PC Monitor DPMS specification explanation

The DPMS standard (Display Power Management Signaling) was developed to extend the useful life of PC monitors as well as to conserve the relatively high amount of energy used by monitors when not required.

In brief terms it works as follows.

The DPMS compliant video controller and the DPMS compliant monitor use the Horizontal sync and Vertical sync signals to control the power mode of the monitor. Because there are 2 signal lines, it allows 4 modes of operation. Normal, Standby, Suspend and Off. The DPMS compliant video card will toggle the sync lines on or off to select the power mode and the monitor will react as follows:

Horiz

Vert

Mode

ON

ON

Normal

OFF

ON

Standby---RGB guns off, power supply on, tube filaments energized, (screen saver mode)

ON

OFF

Suspend---RGB guns off, power supply off, tube filaments energized.

OFF

OFF

Pwr off----Small auxiliary circuit stays on to monitor the HS/VS signals to enable power on when data needs to be displayed on the screen.


Typical recovery times. (Picture on screen)

H-sync

V-sync

Power used

Recovery time

ON

ON

<120 watts*

None

OFF

ON

<110 watts

2-3 secs

ON

OFF

<15 watts

2-3 secs

OFF

OFF

<5 watts

8-10 secs

* The actual wattage will vary with the screen size of the monitor.

(14/15" = 85-100W----16/17" = 95-120W----20/21" = 110-140W )


Description of the Energy Star power management standard.

One monitor manufacturer (CTX) includes an RGB mode into their monitors for use with non DPMS compliant PC's. It works as follows:

NOTE! A DOS prompt will not enable the RGB mode as the C> prompt energizes the guns on each sweep.