公开(公告)号：EP0785681A2

公开(公告)日：1997-07-23

申请号：EP97300285.0

申请日：1997-01-17

申请人： SUN MICROSYSTEMS, INC.

发明人： Rindal, Abraham E. ,  Ih, Ronald H. ,  Law, Michele, K.

IPC分类号： H04N5/65 ,  H01J29/86

CPC分类号： H04N5/21 ,  H01J2229/0015

摘要： Electromagnetic interference ("EMI") is reduced in a CRT video display system by spreading-out the EMI-producing spectra present in the video pixel data and/or clock signals. A clock dropping circuit coupled between the display generator main oscillator and the timing generator periodically phase-modulates the timing generator clock signal such that it comprises N phases, where N≥2. As a result, each horizontal line of video data and the horizontal synchronization signals is phase shifted. This dual-shifting effect eliminates display image distortion that would result if only the video signal were shifted. Video distortion is further minimized by deriving the horizontal and vertical synchronizing signals from a common constant clock. EMI energy associated with each clock harmonic is spread by a frequency amount Af proportional to the rate of phase change in the clock signal, the rate of phase change exceeding half the bandwidth f m 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.

摘要翻译： 电磁干扰（“EMI”）是在CRT视频显示系统由铺展谱存在于视频像素数据和/或时钟信号的EMI产生减少。 耦接于显示发生器主振荡器和定时发生器周期性之间的时钟降压电路进行相位调制定时产生时钟信号搜索做到了包括N个相位，其中N≥2。 其结果是，视频数据和水平同步信号的每一水平行被相移。 这种双移效果省去显示图像失真做将导致如果仅视频信号被移位。 视频失真由从共同的恒定的时钟导出另外的水平和垂直同步信号最小化。 与每个时钟谐波相关联的EMI能量由频率量了Af正比于相变的在时钟信号的速率传播，相变超过标准测量EMI参考窗口的带宽FM一半的速率。 这充分地分散相邻的光谱能量，因此基准窗口的措施，但一个比下降，幅度在同一时间。