Patent Application
20080100470
The present invention relates in general to a lamp for a motor vehicle and more particularly to an external marker or indicator lamp such as a side turn signal indicator lamp.
Motor vehicles typically have several marker and indicator lamps. These lamps enhance vehicle safety by providing information to other drivers. For example, running lamps make a vehicle more visible at night; brake lamps indicate that a vehicle may be slowing down or stopping; and turn signals indicate that a vehicle is about to turn or move in a new direction.
Marker and indicator lamps can only provide information to other drivers if the other driver sees the lamps. First, the marker or indicator lamps must be in the driver's field of view. Second the marker or indicator lamps must be noticed by the driver. For example, when a driver is alongside another vehicle the turn signal lamps on the front and rear of the other vehicle may not be visible to the driver. Even if one of the turn signal lamps is in the driver's field of view, it may not be noticed, because the light from the lamp is directed away from the driver or the indicator lamp is not be large enough to attract the driver's attention.
As a result, the driver may not be alerted when the other vehicle is about to change lanes or make a turn. This is particularly problematic for large vehicles such as tractor trailers or buses because the driver of a car alongside the large vehicle might not see a turn signal on the large vehicle, and the driver of the large vehicle may not see the car alongside.
The objects and advantages of the present invention are provided by a marker or indicator lamp in which light is generated by a plurality of light emitting diodes (LEDs). Some of the LEDs are oriented to optimize the visibility of the LEDS when the lamp is mounted on a vehicle. Other LEDs are oriented to direct light into one or more light guides configured to illuminate a large area.
These and other objects and advantages of the present invention will be understood upon consideration of the detailed description taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts, and in which:
The principles of the present invention relate to the design and use of marker and indicator lights for motor vehicles such as boats, cars, trucks, aircraft, and the like. These principles are described herein with reference to an illustrative side turn signal. A side turn signal is defined by the Society of Automotive Engineers (SAE) in specification SAE J914 as a lighting device normally mounted on the side of a vehicle at or near the front, and used as part of the turn signal system to indicate a change in direction by means of a flashing warning signal on the side toward which the vehicle operator intends to turn or maneuver. One skilled in the art will understand that other marker and/or indicator lights may be designed and used in accordance with the principles of the present invention.
Generally, side turn signal 16 is designed to warn drivers in the zone indicated by dashed lines 18 in
The construction of illustrative side turn signal 16 is shown in more detail in
Housing 36 includes mounting tabs 42 for attaching side turn signal 16 to motor vehicle 10. As shown in
Typical marker and indicator lamps use incandescent bulbs which are relatively fragile, and prone to burn out or break. In contrast, Light Emitting Diodes (LEDs) are more robust, turn on faster, and use less current than incandescent bulbs. As a result, LEDs are overtaking incandescent bulbs in some applications. Due to recent advances in LED technologies, a single high intensity LED is capable of fulfilling the requirements of SAE J914. In accordance with the principles of the present invention, side turn signal 16 is illuminated by high intensity LEDs. As shown in
Circuit board 32 is positioned in rear housing 36 so that LEDs 52 are located adjacent to and point out of openings 46, and LEDs 55 are located adjacent to and point out of openings 48. Rear cover 34 includes posts or stand-offs 26 designed to position circuit board 32 within housing 36. Preferably, rear cover 34 includes clips 28 to securely hold circuit board 32 on posts 26 and clips 30 designed to mate with corresponding portions of rear housing 36. Clips 28 and 30 enable the components to be assembled without tools.
LEDs are not without drawbacks. An incandescent bulb provides omnidirectional illumination, whereas the illumination provided by an LED is more directional. The illumination provided by an LED is primarily directed in an elliptical cone oriented along the optical axis of the LED. Therefore, an LED appears much brighter when viewed from a position near the optical axis than when viewed from an off-axis position.
In accordance with the principles of the present invention, rear cover 34, circuit board 32, and housing 36 are designed so that when side turn signal 16 is mounted on a motor vehicle LEDs 52 are oriented so that their illumination is directed toward the area in which some one viewing the side turn signal is likely to be. Preferably, this is done by orienting the optical axis of the LED toward the target area. Alternatively, a portion of the cone of illumination provided by the LEDs is directed toward the target area. For example, in
To further increase the visibility, side turn signal 16 is designed to have an larger illuminated or projected area than the area of LEDs 52 alone. This is provided by light guides or light pipes 38 in combination with LEDs 55 and housing 36. Light guides are optical structures made of substantially transparent materials in which light coupled into the structure is guided throughout the body of the structure via internal reflection. Out coupling elements reflect some of the out of the light guide. Preferably, light guides 38 are plastic bars or rods disposed in housing 36 so that they are illuminated by LEDs 55. For instance, one end of light guides 38 includes tabs 39 that fit into corresponding slots 47 in housing 36. The other end of light guides 38 is shaped to fit opening 48. As described above, rear cover 34 holds circuit board 32 so that LEDs 55 are adjacent to and directed toward openings 48. Thus, light guides 38 are illuminated by LEDs 55.
The light from LEDs 55 is guided throughout light guides 38 by internal reflection and/or refraction. A rear surface of light guides 38 is faceted, corrugated, or otherwise textured to form out coupling elements to direct the internally reflected light light from LEDs 55 outward through lens 40. A portion of light guides 38 may be metalized. To further enhance the visibility of side turn signal 16, housing 36 includes reflector 58 behind light guides 38. Reflector 58 directs light exiting from the sides of light guides 38 outward though lens 40. Preferably, reflector 58 is a suitably shaped and metalized portion of housing 36, although it may be a separate component.
Thus, an improved marker or indicator lamp and methods of making and using same have been provided. One skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which are presented for purposes of illustration and not of limitation, and that the present invention is limited only by the claims which follow.
