JPS62231189A - Speed calculating device - Google Patents

Abstract

PURPOSE:To allow even a driver who has a little experience in driving under bad visual field conditions due to suspended matter in air to drive at a safe speed by calculating and displaying a proper speed corresponding to the concentration of the suspended matter in air. CONSTITUTION:Light emitted by a light emitting element 1 during the run of a vehicle in a foggy atmosphere strikes on fog 5 and is reflected and diffused, and then received by a light receiving lens 15, so that the light is converged on a photoelectric transducer 11. The converged light is transduced by the photoelectric transducer 11 into an electric signal, which is amplified by a signal amplifier 17 and then inputted to a peak detector 19. The output signal of the peak detector 19 is converted by an A/D converter 21 into a digital value and then inputted to a microprocess 23, which calculates and displays the maximum speed on a display device 25.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention uses a light transmitting/receiving means to detect floating objects in the air,
For example, the present invention relates to a speed calculation device that detects the concentration of fog or smog and calculates a safe running speed of a vehicle in fog or the like.

[Prior Art] In general, a device for calculating a safe speed relative to the external environment in which a vehicle is running is disclosed in Japanese Patent Application Laid-Open No. 55-1568.
As seen in Japanese Patent No. 41, there is a system that optically detects the road surface condition, determines the degree of slippage of the road surface, and calculates an appropriate speed commensurate with the degree of slippage.

[Problems to be Solved by the Invention] However, although a vehicle equipped with such a speed calculation device may be able to determine the appropriate speed depending on the road surface condition, for example, if the vehicle encounters fog and visibility is reduced, There is no particular way to calculate the appropriate speed when driving in fog, and drivers with little experience driving in fog may not know how fast to drive, and end up going too fast. There is a high risk of an accident.

In addition, for weather observation purposes, a device that detects fog, rain, snow, etc. and simply determines the presence or absence of fog, etc. was developed in 1986-17.
It is disclosed in Publication No. M42.

This invention was made by focusing on the above-mentioned conventional problems, and even if a vehicle encounters fog while driving and visibility is reduced, it is possible to calculate an appropriate running speed commensurate with the degree of fog etc. The purpose is to provide four speed calculation devices that enable safe driving.

Means for Solving the Problems In order to achieve this object, the present invention provides a light transmitting means for transmitting light in a predetermined direction, and a method for preventing the light transmitted by the light transmitting means from floating in the air. A light receiving means for receiving the reflected light, a light receiving level detecting means for detecting the light receiving level of the reflected light received by the light receiving means, and a calculating means for calculating the vehicle speed based on the light receiving level detected by the light receiving level detecting means. The configuration has the following.

[Operation] The light transmitted by the light transmitting means is reflected by hitting objects floating in the air, and the light receiving means receives this reflected light. The level of the received light is detected by the received light level detection means, and the calculation means calculates the vehicle speed based on this received light level.

[Example 1] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram of a speed calculation device, in which a light emitting element 1 consisting of a light emitting diode or Rayleigh diode, etc.
Light 7 is transmitted in a predetermined direction to fog (floating matter in the air) 5 through a light transmitting lens 3, and the light emission is made stable by a drive circuit 9 without depending on temperature etc. There is. The light transmitting lens 31, the light emitting element 1, and the drive circuit 9 constitute a light transmitting means. As for the driving method of the driving circuit 9 that generates light, it is preferable to set the output waveform to a sine wave in order to efficiently detect reflected and scattered light from the object (N 2 ) rather than a method in which the light is emitted at a constant rate. Therefore, in this embodiment, the output waveform of the light emitting element 1 is a sine wave.

A photoelectric conversion element 11 including a photodiode or the like as a light receiving element receives reflected light 13 of the transmitted light 7 by the fog 5 via a light receiving lens 15, and converts it into a sinusoidal electric signal. The light receiving lens 15 and the photoelectric conversion element 11 constitute a light receiving means.

The signal amplifier 17 amplifies the photoelectrically converted sine wave signal, and is preferably a narrow band amplifier so that only the necessary frequency signal is amplified. Detection means) input into one. The output of the peak detector 19 increases when the fog is dense because the reflected light 13 from the fog is strong, and on the other hand, when the fog is thin, the output decreases. A/D converter 21 is peak detector 1
It receives an analog output signal from 9, converts it into a digital value, and sends this signal to a microprocessor (calculating means) 23.

The relationship between the peak value of the reflected light 13 from the fog 5 and the visibility distance at that time can be determined experimentally in advance. Therefore, if the visibility distance is found from the peak value of the reflected light 13,
The distance it takes for the vehicle to stop when the brakes are applied at a given vehicle speed (1 lil + driving distance) approximately corresponds to this visibility distance, and the arbitrary vehicle speed at this time is the maximum driving speed. Of course, from the standpoint of safety, the visibility distance must be greater than +II+1 moving distance.For this reason, the microprocessor 23 stores in advance the relationship between the peak value of the reflected light 13 from the fog 5 and the maximum running speed. , Once the maximum running speed is determined, it is displayed on the display 25.

By the way, the light transmitting/receiving section of the apparatus shown in FIG. 1 needs to be devised so that it can detect reflected light from unnecessary objects other than 1':rI5 that obstruct the field of view, or to prevent it from malfunctioning due to sunlight. Therefore, in this embodiment, as shown in FIG. The optical system is set so that it crosses at a short distance (within a few meters) from ゜15 to form an effective detection area C.
It is L.

Further, the region C is located below the light receiving lens 15 with respect to the stomach in a horizontal position so that sunlight does not directly enter the light receiving lens 15. Another possible measure against scattered sunlight is to provide an optical filter in front of the photoelectric conversion element 11 so that only light of the wavelength output from the light emitting element 1 is transmitted.

A suitable mounting location for the light receiving lens 15 that satisfies these conditions is the upper part A of the windshield 29 of the vehicle 27 or the inside of the headlight B of the front grill 31, as shown in FIG. In either case, the area b' where the photoelectric conversion element 11 can condense the reflected light 13 is directed downward, and the effective detection area C does not intersect with the ground. In addition, in the case of the upper part A of the windshield, place it in a place where the wiper crosses, while in the case of the headlight B, install a new wiper in front of the moe light to keep the glass in front of the light transmitting/receiving part clean. There is a need.

In the speed calculation device having such a configuration, while the vehicle is running in fog, the light transmitted from the light emitting element 1 hits the fog 5, is reflected and scattered, and then is received by the light receiving lens 15 and focused on the photoelectric conversion element 11. . The collected light is converted into an electrical signal by a photoelectric conversion element 11, and is input to an erosion peak detector 19, where the signal is amplified by a signal amplifier 17. The output signal of the peak detector 19 is converted into a digital value by the A/D converter 21 and inputted to the microprocessor 23, where the maximum velocity is displayed on the calculated intrusion indicator 25.

The driver checks this display and reduces the speed to a speed commensurate with the visibility distance to avoid danger.

In addition to simply displaying the appropriate speed on the display 25, the following applications can be made to the above-described embodiment.

(1) If the actual traveling speed exceeds the appropriate speed, a warning will be issued.

(2) Lights such as fog lamps are automatically turned on when the actual driving speed exceeds the appropriate speed.

(3) In combination with a constant speed traveling device, when the actual traveling speed exceeds the appropriate speed, the constant speed traveling device decelerates the vehicle to the appropriate speed and runs at a constant speed.

In addition, this speed calculation device is not only installed on the vehicle, but also
It may be installed on the side of the road and used as a speed limit display device when fog occurs.

[Effects of the Invention] As described above, according to the present invention, an appropriate speed is calculated and displayed according to the concentration of suspended matter in the air, so that when visibility is reduced due to suspended matter in the air, the speed is calculated and displayed. Even drivers with little driving experience can always drive at a safe speed.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a speed calculating device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the light transmitting and receiving areas of the transmitting and receiving lens in FIG. 1, and FIG. 3 is a light receiving area in FIG. 1. FIG. 2 is an explanatory diagram showing a location where a lens is installed in a vehicle. 19...Peak detector (received light level detection means) 23.
...Microprocessor (calculating means) patent applicant Nissan Motor Co., Ltd. Figure 2 Figure 3

Claims (1)

[Claims] A light transmitting means for transmitting light in a predetermined direction, a light receiving means for receiving reflected light of the light transmitted by the light transmitting means from objects floating in the air, and a light reception level of the reflected light received by the light receiving means is detected. What is claimed is: 1. A speed calculating device comprising: a light receiving level detecting means for detecting a vehicle speed; and a calculating means for calculating a vehicle speed based on the light receiving level detected by the light receiving level detecting means.