Source: https://patents.justia.com/patent/7746220
Timestamp: 2019-08-21 19:55:24
Document Index: 749446349

Matched Legal Cases: ['art 250', 'art 251', 'art 252', 'art 253', 'art 252', 'art 251', 'art 251', 'art 252', 'art 252', 'art 251', 'art 252', 'art 250', 'art 250', 'art 250', 'art 250', 'art 250', 'art 350', 'art 350', 'art 350', 'art 350', 'art 350', 'art 350', 'art 450', 'art 450', 'art 450', 'art 450', 'art 450', 'art 450', 'art 455', 'Application No. 2006', 'Application No. 2006']

US Patent for Moving object detection apparatus Patent (Patent # 7,746,220 issued June 29, 2010) - Justia Patents Search
Justia Patents Of Relative Distance From An ObstacleUS Patent for Moving object detection apparatus Patent (Patent # 7,746,220)
Dec 29, 2006 - Panasonic
A moving object detection apparatus comprises a transmitter, a receiver, a detection portion, a binary conversion portion and a judgment portion. The transmitter emits energy waves with a first frequency to a detection area. When receiving incoming energy waves from the detection area, the receiver generates an electric signal corresponding to the incoming energy waves. The detection portion obtains a detection signal from a reference signal with the first frequency and the electric signal. The binary conversion portion compares the detection signal with a conversion threshold signal to obtain a binary signal. The judgment portion judges whether or not a moving object approaching or leaving the receiver exists in the detection area based on the binary signal.
The invention relates to moving object detection apparatus and more particularly to moving object detection apparatus for detecting, for example, approach of one or more moving objects within a specified distance in a detection area.
This sort of moving object detection apparatus is used as, for example, a crime prevention device or the like. For example, Japanese Patent Application Publication No. H09-272402 issued Oct. 21, 1997 discloses ultrasonic Doppler type intrusion detection apparatus for vehicle (hereinafter also referred to as “first conventional apparatus”). This apparatus comprises first and second judgment means, and is configured to operate intermittently. The first judgment means judges whether or not a Doppler shift value is in a set range representative of unlawful entry of a person into a vehicle. At this point, the apparatus counts the number of times the first judgment means judges that a Doppler shift value is in the set range, and then obtains a count value. The second judgment means judges whether or not the count value reaches a predetermined value. When the count value reaches the predetermined value, the apparatus gives an alarm. In this apparatus, unlawful entry can be detected without the influence of disturbance. Moreover, since the apparatus operates intermittently, power consumption can be reduced.
Japanese Patent Publication No. S62-43507 issued Sep. 14, 1987 discloses moving object detection apparatus (hereinafter also referred to as “second conventional apparatus”). This apparatus is configured to extract cosine and sine component signals from an output signal for generating ultrasonic waves and an input signal obtained from incoming ultrasonic waves and to convert the cosine and sine component signals into binary signals to set to X and Y coordinates of X-Y coordinate system, respectively. Since an X coordinate value is 1 or 0 and a Y coordinate value is also 1 or 0, a coordinate point (X, Y) corresponds to any quadrant of the coordinate system. And the apparatus judges that a moving object approaching the apparatus exists in a detection area if (X, Y) turns counterclockwise around the origin of the coordinate system, and judges that a moving object leaving the apparatus exists in the detection area if (X, Y) turns clockwise. In this prior art, existence of a moving object approaching or leaving the apparatus can be certainly detected without frequency analysis.
Japanese Patent Application Publication No. H01-189582 issued Jul. 28, 1989 discloses moving object detection apparatus (hereinafter also referred to as “third conventional apparatus”). This apparatus judges whether or not a moving object approaching or leaving an ultrasonic receiver exists in a detection area based on two Doppler signals in the same way as the second conventional apparatus. The apparatus then increases a count value for an alarm in response to the existence of the moving object approaching the receiver and decreases the count value in response to the existence of the moving object leaving the receiver. In this apparatus, the influence caused by the swing of a curtain(s) can be avoided.
It is therefore an object of the present invention to reduce power consumption and to simplify the construction of moving object detection apparatus.
In an enhanced embodiment, the moving object detection apparatus further comprises an oscillator, and the detection portion is provided with a phase shifter, and first and second detection parts. In addition, the binary conversion portion is provided with first and second binary converters, while the judgment portion is provided with a first judgment part, a first counter and a second judgment part. The oscillator generates a first reference signal having the first frequency and supplies the transmitter with the first reference signal to cause the transmitter to emit sine-wave shaped energy waves with the first frequency to the detection area. The phase shifter shifts the phase of the first reference signal by ¼ period to produce a second reference signal. The first detection part mixes the electric signal generated by the receiver with the first reference signal generated by the oscillator to produce a first detection signal. When the second frequency is obtained from the electric signal, the first detection signal becomes a first Doppler shift signal that has a frequency of the difference between the first frequency and the second frequency. The second detection part mixes the electric signal generated by the receiver with the second reference signal produced by the phase shifter to produce a second detection signal. When the second frequency is obtained from the electric signal, the second detection signal becomes a second Doppler shift signal that has a frequency of the difference between the first frequency and the second frequency and is different in phase by ¼ period from the first Doppler shift signal. The first binary converter compares the first detection signal with a first conversion threshold signal to obtain a first binary signal. The second binary converter compares the second detection signal with a second conversion threshold signal to obtain a second binary signal. The first judgment part takes a transition factor whenever first and second values are respectively set to first and second coordinates in two-dimensional coordinate system in response to the levels of the first and second binary signals. The transition factor is specified by the first and second coordinates. If taken each transition factor crosses one coordinate axis in the coordinate system, the first judgment part judges that a moving object approaching or leaving the receiver exists in the detection area, and otherwise judges that the moving object does not exist in the detection area. In case that said moving object exists in the detection area, the first judgment part judges that said moving object approaches the receiver if said each transition factor moves around the origin of the coordinate system in one direction, and judges that said moving object leaves the receiver if said each transition factor moves in reverse direction to the one direction. The first counter adds a first polarity value to a first count value in case that said moving object exists in the detection area and approaches the receiver, and adds a second polarity value to the first count value in case that said moving object exists in the detection area and leaves the receiver. The second polarity value is equal in absolute value to the first polarity value and different in polarity from the first polarity value. When the absolute value of the first count value is larger than that of a judgment threshold value, the second judgment part sends out an existence signal representing that said moving object exists in the detection area. The judgment threshold value is equal in polarity to the first polarity value.
FIG. 1 shows a first embodiment according to the present invention, namely moving object detection apparatus. This apparatus belongs to an ultrasonic Doppler type, and comprises an oscillator 10, a transmitter 11, a receiver 12, a detection portion 13, a binary conversion portion 14, a judgment portion 15 and a power source 17.
The operational theory of the detection portion 13 is explained. For example, when a moving object approaching or leaving the receiver 12 (hereinafter referred to as a “moving object MO”) exists in the detection area and ultrasonic waves from the transmitter 11 are reflected by the moving object MO, the first frequency f1 of the ultrasonic waves is shifted to at least one second frequency fin different from f1 by the Doppler shift. In this case, when the signals Ein and E1 are respectively represented by Ain sin(2πfint+φ) and A1 sin(2πf1t), a signal EinE1 obtained by mixing the signals is given by
EinE1=AinA1(cos {2π(fin−f1)t+φ}−cos {2π(fin+f1)t+φ})/2 (eq. 1),
The detection portion 23 is formed of a phase shifter 230, first and second mixers 231 and 232, and first and second low-pass filters 233 and 234, for example, in the same way as a conventional synchronous detection circuit. For example, the phase shifter 230 advances the phase of a first reference signal E1 with a first frequency f1 by one-fourth period (e.g., 90°) to produce a second reference signal E2, and supplies the signal E2 to the mixer 232.
EinE2=AinA2(sin {2π(fin−f1)t+φ}+sin {2π(fin+f1)t+φ})/2,
The first judgment part 250 is formed of quadrant judgment part 251 and quadrant holding part 252 for a first process as well as a direction judgment part 253 for second and third processes. The part 252 stores at least two-bit data. In case of the first process, whenever setting digital values Xn and Yn to coordinates X and Y in X-Y coordinate system in response to binary signals X and Y from the binary conversion portion 24, respectively, the part 251 takes the transition factor specified by the coordinates X and Y The coordinate X is set to “1” if the binary signal X is a high signal, and is set to “0” if the signal X is a low signal. Also, the coordinate Y is set to “1” if the binary signal Y is a high signal, and is set to “0” if the signal Y is a low signal. Therefore, in case of X=1 and Y=1, the transition factor corresponds to the first quadrant, and accordingly the part 251 replaces quadrant information of the part 252 with the first quadrant and the part 252 holds information of the first quadrant. Similarly, the part 251 replaces quadrant information of the part 252 with the second quadrant in case of X=0 and Y=1, with the third quadrant in case of X=0 and Y=0, and with the fourth quadrant in case of X=1 and Y=0.
The first counter 254 renews a first count value based on each judgment result of the first judgment part 250. The counter 254 adds a constant value to the first count value if the part 250 judges that a moving object MO exists in the detection area. If the part 250 judges that the object MO does not exist in the area, the counter 254 keeps the first count value as-is. In the second embodiment, if the part 250 judges that the object MO exists in the area and approaches the receiver 22, the counter 254 adds a first polarity value to the first count value. The first polarity value is equal to said constant value in absolute value and equal to first threshold in polarity, e.g., “1”. If the part 250 judges that the object MO exists in the area and leaves the receiver 22, the counter 254 adds a second polarity value to the first count value. The second polarity value is equal to said constant value in absolute value and different from the first polarity value in polarity, e.g., “−1”. In the example of FIG. 4B, the counter 254 adds “1” to the first count value when transition factors change from (1, 1) representative of the first quadrant to (0, 1) representative of the second quadrant. The counter 254 adds “1” to the first count value when transition factors change from (0, 1) representative of the second quadrant to (0, 0) representative of the third quadrant. The counter 254 then adds “−1” to the first count value when transition factors change from (0, 0) representative of the third quadrant to (0, 1) representative of the second quadrant.
where v and c are moving speed of the object MO and ultrasonic propagation speed, respectively. Therefore, the frequency f is in proportion to the moving speed of the object MO. When the object MO moves unit distance, the number of waves N of each Doppler shift signal is given by N=2f1/c. Therefore, if each of c and f1 is constant, the number of waves N becomes constant regardless of the moving speed of the object MO, and accordingly the number of times of quadrant transition also becomes constant. That is, the number of times of quadrant transition is 4×N and in proportion to the moving speed of the object MO. Therefore, by utilizing the first count value, moving distance and moving direction of the object MO can be seen.
E11=sin(ωt+φ+fm sin ωot)sin ωt≈½fm sin φsin ωot,
E21=sin(ωt+φ+fm sin ωot)cos ωt≈½fm cos φsin ωot,
where fm sin ωot is small vibration and fm is fm<<1. In this case, if φ is 0 or π/2, either of the signals E11 and E21 becomes zero. If φ is π/4 or 3π/4, the signals E11 and E21 become anti-phase or in-phase.
However, since there is a case that the level of a signal E22 obtained from said incoming ultrasonic waves is out of the third and fourth window ranges, the judgment part 350 further utilizes the phase difference Δφ between the first and second binary signals X and Y If the phase difference Δφ is equal to or smaller than said reference phase, the signals E12 and E22 are almost in-phase or anti-phase, and it is thought that absolute values of those amplitudes are different from each other. Accordingly, it can be supposed that the incoming ultrasonic waves are ultrasonic waves caused by small vibration. In other words, in case that a moving object MO is human, it is considered that the object MO requires the time that the phase difference Δφ exceeds the reference phase in order to change the moving direction. In the example of FIG. 6, each of the third and fourth window ranges is set to twice of each of the first and second window ranges. In this case, the phase difference Δφ reaches π/6(=30°) at a point in time at which the signals E12 and E22 becomes out of the third and fourth window ranges. If the phase difference Δφ is a value in the neighborhood of π/6, it is considered that the incoming ultrasonic waves are ultrasonic waves caused by small vibration, and accordingly in the third embodiment, the reference phase is set, for example, within the range from π/6 to π/4, preferably to π/6. Therefore, if the levels of the first and second detection signals are out of the third and fourth window ranges, respectively, the part 350 performs the first to third processes when the phase difference Δφ is larger than the reference phase. Consequently, it can be further prevented that false detection is made under the influence of, for example, small vibration when a moving object MO does not exist in the detection area. Specifically, the part 350 judges whether or not the phase difference Δφ is larger than the reference phase based on a ratio of period T1 to period T2 shown in FIG. 6. For example, in case that the reference phase is π/4, if T1:T2 is within the range from 1:3 to 3:1, the part 350 performs the first to third processes. Otherwise, the part 350 does not perform the first to third processes. In this case, the part 350 may judge that quadrant factors move between the first quadrant and the third quadrant as shown in FIG. 7A, or move between the second quadrant and the fourth quadrant as shown in FIG. 7B.
In a varied embodiment, the detection portion 43 is configured to produce one of the first and second detection signals E13 and E23. The first judgment part 450 is also configured to judge whether or not a moving object MO exists in a detection area based on a signal from the portion 43. For example, as shown in FIG. 9, the portion 43 is formed of a first mixer 431, a first low-pass filter 433 and a first amplifier 435. This portion 43 produces a first detection signal E13 from a signal Ein and a first reference signal E1, and supplies the signal E13 to the first judgment part 450 through the first binary converter 441. The part 450 detects frequency fin−f1 of the Doppler signal obtained from the signal E10, and compares the frequency with a specified frequency range. When the object MO is, for example, human, the specified frequency range is set based on human moving speed. The part 450 judges that the object MO exists in the area if the frequency fin−f1 is in the specified frequency range. Otherwise, it is judged that the object MO does not exist in the area. The first counter 454 adds a constant value (e.g., “1”) to the first count value if the part 450 judges that the object MO exists in the area. If the part 450 judges that the object MO does not exist in the area, the first count value is kept as-is. The second judgment part 455, second counter 456, subtractor 457 and alarm 46 are formed like, for example, those of FIG. 8.
a phase shifter that shifts the phase of the first reference signal by ¼period to produce a second reference signal;
a second detection part that mixes the electric signal generated by the receiver with the second reference signal produced by the phase shifter to produce a second detection signal, the second detection signal becoming a second Doppler shift signal that has a frequency of the difference between the first frequency and the second frequency and is different in phase by ¼ period from the first Doppler shift signal when the second frequency is obtained from the electric signal;
4287579 September 1, 1981 Inoue et al.
4961039 October 2, 1990 Yamauchi et al.
5280290 January 18, 1994 Evans et al.
61-054483 March 1986 JP
62-043507 February 1987 JP
1-189582 July 1989 JP
2-090084 March 1990 JP
3-195990 August 1991 JP
05-172942 July 1993 JP
5-259744 October 1993 JP
8-166449 June 1996 JP
08-166449 June 1996 JP
09-272402 October 1997 JP
2001-296360 October 2001 JP
2004-358133 December 2004 JP
Notification of Reasons for Refusal for the Application No. 2006-182468 from Japan Patent Office mailed Jun. 30, 2009.
International Search Report PCT/ISA/210, Feb. 6, 2007 (3 pages) with English Translation (1 page).
Written Opinion PCT/ISA/237, Feb. 6, 2007 (5 pages).
Notification of Reasons for Refusal for the Application No. 2006-001714 from Japan Patent Office mailed Oct. 27, 2009.
Lin, Sylvia et al., “C-Band Direct Conversion Receiver Front-End Using A Resistive FET Mixer”, Microwave Symposium Digest, 1999, IEEE MTT-S, vol. 4, pp. 1409-1411.
Patent Publication Number: 20090016162
Inventors: Toshimasa Takagi (Kobe), Fumihiro Kasano (Katano), Hidehiko Fujikawa (Kadoma)
Application Number: 11/887,079
Current U.S. Class: Of Relative Distance From An Obstacle (340/435); Doppler Effect (340/554); Of Collision Or Contact With External Object (340/436); Curb (340/437); Vehicle Parking Indicators (340/932.2); By Doppler Effect (367/90); By Doppler Effect (367/94); Distance Or Direction Finding (367/99); With Beam Steering, Scanning, Or Focussing (367/103); Audible Or Tactile (367/116); With Quadrature Difference Processing (342/152); 342/357.05
International Classification: B60Q 1/00 (20060101); B60Q 1/48 (20060101); G01S 15/00 (20060101);