초록 ▼

A touch panel system using modulated light beams to enable the system to detect when one or more of the light beams are blocked even in bright ambient light conditions. The system has a “touch sensitive”display surface with a defined perimeter. Surrounding the display surface are a multiplicity of l

A touch panel system using modulated light beams to enable the system to detect when one or more of the light beams are blocked even in bright ambient light conditions. The system has a “touch sensitive”display surface with a defined perimeter. Surrounding the display surface are a multiplicity of light emitting elements and light receiving elements. These elements are located so that the light paths defined by selected pairs of light emitting and light receiving elements cross the display surface and define a grid of intersecting light paths. A scanning circuit sequentially enables selected pairs of the light emitting and light receiving elements, modulating the amplitude of the light emitted in accordance with a predetermined pattern. A filter generates a blocked path signal if the currently enabled light receiving element is not generating an output signal modulated in accordance with the predetermined pattern. Finally a computer is used to determine if an object is adjacent to the display surface and the location of the object, by determining if the filter is generating at least two blocked path signals corresponding to light paths which intersect each other within the perimeter of the display surface. A failure detection circuit for testing the LEDs and phototransistors, by checking for blocked LED/phototransistor pairs. When a blocked pair is found the phototransistor of the blocked pair is paired with an LED near the blocked LED and the block LED is paired with a photo-transistor near the blocked LED to determine if they have failed.

대표청구항 ▼

A method of locating the position of an object adjacent to a display surface having a defined perimeter, the steps of the method comprising: providing a multiplicity of light emitting elements and light receiving elements; said elements located so that the light paths defined by selected pairs of li

A method of locating the position of an object adjacent to a display surface having a defined perimeter, the steps of the method comprising: providing a multiplicity of light emitting elements and light receiving elements; said elements located so that the light paths defined by selected pairs of light emitting and light receiving elements cross said display surface and define a grid of intersecting light paths thereon; sequentially energizing selected pairs of said light emitting and light receiving elements; generating a blocked path signal when the currently enabled light receiving means does not receive the light emitted from the currently enabled light emitting means; and testing the operability of a selected one of said elements by performing the steps of: enabling said selected element and a complementary element across said display surface from said selected element, and testing for the presence of a blocked path signal; enabling the same complementary element and a second element of the same type as said selected element and which is located near said selected element, and testing for the presence of a blocked path signal; and denoting the detection of a component failure if a blocked path signal is detected when said selected element is enabled, but no blocked path signal is detected when said second element is enabled.