JP2016197029A - Electrostatic discharge source detecting method, and electrostatic discharge source visualizing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the area where an electrostatic discharge source is present to be accurately identified even including a range of sampling errors.SOLUTION: By an electrostatic discharge source detecting method by which electromagnetic waves generated in connection with electrostatic discharge are detected by a group of reception antennas consisting of multiple reception antennas installed in different locations and three-dimensional coordinates of an electrostatic discharge source are figured out by a hyperbolic curve method from the relation between the time differences of arrivals of the electromagnetic waves at the reception antennas and the installed positions of the reception antennas, a first hyperbola obtained by addition of the values of sampling time intervals and a second hyperbola obtained by subtraction of the values of sampling time intervals relative to a hyperbola for identifying electrostatic discharge source are figured out, and an area formed by crossing of the first hyperbola, the crossing of the second hyperbola, and the crossing of the combination of the first hyperbola and the second hyperbola is identified as an inferred electrostatic discharge source area, which is an area where an accurate electrostatic discharge source including sampling error areas is present.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrostatic discharge source detection method for detecting the electrostatic discharge source including an error range by sampling, by calculating the position of the electrostatic discharge source by the hyperbola method when electrostatic discharge occurs in the object to be measured, and Further, the present invention relates to a method for visualizing an electrostatic discharge generation source for displaying and visualizing the position.

  As an example of a conventional electrostatic discharge occurrence location visualization method and visualization device, Patent Document 1 describes means for easily visualizing a situation in which electrostatic discharge occurs in an object to be measured on a video image.

  The method described in Patent Document 1 describes that “four or more antennas for receiving electromagnetic waves accompanying electrostatic discharge, a video camera for shooting a state of the object to be measured with a moving image, and a shooting range of the video camera. A support with an azimuth / elevation angle reference plate for inspection is installed in the vicinity of the object to be measured, and the hyperbolic method is used to determine the difference between the time when electromagnetic waves generated by the electrostatic discharge generated at the object to be measured reach each antenna. Calculate the position where electrostatic discharge has occurred in the measurement object, and display the marking on the video image of the measurement object to indicate the position of the electrostatic discharge source, the remaining time until electrostatic discharge occurs, and the electrostatic discharge source. The state of electrostatic discharge occurring in the object to be measured is visualized with a video image by superimposing a display indicating the position of the numerical value and the like.

  According to this method, the position where the electrostatic discharge occurred in the measured object is calculated by the hyperbolic method from the difference in the time that the electromagnetic wave generated by the electrostatic discharge generated in the measured object reaches each receiving antenna. Therefore, it is possible to calculate the coordinates of occurrence of electrostatic discharge in the measurement object very accurately.

  In addition, on the video image of the object to be measured, a marking display indicating the position of the electrostatic discharge source, a display of the remaining time until the electrostatic discharge occurs, and a display indicating the position of the electrostatic discharge source numerically, etc. By superimposing and displaying, it is possible to easily confirm in a video image how electrostatic discharge occurs in the object to be measured.

Japanese Patent No. 5374687

  The method described in Patent Document 1 is based on the premise that, in a measurement device used to detect electromagnetic waves generated due to electrostatic discharge, the electromagnetic wave arrival time difference between antennas can be accurately calculated according to theory. In practical measuring instruments, the sampling rate is finite, so an error occurs when calculating the arrival time difference of electromagnetic waves between antennas, and an error also occurs in the discharge position calculated by the hyperbola method. End up.

  However, Patent Document 1 does not mention any calculation error due to the limitation of the sampling rate, nor a method for dealing with the calculation error.

  As described above, when detecting the electrostatic discharge source, the voltage waveform of the electromagnetic wave emitted from the electrostatic discharge source is detected. At this time, since the detection is performed at a predetermined sampling speed, sampling is performed. An error range due to. Therefore, it is practically very effective if an electrostatic discharge source can be specified including the error range due to sampling according to the sampling performance of the measuring instrument.

  The present invention has been made in consideration of such circumstances, and according to the sampling performance of the measuring instrument used for detecting the electrostatic discharge generation source, an accurate electrostatic discharge generation source including an error range due to sampling can be obtained. It is an object of the present invention to provide an electrostatic discharge source detection method and an electrostatic discharge source visualization method capable of specifying an electrostatic discharge source estimation region that is an existing region.

  In order to solve the above problems, the electrostatic discharge generation source detection method of the present invention detects an electromagnetic wave generated due to electrostatic discharge with a reception antenna group including a plurality of reception antennas installed at different locations, and each reception antenna. In the electrostatic discharge source detection method that calculates the three-dimensional coordinates of the electrostatic discharge source by the hyperbola method from the relationship between the time difference in which the electromagnetic wave reaches the antenna and the installation position of the receiving antenna, The first hyperbola obtained by adding the sampling time interval values and the second hyperbola obtained by subtracting the sampling time interval values are obtained, and the intersection of the first hyperbola and the second hyperbola are obtained. The area formed by the intersection of the first hyperbola and the intersection of the first hyperbola and the second hyperbola, including the error range by sampling, is accurate. And identifies as electrostatic discharge source estimation region is a region where the electrostatic discharge source exists.

When calculating the position of the electrostatic discharge source using the hyperbola method, the true electrostatic discharge source is calculated according to the sampling performance of the measuring instrument by calculating the calculation error area of the electrostatic discharge source caused by the sampling time interval. It is possible to specify the area where the exists.
Here, the electrostatic discharge generation source specifying hyperbola is a hyperbola used for specifying an electrostatic discharge generation source in a two-dimensional space or a three-dimensional space.

  The electrostatic discharge generation source visualization method of the present invention is an electrostatic discharge generation source visualization method for visualizing an electrostatic discharge generation source estimation region obtained by the electrostatic discharge generation source detection method of the present invention, and is configured by the receiving antenna group. Using a video imaging device calibrated in a three-dimensional space, the state of the test object is continuously photographed and recorded, and when the receiving antenna group detects an electromagnetic wave generated due to electrostatic discharge, the receiving antenna group is configured. The electrostatic discharge generation source estimation area is marked and displayed on a plan view showing a three-dimensional space or an image captured by the video imaging device, and the electrostatic discharge generation source estimation area is displayed. To do.

Visualize the region where the true discharge source exists by displaying the position of the intersection that specifies the error region as an XY, XZ, and YZ plan view in a three-dimensional space composed of receiving antenna groups It becomes possible to do.
Further, in which region of the device under test the discharge has occurred can be confirmed on the image immediately after the discharge has occurred.
Here, the video photographing device calibrated in the three-dimensional space composed of the receiving antenna group includes the angle of view to be photographed, the angle corresponding to each pixel in the photographed image, and the receiving antenna group. It means a video photographing device in which the installation coordinates and photographing angle of the photographing reference point of the video camera in a three-dimensional space are clarified in advance.

  In the electrostatic discharge generation source visualization method of the present invention, an image captured by the video imaging device is continuously recorded in an infinite loop for an arbitrary time, and when the receiving antenna group detects electrostatic discharge, the image is captured at the moment of detection. Assign a reference number when an electrostatic discharge occurs to a still image, save the image recorded in an infinite loop as a group of images before and after the occurrence of electrostatic discharge, and add markings indicating the estimated area of the electrostatic discharge generation to each stored still image After that, still images can be displayed in time series, and the state of the object to be measured before and after the occurrence of electrostatic discharge can be displayed and confirmed.

  As a result, the region where electrostatic discharge occurs in the device under test and the moment when the electrostatic discharge occurs can be known, so that it is possible to easily confirm the situation where electrostatic discharge occurs in the device under test.

  According to the present invention, according to the sampling performance of the measuring instrument used when detecting the electrostatic discharge source, the electrostatic discharge source estimation region, which is the region where the accurate electrostatic discharge source exists including the error range due to sampling, is determined. Can be identified.

It is a figure which shows the structure of the apparatus which implement | achieves the electrostatic discharge generation source detection method and electrostatic discharge generation source visualization method which concern on 1st embodiment of this invention. It is a figure which shows the azimuth | direction and an elevation angle in a three-dimensional space. It is a figure which shows the voltage waveform and electromagnetic wave arrival reference | standard point of the electromagnetic waves from an electrostatic discharge generation source. It is explanatory drawing of the method of specifying the electrostatic discharge generation source by the hyperbola method. It is explanatory drawing which applied the specification of the position of the electrostatic discharge generation source to the three-dimensional space. It is a figure which shows the error of the arrival time difference by sampling. It is a figure explaining the method of specifying the electrostatic discharge generation source estimation area | region which is an area | region where the accurate electrostatic discharge generation source exists including the error range by sampling. It is a figure which shows the calculation example and display example of an error range. It is a figure which shows an example of the display of the electrostatic discharge generation source estimation area | region by the difference in a sampling rate. It is a figure which shows an example of the display of the electrostatic discharge generation source estimation area | region in the case of a different arrival time difference.

The electrostatic discharge generation source detection method and electrostatic discharge generation source visualization method of the present invention will be described below based on the embodiments.
FIG. 1 shows a configuration of an apparatus for realizing an electrostatic discharge generation source detection method and an electrostatic discharge generation source visualization method according to the first embodiment of the present invention.

  As shown in FIG. 1, receiving antennas 2a, 2b, 2c, and 2d are arranged at arbitrary locations near an object to be measured a for which an electrostatic discharge source b is desired to be specified. A support 1 to which a plate 5 is attached is installed.

  The receiving antennas 2a, 2b, 2c, and 2d are respectively connected to the input terminals ch1, ch2, ch3, and ch4 of the digital oscilloscope 6 through coaxial cables 3a, 3b, 3c, and 3d, respectively. Yes. The digital oscilloscope 6 is connected to a control computer 9 by a digital interface cable 9 a, and the control computer 9 controls the digital oscilloscope 6.

  The video camera 4 is connected to the control computer 9 by the digital interface cable 9 b and is controlled by the control computer 9.

  In the support 1, the position where the receiving antenna 2a is attached is set as a measurement reference point c of the visualization device, and the receiving antennas 2b, 2c, and 2d are attached to arbitrary places whose directions are different by 90 degrees with respect to the receiving antenna 2a. In the case of FIG. 1, with respect to the measurement reference point c, the axis passing through the receiving antenna 2b is taken as the Y axis, the axis passing through the receiving antenna 2c is taken as the X axis, and the axis passing through the receiving antenna 2d is taken as the Z axis. Note that there is no particular limitation on which receiving antenna the XYZ axes are oriented to.

  That is, in the case shown in FIG. 1, the receiving antenna 2a is a reference point receiving antenna, and a receiving antenna group is formed by this reference point receiving antenna and three or more receiving antennas other than the reference point receiving antenna. Yes. The reference point receiving antenna and the other two receiving antennas form one plane, and the other receiving antennas are arranged at positions not on this plane.

  In FIG. 1, signals received by receiving antennas 2a, 2b, 2c, and 2d are transmitted through coaxial cables 3a, 3b, 3c, and 3d, which are high-frequency transmission paths, to a 4-channel input digital oscilloscope 6. Are respectively input to the input channels ch1, ch2, ch3, and ch4.

  The electric signal arrival time difference from each receiving antenna 2a, 2b, 2c, 2d to the digital oscilloscope 6 is examined in advance, and when the electromagnetic wave arrival time difference is calculated, the electric signal transmission time difference is corrected to zero. To do.

  The digital oscilloscope 6 is connected to a control computer 9 by a digital interface cable 9a, and the control computer 9 initializes the digital oscilloscope 6 and sets measurement conditions. The communication interface method for connecting the control computer 9 and the digital oscilloscope 6 is the control of the digital oscilloscope 6 such as GP-IB, RS-232C, LAN, USB, etc. Any method can be used as long as it can exchange data. On the screen of the control computer 9, an electrostatic discharge source estimation area R is displayed. The process leading to this display will be described in detail later.

FIG. 2 shows the azimuth and elevation angle in a three-dimensional space.
As shown in FIG. 2, in a three-dimensional space, the direction from the measurement reference point c on the XY plane where the measurement reference point c exists is an orientation, and the degree of inclination in the vertical direction with respect to the XY plane where the measurement reference point c exists Is the elevation angle. In the case of the present embodiment, the direction of the + Y axis is set to 0 degree, and the direction increases as it rotates clockwise to the + X axis side (right side), and the elevation angle is directed to the XY plane where the measurement reference point c exists. The elevation angle is 0 degree, the elevation angle is +90 degrees in the direction of the + Z axis, and the elevation angle is -90 degrees in the direction of the -Z axis.

  When electromagnetic waves generated by electrostatic discharge are received by any of the receiving antennas 2a, 2b, 2c, and 2d, the digital oscilloscope 6 is triggered and the occurrence of electrostatic discharge is monitored. The trigger function of the digital oscilloscope 6 includes an edge trigger that triggers when there is an input exceeding a certain potential, and a pulse width trigger that triggers when the pulse width of the input signal is within a certain period of time. In addition, there are pattern triggers obtained by combining them with a plurality of input channels, and what kind of trigger conditions are to be adjusted is selected according to the situation at the measurement site.

  When the digital oscilloscope 6 is triggered by receiving an electromagnetic wave generated along with electrostatic discharge, the voltage change of the electromagnetic wave generated along with electrostatic discharge received by the receiving antennas 2a, 2b, 2c and 2d It is recorded as digital data of channels ch1, ch2, ch3 and ch4 of the digital oscilloscope 6.

  The digital data recorded in the digital oscilloscope 6 is a digital oscilloscope 6 in which the time change of the voltage input to each channel is discretely converted into a high-speed AD (from an analog value to a digital value). ) A data group in which voltage values obtained by conversion are recorded in time series by the number of set points.

  When the trigger of the digital oscilloscope 6 is applied, this is detected by the control computer 9 and recorded as the occurrence time of electrostatic discharge. Then, the digital data for four channels recorded by the digital oscilloscope 6 is read by the control computer 9, and the electromagnetic wave arrival reference point in each channel is found.

FIG. 3 shows an image of a voltage waveform and an electromagnetic wave arrival reference point in which an electromagnetic wave generated due to electrostatic discharge is detected by a digital oscilloscope 6 connected to receiving antennas 2a, 2b, 2c, and 2d.
The electromagnetic wave arrival reference point is a reference point for comparing the time when the electromagnetic wave generated due to electrostatic discharge reaches each receiving antenna 2a, 2b, 2c, 2d. In the waveform data of the electromagnetic wave accompanying electrostatic discharge recorded in the digital oscilloscope 6, the measurement point indicating the peak of the first voltage pulse generated by the electromagnetic wave generated by electrostatic discharge is set to reach the electromagnetic wave. Reference points P (2a), P (2b), P (2c), and P (2d) are used.

  The measurement point indicates the number of the digital data recorded in time series in the digital oscilloscope 6.

  When the peak portion of the voltage pulse exceeds the display range of the digital oscilloscope 6, an intermediate measurement point in the exceeding section is set as an electromagnetic wave arrival reference point. An example is P (2c) in FIG.

  When the difference between the measurement points indicating the electromagnetic wave arrival reference point is multiplied by a reciprocal of the sampling rate of the digital oscilloscope 6 at the time of measurement between any two receiving antennas, between the two receiving antennas The arrival time differences t (ba), t (ca), and t (da) of electromagnetic waves generated with electrostatic discharge are calculated.

  The sampling rate is the number of times of measurement per second when discrete changes in voltage or the like are measured in the digital oscilloscope 6.

  The sampling time interval is the reciprocal of the sampling rate, and means the time interval when the digital oscilloscope 6 discretely measures temporal changes such as voltage.

  The hyperbolic method is a method of receiving electromagnetic waves generated by electrostatic discharge with three or more receiving antennas at different installation locations, and different combinations due to the relationship between the time difference at which the electromagnetic waves arrive at each receiving antenna and the installation position of the receiving antennas. This is a technique of calculating the hyperbola between any two receiving antennas and determining the position of the electrostatic discharge source by obtaining the intersection of the hyperbola.

  When calculating the coordinates of the discharge source in the two-dimensional space using the hyperbolic method, when using three or more receiving antennas, and calculating the coordinates of the discharge source in the three-dimensional space using the hyperbolic method, in addition to the three receiving antennas It is necessary to install at least one receiving antenna at a position different from the plane formed by these antenna groups.

Based on FIG. 4, a method for specifying an electrostatic discharge generation source by the hyperbola method will be described.
As shown in FIG. 4A, when the electrostatic discharge generation source b and the receiving antennas 2a, 2b, 2c are all in the same two-dimensional space, the electromagnetic waves accompanying the electrostatic discharge generated by the electrostatic discharge generation source b are generated. When the receiving antennas 2a, 2b and 2c receive, as shown in FIG. 4B, the receiving antenna 2a and the receiving antennas are received according to the difference in the distance between the electrostatic discharge generation source b and the receiving antennas 2a and 2b. An arrival time difference t (ba) with the antenna 2b is generated. Similarly, an arrival time difference t (ca) between the receiving antenna 2a and the receiving antenna 2c is generated according to a difference in distance between the electrostatic discharge generation source b and the installation location of the receiving antennas 2a and 2c.

  A line connecting points at which the arrival time difference is t (ba) with respect to the receiving antennas 2a and 2b is a hyperbola L (ba) with respect to the antennas 2a and 2b. It is not possible to specify which point of the discharge is the source of the discharge. Therefore, another receiving antenna 2c is prepared, and by receiving electromagnetic waves with the antennas 2a, 2b, and 2c, the hyperbola L (ba) and the hyperbola L (ca) are obtained, and the intersection of the two hyperbola is determined by electrostatic discharge. It can be specified as the position of the generation source b.

  FIG. 4C illustrates a situation in which the received waveform cannot be accurately detected due to the slow sampling rate. Sampling points are indicated by white circles in the figure. Since the voltage waveform received by each receiving antenna is discretely detected by sampling, the true time difference to is different from the actually detected time difference t obtained by sampling.

FIG. 5 shows an example in which the above-described specification of the position of the electrostatic discharge generation source b is applied to a three-dimensional space. As shown in FIG. 5A, when the electrostatic discharge source b exists in a three-dimensional space, a receiving antenna 2d is further added on the Z axis, and a hyperbola L (da) obtained by the receiving antennas 2a and 2d. Ask for. As shown in FIG. 5B, a curved surface obtained by rotating the hyperbola L (da) by 360 degrees about the Z axis is calculated. Similarly, as shown in FIG. 5C, a curved surface obtained by rotating a hyperbola L (ba) by the receiving antenna 2a and the receiving antenna 2b by 360 degrees about the Y axis is calculated, and the receiving antenna 2a and the receiving antenna 2c are calculated. A curved surface obtained by rotating the hyperbola L (ca) by 360 degrees about the X axis is calculated.
In addition, since the curved surface obtained by rotating each of the hyperbola L (ba), the hyperbola L (ca), and the hyperbola L (da) is formed by the hyperbola group of each hyperbola, here, Such hyperbola groups are also collectively referred to as hyperbola.

  FIG. 5 (d) shows an XY cross-section for the intersection of the hyperbola obtained by the above method, and by obtaining the points where these three curved surfaces intersect each other, the receiving antennas 2a, 2b, 2c, The coordinates of the electrostatic discharge generation source b in the three-dimensional space with reference to the arrangement of 2d can be calculated.

The number of receiving antennas attached to the support 1 is further increased from four, and it is attached to a place different from the existing receiving antennas 2a, 2b, 2c and 2d, and the number of hyperbolic curves to be calculated is increased, thereby reducing measurement errors. In addition, the calculation accuracy of the electrostatic discharge generation source can be improved.

FIG. 6 shows the arrival time difference error due to sampling.
When calculating the arrival time difference of electromagnetic waves between two receiving antennas used in the hyperbolic method, it is necessary to accurately calculate the detection time difference of the peak of the first voltage pulse of the received waveform data of the two receiving antennas to be compared. However, in practice, the true pulse peak cannot often be detected due to the sampling rate of the measuring instrument used to detect electromagnetic waves. In this case, either the sampling point immediately before or after the pulse peak, the sampling point having a value closer to the peak value is the peak point on sampling.

  A circle in FIG. 6 indicates a sampling point, and a black circle is a peak point detected as a peak value of a voltage pulse. Therefore, the time interval between the two black circles is the detected arrival time difference. In this case, the time difference between the true pulse peak and the pulse peak on sampling is within half the value of the sampling time interval.

  FIG. 6A shows a case where the positions of the true received waveform pulse peaks in the two channels are both outside the peak point on sampling. In this case, the electromagnetic wave arrival time difference detected by sampling is measured to be shorter than the true electromagnetic wave arrival time difference. For this reason, the true electromagnetic wave arrival time difference is longer than the sampling electromagnetic wave arrival time difference by the longest sampling time interval.

  Therefore, in this case, a true peak value exists within the time interval tmax obtained by adding half the sampling time interval before and after the arrival time difference t detected by sampling. become. Therefore, when the value of the sampling time interval is added to the arrival time difference detected by sampling, a true peak always exists within the time interval.

  Conversely, FIG. 6B shows a case where the positions of the true received waveform pulse peaks in the two channels are both inside the peak point on sampling. In this case, the electromagnetic wave arrival time difference detected by sampling is measured longer than the true electromagnetic wave arrival time difference. Therefore, the true electromagnetic wave arrival time difference is the shortest and shorter than the sampling electromagnetic wave arrival time difference by the sampling time interval.

  Therefore, in this case, the true peak value exists within the time interval tmin obtained by subtracting the half of the sampling interval before and after the arrival time difference t detected by sampling. Become. Therefore, when the value of the sampling time interval is subtracted from the arrival time difference detected by sampling, a true peak always exists within the time interval.

  From the above, the true arrival time difference can be obtained by using a measuring instrument having a finite sampling speed. From “the electromagnetic wave arrival time difference on sampling−sampling time interval”, “the electromagnetic wave arrival time difference on sampling + sampling time interval” ”Is always present. Based on this, the present invention accurately detects the electrostatic discharge generation source using the hyperbola corresponding to the arrival time difference by the hyperbola method, and the method will be described below.

Based on FIG. 7, a method for specifying an electrostatic discharge generation source estimation area, which is an area where an accurate electrostatic discharge generation source exists, including an error range due to sampling will be described.
FIG. 7A shows a true electrostatic discharge source bo, and the true electrostatic discharge source bo is theoretically obtained as the intersection of the hyperbola Lo (ba) and the hyperbola Lo (ca). .

  FIG. 7B shows an electrostatic discharge generation source b actually detected at a predetermined sampling rate, and hyperbolic curves L (ba) and L (ca) for specifying the electrostatic discharge generation source. The generation source b is obtained as an intersection of the hyperbola L (ba) and the hyperbola L (ca).

FIG. 7 (c) shows a first hyperbola obtained by adding the sampling time interval to the electrostatic discharge generation source specifying hyperbola L (ba) and L (ca), and the electrostatic discharge generation source specifying A second hyperbola obtained by subtracting the value of the sampling time interval from the hyperbola L (ba) and L (ca) is shown.
The first hyperbola L (ba + 1) and the second hyperbola L (ba-1) obtained by the time difference between the reception antenna 2a and the reception antenna 2b, and the first hyperbola L (ba-1) obtained by the time difference between the reception antenna 2a and the reception antenna 2c. The hyperbola L (ca + 1) and the second hyperbola L (ca-1) are obtained.

  FIG. 7 (d) shows four intersections Q obtained by the intersection of the four hyperbola described above, one intersection by the first hyperbola, one intersection by the second hyperbola, Two intersections of the hyperbola and the second hyperbola are formed. Thereby, the area | region R formed by the crossing by a 1st hyperbola, the crossing by a 2nd hyperbola, and the crossing by the combination of a 1st hyperbola and a 2nd hyperbola is obtained on a plane. This region R always includes a true electrostatic discharge generation source bo, and this region R is an area where an accurate electrostatic discharge generation source exists including an error range due to sampling. As specified.

  When the three-dimensional detection is performed by adding the receiving antenna 2d to the above description, there is one intersection by the first hyperbola, one intersection by the second hyperbola, the first hyperbola and the second hyperbola Six intersections are formed by combination with the hyperbola. As a result, a region R formed by the intersection by the first hyperbola, the intersection by the second hyperbola, and the intersection by the combination of the first hyperbola and the second hyperbola is obtained in the three-dimensional space. This region R always includes a true electrostatic discharge generation source bo, and this region R is an area where an accurate electrostatic discharge generation source exists including an error range due to sampling. As specified.

A specific example for a three-dimensional space is shown below.
Use four receiving antennas. The installation coordinates of the receiving antenna are as follows: antenna 1 (X: 0 cm, Y: 0 cm, Z: 0 cm), antenna 2 (X: 0 cm, Y: 100 cm, Z: 0 cm), antenna 3 (X: 100 cm, Y : 0 cm, Z: 0 cm), and the antenna 4 is (X: 0 cm, Y: 0 cm, Z: 100 cm).

  The difference in arrival time of electromagnetic waves on sampling is that the difference in arrival time of electromagnetic waves between antenna 1 and antenna 2 is 2 ns (the time when the electromagnetic wave reaches antenna 2 is 2 ns earlier than antenna 1), and the difference in arrival time of electromagnetic waves between antenna 1 and antenna 3 is 2 ns ( The time when the electromagnetic wave reaches the antenna 3 from the antenna 1 is 2 ns earlier), and the time difference between the electromagnetic wave arrival of the antenna 1 and the antenna 4 is -0.5 ns (the time when the electromagnetic wave reaches the antenna 4 from the antenna 1 is 0.5 ns later). To do.

When the sampling rate of the measuring instrument to be used is 10 GS / s (sampling time interval is 0.1 ns), in order to specify the region where the true discharge source is estimated to exist, the sampling between the receiving antennas described above is performed. Three-dimensional coordinates are calculated by the hyperbola method from the combination of the eight electromagnetic wave arrival time differences obtained by adding or subtracting the value of the sampling time interval to the upper electromagnetic wave arrival time difference. The calculation results are shown in Table 1.
Note that GS / s (giga sampling / sec) indicates the sampling speed of the measuring device, and 1 GS / s means that 10 9 times of sampling is performed per second. ns (nanosec) is a unit of time, and 1 ns means 0.000000001 seconds.

  According to the above method, in the three-dimensional space, it can be specified as an electrostatic discharge generation source estimation area that is an area where an accurate electrostatic discharge generation source exists including an error range due to sampling.

FIG. 8 shows a calculation example and display example of the error range.
FIG. 8 shows an intersection formed by a hyperbola intersection obtained by taking into account sampling errors based on the arrival time differences received by the four receiving antennas, and an area formed by the intersection of these hyperbola. The discharge source estimation area is displayed.

FIG. 8A is a top view (XY plane), and FIG. 8B is a side view (XZ plane). Point A, point B, point C, point D, point E, point F, point G, point H in the figure are intersected by the first hyperbola, intersected by the second hyperbola, It is an intersection obtained by intersection with a combination of two hyperbolas. Further, as shown in FIG. 8C, when marking an image taken with a video camera calibrated in a three-dimensional space composed of reception antenna groups, an image area formed by six intersections is included. The image is displayed and recognized as an image including two intersections.
Here, the photographing reference point of the video camera is X: 0 cm, Y: 0 cm, Z: 0 cm
The shooting angle of the camera is assumed to be shooting under the conditions of pitching angle (= direction): +45 degrees, rolling angle (= elevation angle): 0 degrees, and yawing angle: 0 degrees (parallel to the XY horizontal plane).

  FIG. 9 is a diagram in which an electrostatic discharge generation source estimation region when the sampling rate is 20 GS / s, 10 GS / s, and 5 GS / s under the same conditions as those shown in FIG. 8 is marked on the image. As can be seen from FIG. 9, the slower the sampling rate, the wider the electrostatic discharge source estimation area. In this way, according to the sampling performance of the measuring instrument used when detecting the electrostatic discharge source, specify the electrostatic discharge source estimation area, which is the area where the accurate electrostatic discharge source exists, including the sampling error range. This is a major feature of the present invention.

  The shape of the electrostatic discharge generation source estimation region varies depending on the arrangement of the receiving antenna and the position of the discharge source. FIG. 10 shows the same conditions as described above, the sampling rate is 10 GS / s, the electromagnetic wave arrival time difference on sampling is 0.6 ns, and the difference between antenna 1 and antenna 2 is 0.6 ns. This is an example of marking on an image when 2.6 ns and the difference between the antenna 1 and the antenna 4 is −1.5 ns. In this case, the discharge generation source on sampling is azimuth: + 19.8 ° and elevation angle: -15, 0 °.

  In this apparatus, as shown in FIG. 1, a video image is taken of the state in which the electrostatic discharge is generated in the measured object a by the video camera 4 in parallel with the monitoring of the occurrence of the electrostatic discharge by the receiving antenna group. To do.

  The video image captured by the video camera 4 includes an area of the object a to be measured that exists in a range of a certain azimuth and elevation angle with the imaging reference point d that is the center of the focus of the imaging device of the video camera 4 as a base point. Each pixel on the video image shows the part of the object to be measured a that exists in a certain azimuth and elevation angle within that area.

  Therefore, the azimuth and elevation angle of the electrostatic discharge source b with respect to the imaging reference point d is calculated, and in the video image captured by the video camera 4, the marking is displayed on the pixel portion where the azimuth and elevation angle correspond to the static electricity source b. The location of the discharge source b is visualized on the video image.

For the video camera 4 used for shooting, the shooting angle of view of the camera used for shooting, the position of the shooting reference point, and the angles (azimuth and elevation) corresponding to the individual pixels in the shot image are examined in advance, and the results are obtained. Record as a captured image angle database. In addition, the installation coordinates and shooting angles (pitching / yawing / rolling) of the shooting reference point (focus position with respect to the shooting angle of view) of the video camera in a three-dimensional space composed of receiving antenna groups are also made clear in advance.
In terms of camera shooting angle, pitching means the azimuth angle in a three-dimensional space composed of receiving antenna groups, and rolling means the elevation angle in a three-dimensional space composed of receiving antenna groups, and yawing. Means a rotation angle with respect to the XY plane of a three-dimensional space constituted by the receiving antenna group. In FIG. 2, pitching, rolling, and yawing are illustrated.

  When marking the position of the discharge source obtained by the hyperbola method on the photographed image, the coordinates of the discharge source calculated are those of the photographed image under the camera installation conditions clarified by the method described above. Calculate whether the pixel is positioned and mark the location.

  When the receiving antenna group and the video camera 4 are integrated with the support 1, it is necessary to calibrate (clarify) the positional relationship and shooting angle between the video camera and the receiving antenna group when moving to various places for monitoring. However, for example, when the video camera and the receiving antenna group are fixed to the wall of the room to operate the entire room at all times, the video camera and the receiving antenna group If the positional relationship and the shooting angle are calibrated (obviously), the integrated jig need not be used.

When shooting an infinite loop using the video camera 4, an internal or external image recording medium is used. As shooting conditions, the shooting speed (fps), the number of recordings before the occurrence of a trigger, the number of recordings after the occurrence of a trigger, the start number of the file name to be assigned, and the like are set.
When infinite loop imaging is started and the discharge detection trigger signal of the measuring instrument is detected, the infinite loop imaging is terminated after imaging for a preset number of recordings after the occurrence of the trigger.

  After that, the received waveform data is read from the digital oscilloscope 6, and the electrostatic discharge generation source estimated area is marked and displayed on the image at the moment when the electrostatic discharge is generated from the images taken by the video imaging device. Visualize the electrostatic discharge source by displaying the discharge source estimation area.

  When an image taken with a video camera continues to be recorded in an infinite loop for an arbitrary amount of time, and the receiving antenna group detects an electrostatic discharge phenomenon, a reference number at the time of the occurrence of electrostatic discharge is assigned to the still image taken at the moment of detection. The images recorded in an infinite loop are stored as a group of images before and after the occurrence of electrostatic discharge, and after adding a marking display indicating the electrostatic discharge source estimation area to each stored still image, the still images are displayed in time series, By displaying and confirming the state of the object under measurement before and after the occurrence of electrostatic discharge in the device under test, it is possible to visualize the state of the occurrence of electrostatic discharge in the device under test.

Note that the following method can be used as a method of matching the timing when the discharge is detected by the digital oscilloscope 6 and the timing of the image at the moment when the electrostatic discharge is generated by the video camera 4.
The first method continues to monitor the digital oscilloscope 6 for a flag indicating discharge detection while performing infinite loop shooting of the video camera 4 using the internal memory of the control computer 9 that controls the digital oscilloscope 6. In this method, when the digital oscilloscope 6 detects that the flag indicating discharge detection has been set, the management number of the image recorded at that moment is recorded.

  The second method is to connect the trigger output terminal of the digital oscilloscope 6 and the trigger input terminal of the video camera 4, perform infinite loop shooting using the internal memory of the video camera 4, and detect the discharge with the digital oscilloscope 6. This is a method of transmitting the trigger signal at the time through the trigger input terminal of the video camera 4.

When a trigger signal or flag for notifying the detection of discharge is detected, the infinite loop shooting is ended after shooting for the number of recorded sheets after the occurrence of the trigger.
When an infinite loop recording is performed in the internal memory of the control computer 9, or when an image is recorded in the internal memory of the image video camera 4 at the time of occurrence of discharge, a specified number of images before and after the trigger is generated are transferred to the control computer 9. .

The second embodiment of the present invention based on the second method will be described in more detail.
In the second embodiment of the present invention, instead of the video camera 4 used in the first embodiment, a video camera having an input terminal triggered by a TTL signal and capable of digitally recording a captured image in an internal memory in an infinite loop. This method is used.

  The trigger output terminal of the digital oscilloscope 6 and the trigger input terminal of the video camera 4 are connected, and when the digital oscilloscope 6 is triggered by electrostatic discharge detection, the video camera is triggered. The video camera is set in an infinite loop shooting state in advance, and after the trigger is applied, a predetermined number of images are recorded, and then the shooting is terminated. When shooting is completed, all still images recorded in an infinite loop are read into the control computer 9 and recorded on a digital recording medium. In some cases, only a part of the image may be stored.

In any of the above-described embodiments, all still image files are given serial numbers in the order of shooting, and file names are given so that it can be seen that the images were shot at the moment when the trigger occurred.
For example, “shooting mode: infinite loop, image recording format: JPG, shooting speed: 30 fps, number of recorded sheets: 2 seconds before trigger generation (60 sheets), 1 second after trigger generation (30 sheets), start file number: f000 If the file name is given in sequential order in the shooting order, the file name “f060” is the image when the trigger is generated.

  A frame indicating the electrostatic discharge generation source is marked and saved on all the read still images. The color used for the marking display is not particularly limited, but for the still image when the trigger is generated, a color different from the color of the marking display other than when the trigger is generated is used so that the image can be identified.

  In accordance with the sampling performance of the measuring instrument used when detecting the electrostatic discharge source, the present invention specifies the electrostatic discharge source estimation region, which is an accurate region including the error range due to sampling. It can be widely used as an electrostatic discharge source detection method and an electrostatic discharge source visualization method that can be performed.

DESCRIPTION OF SYMBOLS 1 Support body 2a, 2b, 2c, 2d Receiving antenna 3a, 3b, 3c, 3d Coaxial cable 4 Video camera 5 Azimuth / elevation angle reference plate 6 Digital oscilloscope 9 Control computer 9a, 9b Digital interface cable a Object to be measured b Electrostatic discharge source c Measurement reference point d Imaging reference point P Electromagnetic wave arrival reference point t Arrival time difference L Hyperbola Q Intersection R Electrostatic discharge source estimation area

Claims (3)

  The electromagnetic waves generated by electrostatic discharge are detected by a group of receiving antennas consisting of multiple receiving antennas installed at different locations. From the relationship between the time difference at which the electromagnetic waves arrive at each receiving antenna and the installation position of the receiving antenna, the hyperbolic method is used. In the electrostatic discharge source detection method for calculating the three-dimensional coordinates of the electrostatic discharge source, the first hyperbola obtained by adding the sampling time interval value to all the electrostatic discharge source identification hyperbola, and sampling The second hyperbola obtained by subtracting the value of the time interval is obtained, and by the intersection by the first hyperbola, the intersection by the second hyperbola, and the intersection by the combination of the first hyperbola and the second hyperbola The formed area is defined as an electrostatic discharge source estimation area, which is an area where an accurate electrostatic discharge source exists including an error range due to sampling. ESD source detection method characterized by identifying Te.   An electrostatic discharge generation source visualization method for visualizing an electrostatic discharge generation source estimation region obtained by the electrostatic discharge generation source detection method according to claim 1, wherein the video shooting is calibrated in a three-dimensional space composed of the receiving antenna group. Using a device, the state of the device under test is continuously photographed and recorded, and when the receiving antenna group detects an electromagnetic wave generated due to electrostatic discharge, a plan view showing a three-dimensional space composed of the receiving antenna group, An electrostatic discharge generation source visualization method, wherein the electrostatic discharge generation source estimation region is marked and displayed on an image captured by the video imaging device, and the electrostatic discharge generation source estimation region is displayed.   An image taken with the video imaging device continues to be recorded in an infinite loop for an arbitrary amount of time, and when the receiving antenna group detects electrostatic discharge, a reference number at the time of occurrence of electrostatic discharge is assigned to the still image taken at the moment of detection. Then, save the images recorded in an infinite loop as a group of images before and after the occurrence of electrostatic discharge, add markings indicating the estimated area of electrostatic discharge generation to each stored still image, and then display the still images in chronological order. 3. The method for visualizing an electrostatic discharge generation source according to claim 2, wherein the state of the object to be measured before and after the occurrence of electrostatic discharge in the test object is displayed and confirmed.

Images