JP5871670B2 - Charged body detection device and charged body detection method - Google Patents

Description

  The present invention detects a charged object (charged body), and displays a charged body detection apparatus and a charged body in a state where a detected charged body can be recognized in a screen on which a moving image including the charged body is displayed. The present invention relates to a body detection method.

  As an apparatus related to this type of charged body detection apparatus, a visualization apparatus for visualizing an electrostatic discharge occurrence location disclosed in Patent Document 1 below is known. This visualization device includes four or more antennas arranged at different positions in a three-dimensional space to receive electromagnetic waves accompanying electrostatic discharge, a video camera for capturing a moving image of the state of the object to be measured, , A support with an azimuth / elevation angle reference plate for examining the shooting range of a video camera, and electromagnetic waves generated by electrostatic discharge are received via an antenna and digital data indicating the voltage change of the electromagnetic waves is recorded. A digital oscilloscope that uses the hyperbolic method based on this digital data to identify the location of the source of electromagnetic waves and a process that displays on the monitor device a marking that indicates the source of electromagnetic waves along with a moving image taken with a video camera And a control computer for executing.

  In this visualization device, the position of the electrostatic discharge source can be marked and displayed at the corresponding position on the moving image taken with the video camera, so the situation where electrostatic discharge occurs in the measured object can be easily visualized on the moving image. It is possible to do.

JP 2010-236918 A (page 5-11, FIG. 1)

  However, the above visualization apparatus has the following problems to be solved. That is, in this visualization device, there is a problem that an object (charged body) charged with static electricity cannot be detected until a discharge occurs because the antenna captures radio waves due to electrostatic discharge. Moreover, since it is necessary to arrange | position several antennas in the position spatially separated, the subject that size reduction of an apparatus is difficult also exists.

  The present invention has been made to solve such a problem, and provides a charged body detection device and a charged body detection method capable of detecting a charged body regardless of the occurrence of discharge and miniaturizing the apparatus. The main purpose.

  In order to achieve the above object, a charged body detection device according to claim 1, wherein a detection electrode capacitively coupled to a specific object via a stray capacitance and a flow between the specific object and the detection electrode via the stray capacitance are provided. A current measurement unit that measures a current value of the current, a camera that captures a moving image of an area including the specific object and outputs still image data constituting the moving image, and a measurement that measures a distance to the specific object. When the movement of the specific object is detected based on the distance unit and the still image data, the number of pixels of the image constituting the specific object in the still image data, the measured distance, and the camera and the An area calculation process for calculating an effective area between the specific object and the detection electrode based on a direction connecting the specific object, and a division obtained by dividing the calculated effective area by the measured distance. A voltage calculation process for calculating the amount of change per unit time of the value and dividing the current value by the amount of change to equivalently calculate the voltage value of the specific object, and the voltage value calculated in advance And a processing unit that executes a determination process for comparing the threshold voltage value to determine whether the specific object is a charged body.

  The charged body detection device according to claim 2, wherein the processing unit displays a moving image of the region on a display unit based on the still image data, and the charged body detection device according to claim 1. Is displayed on the display unit with a display indicating that it is the charged body.

  According to a third aspect of the present invention, there is provided a charged body detection method that forms a moving image while capturing a moving image of a region including the specific object with a camera in a state where the specific object and the detection electrode are capacitively coupled via a stray capacitance. When the movement of the specific object is detected based on still image data, the number of pixels of the image constituting the specific object in the still image data, the distance to the specific object, and the camera and the specific object are connected. An area calculation process for calculating an effective area between the specific object and the detection electrode based on a direction, and a change amount per unit time of a division value obtained by dividing the calculated effective area by the measured distance And a voltage calculation process for equivalently calculating the voltage value of the specific object by dividing the current value by the amount of change, and the calculated voltage value and a predetermined threshold voltage. The specific object by comparing a value to execute determination processing for determining whether or not charged.

  The charged body detection apparatus according to claim 1 and the charged body detection method according to claim 3, wherein a moving image of a region including the specific object is captured by the camera in a state where the specific object and the detection electrode are capacitively coupled via the stray capacitance. When the movement of the specific object is detected based on the still image data constituting this video while shooting, the number of pixels of the image constituting the specific object in the still image data, the distance to the specific object, and the camera and the specific object An area calculation process that calculates the effective area between the specific object and the detection electrode based on the direction connecting the two, and calculates the amount of change per unit time of the division value obtained by dividing this effective area by the measured distance In addition, a voltage calculation process for equivalently calculating the voltage value of the specific object by dividing the current value by the amount of change, and comparing the calculated voltage value with a predetermined threshold voltage value, the specific object It executes a determination process for determining whether a charged body.

  Therefore, according to the charged body detection device and the charged body detection method, it is not necessary to use an antenna that causes an increase in the size of the device, so that the device can be reduced in size and charged regardless of whether discharge has occurred. The body can be detected.

  In addition, according to the charged body detection device of the second aspect, the image of the specific object as the charged body is displayed on the display unit with a display indicating that it is a charged body. Thus, it can be clearly distinguished from an object that moves in an uncharged state.

1 is a perspective view of a charged body detection device 1. FIG. 1 is a configuration diagram showing a configuration of a charged body detection device 1. FIG. 3 is a flowchart for explaining an operation of the charged body detection device 1 and a charged body detection method. 4 is a moving image diagram of a region including objects 11a, 11b, and 11c displayed on the screen 10a of the output unit 10. FIG.

  Hereinafter, embodiments of a charged body detection device and a charged body detection method will be described with reference to the accompanying drawings.

  First, the configuration of the charged body detection device 1 will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, the charged body detection device 1 includes a case 2, a detection electrode 3, a pair of cameras 4 and 5, a current measurement unit 6, a distance measurement unit 7, a processing unit 8, a storage unit 9, and an output unit. 10 and a plurality of (in this example, three as an example) objects 11a, 11b, and 11c (hereinafter also referred to as “object 11” unless otherwise specified) positioned on the front side of the case 2. And a function of detecting the moving object 11 as a specific object. In this example, as an example, a person existing in a room where the charged body detection device 1 is installed is used as an object 11 to detect a person who moves in the room in a charged state (horizontal movement). I will explain.

  As shown in FIG. 1, the case 2 is configured by a rectangular parallelepiped (box) having a hollow inside as an example. The detection electrode 3 is formed of, for example, one conductive flat plate as shown in FIG. 2, and is exposed to the outside on the front surface 2a of the case 2 (surface facing the object 11) as shown in FIG. 1 as an example. It is arranged. With this configuration, the detection electrode 3 includes the objects 11a, 11b, and 11c located on the front surface 2a side of the case 2 and the stray capacitances C1, C2, and C3 (also referred to as “stray capacitance C” unless otherwise distinguished). Via capacitive coupling individually.

  Each of the cameras 4 and 5 includes a camera including an image sensor such as a CCD (Charge Coupled Device) such as a video camera or a CMOS (Complementary Metal Oxide Semiconductor). Further, as shown in FIG. 1 as an example, each of the cameras 4 and 5 has a predetermined distance from the front 2a of the case 2 toward the outside and along the horizontal direction (direction parallel to the floor of the room). They are spaced apart. With this configuration, each of the cameras 4 and 5 captures a moving image of an area including the object 11 located on the front surface 2a side of the case 2 at a position different from each other, and still images (frames) constituting the moving image. Data D1 and D2 are respectively generated at a predetermined frame rate (for example, 30 frames per second) and output to the processing unit 8.

  As shown in FIG. 2 as an example, the current measurement unit 6 includes a current-voltage conversion circuit 6a including an operational amplifier 21 and a feedback resistor 22, and an A / D converter 6b. It is arranged. In this example, as an example, the operational amplifier 21 has a non-inverting input terminal defined as a reference potential (ground potential) and an inverting input terminal connected to the detection electrode 3. With this configuration, when the current I flows between the object 11 and the detection electrode 3 via the stray capacitance C, the current-voltage conversion circuit 6a converts the current I into the voltage V by the feedback resistor 22 and outputs it. . The detection electrode 3 is regulated to the ground potential via the operational amplifier 21 of the current measuring unit 6. The A / D converter 6b receives the voltage V output from the current-voltage conversion circuit 6a, and samples the voltage V at a predetermined sampling period (as an example, the same period as the above frame rate). , Converted into current data Di indicating the voltage value of the voltage V (that is, the current value of the current I) and output to the processing unit 8.

  As an example in this example, the distance measuring unit 7 includes a pair of cameras 4 and 5 and a processing unit 8 as described later, and measures the distance L between each object 11 and the detection electrode 3.

  The processing unit 8 includes a CPU, for example, and is disposed in the case 2. The processing unit 8 stores the still image data D1 and D2 output from the cameras 4 and 5 and the current data Di output from the current measurement unit 6 in the storage unit 9, and stores the still image data D1 and D2. The charged body detection process 50 (see FIG. 3) and the output process are executed based on the current data Di. In this charged body detection process, the processing unit 8 detects the moving object 11 among the respective objects 11 based on one of the still image data D1 and D2 (in this example, still image data D1 as an example). Distance calculating process that functions as the moving body detecting process and the distance measuring unit 7 and calculates the distance L between the moving object 11 and the case 2 based on the still image data D1 and D2, An area calculation process for calculating an effective area S between the moving object 11 and the detection electrode 3 based on the image data D1, D2 and the distance L calculated in the distance calculation process, the current indicated by the current data Di A voltage calculation process for equivalently calculating the voltage value of the voltage V of the moving object 11 based on the current value of I, the calculated distance L, the calculated effective area S, and the relative dielectric constant ε of air; Calculated voltage V The object 11 is moving by comparing the threshold voltage value Vth to perform the determination process for determining whether a charged body (specific object). In this case, the effective area S is the capacitance between the pair of metal plates when the object 11 and the detection electrode 3 are equivalently paired with a pair of metal plates facing each other in parallel. The area of this metal flat plate when it becomes the same as the above-mentioned stray capacitance C shall be said. Further, in the output processing described above, the processing unit 8 generates a moving image of the region including the object 11 based on at least one of the still image data D1 and D2 (one still image data D1 in this example). Output to the output unit 10.

  The storage unit 9 is configured by a semiconductor memory such as a ROM or a RAM as an example, and is disposed in the case 2. In addition, the storage unit 9 stores in advance an operation program for the processing unit 8 and a threshold voltage value Vth. Further, the storage unit 9 functions as a work memory of the CPU that constitutes the processing unit 8.

  As an example, the output unit 10 is configured as a display unit using a display device such as a liquid crystal display. As an example in this example, the output unit 10 is disposed outside the case 2 and connected to the processing unit 8 via a signal cable as shown in FIG. Still image data D3 output at the frame rate (the still image data D1 is subjected to image processing so that the object 11 detected as a specific object can be distinguished from other objects 11 as it is or still image data D1. The still image data) is input, and a moving image of the region including the object 11 is displayed on the screen 10a.

  Next, the charged body detection method together with the operation of the charged body detection apparatus 1 will be described with reference to the drawings.

  In the charged body detection device 1, each camera 4, 5 captures a moving image of a region including each object 11 positioned on the front surface 2 a side of the case 2 and still image data ( Frame data) D1 and D2 are output to the processing unit 8 at a predetermined rate. The current measuring unit 6 converts the current I flowing between the current-voltage conversion circuit 6a and the detection electrode 3 into a voltage V, and the A / D converter 6b converts the current data Di indicating the voltage value of the voltage V into current data Di. The data is converted and output to the processing unit 8.

  The processing unit 8 executes a storage process each time still image data D1 and D2 are input from the cameras 4 and 5, and stores the still image data D1 and D2 in the storage unit 9. Further, each time the current data Di is input from the current measuring unit 6, the processing unit 8 executes a storage process and stores the current data Di in the storage unit 9. In this case, the processing unit 8 stores the latest plural (at least two) data including the latest data in the storage unit 9 for each of the still image data D1 and D2 and the current data Di while updating the data. .

  Further, the processing unit 8 executes the charged body detection process 50 while executing the above storage process. In the charged body detection process 50, the processing unit 8 first executes a moving body detection process (step 51). In this moving body detection process, the processing unit 8 moves among the objects 11 by executing inter-frame difference processing based on the two most recent still image data D1 stored in the storage unit 9. The detected object 11 is detected. As an example, as shown in FIGS. 1 and 2, when only the object 11c is moving, the position of the image constituting the object 11c and the number of pixels of the image change between the two most recent still image data D1. Therefore, the processing unit 8 detects that the object 11c is a moving body by detecting the change in the image of the object 11c by inter-frame difference processing. Note that the processing unit 8 repeatedly executes this moving object detection process until a moving object is detected.

  Next, when a moving body (in this example, a moving object 11c) is detected in the moving body detection process, the processing unit 8 executes a distance calculation process (step 52). In this distance calculation process, the processing unit 8 is based on the most recent data about the still image data D1 and D2 stored in the storage unit 9 and the distance (baseline length) between the cameras 4 and 5. The latest distance Lnew from the case 2 (specifically, the detection electrode 3) to the moving body (object 11c) (the distance Lc to the object 11c at the present time) is calculated. Further, the processing unit 8 starts moving from the case 2 to the moving object (object 11c) based on the data immediately before the latest data and the baseline length for each of the still image data D1 and D2 stored in the storage unit 9. The distance Lold at the past time point is calculated for one frame rate until.

  Further, the processing unit 8 calculates a difference ΔL (= Lnew−Lold) between the two distances Lnew and Lold calculated in this way, and per unit time (sampling period or frame rate) of the distance L with respect to the moving object. The amount of change (distance change amount) ΔL is stored in the storage unit 9 together with the distances Lnew and Lold. Thereby, the distance calculation process is completed. The processing unit 8 executes the distance calculation process each time the storage process is executed (every time each of the still image data D1 and D2 stored in the storage unit 9 is updated). The amount of change ΔL and the distances Lnew and Lold are calculated in real time, and updated and stored in the storage unit 9.

  Subsequently, the processing unit 8 executes an area calculation process (step 53). In the area calculation process, the processing unit 8 and the moving object 11 (object 11c) are based on the still image data D1 and D2 and the distance L (respective distances Lnew and Lold) calculated in the distance calculation process. An effective area S with respect to the detection electrode 3 is calculated. Specifically, the processing unit 8 includes the object 11c acquired from the latest data on one of the still image data D1 and D2 (in this example, still image data D1) stored in the storage unit 9. And the direction connecting the camera (camera 4 in this example) and the object 11c (specifically, the direction in the horizontal plane of the object 11c with respect to the direction (optical axis) of the camera 4) Based on the angle between the straight line connecting the camera 4 and the object 11c and the optical axis in the horizontal plane)) and the calculated distance Lnew, the latest effective area Snew for the object 11c is calculated. In addition, the processing unit 8 has the object 11c acquired from the data immediately before the latest data for one of the still image data D1 and D2 (still image data D1) stored in the storage unit 9. Based on the number of pixels, the direction of the object 11c, and the calculated distance Lold, an effective area Sold for the object 11c is calculated.

  Further, the processing unit 8 calculates a difference ΔS (= Snew−Sold) between the two effective areas Snew and Sold calculated in this way, and unit time (sampling period, that is, frame rate) of the effective area S for the moving object. ) Is stored in the storage unit 9 together with the effective areas Snew and Sold as a change amount (area change amount) ΔS. Thereby, the area calculation process is completed. The processing unit 8 executes the area calculation process each time the storage process is executed (every time each of the still image data D1 and D2 stored in the storage unit 9 is updated), so that the effective area S for the moving object is obtained. Change amount ΔS and effective areas Snew and Sold are calculated in real time and updated and stored in the storage unit 9.

  Next, the processing unit 8 executes a voltage calculation process (step 54). In this voltage calculation process, the processing unit 8 first calculates the current value I1 of the current I flowing between the detection electrode 3 and the current measurement unit 6 based on the latest current data Di stored in the storage unit 9. calculate. In this example, since only the object 11c of each object 11 is moving, only the stray capacitance C3 among the stray capacitances C1, C2, C3 formed between each object 11 and the detection electrode 3 changes. doing. In this case, since the current I generated in the detection electrode 3 is generated in accordance with the change in the stray capacitance C, the generation of the current I measured by the current measuring unit 6 is derived from the moving object 11c. .

The processing unit 8 calculates the distance Lnew stored in the storage unit 9, the change amount ΔL of the distance L, the effective area Snew and the change amount ΔS of the effective area S, and the calculated current value I1 of the current I from the following formula (1 The voltage value Vm of the moving body (object 11c) is calculated and stored in the storage unit 9. Thereby, the voltage calculation process is completed.
Vm = I1 / (ε × ΔL ² / (ΔS × Lnew−Snew × ΔL)) (1)

The equation (1) is calculated as follows. That is, when the object 11 is charged to the voltage value Vm, between the voltage value Vm, the stray capacitance C between the object 11 and the detection electrode 3, and the charge Q stored in the stray capacitance C. Q = C × Vm, and this stray capacitance C is calculated using the effective area S between the object 11 and the detection electrode 3, the relative permittivity ε of air, and the distance L, C = ε × S / Since it is represented by L, when this is substituted into the above Q = C × Vm, it is represented by the following equation (2).
Q = ε × S / L × Vm (2)

Also, differentiating both sides of this equation with time, the following equation (3) is obtained:
dQ / dt = ε × Vm × d (S / L) / dt (3)
In this case, the left side corresponds to the current I because it indicates the amount of change of the charge Q per unit time. On the other hand, since the effective area S and the distance L on the right side are both functions of the time t, d (S / L) / dt is a division value obtained by dividing the effective area S by the distance L per unit time. This corresponds to the amount of change, and is expressed as ((ΔS × L−S × ΔL) / ΔL ² ), where ΔS and ΔL are the amounts of change per unit time of the effective area S and the distance L.

Thereby, the right side is represented as ε × Vm × ((ΔS × LS−ΔL) / ΔL ² ). That is, the above formula (3) is represented by the following formula (4),
I = ε × Vm × ((ΔS × LS−ΔL) / ΔL ² ) (4)
By solving this equation (4) for Vm, the following equation (5) is calculated.
Vm = I / (ε × ΔL ² / (ΔS × L−S × ΔL)) (5)
Finally, by substituting the current value I1 for the current I in the equation (5) and the distance Lnew and effective area Snew calculated at the same timing as the current value I1 into the distance L and effective area S, respectively, Equation (1) is calculated equivalently. Although Vm also changes with time, the amount of change is extremely small, so it is treated as a constant.

  Subsequently, the processing unit 8 executes a discrimination process (step 55). In this determination process, the processing unit 8 compares the voltage value Vm of the moving object (object 11c) calculated in the voltage calculation process with the threshold voltage value Vth stored in the storage unit 9 to determine the voltage value. When Vm is equal to or higher than the threshold voltage value Vth, it is determined that the moving body is a specific object (charged and moving object 11), and that fact is associated with the object 11c in the storage unit 9. Remember. Thereby, the discrimination process is completed, and the charged body detection process 50 is also completed.

  The processing unit 8 executes the output process while executing the above storage process. In this output process, the processing unit 8 inputs still image data D1 and D2 from the cameras 4 and 5 and stores them in the storage unit 9 (every time the storage process is executed), each of the still image data D1 and D2 is stored. A still image data D3 is generated based on at least one of the data (one still image data D1 in this example), and the still image data D3 is output to the output unit 10 so that a moving image of the region including the object 11 is generated. The image is displayed on the screen 10a of the output unit 10 as shown in FIG. In this case, when the charged object detection process 50 does not detect the object 11 as the specific object, the processing unit 8 outputs the still image data D1 as it is to the output unit 10 as the still image data D3. On the other hand, when the processing unit 8 detects the object 11 as the specific object in the charged body detection process 50, the processing unit 8 performs image processing on the still image data D1 to obtain another image of the object 11 detected as the specific object. The still image data D3 is generated by processing it into a display mode that can be distinguished from the image of the object 11. In this example, as an example, as illustrated in FIG. 4, the processing unit 8 indicates an image of the object 11 (the object 11 c) as the specific object with an arrow mark 31 (an example of a display indicating that the object is a charged body). Image processing to be an image is performed on the still image data D 1 to generate still image data D 3, and the still image data D is output to the output unit 10. Thereby, since the object 11c detected as the specific object is displayed while moving together with the arrow mark 31 on the screen 10a of the output unit 10, the operator of the charged body detection apparatus 1 can display the screen 10a of the output unit 10. It is possible to recognize that the object 11c is a specific object based on the moving image displayed on the screen.

  As described above, in this charged body detection device 1 and this charged body detection method, the voltage value Vm of the moving object 11 is directly calculated using the stray capacitances C1, C2, C3 between the detection electrode 3 and the object 11. taking measurement. Therefore, according to this charged body detection device 1 and this charged body detection method, it is not necessary to use an antenna that causes an increase in the size of the device, so that the device can be reduced in size and regardless of whether a discharge occurs. The charged object 11 (charged body) can be detected.

  Further, according to the charged object detection device 1, the screen 10a of the output unit 10 is displayed with the arrow mark 31 (display indicating that the object is a charged object) added to the image of the object 11 (object 11c) as the specific object. Since it is displayed above, it is possible to make the operator clearly recognize the object 11 that moves in an uncharged state.

  In the above example, a configuration in which the arrow mark 31 is added to the image of the object 11 (the object 11c) as the specific object is used as a display indicating that it is a charged body, but regardless of the shape of the arrow. A configuration in which marks, characters, symbols, and the like of other arbitrary shapes (various shapes such as a round shape, a square shape, and a star shape) are added may be employed. In addition, a configuration in which a specific object is provided with a color that can be distinguished from other objects can be adopted as a display indicating that it is a charged body.

  Further, in the above-described charged body detection device 1, the configuration in which the output unit 10 is disposed outside the case 2 is employed, but the configuration in which the output unit 10 is disposed in the case 2 can also be employed. Further, by using the two cameras 4 and 5, the processing unit 8 functions as the distance measuring unit 7 based on the still image data D1 and D2 output from the cameras 4 and 5, and the distance L to the object 11 is detected. However, for example, a configuration including a distance measuring device (for example, a laser distance meter) that can measure the distance L to each object 11 may be employed. According to this configuration, the number of cameras can be reduced to one.

1 Charged body detection device
3 detection electrodes
4,5 camera
6 Current measurement unit
7 Distance measuring section
8 Processing unit 11 Object C1, C2, C3 Floating capacitance D1, D2 Still image data
I current

Claims (3)

A sensing electrode capacitively coupled to a specific object via a stray capacitance;
A current measurement unit that measures a current value of a current flowing between the specific object and the detection electrode via the stray capacitance;
A camera that captures a moving image of an area including the specific object and outputs still image data constituting the moving image;
A distance measuring unit for measuring a distance to the specific object;
When the movement of the specific object is detected based on the still image data, the number of pixels of the image constituting the specific object in the still image data, the measured distance, and the camera and the specific object are determined. An area calculation process for calculating an effective area between the specific object and the detection electrode based on the connecting direction, a change per unit time of a division value obtained by dividing the calculated effective area by the measured distance A voltage calculation process for calculating the voltage value and equivalently calculating the voltage value of the specific object by dividing the current value by the amount of change, and the calculated voltage value and a predetermined threshold voltage value. A charged body detection device comprising: a processing unit that executes a determination process for determining whether the specific object is a charged body by comparison.   The processing unit displays a moving image of the region on the display unit based on the still image data, and attaches a display indicating that the charged object is an image of the specific object detected as the charged body. The charged body detection apparatus according to claim 1, which is displayed on the display unit.   While capturing a moving image of an area including the specific object with a camera in a state where the specific object and the detection electrode are capacitively coupled via a stray capacitance, the specific object is moved based on still image data constituting the moving image. Is detected based on the number of pixels of the image constituting the specific object in the still image data, the distance to the specific object, and the direction connecting the camera and the specific object. An area calculation process for calculating an effective area between and the calculated effective area by dividing the calculated effective area by the measured distance, and calculating a change amount per unit time and dividing the current value by the change amount Voltage calculation processing for equivalently calculating the voltage value of the specific object by dividing by the value, and comparing the calculated voltage value with a predetermined threshold voltage value, Charging object detection method for performing a determination process for determining whether the body or not.

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