JPH0679051B2 - Abnormal waveform inspection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormal waveform inspection apparatus, and in particular, apart from a device under test, it has almost the same function as a non-defective device or a device under test. The present invention relates to an abnormal waveform inspection apparatus which is provided (hereinafter referred to as standard device) and compares the output waveforms of the standard device and the device under test to perform inspection.

Configuration of Conventional Example and Problems Thereof The abnormal waveform inspection apparatus detects a signal waveform output to a device under measurement and determines pass / fail according to the waveform. The simplest method of detecting the signal waveform is to directly observe the signal waveform using an oscilloscope or the like.

Figure 1 shows a conventional bucket bricade device (BB
This is a block configuration of the inspection device of this type used for the inspection of D). FIG. 2 is an operation waveform diagram of an essential part of FIG. The circuit operation will be described below with reference to these drawings.

The device under test (BBD) 1 is connected to the second from the signal input terminal 2
The input signal shown in FIG. 3A is given through the capacitor 3, and a clock signal (not shown) is further applied from the clock signal input terminal 4. Next, when a DC bias was set from the bias source 5 within the region where the device under test 1 operates normally, the non-defective device was delayed from the input signal by a predetermined time t ₁ as shown in FIG. 2B. It appears on the oscilloscope 6 as an output signal. However, when the device under test 1 is defective, the output waveforms are, for example, as shown in FIGS. Conventionally, since the series of inspection work for judging the quality is mainly based on the visual judgment of the inspector, there has been a limit to the accurate and quick inspection.

An object of the present invention is to provide an abnormal waveform inspection apparatus which eliminates the above-mentioned inconvenience.

According to the present invention, in order to achieve the above-mentioned object, an amplitude value and a pulse width are respectively greater than those of the first pulse in synchronization with a first pulse and the first pulse in correspondence with a predetermined input signal. A pair of signal generating means for generating a small second pulse and supplying the first pulse to the standard device and the second pulse to the device under test, and an output signal of the standard device. Is a single input via an amplitude unit and a first comparator having the output signal of the device under test as the other input and an output signal from the first comparator as one input, and a reference voltage The abnormal waveform inspection apparatus includes a second comparator which is the other input, and means for detecting an output signal from the second comparator and determining acceptability according to the detected value. According to this, the inspection circuit device can be simply configured, and in addition, automatic inspection can be performed.

Description of Embodiments FIG. 3 shows an abnormal waveform inspection apparatus according to an embodiment of the present invention. First, the feature of the abnormal waveform inspection apparatus of the present invention is that it uses a standard device having almost the same function as the device under test, but as this standard device, it is convenient if it is a non-defective device among the devices under test. Is. This is because, if the same input signal is applied to both of them at the same time, the amplitude values, pulse widths, phase delays, etc. of the output signals are almost the same, so the inspection can be performed only by comparing the output signals of both. is there. This can be understood from the fact that, without using the standard device here, for example, an apparatus for inspecting a BBD needs a means for detecting the amplitude value, pulse width, phase difference, etc. of the output signal, respectively. See.

FIG. 4 shows an operation waveform diagram of an essential part of FIG.
This is the case when the device under test is a non-defective item. The circuit operation will be described below with reference to these drawings.

An input signal shown in FIG. 4A is applied to the standard device 7 from the signal input terminal 8 via the capacitor 9 and the buffer 10. Further, when a predetermined DC bias is applied from the bias source 11 and the switch 12 is connected to the side a, the output signal of the standard device 7 is sent to the point X on the side of the standard device 7 via the amplifier 23 as shown in FIG. As shown in, the signal appears as an output signal having an amplitude value H ₁ and a pulse width W ₁ delayed by t ₂ from the input signal. Reference numeral 13 is a clock signal input terminal.

On the other hand, the same input signal as that added to the standard device 7 is also applied to the device under test 14 from the signal input terminal 8 through the capacitor 15,
It is provided via the buffer 16. Further device under test
The DC bias of 14 is, for example, a microcomputer 17
Is supplied via a resistor 19 from a programmable power supply 18 controlled by. Here, if the switch 12 is connected to the low side to set the DC bias from the programmable power source 18 to a predetermined value different from the DC bias of the bias source 11, for example, a lower level than that, input signal applied to 8, are level fluctuation by a DC bias is added via a resistor 19, to the point Y of the measuring device 14 side, as shown in FIG. 4 c, the amplitude value H _2, the pulse width The output signal waveform of W ₂ appears. The output signals shown in FIGS. 4b and 4c generated at the points X and Y are applied to the comparator 22 by connecting the switch 12 to the side a and via the resistors 20 and 21, respectively. Note that, here, the amplitude value H ₁ and the pulse width W ₁ of the output signal shown in FIG. 4b on the side of the standard device 7 are the amplitude of the output signal generated on the side of the device under test at the point Y. It is desired to set the value to be slightly larger than the value H ₂ and the pulse width W ₂ . This is because the device under test 14 is subject to variations in manufacturing conditions, etc.
This is due to the fact that the amplitude value, pulse width, etc. of the output signal vary within a range acceptable as a non-defective device. The amplifier 23 is for ensuring the relationship of H ₁ > H ₂ between the amplitude values H ₁ and H ₂ in consideration of the variation of the device under test. Further, the relationship of W ₁ > W ₂ between the pulse widths W ₁ and W ₂ is set by setting the DC bias values of the bias source 11 and the programmable power supply 18, for example, the programmable power supply 18 side is set. It is possible to lower it.

When the output signal shown in FIGS. 4b and 4c is applied to the comparator 22, a substantially zero voltage is generated at the output point P as shown in FIG. 4d. Further, this voltage is applied to one input terminal of the comparator 24. Where the comparator 24
If the reference voltage source 25 is set to the other input terminal of the above, a substantially zero voltage is generated at the output point Q of the comparator 24 as shown in FIG. This voltage is converted into a DC voltage by the DC conversion means 26, and is further sent to the A / D converter 27, and the microcomputer 17 determines whether the device under test 14 is good or bad. The fourth diagram is an example of the case where the device under test 14 is a non-defective product, so that if the voltage generated at the output Q point of the comparator 24 is, for example, 100 (mV) or less, it is A, which corresponds to this value. The signal from the / D converter 27 should be good.

Next, FIG. 5 shows an example in which the device under test 14 is defective. FIG. 5a shows an input signal supplied to the signal input terminal 8, and FIG. 5b shows an output signal generated at the point X on the standard device 7 side. FIG. 5c shows an output signal generated at point Y on the device under test 14 side, and this signal waveform is the same as the output waveform of the defective device already shown in FIG. 2c. When the signals shown in FIGS. 5b and 5c are applied to the comparator 22, an output signal shown in FIG. 5d is generated at the output P point, the output signal is given to the comparator 24, and further to the input terminal 25. When compared with the set reference voltage, an output signal shown in FIG. further,
This output signal is converted into a DC voltage by the DC conversion means 26 and is converted into A /
The D converter 27 converts the analog signal into a digital signal and sends it to the microcomputer 17 to determine that it is defective.

Effects of the Invention As described above, the abnormal waveform inspection apparatus of the present invention is provided with the standard device having substantially the same function as the device under test, simultaneously applying the same input signal to both of them, and comparing these output signals, Since the quality of the device under test is determined by detecting the difference in the waveform, the inspection circuit can be configured very easily. In addition, automatic inspection is possible, so its industrial value is great.

[Brief description of drawings]

FIG. 1 is a diagram showing a conventional abnormal waveform inspection device, FIG. 2 is an operation waveform diagram of an essential part of FIG. 1, and FIG. 3 is a diagram showing an abnormal waveform inspection device according to the present invention. The figure shows the operation waveform diagram of the main part of FIG. 3 when the device under test is a good product and a defective product, respectively. 7 ... Standard device, 8 ... Signal input terminal, 9,15 ... Capacitor, 10,16 ... Buffer, 11 ... Bias source, 12
...... Switch, 13 …… Clock signal input terminal, 14 …… Device under test, 17 …… Microcomputer, 18 …… Programmable power supply, 19,20,21 …… Resistor, 22,24 …… Comparator, 25 …… Reference voltage source, 26 ... DC conversion means, 27 ...
… A / D converter.

Claims (2)

[Claims] 1. A first pulse and a second pulse having an amplitude value and a pulse width each smaller than the first pulse are generated in synchronization with the first pulse in response to a predetermined input signal. And applying the first pulse to the standard device and the second pulse to the device under test, respectively.
A pair of signal generating means, a first comparator that outputs the output signal of the standard device as one input via an amplifier, and an output signal of the device under test as the other input, and from the first comparator A second comparator having the output signal of 1 as one input and the reference voltage as the other input, and means for detecting an output signal from the second comparator and determining acceptability according to the detected value, An abnormal waveform inspection device equipped with. 2. The abnormal waveform inspection apparatus according to claim 1, wherein the means for determining the quality includes DC conversion means, an A / D converter, and a microcomputer.