JPH05157849A - Ultrasonic sensor - Google Patents

Abstract

PURPOSE:To automatically remove foreign material attached to an ultrasonic vibrator. CONSTITUTION:In an ultrasonic sensor for transmitting ultrasonic pulse signals intermittently by an ultrasonic vibrator 1 and receiving reflected waves from an obstruction between one transmission and the following transmission so as to detect the existence of the obstruction, there is appropriately provided exciting time T31 for applying the ultrasonic pulse signals continuously for the specified time longer than the time of transmission during the action of transmission so as to excite the ultrasonic vibrator 1. With this exciting time T31 provided appropriately during the action of intermittent transmission, ultrasonic vibrational energy to the extent of atomizing waterdrops attached to the vibrating face of the ultrasonic vibrator l is supplied, so that the waterdrops attached to the vibrating face of the ultrasonic vibrator 1 cannot stay thereon. This results in preventing the lowering of detecting performance caused by the attachement of waterdrops.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic sensor for detecting an obstacle existing in front of an ultrasonic vibrator.

[0002]

2. Description of the Related Art A conventional ultrasonic sensor is provided, for example, in a corner of an automobile to detect the presence or absence of an obstacle near the corner while staying in the driver's seat. explain. This ultrasonic sensor has an ultrasonic transducer 1, a transmission amplification circuit 2, and a reception amplification circuit 3.
And a detection circuit 4, a microcomputer 7, and a notification means 6.

The ultrasonic oscillator 1 is of an integrated transmitter / receiver type and has a oscillator main body 1a and a horn portion 1b, and receives an amplified transmitter signal A ₁ from a microcomputer 7 to generate ultrasonic waves. It transmits a pulse signal and receives a reflected wave from an obstacle.

The transmission amplifier circuit 2 amplifies the transmission signal A ₁ from the microcomputer 7. The receiving amplification circuit 3 is the ultrasonic transducer 1
The signal of the reflected wave from the obstacle received by is amplified.

The detection circuit 4 extracts a signal having a predetermined level or higher from the reception signal amplified by the reception amplification circuit 3.

The microcomputer 7 is connected to an external power source D and outputs a transmission signal A ₁ for intermittently oscillating the ultrasonic transducer 1 via a transmission amplification circuit 2 and receives a signal from the detection circuit 4. The signal is subjected to signal processing to detect the presence of an obstacle within the detection range, and a display or audio signal is output to drive a notifying means 6 described later.

The notification means 6 is a display or speaker for display, and is driven by the microcomputer 7.

[0008]

In the ultrasonic sensor as described above, as shown in FIG. 3, the ultrasonic transducer is such that the horn portion 1b at the front of the transducer body 1a is opened outward. Therefore, a concave portion is formed by the vibrating surface of the vibrator body 1a and the horn portion 1b.
As shown in (b), if water droplets adhere or the attached water droplets freeze, the ultrasonic transducer cannot transmit or receive waves. As a result, it is erroneously detected that there is no obstacle despite the obstacle in front of the ultrasonic transducer.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an ultrasonic sensor capable of automatically removing water droplets adhering to an ultrasonic vibrator.

[0010]

In order to achieve the above object, the ultrasonic sensor of the present invention intermittently transmits an ultrasonic pulse signal by an ultrasonic vibrator having a vibrator body and a horn portion. At the same time, in the ultrasonic sensor that receives the reflected wave from the obstacle between the transmission and the next transmission, and detects the presence of the obstacle within the detection range, during the operation of the transmission, The ultrasonic wave pulse signal is continuously applied for a predetermined time longer than the time, and an excitation time for exciting the vibrator main body is appropriately provided.

[0011]

According to this structure, during the operation of intermittently transmitting the wave, the excitation time is appropriately set, and the ultrasonic vibration energy to the degree that atomizes the water droplets adhering to the vibration surface of the vibrator main body is given. Therefore, even if water droplets adhere to the vibrating surface of the vibrator body, they cannot stay.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. Members that are substantially the same as those of the conventional example described above are designated by the same reference numerals.

Reference numeral 1 denotes an ultrasonic transducer, which is an integrated transmitter / receiver type, has a transducer body and a horn portion, and is an amplified transmitter signal A ₁ and excitation signal A ₃ from a microcomputer to be described later. In response to this, an ultrasonic pulse signal is transmitted and a reflected wave from an obstacle is received.

Reference numeral 2 is a transmission amplifier circuit which amplifies a transmission signal A ₁ and an excitation signal A ₃ from a microcomputer which will be described later.

Reference numeral 3 denotes a wave receiving / amplifying circuit, which amplifies a signal of a reflected wave from the obstacle received by the ultrasonic transducer 1.

Reference numeral 4 is a detection circuit, which extracts a signal of a predetermined level or higher from the received signal amplified by the reception amplification circuit 3.

Reference numeral 5 denotes a microcomputer, which transmits a transmission signal A ₁ for intermittently oscillating the ultrasonic transducer 1 via the transmission amplification circuit 2 and a predetermined period longer than the transmission time of the transducer main body during the transmission operation. It controls the excitation signal A ₃ that excites continuously for a time. Further, it is equipped with a timing means (not shown) that starts the operation in synchronization with the transmission, and the received signal from the detection circuit 4 is signal-processed by using this timing information to detect an obstacle within the detection range. The presence (presence and absence and distance) of is detected. The excitation signal A ₃ is appropriately provided during the operation of the wave transmission, and gives ultrasonic vibration energy to the vibrator body to the extent that water droplets adhering to the vibration surface of the vibrator body are atomized. Next, the operation will be described.

Reference symbol a is a waveform in which the transmission signal A ₁ amplified and applied to the ultrasonic transducer ₁ and the excitation signal A ₃ are mixed. The transmission signal A ₁ is output from the microcomputer 5 intermittently (every T ₁ hour). The excitation signal A ₃ is applied at the output timing of the transmission signal A ₁ , and the predetermined time (T ₃₁ ) in any cycle
It is output from the microcomputer 5.

B ₁ is the waveform of the received signal received by the amplified ultrasonic transducer 1 when there is an obstacle in the detection range,
A reverberation signal B ₁₁ immediately after transmission, a reflection signal B ₁₂ from an obstacle after a lapse of T ₂ time, and a reverberation signal B ₃ due to excitation are included. A signal having a predetermined level or higher is extracted from the received signal by the detection circuit 4 and output to the microcomputer 5.

C ₁ is an extraction signal from the received signal input to the microcomputer 5 when there is an obstacle within the detection range.
The extracted signal c ₁ is processed by the microcomputer 5.

B ₂ is the waveform of the received signal received by the amplified ultrasonic transducer 1 when there is no obstacle in the detection range,
Reverberation signal B ₂₁ immediately after transmission, reverberation signal B ₃ due to excitation,
It is included. A signal having a predetermined level or higher is extracted from the received signal by the detection circuit 4 and output to the microcomputer 5.

C ₂ is an extraction signal from the received signal input to the microcomputer 5 when there is no obstacle within the detection range.
The extracted signal c ₂ is processed by the microcomputer 5.

When this ultrasonic sensor is started, it is transmitted and excited with a waveform of a, and when there is an obstacle in the detection range, it has a waveform of b ₁ , and when there is no obstacle in the detection range, it has a waveform of b ₂ (reception). If there is an obstacle within the waveform detection range of the signal above the predetermined level in the detection circuit 4,
c _1, when there is no obstacle in the detection range by the signal processing of c ₂ of the waveform, detecting the presence or absence of obstacles. When the excitation signal A ₃ having the waveform of a is applied to the ultrasonic transducer 1, ultrasonic vibration energy is applied to the extent that water droplets attached to the ultrasonic transducer 1 are atomized.

The excitation signal A ₃ is applied automatically or manually after detecting an abnormality in the resonance frequency of the ultrasonic transducer 1 caused by the adhesion of foreign matter or rainfall by a rain sensor provided separately. You may do it.

[0025]

According to the ultrasonic sensor of the present invention, by the above-mentioned configuration, the excitation time is appropriately set during the operation of intermittently transmitting waves to atomize the water droplets attached to the vibrating surface of the vibrator body. Since the ultrasonic vibration energy is applied to such a degree, even if water droplets adhere to the vibration surface of the vibrator main body, they cannot stay. As a result, it is possible to prevent the detection performance from deteriorating due to the adhesion of water droplets.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, in which (a) is a circuit block diagram and (b) is a timing chart.

FIG. 2 shows a conventional example, (a) is a circuit block diagram,
(b) is a timing chart.

3A is a schematic diagram of an ultrasonic transducer, and FIG. 3B is a schematic diagram of an ultrasonic transducer with foreign matter attached.

FIG. 4 is a perspective view similarly provided in a corner of an automobile.

[Explanation of symbols]

 1 Ultrasonic transducer 2 Transmission amplification circuit 3 Reception amplification circuit 4 Detection circuit 5 Microcomputer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H04R 17/00 330 Z 7350-5H // B60R 11/00 8510-3D

Claims (1)

[Claims] 1. An ultrasonic pulse signal is intermittently transmitted by an ultrasonic oscillator having a vibrator body and a horn portion, and a reflected wave from an obstacle is received between one transmission wave and the next transmission wave. In an ultrasonic sensor for detecting the presence of an obstacle within the detection range, an ultrasonic pulse signal is continuously applied for a predetermined time longer than the time of wave transmission to excite the vibrator body during the operation of wave transmission. An ultrasonic sensor characterized in that an excitation time to be set is appropriately set.