JP2003043140A - Sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor device for further improving detecting accuracy with relatively simple device constitution in detecting an object of a resting or slow moving speed at a short distance. SOLUTION: This sensor device has a transmission part for transmitting a radio wave generated by a signal generator, a receiving part for receiving a reflected wave of a transmission signal transmitted from the transmission part, a mixer part for converting a difference between the transmission signal and a received signal received by the receiving part into a signal, and a determining part for determining the existence of the object from output of the mixer part, and has a variable phase difference generating means capable of freely changing a phase difference between the signals on a line between the receiving part and the mixer part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor device that performs sensing by transmitting and receiving radio waves, and is suitable for determining the presence or absence of an object.

[0002]

2. Description of the Related Art Conventionally, pulse radars, FM-CW radars, etc. have been known as a method for detecting an object using transmission and reception of radio waves.

However, these radars have not been very good in detecting accuracy when they are stationary at a short distance or have a slow moving speed. Further, these radars have a problem that they are expensive and have a complicated device configuration.

As a method of detecting a stationary object or a moving object having a slow moving speed at a short distance, there is a method of detecting an arbitrary phase by a Doppler sensor by shifting a fixed angle.
With this method, it was possible to detect a stationary object or a moving object with a slow moving speed, but the control circuit became somewhat complicated due to the provision of a controller for signal fluctuation due to temperature drift of the sensor itself.

Therefore, an object of the present invention is to provide a sensor device which can detect an object at a short distance at a stationary or slow moving speed with a relatively simple device configuration and further improve the detection accuracy.

In order to achieve the above object, the sensor device according to the present invention comprises a transmitter for transmitting the radio wave generated by the signal generator, and a receiver for receiving the reflected wave of the transmission signal transmitted from the transmitter. A sensor unit having a mixer unit for converting a difference between the transmission signal and a reception signal received by the reception unit into a signal, and a determination unit for determining the presence / absence of an object from the output of the mixer unit. It is characterized in that a variable phase difference generating means capable of continuously changing the phase difference of signals in the range of at least 0 to 180 degrees is provided on a line between the mixer section and the mixer section. With such a configuration, when detecting an object for an arbitrary distance, by shifting the phase from 0 degree to 180 degrees on the receiving side, the minimum value to the maximum value of the output obtained from an object without that distance can be obtained. The
The positional output with respect to the distance can be obtained by the width from the minimum value to the maximum value. With this, there is no node of the Doppler signal for any distance, and even if there is a deviation of the reference point due to temperature drift or the like, there is no need to provide a complicated control device because the output value is obtained by the width. Since the output with respect to the distance is uniquely obtained, the detection accuracy is greatly improved. Further, by changing the upper limit of the phase shift to a value slightly exceeding 180 degrees, it is possible to ensure the range of the phase difference from 0 to 180 degrees.

Further, as set forth in claim 2, a transmitting section for transmitting the radio wave generated by the signal generator, a receiving section for receiving a reflected wave of the transmitting signal transmitted from the transmitting section, and the transmitting signal. In a sensor device having a mixer section for converting a difference between a received signal received by the receiving section and a received signal into a signal, and a judging section for judging the presence or absence of an object from the output of the mixer section, from the signal generator to the mixer section. A variable phase difference generating means capable of continuously changing the phase of the signal within a range of at least 0 to 180 degrees on a line between the branch point for transmitting the signal and the mixer section. To do. With such a configuration, when detecting an object at an arbitrary distance, by shifting the phase from 0 degree to 180 degrees on the transmitting side, the minimum value to the maximum value of the output obtained from a certain object without the distance can be obtained. Then, the positional output with respect to the distance is obtained with the width from the minimum value to the maximum value. With this, there is no node of the Doppler signal for any distance, and even if there is a deviation of the reference point due to temperature drift or the like, there is no need to provide a complicated control device because the output value is obtained by the width. Since the output with respect to the distance is uniquely obtained, the detection accuracy is greatly improved. Also, the upper limit of phase shift is 18
By changing the value to a value slightly exceeding 0 degree, the phase difference can be surely secured in the range of 0 to 180 degrees.

According to a third aspect of the present invention, a transmitter for transmitting the radio wave generated by the signal generator, a receiver for receiving a reflected wave of the transmission signal transmitted from the transmitter, and the transmission signal. In a sensor device having a mixer section for converting a difference between a received signal received by the receiving section and a received signal into a signal, and a judging section for judging the presence or absence of an object from the output of the mixer section, from the signal generator to the mixer section. The phase of the signal should be at least 0 on the line between the branch point for transmitting the signal and the transmitter.
A sensor device having variable phase difference generation means capable of continuously changing in a range of 180 degrees to 180 degrees. With such a configuration, when detecting an object at an arbitrary distance, by shifting the phase from 0 degree to 180 degrees on the transmitting side, the minimum value to the maximum value of the output obtained from a certain object without the distance can be obtained. Then, the positional output with respect to the distance is obtained with the width from the minimum value to the maximum value. With this, there is no node of the Doppler signal for any distance, and even if there is a deviation of the reference point due to temperature drift or the like, there is no need to provide a complicated control device because the output value is obtained by the width. Since the output with respect to the distance is uniquely obtained, the detection accuracy is greatly improved. Further, by changing the upper limit of the phase shift to a value slightly exceeding 180 degrees, the phase difference can be reliably ensured in the range of 0 to 180 degrees.

According to the present invention, the received signal is divided into a plurality of signals having an arbitrary phase difference, and the divided signal is controlled by an arbitrary electric signal. Since the phase of the received signal can be shifted from 0 to 180 degrees by attenuating and adding with, the minimum value to the maximum value of the output obtained from a certain object that is not that distance can be obtained, and from that minimum value The positional output with respect to the distance can be obtained by the width up to the maximum value. With this, there is no node of the Doppler signal for any distance, and even if there is a deviation of the reference point due to temperature drift or the like, there is no need to provide a complicated control device because the output value is obtained by the width. Since the output with respect to the distance is uniquely obtained, the detection accuracy is greatly improved.

Further, as described in claim 9, the maximum value or the minimum value is input to the determination section by extracting only the maximum value and / or the minimum value of the output in the determination section, and the maximum value is input to the determination section. Since the minimum value and the threshold value are compared with each other and the comparison is not performed in the portions other than the maximum value and the minimum value, the output of the object at an arbitrary distance is uniquely determined, and the detection accuracy can be further improved.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the center frequency of the transmission signal output from the signal generator is 10.525.
It is assumed that the frequency is near GHz. FIG. 1 is an overall schematic diagram of a sensor device having a phase difference generating means on the receiving side, FIG. 2 is a block diagram of the variable phase difference generating means, FIG. 3 is a block diagram of the attenuator, and FIG. Connection configuration diagram, Fig. 6 determination operation diagram of determination unit, Fig. 7 conceptual diagram of distance measurement measurement, Fig. 8 configuration diagram with phase difference generation means in the transmission unit, Fig. 9 receiver and transmission unit FIG. 10 shows a configuration diagram including the phase difference generating means, FIG. 10 is a schematic diagram of phase difference generation of the variable phase difference generating means, and FIG. 11 is a control signal diagram input to the variable phase difference generating means.

FIG. 1 shows an overall schematic view of a sensor device having a phase difference generating means on the receiving side. The sensor device of this embodiment includes a transmission antenna 2 that transmits a radio wave from a signal generator 1 that generates a transmission signal 3, and a reception antenna 4 that receives a reflected wave of the transmission signal 3 transmitted from the transmission antenna 2.
A mixer section 6 for converting the difference between the transmission signal 3 and the reception signal 5 received by the reception antenna 4 into a signal; a determination section 7 for determining the presence or absence of an object from the output of the mixer section 6; The variable phase difference generating means 8 which can freely change the phase difference of the received signal 5 is provided on the line between the mixer 4 and the mixer section 6.

The 10 GHz band transmission signal 3 output from the signal generator 1 is radiated from the transmission antenna, reflected by an object, and received by the reception antenna 4 as a reception signal 5. The phase of the received signal 5 received by the receiving antenna 4 is changed by 0 to 180 degrees or more (270 degrees in this embodiment) by the variable phase difference generation means 8, and the phase difference output 9 which is a signal having the changed phase is output. . The phase difference output 9 and the transmission signal 3 are mixed in the mixer section 6
Low frequency output by mixing and taking the difference
You get 10. The low frequency output 10 is used to determine the final presence or absence of the object in the determination unit 7.

FIG. 2 shows a block diagram of the variable phase difference generating means 8. The received signal 5 received by the receiving antenna 4 first reaches the fixed phase difference generating means 21 of the variable phase difference generating means 8. In this embodiment, the fixed phase difference generator 8 shifts the phase by 90 degrees. The fixed phase difference generating means used here is a Hybrid Coupled Type phase shifter in this embodiment. By this fixed phase difference generation means 21, the received signal 5
Outputs A signal 22a and B signal 22b, which are two signals having different phases.

The A signal 22a and the B signal 22b output from the fixed phase difference generating means 21 reach the attenuators 24a and 24b provided on the respective lines. The attenuators 24a and 24b are for attenuating an input signal based on a certain electric signal. The A signal 22a and the B signal 22b attenuated by an arbitrary electric signal by the attenuators 24a and 24b are combined by the adder 23, and the C signal 25
Output as a. The phase of the C signal 25a at this time is changed from 0 to 90 degrees with respect to the A signal 22a.

Next, the C signal 25a output from the adder 23
Reaches the fixed phase difference generating means 21 again. As a result, the C signal 25a becomes the D signal 26, which is two signals with different phases.
It outputs a and E signal 26b. Here, the D signal 26a and the E signal 26b output in the same manner as described above are attenuated by the attenuators 24a and 24b according to arbitrary electric signals, respectively, toward the adder 23, and are combined by the adder 23, and the signal is added. It outputs F25b.

At this time, the F signal 25b should be out of phase with the A signal 22a by 0 to 180 degrees.
Since it is also possible that the phase shift is reduced due to the attenuation factor of the attenuator, in this embodiment, another fixed phase difference generation means 21 is provided to ensure that the maximum value and the minimum value of the output for any place are obtained. Is what you are doing.

For the above reason, the fixed phase difference generating means is further provided.
21 is provided and the F signal 25b is input to this. The F signal 25b is output by the fixed phase difference generating means 21 as two signals having different phases, that is, a G signal 27a and an H signal 27b. These two signals 27a and 27b are also attenuated by the attenuators 24a and 24b, combined by the adder 23, and the phase difference output 9
Is also output.

By using the phase difference generating means 8 having the above structure, the phase is shifted from 0 degree to 270 degree at the maximum, and the maximum value and the minimum value of the output with respect to a certain distance can be surely obtained. You can The presence / absence of an object is determined using this phase difference output 9.

Here, FIG. 3 shows a phase difference generation process diagram of each phase difference generation means of the variable phase difference generation means 8. Each phase difference generating means can shift the phase up to 90 degrees. Here, the phase difference generating means at the first stage of FIG. 2 is taken as an example. The received signal 5 received by the receiver 4 is two signals (A signal 2) having a phase difference of 90 degrees by the fixed phase difference generation means 21.
2, B signal 23). Here, the A signal 22 has the same phase as the received signal 5, and the B signal 23 has the same phase as the received signal 5.
There is a 90 degree phase difference.

Here, each of the signals 22 and 23 is applied to the attenuator 2 of each stage.
The signal is attenuated by 4, 25. For example, assuming that the attenuation is performed by the control signal (FIG. 5) such that the attenuation rate of the attenuator 24 is 100% when the attenuation rate of the attenuator 24 is 0%, When the rate is 0% and the attenuation rate of the attenuator 25 is 100%, the signal coming into the adder 26 is the B signal 23.
The output signal is a signal having a phase difference of 90 degrees from the received signal.

Further, the attenuation rate of the attenuator 24 is 100%, and that of the attenuator 2 is
When the attenuation rate of 5 is 0%, the only signal that enters the adder 26 is the A signal 22, and the output signal is the same phase as the received signal 5. Furthermore, when the attenuation rate of the attenuator 24 is 50% and the attenuator of the attenuator 25 is 50%, the signal that enters the adder 26 is one half of the output of the two signals. As the output, a signal having a phase difference of 45 degrees with the received signal 5 is obtained. Thus, depending on the attenuation rate of each attenuator, the adder
The output signal obtained from 26 is from the phase of the received signal 5 and 0.
It will be 90 degrees off. By providing a plurality of the variable phase difference generation means, it becomes possible to freely change the phase difference.

FIG. 4 is a block diagram of the attenuator used in this embodiment. This attenuator is configured by combining a resistor 44, a capacitor 45, a coil 46, and a diode 47, respectively. In this embodiment, a low frequency signal (for example,
Attenuation is performed by inputting a sawtooth wave (Fig. 5) at 1 KHz, but in addition to this, as the control signal 47, a triangular wave (Fig. 6) may be input at a cycle of 1 KHz. Here, since the control input signal 33 inputs different signals,
The two signals only attenuate in the same way with the same attenuation rate,
The situation is such that the phase is not shifted by simply attenuating.

In addition to the control signal input 33 to the attenuator,
As a circuit power supply, a constant voltage is applied as the constant voltage input 46, and by performing these two inputs, the signal input from the signal input unit 31 can be attenuated.

A parallel connection type is also shown as another example of the variable phase difference generating means (FIG. 7). As for FIG. 7,
As in the case of FIG. 2, it is possible to shift the phase from 0 degrees to 270 degrees at the maximum, and thereby it is possible to reliably derive the minimum value to the maximum value of the output for an arbitrary distance.

FIG. 8 shows a block diagram of the judging section 7. The determination unit 7 includes an AC amplifier 80 that amplifies the low-frequency output 10 with reference to GND, a maximum value extraction unit 84 that extracts the maximum value of the output from the AC amplifier 80, and an output from the maximum value extraction circuit 84. And a threshold value, and a comparison determination unit 85 for determining the presence or absence of the object.

Here, the maximum value extraction circuit 84 is composed of a diode 83, a resistor 82, and a capacitor 81 in FIG. 8 of the present embodiment, and this circuit extracts the distance between the origin and the maximum value. This can be done, and this distance is transmitted to the comparison / determination means 85 to derive the distance between the object and the sensor.

FIG. 9 shows a decision operation diagram in the comparison decision section 52. The comparison determination unit 85 compares the distance from the origin obtained from the maximum value extraction circuit 84 with the threshold value. This time,
If the sensor device of the present invention is simply an on / off sensor, one threshold value is set, and the presence or absence of a proposal is determined by whether or not the output reaches the threshold value.
Further, when the sensor device of the present invention is a distance measuring sensor for measuring the distance to the object, a plurality of thresholds are provided, and the operation of FIG. 6 is sequentially performed for each threshold to derive the distance.

When the judgment circuit and the judgment method as in this embodiment are used, the output value with respect to the distance appears on the parabola. By using this characteristic, it becomes possible to perform distance measurement. Distance measurement is easy to measure when an object is a specific object, but first, for a specific object, the distance-
The output characteristic is stored in advance and used as a threshold. By comparing the magnitude of the signal due to the reflected wave from the object with this threshold value, the distance at which the object exists can be derived (Fig. 10).

Further, FIG. 11 shows an overall schematic view of a sensor device having the variable phase difference generating means 8 on the transmitter side. Here, the variable phase difference generating means 8 is provided on the line between the signal generator 1 and the transmission antenna 2 and between the branch point for transmitting a signal from the signal oscillator 1 to the mixer section and the transmission antenna 1. Is. As a result, it is possible to obtain the same output as that provided with the variable phase difference generating means 8 on the receiving side shown above, and it is possible to extract the maximum value and the minimum value. It becomes possible to perform it more accurately.

Next, FIG. 12 shows an overall schematic view of a sensor device in which the variable phase difference generating means 8 is provided on a line for transmitting a transmission signal from the transmitting portion side to the mixer portion 6. As shown in FIGS. 11 and 12, variable phase difference generation means can be provided not only on the reception side but also on the transmission side and the line to the mixer section, so the variable phase difference generation means is inserted according to the circuit configuration of the sensor device. And can be incorporated into various circuit patterns.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a sensor device including a phase difference generation unit on a receiver side.

[Fig. 2] Configuration diagram of variable phase difference generation means

[Fig. 3] Detailed view of variable phase difference generation means

[Fig. 4] Detail of attenuator

[Figure 5] Attenuator control signal (sawtooth wave)

[Figure 6] Attenuator control signal (triangular wave)

[Fig. 7] Configuration diagram of variable phase difference generation means (parallel)

[Figure 8] Judgment unit configuration diagram

[Fig. 9] Judgment operation diagram of judgment unit

[Figure 10] Conceptual diagram of measurement when using for distance measurement

FIG. 11 is an overall configuration diagram of a sensor device including a phase difference generation unit on a transmitter side.

FIG. 12 is an overall configuration diagram of a sensor device including a phase difference generation unit on a line from a transmission side to a mixer unit.

[Explanation of symbols]

1: signal generator, 2: transmission antenna, 3: transmission signal,
4: reception antenna, 5: reception signal, 6: mixer section,
7: Judgment unit, 8: Variable phase difference generation means, 9: Phase difference output, 10: Low frequency output, 21: Fixed phase difference generation means, 22a: A
Signal, 22b: B signal, 23: adder, 24a, b: attenuator, 25
a: C signal, 25b: F signal, 26a: D signal, 26b: E signal, 27
a: G signal, 27b: H signal, 28: Resistance, 41: Signal input section, 4
2: Constant voltage input section, 43: Control signal input section, 44: Resistor, 4
5: capacitor, 46: coil, 47: diode, 48 signal output section, 51: control signal of attenuator 24a, 52: control signal of attenuator 24b, 61: control signal of attenuator 24a, 62: attenuator 24b Control signal, 71: fixed phase difference generating means, 72: attenuator, 73: adder, 74: divider, 75: adder, 76: resistor, 81: capacitor, 82: resistor, 83: diode, 84: operational amplifier , 8
5: Comparison / determination unit, 91: Phase-modulated transmission wave, 92: Phase-modulated reception wave

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mie Ikushima             2-1-1 Nakajima, Kokurakita-ku, Kitakyushu City, Fukuoka Prefecture             No. Totoki Equipment Co., Ltd. F term (reference) 5J070 AB15 AC02 AH14 AK02 AK22

Claims (9)

[Claims] 1. A transmission unit for transmitting an electric wave generated by a signal generator, a reception unit for receiving a reflected wave of a transmission signal transmitted from the transmission unit, and the transmission signal and a reception signal received by the reception unit. In a sensor device having a mixer unit that converts the difference between the signal and the signal into a signal, and a determination unit that determines the presence or absence of an object from the output of the mixer unit, the phase of the signal on the line between the receiving unit and the mixer unit. A variable phase difference generating means capable of continuously changing at least 0 to 180 degrees. 2. A transmission unit for transmitting an electric wave generated by a signal generator, a reception unit for receiving a reflected wave of a transmission signal transmitted from the transmission unit, and the transmission signal and a reception signal received by the reception unit. A branch point for transmitting a signal from the signal generator to the mixer unit in a sensor device having a mixer unit for converting the difference between the signal generator and the mixer into a signal and a determination unit for judging the presence or absence of an object from the output of the mixer unit. A sensor device comprising variable phase difference generation means capable of continuously changing the phase of a signal within a range of at least 0 to 180 degrees on a line between the mixer section and the mixer section. 3. A transmission unit for transmitting an electric wave generated by a signal generator, a reception unit for receiving a reflected wave of the transmission signal transmitted from the transmission unit, and the reception signal received by the transmission signal and the reception unit. A branch point for transmitting a signal from the signal generator to the mixer unit in a sensor device having a mixer unit for converting the difference between the signal generator and the mixer into a signal and a determination unit for judging the presence or absence of an object from the output of the mixer unit. A sensor device comprising a variable phase difference generating means capable of continuously changing the phase of a signal in a range of at least 0 to 180 degrees on a line between a transmitter and a transmitter. 4. The variable phase difference generating means includes fixed phase difference generating means for generating a specific phase difference and outputting a plurality of signals, and a plurality of attenuators for attenuating the plurality of output signals. The sensor device according to any one of claims 1 to 3, wherein: 5. The sensor device according to claim 4, wherein the attenuator controls the attenuation rate of each attenuator by an electric signal from the outside. 6. The sensor device according to claim 4, wherein the electric signal to the attenuator is a triangular wave. 7. The sensor device according to claim 4, wherein the electric signal to the attenuator is a sawtooth wave. 8. The sensor device according to claim 4, wherein the variable phase difference generating means includes an adding device that adds the signals attenuated by the attenuator. 9. The sensor device according to claim 1, wherein the determination unit includes an extraction unit that extracts only the maximum value and / or the minimum value of the output from the mixer unit.