JPS60191327A - Analog-to-digital converter - Google Patents

Abstract

PURPOSE:To simplify the constitution and the conversion accuracy of an A/D converter by using the reference voltage for checking conversion accuracy of the A/D converter main body to both the correction voltage of the converter and the control voltage of an input circuit with switching. CONSTITUTION:A scanner 15 of an A/D converter 1 performs (n+1) scans including (n) pieces of input and an input given from a constant voltage generating circuit 12 in a fixed cycle. A decoder 14 decodes the count value of the scanner 15, and this decoding result is supplied to a switching circuit 18. The circuit 18 supplies with priority the output of the decoder 14 to a multiplexer 13 in a measurement mode of a switch 123. Based on said decoding result, the multiplexer 13 sets the switch 123 to the correction side. Then the decoding result of the decoder 14 is locked, and the input given from the circuit 12 is selected by the multiplexer 13. Thus the reference voltage for checking conversion accuracy is used with switching to both the correction voltage for conversion and the control voltage of an input circuit 11. Thus the constituion of the converter 1 is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a technique for calibrating a main body of a converter constituting an analog-to-digital converter and adjusting an input circuit.

[Technical background of the invention]

FIG. 1 is a block diagram of a conventional analog-to-digital converter (hereinafter referred to as the device), which will be explained below.

The analog quantity is converted from an alternating current quantity to a direct quantity by an AC/DC conversion circuit 2, and is inputted to a number (n) of input circuits 11 in the device 1. Each input port i! 2i11 is a CR filter composed of multiple resistors and capacitors, and inputs an output voltage corresponding to the analog quantity to the multiplexer 13 at the next stage. The purpose of selecting one of the plurality of signals input to this multiplexer is to decode the output of the scanner 15, which is always operating at a fixed cycle, in the next stage decoder 14, and then send the decoded signal to the multiplexer. Give to 13'
do. Depending on the signal from the decoder 14, the multiplexer 13 opens only one input boot out of n inputs, and inputs the output voltage from the input circuit 11 to the analog-to-digital converter main body 16 (hereinafter referred to as the converter main body). . Further, the AD converter in the converter main body operates at regular intervals based on signals from the scanner 15. Then, the converted value converted from the Cyan/Japanese to the digital value by the converter body 16 is stored in the buffer 17. Constant voltage generation circuit 12 in device 1
outputs two types of voltage. One is accuracy voltage 121
It always generates a reference voltage and converts this voltage into an AD
The conversion accuracy of the AD converter in the converter main body 16 is verified to see if the converted results are always within tolerance. One calibration voltage 122 is a voltage for adjusting OP-AmP in the converter main body 16 and calibrating the AD converter.

During normal operation, 5W123 is set to the precision voltage side, and during maintenance and inspection, SW1/23 is switched to the calibration voltage side and operated. The connector bin 19 of the device 1 is for connecting external human power with a cable with a connector.

[Problems with background technology]

The above device has two types of voltages: a reference voltage for verifying the accuracy of the AD converter, and a calibration voltage for performing calibration, so it has the disadvantage that a voltage generation circuit must be installed independently, and that during maintenance and inspection. Although it is possible to calibrate the AD converter, it has the disadvantage that the input circuit cannot be easily adjusted by applying a constant voltage to the input circuit.

[Purpose of the invention]

The present invention has been made with the aim of solving the above problems, and uses a voltage to verify the accuracy of an AD converter. The object of the present invention is to provide an analog-to-digital converter that can be used as a reference voltage for input circuits or as a reference voltage for input circuits.

[Summary of the invention]

In the present invention, the voltage for checking the accuracy of the AD converter is shared as a calibration voltage during maintenance and inspection, and as a voltage for adjusting the input circuit.

[Embodiments of the invention]

Embodiments will be described below with reference to the drawings. FIG. 2 shows the configuration of an embodiment of the device according to the present invention.

Components other than the reference numeral 18 in the figure correspond to those in FIG.

The scanner 15 performs scanning for a total amount (n + 1) of n inputs and one person's power from the constant voltage generating circuit 12 at a constant cycle. The decoder 14 decodes the count value from the scanner 15 and inputs the result to the switching circuit 18. When the 5W 123 is set to the measurement side, the switching circuit 18 gives priority to the decoding result from the decoder 14 and inputs it to the multiplexer 13. If the decoding result at this time is the first, the multiplexer 13
opens the dart corresponding to the i-th input. When 5w123 is set to the calibration side, the decoding result from the decoder 14 is locked, and the (n+1)th corresponding input from the constant voltage generation circuit 12 is selected by the multiplexer 13. That is, one type of voltage from the constant voltage generating circuit 12 is used as an accuracy voltage for verifying the conversion accuracy of the AD converter during measurement, and as a calibration voltage during calibration.

'#g3 Figure shows the switching circuit 18 for one type of voltage. When 5W123 is on the measurement side, inverter element 182
The signal passed through two stages and the signal from the decoder 14 are ANDed by an AND element 183 (9), and the first scanning signal becomes valid when the condition is met. If 5W123 is used for calibration, all conditions of AND by AND element 183 will fail, but (n+
1) Since the next stage of the AND circuit constitutes an OR circuit with the OR element 184, it is inevitable that (n+
1) The IM position, that is, the position of the multiplexer 13 corresponding to constant voltage is selected. Resistor 181 is a pull-up resistor.

When adjusting the input circuit by inputting a constant voltage to the input circuit 11, since the output voltage from the constant voltage generating circuit 12 is output to the male connector bin 19, connect the female connector bin appropriately. If you prepare a connection between the bin 19 corresponding to the output voltage of the constant voltage generation circuit 12 and the bin 19 corresponding to the input circuit 11, and connect this female connector to the male connector of the device 1, A constant voltage input can be easily applied to the input circuit 11, and adjustment can be easily performed.

The above was for one type of voltage, but when performing the conversion accuracy of the AD converter for n = 3 points as Example 2,
Three types of voltages may be input from the constant voltage generation circuit 12 to the multiplexer 13, and the switching circuit 18 may be provided with a decoder for switching three (6) types of voltage positions. A block diagram of AD conversion is shown in FIG. 4, and a switching circuit is shown in FIG. 5 for explanation.

In FIG. 4, the numbers other than #'i and 124 in the figure are the third
Corresponds to the diagram. Output I4 from constant voltage generation circuit 12
Pressure + v, (V) wo (n+1) number, 10 v. Cv,
:+ wo (n+2), vt[v] is assigned to (n10a) and input to the multiplexer 13. The scanner 15 performs scanning for a total of (n+3) fits. The decoder 14 decodes the count value from the scanner 15 and inputs the signal to the switching circuit 18.

The switching circuit 18 transfers the decoded signal from the decoder 14 to the multiplexer 1 according to the states of the 5Ws 123 and 5Ws 124.
Output to 3. This 5W 124 is provided for the purpose of specifying the output voltage of the three glazes from the constant voltage output circuit 12. 3
The output voltage of Yuzu is connected to a connector bin 19 in addition to the multiplexer 13.

The operations of other circuits are exactly the same as in the first embodiment.

Next, referring to FIG. 5, the operation by switching between 5W123 and 5W124 will be explained. When 5W123 is set to the measurement side, the signal from the decoder 14 becomes valid and the multiplexer 13
The 1st to (n+3)th decoded signals are output for each of the signals, and the dart at the position corresponding to this signal is opened and AD converted. At this time, the state of 5W124 has no effect. Next, when the 5W123 is set to the calibration side, the decoded signal from the decoder 14 is divided into I:I, (n+1), (n
+2) and (n+3)th corresponding circuits are enabled. That is, when 5W124 is set to +V□ side, (n+
The decode signal of 1) is output, and when 5W124 is set to +V0, the decode signal of (n+2) is output, SW 12
4 to the -V1 side, (n+3) decoded signals are output, and the voltages corresponding to each number are input from the multiplexer 13 to the converter main body 16 at the next stage. That is,
During measurement, a three-complementary voltage is used for accuracy verification, and during calibration, three types of voltages can be selected as the voltage for calibration by switching SW 124. Furthermore, since all three voltages are connected to the connector pin 19, the input circuit 11's p
The adjustment can be easily performed using the method described in the first embodiment. Resistor 181, inverter element 182, AND element work 8 in the figure
3. The operation of the OR element 184 is the same as that explained in FIG. Although three types of voltages have been described, if these are set to n, the configuration can be easily configured by adding a circuit for specifying n types of voltages to the switching circuit 18 and a circuit for decoding the voltages.

〔Effect of the invention〕

As explained above, according to the present invention, the output voltage of the constant voltage generating circuit can be used in common as a voltage for accuracy verification and calibration of the AD converter without separation. Furthermore, during maintenance inspections, V uses this voltage to calibrate AD converters and input equipment (
It is possible to provide an analog-to-digital converter in which the input circuit can be easily adjusted using the AD converter alone without being affected by the AC/DC converter (for example, an AC/DC converter).

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional analog-to-digital converter, Fig. 2 is a block diagram of an embodiment of the analog-to-digital converter according to the present invention, and Fig. 3 is an implementation of a switching circuit for voltages of class -a. Example configuration diagram, FIG. 4 is another embodiment configuration diagram according to the present invention, FIG. 5 (Q) 2: AC/DC conversion circuit, 11: input circuit, 12: constant voltage generation circuit, 13: multiplexer, 14:
Decoder, 15: Scanner, 16: Analog-digital converter body, 17: Buffer, 18: Switching circuit, 19: Connector bin (male), 121: Accuracy voltage, 122: Calibration voltage, 123,
124: switch, 181: resistor, 182: inverter element, 183: AND element, 184: OR element. (10)

Claims (1)

[Claims] An analog-to-digital conversion device that sequentially outputs a plurality of analog quantities one by one in time series via a multiplexer controlled by a scanner, and converts this output electrical quantity into a digital quantity by an analog nib inotal converter main body, A reference voltage provided for checking the conversion sheath layer of the analog-to-digital converter main body is switched and shared as a voltage for calibrating the analog-to-digital converter main body and a voltage for regulating the input circuit. Analog-digital converter.