JPH0527017A - Object detecting device - Google Patents

Abstract

PURPOSE:To provide an object detecting device capable of detecting the existence and movement of an object between transmitting and receiving antennas over a certain wide range by observing the change of the oscillating frequency from the changes in the phase difference between the transmitted signal and the received signal with phase delay. CONSTITUTION:An object detecting device is provided with a transmitting antenna 1 and a transmitting circuit 3 to radiate the carrier wave modulated by the modulated signal of a certain frequency, and a delayed signal loop part 9 which is comprises a receiving antenna 2 and a receiving circuit 4 which change the carrier wave radiated from the transmitting antenna 1 and the transmitting circuit 3 to the modulated signal by reception and demodulation. There are in addition provided an oscillating circuit part 10 to generate a certain frequency, a coupled circuit 5 to couple the delay time of the demodulation signal for the modulation signal of a certain frequency with the oscillating circuit part 10 as the phase delay characteristic, and a frequency detecting device 8 to detect the changes in the oscillating frequency of the oscillating circuit part 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object detecting device for detecting the presence / absence and movement of an object within a limited range.

[0002]

2. Description of the Related Art As shown in FIG. 2, a conventional object detecting apparatus transmits a transmission signal generated from an oscillation circuit 11 to a transmission circuit 12 when an object does not exist between a light emitting section 13 and a light receiving section 14. The light emitted from the light emitting unit 13 via the light receiving unit 14
The threshold value circuit 16 determines that an object does not exist via the receiving circuit 15 and displays it on the output display unit 17. When an object exists between the light emitting unit 13 and the light receiving unit 14, the light emitted from the light emitting unit 13 is blocked by the object and is not received by the light receiving unit 14, and the object exists in the threshold circuit 16. Was determined and displayed on the output display 17. The same was true when transmitting and receiving by radio waves instead of light.

[0003]

However, the conventional object detecting device is erroneously operated unless the object completely blocks the light, or can detect only a narrow range due to the straightness of the light.

The present invention has been made in view of the above circumstances, and by observing a change in the oscillation frequency from a change in the phase difference between the transmission signal and the reception signal having a phase delay, the object between the transmitting and receiving antennas can be detected. It is an object of the present invention to provide an object detection device capable of detecting the presence or absence and movement and capable of detecting a wide range to some extent.

[0005]

In order to solve the above problems, the present invention provides a transmitting antenna and a transmitting circuit for radiating a carrier wave modulated by a modulation signal of a certain constant frequency, and a transmitting antenna and a transmitting circuit for radiating the carrier wave. A delay signal loop unit including a receiving antenna and a receiving circuit that receives and demodulates a carrier wave and a demodulated signal, an oscillator circuit unit that generates the certain constant frequency, and the demodulation for the modulated signal of the certain constant frequency. It is characterized by comprising a coupling circuit that couples the signal delay time as a phase delay characteristic to the oscillation circuit section, and a frequency detection device that detects a change in the oscillation frequency of the oscillation circuit section.

[0006]

The present invention uses radio waves and utilizes not the interruption of radio signal but the change of the phase delay caused by the presence or the movement of an object. That is, the presence / absence and movement of an object in the radio wave transmission line are detected by including the radio wave transmission line in the oscillation circuit as a delay signal loop unit and observing a phase change in the radio wave transmission line as a change in the oscillation frequency.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the object detecting device of the present invention. In FIG. 1, the transmission antenna 1 and the transmission circuit 3 radiate a carrier wave modulated by a modulation signal having a certain constant frequency. The receiving antenna 2 and the receiving circuit 4 receive and demodulate the carrier waves radiated from the transmitting antenna 1 and the transmitting circuit 3 to obtain demodulated signals. The delay signal loop unit 9 is composed of the transmitting antenna 1 and the transmitting circuit 3, and the receiving antenna 2 and the receiving circuit 4. The oscillator circuit unit 10 is composed of an RC circuit 6 and an amplifier circuit 7, and generates the certain constant frequency. The coupling circuit 5 couples the delay time of the demodulated signal with respect to the modulated signal of the certain constant frequency to the oscillation circuit section 10 as a phase delay characteristic. The frequency detection device 8 detects a change in the oscillation frequency of the oscillation circuit section 10. That is, the delay circuit loop unit 9 including the radio wave transmission path is combined with the oscillation circuit unit 10 made in advance by the coupling circuit 5. The signal V1 oscillated by the oscillator circuit section 10 is radiated as a radio wave signal from the transmitting antenna 1 and enters the delay signal loop section 9. The radiated radio wave signal is received by the receiving antenna 2
And is demodulated by the receiving circuit 4 as a signal V3. This signal V3 has a phase delay with respect to the signal V1.
A phase change of the signal V3 having a phase delay occurs due to the presence or absence of an object and the movement between the transmitting antenna 1 and the receiving antenna 2. When this signal V3 is applied to the oscillation circuit section 10, the oscillation condition changes and the oscillation frequency changes. The change in the oscillation frequency of the oscillation circuit section 10 is detected by the frequency detection device 8.

With the above-mentioned structure, the change in the oscillation frequency can be observed from the change in the phase difference between the transmission signal and the reception signal having a phase delay. Moreover, it is effective in a wide range to some extent. This can be seen from the following.

Arrival from the transmitting antenna 1 to the receiving antenna 2
Landing waves are generally not only direct waves, but many reflected waves and waves.
It is represented by a composite wave of multiple waves such as broken waves. 2 waves as an example
Considering the case of, and expressing them as A1 = a1.exp (j.omega.t) and A2 = a2.exp (j.omega.t), respectively, the composite wave is expressed by the equation (1). A1 + A2 = A · exp (j ψ) …………………… (1) where A ＝ (B² + C² )^1/2 _{B = {a1 + a2 ・ cos (2 πΔl / λ)} ・ cos ωt −a2 · sin (2 πΔl / λ) · sin ωt C = {a1 + a2 ・ cos (2 πΔl / λ)} ・ sin ωt + A2 ・ sin (2 πΔl / λ) ・ cos ωt ψ = tan} -1 (C / B) = f (a1, a2) Δl: Path difference between transmission signal and reception signal ψ: Phase difference between transmission signal and reception signal λ: Wavelength of carrier wave

Therefore, since ψ is a function of a1 and a2,
Ψ also changes depending on the amplitude of one component of the multiple wave, regardless of the direct wave. That is, it is possible to observe the change in the oscillation frequency even in the presence or movement of an object in a place where the direct wave is not blocked within the reach of the radio wave. this is,
It goes without saying that multiple waves of two or more waves are also possible.

[0011]

As described above, according to the present invention, it is possible to detect the presence or absence and the movement of an object between the transmitting and receiving antennas by observing the change of the oscillation frequency from the phase change of the signal in the delay signal loop. There is. Moreover, since radio waves are used, there is an effect that detection can be performed in a wide range to some extent.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of the present invention.

FIG. 2 is a structural explanatory view showing a conventional object detection device.

[Explanation of symbols]

1 ... Transmission antenna, 2 ... Reception antenna, 3 ... Transmission circuit,
4 ... Receiving circuit, 5 ... Coupling circuit, 6 ... RC circuit, 7 ... Amplifying circuit, 8 ... Frequency detecting device, 9 ... Delay signal loop section, 1
0 ... Oscillation circuit section.

Claims (1)

Claim: What is claimed is: 1. A transmission antenna and a transmission circuit for radiating a carrier wave modulated by a modulation signal of a certain constant frequency, and a carrier wave radiated from the transmission antenna and the transmission circuit.
A delay signal loop unit including a reception antenna and a reception circuit that demodulates to a demodulation signal, an oscillation circuit unit that generates the certain constant frequency, and a delay time of the demodulation signal with respect to the modulation signal of the certain constant frequency An object detection device comprising: a coupling circuit coupled to the oscillation circuit unit as a phase delay characteristic; and a frequency detection device that detects a change in an oscillation frequency of the oscillation circuit unit.