JP2005127849A - Proximity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily perform detection at a short distance, and to be manufacturable at low cost. <P>SOLUTION: When a detection object 31 such as a person approaches near external panels 11-14, an electric field in detection areas 11A-14A is reflected or absorbed by the detection object 31, and a field of an electromagnetic wave radiation space is changed. The change is detected by a directional coupler 28, and a frequency for down conversion is inputted into a mixer 23, and the change in the detection areas 11A-14A is recognized by the frequency passing the mixer 23. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a proximity sensor that detects a change in a specific electromagnetic radiation space used to detect a short-distance state of a person, an object, or the like that is approaching a vehicle, and has a use frequency of 300 MHz to 300 GHz. The present invention relates to a proximity sensor using a microwave.

  A conventional proximity sensor includes an oscillating means, a resonant means that resonates with a harmonic of the oscillation frequency of the oscillating means, a detection electrode connected to the resonant means, and an electrostatic capacitance between the detection electrode and the object to be detected. The detection means detects a signal change based on a change in capacitance.

  The oscillating means oscillates at a predetermined frequency, and the resonance means composed of the LC series resonance circuit does not resonate with the oscillation frequency but resonates with the harmonics of the oscillation frequency.

  Therefore, when the object approaches the detection electrode, the capacitance between the object surface and the detection electrode changes, and the signal changes. The approach of the object can be detected by monitoring this signal change.

In this type of proximity sensor, the initial value of the capacitance is set to a value that is increased by a predetermined amount from the value when it matches the resonance frequency to improve the characteristics against temperature change and aging degradation. ing.
JP 2001-55852 A

  In the conventional proximity sensor described above, since the electrostatic capacitance between the object and the detection electrode is detected, the detection distance differs depending on the size of the person or the object, and there is a possibility that the accuracy is poor and malfunctions. There are also many malfunctions due to changes in rain and humidity. When the proximity sensor is disposed on the conductive panel, it is difficult to distinguish between the opening / closing operation of the door and the case where the proximity sensor is sandwiched between the door and the like. Furthermore, since the electrostatic capacitance between the detection electrode and the vehicle body ground is detected, there is a problem that it is difficult to install the detection electrode on the metal body of the vehicle.

  Therefore, the present invention has an object to provide a proximity sensor that can be detected in a vehicle without misoperation due to environmental changes due to changes in rain, humidity, etc., and can be disposed in a vehicle, and a versatile proximity sensor. To do.

  The proximity sensor according to claim 1 includes a conductive member that can be integrated or separated from an attachment target, a detection region that is set outside the conductive member, a feeding point and a receiving point that are set on the conductive member, By amplifying the frequency obtained from the power receiving point and returning the frequency to the feeding point, microwaves are automatically generated using the conductive member as an antenna at a frequency with a sufficiently short wavelength relative to the size of the conductive member. An oscillation circuit for exciting oscillation, and detecting a change in the detection region as a frequency change obtained from the oscillation circuit.

Therefore, an oscillation circuit having a conductive member as an antenna oscillates, electromagnetic waves are radiated from the conductive member to the detection region, and a specific frequency radiated from the conductive member in relation to the detection region and the conductive member. It becomes a resonance state of the state. Even if an electromagnetic wave having an oscillation frequency is radiated from the conductive member, if there is no detection target in the detection region that causes reflection or absorption, the oscillation frequency does not vary. However, when a detection target (dielectric material) such as a person approaches a detection region that is an electromagnetic wave radiation space, a microwave oscillation circuit is formed between the conductive member and the detection target as an antenna, and the conductive The resonance frequency state radiated from the member changes. That is, when a detection target such as a person approaches the conductive member, the electric field in the detection region is reflected or absorbed by the detection target, and the field of the electromagnetic wave radiation space changes. By detecting this, the approach of the detection target can be detected. Here, the change in the frequency to be detected means a frequency shift or a magnitude of the frequency (a magnitude of voltage).

  Here, the conductive member may be a conductor that can be integrated with or separated from an object to be attached, and the basic structure is a one-dimensional structure (mainly only in the length direction), a two-dimensional structure. It can be a three-dimensional structure (mainly having only an area). The detection region set outside the conductive member is determined by the output of the conductive member and the wavelength of the microwave, but is usually set to an arbitrary distance within 50 cm, preferably within 30 cm. The oscillation circuit sets a feeding point and a receiving point on the conductive member, amplifies the frequency obtained from the receiving point, and feeds back the frequency to the feeding point, thereby self-oscillating the microwave. Anything can be used. Further, the detection as the change in the frequency obtained from the oscillation circuit as the change in the detection region is detected as the change in the frequency obtained from the oscillation circuit as a change in the detection target (dielectric material) such as a person near the conductive member. The frequency change may be detected as a pattern, or may be determined by comparison with a predetermined threshold value.

  The feeding point and the receiving point of the conductive member are points estimated or corrected by simulation or simulation and actual machine, and the oscillation frequency and detection region are set in the same manner.

  The proximity sensor according to claim 2 includes a conductive member that can be integrated with or separated from an attachment target, a detection region set outside the conductive member, a feeding point and a power receiving point on the conductive member, By amplifying the frequency obtained from the power receiving point and returning the frequency to the feeding point, microwaves are automatically generated using the conductive member as an antenna at a frequency with a sufficiently short wavelength relative to the size of the conductive member. An oscillation circuit comprising a band-pass filter having a frequency obtained from the power receiving point for excitation oscillation as a specific frequency region, a high frequency amplifier for amplifying and feeding back the frequency in the frequency region to the power feeding point, and power feeding from the power receiving point A directional coupler connected to the path between the points to detect the oscillation state of the oscillation circuit, and a feedback state generated by the directional coupler for down-conversion A mixer for mixing detected by entering the frequency, the frequency being passed through the mixer, in which includes a recognizing circuit to changes in the detection region.

Therefore, the frequency of the specific frequency region is set from the power receiving point of the conductive member through the bandpass filter, and the frequency in the frequency region is amplified by the high frequency amplifier and fed back to the feeding point of the conductive member. As a result, an oscillation circuit whose antenna is an electrically conductive member is formed, and the microwave self-oscillates. An electromagnetic wave is radiated from the conductive member to the detection region, and a specific frequency state radiated from the conductive member, that is, a plurality of frequencies is in a resonance state due to the relationship between the detection region and the conductive member. Even if the oscillation frequency of the oscillation circuit is radiated from the conductive member, if the detection target that causes reflection or absorption is not in the detection region, the oscillation frequency does not vary.

  However, when a detection target (dielectric material) such as a person approaches a detection region that is an electromagnetic wave radiation space, a microwave cavity oscillator is formed between the conductive member and the detection target and radiates from the conductive member. The resonance frequency state to be changed is changed. That is, when a detection target such as a person approaches the conductive member, the electric field in the detection region is reflected or absorbed by the detection target, and the field of the electromagnetic radiation space changes, which is detected by the directional coupler, and the mixer The frequency for down-conversion is input to the, and the change in the detection area is recognized according to the frequency passed through the mixer. Here, the electromagnetic wave radiation space does not mean the reach distance of the electromagnetic wave, but means a detectable detection region.

  Here, the recognition circuit detects a change in a detection target such as a person near the conductive member as a detection region as a change in frequency obtained from the oscillation circuit, and detects the change in frequency as a pattern. Alternatively, it can be determined by comparison with a predetermined threshold. The band-pass filter removes frequency noise (including low-frequency removal) extracted from the feeding point of the conductive member, and determines a predetermined frequency band of the microwave. The mixer mixes the frequency (f) obtained from the feeding point of the conductive member and the frequency (fo) obtained from the oscillator, and down-converts the mixing frequency (mf + nfo; where m and n are −∞. (Integer of ~ + ∞).

  Further, the recognition circuit normally recognizes a change in the detection area, which is the electromagnetic wave radiation space, as a change in oscillation frequency by a frequency pattern, and compares it with a reference frequency pattern corresponding to a known distance, size, etc. By performing the above, the distance, size, etc. of the detection target (dielectric material) are detected linearly, and the movement speed can also be detected by introducing a temporal element as a change in the reference frequency pattern. This recognition circuit only needs to be composed of an analog circuit or a digital circuit. Specifically, it is composed of an FV converter, an FFT, etc. and a memory.

  In the proximity sensor according to the third aspect, the conductive member that can be integrated with or separated from the attachment object is an opening / closing body that can be freely opened / closed with respect to the vehicle. Can be manufactured.

  The proximity sensor according to claim 1 sets a feeding point and a receiving point on a conductive member that can be integrated with or separated from an attachment target, amplifies the frequency obtained from the receiving point, and feeds back the frequency to the feeding point. By changing the size of the conductive member, an oscillation circuit that oscillates microwaves using the conductive member as an antenna at a frequency that is sufficiently short with respect to the size of the conductive member, and a change in the detection region set outside the conductive member This is detected as a change in frequency obtained from the oscillation circuit.

Therefore, the detection target and the conductive member function as an antenna between the detection target and the conductive member in the detection region that is an electromagnetic wave radiation space, and they are regarded as a microwave cavity resonator. Since the microwave oscillation frequency changes depending on the detection region and the detection target, the cavity resonator of the electric field strength (magnetic field) between the conductive members is large in the electromagnetic field. It becomes difficult to be affected by the capacitance of the detection target.

  In particular, between the object to be detected in the detection region where the microwave oscillation circuit is an electromagnetic wave radiation space and the conductive member, both function as an antenna, and the mutual influence of the electric and magnetic fields of the electromagnetic wave is greater. Can be regarded as a cavity resonator of the electric field strength (magnetic field) between the antennas, and is less affected by the capacitance of the detection target in the detection region, so that the detection accuracy is improved. In addition, the use of microwaves with a frequency of 300 MHz to 300 GHz enables detection that is not affected by the atmosphere such as humidity, temperature, water vapor, pressure, etc. in the detection area compared to the conventional capacitance detection type. Therefore, the device is inexpensive. Unlike the Doppler detection using microwaves, detection can be performed even if the detection target in the detection region is not moved.

  Therefore, it is easy to detect a short distance, and it is possible to detect a state that can be manufactured at low cost.

  The proximity sensor according to claim 2 sets a power feeding point and a power receiving point on a conductive member that can be integrated with or separated from an attachment target, amplifies a frequency obtained from the power receiving point, and feeds back the frequency to the power feeding point. By doing so, microwaves are oscillated using the conductive member as an antenna at a frequency having a sufficiently short wavelength with respect to the size of the conductive member. At this time, a specific oscillation state is obtained by a band-pass filter having a frequency obtained from the power receiving point of the conductive member as a specific frequency region and a high-frequency amplifier that amplifies and feeds back the frequency in the frequency region to the feeding point. . A change in the detection region set outside the conductive member is identified by a recognition circuit by a directional coupler that is connected to a path between the power reception point and the power supply point and detects an oscillation state of the oscillation circuit. The microwave oscillation frequency is determined by mixing the feedback state generated by the directional coupler with a mixer that receives the down-conversion frequency and determining the change in the detection region by the frequency that has passed through the mixer. To do.

  That is, the oscillation frequency of the microwave is taken out through the directional coupler, and the pattern of the oscillation frequency is judged. This detected oscillation frequency pattern is stored as a reference frequency pattern corresponding to the distance, size, etc. of the detection target, and compared with the data detected through the directional coupler. Detection of distance, size, etc.

  At this time, when the detection target does not exist in the detection region, if the oscillation frequency radiated from the conductive member is simply set to a specific threshold value, the detected frequency is changed from the threshold value to change the field of the detection region. As a change, the detection target can be detected by “1” and “0”.

  Since the proximity sensor according to claim 3 is an open / close body that can be attached to the vehicle so as to be openable and closable, the conductive member that is integrally or separably attached to the vehicle. In addition to the effects described, the structure can be simplified and inexpensively manufactured.

(Example)
Next, a proximity sensor according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall configuration conceptual diagram of a vehicle equipped with a proximity sensor according to an embodiment of the present invention, and FIG. 2 is a functional block diagram of the proximity sensor according to the embodiment of the present invention.

  In the figure, a band-pass filter 24, a high-frequency amplifier 25, and a directional coupler 28 are connected in series from the power receiving point b to the outer panels 11 to 14 made of metal plates (conductive) of each door of the vehicle 1 to supply power. Connected to point a.

  The band-pass filter 24 removes noise having a frequency reflected or absorbed from the outer panels 11 to 14 and limits it to a frequency region of a specific oscillation frequency. The high frequency amplifier 25 amplifies the output of the band pass filter 24. That is, the frequency in a specific frequency region of the microwave that has passed through the band-pass filter 24 from the power receiving point b of the outer panels 11 to 14 is amplified by the high frequency amplifier 25 and supplied to the feeding point a. The specific frequency from the power feeding point a to the power receiving point b is amplified by the high frequency amplifier 25 and fed back to the power feeding point a.

  That is, white noise is present at the power receiving point b due to noise from the external environment or the like or thermal noise of the high frequency amplifier 25. Therefore, the oscillation state is entered under the condition that the gain is greater than 1 and the phase of the signal is 360 degrees based on this noise.

  Here, the directional coupler 28 enables output from the band-pass filter 24 through the high-frequency amplifier 25 to the power feeding point a, and is supplied from the power receiving point b of the oscillator 22 of the outer panels 11 to 14 to the power feeding point a. Detect frequency. The mixer 23 mixes the frequency (f) in the feedback state generated by the directional coupler 28 and the frequency (fo) obtained from the oscillator 22, and specifically, the mixing frequency (mf + nfo) is obtained by mixing. Is what you get. The S meter (signal meter) 26 detects the output (amplitude of specific frequency, frequency transition) of the mixing frequency (f + fo) with the feedback state frequency (f) generated by the directional coupler 28. Yes. As a result, the change in the frequency (f) in the feedback state caused by the directional coupler 28 is mixed by the oscillator (fo), and the extracted frequency change or wave change is detected by the S meter 26. .

  In addition, the outer panels 11-14 of each door of this embodiment comprise the electroconductive member of this Embodiment.

  In the present embodiment, the case where the outer panels 11 to 14 of each door are antennas will be described, but front and rear bumpers, trunk lids, engine hoods, front doors, back doors, slide doors, swing doors, etc. The movable hood, sunroof, and the like can also be used as the conductive member of the present embodiment, similarly to the outer panels 11-14.

  In addition, the feeding point a and the receiving point b of the outer panels 11 to 14 of each door are points estimated or corrected by simulation or simulation and actual machine, and the radiation frequency is set in the same manner. Usually, the frequency is 300 MHz. It is set to oscillate a microwave of ˜300 GHz.

  The oscillator 22 is an oscillation circuit that outputs a fundamental frequency for down-converting the frequency of radiating microwaves using the outer panels 11 to 14 as antennas with respect to the size of the outer panels 11 to 14 of each door.

  Here, by setting the feeding point a and the receiving point b on the outer panels 11 to 14, amplifying the frequency obtained from the receiving point b, and returning the frequency to the feeding point a, the size of the outer panels 11 to 14 is increased. On the other hand, the oscillation circuit 10 that oscillates microwaves with the outer panels 11 to 14 as antennas at a frequency with a sufficiently short wavelength is configured, A resonator is constituted by the detection regions 11A to 14A which are electromagnetic wave radiation spaces. The detection regions 11A to 14A are set outside the distance corresponding to the half wavelength of the frequency of the radiated microwave with respect to the outer panels 11 to 14.

  When implementing the present invention, the oscillator 22 is sufficient for the size of the outer panels 11 to 14 when the detection target 31 is present in the detection regions 11A to 14A that are radio wave radiation spaces and when the detection target 31 is not present. Since the oscillation frequency determined by the oscillation circuit 10 that oscillates microwaves with the outer panels 11 to 14 as antennas at a short wavelength changes, the change in the frequency (f) of the oscillation frequency radiated from the outer panels 11 to 14 changes. This is to detect and down-convert the frequency (f) of the oscillation frequency radiated from the outer panels 11-14.

  The mixer 23 mixes the frequency (f) in the feedback state generated by the directional coupler 28 and the frequency (fo) obtained from the oscillator 22. More specifically, the mixer 23 mixes the mixing frequency ( mf + nfo). The S meter (signal meter) 26 detects a change in the oscillation frequency of the mixing frequency (f + fo) with the feedback state frequency (f) generated by the directional coupler 28. As a result, the change in the frequency (f) in the feedback state caused by the directional coupler 28 is mixed by the oscillator (fo), and the extracted frequency is detected by the S meter 26.

  At this time, when the detection target 31 does not exist, the frequency of the resonator formed by the outer panels 11 to 14 functioning as antennas and the detection regions 11A to 14A that are electromagnetic wave radiation spaces around the outer panels 11 to 14 is the same. The S meter 26 is monitored so as to be equal to or greater than a predetermined threshold value. However, if the detection target 31 exists, the oscillation frequency between the outer panels 11 to 14 and the detection regions 11A to 14A changes due to the state change of the detection regions 11A to 14A that are electromagnetic wave radiation spaces. The output is less than a predetermined threshold.

  In this way, the mixer 23 mixes and down-converts the feedback state frequency (f) generated by the directional coupler 28 and the frequency (fo) obtained from the oscillator 22, and the S meter 26 sets the specific frequency. The output is being measured. When the detection target 31 such as a person approaches or exists due to a change in the output of a specific frequency (frequency shift, amplitude of the specific frequency) by monitoring the signal meter 26, the detection target 31 and the outer panels 11 to 14 are connected to the antenna. The considered antennas are coupled to each other and detected as a frequency change.

  Further, the recognition circuit 27 detects the detection regions 11A to 14A, which are electromagnetic wave radiation spaces, by using a signal obtained by passing an output such as a frequency shift passed through the bandpass filter 24, a specific frequency or an amplitude of each frequency through the S meter 26. This change in the detected frequency is obtained by measuring a state corresponding to the distance, size, etc. as reference frequency pattern information in advance, and calculating the distance, size, etc. from the reference frequency pattern. By estimating, distance, size, etc. are detected. Further, the moving speed can be determined by changing the reference frequency pattern with time. At this time, the reference frequency pattern of people, objects, sizes, etc. is compared with reference frequency pattern data in which the characteristics, the frequency, the magnitude of amplitude, and the rate of change thereof are mapped in the recognition circuit 27. to decide. According to this method, it is possible to distinguish between a change in the automatic opening / closing operation of the door and an approaching state with a stationary or moving person or object.

  The recognition circuit 26 inputs its output to the electronic control circuit 2. In this embodiment, the electronic control circuit 2 is composed of a microcomputer that executes obstacle detection of the door opening / closing system. When the door is opened / closed, whether the door can be opened / closed safely or whether there is no obstacle is determined. When the determination is made and a person or a structure is detected, the opening / closing of the door is stopped or an alarm sound is generated in the vehicle 1.

  At this time, the oscillator 22, the mixer 23, the band-pass filter 24, the high-frequency amplifier 25, the directional coupler 28, and the S meter 26 that constitute the proximity sensor of the present embodiment are the outer panels 11 to 14 of each door of the vehicle 1. And an inner panel (not shown). The output of the S meter 25 is input to the recognition circuit 26 and the electronic control circuit 2. In this embodiment, the electronic control circuit 2 is a microcomputer that executes an obstacle detection device of a door opening / closing system.

  As described above, the proximity sensor according to the present embodiment includes the outer panels 11 to 14 (conductive members) that can be integrated with or separated from the mounting target such as the vehicle 1 and the detection region 11A set outside the outer panels 11 to 14. To 14A and the outer panels 11 to 14, the feeding point a and the receiving point b are set, the frequency obtained from the receiving point b is amplified, and the frequency is amplified and fed back to the feeding point a. A bandpass filter 24 having a frequency obtained from a power receiving point b that oscillates microwaves with the outer panels 11 to 14 as antennas at a frequency having a sufficiently short wavelength for a size of 11 to 14 and a frequency region Is connected to a path between the power receiving point b and the power feeding point a to detect the oscillation state of the oscillation circuit 10. The directional coupler 28, the mixer 23 that detects the mixing state of the feedback state generated by the directional coupler 28 by inputting a frequency for down-conversion, and the frequency of the detection regions 11 </ b> A to 14 </ b> A depending on the frequency passed through the mixer 23. And a recognition circuit 27 for recognizing a change.

Accordingly, a frequency in a specific frequency region is set from the power receiving point b of the outer panels 11 to 14 through the bandpass filter 24, and the frequency in the frequency region is amplified by the high frequency amplifier 25 and supplied to the feeding point a of the outer panels 11 to 14. . As a result, an oscillation circuit 10 having the outer panels 11 to 14 as antennas is formed, and oscillates microwaves. Electromagnetic waves are radiated from the outer panels 11 to 14 to the detection areas 11A to 14A, and a specific frequency state radiated from the outer panels 11 to 14 in relation to the detection areas 11A to 14A and the outer panels 11 to 14, that is, Multiple frequencies are in resonance. Even if the oscillation frequency of the oscillation circuit 10 is radiated from the outer panels 11 to 14, if the detection object 31 that causes reflection or absorption is not in the detection regions 11A to 14A, the oscillation frequency does not fluctuate.

  However, when the detection target 31 such as a person approaches the detection areas 11A to 14A that are electromagnetic radiation spaces, a microwave resonator is formed between the outer panels 11 to 14, and the outer panels 11 to 14 The radiated resonance frequency state changes. That is, when the detection target 31 such as a person approaches the outer panels 11 to 14, the electric field in the detection regions 11 </ b> A to 14 </ b> A is reflected or absorbed by the detection target 31, and the field of the electromagnetic wave radiation space changes, and the directionality is changed. A detection frequency is detected by the coupler 28, and a down-conversion frequency is input to the mixer 23, and changes in the detection regions 11 </ b> A to 14 </ b> A are recognized based on the frequency passed through the mixer 23.

  The oscillation frequency of the oscillation circuit 10 is obtained by mixing the feedback state generated by the directional coupler 28 with the mixer 23 to which the frequency for down-conversion is input, and the detection regions 11A to 14A depending on the frequency that has passed through the mixer 23. The change is judged by the recognition circuit 27. That is, the frequency of the oscillation circuit 10 is taken out through the directional coupler 28, and the pattern of the existence of the oscillation frequency (signal meter output) is determined. This detected frequency pattern stores a change in frequency corresponding to the distance, size, etc. of the detection objects 11A to 14A as a reference frequency pattern in advance, and the known reference frequency pattern and the detected frequency are stored. In comparison, the distance, size, etc. of the detection target 31 are detected from the reference frequency pattern.

  At this time, when the detection target 31 does not exist in the field of the detection regions 11A to 14A, the outer panels 11 to 14 can be set to be equal to or higher than the threshold value of the specific oscillation frequency radiated from the outer panels 11 to 14. When it becomes less than the threshold value of the specific oscillation frequency radiated from, the detection object 31 can be detected as a change in the field of the detection regions 11A to 14A.

  The feeding points of the outer panels 11 to 14 are points estimated or corrected by simulation or simulation and actual equipment, and the radiation frequency is set similarly.

  The band pass filter 24 removes noise (including low frequency removal) of the frequency taken out from the power receiving point b of the outer panels 11 to 14, and the mixer 23 receives the power receiving point b of the outer panels 11 to 14. The frequency (f) obtained from the above and the frequency (fo) obtained from the oscillator may be mixed to obtain a mixing frequency (mf + nfo; where m and n are integers from −∞ to + ∞).

  Furthermore, the recognition circuit 27 normally recognizes changes in the detection regions 11A to 14A, which are electromagnetic wave radiation spaces, as changes in the oscillation frequency, and compares them with reference frequency patterns corresponding to known distances, sizes, and the like. It is possible to detect the distance, size, etc. by doing so, as long as it is constituted by an analog circuit or a digital circuit.

  In particular, when a microwave resonator is formed between the outer panels 11 to 14 and the detection areas 11A to 14A serving as an electromagnetic wave radiation space, and the detection target 31 exists in the detection areas 11A to 14A, the outer panel It can be considered as a cavity resonator between antennas having the antennas 11 to 14 and the detection target 31 as antennas, and the mutual influence of the electric field / magnetic field of the electromagnetic wave becomes larger, and the detection target 31 of the detection regions 11A to 14A Since it becomes difficult to be influenced by the capacitance, the detection accuracy is improved.

  Therefore, the electronic control circuit 2 that inputs the output of the recognition circuit 27 is a microcomputer that executes the obstacle detection device of the door opening and closing system in this embodiment, and when the door outer panels 11 to 14 are opened, When a person or an object approaches the outer panels 11 to 14 of the door, the opening of the door can be stopped or the state can be notified. Further, even in the operation in the door closing direction, it is possible to prevent a collision with a person or an object.

  Moreover, although the antenna of this Embodiment is made into the outer panels 11-14 of the door of the vehicle 1, the conditions of the outer panels 11-14 change by opening and closing of a door, and the state of detection region 11A-14A Even in this case, the detection regions 11A to 14A can be set under any condition depending on the frequency emitted by the oscillator 22. In particular, when the door of the vehicle 1 is an antenna, it can be used as a sensor for an obstacle detection device, a security system, a keyless entry system, etc. of a door opening / closing system, and the field of the electromagnetic radiation space can be used as an outer panel of the door of the vehicle 1. It can also be set within 11 to 30 cm.

  As described above, the proximity sensor according to the above-described embodiment includes the conductive member including the outer panels 11 to 14 attached to the vehicle 1 so as to be integrated or separable, and the detection regions 11 </ b> A to 11 </ b> A set outside the outer panels 11 to 14. 14A and the outer panels 11 to 14 are set with a feeding point a and a receiving point b, the frequency obtained from the receiving point b is amplified, and the frequency is fed back to the feeding point b. And an oscillation circuit 10 that oscillates microwaves using the outer panels 11 to 14 as antennas at a frequency with a sufficiently short wavelength with respect to the size, and changes in the detection regions 11A to 14A are obtained from the oscillation circuit 10. Is detected.

Therefore, the oscillation circuit 10 having the outer panels 11 to 14 as antennas oscillates, and electromagnetic waves are radiated from the outer panels 11 to 14 to the detection areas 11A to 14A. The relationship between the detection areas 11A to 14A and the outer panels 11 to 14 Thus, a resonance state of a specific frequency state radiated from the outer panels 11 to 14 is obtained. Even if the oscillation frequency of the oscillation circuit 10 is radiated from the outer panels 11 to 14, if the detection target 31 that causes reflection or absorption is not in the detection region, the frequency variation of the oscillation frequency does not occur. However, when the detection target 31 such as a person approaches the detection areas 11A to 14A that are electromagnetic radiation spaces, a microwave cavity oscillator is formed between the detection target 31 and the outer panels 11 to 14 as an antenna. The resonance frequency state radiated from the outer panels 11 to 14 changes. That is, when the detection target 31 such as a person approaches the outer panels 11 to 14, the electric fields in the detection regions 11 </ b> A to 14 </ b> A are reflected or absorbed by the detection target, and the field of the electromagnetic wave radiation space changes. By detecting this, the approach of the detection target 31 can be detected.

  Here, the outer panels 11 to 14 may be any conductor that can be integrated with or separated from the mounting target. The detection regions 11A to 14A set outside the outer panels 11 to 14 are determined by the outer panels 11 to 14 and the wavelength of the microwave, but are usually set to an arbitrary distance within 1 m. Then, the oscillation circuit 10 sets a feeding point a and a receiving point b on the outer panels 11 to 14, amplifies the frequency obtained from the receiving point b, amplifies the frequency to the feeding point a, and feeds it back. Anything that can oscillate microwaves may be used. Further, the change in the detection regions 11A to 14A as the change in the frequency obtained from the oscillation circuit 10 was obtained from the oscillation circuit 10 as the change in the detection target 31 such as a person near the outer panels 11 to 14. This is detected as a change in frequency, and the change in frequency may be detected as a pattern, or may be determined by comparison with a predetermined threshold.

Therefore, when a microwave resonator is formed between the detection regions 11A to 14A serving as the electromagnetic wave radiation space and the detection target 31 exists in the detection regions 11A to 14A, the outer panels 11 to 14 and the detection target 31 are present. Since the oscillation frequency of the microwave changes depending on the detection regions 11A to 14A and the detection target 31, the influence of the electromagnetic field on the electric field and the magnetic field is mutually influenced. And is less susceptible to the capacitance of the detection objects 11A to 14A in the electromagnetic wave radiation space.

  In particular, the microwave oscillation circuit 10 can be regarded as a cavity resonator between the detection areas 31A to 14A in which the electromagnetic wave radiation space is an electromagnetic wave radiation space, and the mutual influence of the electric field / magnetic field of the electromagnetic wave. Becomes larger and is not easily affected by the capacitance of the detection target 31 in the detection regions 11A to 14A, so that the detection accuracy is improved. In addition, by using microwaves with a frequency of 300 MHz to 300 GHz, detection is not affected by the atmosphere of the detection regions 11A to 14A such as humidity, temperature, water vapor, pressure, etc., compared to the conventional capacitance detection type. Therefore, the apparatus becomes inexpensive. Unlike the Doppler detection using microwaves, detection is possible even if the detection target 31 in the detection regions 11A to 14A is not moving.

  Therefore, it is easy to detect a short distance, and it is possible to detect a state that can be manufactured at low cost.

  That is, the oscillation frequency of the microwave is taken out through the directional coupler 28, and the pattern of the oscillation frequency is judged. The detected oscillation frequency pattern is stored as a reference frequency pattern corresponding to the distance, size, etc. of the detection object, and compared with the data detected through the directional coupler 28, and the detection object is detected from the reference frequency pattern. The speed, such as the distance, size, etc., is detected as necessary.

  At this time, when the detection target 31 does not exist in the detection regions 11A to 14A, if a specific oscillation frequency radiated from the outer panels 11 to 14 is simply set as a threshold value, the detected frequency is determined from the threshold value. According to the change, detection of the detection target can be detected as ON / OFF as a change in the field of the detection region.

  The use of microwaves having a frequency of 300 MHz to 300 GHz enables detection that is not affected by the atmosphere of the detection regions 11A to 14A such as humidity, temperature, water vapor, pressure, etc., so that the apparatus is inexpensive. Therefore, it is easy to detect a short distance, and it is possible to detect a state that can be manufactured at low cost.

  Since the present invention enables detection of a short distance of the detection target 27 without being affected by the atmosphere such as humidity, temperature, water vapor, pressure, etc. of the electromagnetic wave radiation space, an obstacle detection device for a door opening / closing system, a security system, In addition to sensors such as keyless entry systems, various short distances are not affected by changes in weather conditions such as humidity changes in the natural air compared to conventional capacitance detection type. It can be used as a sensor for detecting.

  The proximity sensor according to the embodiment of the present invention of this type can be used not only for a vehicle but also for a proximity sensor for a shower toilet that detects the movement and presence of a human body, and its use is not limited to a vehicle. Absent. For example, it can be generalized like a proximity sensor of a shower toilet that detects the movement and presence of a human body. At this time, for example, the outer panels 11 to 14 may function as an antenna. Other configurations are not different from the above embodiment. For example, the outer panels 11 to 14 that are integrally or separably attached to the object to be attached are not limited to planar panels, and can be formed into a shape obtained by processing a strip or a linear member.

FIG. 1 is a conceptual diagram of the overall configuration of a vehicle equipped with the proximity sensor according to the first and second embodiments of the present invention. FIG. 2 is a functional block diagram of the proximity sensor according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle 10 Oscillation circuit 11-14 Outer panel (conductive member)
11A to 14A Detection area 22 Oscillator 23 Mixer 24 Band pass filter 26 S meter 27 Recognition circuit 31 Detection target

Claims (3)

A conductive member that can be integrated with or separated from the mounting target;
A detection region set outside the conductive member;
By setting a feeding point and a receiving point on the conductive member, amplifying the frequency obtained from the receiving point, and returning the frequency to the feeding point, a wavelength sufficient for the size of the conductive member. An oscillation circuit that oscillates microwaves using the conductive member as an antenna at a short frequency,
A proximity sensor that detects a change in the detection region as a change in frequency obtained from the oscillation circuit. A conductive member that can be integrated with or separated from the mounting target;
A detection region set outside the conductive member;
By setting a feeding point and a receiving point on the conductive member, amplifying the frequency obtained from the receiving point, and returning the frequency to the feeding point, a wavelength sufficient for the size of the conductive member. A bandpass filter having a frequency obtained from the power receiving point that oscillates microwaves with the conductive member as an antenna at a short frequency, and a frequency in the specific frequency region and a frequency in the frequency region are amplified and fed back to the feeding point. An oscillation circuit comprising a high-frequency amplifier;
A directional coupler connected to a path between the power receiving point and the power feeding point and detecting an oscillation state of the oscillation circuit;
A mixer that detects mixing by inputting a frequency for down-conversion of the feedback state generated by the directional coupler;
A proximity sensor comprising: a recognition circuit that recognizes a change in the detection region based on a frequency passed through the mixer.   The proximity sensor according to claim 1, wherein the conductive member that can be integrated with or separated from the attachment target is an opening / closing body that is attached to the vehicle so as to be freely opened and closed.

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