To avoid incompatibility of measurement by illuminating a sensor by a projection image, detecting a signal from the sensor, changing the threshold of a detector until the detection of the signal is finished, and storing the value expressing a threshold which finished the detection of the signal from the sensor.
A video generator 310 is controlled by a control logic part 301 so as to generate a green block M at a prescribed sensor such as horizontal and vertical screen positions. Upon illuminating a sensor S1, electric charges generated by light work so that the sensor may show lower impedance to branch a larger current Isen from a reference current (Iref) and to separate a current Isw from a sensor detector 275. A sensor current is advantageous measured by a controllably increasing reference current Iref until switching the detector 275 in order to indicate that sensor illumination is lost. This current is processed as a prescribed threshold to the sensor and a color and is stored.
MCPEAK SEAN PATRICK
BURNETT ANGELA RENEE
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