Abstract: A video display system such as a liquid crystal display television receiver projection system typically uses a high-intensity discharge lamp of the type that should not be re-started or turned on immediately after being turned off. An improved system protecting the lamp from restarts during a cooling off period. The system maintains the lamp, once energized to produce an image, in an off condition during a predetermined cool-down period following receipt of a power-off. Advantageously, the system automatically powers the lamp on at the end of the cool-down period upon receipt a power-on command during the cool-down period.

Abstract: A liquid crystal display television receiver projection system uses a controller responsive to a first signal by providing power to a first set of circuits of the system. The controller is responsive to a second signal by removing power from a second set of circuits of the system; A timer defines a time interval between an instance of a power off signal and an instance of a power on signal. In the event a user issues a power on command before the first interval has elapsed, power will be applied to circuits other than the lamp The lamp will remain de-energized until the first interval has elapsed. Therefore, a user is prevented from re-striking the lamp.

Abstract: Progressive rounding error and convergence error encountered due to multiple use of a center correction adjustment of an image of a video projection display is reduced by calculating a 3×3 matrix for a moved color signal where the non center matrix values represent the difference between the initially measured sensor values stored at initial alignment, and stored most recently measured sensor values. The matrix center value is the sum of the averaged values calculated from the edge center errors, the stored sum of previous moves and the current move. Rerun of the sensor finding routine resets the stored move sum to zero.

Abstract: Method for preventing a high voltage circuit form generating excessive high voltage, wherein the method comprises the following steps: a) reading a digital representation of a reference value associated with one of a plurality of operation modes stored in a memory; b) verifying the integrity of the representation of the reference value; c) providing a sensed signal representing the output voltage of the high voltage circuit; d) comparing the sensed signal with the reference value; e) inhibiting the generation of the high voltage output if the comparison in step (d) indicates excessive high voltage.

Abstract: A method of operating a photo sensor in a projection display device comprises the steps of, illuminating the sensor with a projected image. Detecting a signal from the sensor responsive to the illumination by the projected image. Changing a threshold value of the detector until the signal detection ceases. Storing a value representative of the threshold value which terminated detection of the signal from the sensor.

Abstract: Method for preventing a high voltage circuit form generating excessive high voltage, wherein the method comprises the following steps: