RU1778546C - Scale balancing device - Google Patents

Abstract

Use: for precision weight measurement. Creature: the device contains a compensation coil, a displacement sensor, an integrating pulse-width modulator connected to its output with a key with a current stabilizer, a correction unit connected by its input to the output of the displacement sensor, an amplifier connected by an output to the input of the display unit, and the unit The correction is made in the form of a resonant amplifier, the additional input of which is connected to the second output of the displacement sensor, and the output is connected to the first input of the pulse-width modulator, the second input of which The key to the output of the amplifier, both inputs of which are associated with respective movement sensor outputs, wherein the key is connected to the compensating coil. 1 ill.

Description

The invention relates to a weight measuring technique and can be used for precision weight measurement.

Self-balancing scales are known, comprising a beam, a suspension with a load cup, a motion sensor, an amplifier, a compensation coil, and a readout device.

Known scales do not have the required accuracy and speed due to the large inertia of this device.

Closest to the invention in technical essence is a digital system for automatic weight recording, comprising a compensation coil, a displacement sensor, an integrating pulse-width modulator connected to its output by a key with a stabilizer of a reference current, a correction unit connected by its input to the output

a motion sensor, an amplifier coupled to an output of an input of an indication unit.

The disadvantage of this system is the error associated with static friction and low noise immunity. a differential amplifier with a linear amplitude-frequency characteristic amplifies the high-frequency noise of the sensor and the inertia of the system, does not allow stability to be achieved at a high gain.

The purpose of the invention is to improve accuracy, speed and noise immunity.

To achieve the goal, the correction unit is made in the form of a resonant amplifier, the additional input of which is connected to the second output of the displacement sensor, and the output is connected to the first input of a pulse-width modulator, the second input of which is connected to the output of the amplifier, both inputs of which are connected to

with

VI VI

00

ate about

displacement sensor outputs, while the key is connected to the compensation coil.

The drawing shows the proposed device for balancing weights,

The device comprises a rocker 1, a displacement sensor 2, an amplifier 3, a parallel correction circuit based on a resonant amplifier 4, a weight registration unit 5, a summing pulse-width modulator b, on-off switch 7, current stabilizers 8, a balancing system - a permanent magnet in the compensation coil 9, the test sample 10.

The device operates as follows. When measuring the weight of the sample 10, the rocker moves and the signal of the displacement sensor 2 is fed to the amplifier 3 and aimed at parallel correction containing the resonant amplifier 4, the signal from the amplifier 3 is fed to the recording unit 5 and to the summing pulse-width modulator 6, to which the signal and from the parallel correction device 4. The modulator 6 controls the operation of the on-off switch 7, which switches the current direction from the stabilizer 8. The current flow causes the device 9 to compensate for the gain, proportionally e g A / T.

In order to improve accuracy, speed and noise immunity, the correction unit is made in the form of a resonant amplifier with a transfer characteristic:

KQ (o) R2 (1 / Ri + (o C / (w2LC - 1)).

The resonance frequency a) 1 / C (T is chosen so that the natural frequency of the oscillations of the weighing system is located on an increasing portion of the resonance curve. With this method of correction under the influence of current pulses in the compensating coil, the balance beam starts to make forced oscillations near the equilibrium position, i.e. the weighing system is in dynamic equilibrium, thereby eliminating the error associated with the presence of friction, and reducing inertia.

The amplifier also filters out high-frequency and low-frequency interference, which increases the noise immunity of the system.

Experimental studies of the proposed balance balancing device have shown that the claimed device provides. increase in speed by about five times, measurement accuracy by half with the same level of external and internal interference,

Claims (1)

The claims A balance balancing device, comprising a compensation coil, a displacement sensor, an integrating pulse-width modulator, connected to an output with a key with a stabilizer of a reference current, a correction unit connected to an input to an output of a displacement sensor, an amplifier connected to an output to an input of an indication unit, characterized in that, in order to improve accuracy, speed and noise immunity, the correction unit is made in the form of a resonant amplifier, the additional input of which is connected to the second output of the sensor displacement, and the output with the first input of a pulse-width modulator, the second input of which is connected to the output of the amplifier, both inputs of which are connected to the corresponding outputs of the displacement sensor, while the key is connected to the compensation coil.