JP2012128535A - Reference potential generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a reference potential generator capable of supplying stable reference potential.SOLUTION: A reference potential generator 1 comprises: m (m is an even number equal to or greater than four) electrodes 21A to 21D that are arranged around a reference position in a rotationally symmetric manner; application means for applying electrical charge whose intensity within an adjacent range including the reference position is less than a predetermined value to the m electrodes 21A to 21D; multiple conductors 31A and 31B that are arranged in the range; and amplification means 33 for amplifying a difference between signals obtained from a plurality of conductors 31A and 31B arranged in the range.

Description

  The present invention relates to a reference potential generating device, which is suitable for a device that cannot be grounded.

  For example, a portable device such as a communication terminal device cannot be grounded, making it difficult to obtain a reference potential. As a technique for solving this problem, there has been proposed by the present inventor (see Patent Document 1).

  In this technique, for example, four electrodes are arranged rotationally symmetrically around a reference electrode which is a pair of detection electrodes, and a signal is applied to one of the four electrodes adjacent to the other, and the other is applied to the other. Then, a signal whose phase is shifted by 180 degrees is applied. As a result, the intensity at the reference electrode in the electric field generated from the four electrodes falls within “0” or in the vicinity thereof.

JP 2010-085230 A

  However, matters such as external noise (effect of external force field) and error in the size or position of the electrode cannot be completely excluded, and the intensity at the reference electrode varies due to the matter, The reference potential was unstable.

  The present invention has been made in consideration of the above points, and an object of the present invention is to propose a reference potential generating device capable of providing a stable reference potential.

  In order to solve such a problem, the present invention is a reference potential generating device, which is m (m is an even number of 4 or more) electrodes arranged in a rotational symmetry around a position to be a reference, and should be a reference. Amplifying the difference between signals applied from the application means for applying to the m electrodes the electric charge whose intensity in the vicinity range including the position is less than a predetermined value, to the m electrodes, and the plurality of conductors arranged in the range. And amplifying means.

  In the present invention, charges are applied to the m electrodes from the applying means, and the intensity in the vicinity including the position to be the reference is less than a predetermined value by the electric field formed by the electrodes. When this electric field is affected by a force field in the external environment, a potential fluctuation occurs in a vicinity range including a position to be a reference.

  However, in the present invention, since the difference between signals obtained from conductors arranged in the vicinity including the position to be used as a reference is amplified, the influence of external force on the electric field formed by the m electrodes is canceled out. .

  In addition, since the plurality of conductors arranged in the vicinity range including the position to be the reference is within the range surrounded by the m electrodes, direct coupling to the outside with respect to the electrode is caused by the electrode. Avoided by the electric field formed.

  Therefore, according to the present invention, it is possible to supply the amplification result of the amplification means in a stable state as a signal to be set as the reference potential. Note that stabilization of the reference potential is particularly useful in fields such as the sensing field where precise values are required.

It is a graph which shows the relative intensity change (1 [MHz]) of each electric field according to distance. It is a graph which shows the relative intensity | strength change (10 [MHz]) of each electric field according to distance. It is a figure which shows roughly the structure of a reference electric potential production | generation apparatus. It is a figure which shows roughly the relationship between an electrode position and the electric charge given to the said electrode. It is a figure which shows the electric field and electric potential distribution (1) based on simulation. It is a figure which shows the electric field and electric potential distribution (2) based on simulation. It is a figure which shows the output waveform in a measurement position and a measurement position. It is a figure which shows the structure of the reference electric potential production | generation apparatus in a measurement experiment. It is a figure where it uses for description of the area | region which becomes favorable as a measuring object. It is a figure which shows roughly the relationship (1) of the electrode position in other embodiment and the electric charge given to the said electrode. It is a graph which shows the relationship between the distance of the reference electrode in each electrode structure, and an electric potential. It is a figure which shows schematically the relationship (2) of the electrode position in another embodiment and the electric charge given to the said electrode. It is a figure which shows the structure of the reference electric potential output part in other embodiment.

(1) Electric field communication Before describing a mode for carrying out the present invention, first, electric field type communication will be described from various viewpoints.

[1-1. Classification of electric field]
When r is a distance from a minute dipole serving as an electric field generation source and P is a position separated from the distance r, the electric field intensity E at the position P is expressed by the following equation from the Maxwell equation.
It can be expressed as a music coordinate (r, θ, δ).

  Incidentally, “Q” in the equation (1) is a charge (unit is coulomb), and “l” is a distance between charges (however, “l” is compared with “r” by definition of a minute dipole. “Π” is a circular constant, “ε” is a dielectric constant of a space including a minute dipole, “j” is an imaginary unit, and “k” is a wave number.

When this equation (1) is expanded,
It becomes.

As can be seen from the equation (2), the electric fields E _r and E _Θ are the radiated electric field linearly inversely proportional to the distance from the electric field generation source (the third term of E _Θ ) and the distance 2 from the electric field generation source. A combined electric field of an induction electromagnetic field (second term of E _r , E _Θ ) inversely proportional to the power and a quasi-electrostatic field (first term of E _r , E _Θ ) inversely proportional to the third power of the distance from the electric field source Occurs as.

  Thus, the electric field can be classified into a radiation electric field, an induction electromagnetic field, and a quasi-electrostatic field in relation to the distance.

[1-2. Electric field resolution]
Here, the ratio of the change in electric field strength depending on the distance from the electric field generation source is compared between the radiation electric field, the induction electromagnetic field, and the quasi-electrostatic field.

Of the electric field E _{Θ in} the equation (2), the third term relating to the radiation electric field is differentiated by the distance r.
It can be expressed as

Further, when the second term relating to the induction electromagnetic field in the electric field E _{Θ in} the equation (2) is differentiated by the distance r, the following equation is obtained.
It can be expressed as

Further, when the first term relating to the quasi-electrostatic field is differentiated by the distance r in the electric field E _{Θ in} the equation (2), the following equation is obtained.
It can be expressed as

Note that “T” in the equations (3) to (5) is a part of the equation (2) for the sake of simplicity.
It is replaced as follows.

  As is clear from these formulas (3) to (5), the ratio of the change in the electric field strength depending on the distance is the largest component relating to the quasi-electrostatic field. That is, it can be said that the quasi-electrostatic field has a high resolution with respect to the distance.

[1-3. Relationship between electric field strength and frequency]
Here, the relationship between the relative intensity of each of the radiation electric field, the induction electromagnetic field and the quasi-electrostatic field and the distance is shown in FIG. FIG. 1 shows the relationship between the relative strength and distance of each electric field at 1 [MHz] as an index.

  As is clear from FIG. 1, there is a distance (hereinafter referred to as an intensity boundary distance) in which the relative intensities of the radiated electric field, the induction electromagnetic field, and the quasi-electrostatic field are equal. In a space far from the intensity boundary distance, the radiated electric field is dominant (a state larger than the intensity of the induction electromagnetic field or the quasi-electrostatic field). On the other hand, the quasi-electrostatic field is dominant (a state larger than the intensity of the radiated electric field and the induced electromagnetic field) in a space closer to the intensity boundary distance.

This intensity boundary distance is the component of the electric field corresponding to each term (E _Θ1 , E _Θ2 , E _Θ3 ) of the electric field E _Θ in equation (2), that is, the following equation:
(E _Θ1 = E _Θ2 = E _Θ3 )
That is, that is,
Can be expressed as

The wave number k in the equation (9) is expressed as follows when the speed of light is c (c = 3 × 10 ⁸ [m / s]) and the frequency is f [Hz].
Can be expressed as

Therefore, the intensity boundary distance is arranged by formulas (9) and (10).
It becomes.

  As can be seen from equation (11), when the space of the quasi-electrostatic field that is stronger than the radiated electric field and the induction electromagnetic field (hereinafter referred to as the quasi-electrostatic field dominant space) is widened. Are closely related in frequency.

  Specifically, the lower the frequency, the larger the quasi-electrostatic field dominant space (that is, the intensity boundary distance shown in FIG. 1 becomes longer as the frequency is lower (moves to the right)). On the other hand, the higher the frequency, the narrower the quasi-electrostatic field dominant space (that is, the intensity boundary distance shown in FIG. 1 becomes shorter as the frequency becomes higher (shifts to the left)).

  For example, when 10 [MHz] is selected, the quasi-electrostatic field becomes a space nearer than 4.775 [m] according to the above equation (11). When such 10 [MHz] is selected, the relationship between the relative intensity of each of the radiated electric field, the induction electromagnetic field, and the quasi-electrostatic field and the distance is graphed, and the result shown in FIG.

  As apparent from FIG. 2, the intensity of the quasi-electrostatic field at a point of 0.01 [m] from the electric field generation source is about 18.2 [dB] larger than that of the induction electromagnetic field. Therefore, the quasi-electrostatic field in this case can be regarded as having no influence of the induction electromagnetic field and the radiation electric field. That is, since a magnetic field is generated in the radiated electric field and the induction electromagnetic field, a current is distributed in the radiated electric field and the induction electromagnetic field, but the degree of interference with a secondary electric field due to this distribution is small.

  As described above, the quasi-electrostatic field has a relationship superior to the induction electromagnetic field and the radiated electric field in a wider space from the electric field generation source as the lower frequency band is selected. The degree of is small.

(2) Mode for carrying out the present invention [2-1. Configuration of reference potential generator]
In FIG. 3, the configuration of a reference potential generating device 1 to be mounted on a device in which it is difficult to secure an explicit reference potential, as represented by a portable electronic device such as a mobile phone or a vehicle such as a car. Show. The reference potential generating apparatus 1 includes a circuit power supply unit 10, a singular region forming unit 20, a reference potential output unit 30, and a shielding unit 40.

  The circuit power supply unit 10 generates a power supply voltage for driving the reference potential generation device 1 using a power source such as a battery of a device in which the reference potential generation device 1 is mounted, and uses the power supply voltage to generate the singular region forming unit 20 and the reference potential. This is given to the output unit 30.

  The singular region forming unit 20 includes four electrodes 21 </ b> A to 21 </ b> D, a signal oscillation source 22, and an output adjusting unit 23.

  The electrodes 21 </ b> A to 21 </ b> D have the same shape and the same size, and are arranged at positions that are the vertices of a square whose center of gravity is a position to be a reference. The signal oscillation source 22 oscillates a sine wave signal based on the drive voltage supplied from the circuit power supply unit 10.

  The output adjustment unit 23 adjusts the frequency and amplitude of the sine wave signal oscillated from the signal oscillation source 22 as necessary according to the setting value input via the operation unit, and the sine wave signal is adjusted to each square. Of the electrodes 21A to 21D arranged at the apex positions, the signals are output to the electrodes 21A and 21C arranged on one diagonal line.

  In addition, the output adjusting unit 23 is a signal (hereinafter referred to as “this”) that is different from the electrodes 21B and 21D arranged on the other diagonal by 180 ° in phase and the same frequency and amplitude as the sine wave signals output to the electrodes 21A and 21C. Are also called reverse wave signals).

  The amplitudes of the sine wave signals applied to the four electrodes 21A to 21D are set to the same value, and the frequency of the sine wave signals is a frequency satisfying “r <c / 2πf” based on the above-described equation (11). The Specifically, considering the distance between the center of gravity of the electrodes 21A to 21D and the arrangement position of the electrodes 21A to 21D, the noise floor such as the frequency band of hum noise (about 50 to 60 [Hz]) A frequency is selected that makes the difference between and clear.

  Therefore, when a sine wave signal is applied from the output adjustment unit 23 to the electrodes 21A to 21D, the combined electric field of the radiated electric field, the induction electromagnetic field, and the quasi-electrostatic field generated from the electrodes 21A to 21D has a quasi-electrostatic field advantage. It is formed as a space. Incidentally, the quasi-electrostatic field dominant space is a quasi-electrostatic field space in which the strength is higher than that of the radiation electric field and the induction electromagnetic field, as described above.

  Further, since the electrodes 21A to 21D are given the same level of charge that reverses the polarity of the adjacent electrodes, the electric fields generated by the charges cancel each other. Therefore, as shown in FIG. 4, the intensity of the electric field formed on the electrodes 21 </ b> A to 21 </ b> D is 0 [V / m] or a value close to it on the Z axis (shown by a broken line) regardless of the passage of time. Hereinafter, a region in which the electric field cancels and its intensity is less than an allowable value that can be regarded as 0 [V / m] is referred to as a singular region.

  Here, FIG. 5 and FIG. 6 show the mapping of the electric field in the xy plane obtained by superimposing the electric fields generated by the point charges shown in FIG.

  FIG. 5A shows the electric field E [V / m] on a logarithmic scale, and FIG. 5B shows the electric field E [V / m] on a linear scale. FIG. 5C shows a potential distribution corresponding to the electric field distributions of FIGS. 5A and 5B. FIGS. 6A, 6B, and 6C are enlarged views of the singular regions in FIGS. 5A, 5B, and 5C, respectively. 5 and 6, the charge Q is 1 [C], and the distance between point charges is 0.01 [m].

  As shown in FIGS. 5 and 6, it can be seen that the positions of the centers of gravity of the electrodes 21 </ b> A to 21 </ b> D existing in the xy plane and the vicinity thereof are singular regions.

  Further, as can be seen from FIGS. 5 and 6, the electric field strength at the electrodes 21A to 21D attenuates steeply. Specifically, it attenuates by a power of 2 (number of electrodes) +1. That is, the range of the electric field generated from the electrodes 21A to 21D is in a very limited state.

  This means that the external coupling range for the electrodes 21A to 21D is limited to the very vicinity. Therefore, the coupling between the electrodes 21A to 21D and the other components included in the device on which the reference potential generating device 1 is to be mounted is reduced, and the potential variation at the center of gravity (singular region) of the electrodes 21A to 21D is greatly increased. It will be suppressed. Further, the restriction on the space in which the reference potential generating device 1 is to be arranged is relaxed for the device on which the reference potential generating device 1 is to be mounted.

  As another experiment, the result of measuring the potential in the range surrounded by the four electrodes 21A to 21D is shown in FIG. 7A shows the measurement position, FIG. 7B shows the measurement result at the measurement position, the vertical axis is 5 [mv / div], and the horizontal axis is 500 [ns / div. ].

  In the measurement shown in FIG. 7, as shown in FIG. 8, an acrylic plate of 5 [mm] was arranged on the shield plate as a spacer, and electrodes 21A to 21D were arranged on one surface of the acrylic plate. The frequency of the sine wave signal or reverse wave signal applied to the electrodes 21A to 21D was 1 [MHz], and the amplitude was 1 [V]. In addition, the electric field detection sensor was distribute | arranged to each measurement position shown to FIG. 7 (A).

  As can be seen from the measurement results shown in FIG. 7, the detection level decreases from the center of gravity (point D) of the electrode 21A, 21B, 21C or 21D toward the center of gravity (point A) of the electrodes 21A to 21D, and the direct current component It is close to.

  From this result, as shown in FIG. 9, the regions between the adjacent electrodes 21A and 21B, 21B and 21C, 21C and 21D, 21D and 21A, and the region surrounded by the electrodes 21A to 21D are defined as specific regions. This is a preferred range.

  A more preferable range is a line segment divided into two rectangles (with reference to the point A in FIG. 9 as a reference) among the square symmetry axes formed by the electrodes 21A to 21D arranged at the vertices with the position to be a reference as the center of gravity. X-axis, Y-axis) or a range in the vicinity thereof (a cross-shaped range surrounded by a thick frame).

  As described above, the singular region forming unit 20 gives the charges having the opposite polarity and the same level at the positions adjacent to the electrodes 21A to 21D arranged at the positions of the respective vertices of the square, whereby the gravity centers of the electrodes 21A to 21D The position and its vicinity are formed as a region of 0 [V] (singular region).

  The reference potential output unit 30 includes conductors (hereinafter also referred to as detection electrodes) 31A and 31B, FETs (Field Effect Transistors) 32A and 32B, and a differential amplifier 33 for detecting a potential in a specific region.

  The detection electrodes 31A and 31B have the same shape and the same size, and are arranged at positions that are specific regions. The arrangement positions of the detection electrodes 31A and 31B in this embodiment are point-symmetric with respect to the center of gravity of the four electrodes 21A to 21D.

  The gates of the FETs 32A and 32B are connected to the detection electrodes 31A and 31B. The drains of the FETs 32A and 32B are connected to the differential amplifier 33, and the sources are connected to a portion to be grounded.

  When potential fluctuations occur in the detection electrodes 31A and 31B, the potential fluctuations are detected as current fluctuations between the drain and source in the FETs 32A and 32B, respectively, and the difference between these detection results is amplified in the differential amplifier 33.

  Therefore, the influence of the force field in the external field on the electric field formed by the electrodes 21A to 21D is canceled, and as a result, the fluctuation of the output of the differential amplifier 33 is suppressed, and the DC state or a state close thereto is obtained.

  In this way, the reference potential output unit 30 regards the signal as 0 [V / m] by outputting the difference between the signals obtained from the detection electrodes 31A and 31B arranged in the singular region as a reference potential signal. Is kept below an acceptable value.

  In addition, it has been confirmed by experiments of the present inventors that the drift generated in the singular region can be made almost 0 [V / m] by providing the reference potential output unit 30.

  The shielding unit 40 is a conductive box that houses the circuit power supply unit 10, the singular region forming unit 20, and the reference potential output unit 30, and shields the influence of an external force field on each unit 10, 20, 30. The shielding unit 40 is a common ground target for the circuit power supply unit 10, the singular region forming unit 20, and the reference potential output unit 30.

  In the case of this embodiment, a conductive plate (hereinafter also referred to as a shielding plate) 41 that partitions a space surrounded by the shielding portion 40 into two spaces is provided inside the shielding portion 40. The electrodes 21A to 21D and the detection electrodes 31A and 31B are provided in one space with the shielding plate 41 as a boundary, and the circuit power supply unit 10, the signal oscillation source 22, the output adjustment unit 23, the FETs 32A and 32B, and the other space A differential amplifier 33 is provided.

  Therefore, in this shielding part 40, the influence of the radiation noise etc. which arise from the electronic component in the reference electric potential generator 1 with respect to a specific area | region is reduced significantly by the shielding board 41. FIG. As a result, the potential fluctuation obtained as the difference between the signals from the detection electrodes 31A and 31B arranged in the specific region is significantly suppressed as compared with the case where the shielding plate 41 is not provided.

  Further, in this shielding part 40, for example, an insulating spacer such as an acrylic plate (hereinafter also referred to as an insulating spacer) 42 is used, and is larger than the distance from which the quasi-electrostatic field dominant space should be formed from the inner wall of the shielding part 40. Electrodes 21A to 21D are arranged at a distance.

  Therefore, the coupling between the other parts outside the shielding part 40 and the electrodes 21A to 21D is greatly reduced as compared with the case where the insulating spacer 42 is not used, and the signals from the detection electrodes 31A and 31B arranged in the singular region are transmitted. The fluctuation of the potential obtained as the difference is greatly suppressed.

(3) Other Embodiments In the above-described embodiments, the adjacent polarities are reversed with respect to the electrodes 21A to 21D arranged at the positions corresponding to the vertices of the squares whose center of gravity is the position to be the reference. An electrode structure (planar quadrupole structure) that gives a signal of the same level as the relationship is adopted. However, the electrode structure is not limited to this embodiment.

  For example, the same level where the adjacent polarities are inverted with respect to the electrodes arranged at the positions corresponding to the vertices of the positive 2n (n is an even number of 2 or more) square with the position to be the reference as the center of gravity. It is possible to apply an electrode structure (that is, a planar 2n-pole structure) that gives the above signal.

  Here, FIG. 10 shows the relationship between the electrode position in the planar hexapole structure (n = 3) and the planar octupole structure (n = 4) and the charge applied to the electrode. FIG. 11 shows the relationship between the distance from the singular region (the center of gravity of a regular 2n square on which the reference electrode is arranged) and the potential in the planar quadrupole structure (n = 2), the planar hexapole structure, and the planar octapole structure. Show.

  As can be seen from FIG. 11, in the planar 2n-pole structure, as the electrode structure increases, the degree of potential attenuation near the center of gravity of the regular 2n square increases. This is because if the distance from the center of gravity of the regular 2n square to each vertex is constant, the distance between adjacent charges (that is, the length of the side of the polygon) decreases as n increases, and the electric field generated from the electrode. This is because the efficiency of canceling out is improved. Therefore, as the electrode structure having a large n is adopted as the planar 2n-pole structure, the degree of suppressing the potential fluctuation in the specific region can be increased.

  In addition, for example, for an electrode arranged at a position corresponding to each vertex of a regular polyhedron other than a regular tetrahedron whose center of gravity is a position to be a reference, or a quasi-regular polyhedron in which the shape of all surfaces is a 2n square Thus, an electrode structure (that is, a three-dimensional multipolar structure) that provides a signal of the same level that is a relationship in which adjacent polarities are inverted can be applied. FIG. 12 shows the relationship between the electrode position and the charge applied to the electrode in a three-dimensional octapole structure (regular hexahedron) and a three-dimensional 14-pole structure (truncated octahedron).

  The electrode structure may be other than those described above. In short, an electrode structure in which the same level of charge is applied so that the polarities of adjacent electrodes are directly opposed to m (m is an even number of 4 or more) electrodes that are rotationally symmetric around a position to be a reference. If it is. Refer to Japanese Patent Application No. 2007-56954 already proposed by the present inventor for details of the multipolar structure itself.

  In the above-described embodiment, the alternating signal is applied to the electrodes 21A to 21D, but a DC signal may be used. In short, it is only necessary to apply the same level of charge with the opposite polarity to the adjacent electrodes.

  In the above-described embodiment, the arrangement positions of the detection electrodes 31A and 31B are point-symmetric with respect to the center of gravity of the four electrodes 21A to 21D. However, the arrangement positions of the detection electrodes 31A and 31B may not be symmetrical. In short, the detection electrodes 31A and 31B only have to be arranged in the specific region.

  In the above-described embodiment, two detection electrodes 31A and 31B are arranged in the specific region. However, the number of detection electrodes 31A and 31B to be arranged in the specific region is not limited to two. For example, a form in which four detection electrodes are arranged for a specific region can be applied.

  In this embodiment, as shown in FIG. 13, the detection electrodes 51A, 51B, 52A, and 52B have the same shape and size, and the arrangement positions of the detection electrodes 51A, 51B, 52A, and 52B are the positions of the four electrodes 21A to 21D. It is point-symmetric with respect to the center of gravity. The arrangement positions of the detection electrodes 51A, 51B, 52A, and 52B are such that a line segment that connects the centroids of the detection electrodes 51A and 51B and a line segment that connects the centroids of the detection electrodes 52A and 52B are orthogonal to each other. Are the same length.

  These detection electrodes 51A, 51B, 52A, and 52B are connected to the gates of FETs 61 to 64 to be associated. The drains of the FETs 61 and 62 are connected to the differential amplifier 71, and the drains of the FETs 63 and 64 are connected to the differential amplifier 72. The output terminal of the differential amplifier 71 and the output terminal of the differential amplifier 72 are connected to the input terminal of the differential amplifier 73.

  When a potential variation occurs in the singular region, the potential variation is detected by two sets of detection electrodes 51A, 51B, 52A, and 52B arranged in an orthogonal state, and the difference between the detection results in each set corresponds to 1 Amplified by differential amplifiers 71 and 72 at the stage. Further, the difference between the amplification results of the differential amplifiers 71 and 72 is further amplified by the second-stage differential amplifier 73. Therefore, the output fluctuation from the differential amplifier 73 is further suppressed as compared with the embodiment shown in FIG.

  In addition, the number of detection electrodes should just be a number which will be 2x (x is an integer) on condition that it arrange | positions to a specific area | region. However, from the viewpoint of equalization, it is preferable that the number of detection electrodes is a power of 2, and these are arranged in a symmetrical relationship with the position to be a reference as the center of gravity.

  In addition, the differential amplifier connects a number of 2 × −1 in a plurality of stages using a tournament connection pattern. Of these multiple stages of differential amplifiers, the signal output from the final stage differential amplifier is a signal of the reference potential. In this way, it is possible to achieve an effect that is more than the same effect as that of the above-described embodiment.

  In the above-described embodiment, the shapes of the electrodes 21A to 21D and the detection electrodes 31A, 31B, 51A, 51B, 52A, 52B are square. However, the shape of these electrodes is not limited to this embodiment, and any shape can be adopted. The sizes of the electrodes 21A to 21D and the detection electrodes 31A, 31B, 51A, 51B, 52A, and 52B are not limited to the illustrated sizes.

  In the above-described embodiment, the electrodes 21A to 21D and the detection electrodes 31A, 31B, 51A, 51B, 52A, and 52B are arranged on the same plane.

  In the above embodiment, the grounding object common to the circuit power supply unit 10, the singular region forming unit 20, and the reference potential output unit 30 is the shielding unit 40. However, instead of the shielding unit 40, the shielding plate 41 may be used. Good.

  The present invention can be used in, for example, agriculture, forestry, fishery, mining, construction, manufacturing, electrical, information and communication, transportation, or pharmaceutical industries, and of course, can be widely used in all other industries. is there.

DESCRIPTION OF SYMBOLS 1 ... Reference potential generator 10 ... Circuit power supply part 20 ... Singular area formation part 21A-21D ... Electrode 22 ... Signal oscillation source 23 ... Output adjustment part 30 ... Reference potential Output unit 31A, 31B, 51A, 51B, 52A, 52B ... detection electrode 32A, 32B ... FET
33, 71, 72, 73 ... differential amplifier 40 ... shielding part 41 ... shielding plate 42 ... insulating spacer

Claims (8)

M electrodes (m is an even number equal to or greater than 4) arranged in rotational symmetry around a position to be a reference;
Applying means for applying an electric charge having an intensity in a vicinity range including the position to be the reference to a value less than a predetermined value to the m electrodes;
A plurality of conductors arranged in the range;
An amplifying unit that amplifies a difference between signals obtained from the plurality of conductors. There are x conductors (x is an integer),
2. The reference potential generating device according to claim 1, wherein the amplifying unit includes 2 × −1 differential amplifiers connected in a plurality of stages with a tournament connection pattern. The reference potential generating device according to claim 2, wherein the conductor is a power of 2 and is arranged in the range in a symmetrical relationship with the position to be the reference as a center of gravity. A conductive box housing the m electrodes, the applying means, the plurality of conductors, and the amplifying means;
A conductive plate that partitions the space of the box,
The m number of electrodes and the plurality of conductors are arranged in one space partitioned by the plate, and the applying means and the amplifying means are arranged in the other space. Item 3. The reference potential generating device according to Item 2. The reference potential generating device according to claim 4, wherein the box or the plate is a common grounding object for the applying unit and the amplifying unit. The m electrodes are separated from each other by a distance larger than a distance formed as a space in which the quasi-electrostatic field has a greater intensity than other electric fields among the radiated electric field, induction electromagnetic field, and quasi-electrostatic field generated from the electrodes. The reference potential generating device according to claim 1, wherein the reference potential generating device is arranged. 6. The m electrodes are arranged at positions that are vertices of a regular 2n square (n is an even number of 2 or more) with the position to be the reference as a center of gravity. A reference potential generating device according to claim 1. The application means includes
A signal is applied to one of the adjacent electrodes among the m electrodes, and a signal whose phase is shifted by 180 degrees is applied to the other of the adjacent electrodes. The reference potential generating device according to any one of claims 1 to 5.