JVC DLA-G20 Sales Manual page 17

Projection type (rear projection)
Range of adequate view
The range of adequate view generally depends on the "viewing angle". The rear screen for the JVC DB-70S10 data box is
shown as an example. The viewing angle varies depending on the screen. However, as the D-ILA light output is large, a
fairly large viewing angle can be obtained.
Screen
Mirror
Adequate
view range
Notes on screens for a transmission type rear projection
When a projector with divided pixels is combined with a
screen which uses a Fresnel lens, lenticular lens and
black stripe, cross stripes from the divided pixel panel
interfere with the screen's lens pitch and black striping,
resulting in moiré pattern. The extent to which this pattern
is noticeable depends on the size of the projected image,
the screen's lens pitch and the panel's pixel division pitch.
Although the DLA-S15 has divided pixels, it has a
high aperture ratio with very little cross striping, moiré
patterns are not normally apparent. However, care should
Notes on screens for a transmission type rear projection
The D-ILA's powerful light output results in heat
generation. As the area available behind the screen is
typically small, temperature can rise excessively. Cool the
area behind the screen by providing good ventilation or by
installing an air conditioner.
(When an external fan is added, take air flow resistance
into consideration and use a fan with relatively large
capacity.)
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Screen
Mirror
Adequate
view range
be taken when this unit is combined with a Fresnel
lenticuler screen or black stripe screen. If moiré does
appear, there is no way to get rid of it so be sure to check
it beforehand.
Assuming that no moiré patterns appear, the
Fresnel lenticular screen is a good choice since it can
reproduce much better pictures in terms of the peripheral
light quantity ratio, brightness and viewing angle than a
screen that only uses a dispersal agent.
Heating value
Model DLA-G20 / DLA-S15
Heating value 2260 kJ/h 540 kcal/h
Projector cooling fan capacity
Model DLA-G20 / DLA-S15
3 3
Fan air capacity Total 303.6 m /h (5.06 m /h)
Basic facts about reflecting mirrors
Mirror
● Ideally, when projecting images using rear projection, a
mirror should not be used. However, if limited depth is
available in the installation location, making it necessary to
fold the light axis, you can use one mirror for reflection. If
you use more than one mirror, consult the Projection Sales
Department beforehand. The more mirrors used, the
worse the picture quality and the lower the brightness.
● Be sure to use only a JVC-specified glass surface
mirror. If an underside mirror or refex mirror is used,
picture quality may be adversely affected.
There are three basic types of
reflection mirror.
A. Surface mirror (surface aluminum evaporation
glass mirror)
This mirror has a reflection surface on the glass surface.
As there is no unnecessary reflected light, this mirror pro-
vides optimal reflection image. However, because the
reflection surface is on the surface, it can easily be dam-
aged. Be sure not to touch this surface with bare hands.
Also, in comparison to other types of mirrors, surface mir-
rors are expensive and the
Difference between surface mirror and underside mirrora
Surface mirror (mirror for the DB-70S10)
Reflected light
Glass
Incident light
Reflection metal film
A: Surface mirror
Cost
Performance
Maximum size 2400 mm 1800 mm
Remark Use this type.
Total market (includes mirrors which the Projection Sales Department does not handle)
D-ILA Method Present Condition and Subject Projection type (rear projection)
maximum available size is relatively small. Nevertheless,
if picture quality is the priority, choose this mirror.
B. Underside mirror (general mirror)
The reflection surface is behind the glass. This is the kind
of mirror normally employed in lavatories since the reflec-
tion surface is protected and difficult to damage. Cleaning
is also easier and it is less expensive than a surface mir-
ror. The disadvantage of this type is that light is reflected
not only on the reflection surface but also partially on the
glass surface. As a result, the image is doubled, produc-
ing a ghosting effect which makes it unsuitable for reflec-
tion of a projector image.
C. Refex mirror (Aluminum evaporation polyester film
mirror)
Although refex mirrors are inexpensive, it is difficult to
maintain surface smoothness, resulting in moiré and fuzzy
images. This type of mirror has not been generally suit-
able for actual use. However, it has been recently
improved.
● As a result, a surface mirror is recommended for use
as a reflection mirror for rear projection with the D-ILA.
Underside mirror (general mirror)
Reflected light
Unnecessary
reflected light (ghost)
Glass
Incident light
Reflection metal film
B: Underside mirror C: Refex mirror
3600 mm 1500 mm 600 mm 1400 mm
Not recommended. Not recommended.
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