B&K Precision 1253 - Manual - Manual (Page 12)

5: Cross Hatch
Description: A grid of 16 x 9 boxes, separated by white lines.
Pattern Usage: Used to check and adjust convergence of red, green and blue pictures. The horizontal and
vertical lines are usually best observed to detect color fringing resulting from misconvergence, and the
dots are usually best observed to make fine adjustments.
Even if a display device provides an internally generated crosshatch pattern for checking convergence, it
is often best to double-check the convergence with an externally generated pattern. Occasionally, a
display’s convergence on an internally generated pattern doesn’t match its convergence on external input
video signals.
Also used to check and adjust for the proper geometry of a display, including picture centering, size,
trapezoid (keystone) correction, pincushion (bow) correction, and linearity. Horizontal and vertical
centering controls should be adjusted to center the pattern on the display screen.
Trapezoid correction control(s) should be adjusted to make the pattern’s edges parallel to the edges of the
display screen. Pincushion correction controls should be adjusted to straighten the lines to be straight, and
parallel to the edge of the screen. Use the edge of the display screen or a flexible straightedge, such as a
yardstick, to judge the straightness of the lines. The horizontal linearity control should be adjusted to
make the pattern boxes all the same width. The vertical linearity control should be adjusted to make the
pattern boxes all the same height.
Examples of Uncalibrated Displays: The following images indicate a TV with misconvergence.
The White lines become separated Red, Green and Blue lines. They are either straight or curved. Adjust
the RGB convergence controls to align the colors to overlap, so the Cross Hatch pattern appears as a grid
of white squares.
Linear Misconvergence Non-Linear Misconvergence