Abstract: The invention relates to an AC/DC converter circuit (100) and a method for converting N?2 AC supply voltages (U1, U2, U3) into DC voltage. This is achieved by feeding the AC supply voltages to first terminals (a1, a2, a3) of full bridge converters (11, 12, 13), wherein the second terminals (b1, b2, b3) of these rectifiers are coupled to each other. The outputs (d11, d1?, d2, d2?, d3, d3?) of the rectifiers are fed to the DC terminals of intermediate converters (21, 22, 23). The AC terminals (e1, e1?, e2,e2?, e3, e3?) of the intermediate converters are connected to the primary sides of transformers (31, 32, 33), wherein the secondary sides of these transformers are provided to further rectifiers (41, 42, 43). The circuit design allows using MosFETs of limited voltage capability for processing 380 V three-phase AC current, thus achieving a high efficiency.

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: An imaging system (100) includes a stationary gantry (102) and a rotating gantry (104). The rotating gantry (104) includes a first component (110, 114, 116) supplied with first power and a second component supplied with second power, wherein the first and second power are different. A contactless power chain (118) includes a first transformer (202, 204, 306) for transferring the first power from the stationary gantry (102) to the rotating gantry (104) and a second transformer (202, 204, 306) for transferring the second power from the stationary gantry (102) to the rotating gantry (104). The first and second transformers (202, 204, 306) are shifted relative to each other along the longitudinal axis (108) by a pre-determined finite non-zero distance (240). In another embodiment, an imaging system (100) includes a stationary gantry (102) and a rotating gantry (104) that rotates about a longitudinal axis (108).

Abstract: A system (100) for controlling a plurality of light sources (104a-f) by means of light groups, wherein each light group synchronously controls a subset of the plurality of light sources. The system (100) comprises: a central controller (102); a plurality of light sources (104a-f) wired to the central controller (102); and a light sensor (106a-c) wired to the central controller (102). The central controller (102) is configured to: receive a measurement signal from the light sensor; based on the received measurement signal, determine a subset of light sources that are in optical contact with the light sensor; and include the subset of light sources in a light group associated with the light sensor.

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 driving a gas discharge lamp and relates to a lamp driver circuit for driving a gas discharge lamp. The method includes supplying a current to the gas discharge lamp, reversing the direction of the current supplied to the gas discharge lamp and, substantially simultaneously, generating a relatively high voltage. The generated high voltage serves to prevent a series of re-ignitions of the gas discharge lamp that may lead to visible flickering of the gas discharge lamp or to extinction of the gas discharge lamp.

Abstract: The invention provides a switched mode power converter adapted for zero-voltage transition operation, wherein the converter comprises a half-bridge, having a first power switch (206) and a second power switch, a generator (201) adapted for generating a switching signal S1 after a first period of time, wherein the first period of time starts at the switching off of the second power switch, a controller (202) for converting the switching signal S1 into a control signal S2, wherein the first power switch (206) is switched on in case of the control signal S2, wherein the controller (202) comprises a detector (205), wherein the detector (205) is adapted to generate a first signal S3 in case the voltage over the first power switch (206) is decreasing, a processor (203), wherein the processor (203) is adapted to generate a trigger signal S4 in case of a switching signal S1 and while the first signal S3 is not present, a storage element (204), wherein the storage element (204) is adapted to generate the control signa

Abstract: A resonant DC/DC converter for supplying an output power comprises a switching device (18) for supplying a switched voltage (UWR) to a resonant circuit (20) having a transformer (T). The switched voltage (UWR) is derived from an intermediate circuit voltage (Uz) having a fixed pulse width and frequency so that the zero crossings of the resonant current (Ires) generated in the resonant current are defined. The switching configuration of an inverter circuit (18) is selected by a control device (31) to either increase, decrease or maintain at a substantially constant level the resonant current according to the polarity of the switched voltage, so as to control the output power as required.

Abstract: A voltage multiplier comprising a chain of multiplier stages, each multiplier stage (STGj) comprising first and second inputs (IPIj, IP2j) and first and second outputs (OPIj, 0P2j), which first and second outputs of a multiplier stage is coupled to respective first and second inputs of another multiplier stage, each multiplier stage (STGj) comprising a series diode arrangement of two diodes (DIj, D2j) coupled, in the same current conducting direction, between the first input (IPIj) and the first output (OPIj). Each multiplier stage (STGj) further comprises a first capacitor (CIj) coupled between the first input (IPIj) and the first output (OPIj), and a second capacitor (C2j) coupled between the second input (IP2j) and the second output (0P2j). Each multiplier stage (STGj) further comprises equalizing means (VLSj; C2j, C3j, C4j), preferably capacitors (Csj), for equalizing the current distributions, as a function of time, of the currents (Ij) through the diodes (DIj, D2j).

Abstract: The invention provides a device for a computer tomography gantry (91) for transferring contactlessly electrical energy from a stationary part of the gantry (92) to a rotary part of the gantry (93), wherein the device comprises a first power transformer, a second power transformer, wherein the first and the second power transformers are adapted for transferring the electrical energy, wherein the first power transformer comprises a first winding (506, 507, 542, 602, 601, 1202, 1301, 1401) out of the group consisting of a first set of primary windings and a first set of secondary windings of the first power transformer, wherein the second power transformer comprises a second winding (508, 509, 543, 603, 604, 1204, 1302, 1402) out of the group consisting of a second set of primary windings and a second set of secondary windings of the second power transformer, wherein the first set of primary windings and the second set of primary windings being adapted to be mounted on the stationary part of the gantry, wherein

Abstract: The present invention refers to a high-voltage power supply circuit for inductively transmitting electrical energy from a stationary part to a load on a rotary part which requires a non-symmetrical voltage transfer, for example, an X-ray tube of an X-ray computed tomography device. The circuit may be realized as a resonant-type power converter circuit with a single rotary power transformer (500) or more than one such power transformer, where at least two separate DC/AC power inverter stages provide two individually controllable AC input voltages (U1, U2) to different windings (511, 512) of a multi-primary coil belonging to the rotary power transformer. Two output voltages supplied by the multi-secondary coil (521, 522, 523, 524) of said transformer which are derived from the two individually controllable AC input voltages are fed to the tube electrodes for powering the X-ray tube.

Abstract: This invention relates to a method for controlling a switching device (260) for providing a resonant circuit (350) with a switching voltage (Uwr) for generating a resonant current (Ires) in order to provide a required output power (rP) at an output of a resonant power converter (100). The invention further relates to a control device which is adapted to perform the proposed method for controlling a switching device. Moreover the invention relates to a resonant power converter including a control device for performing the proposed controlling method.

Abstract: The present invention refers to a DC/AC power inverter control unit of a resonant-type power converter circuit (400), in particular a DC/DC converter, for supplying an output power for use in, for example, a high-voltage generator circuitry of an X-ray radio-graphic imaging system, 3D rotational angiography device or X-ray computed tomography device of the fan-or cone-beam type. More particularly, the present invention is directed to a resonant-type power converter circuit out which comprises an interphase transformer (406) connected in series to at least one series resonant tank circuit (403a and 403a? or 403b and 403b?) at the output of two DC/AC power inverter stages (402a+b) supplying a multi-primary winding high-voltage transformer (404), wherein said interphase transformer (406) serves for removing the difference (DI) in the resonant output currents (1 and 2) of the DC/AC power inverter stages (402a+b).

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 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 voltage multiplier comprising a chain of multiplier stages, each multiplier stage (STGj) comprising first and second inputs (IPIj, IP2j) and first and second outputs (OPIj, 0P2j), which first and second outputs of a multiplier stage is coupled to respective first and second inputs of another multiplier stage, each multiplier stage (STGj) comprising a series diode arrangement of two diodes (DIj, D2j) coupled, in the same current conducting direction, between the first input (IPIj) and the first output (OPIj). Each multiplier stage (STGj) further comprises a first capacitor (CIj) coupled between the first input (IPIj) and the first output (OPIj), and a second capacitor (C2j) coupled between the second input (IP2j) and the second output (0P2j). Each multiplier stage (STGj) further comprises equalizing means (VLSj; C2j, C3j, C4j), preferably capacitors (Csj), for equalizing the current distributions, as a function of time, of the currents (Ij) through the diodes (DIj, D2j).

Abstract: A method of controlling an inverter (4) of a gas discharge lamp circuit. The inverter comprises two branches, each having a first semiconductor switch (32, 36) in series with a second semiconductor switch (34, 38) and having a connection node (40, 44), which is connected to a respective output terminal (42, 46) of the inverter. The first and second switches are connected to a first input terminal (16) and to a second input terminal (18) of the inverter, respectively. Each switch has an intrinsic or externally connected antiparallel diode (52-56). The switches of the branches are controlled by a controller in an alternating and cross-like manner to conduct and to not conduct. Controlling of switches is delayed by a first delay time per branch and by a second delay time between branches.

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: 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. According to an exemplary embodiment of the present invention, a power inverter control device for switching point determination is provided which comprises 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.