回描周期 meaning in English

flyback period
retrace period

The driver waits for the vertical retrace period
驱动程序需要等待垂直回描周期。
The driver waits for the vertical retrace period the runtime will beam trace to prevent tearing
驱动程序需要等待垂直回描周期（运行库将实施跟踪以防止脱节）。
No attempt is made to synchronize the copy with the vertical retrace period of the display adapter , so tearing effects may be observed
由于没有尝试使复制与显示适配器的垂直回描周期同步，因此，可能会看到图像撕裂效果。