HD66760 Datasheet, PDF (69/105 Pages) Hitachi Semiconductor – 104 X 80-dot Graphics LCD Controller/Driver for 256 Colors

HD66760
n-raster-row Reversed AC Drive
The HD66760 supports not only the LCD reversed AC drive in a one-frame unit (B-pattern waveform) but
also the n-raster-row reversed AC drive which alternates in an n-raster-row unit from one to 32 raster-rows
(C-pattern waveform). When a problem affecting display quality occurs, such as crosstalk at high-duty
driving of more than 1/64 duty, the n-raster-row reversed AC drive (C-pattern waveform) can improve the
quality.
Determine the number of raster-rows n (NW bit set value + 1) for alternating after confirmation of the display
quality with the actual LCD panel. However, if the number of AC raster-rows is reduced, the LCD alternating
frequency becomes high. Because of this, the charge or discharge current is increased in the LCD cells.
1 frame
1 frame
1 2 3 4 5 6 7 8 9 10 11 12 13
79 80 1 2 3 4 5 6 7 8 9 10 11 12 13
79 80 1 2 3
B-pattern
waveform drive
• 1/80 duty
C-pattern
waveform drive
• 1/80 duty
• 11-raster-row
reversal
• Without EORs
C-pattern
waveform drive
• 1/80 duty
• 11-raster-row
reversal
• With EORs
Note: Specify the number of AC drive raster-rows and the necessity of EOR so that the DC bias is not generated for
the liquid crystal.
Figure 47 Example of an AC Signal under n-raster-row Reversed AC Drive