JPS6122279A - Apparatus for detecting obstacle behind car - Google Patents

Abstract

PURPOSE:To make it possible to certainly transmit signals by eliminating the possibility of contact inferiority, by mechanically performing the transmission of the exciting signal and the receiving signal between a transmitter-receiver and a car body in a non-contact state by coils provided in opposed relationship. CONSTITUTION:An ultrasonic transmitter-receiver 1 is rotated by a motor 2 and the rotary angle thereof is detected by an angle detector 5. A high frequency exciting signal is outputted to the transmitter-receiver 1 at every predetermined rotary angle of the transmitter-receiver 1 by a sonar circuit 4 and the high frequency receiving signal from the transmitter-receiver 1 is inputted and the distance up to an obstacle is measured from the time difference of both signals. Herein, the exciting signal outputted from the sonar circuit 4 is inputted to the transmitter-receiver 1 through the first coil 31 provided to the input/output terminal of the transmitter-receier 1 and the second coil 32 provided so as to be opposed to a car body and the receiving signal is also similarly inputted to the sonar circuit 4 through the coils 31, 32. By this method, the transmission of the exciting signal and the receiving signal can be mechanically performed in a non- contact manner.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an obstacle detection device that detects the distance to an obstacle behind a vehicle, and particularly to a detection device that detects the approach distance to an obstacle from the reflection time of ultrasonic waves. It is related to the device.

[Conventional technology]

The above obstacle detection device is equipped with a transducer for receiving and transmitting ultrasonic waves on a rear bumper, etc., and is more compact and cheaper than using a television camera, etc. ii￥It has the excellent features of being able to be used in the snow and at night, and also being easy to maintain.

By the way, a detection device has been proposed that can detect obstacles in the entire area behind the vehicle using a single ultrasonic transducer (
(Japanese Patent Application No. 57-201757), according to which the device is much more compact and inexpensive1,1.In other words, in the obstacle detection device, a 371-sound wave Ifi receiver is installed at the rear of the vehicle. If it is rotatably provided, it is rotated by a driving means so that it transmits ultrasonic waves and receives reflected waves from obstacles at every predetermined rotation angle behind the vehicle.

[Problem that the invention seeks to solve]

A high-frequency excitation signal is supplied from the vehicle body to the rotating transducer to transmit ultrasonic waves, and a high-frequency reception signal is output from the transducer to the vehicle body when a foul wave is received. . The transmission of these excitation and reception signals has conventionally been carried out mechanically, such as by bringing a brush into contact with a slip ring installed on the rotating shaft of the transducer.However, With this method, signals may not be transmitted properly due to poor contact or wear of the brushes.

[Means for solving problems]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a K II square antique object detection device that is capable of transmitting signals without using mechanical contact parts.

The structure of the present invention is shown in FIG. 1, and in FIG. 11, a C ultrasonic transducer 1 is rotationally driven by a motor 2 serving as a driving means. 1 The rotation angle of the transducer 1 is detected by the angle detection circuit 5, and the sonar circuit 4 serving as distance detection means outputs a high frequency excitation signal thereto at every predetermined rotation angle tα of the transducer 1. A high frequency reception signal from the +1i receiver 1 is input, and the distance to the obstacle is detected from the time difference between the two signals. The detected distance 111 [is displayed on the display device 7 installed in the vehicle interior via the display circuit 6.

A first coil 31 is provided at the input/output end of the rotationally driven ultrasonic transducer 1, and the first coil 31 is provided on the vehicle body.
A second coil 32 facing the coil 31 with a distance therebetween.
is provided and connected to the input and output terminals of the sonar circuit 4. Thus, the excitation signal output from the sonar circuit 4 is input to the ultrasonic transducer 1 through both of the opposing coils 31 and 32, while the received signal output therefrom is similarly input to the ultrasonic transducer 1 from both coils 31 and 32. The signal is input to the sonar circuit 4 through the lines 31 and 32.

(Embodiment) In Fig. 2, an ultrasonic transducer 1 is provided below the rear bumper A of the vehicle. It is directed toward the rear of the vehicle (to the left in the figure).An ultrasonic transducer 12 is installed at the focal point of the reflecting surface 11a to face it.
The ultrasonic wave emitted from the transducer 2 is reflected by the reflecting surface 11a and sent out substantially horizontally to the rear of the vehicle, while the horizontally incident reflected wave is similarly reflected by the reflecting surface 11a and reaches the vibrator 12. The above reflector plate 11 has that.
A rotating shaft 13 is formed protruding from the center of one end, and the rotating shaft 1
3 is pivotally supported by the bottom wall of a bousing 14 fixed to the lower surface of the rear bumper A. Further, the vibrator 12 is connected to the rotating shaft 1
It is embedded and held in a rubber mount 132 fixed to a stay 131 that protrudes from the rubber mount 132.

A spool gear 21 is fitted and fixed on the outer periphery of the rotating shaft 13 protruding into the housing 14, and this is connected to a gear 22.2.
3, and is connected to a gear 24 provided on the output shaft of the motor 2. With this structure, the ultrasonic transducer 1 is driven to rotate about the rotating shaft 13 by the motor 2.

The rotary shaft 13 extends upward through a printed board 51 disposed within the housing 14, and a first coil 31 is provided on the outer periphery of the tip of the rotary shaft 13 by winding it around a circular coil bobbin. The coil 31 is connected to the ultrasonic transducer 12.

A second coil 32 having the same shape as the first coil 31 is provided around the penetrating portion of the rotation shaft 13 on the upper surface of the printed board 51, with a space maintained therebetween. The second coil 32 is connected to a sonar circuit 4 (FIG. 1) provided on the vehicle body outside the housing 14 via a lead-out cable 52. The printed board 51 has the motor 2 running in forward and reverse directions. A drive circuit, which will be described later, is then formed.

The drive v1 circuit causes the motor 2 to rotate in the forward and reverse directions in response to activation signals from reed switches 501 and 502 provided on the lower surfaces of the pudding 1 to the plate 51. The reed switches 501 and 502 are activated when the magnets 25 provided on the top surface of the gear 21 at the left and right rotational ends of the ultrasonic transducer 1 come close to and opposite to the switches 501 and 502, respectively. In this way, the transducer 1 is reciprocated while facing toward the rear of the vehicle. Note that the transducer 1 is covered with a protective cover 15 that is open at the rear.

FIG. 3 shows an angle detection circuit 5 including a motor drive circuit 503.
shows. In the figure, 504 is a flip 70 block, 505 is a bandpass filter that also serves as an amplifier circuit, 5061 is an L comparator, 507 is a binary counter, and 508 is a 4-pitch filter.
is an up/down counter of ~.

The input terminal of the filter 505 is connected to the power supplies tfA and 1E of the motor drive circuit 503. The reed switch 501 is connected to the "S"-7 terminal of the flip 70 tube 504 and the 1ml terminal of the uptown counter 508, and the reed switch 502 is connected to the "S"-7 terminal of the flip 70 tube 504 and the 1 ml terminal of the uptown counter 508.
It is connected to the l'RJ terminal of 071.

The rQJ terminal of the flip-flop 504 is connected to the rU/DJ terminal of the up/down counter 508.

Is reed switch 501.502 working #I-4'? y
In response to this, the flip-flop 504 is set or reset, and the output signal causes the drive circuit 503 to be set or reset.
causes the motor 2 to rotate forward or reverse.

The voltage of the power supply line IE pulsates as the motor 2 rotates. This pulse 01 is shaped into a rectangular pulse by a filter 505 and a comparator 50G, and input to a binary counter 507 for frequency division. The divided pulses are counted by an uptown counter 508. The count output data 5a of the counter 508 is transmitted to the reed switch 50.
1 operation f7+ 1M is set to O, and its value increases with each rotation of 1 yota, and then decreases after lead-in 1502 is activated. That is, the above data 58 is the positive 1jl of the motor! The ultrasonic transducer 1 increases and decreases with the i rotation.
Indicates the rotation angle hemp position. The angle data 5a is displayed on the display circuit 6 (
(Figure 1). Also, the minimum pitch of the angle data 5a (
- The signal 51a is also input to the sonar circuit 4.

The configuration of the sonar circuit 4 is shown in FIG. In Figure 4, 4
01 is analog switch, 402 is preamplifier, /10
3 is a band pass filter, 404 is a variable gain amplifier, 40
5 is a detection circuit, 406 is a comparator, /107 is a flip 7
0 knob, 408 is a gate, 409 is a counter, 410.
412 is an oscillator, 4111.11 is a control circuit, and 417 is a synchronous differentiator. The oscillation frequency of the oscillator 410 and the center frequency of the passband of the bandpass filter 403 are adjusted to the frequency used by the ultrasonic transducer 12. The analog switch /I01 is switched by the output signal 411a of the control circuit 411, and sends out the high frequency excitation signal 410a output from the oscillator 410 to the second coil 32. The excitation signal 410a is transmitted to the first coil 31 disposed opposite the second coil 32, reaches the vibrator 12, and an ultrasonic wave is emitted.

When the reflected wave from an obstacle behind the vehicle reaches the vibrator 12, a high-frequency reception signal corresponding to the frequency of the reflected wave is output from the vibrator 12, and the reception signal is then transmitted from the first coil 31 to the second coil 31. The signal is transmitted to the coil 32 and amplified by the variable gain amplifier 404 to become a signal /l04a. variable gain amplifier 40
4, the magnitude of its gain is controlled by the output signal 411b of the control circuit/111. That is, the gain 1q is at a minimum while there is a lingering effect of the transmission of the vibrator 12, and thereafter the gain is increased stepwise to compensate for the attenuation of the inverse wave due to distance. The flip 70 knob 407 is the control circuit 4
The output signal 406a of the comparator 406 or the output signal Q4 of the control circuit 411 is
At 11f, 12 tsl- will be carried out.

The gate 408 outputs the output signal 4 of the flip flop 407.
During this period, the output pulse of the oscillator /112 is input to the counter /I09 (signal 408a).

The counter 409 converts the pulse signal 408a into
The distance 1111 signal is sent from the terminal 415 as a signal 409a. Further, the counter 409 is reset by the output signal 411d of the control circuit.

The control circuit/111 starts its operation by the differential signal 52a of the minimum bit signal @51a input from the angle detection circuit 5,
Each of the above signals 411a, 411b1411C, 7111(
1,411f to control the entire sonar circuit 4.

Then, when the distance measurement is completed, a measurement end signal 411e is generated from the terminal 416.

FIG. 8 shows a time chart of each of the two signals.

In the figure, (1) shows changes in the angle data 5a corresponding to the rotation angle of the transducer 1, and each number is a digital value of the angle data 5a at a predetermined rotation angle. (2) in the diagram
9) to 9) indicate the generation timing of each signal of the sonar circuit 4 in the angle section (indicated by a chain line in the figure) in which the angle data 5a has a digital value of 15.

Based on the above figure, the operation of the sonar circuit 4 will be explained below.

Upon receiving the signal q51a, the control circuit 411 switches the analog switch 401 to the oscillator 410 side and sends an excitation signal 410a to the ultra-rich wave oscillator 12.

At the same time, the flip-flop 407 is set, and its output signal 407a is set to the "1" level. At this time, the counter 40
9 is reset. Next, the analog switch 401 is switched to the preamplifier 402 side to receive the received signal, cut out the noise, and amplify it (signal 404a).

The signal 4048 is detected by the detection circuit 105 (signal 4.0
5a) When a predetermined level or higher is reached, a signal 406a is generated from the comparator 406 and the flip 70 knob 407 is reset (signal 407a). The period during which the flip 70 knob 407 is set is the time from when the ultrasonic wave is transmitted until when the reflected wave is received. During this period, the output pulse of the oscillator 412 is input to the counter 7I09 through the gate 408 ((M > -5408
8), counted. Therefore, the counter 409 outputs a distance signal 4098 that is proportional to the distance to the obstacle. When the time corresponding to the maximum distance measured by 1 has elapsed, the flip-flop 407 is reset to the control signal /111f of the control circuit 411 regardless of the presence or absence of the output signal 406a of the comparator 406, and at the same time the control circuit 41
1 emits measurement Hiiragi 7 signal @4.11e.

FIG. 5 shows the configuration of the display circuit 6. 61 in the figure is RΔMT
・Memorize the distance to the obstacle in each rotation angle plane of the ultrasonic transducer 1. 62.65 is input to pin 1 to 2
A decoder decodes into three outputs, 63 is an OR gate array, 64 is a data selector, 66 is a control circuit, 67 is a comparator, 68 is an n-ary counter, and 69 is an oscillator.

The above OR gate array 63 is constructed by two people as shown in FIG.
+1 gate 631 is connected in cascade.
The smallest bit of the output signal 62a of the driver 62 (see FIG. 5) is connected to the first stage OR gate 631, and the largest bit is connected to the last stage OR gate 631. The remaining input terminal of the first stage OR gate 631 receives the output signal 6 of the comparator 67.
7a has been input.

In FIG. 5, by appropriately selecting the value of n, the n-ary counter 68 converts the output pulses of the oscillator 69 to output an angle address signal 68a.

In this embodiment, the value of n is 16, and the value of the angle address signal 68a changes periodically from 0 to 15.

When @411e is input at the end of distance measurement, the control circuit 66
controls the data selector 64 to set the angle data 5a to RA.
Enter into M61. Next, write signal 66 to RAM 61
a and writes a distance signal 409a to the address specified by the angle data 5a. When the writing is completed, the angle address signal 68a of the n-ary counter 68 is applied to the RAM 61 via the data selector 64. The address signal 68a is activated periodically, and the distance signals 409a stored at the address specified by the signal 68a are sequentially read out (signal 618).

The decoder 62 generates an output signal 62a in which the bit corresponding to the stored distance signal 61a is at the "1" level. This signal 62a is converted into a display distance 1111 and a signal 638 by an OR gate array 63. In the display distance signal 63a, all bits higher than the bits that have the above-mentioned "1" level become the (1) level. Angle address signal 68al of the n-ary counter 68; also input to the l decoder 65, and the address signal 68a The display angle signal Q (35B) with the corresponding bit set to the "1" level is now transmitted.

=1 The comparator 67 compares the angle data 5a and the angle address signal 68a, and if the two match, outputs the output signal 07.
emits a. In the display distance signal outputted from the OR gate array 63 by the signal 67a, all the pins "." are at the "1" level. In this embodiment, the above display distance -1 signal @63a
is 10 bits, and the display angle signal 65a is 16 bits.

The 4N composition of display H position 7 is shown in figure ff16. 71.7 in the figure
3 is a driver circuit, and 72 is a display element array.

For the display, a photo chain diode, a fluorescent display tube, a liquid crystal, etc. can be used. Each element in the display element array 72 has a
The display element selected by the display distance signal 63a input from the terminal 74 and the display angle signal 65a input from the terminal 75 is turned on. That is,
A row is selected by the bit of the signal 63a that is at the "1" level, a column is selected by the bit that is the "1" level of the signal 65a, and the display element located at the intersection of the selected row and column is It will be turned on.

FIG. 9 shows a front view of the display device 7. The display device 7 is installed on a tray or the like inside the vehicle that can be seen by the driver when the vehicle is backing up. In the figure, 76 is a mark that displays the vehicle width, and the display elements of the display element array 72 are installed only within the vehicle width and near the vehicle width. It is divided into 16 equal parts, which corresponds to each pitch 1 of the display angle signal 65a.
This is 1. C1-Each pitch 1 of distance signal 63a for display display
It corresponds to.

The angle address signal 68a of the n-ary counter 68 in FIG.
are issued in sequence, the angle display signal @65a
and a distance display signal ";'r 63 R is output to the display device 7. As a result, the display element selected by the upper two signals 63a and 65a in the display element array 72 or the point *T (
(shaded area in Figure 9). In the distance 1 II 11 display signal 63a, as mentioned above, all bits higher than the bit corresponding to the distance to the obstacle are "1" label. All lights up (part 72a in the figure). Further, when the scanning angle of the ultrasonic transducer 1 and the angle address signal 68a match, the signal 67a in FIG.
Since all bits of a are at the "1" level, at this time,
All display elements selected by the angle display signal 65a light up (portion 72b in FIG. 9). In this way, the display device 7 displays the position of the obstacle in the entire area near the rear of the vehicle ζ1, and also displays the direction in which the transducer 1 is searching.

(Effects of the Invention) As described above, the obstacle detection device of the present invention is capable of detecting obstacles in the entire rear area of the vehicle using a single rotating ultrasonic transducer, and the above-mentioned transducer and the vehicle body are capable of detecting obstacles. Since the transmission of the excitation signal and reception signal between the two is carried out mechanically and completely without contact by the opposing two-wheels, there is no risk of poor contact, etc., and the above-mentioned signals can be reliably transmitted.

In the above embodiment, the number of turns of the first coil is increased by the number of turns of the second coil (by doing so, it is possible to increase the excitation voltage of the ultrasonic transducer, which increases the transmitted sound pressure and increases the number of turns of the second coil. It is possible to reduce the influence of noise.

Furthermore, in the above embodiment, the rotation angle of the ultrasonic transducer is detected based on the rotational speed of the motor based on the pulsation of the power supply line to the motor, without providing a special cornerstone detector. E'), in this respect;
b-inspection9. The I'lH location is inexpensive and non-impact.

[Brief explanation of the drawing]

An overall sectional view of the ultrasonic transducer rotatably mounted below the Yabanpa, Figure 3 is a circuit diagram of the angle detection circuit, Figure 4 is a block diagram of the sonar circuit, Figure 5 is a block diagram of the display circuit,
FIG. 6 is a block diagram of the display device, FIG. 7 is a circuit diagram of the OR gate array circuit, FIG. 8 is a waveform diagram of each signal of the sonar circuit, and FIG. 9 is a front view of the display device. 1... Ultrasonic transducer 13... Rotating shaft 2... Motor (driving means) 31... First coil 32...・Second coil 4... Sonar circuit VB (distance detection means) 5...
...Angle detection circuit (angle detection means) Fig. 2 Fig. 5 Fig. 6 Fig. 7 t)/Q Fig. 8 (9) o411e Fig. 9

Claims (2)

[Claims] (1) An ultrasonic transducer installed at the rear of the vehicle that inputs a high-frequency excitation signal to transmit ultrasonic waves, receives reflected waves from obstacles, and outputs a high-frequency received signal; A driving means for rotating and transmitting and scanning ultrasonic waves towards the rear area of the vehicle; an angle detecting means for detecting the rotation angle of the ultrasonic transducer; A rear obstacle detection device for a vehicle is equipped with a distance detection means for outputting a signal to a transducer and inputting a received signal from the transducer and detecting the distance to the obstacle from the time difference between the two signals. The ultrasonic transducer is provided with a first coil at its input and output ends, and the vehicle body is provided with a second coil that faces the first coil at a distance. It is characterized in that it is connected to the input/output end of the distance detection means, and the excitation signal and the received signal are transmitted between the ultrasonic transducer and the distance detection means via the first and second coils. Rear obstacle detection device for vehicles. (2) The ultrasonic transducer is installed on a rotating shaft that is rotatably supported by the vehicle body, and the first coil is integrally fixed around the rotating shaft, and the vehicle body supports the rotating shaft. 2. The rear obstacle detection device for a vehicle according to claim 1, further comprising: a rear obstacle detection device for a vehicle according to claim 1, wherein the second coil is provided around the second coil so as to face the first coil.