hd66765 Renesas Electronics Corporation., hd66765 Datasheet - Page 67

• Manufacturer Part Number: hd66765
• Description: 396-channel Segment Driver With Internal Ram For 4096-color Displays - Hitachi Semiconductor
• Manufacturer: Renesas Electronics Corporation.

n-raster-row Reversed AC Drive
The HD66765 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 64 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.
B-pat t ern
wa veform drive
• 1/80 duty
C- pat tern
wav eform drive
• 1/80 duty
• 11-raster-row
• Without EORs
C- pat tern
wav eform drive
• 1/80 duty
• 11-rast er-row
• With EORs
reversal
revers al
Note: Specify the numb er of AC drive raster-rows and the necess ity of EOR so that the DC bias is not generated f
the liquid crys tal.
Figure 50 Example of an AC Signal under n-raster-row Reversed AC Drive
1 2 3 4 5 6 7 8 9 10 11 12 13
1 frame
67
79 80 1 2 3 4 5 6 7 8 9 10 111213
1 frame
HD66765
79 80 1 2 3