JPH0555824B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle obstacle detection device particularly suitable for detecting obstacles behind a vehicle.

[Prior Art] When backing up in a car or the like, it is necessary to detect obstacles behind the vehicle in advance to ensure safety.
At this time, it would be convenient if obstacles could be detected automatically, and optical detection devices are conventionally known as this type of detection device. For example, a light-emitting part and a light-receiving part are installed at the rear of a car, the light-receiving part emits modulated light for detection, and the light-receiving part receives the reflected light when this modulated light hits an obstacle. It is designed to detect objects.

[Problem that the invention seeks to solve]

However, in conventional vehicle obstacle detection devices, the light receiving unit only detects the reflected light that is reflected back from the modulated light when it hits the obstacle, so it is difficult to accurately detect the position of the obstacle. However, there was a problem that obstacles could not be reliably detected.

The present invention was made in view of these problems, and an object of the present invention is to provide an obstacle detection device for a vehicle that can accurately detect the position of an obstacle and can reliably detect the obstacle. It is said that

[Means for solving problems]

The vehicle obstacle detection device of this invention has stop,
A plurality of light emitting elements arranged in a planar manner as a light source of a tail lamp, an output drive circuit that causes these light emitting elements to emit modulated light of a specific frequency for a sufficiently short period of time compared to the period at regular intervals, and a plurality of light emitting elements arranged in a line with spaces between them and receiving reflected light when the modulated light is reflected by an obstacle;
A tuning circuit provided for each of these light emitting elements and extracting the signal of the constant period from the output of the light emitting element, a latch circuit that turns the extracted signal on and off sequentially for each light emitting element in synchronization with the constant period, and the latch circuit. an A/D converter that converts the signal controlled by the circuit into a digital signal according to its level;
The digital signal output from the A/D converter is temporarily stored as the level of the light reception signal from each light emitting element, the levels are compared, and the light emitting element that outputs the signal with the highest level is installed. and an arithmetic circuit that determines the area corresponding to the obstacle as the position of the obstacle.

[Effect]

In the vehicle obstacle detection device of this invention,
The modulation reflected by the obstacle is incident on the light receiving element, a modulation signal is extracted from the output of the light receiving element in synchronization with the modulation period, and the position of the obstacle is calculated from the level of this signal.

〔Example〕

FIG. 1 is a block diagram showing the circuit configuration of a vehicle obstacle detection device according to the present invention. In the figure, 1 and 2 are oscillators with oscillation frequencies f ₀ and f ₁ respectively, Q ₁ and Q ₂ are AND circuits and XOR circuits,
AND circuit Q ₁ receives the outputs of oscillators 1 and 2,
The output of the AND circuit _Q1 and the signal from the writing switch 3 are input to the XOR circuit _Q2 . 4 is
LED (light emitting diode) 5 which is a plurality of light emitting elements arranged in a planar manner based on the output of the XOR circuit Q ₂
6a, 6b, 6c are light emitting elements that receive the reflected light when the modulated light is reflected by an obstacle (not shown); 7a, 7b, 7c are each Light receiving element 6a, 6
Tuned amplifiers 14a, 14b, 14 which extract and amplify the above-mentioned constant period signals from the outputs of outputs 14b and 6c;
c is a detection circuit for rectifying and smoothing the signal;
15a, 15b, 15c are peak hold circuits for holding the peak level of the detected signal;
8a, 8b, 8c convert the retained signals into A/D
An A/D converter that converts (analog/digital) and inputs it to the arithmetic circuit (microcomputer) 9;
Reference numeral 10 indicates that the signals extracted by the tuned amplifiers 7a, 7b, and 7c are sequentially transmitted to each light receiving element in synchronization with the above-mentioned constant period.
It is a latch circuit that turns ON/OFF.

The light receiving elements 6a, 6b, 6 detected in this way
The signals from c are sent to tuned amplifiers 7a and 7, respectively.
b, 7c take out and amplify the above-mentioned fixed period signal, and after detection by the detection circuits 14a, 14b, 14c, the latch circuit 10 sequentially outputs the peak hold circuits 15a, 15 at each fixed period.
b, 15c, the peak level is held, and the held signals are respectively input to A/D converters 8a, 8b, 8c, converted to digital signals, and further input to the arithmetic circuit 9. stored in memory. The arithmetic circuit 9 compares these three data according to the program, and
The difference between the three data is compared with a preset internal value, and if it is less than that value, it is determined that there is no obstacle, and if it is greater than that value, it is determined that there is an obstacle. to decide. When it is determined that there is an obstacle, the position where the light receiving element corresponding to the A/D converter that outputs the largest value is installed corresponds to the position where the obstacle exists, so the arithmetic circuit 9 compares the three data and calculates where the obstacle is present. 11 is an alarm display circuit that displays an alarm when an obstacle is output. In addition, in the figure, three light receiving elements 6a, 6
Although only b and 6c are shown, a large number of these light receiving elements are arranged, and a large number of LEDs 5 are also arranged.

FIG. 2 is an external view of a rear combination lamp for an automobile, which is equipped with a light-emitting section and a light-receiving section having the above-mentioned LED and light-receiving elements 6a to 6c. LED5 forms the stop light and tail light 12.
It is also used as an LED. Also, Figure 3 a, b
1 shows an example of the arrangement of the LED 5 and the light receiving elements 6a to 6c, in which a large number of the LEDs 5 are arranged in a plane, and the light receiving elements 6a to 6c are arranged linearly at regular intervals. Then, the light receiving elements 6a to 6c
A light shielding plate 13 is provided between the two so that the modulated light of the LED 5 does not enter directly.

Next, the operation will be explained using the timing chart shown in FIG. FIG. 4 shows the waveforms of the modulated light from the LED 5 and the signals input to the arithmetic circuit 9 from each of the light receiving elements 6a to 6c.

As mentioned above, oscillators 1 and 2 have f ₀ and
The oscillation frequency is f ₁ , and the oscillator 2 has a period T
(T=T ₁ +T ₂ ), and oscillates at a duty ratio of T ₁ /T. These two oscillation signals are mixed by an AND circuit _Q1 and input to one terminal of an XOR circuit _Q2 .
A signal from the mode switching writing switch 3 is input to the other terminal of the XOR circuit _Q2 .
Then, the output signal of the XOR circuit _Q2 is input to the output drive circuit 4, which causes the output drive circuit 4 to stop and cause the LED 5 of the tail lamp 12 to blink. In other words, LED 5 transmits the signal of carrier frequency f ₀ to T ₁ ,
It blinks with a signal modulated by a continuous pulse signal with a width of T ₂ , and emits a modulated light toward the rear of the vehicle for detecting obstacles. At this time, the lighting switch 3 switches the mode between daytime and nighttime.
The blinking status of LED5 changes. That is, in the daytime, as shown in Figure 4a, the emission time of the modulated light is
Keep T ₁ sufficiently shorter than the OFF time T ₂ (T ₁
<< T ₂ ), so that the lighting of the LED 5 is not perceivable to the naked eye, and in the case of nighttime, as shown in Figure 4 b, the operation of the modulated light emission time T ₁ remains unchanged, and the operation of a. By setting the OFF (lights out) time T ₂ to ON (lights on), the stop and the decrease in the brightness of the tail lamp 12 are not recognized.

On the other hand, each of the light receiving elements 6a to 6c is sequentially turned on in synchronization with a signal having a period T, and this ON time _T3 is appropriately set within the range of the period T ( _T3 ≦T).
If there is an obstacle behind the car, the LED
When the modulated light from 5 hits this obstacle, it is diffusely reflected,
The reflected light enters each light receiving element 6a to 6c.
Each of the light receiving elements 6a to 6c converts the incident light into an electrical signal, and the tuned amplifiers 7a to 7c amplify only the signal with the same frequency f ₀ as the light emission signal of the LED 5 from among the electrical signals, and the detection circuit 14a ~14c detects the wave and converts it into a DC level signal. At this time, the latch circuit 10 sequentially outputs the outputs of the detection circuits 14a to 14c in synchronization with the signal (period T) of the oscillator 2.
The above DC level signal (light level signal) is turned ON/OFF and controlled by this latch circuit 10.
The peak levels are held by peak hold circuits 15a to 15c, and converted into digital signals according to the levels by A/D converters 8a to 8c,
The signals are input to the arithmetic circuit 9 from each port.

The arithmetic circuit 9 receives digital signals input from the A/D converters 8a to 8c, that is, each of the light receiving elements 6a to 8c.
From the level of the reflected light incident on 6c, the presence, distance, and position (direction) of an obstacle that is a reflecting object is calculated, and a sound warning is issued to the driver, and the position, distance, etc. are displayed on the display board of the display circuit 11. Display.
At this time, the position of the obstacle can be detected more accurately by comparing the levels of the respective light reception signals and identifying the light receiving element that outputs the light reception signal with the highest level.

In the above embodiment, since the light source (LED 5) of the stop and tail lamp 12 is a light emitting element, the installation space is small and a large amount of light can be obtained at low cost. Furthermore, since all the LEDs 5 can be driven with the same signal, the output drive circuit 4 can have a simple circuit configuration.

Furthermore, as shown in Fig. 5, the R (right) side and the L side
The rear combination lamp on the (left) side is
They may be driven by the same control circuit 14 using, etc. Furthermore, since the amount of light received may differ somewhat depending on the position of the light receiving elements 6a to 6c, it is desirable that the arithmetic circuit 9 corrects each element and calculates the position of the obstacle.

〔Effect of the invention〕

As explained above, according to the present invention, a modulated signal is extracted from the output of the light receiving element on which the reflected light from the obstacle is incident, in synchronization with the period of the original signal, and the level of the modulated signal is determined based on the level of the signal. Since the calculation is performed, the position of the obstacle can be detected accurately and the obstacle can be detected reliably.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is an outline drawing of a rear combination lamp equipped with the LED and light receiving element shown in Fig. 1, and Fig. 3 a and b are diagrams of the LED and light receiving element. A configuration diagram showing an example of the arrangement,
4a and 4b are time charts showing the operation of the circuit shown in FIG. 1, and FIG. 5 is an explanatory diagram showing an example in which left and right rear combination lamps are driven by the same control circuit. 1, 2...Oscillator, 4...Output drive circuit, 5...
...LED (light emitting diode), 6a, 6b, 6c...
...Photodetector, 7a, 7b, 7c...Tuning amplifier,
9... Arithmetic circuit, 10... Latch circuit, 11...
Alarm display circuit, 12...stop, tail lamp, 13...shading plate, 14a, 14b, 14c...
...Detection circuit, 15a, 15b, 15c...Peak hold circuit.

Claims (1)

[Claims] 1. A plurality of light emitting elements arranged in a planar manner as a light source for a stop lamp and a tail lamp, and an output drive circuit that causes the light emitting elements to emit modulated light of a specific frequency at a fixed period for a sufficiently short time compared to the period. , a plurality of light emitting elements arranged in a line at regular intervals to receive reflected light when the modulated light is reflected by an obstacle; A tuning circuit that extracts the signal, a latch circuit that sequentially turns the extracted signal ON/OFF for each light emitting element in synchronization with the above-mentioned fixed period, and converts the signal controlled by the latch circuit into a digital signal according to its level. The A/D converter and the digital signal output from the A/D converter were temporarily stored as the level of the light reception signal from each light emitting element, and the levels were compared and the signal with the highest level was output. An obstacle detection device for a vehicle, comprising an arithmetic circuit that determines an area corresponding to a position where a light emitting element is arranged as an obstacle position.