Browse Prior Art Database

Energy Recovery Method for a Liquid Crystal Display Source Driver

IP.com Disclosure Number: IPCOM000118889D
Original Publication Date: 1997-Aug-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Kobayashi, Y: AUTHOR [+2]

Abstract

Disclosed is an energy recovery method for Thin Film Transistor Liquid Crystal Displays (TFT LCDs). When a TFT LCD is driven by an analog source driver with a High Voltage (HV) inversion scheme, the driving voltage on even and odd data lines alternates in time and position. That is to say, at one instant, even data lines are positive and odd data lines are negative, and at the next instant, even data lines become negative and odd data lines become positive. One data line is electrically equivalent to one capacitor, which means that, by adding an extra coil, an electrical resonance circuit can be formed. This resonance circuit will effectively reverse the electrical charges of even and odd data lines, thus reducing the power consumption of the LCD.

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Energy Recovery Method for a Liquid Crystal Display Source Driver

      Disclosed is an energy recovery method for Thin Film Transistor
Liquid Crystal Displays (TFT LCDs).  When a TFT LCD is driven by an
analog source driver with a High Voltage (HV) inversion scheme, the
driving voltage on even and odd data lines alternates in time and
position.  That is to say, at one instant, even data lines are
positive and odd data lines are negative, and at the next instant,
even data lines  become negative and odd data lines become positive.
One data line is electrically equivalent to one capacitor, which
means that, by adding an extra coil, an electrical resonance circuit
can be formed.  This resonance circuit will effectively reverse the
electrical charges of even  and odd data lines, thus reducing the
power consumption of the LCD.

      The proposed energy recovery method requires an additional two
coils and four transistors.  At first, assume that data line is
positive, then TR1 is ON and the energy in the data lines is guided
to the coil1  until the voltage of the data lines becomes zero.
Then, TR1 is OFF and  Di1 is ON, and the energy in the coils
generates the negative voltage and drives the data lines to the
negative voltage.  In the next instance,  the data line is negative,
then TR2 is ON and the energy in the data lines is guided to the
coil2 until the voltage of the data lines becomes  zero.  Then, TR2
is OFF and Di2 is ON, and the energy in the coil2...