| 摘要 |
<p>PURPOSE:To omit the selection of light emitting elements for a light source to be attached to a CRT of a large caliber by driving the light emitting elements LED contiguous to each other in parallel with each other via a drive circuit consisting of the drive elements provided for each light emitting element and performing the simultaneous light emitting actions of those light emitting elements. CONSTITUTION:The LEDD 1a and D1b are set opposite and close to each other at the front edge of a CRT screen of an optical touch panel. A light emission control switch circuit 104 sweeps many outputs by the input control signal and secures the simultaneous conduction of a pair of drive transistors Q1a and Q1b to turn on the paired LEDD 1a and D1b. Thus two LEDs work equally to each other with a current kept within the maximum rated range of the LEDs even though these LEDs have some different characteristics from each other. As a result, the light emitting outputs of both LEDs can be increased equivalently and substantially to the double. Thus it is possible to omit the selection of LEDs and also to evade the increase of the overall power consumption of a touch panel device.</p> |
