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Inverter Driving Method for Noise Cancel in Liquid Crystal Display

IP.com Disclosure Number: IPCOM000117445D
Original Publication Date: 1996-Feb-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 4 page(s) / 68K

Publishing Venue

IBM

Related People

Kimura, Y: AUTHOR [+3]

Abstract

Disclosed is a device for controlling a frequency of Cold Cathode Fluorescent Lamp (CFL) driving circuit of the backlight power unit (inverter) in Liquid Crystal Display (LCD). To control this driving frequency, CFL frequency and horizontal synchronous (H-sync) frequency in LCD screen are not synchronized each other. According to this method, it is possible to cancel the interference noise in LCD screen.

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Inverter Driving Method for Noise Cancel in Liquid Crystal Display

      Disclosed is a device for controlling a frequency of Cold
Cathode Fluorescent Lamp (CFL) driving circuit of the backlight power
unit (inverter) in Liquid Crystal Display (LCD).  To control this
driving frequency, CFL frequency and horizontal synchronous (H-sync)
frequency in LCD screen are not synchronized each other.  According
to this method, it is possible to cancel the interference noise in
LCD screen.

      This method achieves automatic CFL frequency control, and
interference noise in LCD screen is cancelled.
  1.  Fig. 1 shows a inverter of the backlight.  The control signal
of
       H-sync frequency is inputted to the inverter from LCD module.
       This inverter has several CFL driving circuits (Royer
circuits).
       One of Royer circuits receives the above control signal from
LCD.
       By this control signal, this inverter sets best circuit of CFL
       frequency which CFL and H-sync frequency are not synchronized
       each other.
  2.  Fig. 2 shows a Royer circuit of the inverter.  This inverter
has
       several capacitors on Royer circuit, and receives the control
       signal from LCD.  By this control signal, this inverter sets
best
       capacitor which CFL and H-sync frequency are not synchronized
       each other.  Therefore, the interference noise in LCD screen
is
       cancelled.
  3....