0704833-A2 is referenced by 11 patents and cites 5 patents.

Electromagnetic interference ("EMI") generated by a flat panel video display system is reduced by periodically phase-modulating the panel clock. This spreads EMI energy associated with each panel clock harmonic by a frequency amount DELTA f proportional to the rate of phase change in the panel clock signal. EMI energy associated with each panel clock harmonic is reduced relative to a square-wave panel clock signal because the same energy is now spread over a group of frequencies centered about each harmonic. The phase of the panel clock is changed at a rate exceeding the bandwidth fm of a standard EMI measurement reference window. This disperses adjacent spectral energy sufficiently so the reference window measures but one, decreased, amplitude at a time.; Phase-modulation may be achieved using a clock pulse dropping circuit that receives a square-wave input of frequency Nfc from a main oscillator, drops at least one clock pulse out of a stream of M clock pulses, and frequency divides the resultant waveform by N. The resultant panel clock will have two phases, wherein rate of phase change DELTA f is Nfc/2M. The spectral spacing DELTA f of sidebands around each harmonic in the EMI spectrum changes as a function of DELTA f. Measured EMI is reduced when DELTA f = Nfc/2M > fm.

Title
Method and apparatus for reducing electromagnetic interference radiated by flat panel display systems
Application Number
EP19950115200 19950927
Publication Number
0704833 (A2)
Application Date
September 27, 1995
Publication Date
April 3, 1996
Inventor
Kurihara Steven M
US
Rindal Abraham E
US
Assignee
Sun Microsystems
US
IPC
G09G 03/20
H04B 15/02
G09G 05/18
G09G 05/00
G09G 03/20
H04B 15/04
G09G 05/18
G09G 05/00
G09G 03/20
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