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Noise Compensation for Liquid Crystal Display

IP.com Disclosure Number: IPCOM000114967D
Original Publication Date: 1995-Feb-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 4 page(s) / 65K

Publishing Venue

IBM

Related People

Ishikawa, T: AUTHOR [+3]

Abstract

In Liquid Crystal Display (LCD) monitors which can be directly attached to the analog video interface of PC/Workstation, several types of noises are observed on LCD panel due to changing analog signals to digital signals. These noises are caused by quantization error, thermal drift of devices, ripple noise on video signal from PC/Workstation, etc. This algorithm aims to reduce such noises.

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Noise Compensation for Liquid Crystal Display

      In Liquid Crystal Display (LCD) monitors which can be directly
attached to the analog video interface of PC/Workstation, several
types of noises are observed on LCD panel due to changing analog
signals to digital signals.  These noises are caused by quantization
error, thermal drift of devices, ripple noise on video signal from
PC/Workstation, etc.  This algorithm aims to reduce such noises.

To realize this algorithm, the following variables are defined:
  Video-in:  Output of Analog to Digital Converter (ADC),
              input of this algorithm.
  Video-out: Output of this algorithm.
  Diff:      To accumulate video-level deferences between current
              frame and previous frame.  Diff absorbs noises.  (Fig.
1)

Concept of this algorithm is as follows.
  1.  Aim at certain dot and calculate Diff.  Even if Video_in is
       changed, as long as Diff is within certain range (Threshold A,
       Th A in Fig. 2), Video_out keeps its value.
  2.  In case Video_in is changed more than certain level (Threshold
B,
       Th B in Fig. 2), Video_out is changed to the new level.  And
DIff
       will be calculated from start.

      Fig. 2 shows an example of application.  Although there is some
noise on Video_in signal, noise on Video_out signal is reduced by
this algorithm.

      Figs. 3 and 4 show algorithm for one dot.  To reduce noises...