JPH0829535A - Laser radar for vehicle - Google Patents

Abstract

PURPOSE:To obtain a laser radar being employed as means for measuring the inter-vehicle distance in the rear-end collision alarm system of vehicle in which the measuring performance can be sustained well regardless of weather conditions, e.g. snow fall. CONSTITUTION:A cover glass covering the front of light emitting part and light receiving part of a laser diode is provided with a heater means 9 and an ultrasonic oscillator 20 exciting the bending oscillation. Furthermore, the laser radar is provided with means (not shown) for measuring the extent of contamination of the cover glass, and means 5a for controlling the heater means 9 and the ultrasonic oscillator 20 to sustain the extent of contamination at a predetermined level or below based on the measurement. This constitution removes snow, frost, rain drop, dust, and the like automatically thus sustaining a good measuring performance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a laser radar device used as a means for measuring an inter-vehicle distance in a vehicle collision warning system.

[0002]

2. Description of the Related Art As a rear-end collision warning system for preventing a rear-end collision accident of a vehicle, a vehicle speed sensor and a laser radar device are provided, and a safe inter-vehicle distance is obtained from a detected value of the vehicle speed. It is known that an alarm device in a driver's cab is activated when the distance is lowered as compared with the distance.

In this case, in order to protect the light emitting portion and the light receiving portion of the laser radar from dirt, a high pressure air jet nozzle for forming an air curtain is provided in front of them. This nozzle is connected to a surge tank via an electromagnetic valve, and an electromagnetic valve opened and closed by a manual switch in the operator's cab is provided in the middle of the piping (Japanese Utility Model Laid-Open No. 2-7155).

[0004]

However, in such a conventional example, it is difficult to completely blow off snowfall or the like from the front surfaces of the light emitting portion and the light receiving portion, and if the snow or the like adhering to them is frozen without being removed, a laser beam is generated. There was a concern that the measurement performance of the radar would be significantly reduced.

Further, structurally, many additional parts such as an injection nozzle, a surge tank and an air pipe including a solenoid valve are required, and a dedicated compressor is required as a source of high pressure air, which is not only disadvantageous in terms of space and layout. However, there is a problem in that energy consumption increases when driving the compressor.

An object of the present invention is to effectively solve such a problem.

[0007]

According to a first aspect of the present invention, in a laser radar device used as a means for measuring an inter-vehicle distance in a vehicle rear-end collision warning system, a cover glass covering the front surface of a light emitting portion and a light receiving portion of the laser radar is used. A heater means for heating the is provided.

In a second aspect of the invention, the first aspect is provided with a detecting means for measuring the degree of contamination of the cover glass, and a control means for operating the heater means so as to keep the degree of contamination below a certain level from the measured value.

According to a third aspect of the invention, in a laser radar apparatus used as a vehicle distance measuring means in a vehicle rear-end collision warning system, an ultrasonic transducer is provided on a cover glass that covers the front surface of the light emitting portion and the light receiving portion of the laser radar.

In the fourth invention, means for measuring the degree of contamination of the cover glass and control means for activating the ultrasonic transducer so as to keep the degree of contamination below a certain level from the measured value are provided.

[0011]

According to the first aspect of the present invention, when the heater means is activated, snow and frost adhering to the cover glass are melted and removed, so that the measurement performance of the laser radar is improved regardless of weather conditions and running conditions. Can be maintained at

According to the second aspect of the present invention, even when snow or frost adheres to the cover glass, the heater means operates so as to keep the degree of dirt below a certain level, so that snow and frost can be removed. It is automatically and efficiently performed, and the measurement performance of the laser radar can be kept good.

According to the third aspect of the present invention, when the ultrasonic oscillator is activated, bending vibration is excited in the cover glass and splashes raindrops, dust, etc. adhering to the cover glass, so that the measurement performance of the laser radar can be favorably maintained.

According to the fourth aspect of the invention, when raindrops or dust adheres to the cover glass, the ultrasonic transducer operates so as to keep the degree of contamination below a certain level, so raindrops or dust are automatically removed. Efficiently, and the measurement performance of the laser radar can be favorably maintained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of a rear-end collision warning system for a vehicle, which is a vehicle speed sensor 1 for detecting a vehicle speed, a laser radar device 2 for measuring an inter-vehicle distance, and an alarm for generating a rear-end collision warning in a driver's cab. A buzzer 3 and a monitor circuit 4 for receiving various control signals from an information processing circuit 5 described later and displaying various kinds of information in the driver's cab are provided. Then, the information processing circuit 5 obtains the safe inter-vehicle distance from the detection value of the vehicle speed sensor 1, and when the measured value of the laser radar device 2 becomes lower than the safe inter-vehicle distance, the rear impact warning control for activating the warning buzzer 3 in the cab I do.

As shown in FIG. 2, the laser radar device 2 is provided with a heat ray heater 9 on a cover glass 8 which covers the front surfaces of the light emitting portion 6 and the light receiving portion 7. A plurality of these heaters 9 are arranged side by side in the lateral direction over substantially the entire surface of the glass 8, and are attached so that the intervals between the wirings are slightly dense around the front areas of the light emitting section 6 and the light receiving section 7. .

In order to protect the measurement performance of the laser radar from dirt, a function for controlling the operation of the heat ray heater 9 is added to the information processing circuit 5, and the degree of dirt on the cover glass 8 is detected as a detection means necessary for the control. A dirt sensor (not shown) that measures the internal reflectance of the emitted light beam is housed in the laser radar device 2.

FIG. 3 is a flow chart for explaining the control contents of the information processing circuit 5. Based on the detected value of the vehicle speed sensor 1 and the measured value of the laser radar device 2 after the initial setting, the alarm buzzer in the driver's cab as described above. 3 performs information processing of a rear-end collision alarm that controls the operations of the monitor circuit 4 and the monitor circuit 4 (step 1.0).
1, 1.02). When the degree of dirt (internal reflectance) of the cover glass 8 measured by the dirt sensor reaches a predetermined value A% or more, the heat wire heater 9 is turned on, and after heating for a predetermined time, the degree of dirt is constant. It is determined whether or not the value is B% (a level that does not hinder the distance measurement of the laser radar) or less, and when it becomes B% or less, the heat ray heater 9 is turned off (steps 1.03 to 1.07).

With such a structure, when the cover glass 8 of the laser radar device 2 is adhered with snow or the like and the degree of contamination thereof becomes A% or more, the heat ray heater 9 automatically operates.
Snow and the like on the surface of the glass 8 are melted and removed by the heat amount of the heater 9. Therefore, the degree of contamination of the cover glass 8 can be kept at B% or less even during snowfall, so that the measurement performance of the laser radar can be favorably maintained.

Although not shown, a switch for manually controlling the operation of the heater 9 is provided in the driver's cab, and in order to reduce unnecessary power consumption in fine weather or the like, this switch has a cover glass 8
It is advisable to add a function to cancel the automatic heating control of.

4 and 5 show another embodiment, in which an ultrasonic transducer 20 is used in addition to the heat ray heater 9. The ultrasonic oscillator 20 excites bending vibration in the glass 8 when it is supplied with a voltage. In order to avoid interference with the heat ray heater 9, a plurality of ultrasonic oscillators 20 are arranged on the back surface of the glass 8 in the center and side by side in this example. Set up. The same components as those in FIGS. 1 and 2 are designated by the same reference numerals.

The control contents of the information processing circuit 5a will be described with reference to the flowchart of FIG. 6, which is based on the detection value of the vehicle speed sensor 1 and the measurement value of the laser radar device 2 after the initial setting. Similarly, information processing of a rear-end collision alarm that controls the operation of the alarm buzzer 3 and the monitor circuit 4 in the driver's cab is performed (steps 1.01 and 1.02).

When the degree of dirt (internal reflectance) of the cover glass 8 measured by the dirt sensor becomes a predetermined value A% or more, the dirt level is a constant value B% (a level that does not hinder the distance measurement of the laser radar). The heat wire heater 9 is turned on until the temperature drops below, and after heating for a predetermined time, the ultrasonic transducer 20 is intermittently operated in a predetermined pattern (steps 1.03 to 1.11).

According to this, when the degree of contamination of the cover glass 8 becomes A% or more, the heat ray heater 9 and the ultrasonic transducer 20 are automatically operated until the level falls below the level B% which does not hinder the distance measurement of the laser radar. Works. Snow and frost on the surface of the glass 8 are melted by the amount of heat of the heater 9, and are blown off from the surface of the glass 8 by the bending vibration excited by the ultrasonic vibrator 20 as in the case of rainwater and dust. Therefore, the measurement performance of the laser radar can be favorably maintained regardless of the weather conditions and the running conditions.

Further, by using the ultrasonic transducer 20,
Compared with the below-mentioned air blow device that injects high pressure air,
Since it does not require additional parts such as air pipes and injection nozzles, it is advantageous in terms of space and layout, and consumes less power than air blow operation, thus reducing the burden on the battery. The heat wire heaters may be arranged side by side in the vertical direction on the cover glass surface.

FIG. 7 shows yet another embodiment, in which an air blower 11 is used in place of the ultrasonic vibrator 20. The air blower 11 generates high pressure air to generate the nozzle 1
It is made to jet from 0, and the adhered matter on the surface of the cover glass is blown off. The same components as those in FIG. 1 are designated by the same reference numerals. The control contents of the information processing circuit 5b are shown in the flowchart of FIG. 8. However, when the ultrasonic transducer 20 is read as the air blower 11, the same steps as those in the flowchart of FIG. Omit it.

[0027]

According to the first aspect of the present invention, in the laser radar device used as the vehicle distance measuring means in the vehicle rear-end collision warning system, the cover glass covering the front surface of the light emitting portion and the light receiving portion of the laser radar is heated. Since the heater means is provided, it is possible to remove snow, frost, etc. adhering to the cover glass by the operation of the heater means, so that the measurement performance of the laser radar can be favorably maintained regardless of weather conditions and running conditions.

According to the second aspect of the present invention, the detection means for measuring the degree of dirt on the cover glass and the control means for operating the heater means so as to keep the degree of dirt below a certain level from the measured value are provided. Removal of frost and frost is automatically and efficiently performed, and the measurement performance of the laser radar can be maintained well.

According to the third aspect of the invention, in the laser radar device used as the vehicle distance measuring means in the vehicle rear-end collision warning system, an ultrasonic transducer is provided on the cover glass covering the front surface of the light emitting portion and the light receiving portion of the laser radar. Since it was set up,
Since the raindrops and dust adhering to the cover glass can be removed by the bending vibration excited by the ultrasonic oscillator, the measurement performance of the laser radar can be maintained well.

According to the fourth invention, the means for measuring the degree of contamination of the cover glass and the control means for activating the ultrasonic transducer so as to keep the degree of contamination below a certain level from the measured value are provided. Raindrops and dust can be removed automatically and efficiently, and the measurement performance of the laser radar can be kept good.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a system showing an embodiment of the present invention.

FIG. 2 is a perspective view of a laser radar device and a front view thereof.

FIG. 3 is a flowchart illustrating the control contents of the system.

FIG. 4 is a configuration diagram of a system showing another embodiment.

FIG. 5 is a perspective view of a laser radar device and a front view thereof.

FIG. 6 is a flowchart illustrating the control contents of the system.

FIG. 7 is a structural diagram of a system showing another embodiment.

FIG. 8 is a flowchart illustrating the control contents of the system.

[Explanation of symbols]

 1 Vehicle speed sensor 2 Laser radar device 3 Alarm buzzer 5, 5a, 5b Information processing circuit 6 Light emitting part 7 Light receiving part 8 Cover glass 9 Heat wire heater 11 Air blow device 20 Ultrasonic transducer

Claims (4)

[Claims] 1. A laser radar device used as a vehicle-to-vehicle distance measuring means in a vehicle rear-end collision warning system, wherein a cover glass covering a front surface of a light emitting portion and a light receiving portion of the laser radar is provided with heater means for heating the cover glass. Characteristic vehicle laser radar device. 2. The detecting means for measuring the degree of contamination of the cover glass, and the control means for operating the heater means so as to keep the degree of contamination below a certain level from the measured value are provided. The described laser radar device. 3. A laser radar device used as a vehicle-to-vehicle distance measuring means in a rear-end collision warning system of a vehicle, characterized in that an ultrasonic transducer is provided on a cover glass covering a front surface of a light emitting portion and a light receiving portion of the laser radar. Laser radar device for vehicles. 4. A means for measuring the degree of contamination of the cover glass, and a control means for operating the ultrasonic transducer so as to keep the degree of contamination below a certain level from the measured value. The laser radar device according to item 1.