JP2008219466A - A/d convertor and abnormality detecting device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a smaller A/D conversion circuit to measure analogue signals containing an abnormal state at an input stage, even if a measuring terminal and a level comparison circuit are not provided on a substrate. <P>SOLUTION: An A/D convertor 100 comprises: a signal level conversion circuit 3 which branches from an input stage of an A/D conversion circuit 2 and compresses amplitude of the analogue signal at the input stage; a phase delay circuit 4 which shifts a specified phase of the signal after level conversion; a coupling circuit 5 which superposes a delay signal outputted from the phase delay circuit 4 on the output digital signal of the A/D conversion circuit 2; and a terminal 6 for outputting an output of the coupling circuit 5 to the outside. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides, for example, an A / D converter that can measure an abnormal state of an analog signal at an input stage in an A / D converter provided in an encoder or the like provided in an FA device, and the A / D converter. The present invention relates to an abnormality detection device using the

In a circuit that converts an analog signal into a digital signal, measurement of the analog signal at the input stage is effective for detecting an abnormality in the analog signal. As a conventional abnormality detection circuit, a technique is provided in which a detection circuit that measures an analog signal including an abnormal state of an input stage is provided, and the output of the detection circuit is measured through a dedicated terminal (for example, Patent Documents) 1).
In addition, a circuit for comparing the signal level of an analog signal including an abnormal state of the input stage is provided, and the comparison signal level is changed from the outside to measure the change in the pulse width of the digital signal in the output stage accompanying the change. Thus, it is shown that an abnormality is detected (for example, Patent Document 2).

JP 2003-248022 (P3, lines 31 to 50, FIG. 1) JP 02-223864 A (P3, lines 10 to 17, FIG. 3)

  In an A / D conversion circuit capable of detecting such an abnormal state of an analog signal, a circuit for detecting an abnormality, an additional circuit for providing a comparison signal, and a terminal for outputting an abnormality detection signal In addition, it is necessary to install a terminal for making the comparison signal variable on the circuit board. However, it has become difficult to respond to recent demands for downsizing and cost reduction of equipment with the above-described conventional technology.

  The present invention has been made to solve the above-described problems, and without adding a new terminal for outputting an abnormality detection signal or the like, by adding an inexpensive circuit, To provide an A / D conversion device that outputs an analog signal including an abnormal state to the outside, and to provide an abnormality detection device that detects an abnormality by measuring an output waveform using the A / D conversion device. It is aimed.

  An A / D conversion device according to a first aspect of the present invention is provided on a substrate, converts an input analog signal into a digital signal, and branches from an input stage of the A / D conversion circuit to input A signal level conversion circuit for compressing the amplitude of the stage analog signal, a delay circuit for shifting the level-converted signal by a predetermined phase amount, and the delayed signal and the output stage digital signal of the A / D conversion circuit are superimposed. A coupling circuit and a terminal for outputting a digital and analog superposition signal repeatedly output by the coupling circuit to the outside are provided.

  An abnormality detection apparatus according to a second invention is an abnormality detection apparatus including the A / D conversion apparatus according to the first invention and an output waveform analysis apparatus. The output waveform analysis apparatus includes an A An A / D conversion trigger signal generation circuit for generating a periodic trigger signal by inputting a repetitive signal output from the / D conversion device, and an analog / output signal output from the A / D conversion device based on the trigger signal An A / D conversion circuit that performs digital conversion and an abnormality determination that determines that an analog signal input to the A / D conversion device is abnormal by comparing the output of the A / D conversion circuit with a preset reference output value And a circuit.

  An A / D conversion device according to a first aspect of the present invention is provided on a substrate, converts an input analog signal into a digital signal, and branches from an input stage of the A / D conversion circuit to input A signal level conversion circuit that compresses the amplitude of the stage analog signal, a delay circuit that shifts the level-converted signal by a predetermined phase amount, and the delayed signal and the output stage digital signal of the A / D conversion circuit are superimposed And a terminal for outputting a digital and analog superimposed signal that is repeatedly output by the coupling circuit to the outside. Therefore, an input stage analog signal including an abnormal state in the A / D conversion circuit is Avoid the influence of noise that occurs due to changes in the output of the digital signal at the output stage. Can be output to the outside, miniaturization of the A / D converter circuit device including a substrate becomes feasible, also cost reduction can be achieved.

  An abnormality detection apparatus according to a second invention is an abnormality detection apparatus including the A / D conversion apparatus according to the first invention and an output waveform analysis apparatus. The output waveform analysis apparatus includes an A An A / D conversion trigger signal generation circuit for generating a periodic trigger signal by inputting a repetitive signal output from the / D conversion device, and an analog / output signal output from the A / D conversion device based on the trigger signal An A / D conversion circuit that performs digital conversion and an abnormality determination that determines that an analog signal input to the A / D conversion device is abnormal by comparing the output of the A / D conversion circuit with a preset reference output value Circuit, so that the signal output from the A / D converter, that is, the input stage analog signal including an abnormal state, is avoided the influence of the noise generated by the change in the output of the digital signal in the output stage. Then phase Since the output waveform analyzer analyzes the superimposed waveform, the processing routine for only a simple A / D conversion process regardless of the repetition period of the abnormal waveform at the input stage of the A / D converter. Measurement can be performed with the, and the abnormality determination process can be simplified without being affected by noise. Furthermore, there is an effect that an analog waveform can be measured even when a pulse is missing.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram showing an A / D conversion apparatus 100 according to Embodiment 1 of the present invention. An analog signal is input from an external sensor input 1 to the A / D conversion device 100 provided on the substrate 7 and connected to the input stage of the buffer IC 2. In the buffer IC2, which is an A / D conversion circuit, the analog signal changes to high and low according to the internal reference level, and is output as a digital signal from the output stage. The analog signal at the input stage is bifurcated and connected to the signal level conversion circuit 3, and the signal level conversion circuit 3 has a sufficiently small value, for example, 1/10 to 1/5 of the digital output signal. Converted to signal level. The converted signal is connected to the delay circuit 4 and is sufficient to avoid the influence of noise generated with the output change of the rise and fall of the buffer IC2, that is, stable without noise after the rise and fall. The phase is delayed by a predetermined DL shown in FIG. 2 (d) at the time when the waveform area is reached, and is input to the coupling circuit 5. The coupling circuit 5 generates and outputs a signal obtained by superimposing the phase delayed signal and the output signal of the buffer IC 2, and the output signal is output from the terminal 6 to the outside.
FIG. 2 shows the waveform processing progress of the A / D conversion apparatus 100 according to the first embodiment of the present invention. FIG. 2A shows an analog signal of the measurement point A input from the sensor input 1. In the first embodiment, a signal with a small amplitude is used as an abnormal signal as shown in FIG. The signal level conversion circuit 3 converts the signal to the analog signal shown in FIG. 2C at the measurement point C, and the delay circuit 4 converts the analog signal after the delay processing shown in FIG. . On the other hand, the analog signal shown in FIG. 2A at the measurement point A is converted into a digital signal shown in FIG. 2B at the measurement point B by the buffer IC2. In the coupling circuit 5, the analog waveform after the delay processing at the measurement point D (FIG. 2D) and the digital signal at the measurement point B (FIG. 2B) are superimposed, as shown in FIG. Is converted into a digital signal at measurement point E, and this signal is output.

The digital signal (FIG. 2 (e)) of the measurement point E, which is an output signal, has the features of the analog signal waveform at the input stage superimposed on the digital waveform as the feature amount X and feature amount Y, and the feature amount Y Can detect an abnormal signal whose amplitude is smaller than the feature amount X and whose input amplitude is small. Here, the feature amount X is assumed to be in a state where the analog signal waveform at the input stage is normal, and the feature amount Y is assumed to be in an abnormal state.
FIG. 2E shows an example in which the amplitude is feature quantity X> feature quantity Y. However, the present invention is not limited to this example, and there may be a case where feature quantity X <feature quantity Y.
According to this configuration, it is possible to detect an abnormal signal by outputting an analog signal of an input stage including an abnormal state to the outside without adding a terminal for extracting the analog signal to the outside.
Next, an example is shown. The A / D conversion device 100 according to the first embodiment is provided in, for example, a mass-produced FA device (factory automation device). Detection of an abnormal waveform of the analog signal output from the FA device is confirmed at the product testing stage in the manufacturer's factory. That is, a dedicated waveform analysis device is connected to the terminal 6 of the A / D converter 100 shown in FIG. 1 in the factory, for example, the feature quantity X is set as a preset reference output value, and the feature quantity Y / feature quantity X Is less than a predetermined value (when X> Y), when it is equal to or greater than a predetermined value (when X <Y), or when | feature amount X-feature amount Y | This confirms the product of the FA device. The quality of the FA device after delivery to the customer can be confirmed by the same procedure, for example, at the time of regular inspection.
As described above, the A / D conversion device 100 according to the first embodiment can be downsized without requiring any special additional circuit or terminal as in the prior art, and can easily detect an abnormal signal of an analog signal in the input stage. Can be detected.
The buffer IC 2 may be a comparator IC or an inverter IC, and the signal level conversion circuit 3 and the delay circuit 4 may be exchanged in order of paths or may be configured by a circuit in which both are integrated.

Embodiment 2. FIG.
Next, a second embodiment will be described.
FIG. 3 is a block diagram showing an abnormality detection apparatus 300 for a signal repeatedly output according to Embodiment 2 of the present invention. The output waveform analyzing apparatus 200 for analyzing the output waveform is added to the A / D conversion apparatus 100 of the first embodiment described above, and the output waveform analyzing apparatus 200 is an analog output from the A / D conversion apparatus 100. An A / D conversion circuit 17 for acquiring a waveform obtained by superimposing a digital waveform on the waveform as digital data, an A / D conversion trigger signal generation circuit 18 for generating a waveform acquisition timing, and an A / D conversion circuit 17 It is composed of an abnormality determination circuit 19 that determines abnormality from the / D converted data.
FIG. 4 is a diagram showing the operation of the output waveform analysis device 200 in the abnormality detection device 300 according to Embodiment 2 of the present invention. The output signal of the A / D conversion device 100 is output by the output waveform measurement cable 16. The trigger period 20 is generated at the rising timing of the digital signal by the A / D conversion trigger signal generation circuit 18 connected to the analysis device 200, and the conversion start trigger signal is transmitted to the A / D conversion circuit 17. The A / D conversion trigger signal generation circuit 18 starts the conversion of the A / D conversion circuit 17 at a predetermined timing DL sufficient to avoid the influence of noise, as in the first embodiment. Output a delayed signal. The A / D conversion circuit 17 receives the trigger signal and performs A / D conversion at the sampling period 21. The conversion result is shown as feature quantities x and y in FIG. The abnormality determination circuit 19 inputs an A / D conversion result and determines an abnormality. In this case, for example, the feature value x is set as a reference output value when the analog input of the A / D conversion apparatus 100 is set in advance, and the feature value y / feature value x is equal to or less than a predetermined value (x> y). ) Or above a predetermined value (when y> x), or when | feature quantity x-feature quantity y | is above a predetermined value, the analog input signal to the A / D converter 100 is determined to be abnormal. It is.
According to this configuration, it is possible to measure an abnormal waveform in a repeated input stage with the same processing routine that includes only a simple A / D conversion process regardless of the repetition period, thereby simplifying the abnormality determination process. Furthermore, as shown by the feature value z in FIG. 4, there is an effect that an analog waveform can be measured even when a pulse is missing.

  The A / D conversion device according to the first embodiment of the present invention can be used for a general electrical measurement device, and the abnormality detection device according to the second embodiment is a general electrical measurement device. The present invention can be used for an apparatus that detects an abnormality in an input stage.

1 is a configuration diagram illustrating an A / D conversion device according to a first embodiment. It is a figure which shows the waveform process progress of the A / D converter of Embodiment 1. FIG. It is a block diagram which shows the abnormality detection apparatus of Embodiment 2. It is a figure which shows operation | movement of the output waveform analyzer of the abnormality detection apparatus of Embodiment 2. FIG.

Explanation of symbols

1 sensor, 2 buffer IC, 3 signal level conversion circuit, 4 delay circuit,
5 coupling circuit, 6 terminals, 7 substrate, 17 A / D conversion circuit,
18 A / D conversion trigger signal generation circuit, 19 Abnormality determination circuit,
100 A / D converter, 200 output waveform analyzer, 300 abnormality detector.

Claims (6)

An A / D conversion circuit which is provided on the substrate and converts an input analog signal into a digital signal; a signal level conversion circuit which branches from the input stage of the A / D conversion circuit and compresses the amplitude of the input stage analog signal; A delay circuit for shifting the level-converted signal by a predetermined phase amount, a coupling circuit for superimposing the delayed signal and the output stage digital signal of the A / D conversion circuit, and the coupling circuit repeatedly outputting A digital / analog conversion apparatus comprising a terminal for outputting an analog superimposed signal to the outside. An abnormality detection device comprising the A / D conversion device according to claim 1 and an output waveform analysis device, wherein the output waveform analysis device includes a repetitive signal output from the A / D conversion device. A / D conversion trigger signal generation circuit for generating a periodic trigger signal, and A / D conversion for analog / digital conversion of the output signal of the A / D conversion device based on the trigger signal A circuit and an abnormality determination circuit that determines that an analog signal input to the A / D converter is abnormal by comparing the output of the A / D converter circuit with a preset reference output value. An abnormality detection device characterized by the above. The predetermined phase amount shifted by the delay circuit is a phase amount at the time when a stable waveform region free from noise after rising and falling of the output stage of the A / D conversion circuit is reached. 1. The A / D conversion device according to 1. 2. The A / D conversion apparatus according to claim 1, wherein the signal level conversion circuit compresses the digital output signal of the A / D conversion circuit to a signal level of 1/10 to 1/5. The abnormality determination circuit determines an abnormality when a ratio of an output of the A / D conversion circuit to a preset reference output value is either a predetermined value or less or a predetermined value or more. Item 3. The abnormality detection device according to Item 2. The abnormality detection circuit according to claim 2, wherein the abnormality determination circuit determines that an abnormality occurs when a difference between the output of the A / D conversion circuit and a preset reference value output is a predetermined value or more. apparatus.

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