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Center scan and AF modes
Description of Center Scan and AF Mode Operation
The center scan and AF modes realize high frame rates by sweeping the top and bottom of the picture with
high-speed transfer and cutting out the center of the picture.
The various readout modes during center scan and AF operation are described below.
• AF modes
AF mode (1), (2): The output method is the same as readout in 2/8-line readout mode.
• Center scan modes
Center scan mode (1): The output method is the same as 2/4-line readout mode.
Center scan mode (2): The output method consists of 2-line addition readout whereby the signals for only
Center scan mode (3): The output method is the same as progressive scan mode.
The readout method, frame rate, number of output lines and other information for each readout mode are
shown in the table below.
Mode
Progressive scan mode
2/8-line readout mode
2/4-line readout mode
2-line addition mode
Center scan mode (1)
Center scan mode (2)
Center scan mode (3)
AF mode (1)
AF mode (2)
Undesired portions (Swept by vertical register high-speed transfer)
two out of four lines (3rd and 4th lines, 7th and 8th lines, and so on) are read out,
the vertical register is shifted by 2 bits, and then the signals of the remaining two
out of the four lines (1st and 2nd lines, 5th and 6th lines, and so on) are read out
and added within the vertical register.
Readout method
Progressive scan
2/8-line readout
2/4-line readout
2/4-line readout
2/4-line readout
2-line addition readout
Progressive scan
2/8-line readout
2/8-line readout
Picture center cut-out portion
Frame rate (frame/s)
Addition
method
28.6MHz
None
9.99
None
29.97
None
19.98
Vertical 2-line
19.98
None
29.97
Vertical 2-line
29.97
None
29.97
None
59.94
None
119.88
– 17 –
ICX274AQ
Number of output
effective pixel data
lines
36MHz
28.6MHz
36MHz
14.985
1220
29.97
305
19.98
610
19.98
1220
29.97
434
29.97
434
29.97
444
59.94
170
119.88
43
1220
305
610
1220
568
568
580
235
75
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