초록 ▼

A detection circuit (30, 32) for carrying out a rapid search technique for locating the position of a stylus (12) relative to a display screen (10). A microprocessor (34) and related components select a group of light detectors (20, 28) that are positioned near the display screen (10). The summed ou

A detection circuit (30, 32) for carrying out a rapid search technique for locating the position of a stylus (12) relative to a display screen (10). A microprocessor (34) and related components select a group of light detectors (20, 28) that are positioned near the display screen (10). The summed output current of the selected group of detectors (20, 28) is monitored to determine whether the output of any detector in the selected group is reduced because of the presence of a stylus (12). Whenever the selected group shows such reduction in output current, that selected groups is divided into two subgroups. The subgroup having reduced current output due to the presence of the stylus (12) is further divided until the particular detector(s) having reduced output current is found, the position of the detector is correlated to the location of the stylus (12) relative to the screen (10).

대표청구항 ▼

In an optical touch panel system having a light source for directing light toward plural light detector elements that each generate an analog output signal representing the amount of light received from the light source, an amount of light less than a predetermined threshold representing a selected

In an optical touch panel system having a light source for directing light toward plural light detector elements that each generate an analog output signal representing the amount of light received from the light source, an amount of light less than a predetermined threshold representing a selected location on the touch panel, a method for identifying the selected location, comprising: designating a group of the light detectors as a sampling group; forming a summed output signal with a magnitude representing a sum of the amplitudes of the analog output signals generated by the light detector elements in the sampling group; comparing the summed output signal to a reference output signal having a magnitude representing a sum of the amplitudes of the analog output signals generated by the light detector elements in the sampling group when they all receive the light from the light source; and whenever the magnitude of the summed output signal differs from the magnitude of the reference output signal by more than a predetermined signal difference, dividing the sampling group of light detectors into a subgroup and designating it as a sampling group.