JPH08178985A - Measuring apparatus for leak current - Google Patents

Abstract

PURPOSE: To easily measure current flowing out of an opening of a housing of electric device and to provide data useful for EMC control. CONSTITUTION: A personal computer 5 is used as a controller, and a probe 3 comprises an ammeter 1 for detecting leak current and a two-dimensional position detector 2 which are assembled as a single unit, wherein the two-dimensional position detector 2 uses a mouse connected to the personal computer 5. The ammeter 1 for detecting flow-out current is built into the mouse, and by operating the mouse so that its bottom is in contact with a surface of a metallic housing, both position information and a current value can be obtained, so that intensity can be indicated on a map on a computer screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge current measuring device, and more particularly to a device for easily measuring a current flowing out from an opening of a casing of an electronic device.

[0002]

2. Description of the Related Art A housing has a large number of relatively small openings for door gaps and heat radiation. Electromagnetic radiation from the housing is generated by current leaking from these openings and flowing on the outer surface of the housing. Therefore, when considering the radiation from the housing, it is very important to know from which opening the current is flowing out in order to suppress the radiation.
Conventionally, when measuring the discharge current from the opening of the metal housing, hold the current probe for detecting the discharge current by hand,
I measured the change in output by sliding along the surface of the housing. Then, the output of the constant current is recorded using an ammeter for detecting the side current.

[0003]

In the above-mentioned prior art, the current probe for detecting the shunt current is held by hand and slid on the surface of the casing to measure the change in output, and the shunt current for the shunt current is detected. Since the ammeter of 2 is used to write the output at a constant interval, it is difficult to accurately obtain the position information, and it is not efficient.
Therefore, in order to simplify the operation of writing the output of the ammeter for detecting the sideward current at regular intervals, some measures have been taken, such as attaching graph paper to the surface of the case to make it easier to obtain position information. It wasn't very efficient.

A system for mounting on a non-metal two-dimensional stage and measuring at regular intervals is conceivable. However, assembling a device that can accurately move a stage in a wide movable range with a non-metal material such as resin is of great strength. It is very difficult in terms of size, and the device becomes large. Therefore, there is a drawback in that it is impossible to measure a device such as a large-scale device that does not fit on the stage. It is an object of the present invention to provide a system capable of easily measuring the discharge current without being affected by the size of the measurement object.

[0005]

SUMMARY OF THE INVENTION The present invention provides a probe in which an ammeter for detecting a source current and a two-dimensional position detecting device are integrated, a detector for detecting a source current, a detection output and position information. Is provided with a controller for displaying or saving
A source current measuring device characterized in that the controller displays or stores the position information and the detection output of the ammeter when the probe is swept over the surface of the metal casing. Further, the present invention provides a probe in which an ammeter for detecting the source current is incorporated, a detector for detecting the source current, a two-dimensional position detecting device for detecting the position of the probe, a detection output and position information. A source current measuring device comprising a controller for displaying or storing, and displaying or storing the position information and the detection output of an ammeter when the probe is swept on the surface of a metal housing by the controller.

Further, according to the present invention, a two-dimensional position detecting device is
It is a configuration in which the laser range finder is placed on a rotary table with an encoder, and the rotary table is driven by a controller.
The two-dimensional coordinates are obtained from the rotation angle indicated by the encoder when the laser beam is emitted while rotating the laser distance measuring device and the reflected light from the probe is received, and the distance measured value. It is a side current measuring device. Further, the present invention is a configuration in which the two-dimensional position detecting device is installed on the rotary table driven by the controller at two places apart from each other by a constant distance, and is required during the rotation. Further, the above-mentioned source current measuring device is characterized in that the position of the probe is detected from the distance between the respective probes and the distance between the laser distance measuring devices.

[0007]

In order to solve the above problems, the present invention provides
A means for solving the above is provided, and the means for solving the problem will be specifically described and its operation will be described. The source current measuring device of the present invention is a probe in which a two-dimensional position detecting device and a source ammeter are housed in a non-metallic case of a handy size, a preprocessing device for preprocessing probe output, and position information and probe output. It consists of a processing controller. While holding this probe by hand as if sliding it on the surface of the non-measurement object's housing, the probe detects position information at each position and the source current. The output of the probe is position information on the two-dimensional plane and the value of the current flowing out at that position.
The controller sets the two-dimensional position information and the current value at that time to 1
Store as data. In addition, the result can be output on the screen.

The source current detected by the probe is often an AC waveform containing various frequency components. Therefore, pre-processing is performed by the wave detector before being taken into the controller. For example, if the AC waveform is simply smoothed, the total amount of all frequencies is detected. Use a filter to detect only leakage current at a specific frequency. Moreover, each frequency component is separated and output using a spectrum analyzer.

Further, the probe of the present invention incorporates only the ammeter for detecting the discharge current, and the two-dimensional position recognizing device uses the laser distance measuring device placed on the origin of the measurement plane.
The laser range finder emits a laser beam to obtain the distance from the reflection component from the target object. Next, there are two inventions for detecting a two-dimensional position using this. In one of the inventions, one laser range finder is placed on a rotary encoder and placed at the origin of the measurement plane, and a two-dimensional position is calculated from the distance d from the probe to the probe and the angle θ indicated by the rotary encoder at that time. dcos θ, dsin
θ) (FIG. 3).

According to another aspect of the invention, two encoders are installed at a distance L1 and distances L2 and L3 from each point to the probe are obtained, and L1, L2 and L3 are respectively obtained.
This is to calculate the positions of the vertices of a triangle whose three sides are 3 (FIG. 4). In this device, two points are calculated at positions where a straight line connecting the two laser distance measuring devices is a line of symmetry, but in actuality, only one side of them is effective. In either case, a driver driven by the controller is required to cause the laser range finder to rotate left and right.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. [Embodiment 1] FIG. 1 is a block diagram of a source current measuring apparatus according to a first embodiment of the present invention. As shown in Figure 1,
A personal computer (5) is used as a controller. The probe (3) is a combination of an ammeter (1) for detecting an outflow current and a two-dimensional position detecting device (2). The two-dimensional position detecting device (2) which is a position recognizing device is
Using a mouse connected to a personal computer (5). An ammeter (1) for detecting a small side current is embedded in the mouse, and the detection surface is the bottom surface of the mouse so that the output sensitivity can be obtained when the bottom surface of the mouse is swept so as to contact the surface of the metal case. It is installed according to.

The output of the side-current detecting ammeter (1) is connected to a spectrum analyzer (4), which is a detector here. The detection mode of the spectrum analyzer (4) is the personal computer (5)
Is performed through a communication cable from the device to instruct the detection of the current value of a specific frequency, the selection of the frequency sweep mode, and the transfer of the current value. The personal computer (5) reads the current value as a digital value and handles it as one data together with the position output of the mouse at that location. Actually, the mouse recognizes the change in the relative position, and therefore the position from which the measurement start point is taken as the origin is recognized. The origin is recognized when the clip button of the mouse is pressed. In this way, by embedding a side-current detection ammeter in the mouse and operating the mouse, both position information and current value can be obtained, and intensity can be illustrated on the map of the PC screen. It is a thing.

There are two points to be noted when recognizing the position using the mouse. First, since the mouse recognizes the relative position, tilting and sweeping the mouse may cause an error from the actual position. Therefore, it is necessary to always sweep the mouse in a certain direction. When sweeping, it is better to sweep to a ruler. Another point to note is that if the sweep speed is too fast, there is a time lag between the sampling of position information and the sampling of its current value,
The value may deviate significantly. It is necessary to properly set the sampling time from the processing speeds of the personal computer (5) and the spectrum analyzer (4) to realize the sweep speed that minimizes the error.

The personal computer (5) has a function of displaying numerical data and storing continuous data,
A function to save only the data when the mouse is clipped, a function to draw a contour map at the point where the mouse is traced by painting the output values as color-coded points on the screen as a two-dimensional plane, and data input After that, there is a function to analyze all data and draw a contour map of all areas.
Also, the function of drawing the output when tracing on a certain straight line is easily realized by software.

[Embodiment 2] FIG. 2 is a block diagram of a source current measuring apparatus according to a second embodiment of the present invention. As shown in FIG. 2, a probe having a built-in source current detection ammeter (1), a detector (spectrum analyzer) for detecting source current, and a two-dimensional position detection for detecting the position of the probe. It is provided with a device (2) and a controller (personal computer) (5) for displaying or storing the detection output and position information. The rotary table (6) and the laser distance measuring device (7) are applied to the two-dimensional position detecting device (2).

That is, the same as the first embodiment in that the personal computer (5) is used as the controller and the output of the current source ammeter (1) is received by the spectrum analyzer (4). The difference is that the mouse of the personal computer (5) is not used as the position recognition device. In the second embodiment, the laser range finder (7) is applied. FIG. 3 is a diagram illustrating the configuration and operation of two-dimensional position detection according to the present invention. As shown in FIG.
The current meter for detecting the side current (1) is connected to the detector (spectrum analyzer) (4), and the two-dimensional position detecting device including the rotary table (6) and the laser distance measuring device (7) is the controller ( 5) is connected. One laser range finder (7) with rotary base (6) with encoder
2D position from the distance d to the probe and the angle θ indicated by the encoder at that time (dcos
θ, dsin θ).

FIG. 4 is a diagram showing the construction and operation of another two-dimensional position detecting device according to the present invention. As shown in FIG. 4, the ammeter (1) for detecting the outflow current is connected to the wave detector (spectrum analyzer) (4), and the rotary table (6) and the laser range finder (7) are provided. These are connected to the controller (5).
In this way, if two laser range finding devices (7) can be used, two encoders are installed at a distance L1 and the distances L2 and L3 from each point to the probe are obtained, and L1, L2 and L3 are calculated. It can be calculated as the positions of the vertices of a triangle having three sides.

In the second embodiment, there is no restriction on the orientation of the probe (3) and the two-dimensional position can be obtained with high accuracy. However, when the laser range finder (7) is used, there are obstacles in between. It is recommended to use it in a place that does not exist. When the protrusion is protruding from the housing, it is necessary to devise such as transmitting and receiving the laser light at a position higher than the protrusion or using it at a position avoiding the protrusion.

[0019]

By using the source current measuring device of the present invention, it is possible to identify the location of the source side of the casing current that causes the radiation from the electronic equipment, and particularly the simple measurement can be performed on site. EMI for shielding
It becomes easy to take EMC countermeasures such as mounting a gasket for countermeasures, a metal tape, a magnetic sheet for shielding. The mouse method is particularly simple and suitable for searching. The laser distance measuring method is effective in accurately mapping the leak state.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a source current measuring device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a source current measuring device according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating the configuration and operation of two-dimensional position detection according to the present invention.

FIG. 4 is a diagram illustrating the configuration and operation of one two-dimensional position detection device according to the present invention.

[Explanation of symbols]

 1 Ammeter for side current detection 2 Two-dimensional position detector 3 Probe 4 Wave detector (spectrum analyzer) 5 Controller (personal computer) 6 Rotating table 7 Laser range finder

Claims (4)

[Claims] 1. A probe provided with an ammeter for detecting the source current and a two-dimensional position detecting device, a detector for detecting the source current, and a controller for displaying or storing the detection output and position information. A source current measuring device characterized in that the controller displays or stores the position information and the detection output of the ammeter when the probe is swept on the surface of the metal casing. 2. A probe having a built-in ammeter for detecting the source current, a detector for detecting the source current, a two-dimensional position detector for detecting the position of the probe, and a detection output and position information. Alternatively, the source current measuring device is provided with a controller for storing, and the controller displays or stores the position information and the detection output of the ammeter when the probe is swept on the surface of the metal casing. 3. The two-dimensional position detecting device has a structure in which a laser range finder is mounted on a rotary table with an encoder, and the rotary table is driven by a controller to emit laser light while rotating the laser range finder. The two-dimensional coordinates are obtained from the rotation angle indicated by the encoder at the time of emission and the reflected light from the probe and the measured distance.
Side-current measuring device described in. 4. The two-dimensional position detecting device has a configuration in which two laser range finding devices are installed on a turntable driven by a controller at locations separated by a certain distance, and is obtained during rotation. The source current measuring device according to claim 2, wherein the position of the probe is detected from the distance between the respective probes and the distance between the laser distance measuring devices.