TM 5-6675-316-14
(17) The mechanical movement of the font disc is accomplished by changing the
position of the cam. This laterally moves the roller and the font disc. The flash
window remains stationary. Once the selected character has been illuminated, the
image passes through the optical system where it is magnified as determined by
keyboard size selection, and the values stored in the microprocessor program.
(18) The illuminated character image is projected into the enlarging lens.
The position of this lens from the font disc determines the final image size, in
this case from 5.5 to 74 points. The enlarging lens is moved backward and forward
on a carriage driven by a helix screw and stepping motor. The microprocessor
program determines the position of the lens by feeding information on the required
number of motor steps via the driver board to the stepping motor. By moving the
lens closer to the font disc, the aerial image increases in size. By moving the
lens away from the font disc, the image gets smaller. This increase and decrease in
size can be translated into point size as shown. The image formed is known as the
primary image, and is from 5.5 to 74 points in size.
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