JVC DLA-G20 Sales Manual page 7

"Brightness" basics
Reference material (3)
Projected images can be difficult to see under bright light
because the ambient light lowers the contrast ratio by
illuminating the screen surface. As a result, the screen
(and the image) appears whiter. The contrast ratio is
normally classified as shown below. In each case, the
Reference table for the reflection limit of the external light on the screen (aspect ratio = 4:3)
Required contrast ratio 30 : 1
Model DLA-G20 Reference/DLA-S15
Contrast 250 250
Light output ( ) 1000 1000
Screen size
(Inches/model)
Length (m) Width (m) Lux ( ) Lux (
42 0.85 0.64 53.70
45 0.91 0.69 46.78
50 1.02 0.76 37.89
60 1.22 0.91 26.31
70 1.42 1.07 19.33
80 1.63 1.22 14.80
90 1.83 1.37 11.69
100 2.03 1.52 9.47
110 2.24 1.68 7.83
120 2.44 1.83 6.58
130 2.64 1.98 5.60
140 2.84 2.13 4.83
150 3.05 2.29 4.21
160 3.25 2.44 3.70
170 3.45 2.59 3.28
180 3.66 2.74 2.92
190 3.86 2.90 2.62
200 4.06 3.05 2.37
220 4.47 3.35 1.96
240 4.88 3.66 1.64
250 5.08 3.81 1.52
260 5.28 3.96 1.40
280 5.69
4.27 1.21
300 6.10 4.57 1.05
30:1 = The minimum contrast ratio required for a general presentation
50:1 = The minimum contrast ratio required to watch a picture
100: 1 = Contrast ratio acceptable to most people
• Select the contrast ratio according to the usage conditions.
Formula
1 1
XL = L –
Calculate with
C C
T
10
reflection limit of the external light on the screen surface is
shown as reference. For actual installation, the reflection
amount on the screen should not exceed the values
shown below.
50 : 1 100 : 1
DLA-G20 Reference/DLA-S15 DLA-G20 Reference/DLA-S15
250 250 250 250
1000 1000 1000 1000
) Lux ( ) Lux ( ) Lux ( ) Lux (
29.29 10.98
25.51 9.57
20.67 7.75
14.35 5.38
10.54 3.95
8.07 3.03
6.38 2.39
5.17 1.94
4.27 1.60
3.59 1.35
3.06 1.15
2.64 0.99
2.30 0.86
2.02 0.76
1.79 0.67
1.59 0.60
1.43 0.54
1.29 0.48
1.07 0.40
0.90 0.34
0.83 0.31
0.76 0.29
0.66 0.25
0.57 0.22
X = Reflection illuminance ( )
L
Light output ( )
L = White illuminance = ( )
Screen area (m 2 )
C = Required contrast ratio
T
C = Contrast ratio of the projector
Reference material (4)
ANSI
The light output (lumen) of a projector cannot be clearly
understood when different measurement methods are
used. When data has been obtained with various
measurement methods under different conditions, it is
difficult to compare actual performance. To ensure a
relatively meaningful basis for comparison, many
manufacturers adhere to measurement standards set forth
by "ANSI" (American National Standard Institute). The
D-ILA is measured according to the ANSI IT 7.228.
)
ANSI measurement method
Connect a signal generator and project signals at 100%
level (all-white) on the screen.
(1) Project a signal pattern as shown in Fig.1 and adjust
the contrast and brightness so that the difference in
lightness of each block can be recognized clearly. In this
case, the aspect ratio should be the same for the screen
and pattern.
(2) Project the all-white with this contrast and brightness.
Fig. 1
0 5
90 95
Reference material (5)
Which is brighter, 1000 or 2000
2000 would seem to be brighter. However, the
measurement unit is different. "
light output while " "(lux) shows the illuminance. These
vary depending on the screen size.
D-ILA Method Present Condition and Subject "Brightness" basics
Measure the center point in each zone which is obtained
by equally dividing the screen into 9 as shown in Fig.2.
The ANSI value is obtained by averaging the 9 measured
point values. Normally, an illuminance meter is used for
measurement. As the measurement unit is
the value of (lumen) by calculating with the projected
screen area.
• ANSI is shown autonomously by each manufacturer and
is not required. At present, the measurement method for
light output is not prescribed.
• Even though ANSI indication is shown, a unique meas-
urement method may have been used or conditions (1)
may not be satisfied. Be careful!
• If the fact that the data is obtained according to
"American National Standard IT 7.228" is shown on the
document, the data is correct.classified as shown below.
In each case, the reflection limit of the external light on the
screen surface is shown as reference. For actual installa-
tion, the reflection amount on the screen should not
exceed the values shown below.
Fig. 2
10
100
(40" type, 4:3)?
Light output (
Illuminance ( ) =
Screen area (m
" (lumen) shows the
Therefore,
the light output ( ) = illuminance (
A 40" screen with 4:3 aspect ratio is
0.5 m 2 , = 2000 x 0.5 = 1000.
Therefore, 1000 and 2000
(lux), obtain
)
2
)
) screen area (m 2 ).
have the same brightness.
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