Epson EMP-8000 Service Manual page 73

Mechanical adjustments for optical engine.
1. Optical Head Unit
The alignment (height/left and right/concurrent) of the polarization plates (include R/G/B light
valves) is applied in the factory. If the alignment is modified, clear color image will not be
made, because of the color divergence.




Caution:
Do not apply any mechanical stress and also not loosen the screws.
2. Prism Unit
To synthesize the light output from each polarization plate (include R/G/B light valves), the
alignment (concurrent to the polarization plate) of the prism unit is applied in our factory. If the
alignment is modified, clear image will not be made, because of the pixel divergence to R/G/B
synthesizing and projection lens unit, being out of focus and color uniformity.




Caution:
Do not loosen the prism unit fixing screws.
3. Light guide unit
The alignment of the light guide unit on the optical head unit is applied (gap and concurrent to
the polarization plate) in our factory. If the alignment is modified, clear image will not be made,
because of being out of the brightness uniformity on the display screen (brightness or chroma
is not uniform on the screen.)
In consideration of the alignment of the lens array and the mirrors, and also their combina-
tions, the factory setting is applied to the light guide unit to support the best display perfor-
mance. (If the alignment is modified or the location is changed, there comes distortion on the
display screen, therefore clear image will nit be made.)




Caution:
Do not disassemble the light guide unit. If you remove the upper guide cover from the unit, the
alignment of lenses or mirrors may be unintentionally changed and also dust may stick to the
unit.
Since Optical engine on the EMP-9000/8000 requires very precise adjustment, it can not be
adjusted in the field.
Electrical corrections(DR board)
Some parts in the mechanical section of the optical system require some mechanical adjust-
ments mentioned above. In the control circuit (Driver Board Assembly), the output driver for
the display signal is slightly different from the output driver of other device (Driver Board
Assembly) in individuality. The mechanical section itself of the optical system (e.g. light
valves) must be electrically corrected. Therefore to obtain the best image, not only the
mechanical adjustment but the electric correction is required. For this reason some correction
values are written to Flash ROM of the Driver Board Assembly on factory shipping. For match-
ing the optical system and electrical system, the electric correction is necessary. Conse-
quently, the driver board and the optical block (consists of optical head / light guide unit) make
one set.
At the factory shipment, following correction data are stored in the Flash ROM on the Driver
Board Assembly according to the specified optical engine.
• Gamma adjustment data
• Flicker adjustment data
• Ghost contrast adjustment data
• Sub contrast adjustment data




Caution:
For the writing correction values, an expensive, special device and also skillful engineer are
necessary, therefore it can not adjust in the field.
SEIKO EPSON
EMP-9000/8000
3-3 Revision:A