Browse Prior Art Database

Video Bandwidth Optimization Using Monitor ID Bits

IP.com Disclosure Number: IPCOM000102298D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 38K

Publishing Venue

IBM

Related People

Morrish, AJ: AUTHOR [+2]

Abstract

This article describes a method of optimizing the Radio Frequency Interference (RFI) of monochrome and colour display monitors. Excessive slew rates on low frequency monitors are avoided.

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This is the abbreviated version, containing approximately 89% of the total text.

Video Bandwidth Optimization Using Monitor ID Bits

       This article describes a  method of optimizing the Radio
Frequency Interference (RFI) of monochrome and colour display
monitors.  Excessive slew rates on low frequency monitors are
avoided.

      This scheme is a control circuit which optimizes the video
bandwidth of a monitor in order to minimize RFI and maximize
performance.  It is achieved by testing the monitor ID bit
assignments, which enable the system unit to recognize monitor types,
and then to modify the video data to optimize performance to suit
that particular monitor.

      Due to the physical nature of monchrome to colour CRTs, the
slew rate of the video pulse must differ.  In order to maximize spot
performance on mono CRTs, high slew rates and narrow pulse widths can
be used in order to optimize a single pel.

      On monochrome CRTs spot size is small (<0.5 mm); on colour CRTs
spot size is larger (approx l mm)) and longer pulse widths can be
used without detriment to the spot size visible on the CRT.  Thus a
single interface can drive different frequency monitors without
excessive slew rates on low frequency monitors.

      The scheme hardware shown in the figure monitors the ID bit
status of the interface to recognize the type of communicating
monitor.  It then enables a suitable pulse-shaping/pulse-width
circuit, such as variable cut-off frequency filters, to modify the
video pulse bandwidth e.g., slope and width.  Thi...