JP3386876B2 - Ultrasonic detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of transmitting an ultrasonic pulse from an ultrasonic vibrator and reflecting a reflected wave from an object to the ultrasonic vibrator or another ultrasonic wave. The present invention relates to an ultrasonic detector that detects presence or absence of an object by receiving a wave with a vibrator. [0002] Conventionally, an ultrasonic pulse is transmitted from an ultrasonic vibrator, and a reflected wave from an object is received by the ultrasonic vibrator or another ultrasonic vibrator. FIG. 5 shows an example of an ultrasonic detector for detecting the presence / absence of an ultrasonic wave. The ultrasonic detector includes an ultrasonic vibrator 1 integrated with a transmitting / receiving wave and a transmitting unit 3 receiving a transmitting signal from the arithmetic and control unit 2.
Driven to ultrasonic pulses by as well as transmit a (see FIG. 6 (a)), the reflected wave from the object (Fig. (B) see)
Is received. [0003] A transmitting section 3 is composed of a transistor Q ₁ inserted on the primary side of a transformer T for boosting an output voltage from a power supply section 5 for supplying power for transmitting ultrasonic pulses. It is turned on and off by the transmission signal, and the transformer T
The amplified transmission signal output to the secondary side is supplied to the ultrasonic vibrator 1 for driving. Note that a reverberation absorbing unit 6 that absorbs reverberation generated in the ultrasonic vibrator 1 is inserted between the secondary side of the transformer T and the ultrasonic vibrator 1. Further, the transmission output of the ultrasonic pulse transmitted from the ultrasonic transducer 1 is determined by the output voltage of the power supply unit 5, the turns ratio of the transformer T, and the like. On the other hand, a reflected wave from an object received by the ultrasonic vibrator 1 is converted into an electric signal, amplified by a signal amplifying unit 7, converted into a pulse signal by a waveform shaping unit 8, and processed by an arithmetic and control unit. 2 is input. The arithmetic control unit 2 performs an arithmetic operation based on the pulse signal corresponding to the reflected wave to detect the presence or absence of an object or measure the distance to the object. Note that the arithmetic control unit 2 receives power supply from the power supply circuit 9. [0005] Generally, in an ultrasonic detector, when water droplets adhered to the ultrasonic vibrator 1 freeze or foreign matter such as mud or snow adheres, reflection occurs. There is a problem that the detection sensitivity of the wave is reduced. Therefore, in order to detect that the abnormality such as adhesion of freezing and foreign matter such as described above occurs in the ultrasonic vibrator 1, the transmitting of the reverberation signal included in the received signal (see FIG. 6 (b)) Focusing on the fact that the time width t _{1 of the} reverberation signal when an abnormality occurs in the ultrasonic vibrator 1 is shorter than the time width t ₀ of the reverberation signal in a normal state where no abnormality occurs, By comparing the time width of the reverberation time with the time width t ₀ of the reverberation signal in a normal state, it is possible to detect whether or not an abnormality has occurred in the ultrasonic vibrator 1 (Japanese Unexamined Patent Application Publication No. 5-232240).
Japanese Unexamined Patent Application Publication No. Hei 5-232241), or a method in which it is determined that an abnormality has occurred when the received signal of the ultrasonic transducer 1 is only a reverberation signal (Japanese Patent Application Laid-Open No. Hei 5-232241). No. 5-42952). However, when the degree of freezing is small or the amount of adhered foreign matter is small, it is difficult to detect an abnormality because the difference in the time width is small. There is a problem that it is difficult to detect the abnormality, and the abnormality cannot be detected until the abnormality occurs and the detection area of the object is considerably narrowed or cannot be detected at all. An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide an ultrasonic detector capable of easily detecting an abnormality occurring in an ultrasonic transducer. According to the first aspect of the present invention, in order to achieve the above object, an ultrasonic pulse is transmitted from an ultrasonic vibrator, and a reflected wave from an object is subjected to the ultrasonic vibration. A transmitting unit for transmitting an ultrasonic pulse by driving an ultrasonic vibrator in an ultrasonic detector for detecting the presence or absence of an object by receiving a wave by a transducer or another ultrasonic vibrator; and a transmitting unit. A power supply unit that supplies power for transmitting an ultrasonic pulse to and supplies a variable amount of power, and a reflected wave from an object received by the ultrasonic vibrator.
To a pulse signal and output from the conversion means
Calculation based on the pulse signal corresponding to the reflected wave
When the existence of the above object and the distance to the object are obtained,
If the time width of the reverberation signal due to transmission is not abnormal
Ultrasonic transducer by comparing the time width in the
And an arithmetic control unit that detects whether an abnormality has occurred in the
Detects whether the ultrasonic transducer is abnormal
The operation control unit controls the power supply unit and supplies it to the transmission unit when performing
It is characterized in that the power is made smaller than in the normal detection state . According to the structure of the first aspect of the present invention, an ultrasonic pulse is transmitted from an ultrasonic vibrator, and a reflected wave from an object is received by the ultrasonic vibrator or another ultrasonic vibrator. In the ultrasonic detector that detects the presence or absence of an object by transmitting, an ultrasonic transducer is driven to transmit ultrasonic pulses, and power is supplied to the transmitting unit for ultrasonic pulse transmission Power supply unit with variable supply power and object received by ultrasonic transducer
Conversion means for converting the reflected wave from
Based on a pulse signal corresponding to the reflected wave output from the
And the distance to the object
And the time width of the reverberation signal due to transmission is abnormal.
By comparing with the time width when it does not occur
A function to detect whether an abnormality has occurred in the ultrasonic vibrator.
With an arithmetic control unit, and an abnormality has occurred in the ultrasonic vibrator.
The arithmetic control unit controls the power supply unit to detect
The power supplied to the wave unit is made smaller than that in the normal detection state, so that the ultrasonic pulse transmitted from the ultrasonic vibrator according to the change in the power supplied from the power supply unit to the transmitting unit. it is possible to change the duration of transmitting the reverberation of received wave by the ultrasonic vibrator in Rukoto changing the transmitting output, attached to the ultrasonic transducer
Detects abnormalities such as a drop in detection sensitivity due to frozen water droplets
The power supply unit supplies power to the object
It is smaller than the level in the normal detection state to detect nothing
The reverberation time of the transmitted wave included in the received wave
It can be shorter than the reverberation time in the normal detection state
Therefore, the above-described abnormality detection can be facilitated. An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit block diagram of the present embodiment. Since the basic configuration is the same as that of the conventional example, common portions are denoted by the same reference numerals and description thereof is omitted. A feature of the present invention resides in a power supply unit 4 for supplying power for transmitting an ultrasonic pulse to the transmitting unit 3. The power supply unit 4 includes first and second two power supply circuits 4 ₁ and 4 _2. The first and second power supply circuits 4 ₁ and 4 ₂ are controlled by a control signal given from the arithmetic control unit 2. Only one of the power supply circuits 4 ₁ and 4 ₂ is selected, and power is supplied to the transmitting unit 3 from the selected power supply circuit.
That is, the first power supply circuit 4 ₁ the control signal is input directly, while the second power supply circuit 4 ₂ are input the control signal is inverted by the inverter IC. In the present embodiment, the first output voltage V ₁ of the power supply circuit 4 ₁ is set higher than the output voltage V ₂ of the second power supply circuit 4 _2. Next, the operation of the ultrasonic detector of this embodiment will be described. First, in the normal detection condition for detecting the presence or absence of an object, the operation control unit 2 stops the second operation of the power supply circuit 4 ₂ by operating the first power supply circuit 4 ₁ by the control signal. That is, the power supply unit 4 includes the first power supply circuit 4
Than it supplies _first output voltages V ₁ to the transmitting unit 3. Then, the ultrasonic transducer 1 is driven by the transmission signal (see FIG. 2A) amplified by the transmission unit 3, and the transmission signal is transmitted as an ultrasonic pulse. On the other hand, in the ultrasonic vibrator 1, reverberation is generated by the transmitted wave, and the reverberation signal is converted into a signal having a certain time width t ₂ as well as a received signal corresponding to the reflected wave from the object and an arithmetic control unit. 2 (see FIG. 2B). Here, in the normal detection state, when an abnormality such as a drop of water attached to the ultrasonic vibrator 1 freezes or a decrease in detection sensitivity due to foreign matter such as mud or snow adhering to the ultrasonic vibrator 1 occurs. The time width t ₃ of the reverberation signal is shorter than when no abnormality occurs (see FIG. 2C). The arithmetic control unit 2 compares the time width of the reverberation signal with the time width in a state where no abnormality has occurred to detect whether or not the above-described abnormality has occurred in the ultrasonic transducer 1. I have. However, the difference in the time width of the reverberation signal in the normal detection state is small, and it is difficult to detect the occurrence of an abnormality. Therefore, in the ultrasonic detector according to the present embodiment, when it is attempted to detect whether or not the ultrasonic vibrator 1 is abnormal, the arithmetic and control unit 2 uses the control signal to control the first power supply circuit. 4 the _first operation to operate the second power supply circuit 4 ₂ is stopped, the second power supply circuit 4 ₂
It supplies the output voltage V ₂ to the transmitting unit 3. However, the second
Since the output voltage V ₂ of the power supply circuit 4 ₂ is set the first power supply circuit 4 _first output voltages V ₁ lower than the peak of the amplified transmit signal by the transmitting unit 3 - peak voltage Vpp '
The peak of the transmitting signal when the first output voltage V ₁ of the power supply circuit 4 ₁ is supplied to the transmitting unit 3 - smaller than the peak voltage Vpp (see FIG. 2). Therefore, the time width t ₅ of the reverberation signal when an abnormality occurs in the ultrasonic transducer 1 (see FIG. 2 (f)).
And the time width t ₄ of the reverberation signal when no abnormality occurs.
The difference between (see FIG. 2 (e) see) is greater than the difference in the case where the power supply to the transmitting unit 3 from the first power supply circuit 4 _1,
It is possible to easily detect the occurrence of abnormality in the ultrasonic transducer 1. Further, according to the above configuration, the occurrence of abnormality of the ultrasonic oscillator 1 can be detected at an early stage, and therefore, as shown in FIG. The difference between the detection area B reduced due to the occurrence of the abnormality and the detection area A ′ in the conventional configuration shown in FIG. 4 is sufficiently smaller than the difference between the detection area B ′ reduced due to the occurrence of the abnormality. can do. As a result, the reliability when using the ultrasonic detector can be improved. Furthermore, taking advantage of the fact that the detection area becomes smaller, objects that do not normally need to be detected (such as the ground)
Can be prevented from being detected, and there is an advantage that erroneous detection can be prevented . According to the first aspect of the present invention, an ultrasonic pulse is transmitted from an ultrasonic vibrator, and a reflected wave from an object is received by the ultrasonic vibrator or another ultrasonic vibrator. In the ultrasonic detector that detects the presence or absence of an object by transmitting, an ultrasonic transducer is driven to transmit ultrasonic pulses, and power is supplied to the transmitting unit for ultrasonic pulse transmission Power supply unit with variable power supply and an object received by the ultrasonic transducer
Conversion means for converting the reflected waves into pulse signals;
Based on the pulse signal corresponding to the reflected wave output from the stage
Calculation to determine the existence of the object and the distance to the object.
And the time width of the reverberation signal due to transmission is abnormal.
By comparing with the time width in the state without producing
Calculation to detect whether or not the ultrasonic transducer is abnormal
Control unit to check if an ultrasonic transducer is abnormal
The arithmetic control unit controls the power supply unit to detect
Since the power supplied to the unit is smaller than in the normal detection state ,
Reception by the ultrasonic vibrator in Rukoto changing <br/> the transmitting output of the ultrasonic pulse transmitting from an ultrasonic transducer in accordance with the change of the power supplied to the transmitting unit from the power supply unit Can change the reverberation time width of the transmitted wave,
Detects abnormalities such as reduced detection sensitivity due to freezing of water droplets
In this case, the arithmetic and control unit determines whether the power
Make the level lower than the level in the normal detection state to detect
The reverberation time of the transmitted wave included in the received wave
Can be shorter than the reverberation time in the intellectual state
Freezing of water droplets attached to the ultrasonic vibrator
Abnormalities such as a decrease in detection sensitivity due to foreign matter adhering to
This has the effect of being able to be detected. Also frozen
The degree of freezing is relatively light when abnormalities such as
Operation can be detected in the initial state
Prevents erroneous detection of ultrasonic transducer abnormalities in the part and ensures reliability
There is an effect that the performance can be improved .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit block diagram showing an embodiment. FIGS. 2A to 2F are diagrams for explaining the operation of the above. FIG. 3 is a diagram showing a detection area according to the first embodiment; FIG. 4 is a diagram showing a detection area of a conventional ultrasonic detector. FIG. 5 is a circuit block diagram showing a conventional example. FIGS. 6 (a) to 6 (c) are views for explaining the operation of the above.
FIG. [Description of Signs] 1 Ultrasonic transducer 2 Operation control unit 3 Transmitting unit 4 Power supply unit 4 ₁ First power supply circuit 4 ₂ Second power supply circuit IC Inverter T Transformer Q ₁ Transistor

Claims (1)

(57) [Claims 1] An ultrasonic pulse is transmitted from an ultrasonic vibrator, and a reflected wave from an object is received by the ultrasonic vibrator or another ultrasonic vibrator. In the ultrasonic detector that detects the presence or absence of an object, a transmitting unit that drives the ultrasonic transducer to transmit the ultrasonic pulse, and supplies power for transmitting the ultrasonic pulse to the transmitting unit And a power supply unit with variable supply power and a pulse reflected from an object received by the ultrasonic vibrator.
Conversion means for converting the input signal into an output signal, and output from the conversion means.
Perform the calculation based on the pulse signal corresponding to the reflected wave
Determine the presence of the object and the distance to the object, and send
No abnormalities in the time width of the reverberation signal due to waves
Abnormality in ultrasonic transducer by comparing with time width at
And an arithmetic control unit that detects whether or not
When detecting whether an abnormality has occurred in the ultrasonic transducer
The arithmetic and control unit controls the power supply unit to reduce the power supplied to the transmission unit.
An ultrasonic detector characterized by being smaller than a normal detection state .