JPS63168576A - Electronic circuit measuring apparatus - Google Patents

Abstract

PURPOSE:To enable high-speed measurement, by operating a D/A converter into which is inputted an input data for measurement and an A/D converter into which is inputted a signal from an electronic circuit to be measured by the same reference clock pulse. CONSTITUTION:A measuring input data stored in a data memory section 4 is converted into an analog signal with a D/A converter 5 to be applied to a circuit 1 to be measured. An output of a detection circuit 7 which detects an output of the circuit 1 is converted into a digital signal with an A/D converter 15 to be applied to a memory 16. Operations of the converters 5 and 15 and a mode control circuit 19 for switching modes of the circuits 1 and 7 are all performed synchronously by a reference clock pulse generated with a reference clock pulse generation circuit 2. This enables synchronization among the switching of operation modes, application of a measuring input signal and fetching of signals from the circuit 1, thereby permitting high-speed measurement of characteristics of an electronic circuit in various operation modes.

Description

[Detailed description of the invention] The present invention will be described in the following order.

A. Industrial field of application B9 Summary of the invention C9 Prior art 1 Problems to be solved by the invention E0 Means for solving the problems F1 Effects G. Examples [Figures 1 to 4 1 H9 Invention Effects (A, Industrial Application Field) The present invention is an electronic circuit measuring device, particularly an electronic circuit that measures the characteristics of electronic circuits with high signal frequencies such as video tape recorders, video cameras, and television receivers in various operating modes. Concerning a measuring device.

(B. Summary of the Invention) The present invention provides an electronic circuit measuring device that measures the characteristics of an electronic circuit in an off-duty operation mode where the signal frequency is high. , Human power data for measurement used in the state of digital signals is converted to analog (No. 3) by a D/A converter and input to the electronic circuit under test, and the analog signal output from the electronic circuit under test is The A/D converter converts the signal into a digital signal, which is then subjected to arithmetic processing, and the mode control circuit switches the operating mode of the electronic circuit under test.
The conversion operations of the converter and the A/D converter are performed using the same reference clock pulse.

(C, Prior Art) Devices such as video tape recorders, video cameras, and television receivers contain complex electronic circuits that process very high frequency signals. It is necessary to measure whether the device has predetermined characteristics and to automatically adjust the electronic circuit according to the measurement results.

Conventionally, the inspection and adjustment of such electronic circuits involves
Measuring devices have been used that manually apply measurement signals to the electronic circuit under test, switch the operating mode of the electronic circuit under test, detect signals, etc. asynchronously, and perform signal detection using an analog method.

(D. Problem to be Solved by the Invention) By the way, according to the above-mentioned measuring device, even if the electronic circuit to be measured itself has a fast processing speed, signal detection is performed using an unlog processing method. It has been impossible to synchronize input of signals, detection of signals, and switching of operating modes at high speed. Therefore, the time required for inspection and adjustment becomes longer, which is one of the factors that restricts the speed of mass production of devices such as video tape recorders, video cameras, and television receivers.

That is, electronic circuits used in video tape recorders, video cameras, television receivers, etc. process high-frequency signals, and therefore switching their operating modes is originally a short period of IH (horizontal period) or several H. This can be done very quickly in between. Therefore, if measurements are performed using human power, signal detection, and high-speed switching of operation modes, the time required for measurement will be shortened, and the electronic circuits that flow through them on the production line will be formed. It should be possible to sequentially measure a large number of printed wiring boards at high speed. However, since conventional measuring devices are analog systems, it is not possible to quickly change the type of measurement or change the operation mode, and as a result, it takes a very long time.

Therefore, the inventor of the present application considered measuring with a digital measuring device. That is, an input signal to be applied to the electronic circuit under test for measurement is prepared in the form of a digital signal, and the signal is converted to an analog signal by a D/A converter and then applied to the signal output from the electronic circuit under test. is converted into a digital signal by an A/D converter and stored in the memory, and after all data to be measured has been captured, the data is read out from the memory and processed through arithmetic processing to evaluate the characteristics of the electronic circuit under test. , the switching of the operating mode of the electronic circuit under test is also performed digitally. However, when measuring using such a digital method, the calculation time required for the measurement is often unexpectedly long. To give a specific example, the color signal or color synchronization signal of the video signal has a very high frequency of 3.85 MHz, and it is very important to accurately understand its level and phase. . If this data is A/D-converted using a control pulse having a frequency that is, for example, four times that frequency, and then used for calculation, very complicated calculations are usually required due to the interpolation between sample data. Therefore, the time required for measurement cannot be made very short.

The present invention has been devised to solve these problems, and its 1-purpose is to enable high-speed measurement of the characteristics of E-element circuits in various operating modes. be.

(E. Means for solving the problems) In order to solve the above problems, the electronic circuit measuring device of the present invention has the following steps:
Manual measurement data prepared in the form of a digital signal is converted into an analog signal by a D/A converter and input manually to the electronic circuit under test, and the analog signal output from the electronic circuit under test is converted to an analog signal using an A/D converter. A converter converts it and then performs arithmetic processing, a mode control circuit switches the operating mode of the electronic circuit under test, and the D/A converter and A/D
This is characterized in that the conversion operations of the converters are performed using the same reference clock pulse.

(F. Effect) According to the electronic circuit measuring device of the present invention, switching the operation mode of the electronic circuit under test, applying a human power signal for measurement to the electronic circuit under test, and extracting a signal from the electronic circuit under test can be performed digitally. Therefore, the switching of the operating mode, the application of the measurement input signal, and the extraction of the signal from the electronic circuit under test can be performed in synchronization with each other, and in turn, these operations can be performed at extremely high speed.

Then, the same reference clock pulse is used for the D/A converter that converts digital human input data for measurement into analog input signals for measurement, and the A/D converter that converts the output of the electronic circuit under test into digital signals. Since the operation is performed, the D/A conversion on the input side of the electronic circuit under test and the A/D conversion on the output side of the electronic circuit under test can be completely synchronized. Therefore, even if the signal has a very high frequency, such as a color signal or a color synchronization signal, the level changes according to a certain rule, that is, the waveform has a certain shape, such as a sine wave. The peak value and amplitude of a signal can be determined using simple arithmetic operations. This is because the D/A of the signal input to the electronic circuit under test
Since the conversion and the A/D conversion of the signal detected from the electronic circuit under test are performed synchronously, the time relationship between each A/D conversion point is exactly the same as the time relationship between each D/A conversion point. be. Therefore, although there is a time delay in how the level changes at each D/A conversion point that exists in order on the time axis, the A/A
It appears in level changes at the time of conversion, and understanding the source, for example, color signal or color synchronization signal from A/D conversion data, can be done by simple calculations such as four arithmetic calculations without complicated interpolation calculations. I can do it. Therefore, calculations for measurement can be performed quickly.

Therefore, measurements can be made at very high speed.

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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The electronic circuit measuring apparatus of the present invention will be explained in detail according to the illustrated embodiments.

1 to 4 are for explaining one embodiment of the electronic circuit measuring device of the present invention, and FIG. 1 is a circuit block diagram showing the circuit configuration.

In the drawings, 1 is an electronic circuit to be measured, and circuit 1-1
．． 1-2, 1-3, -1-n, etc.

2 is a reference clock pulse generation circuit, and the electronic circuit under test 1
If it is for a video camera with the NTSC signal standard, the subcarrier frequency is 3.58M.
A reference clock pulse having a frequency of 14.8 MHz, which is four times Hz, is generated. This is because it sufficiently satisfies the sampling theorem for No. 13 in the highest frequency band of 4.2 MHz, and is convenient for grasping very important color signals and color synchronization signals (subcarriers).

If the electronic circuit to be measured is for a video camera, it has a built-in oscillator (not shown) that generates the above-mentioned subcarriers, so the output of the oscillator (not shown) is used as a reference signal as shown by the two-dot chain line. It is recommended that the reference clock pulse be generated by capturing the reference clock pulse.

Reference numeral 3 denotes an input signal generation circuit, which includes a data storage section 4 consisting of a RAM that stores human power data for measurement (for example, a video signal) in the form of a digital signal of the human power signal for measurement applied to the electronic circuit under test 1; It consists of a D/A converter 5 that converts the measurement input data read out from the D/A converter 4 into an analog signal, and an LPF (low-pass filter) 6 that interpolates the signal output from the D/A converter 5.
The output of F6 is input to the electronic circuit under test 1 as a measurement input signal. The data storage section 4 can store contents of various video signals in units of one horizontal period.

7 is a detection circuit, which is composed of circuits 8 to 14 described below. 8 is a switching circuit which receives the output signals of each circuit 1-1, 1-2 = 1-n constituting the electronic circuit under test 1, and selects one of them designated by a switching signal from the serial-parallel conversion circuit 21, which will be described later. Outputs one output signal. 9 is an amplifier that amplifies the signal output from the switching circuit 8; IO is a group of filters that pass the signal amplified by the amplifier;
Filters 10 with mutually different characteristics. ．． 102, -10n
Consisting of The filter 10, . 10□-10,,
It receives the output signals of , and outputs one output signal designated by the switching signal from the serial-parallel conversion circuit 21 . 12 is a clamp circuit that clamps the signal output from the switching circuit 11; 13 is a DC level shift circuit that shifts the DC level of the signal output from the clamp circuit 12; and 14 is a signal output from the DC level shift circuit 13. Serial to parallel conversion circuit 2
This is a gay control circuit that amplifies at an amplification degree specified by 1.

15 is an A/D converter that outputs from the detection circuit 7 and converts an analog signal into a digital signal; 16 is an A/D converter;
Memory for storing signals output from the D converter, 1
A CPU 7 analyzes the characteristics of the electronic circuit under test 1 by calculating the detection data stored in the memory 16;
Reference numeral 8 denotes an adjustment device that automatically performs various adjustments of the electronic circuit 1 to be measured based on the analysis result by the CPU 17. The adjustment by the adjustment device 18 involves controlling the adjustment parts of the electronic circuit 1 to be measured, such as controlling a motor for rotating a volume,
This includes cutting fuse elements of ICs with redundant circuits, various trimmings, and writing to electronic volume ROMs.

Reference numeral 19 denotes a mode control circuit, which operates by receiving the reference clock pulse outputted from the reference clock pulse generation circuit 2 as a control signal, and outputs a mode setting signal for specifying the operating mode of the electronic circuit under test 1 and a detection circuit for the detection circuit. Generates a mode setting signal that specifies the mode. The operating modes of the electronic circuit under test 1 include various operating modes such as LP (long play) mode, sp (short play) mode, playback mode, and recording mode.

The operation mode is switched by converting the serial mode setting signal into a parallel signal by the serial-parallel conversion circuit 2o and applying the parallel signal to the electronic circuit under test 1. Furthermore, the detection mode of the detection circuit 7 means that the switching circuit 8 selects the output signal of which circuit forming the electronic circuit under test 1, the selected output signal is passed through which filter by the switching circuit 11, and is extracted. , clamp circuit 12, DC level shift circuit 13,
Refers to the state of how the gain control circuit 14 clamps, shifts the DC level, and amplifies the detection mode of the detection circuit 7. The switching of the detection mode of the detection circuit 7 involves converting a serial mode setting signal into a parallel signal by the serial-parallel conversion circuit 21. This is done by applying the same to each part of the detection circuit 7. Further, the reference clock pulse outputted from the reference clock pulse generation circuit 2 is transmitted to the A/D converter 15.
is sent to via the mode control circuit 19. This is because if A/D conversion is performed for each clock pulse, a lot of unnecessary data will be recorded in the memory 16, making it impossible to effectively utilize the memory 16, which has a limited capacity, so only the minimum necessary interval is sampled. However, in order to avoid sampling in the remaining sections, it is necessary to appropriately thin out the reference clock pulses manually inputted to the A/D converter 15 as a control signal, and this is done by the mode control circuit 19.

The mode control circuit 19 is composed of a RAM, and transmits two types of mode setting No. 45 in chronological order according to its stored contents to set the operating mode of the electronic circuit under test and the detection mode of the detection circuit 7 in a predetermined order. Switch. Therefore, when it is necessary to change the operating mode of the electronic circuit under test 1 and the detection mode of the detection circuit 7 due to changes in the inspection contents, the model of the electronic circuit under test, etc., the RAM
It is only necessary to rewrite the memory contents of the mode control circuit 19 consisting of the following.

The electronic circuit measuring device shown in FIG. A/D conversion of the output signal of the detection circuit 7 is all 1
This is done synchronously based on the reference clock pulses generated by the two reference clock pulse generation circuits 2.

FIG. 2 is a time chart showing an example of the operation of the electric circuit measuring device, and the operation will be explained according to this diagram.

This electronic circuit measuring device has 1024 horizontal periods H (approximately 6 hours)
4m5ec) as one repetition period. The human input signals A, B, C, D, and E are video signals that are output in time series with one horizontal period as a unit, and are prepared to have the most preferable waveforms for performing different predetermined types of measurements. It is a group. For example, human input signal A is a video signal group for measuring the level of a color burst signal, human input signal B is a video signal group for measuring the color signal level, and input signal C is a video signal for measuring the luminance signal level. Each video signal group is composed of a plurality of video signals selected in IH units according to the measurement purpose, and the input signals A, B, C, D, and E are chronologically stored in the data storage unit 4. The signal is read out to the D/A converter 5, where it is converted into an analog signal, and then manually input to the electronic circuit under test 1.

The electronic circuit under test 1 receives a video signal as a human input signal from the D/A converter 5 (input signal generation circuit 3) side, and its operation mode is controlled by a mode setting signal from the mode control circuit I9. Therefore, the operating mode of the electronic circuit 1 to be measured, which is a prerequisite for measurement, can be set and switched as desired. In FIG. 2, marks 1, 2, and 2 indicate different operation modes.

The mode control circuit 19 also controls the electronic circuit under test 1.
In addition to controlling the operation mode of the detection circuit 7, the detection mode of the detection circuit 7 is also controlled. A, 口, HA, 2, and HO are each different detection modes.

In the example shown in FIG. 2, at the start of each repetition cycle, the operating mode of the electronic circuit under test 1 is switched to 1, and the detection mode of the detection circuit 7 is switched to A. In this state, a signal generated by passing the input signal A through the electronic circuit under test 1 is detected by the detection circuit 7.

In this case, it goes without saying that the way the signal is detected differs depending on the detection mode of the detection circuit 7. That is, depending on the detection mode, the circuit 1-1 constituting the electronic circuit under test 1
Which circuit's output signal from ~1-n should be extracted, which filter should the extracted signal be passed through, how should the filtered signal be clamped, and the signal whose DC bias was fixed by clamp processing? It is defined how to shift the DC level of the signal and how much to amplify it. Circuits 1-1 to 1- of the electronic circuit under test 1
Being able to select the circuit that extracts the output signal from n is because the detection point differs depending on the type of measurement, etc.
This is also because there are cases where it is necessary to use a plurality of detection points even in one type of measurement. Also, a plurality of filters 1o.

The reason why filters 102 to 10n are provided and the filter through which the detection signal 48 is passed is switched by the switching circuit 11 is to shorten the time required for filter processing.

That is, in this electronic circuit measuring device, the detection signal is converted into a digital signal and the CPU 17 performs arithmetic processing, so that filter processing can be performed by calculation without using a filter. Therefore, from that point of view, it is not necessarily necessary to provide a filter and pass No. 43 through it. However, performing filter processing by calculation takes a very long time. There are about eight types of filter processing necessary for measuring circuit boards used in video tape recorders, video cameras, and the like. Therefore, about eight filters with different characteristics are provided, and the switching circuit 11 switches the filter to be used. Clamping by clamp circuit 12 is performed to establish the DC level of the signal for later digitizing.

Since the clamp point and clamp level need to be changed depending on the type of measurement line, etc., they can be controlled. Also, the DC level is shifted by the DC level shift circuit 13, and the output of the circuit 13 is transferred to the gain control circuit! 4 is amplified by the A/D converter 15 depending on the signal to be measured.
This is to enable effective use of the human-powered dynamic range, and the stiffness can reduce relative quantization noise.

Now, when the repetition period starts, signal detection is performed with the operation mode of the electronic circuit under test 1 being 1 and the detection mode of the detection circuit 7 being 1. Next, the human input signal changes to B, and the detection mode of the detection circuit 7 is switched from A to mouth. The rising edge of the pulse indicating the change in detection mode in FIG. 2 indicates the start of switching, and the falling edge of the pulse indicates the end of switching.

Signal detection (A/D conversion) is not performed between the start and end of the switching, that is, the period during which the switching is being performed. When the switching is completed, data regarding the human input signal B is taken in, that is, A/D conversion is performed by the A/D converter 15, and the converted digital signal is stored in the memory 1.
Memory to 6 is performed.

Next, as the human input signal becomes C, the operation mode of the electronic circuit under test 1 switches from summer to H, and the detection mode of the detection circuit 7 switches from mouth to eight. Data is not captured during the switching, and data regarding the human input signal C is captured when the switching is completed. Thereafter, the input signal is switched from C to D, and the detection mode of the detection circuit 7 is switched from 8 to 2. When the switching is completed, data regarding the input signal is captured.

Next, when the 5 human power signal changes to E (the last human power signal in this example), the operation mode of the electronic circuit 1 to be measured changes from ■ to m, and the detection mode of the detection circuit 7 changes from 2 to E. Although data is not captured during the switching, measurement data regarding the human input signal E is captured after the switching is completed. In this embodiment, this is the last data capture, and when the last data capture is completed, in other words, when the mode control circuit 19 finishes capturing the last data, the mode control circuit 19 transfers the series of data. An end club indicating that the import has been completed is sent to the CPU 17. Then, the CPU 7 starts arithmetic processing of the data. The time required for this data processing is not constant and varies depending on the case. While the arithmetic processing is being performed, the input signal generation circuit 3 continues to send out human input signals, and the operation mode of the electronic circuit under test 1 and the detection mode of the detection circuit 7 are switched by the mode control circuit 19. However, data acquisition is stopped.

Then, when the CPU 17 finishes the predetermined calculation processing (including not only simple calculation but also control of the adjustment device 18 based on the calculation result), the CPU 17 sends a start flag to the mode control circuit in order to start measurement on the next electronic circuit under test 1. Send to 19. Then, data for the next measurement will be taken in from the repetition period following the repetition period when the start flag was sent out.

Figures 3 (A) to (C) roughly explain three types of measurement examples for the same input signal;
) shows the data extraction timing for the level measurement of the luminance signal, (B) the burst level measurement, and (C) the data extraction timing for the color A9) measurement.

The level of the luminance signal was detected during the period t1 while the synchronization signal was being generated, as shown in FIG. This can be done by calculating the difference between a certain luminance, for example, a level D7 detected during a period t3 during which a self-peak signal is being generated. Note that the periods tl, t2. t3 refers to a longer period than one sample period, during which several or tens of sample blinks are performed.

In addition, the color burst signal level measurement is performed at the level detected during the first two color burst signal generation periods as shown in Figure (B), and the color signal level is measured as shown in Figure (C). This is performed by appropriately calculating the level detected during the generation period t4 of the color signal to be processed. Since the object to be measured is a 3.58 MHz sine wave, the calculation in this case may not be done by subtraction as in the case of measuring the brightness level 4A, but it can be done by using four arithmetic operations, which are very simple calculations by a computer. Various measurements can be performed on color signals or color synchronization signals. This is because, as shown in Fig. 4, D/A conversion by the D/A converter 5 and A/D conversion by the A/D converter 15 are performed in synchronization, so the evaluation of detected data is performed using a comparative method. This is because it can be done with In other words, although there is naturally a certain time delay between the D/A conversion of the human input data for measurement and the A/D conversion of the output of the detection circuit 7,
Since these two conversions are performed in synchronization with the same reference clock pulse, each D/A conversion (
Solid line) Time relationship between time points and each A on the A/D conversion side
The time relationship between the /D conversion (double-dashed line) is exactly the same, and the way the level changes on the D/A conversion side appears on the A/D conversion side with the above time delay. /D
It is possible to calculate both peak values of the color signal or color synchronization signal of the video signal and the level difference between them from the data regarding the converted multiple levels by using four arithmetic calculations. No interpolation or other calculations between data are required. Therefore, measurements can be made very quickly. Of course, there is no FM jitter between each clock pulse of the reference clock pulse, and there is no problem with absolute accuracy.

In addition, according to this electronic circuit measuring device, not only can calculations for data analysis be performed at high speed in Q', but also the switching of the operation mode of the electronic circuit under test 1 and the detection mode of the detection circuit 7 can be performed using manual input signals. Since the human input to the electronic circuit under test 1 and the input of output data from the electronic circuit under test 1 can all be processed in synchronization with each other using the same reference clock pulse, the time required for processing other than calculations can also be shortened. I can do it. In this respect as well, the time required for measurement can be shortened, allowing high-speed measurement and high-speed adjustment.

According to this electronic circuit measuring device, the data storage section 4
By rewriting the memory contents of the mode control circuit 1, it is possible to respond to changes in the human power data for measurement.
By changing the contents of tα in item 9 by -7, it is possible to cope with changes in the operation mode of the electronic circuit under test 1 and the detection mode of the detection circuit 7. Therefore,
Additions and changes to measurement contents, additions and changes to measurement items, etc. can be easily realized by changing so-called software without changing so-called hardware.

(H, Effect of the Invention) As described above, the electronic circuit measuring device of the present invention has a D/A converter that converts human power data for measurement into an analog signal and sends it to the electronic circuit under test as a human power signal for measurement. ,
an A/D converter that converts the signal from the electronic circuit under test into a digital signal; a calculation means that performs calculation processing on the digital signal output from the A/D converter; and a digital mode control unit for the electronic circuit under test. and a mode control circuit that sends out a setting signal to control the operating mode of the electronic circuit under test, and the D/
This is characterized in that the A converter and the A/D converter are operated using the same reference clock pulse.

Therefore, the electronic circuit measuring device of the present invention digitally switches the operation mode of the electronic circuit under test, applies a human power signal for measurement to the electronic circuit under test, and extracts the signal from the electronic circuit under test. Mode switching, application of a human power signal for measurement, and signal extraction from the electronic circuit to be measured can be performed in synchronization with each other, and furthermore, these operations can be performed at extremely high speed.

Then, the same reference clock pulse is used for the D/A converter that converts the digital human power data for measurement into an analog human power signal for measurement, and the A/D converter that converts the output of the electronic detection circuit under test into a digital signal. Since the conversion operation is performed, the D/A at the input terminal of the electronic circuit under test is
The conversion and the A/D conversion on the output side of the electronic circuit under test can be completely synchronized. Therefore, even if the signal has a very high frequency, such as a color signal or a color synchronization signal, if the waveform has a certain shape, such as a sine wave, it can be calculated using simple four arithmetic operations.・Mode control circuit.

value and amplitude can be determined. Therefore, it is possible to perform calculation processing for measurement at high speed. Therefore,
Measurements can be made very quickly.

[Brief explanation of the drawing]

1 to 4 are for explaining one embodiment of the electronic circuit measuring device of the present invention. FIG. 1 is a circuit block diagram showing the circuit configuration of the electronic circuit measuring device, and FIG. Time charts showing operation examples; Figures 3 (A) to (C) are time charts showing data extraction timing for each measurement example; Figure 4 is time between D/A conversion and A/D conversion. FIG. Explanation of symbols 1...Electronic circuit to be measured, 5...D/A converter, 15...A/D converter, 17...Calculating means, Applicant Hide Ogawa, Patent Attorney for Sony Corporation Data extraction timing for each measurement example. Figure 3 shows the time chart.

Claims (1)

[Claims] (1) A D/A converter that converts measurement input data into an analog signal and sends it to the electronic circuit under test as a measurement input signal, and an A/D converter that converts the signal from the electronic circuit under test into a digital signal. and a calculation means for processing the digital signal output from the A/D converter, and a mode for controlling the operating mode of the electronic circuit under test by sending a digital mode setting signal to the electronic circuit under test. An electronic circuit measuring device comprising at least a control circuit, wherein the D/A converter and the A/D converter are operated using the same reference clock pulse.