JPH11271452A - Start alarm device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a start alarm device in which the light emitting time of a light emitting element is shortened in a state that its own vehicle is stopped and that the light emitting element is hard to cool and in which the durable life of the light emitting element is enhanced. SOLUTION: When a state that both its own vehicle and a preceding vehicle are stopped is constituted for a set time or higher, the light emitting operation of a light emitting element 8 is stopped once. The quantity of light from the brake lamp of the preceding vehicle is detected by a light emitting element 11. Then the quantity of received light does not exceed a reference value, i.e., when it is judged that the brake lamp is turned off (a brake is not operated), the light emitting operation of the light emitting element 8 is resumed. On the other hand, a start alarm device is constituted in such a way that, when the quantity of received light exceeds the reference value, i.e., when it is judged that the brake is operated, the stop of the light emitting operation of the light emitting element 8 and the detection of the quantity of light by the light emitting element 11 are performed in succession, that, when the quantity of received light is changed, i.e., when it is judged that the preceding vehicle is started in such a way that its distance is increased and that the quantity of received light is dropped or that the brake lamp is turned off, the light emitting operation of the light emitting element 8 is resumed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a start alarm device for notifying an occupant that a preceding vehicle existing in front of a vehicle has started, and more particularly to radiating a laser toward the front of the vehicle by causing a light emitting element to emit light. Also, the present invention relates to a start alarm device using a laser radar device for detecting a distance from a preceding vehicle by detecting a reflected light from a preceding vehicle with a light receiving element and calculating a time from the emission to the arrival of the reflected light.

[0002]

2. Description of the Related Art As a conventional start alarm device, for example, one described in Japanese Utility Model Laid-Open No. 5-92770 is known. This means that when the own vehicle is in a stopped state, if the inter-vehicle distance to the preceding vehicle is equal to or less than a set value, it is considered that there is a traffic jam, and if it is determined that the preceding vehicle has started during this traffic jam,
First, an alarm is issued with visible light. After that, when it is determined that the stop state of the own vehicle has continued for a certain period of time, a sound warning is issued.

[0003]

However, in the above-described conventional start alarm device, when a laser radar is used as a distance sensor between the host vehicle and the preceding vehicle, both the own vehicle and the preceding vehicle are stopped and the distance between the vehicles is low. Even when the distance does not change continuously, the light emitting element needs to emit light at all times. However, when the vehicle is stopped, there is no traveling wind, so that the light-emitting element is less likely to be cooled as compared to when the vehicle is traveling, so that the durability of the light-emitting element is shortened.

[0004] The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a start alarm device that can improve the durability life of a light emitting element.

[0005]

In order to achieve the above object, the present invention is configured as described in the appended claims. That is, according to the first aspect of the present invention, when the state in which both the own vehicle and the preceding vehicle are stopped continues for a predetermined time or more, the light emission of the light emitting element is temporarily stopped, and the light amount from the brake lamp of the preceding vehicle is reduced. If it is detected that the amount of received light does not exceed the reference value, that is, if it is determined that the brake lamp is turned off (the brake is not operated), light emission is restarted. On the other hand, when the amount of received light exceeds the reference value, that is, when it is determined that the brake is operating, the light emission of the light emitting element is continuously stopped and the amount of light is detected by the light receiving element. That is, when it is determined that the inter-vehicle distance has been increased and the inter-vehicle distance has decreased and the amount of received light has decreased, or that the brake lamp has been turned off, light emission is restarted.

[0006] With the above configuration, when both the front vehicle and the own vehicle stop and the brake of the front vehicle is operating, the light emission of the light emitting element can be stopped. Further, even when the preceding vehicle is stopped without operating the brake (the brake lamp is not lit), the light emission of the light emitting element is intermittently stopped at regular intervals. Therefore, the emission time of the light emitting element can be reduced when the vehicle is stopped. Further, when there is a possibility that the preceding vehicle has started, it is possible to reliably detect the alarm and issue an alarm.

Further, in the invention according to claim 3,
Two light receiving elements are provided, and the wavelength-sensitivity characteristics of each light receiving element are set so that the reflected light of the laser is detected on the one hand and the light quantity of the brake lamp of the front vehicle is detected on the other hand.

Further, in the invention according to claim 4,
Separate the light receiving element for detecting the reflected light of the laser and the light receiving element for detecting the light amount of the brake lamp of the front vehicle,
A filter that transmits only red light is disposed in front of the light receiving element that detects the light amount of the brake lamp. As a result, it is possible to reduce the influence of disturbance of the surrounding light source other than the brake lamp.

[0009]

According to the present invention, the light-emitting time of the light-emitting element in the vehicle stopped state where the light-emitting element is hardly cooled is shortened,
The effect that the durability life of the light emitting element can be improved can be obtained. Further, according to the fourth aspect of the present invention, the effect of reducing the influence of disturbance of the surrounding light source other than the brake lamp can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a block diagram showing a start alarm device 1 according to a first embodiment of the present invention. The start alarm device 1 measures an inter-vehicle distance from a preceding vehicle, and outputs a distance signal and a start alarm signal. The laser radar device 2 receives the inter-vehicle distance signal from the laser radar device 2 and displays the inter-vehicle distance. And a buzzer 4 which receives a start alarm signal from the laser radar device 2 and emits an alarm sound.

The laser radar device 2 includes a power supply circuit 5, a signal processing device 6, a drive circuit 7, a light emitting element 8, a light emitting lens 9, a light receiving lens 10, a light receiving element 11, and an amplifier circuit 12. Although the signal processing device 6 is described inside the laser radar device 2, this portion includes not only the distance measurement control of a normal laser radar device but also the control content of the control means according to claim 1. I have. The signal processing device 6 can be constituted by, for example, a CPU. In addition, the signal processing device 6
A signal from a vehicle speed sensor (not shown) (for example, a sensor that measures the rotation of a wheel or an axle, or a Doppler radar that detects the ground speed) is used as the vehicle speed signal to be input to. For the light emitting element 8 and the light receiving element 11, for example, a semiconductor element can be used.

FIG. 2 is a diagram for explaining the operation of the present embodiment, and shows a side view showing a running state of the vehicle and a signal waveform diagram corresponding thereto. Hereinafter, the principle of detecting the distance between the vehicle and the front vehicle by the laser radar device 2 will be described with reference to FIGS. The laser radar device 2 has its own vehicle 13
Attached to the front of the. Then, when an ON / OFF signal by an ignition switch or the like is turned ON, the signal processing device 6 issues a drive signal for the light emitting element 8.

The drive circuit 7 drives the light emitting element 8 in response to a drive signal from the signal processing device 6. As the light emitting element 8, an element that emits near-infrared light having a radiation intensity peak near the wavelength λ = 850 to 950 nm is generally used. After the light emitted by the light emitting element 8 passes through the light emitting lens 9, the light is emitted as pulsed radiation 14 toward the front of the vehicle 13. The emitted light 14 is reflected by the reflector 16 of the front vehicle 15.
And returns to the laser radar device 2 as reflected light 17.

The reflected light 17 is condensed on the light receiving element 11 by the light receiving lens 10 and is converted by the light receiving element 11 into a current proportional to the amount of light. The output of the light receiving element 11 is amplified by the amplifier circuit 12 and input to the signal processing device 6.

The signal processing device 6 calculates the time t from the emission of the radiated light 14 to the arrival of the reflected light 17, and calculates the inter-vehicle distance D between the own vehicle 13 and the front vehicle 15 based on the following equation. I do. D = (c × t) / 2 where c: light speed The calculated inter-vehicle distance D is used as the inter-vehicle distance signal in the display device 3.
And is displayed on the display device 3 as inter-vehicle distance information up to the preceding vehicle 15. In addition, the signal processing device 6 calculates the following distance,
A start warning signal is sent to the buzzer 4 when a predetermined judgment condition is satisfied from the vehicle speed or the like. Buzzer 4 receives the signal,
The occupant of the vehicle is notified by sound that the preceding vehicle has started.

Next, FIG. 3 is a flowchart showing a flow up to issuing a start alarm signal. First, as shown in steps 100 to 106, the distance Dn to the preceding vehicle
Is measured, and if all of the following conditions (1) to (4) are satisfied, the present inter-vehicle distance Dn is changed to the previous inter-vehicle distance Dn.
It is stored in the memory as −1 (step 105), and the light emission of the light emitting element is stopped (step 106).

(1) The present inter-vehicle distance Dn is equal to or less than a predetermined value Ds (step 101). (2) Current inter-vehicle distance Dn and previous inter-vehicle distance Dn
-1 is equal (step 102). (3) The vehicle has stopped (step 103). However, Va in the figure is the own vehicle speed, and is a value based on the vehicle speed signal from the vehicle speed sensor. (4) The states (1) to (3) have continued for a predetermined time T1 or more (step 104).

When all of the above conditions (1) to (4) are satisfied, both the preceding vehicle and the own vehicle are stopped and are relatively close to the preceding vehicle. In such a state, the front vehicle may be stopped by depressing the brake, and the front vehicle does not start as long as the brake is depressed. That is, since the inter-vehicle distance to the preceding vehicle does not change, there is no need to constantly measure the distance to the preceding vehicle, and it is not necessary to make the light emitting element emit light. Therefore, light emission is stopped, and the life of the light emitting element is extended.

In the above conditions (1) to (4), the predetermined value Ds of the following distance and the predetermined time T1 are determined by the distance to the preceding vehicle when the preceding vehicle is stopped due to the presence of the preceding vehicle due to a signal waiting or traffic jam. It can be determined from the experience value such as the stop time and the like. As an example, numerical values such as Ds: 6 m and T1: 3 seconds can be used.

On the other hand, if any one of the above conditions (1) to (4) is not satisfied, the current inter-vehicle distance Dn
Is stored in the memory as the preceding inter-vehicle distance Dn-1, and a normal distance measurement operation is performed (steps 107 and 1).
00).

Here, the characteristics of the light receiving element will be described.
FIG. 4 is a characteristic diagram showing the wavelength-sensitivity characteristics of the light receiving element. As shown in FIG. 4, the light receiving element has a wavelength λ: 700 to 90.
It has high sensitivity at 0 nm. That is, near-infrared light and red light emitted from the light emitting element can be detected with high sensitivity, and the sensitivity to light of other colors is low. By using a light receiving element having such a sensitivity characteristic, when the light emitting element stops emitting light, it is possible to detect the red light from the brake lamp of the preceding vehicle and detect whether or not the preceding vehicle is stepping on the brake.

Returning to the flowchart of FIG. 3 again, in steps 108 to 110, the light amount is detected by the light receiving element.
If the amount of received light exceeds a predetermined reference value α, it is determined that the preceding vehicle is stepping on the brake. In that case, the light amount detection by the light receiving element is continued while the light emission is stopped.

If the received light amount does not change compared to the previous received light amount, it is determined that the preceding vehicle has continued to depress the brake, and the light amount detection is continued (NO in step 111). However, when the light amount changes (YES in step 111).
In step S112, it is determined that the vehicle has exhibited some behavior, such as releasing the brake or moving forward in a creep state while stepping on the brake, and restarts light emission to perform distance measurement (step 112).

In step 109, the received light amount is set to the reference value α.
If it does not exceed, the brake lamp is not lit (the preceding vehicle has not depressed the brake), so it is considered that there is a possibility that the vehicle will start immediately. Perform ranging.

After restarting the distance measurement, the following (5)
When all of conditions (7) to (7) are satisfied, the start alarm is turned on.
And an alarm is issued (step 116). On the other hand, (5)
If any one of the conditions (7) to (7) is not satisfied, the current inter-vehicle distance Dn is stored in the memory as the previous inter-vehicle distance Dn-1 (step 118), and the distance measurement (step 100) is performed. .

(5) The current inter-vehicle distance Dn is larger than the previous inter-vehicle distance Dn-1 (step 113). (6) The vehicle has stopped (step 114). (7) The conditions (5) and (6) have continued for a predetermined time T2 or more (step 115). The case where all of the above conditions (5) to (7) are satisfied is a case where the own vehicle is stopped while the preceding vehicle has started and the state has continued for a predetermined time or more.

Next, an operation example in the present embodiment will be described. 5 and 6 are signal waveform diagrams showing an example of the operation of the start alarm device in a specific scene. In FIGS. 5 and 6, the horizontal axis indicates time. First, FIG. 5 shows a case where the preceding vehicle has stopped by stepping on the brake. The state where the inter-vehicle distance to the preceding vehicle does not change and the vehicle is stopped is T
If it continues for 1 second or more, the light emission of the light emitting element is stopped and red light from the brake lamp is detected (point a). Thereafter, when the brake is released to start the preceding vehicle, the red light changes, and the light receiving level of the light receiving element changes (point b). As a result, light emission is resumed, and the distance to the preceding vehicle is measured (point c). If the state in which the preceding vehicle starts and the own vehicle is stopped continues for T2 seconds or more, an alarm is issued (point d). As described above, when the time when both the preceding vehicle and the own vehicle are stopped is T0, light emission is stopped for approximately (T0-T1).

FIG. 6 shows a case where the preceding vehicle is stopped without stepping on the brake. In this case, the light receiving level does not exceed the reference value α (point e) because the preceding vehicle has not stepped on the brake. As a result, the light emission is restarted and the distance between the vehicle and the preceding vehicle is measured (point f). If the inter-vehicle distance at that time has not changed from the previous inter-vehicle distance and the own vehicle has stopped, it means that the state has continued for T1 or more, and the light emission is stopped again (point g). As a result, light emission and stop are intermittently repeated until the start of the preceding vehicle is detected by the inter-vehicle distance measurement. In this way, light emission is stopped for about half of (T0-T1). Note that, as described above, the cycle of repeating light emission and stop when the light receiving level does not exceed the reference value α can be arbitrarily set by setting the minimum duration of light emission and stop.

Next, FIG. 7 is a block diagram showing a start alarm device 18 according to a second embodiment of the present invention. In the first embodiment, the detection of near-infrared light and red light is performed by one light-receiving element. However, in the present embodiment, the detection is performed separately. The start alarm device 18 includes a laser radar device 19, a display device 3, and a buzzer 4. Of the components constituting the laser radar device 18, the power supply circuit 5,
The drive circuit 7, the light emitting element 8, the light emitting lens 9, and the light receiving lens 10 are the same as in the first embodiment. Further, the signal processing device 26 includes not only the distance measurement control of the ordinary laser radar device but also the control content of the control means according to the first embodiment, as in the first embodiment.

Hereinafter, portions different from the first embodiment will be described. Reference numeral 20 denotes a light receiving element having a sensitivity peak for near infrared light. FIG. 8 is a characteristic diagram showing an example of the wavelength-sensitivity characteristics of the light receiving element 20. Reference numeral 21 denotes an amplifier circuit for amplifying an input from the light receiving element 20 and outputting the amplified signal.
A filter 22 has a characteristic of transmitting only red light. Reference numeral 23 denotes a light receiving lens for collecting light transmitted through the filter 22, and the light collected by the light receiving lens 23 is detected by a light receiving element 24. The light receiving element 24 has a sensitivity peak for red light. FIG. 9 shows the light receiving element 2
4 is a characteristic diagram illustrating an example of a wavelength-sensitivity characteristic of FIG. An amplifier circuit 25 amplifies the input from the light receiving element 24 and outputs the amplified signal. Reference numeral 26 denotes a signal processing device which receives an input from the amplifier circuits 21 and 25, calculates an inter-vehicle distance to the preceding vehicle, and outputs a start warning signal based on the input. This is shown in Figure 3
This is the same as that described above.

When light emission of the light emitting element is stopped, it is desired to detect only red light from the front of the own vehicle. It is considered that the brake light of the front car occupies a large part of the light from the front because it is stopped close to the front car.
Light from other light sources may be mixed. These lights are received via a filter 22 and a light receiving element 24
By using a red light having a sensitivity peak at the wavelength of red light, the influence from the ambient light source can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a start alarm device 1 according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the present embodiment, and is a side view showing a traveling state of the vehicle and a corresponding signal waveform diagram.

FIG. 3 is a flowchart showing a flow up to issuing a start alarm signal.

FIG. 4 is a characteristic diagram showing wavelength-sensitivity characteristics of a light receiving element.

FIG. 5 is a signal waveform diagram showing an example of the operation of the start alarm device when the front vehicle stops by stepping on the brake.

FIG. 6 is a signal waveform diagram showing an example of the operation of the start alarm device when the preceding vehicle is stopped without stepping on the brake.

FIG. 7 is a block diagram showing a start alarm device 18 according to a second embodiment of the present invention.

FIG. 8 is a characteristic diagram showing an example of a wavelength-sensitivity characteristic of the light receiving element 20 that receives a laser beam.

FIG. 9 shows a light receiving element 2 for receiving red light from a brake lamp.
4 is a characteristic diagram illustrating an example of a wavelength-sensitivity characteristic of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Start alarm device 2 ... Laser radar device 3 ... Display device 4 ... Buzzer 5 ... Power supply circuit 6 ... Signal processing device 7 ... Drive circuit 8 ... Light emitting element 9 ... Light emitting lens 10 ... Light receiving lens 11 ... Light receiving element 12 ... Amplifying circuit 13 Own car 14 Radiation light 15 Front car 16 Reflector 17 Reflected light 18 Starting alarm device 19 Laser radar device 20 Light receiving element 21 Amplifying circuit 22 Filter 23 Light receiving lens 24 Light receiving Element 25: Amplifier circuit 26: Signal processing device

Claims (4)

[Claims] 1. A light emitting element emits light to emit a laser beam in front of the own vehicle, and a reflected light from a preceding vehicle existing in front of the own vehicle is detected by a light receiving element. By using a laser radar device that calculates the inter-vehicle distance to the preceding vehicle by calculating the time, a start alarm device that notifies the occupant that the preceding vehicle has started, When the inter-vehicle distance with the preceding vehicle does not change, and when the stopped state of the own vehicle continues for a predetermined time or more, the light emitting element temporarily stops emitting light and the light receiving element detects the amount of light from the front, When the amount of light received by the light receiving element exceeds the reference value, the light emission stop and the light amount detection from the front are continued, and when the light amount does not exceed the reference value, the light emission of the light emitting element is restarted and Measure the distance, and In the state where the light emission is stopped and the light amount detection is continued beyond the reference value, when the light receiving amount of the light receiving element changes, control means for controlling the light emitting element to restart the light emission and measure the distance to the front. A start alarm device comprising: 2. The start alarm device according to claim 1, wherein the light receiving element has a wavelength-sensitivity characteristic capable of detecting a red light region. 3. The start according to claim 1, wherein said light receiving element comprises two light receiving elements, and one of said light receiving elements has a sensitivity peak at a wavelength in a red light region. Alarm device. 4. The starting alarm device according to claim 3, wherein a filter that transmits only red light is disposed in front of the light receiving element having a sensitivity peak at a wavelength in a red light region.