JP-7857317-B2 - Vehicle headlights

JP7857317B2JP 7857317 B2JP7857317 B2JP 7857317B2JP-7857317-B2

Inventors

土屋俊幸
松浦秀治

Assignees

株式会社小糸製作所

Dates

Publication Date: 20260512
Application Date: 20221122
Priority Date: 20211124

Claims (6)

A first light source unit emits a first light that forms the low beam light distribution pattern in front of the vehicle, A second light source unit emits second light that is added to the low beam light distribution pattern to form an additional light distribution pattern that forms the high beam light distribution pattern, Control unit and Equipped with, The headlight for a vehicle is characterized in that, when the control unit performs temperature derating on the second light source based on the temperature of the second light source while the high beam light distribution pattern is being formed, it moves at least the upper edge of the low beam light distribution pattern upward.
The vehicle headlight according to claim 1, characterized in that when the control unit performs the temperature derating on the second light source, it moves the upper edge of the low beam light distribution pattern upward before performing the temperature derating.
The vehicle headlight according to claim 1 or 2, characterized in that when the control unit performs the temperature derating on the second light source, it increases the amount of movement of the upper edge of the light distribution pattern of the low beam according to the vehicle's travel speed.
The vehicle headlight according to claim 1 or 2, characterized in that when the control unit performs the temperature derating on the second light source, it moves at least the upper edge of the additional light distribution pattern upward.
The vehicle headlight according to claim 1 or 2, characterized in that when the control unit performs the temperature derating on the second light source, it moves the lower edge of the additional light distribution pattern upward by a smaller amount than the upper edge of the low beam light distribution pattern.
The vehicle headlight according to claim 1 or 2, characterized in that when the control unit performs the temperature derating on the second light source, it moves the lower edge of the additional light distribution pattern upward after the movement of the upper edge of the low beam light distribution pattern.

Description

This invention relates to a vehicle headlight. Vehicle headlights may include a light-emitting unit, such as an LED (Light Emitting Diode), and a circuit board on which the light-emitting unit is mounted. In such vehicle headlights, if the temperature of the light source unit exceeds a predetermined value, the duty cycle of the light-emitting unit may be reduced according to that temperature. Reducing the duty cycle reduces the amount of heat generated from the light-emitting unit, thus protecting the light-emitting unit from heat. This control of the duty cycle is called temperature derating, and a lighting device that performs temperature derating is disclosed in Patent Document 1 below. Japanese Patent Publication No. 2018-134981 In vehicle headlights, the high beam light distribution pattern is sometimes formed by the low beam light distribution pattern and an additional light distribution pattern added to the low beam light distribution pattern. The additional light distribution pattern tends to be darker at the upper and lower edges than at the center. If temperature derating is performed on the light-emitting part that emits the light forming the additional light distribution pattern while the high beam light distribution pattern is being formed, the center of the additional light distribution pattern becomes darker, and consequently, the lower edge of the additional light distribution pattern also becomes darker. This darkening of the additional light distribution pattern can reduce forward visibility. Therefore, the present invention aims to provide a vehicle headlight that can suppress the decrease in forward visibility when temperature derating is performed. To achieve the above objective, the vehicle headlight of the present invention comprises a first light source unit that emits first light to form a low beam light distribution pattern toward the front of the vehicle, a second light source unit that emits second light to form an additional light distribution pattern which is added to the low beam light distribution pattern to form a high beam light distribution pattern, and a control unit, wherein when the control unit performs temperature derating on the second light source unit based on the temperature of the second light source unit while the high beam light distribution pattern is being formed, it moves at least the upper edge of the low beam light distribution pattern upward. According to the above configuration, by moving the upper edge of the low beam's light distribution pattern upward, the upper edge of the low beam's light distribution pattern can brighten the lower edge of the additional light distribution pattern, which would otherwise be darkened by temperature derating. Therefore, a decrease in forward visibility can be suppressed. Furthermore, when the control unit performs the temperature derating on the second light source, it may move the upper edge of the low beam's light distribution pattern upward before performing the temperature derating. Conversely to the above configuration, if the upper edge of the low beam's light distribution pattern moves upward after temperature derating, two peaks may be formed in the intensity distribution of the high beam's light distribution pattern between the time of temperature derating and the time the upper edge of the low beam's light distribution pattern moves, due to the region with the highest intensity in the low beam's light distribution pattern and the region with the highest intensity in the additional light distribution pattern. When two peaks are formed, the region corresponding to the intensity dip located between the two peaks in the high beam's light distribution pattern tends to be darker than the regions on either side of the dip. If the region corresponding to the dip is located in the driver's line of sight, the driver may perceive that the area in their line of sight is darker than elsewhere, potentially reducing visibility. However, in the above configuration, since the upper edge of the low beam's light distribution pattern moves upward before temperature derating, the formation of a dip between the two peaks can be suppressed. Therefore, the reduction in visibility can be suppressed compared to the case where a dip is formed. Furthermore, when the control unit performs the temperature derating on the second light source, it may increase the amount of movement of the upper edge of the low beam's light distribution pattern according to the vehicle's travel speed. According to the above configuration, when the vehicle is traveling at high speed, the amount of movement of the upper end increases compared to when the vehicle is traveling at low speed, allowing the driver to see far ahead in a brighter view, potentially improving safety. Furthermore, when the control unit performs the temperature derating on the second light source, it may move at least the upper edge of the additional light distribution pattern upward. Whe