Smart Traffic Light Module
From PDI
Contents |
Preface
Proliferation of lighting devices alternative to incandescent light bulbs, such as high brightness LEDs, brought their prices down enough to allow their use in such devices as traffic lights: [1], [2], etc.
Compared to a traditional incandescent bulb-based traffic light, such arrangement provides increased brightness of the signal, while severely reducing the energy usage.
Problems with existing designs
While increased brightness of the signal certainly provides benefits in bright daylight, during the nighttime, it irritates the eyes of the drivers as they drive next to such traffic light, and in rare cases, may even blind the driver as he enters the intersection
Claims
This invention describes:
- the LED based traffic signal module, in which individual LEDs are placed within a circular shape of the module in concentric rings, or in checkerboard, hexagonal or some other regular pattern;
- the LED based traffic signal module as claimed in claim 1, in which individual LEDs comprising the module are electrically connected in two or more groups, provided that the physical locations of LEDs belonging to each electrically interconnected group are evenly distributed over the face of the module;
- the LED based traffic signal module as claimed in claim 2, in which each group of electrically interconnected LEDs can be switched on and off individually;
- the LED based traffic signal module as claimed in claim 3, which is equipped with a rearward-facing ambient light detector, such as the said detector registers the ambient light conditions in the direction opposite to the direction of light emitted by LEDs comprising the module, and thus in the same direction the gaze of the motorist observing the module would be directed, as to ensure that special light conditions such as the presence of a bright light source in the direction of motorist's sight are properly detected;
- the LED based traffic signal module as claimed in claim 4, which is equipped with a microelectronic device capable of estimating the brightness of the ambient light visible to the oncoming motorist through the use of above mentioned light sensor, and adjusting the brightness of the traffic signal light module by turning on a specific number of electrically interconnected LED groups as to provide a sufficient and comfortable level of contrast between the ambient light and the light emitted by the signal, as judged by the oncoming motorist.
- the LED based traffic signal module claimed in claim 5, in which the aforementioned microelectronic device alternates the order in which the LED groups of equal total brightness are switched on and off, as to ensure that the "on"-time of each group remains the same throughout the life of the module, as to average out the wear.
- the LED based traffic signal module, in which there are circuits for dimming the LEDs, since it recently has become much easier to dim LEDs, either individually, in groups or all at once, so that you not have to switch some LEDs off and keep other LEDs on to decrease the emitted light, making the device less complex;
In layman's terms
The LED traffic light module consist of dozens of LEDs. The proposal is not to light up every single one at night, but switch off most of them, leaving only about half of them on at dawn/dusk, and 20-30% at night. Alternatively all the LEDs would be dimmed instead, keeping all the LEDs lit but at with lower brightness levels. To further improve the safety, the ambient light sensor would simulate the eye of the driver in determining when to switch the extra LEDs off or dim the LEDs more, and will also crank up the light output when the sun is straight behind the traffic light, so the light can still be seen in such condition.
Benefits of the proposed design
- More comfortable driving conditions (not burning the driver's eyes at night)
- Further reduced electricity use at night;
- Longer LED life as they're not lit all the time;
