Vastview Technology Inc.

Hung-Chi Chu

Yuhren Shen

Yuh-Ren Shen

Ming-Chia Wang

Chang-Cheng Lin

An apparatus for driving LEDs using high voltage includes two LED driving circuits and two switches controlled by a universal controller so as to connect the two LED driving circuits in two different configurations. Each LED driving circuit has an LED unit formed by a plurality of LED segments. Each LED segment has an associated bypass switch controlled by an LED controller to bypass or connect the LED segment in the LED unit. When an input voltage ranges from rectified 90 volt AC to rectified 140 volt AC, the two switches are controlled to connect the two LED driving circuits in parallel. When the input voltage ranges from rectified 180 volt AC to rectified 265 volt AC, the two switches are controlled to connect the LED segments of the LED unit in one LED driving circuit in series with the other LED driving circuit.

Universal method for driving LEDs using high voltage

An LED driving circuit comprises an LED unit having a plurality of LEDs connected in series, coupled with a voltage charging and discharging unit and powered by a rectified AC voltage of an AC input voltage. A controllable current limiting unit or a current limiting unit in association with a switch connects the LED unit to ground. The voltage charging and discharging unit has first and second diodes connected to the LED unit, and a storage capacitor to form a charging path through the first diode and a discharging path through the second diode in order to provide a steady state capacitor voltage for reducing the number of LEDs connected in series in the LED unit.

Low-cost LED driving circuit using high voltage

An apparatus for driving LEDs using high voltage includes two LED driving circuits and two switches that can be turned on or off by a universal controller so as to connect the two LED driving circuits in two different configurations. When the input voltage is in a range from rectified 90 volt AC to rectified 140 volt AC, the two switches are controlled in such a way that the two LED driving circuits are connected in parallel. When the input voltage Vis in a range from rectified 180 volt AC to rectified 265 volt AC, the two switches are controlled to connect the LED segments of the LED unit in one LED driving circuit in series with the other LED driving circuit.

An LED-based lighting apparatus comprises a rectified AC voltage source having a rectified output connected to a storage capacitor through a switching device, a plurality of LED segments controlled by a linear driving circuit and at least one charging path connected between the LED segments and the storage capacitor. One or more controllable linear LED driving units may be connected in parallel with the storage capacitor to provide balance between reducing flicker and increasing power factor of the lighting apparatus.

Low flicker LED driving circuit with high power factor

An apparatus comprises red, green and blue LED strings each having a corresponding switching circuit. Each LED string is divided into a plurality of LED segments. The three LED strings are connected in parallel or in series. Each LED string may be connected in series with a respective current source or share a common current source. A controller controls each switching circuit so that the number of LED segments connected in series in the red, green or blue LED string can be respectively controlled according to a color setting signal and the voltage level of an input voltage. A first control method is provided for controlling the apparatus having a constant input voltage and a second control method is provided for controlling the apparatus having a periodically time-varying input voltage.

Apparatus for driving multi-color LED strings

An apparatus for driving LEDs using high voltage includes a plurality of LEDs divided into a plurality of LED segments connected in series with a switching voltage detector and a current limiting device. Each of the plurality of LED segments is connected in parallel with a switching device. A high input voltage supplies power to the apparatus. The switching voltage detector generates a first mode change signal when the input voltage increases and a second mode change signal when the input voltage decreases. A switch controller receives the two mode change signals and generates a plurality of switching control signals to respectively control the switching devices of the plurality of LED segments.

Apparatus for driving LEDs using high voltage

An LED-based lighting apparatus includes a plurality of LED-based lighting segments connected in series with a current control device. Each lighting segment has at least one LED-based lighting unit connected in series. A plurality of switch controllers controlled by a switching voltage comparator unit is connected with the plurality of LED-based lighting segments to provide multiple operation modes for turning on different number of LED-based lighting segments. In one embodiment, each switch controller is connected in parallel with a corresponding segment. The switching voltage comparator unit generates a propagation signal that propagates through and controls the plurality of switch controllers. In the other embodiment, each switch controller is connected between a positive end of the corresponding segment and a current control device. The switching voltage comparator unit generates two propagation signals that propagate through and control the plurality of switch controllers.

Apparatus for driving a plurality of segments of LED-based lighting units

An apparatus for driving LEDs using high voltage includes a plurality of LEDs divided into a plurality of LED segments connected in series and a plurality of three-terminal voltage controlled current limiting devices. Each of the current limiting devices is associated with one of the LED segments and has a first terminal connected to a negative end of the associated LED segment, a second terminal applied with a bias voltage and a third terminal connected to a common node. A current source is connected between the common node and ground. A power-loss reduction circuit having a plurality of LEDs controlled by an LED controlling circuit may further be inserted between the common node and the current source to reduce the power loss in the current source because of the high voltage at the common node.

A plurality of LED-based lighting units is segmented into a plurality of LED-based lighting segments connected in series. Each lighting segment has a plurality of LED-based lighting units connected in series with at least a series-connection switch, and a bypass-connection switch is connected in parallel with the series of LED-based lighting units. The total number of LED-based lighting units can be determined by a maximum voltage level of an input voltage supply and the forward voltage of the LED-based lighting unit for achieving optimal efficiency. The number of lighting segments and the number of lighting units in each lighting segment are properly chosen based on the total number of the LED-based lighting units in such away that any number up to the total number of all the LED-based lighting units can be connected in series by respectively controlling the series-connection switch and the bypass-connection switch of each LED-based lighting segment.

Methods and apparatus for segmenting and driving LED-based lighting units

A plurality of switching units interleaves with a plurality of LED-based lighting units to configure the interconnection of the LED-based lighting units for providing multiple lighting modes. Each switching unit disposed between a leading lighting unit and a trailing lighting unit is separately controlled by a controller. The switching unit can be configured to connect the two LED-based lighting units in parallel or in series, or to bypass the leading LED-based lighting unit. All the LED-based lighting units are connected in series when an input voltage supply is at a maximum voltage level, and connected in parallel when the input voltage supply is at a minimum voltage level. As the input voltage level decreases, the number of LED-based lighting units connected in parallel increases, and vice versa.

Methods and apparatus for driving LED-based lighting units

A DC-DC converter includes a temperature compensation circuit arranged between a feedback differential amplification circuit and an output voltage detection circuit to compensate the variation of the voltage level of the DC output voltage of the converter caused by ambient temperature changes. The temperature compensation circuit includes a temperature detection circuit that detects the ambient temperature and, in response thereto, generates a temperature signal; and a current source circuit that is connected between a feedback signal input terminal of the feedback differential amplification circuit and the output voltage detection circuit. The current source circuit, based on the temperature signal, generates an electrical current and a compensation voltage proportional to the electrical current. The compensation voltage is applied to the DC output voltage to thereby regulate the voltage level of the DC output voltage. The temperature signal is a temperature signal of positive temperature characteristics and/or a temperature signal of negative temperature characteristics.

DC-DC converter with temperature compensation circuit

A constant current regulator includes a current sensing circuit loop connected to a switch unit of the constant current regulator to detect a current flowing through the switch unit and to generate a detection current that is in proportion to the current flowing through the switch unit. The detection current flows through a detection resistor to induce a detection voltage. A differential amplifier bases on a set voltage and the received detection voltage to generate an error voltage to a pulse width modulation controller, which in turn causes a gate driver circuit to control the switching operation of the switch unit thereby supplying a constant current to a load connected to an output voltage of the regulator.

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Hsinchu County, Taiwan

Hung-Chi Chu