JPS61250532A - Automatic phase control method in stress image system - Google Patents

Abstract

PURPOSE:To attain to easily control a phase with high accuracy, by performing a large number of final scannings on the basis of a max. stress imparting phase calculated by performing a reduced number of preparatory scannings and the phase only in the circumference thereof to find out a max. stress value imparting phase. CONSTITUTION:An order is applied to an A/D converter 5 from a preparatory and final scanning setting means 18 and a reduced number of preparatory scannings are performed to calculate the preparatory phase corresponding to a max. stress value. This phase information is sent to the preparatory and final scanning setting means 18 and the final scanning of an image spot is performed only on the basis of a set phase and the phase in the circumference thereof. That is, the same measuring area is scanned many times on the basis of each phase. A stress value is obtained from the integrated temp. data obtained at every phase by a detector 17 and once stored in a memory 6c and the stored stress values are succeedingly called out from the memory 6c to a phase control means 9 successively or simultaneously to perform the comparison of magnitude and the phase imparting a max. stress value is discriminated and set to a scanner 3 or a phase data generation means 12. Therefore, phase control can be easily performed with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) In measuring stress distribution information of a test object using thermoelastic effect, the present invention provides an image of the test object loaded with a load signal using an infrared detector. An automatic stress imaging system that adjusts the phase (timing) of temperature data detection with respect to a load signal in a stress imaging system that performs horizontal and vertical scanning with a spot and displays an image of stress distribution based on the obtained temperature data. This invention relates to a phase adjustment method.

(Prior Art) Many systems have been proposed for displaying stress distribution on a display device based on temperature distribution data obtained by scanning a subject with an image spot of an infrared detector.

An example of this conventional stress imaging system will be briefly explained.

FIG. 2 is a diagram for explaining the outline of a stress imaging system used to explain the conventional automatic phase adjustment method and the present invention. 1 is an object to be examined, and a load is applied to the object 1 by a load shaker 2. When this load signal is applied, a temperature distribution is generated on the surface of the object 1 due to the thermoelastic effect in a distribution corresponding to the stress distribution. 3 is an infrared scanner that scans the object 1 with an image spot, and this horizontal and vertical scanning reads the analog temperature data of the object 1, which is suitably amplified by the next stage signal processing system 4 and then converted to the primary A/ The D converter 5 converts the data into digital temperature data and supplies it to the computer 6 at the next stage. 7 is the timing circuit.

In addition to taking the load supply and timing of the load shaker 2, the A/D
A timing pulse is also supplied to the converter 5 and the computer 6 to determine the timing at which digital temperature data is taken into the computer 6.

This system is configured to convert the thus captured temperature data into stress distribution data through computer processing, and display the data as a stress image on the display device 8.

By the way, since the temperature change caused by the thermoelastic effect of the test object is generally small, the S/N ratio is extremely small in stress measurement using such a low-level signal.

This cannot be put to practical use in displaying stress distribution images.

(Problem to be Solved by the Invention) By the way, in conventional stress imaging systems using thermoelastic effects, there is a slight difference between the load signal applied to the object and the stress signal generated in the object due to this load signal. However, there is a phase shift. Therefore, it is necessary to match the timing of detecting the temperature data of the object to the phase of the stress signal.

However, the stress signal due to the thermoelastic effect is a very small signal and has a low frequency of about 1 to 5G)12, so it is extremely difficult to perform this phase alignment manually. there were.

Attempts have also been made to automatically perform this phase matching, but in order to obtain the required accuracy, it is necessary to scan the same measurement location multiple times and integrate the obtained temperature data to improve the S/N ratio. It is necessary. However, if the temperature data is integrated by scanning the same number of times for all phases,
It takes a long time to capture this temperature data, which is not practical.

An object of the present invention is to provide an automatic phase adjustment method in a stress imaging system that automatically performs such phase adjustment in a short time.

(Means for Solving the Problems) In order to achieve this objective, according to the present invention, an image spot obtained by horizontally and vertically scanning an object to which a load is applied periodically with an image spot of an infrared detector. In an automatic phase adjustment method in a stress imaging system, which adjusts the phase of temperature data detection with respect to a load signal of this periodic load in order to display stress distribution as an image based on temperature data.

For each set different phase, a preliminary stress value is determined by integrating temperature data at the same measurement point, and a preliminary phase corresponding to a maximum preliminary stress value among these preliminary stress values is determined.

A step of calculating stress values by integrating more temperature data than when calculating the preliminary stress value for each of the surrounding phases including this preliminary phase, and adjusting the phase to a phase that gives the maximum stress value among these stress values. It is characterized by having the following.

Furthermore, in implementing the present invention, the cycle of the load signal is detected in order to set different phases.

It is preferable to set phase data that can be set to different delay times based on this detected cycle, and to determine the timing of temperature data detection based on this phase data.

Detection is performed by forming compression and tension signals, each having a phase determined by phase data with respect to the load signal and having the same period as this load signal, and performing a logical operation on these compression and tension signals and a horizontal scanning timing signal. It is preferable to form a horizontal effective timing signal and to detect temperature data for each horizontal effective timing signal for each set different phase.

Further, in a preferred embodiment of the present invention, the phase data can be set manually or automatically to set the phase that provides the maximum stress value among the stress values.

(Function) As described above, according to the automatic phase adjustment method of the present invention, the image spot is first scanned a plurality of times for the same measurement point at each of the different phases between 0 @ and 180 @, and the image spot is scanned multiple times at each phase. Calculate the integrated temperature data, calculate the pre-stress at each phase from these integrated temperature data, select the maximum pre-stress among these pre-stress values, and first find the pre-phase corresponding to this maximum pre-stress. Only for the peripheral phases including this preliminary phase, the same measurement point is scanned more times than the number of scans when calculating the preliminary stress, and the integrated temperature data for each phase is obtained, and from these integrated temperature data, each phase is The phase of temperature data detection is adjusted to the phase that gives the maximum stress value among these stress values.

Conventionally, scanning was performed about 258 times for each phase, but
According to this invention, the corresponding number of scans is approximately 64 times for determining the preliminary phase for each phase and approximately 258 times for determining the maximum stress phase, so the total scanning time is reduced to 1/2. This is significantly shorter than before.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, the present invention will be described with reference to an apparatus shown in FIG. 1 for implementing the automatic phase adjustment method for a stress imaging system of the present invention.

First, a load signal is supplied from the load shaker 2 to the periodic signal detection means 11, one period of the load signal is determined, a periodic signal (time delay signal) having this information is generated, and the compression and tension signal forming means 13 supply to. In this compression and tension signal forming means 13, a phase of, for example, 45° is set with respect to the load signal as an initial phase, and compression and tension signals having the same period as that of the load signal are respectively formed.

Next, these compression and tension signals and the horizontal scanning timing signal from the scanner 3 are supplied to the logic operation circuit 15, where, for example, they are synchronized to form a horizontal valid timing signal, which is sent to the scanner 3. The subject l is scanned with an image spot based on this horizontal effective timing signal, temperature data is input into the computer 6, and this temperature data is converted into a video signal by the temperature data-stress distribution data conversion means 8a and displayed on the display device 8. Displays one screen of stress images.

Next, the cross point X of the horizontal and vertical cursors h and V is set to the portion R where the stress value is high. Subsequently, the vertical scanning by the scanner 3 is advanced to the vertical position of the cursor, the vertical scanning is stopped, and horizontal (line) scanning is performed at this position.

At this time, since the phase is initially set to 45°, the signal processing circuit 4 receives temperature data obtained by scanning several points near the cursor cross point X, for example, 84 times with this phase relationship.
and sent to the computer 6 via the A/D converter 5, and its detection means! In step 7, temperature data is integrated to obtain compressive and tensile stresses, and the difference between the compressive and tensile stresses is calculated to obtain stress values. Thereafter, the average value of the stress values for these several points is determined, and this average stress value is stored in the memory 6C of the computer 6.

By the way, in this invention, the preliminary scanning and main scanning setting means 1
A command is given to the A/D converter 5 from 8 to perform a preliminary scan to find a preliminary phase corresponding to the maximum preliminary stress value. For this reason, the initially set phase is changed and the same measurement point is scanned, for example, 64 times for each phase. From the temperature data obtained from these scans, the average stress value is determined as the preliminary stress value in the same manner as described above. This is stored in the memory 6c.

After storing the preliminary stress values obtained by sequentially changing the phase in this way in the memory QC, these values are stored in the phase adjusting means 1.
8, the maximum prestress value among these prestress values is determined, a phase corresponding to this maximum prestress value is set, and this phase information is sent to the prescan/main scan setting means 1.
8, and main scanning of the image spot is performed using only this set phase and its surrounding position 14.

This main scan covers, for example, 258 of the same measurement points in each phase.
The stress values are obtained from the integrated temperature data obtained for each phase in the detector 17 in the same manner as described above, these stress values are temporarily stored in the memory 8c, and then the phase adjustment is performed using these stress values from the memory 8c. The means 18 is sequentially or simultaneously called to compare the magnitudes sequentially or simultaneously, the phase giving the maximum stress value is determined, and the phase is set in the scanner 3 or the phase data generating means 12. Alternatively, while determining whether or not the maximum stress value is reached by the phase adjustment means 18, the scanner 3
Alternatively, the phase of the phase data generating means 12 is adjusted, and when the maximum stress value is determined, the phase at that time is fixed.

As described above, according to the present invention, a preliminary scan with a small number of scans is performed for N phases from 00 to 180 degrees to predict the phase that will give the maximum stress, and then how many points in the vicinity that include this predicted phase are calculated. By sequentially performing main scans with a large number of scans for each phase, the phase that provides the maximum stress value can be found with high precision and in a short time, and adjustment can be made to that phase.

Therefore, even if there is a phase shift between the load signal and the stress signal, the temperature data can always be imported into the computer in an optimal state, and the stress can be displayed in the optimal measurement state.

FIG. 4 is a block diagram showing a part of the apparatus from generation of one-cycle value signal to obtaining horizontal effective scanning timing signal for carrying out the automatic phase adjustment method of the present invention, and FIG. 5 is a signal waveform for explaining the process. It is a diagram.

First, the load signal is made into a sine wave signal as shown in FIG. 5(A). This load signal is supplied to a comparator 53 via an amplifier 51, which generates an output signal of a constant level when the amplitude of the load signal is equal to or higher than the zero level.

This signal is shown in FIG. 5(B).

The output signal from the comparator 53 is supplied to rising and falling differentiating circuits 55 and 57, respectively, to obtain differentiated signals as shown in FIGS. 5(C) and 5(D). These rising differential signals and falling differential signals are used as compression start pulses and tension start pulses, respectively, as will be described later.

Next, the rising differential signal is a periodic signal generating means! Supply to 4. In this embodiment, this means is comprised of two mono-multivibrators 58 and 81 for time delay, a period counter B3, and a latch circuit 85.

On the other hand, 87 is a clock pulse generator that generates clock pulses at any suitable frequency; - period counter B3;
clock input. A differential signal from a rising differential circuit 55 is supplied to the signal input of the counter 83 via two monovibrators 58 and B1. Therefore, clock counting is started by this first differential signal and stopped by the next differential signal. This count value is stored in the latch circuit 85, and on the other hand, the output from the mono multivibrator 58 is sent as a latch pulse to this latch circuit B5.
supply to. The latch circuit B5 outputs this count value as one-cycle data Ts representing one-cycle time to the input/output capotro 8.
through the central processing unit 71 of the computer 6 (hereinafter referred to as C
(referred to as PU).

In the CPU 71, the phase data generating means 12 calculates the phase data Tθ from this one-cycle data Ts, and supplies this to the compression and tension signal forming means 13. The phase here corresponds to the phase difference between the cycle of the load signal and the cycle of measuring temperature data. This phase data Tθ represents a time delay with respect to the load signal. For this phase data, the number of divisions in one cycle is determined in advance as Ns, and the number of divisions Ns can be arbitrarily set to N (0≦N
≦Ns) and calculate from Tθ=TsXN/Ns. The value of N can be set by inputting it from the CPU 71, and can also be set according to the stress value, as will be described later.

This phase data To is supplied to the compression counter 75 and tension counter 77 of the compression and tension signal forming means 13 via the input/output coupler door 3. In this case, compression and tension counters 75 and 77 are supplied with compression start pulses and tension start pulses from differentiating circuits 55 and 57, respectively, and are loaded with respective phase data using these start pulses.

These counters 75 and 77 can be countdown counters or countup counters, but the case where they are countdown counters will be explained. In this case, it is assumed that the supplied phase data Tθ corresponds to a phase of 45°, and the compression counter 75 counts accordingly.
, and the clock from the clock pulse generator 87 is subtracted and counted (FIG. 5 CF)). When this count value becomes zero or less than zero, an under-hollow signal is generated from this counter 75. 2 lip flop C or less,
(referred to as FF) 79, and this FF? θ is set to form a compressed signal (FIG. 5(H)).

Similarly, the phase data To is loaded into the tension counter 77 by the tension start pulse from the falling differentiation circuit 57, and the clock is subtracted. When the count value is complete or less than zero, an under-hollow signal is not generated. Figure 5 (G))
, this signal resets the FF 79 and inverts the compression signal described above to form a tension signal.

In this way, based on the periodic signal, it is possible to form compression and tension signals, respectively, which have an arbitrary phase with respect to the load signal and have the same period as the load signal.

Next, in order to form a horizontal effective timing signal from these compression and tension signals and a horizontal scanning timing signal, F
Compression and tension signals are supplied from F79 to the logic operation circuit 15. On the other hand, this logic operation circuit 15 is supplied with a horizontal scanning timing signal HBL (Fig. 5 (■)) from the scanner 3, and for example, takes the logical product of both signals to obtain a horizontal effective timing signal (Fig. 5 (■)) for the compression period. (shown as a solid line in (J)) and the horizontal effective timing signal (effective HBL) for the tension period (
(shown by dotted lines in FIG. 5(J)) are formed respectively.

The horizontal effective timing signal (effective HBL) thus obtained is sent to the scanner 3, and the temperature data of the subject I is measured at such horizontal scanning timing (FIG. 1).

Next, by manually or automatically changing the value of N described above, the phase data Tθ can be sequentially changed within the range of 0° to 180′, thereby changing the phase of temperature data detection.

This invention is not limited only to the embodiments described above. For example, each of the means 11, 13, 15, and 18 described above may have a configuration other than the configuration described here, and these may have a configuration other than the configuration described here. It can be easily configured using electronic technology. Further, the phase data generating means 12. The detecting means 17 may be made to function in the cPU of the computer 6, or separate CPUs may be provided, each or a part of which is common, and the logic operation circuit 15 may be made to function in these CPUs. Separate means may be provided to set the preliminary scan and the main scan.

The above-mentioned logical operation circuit 15, detection means 17, phase adjustment means 18, phase data generation means 12, preliminary scanning/main scanning setting means 1B, and other components are made of conventionally commonly used electronic elements and/or electronic elements. It can be easily formed or functioned by using or combining circuits.

Furthermore, the present invention is suitable for application to point-scan or area-scan type stress imaging systems.

(Effects of the Invention) As is clear from the above description, according to the automatic phase adjustment method of the present invention, there is a slight difference between the load signal applied to the object and the stress signal generated in the object due to this load signal. However, even if there is a phase shift, the phase is automatically shifted and a small number of preliminary scans are performed at each different phase to calculate each preliminary stress value (preferably the average stress value).
is determined, and among these preliminary stress values, the maximum preliminary stress value is scanned many times with the phase only around the given area to find the phase that gives the maximum stress value, and the phase is adjusted to that phase.

Therefore, according to the present invention, phase adjustment can be performed more simply, easily, and more accurately in a shorter time than in the past.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an apparatus for explaining the automatic phase adjustment method in the stress imaging system of the present invention, and FIG. 2 is a block diagram showing a conventional stress imaging system. FIG. 3 is a diagram for explaining the present invention. FIG. 4 is a block diagram of the main parts used to explain the invention. FIG. 5 is a signal waveform diagram for explaining the present invention. i -... Subject, 2... Load shaker 3...
Scanner, 4...Signal processing system 5...A/
D converter, 6... Computer 8a... Control signal generation means 8b... Temperature data - stress distribution data conversion means 8C.
...Memory 7...Timing circuit, 8...Display device 9...
Control circuit, 11... Periodic signal detection means 12.
...Phase data generation means, 13...Compression and tension signal formation means 15...Logic operation circuit, 1? --Detection means 1
8...Preliminary scanning and main scanning setting means 19...Phase adjustment means, 51...Amplifier 53.
...Comparator, 55...Rise differentiation circuit 5
7...Falling differentiation circuit 59.81-...Mono multivibrator 83...-
Cycle counter, 85...Latch circuit 87--Clock generator, II9.73.83...Input port door 1...Central processing unit (CPU) 75...Compression counter, 77...Tension counter 78
···flip flop.

Claims (4)

[Claims] (1) In order to display the stress distribution as an image based on the temperature data obtained by horizontally and vertically scanning the subject to which a load is applied periodically with the image spot of the infrared detector, the load of the periodic load is In an automatic phase adjustment method in a stress imaging system that adjusts the phase of temperature data detection with respect to a signal, preliminary scanning is performed multiple times for each set different phase and temperature data at the same measurement point is integrated to calculate the preliminary stress. and determining a preliminary phase corresponding to the maximum preliminary stress value among these preliminary stress values, and performing main scanning a greater number of times than the number of preliminary scans for each of the surrounding phases including the preliminary phase. 1. A method for automatic phase adjustment in a stress imaging system, comprising the steps of: accumulating temperature data to obtain a stress value; and adjusting the phase to give a maximum stress value among these stress values. (2) In the automatic phase adjustment method in a stress imaging system according to claim 1, in order to set the different phases, detect the period of the load signal, and set the different phases based on the detected period. An automatic phase adjustment method, characterized in that phase data that can be set as a delay time is set, and the timing of detecting temperature data is determined based on the phase data. (3) In the automatic phase adjustment method in a stress imaging system according to claim 1, the temperature data detection has a phase determined by the phase data with respect to the load signal and has the same period as the load signal. forming compression and tension signals, respectively, and performing a logical operation on these compression and tension signals and the horizontal scanning timing signal to form a horizontal effective timing signal, and for each horizontal effective timing signal for each set different phase. An automatic phase adjustment method in a stress imaging system, characterized in that the automatic phase adjustment method is carried out by detecting the temperature data. (4) In the automatic phase adjustment method in a stress imaging system according to claim 2, the phase data is set manually or automatically so as to set the phase that gives the maximum stress value among the stress values. An automatic phase adjustment method in a stress imaging system, characterized by: