Aspects of the present application relate to a bypass switch for a lamp, such as a surgical or diagnostic lamp. When activated, the bypass switch may act to allow electric power to bypass elements of a control board so that the electric power is provided to the plurality of lamp elements.

A first photosensor is sensitive to the wavelength of excitation light, insensitive to the wavelength of fluorescent light, and receives a portion of the output light to generate a first current corresponding to the amount of light received. A second photosensor is sensitive to the fluorescent light wavelength, insensitive to excitation light wavelength, and receives a portion of the output light to generate a second current corresponding to the received light amount. A first current/voltage conversion circuit outputs a first detection voltage corresponding to the voltage drop across a first resistor. A second current/voltage conversion circuit outputs a second detection voltage corresponding to the voltage drop across a second resistor. If (i) a relation between the magnitudes of the first detection voltage and the second detection voltage has reversed, or (ii) if the first detection voltage deviates from a normal voltage range, a judgment unit asserts an abnormality detection signal.

An airfield runway lamp controller is described herein. One airfield runway lamp controller includes a current sense transformer configured to detect a failure of a light source of an airfield runway lamp, and an alternating current (AC) switch configured to shunt the light source of the airfield runway lamp upon the current sense transformer detecting a failure of the light source.

A lighting circuit utilizes a buck converter that supplies a drive current to a light source and is feedback-controlled so that the drive current comes close to a target current. An open-circuit detection circuit compares a potential difference between and input voltage and an output voltage of the buck converter with a threshold voltage.

A luminaire includes a microcontroller and program logic that calculates the operational age of a light engine that includes a plurality of light emitting diodes connected in series. The program logic uses changes in transition voltage to calculate the operational age of a light engine. Changes in forward voltage across the light engine are used to detect sudden catastrophic failure of individual light emitting diodes. In response to the sudden catastrophic failure of one of the light emitting diodes, the program logic adjusts the power provided to the light engine based on the calculated operational age of the light engine. For example, the operational age of the light engine may be compared with a warrantied lifespan, and the power may be adjusted to increase the likelihood of compliance with the warranty.

A lighting system waveform shaping circuit (WSC) includes a line voltage input, a line voltage output connectable to an input voltage port of a control unit, a neutral line input connectable to a neutral line of a voltage power source, and the WSC including an impedance matching network (IMN) configured to alter an input impedance of the lighting control circuit. In one embodiment, the IMN can include a resistor in series with the line voltage input, and an actively-controlled bypass switch in parallel with the resistor. In another embodiment, the IMN can include respective ferrite chokes surrounding the input and the output voltage lines, a capacitor between the line voltage input and the neutral line input, a capacitor between the neutral line input and a protected earth ground, and a resistor in series between the neutral line input and the lighting control unit neutral line input port.

A lighting apparatus with an image-projecting function that is convenient for a user can be provided. The lighting apparatus includes: an illuminating unit that emits illumination light; and a projection-type image display unit that projects an image. The projection-type image display unit is configured so that a setting menu screen settable about an image displayed by the projection-type image display unit can be displayed.

A system and method provide fail-safe operation of a lighting system. A lighting level detector is used to obtain a baseline lighting level for a low-intensity light. If the detector measures less than the baseline level when an occupancy sensor determines the space is unoccupied, a high-intensity light is energized and an indication is provided to a user that the low-intensity light has failed. A method provides daylighting operation of a lighting system. An occupancy sensor can have Wi-Fi functionality to enable remote configuration of the sensor. A line voltage occupancy sensor can include an interface with low voltage devices. An occupancy sensor can include an integral interface to enable an external control system to override the sensor's normal logic under emergency conditions. An occupancy sensor can include an active temperature compensation feature. An occupancy sensor can also incorporate an automatically adjustable coverage area.

An anti-flicker and anti-glow switchable load apparatus to be installed in the light socket of a commonly powered electronic switching device, such as a motion activated light switch. An energy efficient light bulb or lamp, such as a cathode fluorescent lamp or light emitting diode is then electrically connected to the apparatus. A first embodiment of the present invention includes a switchable light source, a switchable load, a controller, and a voltage sensor. When the present invention in the first embodiment detects a higher voltage, thus indicating the lamp has been switched from the off state to the on state, the switchable load is disconnected, and the current is re-routed to pass through the energy efficient lamp.

Provided is a technique that facilitates control of a navigation light which uses light-emitting diodes for a light source. This navigation light control system is provided with: a navigation light that has a light source for which a light-emitting diode is used; a power supply unit that supplies power to the navigation light; and a control device that controls lighting of the navigation light, wherein the control device is provided with a light source circuit that supplies the power received from the power supply unit to the light source, and a determination unit that determines failure of the light source on the basis of the value of the current flowing through a resistor connected to the light source circuit.