An ambient light sensor produces a current signal that varies linearly with the level of ambient light. The current signal is multiplied by a user dimming preference to generate a brightness control signal that automatically compensates for ambient light variations in visual information display systems. The multiplying function provides noticeable user dimming control at relatively high ambient light levels.

Method and apparatus to control display brightness with ambient light correction

An illumination control circuit allows a user to set a desired brightness level and maintains the desired brightness level over temperature and life of a light source. The illumination control circuit uses a dual feedback loop with both optical and thermal feedbacks. The optical feedback loop controls power to the light source during normal operations. The thermal feedback loop overrides the optical feedback loop when the temperature of the light source becomes excessive.

Optical and temperature feedbacks to control display brightness

A lamp inverter with continuous strike voltage facilitates faster striking of a fluorescent lamp, especially at cold temperatures. A frequency sweep generator sweeps the frequency of the lamp inverter to a striking frequency corresponding to a striking lamp voltage and then maintains the striking frequency until the lamp strikes.

Apparatus and method for striking a fluorescent lamp

An apparatus and method for driving a lamp are provided. In one embodiment, an inverter having four switching elements is split into two inverter arms that are deployed at separate terminals of a floating lamp structure to achieve even light output. A controller drives both inverter arms such that power switching lines do not cross the floating lamp structure. In one embodiment, the controller adjusts the brightness of the lamp structure by adjusting the phase difference between outputs of a first inverter arm relative to a second inverter arm. In one embodiment, the controller adjusts the brightness by symmetrically pulse width modulating the outputs of the first inverter arm and the second inverter arm.

Split phase inverters for ccfl backlight system

A backlight intensity for a transflective display increases proportionately with increasing ambient light levels for a first range of ambient light levels and decreases proportionately with increasing ambient levels for a second range of ambient light levels to improve power efficiency. The second range of ambient light levels is higher than the first range of ambient light levels.

Dual-slope brightness control for transflective displays

The present invention relates to a discharge lamp lighting apparatus in which overshoot occurring when the polarity of AC rectangular wave voltage/current is inverted is suppressed. An inverter converts DC power supplied by a converter to AC rectangular wave power and outputs the AC rectangular wave power. A power calculation unit generates a power detection signal based upon a voltage detection signal and a current detection signal detected on the output side of the converter. A control target value setting unit outputs an output power command value to be used to control the DC power so as to achieve a target value. A correction signal generation unit outputs a correction signal to be used to correct the output power command value in conformance to the power detection signal in synchronization with a polarity inversion of the AC rectangular wave power. A converter control signal generation unit outputs a signal corresponding to the error of the power detection signal relative to the output power command value. A pulse width control unit implements pulse width control on the converter based upon the signal provided by the converter control signal generation unit.

Discharge lamp lighting apparatus

The present invention relates to a discharge lamp lighting method and a discharge lamp lighting apparatus that achieve a reduction in the extent of lamp flickering by adopting a relatively simple circuit structure. A power supply unit 1 supplies AC power (Po) to a discharge lamp 3, and a control unit 2 implements control on the power supply unit 1 so as to gradually increase the instantaneous value of the AC power (Po) during a half cycle (τ/2) of an AC pulse current (Io) as the time elapses from the rise of the half cycle (τ/2) toward an end of the half cycle.

Discharge lamp lighting method and discharge lamp lighting apparatus

The present invention relates to a switching power supply apparatus equipped with an over-temperature protection circuit that operates appropriately even when a problem occurs in the control circuit A switching conversion circuit 2 has a switching element 21 turned on and off according to a drive signal S 5 supplied from a drive circuit 5 , converts the voltage supplied via a input circuit 1 to switching output, and outputs that switching output An output circuit 3 is supplied with the switching output, adjusts the supplied switching output to a prescribed output, and outputs that prescribed output A control circuit 4 supplies a control signal S 4 to the drive circuit 5  An over-temperature protection circuit 6 comprises a temperature detector 61 and a switch 62 , and is connected to the control electrode of the switching element 21 , and cuts off the drive signal S 5 via the switch 62 when the temperature detector 61 detects an abnormal temperature in the switching power supply apparatus

Switching power supply apparatus

The present invention relates to a switching power supply apparatus equipped with an over-temperature protection circuit that operates appropriately even when a problem occurs in the control circuit. A switching conversion circuit 2 has a switching element 21 turned on and off according to a drive signal S5 supplied from a drive circuit 5, converts the voltage supplied via a input circuit 1 to switching output, and outputs that switching output. An output circuit 3 is supplied with the switching output, adjusts the supplied switching output to a prescribed output, and outputs that prescribed output. A control circuit 4 supplies a control signal S4 to the drive circuit 5. An over-temperature protection circuit 6 comprises a temperature detector 61 and a switch 62, and is connected to the control electrode of the switching element 21, and cuts off the drive signal S5 via the switch 62 when the temperature detector 61 detects an abnormal temperature in the switching power supply apparatus.

Switching power supply apparatus with over-temperature protection

PROBLEM TO BE SOLVED: To provide a switching power supply comprising an excessive temperature protective circuit operating appropriately even if a control circuit is in a abnormal state. SOLUTION: A switching conversion circuit 2 comprises a switching element 21 being turned on/off by a drive signal S5 supplied from a drive circuit 5 and outputs a voltage being supplied through an input circuit 1 while converting the voltage into a switching output. The switching output is supplied to an output circuit 3 and outputted after being regulated into a specified output. A control circuit 4 supplies a control signal S4 to the drive circuit 5. An excessive temperature protective circuit 6 comprising a temperature detecting section 61 and a switch section 62 is connected with the control electrode of the switching element 21 and interrupts the drive signal S5 through a switch section 22 when the temperature detecting section 61 detects an abnormal temperature of the switching power supply.

Yutaka Ishihara

Papers

Discharge lamp lighting apparatus

Discharge lamp lighting method and discharge lamp lighting apparatus

Switching power supply apparatus

Switching power supply apparatus with over-temperature protection

Switching power supply