DPMS

4/21/2001

Display Power Management System - DPMS: DPMS allows a computer to put a monitor into power saving modes by manipulating the monitor synchronization signals. Monitors, unlike Television, are fed by separate horizontal and vertical synch signals lines. Thus it is very easy to present the monitor with four states. Both synch signals; horizontal synch only; vertical synch only; Neither.

If both synch signals are present, the monitor is in Normal operation where it will dissipate 60 to 140 watts.

If the horizontal synch is suppressed, but the vertical synch remains, the monitor is placed in "Standby" or "screen saver" mode with the color guns off but all other circuitry working. The drops monitor power requirements by 10% or more. It takes several seconds for the picture to return when horizontal synch is restored. "Screen Saver" mode has absolutely nothing to do with screen savers that pop up when the computer is unused.

If the horizontal synch is present, but the vertical synch is suppressed, the monitor is placed in "Suspend" mode with the power supply off but with power provided to the CRT filaments. Power savings are up to 90%. Recovery requires several seconds.

If both synchronization signals are removed, the monitor will shut down except for a monitoring circuit that draws a few watts (Inactive Mode). Recovery time will be about 10 seconds.

At least one monitor vendor (CTX) provides a non-DPMS power saving mode called RGB. In RGB mode, if no signal is seen at any of the color guns for some specified time the monitor shuts down.

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