Browse Prior Art Database

Separated Common Electrodes

IP.com Disclosure Number: IPCOM000116129D
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Tokuda, T: AUTHOR

Abstract

Disclosed is an idea that reduces power consumption and electro-magnetic noise of Thin Film Transistor - Liquid Crystal Display (TFT-LCD) which is drived by one horizontal line inversion.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 87% of the total text.

Separated Common Electrodes

      Disclosed is an idea that reduces power consumption and
electro-magnetic noise of Thin Film Transistor - Liquid Crystal
Display (TFT-LCD) which is drived by one horizontal line inversion.

      Fig. 1 shows conventional structure of a common electrode and
its drive wave form of one horizontal line inversion.  In this case,
voltage level of a common electrode is periodically changed at each
line scanning (each horizontal drive period).  The number of voltage
alternation in a frame period is the same as that of total display
lines.  (In this article, no voltage alternation is assumed during
vertical blanking time.)  At this rate, power loss and switching
noise occurs by voltage alternation of a common electrode which has
relatively large load capacitance in the TFT-LCD.

      Fig. 2 shows new structure of common electrodes and its drive
wave form.  A common electrode is separated into two common electrode
(A) and (B) like a pair of combs.  This separation corresponds to the
required voltage alternation.  With this new structure, only one time
voltage alternation in a frame period is required to achieve the
equivalent drive in the above mentioned conventional common
electrode.  Therefore, the loss at charge and discharge of common
electrodes decreases to 1 / (The number of total display lines) of
that of the conventional method.  Electro-magnetic switching noise
coming from the common electrode voltage alternation also d...