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Frame Rate Conversion/Dither Control for Analog Input

IP.com Disclosure Number: IPCOM000112512D
Original Publication Date: 1994-May-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 4 page(s) / 82K

Publishing Venue

IBM

Related People

Ishii, K: AUTHOR [+3]

Abstract

Abstract: There are several products which display texts and graphic image to LCD Display. In some cases, the input from System unit is analog signal and the output to LCD panel driver is digital. At this case, the color number is limited by the LCD driver. If the LCD driver is 6 bit and original data has 8 bit, we have to reduce the number by some data processing. This paper describes the new implementation for data processing which eliminates the cost of A/D converter and size of logic. This method converts the input bits to output bits without high power A/D converter.

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Frame Rate Conversion/Dither Control for Analog Input

      Abstract: There are several products which display texts and
graphic image to LCD Display.  In some cases, the input from System
unit is analog signal and the output to LCD panel driver is digital.
At this case, the color number is limited by the LCD driver.  If the
LCD driver is 6 bit and original data has 8 bit, we have to reduce
the number by some data processing.  This paper describes the new
implementation for data processing which eliminates the cost of A/D
converter and size of logic.  This method converts the input bits to
output bits without high power A/D converter.

      Conventional Technique: At conventional method (Fig. 1-1), the
analog video data which contains 8 bits color for each R/G/B is
converted to 8 bits(x3) digital data through A/D converter.  Then
this data are rounded to each 6 bits by Frame Rate Conversion (FRC)
or some Dither conversion.  For this implementation, we need
expensive 8 bit high speed A/D converter and high speed 8 to 6 bit
conversion logic.

      Objectives: This new implementation reduces the chip size of
A/D converter to 1/4, its power consumption to 1/4, also the size of
digital conversion circuit to 1/4 and its power to 1/4.  Then it
makes possible to reduce total cost to 1/4.

      For new implementation, only 6 bit A/D converter and some logic
make the same data conversion as conventional one (Fig. 1-2).

      Contents: At a conventional FRC, the 8 bits video data which is
digital-converted through A/D chip is added at FRC/Dither circuit
with small number which corresponding to its place and time and then
rounded to 6 bits data.  Fig. 1-3 shows one typical FRC pattern.  The
frame rate of LCD is 60kHz and any one dot on screen is calculated
each 17msec and displayed.  For example, if the video da...