17
Tuner
Video 1-4
480i
A/V
Switches
Progressive or
interlaced output
DRC
circuit
MID
circuit
480p
960i
240/480
lines
15.75kHz/31.5kHz
480
lines
33.75kHz
Expand
Vertical
480 active lines
540 lines
DRC
circuit
MID Circuit
480p
480i
960i
Progressive
480p + 60 = 540p lines
Expand
Vertical
960 active lines (2 fields)
1080 lines
540p
1080i
960i + 120 = 1080i lines
Interlaced
Adds 60
blank lines/scan
Progressive Scan - In this example of the progressive scan video pro-
cessing, an NTSC still picture signal is input from a DVD player (in pause).
The user chooses progressive scan from the menu to reduce picture flicker.
Flicker occurs in an interlaced picture when the two fields are not exactly
the same images. The flicker is more noticeable in the movement area(s)
of the picture where the fields are different.
In the progressive scan mode the DRC circuit doubles the number of lines
from 480i (actually 240 lines) to 480p to make the NTSC signal compat-
ible with the TV.
Interlace Scan - In a second example of the video processing, an NTSC
signal with live pictures is input from an antenna. The user chooses the
interlace scan mode from the menu because of the moving images. Each
interlaced field displays a slightly different transitioning picture making
movement seem smoother.
In the interlaced scan mode the DRC circuit still must double the number
of lines to meet the TV’s 480-line/scan requirement. The resolution is
changed from 480i (actually 240 lines) to 960i (actually 480 lines) by the
DRC circuit.
MID Circuit
Fortunately, the model KV32XBR400 TV’s horizontal deflection stage scans
at a 33.75kHz rate to display high definition (1080i) video signals. How-
ever The horizontal frequency output the DRC circuit is double that of
NTSC at 31.5kHz. This is slower than the KV32XBR400’s 33.75kHz rate.
Since the TV scans at a faster rate than what is input, the picture is fin-
ished faster, leaving blank lines at the bottom.
The MID circuit centers the picture by adding 30 blank lines above and
below the picture (60 lines total). This simple method permits the TV to
keep the vertical frequency at 60Hz. Therefore the MID circuit increases
the number of lines from 480p to 540p but these extra lines are blank.
There are still only 480 active (picture) lines.
Vertical Expansion
To keep the 60 blank lines invisible, the vertical size is expanded slightly
(picture overscaned) so the 480 lines fill the 4:3 aspect ratio screen. This
is seen in the previous diagram where the 60 blank lines are shown (ex-
aggerated) in black.
Summary of Contents for KV-32XBR400
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