Abstract: The present invention relates to a method of operating a projection system comprising several solid state light sources (2, 3, 4) of different colour 13, 14, 15) and at least one spatial light modulator (1) having an array of switchable elements. Said array is illuminated by at least one of said light sources (2, 3, 4) for several illumination periods and is addressed such that the light is timely and spatially modulated to project images onto a screen. In the present method said light sources (2, 3, 4) are controlled to emit light modulated in amplitude (15) and/or time (18) during said illumination periods of said array. With the present method an increased greyscale resolution of the projection system can be achieved.

Abstract: Ignition of a gas discharge lamp 10, which has a gas containing main space and two inner electrodes, of a lighting unit 4 of a lighting system is achieved by the use of a high frequency resonance circuit. The resonance circuit is connected to the inner electrodes and to a supply device 2, which supplies an alternating supply voltage. An outer electrode 22 is arranged near one the inner electrodes and to a node of the resonance circuit. Upon supplying the supply voltage a high voltage alternating burst will be generated at the outer electrode. This will result into a discharge of the gas in the main space. In turn, this will induce a discharge of the remaining gas. Then the frequency of the supply voltage will increase and a small reactive current only will remain to flow through the resonance circuit.

Abstract: A method for operating a projection system (1) is described, wherein a brightness level (B1, B2, B3, B4, B5, B6) in an image (IM) is represented by the total length of a number of light switch-on phases within a particular image cycle (VT). A high pressure discharge lamp (2) of the projection system (1) is operated via a lamp driver with an essentially square-wave alternating current (IL) SO that an overshoot sequence (O), which occurs in the alternating current (IL) after a current zero crossing during operation of the high pressure discharge lamp (2), has a frequency so high that for each possible brightness level at least one full period (P) of the overshoot sequence (O) lies essentially within a light switch-on or switch-off phase (ts) following the zero crossing. A projection system (1) and a lamp driver (10) for a high pressure discharge lamp (2) in such a projection system (1) are also described.

Abstract: The invention relates to a standby circuit, an electrical device with a standby circuit, a method for the control of the electrical device and a power supply assembly. Whereas the power supply unit and the control electronics are in permanent operation when conventional devices are in the standby mode and consequently have a high power consumption, the invention proposes a solution for saving energy while retaining convenience of operation by which the power supply unit is switched off in the standby mode. A standby circuit, preferably fed by an energy buffer element, remains active in the standby mode and monitors signal inputs for activation events. When an activation event occurs, the standby circuit switches on the power supply unit.

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: 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: 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: There is described a method for operating a high-intensity discharge lamp (2), in which the high-intensity discharge lamp (2) is acted upon by an AC current (I) which commutates between positive pulses (Ip) and negative pulses (In) with a predefined current amplitude (IA), wherein a pulse width ratio between the pulse width of a positive pulse (Ip) and the pulse width of an adjacent negative pulse (In) is modulated in such a way that the mean current value (I) of two successive positive and negative pulses (Ip, In) fluctuates periodically between positive and negative values. In addition, the value of the current amplitude (IA) is modulated in accordance with a predefined modulation function (M). A description is also given of a corresponding lamp driver (10) for a high-intensity discharge lamp (2) and of a projection system (1) comprising such a lamp driver (10).

Abstract: The invention relates to a method and an arrangement (10) for monitoring a gas discharge lamp (22), comprising a control circuit (18) for detecting an electrical measured value assigned to the lamp voltage. The control circuit (18) is provided for detecting one voltage value prior to a change in current and a second voltage value after a change in current, or a setting time, and for producing a control signal which depends on the difference in the voltage values or on the setting time. In this way, a pressure within the lamp is monitored and a control signal can be produced which can be used to cool the lamp or to switch the lamp off. This methods detects inflation and therefore prevents an explosion of the lamp.

Abstract: The invention relates to an arrangement for converting mechanical energy into electrical energy comprising a piezo-electric auxiliary generator producing an auxiliary voltage and a main generator which is coupled mechanically with the auxiliary generator and producing the electrical energy.

Abstract: 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.

Abstract: The invention relates to a circuit (2) comprising at least two parallel-connected light-emitting diodes (4, 5) opposite poled in a first parallel branch (12) and comprising at least two parallel-connected light-emitting diodes (6, 7) opposite poled in a second parallel branch (13), and also comprising a capacitor (8) and a coil (9). According to the invention, the first parallel branch (12) has a capacitor (8) and the second parallel branch (13) has the coil (9). On account of the capacitive parallel branch (10) and the inductive parallel branch (11), idle currents arise which are phase-shifted with respect to one another. The idle currents compensate one another and light changes of the oppositely-poled diode pairs take place at different points in time. A light current is thun smoothed.

Abstract: 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.

Abstract: 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.

Abstract: The invention relates to a method of representing a video image based on a video signal by means of a projector which comprises an image display device and a high-pressure gas discharge lamp, which lamp is supplied with a square-wave alternating current (I0, I10) on which a current pulse (P1, P3, P10, P40) is superimposed before each phase reversal. According to the invention, the alternating current (I0, I10) is superimposed with a second current pulse (P2, P4, P20, P30, P50, P60) of the same polarity. A simple attunement of the alternating current frequency to the image frequency without image artifacts is made possible by the second pulses (P2, P4, P20, P30, P50, P60).

Abstract: A method and a circuit arrangement for the operation of a high-pressure gas discharge lamp (HID [high intensity discharge] lamp or UHP [ultra high performance] lamp) is described, which lamp is particularly suitable for illuminating projection displays with sequential color rendering (for example LCOS or SCR-DMD systems) with a pulsatory lamp current. Artefacts in the color rendering are avoided through the generation of at least one compensation pulse of a given amplitude and a given timing and through superimposition thereof on the lamp current.

Abstract: A wireless resonant powering device 1 according to the invention comprises a first inductor winding 3, which is arranged to form a transformer 9 with the inductor winding 13 of the energizable load 11. The first inductor winding 3 is arranged to form a resonant circuit 5, which may comprise a suitable plurality of electric capacitances and coils. The components of the resonant circuit 5 are selected such that the magnetic energy received by the inductor winding 13 damps the energy flow in the resonant circuit so that the induced voltage in the inductor winding 13 is substantially constant and is independent of the magnetic coupling between the first inductor winding 3 and the inductor winding 13 at the operating frequency of the driving means 6. The resonant circuit is driven by the driving means 6, comprising a control unit 6c arranged to induce an alternating voltage between a first semiconductor switch 6a and a second semiconductor switch 6b.

Abstract: A projection system for image representation includes a display, a lamp, and a sensor for generating a sensor signal for monitoring and compensating changes in the luminous flux provided by the lamp. To achieve a monitoring of the light quantity actually incident on the display, an optical component is arranged in a light path between the lamp and the display. The optical component allows a first light component to pass through and reflects a second light component such that one of the light components is directed at the display and the other light component is directed at the sensor arranged outside the light path. A sensor signal generated in this manner renders it possible to compensate for fluctuations in the luminous flux provided by the lamp through the control of a lamp driver in an effective.

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 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.

Abstract: The invention relates to a circuit (1) and a method for operation of a gas discharge lamp (3) with a switching transformer (2), which switching transformer comprises a switch (22), a converter inductor (24) and a control means (27) in a control loop (33) for measuring a lamp voltage and setting a desired power. In accordance with the invention, the switching transformer (2) comprises a second control loop (80). By means of the second control loop the switching transformer is adjustable to individual lamp conditions.