JPH02171685A - Detecting device of moving body - Google Patents

Abstract

PURPOSE:To simplify a circuit construction and to reduce the cost by a method wherein outputs of two systems obtained from a pair of mixer circuits are subjected to a time-division processing by a switch circuit and thereby made usable as a signals of one system. CONSTITUTION:A wave reception signal Ein is mixed with reference signals Eo and Eo' and detected in mixer circuits 11a and 11b. As the result, a pair of Doppler signals E and E' obtained as beat signals are different in phase from each other. The two Doppler signals E and E' are inputted to a switch circuit 15. The switch circuit 15 is constructed of an analog switch and subjected to a switching control in synchronization with a timing signal T of a prescribed period outputted from a timing circuit 16. Then, an output of a quadrant signal generating circuit 14 is integrated in an arithmetic circuit 17, and when the absolute value of an integrated value exceeds threshold values Rfh and Rf1, a detection signal is outputted. By this constitution, a circuit construction in a stage behind the mixer circuits is simplified and thereby the cost is reduced.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention emits continuous energy waves such as ultrasonic waves into a monitoring space and detects the frequency shift of the reflected waves caused by the movement of an object. The present invention relates to a moving object detection device that detects the presence of an object moving in space.

[Prior Art] Generally, this type of moving object detection device emits continuous energy waves such as ultrasonic waves of a predetermined frequency into a monitoring space.
It is configured to detect the frequency shift of reflected waves that occurs as a Doppler effect as the object moves.

The configuration shown in Figure 6 is known as one that realizes the detection of moving objects in this way (Japanese Patent Publication No. 62-4350
In this configuration, the output from the oscillation circuit 10 is converted into ultrasonic waves by the transmitter 1 and radiated into the monitoring space, and the reflected waves from the moving object are received by the receiver 2. It is converted into a wave signal Ein. The received signal Ein is sent to the mixer circuit 11.
Reference signals E o and E o ' are provided at a and 11b, respectively.
A pair of Doppler signals E, which are beat signals, are mixed with
E' can be obtained. One reference signal E0
is obtained by passing the output of the oscillation circuit 10 through the phase shift circuit 12,
The other reference signal Eo' is obtained as the output of the oscillation circuit 10. Therefore, both reference signals E. , E0' have different phases. As a result, mixer circuits 11a, l
A pair of Doppler signals E and E' obtained as beat signals at the output of lb also have different phases. The Doppler signals E and E' are converted into binary numbers by circuits 21a and 2, respectively.
“H” or “L” depending on whether the signal is positive or negative through 1b.
” is assigned and converted into the axis code signals X and Y. Since each of the axis code signals X and Y has two values, four states can be expressed by a combination of the two. These four states represent both Doppler signals E and E at the same time.
It represents the quadrant on the vector plane in which the vector whose component is ' exists. Therefore, if the combination of code signals X and Y is detected by the quadrant detection circuit 22, quadrant signals I to (2) corresponding to the quadrant in which the above-mentioned vector exists can be obtained. These quadrant signals r~■ are input to the quadrant transition direction detection circuit 23, and when the quadrant in the vector plane in which the vector exists changes, it is detected whether the change occurs clockwise or counterclockwise. . That is, when the quadrant transition direction detection circuit 23 detects a quadrant transition, it generates a transition signal Z' consisting of a bipolar pulse having a positive or negative sign corresponding to the direction of the transition, and detects the next transition. The state remains the same until a signal is generated. The transition signal Z' is input to the integrating circuit 24, an integral value corresponding to the time when the transition signal Z' in the same direction is generated is obtained, and the output value of the integrating circuit 24 is set to a threshold value preset in the threshold circuit 25. A detection signal is obtained when the value exceeds . The detection signal is input to the alarm drive circuit 26, and the presence of the moving object is notified.

As described above, by monitoring how the quadrant on the vector plane in which the vector whose components are the signals Eo and Eo' changing, the presence of a moving object in the monitoring space can be determined. can be detected.

[Problems to be Solved by the Invention] In the above configuration, there are two circuits from the mixer circuits 11a and llb to the quadrant detection circuit 22, so the circuit configuration is complicated and becomes a bottleneck for cost reduction. ing.

The present invention aims to solve the above-mentioned problems, and provides a moving object detection device whose cost is reduced by simplifying the circuit configuration.

[Means for Solving the Problem] In order to achieve the above object, the present invention includes a switch circuit that alternately passes the outputs of both mixer circuits at predetermined time intervals;
When the quadrant on the vector plane of a vector whose components are the Doppler signal output from one mixer circuit and the Doppler signal output from the other mixer circuit that is input to this Doppler signal subsequently changes, the direction of the change changes. It also includes a quadrant transition signal generation circuit that generates a corresponding quadrant transition signal.

In addition, there is a switch circuit that passes a pair of reference signals that have the same frequency as the transmission signal but different phases from each other at predetermined time intervals, and a mixer circuit that mixes the reference signal that has passed through the switch circuit with the reception signal and converts it into a Doppler signal. When the quadrant on the vector plane of a vector whose components are a Doppler signal corresponding to one reference signal and a Doppler signal corresponding to the other reference signal inputted subsequently to this Doppler signal changes, the direction of change changes. A quadrant transition signal generation circuit that generates a corresponding quadrant transition signal may also be provided.

[Operation] According to the first configuration, the outputs of two systems obtained from a pair of mixer circuits can be treated as one system of signals by time-division processing using a switch circuit. This simplifies the circuit configuration in subsequent stages, leading to lower costs.

Further, according to the second configuration, since the pair of reference signals can be time-division processed and input to the mixer circuit as l-system signals, there is only one mixer circuit, which further simplifies the circuit configuration. can be achieved.

[Embodiment 1] A block diagram of this embodiment is shown in FIG. 1. The 6-oscillation circuit 10 continuously oscillates at a constant frequency. The output of the 0-oscillation circuit 10 is input to the transmitter 1, and ultrasonic waves are emitted into the monitoring space. be done. If an object exists in the monitoring space, the reflected wave is received by the receiver 2 and converted into a received signal Ein. Received signal E
in is input to a pair of mixer circuits 11a and 11b, respectively, and mixed with reference signals E 1 , , E 2 , and ′ having the same frequency as the output frequency of the oscillation circuit 10 . One reference signal E0
is input through the phase shift circuit 12, and the phase shift circuit 12
Since the phase of the input signal is advanced by 90 degrees and outputted, both reference signals E, , E,' have a phase difference of 90 degrees from each other. As a result of mixing and detecting the received signal Ein with the reference signals Eo and Eo' in the mixer circuits 11a and llb, a pair of Doppler signals E are obtained as beat signals.
, E' also have different phases (Fig. 3(a)
) See (b)) 0 Doppler signal E.

E' is input to the switch circuit 15. switch circuit 1
5 is composed of an analog switch, and is switched and controlled in synchronization with a timing signal T of a constant period outputted from a timing circuit 16 (see FIG. 3(c)). In other words, the switch circuit 15 has two inputs. It binarizes the data and passes it through alternately at a constant period. The output of the switch circuit 15 is input to the amplifier circuit 13 and amplified (1k<see FIG. 3(d)), and the quadrant transition signal generation circuit 14
is input. The quadrant transition signal generation circuit 14 reads and holds the output of the amplifier circuit 13 in synchronization with the timing signal T, and generates axis code signals X and Y similar to the conventional one (Fig. 3(e) and (f)). ), the axis code signal It is created corresponding to the signal S. When the timing signal T rises or falls, if the output signal S of the amplifier circuit 13 does not change from the previous state, the axis code signals X and Y are maintained as they are. By the way, as shown in FIG. 2, the reference signal Eo.

Assuming that the phase difference of Eo' is 90° and considering a quadrant on the vector plane in which a vector whose components are Doppler signals E and E' exists, the movement of an object in the monitoring space is replaced by a change in the direction of the vector. be able to. Therefore, there are four states depending on the polarity combinations of the Doppler signals E and E'! 'II(
If we consider positive and negative, positive and negative, negative and negative, we can represent quadrants 1 to ■ where vectors exist on the vector plane (
(See Figure 3(g)).

By performing such signal processing, the quadrant transition signal generation circuit 14 detects the quadrant on the vector plane in which the vector whose components are the Doppler signals E , , E , ' exists, and when the quadrant changes, the change occurs. A quadrant transition signal is output, which is a pair of a direction signal Z (see Fig. 3 (h)) indicating whether the quadrant has occurred counterclockwise or clockwise, and a transition signal Q indicating that there has been a change in the quadrant. . Here, the timing signal T
The period is set to be short enough to detect the movement of the object.

Further, FIG. 3 corresponds to the state in which the vector moves as shown in FIG. 2.

The output of the quadrant signal generation circuit 14 is integrated by an arithmetic circuit 17, and when the absolute value of the integrated value exceeds thresholds Rfh and Rfl set in advance by a threshold circuit 18, a detection signal is outputted through a detection signal output circuit 19. (Figure 3 (i)
In other words, a detection signal is obtained when the difference in the number of times a positive direction signal and a negative direction signal occur exceeds a certain value.

In the above embodiment, the signal is delayed by the time width of the timing signal T at most with respect to the actual movement of the object, but in this type of moving object detection device, once the tendency of movement of the object is known, That's fine, so the slight time difference is not a problem.

[Embodiment 2] In this embodiment, as shown in FIG. 4, the output of the oscillation circuit 10 is branched into two systems, one of which is passed through the phase shift circuit 12, and then
The output of the oscillation circuit 10 and the output of the phase shift circuit 12 are input to a switch circuit 15.

The switch circuit 15 alternately selectively switches between the output of the oscillation circuit 10 and the output of the phase shift circuit 12 at fixed time intervals based on the timing signal T (see FIG. 5(a)) which is the output of the timing circuit 16. pass through.

Therefore, a pair of reference signals E o with mutually different phases
, E o ' are obtained alternately at regular intervals (see FIG. 5(b)), that is, the mixer circuit 11
Then, the received signal Ein is alternately mixed with reference signals Eo and Eo' having different phases at regular intervals,
A pair of Doppler signals E and E' having different phases can be obtained alternately at regular intervals as the output of the mixer circuit 11. These Doppler signals E and E' are transmitted to an amplifier circuit 13.
After being input to and amplified (see FIG. 5(c)), the signal is input to the quadrant transition signal generation circuit 14. The following operation is the same as in the first embodiment, and the quadrant transition signal generation circuit 14 generates axis code signals Detect the quadrant on the vector plane in which the vector exists (see Figure 5 (f)), and when the quadrant changes, it will be positive or A negative polarity is assigned (see FIG. 5(g)). Thus, when the quadrant is transferred, a direction signal Z representing the direction of transfer and a transfer signal Q indicating that the transfer has occurred are output as a pair.

Since the subsequent processing is the same as in the first embodiment, the explanation will be omitted.

[Effects of the Invention] As described above, the present invention includes a switch circuit that alternately passes the outputs of both mixer circuits at predetermined time intervals, a Doppler signal output from one of the mixer circuits, and a Doppler signal that is input successively to the Doppler signal. and a quadrant transition signal generation circuit that generates a quadrant transition signal corresponding to the direction of change when the quadrant on the vector plane of the vector whose components include the Doppler signal output from the other mixer circuit changes. By time-sharing processing the two systems of output obtained from a pair of mixer circuits using a switch circuit, it is possible to treat them as one system of signals, which simplifies the circuit configuration at the stage after the mixer circuit. This has the advantage of leading to cost reduction.

In addition, there is a switch circuit that passes a pair of reference signals that have the same frequency as the transmission signal but different phases from each other at predetermined time intervals, and a mixer circuit that mixes the reference signal that has passed through the switch circuit with the reception signal and converts it into a Doppler signal. When the quadrant on the vector plane of a vector whose components are a Doppler signal corresponding to one reference signal and a Doppler signal corresponding to the other reference signal inputted subsequently to this Doppler signal changes, the direction of change changes. By providing a quadrant transition signal generation circuit that generates a corresponding quadrant transition signal, the pair of reference signals can be time-division processed and input to the mixer circuit as one signal system, so the mixer circuit can also be divided into one This has the advantage that the circuit configuration can be further simplified.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the first embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams of the same operation as above, FIG. 4 is a block diagram showing the second embodiment of the present invention, and FIG. 5 is the same as above. FIG. 6 is a block diagram showing a conventional example. DESCRIPTION OF SYMBOLS 1... Transmitter, 2... Receiver, 10... Oscillation circuit, 11 a, 1 l b... Mixer circuit, 14...
Quadrant transition signal generation circuit, 15... switch, 16...
- Timing circuit, 17... Arithmetic circuit, 18... Threshold circuit, 19... Detection signal output circuit, E, E'...
de Sopra signal, Ein...received signal, E o ,
E 0'...Reference signal. Agent Patent Attorney Ishi 1) Chief Shichimo 2 Emi 3 Gun 5

Claims (2)

[Claims] (1) An oscillation circuit that oscillates at a predetermined frequency, a transmitter that converts the output from the oscillation circuit into a continuous energy wave and transmits it to the monitoring space, and a receiver that receives reflected waves from moving objects. A receiver that outputs a signal, a pair of mixer circuits that mix a pair of reference signals that have the same frequency as the transmitted signal and have different phases with the received signal and convert them into a pair of Doppler signals that have different phases. A switch circuit that passes the output of the mixer circuit alternately at predetermined time intervals, and a Doppler signal output from one mixer circuit and a Doppler signal output from the other mixer circuit that is input subsequent to this Doppler signal. A quadrant transition signal generation circuit generates a quadrant transition signal corresponding to the direction of change when the quadrant on the vector plane of a vector changes, and when the difference in the number of times quadrant transition signals in both directions are generated exceeds a predetermined value. A moving object detection device comprising: a threshold circuit that outputs a detection signal. (2) An oscillation circuit that oscillates at a predetermined frequency, a transmitter that converts the output from the oscillation circuit into a continuous energy wave and transmits it to the monitoring space, and a receiver that receives reflected waves from moving objects. A receiver that outputs a signal, a switch circuit that passes a pair of reference signals that have the same frequency as the transmitted signal but different phases from each other at predetermined time intervals, and mixes the reference signal that has passed through the switch circuit with the received signal. A quadrant on a vector plane of a vector whose components are a mixer circuit that converts it into a Doppler signal, a Doppler signal corresponding to one reference signal, and a Doppler signal corresponding to the other reference signal inputted subsequently to this Doppler signal. It is equipped with a quadrant transition signal generation circuit that generates a quadrant transition signal corresponding to the direction of change when the change occurs, and a threshold circuit that outputs a detection signal when the difference in the number of times quadrant transition signals in both directions are generated exceeds a predetermined value. A moving object detection device characterized by: