Abstract: An LED backlight structure for setting voltages and currents for LEDs. Red LEDs are connected in series between a first voltage regulator and a first controllable current source, green LEDs are connected in series between a second voltage regulator and a second controllable current source, blue LEDs are connected in series between a third voltage regulator and a third controllable current source. The current sources may be linear current regulators controlled to balance the three colors to achieve a target light output of the board using a light detection chamber. PWM controllers control transistor switches connected in parallel across groups of LEDs, where the duty cycles set the average current through each group of LEDs. The control values used to achieve target light characteristics are stored in memory. The PWM controller may control brightness levels of the LEDs. The backlight may be for an LCD television.

Abstract: An LED backlight structure and technique for setting the voltages and currents for the LEDs are described. In one embodiment, red LEDs are connected in series between a first voltage regulator and a first controllable current source, green LEDs are connected in series between a second voltage regulator and a second controllable current source, and blue LEDs are connected in series between a third voltage regulator and a third controllable current source. The current sources may linear current regulators. After all the LEDs are mounted on a printed circuit board, each voltage regulator is controlled so that there is a minimum voltage drop across the current source to minimize energy dissipation by the current source. Also, after all the LEDs are mounted on the printed circuit board, the current sources are controlled to balance the three colors to achieve a target light output of the board using a light detection chamber.

Abstract: A measurement device measures voltage/current characteristics of a device under test (DUT) and suppresses spikes and overshoots which appear in an output when voltage and current settings fed to the DUT are changed, and makes possible rapid setting changes. The measurement device has a V holding loop which contains a capacitor, an error amplifier, an FET switch, a voltage-current converter, an integrator, a power amplifier, a current ranging circuit and a buffer amplifier. During ordinary operation of the circuit, the FET switch is on and the output voltage is remembered by the capacitor. When the voltage-current settings are changed, the FET switch is off, the feedback circuit of the V holding loop is formed, and the value of the output voltage immediately before the changes were performed is held, on the basis of the voltage of the capacitor.

Abstract: An exhaust device for a working machine in which a mixing tubular member is disposed opposite to an outlet opening of the muffler through a space interposed between them, and an air-flow passage is provided to introduce a portion of pressurized air from a blower into the inside of an air guide wall on the outer periphery of the outlet opening.