Abstract: The invention describes a method of shutting down a high pressure discharge lamp (1) in which a pair of electrodes (2) are disposed in an arc tube (3). This method comprises the steps of reducing the lamp power (PA) to a reduced operation level that enables the maintenance of an arc discharge between the electrodes (2) in a transition state from a lighting state to an extinguished state; driving the lamp (1) at the reduced operation level such that that the lamp (1) cools down; monitoring the lamp voltage (U) during this lamp power reduction process and during driving of the lamp (1) at the reduced operation level with regard to a defined discharge process stability criteria and increasing the lamp power (PA) if the discharge process stability criterion is not satisfied; completely shutting down the lamp power (PA) after sufficient duration to allow the lamp (1) to cool down to a state in which the gas pressure is such that the lamp (1) could be reignited shortly after being extinguished.

Abstract: The invention relates to a power supply circuit (10) and methods for supplying electrical power to at least one load output. The circuit comprises a main power supply unit (12) with a voltage input (14), a main switching element (26) and a reactive element (28). The switching element (26) is controllable to deliver an output voltage or current (I out). Output units (20a, 20b, 20c) with load outputs are connected to a main power supply unit (12). In order to drive loads connected to the load outputs, e.g. LEDs, OLEDs or laser diodes, with exact pulses, each output unit (20a, 20b, 20c) has a load switching element (38) to connect or disconnect the main power supply unit (12) to or from the load output. There are further provided switched capacitor units (34), each with a capacitor (C) and a capacitor switching element (40). The capacitor units may be operated such that the capacitors remain essentially charged at different voltage levels.

Abstract: In this method an arc-length control value, indicating the current length of a discharge arc of the gas-discharge lamp (1), is monitored and the lamp (1) is driven in a first operation mode (OMP) with a first current wave-shape when the arc-length control value indicates that the arc-length is higher than a switching threshold, which first current wave-shape is selected to result in a tip (31) growing on an electrode (30) of the lamp (1), and the lamp (1) is driven in a second operation mode (OMn) with a second current wave-shape when the arc-length control value indicates that the arc-length is lower than a switching threshold, which second current wave-shape is selected such that the tip (31) on the electrode (30) is at least partly melted back.

Abstract: The invention describes an image projection method for projecting an image (1) onto a display (2), which method comprises the steps of a) obtaining an image pixel array (A, A?) for the image to be projected; b) obtaining a plurality of pixel allocation arrays (21, 22, 31, 32, 33) for the image pixel array (A, A?), whereby each pixel allocation array (21, 22, 31, 32, 33) comprises occupied elements and vacant elements; c) generating a trigger pulse train (T2, T3) for a laser light source (LR, LG, LB) according to a pixel allocation array (21, 22, 31, 32, 33), whereby a trigger pulse is generated for each occupied element of the pixel allocation array (21, 22, 31, 32, 33); d) generating a modulation signal (M2, M2R, M2G, M2B, M3) for the laser light source (LR, LG, LB) on the basis of the image pixel array (A, A); e) switching the laser light source (LR, LG, LB) with the trigger pulse train (T2, T3) and modulating the laser light source (LR, LG, LB) with the modulation signal (M2, M2R, M2G, M2B, M3) to generate

Abstract: A description is given of a method and a circuit arrangement for operating a high-pressure gas discharge lamp with a lamp current superposed with first current pulses, in particular in a system for the time-sequential production of (primary) colors and possibly white segments, from which an image to be displayed is synthesized, in which, in order to change or correct color and/or brightness properties of the image, the first current pulses are adjusted with regard to their amplitude and/or temporal length and/or temporal position relative to the production of the colors and/or white segments. A description is also given of a projection system comprising such a circuit arrangement.

Abstract: Supply circuits for supplying voltage and current signals to light sources (6) comprise switches (22, 32, 42, 52) and controllers (21, 31, 41, 51) to control the switches (22, 32, 42, 52) for reducing values of frequency components of harmonic content of power spectra of the light sources (6). By switching one of the voltage and current signals or by switching signals that result in one of the voltage and current signals, the other one of the voltage and current signals can be adjusted. The power spectrum of the light source (6) may be a function of the voltage and current signals. By adjusting one of them, the power spectrum can be adjusted such that values of frequency components of the harmonic content of the power spectrum are reduced. As a result, visible flicker is reduced in the light originating from the light source (6) without the use of energy storage capacitors for reducing this visible flicker.

Abstract: A light source sequentially emits lights generated by at least three light emitting elements each emitting a different primary color to generate an image. Each light emitting element has a duty cycle in a lighting period, which may be an image frame period. A sequence scheme is provided for alternatingly driving different ones of the light emitting elements. The light emitting elements are driven in accordance with the sequence scheme at least two times in the lighting period, while maintaining the duty cycle for each light emitting element. In the sequence scheme, at least one light emitting element having the highest temperature sensitivity of all light emitting elements is driven more times than another one.

Abstract: The invention describes a method of driving a discharge lamp (1), wherein a blackening value (N) is determined, which blackening value (N) represents a level of blackening of the interior of the lamp (1), and a recovery parameter (2, T) is calculate based on the blackening value (N). When the lamp power is increased above the saturation power level, the lamp (1) is driven according to the recovery parameter (2, T) for the duration of a specific recovery time. The invention further describes a driving arrangement (70, 70), and a projector system (10) comprising a high-pressure discharge lamp (1) and such a driving arrangement (70, 70).

Abstract: A scanning backlight unit (BU) for a matrix display comprises a plurality of light sources (L1, . . . , Ln). A driver (2) supplies drive signals (D1, . . . , Dn) to the light sources (L1, . . . , Ln). A controller (3) controls the driver (2) to separately activate the light sources (L1, . . . , Ln) to obtain light-emitting regions (5) being active. A light sensor (4) is associated with a group of at least two of the light sources (L1, . . . , Ln) to supply a sensor signal (SES) which indicates a luminance (LU) of the group. The controller (3) reads the sensor signal (SES) at different instants (ts1, . . . , tsn) at which mutually different subsets of the light sources (L1, . . . , Ln) of the group are active to control the driver (2) to supply power levels to the light sources (L1, . . . , Ln) of the group to obtain a luminance (LU1, . . . , LUn) of each one of the light sources (L1, . . . , Ln) of the group in dependence on the sensor signal (SES).

Abstract: A method for driving a high-pressure gas discharge lamp of a projector system, which is suitable to produce and to supply to a light valve device during a projection interval (4) a light beam of a basic color which is selected from several basic colors (G, R, B). The lamp is driven by a lamp current. During said projection interval light valves of the light valve device are controlled in a pulse width modulation manner to have each valve provide a respective wanted light integral over said projection interval. During at least one of a number of successive projection intervals associated with one basic color a magnitude of the lamp current is temporarily reduced for at least a time that all light valves can be controlled for said one basic color.

Abstract: A projection system and a method for operating a discharge lamp are described. The protection system comprises a discharge lamp 12 and driving electronics 14. The color wheel 18 serves as color filter for filtering light 16 emitted from lamp 12 to generate a light sequence 20 with different colors in sequential color time periods 22, 22a. In between color time periods 22, 22a, spoke time periods 24, 24a are arranged. The driving electronics provide a lamp current I with superimposed first current pulses, which are generated in at least one of the color time periods 22, 22a. In order to allow greater flexibility and be able to achieve stable arc operation and constant color point over lamp lifetime, the driving electronics 14 further provide second current pulses superimposed on the lamp current. The second current pulses are generated during at least one of the spoke time periods 24, 24a.

Abstract: The invention describes a method of driving a discharge lamp (1) in a projection system (10), wherein, in a feed-forward control process, system status data (SDL, SDF, SDV) comprising static information pertaining to the design of the system and/or dynamic information pertaining to the projection system and/or dynamic information pertaining to the lamp operation are obtained. Based on the system status data (SDL, SDF, SDV), a momentary target light waveshape (LWT, LWT?) required by the projection system (10) and a waveshape correcting function are determined. Subsequently, the actual current (I) of the discharge lamp (1) is controlled regulated according to a momentary required waveshape (RW) which is determined based on the target light waveshape (LWT, LWT?) and the waveshape correcting function. Moreover the invention describes an appropriate driving unit (11) for driving a discharge lamp (1) and a projection system (10), comprising such a driving unit (11).

Abstract: A driver circuit 10 is described for driving loads such as LED, OLED or LASER diode devices L. A switching converter 12 has a switching element M1 and reactive elements L1, C1 to provide an output switching voltage V1 by sequential switching operations of the switching element M1. The load L is connected to the output switching voltage. A linear current driver circuit 14 is connected in series to the load L and comprises an amplification element Q1 and a feedback circuit R1, 22 with a current control input VL, set, IB. In order to enable the circuit to be easily used, a control unit 16, 116, 216 is provided with a sensing input VL, 1, VL, 2 for a current or voltage at the linear current driver 14. A microcontroller 30, 130, 230 executes a control program for processing the sensing input and providing both a current control output VL, set, IB and a switching control output VL, set in accordance with a set current value Iset.

Abstract: The present invention relates to a method of generating light with a predetermined chromaticity value of a color gamut by color mixing of the light emitted by a plurality of light sources, each of which emits light with a primary color, the light sources being capable of emitting light with at least three primary colors, wherein at least a first and a second light source are used to emit light of at least one primary color.

Abstract: The invention describes a method of adjusting the light output of a projector system comprising a light source (1) and a display unit (2) with controllable elements (M1, M6) for controlling the path of the light originating from the light source (1), which method comprises compiling a switching sequence (S1, SRGB, Sint) for the controllable elements (M1, M6) of the display unit (2), which switching sequence (S1, SRGB, Sint) comprises long segments and short segments, whereby a long segment is of a duration greater than or equal to a predefined threshold and a short segment is of a duration less than or equal to the predefined threshold; obtaining a light output adjustment measure (15, 15?) by which the light output of the light source (1) is to be adjusted; and generating a light pulse sequence (L50, L25, LR50, LG5o, LB5o, LRmt5o, LGmt5o, LBmt5o) such that the duration of a light pulse (LP) of the light pulse sequence (L50, L25, LR50, LG5O, LB5O, LRint50, LGint5o, LBint5o) during a segment of the switching se

Abstract: Generating an output pulse signal (Y), which has an output signal period (Ty), which is divided by a magnitude transition into a leading part (LP) and a trailing part (TP). During each output signal period (Ty) altering means (27 to 36) determine in a coarse and fine way a duration (TLP, TTP) of one or both of said output signal period parts (LP, TP) by using a clock signal (Cx) of different clock cycle durations (TCx0, TCx1, TCx2), dependent on a value of a first digital number (D1) and a value of second, less significant digital number (D3, D5), respectively.

Abstract: The invention describes a method of shutting down a high pressure discharge lamp (1) in which a pair of electrodes (2) is disposed in an arc tube (3), which method comprises reducing, upon receipt of a shut-down request (SR), the lamp power (P) towards a reduced power level (PR) required to sustain a long-term arc discharge between the electrodes (2), and driving the lamp (1) towards the reduced power level (PR) for a reduced power duration before completely shutting down the lamp power (P), whereby, prior to reducing the lamp power (P) towards the reduced power level (PR), the lamp power (P) is reduced to an undershoot power level (Pu), which undershoot power level (Pu) is lower than the reduced power level (PR) required to sustain a long-term arc discharge between the electrodes (2), and the lamp is driven at this undershoot power level (Pu) for an undershoot power duration (tu) before increasing the lamp power (P) again to approach the reduced power level (PR).

Abstract: The invention describes a method of driving a discharge lamp (1), wherein a value of pressure (Prlamp) in the lamp (1) is determined during operation of the lamp (1) at a dimmed power level, a correction factor (K, KR, KG, KB) is determined based on the dimmed power level pressure value (Prlamp), a required power value (Ptarget) for a requested light output level is calculated using the correction factor (K, KR, KG, KB), and the lamp (1) is driven according to the required power value (Ptarget). The invention further describes a method of driving a projector system (10, 10?). A driving unit (11, 11?) for driving a discharge lamp (1) in a projector system (10, 10?) is also described, as well as a projector system comprising a high-pressure discharge lamp (1) and a driving unit (11, 11?).

Abstract: A projection system and a method for operating a discharge lamp are described. The protection system comprises a discharge lamp 12 and driving electronics 14. The color wheel 18 serves as color filter for filtering light 16 emitted from lamp 12 to generate a light sequence 20 with different colors in sequential color time periods 22, 22a. In between color time periods 22, 22a, spoke time periods 24, 24a are arranged. The driving electronics provide a lamp current I with superimposed first current pulses, which are generated in at least one of the color time periods 22, 22a. In order to allow greater flexibility and be able to achieve stable arc operation and constant color point over lamp lifetime, the driving electronics 14 further provide second current pulses superimposed on the lamp current. The second current pulses are generated during at least one of the spoke time periods 24, 24a.

Abstract: This invention describes a method for driving a gas discharge lamp (1), whereby an alternating voltage (U) is applied to the gas discharge lamp (1), the alternating voltage (U) having a first polarity during a first time interval (tf1, ts1) and a second polarity opposite to the first polarity during a second time interval (tf2, ts2). In this method, the first time interval (tf1) and the second time interval (tf2) are repeated alternately during a first operation mode. During a second operation mode, the electrical power (P) being provided to the gas discharge lamp (1) is smaller compared to the first operation mode, and the first time interval (ts1) and the second time interval (ts2) are repeated alternately, whereby in this second operation mode the duration of the first time interval (ts1) is at least a multiple of the duration of the second time interval (ts2).