Discussion
A subpixel is controlled by applying or not applying a voltage between the column electrode and the
row electrode. This electric field naturally bows out into liquid crystal material in adjacent subpixels.
When this produces a visible effect, it is called crosstalk. Crosstalk is dramatically reduced when slightly
different voltages are used among adjacent subpixels.
Kyocera color STN LCDs larger than 3.8 inch size have internal circuits to divide the drive voltage into
differently biased groups. Page 1 of a full specification will say whether the LCD already includes a bias
voltage circuit. 3.8 inch and smaller LCDs require the customer to provide this circuit. The certain way to
determine if the customer must provide the bias circuit is to look at the interface signal table in section 8
of the full specification. If six signals named V0..V5 are shown, then the customer must provide different
voltages for them. In this case the full spec will also show the recommended bias voltage circuit with outputs
V0..V5, like the one shown below.
V0, V1 and V2 carry the LCD driving voltage of around 29 Volts. V3, V4 and V5 carry the ground of around 0 Volts.
The amount of bias voltage must be the same. This requirement is stated more exactly as:
|V0-V1| = |V1-V2| = |V3-V4| = |V4-V5|
Terminology can be confusing. The inputs to the circuit are named VEE and ground in the diagram below. But in
this circuit VEE = V0 and ground = V5. Section 5 Electrical Characteristics avoids the name VEE, instead calling
it V0-V5.
R3, R4 = 15.0k ohm ± 0.5%
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