Abstract: A solid state light apparatus ideally suited for use in traffic control signals provided with optical feedback to achieve a constant light output, preferably by detecting back-scattered light from a diffuser centered above an LED array. The control logic allows for the LEDs to be individually driven, and having their drive characteristics changed over time to ensure a uniform beam of light is generated at an intensity meeting DOT standards, across the life of the device. The optical feedback also establishes the uniform beam intensity level as a function of sensed ambient light to discern day and night operation.

Abstract: A solid state light apparatus with a solar shielded heatsink ideally suited for traffic controls. The current state of the art solid state traffic signals utilize LED arrays encased in the existing plastic or metal traffic signal cases which were originally design for incandescent bulbs. Unlike LED's, incandescent bulbs are insensitive to high temperatures. As a result heat will build up on the LED die because of the limitations of the existing incandescent case design. The apparatus mounts the LED array directly to a louvered external heatsink in contact with the air outside of the traffic signal case facilitating the dissipation of heat generated from the LED die and from the sunlight shining on the case. For 25% of all signals (those facing west), during the late afternoon sunset the lensing system will focused the sunlight directly on the LED die raising the die temperature an additional 20 C.

Abstract: An area array of LEDs (46) encompassed within a single reflector housing (302) which can be selectively masked (320) to mechanically adjust the viewing angle of the light generated therefrom. The area array of LEDs are disposed within a cavity of a housing forming a trough which is covered by a holographic diffuser. A mask is selectively positionable and attached to the top of the diffuser to mask a portion of the LEDs, and may be secured in position using Velcro® material. By selectively masking the portions of LEDs, the beam angle from the lens can be selectively adjusted. Multiple colored LEDs are provided such that more than one color light beam can be generated from the single signal housing. The mask selectively adjusts both the angle and shape of the beam ultimately transmitted by the associated Fresnel lens.

Abstract: A split-phase pedestrian head traffic signal having directional light beams and a variable beamwidth. The pedestrian heads are selectively controlled such that half-way through a control cycle, a pedestrian half-way across the street may see a “walk” signal, while a pedestrian still at the far side of the street will actually see a “stop hand” signal. A pair of pedestrian heads each having a split-phase facilitate the beam steering such that the appropriate walk or stop hand signal are viewed by the pedestrian at the appropriate location. An area array of LEDs in combination with a Fresnel lens is selectively controlled such that light generated from the respective head can be directed toward different positions of the street for informing pedestrians at different locations attempting to cross the street.

Abstract: A stacked logic circuit (20) having a serially connected first logic circuit (12) operating off a first voltage differential and providing in series with a second logic circuit (14) operating off a second voltage differential. The second logic circuit being in series with the first logic circuit recycles the current of the first logic circuit. A low impedance shunt circuit (30) is provided in parallel with the first logic circuit (12) and shunts additional current required of and to the second logic circuit (14) from the single voltage source (VCC). A Zener diode (Z1) shunts current from the first logic circuit not required by the second logic circuit via a shunt node (N). The shunt circuit (30) includes a Darlington pair of transistors or a three terminal voltage regulator (42) and only shunts a very small amount of current to ground. The stacked logic circuit of the present invention efficiently uses current drawn by the single voltage source to reduce power consumption.

Abstract: A solid state light apparatus generating a homogenous light beam ideally suited for use in traffic control signals. A solid state light source comprises an area array of LEDs uniformly illuminating a light diffuser to achieve the homogenous light beam. In one embodiment, a plurality of light guides direct light from each LED such that each LED illuminates the same square area of the light diffuser. In another embodiment, the LEDs are provided with lenses having a different radius of curvature such that a convex bottom surface of the light diffuser is uniformly illuminated. The LEDs proximate the center of the array have a smaller radius of curvature than the outer LEDs having flatter lenses.

Abstract: A solid state light apparatus ideally suited for use in traffic control signals having a Self Diagnostic/Predictive Failure Analysis (SD/PFA) function facilitating a real time status of the signal as well as prediction of failure years in advance of the actual failure. Unlike incandescent signals, all LED based signals degrade over time until they are no longer in DOT light output specifications. Current state of the art solid state signals must be periodically monitored to see if the light output is in specification. This is done by having DOT or contracted personnel ascend in a bucket truck and place a light meter on the signal typically on an annual basis. A signal system with SD/PFA coupled with a modem or RF link provides real time data, without the use of a bucket truck on the status of the signal. The system also provides data which allows the determination via an algorithm of when the signal will go below light output specifications in the future.

Abstract: A solid state light apparatus suited for use in traffic control signals and having a unitary transparent cover generating a homogenous light beam. A solid state light source comprises an area array of LEDs uniformly illuminating a light diffuser to achieve the homogenous light beam. The unitary cover has a lens defined at an inner portion thereof, and an outer portion encompassing the lens adapted to sealingly secure to the apparatus housing. The lens is continuous with the outer portion such that water and other environmental elements can not penetrate into the housing electronics.

Abstract: A solid state traffic control signal adapted to facilitate light alignment and viewing angles during installation. The traffic control signal includes a video camera or a detachable optical sighting system with a grid representing the various viewing angles of individual LED's for quick alignment and viewing angle programming. This system greatly reduces the amount of trial-and-error and multi-man requirements for installation.

Abstract: A modular solid state light apparatus ideally suited for use in traffic control signals. Current state of the art solid state signals are sealed units which fit into existing signal cases once the primary lens and incandescent bulb, and sometimes even the incandescent reflector, are removed. The modular system replaces the entire case with a custom case designed to accommodate current and future features at approximately {fraction (1/10)} the present cost of a stand alone system. These upgrade features include but are not limited to vehicle preemption, electronically steerable beam, predictive failure analysis, various power supplies, LED arrays in various colors, optical alignment tools used for installation, video camera, in car Telematics, video loop detection, red light running, various communications links, infrared sensors to sense people and vehicles under fog, rain smoke, and other adverse visual conditions, chemical ‘sniffers’, automobile emission monitoring, and adaptive control.