NEC Display Solutions of America, Inc.
NP901W Installation Guide
Ceiling Mounted and Desktop
Rev 1.0
www.necdisplay.com
NP901W
Page 4 of 6
Formulas
The Projection Formulas use the image width for calculation. Image height is the same for all aspect ratios, only horizontal image
size varies when using a 16:10 aspect ratio screen. For proper projector placement, determine the image width for a desired screen
size. Use the Screen Formulas below to calculate all screen dimensions. Plug in the image width “W” for a 4:3 aspect ratio image in
the Projection Formulas.
Refer to the diagrams (page 5) and charts below for popular screen sizes 16:9 screens:
Definitions:
4:3 Screen Formulas:
W
=
Image
Width
W
=
H
x
4/3
H
=
Image
Height
(size)
H
=
W
x
3/4
B = Vertical distance between lens center and screen center
Screen Diagonal = W x 5/4
C = Throw distance
D = Vertical distance between lens center and screen top
(screen
bottom
for
desktop
application)
Projection Formulas:
B
=
0.327W
C
(wide) = 1.737W – 1.823
C
(tele) =2.085W – 1.820
D
= -0.050W
α
(wide) = tan¯¹ (B/C(wide))
α
(tele) = tan¯¹ (B/C(tele))
Note:
Tilting the front of the projector or down by more than 45° from level could reduce lamp life by up to 20%.
Distance Chart for popular 4:3 aspect ratios on a 16:9 screen
Diagonal
Width(W)
Height (H)
Diagonal Width(W) Height (H)
inches
inches
inches
inches
inches
inches
inches
49
43
24
40
32
24
10
54
-
65
10.8 -
9.0
73
64
36
60
48
36
16
81
-
98
10.8 -
9.0
92
80
45
75
60
45
20
102
-
123
10.8 -
9.0
100
87
49
82
65
49
21
112
-
134
10.8 -
9.0
106
92
52
87
69
52
23
118
-
143
10.8 -
9.0
110
96
54
90
72
54
24
123
-
148
10.7 -
9.0
120
105
59
98
78
59
26
134
-
161
10.7 -
9.0
122
107
60
100
80
60
26
137
-
165
10.7 -
8.9
133
116
65
108
87
65
28
149
-
179
10.7 -
8.9
135
117
66
110
88
66
29
151
-
181
10.7 -
8.9
159
139
78
130
104
78
34
179
-
215
10.7 -
8.9
161
140
79
132
105
79
34
181
-
218
10.7 -
8.9
230
201
113
188
151
113
49
260
-
312
10.7 -
8.9
275
240
135
225
180
135
59
310
-
373
10.7 -
8.9
Screen Size (16:9)
Image Size (4:3)
on a (16:9) screen
B
inches
inches
inches
C
w ide - tele
D
α
w ide - tele
-2
-2
-3
-3
-3
-4
-4
-4
-9
-4
-4
-5
-8
-5
Note:
For screen sizes not indicated on the projection tables, use the formulas on page above.
Input Signal Aspect Ratio
4:3 image on a 16:9 screen
