JP2012122806A - Mobile object detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile object detection device capable of expanding a monitoring space and reducing a blind space while suppressing increase in a number of components and enlargement in size of the device.SOLUTION: A mobile object detection device comprises: an oscillation circuit 3; two transducers 1 and 2; phase detection circuits 6A and 6B for obtaining a pair of Doppler signals E3 and E4 having mutually different phases by mixing received signals E0 with reference signals E1 and E2, which have the same frequency as a transmitted signal and mutually different phase; a signal processing unit 8 for signal processing the pair of Doppler signals E3 and E4, and detecting movement of an object A1 in a monitoring space to output a detection signal; and an inverting circuit 5 for outputting an inverted signal by inverting the transmitted signal outputted from the oscillation circuit 3. In the mobile object detection device, the transmitted signal is inputted into the transducer 1, the inverted signal is inputted into the other transducer 2, the transducers 1 and 2 are connected in series, and the received signal E0 is extracted from a midpoint of a connection path.

Description

  The present invention radiates continuous energy waves such as ultrasonic waves and radio waves to the monitoring space, and detects the frequency shift of the reflected wave caused by the movement of the object in the monitoring space, thereby the presence of an object moving in the monitoring space. The present invention relates to a moving body detection apparatus that detects the above.

  2. Description of the Related Art In recent years, vehicle theft and on-the-car theft of automobiles have increased, and therefore in-vehicle theft alarm devices that sound an alarm sound when a suspicious person enters a parked vehicle have become widespread. Such an in-vehicle burglar alarm device is equipped with a moving body detection device for detecting the presence or absence of a moving body (person) in the monitoring space (inside the vehicle). This type of moving body detection apparatus radiates a continuous energy wave (for example, an ultrasonic wave) having a predetermined frequency into a monitoring space, and a reflected wave generated as a Doppler effect as the moving body existing in the monitoring space moves. The frequency shift is detected (for example, see Patent Document 1).

  In the conventional example described in Patent Document 1, since a plurality of transmitters are provided, a continuous energy wave can be spread to a place that has been a blind spot in the past, so that the monitoring space is expanded. Yes. Further, as compared with the case where a plurality of sets of transmitters and receivers are provided, it is not necessary to increase the number of circuits for processing the received signals output from the receivers, thereby suppressing an increase in circuit scale.

JP 2010-25672 A Japanese Patent Laid-Open No. Sho 61-270686

  By the way, in the thing of patent document 1, although a transmitter and a receiver are used separately, the structure of the transmission / reception integral type which uses both a transmitter and a receiver by one ultrasonic transducer | vibrator is used. Is conventionally known. Here, in the conventional example described in Patent Document 1, it can be considered that any one of a plurality of transmitters and a receiver are shared by one transmitter / receiver. However, the following problems occur. Can occur.

  For example, as shown in FIG. 5, it is assumed that the transducer 101 is installed on the ceiling of the front seat of the three-row seat vehicle 100 and the transmitter 102 is installed on the ceiling of the rear seat. In this case, when the ultrasonic wave transmitted from the rear transmitter 102 is reflected by an object 103 such as a bag placed on the rear seat, the reflected wave is blocked by the seat, so that the front transmitter / receiver 101 receives the reflected wave. There was a problem that blind spots occurred in the surveillance space.

  As a means for solving this problem, it is conceivable to use two transmitters / receivers so that the reflected wave can be received also on the rear seat side of the vehicle 100, and two independent transmitters are used. For example, Patent Document 2 discloses a configuration for monitoring a monitoring space. In the conventional example described in Patent Document 2, only the received signal is extracted by removing the frequency components of the transmitted signal from each other using the transmitted signals of the two ultrasonic heads (transmitter / receiver). Yes.

  However, in the conventional example described in Patent Document 2, since the frequency components of the transmission signal are removed by adding the transmission signals output from the two ultrasonic heads by the adder, an adder is necessary. There was a problem that the number of parts increased by that amount. Further, since a space for providing the adder is required, there is a problem that the apparatus is increased in size.

  The present invention has been made in view of the above points, and provides a moving body detection apparatus capable of expanding a monitoring space and reducing blind spots while suppressing an increase in the number of parts and an increase in the size of the apparatus. For the purpose.

  The moving body detection device of the present invention includes an oscillating unit that oscillates a transmission signal at a predetermined frequency, a transmission unit that transmits a continuous energy wave whose amplitude periodically changes according to an input signal, to the monitoring space, and Two transmitters / receivers each having a receiving means for receiving a reflected wave generated by reflecting the continuous energy wave to an object existing in the monitoring space; and a reference signal having the same frequency as that of the transmitted signal but different in phase from each other Phase detection means for obtaining a pair of Doppler signals having an amplitude corresponding to a phase difference from the reference signal and having a phase different from each other by mixing the reception signals output from the respective transducers; Detection means for detecting a movement of the object in the monitoring space and outputting a detection signal by performing signal processing on a pair of Doppler signals, and an inverted signal obtained by inverting the transmission signal output from the oscillation means Output And the one of the transducers receives the transmission signal from the oscillation unit, and the other transducer receives the inverted signal from the inversion unit, Each transducer is connected in series and the received signal is taken out from the midpoint of the connected path.

  In this moving body detection apparatus, it is preferable that the transducers are arranged in a distributed manner with respect to the monitoring space.

  In this moving body detection device, each of the transducers is concentrated at a predetermined location with respect to the monitoring space, and each of the transducers has a detection region in which the directions of the transmission and reception are different from each other. It is preferable that it is arranged so as to face.

  The present invention has an effect that the monitoring space can be expanded and the blind spot can be reduced while suppressing an increase in the number of parts and an increase in the size of the apparatus.

It is a block diagram which shows embodiment of the mobile body detection apparatus which concerns on this invention. It is a principal part circuit diagram same as the above. It is the schematic which shows the example of arrangement | positioning of a transmitter / receiver same as the above. It is the schematic which shows the other example of arrangement | positioning of a transmitter / receiver same as the above. It is the schematic which shows the example of arrangement | positioning of the transmitter and transmitter / receiver in the conventional mobile body detection apparatus.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a moving body detection apparatus according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the present embodiment includes a first transmitter / receiver 1 and a second transmitter / receiver 2 connected in series, an oscillation circuit 3 (oscillating means), an inverting circuit 5, and a phase detector. Circuits 6A and 6B and a signal processing unit 8 are provided.

  The first transmitter / receiver 1 and the second transmitter / receiver 2 are both composed of ultrasonic transducers, transmitting means for transmitting ultrasonic waves (continuous energy waves) toward the monitoring space, and in the monitoring space It also serves as a wave receiving means for receiving a reflected wave from the object A1 existing in the area. The first transmitter / receiver 1 is directly input with a transmission signal from an oscillation circuit 3 that oscillates a sinusoidal transmission signal having a predetermined frequency. Further, an inverted signal obtained by inverting the transmission signal from the oscillation circuit 3 by the inverting circuit 5 is input to the second transducer 2. Each of the transducers 1 and 2 is driven by a transmission signal and an inverted signal, and transmits an ultrasonic wave having the same frequency as the oscillation frequency of the oscillation circuit 3 toward the monitoring space.

  Each of the transducers 1 and 2 receives the reflected wave from the object A1 and converts it into a received signal E0. The received signal E0 is input to the first and second phase detection circuits 6A and 6B, respectively. Then, the reference signals E1 and E2 having the same frequency as the oscillation frequency of the oscillation circuit 3 are mixed (mixed). Here, one reference signal E1 is an output of the phase shift circuit 4, and is set so that the phases of both reference signals E1 and E2 are different from each other. Therefore, the pair of Doppler signals E3 and E4 obtained as beat signals at the outputs of the phase detection circuits 6A and 6B also have different phases. The pair of Doppler signals E3 and E4 are amplified by the first and second amplifier circuits 7A and 7B, respectively, and then taken into the signal processing unit 8.

In the signal processing unit 8, the pair of Doppler signals E3 and E4 are sampled and quantized by the sampling circuit 80 at a predetermined sampling period, and converted from an analog value to a digital value. The data are sequentially stored in the memory 81. We define one digital values X _n of the Doppler signal E3 obtained by converting a sampling circuit _80, a digital value obtained by converting the other of the Doppler signal E4 in the sampling circuit 80 _(n is a positive integer) Y _n and. In addition, a vector R _n is defined that starts from the origin of the two-dimensional orthogonal coordinate system and ends at (X _n , Y _n ). The size of the vector R _n corresponds to the amplitude of the Doppler signals E3, E4.

In the vector rotation angle calculation circuit 82 subsequent to the sampling circuit 80, an angle φ formed by the vector R _{n −1} obtained by the previous sampling and stored in the memory 81 and the vector R _n obtained by the current sampling is obtained. _n (this angle is called a vector rotation angle) is calculated. The vector rotation angle calculation circuit 82 calculates the rotation angle φ _n using the following equation.

_{φ n = arctan {(X n} -1 Y n -Y n-1 X n) / (X n-1 X n + Y n-1 Y n)}
Therefore, when the object A1 approaches, the polarity of the rotational angle phi _n to vector R _n rotates counterclockwise it is positive, when the object A1 is away, because the vector R _n rotates clockwise the polarity of the rotation angle phi _n becomes negative. Then, if the rotation angle φ _n obtained by the vector rotation angle calculation circuit 82 is integrated by the subsequent rotation angle integration circuit 83, the integrated value (= φ ₁ + φ ₂ +... Φ _n +...) Is the moving distance of the object A1. It will be proportional to Further, the integrated value integrated by the rotation angle integrating circuit 83 is compared with a predetermined threshold by the subsequent threshold circuit 84, and the threshold circuit 84 sends a detection signal when the integrated value exceeds the threshold. The detection signal is input to the alarm drive circuit 9, and the presence of the moving object A1 is appropriately notified by an alarm (not shown). In addition, it is also possible to implement | achieve the function of each said circuit by comprising the signal processing part 8 with a microcomputer and running a program in a microcomputer.

  Here, in the present embodiment, the transducers 1 and 2 are connected in series, and the transmission signal from the oscillation circuit 3 is input to one first transducer 1 and the other second An inverted signal obtained by inverting the transmission signal from the oscillation circuit 3 by the inverting circuit 5 is input to the transducer 2. Specifically, as shown in FIG. 2, the transmission signal from the oscillation circuit 3 is input to the first transducer 1 through the series circuit of the capacitor C1 and the resistor R1, and the inversion from the inversion circuit 5 is performed. A signal is input to the second transducer 2 via a series circuit of a capacitor C2 and a resistor R2. Further, the received signal E0 is taken out through a capacitor C3 from the midpoint of the path connecting the first transducer 1 and the second transducer 2 in series.

  Therefore, at the midpoint, the ultrasonic wave from the second transducer 2 received by the first transducer 1 and the first transducer 1 received by the second transducer 2 are received. Cancels out the ultrasonic waves from Therefore, the frequency component of the transmission signal is removed, and only the reception signal E0 is input to the phase detection circuits 6A and 6B.

  As described above, in the present embodiment, since the two transmitters and receivers 1 and 2 that also serve as the transmitter and the receiver are used, the case where the transmitter and the transmitter are used as in the prior art. In comparison, the monitoring space can be expanded and the blind spot can be reduced. Further, in the present embodiment, the transmitter / receiver 1 and 2 receive a transmission signal whose phase is inverted, and the received signal E0 is received from the midpoint of the path connecting the transmitter / receiver 1 and 2 in series. Since it is extracted, only the received signal E0 from which the frequency component of the transmitted signal is removed can be extracted. Therefore, since it is not necessary to remove the frequency component of the transmission signal using an adder as in the prior art, an adder becomes unnecessary, and as a result, an increase in the number of parts and an increase in the size of the apparatus can be suppressed.

  Hereinafter, an arrangement example of the transducers 1 and 2 will be described. For example, as shown in FIG. 3, the first transducer 1 is installed on the ceiling of the front seat of the vehicle 100, and the second transducer 2 is installed on the ceiling of the rear seat. It is conceivable to disperse and arrange the transducers 1 and 2 in the monitoring space. In this case, since the inside of the vehicle 100 can be uniformly covered by the detection area B1 by the first transducer 1 and the detection area B2 by the second transducer 2, the monitoring space can be expanded, and The number of blind spots can be reduced.

  Further, for example, as shown in FIG. 4, each of the transducers 1 and 2 is installed on the ceiling of the central portion of the vehicle 100, that is, is concentrated on a predetermined position with respect to the monitoring space in the vehicle 100, It is conceivable to arrange the transducers 1 and 2 toward different detection areas. Also in this case, since the inside of the vehicle 100 can be covered evenly by the detection area B1 by the first transducer 1 and the detection area B2 by the second transducer 2, the monitoring space can be expanded. In addition, the blind spots can be reduced. Further, when installing the transmitters and receivers 1 and 2 as shown in FIG. 4, the transmitters and receivers 1 and 2 and the circuits can be built in an existing room lamp on the ceiling of the center of the vehicle 100. Therefore, the device can be easily attached. Furthermore, since the transducers 1 and 2 are concentrated in one place, there is an effect that wiring between each circuit by the wire harness and the transducers 1 and 2 becomes easy.

DESCRIPTION OF SYMBOLS 1 1st transducer 2 2nd transducer 3 Oscillation circuit (oscillation means)
5 Inversion circuit (inversion means)
6A First phase detection circuit (phase detection means)
6B Second phase detection circuit (phase detection means)
8 Signal processor (detection means)
A1 object

Claims (3)

  Oscillating means for oscillating a transmission signal at a predetermined frequency, transmission means for transmitting a continuous energy wave whose amplitude periodically changes according to an input signal to the monitoring space, and the continuous energy wave in the monitoring space Two transmitters / receivers including receiving means for receiving a reflected wave generated by reflection on an existing object, a reference signal having the same frequency as that of the transmitted signal and a phase different from each other, and the respective transmitters / receivers are output. Phase detection means for obtaining a pair of Doppler signals having an amplitude corresponding to the phase difference from the reference signal by mixing the received signal and having a phase different from each other, and signal processing the pair of Doppler signals Detecting means for detecting the movement of the object in the monitoring space and outputting a detection signal, and having an inverting means for outputting an inverted signal obtained by inverting the transmission signal output from the oscillating means, Of the above The wave receiving signal is input to the wave receiving device from the oscillating means, and the other wave transmitting / receiving device is input the inverted signal from the inverting means to connect the wave receiving / receiving devices in series. A moving body detection apparatus that extracts the received signal from a midpoint of a path connected together.   The mobile body detection device according to claim 1, wherein each of the transducers is arranged in a distributed manner with respect to the monitoring space.   The transducers are arranged at a predetermined location with respect to the monitoring space, and the transducers are arranged so that the directions of the transducers are directed to different detection areas. The moving body detection apparatus according to claim 1.

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