9-5
(2-2) Left-right Asymmetrical Correction (LIN coil)
In the circuit shown in Fig. 6 , the deflection coil current
iH does not flow straight as shown by a dotted line in the
figure if the linearity coil does not exist, by flows as
shown by the solid line because of effect of the diode for a
first scanning (screen left side) and effect of resistance of the
deflection coil for later half period of scanning (screen right
side). That is, the deflection current becomes a sawtooth
current with bad linearity, resulting in reproducing of
asymmetrical pictures at left and right sides of the screen (left
side expanded, right side compressed).
When a horizontal linearity coil LI with a current characteristic
as shown in figure is used, left side picture will be
compressed and right side picture will be expanded because
the inductance is high at the left side on the screen and low
at the right side. The left-right asymmetrical correction is
carried out in this way, and pictures with good linearity in
total are obtained.
Fig. 6 Linearity coil
TR
D
Co
L
H
FBT
iH
L
I
Vcc
Cs
Deflection
coil
S-character
capacitor
Deflection coil current
Deflection coil current
Resistance of L
H
Characteristic of D
Linearity coil characteristic
Inductance
(µH)
Left(Left)
(Right)
Current
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