KR20190076478A - Apparatus and Method for Sensing of Human Body Using Coil - Google Patents

Abstract

According to an embodiment of the present disclosure, an apparatus for detecting a human body can include a detection part configured to simultaneously form capacitance and inductance, a first sensing part which is electrically connected to the detection pat in a first detection mode and detects whether an object approaches based on a change in capacitance; and a second detection part which is electrically connected to the detection part in a second detection mode when the first detection part detects the approach of the object and determines the type of the approaching object based on a change in impedance. It is possible to improve the accuracy of detecting the human body.

Description

[0001] APPARATUS AND METHOD FOR DETECTING HUMAN BODY USING COIL [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an object detecting apparatus, and more particularly, to a human body detecting apparatus and method using a coil.

Various types of sensors are used to detect objects. For example, the sensor device can measure temperature, pressure, humidity, sound, gas flow rate, speed, and vibration according to the object to be sensed, and it can be varied by optical method, ultrasonic method, . ≪ / RTI >

The capacitance type sensor device detects an object by using the principle that the capacitance between the detection electrode provided on the sensor device and the ground increases when the detected object approaches or touches the sensor device.

The capacitance type sensor device is capable of detecting any object having a dielectric constant, is strong in noise immunity, has a wide use field due to its simple configuration and low manufacturing cost.

However, since the capacitance type sensor device detects only the change of the capacitance, it reacts when the change of the capacitance is exceeded by a certain level of access by an object. Therefore, the possibility of detection error can not be excluded when applied to a specific object, for example, a system designed to respond to a human body.

Embodiments of the present technology can provide a human body sensing apparatus and method using a coil capable of distinguishing between a conductive object and a human body.

Embodiments of the present technology can provide a human body sensing apparatus and method using a coil that can improve the accuracy of human body sensing.

A human body sensing apparatus using a coil according to an embodiment of the present invention includes: a detector capable of simultaneously forming a capacitance and an inductance; A first sensing unit electrically connected to the detection unit in a first sensing mode to sense whether an arbitrary object is approaching based on a capacitance change; And a second sensing unit that is electrically connected to the detection unit in the second sensing mode to determine the type of the object based on the impedance change when the sensing unit senses that an object is approaching .

A method for detecting a human body using a coil according to an embodiment of the present invention includes a detection unit capable of simultaneously forming a capacitance and an inductance, the method comprising: setting a first sensing mode; Sensing whether an object has approached the detection unit based on a change in capacitance of the detection unit in the first sensing mode; Switching to a second sensing mode when an object is detected as approaching in the first sensing mode; And determining a type of the object based on the impedance change of the detection unit in the second sensing mode.

According to this technology, since the object is detected by the hybrid method which detects both the capacitance change and the induction capacitance change, the detection accuracy for the object to be detected is greatly improved. Accordingly, it is possible to distinguish whether the approached object is a human body or an electrically conductive object, so that the operational reliability of a system designed to operate in response to a human body can be improved.

1 is a block diagram of a human body detecting apparatus using a coil according to an embodiment.
2 is a configuration diagram of a detection unit according to an embodiment.
3A and 3B are simplified circuit diagrams of a detection unit according to an embodiment.
4 is a diagram for explaining a relationship between a capacitance change amount and an induced capacitance change amount according to an approach of an object.
5 to 8 are block diagrams of a human body sensing apparatus according to embodiments.
9A and 9B are diagrams for explaining the sensing method in the first sensing mode.
10 is a configuration diagram of a detection unit according to the embodiments.
11 is a flowchart illustrating a human body detection method according to an embodiment.

Hereinafter, embodiments of the present technology will be described in more detail with reference to the accompanying drawings.

1 is a block diagram of a human body detecting apparatus using a coil according to an embodiment.

Referring to FIG. 1, a human body sensing apparatus 10 according to an embodiment includes a controller 100, a detector 110, a switching unit 120, a first sensing unit 130, and a second sensing unit 140 . ≪ / RTI >

The control unit 100 may be configured to control the entire operation of the human body sensing apparatus 10.

The detection unit 110 is a part where substantial object approaching or contacting occurs, and can be configured using a structure capable of simultaneously forming a capacitance and an inductance. In one embodiment, the detector 110 may comprise a coil.

The switching unit 120 may electrically connect the detection unit 110 and the first sensing unit 130 under the control of the controller 100 in the first sensing mode. The switching unit 120 may be configured to electrically connect the detection unit 110 and the second sensing unit 140 under the control of the controller 100 in the second sensing mode.

In one embodiment, the first sensing mode may be referred to as a proximity mode, or a capacitive mode, or a capacitance mode. In addition, the second sensing mode may be an object determination mode, an inductive capacity mode, or an inductance mode. Or an impedance mode.

In the first sensing mode, the first sensing unit 130 may be configured to determine proximity of an object based on a change in capacitance of the sensing unit 110 as the object approaches or touches the sensing unit 110.

When it is determined by the first sensing unit 130 that the object is close, the controller 100 operates the human body sensing apparatus 10 in the second sensing mode. That is, the control unit 100 controls the switching unit 120 so that the detection unit 110 and the second sensing unit 140 are electrically connected.

In the second sensing mode, the second sensing unit 140 may be configured to determine whether an object in proximity to or in contact with the sensing unit 110 is a human body.

As described above, the human body sensing apparatus 10 according to the present invention uses an element, for example, a coil, whose inductance and capacitance change in accordance with the proximity or contact of an object, as the detection unit 110.

When the first sensing unit 130 is operated in the first sensing mode and it is detected that the capacitance is changed, it is determined that an arbitrary object is approaching. Thereafter, the mode is switched to the second sensing mode, and it is determined whether the object to be inspected is the human body based on the capacitance change amount and the inductance variation amount.

As described above, in the present technology, the change amount of the inductance as well as the change in the capacitance can be simultaneously detected. As a result, it is possible to distinguish between a conductive object and a human body, thereby preventing a malfunction in a system that is made to respond to a human body.

That is, since the capacitance change amount and the inductance change amount will be different depending on the characteristics of the object approaching the human body sensing apparatus 10, it is possible to detect whether or not the approaching object is human.

2 is a configuration diagram of a detection unit according to an embodiment.

The detection unit 110 of the human body sensing apparatus 10 according to an embodiment of the present invention may be configured to simultaneously form a capacitance and an inductance. For this purpose, the detection unit 110 may be composed of a helical coil. The helical coil can be made of wire or PCB, and can have a two-dimensional or three-dimensional structure.

FIG. 2 is a plan view of a two-dimensional spiral coil according to an embodiment of the present invention.

3A and 3B are simplified circuit diagrams of a detection unit according to an embodiment.

Fig. 3A schematically shows parasitic capacitance components present in the two-dimensional helical coil shown in Fig. 2, and Fig. 3B is an equivalent circuit diagram of Fig. 3A.

As can be seen from FIGS. 3A and 3B, in the case of the helical coil, inductance and capacitance can be formed at the same time, so that it can be adopted as the detection unit 110 of the human body sensing apparatus 10 according to the present invention.

In order to detect changes in capacitance and inductance, a self-oscillator using an LC circuit is configured to detect a change in oscillation frequency, or a method of detecting a change in amplitude and phase by applying a reference signal having a constant frequency to an LC circuit Branching methods can be used.

The frequency of the self-oscillator using the LC circuit is determined by the values of L and C.

In the oscillator using the LC circuit, the L component includes the helical coil. When an object is adjacent to the detection unit 110 to increase the capacitance and increase the inductance, the oscillation frequency f ₀ is low And the oscillation frequency f ₀ is increased when the inductance is decreased.

Generally, the inductance decreases when an object is in a condition where an eddy current is formed adjacent to the human body sensing device 10, and the inductance increases when ferrite magnetic substances are adjacent to each other. On the other hand, if there is no reduction in charge due to leakage current, capacitance will increase when an object is adjacent.

Therefore, based on the inductance change amount and the capacitance change amount, it is possible to detect whether the adjacent object is a conductor or a bank, or both the capacitance component and the inductance component, and the degree of the degree.

As an example, it is assumed that an arbitrary object having a capacitance is brought close to the detection unit 110.

In the case of a conventional capacitance sensor, if an object is brought close to the object, the frequency (f ₀ ) of the oscillator constituting the sensing circuit will be reduced only by the increase (+ ΔC) of the capacitance. Alternatively, when an arbitrary object is brought close to the human body sensing apparatus 10 proposed in the present technology, the characteristics of the detector 110, the value of the capacitor C constituting the oscillator together with the detector 110, The capacitance increase (+ DELTA C) and the inductance decrease (-DELTA L) are different from each other, and thus, the variation amounts of the oscillation frequency are different from each other. Here, the characteristic of the detection unit 110 may include magnitude, inductance value, shape, and the like.

4 is a diagram for explaining a relationship between a capacitance change amount and an induced capacitance change amount according to an approach of an object.

4, when the inductance decrease (-ΔL) is larger than the capacitance increase (+ ΔC) due to any object adjacent to the detector 110, the oscillation frequency of the oscillator increases (f ₀ + Δf). On the other hand, when the capacitance increase (+ ΔC) is larger than the inductance decrease (-ΔL), the oscillation frequency of the oscillator decreases (f ₀ -Δf).

Therefore, it is obvious that the oscillation frequency (f ₀ ) will decrease if an object having a low conductivity and a high dielectric constant, such as a human body, is adjacent to the detection unit 110.

5 to 8 are block diagrams of a human body sensing apparatus according to embodiments. The operation of the human body sensing apparatus 10 for sensing a human body in a hybrid manner will be described in more detail with reference to FIGS. 5 to 8. FIG.

5 and 6 are exemplary circuits of the human body sensing apparatuses 10-1 and 10-2 using the LC parallel resonance oscillator.

The human body sensing apparatus 10-1 of FIG. 5 is configured to be able to determine whether the human body is approaching or not based on the change amount of the oscillation frequency.

5, the switching unit 120 includes a switch operating in response to a switch control signal S ₁ , a switch operating in response to a third switch control signal S ₃ , and an inverted third switch control signal / S ₃ ). ≪ / RTI >

In the first detection mode, the control unit 110 is inverted, the third switch control signal (/ S ₃₎ in response to turn-on at least one or more switches to be driven in and the first switch control signal (S ₁₎ and the third switch control signal The switch operating in response to the third sensing signal S ₃ is turned off so that the detection unit 110 and the first sensing unit 130 are electrically connected.

That is, the detection unit 110 and the second sensing unit 140 are disconnected and the detection unit 110 is used as a capacitance sensing pad to determine whether the object is in proximity to the object.

The first sensing unit 130 may be configured to sense a change in capacitance according to an arbitrary object adjacent to the sensing unit 110. In one embodiment, the first sensing unit 130 may be configured to measure the capacitance change as well as the capacitance value according to the proximity of any object.

In the second sensing mode, the controller 110 turns on the switch driven in response to the first switch control signal S ₁ and the third switch control signal S ₃ and outputs the inverted third switch control signal / S ₃ To turn off the switch to electrically connect the detection unit 110 and the second sensing unit 140.

The second sensing unit 140 may be configured to determine whether the human body is approaching based on the inductance variation amount depending on the characteristics of the object approaching the detection unit 110. [

In an embodiment, the second sensing unit 140 may include a frequency measuring unit 141, an inductive capacitance measuring unit 143, and a determining unit 145.

The frequency measuring unit 141 may be configured to detect the oscillation frequency f _{0 that} varies with the change in inductance of the detecting unit 110, including the capacitor C, the oscillating circuit 1411, and the amplifying circuit 1413 .

이므로, 유도 용량 측정부(143)는 주파수 측정부(141)에서 측정된 발진 주파수(f₀)와 제 1 감지부(130)에서 검출한 정전용량값에 기초하여 유도용량값을 검출하도록 구성될 수 있다.The oscillation frequency of the resonant circuit is

The inductive capacitance measuring unit 143 is configured to detect the inductance capacitance value based on the oscillation frequency f ₀ measured by the frequency measuring unit 141 and the capacitance value detected by the first sensing unit 130 .

The determination unit 145 may be configured to determine whether an adjacent object is a human body based on the inductance measured by the inductive capacitance measurement unit 143 and generate an output signal OUT. The determination unit 145 may determine whether the human body is in proximity to the inductive capacitance measured by the inductive capacitance measuring unit 143 based on whether the inductive capacitance measured by the inductive capacitance measuring unit 143 is greater or less than the inductive capacitance value inherent to the detecting unit 110. [

However, it may happen that the oscillation frequency f ₀ does not fluctuate because the capacitance increase (+ C) and the inductance decrease (-ΔL) are the same.

In the LC parallel resonance circuit, the impedance due to L and C becomes small even if the capacitance increase (+ ΔC) and the inductance decrease (-ΔL) are the same, so the output voltage of the oscillation signal decreases. When the capacitance increase (+ ΔC) and the inductance decrease (-ΔL) are the same in the LC series resonant circuit, the impedance due to L and C becomes small and the output voltage of the oscillation signal decreases.

Therefore, even when the capacitance increase (+ C) and the inductance decrease (-ΔL) are the same, the object approaching based on the characteristic (amplitude, phase) of the oscillation signal can be discriminated.

The human body detecting apparatus 10-2 of FIG. 6 can determine whether the human body is approaching based on the magnitude of the oscillation signal when the oscillation frequency does not change.

The human sensing apparatus 10-2 shown in FIG. 6 has substantially the same configuration as that of the human sensing apparatus 10-1 shown in FIG. 5 except for the configuration of the second sensing unit 140-1.

The second sensing unit 140-1 shown in FIG. 6 may include a phase / amplitude detector 147 in addition to the frequency measuring unit 141, the inductive capacitance measuring unit 143, and the determining unit 145.

The phase / amplitude detection unit 147 may include a signal source 1471, a path setting switch S ₂ , and an impedance measurement unit 1473.

In the first sensing mode, the third switch bar / S ₃ of the switching unit 120 is turned on and the first switch S ₁ and the third switch S ₃ are turned off, and the phase / amplitude detector 147 ) routing switch (S ₂₎ is such that the turn-off by detector 110 with a first sensing part 130 is electrically connected to each other.

That is, the detection unit 110 and the second sensing unit 140 are disconnected and the detection unit 110 is used as a capacitance sensing pad to determine whether the object is in proximity to the object.

The first sensing unit 130 may be configured to sense a change in capacitance according to an arbitrary object adjacent to the sensing unit 110. In one embodiment, the first sensing unit 130 may be configured to measure the capacitance change as well as the capacitance value according to the proximity of any object.

When the first sensing unit 130 detects the approach of the object and switches to the second sensing mode, the third switch bar / S ₃ is turned off. When the first switch S ₁ and the third switch S ₃ are turned on or the path setting switch S ₂ of the phase / amplitude detector 147 is turned on, (140) are electrically connected to each other.

In the second sensing mode, when the first switch S ₁ and the third switch S ₃ are turned on, the same operation as the human body sensing apparatus 10-1 shown in FIG. 5 can be performed.

In the second sensing mode, the amplitude and / or phase of the oscillation signal can be measured when the path setting switch S ₂ is turned on along with the first switch S ₁ and the third switch S ₃ , It is possible to judge whether or not the human body is approaching.

For example, when the capacitance increase (+ C) and the inductance decrease (-ΔL) are the same and there is no fluctuation in the oscillation frequency, the phase / amplitude detector 147 is operated to set a fixed frequency of a constant magnitude in the signal source 1471 the signal that has been applied, at this time, impedance can be measured through a portion (1473) detecting an amplitude (Av) and / or phase (Ф o).

Then, the determination unit 145 can determine whether or not the human body is approaching based on the amplitude and / or the phase value.

7 and 8 are exemplary circuits of the phosphor sensing apparatuses 10-3 and 10-4 using a pi -type LC resonant oscillator.

The human body sensing apparatus 10-3 shown in Fig. 7 is different from the human body sensing apparatus 10-3 shown in Fig. 5 except that the coil constituting the detection unit 110 constitutes a pi- (10-1).

The human body sensing apparatus 10-4 shown in FIG. 8 is different from the human body sensing apparatus 10-4 shown in FIG. 6 except that the coils constituting the detection unit 110 constitute a pi-shaped oscillator together with the capacitors C1 and C2. (10-2).

9A and 9B are diagrams for explaining the sensing method in the first sensing mode.

The human body sensing apparatus 10 shown in FIGS. 5 to 8 can detect the electrostatic capacitance by setting the detection unit 110 as a sensing pad of the electrostatic capacitance sensor device in the first sensing mode.

In one embodiment, as shown in FIG. 9A, the first and second sensing units 110 and 130, which operate in response to the inverted third switch control signal / S ₃ , Both ends of the detection unit 110 can be connected to the first sensing unit 130 by turning on the switches SW1 and SW2 (a). 9A is a conceptual diagram of (a) and (c) shows an equivalent circuit diagram. That is, it is possible to detect the capacitance change of the detection unit 110 while both ends of the detection unit 110 are connected to the first sensing unit 130.

In one embodiment, as shown in FIG. 9B, only one terminal of the detection unit 110 may be connected to the first sensing unit 130 to detect a change in capacitance of the detection unit 110.

For example, the first switch SW1 is turned on and the second switch SW2 is turned on as shown in (a) of FIG. 9, and the switch SW1 or SW2 for connecting the detection unit 110 and the first sensing unit 130 2 switch SW2 can detect the electrostatic capacity in the open state. 9B is a conceptual diagram of (a) and (c) is an equivalent circuit diagram.

In this way, in the first sensing mode, the switching unit 120 can be controlled to convert the human body sensing apparatus 10 into the form of a capacitance sensor. If a change in capacitance is detected in this state, it is determined that an arbitrary object has approached, and the switching unit 120 is controlled to switch to the second sensing mode to distinguish the approaching object. In the second sensing mode, a frequency and / or magnitude and / or phase indicating the characteristic impedance of the object are sensed to determine whether the object is an object to be sensed.

10 is a configuration diagram of a detection unit according to the embodiments.

It is effective to determine that the size of the detection unit 110 that can be composed of the helical coil is proportional to the size of the object to be sensed and that the larger the size of the detection unit 110, to be.

Also, when the inductance value of the detection unit 110 is increased on the basis of a certain oscillation frequency, the parasitic capacitance increases in proportion thereto, and the C value constituting the resonance circuit is set to be small. On the other hand, The smaller the parasitic capacitance, the larger the value of C constituting the resonant circuit is set.

When the inductance value is large, a strong magnetic field is formed. In this case, the permittivity is relatively high, such as silicon or a human body, but is relatively sensitive to a large conductive object such as a metal plate.

If the inductance value is small, the magnetic field is weakly formed, and as the conductive object approaches, a reduction in inductance becomes a main factor for varying the oscillation frequency up to a certain distance. As a result.

Therefore, if the inductance value of the detection unit 110 is high, the frequency becomes gradually higher as the object approaches, whereas when the inductance value of the detection unit 110 is small, until the object approaches a certain distance If the oscillation frequency increases and approaches beyond a certain point, the oscillation frequency decreases again due to an increase in capacitance rather than a decrease in inductance.

On the other hand, even if the inductance value of the detection unit 110 is the same, the detection range may be different depending on the shape thereof. For example, a two-dimensional helical coil implemented on a plane and a three-dimensional helical coil embodied on a three-dimensional basis can be compared as an example. The two-dimensional helical coil has a large detection area while the sensing distance is short, and the sensing area of the three-dimensional helical coil is narrow, but the magnetic flux density is concentrated and the sensing distance may be long.

Furthermore, if the distance between the conductors constituting the coil serving as the detection unit 110 is widened, the parasitic capacitance is reduced and the capacitive change can be sensitively responded.

Therefore, the present invention can be applied to various fields by adjusting the size, shape, and inductance of the detection unit 110 and the C value of the oscillation circuit according to the characteristics (size, shape, material, etc.) of the object to be sensed.

As shown in FIG. 10, not only the human body but also various objects can be detected using the principle of the human body sensing apparatus 10 according to the present invention, and the inductance value can be appropriately set according to the type of the object to be detected.

Referring to FIG. 10, a two-dimensional helical coil can be used as a sensing unit for a touch switch (a), a large area level sensing device (c), and a large area sensing object (e).

In another embodiment, the touch switch responsive to human contact can use a spring coil b or a conical coil g with tension or a cylindrical coil h with tension. A three-dimensional helical coil can be used for remote water level detection (d) and foreign substance detection inside the container (f).

11 is a flowchart illustrating a human body detection method according to an embodiment.

The human body sensing method using the human body sensing devices 10, 10-1, 10-2, 10-3, and 10-4 shown in FIGS. 1 and 5 to 8 will be described with reference to FIG.

The human body detecting devices 10, 10-1, 10-2, 10-3, and 10-4 may be initially set to the first sensing mode and operate (S101).

In the first sensing mode, the detection unit 110 maintains a connection state with the first sensing unit 130 and is not connected to the second sensing unit 140. [ Therefore, the detection unit 110 acts like the sensing pad of the capacitance sensor.

In the first sensing mode, the first sensing unit 130 determines whether an arbitrary object is in proximity with the capacitance depending on whether the capacitance is changed (S103).

If it is determined in step S103 that an arbitrary object is approaching (S103-Y), the human body sensing apparatus 10, 10-1, 10-2, 10-3, and 10-4 switches to the second sensing mode (S105). If an arbitrary object is not approaching (S103-N), the first sensing mode is maintained (S101).

When an arbitrary object approaches and switches to the second sensing mode, the second sensing unit 140 determines the frequency and the phase of the object from the oscillation signal output from the resonance circuit formed by the sensing unit 110, / Or amplitude and / or phase.

Then, based on the value detected in step S107, it is determined whether the object to be accessed is a human body (S109). If it is a human body, the second sensing mode is maintained (S101-Y), and if it is not a human body (S109-N), the first sensing mode can be switched (S101).

In one embodiment, the first sensing unit 130 of the human body sensing apparatus 10, 10-1, 10-2, 10-3, and 10-4 determines that an arbitrary object approaches in step S103, The capacitance value can be detected.

The second sensing unit 140 may calculate the inductance value based on the frequency measurement value of the oscillation circuit and the capacitance value detected by the first sensing unit 130 in step S107. In addition, in step S109, it is possible to determine whether or not the human body is approaching based on the inductance value calculated in step S107.

If it is determined that an arbitrary object is close but the oscillation frequency does not fluctuate, the amplitude and phase of the oscillation signal can be measured in step S108 and the human body can be determined on the basis of the amplitude and phase in step 09D have.

Although the human body sensing method of sensing the capacitance change in the first sensing mode and determining the type of object approaching based on the impedance change according to the inductance change in the second sensing mode has been described above, Do not.

For example, in the first sensing mode, it is possible to detect a change in inductance to determine whether an arbitrary object has approached. In one embodiment, the oscillation frequency of the oscillation signal according to the inductance change can be measured in the first sensing mode. If it is determined that an arbitrary object is approaching, it switches to the second sensing mode and detects the electrostatic capacity according to the characteristics of the approaching object. The inductance value may be extracted according to the oscillation frequency measured in the first sensing mode and the capacitance value measured in the second sensing mode to determine the type of the transferred object.

Thus, those skilled in the art will appreciate that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

10, 10-1, 10-2, 10-3, 10-4: Human body detection device
110:
120:
130:
140: second sensing unit

Claims (10)

A detector capable of simultaneously forming a capacitance and an inductance;
A first sensing unit electrically connected to the detection unit in a first sensing mode to sense whether an arbitrary object is approaching based on a capacitance change; And
A second sensing unit electrically connected to the sensing unit in a second sensing mode to determine the type of the object based on the impedance change when the sensing unit senses that an object approaches;
And a human body detecting device. The method according to claim 1,
Wherein the detection unit is configured to include a coil. The method according to claim 1,
Wherein the detection unit is configured to include a helical coil. The method according to claim 1,
Wherein the second sensing unit is configured to detect a frequency change from an oscillating signal of a resonant circuit including the detecting unit. The method according to claim 1,
And the second sensing unit is configured to detect the amplitude and / or phase from the oscillating signal of the resonant circuit including the detecting unit. A human body detecting method of a human body detecting device including a detecting part capable of simultaneously forming a capacitance and an inductance,
Setting a first sensing mode;
Sensing whether an object has approached the detection unit based on a change in capacitance of the detection unit in the first sensing mode;
Switching to a second sensing mode when an object is detected as approaching in the first sensing mode; And
Determining a type of an approaching object based on a change in impedance of the detection unit in the second sensing mode;
Wherein the human body detection method comprises: The method according to claim 6,
Wherein the detection unit is configured to include a coil. The method according to claim 6,
Wherein the detecting unit is configured to include a helical coil. The method according to claim 6,
Wherein the second sensing mode is configured to detect a frequency change from an oscillation signal of a resonant circuit including the detection unit. The method according to claim 6,
Wherein the second sensing mode is configured to include detecting amplitude and / or phase from an oscillating signal of a resonant circuit including the detecting unit.

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