JP2002267744A - Object detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a relatively inexpensive object detector of relatively simple detector constitution, capable of enhancing detection precision of a stationary object in a near distance. SOLUTION: A microwave of 10.525 GHz is used as a transmission signal. Antenna pitches between reception antennas 5, 7, 9 are at set about 15 mm of 1/2 wave length of a standing wave of the microwave and 2.4 mm which is not a multiple thereof. The first, second and third standing waves of analog signals are converted respectively into digital signals by an A/D converter 29 to be stored in a memory part 33. The first - third full-wave rectification processing parts 35-39 conduct respectively processings corresponding to full- wave rectifications to the respective digital data corresponding to the first - third standing waves, using as a reference output voltages from the first - third direct current amplifying circuit 21-25 sides when the transmission is not emitted from a transmission antenna 3. An adding part 41 conducts processing for summing up the digital data after the processing, and a voltage level comparing part 45 checks whether the digital data provided therein is larger than a threshold voltage level or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an object detection device, and more particularly to an object detection device suitable for detecting whether or not a stationary human body is within a predetermined distance range.

[0002]

2. Description of the Related Art Pulse radars, FM-CW radars, and the like are known as devices for detecting objects using radio waves. The pulse radar measures the distance from the device to the target object based on the length of time from when the pulsed radio wave is radiated to when the pulsed radio wave hits the target object and returns to the device. Is measured. On the other hand, the FM-CW radar measures a beat frequency between a transmission signal and a reflection signal generated by performing frequency modulation (FM) on a continuous wave (CW) signal radiated from the device, for example, with a sawtooth wave. The distance from the device to the target object is measured.

[0003]

By the way, the above-mentioned pulse radar is configured to measure a distance from the apparatus to a target object based on a length of time from a time when the radio wave is emitted to a time when the radio wave is received. Therefore, it is not suitable for distance measurement when the target object exists at a short distance.
In addition, there is a problem that the device configuration is relatively complicated and expensive. On the other hand, the FM-CW radar is configured to determine the distance from the device to the target object by measuring the beat frequency between the transmission signal and the reflection signal generated due to the signal processing as described above. In addition, when the target object is located at a short distance, the frequency must be largely changed, so that the occupied frequency bandwidth of the transmission signal is widened. Moreover,
As in the above-described pulse radar, there are problems that the device configuration is relatively complicated and expensive. Therefore,
A method using a Doppler radar as a means for detecting an object instead of the above-described pulse radar or FM-CW radar was also studied. However, Doppler radar is effective when detecting objects moving at high speed such as aircraft and automobiles, but it is almost stationary, for example, just before the toilet, for example, the human body, trying to use it in the toilet. It is not suitable for detecting a human body standing in a state, and also has a problem that it is expensive.

Therefore, when an object such as a human body in a stationary state is to be detected, a radio wave belonging to a predetermined frequency band is radiated to the target object, and the radiated radio wave and the target object are reflected and reflected. A method of detecting the target object by measuring the intensity of a standing wave generated by the returning radio wave has been studied. However, in the standing wave, the period in which the antinode portion having a large amplitude and the node portion having a small node that can be regarded as being stopped at the same position with each other, that is, the period of the strength of the standing wave is determined by the standing wave. There is a problem in that the distance from the apparatus to the target object cannot be determined only by measuring the intensity of the standing wave because it appears at a half wavelength of the standing wave.

Accordingly, an object of the present invention is to provide a relatively simple device configuration and a relatively low-cost object detection device capable of improving the detection accuracy of a short-distance stationary object.

[0006]

An object detecting apparatus according to a first aspect of the present invention receives a predetermined signal generated as a transmission signal, and radiates the signal as a radio wave. When a wavelength of a standing wave generated by a signal received as an external radio wave and a transmission signal to be radiated as the radio wave is λ, and the number of the receiving antennas is m, ｛( λ / 2) / m} + n
A plurality of reception antennas arranged at intervals represented by λ / 2 (where n is an arbitrary integer), and a plurality of constants having different phases generated from a reception signal from each reception antenna and the transmission signal. A signal processing unit that performs predetermined arithmetic processing after full-wave rectification of a standing wave, and a level of a signal waveform generated based on the above processing and a comparison result between a preset threshold level and a target object. Determining means for determining the presence or absence.

[0007] According to the above configuration, a plurality of standing waves having different phases generated from the reception signal and the transmission signal from each reception antenna are subjected to full-wave rectification and then subjected to predetermined arithmetic processing. Based on the comparison result between the level of the signal waveform generated based on the threshold level and a preset threshold level,
Since the presence or absence of the target object is determined, it is possible to detect with high accuracy whether or not a stationary object exists within a predetermined distance range.

[0008] In a preferred embodiment according to the first aspect of the present invention, the arithmetic processing includes a processing of synthesizing each standing wave after full-wave rectification. In a modification of the above embodiment, the arithmetic processing includes a process of extracting the maximum value of each standing wave after full-wave rectification.

In the above-mentioned embodiment, for example, a radio wave included in a microwave frequency band is used as the transmission signal. The detection target object may be, for example, a human body in a stationary state within a predetermined distance range from the reference position. Further, when it is determined that the target object is present, the determination means performs the processing assuming that the target object is within a predetermined distance range.

An object detection device according to a second aspect of the present invention includes a transmission antenna for receiving a generated predetermined signal as a transmission signal and radiating the signal as radio waves, and a plurality of reception antennas, When the wavelength of a standing wave generated by a signal received as an external radio wave and a transmission signal to be radiated as the radio wave is λ, and the number of receiving antennas is m, (λ / m) + nλ (where And n is an arbitrary integer), and a plurality of standing waves having different phases generated from a reception signal from each reception antenna and the transmission signal, which are arranged at an interval represented by Signal processing means for performing predetermined arithmetic processing after wave rectification, and determining whether or not a target object is present based on a comparison result between a level of a signal waveform generated based on the above processing and a preset threshold level means Equipped with a.

In a preferred embodiment according to the second aspect of the present invention, the arithmetic processing includes a processing of synthesizing each standing wave after the half-wave rectification. In a modification of the above-described embodiment, the arithmetic processing includes a process of extracting the maximum value of each standing wave after half-wave rectification.

In the above-mentioned embodiment, for example, a radio wave included in a microwave frequency band is used as the transmission signal. The detection target object may be, for example, a human body in a stationary state within a predetermined distance range from the reference position. Further, when it is determined that the target object is present, the determination means performs the processing assuming that the target object is within a predetermined distance range.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an explanatory diagram of an object detecting device according to a first embodiment of the present invention.

The above-mentioned device is a type of Doppler sensor that performs a detection operation of a target object (stationary human body) using the Doppler effect of radio waves. The detection operation is performed using a microwave that is a radio wave in a frequency band of about 10 GHz, more specifically, a microwave having a frequency of 10.525 GHz. The above device is shown in FIG.
As shown in FIG. 1, a waveguide 1, a transmitting antenna 3 provided at a predetermined position in the waveguide 1, and a plurality of antennas (3 in FIG.
Book) receiving antennas 5, 7, 9
It also includes a plurality of types of signal processing circuits described later (shown in FIG. 2) and information processing circuits (for example, microcomputers).

The waveguide 1 is a microwave transmission path composed of a hollow pipe having high conductivity. The transmitting antenna 3 radiates the microwave generated and output by a transmitting circuit described later (shown in FIG. 2) as a transmitting signal through the waveguide 1 in a predetermined direction, that is, in the direction of the stationary human body 11. (Send. The receiving antennas 5, 7, and 9 are respectively arranged at appropriate positions in the waveguide 1 at a predetermined antenna pitch.

In this embodiment, as described above, 10.525 GHz
Is radiated to the outside of the device as a transmission signal. In this embodiment and a second embodiment to be described later, the antenna pitch is set to a standing wave (a combination of the transmission signal and the reception signal) which is a composite wave of the transmission signal and the radiated microwave reception signal. The synthesis is performed in the above device) to set to 2.4 mm for full wave rectification. On the other hand, when the standing wave is half-wave rectified as in the third and fourth embodiments described later, the antenna pitch is set to 4.8 mm.

The reason is that in the standing wave, the period in which the antinode portion having a large amplitude and the node portion having a small amplitude (which can be regarded as stopping at the same position as each other), that is, one of the standing waves, The period of the intensity that appears at the / 2 wavelength is 10.525GH
In the microwave standing wave of z, the distance is approximately 15 mm (10.52
Since one wavelength of 5 GHz is approximately 30 mm, a half wavelength is approximately 15 mm.
mm). Therefore, unless the antenna pitch is set to a value deviating from 15 mm or a multiple thereof, the intensity (voltage level) of the standing wave based on the received signal output from each receiving antenna cannot be measured. In the fourth embodiment, the distance is set to 15 mm and a value (2.4 mm or 4.8 mm) that is not a multiple thereof as described above.

Each of the receiving antennas 5, 7, and 9 radiates the microwaves radiated from the transmitting antenna 3 through the waveguide 1 in a predetermined direction and reflected on a stationary human body 11 (object to be detected). , Respectively, at the position set by the antenna pitch as described above. Then, these are used as reception signals, and each reception antenna (5, 7,
9) A plurality of mixer circuits provided for each (shown in FIG. 2)
Respectively.

FIG. 2 is a block diagram showing a circuit configuration provided in the object detecting device shown in FIG.

As shown in FIG. 2, the above-mentioned device comprises a transmitting circuit 13, a first mixer circuit 15, and a second mixer circuit 17.
, A third mixer circuit 19, a first DC amplifier circuit 21,
The circuit includes a second DC amplifier circuit 23, a third DC amplifier circuit 25, a selector circuit 27, an A / D converter circuit 29, and an information processing circuit 31 such as a microcomputer. The information processing circuit 31 includes a memory unit 33, a first full-wave rectification processing unit 35, a second full-wave rectification processing unit 37, a third full-wave rectification processing unit 39, an addition unit 41, and a threshold voltage level data holding unit (holding unit). 43) voltage level data comparing section (comparing section) 4
5. Each of the function blocks of the detection result determination unit (determination unit) 47 and the determination result output unit (output unit) 49 has the function shown by each functional block.

The transmission circuit 13 generates a transmission signal of a predetermined frequency within the designated frequency band (in this embodiment, the microwave of 10.525 GHz as described above), and transmits the transmission signal to the signal transmission inside the apparatus. It radiates (transmits) as radio waves in a predetermined direction (the stationary human body 11 shown in FIG. 1) through the road 12 and the transmitting antenna 3. At the same time, the transmission signal is transmitted from the transmission circuit 13 to the first mixer circuit 15 via the signal transmission path 14 and to the second mixer circuit 17 via the signal transmission path 16.
Then, the signals are output to the third mixer circuit 19 through the signal transmission line 18, respectively. The transmission signal is, for example, a transmission antenna 3
The signal is transmitted from the transmission circuit 13 at a ratio of 7 to the side and 3 to the first to third mixer circuits (15 to 19).

The first mixer circuit 15 mixes and adjusts the received signal from the receiving antenna 5 and the transmitted signal transmitted from the transmitting circuit 13 through the signal transmission line 14 to adjust the received signal.
A microwave standing wave (first standing wave) of 10.525 GHz is generated, and the first standing wave is transmitted to the corresponding first DC amplification circuit 21.
Through the selector circuit 27. Similarly to the first mixer circuit 15, the second mixer circuit 17 mixes and adjusts the reception signal from the reception antenna 5 with the transmission signal transmitted from the transmission circuit 13 through the signal transmission line 16 to perform the microwave control. Generate a standing wave (second standing wave) of
The second standing wave is output to the selector circuit 27 through the corresponding second DC amplifier circuit 23. Similarly, the third mixer circuit 19 mixes and adjusts the reception signal from the reception antenna 5 and the transmission signal transmitted from the transmission circuit 13 through the signal transmission line 18 in the same manner as described above, so that the microwave standing A third standing wave is generated, and the third standing wave is supplied to the selector circuit 27 through the corresponding third DC amplifier circuit 25.
Output to

The selector circuit 27 receives the first DC amplification circuit 21 based on the selection operation control signal from the information processing circuit 31.
From the first standing wave from the second DC amplification circuit 23 and the third standing wave from the third DC amplification circuit 25 at predetermined timing. Reading,
Output to the A / D conversion circuit 29. A / D conversion circuit 29
Converts the first, second, and third standing waves (analog signals) provided through the selector circuit 27 into digital signals, and sends the digital signals to the information processing circuit 31. These digital signals are written in predetermined storage areas in the memory unit 33 in the information processing circuit 31, and are stored in the memory unit 33.

The first full-wave rectification processing unit 35 includes a memory unit 33
The above-mentioned (first standing wave) digital signal is read out from the predetermined storage area of. By subjecting the digital signal to predetermined arithmetic processing, digital data corresponding to a signal waveform (voltage level) obtained by full-wave rectification of the first standing wave (analog signal) is generated. The data is output to the adder 41 at a predetermined timing.

The second full-wave rectification processor 37 reads the digital signal (of the second standing wave) from a predetermined storage area of the memory unit 33, as in the first full-wave rectification processor 35. By subjecting the second standing wave to full-wave rectification, digital data corresponding to a signal waveform obtained by performing full-wave rectification is generated, and the digital data is output to the adding unit 41 at a predetermined timing.

Further, the third full-wave rectification processing unit 39 reads the digital signal (of the third standing wave) from a predetermined storage area of the memory unit 33 in the same manner as described above. Then, by subjecting the third standing wave to full-wave rectification, digital data corresponding to the signal waveform obtained by performing the predetermined arithmetic processing is generated, and the digital data is output to the adding unit 41 at a predetermined timing.

The adder 41 includes a first full-wave rectifier 35,
The digital data output from the second full-wave rectification processor 37 and the third full-wave rectification processor 39 at predetermined timings are individually read. Then, a process of adding these digital data is performed, and a signal waveform (analog waveform) obtained by synthesizing the standing waves (first, second, and third standing waves) after the full-wave rectification is obtained. ) Is generated and output to the comparison unit 45. Digital data corresponding to the signal waveform obtained by the adding process is approximated to digital data corresponding to an envelope of each of the standing waves (first, second, and third standing waves) after the full-wave rectification. The summing process is performed to minimize the fluctuation of the value reflecting the unevenness of the standing wave inherent in the individual digital data described above.

The holding section 43 stores voltage level data (digital data) serving as a threshold value for determining whether or not a target object (stationary human body) exists within a certain distance range from the installation position of the device. The stored data is output to the comparing unit 45 in response to a data read request from the comparing unit 45. Note that the distance range is not represented by a fixed numerical value (specific numerical value), for example, within 1 meter from the installation position of the device as a reference position, but a numerical value that is an approximate standard. The range is shown. The comparing unit 45 reads the digital data from the adding unit 41 and the threshold voltage level data from the holding unit 43, compares the two values, and notifies the determination unit 47 of the comparison result.

The determination unit 47 determines that the content of the notification is
The value of the digital data from 1 is larger than the value of the threshold voltage level data (the signal strength of the reflected microwave wave received by each of the receiving antennas 5, 7, and 9 exceeds the threshold voltage level. ), The target object (a stationary human body) was detected (there is a target object)
Is determined. On the other hand, if the notification content indicates that the value of the threshold voltage level data is larger than the value of the digital data from the adding unit 41, the determination unit 47 does not detect the target object (the target object is not detected). No).
The determination unit 47 outputs the determination result to the outside of the information processing circuit 31 through the output unit 49.

FIG. 3 is a block diagram showing the internal configuration of the transmitting circuit 13 shown in FIG.

As shown in FIG. 3, the oscillation circuit 13 includes an oscillator 53 and a bias voltage output unit 51 for supplying a bias voltage of +5 V to the oscillator 53 as a drive source. 10.5 as described above
Transmitting antenna 3 using microwave of 25GHz as transmitting signal
And the first, second, and third mixer circuits (15, 1
7, 19).

FIG. 4 shows output signals from the first, second, and third mixer circuits (15, 17, 19) when a plurality of (three) receiving antennas are arranged at an antenna pitch of 2.4 mm. FIG. 4 is a waveform diagram showing waveforms of respective standing waves. Also,
FIG. 5 shows the first, second, and third mixer circuits (15, 1, 1).
7, 19), digital data representing each standing wave, which has been subjected to predetermined arithmetic processing by each full-wave rectification processing unit (35-39), is converted into an analog signal waveform. FIG. Further, FIG. 6 shows digital data (signals obtained by synthesizing the waveforms after full-wave rectification) obtained by adding together the digital data after the processing corresponding to the full-wave rectification by the adding unit 41. (Showing a waveform) is shown by an analog signal waveform.

In FIG. 4, the vertical axis indicates the signal strength of each standing wave, and the horizontal axis indicates the distance from the installation position of the receiving antenna 5 when the installation position is used as a reference position. Also, the code A
Is the first standing wave (that is, the first standing wave from the first mixer circuit 15).
The output waveform through the DC amplification circuit 21) is the second
The standing wave (that is, the output waveform from the second mixer circuit 17 through the second DC amplifier circuit 23) is denoted by C
The standing waves (that is, output waveforms from the third mixer circuit 19 through the third DC amplifier circuit 25) are shown. As mentioned above, each receive antenna 5,7,9 is receiving antenna 5
The receiving antenna 7 is disposed at a position 2.4 mm away from the reference position, and the receiving antenna 9 is disposed at a position 2.4 mm away from the reference position. Therefore, the phase difference between the first standing wave A and the second standing wave B and the phase difference between the second standing wave B and the third standing wave C should be indicated by the antenna pitch (2.4 mm), respectively. Can be. As described above, the digital data corresponding to the first standing wave A, the second standing wave B, and the third standing wave C are respectively converted into the first full-wave rectification processing unit 35,
The second full-wave rectification processing unit 37 and the third full-wave rectification processing unit 39 individually perform arithmetic processing corresponding to full-wave rectification, so that in each full-wave rectification processing unit (35 to 39), The digital data of the value corresponding to each full-wave rectified waveform A ', B', C 'as shown in FIG. As shown in FIG. 6, which is obtained by synthesizing the full-wave rectified waveforms A ′, B ′, and C ′ by performing a process of adding these digital data by the adding unit 41 as described above. Digital data having a value corresponding to the signal waveform D is generated in the adder 41. As described above, the signal waveform D itself approximates the envelope of each of the waveforms A ', B', and C '. In other words, in order to minimize the fluctuation of the value reflecting the unevenness of the standing wave inherent in the individual digital data described above, the adding unit 41 performs the adding processing of the digital data.

FIG. 7 is a flowchart mainly showing the processing operation of each section of the information processing circuit 31 shown in FIG.

In FIG. 7, first, the first, second and third standing waves selectively output from the selector circuit 27 at a predetermined timing are converted into digital data and stored (step S61). ). Next, the transmission signal (1
When the transmitting antenna 3 does not radiate a microwave of 0.525 GHz (no signal), the first to third DC amplifier circuits (21
-25) based on the value of the voltage output from each side,
An arithmetic process corresponding to full-wave rectification of each digital data corresponding to the first to third standing waves is performed for each digital data (step S62). Then, the digital data after the arithmetic processing is added is processed (step S63), and it is checked whether the digital data obtained by the addition is higher than the above-described threshold voltage level. If it is larger (step S64), it is determined that the target object is present (a stationary human body is detected). In this case, detecting the distance from the installation position of the device to the stationary human body, which is the detection target object, with relatively high accuracy requires the reflectance (reflection intensity) of the transmission signal even by the clothing of the human body. ) Is different, but it is possible to grasp the approximate distance from the device to the human body (step S65). On the other hand, if the digital data is smaller than the threshold voltage level, it is determined that there is no target object (a stationary human body was not detected) (step S66).

As described above, according to the first embodiment of the present invention, the first, second, and third signals having the above-described phase difference are provided.
Digital data representing a waveform obtained by performing an arithmetic process corresponding to full-wave rectification on digital data representing each standing wave of the above, and adding each digital data after the arithmetic process. And the threshold voltage level data. And, based on the comparison result,
Since it is determined whether or not the stationary human body is within a predetermined distance range from the above-described device, the fluctuation of the value reflecting the unevenness of the standing wave inherent in each digital data is minimized. Accordingly, the detection accuracy of the presence or absence of the stationary human body as the target object can be improved.

Further, the detection range is set at a short distance of 1 m or less, mainly with a relatively small number of parts, without complicating the apparatus configuration, and at a relatively low cost. It is possible to realize a relatively reliable object detection device as a detection target object. Therefore, for example, if the above-described device is arranged at an appropriate place in a Western-style / Japanese-style flush toilet or a flush-type men's urinal in a toilet room, it is possible to relatively accurately detect a person trying to use the toilet. Therefore, it is possible to appropriately control the flow of water before and after the toilet in each toilet. In other words, it is possible to prevent waste such as erroneously draining to the toilet even though a person is not near the toilet.

In the above embodiment, an example in which three receiving antennas (5, 7, 9) are arranged at an antenna pitch of 2.4 mm has been described, but a plurality of standing waves having a phase difference are intentionally used. Are combined to reduce the influence of the above-mentioned unevenness of the standing wave. Therefore, the number of receiving antennas is required to be at least two or more. In the embodiment, any value can be set as long as it is not a length of a half wavelength of 10.525 GHz microwave or a multiple thereof.

Further, in the above-described embodiment, the full-wave rectification processing for each standing wave and the addition (synthesis) processing of each signal waveform after full-wave rectification are performed in an information processing circuit such as a microcomputer. However, the above-described processing may be performed using hardware such as a full-wave rectifier circuit and an adder.

FIG. 8 is a block diagram showing a circuit configuration inside the object detection device according to the second embodiment of the present invention.

In this embodiment, in addition to the generation of a signal waveform by full-wave rectification of the first, second, and third standing waves, and addition (synthesis) of the standing waves after full-wave rectification. The equal division of the signal waveform at an arbitrary interval and the extraction of the maximum value for each section generated by the equal division are also performed by software processing in the information processing circuit. When the maximum values extracted in this way are connected by a curve, the curve is similar to the envelope of each standing wave after full-wave rectification, as in the first embodiment. . That is, even when the maximum value extraction processing as described above is performed, the fluctuation of the value reflecting the unevenness of each of the standing waves can be minimized.

Therefore, in the present embodiment, as in the first embodiment, the processing of digital data corresponding to full-wave rectification is performed by each full-wave rectification processing unit (35 to 39).
However, instead of the adder 41, a signal waveform is generated by adding (synthesizing) each standing wave after full-wave rectification, and the signal waveform is equally divided at an arbitrary interval and generated by the equal division. The maximum value extracting unit 73 is provided in the information processing circuit 71 as a functional block for processing digital data corresponding to the extraction of the maximum value for each section. The other configurations are the same as those shown in FIG. 2, and the description thereof will be omitted.

FIG. 9 shows digital data obtained by the maximum value extracting section 73 from the digital data after performing the processing corresponding to the full-wave rectification by the maximum value extracting processing (maximum values of the extracted sections are compared with each other). Is shown by analog signal waveforms.

As shown in FIG. 9, the maximum value extracting unit 73
It can be seen that the analog signal waveform D ′ representing the digital data obtained by performing the maximum value extraction processing is very similar to the (analog) signal waveform D shown in FIG.

FIG. 10 is a flowchart mainly showing the processing operation of each section of the information processing circuit 71 shown in FIG.

In the flowchart shown in FIG. 10, step S6
In step 7, the maximum value extracting unit 73 performs the above-described maximum value extracting process on each digital data corresponding to the first to third standing waves on which the arithmetic processing corresponding to the full-wave rectification has been performed. Only the operation differs from the flow chart shown in FIG. Therefore, all the remaining flows other than the flow of the maximum value extraction processing operation are denoted by the same reference numerals as in FIG. 7, and the description thereof is omitted. Note that the detailed description of the processing operation shown in step S67 is also omitted because it is redundant.

FIG. 11 is a block diagram showing a circuit configuration inside the object detecting device according to the third embodiment of the present invention.

In this embodiment, the information processing circuit 75 includes first, second, and third full-wave rectification processing units (35, 37, 3
Instead of 9), first, second, and third half-wave rectification processing units (77, 79, 81) are provided, respectively, and the first, second, and third half-wave rectification processing units (77, 79, 81) are provided. 79, 81), the first, second, and third standing waves are subjected to arithmetic processing corresponding to half-wave rectification on each digital data corresponding to each of the standing waves. Is different from the embodiment of FIG. The other configuration is the same as the configuration shown in FIG. 2, and thus the same reference numerals as those in FIG. 2 denote the same parts, and a description thereof will be omitted.

FIG. 12 shows output signals from the first, second, and third mixer circuits (15, 17, 19) when a plurality of (three) receiving antennas are arranged at an antenna pitch of 4.8 mm. FIG. 4 is a waveform diagram showing waveforms of respective standing waves. Also,
FIG. 13 shows the first, second, and third mixer circuits (15, 1, 1).
Digital data representing each standing wave outputted from each of the half-wave rectification processing sections (77, 79, 8).
FIG. 1B is a diagram showing digital data after performing a predetermined arithmetic processing in an analog signal waveform. Further, FIG.
FIG. 5 is a diagram showing digital signal obtained by adding processing of each digital data by the adding unit 41 after performing processing corresponding to half-wave rectification in an analog signal waveform.

In FIG. 12, the vertical axis indicates the signal strength of each standing wave, and the horizontal axis indicates the distance from the installation position of the receiving antenna 5 when the installation position is used as a reference position. Further, reference numeral E denotes the first standing wave, reference numeral F denotes the second standing wave, and reference numeral G denotes the third standing wave. Each of the receiving antennas 5, 7, 9 is located at a position 4.8 mm away from the position of the receiving antenna 5 as a reference position.
However, the receiving antenna 9 is located 4.8 mm away therefrom.
, Respectively. Therefore, the phase difference between the first standing wave E and the second standing wave F and the phase difference between the second standing wave F and the third standing wave G should be indicated by the antenna pitch (4.8 mm), respectively. Can be. The first standing wave E, the second standing wave F, the third
The digital data corresponding to the standing wave G is individually processed by the first half-wave rectification processing unit 77, the second half-wave rectification processing unit 79, and the third half-wave rectification processing unit 81 to calculate the processing corresponding to the half-wave rectification. As a result, the half-wave rectification waveforms E ′, F ′, G as shown in FIG.
Is generated. Then, a process of adding these digital data by the adder 41 is performed, whereby the half-wave rectified waveforms E ′ and F ′ are added.
The digital data having a value corresponding to the signal waveform H as shown in FIG. Note that the signal waveform H itself is, as described above, the respective waveforms E ′ and F ′.
′ And G ′.

FIG. 15 is a flowchart mainly showing the processing operation of each section of the information processing circuit shown in FIG.

In the flowchart shown in FIG. 15, step S8 is performed.
In 3, each of the half-wave rectification processing units (77 to 81)
Only the operation of performing the arithmetic processing corresponding to the half-wave rectification as described above on each digital data corresponding to the third to third standing waves is different from the flowchart shown in FIG. Therefore, all the remaining flows other than the flow of the operation of the half-wave rectification process are denoted by the same reference numerals as those in FIG. 7 and their description is omitted. Note that the detailed description of the processing operation shown in step S83 is also redundant and will be omitted.

FIG. 16 is a block diagram showing a circuit configuration inside the object detection device according to the fourth embodiment of the present invention.

In this embodiment, the information processing circuit 85 includes first, second, and third full-wave rectification processing units (35, 37, 3
Instead of 9), the first, second, and third half-wave rectification processing units (77, 79, 81) are respectively provided, and the maximum value extraction unit 73 is provided instead of the addition unit 41. This is different from the first embodiment. The other configuration is the same as the configuration shown in FIG. 2, and thus the same reference numerals as those in FIG. 2 denote the same parts, and a description thereof will be omitted.

FIG. 17 shows digital data obtained by the maximum value extracting section 73 from the digital data after performing the processing corresponding to the half-wave rectification by the maximum value extracting processing (the maximum values of each extracted section are not shown). Is shown by analog signal waveforms.

As shown in FIG. 17, the maximum value extracting section 7
It can be seen that the analog signal waveform H ′ representing digital data obtained by performing the maximum value extraction processing is very similar to the (analog) signal waveform H shown in FIG.

FIG. 18 is a flowchart mainly showing the processing operation of each section of the information processing circuit shown in FIG.

In the flowchart shown in FIG. 18, step S6
In step 7, the maximum value extracting unit 73 performs the above-described maximum value extracting process on each digital data corresponding to the first to third standing waves on which the arithmetic processing corresponding to the half-wave rectification has been performed. Only the operation differs from the flowchart shown in FIG. Therefore,
All the remaining flows other than the flow of the maximum value extraction processing operation are denoted by the same reference numerals as those in FIG. 15, and the description is omitted. Note that the detailed description of the processing operation shown in step S67 is also omitted because it is redundant.

As described above, the first preferred embodiment of the present invention
Although the fourth to fourth embodiments have been described, these are examples for describing the present invention, and are not intended to limit the scope of the present invention only to these embodiments. The present invention can be implemented in other various forms.

[0061]

As described above, according to the present invention,
It is possible to provide an object detection device that can improve the detection accuracy of a stationary object at a short distance and has a relatively simple device configuration and a relatively low cost.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an object detection device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a circuit configuration inside the object detection device shown in FIG.

FIG. 3 is a block diagram showing an internal configuration of the transmission circuit shown in FIG. 2;

FIG. 4 shows the waveform of each standing wave output from each of the first, second, and third mixer circuits when a plurality of (three) receiving antennas are arranged at an antenna pitch of 2.4 mm. Waveform diagram.

FIG. 5 is digital data representing each standing wave output from each of the first, second, and third mixer circuits, and is digital data after each full-wave rectification processing unit has performed a predetermined arithmetic processing; FIG. 4 is a diagram showing data in an analog signal waveform.

FIG. 6 is a diagram showing digital signal obtained by adding processing of each digital data by an adding unit after performing processing corresponding to full-wave rectification in an analog signal waveform.

FIG. 7 is a flowchart mainly showing the processing operation of each section of the information processing circuit shown in FIG. 2;

FIG. 8 is a block diagram showing a circuit configuration inside an object detection device according to a second embodiment of the present invention.

FIG. 9 is a diagram illustrating digital data obtained by a maximum value extraction process from each digital data after a maximum value extraction unit has performed a process corresponding to full-wave rectification, as an analog signal waveform.

FIG. 10 is a flowchart mainly showing the processing operation of each section of the information processing circuit shown in FIG. 8;

FIG. 11 is a block diagram showing a circuit configuration inside an object detection device according to a third embodiment of the present invention.

FIG. 12 shows waveforms of respective standing waves output from the first, second, and third mixer circuits when a plurality of (three) receiving antennas are arranged at an antenna pitch of 4.8 mm. Waveform diagram.

FIG. 13 is digital data representing each standing wave output from each of the first, second, and third mixer circuits, and is digital data after each half-wave rectification processing unit has performed a predetermined arithmetic processing; FIG. 4 is a diagram showing data in an analog signal waveform.

FIG. 14 is a diagram showing digital signal waveforms obtained by adding digital data to each other after performing a process corresponding to half-wave rectification by an adding unit, in the form of an analog signal waveform.

FIG. 15 is a flowchart mainly showing the processing operation of each section of the information processing circuit shown in FIG. 11;

FIG. 16 is a block diagram showing a circuit configuration inside an object detection device according to a fourth embodiment of the present invention.

FIG. 17 is a diagram showing, as an analog signal waveform, digital data obtained by the maximum value extracting unit from each digital data after the maximum value extracting unit has performed processing corresponding to half-wave rectification.

FIG. 18 is a flowchart mainly showing the processing operation of each section of the information processing circuit shown in FIG. 16;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Waveguide 3 Transmitting antenna 5, 7, 9 Receiving antenna 11 Object to be detected (stationary human body) 13 Transmitting circuit 15 First mixer circuit 17 Second mixer circuit 19 Third mixer circuit 21 First DC amplifier circuit 23 Second DC amplifier circuit 25 Third DC amplifier circuit 27 Selector circuit 29 A / D conversion circuit 31, 71, 75, 85 Information processing circuit (for example, microcomputer) 33 Memory unit 35 First full-wave rectification processing unit 37 Second full circuit Wave rectification processing unit 39 Third full-wave rectification processing unit 41 Addition unit 43 Threshold voltage level data holding unit (Holding unit) 45 Voltage level data comparison unit (Comparison unit) 47 Detection result judgment unit (Judgment unit) 49 Judgment result output unit (Output unit) 51 Bias voltage output unit 53 Oscillator 73 Maximum value extraction unit 77 First half-wave rectification processing unit 79 Second half-wave rectification processing unit 81 Third half-wave rectification Flow processing unit

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Kentaro Todoroki 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Tochiki Kiki Co., Ltd. 2-1-1, Totoki Kiki Co., Ltd. (72) Inventor Masayuki Nagaishi 2-1-1, Nakajima, Kokurakita-ku, Kitakyushu, Fukuoka Prefecture Totoki Kiki Co., Ltd. (72) Inventor, Yasushi Inuma Kitakyushu, Fukuoka 2-1-1 Nakajima, Kokurakita-ku, Tokyo F-term (reference) in Toko Kiki Co., Ltd. 5J070 AB15 AC20 AD03 AE09 AH31 AK02 AK22

Claims (9)

[Claims] 1. A transmission antenna for receiving a generated predetermined signal as a transmission signal and radiating the signal as a radio wave, a plurality of reception antennas, and a signal received as an external radio wave. When the wavelength of a standing wave generated by a transmission signal to be radiated as a radio wave is λ, and the number of receiving antennas is m, the antennas are arranged at intervals represented by {(λ / 2) / m} + nλ / 2. A plurality of receiving antennas, and a plurality of standing waves having different phases generated from the reception signal and the transmission signal from each of the reception antennas, signal processing means for performing predetermined arithmetic processing after full-wave rectification, An object detection device comprising: a determination unit configured to determine presence or absence of a target object based on a comparison result between a level of a signal waveform generated based on the processing and a preset threshold level. 2. The object detection apparatus according to claim 1, wherein the arithmetic processing includes a processing of combining the standing waves after the full-wave rectification. 3. The object detection apparatus according to claim 1, wherein the arithmetic processing includes a process of extracting a maximum value of each standing wave after the full-wave rectification. 4. A transmitting antenna for receiving the generated predetermined signal as a transmission signal and radiating the signal as a radio wave, a plurality of receiving antennas, and a signal received as an external radio wave, When the wavelength of a standing wave generated by a transmission signal to be radiated as a radio wave is λ and the number of receiving antennas is m, a plurality of receiving antennas arranged at intervals represented by (λ / m) + nλ And a plurality of standing waves having different phases generated from the reception signal and the transmission signal from each of the reception antennas, signal processing means for performing predetermined arithmetic processing after half-wave rectification, and based on the processing. An object detection device comprising: a determination unit configured to determine the presence or absence of a target object based on a comparison result between a level of the generated signal waveform and a preset threshold level. 5. The object detection device according to claim 4, wherein the arithmetic processing includes a processing of combining the standing waves after the half-wave rectification. 6. The object detection apparatus according to claim 4, wherein the arithmetic processing includes a processing of extracting a maximum value of each standing wave after the half-wave rectification. 7. The object detection device according to claim 1, wherein the transmission signal is a radio wave included in a microwave frequency band. 8. The object detection device according to claim 1, wherein the detection target object is a human body in a stationary state within a predetermined distance range from the reference position. 9. The object detection apparatus according to claim 1, wherein when the determination unit determines that there is a target object, the determination unit performs processing assuming that the target object is within a predetermined distance range.