Abstract:
A control unit (2) of a remote control receiver sets the forward or reverse direction operating mode of the photodiode (1) as a function of the useful signal level of its output signal, and to be precise, during standby, the photovoltaic operating mode (forward mode), since in this mode no external bias current is required. If the useful signal level of the photodiode (1) exceeds a predefined threshold, the reverse mode is set, and this brings with it a higher sensitivity. A series circuit (A) of a number of identical photodiodes DA1... DAn in the forward mode allows the realization of a controlled current source (6) having a transistor (T), since the permissible diode voltage (Ud) of the overall arrangement may have n times the value of the operating voltage of an individual photodiode. Thus at the same time the voltage across the individual diodes can be set to a very low value and a favorable operating range for the current source can be set. The possible sensitivity of the receiver module having diodes in this operating mode can thereby be considerably increased.
Abstract:
The present invention relates to an LED lamp (1) adapted for operation with an alternating current. The LED retrofit lamp (1) comprises a LED unit (7, 7', 7'', 7''') and a compensation circuit with a controllable switching device (9, 9'), connected parallel to said LED unit (7, 7', 7'', 7''') to provide an alternate current path. A control unit (10, 10', 10'') is adapted to control said switching device (9, 9') in a compensation mode in which said switching device (9, 9') is set to the conducting state for the duration of a shunt period in each half cycle of the alternating current to allow adapting the power/current of the inventive LED lamp (1), so that a versatile and optimized operation of the lamp (1) is possible.
Abstract:
A disconnecting circuit (SW1, RS, COM, CO) for a power converter (CON) supplies power to a load device (LO; 2). The disconnecting circuit (SW1, RS, COM, CO) comprises a switch (SW1) arranged in series with the power converter (CON) to disconnect a supply of power to the load device (LO, 2). A sense circuit (RS) supplies a sensed value indicating an operation mode of the load device (LO, 2). A controller (CO, COM) receives the sensed value to control the switch (SW1) to disconnect the supply of the power from the load device (LO, 2) when the sensed value drops below a reference level indicating a standby mode of the load device (LO, 2).
Abstract:
The present invention relates to a device and method for controlling the color point of an LED light source (50). Color point control is a most interesting product feature both for white and colored LED light sources. In known methods for the color control of RGB LED light sources use is made of flux and color sensors. However, there are difficulties with respect to sensing quickly changing ambient light, deeply dimmed colors, coordinating the measurements with the switching of the LEDs, and controlling the color in LED light units comprising a number of independent LED lamps, e.g. segmented wall washers and LCD backlights. It is proposed according to the present invention to control the color of the LED light source (50), using a model-based feed forward approach. Factors relating the parameters controlling the LED currents to the brightness for the different colors (and segments) are stored and used for open loop control. A slow-running procedure continuously measures and updates these factors. Whilst the measurements are e.g. synchronized with the PWM, the procedure itself can run considerably slower and updates the factors asynchronously.
Abstract:
The present invention relates to a supply circuit for supplying an output signal to a load, in particular for supplying a DC output current (Io) to an electronic lamp unit (LE), comprising: an input circuit (1) comprising input terminals (10, 11) for receiving an input supply signal (Us), a transistor H-bridge circuit (12) having separately controllable transistors (T1, T2, T3, T4) for converting said input supply signal (Us) into a pulse signal (Ul), and an inductance circuit (Li) coupled between an input terminal (10, 11) and a H- bridge circuit input terminal (121), an output circuit (2) comprising a resonance circuit (Cs, Ls), a transformer (Tr) and an output rectifier circuit (B2), in particular a full bridge rectifier circuit, for converting said pulse signal (Ul) into said output signal (Io), and output terminals (20, 21) for outputting said output signal (Io) to said load (LE), a control circuit (3) for generating control signals (si, s2) for controlling the transistors (T1, T2, T3, T4) of said transistor H-bridge circuit (12).
Abstract:
Adaptation circuits (3) for controlling conversion circuits (1-2) for converting input signals into pulse signals and for converting pulse signals into output signals are provided with generators (30) for generating control signals in dependence of input signals and (basic idea) with compensation circuits (71-72,81-83) for adjusting the generators (30) in dependence of input information for increasing a stability of output signals, to be able to supply relatively constant output signals to loads (6). The adaptation circuits (3) may reduce dependencies between input signals and output signals and may generate control signals independently from output signals to avoid feedback loops. Input signals may be input voltages, output signals may be output currents, and input information may comprise input voltages and nominal input voltages for compensating for variations of input voltages or may comprise nominal output voltages and input currents proportional to output voltages for compensating for variations of output voltages.
Abstract:
Operating a lighting device by acquiring a target brightness level of at least one solid-state lighting unit, and determining a reference driving current amplitude for obtaining the target brightness level. If the reference driving current amplitude is below an optimum driving current amplitude, the solid-state lighting unit is operated at the optimum driving current amplitude, which is pulse-width modulated to obtain the target brightness level.
Abstract:
The invention relates to a lighting device that may particularly be used as an LCD backlight and that comprises an array of light emitters (11.1, 11.2) which are optionally separated by optical barriers (13). The light emitters (11.1, 11.2) may particularly be realized by groups of LEDs (12.1, 12.2) of different colors, for example red, green and blue. Local control units (16), driving units (15.1, 15.2), and sensor units (14) are provided to control the individual light output of the light emitters, wherein at least one of these components is shared by two or more light emitters (11.1, 11.2).