9
1399.18
1218.84
987.26
685.60
503.71
385.65
304.71
246.82
203.98
171.40
146.04
125.93
109.70
96.41
85.40
76.18
68.37
61.70
50.99
42.85
39.49
36.51
31.48
27.42
42
45
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
220
240
250
260
280
300
0.85
0.91
1.02
1.22
1.42
1.63
1.83
2.03
2.24
2.44
2.64
2.84
3.05
3.25
3.45
3.66
3.86
4.06
4.47
4.88
5.08
5.28
5.69
6.10
0.64
0.69
0.76
0.91
1.07
1.22
1.37
1.52
1.68
1.83
1.98
2.13
2.29
2.44
2.59
2.74
2.90
3.05
3.35
3.66
3.81
3.96
4.27
4.57
Intensity at-a-glance table (with fine bead screen)
Aspect ratio = 4:3
Screen gain = 2.4
Model
Light output ( )
Screen
size
(model, inches)
DLA-G20
1000
cd / m
2
Width
Length
339.37
280.47
235.67
100
110
120
2.03
2.24
2.44
1.52
1.68
1.83
Intensity at-a-glance table (with SF-H1102 Fresnel lenticular)
Aspect ratio = 4:3
Screen gain = 3.3
Model
Light output ( )
Screen
size
(model, inches)
DLA-G20
1000
cd / m
2
Width
Length
1056.97
60
1.22
0.91
Intensity table (with SF-L060FJ)
Aspect ratio = 4:3
Screen gain = 3.7
Model
Light output ( )
Screen
size
(model, inches)
DLA-G20
1000
cd / m
2
Width
Length
400.87
70
1.42
1.07
DB-70S10 intensity table
Aspect ratio = 4:3
Screen gain = 1.9
Model
Light output ( )
Screen
size
(model, inches)
DLA-S15
1000
cd / m
2
Width
Length
1085.53
60
1.22
0.91
Intensity table (with SF-L060SJ)
Aspect ratio = 4:3
Screen gain = 3.8
Model
Light output ( )
Screen
size
(model, inches)
DLA-G20
1000
cd / m
2
Width
Length
479.42
77.5
1.57
1.18
Intensity table (with SF-L080S)
Aspect ratio = 4:3
Screen gain = 2.8
Model
Light output ( )
Screen
size
(model, inches)
DLA-G20
1000
cd / m
2
Width
Length
308.52
100
2.03
1.52
Intensity table (with SF-L100FJ)
Aspect ratio = 4:3
Screen gain = 3.0
Model
Light output ( )
Screen
size
(model, inches)
DLA-G20
1000
cd / m
2
Width
Length
Even with the
same 1000 lm level,
there is a big difference
in actual brightness.
CRT system
D-ILA
10% peak
(measured by outputting only 10% of the white)
All-white
All-white
1000 200~340
1000 (with DLA-G20)
D-ILA Method Present Condition and Subject
8
Brightness levels can be expressed in various ways (units).
Unit
Light flux
Illuminance
Intensity
Symbol
cd/m
2
nit
ft-L
Reading
Lumen
lux
Candela per
square meter
Nit
Foot-lambert
Description
The light output of a projector itself. A projector’s basic brightness performance is easy to measure.
However, the actual brightness can vary depending on the settings used and other factors. When comparing
brightness performance, these settings should be checked. (eg.: 10% peak, all-white, etc., refer to (2) on the next
page.)
To measure illuminance, the projected screen size (area), as well as the
reading, is taken into consideration.
When an area of 1 m
2
is projected with light output of 1
, illuminance is 1 .
Therefore, the smaller the projection area, the larger the value of
, even when the
value remains the same.
Similarly, the larger the projection area, the smaller the value of .
It is important to know the projection screen size when assessing the
value. If the value seems very high, it may
be based on a very small projection screen size.
Intensity is a measure of the amount of light reflected from the screen. This is what people normally experience as
brightness. Intensity is based on the reflectance (gain) of the screen and the illuminance ( ).
Although intensity is a fair reference for brightness, it is important to compare the projector’s brightness performance
carefully. Because screen area and reflectance are added to the calculation, the intensity value can vary widely
according to different conditions.
With light flux of
1
If an area of
1 m
2
is illuminated,
illuminance of
1
is obtained.
When the distance is doubled,
the area is quadrupled,
meaning that illuminance is
1/4 .
If the distance is doubled,
but projection size remains the same,
then illuminance also
remains the same
(1 ).
Illuminance ( ) =
Light flux ( )
Screen area (m
2
)
Intensity (cd/m
2
) =
Illuminance ( )
2
screen reflectance (gain)
(radian)
3.14
ft-L = dc/m
2
2
0.292
cd/m
2
= nit = ft-L
2
3.43
(Nowadays, cd/m
2
is more commonly used than nit.)
80
100
120
150
200
300
1.99 m
2
3.09 m
2
4.47 m
2
6.98 m
2
12.38 m
2
27.88 m
2
1.77 m
2
2.76 m
2
3.96 m
2
6.21 m
2
11.03 m
2
24.83 m
2
Model
(inches) (diagonal)
4 : 3
(16:9)
reference
“Brightness” basics
The value of the light flux ( ) showing the projector’s
light output varies depending on incidental conditions.
The “10% peak” value used for many CRT projectors
increases to 3 to 5 times the all-white value.
For example, if a CRT projector has a brightness level of
1000 at 10% peak, the value at all-white will be from
200 to 340 . With the DLA-G20, on the other hand,
the value at all-white is 1000 , making the DLA-G20 3 to
5 times brighter than a CRT projector of the same level.
This shows the importance of taking incidental conditions
into account when comparing light flux ( ) performance.
•
If a mirror for folding a light axis is
available, add the reflectance of the
mirror to the calculation according to
the number of mirrors used.
•The intensity of the Japanese
standard theater screen is around
30 to 65 cd/m
2
.
Reference material (1)
Reference material (2)
Brightness levels can be expressed in various ways (units).
Screen brightness is not related to throw distance. It is determined by projection size and screen reflectance (gain) unless
the projection space is smoky or hazy. Even with a long throw distance, the brightness remains the same if the projection
size is set to the same value by changing the lens magnification. The relationship is shown below.
m
Relationship among the projector light output, screen area and illuminance
m
Formula
m
The area of a typical screen
•
Catalog data should be compared with the same unit.
“Brightness” basics
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