JP2016109476A - Electrostatic measurement device and electrostatic removal system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic measurement device and an electrostatic removal system which can improve a measurement accuracy of the surface potential of the static electricity of a measurement object during transport.SOLUTION: An electrostatic measurement device 10 includes: an electrode 30 for detecting a change of the potential generated by a measurement object 14 transported by a transport device 16; a signal component generation part 44 for generating a signal of the signal component in which a noise component is removed by adding a maximum value and a minimum value of a change potential signal detected from the electrode 30; and a potential calculation part 48 for calculating the surface potential of the measurement object 14 on the basis of the signal of the signal component. The electrostatic removal system 12 includes the electrostatic measurement device 10 and an antistatic device 18.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a static electricity measuring apparatus that measures the surface potential of a measurement object being conveyed and a static electricity removal system that neutralizes static electricity charged on the measurement object.

  Patent Document 1 listed below discloses a static electricity amount measuring device that receives a virtual electromagnetic wave generated by applying vibration to a measurement object by a receiving unit and measures the static electricity amount. In Patent Document 2 below, the surface potential of a measurement object is measured using a sensor unit composed of a sensor electrode and a tuning-fork type vibrating body provided between the sensor electrode and the measurement object. A surface potential measuring device is disclosed.

JP 2013-3039 A JP-A-8-129043

  When measuring the surface potential (electrostatic quantity) of the measurement object using the techniques of Patent Documents 1 and 2, the measurement object is vibrated or the tuning fork vibration is generated between the measurement object and the sensor electrode. By vibrating the body or rotating the rotary impeller, an alternating potential signal (virtual electromagnetic wave) having an amplitude level corresponding to the surface potential of the measurement object is generated, and the alternating potential signal is transmitted to the sensor unit ( (Receiving unit). In other words, the amount of change is detected by interrupting the lines of electric force.

  Therefore, since the surface potential of the measurement object is calculated by integrating the change in the AC potential signal, a time delay of a certain time (for example, about 0.5 seconds) occurs in the calculation of the surface potential. That is, since the signals obtained by synchronously detecting the intermittent lines of electric force are connected and integration is performed to smooth them, a time delay of a certain time occurs in the calculation of the surface potential. Therefore, when measuring the surface potential (electrostatic amount) of a measurement object being conveyed by a conveyance device such as a belt conveyor, the measurement object conveyance speed is faster than a predetermined speed (for example, several tens of mm / sec). The measurement object passes before the measurement of the surface potential of the measurement object by the surface potential measuring device (electrostatic quantity measuring device) is completed. The reason will be briefly described with reference to FIG.

  For example, positive (+) static electricity is charged on the surface, and the measurement object 100 whose surface potential is, for example, +10 kV is at a constant speed (for example, a speed faster than several tens of mm / sec) by the conveyor belt 102 or the like. Suppose that it is transported in the transport direction. When the measurement object 100 comes near the sensor unit (reception unit) 104 of the surface potential measuring device, the surface potential measured by the surface potential measuring device gradually increases as shown by the solid line waveform 106 in FIG. To do. However, since the measuring object 100 passes through the sensor unit 104 before the surface potential of the measuring object 100 measured by the surface potential measuring instrument becomes +10 kV, the surface potential measured by the surface potential measuring instrument is actually This is a value smaller than the surface potential of the measurement object. As a result, the surface potential of the measurement object cannot be accurately measured.

  Accordingly, an object of the present invention is to provide a static electricity measuring apparatus and a static electricity removing system that improve the measurement accuracy of the surface potential of a measurement object being conveyed.

  The present invention is an electrostatic measurement device, which adds an electrode for detecting a change in potential caused by a measurement object transported by a transport device, and a maximum value and a minimum value of a change potential signal detected from the electrode. Thus, a signal component generation unit that generates a signal component signal from which the noise component has been removed, and a potential calculation unit that calculates the surface potential of the measurement object based on the signal component signal are provided.

  The present invention is the static electricity measuring apparatus, wherein an amplifying unit that amplifies the change potential signal detected from the electrode, and a low-pass that removes a high-frequency noise component contained in the change potential signal amplified by the amplifying unit. And the signal component generation unit adds the maximum value and the minimum value of the change potential signal from which the high-frequency noise component has been removed by the low-pass filter, thereby obtaining the signal component signal. It may be generated.

  The present invention may be the static electricity measuring apparatus, further comprising a display unit that displays a value of a surface potential of the measurement object or a signal waveform of the signal component.

  The present invention is the static electricity measuring apparatus, wherein the electrode is made of a circular or polygonal metal.

  The present invention is a static elimination system, which is a static elimination device that neutralizes static electricity charged on the measurement target based on the surface potential of the measurement target calculated by the static measurement device and the potential calculation unit. With.

  According to the present invention, the signal component generation unit generates the signal component signal from which the noise component has been removed by adding the maximum value and the minimum value of the change potential signal detected from the electrodes. It can be configured with only simple electrodes, and the cost is low. Further, since the potential change is detected by this electrode and the surface potential of the measurement object is measured based on the detected change potential signal, the measurement accuracy of the surface potential of the measurement object being conveyed is improved.

It is a figure which shows the structure of the static elimination system provided with an electrostatic measurement apparatus. It is a figure which shows the structure of the electrode shown in FIG. It is a figure which shows the structure of the signal component production | generation part shown in FIG. It is a figure which shows the waveform of the change potential signal which does not contain the noise component detected by the electrode shown in FIG. It is a figure which shows the waveform of the change potential signal actually detected by the electrode shown in FIG. It is a figure explaining the subject of a prior art.

  BEST MODE FOR CARRYING OUT THE INVENTION A static electricity measuring apparatus and a static electricity removing system having an electrostatic electricity measuring apparatus according to an aspect of the present invention will be described in detail below with reference to the accompanying drawings. In addition, the aspect of this invention is not limited to these embodiment, What added the various change or improvement is included. That is, the constituent elements described below include those that can be easily assumed by those skilled in the art and substantially the same elements, and the constituent elements described below can be appropriately combined. In addition, various omissions, substitutions, or changes of the components can be made without departing from the scope of the present invention.

  FIG. 1 is a diagram illustrating a configuration of a static electricity removal system 12 including a static electricity measuring device 10. The static electricity removal system 12 is a static measurement that measures (measures) a transport device 16 that transports the measurement object 14 and a static potential (surface potential) charged on the measurement object 14 that is transported by the transport device 16. The apparatus 10 includes a static elimination device 18 that neutralizes static electricity charged on the measurement object 14. The static electricity measuring device 10 is a surface potential measuring device that measures the surface potential of static electricity charged on the surface of the measurement object 14.

  The measurement object 14 to be measured is various parts and products flowing through a production line such as a factory. Examples of the measurement object 14 include a component package, an electronic component, a semiconductor integrated component, a semiconductor wafer, an electronic element, a substrate, a connector, an electronic device, a textile product, a chemical, a chemical, a film, a resin, a plastic, a packaging material, and And food.

  The transport device 16 transports the measurement object 14 along the transport direction A. The conveying device 16 includes a conveying belt 20, a driving roller 22 that moves the conveying belt 20, a drive control unit 24 that drives and controls the driving roller 22, and the like. When the drive roller 22 is rotated by the drive control of the drive control unit 24, the transport belt 20 moves along the transport direction A, and the transport speed of the measurement object 14 is determined according to the rotational speed of the drive roller 22. The measurement object 14 is placed on the conveyance belt 20 and is conveyed by the conveyance belt 20 moving along the conveyance direction A. Although not shown, the drive control unit 24 includes a motor that rotates the drive roller 22 and a driver that drives the motor. The drive control unit 24 may convey the measurement object 14 at a constant conveyance speed by rotating the drive roller 22 at a constant speed.

  The static electricity measuring apparatus 10 includes an electrode 30, a signal processing unit 32, and a display unit 34. The electrode 30 serving as a sensor unit detects a change in potential, and detects a change in potential caused by the measurement object 14 transported by the transport device 16. The electrode 30 is fixedly disposed at a predetermined position on the transport path of the transport device 16, and is spaced a predetermined distance (predetermined distance) from the measurement object 14 to be transported. Opposed. A change potential signal of the electrode 30 (an analog signal indicating the detected change amount of the potential) is input to the signal processing unit 32.

  As shown in FIG. 2, the electrode 30 is made of a circular (including a perfect circle and an ellipse) metal such as copper or aluminum. A signal line 36 is connected to the center point of the metal electrode 30, and the other end of the signal line 36 is connected to the amplification unit 40 of the signal processing unit 32. The signal line 36 is covered with a shield member 38, and the shield member 38 is grounded. In addition, you may comprise the electrode 30 by polygonal electrodes, such as a square and a pentagon. In short, the electrode 30 may be a plate-like or plate-like metal, and the shape thereof is not limited. Further, although the electrode 30 is attached to the central conductor (signal line 36) of the coaxial cable, the signal line 36 is simply cut, that is, the electrode 30 is not provided as shown in FIG. Also good. Even if the electrode 30 as shown in FIG. 2 is not provided, if the end of the cut portion of the signal line 36 is exposed to the outside, the end of the cut portion of the signal line 36 functions as an electrode. is there. Furthermore, even if the end portion of the cut portion is electrically insulated, it is not covered with metal or the like, or if the signal line 36 is not short-circuited with the shield member 38 (ground GND), The end portion functions as the electrode 30.

  The signal processing unit 32 includes an amplification unit 40, a low-pass filter 42, a signal component generation unit 44, an AD conversion unit 46, and a potential calculation unit 48. The amplifying unit (amplifying circuit) 40 amplifies the analog change potential signal detected by the electrode 30 and outputs the amplified signal to the low-pass filter 42. The low-pass filter 42 removes a high-frequency noise component included in the change potential signal amplified by the amplification unit 40 and outputs the high-frequency noise component to the signal component generation unit 44.

  The signal component generation unit 44 adds the maximum value and the minimum value of the change potential signal to generate a signal component signal from which the noise component has been removed. Specifically, as shown in FIG. 3, the signal component generation unit 44 extracts a maximum value extraction unit 50 that extracts the maximum value of the change potential signal, a minimum value extraction unit 52 that extracts the minimum value of the change potential signal, and extraction. And an adder (adder) 54 for adding the maximum value and the minimum value of the changed potential signal. The signal component generation unit 44 outputs the generated signal component signal (addition signal) to the AD conversion unit 46. The reason why the signal component generation unit 44 is provided will be described below.

  FIG. 4 is a diagram illustrating a waveform 60 of a change potential signal that does not include a noise component detected by the electrode 30. A waveform 60 shows the change potential signal after the high-frequency noise component is removed by the low-pass filter 42. The surface of the measurement object 14 is assumed to be charged with positive (+) static electricity, and the surface potential is set to a predetermined potential (positive potential). In the present embodiment, the shape of the measurement object 14 is a rectangular parallelepiped, but is not limited to this.

  Until the end of the measuring object 14 on the conveyance direction A side passes through the electrode 30, the change potential signal (potential change amount) detected by the electrode 30 is 0V. When the end of the measuring object 14 on the conveyance direction A side passes through the electrode 30, the change potential signal of the electrode 30 swings to the positive (+) side. Thereafter, when the end of the measurement object 14 opposite to the conveyance direction A passes through the electrode 30, the change potential signal detected by the electrode 30 swings to the negative (−) side. Needless to say, while the portion between the end of the measuring object 14 on the conveyance direction A side and the opposite end passes through the electrode 30, the change potential signal detected by the electrode 30 is When the surface of the measurement object 14 is uniformly charged at the same potential and is charged with static electricity, the voltage is 0 V as shown in FIG. 4, but when there is uneven charging, it varies depending on the amount of electrostatic charge. .

  Note that, when negative (-) static electricity is charged on the surface of the measurement object 14, the waveform 60 is inverted. That is, when the end of the measurement object 14 on the conveyance direction A side passes through the electrode 30, the change potential signal of the electrode 30 swings to the negative (−) side, and the end of the measurement object 14 on the opposite side to the conveyance direction A. When the part passes through the electrode 30, the change potential signal detected by the electrode 30 swings to the positive (+) side. Therefore, the polarity of the static electricity charged on the measurement object 14 can also be determined depending on whether the change potential signal first swings positive or negative.

  However, as shown in FIG. 5, the change potential signal actually detected by the electrode 30 includes a noise component signal that cannot be removed by the low-pass filter 42 in addition to the signal component signal. A hatched portion in FIG. 5 is a noise component of the change potential signal, and a waveform indicated by a dotted line 62 is a signal component to be detected. The dotted line 62 in FIG. 5 is the same as the waveform 60 shown in FIG. This noise component is generated when the conveying device 16 drives the conveying belt 20 using magnetic force. More specifically, since the drive control unit 24 in the transport device 16 drives the motor by a switching power supply, this becomes a cause of generation of switching noise and magnetic noise. In addition, a component conveyance system (for example, a parts feeder or the like) that vibrates by magnetism is adjacent to the periphery, and these electromagnetic waves become large interference waves for static electricity detection. The parts feeder is a device that feeds out parts by using an electromagnet to shift the phase in two directions, up and down and left and right.

  Therefore, in the present embodiment, a signal component generation unit 44 is provided, and the signal component generation unit 44 adds the maximum value (positive) and minimum value (negative) of the change potential signal detected by the electrode 30. 4 generates substantially the same signal (signal component signal) as the waveform 60 shown in FIG. The signal component generation unit 44 may generate the signal component signal by subtracting the absolute value of the minimum value of the change potential signal from the absolute value of the maximum value of the change potential signal.

  The AD conversion unit 46 converts an output signal of the signal component generation unit 44, that is, an analog signal component signal into a digital signal, and outputs the converted signal component signal to the potential calculation unit 48 and the display unit 34. To do.

  The potential calculation unit 48 calculates the surface potential of the measurement object 14 based on the signal component signal converted into a digital signal. Specifically, among the signals of the signal component generated by the signal component generation unit 44, when the end of the measurement target 14 on the transport direction A side passes through the electrode 30, the potential at which the swing width becomes the largest is obtained. Multiply the coefficient to calculate the surface potential. That is, when the static electricity charged in the measurement object 14 is positive (+), the surface potential is calculated by multiplying the maximum value of the potential of the signal component by the coefficient, so that the calculated surface potential is positive (+ ) On the contrary, when the static electricity charged in the measurement object 14 is negative (−), the surface potential is calculated by multiplying the minimum value of the potential of the signal component by a coefficient, so that the calculated surface potential is negative ( −). This coefficient is a value determined in advance by experiments or the like. The potential calculation unit 48 outputs the calculated surface potential of the measurement object 14 to the display unit 34 and the charge removal apparatus 18. The potential calculation unit 48 can be configured by a computer. The surface potential calculated by the potential calculation unit 48 is calibrated in advance by measuring a sample charged with a known potential with the electrode 30 or a calibrated surface potential meter.

  The potential calculation unit 48 may integrate the signal component signal generated by the signal component generation unit 44. A waveform 64 in FIG. 4 is a waveform when the signal component signal is integrated. It can be seen that this waveform 64 indicates the shape of the measurement object 14 along the conveyance direction A. That is, the potential calculation unit 48 may calculate and recognize the shape of the measurement object 14 by integrating the signal component signal.

  The display unit 34 includes a display (liquid crystal display or the like) and a drive control unit that controls driving of the display (not shown), and the waveform of the signal component signal output from the AD conversion unit 46 or the potential calculation unit. 48 displays the value of the surface potential of the measurement object 14 calculated. The display unit 34 may display the shape of the measurement object 14 calculated by the potential calculation unit 48.

  The static eliminator 18 neutralizes (removes) the static electricity charged in the measurement object 14 based on the surface potential of the measurement object 14 calculated by the potential calculation unit 48, that is, measured by the static electricity measurement apparatus 10. When the measurement target 14 is charged with positive (+) static electricity, the static eliminator 18 charges the measurement target 14 by, for example, injecting negatively charged ions onto the measurement target 14. Remove static electricity. Conversely, when the measurement object 14 is charged with negative (−) static electricity, for example, by discharging positively charged ions to the measurement object 14, the static electricity charged on the measurement object 14 is removed. To do. At this time, the amount of ions to be ejected is changed according to the measured surface potential of the measurement object 14. That is, ions are ejected in an amount that removes static electricity from the measured measurement object 14. This is because if a larger amount of ions than the amount of static electricity to be removed from the measurement object 14 is ejected, the measurement object 14 is charged with static electricity having the opposite polarity. The static elimination device 18 neutralizes static electricity charged on the measurement object 14 by ejecting ions, but static electricity may be eliminated by other methods. In addition, the static electricity measuring device 10 is further provided on the downstream side as viewed from the conveyance direction A from the static eliminator 18, and it is confirmed whether static electricity has been removed by the static electricity measuring device 10 further provided on the downstream side after the static electricity removal by the static eliminator 18. May be.

  In this way, the signal component generation unit 44 adds the maximum value and the minimum value of the change potential signal detected from the electrode 30 to generate a signal component signal from which the noise component has been removed. A simple electrode 30 can be used, and the cost is low. Further, since the potential change is detected by the electrode 30 and the surface potential of the measurement object 14 is measured (calculated) based on the detected change potential signal, the surface potential of the measurement object 14 being conveyed is measured. (Measurement) accuracy is improved. That is, even when the conveyance speed of the measurement object 14 is higher than a predetermined speed (for example, several tens of mm / sec), the surface potential of the measurement object 14 can be measured.

  Since the static electricity measuring apparatus 10 of this Embodiment detects the change potential signal of the measurement target object 14 currently conveyed, it cannot measure the surface potential of the stationary measurement target object 14. Further, in the present embodiment, the static electricity measuring device 10 measures the surface potential of the measurement object 14 that is linearly conveyed by the conveying device 16, but is rotated and conveyed so as to draw an arc. The surface potential of the measurement object 14 may be measured. In this case, the conveying device 16 has a rotating disk that rotates about the central axis, and the measuring object 14 can be rotated and conveyed by placing the measuring object 14 on the rotating disk. . In short, if the relative velocity between the electrode 30 and the measurement object 14 is not zero, the electrostatic measurement device 10 can measure the surface potential of the measurement object 14. Therefore, the surface potential of the measurement object 14 can be measured by moving the electrode 30 while keeping the measurement object 14 stationary without being conveyed. The transport device 16 of the present embodiment may be any device that can displace the relative position between the electrode 30 and the measurement object 14.

  Since the amplifying unit 40 that amplifies the change potential signal detected by the electrode 30 and the low-pass filter 42 that removes the high-frequency noise component contained in the change potential signal amplified by the amplifying unit 40 are provided, the measurement object 14 is more accurately detected. Can be measured (calculated).

  Since the display unit 34 for displaying the value of the surface potential of the measurement object 14 or the waveform of the signal component signal is provided, the waveform of the signal component signal or the surface from which the surface potential of the measurement object 14 is calculated is calculated. The user can recognize the potential value.

  Since the static elimination device 18 that neutralizes (removes) the static electricity charged on the measurement object 14 is provided based on the surface potential of the measurement object 14, the static electricity charged on the measurement object 14 can be accurately eliminated. Can do.

  Part or all of the signal processing unit 32 may be realized by hardware such as an electric circuit, or may be realized by software using a computer that executes processing according to a program.

  Although not described in the above embodiment, the transport device 16 may be provided with a position sensor that detects to which position the measurement object 14 has been transported. For example, the position sensor may be provided in the vicinity of the position where the electrode 30 is provided and at a predetermined position upstream from the position where the electrode 30 is provided as viewed in the transport direction A. Thereby, the timing at which the measurement object 14 passes by the position sensor can be detected. Therefore, from the distance between the position sensor and the electrode 30, the conveyance speed of the measurement object 14, and the detection timing of the measurement object 14 by the position sensor, the end on the conveyance direction A side of the measurement object 14 is the electrode. The timing of passing 30 can also be obtained. The timing at which the measurement object 14 passes through the charge removal device 18 is also determined from the distance between the position sensor and the charge removal device 18, the conveyance speed of the measurement object 14, and the detection timing of the measurement object 14 by the position sensor. Can do. The timing at which the measurement object 14 passes through the electrode 30 or the static eliminator 18 may be calculated by a host controller (not shown) of the static eliminator system 12, and the drive controller 24, the potential calculator 48, or the static eliminator 18. The control unit (not shown) may calculate.

DESCRIPTION OF SYMBOLS 10 ... Static electricity measuring apparatus 12 ... Static electricity removal system 14 ... Measurement object 16 ... Conveyance apparatus 18 ... Static elimination apparatus 20 ... Conveyance belt 22 ... Drive roller 24 ... Drive control part 30 ... Electrode 32 ... Signal processing part 34 ... Display part 36 ... Signal line 38 ... Shield member 40 ... Amplifier 42 ... Low pass filter 44 ... Signal component generator 46 ... AD converter 48 ... Potential calculator 50 ... Maximum value extractor 52 ... Minimum value extractor 54 ... Adder

Claims (5)

An electrode for detecting a change in potential caused by the measurement object conveyed by the conveying device;
A signal component generation unit that generates a signal component signal from which a noise component has been removed by adding the maximum value and the minimum value of the change potential signal detected from the electrode;
A potential calculation unit that calculates a surface potential of the measurement object based on a signal of the signal component;
An electrostatic measurement apparatus comprising: The static electricity measuring apparatus according to claim 1,
An amplifier for amplifying the change potential signal detected from the electrode;
A low-pass filter for removing high-frequency noise components contained in the change potential signal amplified by the amplification unit;
With
The signal component generation unit generates a signal of the signal component by adding the maximum value and the minimum value of the change potential signal from which a high-frequency noise component has been removed by a low-pass filter. apparatus. The static electricity measuring apparatus according to claim 1 or 2,
An electrostatic measurement apparatus comprising: a display unit that displays a value of a surface potential of the measurement object or a signal waveform of the signal component. It is the static electricity measuring device of any one of Claims 1-3,
The electrostatic measurement apparatus, wherein the electrode is made of a circular or polygonal metal. The static electricity measuring device according to any one of claims 1 to 4,
Based on the surface potential of the measurement object calculated by the potential calculation unit, a static eliminator that neutralizes static electricity charged on the measurement object;
An electrostatic removal system comprising:

Images