Brightness" Basics - JVC DLA-G20 Sales Manual

"Brightness" basics

Brightness levels can be expressed in various ways (units).
Unit Symbol Reading Description
Light flux Lumen 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.)
Illuminance lux To measure illuminance, the projected screen size (area), as well as the
2
When an area of 1 m is projected with light output of 1
Therefore, the smaller the projection area, the larger the value of
Similarly, the larger the projection area, the smaller the value of
It is important to know the projection screen size when assessing the
be based on a very small projection screen size.
2
Intensity cd/m Candela per Intensity is a measure of the amount of light reflected from the screen. This is what people normally experience as
square meter brightness. Intensity is based on the reflectance (gain) of the screen and the illuminance (
nit Nit Although intensity is a fair reference for brightness, it is important to compare the projector's brightness performance
ft-L Foot-lambert carefully. Because screen area and reflectance are added to the calculation, the intensity value can vary widely
according to different conditions.
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.
Relationship among the projector light output, screen area and illuminance
1
With light flux of
2
1 m
If an area of is illuminated,
1
illuminance of is obtained.
When the distance is doubled,
the area is quadrupled,
1/4
meaning that illuminance is
Formula
Light flux ( )
Illuminance ( ) =
2
Screen area (m )
Illuminance ( ) screen reflectance (gain)
Intensity (cd/m 2 ) =
(radian)
3.14
ft-L = dc/m 2 0.292
cd/m 2 = nit = ft-L 3.43
2
(Nowadays, cd/m is more commonly used than nit.)
• Catalog data should be compared with the same unit.
8
reading, is taken into consideration.
, illuminance is 1 .
, even when the value remains the same.
.
value. If the value seems very high, it may
).
.
If the distance is doubled,
but projection size remains the same,
then illuminance also
(1 ).
remains the same
The area of a typical screen
Model (16:9)
4 : 3
(inches) (diagonal) reference
2 2
80 1.99 m 1.77 m
2 2
100 3.09 m 2.76 m
120 4.47 m 2 3.96 m 2
150 6.98 m 2 6.21 m 2
200 12.38 m 2 11.03 m 2
2 2
300 27.88 m 24.83 m
Reference material (1)
Intensity at-a-glance table (with fine bead screen) Intensity table (with SF-L060FJ)
Aspect ratio = 4:3 Aspect ratio = 4:3
Screen gain = 2.4 Screen gain = 3.7
Model
DLA-G20
Screen Screen
size Light output ( ) size Light output (
1000
(model, inches) (model, inches)
2
Length Width cd / m Length
42 0.85 0.64 1399.18 60 1.22
45 0.91 0.69 1218.84
Intensity table (with SF-L060SJ)
50 1.02 0.76 987.26
Aspect ratio = 4:3
60 1.22 0.91 685.60
Screen gain = 3.8
70 1.42 1.07 503.71
80 1.63 1.22 385.65 Screen
size Light output (
90 1.83 1.37 304.71
(model, inches)
Length
100 2.03 1.52 246.82
60 1.22
110 2.24 1.68 203.98
120 2.44 1.83 171.40
Intensity table (with SF-L080S)
130 2.64 1.98 146.04
Aspect ratio = 4:3
140 2.84 2.13 125.93
Screen gain = 2.8
150 3.05 2.29 109.70
Screen
160 3.25 2.44 96.41
size Light output (
170 3.45 2.59 85.40 (model, inches)
Length
180 3.66 2.74 76.18
77.5 1.57
190 3.86 2.90 68.37
200 4.06 3.05 61.70 Intensity table (with SF-L100FJ)
220 4.47 3.35 50.99
Aspect ratio = 4:3
Screen gain = 3.0
240 4.88 3.66 42.85
250 5.08 3.81 39.49
Screen
260 5.28 3.96 36.51 size Light output (
(model, inches)
280 5.69 4.27 31.48 Length
300 6.10 4.57 27.42 100 2.03
Reference material (2)
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
10% peak
(measured by outputting only 10% of the white)
CRT system
1000 200~340
D-ILA
1000
D-ILA Method Present Condition and Subject "Brightness" basics
DB-70S10 intensity table
Aspect ratio = 4:3
Screen gain = 1.9
Model Model
DLA-G20 DLA-S15
Screen
) size Light output ( )
1000 1000
(model, inches)
2
Width cd / m Length Width cd / m
0.91 1056.97 70 1.42 1.07
Intensity at-a-glance table (with SF-H1102 Fresnel lenticular)
Aspect ratio = 4:3
Screen gain = 3.3
Model Model
DLA-G20 DLA-G20
Screen
) size Light output ( )
1000 1000
(model, inches)
2
Width cd / m Length Width cd / m
0.91 1085.53 100 2.03 1.52
110 2.24 1.68
120 2.44 1.83
• If a mirror for folding a light axis is
Model available, add the reflectance of the
DLA-G20
)
1000
mirror to the calculation according to
2
Width cd / m
the number of mirrors used.
1.18 479.42
•The intensity of the Japanese
standard theater screen is around
30 to 65 cd/m 2 .
Model DLA-G20
) 1000
Width cd / m 2
1.52 308.52
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.
All-white
Even with the
same 1000 lm level,
there is a big difference
All-white
in actual brightness.
(with DLA-G20)
2
400.87
2
339.37
280.47
235.67
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