Browse Prior Art Database

Method of Preventing Users from Damaging Connectors on VESA Display Data Channel Compliant Monitors

IP.com Disclosure Number: IPCOM000116690D
Original Publication Date: 1995-Oct-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Church, J: AUTHOR [+2]

Abstract

Described is a technique that may be utilized to prevent users from damaging the interface cable connector ('15-pin D-shell') when attaching a DDC2AB compliant monitor to certain non DDC2AB compliant PCs.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Method of Preventing Users from Damaging Connectors on VESA Display
Data Channel Compliant Monitors

      Described is a technique that may be utilized to prevent users
from damaging the interface cable connector ('15-pin D-shell') when
attaching a DDC2AB compliant monitor to certain non DDC2AB compliant
PCs.

      A current area of development for PCs is directed to avoiding
the present need for users to configure their PCs.  The PC will be
able to identify automatically the capabilities of its internal
expansion/video cards, external printers, monitors etc. and will
automatically optimize its set-up to take fullest advantage of these
capabilities.  For monitors, this typically means automatically
running at the highest refresh rate supported at a particular screen
resolution.  This is achieved by the monitor transmitting data to the
PC via the connecting interface cable, using a protocol such as that
defined in VESA's Display Data Channel (DDC) standard.  DDC has a
number of different levels, ranging from simple one-way
communications from the monitor to the PC to full two-way
communications, allowing many of the monitor's functions to be
controlled directly from the PC.  The level of primary interest in
this disclosure is DDC2AB.  'AB' stands for 'Access Bus', the basis
for communications between the PC and the monitor.  One feature of
the bus is that peripherals must be able to detect bus power
disappearing and then reset themselves.  In order to do this, it is
necessary to monitor the Access Bus +5V supply, generated in the PC.
How does the DDC2AB monitor achieve this since +5V is not usually
transmitted from the PC to the monitor?  The VESA standard calls for
the PC to use a previously unused line in the monitor's 15-pin
D-shell connector ie pin 9.  This is the basis for the problem.  The
DDC2AB standard calls for the monito...