reflect light (wich night otherwise be lost) back onto the copy
help to make the illumination unform. The secondary mirror assembly
consists of an aluminum sheet metal frame and three secondary rear
surface mirrors that are held in the frame by means of retaining strips.
Shock absorbing material is placed between the mirrors and frames to
minimize breakage. The entire assembly is mounted in the projector
by means of U-type self locking speed nuts and sheet metal screws.
f. Reflector and Lamp Holder Assembly (figs. 8, 14, and 15)
reflector assembly consists of a steel frame in which are mounted the
lamp holder and the parabolic reflector. The lamp holder is fastened
to the frame by means of two screws, and the parabolic reflector is held
by means of two clamping straps.
g. Pointer (figs. 4, 5, 8, anti 16) . The built-in optical pointer takes
stray light from the side of the lamp filament and, by means of properly
located mirrors and lenses, projects the image of an arrow on the
screen. This imagc can be moved to point out details anywhere on the
screen. The pointer system consists of a bracket (mounted on the inside
of the housing) on which are mounted a condensing lens, an adjustable
rear surface mirror, an aperture plate containing the arrow to be
projected, a front surface mirror, and a lens tube.
h. Undercarriage Assembly (figs.
5, 8, and 10)
. The undercarriage
assembly, supported on a parallel linkage, is self-locking when in the
lowered position. The assembly includes an orifice plate and a vacuum
box projection stage (par. 15) on which a crank operated conveyor
belt type, copy feeding mechanism is mounted. The cooling fan and
motor are mounted in the forward end of the undercarriage above the
orifice plate and are inclosed on three sides and protected on `the top
and bottom by screens. The four parallel arms are connected to the
base of the projector by shoulder screws on which the parallel arms
pivot. Tension springs, connected between the projector base and the
forward pair of parallel arms, serve to hold the undercarriage either in
the raised or lowered position for the insertion of thick copy.
i. Copy Feeding Mechanism (figs.
10 and 11)
. The copy feeding
unit consists of an aluminum structure that supports two rollers. One
roller is crank operated and the other roller is mounted so that it can
rotate freely. An endless perforated neoprene belt is stretched over both
rollers and a perforated metal shelf. The copy feeding unit is supported
on the undercarriage vacuum box. As the exhaust fan forces the air
out, it creates a vacuum at the top of the perforated belt. Material
placed on this belt is held down upon it and, as the crank is operated,
the material is carried into the projector and on out as the cranking
is continued. The belt also serves as the projection stage for thick