JPH052953B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an ultrasonic object detector for a vehicle that detects an object using ultrasonic pulses.

[Background Art] This type of ultrasonic object detector transmits an ultrasonic pulse and detects the presence or absence of a reflected wave from the object and the time delay between the sending of the ultrasonic pulse and the reception of the reflected wave. It is now possible to measure the presence of an object and the distance between the sensor and the object. By the way, ultrasonic object detectors installed in vehicles are often used for the purpose of detecting nearby objects, so they receive vehicle speed pulses from other devices as control inputs according to the vehicle speed, The system transmits ultrasonic pulses only when the vehicle speed is below the set speed, performs a detection operation to receive reflected waves from objects, and displays the results to inform the driver. Furthermore, in order to prevent false alarms due to external electrical and acoustic noise, a detection display is performed to indicate the presence of an object only when the object is detected a plurality of times in succession.

However, if the object detection using the multiple continuous detection method described above is performed for the first time when the vehicle speed drops below the set speed, there will be a time delay in the detection display, and if the vehicle approaches the object, the detection display will be performed. There was a risk that the vehicle would collide with an object in front of it. For example, as shown in Fig. 3, an ultrasonic object detector for a vehicle is explained in which the vehicle speed at which the detection operation starts is V ₁ and the detection display is displayed for the first time when an object is detected three times in a row. As shown in FIG. b, the ultrasonic object detector starts the detection operation at time t ₁ when the vehicle speed becomes slower than V ₁ . Then, as shown in FIG. 3a, the detection operation of transmitting an ultrasonic pulse P from the ultrasonic object detector and receiving the reflected wave from the object is intermittently repeated a plurality of times. Note that object detection is performed using only the reflected waves received within the wave reception gate period G corresponding to the detection area. If the object is detected three times in a row by this detection operation, the detection display is performed for the first time at the end time _t2 of the third detection operation. Therefore, the starting point of the sensing operation
There will be a time delay in the detection display output by the time T _{1 between t 1} and _{the time t 2 at} which the detection display is performed.

[Object of the Invention] The present invention has been made in view of the above-mentioned points, and its purpose is to reduce the response time even when a detection display is performed for the first time after an object is detected multiple times in a row. An object of the present invention is to provide an ultrasonic object detector for a vehicle that does not cause delays.

[Disclosure of the Invention] (Structure) The present invention transmits ultrasonic pulses and receives reflected waves from an object, and detects the presence of the object only when the presence of the object is detected multiple times in succession. In a vehicle ultrasonic object detector that performs a detection operation to determine that an object exists and displays a detection display when it is determined that an object exists, the detection operation is performed when the vehicle speed is below a preset first vehicle speed, and the If it is determined that an object exists when the vehicle speed is below a preset second vehicle speed that is slower than the first vehicle speed, a detection display is performed.By setting the vehicle speed at which the detection operation is performed to be faster than the vehicle speed, the response time is This is to avoid delays.

(Example) An example of the present invention is shown in FIGS. 1 and 2.
First, the basic configuration for performing the object detection operation of this embodiment will be explained. This embodiment includes a transmitting ultrasonic transducer 1a for transmitting ultrasonic pulses and a receiving ultrasonic transducer 1b for receiving reflected waves from an object. A wave transmission control unit 2a that controls the ultrasonic pulses to be transmitted intermittently from the ultrasonic transducer 1a for use in the
A drive circuit 3 that drives the ultrasonic transducer 1a for transmitting waves based on the output, and a receiver that receives reflected waves from an object (for example, a person) 7 of the ultrasonic pulses transmitted from the ultrasonic transducer 1a. A wave receiving circuit 4 that amplifies and detects the output of the ultrasonic transducer 1b for waves, and this wave receiving circuit 4
A delay time detection section that detects the delay time from when the ultrasonic pulse is transmitted until the reflected wave from the object 7 is received based on the timing signal indicating the transmission point of the ultrasonic pulse from the output and transmission control section 2a. 2b, a memory 2d for storing the delay time detected by the delay time detection section 2b, and a storage control section 2c for controlling the memory 2d to write the delay time detected by the delay time detection section 2b. , arithmetic processing that determines whether the object 7 has been detected a predetermined number of times in succession, and calculates the distance to the object 7 from the delay time stored in the memory 2d when the object 7 has been detected a plurality of times in succession; It consists of a section 2e and an output section 5 which drives an alarm 6 such as a lamp or a buzzer using the output of the arithmetic processing circuit 2e to display a detection display. Here, drive circuit 3
The above-mentioned sections 2a to 2e except for the wave receiving circuit 4 are functional blocks operated by the microprocessor 2 through program processing. In addition,
It is also possible to configure it discretely without using the microprocessor 2. Furthermore, the wave transmission control section 2a to the arithmetic processing section 2e are sections that transmit ultrasonic pulses, receive reflected waves from the object 7, and perform detection operations through signal processing. In the following description, it will be referred to as a detection operation block 21, and the output section 5 will also be referred to as a display block 22 that performs a detection display indicating that the object 7 is present. In addition,
As mentioned above, it goes without saying that the ultrasonic transducers 1a and 1b for transmitting and receiving waves do not need to be separate.

The operation of this embodiment will be explained below. This ultrasonic object detector is configured to perform a detection operation at predetermined intermittent intervals based on a control signal output from the wave transmission control section 2a. That is, the drive circuit 3 is intermittently driven by the output of the wave transmission control section 2a, and ultrasonic pulses are intermittently transmitted from the ultrasonic transducer 1a for wave transmission. At this time, the wave transmission control section 2
A timing signal indicating the timing at which the ultrasonic pulse was transmitted is output to the delay time detection section 2b from a, and the delay time detection section 2b performs a detection operation to detect the time delay from this point until the reflected wave is received. Start. When the reflected wave from the object 7 is received by the receiving ultrasonic transducer 1b, this received signal is transmitted to the delay time detection unit 2 via the receiving circuit 4.
b, and the delay time detection unit 2b detects the delay time from the time of wave transmission to the time of wave reception. This detected delay time is stored in the memory 2 in the storage control unit 2c.
d, and is also input to the arithmetic processing section 2e. This arithmetic processing unit 2e determines whether this delay time is within the reception gate period G in which the ultrasonic object detector determines the detection area in which the object 7 should be detected, and If the object 7 is an object, it is determined that the object 7 exists. By repeating this operation multiple times, the object 7 set in the arithmetic processing unit 2e is
object 7 as many times as it should be detected and displayed.
is detected, the arithmetic processing unit 2e reads out the latest delay time stored in the memory 2d, and
Calculate the distance to object 7. Then, by driving the output circuit 5 according to this distance, the alarm 6 performs an appropriate notification operation according to the distance.
Note that the notification device 6 does not necessarily need to provide notification according to the distance.

The above has been a description of the configuration and operation of an ordinary ultrasonic object detector of multiple continuous detection type.Next, the detection operation and detection display according to vehicle speed, which are the features of this embodiment, will be explained. In this embodiment, the detection block 21 and the display block 22 are operated to start the detection operation when the vehicle speed drops below a preset vehicle speed, and to start the detection display when the vehicle speed drops below the set vehicle speed. It is something. In other words, in this embodiment, the vehicle speed is calculated from a vehicle speed pulse that corresponds to the vehicle speed input from another device, and the vehicle speed is used to determine whether the calculation result is the vehicle speed at which the detection operation is started and the vehicle speed at which the detection display is started. A calculation unit 2f, a detection operation control unit 2g that operates the detection block 21 when the vehicle speed calculation unit 2f detects that the vehicle speed has become lower than the vehicle speed at which the detection operation is started, and a detection operation control unit 2g that operates the detection block 21, and the vehicle speed calculation unit 2f. The detection display control section 2h operates the display block 22 when it is detected that the vehicle speed has become lower than the vehicle speed at which the detection display starts. In addition,
The vehicle speed at which the detection display starts is the same as the vehicle speed at which the conventional detection operation and detection display start, and the vehicle speed at which the detection operation in this embodiment is performed is set faster than the above vehicle speed.

The detection operation and detection display operation according to the vehicle speed will be explained with reference to FIG. Suppose that a vehicle that was traveling at high speed applies the brakes and the vehicle speed drops below V ₂ at which the detection operation begins. This vehicle speed is detected by the vehicle speed calculation section 2f, and the detection operation control section 2
At g, the detection operation block 21 starts operating, and the above-mentioned continuous detection operation is performed multiple times. and,
The vehicle speed further decreases and the vehicle speed at which the detection display starts
When the vehicle speed becomes lower than _V1 , the vehicle speed calculation section 2f detects that the vehicle speed has reached the point at which the detection display starts, and the detection display control section 2h puts the detection display block 22 into a state of accepting the output of the detection operation block 21. In other words, as shown in Figure 2, it is assumed that the object 7 is detected twice in a row from time t ₀ when the detection operation starts to time t ₁ when the detection display starts, and then the detection display starts. Third object 7 after time t ₁
If detection is made, the alarm 6 is activated by the output of the third detection operation block 21. In other words, if the detection operation is performed from time t ₁ when the vehicle speed reaches the slower speed as in the past, the object 7 is only detected to exist when the presence of the object 7 is detected three times in a row. is notified by the alarm 6, it is necessary to perform the detection operation at least three times from the time t ₁ , which results in a time delay. In contrast, in this embodiment, the detection operation is already performed at the time t ₀ . Since the operation has been started, there is no delay in issuing the alarm from the alarm 6. It is also possible that the object 7 has already been detected three times between time t ₀ and time t ₁ , but in this case, the alarm 6 will immediately issue an alarm at time t ₁ when the detection display starts. .

[Effects of the Invention] As described above, the present invention performs the detection operation when the vehicle speed is lower than the first preset speed, and
If it is determined that an object exists when the vehicle speed is below a preset second vehicle speed, which is slower than the second vehicle speed, a detection display is performed. By setting the speed to be faster, the detection display will not be displayed for the first time when the presence of an object is detected multiple times in a row after the detection display starts, such as when the detection operation starts at the same time as the detection display starts. If the presence of the object is detected by the time this detection display starts, the detection display can be displayed immediately, and there is no delay in response time, and the presence of the object is detected. This has the effect of preventing the danger of being told that the vehicle has already collided with an object when the display is performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the circuit configuration of an embodiment of the present invention, FIG. 2 is an explanatory diagram of the same operation, and FIG. 3 is an explanatory diagram of the operation of a conventional example. 2f is a vehicle speed calculation section, 2g is a detection operation control section, 2
h is a detection display control unit, 21 is a detection operation block,
22 is a display block.

Claims (1)

[Claims] 1 Transmits ultrasonic pulses and receives reflected waves from objects, performs a detection operation that determines that an object exists only when the presence of an object is detected multiple times in a row, and detects the presence of an object. In a vehicle ultrasonic object detector that performs a detection display when it is determined that 2. An ultrasonic object detector for a vehicle, characterized in that if it is determined that an object exists when the vehicle speed is below 2, a detection display is performed.