MTF Graph and Its Discussion
TYPICAL MTF VS DEPTH OF FOCUS
60
50
40
30
20
10
0
0
0.2
0.4
0.6
DEPTH FROM THE WINDOW SURFACE(mm)
MTF IN %
Item
Power Supply
Figure 3. Typical MTF versus Distance
See Figure 3, Typical MTF versus Distance. This graph essentially shows the working
depth-of-focus. Two curves indicates the spread among the modules. Note that MTF is
greater than 40% out to distance greater than 0.4 mm from the glass surface. Since this
module is a 200DPI module, a pixel density of 200 pixel per inch, the MTF was measured
with a 100 DPI or a 50 line-pair per inch optical bar pattern. The test was conducted with
pixel rate set to 2.5MHz.
The effective algorithm used in the measurements is as described by the following
equation:
MTF={[Vp(n)+Vp(n+1)]/2-[Vp(n+2)+Vp(n+3)]/2}/{[Vp(n)+Vp(n+1)]/2+[Vp(n+2)+Vp(n+3)]/2}
Where n is 1, 2, .....1728
th
, Vp(n) is the signal amplitude of the n
th
pixel.
Operating Conditions (25 °C)
Symbol
Vdd (positive)
Vn (negative)
Idd (positive)
In (negative)
(1)
Input voltage at digital high Vih
Input voltage at digital low Vil
Clock frequency
Fclk
Min
4.5
-10
60
20
Vdd-1.0
0
0.2
(2)
Typical
5.0
-5
66
20
Vdd-.5
Max
5.5
-4.0
75
20
Vdd
0.6
5.5
(3)
Units
V
V
ma
ma
V
V
MHz
PAGE 7 OF 10 - PI227/228/229, 01-31-04
AMI [ AMI SEMICONDUCTOR ]
