JPH0481681A - Ultrasonic sensor - Google Patents

Abstract

PURPOSE:To apply a small-sized and inexpensive ultrasonic sensor in a wide field by sending ultrasonic signals to a target by means of a single ultrasonic oscillator which serves both as a wave transmitter and a wave receiver. CONSTITUTION:An oscillation circuit 1 oscillates at resonance frequency of an ultrasonic oscillator 2, and its oscillation output is converted into ultrasonic waves by the ultrasonic oscillator 2 to be sent to a target 3. The sent ultrasonic waves are reflected by the moving target 3, and an electric signal comprising a combination of an electric signal received and converted by the ultrasonic oscillator 2 and a wave transmission output signal applied to the ultrasonic oscillator 2 for sending the ultrasonic waves is influenced by a change in impedance of the ultrasonic oscillator generated by a positional relation between the ultrasonic oscillator 2 and the target so that the synthesized electric signal fluctuates. The fluctuating electric signal is detected by a wave detecting circuit 4, and a resonance frequency component of the ultrasonic oscillator 2 is cut by an LPF 5 to take out only a fluctuation voltage component so that it is amplified by an amplifying circuit 6 to be output.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) The present invention is an ultrasonic sensor that transmits and receives ultrasonic waves using one ultrasonic transducer and detects the movement of an object.

11.I Conventionally, there is an ultrasonic Doppler method as a method for extracting the movement of an object.

As shown in FIG. 2, the conventional ultrasonic Doppler method uses an oscillation circuit 7 to oscillate at the resonant frequency of a transmitting transducer 8
The transmitting transducer 8 converts it into an ultrasonic wave and transmits the ultrasonic signal, and the reflected signal of the ultrasonic wave reflected from the moving object 3 (for example, a moving fish) is used as a receiving vibration. After the wave is received by the transmitter 9 and converted into an electric signal, it is amplified by the amplifier circuit 10.
A mixing circuit 11 performs mixing with an electric signal for transmission, and the wave is detected by a detection circuit 12 to detect a Doppler signal.

However, the ultrasonic Doppler detection device configured in this way has dedicated ultrasonic transducers for transmitting and receiving waves, and requires a mixing circuit to detect the Doppler signal, so the sensor (Resonator) The disadvantage was that the shape was large, difficult to process, and the cost was high.

In order to solve the above-mentioned problems, the present invention aims to solve the above problems.
One that has two ultrasonic transducers, one for wave reception only,
By using one transducer for both transmitting and receiving waves, even though it has a mixing circuit, it is able to detect the fluctuating voltage that occurs between the electrodes of the ultrasonic transducer in response to the movement of the object. The present invention transmits an ultrasonic signal to a target object (a moving object) using one ultrasonic transducer that serves both as a transmitter and a receiver.
An electric signal generated at the electrode of the ultrasonic transducer by receiving the ultrasonic reflected signal reflected from the target object by the ultrasonic transducer, and an electrode of the ultrasonic transducer for transmitting the ultrasonic wave. The electric signal generated by combining the transmitted wave output signal added to Electrical signals fluctuate.

By inputting the electric signal that fluctuates in response to the movement of the object into the electric circuit, only the voltage component that fluctuates in response to the movement of the object can be extracted.

Figure 1 shows a circuit configuration diagram of an embodiment of the present invention, in which an oscillation circuit 1 oscillates at the resonant frequency of an ultrasonic transducer 2,
The oscillation output is converted into ultrasonic waves by the ultrasonic transducer 2, and the ultrasonic waves are transmitted to the object 3.

The transmitted ultrasonic wave is reflected by a moving object 3, and this ultrasonic reflected signal is received by an ultrasonic transducer 2 and converted into an electric signal and an ultrasonic wave to transmit the ultrasonic wave. The electrical signal that is synthesized with the transmission output signal applied to the transducer 2 is affected by the impedance change of the ultrasonic transducer that occurs due to the positional relationship between the N-sonic transducer 2 and the target object, and the synthesized electrical signal is generated. The signal fluctuates.

This fluctuating electric signal is detected by a detection circuit 4, the resonance frequency component of the ultrasonic transducer 2 is cut by a low-pass filter 5, and only the fluctuating voltage component is taken out, which is amplified by an amplifier circuit 6 and output.

i Bean Skin 11 As is clear from the above description, the present invention provides a small and low-cost ultrasonic sensor that can detect the movement of an object using a single vibrator that serves both for transmitting and receiving waves. can be provided to a wide range of fields.

For example, a new type of fish finder that can obtain a variety of information based on the movement of fish, medical equipment that detects heart movement and blood flow, and household equipment that requires lower prices (priest detection, human detection switches, etc.) We can provide products using ultrasonic sensors that can detect movement, especially in fields where low cost and small size are required.

FIG. 1 is a circuit configuration diagram of an embodiment of the present invention, and FIG. 2 is a circuit configuration diagram for explaining another conventional example.

DESCRIPTION OF SYMBOLS 1... Oscillation circuit, 2... Ultrasonic transducer, 3... Moving object, 4... Detection circuit, 5... Low pass filter 6... Amplification circuit, 7. Oscillation circuit , 8...
・Transmission vibrator, 9... Wave reception vibrator, 10... Amplification circuit, 11... Mixing circuit, 12... Detection circuit, 13... Amplification circuit

Claims (1)

[Claims] Ultrasonic waves that are characterized by extracting the varying voltage between the electrodes of the ultrasonic transducer in response to the movement of an object caused by transmitting ultrasonic waves with one ultrasonic transducer and simultaneously receiving reflected waves. sensor.