摘要:
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.
摘要:
Bleeder circuits (1) for combinations of phase cutting dimmers (2) and light emitting diode circuits (3) comprise active circuitry (4) to increase a number of options. The active circuitry (4) may comprise a current limiting circuit (5) for limiting a current flowing through the bleeder circuit (1). The active circuitry (4) may comprise a voltage detecting circuit (6) for activating or deactivating, in response to a detection result, the current limiting circuit (5) and may comprise control circuitry such as a micro processor circuit (7) for controlling the current limiting circuit (5) and may comprise a control circuit (9) for using information derived from a current flowing through the light emitting diode circuit (3) for controlling the current limiting circuit (5) and for controlling at least a part of the light emitting diode circuit (3) that comprises anti-parallel light emitting diodes (31-32) or serial and/or parallel light emitting diodes (33-36).
摘要:
The invention relates to an image projector with a High-Intensity-Discharge HID lamp (112) and a method of operating it. Such lamps have the disadvantage that their voltaic arc jumps back and forth between different positions at unforeseeable times during operation. This so-called arc jumping has the effect of changing the brightness, i.e. the overall brightness and/or the brightness distribution of the light emitted by the HID lamp (112). For the viewer of an image projected with such a projector, this effect appears as a jolt of this projected image. To avoid such effects for the viewer, it is first proposed according to the invention that changes in the brightness of the light in the image projector's beam path are detected. As soon as a change in brightness caused by an arc jump has been detected, this brightness is reset to a brightness detected at a moment t-2 before the arc jump, in order subsequently to convert it during a predetermined time interval T to the brightness resulting from the arc jump. This resetting must occur so soon after the arc jump, and the conversion so slowly, that the changes in the brightness of the light incident on a picture screen device (118) resulting from the arc jump, the reset, and the conversion are not perceptible to the human eye.
摘要:
A circuit and a method for operation of a gas discharge lamp includes a switching transformer having a switch, a converter, inductor and a controller in a control loop for measuring a lamp voltage and setting a desired power. The switching transformer further includes a second control loop used for adjusting the switching transformer to individual lamp conditions.
摘要:
A projection system for image reproduction includes at least one lamp and sensor for generating a sensor signal for monitoring changes in the luminous flux generated by the lamp and for compensating these changes through a suitable control of the image reproduction. The projection system further includes a device for eliminating substantially periodic interference components from the sensor signal generated by the sensor. These interference components may be generated by an optical component such as a color modulator of the projection system. The projection system provides substantially interference-free compensation of fluctuations in the luminous flux generated by the lamp, for example, owing to an unstable arc discharge. Further, the positioning of the sensor in the projection system may not be critical.
摘要:
The invention relates to a method for operating a discharge lamp 11 including two electrodes 12,13. The method comprises applying to the electrodes an alternating current ILamp. In order to improve the performance of the lamp and to increase the life time of the lamp, it is proposed that the alternating current has a direct current component DC for compensating a temperature difference between the two electrodes. The direct current component is selected more specifically such that a first electrode, which is expected to have a lower temperature than the second electrode, functions as anode for the direct current component, while the second electrode functions as cathode for the direct current component. The invention relates equally to an electronic circuit and to a software program for operating a discharge lamp correspondingly, as well as to a lighting system comprising a discharge lamp and means for operating this discharge lamp correspondingly.
摘要:
In the case of known switched-mode power supplies with integrated preconditioner, the control curves are largely congruent, but deviate from one another in low-load operation, whereby the unregulated intermediate circuit voltage increases. To improve efficiency in low-load operation, closed-loop control of the burst cycle is effected on the primary side of the voltage transformer. The intermediate circuit voltage is limited to a permissible limit value. The closed-loop control device in the switching stage taps the intermediate circuit voltage at a voltage divider which is arranged between the preconditioner functional unit and the switching stage. An assembly additionally monitors the output voltage, for example by means of an optocoupler. Burst mode comprises one or more burst cycles. A burst cycle is started when the intermediate circuit voltage reaches its limit value. At this time, the voltage transformer is switched off. A burst cycle ends when the output voltage reaches a minimum value. At this time at the latest, the voltage transformer is switched on again. Burst mode is terminated again either when the switched-mode power supply is again operated under normal load or when a maximum time has elapsed, measured from the start of burst mode.
摘要:
Driver circuits (1) for driving load circuits (2, 3) receive source signals from sources and provide feeding signals to the load circuits (2,3) and charging signals to capacitor circuits (21). These capacitor circuits (21) provide supporting signals to the load circuits (2, 3) in addition to the feeding signals. By providing the driver circuits (1) with control circuits (22) for controlling the supporting signals, the capacitor circuits (21) can become less bulky/costly and/or will limit the lifetime of the driver circuits (1) to a smaller extent. Further, these driver circuits (1) may get improved efficiencies. Said controlling may comprise controlling moments in time at which the supporting signals are offered to the load circuits (2, 3) or not, and/or may comprise controlling sizes of the supporting signals, and/or may be done in response to detection results from detectors (23) for detecting parameters of one or more signals. Said controlling may comprise switching via switches (24).
摘要:
Driver circuits (1) for driving load circuits (2) comprising first and second light circuits (21-22, 71-72) are in first/second modes for input voltages having first/second voltage amplitudes, the second voltage amplitudes being larger than the first voltage amplitudes. The first light circuits (21, 71) are on in the first and second modes. The second light circuits (22, 72) are off in the first modes and are on in the second modes. A control circuit (21, 71) in dependence of the modes to extend control. These currents may get smaller current amplitudes in higher modes. Light outputs of the first light circuit (21, 71) may get smaller in higher modes. A total light output of all light circuits (21-22, 71-72) may remain substantially constant during all modes.
摘要:
An image projection method comprises the steps of a) obtaining an image pixel array for the image to be projected; b) obtaining a plurality of pixel allocation arrays for the image pixel array, whereby each pixel allocation array comprises occupied elements and vacant elements; c) generating a trigger pulse train for a laser light source according to a pixel allocation array, whereby a trigger pulse is generated for each occupied element; d) generating a modulation signal for the laser light source; e) switching the laser light source with the trigger pulse train and modulating the laser light source with the modulation signal to generate a laser light pulse sequence for a sub-frame image; f) and scanning the laser light pulse sequence to traverse the display; thereby, the steps c) to f) are carried out for each pixel allocation array so that the image appears on the display.