JPS62261072A - Potential difference measuring apparatus - Google Patents

Abstract

PURPOSE:To measure a potential between two points specified on a time axis, by detecting inversion of output of a comparator at first and second measuring points to compute a difference between both data thus obtained. CONSTITUTION:A signal to be measured is supplied to a comparator 1 to be compared with an output of an A/D converter 7 and an output of the comparator is supplied to FFs 2 and 3 separately. A measuring section signal is supplied to the FF 3 as clock signal through the FF 2 and an inverter 4. Then, with the starting point of the measuring section signal as first measuring point, inversion of an output of the comparator 1 at this measuring point is detected by a Q output of the FF 2 and a count value (a) of the counter 6 at this point is supplied to a control computation circuit 5. Moreover, with the ending point of the measuring section signal as second measuring point, inversion of an output of the comparator 1 at this measuring point is detected by a Q output of the FF 3 and a count value (b) of the counter 6 at this point is supplied to the circuit 5. Then, the computation (a-b) of count values is done. This enables the measuring of a potential difference between two points specified on a time axis with a simple construction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Graduate field of application) The present invention relates to a potential difference measuring device, and more particularly to a potential difference measuring device that measures a potential difference between two points, such as a signal displayed on an oscilloscope.

(Prior Art) A conventional method for measuring potential difference is a method using a voltmeter, a digital multimeter, or the like.

Another method used is to display the signal to be measured on the tube surface of an oscilloscope and read the scale on the tube surface.

(Problem to be Solved by the Invention) However, in the latter case, it is rare that the voltage can be read directly from the waveform displayed on the screen, and it is necessary to convert it taking sensitivity into account, or to calculate the voltage in relation to the scale. There was an issue where it was difficult to read.

SUMMARY OF THE INVENTION An object of the present invention is to provide a potential difference measuring device that solves the above-mentioned problems, and in particular, a potential difference measuring device that can measure the potential difference between two designated points on the time axis.

(Means for Solving the Problems) In order to solve the above problems, the present invention is constructed as follows.

a digital/analog conversion means, a data supply means for outputting digital data to the digital/analog conversion means, an analog comparator for comparing the analog signal converted by the digital/analog conversion means with the signal under test; a first detection means for detecting an inversion of the analog comparator output at one measurement point; and a second detection means for detecting an inversion of the analog comparator output at a second measurement point.
and changing the output digital data from the data supply means, reading the output digital data from the data supply means when the analog comparator output by the first detection means is inverted, and detecting the second detection means. an operation for reading the output digital data from the data supply means when the analog comparator output is inverted by the means, and calculating the potential difference between the first measurement point and the second measurement point from the difference between the read digital data; equipped with means.

(Function) The output digital data of the data supply means is changed by the digital data from the calculation means, and the output digital data from the data supply means is supplied to the digital/analog conversion means and converted into an analog signal. This analog signal is modified by output digital data output from the data supply means. The analog signal output from the digital/analog conversion means and the signal under test are compared in an analog comparator, and the first detection means detects the inversion of the analog comparator output at the first measurement point, and the data at this time is The output digital data of the supply means is read into the calculation means. The output digital data of the data supply means at this time corresponds to the signal level under measurement at the first measurement point.

Similarly, the inversion of the analog comparator output at the second measurement point is detected by the second detection means, and the output digital data of the data supply means at this time is read into the calculation means. The output digital data of the data supply means at this time corresponds to the signal level under measurement at the second measurement point.

A calculation means calculates the difference between the two read digital data. Therefore, this difference corresponds to the difference between the measured point level at the first measuring point and the measured point level at the second measuring point. The potential difference will be measured.

(Example of the invention) The present invention will be explained below with reference to Examples.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

The signal to be measured is supplied to analog comparator 1, and digital/
It is compared with the output of an analog converter (hereinafter referred to as a D/A converter) 7. The output of analog comparator 1 is sent to latch circuits 2 and 3.
Supplied as data.

The measurement interval signal is supplied to the latch circuit 2 as a clock signal, and the measurement interval signal via the inverter 4 is supplied to the latch circuit 3 as a clock signal.

The control calculation circuit 5 supplies clock pulses to a counter 6, and the count value of the clock pulses by the counter 6 is supplied to a D/A converter 7.

On the other hand, the Q outputs of latch circuits 2 and 3 are controlled by control calculation circuit 5.
The starting point of the measurement period signal is set as the first measurement point, and the Q output of the launch circuit 2 detects whether the output of the analog comparator 1 is inverted, and the output of the analog comparator 1 is set as the first measurement point. When the output of the analog comparator 1 is inverted at the measurement point, read the count value (al) of the counter 6 and use the Q output of the latch circuit 3 to detect whether the output of the analog comparator 1 is inverted, using the end point of the measurement interval signal as the second measurement point. However, when the output of the analog comparator 1 is inverted at the second measurement point, the count value (b) of the counter 6 is read and the calculation (a-b) is performed.

Now, an example of the signal waveform to be measured is as shown in Figure 2 (al).The measurement interval signal is a signal of logic "1" (hereinafter simply referred to as high potential), and is, for example, a sweep interval signal of an oscilloscope. Alternatively, it may be a signal created using a sweep section signal.

The counter 6 counts clock pulses output from the control calculation circuit 5, and the counted value is converted into an analog signal by the D/A converter 7, and compared with the voltage to be measured in the analog comparator 1.

It is now assumed that the initial setting value for the D/A converter 7 is "0" and the counter 6 performs up-counting.

Therefore, each time the clock pulse from the control calculation circuit 5 is received, the analog signal level of the D/A converter 7 increases. (i) When the analog signal level of the D/A converter 7 is “A”, the Q outputs of the latch circuits 2 and 3 are at a low potential at the beginning and end of the measurement period, and are lower than the signal level under measurement. I understand that. (ii) When the analog signal level of the D/A converter 7 is "B", the Q output of the latch circuit 2 is at a high potential at the beginning position of the measurement section, and the Q output of the latch circuit 2 is at a high potential at the end position of the measurement section. The Q output of
' and "b". (iii
) When the analog signal level of the D/A converter 7 is at "C" and "D", the Q outputs of the latch circuits 2 and 3 are at a high potential at the beginning and end of the measurement period, and the It turns out that the level is higher.

However, the analog signal level of the D/A converter 7 changes sequentially as the count value of the counter 6 increases. As a result, the Q of the latch circuit 2 at the leading edge of the measurement interval signal is
When the output changes from a low potential to a high potential, it is detected that the output of the analog comparator 1 is inverted, and the count value (a) of the counter 6 at this time is read.

Similarly, the Q of the latch circuit 3 at the trailing edge of the measurement period signal
It is detected that the output of the analog comparator 1 is inverted due to the change in the output from a low potential to a high potential, and the count value (b) of the counter 6 at this time is read.
Then, the calculation (a-b) is performed, and the second circuit 2.
3 and counter 6 are reset.

Therefore, the potential difference between two specified points on the time axis can be obtained.

Although the above-described embodiment uses the counter 6 as an example, a register may be used instead of the counter 6. When a register is used, the value set therein is given by the control arithmetic circuit 5. For example, once a predetermined set value is given, the set value may be sequentially changed by incrementing or decrementing. Also, it may be changed arbitrarily.

In the above explanation, the case where the voltage to be measured shows a local minimum value near the beginning and near the end of the measurement interval as shown in FIG. , 3 can detect the inversion of the output of the analog comparator 1.

Measurement is particularly easy when the signal under test has a repetitive waveform.

(Effects of the Invention) As explained above, according to the present invention, the potential difference between two points specified on the time axis can be measured with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a waveform diagram for explaining the operation of one embodiment of the present invention. 1... Analog comparator, 2 and 3... Latch circuit, 4... Impark, 5... Control calculation circuit, 6...
-Counter, 7...D/A...converter.

Claims (3)

[Claims] (1) Digital/analog conversion means, data supply means for outputting digital data to the digital/analog conversion means, and an analog comparator for comparing the analog signal converted by the digital/analog conversion means with the signal under test. a first detection means for detecting an inversion of the analog comparator output at a first measurement point; a second detection means for detecting an inversion of the analog comparator output at a second measurement point; changing the output digital data from the supply means, reading the output digital data from the data supply means when the analog comparator output by the first detection means is inverted, and changing the output digital data from the analog comparator output by the second detection means; calculation means for reading the output digital data from the data supply means at the time of inversion, and calculating the potential difference between the first measurement point and the second measurement point from the difference between the read digital data. Characteristic potential difference measuring device. (2) The potential difference measuring device according to claim 1, wherein the data supply means is a pulse counting means for counting count pulses supplied from the calculation means. (3) The potential difference measuring device according to claim 1, wherein the data supply means is a register in which digital data is set by the output from the calculation means.