Abstract: Resonant DC-DC converters use a switching network to step a single DC voltage up to a working DC level using a resonant tank. However, high voltage DC power supply systems, for example, those used to power X-ray sources, are increasingly being integrated into smaller form factors, and it is becoming attractive to be able to make use of multiple DC-DC power supplies to power such X-ray sources. The present invention provides a topology for a resonant DC-DC converter, a DC electrical supply system, and method of operating a DC-DC resonant converter. The proposed topology uses a switching network to connect multiple DC power supplies to the resonant tank, to enable a more flexible provision of input power.

Abstract: A lighting device for generating colored and white light. According to the invention the lighting device comprises at least one light source (1, 4) emitting blue or ultraviolet light and a color conversion unit (2, 5) for converting said blue or ultraviolet light into visible light comprising at least two sections (2a, 2b, 2c, 6a, 6b, 6c, 6d), at least one section (2c, 6d) of which being a transparent or translucent color converting section, said color conversion unit (2, 5) being arranged for alternately illuminating said at least two sections (2a, 2b, 2c, 6a, 6b, 6c, 6d) with said blue or ultraviolet light, said at least one color converting section containing luminescent material, wherein said luminescent material is a luminescent organic dye in a polymer matrix or a crystalline inorganic luminescent material.

Abstract: Current switching point determination devices use two comparators with fixed threshold values. A power inverter control device for switching point determination is provided which includes a filter circuit and a subsequent single comparator. By this arrangement, the time event is independent of the amplitude and for sufficiently small frequencies also of the frequency.

Abstract: A controller is described, which is particularly suited for a power supply with switching elements (S1, S2), such as a switching mode power supply. The controller comprises a logical unit (18) which calculates a binary state value Zk by a first logical operation from a binary input value I and a prior binary state value Zk?1. The logical unit further calculates a binary output value Y by a second logical operation from the binary input value I and the binary state value Zk. In this way, fast and efficient fully digital control may be realized especially for a switching mode power supply, where the binary input value I is a comparator value and the binary output value Y is used to drive the switch elements (S1, S2). An adaptation unit (20), which may be a signal processor, determines the logical operations and delivers them to the logical unit (18) during operation of the controller unit (16).

Abstract: An apparatus and method for determining an output voltage or output current in an SMPS circuit 10 are described. The SMPS circuit comprises a switching element 18 which in operation is switched according to consecutive switching cycles. An electrical value IL within the SMPS circuit 10 is compared to a reference value Iref. The electrical value IL varies within the switching cycle such that is equal to the reference value at least once during each cycle. The comparator signal comp is evaluated to determine timing information t of an instant of change in the signal. The timing information t is used for determining the output voltage Vout,Av or output current Iout,Av.

Abstract: The invention relates to a method of determining a zero point (V0) of a current sensor in a circuit arrangement for operating a gas discharge lamp. The invention is characterized by the following process steps: the current (11) through the sensor is switched off for a short period during a first half wave (13) and a first test value (V6) is determined, then the current (11) through the sensor is switched off for a short period during a second half wave (14) having a different polarity and a second test value (?V7) is determined, whereupon an average value is formed of the two test values (V6, ?V7), and the zero point (Vx, V0) is determined by means of said average value. It is prevented thereby that the zero point drifts during lamp operation, for example owing to heating, and that amplitudes of the positive and negative half waves (13, 14) of the lamp current (11) are formed differently. Impairment of lamp life and visible artefacts in a presented projection image are prevented.

Abstract: The invention relates to a decentralized power generation system comprising a plurality of decentralized power generating units (11,12;13,14). In order to enable an optimized control of these power generating units while enabling at the same time a high security in the system, it is proposed that the system further comprises a plurality of DC/DC converters (31,32), each connected to another one of the power generating units for converting a current provided by the power generating units. The proposed system moreover comprises a DC bus (40) to which the DC/DC converters feed a respectively converted current. The proposed system moreover comprises at least one power receiving component (20) retrieving current from the DC bus, which power receiving component is physically separated from the DC/DC converters. The invention relates equally to a corresponding method.

Abstract: The invention relates to a DC/DC converter for use in a decentralized power generation system. If a DC/DC converter is physically separated from a power receiving component and connected to such a power receiving component via a DC bus, a short-circuit on the DC bus may endanger the system and service personnel. In order to minimize such a risk, it is proposed that the DC/DC converter comprises a converting component for DC/DC converting a direct current supplied by a power generating unit and for supplying a resulting converted direct current to a DC bus, and that the DC/DC converter comprises in addition a control component arranged to monitor a voltage at the outputs of the DC/DC converter and to cause the converting component to enter a short-circuit protection mode if the monitored voltage lies below a predetermined voltage threshold. The invention relates equally to a corresponding system and to a corresponding method.

Abstract: The invention relates to a resonant power LED control circuit for the independent, simultaneous brightness and color or color temperature control of two LEDs (41, 42) or two groups of LEDs, comprising a single resonant converter which is essentially formed from a half or full bridge DC/AC converter (2) with a control unit (21), a resonant capacitor, and a transformer (3).

Abstract: The invention relates to a circuit arrangement for operating a gas discharge lamp with a current. According to the invention, the current comprises a high-frequency AC component and a low-frequency AC component.

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.

Abstract: The invention relates to an electronic circuit and to a method of supplying a high-pressure discharge arc lamp (12). The circuit comprises a DC-AC converter, for which purpose two controllable switching elements T1, T2 are connected in the form of a half bridge to an operating potential U+ and a reference potential (10). The circuit further comprises a two-stage filter arrangement. The lamp is connected to a coil Lign of the second filter stage, and the same connection terminal of this coil Lign is connected to the reference potential (10) via a capacitor Cign. To make the circuit as small and as economical as possible, while high high-frequency interference peaks and strong currents in the circuit are avoided, it is proposed that a coil Trfilt of the first filter stage has at least three taps.

Abstract: A projection system for image display with at least one lamp (1), with at least one sensor (5) for detecting changes in the luminous flux delivered by said at least one lamp (1) and for compensating these changes through a suitable control of the image display and/or the lamp is described. The projection system is remarkable in that a light integrator (3) is provided, into which at least a portion of the light provided by the lamp (1) is coupled in, while the sensor (5) is optically coupled to the light integrator (3) such that it detects the luminous intensity present in the light integrator (3). Since this luminous intensity is very homogeneous because of the multiple reflections and is not influenced by brightness fluctuations caused by an optical component such as, for example, a color modulator (4), a very accurate compensation of changes in the luminous flux generated by the lamp (1) is made possible by the sensor signal.

Abstract: A projection system for image reproduction by means of at least one lamp (10) as well as a sensor (30) for generating a sensor signal for monitoring changes in the luminous flux generated by said at least one lamp (10) and for compensating these changes through a suitable control of the image reproduction is described. The projection system comprises a device (31; 32; 36, 37) for eliminating substantially periodic interference components from the sensor signal generated by the at least one sensor (30; 301, 302, 303). These interference components may be generated by an optical component such as in particular a color modulator (12) of the projection system. The invention thus renders possible an at least substantially interference-free compensation of fluctuations in the luminous flux generated by the lamp (10), for example owing to an unstable arc discharge, also in those color systems in which the positioning of the sensor (30) in the projection system is non-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 an electronic circuit and a method of supplying energy to a high-pressure gas-discharge lamp H, 65, 75. The electronic circuit comprises a line-supply input section 62, 72 to receive and convert an a.c. voltage from an a.c. line-supply system 61, 71, an energy storage means 63, 73 to store the energy put out by the line-supply input section 62, 72 and a lamp-current regulating unit 64, 74 that is supplied with an input voltage U1 by the line-supply input section 62, 72 via the energy storage means 63, 73 and that makes available a lamp current I2 for a high-pressure gas-discharge lamp II, 65, 75. To make it possible for the energy storage means 63, 73 to be particularly small, it is proposed that the lamp-current regulating unit 64, 74 have a power section L, D, C, S, A1, A2, K having a transconductive property.

Abstract: The invention relates to a circuit (1) having a converter (2) for converting an a.c. voltage into a d.c. voltage, which converter (2) has a diode half-bridge (8), a switch half-bridge (10) and two d.c. rails (20, 25). In accordance with the invention, the converter (2) has a second converter (3) for converting the a.c. voltage into a second d.c. voltage.

Abstract: The invention relates to a method for enhancing brightness and contrast in images provided by a projection-based presenter utilising a display panel (5) illuminated by at least one scrolling band of light and a lamp (3) as a light source for said at least one scrolling band of light. In order to enable such an enhancement, it is proposed that the method comprises modulating the light output of the lamp (3) between different scrolling positions in a way that a higher light intensity is supplied by said lamp (3) when parts of the display panel (5) currently representing brighter parts of a respective image are illuminated by said at least one scrolling band of light than when parts of the display panel (5) currently representing less bright parts of said image are illuminated by said at least one scrolling band of light. The invention relates equally to a corresponding projector, and to an image processor and a regulation and controlling system for such a projector.

Abstract: The invention relates to an electronic circuit for igniting a high-pressure lamp. A resonant circuit 13 of the circuit is used to supply the ignition voltage for the high-pressure lamp. To enable an exact adjustment of the resonance frequency in the resonant circuit, it is proposed that the circuit also comprises converter 12 for generating an alternating voltage with which the resonant circuit 13 is excited and an oscillator 14, 16, 17 for driving the converter 12, the fundamental frequency of the output voltage of the oscillator being at least in proximity to an integral fraction of the resonance frequency of the resonant circuit 13. Finally, it is proposed that the circuit includes a feedback 17 from the resonant circuit 13 to the oscillator 14, 16, 17, whereby the fundamental frequency of the output voltage of the oscillator is so tuned that the resulting frequency of the output voltage of the oscillator corresponds substantially exactly to the integral fraction of the resonance frequency.

Abstract: 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.