Quantum Data 801GC, 801GF, 801GX manual Linearty Linearity contd

Linearty (Linearity) — contd.

Detail showing center of linearity test image. All lines are one pixel thick.

Test	Linearity adjustment
Purpose	In order to present an undistorted display, the
	horizontal and vertical sweeps of the electron beam
	across the face of the CRT should be at uniform
	speeds. Any non-uniformity in the sweep causes
	portions of an image to stretch while other portions
	are compressed. Non-linearity in a monitor shows
	up in several ways. It may be present across the
	entire screen, in a large portion of the screen, or
	localized in a very small area.
Method	The circles in the image can be used to do a ball
	park adjustment of a monitor’s linearity controls.
	Adjust the controls to form perfectly round circles.
	The crosshatch image can be used to measure
	linearity and to make finer control adjustments.
	All the full boxes in the crosshatch should be
	identical in size. Measure them with a ruler or a
	gauge made for the monitor you’re testing. Any
	deviation should be within your spec limits. Use
	the tic marks and a ruler or gauge to measure
	linearity over a small portion of the display.
	Compare the number of tic marks per unit of
	measure with an adjacent or overlapping area.

4-38 Chapter 4: Built-In Images Model 801GC, 801GF & 801GX¥Rev. X1