JP2005121541A - Proximity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a proximity sensor easy to detect a short distance, and capable of producing it economically. <P>SOLUTION: The sensor comprises outer panels 11-14 attached to a vehicle 1, detection regions 11A-14A set on the outside of the outer panels 11-14, and the UWB oscillator 21 for outputting microwave wide band frequencies for radiating the sufficiently short wave frequency using the outside panels 11-14 as an antenna, wherein a resonance circuit between the outer panels 11-14 and the detection object 31 in the detection regions 11A-14A is completed, thereby detecting the change in the detection regions 11A-14A from the difference of frequency propagation fed from the feeding point (a) of the UWB oscillator 21. <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-range state, and relates to a proximity sensor that uses a UWB oscillator that outputs a wideband frequency of a microwave. Is.

  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 member, 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, an object of the present invention is to provide a proximity sensor that can be detected with high accuracy without malfunction due to environmental changes due to changes in rain or humidity.

  The proximity sensor according to claim 1 has a wavelength sufficient for a conductive member that is integrally or separably attached to an attachment target, a detection region that is set outside the conductive member, and a size of the conductive member. A UWB oscillator that supplies a microwave wideband frequency that radiates the conductive member as an antenna at a short frequency, and forms a resonance circuit between the conductive member and a detection target in the detection region. The change in the detection region is detected from the difference in the propagation state of the frequency supplied from the feeding point of the UWB oscillator.

  Therefore, a microwave resonance circuit is formed between the detection target in the detection region and the conductive member, and the microwave is supplied to the conductive member by the UWB oscillator. The resonance circuit formed by the detection target of the detection region and the conductive member is in a resonance state at a plurality of resonance frequencies supplied by the UWB oscillator, but is reflected or absorbed at other frequencies and detected in the detection region. If the target exists, the propagation state of the frequency supplied from the UWB oscillator changes accordingly, so that the presence or absence of the detection target can be detected. That is, if there is a detection target in the detection region, the resonance circuit changes the propagation state of the frequency supplied from the UWB oscillator, so that the detection target can be determined by detecting it.

  Here, the UWB oscillator is a resonant circuit formed between the conductive member and a detection target in the detection region using the conductive member as an antenna at a frequency having a sufficiently short wavelength with respect to the size of the entire conductive member. The electromagnetic wave is supplied to the sensor, and the existence of the detection target is known from the propagation state of the supplied frequency. Incidentally, UWB (Ultra Wide Band) is a technique for transmitting signals without modulation by using a collection of impulse trains with a very narrow pulse width as a wideband frequency without using a carrier wave as in the current communication technology. Of course, the occupied frequency band is wider than the frequency used in the conventional communication technology. The US FCC (Federal Communications Commission) defines UWB, which exhibits the frequency-output characteristics shown in FIG.

In FIG. 6, Δf / fc = 2 (fH−fL) / (fH + fL) ≧ 20%,
Alternatively, Δf = fH−fL ≧ 500 MHz is defined. UWB in the case of carrying out the present invention has the same meaning as the above definition.

  In addition, the conductive member that is integrally or separably attached to the object to be attached is not limited to a planar panel as the conductive member that is integrally or separably attached to the object to be attached. It can be made into the shape which processed the member.

  The feeding point of the conductive member is set as a point roughly estimated by simulation and actual measurement. The reference oscillator is an oscillator that determines a mixing frequency, and may be an ordinary microwave oscillator.

  The detection of the change in the detection region of the proximity sensor according to claim 2 is performed by amplifying the frequency of the conductive member by amplifying means after passing through a directional coupler and a bandpass filter connected to a feeding point of the UWB oscillator. In addition, it is performed using a mixer that inputs and mixes a frequency for down-conversion and a recognition circuit that detects a change in the detection region based on the frequency passed through the mixer.

  When there is no detection target, the transfer function of a specific frequency obtained from the conductive member hardly fluctuates. In other words, a resonance state occurs at a plurality of resonance frequencies supplied by the UWB oscillator, but reflection or absorption occurs at other frequencies, and if there is no detection target in the detection region, propagation of the frequency supplied from the UWB oscillator is performed. The state is uniquely determined. However, if the detection target exists in the detection region, the transfer function of each frequency component supplied from the UWB oscillator changes accordingly, so that the presence or absence of the detection target can be detected. At this time, the microwave radiated from the conductive member is extracted as a frequency in which each wavelength component (frequency component) affected by the detection target is removed from the noise through the bandpass filter, and is further mixed with the frequency of the reference oscillator. Then, down-conversion is performed, and the frequency pattern of each detected frequency is determined. This detected frequency pattern can detect the distance to be detected, its size, and the like by comparison with a known frequency pattern.

  Here, the recognition circuit for detecting the change in the detection region performs frequency analysis on the frequency component based on the propagation state using FFT (Fast Fourier Transform) used for frequency analysis, The distribution state of the frequency component may be determined. Further, an FV converter (frequency voltage converter) may be used.

  The directional coupler is a circuit connected to the UWB oscillator and its feeding point, introduced to the band-pass filter side connected to the feeding point of the conductive member, and blocking the movement in the opposite direction.

  The detection of the change in the detection region of the proximity sensor according to claim 3 is performed by introducing the frequency of the conductive member from one or more individually received power receiving points and inputting a frequency for down-conversion. Then, the mixing is performed using a mixer that performs mixing, and a recognition circuit that detects a change in the detection region based on the frequency that has passed through the mixer.

  When a detection target such as a person approaches the conductive member, the electric field of the electromagnetic wave is reflected or absorbed by the detection target, and the transfer function of each frequency changes. At this time, the transfer function of each wavelength component (frequency component) affected by the detection target from the conductive member is a frequency obtained by removing noise from one or more individually disposed power receiving points of the conductive member through a bandpass filter. It is extracted, mixed with the frequency of the reference oscillator, down-converted, and the frequency pattern of each detected frequency is determined. The detected frequency pattern can detect the distance, size, etc. of the detection target by comparison with a known frequency pattern. In particular, in the case where a power receiving point having two or more individually disposed power receiving points is provided, a plurality of transfer function states can be used.

  For example, when the size of the conductive member is large, the detection sensitivity may decrease, because the electromagnetic wave is radiated from the feeding point and the distance when returning (to the receiving point) again becomes longer. In addition, the signal may be attenuated. Therefore, by providing a plurality of power receiving points, the sensitivity can be further improved and the S / N ratio can be ensured.

  A proximity sensor according to a fourth aspect of the present invention includes a conductive member that is integrally or separably attached to an attachment target, a detection region that is set outside the conductive member, and a wavelength sufficient for the size of the conductive member. Comprises a UWB oscillator that outputs a wideband frequency of microwaves that radiate the conductive member as an antenna at a short frequency, and forms a resonance circuit between the conductive member and a detection target in the detection region. From the change in the propagation state of the frequency supplied from the feeding point of the UWB oscillator, for example, the change in the detection region and the moving body speed are detected as the change in the frequency pattern and the Doppler shift of each frequency.

  A microwave resonance circuit is formed between a detection region, which is an electromagnetic wave radiation space, and a conductive member. When microwaves are supplied from the UWB oscillator to the detection region, the detection target and the conductive member are formed in the detection region. The resonant circuit is in a resonance state at a plurality of resonance frequencies supplied by the UWB oscillator, but reflects or absorbs at a plurality of other frequencies, and if a detection target exists in the detection region, it is supplied from the UWB oscillator. Since the propagation state of the selected frequency changes, the presence / absence of the detection target can be detected. Further, the moving speed of the detection target can be detected by Doppler shift of individual frequencies in the propagation state. For example, when a detection target such as a person approaches the conductive member, the electric field of the electromagnetic wave is reflected or absorbed by the detection target, the propagation state changes, and the field of the detection region changes. At this time, the frequency detected from the conductive member has each wavelength component (frequency component) affected by a detection target such as a person, and thus appears as a change in the frequency pattern according to the propagation state. Here, based on the change of the frequency pattern of the conductive member, the frequency pattern including the detected change speed and the Doppler shift of each frequency is compared with a known reference frequency pattern, and the distance and magnitude from the reference frequency pattern are compared. It is possible to detect the moving speed and the like.

  That is, since a UWB oscillator that outputs microwaves is a wide band, a resonance circuit determined by a detection region that is a radio wave radiation space and a conductive member that functions as an antenna has a plurality of resonances supplied by the UWB oscillator. Resonance occurs at frequencies, reflection or absorption occurs at other frequencies, and their transfer functions change. Therefore, if there is a detection target in the detection region, the transfer function of the frequency radiated from the UWB oscillator changes compared to when the detection target does not exist, so the presence / absence of the detection target and the speed of movement thereof are detected. can do.

  The feeding point of the conductive member is set as a point roughly estimated by simulation and actual measurement. The reference oscillator is an oscillator that determines a mixing frequency, and may be an ordinary microwave oscillator.

  The change of the detection area of the proximity sensor and the recognition of the moving body speed of the proximity sensor according to claim 5 are mixed by introducing the frequency of the conductive member and inputting the frequency for down-conversion and the frequency of the UWB oscillator. A mixer, and a recognition circuit that detects a change in the detection region and a moving body speed as a change in a frequency pattern and a Doppler shift of each frequency according to the frequency passed through the mixer.

  Here, when a microwave resonance circuit is formed between a detection region which is an electromagnetic wave radiation space and a conductive member, and microwaves are supplied from the UWB oscillator, the detection target and the conductivity of the detection region are detected. The resonance circuit formed by the members is in a resonance state at a plurality of resonance frequencies supplied by the UWB oscillator, but reflects or absorbs at a plurality of other frequencies, so that their transfer functions change. At this time, since the frequency detected from the conductive member has a wavelength component (frequency component) that is affected by the detection target, the movement speed of the detection target is determined by the frequency pattern change speed or frequency shift. Can be detected. Based on the changing speed of the frequency pattern of the conductive member, the change speed of the detected frequency pattern is compared with the changing speed of a known reference frequency pattern, and the distance, size, moving speed, etc. from the reference frequency pattern are compared. Detection can also be performed.

  This recognition circuit normally recognizes a change of a transfer function to a detection region which is an electromagnetic wave radiation space by a UWB oscillator as a change of a frequency pattern, and the detected frequency pattern is recognized by a known distance, size, The distance, size, moving speed, and the like are detected by comparing with a reference frequency pattern corresponding to the moving speed and the like, and any analog circuit or digital circuit may be used. Specifically, it is composed of an FV converter, an FFT, etc. and a memory.

  A proximity sensor according to a sixth aspect of the present invention is an open / close body that can be attached to the vehicle so that the conductive member is integrally or separably attached to the vehicle so as to be openable and closable. Can be manufactured.

  In the proximity sensor according to claim 1, a UWB oscillator having a microwave frequency that forms a microwave resonance circuit between a detection target in a detection region and a conductive member, and radiates using the conductive member as an antenna, Microwaves are radiated there. At this time, a resonance state occurs at each of the plurality of resonance frequencies supplied by the UWB oscillator, and reflection or absorption occurs at the other plurality of frequencies, and their transfer functions change. By detecting this, the detection target can be determined.

  Therefore, for example, a microwave UWB oscillator that oscillates in a frequency band having a sufficiently short wavelength with respect to the size of the conductive member is connected to a feeding point, and a microwave impulse having a wide bandwidth is radiated. The radiated microwave impulse is radiated using the conductive member as an antenna. At this time, when the detection target does not exist outside the conductive member, the transfer function is uniquely determined according to the antenna characteristics. That is, the antenna characteristics are determined when considered as a transfer function for comparing the signal radiated from the antenna with the signal transmitted from the oscillator side.

  At this time, a microwave resonance circuit having a large influence between the electric field and the magnetic field of the electromagnetic wave is formed between the detection target of the detection region serving as the electromagnetic wave radiation space and the conductive member. The frequency of the UWB oscillator corresponding to the detection target is propagated. In particular, the use frequency of the microwave of the UWB oscillator makes the influence of the electric field and magnetic field of the electromagnetic wave large, and it becomes difficult to be affected by the capacitance of the detection target in the detection region. Compared with the type, it is possible to perform detection that is not affected by the atmosphere such as humidity, temperature, water vapor, pressure, etc. in the detection region, and the apparatus is inexpensive and the detection accuracy is improved. Further, unlike the detection of the Doppler frequency, detection is possible even if the detection target in the detection region is not moved. In particular, by using a UWB oscillator, there are many resonance frequencies that can be radiated from the conductive member, and the change in the propagation state is detected, so it can be carried out without special investigation of the characteristics of the conductive member. Standardization is also possible.

  The detection of the change in the detection region of the proximity sensor according to claim 2 is performed by amplifying the frequency of the conductive member by amplifying means after passing through a directional coupler and a bandpass filter connected to a feeding point of the UWB oscillator. And a mixer for inputting and mixing a frequency for down-conversion and a recognition circuit for detecting a change in the detection region based on the frequency passed through the mixer. In addition to the effect, if there is a detection target in the detection region, the electromagnetic wave of the frequency supplied from the UWB oscillator is radiated from the feed point, and when the detection target exists, the signal returning to the feed point changes. To do. The change is detected as a change in the transfer function. At this time, the frequency pattern that has passed through the detected bandpass filter is a frequency pattern from which noise has been removed. Further, the directional coupler can eliminate the influence of the reflection from the feeding point of the conductive member and the disturbance entering the feeding point from the outside on the output of the UWB oscillator, so that the UWB oscillator can stably oscillate. .

  The detection of the change in the detection region of the proximity sensor according to claim 3 is performed by introducing the frequency of the conductive member from one or more individually received power receiving points and inputting a frequency for down-conversion. Then, the mixing is performed using a mixer that performs mixing, and a recognition circuit that detects a change in the detection region based on the frequency that has passed through the mixer. Therefore, in addition to the effect of claim 1 or 2, the frequency pattern that has passed through the detected bandpass filter is based on a known reference pattern corresponding to the distance, size, etc. of the detection target in advance. Compared with the data stored as a frequency pattern, the distance, size, etc. of the detection target can be detected from the reference frequency pattern.

  In other words, the impulse signal that returns to the power receiving point can be regarded as a transfer function of antenna characteristics. When the detection target exists outside the conductive member, the conductive member and the detection target have an eigenvalue having a resonance frequency, so that the conductive member and the detection target are combined as an antenna, and one or two or more are arranged individually. It can be detected from the received power point as a difference in transfer function. From this, since the difference in the propagation state of the frequency supplied from the UWB oscillator changes depending on the presence or absence of the detection target in the detection region, it is detected as a Doppler shift of each frequency. Further, by providing a plurality of power receiving points, the detection resolution can be further improved and the S / N ratio can be secured.

  The proximity sensor according to claim 4 is a UWB oscillator having a microwave frequency that forms a microwave resonance circuit between a detection target in a detection region and a conductive member, and radiates the conductive member as an antenna. Microwaves are radiated there. At this time, a plurality of resonance frequencies supplied by the UWB oscillator are in a resonance state, and reflection or absorption occurs at other frequencies, and their transfer functions change depending on whether or not a detection target exists in the detection region. . Therefore, if a detection target exists in the detection region, the transfer function of the frequency supplied from the UWB oscillator changes. By detecting this as a Doppler shift of individual frequencies of the transfer function, the moving speed of the detection target can be determined.

  At this time, a microwave resonance circuit having a large mutual influence of the electric field and magnetic field of the electromagnetic wave is formed between the detection target of the detection region serving as the electromagnetic wave radiation space, and depending on the detection region and the detection target. The frequency of the UWB oscillator is propagated. In particular, the use of microwaves with a wide frequency range makes the electromagnetic field's electric field and magnetic field's mutual influence large, making it difficult to be affected by the capacitance of the detection target in the detection area. Compared with the type, it is possible to perform detection that is not affected by the atmosphere such as humidity, temperature, water vapor, pressure, etc. in the detection region, and the apparatus is inexpensive and the detection accuracy is improved. Further, the deviation and change speed of the propagation state are detected based on the deviation and change speed of the frequency pattern, and the detection target distance and moving speed can be detected. In particular, since there are a large number of resonance frequencies that can be radiated from the conductive member by using the UWB oscillator, it can be carried out without detailed investigation of the characteristics of the conductive member, and standardization is also possible.

  The proximity sensor according to claim 5 forms a microwave resonance circuit between a detection target in a detection region and a conductive member, and a UWB oscillator having a microwave frequency radiated by using the conductive member as an antenna, Microwaves are radiated there. At this time, resonance occurs at a plurality of resonance frequencies supplied by the UWB oscillator, reflection or absorption occurs at other frequencies, and their transfer functions change. Therefore, in addition to the effect of claim 4, since the frequency detected from the conductive member has a wavelength component (frequency component) influenced by the detection target, the frequency pattern change rate based on each frequency or The moving speed of the detection target can be detected by the frequency shift. Based on the changing speed or deviation of the frequency pattern of the conductive member, the Doppler shift of each frequency of the detected frequency pattern is compared with the changing speed or deviation of the known reference frequency pattern, and the reference frequency pattern It is also possible to detect distance, size, moving speed, etc.

  According to a sixth aspect of the present invention, the proximity sensor according to the sixth aspect is an open / close body that can be attached to the vehicle so as to be openable / closable. In addition to the effects described in one, the structure can be simplified and inexpensively manufactured.

[Embodiment 1]

  Next, a proximity sensor according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram of the overall configuration 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 Embodiment 1 of the present invention.

  1 and 2, the antenna terminals of the UWB oscillator 21 are electrically connected to the outer panels 11 to 14 made of a metal plate (conductive) of each door of the vehicle 1, and the bottom is a feeding point a. . The outer panels 11 to 14 of the doors are antennas that receive microwaves from the feeding point a and radiate microwaves on the surfaces thereof. The outer panels 11 to 14 of the doors are electrically conductive according to the present embodiment. Configure the member. In the present embodiment, the case where the outer panels 11 to 14 of the doors are antennas will be described, but the front and rear bumpers, trunk lid, engine hood, front door, back door, slide door, swing of the vehicle 1 Doors, other movable hoods, sunroofs and the like can also be used as the conductive panels of the present embodiment in the same manner as the outer panels 11 to 14, and among these, the front door, the back door, the slide door, the swing Both doors and the like can be regarded as an opening / closing body that can be freely opened and closed with respect to the vehicle.

  The UWB oscillator 21 outputs a wideband frequency of microwaves that can radiate the outer panels 11 to 14 as antennas at a frequency having a sufficiently short wavelength with respect to the size of the outer panels 11 to 14 of each door. Moreover, the feeding point a of the outer panels 11 to 14 of each door is set to a point estimated or corrected by simulation or simulation and actual machine. Similarly, the power reception point b for detecting the transfer function from the outer panels 11 to 14 of each door is also set to a point estimated or corrected by simulation or simulation and actual equipment.

  The UWB oscillator 21 that oscillates a microwave with a wide frequency band is obtained by changing the transfer function of the resonance circuit formed by the outer panels 11 to 14 that function as antennas and the detection regions 11A to 14A around the outer panels 11 to 14. Knowing the propagation state of the microwaves of the outer panels 11 to 14, specifically, the UWB oscillator 21 is a specific plurality determined by the detection regions 11 A to 14 A and the outer panels 11 to 14 (conductive members). Has the frequency as the resonance frequency. In addition, detection area 11A-14A is set outside the distance for the wavelength of the frequency of the microwaves with respect to the outer panels 11-14.

  The UWB oscillator 21 in the case of implementing the present invention detects changes in reflection / absorption at a plurality of resonant oscillation frequencies (f) by changes in the detection regions 11A to 14A. The reference oscillator 22 detects a frequency that changes based on a change in the propagation state of the detection regions 11A to 14A, which are radio wave radiation spaces, and is a microwave oscillator having a specific frequency (fo). This is an oscillator that oscillates a microwave having the same frequency as that of the oscillator 21 or in the vicinity thereof. The reference oscillator 22 oscillates a stable microwave having a specific frequency, and an oscillator whose oscillation frequency (fo) is relatively stable is used.

  The band pass filter 24 is a filter that selects only a specific frequency from which noise has been removed. The high frequency amplifier 25 amplifies the output of the band pass filter 24. The mixer 23 mixes the frequency (f) obtained from the UWB oscillator 21 and the frequency (fo) obtained from the reference oscillator 22, and the mixing frequency (mf + nfo; where m and n are from −∞ to + ∞. Any integer may be used. In addition, the FV converter 26 that converts the frequency as a voltage detects the frequency pattern that has passed through the bandpass filter 24. As a result, the change of the frequency pattern is mixed by the reference oscillator (fo), the extracted frequency pattern is detected by the FV converter 26, and the change of the voltage value corresponding to each frequency frequency pattern or the pattern of each frequency pattern is detected. I try to get matching.

  A UWB oscillator 21 having a microwave frequency radiated using the outer panels 11 to 14 of the vehicle 1 as an antenna is between the detection target 31 in the detection regions 11A to 14A serving as an electromagnetic wave radiation space and the outer panels 11 to 14. A microwave resonance circuit is formed, and there are a plurality of resonance frequencies that can be radiated from the outer panels 11 to 14 due to the relationship between the detection regions 11A to 14A and the outer panels 11 to 14. That is, a resonance state is obtained at a plurality of resonance frequencies supplied by the UWB oscillator 21, and reflection or absorption is caused at a plurality of other frequencies, and their transfer functions correspond to the respective frequencies. When the detection target 31 exists in the detection regions 11A to 14A, the detection target 31 becomes an antenna, and corresponds to the outer panels 11 to 14 functioning as an antenna, and the antennas are coupled to each other. At this time, the transfer function of each frequency radiated from the UWB oscillator 21 changes compared to when the detection target 31 does not exist. By detecting this, the detection target 31 can be determined.

  For example, when the detection target 31 does not exist, the transfer function determined by the outer panels 11 to 14 has a specific frequency pattern in which the FV converter 26 is a change in voltage value corresponding to each frequency. However, when the detection target 31 exists, the output of the FV converter 26 has a different frequency pattern from that when the detection target 31 does not exist due to a change in the state of the detection regions 11A to 14A that are electromagnetic wave radiation spaces.

  Thus, since the frequency band of the UWB oscillator 21 is wide, the microwaves radiated from the outer panels 11 to 14 have a large number of resonance frequencies. The mixer 23 mixes and down-converts the frequency (f) obtained from the UWB oscillator 21 and the frequency (fo) obtained from the reference oscillator 22, and obtains a frequency pattern by the FV converter 26. At this time, when a person or the like comes close to each other, the antennas and the outer panels 11 to 14 are considered as antennas, and the transfer function is different from the transfer function when there is no person or the like. It can be detected as a pattern change.

  Furthermore, the recognition circuit 27 uses the frequency that has passed through the band-pass filter 24 as a signal that has passed through the FV converter 26, and changes the state changes of the detection regions 11A to 14A, which are electromagnetic wave radiation spaces, with the difference in microwave transfer function. The change in the detected frequency pattern is to measure the state corresponding to the distance, size, etc. as a reference frequency pattern in advance, and estimate the distance, size, etc. from the reference frequency pattern. Thus, the distance, size, etc. can be detected.

  That is, at this time, information such as a person, an object, and a size is determined by comparing their characteristics with a reference frequency pattern mapped inside the recognition circuit 27. According to this method, it is possible to distinguish a change during an automatic opening / closing operation of a door from an approach to a person or an object.

  The recognition circuit 27 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 structure is detected, the opening and closing of the door can be stopped or an alarm sound can be generated in the vehicle 1.

  The UWB oscillator 21, the reference oscillator 22, the mixer 23, the band pass filter 24, and the FV converter 26 that constitute the proximity sensor 10 of the present embodiment are connected to the outer panels 11 to 14 and the inner panels of the doors of the vehicle 1. It is built in between the panel (not shown). The output of the FV converter 26 is input to the recognition circuit 27 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 10 according to the present embodiment includes a conductive member including the outer panels 11 to 14 attached to the vehicle 1 so as to be integrated or separable, and a detection region 11A set outside the outer panels 11 to 14. To 14A, a UWB oscillator 21 that outputs a wideband frequency for supplying microwaves to the outer panels 11 to 14, and a power receiving point a different from the feeding point a of the UWB oscillator 21 of the conductive member made of the outer panels 11 to 14 Noise is removed through a band-pass filter 24 at a point b, and a mixer 23 that receives and mixes the frequency of the reference oscillator 22 for down-conversion, and a frequency pattern that has passed through the mixer 23, thereby detecting the regions 11A to 14A. And a recognition circuit 27 for recognizing a change.

  The proximity sensor 10 of the first embodiment configured as described above operates as follows.

  First, a resonance circuit is formed between the outer panels 11 to 14 of each door of the vehicle 1 and the detection target 31 of the detection areas 11A to 14A, and the UWB oscillator 21 is a wideband microwave with respect to the outer panels 11 to 14. Supply. The propagation state is determined by the relationship between the detection regions 11A to 14A, the outer panels 11 to 14, and the detection target 31 such as a person, and the propagation state radiated from the outer panels 11 to 14 changes depending on the presence of the detection target 31.

  That is, in the resonance circuit composed of the outer panels 11 to 14 and the detection target 31 of the detection areas 11A to 14A, the detection target 31 that is resonated by the microwave applied from the UWB oscillator 21 and causes reflection or absorption is detected. When it is not within 11A-14A, it will be in the propagation state of a specific frequency. However, when the detection target 31 such as a person approaches the outer panels 11 to 14, the electric field of the microwave is reflected or absorbed by the detection target 31, and the detection targets 31 of the outer panels 11 to 14 and the detection regions 11A to 14A The resonance circuit composed of is a microwave transfer function different from that when the detection target 31 such as a person does not exist. That is, if the detection target 31 exists in the detection regions 11A to 14A, the propagation state of the frequency supplied from the UWB oscillator 21 changes. This change is noise-removed through the band-pass filter 24 to extract a frequency in a predetermined band, and the extracted frequency is introduced into the mixer 23 together with the output frequency (fo) of the reference oscillator 22 and mixed by the mixer 23. The down-converted frequency is a mixing frequency (f + fo). The mixing frequency (f + fo) from the mixer 23 is input to the FV converter 26, where a frequency pattern based on the transfer function is detected.

  The mixing frequency (f + fo) is detected by recognizing the difference in the frequency pattern in which the frequency that has passed through the band-pass filter 24 through the FV converter 26 by the recognition circuit 27 as the state change in the detection regions 11A to 14A It is. This change in the detected frequency pattern is measured in advance by measuring a reference frequency pattern corresponding to the distance, size, etc., and estimating the distance, size, etc., from the reference frequency pattern. Detection can be performed. Moreover, the moving speed and distance of the detection target 31 can be detected from the changing speed of the reference frequency pattern.

  Therefore, in this embodiment, 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, 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.

  Since the UWB oscillator 21 is an oscillator that oscillates a wide-band microwave, the frequency that can be radiated from the outer panels 11 to 14 can be selected at low cost, and the entire apparatus is inexpensive. be able to. 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 by a plurality of radiating frequencies of the UWB oscillator 21 that oscillates a wideband microwave. In particular, in the case where the door of the vehicle 1 is an antenna, it can be used as a sensor for a crime prevention system, a keyless entry system, etc., and by selecting the frequency band of the UWB oscillator 21, the outer panel 11-14 of the door of the vehicle 1 can be used. The detection areas 11A to 14A can be set within about 30 cm. Therefore, the field of the electromagnetic wave radiation space can be set within about 30 cm from the outer panels 11 to 14 of the door of the vehicle 1.

As described above, since the microwave resonance circuit is formed between the outer panels 11 to 14 and the detection target 31 of the detection regions 11A to 14A, the mutual influence of the electric field / magnetic field of the electromagnetic wave becomes larger, and the detection region 11A. Since it becomes difficult to be influenced by the electrostatic capacitance of the detection target of -14A, the detection accuracy is improved. In particular, as compared with the conventional capacitance detection type, since the detection is not affected by the atmosphere such as humidity, temperature, water vapor, and pressure in the detection region, the apparatus is inexpensive. In addition, since the UWB oscillator 21 has a plurality of radiating frequencies, the radiated wave from the conductive member including the outer panels 11 to 14 can be surely captured when the simulation results are combined. Therefore, it is easy to detect a short distance, and it is possible to detect a state that can be manufactured at low cost.
[Embodiment 2]

  FIG. 3 is a functional block diagram of the proximity sensor according to the second embodiment of the present invention. In addition, since the same code | symbol or the same symbol as the said Embodiment 1 in a figure shows the component which is the same or it corresponds, the detailed description is abbreviate | omitted and only a different point is demonstrated.

  The proximity sensor 10 according to the present embodiment has another power receiving point b, which is different from the power feeding point a of the UWB oscillator 21 of the conductive member made of the outer panels 11 to 14, in addition to the circuit configuration of the first embodiment. One power receiving point b is provided. Noise is removed from these feed points b through a band-pass filter 124, amplified by a high-frequency amplifier 125, and mixed by inputting the frequency of a reference oscillator 122 for down-conversion, and passed through the mixer 123. In this embodiment, a recognition circuit 27 that recognizes changes in the detection areas 11A to 14A is added according to the frequency pattern, and the power receiving point is increased. The added basic circuit configuration is the same as that of the first embodiment.

  The embodiment of FIG. 3 shows an example in which a plurality (two) of power receiving points b are provided on a conductive member made of outer panels 11 to 14. By providing a plurality of (two) power receiving points in this manner, the detection resolution can be further improved and the S / N ratio can be ensured.

In this embodiment, the number of power receiving points b is two or more. However, the difference between the two transfer functions can be detected, and the detection resolution is improved as compared with the case where the number of power receiving points b is one. Of course, if the number is two or more, the detection resolution is improved accordingly. In this embodiment, when the size of the conductive member is large, electromagnetic waves are radiated from the feeding point, the distance when returning (to the receiving point) again becomes long, and the signal may be attenuated. By providing a plurality of power receiving points, the sensitivity can be further improved and the S / N ratio can be secured.
[Embodiment 3]

  The proximity sensor 10 of the first embodiment detects the presence of the detection target 31, but can also detect the movement thereof.

  FIG. 4 is a functional block diagram of the proximity sensor 10 according to the third embodiment of the present invention. In addition, since the same code | symbol or the same symbol as the said Embodiment 1 in a figure shows the component which is the same or it corresponds, the detailed description is abbreviate | omitted and only a different point is demonstrated.

  In this embodiment, by using the directional coupler 28, the configuration having the power feeding point a and the power receiving point b can be set to only a single power feeding point a.

  In FIG. 4, the directional coupler 28 is a circuit that inputs the output of the UWB oscillator 21 to the mixer 23 but does not transmit the signal of the mixer 23 to the UWB oscillator 21. This is a circuit that blocks the signal that is reflected from the feeding point a or inputted to the feeding point a that also serves as the receiving point b from being input to the UWB oscillator 21.

  The proximity sensor 10 according to the third embodiment includes detection areas 11A to 14A set on the outside of a conductive member including outer panels 11 to 14 that are integrally or separably attached to the vehicle 1, and outer panels 11 to 14. The UWB oscillator 21 that supplies a wideband frequency of microwaves using the outer panels 11 to 14 as antennas at a frequency that is sufficiently short in wavelength, and the same feeding point as the feeding point a of the UWB oscillator 21 of the outer panels 11 to 14 Noise is removed from the point a through the directional coupler 28 and the bandpass filter 24, and the frequency output from the reference oscillator 22 that oscillates the frequency for down-conversion is input and mixed, and the mixer 23 detects the Doppler frequency. And a recognition circuit 27 for recognizing changes in the detection regions 11A to 14A according to each frequency pattern passing through the mixer 23. It can be configured as an embodiment of Bei. That is, the power feeding point a and the power receiving point b of the proximity sensor 10 according to the first and second embodiments are one.

Therefore, when the proximity sensor 10 according to the third embodiment supplies the microwaves from the UWB oscillator 21 to the outer panels 11 to 14, the conductive member including the detection target 31 and the outer panels 11 to 14 in the detection regions 11A to 14A A resonant circuit of microwaves is formed between them, and resonates at a plurality of frequencies set by the detection regions 11A to 14A and the outer panels 11 to 14. At this time, the frequency patterns obtained from the outer panels 11 to 14 based on the transfer function when there is no detection target 31 causing reflection in the detection areas 11A to 14A are recorded. When the detection object 31 such as a person approaches the outer panels 11 to 14, the transfer function of the resonance circuit formed by the outer panels 11 to 14 and the detection objects 31 in the detection regions 11 </ b> A to 14 </ b> A changes due to the difference in the transfer function. To do. At this time, the outer panels 11 to 14 have each frequency (wavelength) component based on the difference in transfer function affected by the detection target 31 such as a person. Each frequency is extracted through the band-pass filter 24, mixed with the frequency of the reference oscillator 22, and a Doppler frequency component (frequency shift) between the frequency that has passed through the band-pass filter 24 and the frequency that has passed through the band-pass filter 24. And is down-converted with the frequency of the reference oscillator 22, and the change in the frequency is judged by the output of the FV converter 26. The frequency pattern detected at the output of the FV converter 26 is compared with a known reference frequency pattern in advance, and the distance, size, etc. are detected from the reference signal. Further, the moving speed of the detection target 31 can be detected from the Doppler shift of each frequency of the change in the reference frequency pattern.
[Embodiment 4]

  FIG. 5 is a functional block diagram of the proximity sensor 10 according to the fourth embodiment of the present invention. In addition, since the same code | symbol or the same symbol as the said Embodiment 1 in a figure shows the component which is the same or it corresponds, the detailed description is abbreviate | omitted and only a different point is demonstrated.

  In addition, the proximity sensor 10 according to the fourth embodiment includes detection areas 11A to 14A set on the outside of a conductive member including outer panels 11 to 14 that are integrally or separably attached to the vehicle 1, and the outer panel 11. A UWB oscillator 21 that supplies a wideband frequency of microwaves using the outer panels 11 to 14 as antennas at a frequency that is sufficiently short with respect to the size of ˜14, and a feeding point a of the UWB oscillator 21 of the outer panels 11 to 14 Removes noise via a band-pass filter 24 at another feeding point b, and inputs the output frequency of the UWB oscillator 21 via a reference oscillator 22 and a directional coupler 28 that oscillates a frequency for down-conversion. Mixing and detecting the Doppler frequency, and the detection regions 11A to 14 depending on the frequency of a predetermined band that has passed through the mixer 23. The changes in propagation conditions can be configured as an embodiment comprising a recognizing circuit 27.

  Therefore, when the proximity sensor 10 according to the fourth embodiment supplies a microwave from the UWB oscillator 21 to the outer panels 11 to 14, the conductive member including the detection target 31 in the detection regions 11A to 14A and the outer panels 11 to 14; A microwave resonance circuit is formed between the detection regions 11A to 14A and the outer panels 11 to 14 to resonate at a plurality of frequencies. A frequency pattern obtained from the outer panels 11 to 14 based on the transfer function when there is no detection target 31 causing reflection in the detection areas 11A to 14A is recorded. When the detection object 31 such as a person approaches the outer panels 11 to 14, the frequency pattern of the resonance circuit formed by the outer panels 11 to 14 and the detection objects 31 in the detection regions 11 </ b> A to 14 </ b> A changes due to a difference in transfer function. To do. At this time, since the outer panels 11 to 14 have a frequency (wavelength) component based on the difference in the transfer function affected by the detection target 31 such as a person, they are taken out through the bandpass filter 24 and UWB. The output frequency of the oscillator 31 is mixed, a Doppler frequency component is taken out between them, and down-converted according to the frequency of the reference oscillator 22. The obtained frequency change is determined by a frequency pattern corresponding to each frequency of the output of the FV converter 26. The detected frequency pattern is compared with a known reference frequency pattern in advance, and the distance, size, etc. are detected from the reference signal. Further, the moving speed of the detection target 31 can be detected by the Doppler frequency.

  In the third embodiment and the fourth embodiment, the UWB oscillator 21 is placed between the outer panels 11 to 14 and the detection region 11A to 14A or the detection target 31 of the detection region 11A to 14A in the electromagnetic wave radiation space. The electric field strength (magnetic field) between the outer panels 11 to 14 and the detection regions 11A to 14A or the detection objects 31 of the outer panels 11 to 14 and the detection regions 11A to 14A is regarded as each antenna. Therefore, it is difficult to be affected by the capacitance of the detection target in the detection regions 11A to 14A, so that the detection accuracy is improved. In particular, as compared with the conventional capacitance detection type, since the detection is not affected by the atmosphere such as humidity, temperature, water vapor, and pressure in the detection region, the apparatus is inexpensive. In addition, the use of the UWB oscillator 21 has a plurality of radiable frequencies. Therefore, when the simulation results are combined, the radiated wave from the conductive member made of the outer panels 11 to 14 can be reliably captured. The difference in the transfer function can be clearly detected as the difference in the frequency pattern. Therefore, it is easy to detect a short distance, and it is possible to detect a state that can be manufactured at low cost. In addition, the moving speed of the detection target 31 can be detected by detecting the Doppler shift of the individual frequencies of the frequency pattern.

  Here, the UWB oscillator 21 that outputs the microwaves of the third and fourth embodiments is specified by the detection regions 11A to 14A that are radio wave radiation spaces and the outer panels 11 to 14 that function as antennas. A plurality of resonance frequencies. The feeding point a of the conductive member made up of the outer panels 11 to 14 is set to a point roughly estimated by simulation and actual measurement. The reference oscillator 22 that oscillates a stable microwave may be an oscillator that stabilizes the oscillation frequency.

  The bandpass filter 24 of the third embodiment and the fourth embodiment removes noise, and the mixer 23 only needs to obtain a mixing frequency (mf + nfo). Further, the recognition circuit 27 recognizes a change in the detection regions 11A to 14A, which are the electromagnetic wave radiation spaces, by a frequency pattern based on a difference in transfer function, and corresponds the frequency pattern to a known distance, size, and the like. By comparing with a reference frequency pattern, distance, size, etc. are detected, and an analog circuit or digital that detects the moving speed of the detection target 31 by Doppler shift of individual frequencies of the frequency pattern What is necessary is just to be comprised with a circuit.

  Here, the proximity sensor 10 according to the first to fourth embodiments includes a conductive member including outer panels 11 to 14 that are integrally or separably attached to an attachment target such as a vehicle 1 and the outside of the outer panels 11 to 14. UWB oscillator 21 that outputs a wideband frequency of microwaves radiated by using outer panels 11 to 14 as antennas at a sufficiently short frequency with respect to detection areas 11A to 14A set to the size of outer panels 11 to 14 The detection region is based on the difference in the propagation state of the frequency supplied from the feeding point of the UWB oscillator 21 by forming a resonance circuit between the outer panels 11 to 14 and the detection target 31 of the detection regions 11A to 14A. The change of 11A-14A is detected as a change of a frequency pattern.

  Therefore, the UWB oscillator 21 having a microwave frequency for supplying the outer panels 11 to 14 of the vehicle 1 as an antenna has a detection target 31 in the detection areas 11A to 14A and the outer panels 11 to 14 serving as an electromagnetic wave radiation space. A microwave resonance circuit is formed between them, and microwaves are radiated from the outer panels 11 to 14. Accordingly, when there is a case where there is no detection target 31 causing reflection, a difference in transfer function occurs. Further, when the detection target 31 such as a person approaches the outer panels 11 to 14, the electric field of the radiated electromagnetic wave is reflected or absorbed by the detection target 31, and the detection target 31 such as a person is stationary. Since the transfer function of the electromagnetic wave radiation space changes, it can be understood as a difference in Doppler shift of individual frequencies in the frequency pattern, and the proximity speed and distance of the detection target 31 can be determined by determining the frequency pattern.

  In particular, since a microwave resonance circuit is formed between the outer panels 11 to 14 fed by the UWB oscillator 21 and the detection target 31 in the detection regions 11A to 14A, the mutual influence of the electric field / magnetic field of electromagnetic waves is more conventional. Compared to the capacitance detection type, the detection area can be detected without being influenced by the atmosphere such as humidity, temperature, water vapor, and pressure. Thus, since it becomes difficult to be influenced by the capacitance of the detection target in the detection regions 11A to 14A, the detection accuracy is improved. In addition, since the UWB oscillator 21 has a plurality of frequencies that resonate and a plurality of frequencies that are not in a resonance state, when the simulation results are combined, the radiation waves from the outer panels 11 to 14 can be reliably captured. it can.

  The use of the UWB oscillator 21 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.

  In addition, since the proximity sensor of this Embodiment is used for the vehicle 1, there are many components that can be used as a conductive panel like the outer panels 11 to 14 of the door, and other components can also be used. Therefore, it is preferable to use it for vehicles.

  Since the present invention enables detection of a short distance of the detection target 31 without being affected by the atmosphere such as humidity, temperature, water vapor, pressure, etc. of the electromagnetic 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 10 according to the embodiment of the present invention of this type can be used not only for a vehicle but also for a shower toilet sensor for detecting 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 shower toilet sensor 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. In addition, 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.

  At this time, the proximity sensor 10 according to the embodiment of the present invention may be provided with conductive members such as the outer panels 11 to 14 attached to the attachment target so as to be integrated with or separated from the attachment target.

  Note that the general-purpose proximity sensor 10 can also have the same configuration as that of the above-described embodiment and has the same operational effects, and thus the detailed description thereof is omitted.

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 Embodiment 1 of the present invention. FIG. 3 is a functional block diagram of the proximity sensor according to the second embodiment of the present invention. FIG. 4 is a functional block diagram of the proximity sensor according to the third embodiment of the present invention. FIG. 5 is a functional block diagram of the proximity sensor according to the fourth embodiment of the present invention. FIG. 6 is a frequency-power characteristic diagram defined by the US FCC (Federal Communications Commission) for UWB.

Explanation of symbols

1 Vehicle 11-14 Outer panel (conductive member)
11A to 14A Detection area 21 UWB oscillator 22 Reference oscillator 23 Mixer 24 Band pass filter 26 FV converter 27 Recognition circuit 31 Detection target

Claims (6)

A conductive member that is integrally or separably attached to an attachment target, a detection region set outside the conductive member, and a frequency band having a sufficiently short wavelength with respect to the size of the conductive member. A UWB (Ultra Wide Band) oscillator that supplies a microwave wideband frequency radiating as an antenna,
A proximity sensor, wherein a resonance circuit is formed between the conductive member and the detection region, and a change in the detection region is detected from a difference in propagation state of a frequency supplied from a feeding point of the UWB oscillator. .   The change in the detection area is detected by amplifying the frequency of the conductive member by amplifying means after passing through a directional coupler connected to a feeding point of the UWB oscillator and a band pass filter, and for down-conversion. 2. The proximity sensor according to claim 1, wherein the proximity sensor is configured to use a mixer that inputs and mixes the frequency of the first frequency and a recognition circuit that detects a change in the detection area based on the frequency passed through the mixer.   The detection of the change in the detection region is performed by introducing a frequency of the conductive member from one or more individually received power receiving points and mixing a frequency by inputting a frequency for down-conversion, and The proximity sensor according to claim 1, wherein the proximity sensor is used by using a recognition circuit that detects a change in the detection region based on a frequency passed through a mixer. A conductive member that is integrally or separably attached to an attachment target, a detection region that is set outside the conductive member, and the conductive member that has a sufficiently short wavelength with respect to the size of the conductive member. A UWB oscillator that supplies a wideband frequency of microwaves radiated as an antenna,
A resonance circuit is formed between the conductive member and the detection region, and a change in the detection region and a moving body speed are detected from a change in a propagation state of a frequency supplied from a feeding point of the UWB oscillator. Proximity sensor.   The change of the detection area and the recognition of the moving body speed are performed by introducing the frequency of the conductive member and mixing the frequency by inputting the frequency for down-conversion and the frequency of the UWB oscillator, and passing the mixer through the mixer. The proximity sensor according to claim 4, further comprising: a recognition circuit that detects a change in the detection area and a moving body speed according to a frequency.   The conductive member formed so as to be integrally or separably attached to the attachment target is an opening / closing body that is attached to the vehicle so as to be openable / closable. 6. The conductive member according to any one of claims 1 to 5, Proximity sensor.

Images