formed by the input diode of the optocoupler 2, diode 5 and resistors 3 and 6 is determined by the expression

(2)

X1

,

The integrator 12 integrates the voltage difference U, and U, and at time tj, the voltage U at its output is set to

Uu - | - (Uo, -Uxn) - | -U fRCK, (3)

where T is the integration time constant. After the formation of the pulse tp is completed, the input diode of the optocoupler 8 is turned on and the input diode of the optocoupler 2 is turned off. The resistance of the overcharge circuit of the compensating capacitor 10 is shunted by the reverse resistance of the output diode of the optocoupler 8. and resistors 9 and 11, is determined in this case by

and

og

,

(four)

The voltage Ujf at the output of the bridge circuit formed by the output diode of the optocoupler 2, diode 5 and resistors 3 and 6, is determined by the expression

  Un, fR (Cx-Co), (5)

.

where Cx sensor capacity 4.

L

The integrator 12 integrates the voltage difference V and V j over time 15 (until the comparator 13 switches. The output voltage of the integrator 12 decreases linearly from level to zero, and when the comparator 13 switches, the constant pulse pulse generator 14 starts, after which the process repeats. Therefore, in view of (3)

BUT

 - - | - Un, fRCK - | - - (Cx - and tx to- || - X. (7)

The duration of the time interval tjf on the drives of the former 14 is determined by the ratio of the capacitances of the compensating capacitor 10 and the sensor A, as well as the pulse duration t

and does not depend on the instability of the output voltage and frequency of the pulse generator and changes in the dielectric constant of the medium. Invention Formula

A device for converting a displacement peQ into a time interval comprising a pulse generator, a first diode optocoupler, a diode, a capacitive sensor, a reference capacitor, a compensating capacitor, four resistors,

5 pulse generator of constant duration, zero potential bus and output bus, pulse generator output connected to the diode anode and cathode of the first diode output diode, the anode of which is connected to the first output of the capacitive sensor and through serially connected first, second, third and fourth resistors to the first terminal of the compensating capacitor of the capacitor, the cathode of the diode is connected to the first terminal of the reference capacitor and the common terminal of the second and third resistors, the second terminals of the capacitive sensor compensating for The capacitor, the reference capacitor and the anode of the input diode of the first optocoupler are connected to the zero potential bus, which is different from the fact that, in order to improve accuracy, an integrator, a second optocoupler, a comparator, the first conclusions, the second and third, fourth resistors. are connected respectively to the inverse and direct pins of the integrator, the output of which is connected to the inverse of the comparator, the output of which is connected to the input of the pulse shaper of a constant duration At the input diode of the first optocoupler, the inverted output of the pulse generator of constant duration is connected to the output bus and the cathode of the input diode of the second optocoupler whose anode is connected to the zero potential bus, the output of the pulse generator is connected to the cathode of the output diode of the second optocoupler whose anode is connected to the first output of the compensating capacitor, direct input of the comparator

five

0

five

connected to the zero potential bus.

Claims (1)

Claim A device for converting movement to a time interval containing a pulse generator, a first diode optocoupler, a diode, a capacitive sensor, a reference capacitor, a compensating capacitor, four resistors, a pulse shaper of constant duration, a zero potential bus and an output bus, the pulse generator output is connected to the diode anode and the cathode of the output diode of the first optocoupler, the anode of which is connected to the first output of the capacitive sensor and through the first, second, third and fourth resistors connected in series to the first terminal of the compensating capacitor, the cathode of the diode is connected to the first terminal of the reference capacitor and the common terminal of the second and third resistors, the second terminals of the capacitive sensor, the compensating capacitor, the reference capacitor and the anode of the input diode of the first optocoupler are connected to a zero potential bus, characterized in that, with In order to increase accuracy, an integrator, a second optocoupler, a comparator are introduced into it, the general conclusions of the first, second and third, fourth resistors are connected respectively to the inverse and direct output an integrator, the output of which is connected to the inverse input of the comparator, the output of which is connected to the input of a pulse shaper of constant duration, the direct output of which is connected to the cathode of the input diode of the first optocoupler, the inverse output of the pulse shaper of constant duration is connected to the output bus and the cathode of the input diode of the second optocoupler, anode which is connected to the bus of zero potential, the output of the pulse generator is connected to the cathode of the output diode of the second optocoupler, the anode of which is connected to the first output capacitor, the direct input of the comparator is connected to the zero potential bus. VNIIIPI Order 3861/36 _________ Circulation 680 Subscription Custom polygr. ave, city of Uzhhorod, st. Project, 4