JP2803857B2 - Ultrasonic detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic detector that transmits an ultrasonic pulse, receives a reflected wave from an object, and detects the object, and in particular, receives an ultrasonic wave. The present invention relates to an ultrasonic detector that determines the magnitude of a signal.

[Conventional technology]

Conventionally, there is known an ultrasonic detector that detects an object in the detection area by transmitting and receiving an ultrasonic pulse to and from the detection area to improve the object detection performance by providing a hysteresis to the detection area. ing.

FIG. 11 and FIG. 12 are circuit diagrams of a received signal detection portion of a conventional ultrasonic detector.

In FIG. 11, the received signal is guided to detection circuits 111 and 112,
Here dividing resistors 113, 114 different levels of the threshold value V outputted from _TH10, V _TH20 are compared respectively (<V _TH10). That is, in the detection circuit 111, received signal threshold V _TH10 more levels are extracted, whereas, in the detection circuit 112, received signal threshold V _TH20 more levels are extracted. Once the received signal is detected, the microcomputer 115
Is switched from the detection circuit 111 to the detection circuit 112 to detect an object.

Further, in FIG. 12, the received signal is guided to the detection circuit 121, where the threshold value V _TH30 output from the voltage _dividing resistor section 122 is output.
And a received signal having a level _{equal to} or higher than the threshold value V _TH30 is extracted. Then, once the received signal is detected,
The microcomputer 123 outputs an instruction signal for lowering the threshold level to the threshold variable circuit 124 so as to detect even a low-level received signal.

Further, in the ultrasonic detector that changes the detection area in accordance with the distance by using the method of changing the threshold value, a method of changing the threshold value has been used.

[Problems to be solved by the invention]

The above signal detection is performed by changing the threshold value. Therefore, a plurality of voltage dividing resistor units that generate this threshold value, and means for switching or changing the threshold value of the detection circuit each time when judging the magnitude of the received signal or changing the detection area are required. Was needed.

The present invention has been made in view of the above, and even if the transmitted ultrasonic pulses have the same pulse width, the directivity angle in transmitted waves, the signal width of the reflected wave differs depending on the distance. It is an object of the present invention to provide an ultrasonic detector that determines the presence or absence of an object based on the signal width of a received signal within a predetermined detection area.

(Means for Solving the Problems) The present invention relates to an ultrasonic detector that transmits an ultrasonic pulse having a predetermined directivity angle and detects the presence or absence of an object by receiving a reflected wave from the object. Means for detecting the signal width of the received signal, and first and second first and second detection areas corresponding to the first and second detection areas divided according to the ultrasonic reflection level at the object.
Signal width setting means for setting the set width of the second and the second set width;
Comparing means for comparing a signal width of the received signal with a set width in a corresponding detection area among the first set width and the second set width; and, based on the comparison result, the presence or absence of an object in the corresponding detection area. And a determination unit for determining the

(Operation) According to the present invention, the transmitted ultrasonic pulse is reflected by an object or the like, and the received and received wave signal is:
When the signal is from the first detection area, it is compared with the corresponding first set width, and when the signal is from the rear in the second detection, it is compared with the corresponding second set width. . Then, as a result of the comparison, if the signal width of the received signal is longer than the corresponding set width, it is determined that there is an object in the detection area, and if the signal width of the received signal is shorter than the corresponding set width, the detection area is determined. It is determined that there is no object.

〔Example〕

FIG. 1 is a circuit diagram showing a first embodiment according to the present invention.

In the figure, 1 is a microcomputer (hereinafter referred to as a microcomputer), 2 is a receiving amplifier circuit for amplifying a predetermined frequency signal output from the microcomputer 1, and 3 is a receiving amplifier circuit 2.
The ultrasonic transmitter is excited by an amplified signal having a predetermined width from the transmitter. The microcomputer 1 is configured to output the frequency signal having the predetermined width periodically or in response to an operation of an operator. The ultrasonic transmitter 3 transmits an ultrasonic pulse to a desired directivity range via an ultrasonic horn (not shown) when energized.

Reference numeral 4 denotes an ultrasonic wave receiver for receiving an ultrasonic wave transmitted from the ultrasonic wave transmitter 3 and reflecting a reflected wave reflected from an object. The directional range of the ultrasonic detector is set by the directional characteristics of the ultrasonic transmitter 3 and the ultrasonic receiver 4.
Reference numeral 5 denotes a reception amplification circuit that amplifies a reception signal received by the ultrasonic receiver 4.

As will be described later, the microcomputer 1 forms the reception gate, detects (measures) the signal width of the reception signal, compares the signal width of the reception signal with a predetermined width, and determines the magnitude of the reception signal. Execute the process.

Next, the operation will be described with reference to the timing chart of FIG.

First, an ultrasonic pulse A having a predetermined width is transmitted from the ultrasonic transmitter 3.
₁ (FIG. 2, a) is transmitted. The reflected wave from the object accompanying this transmission is received by the ultrasonic wave receiver 4 and amplified by the reception amplification circuit 5 (FIG. 2, c). The amplified received signal c is taken into the microcomputer 1. The microcomputer 1 generates a reception gate B _G in the distance direction by a predetermined distance range using a distance signal from the distance counter which is reset every transmit, the reception gate B _G from the received signals c taken in extracting the received signals C ₁ present. Furthermore, the microcomputer 1 during the life of the received signals C _1, for example, to measure the signal width of the received signals C ₁ such as by counting the distances clock. Then compared with a preset width and the signal width of the measured received signals C ₁ in order to determine whether as a detection target.

Now, assuming that the predetermined width is t _A and the signal width of the received signal C ₁ is t ₁ , if t _A <t _1, a large received signal to be detected is detected. If so, a notification to that effect is given by display, sound or buzzer.

Next, an ultrasonic pulse A ₂ is transmitting, similarly range gates
If the received signal C ₂ obtained in B _G, together with the microcomputer 1 as before, to measure the signal width t ₂ of the received signal C _2,
Compared with a preset width t _A. If t ₂ <t _A , it is determined that the signal is a small received signal that is not to be detected, and no notification is made by display or the like.

The microcomputer 1 is the predetermined width t _A has been to be able to set appropriately changed to the desired width, appropriately changing the size of the object to be detected by changing the width t _A I can do it.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention, and FIG. 4 is a timing chart.

Note that the components denoted by the same reference numerals as those in FIG. 1 indicate the same components.

In the second embodiment, a signal width equal to or more than a predetermined level in a received signal is measured instead of a method of measuring the entire width of the received signal in the existing period. That is,
A predetermined threshold value V _TH1 is set, and a received signal having the threshold value V _TH1 or more is extracted.

The detection circuit 6 sends out an output and extracts a signal while the level of the received signal from the receiving amplification circuit 5 is equal to or higher than the threshold value V _TH1 . FIG. 4 is a timing chart for explaining the operation of the detection circuit 6, and the received signals A ₁ and A ₂ show outputs from the received amplifier circuit 5. Signal width of the received signals A ₁ is t _11, the signal width of the received signal A ₂ is t _21. Then, the microcomputer 5 captures the extracted signal from the detection circuit 6 and
As in the embodiment, the distance t is used to extract the width t of the extracted signal.
_11, sequentially to measure the t _21. The measurement result is compared with a predetermined width t _A, the magnitude is determined.

In this embodiment, the influence of the rising and falling portions of the received signal can be effectively removed.

FIG. 5 is a diagram for explaining a third embodiment of the present invention, by changing the set width t _A, in which a hysteresis in the detection area.

The circuit configuration for achieving the third embodiment is the same as the first embodiment.
Both FIG. 3 and FIG. 3 can be used. Here, for convenience of explanation, description will be made using the circuit diagram of FIG. In this embodiment, instead of the ultrasonic wave transmitter 3 and the ultrasonic wave receiver 4, an ultrasonic wave transmitter / receiver 7 which is used for both transmitting and receiving is used. Further, the microcomputer 5 can perform the above-described processing and calculation,
It is adapted to perform a process of changing the setting width t _A under conditions in as described below.

In FIG. 5, reference numeral 8 denotes a horn mounted on the front surface of the ultrasonic transducer 7, and a desired directional characteristic (wider than a detection area II described later) is obtained by the horn 8. The level of the received signal reflected and received by the object is higher as the object is closer to the ultrasonic wave transmitter / receiver 7 and higher in the direction toward the transmission center. Detection area I represents the object detection range when the setting width is t _A1, detection area II (containing the detection area I) show detection range of the object when the setting width is t _A2 (<t _A1). The area III indicates the area outside the detection range. Also, P
₁ shows an arbitrary position in the detection area I, P ₂ denotes an arbitrary position in the detection area II.

In such a configuration, the operation will be described with reference to the timing chart of FIG. 6 and the flowchart of FIG.

The setting width t _A of the microcomputer 1 is assumed to have set to t _A1 as the initial state.

Under such conditions, first, in step S _1, via the horn 8 ultrasonic pulses A ₁ (FIG. 6, a) when is transmitting, the detection area I, the reflected wave from II is reception (Step
S _2). The reception signal B ₁ (b _{1 in} FIG. 6) is amplified by the reception amplification circuit 5, and the next stage detection circuit 6 extracts a signal in a period _{equal to} or longer than the threshold value V _{TH1, and then} takes in the microcomputer 1. It is. The microcomputer 1 measures a period during which the received signal is extracted, that is, a signal width. The signal width t ₁ of the received signals B ₁ obtained by such measurement and the set width t _A1 are compared (Step S
₃ ). At this time, if t ₁ <t _A1 (NO in step S _3),
As the object of the detection target in the detection area I and the detection area II is absent, the notification is not performed by such as a display (Step S _4). In this case, the process returns to step S _1, performs the same transmitting in a predetermined cycle, or in response to an instruction of the operator. On the other hand, if t _A1 <t ₁ (YE at Step S ₃
S), it is determined that an object has appeared in the detection area I, and notification by display or the like is performed. (Step S _5).

An object is once detected in the detection area I (step S ₃
After that, an ultrasonic pulse is transmitted (step S).
₆ ) When the reflected wave from the object is received (step
S ₇ ), the reception signal B ₂ (FIG. 6, b ₂ ) is amplified by the reception amplification circuit 5, and after the next stage detection circuit 6 extracts the signal in the period of the threshold V _TH1 or more, It is taken into the microcomputer 1. The microcomputer 1 measures a period during which the received signal is extracted, that is, a signal width. At this time, the microcomputer 1 changes the set width from t _A1 to t.
Change to _A2 (<t _A1 ). That is, once an object in the detection area I in the step S ₃ is detected, the microcomputer 1 is to cause hysteresis in the detection area, to extend the detection area from I to II. Then, the has changed signal width t ₂ Toko obtained received signals B ₂ by the measuring and setting width t _A2 are compared (Step S _8). At this time, if t ₂ <t _A2 (NO in step S _8), the detection area I, the II determines the object to be detected object is no longer present, notification is not carried out by such as a display (step S _9). Alternatively, if an object is detected in the previous detection operation and the display or the like is maintained, the display or the like is stopped. Then, the process returns to step S _1, performs the same transmitting. On the other hand, t _A2 <t
If ₂ (YES in step S _8), the detection area I, the II determines that the object is present, the notification by the display or the like is performed (step S _10). If an object is detected by the previous detection operation and a display or the like is maintained, the display or the like is continuously maintained. In this case, step
Returns to S _6, performs the transmitting of the ultrasonic pulse. When the received signal is obtained by the transmitting, a signal width of the received signal and the set width t _A2 are compared. Thus, received signal is once detected, set width is changed to t _A2, moreover while the object is continuously detected in this state setting width as the comparison reference is held at t _A2. On the other hand, when the object in the detection area II is not detected (NO in step S _8), set width is t _A2
From t _A1 .

Thus, in the third embodiment, widening modification of the detection area, that is, by a hysteresis in the detection area, near the boundary of the detection area I, for example, the position P ₁ position
No flickering objects in and out of the detection area I between P _2, ensure reception can be detected. Also, (YES in step S ₃₎ movement information that the object has moved from the detection area II to the detection area I also can be obtained. However. Furthermore, the detection area I, the range of II is by appropriately adjusting change width t _A set in the microcomputer 1, it is possible to set a desired detection area.

FIG. 8 is a view for explaining a fourth embodiment of the present invention, in which a plurality of detection areas are provided in the distance direction.

The circuit configuration for achieving the fourth embodiment is the same as the first embodiment.
Both FIG. 3 and FIG. 3 can be used. Here, for convenience of explanation, description will be made using the circuit diagram of FIG.

The microcomputer 1 is the process, in addition to the operation, over ultrasound after transmitting time (per detection area) performs processing for changing the setting width t _A.

In the drawings, reference numeral 9 denotes an ultrasonic transducer mounted at an appropriate position in a corner of the automobile 10, for example. The ultrasonic transducer 9 is composed of a transducer 7 and a horn 8 shown in FIG.
It consists of. Ultrasonic detector consisting of such a configuration, reception gate T _G as shown in FIG. 9 b is set, this range corresponds to the solid line H _G of Figure 8.

The inside receiving wave gate range H _G are set three detection areas. That is, the detection area H ₁ from minute time course excluding the effect of reverberation immediately after transmitting to the T ₁ time, after the T ₁ time elapses after detection area H ₂ and the T ₂ time elapsed until T ₂ time, T ₃ is a detection area H ₃ up to the point. Further, the microcomputer 1 sequentially switches and changes the set width in accordance with the elapsed time from the time of transmission, that is, for each detection area. Set the width t _A1 is in the detection area H _1, detection area H ₂
Set the width t _A2 in the inner sets width t _A3 is in the detection area H _3. Each width is set to, for example, _{t A3 <t A2 <t A1} .

In FIG. 9, signals c ₁ , c ₂ and c ₃ are timing charts for explaining the relationship between the detection area and the signal width of the reception signal, and C ₁ indicates the reception signal received in the detection area H _1. Show. Signal width t ₁ of the received signal is, if t _A1 <t _1, it is determined that the object. C ₂ represents a received signals received by the detection area H _2. Signal width t ₂ of the received signal is, if t _A2 <t _2, it is determined that the object. Also, C ₃ denotes a received signals received by the detection area H _3. The signal width t _{3 of the} received signal is t _A3 <t ₃
If so, the object is determined.

These signals c ₁ , c ₂ and c ₃ are referred to as
It is described as being included in one received signal.

Next, the operation will be described with reference to the flowchart of FIG.

First, in step S _11, ultrasound signals A ₁ (Figure 9, a)
There is transmitting, the reflected wave from the object is received wave (step S _12), is amplified by the reception amplifier circuit 5 is taken into the microcomputer 1. The microcomputer 1 measures the signal width t ₁ of the received signal C ₁ (FIG. 9, c ₁ ) received in the first receiving gate T ₁ (detection area H ₁ ), and calculates the signal width t ₁ comparing the predetermined width t _A1 (step S _13). If t _A1 <t ₁ (Y in Step S ₁₃
ES), the microcomputer 1 determines that the received signals to be detected in the detection area H ₁ exists, performs a notification by the display or the like (step S _14), and terminates the one detection operation. Then, the process returns to step S _11, performs transmit ultrasonic pulses.

On the other hand, if t ₁ <t _A1 (NO in step S _13), it is determined that the microcomputer 1 received signal to be detected in the detection area H ₁ is absent, without notification by display or the like, step
Moves to S _15. In step S _15, then reception gate
Received signal C ₂ (No. 9) received within T ₂ (detection area H ₂ )
In the figure, the signal width t ₂ of c ₂ ) is measured, and this signal width t ₂ and the predetermined width t are measured.
Comparing the _A2 (step S _15). If t _A2 <t ₂ (YES in step S _15), the microcomputer 1 determines that the received signals to be detected in the detection area H ₂ is present, perform the notification by the display or the like (step S _16), One detection operation ends. Then, the process returns to step S _11, performs transmit ultrasonic pulses.

On the other hand, if t ₂ <t _A2 (NO in step S _15), it is determined that the microcomputer 1 received signal to be detected in the detection area H ₂ does not exist, without a notification by the display or the like, step
Moves to S _17. In step S _17, received signal C ₃ is reception in the last reception gate T ₃ (detection area H ₃₎ (9
FIG measures the signal width t ₃ of the c _3), the signal width t ₃ and the predetermined width T
Comparing the _A3 (step S _15). If t _A3 <t ₃ (YES in step S _17), the microcomputer 1 determines that the received signals to be detected in the detection area H ₃ exists, performs a notification by the display or the like (step S _18), One detection operation ends. Then, the process returns to step S _11, performs transmit ultrasonic pulses.

On the other hand, if t ₃ <t _A3 (NO in step S _17), the microcomputer 1 determines that the received signals and the detection target detection area H ₁ to H ₃ is absent, perform notification by the display or the like without (step S _19), and terminates the one detection operation. Thereafter, the process returns to step S _11, performs transmit ultrasonic pulses.

According to this embodiment, by providing a plurality of setting widths, the same effect as changing the gain in the distance direction can be achieved.

In addition, by appropriately changing the setting width of each detection area,
An object of a desired size can be detected for each detection area.

〔The invention's effect〕

As described above, according to the present invention, a different set width is set for each of the plurality of detection areas, and the received signal of the object in any of the detection areas is compared with the corresponding set width. As a result, the presence or absence of an object can be accurately detected for each detection area based on the comparison result,
A highly reliable ultrasonic detector can be provided.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment according to the present invention, and FIG.
FIG. 3 is a timing chart, FIG. 3 is a circuit diagram showing a second embodiment of the present invention, FIG. 4 is a timing chart thereof, FIG. 5 is a diagram for explaining a third embodiment of the present invention, and FIG.
FIG. 7, FIG. 7 is a timing chart and a flowchart thereof, FIG. 8 is a diagram for explaining a fourth embodiment of the present invention, FIG.
FIG. 10 and FIG. 10 are timing charts and flowcharts, and FIGS. 11 and 12 are circuit diagrams of a received signal detection portion of a conventional ultrasonic detector. DESCRIPTION OF SYMBOLS 1 ... microcomputer, 2 ... transmission amplifier circuit, 3 ... ultrasonic transmitter, 4 ... ultrasonic receiver, 5 ... reception amplifier circuit, 6 ...
... Detection circuit, 7,9 ... Ultrasonic transducer, 8 ... Horn

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01S 7/52-7/66 G01S 15/00-15/96

Claims (3)

(57) [Claims] An ultrasonic detector for transmitting an ultrasonic pulse having a predetermined directivity angle and receiving a reflected wave from an object to detect the presence / absence of an object detects a signal width of a received signal. Means for performing the first and second detection areas corresponding to the first and second detection areas divided according to the ultrasonic reflection level of the object.
Signal width setting means for setting the set width of the second and the second set width;
Comparing means for comparing a signal width of the received signal with a set width in a corresponding detection area among the first set width and the second set width; and, based on the comparison result, the presence or absence of an object in the corresponding detection area. An ultrasonic detector, comprising: a determination unit configured to determine the state of the ultrasonic wave. 2. The method according to claim 1, wherein the first and second detection areas are divided into a center side and both sides of the directivity angle, and the first set width is set to be larger than the second set width. The ultrasonic detector according to claim 1, characterized in that: 3. The method according to claim 1, wherein the first and second detection areas are divided according to a lapse of time after transmission, and the first set width is set to be larger than the second set width. The ultrasonic detector according to claim 1.