JP5429063B2 - Rear collision warning device for vehicles - Google Patents

Description

  The present invention relates to a vehicular rear-end collision warning device that warns a rear vehicle when the rear vehicle approaches in order to prevent a rear vehicle from colliding.

  Conventionally, in order to prevent a rear vehicle from colliding, a rear collision warning device for a vehicle that warns the rear vehicle when the rear vehicle approaches is known (for example, see Patent Documents 1 and 2). . For example, in Patent Document 1, a warning device that emits a warning sound when a distance sensor that measures the distance between the vehicle behind and the vehicle behind the vehicle is determined and the distance between the vehicle and the vehicle behind is determined by the distance sensor. It is disclosed.

  For example, Patent Document 2 discloses a warning device including an LED that emits light toward a rear vehicle when the rear vehicle approaches in order to prevent a rear vehicle rear-end collision at night when visibility deteriorates. ing. The warning device of Patent Document 2 includes a light receiving element that detects headlight light of a rear vehicle. Then, whether or not the rear vehicle is approaching is determined based on whether or not the light receiving element detects the headlight light of the rear vehicle. Moreover, the warning device of Patent Document 2 includes a solar cell for supplying power to the warning device. Then, based on the power generation amount of the solar cell, it is distinguished whether it is daytime or nighttime. If it is daytime, it is not necessary to warn, and the power generated by the solar cell is charged into the secondary battery. In the nighttime, the warning device is driven by the power charged in the secondary battery.

JP 2001-239856 A JP 7-257273 A

  However, in the conventional vehicle rear-end collision warning device, it is necessary to provide a sensor such as a distance sensor and a light receiving element for detecting the approach of the rear vehicle, and there is a problem that the configuration becomes complicated.

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide a vehicular rear-end collision warning device that can warn an approaching rear vehicle with a simpler configuration than before. .

In order to solve the above problems, a vehicle rear-end collision warning device according to the present invention is provided in the host vehicle, and emits light toward the rear of the host vehicle;
A solar cell that is provided at a position where the light emitted from the vehicle behind the host vehicle can be received, and that generates power by the received light;
Based on the amount of power generated by the solar cell, an approach determining means for determining whether or not a rear vehicle is approaching the host vehicle,
When the approach determining means determines that the rear vehicle is approaching, a signal output means for outputting a light emission instruction signal instructing light emission of the light emitting unit;
Which receives the emission instruction signal outputted from the signal output unit, based on receiving the emission instruction signal, driving means for emitting the light emitting portion by the power which the solar cell is generating power, Ru with a .

  According to this, since the solar cell is provided at a position where light light emitted from the rear vehicle can be received, electric power can be generated by receiving the light light from the rear vehicle at night. The approach determining means determines whether or not the rear vehicle is approaching the host vehicle based on the amount of power generated by the solar cell, and it is necessary to provide a sensor for detecting the approach of the rear vehicle. Since there is no, the configuration can be simplified. When the approach determination means determines that the vehicle behind is approaching, the signal output means outputs a light emission instruction signal instructing light emission of the light emitting unit, and the drive means receives the light emission instruction signal. Since the light emitting unit is driven based on the above, light can be emitted toward the rear vehicle. Therefore, it is possible to call attention to the rear vehicle. Furthermore, since the drive means is driven by the power generated by the solar cell, that is, the power generated by the light of the rear vehicle, it is possible to suppress the power consumption of a separate system from the solar cell.

Further, in the present invention, based on the amount of power generated by the solar cell, it is provided with day / night determination means for determining whether it is currently nighttime or daytime,
When the day / night determination means determines that it is currently daytime, the light emitting unit may not emit light.

  According to this, in the daytime, it is considered that the rear vehicle can easily see the own vehicle and there is little need to give a warning. However, if the day / night determination means determines that it is currently daytime, Since this is not done, unnecessary warnings can be prevented.

Further, in the present invention, it further comprises a change amount calculation means for calculating a power generation change amount indicating a time change of the power generation amount generated by the solar cell,
The approach determining means determines whether or not a rear vehicle is approaching the host vehicle based on the power generation change amount calculated by the change amount calculating means.

  According to this, the change amount calculation means calculates the power generation change amount indicating the time change of the power generation amount generated by the solar cell. The power generation change amount can be used as an index of how fast the rear vehicle is approaching the host vehicle. That is, when the rear vehicle is approaching the host vehicle at a high speed, the temporal change in the amount of light received by the solar cell is increased, and thus the amount of power generation change is increased. On the other hand, for example, when both the host vehicle and the rear vehicle are stopped, such as when parking or waiting for a signal, even if the power generation amount is large, the power generation change amount is small. There is no need to warn in such cases. And since an approach judgment means judges whether the back vehicle is approaching to the own vehicle based on the amount of power generation change, it can judge correctly whether it is the approach which needs to be warned.

Further, in the present invention, when the approach determining means determines that a rear vehicle is approaching, a light emission pattern when the light emitting unit emits light, and a light emission pattern that differs according to the power generation change amount is displayed. A light emission pattern determining means for determining,
The signal output means outputs a signal instructing light emission in the light emission pattern determined by the light emission pattern determination means as the light emission instruction signal,
The driving unit causes the light emitting unit to emit light with the light emission pattern based on the light emission instruction signal instructing light emission with the light emission pattern.

  According to this, the light emission pattern determining means determines a different light emission pattern according to the amount of change in power generation, and the signal output means and the drive means cause the light emitting unit to emit light with the determined light emission pattern. Thus, it is possible to easily determine how close the vehicle is.

  In this case, the light emission pattern determining means determines a light emission pattern in which the amount of light when the light emission changes as the light generation change amount increases.

  According to this, since the light emission pattern determining means determines the light emission pattern in which the amount of light when the light emission changes is larger as the power generation change amount is larger, the light emitting portion can be made to emit light brighter as the rear vehicle approaches the host vehicle. . Therefore, greater attention can be urged toward the rear vehicle as it approaches the host vehicle.

  In addition, the light emission pattern determination unit may determine a light emission pattern that blinks so that the light emission cycle becomes shorter as the power generation change amount is larger.

  According to this, since the light emission pattern determining means determines the flashing light emission pattern in which the light emission cycle becomes shorter as the power generation change amount is larger, the light emitting unit can be made to flash in a shorter cycle as the rear vehicle approaches the host vehicle. it can. Therefore, greater attention can be urged toward the rear vehicle as it approaches the host vehicle.

Further, in the present invention, a battery that charges the power generated by the solar cell while the driving unit does not cause the light emitting unit to emit light,
The driving means may cause the light emitting unit to emit light by charging power charged in the battery in addition to power generated by the solar cell.

  According to this, while the driving means does not cause the light emitting unit to emit light, the battery can be charged with the electric power generated by the daytime sun or the like. And since a drive means is driven also with the charging electric power charged in the battery, even if the light light from a back vehicle is weak, a drive means can be driven and a light emission part can be light-emitted. .

1 is a block diagram illustrating a configuration of a vehicular rear-end collision warning device 1. FIG. It is the figure which showed the external appearance of the own vehicle 100 and the back vehicle. 4 is a diagram illustrating the relationship between the amount of received light and the amount of power generation P in the solar cell 10. FIG. It is the flowchart which showed the process which the control part 20 performs. It is a figure explaining the difference in the electric power generation amount of the solar cell 10 at night and daytime. It is the figure which showed the lines 81 and 82 which illustrated the time change of the electric power generation amount P at the time of vehicle approach (the figure (a)) and normal time (the figure (b)). It is the figure which showed electric power generation variation | change_quantity (DELTA) P1 at the time of approach, and electric power generation variation | change_quantity (DELTA) P2 at the time of normal time in the bar graph shape. It is the figure which showed the line 71 which illustrated the relationship between power generation variation | change_quantity (DELTA) P and the light quantity S or the light emission period T. FIG. It is the block diagram which showed the structure of the vehicle rear-end collision warning apparatus 2 which concerns on a modification.

  Hereinafter, an embodiment of a vehicular rear-end collision warning device according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a vehicular rear-end collision warning device 1 according to the present embodiment. The vehicle rear-end collision warning device 1 is provided in the host vehicle and includes a solar cell 10, a control unit 20, a drive unit 30, and a light emitting unit 40 as shown in FIG. The solar cell 10 is a panel-shaped device that generates electricity by light such as sunlight, and is provided at a position where the headlight can be received when the rear vehicle lights the headlight.

  Here, FIG. 2 is a diagram for explaining a specific installation position of the solar battery 10 and shows the appearance of the host vehicle 100 and the rear vehicle 200. As shown in FIG. 2, the host vehicle 100 is, for example, a sedan type passenger vehicle having a trunk portion 110 provided in a form separated from a passenger compartment at the rear of the host vehicle 100. The solar cell 10 is provided at the rear side surface 111 of the trunk portion 110, that is, at the tail end of the host vehicle 100. Since the rear side surface 111 faces rearward of the host vehicle 100, the panel-like solar cell 10 provided on the rear side surface 111 also faces rearward of the host vehicle 100. In general, the height of the rear side surface of the passenger car (the rear side surface 111 in FIG. 2) and the height of the headlight of the passenger car are approximately the same, and therefore, as shown in FIG. The obtained solar cell 10 can efficiently receive the headlight light L1 emitted from the rear vehicle 200 almost from the front. Of course, the solar cell 10 can receive not only the headlight light L1 but also sunlight L2 (including reflected sunlight) in the daytime.

  In addition, when the own vehicle is not a sedan type passenger car, for example, even if it is a one-box car, similarly, by providing a solar cell on the rear side surface of the own vehicle, the headlight light of the rear vehicle can be received efficiently.

  Moreover, the solar cell 10 shall generate electric power according to the amount of received light. Here, FIG. 3 is a diagram illustrating the relationship between the amount of received light and the amount of power generation P in the solar cell 10. As shown in FIG. 3, in the solar cell 10, the power generation amount P increases as the amount of received light increases.

In the present invention, the light emitting unit 40 is caused to emit light with the electric power generated by the solar cell 10 from the headlight light L1 from the rear vehicle 200. Therefore, as the solar cell 10, the light emitting unit 40 can emit light. A solar cell having the ability to generate electric power is employed. For example, a solar cell having a desired power generation capability can be configured by using a plurality of solar cells having a certain power generation capability. For example, assuming that there is a solar cell of 15 cm × 7.5 cm, it is possible to configure a solar cell with an area (15 cm × 7.5 cm × 36) = 0.450 m ² by arranging 36 solar cells. Then, assuming that the solar battery has a power generation capacity by sunlight in the daytime of 80 W in summer when the amount of sunlight is large, 40 W in winter when the amount of sunlight is small, and the power consumption of the headlight is 66 W, for example, The battery can provide the same power as a headlight. Therefore, it is considered that power for causing the light emitting unit 40 to emit light can be covered.

  Returning to the description of FIG. 1, the power generation amount signal indicating the power generation amount in the solar cell 10 is input to the control unit 20. The control unit 20 includes a computer such as a CPU, a ROM, and a RAM, and a circuit that converts an input power generation amount signal into a signal (a power generation change amount described later) as necessary. And the computer (control part 20) performs the process about whether it is necessary to warn the back vehicle 200 based on the input electric power generation amount signal. If it is determined that a warning is necessary, a light emission instruction signal for instructing light emission of the light emitting unit 40 is output to the drive unit 30. The light emission instruction signal is a signal that also indicates the light emission pattern (light quantity, light emission cycle) of the light emitting unit 40. The processing executed by the control unit 20 will be described in detail later.

  The drive unit 30 is configured as a drive circuit that receives the light emission instruction signal output from the control unit 20 and generates a drive signal for causing the light emission unit 40 to emit light when the light emission instruction signal is received. is there. Specifically, the drive unit 30 generates a drive signal corresponding to the light emission pattern (light quantity, light emission cycle) instructed by the light emission instruction signal. A drive signal having a large voltage value, current value, duty ratio, etc. is generated. Further, for example, when a light emission pattern with a short light emission cycle is instructed, the drive unit 30 generates a drive signal with a short cycle. In the present embodiment, the power generated by the solar cell 10 is input to the drive unit 30, and the drive unit 30 is driven by the power from the solar cell 10. The drive unit 30 corresponds to the “drive unit” of the present invention.

  The light emitting unit 40 emits light in response to a driving signal from the driving unit 30 and is, for example, an LED. The light emitting unit 40 is provided at a position where light is emitted toward the rear of the host vehicle 100. Specifically, as shown in FIG. 2, the light emitting unit 40 is provided in the rear window unit 120 of the host vehicle 100, and more specifically, provided in the four corners of the rear window unit 120. Therefore, since the light emitted from the light emitting unit 40 is directed to the rear of the host vehicle 100, the rear vehicle 200 can easily recognize that the light emitting unit 40 has emitted light. Note that the installation position of the light emitting unit 40 is not limited to that shown in FIG. 2, and may be installed at any position as long as the rear vehicle 200 can grasp the light emission of the light emitting unit 40. 110 may be installed on the rear side surface 111. Of course, the number of light emitting units 40 is not limited to four.

  Next, processing executed by the control unit 20 will be described with reference to the flowchart of FIG. Note that the processing of the flowchart of FIG. 4 is started, for example, when the engine is started, and then repeatedly executed at regular intervals.

  First, in step S11, based on the power generation amount signal from the solar cell 10, it is determined whether the current time is night or daytime. Specifically, the determination is made by paying attention to the difference in the power generation amount of the solar cell 10 between nighttime and daytime. Here, FIG. 5 is a diagram for explaining the difference in power generation amount of the solar cell 10 between nighttime and daytime. Specifically, FIG. 5A shows the power generation amount of the solar cell 10 at night. FIG. 5 (b) shows the power generation amount of the solar cell 10 in the daytime in a bar graph for each of the normal time and the time of the vehicle approach. FIG. In addition, the vertical axis | shaft (axis | shaft of electric power generation amount P) of Fig.5 (a) and FIG.5 (b) is the same scale.

  As shown in FIGS. 5A and 5B, since the sun does not come out at night, the nighttime power generation amounts P1 and P2 are smaller than the daytime power generation amounts P3 and P4. When the vehicle approaches at night, the amount of headlight light L1 from the rear vehicle 200 increases, so that the power generation amount P2 when the vehicle approaches is larger than the power generation amount P1 at the normal time. Even in this case, the power generation amount P2 when the vehicle approaches is considered to be smaller than the daytime power generation amounts P3 and P4. Therefore, as shown in FIG. 5, a line 91 for dividing day and night can be drawn between the power generation amounts P1 and P2 at night and the power generation amounts P3 and P4 during the daytime. In addition, since it is considered that the headlight is not turned on in the daytime, the power generation amounts P3 and P4 are the same between the normal time and the vehicle approach (see FIG. 5B).

  In step S11, it is determined whether the current power generation amount P is smaller than the power generation amount threshold value Pth indicated by the line 91 in FIG. Here, when the power generation amount P is larger than the threshold value Pth (S11: NO), the process of the flowchart in FIG. In this case, no warning is given. This is because, in the daytime, the rear vehicle 200 can easily see the host vehicle 100, so that it is not particularly necessary to warn by light emission. On the other hand, when the power generation amount P is smaller than the threshold value Pth (S11: YES), it is assumed that it is nighttime, and the processing from step S12 is executed. In addition, the control part 20 which performs step S11 is equivalent to "day and night judgment means" in this invention.

  In step S12, a power generation change amount ΔP indicating a time change of the power generation amount P is calculated. Here, FIG. 6 is a diagram for explaining the concept of the power generation change amount ΔP. Specifically, FIG. 6A shows a line 81 illustrating the time change of the power generation amount P when the vehicle approaches. FIG. 6B shows a line 82 illustrating the time variation of the power generation amount P at the normal time. When the rear vehicle 200 gradually approaches the host vehicle 100, the amount of light received by the solar cell 10 gradually increases as the rear vehicle 200 approaches, so the power generation amount P by the solar cell 10 is increased. Gradually increases with time (see FIG. 6A). On the other hand, when the rear vehicle 200 is traveling at a constant distance from the host vehicle 100, and when gradually moving away from the host vehicle 100, the host vehicle 100, the rear vehicle, such as when waiting for a signal or parking. In a normal time such as when both the vehicles 200 are stopped, the time change of the power generation amount P is small (see FIG. 6B). That is, the line 81 when approaching FIG. 6A has a larger slope than the line 82 when normal in FIG.

  In step S12, the current inclination of the line of time variation of the power generation amount P is calculated as the power generation variation amount ΔP. In the example of FIG. 6, the slope of the line 81 (when approaching) or the line 82 (when normal) at the present time is calculated. Here, FIG. 7 is a graph showing the power generation change amount ΔP1 when approaching and the power generation change amount ΔP2 during normal time in a bar graph form. As described with reference to FIG. 6, since the line 81 at the time of approach has a larger slope than the line 82 at the time of normal approach, the power generation change amount ΔP1 at the time of approach is larger than the power generation change amount ΔP2 at the time of normal time (FIG. 7). reference). Therefore, as shown in FIG. 7, a line 92 for distinguishing whether or not the vehicle is approaching can be drawn between the power generation change amount ΔP1 at the time of approach and the power generation change amount ΔP2 at the time of normal time. In addition, the control part 20 which performs step S12 is equivalent to the "change amount calculation means" of this invention.

  In step S13, it is determined whether or not the power generation change amount ΔP calculated in step S12 is greater than the power generation change amount threshold value ΔPth indicated by the line 92 in FIG. If it is smaller (S13: NO), it is assumed that it is normal time, and the flowchart of FIG. In this case, no warning is given. As a result, when the vehicle 100 is traveling a certain distance from the host vehicle 100, and when gradually moving away from the host vehicle 100, both the host vehicle 100 and the rear vehicle 200 are stopped like waiting for a signal or parking. In such a case, an unnecessary warning can be prevented. In addition, the control part 20 which performs step S13 is corresponded to the "approach determination means" of this invention.

  In step S13, when the power generation change amount ΔP is larger than the threshold value ΔPth (S13: YES), it is determined that the rear vehicle 200 is approaching, and the process proceeds to step S14 and subsequent steps to warn the rear vehicle 200. First, in step S14, a light emission pattern when the light emitting unit 40 emits light is determined. Specifically, a light emission pattern in which the light amount S (brightness) when the light is emitted increases as the power generation change amount ΔP increases is determined as the light emission pattern. Further, as the light emission pattern, a light emission pattern that blinks so that the light emission period T becomes shorter as the power generation change amount ΔP is larger may be determined. In addition, you may determine the light emission pattern which changes both the light quantity S and the light emission period T. FIG.

  Here, FIG. 8 is a diagram for explaining a specific method of determining the light emission pattern. Specifically, the line 71 and the power generation change amount ΔP showing the relationship between the power generation change amount ΔP and the light amount S. A line 72 illustrating the relationship between the light emission period T and the light emission period T is shown. As shown in FIG. 8, the line 71 of the light quantity S is a line in which the light quantity S increases proportionally as the power generation change amount ΔP increases. On the other hand, the line 72 of the light emission period T is a line in which the light emission period T decreases proportionally as the power generation change amount ΔP increases. Note that when the power generation change amount ΔP is smaller than the threshold value ΔPth in step S13 (S13: NO), it is not necessary to determine the light emission pattern, and FIG. 8 shows lines 71 and 72 in the range equal to or larger than the threshold value ΔPth. Yes. According to the relationship of FIG. 8, the larger the power generation change ΔP, that is, the closer the rear vehicle 200 approaches, the more light emission pattern S or the light emission pattern with a short light emission period T is determined. Then, the relationship between the power generation change amount ΔP and the light amount S or the light emission period T as shown in FIG. 8 is stored in advance in the ROM or the like, and in step S14, the current power generation change amount ΔP is obtained by referring to the stored relationship. The light emission pattern according to the is determined. For example, when the power generation change amount ΔP is ΔP1, as shown in FIG. 8, the light amount S1 or the light emission period T1 corresponding to the power generation change amount ΔP1 is determined. In addition, the control part 20 which performs step S14 is corresponded to the "light emission pattern determination means" of this invention.

  Next, in step S <b> 15, a light emission instruction signal instructing light emission of the light emitting unit 40 with the determined light emission pattern is output to the drive unit 30. The drive unit 30 receives the light emission instruction signal and generates a drive signal corresponding to the light emission pattern instructed by the light emission instruction signal. At this time, as described above, the drive unit 30 generates a drive signal based on the power generated by the solar battery 10, that is, the power generated by the headlight light L1 from the rear vehicle 200. And based on the drive signal, the light emission part 40 is light-emitted. As a result, the light emitting unit 40 emits light with different light emission patterns depending on the degree of approach of the rear vehicle 200. Specifically, as the rear vehicle 200 approaches quickly, the light emitting unit 40 emits light brightly or at short intervals. Flashes. Therefore, it is possible to call attention to the rear vehicle 200 as it gets closer. Then, after the process of step S15, the process of the flowchart of FIG. The control unit 20 that executes step S15 corresponds to the “signal output means” of the present invention.

  As described above, according to the vehicular rear-end collision warning device 1 of this embodiment, (1) a sensor for determining day and night, (2) a sensor for determining the approach of the rear vehicle 200, and (3) driving Since the three functions of the power generator of the unit 30 are realized by the solar cell 10, the configuration can be simplified as compared with the conventional case.

(Modification)
Next, a modification of the vehicular rear-end collision warning device of the present invention will be described. In the above embodiment, the power of the drive unit 30 is secured only by the solar cell 10. This is because, as described above, it is considered that the power for driving the headlight can be secured by using a plurality of solar cells. However, there may be a case where sufficient power cannot be secured from the headlight light L1 because the headlight light L1 from the rear vehicle 200 is weak. Therefore, a vehicular rear-end collision warning device may be configured as shown in FIG. FIG. 9 is a block diagram illustrating a configuration of the vehicular rear-end collision warning device 2 according to a modification. In addition, the same code | symbol is attached | subjected to the components which are not changed with the vehicle rear-end collision warning device 1 of FIG.

  As shown in FIG. 9, the vehicular rear-end collision warning device 2 includes a sub battery 50 in addition to the configuration of FIG. The sub-battery 50 is a battery different from a main battery (not shown) that is a main power source of the host vehicle 100. Further, the sub-battery 50 is connected to the solar cell 10 so that the electric power generated by the solar cell 10 is charged. Further, the sub battery 50 is connected to the drive unit 30, and the charging power of the sub battery 50 is supplied to the drive unit 30. Thereby, for example, the power generated by the solar cell 10 in the daytime can be charged in the sub-battery 50. When driving the drive unit 30 at night, the drive unit 30 can be driven by the charging power of the sub battery 50 in addition to the power generated by the headlight light L1 of the rear vehicle 200. Therefore, even if the headlight light L1 of the rear vehicle 200 is weak, the light emitting unit 40 can emit light.

  The vehicular rear-end collision warning device according to the present invention is not limited to the above-described embodiment, and can be modified without departing from the scope of the claims. For example, in the above embodiment, it is determined whether or not the rear vehicle is approaching based on the power generation change amount ΔP. However, it is simply determined whether or not the rear vehicle is approaching at the distance between the host vehicle and the host vehicle. If so, the determination may be made based on the power generation amount P. That is, as shown in FIG. 5 (a), since the power generation amount P2 when the vehicle approaches is larger than the power generation amount P1 at the normal time, by setting a threshold between these power generation amounts P1 and P2, It is possible to determine whether the vehicle is approaching or the vehicle is approaching.

  Moreover, in the said embodiment, although the light quantity S and the light emission period T were varied as the light emission pattern of the light emission part 40, it is not restricted to this, For example, you may vary a light emission color. In this case, for example, a plurality of light emitting units having different emission colors are provided, and the light emitting units to emit light are changed according to the approaching degree of the rear vehicle.

DESCRIPTION OF SYMBOLS 1, 2 Vehicle rear-end collision warning device 10 Solar cell 20 Control part 30 Drive part 40 Light emission part 50 Sub battery 100 Own vehicle 111 Rear part side surface 200 Rear vehicle L1 Headlight light

Claims (6)

A light emitting unit provided in the host vehicle and emitting light toward the rear of the host vehicle;
A solar cell that is provided at a position where the light emitted from the vehicle behind the host vehicle can be received, and that generates power by the received light;
Based on the amount of power generated by the solar cell, an approach determining means for determining whether or not a rear vehicle is approaching the host vehicle,
When the approach determining means determines that the rear vehicle is approaching, a signal output means for outputting a light emission instruction signal instructing light emission of the light emitting unit;
Drive means for receiving the light emission instruction signal output from the signal output means and causing the light emitting unit to emit light by the power generated by the solar cell based on the reception of the light emission instruction signal;
A change amount calculating means for calculating a power generation change amount indicating a time change of the power generation amount generated by the solar cell;
The approach determination means determines whether or not a rear vehicle is approaching the host vehicle based on the power generation change amount calculated by the change amount calculation means . Based on the amount of power generated by the solar cell, it comprises day / night judgment means for judging whether it is currently nighttime or daytime,
2. The vehicular rear-end collision warning device according to claim 1, wherein when the day / night determination unit determines that it is currently daytime, the light emitting unit does not emit light. When the approach determining means determines that a vehicle behind is approaching, a light emission pattern determining means for determining a light emission pattern when the light emitting unit is caused to emit light and differing according to the power generation change amount With
The signal output means outputs a signal instructing light emission in the light emission pattern determined by the light emission pattern determination means as the light emission instruction signal,
3. The vehicular rear-end collision warning device according to claim 1 , wherein the driving unit causes the light emitting unit to emit light with the light emission pattern based on the light emission instruction signal instructing light emission with the light emission pattern. . 4. The vehicular rear-end collision warning device according to claim 3, wherein the light emission pattern determination unit determines a light emission pattern in which a light amount when the light emission is increased as the power generation change amount is larger as the light emission pattern . 5. The vehicular rear-end collision warning according to claim 3 , wherein the light emission pattern determination unit determines a light emission pattern that blinks so that a light emission cycle becomes shorter as the power generation change amount is larger. apparatus. A battery for charging the power generated by the solar cell while the driving means does not cause the light emitting unit to emit light;
It said drive means, in addition to the power which the solar cell is generating, for a vehicle according to claim 1, characterized in that for light emitting the light emitting portion by the charging electric power charged in the battery Rear-end collision warning device.

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