JPH0858504A - Collision alarm device - Google Patents

Abstract

PURPOSE: To enable stable detection of optical detection deteriorating material such as sticking of waterdrop even if suck material is stuck on the surface of a translucent glass cover of collision alarm device. CONSTITUTION: Because an uneven part is minutely provided on a part of the surface of a translucent glass cover 5, usually, reflection of light amount into the case through such uneven surface 5a is more than that through the existing cover. When waterdrop is stuck on the uneven surface 5a, the uneven surface 5a becomes flat, therefore the same amount of light as when the uneven surface 5a does not exist is reflected into the case. Thus the amount of light reflecting into the case changes a great deal and facilitates the detection of the waterdrops.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collision warning device for detecting an obstacle in front of a vehicle to prevent a collision accident from occurring.

[0002]

2. Description of the Related Art As a conventional collision warning device, there is one shown in FIG. 2, for example. In the figure, reference numeral 1 is a distance detection unit that detects a distance between a vehicle and a front obstacle using a laser beam (light beam) emitted from a laser diode (hereinafter referred to as LD). Contamination determination circuit 7, alarm device 8, drive signal generation circuit 11, LD switching driver 12, LD array 13, light transmitting lens 1
4, light receiving lens 15, photodiode (also referred to as PD) 16, amplifier circuit 17, threshold value generating circuit 18, comparator 19, counter 20, reference pulse generating circuit 21
It consists of Reference numeral 2 denotes a running state detection unit that detects the running state of the vehicle such as the vehicle speed.

Reference numeral 3 designates the own vehicle based on the distance information returned to the distance detection unit 1 in response to the distance detection command and the own vehicle speed information detected by the running state detection unit 2. By calculating the relative speed with the front obstacle, it is judged whether the front obstacle is a stationary object or a moving object, and the own vehicle speed, the relative speed,
A signal processing unit (signal processing means) that determines the possibility of collision between the host vehicle and a front obstacle according to the distance setting or the like set according to individual differences in free running time until the driver brakes, It is composed of an arithmetic circuit 41 composed of a microcomputer and the like, and a distance setting switch 42.

Reference numeral 4 indicates the distance between the vehicle and the front obstacle based on the information from the signal processing unit 3, and the signal processing unit 3 judges that there is a possibility of collision with the front obstacle. In the case where the signal is given, it is an alarm notifying section that generates an alarm in response to the signal, and is composed of a distance indicator 51 and an alarm 52. Reference numeral 5 denotes a translucent glass cover, which is arranged in front of the light-transmitting lens 14 and the light-receiving lens 15 and closes an opening at one end of a case (not shown) in which the circuits and the like are hermetically sealed and housed. To do. Reference numeral 6 denotes a photodiode for detecting the degree of contamination, which is a light-transmitting lens, which is arranged near the light-transmitting lens 14 and receives the reflected light C from the surface of the transparent cover 5 as shown in FIG. .

Next, the operation of the above configuration will be described. The vehicle speed signal of the own vehicle detected by the vehicle speed sensor 31 is sent to the arithmetic circuit 41. When the vehicle speed calculated based on the vehicle speed signal is 35 Km / h or more, the arithmetic circuit 41 generates the distance signal of the distance detecting unit 1. A distance detection command signal is sent to the circuit 11.

In the distance detecting section 1, the drive signal generating circuit 11 receives the distance detection command signal and the drive signal generating circuit 11 receives the signal.
Sends the LD light emission signal shown in FIG. 4A to the LD switching driver 12. The LD switching driver 12 is based on the received LD light emission signal (a), as shown in FIG.
The signals shown in (c) and (d) are transmitted, and L is used as a light emitting means.
The LD-L, LD-C, and LD-R of the D array 13 are sequentially made to emit light.

The laser beam (light beam) from the LD-L of the LD array 13 is projected to the front left of the vehicle, the laser beam from the LD-C is projected to the front, and the laser beam from the LD-R is projected to the front right. The laser beam emitted from the LD-C is emitted through the optical lens 14, and the laser beam emitted from the laser diode LD
The laser beam of L is the vehicle that interrupts from the left lane, LD
The -R laser beam is used to detect an oncoming vehicle from the right lane.

The light reflected from the front obstacle is received by the light receiving lens 15
The light is collected by and is received by the photodiode 16. This received light signal is sent to the amplifier circuit 17, which amplifies it and outputs the signal of FIG. In this signal, a reflection signal B from a front obstacle and a reflection signal A from a short distance road surface are mixed.

The threshold value generation circuit 18 is based on the LD light emission signal (a) output from the drive signal generation circuit 11 and shown in FIG.
The threshold signal shown in FIG.
Output to. The comparator 19 compares only the output signal (e) of the amplifier circuit 17 with the threshold signal (f) to extract only the reflected signal from the obstacle,
The obstacle detection pulse signal shown in FIG. 4 (g) is output.

The counter 20 starts counting the clock pulse signal supplied from the reference pulse generating circuit 21 at the rising edge of the LD light emission signal (a) as shown in FIG. The count is stopped at the rising edge of the obstacle detection pulse signal (g) based on the above, the distance information to the obstacle is obtained from the count-up time and the speed of light, and it is sent to the arithmetic circuit 41 of the signal processing unit 3.

Next, a method of determining the possibility of collision in the arithmetic circuit 41 of the signal processing unit 3 will be described with reference to the flowchart shown in FIG. First, when the power is turned on,
Proceeding to the START step, C constituting the arithmetic circuit 41
Initialization of PU, RAM, etc. is performed. Next, in step ST11, the counter 20 of the distance detection unit 1 is set at predetermined intervals.
A distance signal indicating the information on the distance R from the obstacle and a vehicle speed signal indicating the information on the own vehicle speed Vf from the vehicle speed sensor 31 of the traveling state detection unit 2 are fetched into the arithmetic circuit 41.

Then, in step ST12, the distance signal R is converted into a display signal and sent to the distance display 51 for display. Next, in step ST13, the inter-vehicle distance R is differentiated to differentiate the relative speed (d / dt) between an obstacle such as a preceding vehicle and the host vehicle.
R is calculated using a calculation method such as the least squares method, and the vehicle speed Va of the preceding vehicle is calculated from the own vehicle speed Vf and the relative speed (d / d).
t) Calculated by the sum of R.

In this calculation, (d / dt) R <0
In case of (d / dt) R> 0, the distance is decreasing, and in case of (d / dt) R> 0, the distance is increasing. In each case, there is no change in distance.

In determining the possibility of collision with an obstacle, the initial speed of the host vehicle is Vf (m / s), the initial speed of the obstacle (preceding vehicle) is Va (m / s), and both deceleration performances Is α (m / s
² ), the idling time by the time Td before the own vehicle sets the brake on the difference between the stop distance Vf ² / 2α of the own vehicle and the stop distance Va ² / 2α of the preceding vehicle is set. The distance R shown in the equation 1 which is the sum of the distances Vf and Td serves as a criterion.

[0015]

[Equation 1]

Therefore, first, in step ST14, the relative speed (d / dt) R and the vehicle speed Vf are compared, and-(d /
dt) In the case of R≈Vf, that is, when the obstacle is regarded as a road stop, the process proceeds to step ST15, and since Va = 0 in the formula 1, there is a risk of collision according to the driving law of the following formula 2. To judge.

[0017]

[Equation 2]

When the equation 2 is satisfied, there is a risk that the obstacle collides with the obstacle, and the process proceeds to the switch ST18 to generate an alarm signal to the alarm notification unit 4. The alarm 52 is sent to issue an alarm for avoiding danger.

On the other hand, as a result of the judgment in step ST14,
If-(d / dt) R≈Vf is not satisfied, the obstacle is a preceding vehicle traveling on the road ahead, and the danger judgment should be made according to the equation 1. However, the relative velocity (d / d
t) Since the calculation accuracy of R cannot be strictly obtained, the calculation error may give an erroneous alarm. Therefore, in the case of a preceding vehicle in which an obstacle moves, the relative speed (d / dt) in step ST16.
First, it is determined whether R is equal to or higher than a predetermined speed C (m / sec).

As a result, when (d / dt) R ≧ C, the relative speed is fast and the vehicle is approaching rapidly. Therefore, the preceding vehicle is regarded as infinitely close to the stopped object, and the process proceeds to step ST15. With the same logic as that of the stop obstacle, the warning output judgment is performed by the discriminant equation of Formula 2.

Further, the determination result of step ST16 is (d
/ Dt) R <C, the relative speed is slow and it is considered that the vehicle is normally following the vehicle at a constant inter-vehicle distance.
Since the preceding vehicle speed Va is almost equal, the number 1 becomes the number 3 shown below, and in step ST17, the risk of collision is determined by the number 3, and similarly when this number 3 is satisfied, an alarm is issued. .

[0022]

(Equation 3)

Most of the light beam D emitted from the light-transmitting lens 14 passes through the light-transmissive glass cover 5, but a part of it (indicated by the symbol C) transmits light as shown in FIG. Whether or not an alarm should be given by the dirt determination circuit 7 after being reflected by the outside surface of the transparent glass cover 5 toward the inside of the case and received by the photodiode 6 constituting the dirt detection sensor (the amount of light received increases in proportion to the dirt degree). If it is determined that an alarm should be issued (there is a possibility that the function may deteriorate and it may become difficult to use), the alarm device 8 is driven.

[0024]

However, in the collision alarm device having such a structure, since the surface of the translucent glass cover is formed extremely flat, the collision alarm device is in a normal use environment. The ratio of the light reflected in the case due to the dirt on the cover surface is 7
In the case of ~ 8%, when water drops adhere to the cover surface due to rain or the like, there is no big difference of 5-6%, so there is a problem that water drops, etc. cannot be detected stably and reliably (100% completely). there were.

The present invention has been made by paying attention to such a problem, and even if a substance that deteriorates in optical detection such as adhesion of water drops adheres to the surface of the translucent glass cover, it can be stably maintained. The purpose is to be able to detect.

[0026]

A collision warning circuit according to the present invention comprises a light emitting means for emitting a light beam toward the front, and a light receiving means for receiving reflected light of the light beam from the light emitting means due to a front obstacle. A distance between the light-transmitting cover arranged in front of the light-emitting means and the light-receiving means and an obstacle in front calculated from the light-receiving signal from the light-receiving means and the vehicle speed of the vehicle detected by the vehicle speed sensor. And a signal processing means for generating an alarm signal based on the relative speed, and a part of the light beam emitted from the light emitting means, which is reflected by the translucent cover, is received, and the transmitted light is transmitted based on the received light amount. The optical cover is provided with a function deterioration detecting means for detecting a function deterioration degree and an alarm means for issuing an alarm based on the detection output from the signal processing means and the function deterioration detecting means.

[0027]

In the collision warning circuit according to the present invention, since the uneven portion is finely provided on a part of the surface of the light-transmitting glass cover, the amount of light reflected inside the case by the uneven surface is always constant. A greater amount is reflected. Further, when water drops adhere to the uneven surface, the uneven surface becomes flat, so that light equivalent to that in the state where there is no uneven surface is reflected in the case. Therefore, the amount of light reflected in the case changes greatly, and it becomes easier to detect water drops.

[0028]

EXAMPLE Next, the configuration will be described with reference to FIG.
Since only the translucent glass cover 5 is different and the other parts are the same as those shown in FIG. 2, only the different parts will be described. That is, the conventional translucent glass cover 5 has a flat surface and is like ordinary transparent glass.
On the other hand, the translucent glass cover 5 shown in FIG. 1 has a part of the outer plane (plane outside the case) (the light transmitting lens 1).
4 is a part of the portion where the light beam D that has passed through 4 passes through the translucent glass cover 5, and is indicated by the symbol E in FIG.
An uneven portion 5b having an unevenness degree similar to that of ordinary frosted glass is provided.

In the normal state, the translucent glass cover 5 reflects about 20% of the light beam incident on the uneven surface 5a, and part of the light beam C is a photodiode (for detecting dirt) ( Although the light is received by the function deterioration detecting means 6), when water drops adhere to the uneven surface 5a due to rain or the like, the water drops do not enter into the concave portions of the uneven surface 5a and do not drop. As a result, the surface becomes flat and reflected. The rate is reduced to about 10%, and the reflection is much lower than usual (even compared to the conventional one).

[0030]

As described above, according to the present invention, there is an effect that the difference in reflectance between the normal time and the time when water droplets are attached in rainy weather becomes large and detection becomes easy.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view of a main part of an embodiment of the present invention.

FIG. 2 is a circuit block explanatory diagram for explaining a conventional example.

FIG. 3 is a cross-sectional explanatory view of a main part of a conventional example corresponding to the main part of the present invention.

FIG. 4 is a timing diagram showing a time relationship of signals of respective parts in the distance detection unit of FIG.

5 is a timing chart showing the flow of processing in the arithmetic circuit in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 signal detection unit 2 running state detection unit 3 signal processing unit 4 alarm notification unit 5 translucent glass cover 5a uneven surface 6 function deterioration detection unit 7 function deterioration determination circuit 8 alarm device

Claims (1)

[Claims] 1. A light emitting means for emitting a light beam toward the front, a light receiving means for receiving reflected light of the light beam from the light emitting means by an obstacle in front, and a light receiving means arranged in front of the light emitting means and the light receiving means. A signal for creating an alarm signal based on the distance between the obstacle and the front obstacle, which is calculated from the received light signal from the light receiving means and the vehicle speed of the host vehicle detected by the vehicle speed sensor. Degradation of the function of receiving a part of the light beam emitted from the light emitting means from the processing means and reflected by the translucent cover, and detecting the degree of functional deterioration of the translucent cover based on the amount of the received light. A collision warning device comprising: a detection means and an alarm means for issuing an alarm based on the detection output from the signal processing means and the function deterioration detection means.