Abstract: An LLC backlight driving control circuit is disclosed and includes an LLC resonant converter circuit configured to drive a current to alter periodically; a rectifying and filtering circuit configured to balance a light bar voltage difference; a control circuit configured to implement a constant current feedback; and two paths of LED light bars configured to provide LED backlight. The LLC resonant converter circuit, the rectifying and filtering circuit, the two paths of LED light bars, and the control circuit are connected in sequence to form a loop circuit. The LLC resonant converter circuit inputs a power supply current to the two paths of LED light bars and controls an output duty cycle of the LLC resonant converter circuit by acquiring a current flowing through a sampling resistor, thereby controlling a voltage that is outputted to the two paths of LED light bars.

Abstract: A remote controller is arranged for selecting a light source among a plurality of light sources. The remote controller has an omnidirectional transmitter and is arranged to instruct, by means of the omnidirectional transmitter, the light sources to transmit a directional signal comprising a code, which is unique for each light source. Further, the remote controller has a directional signal receiver, and is arranged to receive the directional signals from the light sources, and signal comparison circuitry connected with the directional signal receiver. The remote controller is arranged to select one of the light sources on basis of the received directional signals. Furthermore, the remote controller comprises a transmission indicator, which is arranged to generate an indication signal, indicative of a successful omnidirectional transmission, and it is arranged to initiate the selection of one of the light sources by means of the indication signal.

Abstract: A method of selecting a light source among a plurality of light sources by means of a remote controller includes the remote controller: instructing, by omnidirectional transmission, the light sources to each transmit a directional signal comprising a code, which is unique for each light source; —receiving the directional signals from the light sources; and selecting one of the light sources on basis of the received directional signals. Furthermore, the method includes: generating, remotely of the light sources, codes to be transmitted by the light sources; and—the remote controller instructing each one of the light sources which one of the remotely determined codes to transmit.

Abstract: A soft-start circuit generates a soft-start voltage Vss having a voltage level that rises over time. A pulse width modulator generates a PWM signal having a duty ratio adjusted such that a feedback voltage Vout? that corresponds to the output voltage Vout of the switching power supply matches the soft-start voltage Vss. A driver circuit controls a switching element according to the PWM signal. A capacitor is arranged such that one terminal thereof is set to a fixed electric potential. A current source generates a charge current that flows intermittently in synchronization with the PWM signal so as to charge the capacitor. The soft-start circuit outputs, as the soft-start voltage Vss, a voltage that occurs at the capacitor.

Abstract: The instant disclosure relates to a LED backlight driving module. The driving module utilizes a plurality of second power isolation transformers interconnected to each other in series and connected to a secondary winding of a first power isolation transformer in parallel to produce a plurality of second driving signals with uniform current, and driving corresponding LED light bars with uniform brightness. Optionally, a base voltage circuit can be used to provide a base voltage with negative voltage level on the other end of LED light bars, so as to lower the positive voltage level of the second driving signals. Thus, it is beneficial that the LED backlight driving module provides higher power conversion efficiency and has lower design cost.

Abstract: The invention discloses a method for igniting a lamp of a projector. The method includes steps of: (a) sensing a first temperature difference in response to power-off of the projector; (b) in response to power-on of the projector, detecting an aftercooling time and judging whether it is smaller than a predetermined cooling time, if YES, perform step (c); otherwise, perform step (g); (c) sensing a second temperature difference; (d) judging whether a ratio of the second temperature difference to the first temperature difference is larger than a threshold, if YES, perform step (e); otherwise, perform step (g); (e) calculating a re-cooling time; (f) controlling a fan to operate for the re-cooling time to cool the lamp down; and (g) igniting the lamp.

Abstract: A method of generating an output DC voltage of a gas discharge process voltage supply unit, in which in a first voltage transformation stage a first DC voltage is transformed into a second DC voltage of a predetermined voltage range, and the output DC voltage is generated from the second DC voltage in a second voltage transformation stage. A switching element of at least one boost converter is switched with a controlled pulse-duty factor for generating the output DC voltage in the second voltage transformation stage. This method permits striking and maintenance of a plasma process.

Abstract: A push-pull inverter is supplied from an inductively current-limited DC voltage source by way of a center-tap on a transformer having significant inductance. This transformer inductance is parallel-coupled with a capacitance means. The inverter is made to self-oscillate through positive feedback provided by way of a saturable current transformer. The inverter frequency is determined by the saturation time of this current transformer, which saturation time is designed to be somewhat longer than the half-cycle period of the natural resonance frequency of the transformer inductance combined with the capacitance means. By controlling the length of this saturation time, the magnitude of the current provided to the fluorescent lamp is controlled, thereby permitting control of the light output in response to changes in the magnitude of the power line voltage.

Abstract: An apparatus for operating a fluorescent lamp having first and second power source circuits, the second power source circuit including a high frequency transformer having two or more outputs for supplying pre-heating electric currents to filaments, the second power source circuit being arranged to be controllable individually from the first power source circuit for supplying a tube electric current to turn on a fluorescent lamp so that the electric power level for pre-heating the filaments is switched between a state where a light adjustment is performed by turning on/off a tube electric current at high frequency and a state where the fluorescent lamp is turned off in a standby mode.

Abstract: A frequency-modulated converter with a series-parallel resonance, particularly for driving any ohmic or inductive load, including gas discharge tubes, wherein a commutating voltage switch in the form of a transistor is provided and is connected in series between a negative electrode of a direct current voltage source and a first terminal of an inductor, and a pulse generator circuit is provided between the voltage source and the transistor's control electrode and the inductor's second terminal is connected to the primary winding of a transformer.A first capacitor and rectifier diode are also provided in a first and second parallel branch respectively between the transistor's charge receiving and charge emitting electrodes, and a second capacitor is provided across the voltage source's electrodes, and a smoothing capacitance is provided for the voltage source, the second capacitor being connected in series with the inductor via the diode.

Abstract: A diming circuit for a hot cathode fluorescent lamp is operated in a push-pull mode whereby the hot filaments are alternately the cathode and the anode. Both filaments thus experience similar degradation with time at all brightness levels, thereby enhancing and lengthening the life of the lamp.

Abstract: An electronic fluorescent lamp ballast having at least an energy storing component, a controlling component which has two states, and two socket elements which enables the filaments of the fluorescent lamp to be connected in series with the energy storing component. A constant current flows through a portion of the energy storing component when the controlling component is in one state producing an "energy latching" effect which will enable the ballast to achieve a very high efficiency of energy transfer. The ballast also has a self adjustable frequency of operation as a function of lamp impedance variation due to age and enables constant ionization within the fluorescent lamp.

Abstract: A solid state bridge inverter is disclosed wherein the power for driving the transistors is generated by the current flowing to the load. Windings are so connected on the drive transformers that one transistor cannot possibly turn on until the other one is fully off including storage and turn off time. This is accomplished in such a manner that the load may be highly inductive without any detrimental effect upon the power transistors. Also disclosed is a unique method for deriving the power for the logic circuitry as well as a concept where a single magnetic element can provide both a balun type filter action on the input as well as power factor correction and smoothing action to supply filtered DC voltage and current to the inverter while maintaining a 0.9+ power factor to the AC line. Further disclosed is a combination of the above described components along with further unique circuit configurations to provide a highly efficient solid state fluorescent ballast.

Abstract: The above and other objects, advantages and capabilities are achieved in one aspect of the invention by an output circuit for an electronic ballast system. The circuit includes N sets of output connections for accepting N lamps. The lamps are driven by an output autotransformer coupled to the lamps through a feedback winding that is used to apply a feedback signal to an inverter drive circuit. Capacitive impedances are coupled across the lamps so that the capacitances, the lamp filaments, the feedback winding, and the output transformer form a circuit loop. The capacitances are chosen to have an impedance, at the inverter operating frequency, less than the pre-ignition impedance of the lamps and greater than the post-ignition impedance.

Abstract: The above and other objects, advantages and capabilities are achieved in one aspect of this invention by a drive scheme for a plurality, that is, for N, where N-2, flourescent lamps. The drive circuit comprises (N+1) pairs of output terminals, each comprising associated first and second individual terminals. An output transformer is coupled at one end to the (0,1).sup.1 terminal and at another end to the (0,1).sup.N+1 terminal. N impedance elements, typically capacitors, are coupled across associated pairs of lamp filaments in a fashion whereby each impedance element is coupled at one end to the second terminal of one pair and at another end to the second terminal of the succeeding pair. To wit: The first impedance element is coupled between the second terminal of the first pair, and the N.sup.th element is coupled between the second terminal of the N.sup.th pair and the second terminal of the (N+1).sup.th pair.

Abstract: A solid state power supply and light emission controller for a cold cathode luminescent tube which converts alternating current line voltage, or direct current voltage, into a variable repetition rate pulse alternating current voltage for energizing the tube and for controlling the light emission of the tube. The power supply provides for essentially constant light emission from the tube in the presence of variations in the internal impedance of the tube, variations in ambient temperature, and variations in line voltage. The power supply finds use, for example, with cold cathode luminescent tubes such as neon tubes, and the like.

Abstract: An inverter ballast for fluorescent lamps utilizing a resonant circuit coupled to the lamp and operated from a source of DC power through transistors. The transistors are controlled by a sensing means in the resonant loop which insures that the transistor switch at zero current. Furthermore, the coupling means for the load controls a source of heater voltage to the anodes of the fluorescent light which operate at very low current, an antisaturation circuit made up of separate windings are on the current transformer and connected to the switching transistor bases and through diodes to the power supply to prevent "shoot through" current in the transistors. An autotransformer is used as a high leakage reactance transformer; and a circuit is provided to prevent overload of the resonant circuit in case of lamp failure. Shoot through currents are prevented, and overload of the resonant circuit is prevented, and an autotransformer coupling of the resonant circuit to the load is used.

Abstract: A power supply including a high frequency inverter circuit coupled to an electron discharge lamp load through a special purpose transformer is disclosed. The transformer is wound on a saturable ferromagnetic core structure forming a first magnetic flux path coupling the primary and secondary windings of the transformer and a second shunt magnetic path including an air gap which carries and increasing share of flux as load current increases. The switching of the inverter circuit occurs in response to the partial saturation of the core. Auxilliary windings serially connected with the primary winding of the transformer and wound about the shunt magnetic path enhance the current regulating properties of the supply.

Abstract: An output transformer for an inverter driven by a pulsating voltage obtained through the full wave rectification of a low frequency alternating current voltage is provided with an auxiliary winding, and a high frequency voltage obtained from the auxiliary winding is rectified to obtain a voltage for charging a capacitor. The voltage across the capacitor is used as an auxiliary voltage together with the pulsating voltage for driving the inverter. The circuit for charging the capacitor includes a current limiting inductor having first and second coil sections, through which the charging current flows alternately in opposite directions depending upon the polarity of the high frequency voltage.

Abstract: To prevent excessive voltages from interfering with a switching transistor supplying a fluorescent tube circuit with alternating pulses from a d-c supply upon removal of the fluorescent tube from the tube transformer, a voltage detector is connected to the primary or input winding of the fluorescent tube transformer to determine occurrence of excessive voltages upon removal of the tube from the secondary, the sensed excessive voltage being applied to a switching circuit to remove the transformer from the supply. The system is particularly applicable to emergency supply connections in which the tubes are, normally, supplied from an alternating current network and from a transistor inverter and a battery under conditions of network power failures.

Abstract: Welding arc stabilizing and igniting is effected with at least one pulse-forming condenser switched by spark gap or semiconductor switch to deliver a sharp discharge pulse through the winding of a pulse transformer, the magnetic energy thus built up in the transformer being then dissipated by a unidirectional diode bypass of the winding through the switch. The pulses are delivered by the transformer to the welding electrodes, and can be combined with pulses of lower voltage and longer duration by an appropriate series condenser-resistor combination in the transformer output. The pulse-forming condenser can be charged by simple resistor connection to the input of a step-down welding current transformer, or by transformer coupling to any source of AC welding current.

Abstract: A frequency-modulated converter with a series-parallel resonance, particularly for driving any ohmic or inductive load, including gas discharge tubes, wherein a commutating voltage switch in the form of a transistor is provided and is connected in series between a negative electrode of a direct current voltage source and a first terminal of an inductor, and a pulse generator circuit is provided between the voltage source and the transistor's control electrode and the inductor's second terminal is connected to the primary winding of a transformer. A first capacitor and rectifier diode are also provided in a first and second parallel branch respectively between the transistor's charge receiving and charge emitting electrodes, and a second capacitor is provided across the voltage source's electrodes, and a smoothing capacitance is provided for the voltage source, the second capacitor being connected in series with the inductor via the diode.