Browse Prior Art Database

Display Power Management by Supply Rail Analysis

IP.com Disclosure Number: IPCOM000106460D
Original Publication Date: 1993-Nov-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Knox, A: AUTHOR

Abstract

Disclosed is a low cost power management facility which depends only on the screen content of a VDU being blanked and does not require the display to have a microprocessor or similar complex control device to trigger power shutdown.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 61% of the total text.

Display Power Management by Supply Rail Analysis

      Disclosed is a low cost power management facility which depends
only on the screen content of a VDU being blanked and does not
require the display to have a microprocessor or similar complex
control device to trigger power shutdown.

      To provide efficient Power Management of a display, a signal
denoting display usage finished is required.  There are at present
two methods identified:  system dependent via the sync signals in
line with the VESA proposals and system independent.  This disclosure
relates to a method whereby the display may perform simple power
management at minimal cost without recourse to extensive control and
detection methods in the display.

      There are many "screen saver" programs extant which, after a
preset interval, cause either a bitmap or blank screen to the
displayed.  This new solution uses screen blanking as a signal to the
display that power management is to be invoked.  When the screen is
blanked, the EHT current will fall to a low value.  It will not
necessarily drop to zero since there may be some bleed path to
discharge the CRT, i.e., a DC component to the beam current.  During
the display of characters however beam current will flow.  It is
proposed that this AC component be used as the monitoring signal for
the power management signal.  Supply rails other than EHT are also
suitable for this method providing that their AC ripple is linked to
video activity. ...