JPH01285867A - Voltage measuring circuit - Google Patents

Abstract

PURPOSE:To enhance accuracy, by measuring the output frequencies of a pair of voltage control oscillators controlled on the basis of the potential of a measuring voltage source according to reference frequency and subtracting the output data of respective counters. CONSTITUTION:The voltages at both terminals of a measuring voltage source 1 allowed to float with respect to the ground are inputted to voltage control oscillators (VCO) 2, 3 and the frequencies from the VCOS 2, 3 are counted by frequency counters 4, 5 according to the reference oscillation frequency from a reference oscillator 8. The outputs of two sets of the counters 4, 5 are subtracted, for example, by a subtractor 6 and the obtained value results in the reading of a change in the oscillation frequency and, since said value is equivalent to the potential difference between both terminals of the measuring voltage source 1, a measured value can be obtained from the subtraction result through a decoder 7. Therefore, accuracy, a measuring time and cost can be satisfied simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a voltage measuring circuit, and more particularly to a measuring force method that is effective when measuring a flowing voltage difference.

(Prior art) Conventionally, the methods for digitally measuring the city H are A,
There are the following two methods using a /D converter.

One of them is the integral method, which uses an integrator from an operational amplifier and a capacitor to integrate the human power signal and a reference voltage in the opposite direction, and then integrates it with the base power supply for comparing unknown human power signals. The output state of the device is checked by a comparator, and the width of the integrated stroke is measured by a pulse generator. Also, a counter measures time.

Therefore, the voltage of the unknown human input signal is determined.

The other method is the successive approximation method, which uses a comparator, a register for successive approximation, a D/8 register, and a base f.
The output voltage of the D/A converter is compared from the @L-fj bit of the successive approximation register so that it matches the input terminal, and must match. Set 1-1' sequentially and compare until 1) matches, using unknown human power.
: This is a method for determining Nt sweat.

(Problems to be Solved by the Invention) However, among the above-mentioned conventional methods, the integral method has a contradictory relationship between measurement accuracy and measurement time, and it has been difficult to satisfy both. - The problem of high cost due to the structure of the successive approximation method has been solved. As described above, it has been difficult to satisfy the factors of accuracy, measurement time, and cost.

The present invention is intended to solve the problem of stiffness, and it is an object of the present invention to provide a voltage measuring circuit that can simultaneously satisfy the factors of accuracy, measurement time, and cost.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a voltage measurement circuit that measures a voltage difference between both ends of a measurement voltage source of a voltage measurement target. A pair of voltage controlled oscillators controlled by the potentials at both ends, a pair of frequency counters that measure the frequency that is the output of each voltage controlled oscillator according to a reference oscillation frequency from a reference oscillator, and output data of each frequency counter is The feature is that it is equipped with an arithmetic unit that performs calculations or additions.

According to the present invention having the above-described configuration, the frequency that is the output of the pair of voltage controlled oscillators controlled by the potentials across the measurement voltage source is calculated from the reference oscillator by the pair of frequency counters. i'l is measured according to the reference oscillation frequency. Then, the 4Ii multiplier subtracts or adds the output data of each frequency counter 9, and the result of this operation is used to create a pair of :t
The changes in the total frequency of the tr controlled oscillator are read. This (11'+ is equivalently 71 to measure the pressure NIQ constant object?) is the voltage difference between both ends of the pressure source.

Therefore, the present invention can solve the above problems and provide a voltage measuring circuit that can simultaneously satisfy the following factors: accuracy, measurement time, and cost.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The attached page 1 is a block diagram showing the circuit configuration of an embodiment of the present invention. In the figure, reference numeral 1 denotes a measurement voltage source, which is the object of voltage measurement, and the voltage at both ends of this voltage source is assumed to be floating with respect to ground. 2.3 is a voltage controlled oscillator (hereinafter abbreviated as vCO), which changes the oscillation frequency according to the voltage value. 4.5 is the frequency counter,
v according to the reference oscillation frequency from the reference oscillator 8, which will be described later.
Count the frequencies from CO2 and CO3. 6 is a subtractor, 2
The output data of the pair of frequency counters 4 and 5 are subtracted. 7
A decoder converts the subtraction result of the subtracter 6 into display data to be displayed on a display device. A reference oscillator 8 outputs a reference oscillation frequency. Incidentally, it is necessary to use the same V(:02.3), and it may be one of 14·C oscillation or a digital type (for example, Motorola's MC4024).

Next, the circuit operation of this embodiment will be described. The voltage difference between both ends of the measurement voltage source is equal to λ of the oscillation frequency of two sets of Vll:02.3, and is supplied to the frequency counters 4 and 5, respectively.

Frequency counter 4.5 measures the frequency from vCO2, 3 according to the reference oscillation frequency from reference oscillator 8. The higher the oscillation frequency of VC (12, 3), the better the measurement speed and measurement accuracy at this time, and the conventional contradictory relationship between speed measurement 11 and measurement accuracy does not exist in this method. By supplying the reference oscillation frequency of the counter from one reference oscillator 8, trifle [cancellation] is achieved, and output fluctuations do not appear depending on the stability of the reference oscillator 8.Then, each output data of the two frequency counters 4 and 5 is subtracted by subtractor 6, and two sets of vCO2
, 3 is read, and since this change is equivalently equal to the voltage difference between both ends of the measurement voltage source, the potential of the measurement voltage source is read.

In the above embodiment, a subtracter is used, but an adder may also be used. In this case, it is necessary to offset the kneading process. Is it necessary to provide a If the output data from the adder and the voltage value output from the measurement voltage source are calibrated in advance, the voltage value of the measurement voltage source can be measured.

(Effects of the Invention) As explained in 1 below, according to the present invention, it is possible to satisfy the factors of accuracy, measurement time, and cost at the same time, and since it can be constructed using only digital circuits, it is also possible to implement it in an IC. Furthermore, when measuring the absolute value rather than the float-tained electric rf, there is an effect that measurement performance is improved by omitting a part.

[Brief explanation of the drawing]

The accompanying drawing is a block diagram showing the system configuration of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Measurement type L+- source, 2.3...Voltage controlled oscillator, 4.5...Frequency counter, 6...Subtractor, 7...Decoder, 8...Base ring oscillator .

Claims (1)

[Scope of Claims] A voltage measurement circuit that measures a voltage difference between both ends of a measurement voltage source to be measured, comprising: a reference oscillator; a pair of voltage-controlled oscillators controlled by a potential across the measurement voltage source; A pair of frequency counters that measure the frequency output from each of the voltage controlled oscillators according to a reference oscillation frequency from the reference oscillator, and an arithmetic unit that subtracts or adds the output data of each of the frequency counters. Features a voltage measurement circuit.