JP2012122726A - Proximity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a proximity sensor that can operate with low electric power and highly accurately detect an object to be detected.SOLUTION: A proximity sensor 1a comprises an oscillator 2, a transmission antenna 3 that radiates an alternating current signal Ea based on a signal from the oscillator 2, a receiving antenna 4 that receives an alternating current signal Eb, and a resonator 5 connected to the receiving antenna 4. The resonator 5 is constructed using, for example, a crystal oscillator. The proximity sensor 1a also comprises a buffer 6 and a resistor 7 that connect the output of the oscillator 2 and one end of the resonator 5. The resonator 5 is pre-excited at the oscillatory frequency of the oscillator 2. The proximity sensor 1a also comprises an amplifier 8 that amplifies the output of the resonator 5, and a phase detector 9 that performs phase detection of a signal received by the receiving antenna 4 using an output signal from the oscillator 2. The proximity sensor 1a also comprises an LPF 10 that smooths the output from the phase detector 9, and an output terminal 11.

Description

  The present invention relates to a proximity sensor that detects the position of an object.

  Conventionally, it has so-called proximity that has two antennas, generates an alternating electromagnetic field from one antenna, receives it by the other antenna, and detects the phase of the received signal to detect the position and movement of the object. Sensors have been proposed (see, for example, Patent Documents 1 and 2).

  FIG. 20 is a circuit diagram showing a configuration of a conventional proximity sensor described in Patent Documents 1 and 2. In the conventional proximity sensor, the AC signal Ea is transmitted from the transmission antenna 103 based on the signal of the oscillator 102, and the AC signal Eb is taken into the circuit by the reception antenna 104. In the conventional proximity sensor, the signal taken into the circuit by the receiving antenna 104 is directly amplified by the amplifier 108 and then detected by the signal of the oscillator 102 by the phase detector 109.

  Furthermore, the conventional proximity sensor converts the output of the phase detector 109 into a direct current by the LPF 110 and outputs the change in the electromagnetic wave in the inspection region from the output terminal 111 as the change in the direct current voltage.

JP 2006-275629 A (page 3-5, FIG. 1) JP 2007-171031 A (page 4-6, FIG. 1)

  However, the prior art has the following problems. Since the phenomenon described above is very weak, a sufficient gain cannot be obtained unless the frequency is high due to the characteristics of the antenna or the interaction between the object to be detected and the radio wave. Therefore, in order to obtain sufficient detection sensitivity as a proximity sensor, it is necessary to generate a signal with a very high frequency from the oscillator 102 in both methods of Patent Documents 1 and 2. In Patent Document 1 conscious of low frequencies, a high frequency of the lowest HF band is assumed, and in Patent Document 2, a GHz band is assumed.

  On the other hand, in order to generate a high-frequency signal, a large amount of energy must be input, and there is a problem that a circuit configuration with a large power consumption for dealing with the high-frequency signal must be used for the entire circuit.

  Accordingly, an object of the present invention is to solve the above-described problems, and to provide a proximity sensor that operates with low power and can detect a test object with high accuracy.

  In order to solve the above-described problems and achieve the object, the proximity sensor of the present invention adopts the following configuration.

  A proximity sensor according to the present invention includes an AC signal generation source, a transmission antenna that transmits radio waves based on signals from the AC signal generation source, a reception antenna that receives radio waves, a resonant element connected to the reception antenna, and an AC signal. Phase detection means for detecting a phase of a signal received by a receiving antenna as a source signal.

In addition to the above-described configuration, the proximity sensor of the present invention is characterized in that the resonant element is excited in advance based on a signal from an AC signal source.
Furthermore, in addition to the above-described configuration, the proximity sensor of the present invention is characterized in that the resonant element is excited in advance by electrical coupling based on the signal of the AC signal source.
Furthermore, the proximity sensor of the present invention is characterized in that, in addition to the above-described configuration, the resonant element is excited in advance by mechanical coupling based on the signal of the AC signal source.

Furthermore, the proximity sensor of the present invention is characterized in that, in addition to the above-described configuration, the resonant element includes a vibrator.
Further, the proximity sensor of the present invention is characterized in that, in addition to the configuration described above, the AC signal generation source is an oscillator having a vibrator, and the resonator of the resonance element and the vibrator of the oscillator are integrally formed. To do.
Furthermore, in addition to the above-described configuration, the proximity sensor of the present invention is characterized in that the vibrator is a crystal vibrator, a ceramic vibrator, or a MEMS vibrator.

Furthermore, in addition to the above-described configuration, the proximity sensor of the present invention is characterized in that the resonance element includes an LC resonance circuit.
In addition to the above-described configuration, the proximity sensor of the present invention is characterized in that it includes differential amplification means that differentially amplifies the outputs from both ends of the resonant element and outputs the signals as signals received by the receiving antenna.
Further, the proximity sensor according to the present invention includes, in addition to the above-described configuration, boosting means for boosting the power supply of the circuit of the AC signal generation source between the AC signal generation source and the transmission antenna, and a signal of the AC signal generation source. And amplifying means for amplifying with a power supply system boosted by the boosting means.

Furthermore, the proximity sensor of the present invention is characterized in that, in addition to the above-described configuration, one of the transmission antenna and the reception antenna is a rod-shaped antenna and the other is a ring-shaped antenna.
Furthermore, in the proximity sensor of the present invention, in addition to the above-described configuration, the ring-shaped antenna has a shape in which a plurality of concentric rings are joined.
Furthermore, the proximity sensor of the present invention is characterized in that, in addition to the above-described configuration, the ring-shaped antenna has a coiled shape wound a plurality of times.
Furthermore, the proximity sensor of the present invention is characterized in that, in addition to the above-described configuration, the tip of the rod-shaped antenna has a coiled shape wound a plurality of times.

Furthermore, the proximity sensor of the present invention includes a transparent substrate in addition to the configuration described above, and the transmission antenna and the reception antenna are formed of a transparent electrode on the transparent substrate.
Furthermore, in addition to the above-described configuration, the proximity sensor of the present invention is characterized in that the transmission antenna and the reception antenna are formed in a concentric ring shape.
Further, the proximity sensor of the present invention is characterized in that, in addition to the above-described configuration, the transmitting antenna and the receiving antenna are formed in concentric circular arcs.

Further, in the proximity sensor of the present invention, in addition to the above-described configuration, the transparent substrate is rectangular, and the transmission antenna and the reception antenna are a quarter circle across two sides at the corner of the transparent electric substrate. It is formed in an arc shape.
Further, in the proximity sensor of the present invention, in addition to the configuration described above, the transparent substrate has a rectangular shape, and the transmitting antenna and the receiving antenna are formed in a half arc shape on the side of the transparent substrate. Features.
Furthermore, the proximity sensor of the present invention is characterized in that, in addition to the above-described configuration, at least one of the transmission antenna and the reception antenna is formed in a double or more pattern.

  The proximity sensor of the present invention includes a resonant element connected to a receiving antenna, excites the resonant element using a signal received by the receiving antenna, and performs phase detection using a signal stored in the resonant element. This makes it possible to increase the sensitivity, that is, to detect the distance information to the object to be detected with a high S / N, as compared with the conventional technique in which the phase detection is performed using the signal received by the antenna as it is.

  In addition, the proximity sensor of the present invention can reduce the signal generated from the AC signal generation source to a low frequency. Therefore, the proximity sensor has a simple circuit configuration and low power compared to the prior art that needs to use a high-frequency signal. It becomes possible to operate.

It is a circuit diagram which shows the structure of the proximity sensor of Example 1 of this invention. It is a circuit diagram which shows the structure of the proximity sensor of Example 2 of this invention. It is a circuit diagram which shows the structure of the proximity sensor of Example 3 of this invention. It is a symbol figure which shows a composite vibration conductor typically. It is a top view which shows the structural example of a composite vibrating body. It is sectional drawing which shows the structural example of a composite vibrating body. It is a circuit diagram which shows the structure of the proximity sensor of Example 4 of this invention. It is explanatory drawing which shows the structural example of a transmitting antenna and a receiving antenna. It is explanatory drawing which shows the structural example of a transmitting antenna and a receiving antenna. It is explanatory drawing which shows the structural example of a transmitting antenna and a receiving antenna. It is explanatory drawing which shows the structural example of a transmitting antenna and a receiving antenna. It is explanatory drawing which shows the structural example of a transmitting antenna and a receiving antenna. It is explanatory drawing which shows the structural example of a transmitting antenna and a receiving antenna. It is explanatory drawing which shows the output voltage of the sensor with respect to the approach distance of a to-be-tested object. It is explanatory drawing which shows the structural example of the transmission antenna and reception antenna which were formed on the transparent substrate. It is explanatory drawing which shows the structural example of the transmission antenna and reception antenna which were formed on the transparent substrate. It is explanatory drawing which shows the structural example of the transmission antenna and reception antenna which were formed on the transparent substrate. It is explanatory drawing which shows the structural example of the transmission antenna and reception antenna which were formed on the transparent substrate. It is explanatory drawing which shows the structural example of the transmission antenna and reception antenna which were formed on the transparent substrate. It is a circuit diagram which shows the structure of the conventional proximity sensor.

Hereinafter, embodiments of the present invention will be described in detail.
[Example 1: FIG. 1]
First, the configuration of the proximity sensor according to the first embodiment of the present invention will be described. FIG. 1 is a circuit diagram illustrating a configuration of the proximity sensor 1a according to the first embodiment. As shown in FIG. 1, the proximity sensor 1 a includes an oscillator 2 and a transmission antenna 3 that radiates an AC signal Ea to a region to be inspected based on a low-frequency signal generated by the oscillator 2.

The oscillator 2 is an example of an AC signal generation source, and is configured using, for example, a crystal resonator. The AC signal Ea radiated from the transmitting antenna 3 has high frequency stability because the stability of the frequency and intensity affects the output stability of the proximity sensor, and is stable with respect to temperature, changes with time, etc. It is desirable to use a simple crystal resonator.

  For example, a tuning fork type crystal resonator that enables oscillation in the VLF band is used in order to aim for a low power consumption configuration assuming that it is used in a portable device or the like. Further, even in the case of quartz, the oscillation impedance changes by 10% or more over a wide operating temperature range such as −40 ° C. to 85 ° C. Therefore, it is necessary to provide an AGC circuit that stabilizes the oscillation amplitude. desirable.

  In addition to quartz resonators, piezoelectric elements such as PZT thin films and ceramics (ceramic oscillators), MEMS vibrators formed on the surface of a vibrating body composed of piezoelectric elements such as PZT thin films, and tantalum The oscillator 2 may be configured using a vibrator using lithium acid single crystal, lithium niobate single crystal, or langasite.

  Further, the proximity sensor 1 a includes a receiving antenna 4 that receives an AC signal Eb from a region to be inspected, and a resonator 5 that is connected to the receiving antenna 4. The other end of the resonator 5 connected to the receiving antenna 4 is clamped to a reference voltage. The resonator 5 is excited by the AC signal Eb received by the receiving antenna 4.

  The resonator 5 is configured with as little energy loss as possible. The resonator 5 is configured using, for example, a crystal resonator having a resonance frequency close to the frequency of the oscillator 2. Since the quartz crystal resonator has little energy loss during vibration, it can be stored in a long time interval without attenuating minute changes in electromagnetic waves.

  Other than the quartz crystal resonator, similarly to the oscillator 2, a piezoelectric element such as a PZT thin film and a ceramic vibrator (ceramic vibrator), and a MEMS formed on the surface of a vibrating body including a piezoelectric element such as a PZT thin film made of MEMS. The resonator 5 may be configured using a vibrator, a vibrator using lithium tantalate single crystal, lithium niobate single crystal, or langasite.

  Further, the resonator 5 is formed by using a resonator in which an ultra-small vibrating body is formed using a silicon process and electromechanical coupling is realized using a capacitor, an LC resonance circuit having a resonance frequency close to the frequency of the oscillator 2, and the like. It may be configured. In consideration of miniaturization, a capacitive MEMS vibrator is also promising.

  Further, the proximity sensor 1 a includes a buffer 6 and a resistor 7 that connect the output of the oscillator 2 and one terminal of the resonator 5. With this configuration, the resonator 5 is excited in advance at the oscillation frequency of the oscillator 2 (hereinafter, this vibration is referred to as pre-excitation).

  Here, as the oscillation frequency of the oscillator 2 and the resonance frequency of the resonator 5 are closer, pre-excitation is performed more efficiently (hereinafter, a difference between the oscillation frequency of the oscillator 2 and the resonance frequency of the resonator 5 is referred to as a detuning degree). . However, if the degree of detuning is very close or exactly the same, beat or resonance occurs, which affects the output after detection, which is not desirable. In order to rectify and output a DC voltage, it is necessary to keep the degree of detuning at least higher than the cutoff frequency of the rectifying LPF 10 described later.

  The buffer 6 is provided in order to avoid the influence from the circuit in the subsequent stage on the oscillator 2. The resistor 7 is a coupling resistance between the oscillator 2 and the resonator 5, and has a resistance value that appropriately couples the resonator 5 to the oscillator 2. If the value of the resistor 7 is too small, the electrical coupling becomes too strong, and the amplitude of the resonator 5 is determined by the output of the buffer 6 so that the signal from the receiving antenna 4 is not reflected. On the other hand, if the value of the resistor 7 is too large, the electrical coupling is too weak and the pre-excitation is not performed sufficiently and the effect of the resonator 5 is lost. For this reason, selection of the resistance value of the resistor 7 is important. When a crystal resonator having a resonance frequency of several tens of kHz is used as the resonator 5, the resistance value of the resistor 7 is appropriately about 0.5 to 1 MΩ.

  Further, the proximity sensor 1 a includes an amplifier 8 that amplifies the output of the resonator 5, and a phase detector 9 that detects the phase of the signal received by the receiving antenna 4 with the output signal of the oscillator 2. Further, the proximity sensor 1 a includes an LPF (low-pass filter) 10 that smoothes the output of the phase detector 9 and an output terminal 11.

Next, the operation of the proximity sensor 1a having the above-described configuration will be described.
First, a low-frequency signal is generated by the oscillator 2, and the AC signal Ea is radiated to the inspection area by the transmitting antenna 3. The AC signal Ea radiated from the transmitting antenna 3 forms an electromagnetic field determined by the atmosphere, dielectric, conductor, etc. existing in this area in the area to be inspected. The receiving antenna 4 receives an AC signal Eb corresponding to an electromagnetic field formed in the inspection area.

  At this time, if an object existing in the inspected area does not move at all, the electromagnetic field formed by the AC signal Ea transmitted by the transmitting antenna 3 is in a steady state, and the AC signal Eb received by the receiving antenna 4 has a stable phase. And with amplitude. However, when an inspected object O having an appropriate dielectric constant such as a human finger enters this region, the electromagnetic field changes due to disturbance. As a result, the phase and amplitude of the AC signal Eb received by the receiving antenna 4 change.

  When the resonator 5 includes a crystal resonator, for example, the current due to the AC signal Eb captured from the receiving antenna 4 is extremely small, so that the stopped crystal resonator is excited to the specified frequency only by the current due to the AC signal Eb. Difficult to do. For this reason, as described above, in this embodiment, the crystal resonator of the resonator 5 is pre-excited at the same frequency as the current taken in from the receiving antenna 4.

  In a state where the crystal resonator of the resonator 5 is pre-excited, the AC signal Eb received by the receiving antenna 4 is taken into the crystal resonator of the resonator 5 and accumulated in the crystal resonator. In the case of a crystal resonator having a Q value of tens of thousands, information stored in the crystal resonator is integrated into a size several tens of thousands of times.

  The vibration of the resonator 5 storing the information from the receiving antenna 4 is electrically amplified by the amplifier 8. The output of the amplifier 8 is phase-detected at the frequency of the oscillator 2 by the phase detector 9, smoothed by the LPF 10, and output as a change in DC voltage from the output terminal 11.

  As described above, when an object to be inspected O having an appropriate dielectric constant such as a human finger enters the area to be inspected, the electromagnetic field changes due to disturbance. As a result, the phase and amplitude of the AC signal Eb received by the receiving antenna 4 change, so that the output of the phase detector 9 changes, and the DC output from the smoother 10 that smoothes this changes. The presence and movement of the test object O can be known by the change in the DC output.

  It should be noted here that the electromagnetic field in the region to be inspected formed by the transmission antenna 3 varies depending on the arrangement of objects in the region to be inspected, and the region to be inspected as viewed from the transmitting antenna 3 and the receiving antenna 4 If it is interpreted as a range in which electromagnetic waves are formed, in principle, it extends to infinity. Therefore, an area that can be sensed by the proximity sensor according to the present embodiment without being buried in noise is defined as an inspected area, and an output in an environment in which the transmitting antenna 3 and the receiving antenna 4 are installed is set as a background. It is necessary to grasp the change due to the disturbance of this as a change from this background output.

As described above, the proximity sensor 1a of the present embodiment excites the resonator 5 using the AC signal Eb received by the receiving antenna 4, and performs phase detection using the signal stored in the resonator 5. As a result, the sensitivity is increased (that is, with a high S / N) and the distance information to the object to be detected O can be detected with high accuracy as compared with the conventional technique in which the phase detection is performed using the AC signal received by the antenna as it is. It becomes possible.

  Further, the proximity sensor 1a according to the present embodiment can make a signal generated from the oscillator 2 a low frequency (for example, VLF band), and therefore has a simple circuit configuration as compared with the prior art that needs to use a high frequency signal. It is possible to operate with low power.

  Further, in the proximity sensor 1a of the present embodiment, the resonator 5 includes a crystal resonator, for example, and this crystal resonator is pre-excited so that the AC signal Eb received by the receiving antenna 4 is weak. Even if it exists, it becomes possible to detect the distance information to the test object O with high accuracy.

  Next, another embodiment of the proximity sensor of the present invention will be described. In the following description, the same reference numerals are given to the same components that have already been described, and detailed descriptions thereof will be omitted, and only differences in configuration will be described.

[Example 2: FIG. 2]
A proximity sensor according to Example 2 of the present invention will be described. FIG. 2 is a circuit diagram illustrating a configuration of the proximity sensor 1b according to the second embodiment. As shown in FIG. 2, the proximity sensor 1 b according to the second embodiment includes an inverting amplifier 12 connected to the other terminal of the resonator 5 in addition to the amplifier 8 connected to the receiving antenna 4 side terminal of the resonator 5. And a differential amplifier 13 for differentially amplifying the outputs of the amplifier 8 and the inverting amplifier 12.

  When a signal having a frequency away from the resonance frequency is input to the resonator 5, a signal having a phase substantially inverted from the input signal is output from the other terminal. Accordingly, an approximately in-phase AC signal is output from the amplifier 8 and the inverting amplifier 12.

  From the amplifier 8, the signal received by the receiving antenna 4 is superimposed on the signal corresponding to the pre-excitation and output. In contrast, the inverting amplifier 12 outputs a signal corresponding to pre-excitation that is not affected by the signal received by the receiving antenna 4. Therefore, the differential amplifier 13 that takes the difference between the outputs of the amplifier 8 and the inverting amplifier 12 does not include the amplitude due to the pre-excitation, and outputs only the signal received by the receiving antenna 4.

  In general, if the voltage amplitude in the AC state before detection is set large, noise generated during detection due to phase noise between the reference signal for detection and the detected signal is suppressed to a low level. High detection is possible. In the proximity sensor 1a according to the first embodiment shown in FIG. 1, since the signal resulting from the pre-excitation with amplitude much larger than the detection signal is superimposed on the output of the amplifier 8, the pre-detection gain cannot be increased. There is a problem to say.

On the other hand, in the proximity sensor 1b of the second embodiment shown in FIG. 2, the signal due to the pre-excitation is removed by the differential amplifier 13, so that the amplitude of the output signal from the differential amplifier 13 is from the receiving antenna 4. It is only a signal that is input and integrated by the resonator 5, and the amplitude is not raised by pre-excitation.
Therefore, the detection signal can be amplified in the subsequent stage without worrying about saturation of the amplitude of the pre-excitation, and in principle, the amplification factor before detection can be maximized. As a result, a proximity sensor having a higher S / N can be configured.

FIG. 2 shows an example in which the inverting amplifier 12 is used to generate a reference signal to be input to the differential amplifier 13. However, when the oscillation frequency of the oscillator 2 and the resonance frequency of the resonator 5 are close to each other (that is, when the degree of detuning is small), the phase difference between outputs from both ends of the resonator 5 depends on the nature of the resonator 5 and the like. It will not be 180 degrees. In this case, it is necessary to use a phase shifter instead of the inverting amplifier 12 so that the output of the amplifier 8 and the phase of the phase shifter are substantially matched.

  The operation of detecting the distance of the object O to be detected by the proximity sensor 1b of the second embodiment is the same as that of the first embodiment. Similar to the proximity sensor 1 a of the first embodiment, the proximity sensor 1 b of the second embodiment excites the resonator 5 using the AC signal Eb received by the receiving antenna 4, and uses a signal stored in the resonator 5. By performing phase detection, distance information to the object to be detected O can be detected with high accuracy. In addition, since the signal generated from the oscillator 2 can be set to a low frequency, it is possible to operate with a simple circuit configuration and low power.

[Example 3: Figs. 3 to 6]
Next, a proximity sensor according to Example 3 of the present invention will be described. FIG. 3 is a circuit diagram illustrating a configuration of the proximity sensor 1c according to the third embodiment. The proximity sensor 1c according to the third embodiment is characterized in that the resonator 5 is pre-excited mechanically by the oscillator 2. In order to show that the same function as the resistor 7 shown in FIG. 2 is performed, in FIG. 3, the mechanical coupling 14 for pre-exciting the resonator 5 by the oscillator 2 is schematically replaced with a circuit.

  In the following description, the oscillator 2 and the resonator 5 are each configured using a crystal resonator as a configuration for mechanically pre-exciting the resonator 5 by the oscillator 2, and the crystal resonators of the oscillator 2 and the resonator 5 are The example formed integrally is shown.

FIG. 4 is an electrical symbol diagram schematically showing a composite vibrator 20 in which the oscillator 2 and the crystal resonator of the resonator 5 are mechanically coupled and formed integrally. As shown in FIG. 4, in the composite vibrator 20, a vibrator 21 constituting the oscillator 2 and a vibrator 22 constituting the resonator 5 are coupled by a mechanical coupling 23. The mechanical coupling 23 in FIG. 4 is a concept equivalent to the mechanical coupling 14 in FIG.
The composite vibrator 20 shown in FIG. 4 is a four-terminal element. Electrodes 211 and 222 are formed on the vibrator 21, and electrodes 221 and 222 are formed on the vibrator 22.

  An example of a specific shape of the composite vibrator shown in FIG. 4 is shown in FIGS. 5 and 6 as a composite vibrator 20a. FIG. 5 is a plan view of the composite vibrator 20a, and FIG. 6 is a cross-sectional view taken along the line A-A 'of FIG. The composite vibrating body 20a is processed by a wet etching operation from a Z-cut quartz plate having a thickness of about 100 μm to 200 μm, for example.

  As shown in FIG. 5, the composite vibrating body 20a includes a leg 21aL and a leg 21aR that are slightly different in shape such as width and cross-sectional shape. The composite vibrator 20a has a central leg 22a located between the legs 21aL and 21aR. The center leg 22a is designed with a width different from that of the legs 21aL and 21aR. The legs 21aL, 21aR and the central leg 22a are joined to the base 24 at one end, and the composite vibrator 20a has a shape like the letter E when viewed from the direction of the optical axis of the crystal, that is, the Z axis. Yes.

As shown in FIG. 6, electrodes 211 are formed on both side surfaces perpendicular to the optical axis direction of the legs 21aL and both side surfaces perpendicular to the electric axis direction of the legs 21aR. Electrodes 212 are formed on both side surfaces perpendicular to the electric axis direction of the legs 21aL and both side surfaces perpendicular to the optical axis direction of the legs 21aR. The leg 21aL and the leg 21aR constitute the vibrator 21 shown in FIG.
Electrodes 221 are formed on both side surfaces perpendicular to the electric axis direction of the central leg 22a, and electrodes 222 are formed on both side surfaces perpendicular to the optical axis direction of the central leg 22a. The legs 22a constitute the vibrator 22 shown in FIG.

The crystal resonator cut out by the Z cut expands and contracts in the mechanical axis direction when an electric field is applied in the electric axis direction, and generates an electric field in the electric axis direction when the leg is expanded and contracted in the mechanical axis direction. Therefore, when an alternating current is applied between the electrode 211 and the electrode 212, the composite vibrator 20a causes the tuning fork-type bending vibration of the leg 21aL and the leg 21aR as indicated by an arrow B in FIG. The natural frequency of this bending vibration is approximately determined by the width and length of the legs 21aL and 21aR. In addition, when the leg 21aL and the leg 21aR perform tuning-fork type bending vibration, an alternating current is generated between the electrode 211 and the electrode 212.

  When the leg 21aL and the leg 21aR perform tuning-fork type flexural vibration, the leg 21aL and the leg 21aR are slightly different in shape from each other and thus do not balance, and the composite vibrator 20a vibrates slightly. Due to the influence of the vibration of the composite vibration body 20a as a whole, the central leg 22a slightly vibrates in a direction orthogonal to the extending direction of the legs in a plane including all the legs as shown by an arrow C in FIG. .

  The slight vibration of the leg 22a is the vibration caused by the mechanical couplings 14 and 23 described above. When the leg 22a slightly vibrates, a weak current is generated between the electrode 221 and the electrode 222 at the oscillation frequency of the leg 21aL and the leg 21aR. This is pre-excitation. This phenomenon can be said as follows. In the composite vibrating body 20a, the legs 21aL and the legs 21aR on both sides constitute the vibrator 21, and this vibration excites another vibrating body 22 (leg 22a) by weak mechanical coupling. The width of the leg 21aL and the leg 21aR and the width of the leg 22a are designed so that the degree of detuning, which is the difference between their natural frequencies, is several hundred Hz, for example.

  In the above description, the shape of the leg 21aL and the leg 21aR is slightly different from each other. However, even if the leg 21aL and the leg 21aR are designed to have the same length and thickness, the work accuracy of the crystal tuning fork shape is improved. Since there is a limit, the shapes of the legs 21aL and 21aR are slightly different from each other. Therefore, as described above, the vibrations of the legs 21aL and the legs 21aR are not balanced with each other, the entire composite vibration body 20a vibrates, and the central leg 22a vibrates due to the influence of this vibration.

  It should be further noted that when the composite vibrator 20a is rotated in the optical axis direction while the vibrator 21 (the legs 21aL and 21aR) is oscillating, the excitation proportional to the rotational speed is caused by the Coriolis force. Is superimposed on the vibration of the vibrator 22 (leg 22a), and the output of the proximity sensor becomes erroneous. In order to avoid this, the base 24 is firmly fixed by narrowing the distance between the legs (leg 21aL, leg 21aR, leg 22a) so that the moment in the direction of rotation of the optical axis is reduced.

  The operation of detecting the distance of the object O to be detected by the proximity sensor 1c of the third embodiment is the same as that of the first embodiment described above. Similar to the proximity sensor 1 a of the first embodiment, the proximity sensor 1 c of the third embodiment also excites the resonator 5 using the AC signal Eb received by the receiving antenna 4 and uses the signal stored in the resonator 5. By performing phase detection, distance information to the object to be detected O can be detected with high accuracy. In addition, since the signal generated from the oscillator 2 can be set to a low frequency, it is possible to operate with a simple circuit configuration and low power.

  Further, as described above, the proximity sensor 1c according to the third embodiment is configured to mechanically perform the pre-excitation of the resonator 5, and the receiving antenna 4 and the oscillator 2 are not electrically coupled. Therefore, compared with the first and second embodiments in which the receiving antenna 4 and the oscillator 2 are electrically coupled, the AC signal Eb received by the receiving antenna 4 is not hindered by the output signal of the oscillator 2, It becomes possible to detect the distance information to the test object O with high sensitivity.

  Further, in the proximity sensor 1c according to the third embodiment, since the vibrator 21 constituting the oscillator 2 and the vibrator 22 constituting the resonator 5 are integrally formed as the composite vibrator 20, the size of the device can be reduced. Is possible.

4 to 6 show an example in which the oscillator 2 and the resonator 5 are each configured using a crystal resonator, and the crystal resonators of the oscillator 2 and the resonator 5 are integrally formed as a composite vibrator 20. It was. However, the present invention is not limited to this, and the oscillator 2 and the resonator 5 are each configured to include a resonator other than a crystal resonator such as a ceramic resonator and a MEMS resonator, and the resonator 2 and the resonator 5 resonate. The vibrator of the vessel 5 may be integrally formed as a composite vibrator.

[Example 4: FIG. 7]
Next, a proximity sensor according to Example 4 of the present invention will be described. FIG. 7 is a circuit diagram illustrating a configuration of the proximity sensor 1d according to the fourth embodiment. As illustrated in FIG. 7, the proximity sensor 1 d according to the fourth embodiment includes a booster circuit 30 that boosts the power supply of the circuit of the oscillator 2 between the oscillator 2 and the transmission antenna 3 in the configuration of the proximity sensor 1 c according to the third embodiment. And an amplifier circuit 31 that amplifies the signal of the AC signal generation source by the power supply system boosted by the booster circuit 30. The booster circuit 30 is an example of a booster, and the amplifier circuit 31 is an example of an amplifier.
With such a configuration, the signal output from the oscillator 2 is voltage amplified by the booster circuit 30 and the amplifier circuit 31, and the transmission antenna 3 is based on the signal amplified in comparison with the power supply voltage used by this apparatus. As a result, a stronger electromagnetic wave AC signal Ea is radiated to the region to be inspected.

Therefore, the proximity sensor 1d according to the fourth embodiment has a wider inspection area than the proximity sensor 1c according to the third embodiment, even if the power supply voltage used is a low power supply voltage such as 3V and 5V. O distance can be detected.
In the fourth embodiment shown in FIG. 7, the booster circuit 30 is exemplified in the configuration of the proximity sensor 1c of the third embodiment. However, in the configuration of the proximity sensor 1a of the first embodiment or the proximity sensor 1b of the second embodiment, the oscillator 2 and the transmission antenna 3 may be provided with a booster circuit 30.

[Configuration Examples of Transmitting Antenna and Receiving Antenna: FIGS. 8 to 19]
Next, the configuration of the transmission antenna 3 and the reception antenna 4 used in the proximity sensor of each embodiment described above will be described. 8 to 13 are explanatory diagrams of the configurations of the transmission antenna 3 and the reception antenna 4.

  In the proximity sensor of each embodiment described above, some arrangement is required for the arrangement of the transmission antenna 3 and the reception antenna 4. Considering the efficiency of the antenna, the planar transmission antenna 3a and the reception antenna 4a are arranged in parallel as shown in FIG. 8, or the rod-like transmission antenna 3b and the reception antenna 4b are arranged in parallel as shown in FIG. The arrangement for detecting the approach of the object to be measured in the space region between the antennas has the largest change in the way of propagation of electromagnetic waves, and the sensitivity as a sensor is large. Further, it is desirable to provide shields 15 and 16 in the wiring part in order to suppress the influence on the reception and transmission of signals in the wiring part.

However, in the antenna configurations shown in FIGS. 8 and 9, even if the distance between the test object and the antenna is the same, if the movement direction of the test object with respect to the antenna is different, the output of the proximity sensor will be different. End up.
Hereinafter, with reference to FIGS. 10 to 13, the configuration of the transmission antenna 3 and the reception antenna 4 in which the output of the proximity sensor does not depend on the moving direction of the object to be detected with respect to the antenna but depends on the distance between the antenna and the object to be detected. explain.

  The antenna configuration shown in FIG. 10 includes a rod-shaped transmitting antenna 3c and a ring-shaped receiving antenna disposed at an equal distance from the rod-shaped transmitting antenna 3c in a plane perpendicular to the direction in which the rod-shaped transmitting antenna 3c extends. 4c. The rod-shaped transmitting antenna 3c is provided with a shield 15 at a portion excluding a minute portion at the tip, and the ring-shaped receiving antenna 4c is provided with a shield 16 at a portion excluding the ring portion.

In the antenna having the configuration shown in FIG. 10, the electromagnetic wave transmitted from the transmission antenna 3c is symmetric about the rod-shaped portion of the transmission antenna 3c. Further, in the antenna having the configuration shown in FIG. 10, when the ring diameter of the receiving antenna 4c is reduced, the electromagnetic field formed from the transmitting antenna 3c to the receiving antenna 4c is considered to be centrally symmetric from a position away from a predetermined distance. Can do.
Therefore, the antenna configured as shown in FIG. 10 can be configured such that the output of the proximity sensor does not depend on the moving direction of the test object relative to the antenna but depends on the distance between the antenna and the test object.

  The antenna having the configuration shown in FIG. 11 includes a receiving antenna 4d in which a plurality of concentric rings are joined to the antenna having the configuration shown in FIG. The antenna having the configuration shown in FIG. 12 includes a coil-shaped receiving antenna 4e wound a plurality of times in the antenna having the configuration shown in FIG. With the configuration shown in FIGS. 11 and 12, it is possible to improve the reception sensitivity of the antenna. The reception sensitivity of the antenna increases with the number of rings.

  The antenna having the configuration shown in FIG. 13 is provided with a transmission antenna 3d having a coiled tip portion wound a plurality of times in the antenna having the configuration shown in FIG. With this configuration, it is possible to increase the area functioning as a transmission antenna and improve the output of the transmission antenna. The transmission antenna 3d may be combined with the reception antennas 4c and 4d shown in FIGS.

  FIG. 14 illustrates an experiment using the proximity sensor 1c according to the third embodiment including the antenna having the configuration illustrated in FIG. 13, and the test object obtained as a result of the experiment and the output voltage of the sensor. Show the relationship. A human finger is used as the test object. In FIG. 14, the horizontal axis (X axis) indicates the distance from the center of the antenna to the object to be detected, and the vertical axis (Y axis) indicates the output voltage of the sensor. The solid line in FIG. 14 indicates the output of the sensor, and the broken line indicates a line approximated by Y = 3000 / X-50.

  The output of the proximity sensor used in this experiment is a direct current. In FIG. 14, the output voltage is shown as a difference value from the output value when the test object is sufficiently away from the proximity sensor. The output of the proximity sensor used in this experiment has a noise of about 2 mVrms, and the output is buried in noise at a distance exceeding 5 cm as shown in FIG.

  Further, as shown in FIG. 14, it can be confirmed that the output of the proximity sensor used in this experiment is almost inversely proportional to the distance from the center of the antenna of the test object. Thus, the fact that the output is inversely proportional to the distance of the object to be tested confirms that the distance detection operation by the proximity sensor is caused by electromagnetic waves rather than electrostatic fields.

  It was also confirmed that the proximity sensor used in this experiment was able to detect an object to be detected within a distance of about 5 cm with sufficient S / N when the output of the oscillator 2 was a voltage amplitude of 5V. If the output of the oscillator 2 is set to a voltage amplitude of 100 V with the proximity sensor of the present invention, a test object within a distance of about 1 m can be detected with sufficient S / N.

Although FIGS. 10 to 13 show an example in which the rod-shaped transmission antenna 3 and the ring-shaped reception antenna 4 are provided, the transmission antenna 3 may have a ring shape and the reception antenna 4 may have a rod shape.
The transmitting antenna 3 and the receiving antenna 4 described with reference to FIGS. 8 to 13 have antenna configurations optimized for sensitivity when there is not much restriction on the installation environment.

Recently, there is an increasing need for an input device linked to video information drawn on a display, that is, an input device called a touch panel. If the transmitting antenna and the receiving antenna of the proximity sensor of the present invention are arranged on the display, the position of the test object located in the three-dimensional region on the display is detected, and according to the three-dimensional position information of the test object. An input device can be configured by controlling input to the device.

  Hereinafter, the transmitting antenna 3 and the receiving antenna 4 formed using a transparent electrode such as ITO on a transparent substrate in order to constitute such an input device will be described. FIG. 15 is a first configuration example of the transmission antenna 3 and the reception antenna 4 formed using a transparent electrode on a transparent substrate.

  The antenna configuration shown in FIG. 15 includes a transmission antenna 3f and a reception antenna 4f formed in a ring shape by transparent wiring using a transparent electrode such as ITO on a transparent substrate 25 such as glass or resin. The pattern of the receiving antenna 4f is formed concentrically around the pattern of the transmitting antenna 3f. By forming the transmission antenna and the reception antenna in a concentric ring shape in this way, the antenna and the test object are independent of the moving direction of the test object with respect to the antenna, similarly to the antenna configuration shown in FIGS. The output of the proximity sensor depending on the distance can be obtained.

In addition, it is necessary to perform wiring for connecting the transmitting antenna 3f and the receiving antenna 4f to a circuit unit (not shown) that constitutes the proximity sensor, but in order to suppress the influence on the reception and transmission of the signal of the wiring unit, It is desirable to provide shields 15 and 16.
FIG. 15 shows an example in which the transmission antenna and the reception antenna are formed with a single ring-shaped pattern, but one or both of the transmission antenna and the reception antenna may be formed with a double or more ring-shaped pattern. good. The reception sensitivity of the antenna can be improved by increasing the number of rings of each antenna.

  Usually, the display area is rectangular. When an object located in the three-dimensional space on the rectangular area is detected by, for example, four proximity sensors, it is reasonable to arrange the antennas of the proximity sensors at the corners of the rectangular area.

  Here, as described above, since the output of the proximity sensor of the present invention is inversely proportional to the distance between the object to be measured and the center of the antenna, the output of the sensor becomes too large near the center of the ring of the antenna. Further, the vicinity of the center of the ring of the antenna is also a singular region where the situation where the sensitivity is inversely proportional to the distance is distorted. Therefore, the vicinity of the center of the ring is not suitable for detection.

However, when the antenna having the configuration shown in FIG. 15 is arranged at the corner of the rectangular region, the vicinity of the center of the ring of the antenna is located inside from the corner. Further, when the antenna is formed with a large ring in order to increase sensitivity, the vicinity of the center of the ring of the antenna is positioned further inside.
That is, even if the antenna having the configuration shown in FIG. 15 is arranged at the corner of the rectangular area, the vicinity of the center of the ring unsuitable for detection is located inside the corner of the rectangular area. There is a problem that an object located in space cannot be detected correctly.

  FIG. 16 is a configuration for solving such a problem, and is a second configuration example of the transmission antenna 3 and the reception antenna 4 formed using a transparent electrode on a transparent substrate. In the configuration of the antenna shown in FIG. 16, a 1/4 arc-shaped transmitting antenna 3 g 1 and receiving antenna 4 g 1 are connected to the transparent substrate 25 by transparent wiring using transparent electrodes such as ITO at the corners of the transparent substrate 25. It is formed across two sides. The pattern of the receiving antenna 4g1 is formed in a concentric circular arc shape surrounding the pattern of the transmitting antenna 3g1.

Wiring for connecting to the circuit unit (not shown) constituting the proximity sensor is performed from each of the transmission antenna 3g1 and the reception antenna 4g1 via the connection terminals 27 and 28. In order to suppress the influence on the reception and transmission of the signal of the wiring part, it is desirable to provide shields 15 and 16 in the wiring part.

Similarly, the transmitting antennas 3g2-3g4 and the receiving antennas 4g2-4g4 are formed in the other corners of the transparent substrate 25 in a 1/4 arc pattern. The pattern of the receiving antennas 4g2-4g4 is formed in a concentric circular arc shape surrounding the pattern of the transmitting antennas 3g2-3g4.
Here, the transmitting antenna 3g2 and the receiving antenna 4g2, the transmitting antenna 3g3 and the receiving antenna 4g3, and the transmitting antenna 3g4 and the receiving antenna 4g4 are respectively connected to circuit units constituting separate proximity sensors. In FIG. 16, only the wiring from the transmission antenna 3g1 and the reception antenna 4g1 is shown.

  In the configuration example shown in FIG. 16, by forming the transmission antenna and the reception antenna in a ¼ arc shape, the vicinity of the center of the ring unsuitable for detection can be positioned at the corner of the rectangular region. Thereby, it is possible to correctly detect an object located in the three-dimensional space on the display area.

  In the configuration example shown in FIG. 16, the transmitting antenna and the receiving antenna are formed in concentric circular arcs, so that the inner side of the rectangular area does not depend on the moving direction of the test object with respect to the antenna, The output of the proximity sensor depending on the distance of the test object can be obtained.

  FIG. 17 shows a third configuration example of the transmitting antenna 3 and the receiving antenna 4 formed using a transparent electrode on a transparent substrate. In the antenna configuration shown in FIG. 17, arc-shaped transmission antennas 3h1-3h4 and reception antennas 4h1-4h4 are formed on a transparent substrate 25 by transparent wiring using transparent electrodes such as ITO. The pattern of the receiving antennas 4h1-4h4 surrounds the pattern of the transmitting antennas 3h1-3h4 and is formed in a concentric circular arc shape across the two sides at the corner of the transparent substrate 25.

  The transmission antenna 3h1 and the reception antenna 4h1, the transmission antenna 3h2 and the reception antenna 4h2, the transmission antenna 3h3 and the reception antenna 4h3, and the transmission antenna 3h4 and the reception antenna 4h4 are respectively connected to circuit units constituting separate proximity sensors. In FIG. 17, only the wiring from the transmitting antenna 3h1 and the receiving antenna 4h1 is shown.

  In FIG. 17, the boundary of the display portion of the display is indicated by B. The boundary B of the display unit is located inward from the end of the transparent substrate 25 by a predetermined length. Further, the center C1-C4 of the arcs of the transmitting antennas 3h1-3h4 and the receiving antennas 4h1-4h4 are respectively located at the corners of the display unit. The transmission antennas 3h1-3h4 and the reception antennas 4h1-4h4 are arcs larger than ¼, and are formed beyond the boundary B of the display unit to the end of the transparent substrate 25.

  Accordingly, in the antenna having the configuration shown in FIG. 17, the sensitivity distortion with respect to the area of the display unit is suppressed and the position of the object to be detected is accurately compared with the antenna formed by the ¼ arc shown in FIG. It becomes possible to detect.

  FIG. 18 shows a fourth configuration example of the transmitting antenna 3 and the receiving antenna 4 formed using a transparent electrode on a transparent substrate. In the configuration of the antenna shown in FIG. 18, the transmitting antenna 3 i 1-3 i 4 and the receiving antenna 4 i 1-4 i 4 are each made up of a quarter of a quarter by transparent wiring using a transparent electrode such as ITO on the transparent substrate 25. It is formed with an arc-shaped pattern. The pattern of the receiving antennas 4g1-4g4 surrounds the pattern of the transmitting antennas 3g1-3g4, and is formed in a concentric circular arc shape at the corner of the boundary B of the display unit.

Transmitting antenna 3i1 and receiving antenna 4i1, transmitting antenna 3i2 and receiving antenna 4i2
The transmitting antenna 3i3 and the receiving antenna 4i3, and the transmitting antenna 3i4 and the receiving antenna 4i4 are respectively connected to circuit units constituting separate proximity sensors. In FIG. 18, only the wiring from the transmitting antenna 3i1 and the receiving antenna 4i1 is shown.

In the antenna having the configuration shown in FIG. 18, the transmitting antennas 3i1-3i4 and the receiving antennas 4i1-4i4 are each formed in a double ¼ arc-shaped pattern, so that the receiving sensitivity of the antenna can be improved. It becomes. The reception sensitivity of the antenna can be improved by increasing the number of arc-shaped pattern rings of each antenna.
Although FIG. 18 shows an example in which both the transmitting antenna and the receiving antenna are formed with a double arc pattern, only one of the antennas may be formed with a double arc pattern. Further, one or both of the transmission antenna and the reception antenna may be formed in a triple or more arc pattern.

FIG. 19 shows a fifth configuration example of the transmission antenna 3 and the reception antenna 4 formed using a transparent electrode on a transparent substrate.
In the configuration of the antenna shown in FIG. 19, similarly to FIG. 18, the transmitting antenna 3j1-3j4 and the receiving antenna 4j1-4j4 are respectively formed by transparent wiring using transparent electrodes such as ITO at the corners of the transparent substrate 25. It is formed of a double quarter arc pattern.

  The transmitting antenna 3j1 and the receiving antenna 4j1, the transmitting antenna 3j2 and the receiving antenna 4j2, the transmitting antenna 3j3 and the receiving antenna 4j3, and the transmitting antenna 3j4 and the receiving antenna 4j4 are respectively connected to circuit units constituting separate proximity sensors. In FIG. 19, only the wiring from the transmitting antenna 3j1 and the receiving antenna 4j1 is shown.

The antenna configuration shown in FIG. 19 further includes a transmission antenna 3j5-3j6 and a reception antenna 4j5-4j6 formed on the side of the transparent substrate 25 in a double half arc pattern. The pattern of the receiving antennas 4j5-4j6 surrounds the pattern of the transmitting antennas 3j5-3j6 and is formed in a concentric circular arc shape at the corner of the boundary B of the display unit.
The transmission antenna 3j5 and the reception antenna 4j5, and the transmission antenna 3j6 and the reception antenna 4j6 are respectively connected to circuit units constituting separate proximity sensors.

With the configuration as shown in FIG. 19, it is possible to detect an object in a wider inspection area as compared with the configurations of FIGS. 16 to 18 in which the antennas are arranged only at the corners of the transparent substrate. Become.
Although FIG. 19 shows an example in which both the transmitting antenna and the receiving antenna are formed with a double arc pattern, one or both antennas may be formed with one arc pattern.
FIGS. 15 to 19 show an example in which the reception antenna 4 is formed surrounding the transmission antenna 3, but the transmission antenna 3 may be formed surrounding the reception antenna 4.

  In the proximity sensor of the present invention, as shown in FIG. 15 to FIG. 19, a transmission antenna and a reception antenna formed of a transparent electrode on a transparent substrate are used, and this antenna is arranged on the display, whereby 3 on the display is displayed. It is possible to configure an input device that detects the position of the test object located in the three-dimensional region and controls the input to the device in accordance with the three-dimensional position information of the test object.

1a, 1b, 1c, 1d Proximity sensor 2 Oscillator 3, 3a, 3b, 3c, 3d, 3f, 3g1-3g4, 3h1-3h4, 3i1-3i
4, 3j1-3j6 Transmitting antenna 4, 4a, 4b, 4c, 4d, 4e, 4f, 4g1-4g4, 4h1-4h4, 4i1-4i4, 4j1-4j6 Receiving antenna 5 Resonator 6 Buffer 7 Resistor 8 Amplifier 9 Phase detection 10 LPF
DESCRIPTION OF SYMBOLS 11 Output terminal 12 Inverting amplifier 13 Differential amplifier 14, 23 Mechanical coupling 15, 16 Shield 20, 20a Composite vibrator 21, 22 Vibrator 211, 212, 221, 222 Electrode 21aL, 21aR, 22a Leg 24 Base 25 Transparent substrate 27 Connection terminal 28 Connection terminal 30 Booster circuit 31 Amplifier circuit

Claims (20)

An AC signal source;
A transmission antenna that transmits radio waves based on a signal from the AC signal generation source;
A receiving antenna for receiving radio waves,
A resonant element connected to the receiving antenna;
Phase detection means for phase-detecting a signal received by the receiving antenna with a signal of the AC signal generation source. A proximity sensor, comprising: The proximity sensor according to claim 1, wherein the resonance element is excited in advance based on a signal from the AC signal source. The proximity sensor according to claim 2, wherein the resonance element is excited in advance by electrical coupling based on a signal from the AC signal source. The proximity sensor according to claim 2, wherein the resonance element is excited in advance by mechanical coupling based on a signal from the AC signal source. The proximity sensor according to claim 1, wherein the resonance element includes a vibrator. The AC signal generation source is an oscillator having a vibrator,
The proximity sensor according to claim 5, wherein the resonator of the resonant element and the resonator of the oscillator are integrally formed. The proximity sensor according to claim 5, wherein the vibrator is a crystal vibrator, a ceramic vibrator, or a MEMS vibrator. The proximity sensor according to claim 1, wherein the resonance element includes an LC resonance circuit. The proximity sensor according to any one of claims 1 to 8, further comprising differential amplifying means for differentially amplifying outputs from both ends of the resonant element and outputting the signals as signals received by the receiving antenna. . Between the AC signal generation source and the transmitting antenna,
Boosting means for boosting the power supply of the circuit of the AC signal generation source;
The proximity sensor according to claim 1, further comprising: an amplifying unit that amplifies the signal of the AC signal generation source by a power supply system boosted by the boosting unit. 10. The proximity sensor according to claim 1, wherein one of the transmission antenna and the reception antenna is a rod-shaped antenna, and the other is a ring-shaped antenna. The proximity sensor according to claim 10, wherein the ring-shaped antenna has a shape in which a plurality of concentric rings are joined. The proximity sensor according to claim 10, wherein the ring-shaped antenna has a coiled shape wound a plurality of times. The proximity sensor according to any one of claims 10 to 12, wherein a tip end portion of the rod-shaped antenna has a coil shape wound a plurality of times. With a transparent substrate,
The proximity sensor according to any one of claims 1 to 9, wherein the transmitting antenna and the receiving antenna are formed of a transparent electrode on the transparent substrate. The proximity sensor according to claim 14, wherein the transmission antenna and the reception antenna are formed in a concentric ring shape. The proximity sensor according to claim 14, wherein the transmitting antenna and the receiving antenna are formed in a concentric circular arc shape. The transparent substrate has a rectangular shape,
The proximity sensor according to claim 16, wherein the transmitting antenna and the receiving antenna are formed in a ¼ arc shape across two sides at a corner of the transparent electric substrate. The transparent substrate has a rectangular shape,
The proximity sensor according to claim 16, wherein the transmission antenna and the reception antenna are formed in a half arc shape on a side portion of the transparent substrate. The proximity sensor according to any one of claims 15 to 19, wherein at least one of the transmission antenna and the reception antenna is formed in a double or more pattern.

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