JP2003084037A - Signal waveform inspecting method and device for electronic circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and automatically determine whether the operation is normal or not at a number of inspection points of an electronic circuit incorporated in various electronic devices by each inspection point in a short time. SOLUTION: A signal waveform given from a designated inspection point of the electronic circuit 10 is imaged and displayed on an oscilloscope 4, and the displayed signal waveform is imaged by a CCD camera 5. The obtained image information is input to an image processing part 6, and the image information is recognized as an image pattern in the image processing part 6. The image pattern is compared with a registered pattern of the signal waveform of the inspection point previously input from the CCD camera or a touch panel to determine whether the output of the inspection point is normal or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic circuit signal waveform inspection method and apparatus for inspecting whether or not an electronic circuit incorporated in various electronic devices has a normal function.

[0002]

2. Description of the Related Art A general method for inspecting a signal waveform of an electronic circuit in the related art is to display an image of a signal waveform given from a predetermined inspection point of an electronic circuit to be inspected on an oscilloscope, and to display this image on an operator. There is known a method of visually judging whether the item is right or wrong. At this time, the inspection points are often switched manually.

Further, as an automatic inspection,
The signal waveform given from a predetermined inspection point of the electronic circuit to be inspected is recognized as a set of points, each point is digitized as coordinate position data, and this numerical data is input to the computer and pre-input. There is known a method of comparing with the numerical data of the normal signal waveform of the inspection point, which is determined to be normal when there is a match including the margin and abnormal when the mismatch. It is also known to compare a set of points as a function. In these cases, switching of inspection points is often automated.

[0004]

According to the conventional example carried out by the above-mentioned worker, the worker visually judges whether the signal waveform is right or wrong, and the inspection points are manually switched, so that the judgment requires skill and the processing time is long. On the other hand, there is an inconvenience that it is easy to make a mistake in judgment or a mistake in switching. Further, according to the above-mentioned automated conventional example, since it is a process using a computer, a judgment error or a switching error does not occur, but there is a disadvantage that it takes time to create a program and input data and work efficiency is poor. The present invention aims to eliminate these disadvantages.

[0005]

In order to achieve the above object, a method for inspecting a signal waveform of an electronic circuit according to the present invention recognizes a signal waveform given from a predetermined inspection point of the electronic circuit as an image pattern, This image pattern is compared with the image pattern of the signal waveform of the inspection point registered in advance to determine whether or not the signal waveform of the predetermined inspection point is normal. To recognize the signal waveform as an image pattern, for example, the signal waveform may be displayed as an image, and the image information obtained by imaging the displayed signal waveform may be recognized as an image pattern.

In the above inspection method, the signal waveforms registered in advance can be registered as waveforms that can be judged to be normal or abnormal, and these signal waveforms can be registered by an electronic camera such as a CCD camera or a touch panel. It can be performed as an image using an input means capable of inputting an image such as.

In order to achieve the above-mentioned object, the signal waveform inspecting apparatus for an electronic circuit according to the present invention also includes an inspection point switching section for sequentially switching connection with a large number of inspection points of the electronic circuit, and this inspection point switching. A switching control unit for controlling the switching operation of the unit, a signal waveform of an inspection point in a connected state provided through the inspection point switching unit, for example, a display unit including an oscilloscope, and a signal displayed on this display unit Image waveform, eg CCD
An image pickup unit including an electronic camera such as a camera, and image information of the signal waveform captured by the image pickup unit is recognized as an image pattern, and the recognized image pattern is registered in advance. And an image processing unit that determines whether or not the output of the inspection point is normal.

By providing an image information output section in which the functions of the display section and the image pickup section are integrated, the display section and the image pickup section can be replaced. Further, when it is determined that the image processing unit of the inspection apparatus is abnormal, the cause of the abnormality may be determined based on the shape of the abnormal waveform, and the cause of the abnormality may be output.

[0009]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Here, FIG. 1 is a block diagram showing the overall configuration of the apparatus, FIG. 2 is a block diagram showing the configuration of an image processing unit, and FIGS. 3 and 4 are waveform diagrams showing an input example of a registered pattern.

As shown in FIG. 1, a signal waveform inspecting apparatus 1 for an electronic circuit is a switching circuit 2 which is an inspection point switching section which is electrically connected to an electronic circuit 10 to be inspected and switches a connection relation with an inspection point. And a control unit 3 including a CPU that is a switching control unit that controls the switching operation of the switching circuit 2.
An oscilloscope 4 which is a display unit for displaying a signal waveform of an inspection point given through the switching circuit 2, a CCD camera 5 which is an imaging unit for imaging the signal waveform displayed on the display screen of the oscilloscope 4, and the CCD An image processing unit 6 is provided for inputting a signal waveform taken by the camera 5 and performing image processing to determine whether or not the output of the inspection point is normal and, if it is determined to be abnormal, the cause thereof.

The above-mentioned switching circuits 2 are n (n is an arbitrary integer, the same applies hereinafter) corresponding to the inspection points of the electronic circuit 10.
Output terminals 10a, 10b, 10c ... 10n of n input terminals 2a, 2b, 2c ...
It has 2n and one output terminal 2t. Also, a switch mechanism 2s for switching the connection relationship between each of the input terminals 2a, 2b, 2c ... 2n and the output terminal 2t.
have. The switch mechanism 2s receives the control signal from the controller 3 and receives the input terminals 2a, 2b, 2c ... 2n.
Any one of them is configured to perform a switching operation so as to be connected to the output terminal 2t.

The output terminal 2t of the switching circuit 2 is connected to the input terminal 4a of the oscilloscope 4. The oscilloscope 4 has, on its display screen 4b, output terminals 10a, 10b, 10c, corresponding to the inspection points of the electronic circuit 10.
.. The signal waveform output from 10n is displayed. Then, the CCD camera 5, which is an imaging unit that captures the signal waveform displayed on the display screen 4b of the oscilloscope 4, outputs the captured signal waveform to the image processing unit 6 as image data of, for example, 512 × 480 pixels. is doing.

As shown in FIG. 2, in the image processing unit 6 in which the signal waveform is input as image data, the input signal is input to the amplifier 6
Amplify with 0 and digitize with A / D converter 61,
It is output to the IC 62 dedicated to image processing. This image processing I
C62 divides the image data from the CCD camera 5 into, for example, 256 gradation levels for each pixel, extracts the gradation difference from this pixel data for each pixel, and performs difference processing calculation to form an image pattern for one screen. recognize. At this time, the margin correction setting is performed so that the image data has a slight width.
In the difference processing calculation of each pixel extracted and determined in the screen pattern, high speed processing can be performed while ensuring accuracy.

The image memory 63 connected to the image processing dedicated IC 62 stores in advance a normal or abnormal signal waveform for each inspection point as a registered pattern which is an image pattern. The registered pattern and the recognized image pattern are stored in advance. Is compared with the image processing-dedicated IC 62 to determine whether or not the output of the inspection point is normal from the correlation between both waveforms. This registered pattern is obtained by imaging the signal waveform of each inspection point of a normal or abnormal electronic circuit with a CCD camera and storing it in the image memory 63, or by using the liquid crystal display 66 as a touch panel type to normal or abnormal from this touch panel. Is input and stored in the image memory 63.

CCD camera 5 input to the image processing unit 62
The image data according to is determined to be normal as described above, and is displayed as an image on the liquid crystal display 66 via the image display controller 65 controlled by the CPU 64. At this time, the liquid crystal display 66 also displays the compared registered pattern as an image under the control of the CPU 64, and the judgment result of the normality made by the image processing IC 62 is, for example, “OK” or “NG”. Is displayed.

If the judgment result is abnormal, CP
The U64 determines the cause of the abnormality from the waveform shape and displays the cause of the abnormality together with the determination result. The determination of the cause of abnormality is made by comparing with the registered pattern of the abnormal waveform corresponding to the specific cause input to the image memory 63, as described above. The identification of the cause is ensured.

The CPU 64 has a program memory 67, is connected to a keyboard 68, and performs various necessary inputs from the keyboard 68. In addition, the CPU 64
Outputs a termination signal to the control unit 3 via the communication interface 69 when the determination result of whether the image processing-dedicated IC 62 is normal or not is output. Upon receiving this output, the control unit 3 outputs a switching signal to the switching circuit 2.

Next, the operation of the signal waveform inspection apparatus 1 described above will be described. In the state of FIG. 1, the switching circuit 2
The switch mechanism 2 s of the electronic circuit 10 has an output terminal 10 a
The input terminal 2a connected to is connected to the output terminal 2t, whereby the signal waveform of the inspection point of the electronic circuit 10 corresponding to the output terminal 10a is displayed on the display screen 4b of the oscilloscope 4. The displayed signal waveform is imaged by the CCD camera 5 and, for example, 512 × 480
The image data of the pixel is output to the image processing unit 6.

In the image processing unit 6, the input image data is amplified by the amplifier 60 and digitized by the A / D converter 61, and then the image processing dedicated IC 62 converts the image data for each pixel into, for example, 256 stages of floors. The tone difference is extracted for each pixel, and the gradation difference is extracted for each pixel, the margin correction is set, and the difference processing operation is performed to recognize it as an image pattern of one screen. The recognized image pattern is compared with a registered pattern, which is stored in the image memory 63 in advance and indicates a normal or abnormal signal waveform of the inspection point corresponding to the output terminal 10a, and whether the output of the inspection point is normal or not. The judgment result is displayed on the liquid crystal display 66 together with the compared signal waveforms. If the determination result is abnormal, the cause thereof is also displayed on the liquid crystal display 66.

When a determination result is output, the CPU 64 outputs an end signal to the control unit 3 via the communication interface 69, and the control unit 3 receiving this output outputs a switching signal to the switching circuit 2, The switch mechanism 2s is operated to release the connection with the input terminal 2a, while keeping the connection state with the input terminal 2b. As a result, the signal waveform of the inspection point corresponding to the output terminal 10b of the electronic circuit 10 is newly displayed on the display screen 4b of the oscilloscope 4. This signal waveform is picked up by the CCD camera 5, and it is determined whether or not the output of this inspection point is normal as described above. When a determination result is obtained, the switching signal of the control unit 3 which receives the end signal of the CPU 64 , The switch mechanism 2s operates again and the input terminal 2
While the connection with b is released, the input terminal 2c is connected.

By repeating such an operation, it is displayed on the display screen 4b of the oscilloscope 4 whether or not the signal waveforms of all the inspection points corresponding to the output terminals 10a to 10n of the electronic circuit 10 are normal. The signal waveform thus obtained is taken into the image processing unit 6 as image data picked up by the CCD camera 5, and the image pattern obtained by the image processing is compared with a registered pattern that has been input in advance to make a determination.

FIG. 3 shows an embodiment relating to input using a touch panel of a registered pattern, and is an example in which two waveforms P1 and P2 indicating the upper limit and the lower limit of a certain permissible range which can be judged to be normal by the touch panel are input. is there. The determination as to whether the signal waveform at the inspection point is normal in this embodiment is normal if the signal waveform is between the two waveforms P1 and P2, and abnormal if it is not.

FIG. 4 shows another embodiment of inputting a registered pattern, showing an example in which an abnormal waveform P3 is input. This abnormal waveform P3 is abnormal in that the broken line portion is missing. By registering the cause of the abnormality, even if the same waveform occurs at a certain inspection point in the electronic circuit to be inspected, it is possible to find the cause. Can be specified.

The present invention is not limited to the above-described embodiments. For example, the display section may be a CRT or a liquid crystal display in addition to the oscilloscope 4, and the image pickup section may be a CCD.
It is not limited to the camera 5. Further, the functions of the display unit and the image pickup unit may be integrated to form an image information output unit. Further, although the configuration of the image processing unit 6 is not limited to the illustrated example, the use of the image processing dedicated IC 62 improves the processing speed. Furthermore, it is not always necessary to determine the cause of abnormality in the image processing unit 6, and the liquid crystal display 66 may be configured to display only the determination result. Furthermore, it is also possible to simultaneously display the signal waveforms corresponding to a plurality of inspection points on the display screen 4b of the oscilloscope 4 and judge a plurality of signal waveforms at a time. In this case, the processing speed is further improved. be able to.

[0025]

As described above, according to the signal waveform inspection method and inspection apparatus for an electronic circuit of the present invention, it is automatically determined whether or not the operation at many inspection points of the electronic circuit is normal. In addition to requiring no skill, human error can be eliminated and accurate inspection can be performed in an extremely short time. Particularly, according to the invention described in claim 3,
The effect of facilitating the input of the image pattern of the signal waveform as the registered pattern is obtained, and according to the invention described in claim 6, by specifying the cause at the time of abnormality,
This has the effect of reducing the repair time.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of an apparatus.

FIG. 2 is a block diagram showing a configuration of an image processing unit.

FIG. 3 is a waveform chart showing one input example of a registered pattern.

FIG. 4 is a waveform chart showing another input example of a registered pattern.

[Explanation of symbols]

1 Signal waveform inspection device 2 switching circuit 3 control unit 4 oscilloscope 5 CCD camera 6 Image processing unit 10 electronic circuits

Continued front page    (72) Inventor Masaki Hagiwara             1-2260 Owada-cho, Saitama City, Saitama Prefecture               UMC Electronics Co., Ltd.             Inside the company (72) Inventor Yasuyuki Asaka             1-2260 Owada-cho, Saitama City, Saitama Prefecture               UMC Electronics Co., Ltd.             Inside the company F-term (reference) 2G132 AA12 AC03 AE14 AE16 AE18                       AH00 AL09 AL11                 5B057 AA03 BA02 BA26 DA03 DB02                       DB05 DB09 DC34

Claims (6)

[Claims] 1. A signal waveform given from a predetermined inspection point of an electronic circuit is recognized as an image pattern, and this image pattern is compared with an image pattern of a signal waveform of the inspection point registered in advance, A method for inspecting a signal waveform of an electronic circuit, comprising determining whether or not an output at a predetermined inspection point is normal. 2. The method for inspecting a signal waveform of an electronic circuit according to claim 1, wherein the signal waveform registered in advance is a waveform which can be determined to be normal or abnormal. 3. The input of the signal waveform registered in advance is input by an input unit capable of inputting an image, such as an electronic camera or a touch panel.
Alternatively, the method for inspecting a signal waveform of an electronic circuit according to claim 2. 4. An inspection point switching unit that sequentially switches connections to a large number of inspection points of an electronic circuit, a switching control unit that controls a switching operation of the inspection point switching unit, and an inspection point switching unit. An image information output unit that outputs the signal waveform of the inspection point in the connected state as image information, and an image of the signal waveform of the inspection point in which this image information is recognized as an image pattern and the recognized image pattern is registered in advance. A signal waveform inspection apparatus for an electronic circuit, comprising: an image processing unit that determines whether or not the output of the inspection point is normal by comparing with a pattern. 5. An inspection point switching unit that sequentially switches connections to a large number of inspection points of an electronic circuit, a switching control unit that controls a switching operation of the inspection point switching unit, and an inspection point switching unit. A display unit that displays the signal waveform of the inspection point in the connected state, an image capturing unit that captures the signal waveform displayed on this display unit, and image information of the signal waveform captured by this image capturing unit is recognized as an image pattern. An electronic device comprising: an image processing unit that compares the recognized image pattern with an image pattern of a signal waveform of the inspection point registered in advance to determine whether the output of the inspection point is normal. Circuit signal waveform inspection device. 6. The image processing unit, when it is determined to be abnormal,
The signal waveform inspection apparatus for an electronic circuit according to claim 4 or 5, wherein the cause of abnormality is determined based on the shape of the abnormal waveform and the cause of abnormality is output.