7. Lenses & lens holder
If yes, the B ack Focal Length is correctly adjusted.
If no, repeat with step 4.
9. Is the projected image in the corners as sharp as in the middle?
If yes, proceed with the procedure "Fixation of the Lens Holder front plate", page 77.
If no, Sch eimpflug adjustment is required. See procedure "Scheimpflug adjustm ent", page 74, prior to fixate the Lens Holder
front plate. CAUTION: Skip the action, in the Scheimpflug adjustmen t p rocedure, to turn the three S cheimp flug adjustment nuts
until the front of the nut is equally aligned with the front of the threaded rod!
7.7 Scheimpflug adjustment
What has to be done ?
The lens holder has to be adjusted so that the “sharp focus plane” of the projected image falls together with the plane of the screen
(Fp1→Fp2). This is achieved by changing the distance between the DMD plane and the lens plane (Lp1→Lp2). T he closer the lens
plane comes to the DMD plane the further the sharp focus plane will be. It can sometimes happ en that you won’t b e able to get a
complete focused image on the screen due to a tilt (or swing) of the lens plane with respect to the DM D plane. This is also known
as Sheimpflug’s law. To solv e this the lens plane must be placed parallel with the DMD plane. T his can be achieved by t urning the
lens holder to remove the tilt (or swing) between lens plane and DMD plane (Lp3→Lp4).
SCREEN
DMD
Lp1
Lp2
Fp1
Fp2
SCREEN
DMD
Lp3
Lp4
Fp3
Fp4
(Scheimpflug)
Image 7-29
Scheimpflug principle
Scheimpflug principle
The "plane of sharp focus" can be changed so that any plane can be bro ught into s harp focus. When the DMD plane
and lens plane are parallel, the plane of sharp focus will als o be parallel to these two planes. If, h owever, the lens
plane is tilted with respect to the DMD plane, the plane of sharp focus will also be tilted according to geometrical and
optical properties. The DMD plane, the principal lens plane and the s harp focus plane will intersect in a line below the
projector for downward lens tilt.
Scheimpflug adjustment points
4
1
2
3
d
D
c
C
A
a
B
b
Image 7-30
Scheimpflug adjustments
Indication on drawing Function
4 Locking nut
74
R5906753 DPXK BLP SERIES 20/11/2017
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