Acer AM501, Service Manual

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12
4.4 Brightness and Contrast
Definitions:
Active area This zone can be lighted when the background color is changed from
black to any other color. Its dimensions, in terms of timing correspond to
the "active area "times described in table 3
Raster area Under certain conditions (see table 4) this zone must be visible when no video input is
applied. Width and height of the raster area must be larger than the corresponding
dimensions of the active area.
Border Comprising any area of the screen outside the raster area.
Brightness This control is mainly intended as a raster luminance adjustment.
Contrast This control shall vary the gain of the video amplifier, thus adjusting the contrast
of the displayed images, and shall not have any visible effect on the raster luminance.
Both controls shall not affect the border. Inside this zone the raster shall be always under the minimum
perceptible level and no evidence of retracing(images or distortion)shall be visible on the screen at any
setting of the luminance controls. The user controls shall operate as described on table 4. This check
must be performed under a diffused illumination of 10 lux and on 48k mode (Horizontal frequency).
Table 4
Patterns Setting of user Controls Luminance Limits
Brightness Contrast Raster Area White Area
A Min Any Not Visible *
A Max Min 0.3 ~ 3.0 FL *
B Max Max * 60 FL<=
C Max Max *
>
29FL
B Min Max Not Visible Visible
B Min Min Not Visible Not Visible
Legend:
*Don't Care
A Black screen @0 mV video level.
B 2
?
x 2
?
white box, @700mV video level.
C Full white screen, 100% of the data area @700mV video level
.