Patent ID: 6239716
Filing Date: 2001-05-29
Classification: G09G,H05B,Y02B,Y10S

Abstract:
An optical display device with a set of LEDs which are connected in series or in parallel, said optical display device comprising:a set of LEDs comprising a matrix, said matrix comprising at least one column of at least one LED, with the LEDs in each column being connected in series and the columns being connected in parallel,first control circuit means which are connected to at least each column and act as a controllable current source to set a constant current through the corresponding column(s),logic circuit means for delivering different clock pulses with different frequencies to the first control circuit means for cyclic switching of at least one LED to generate signals that are visible to the human eye and at the same time signals that are not visible to the human eye, andsecond control circuit means connected to the matrix and the first control circuit means, for acting as a controllable voltage source to adjust the voltage across the LEDs as a function of the current injected.