(9) All of the incoming voltages and signals to the
scan rate is applied to the log amplifier and the photocell
camera pass through the EMI filter.
amplifier from the bias network which receives its V/H
2-2. Functioning of Body
signal from the operate relay. The output of the
photocell is applied to the differential amplifier
simultaneously with outputs from the log amplifier,
The body contains all the optical components (para 2-6)
photocell amplifier, and the aei networks. The photocell
of the camera and the mechanisms by which the film
is a photosensitive resistor and is arranged in a voltage
transport and exposure (para 27), image motion
divider network where its resistance varies in inverse
proportion to the terrain brightness. The output from the
2-9) are made
In addition, the body houses
photocell and its associated networks are compared with
a lens and mirror assembly and a recording head
the voltage from the aec feedback potentiometer. The
difference or error voltage is amplified and converted to
photographically recorded on the film as part of the
an ac signal which is applied to the aec servo amplifier.
aircraft's auxiliary data annotation system (adas).
The servo amplifier drives the aec motor which through
a. The optical components include a 3 inch f/ 2.8
a gear train reduction drives the arm of the feedback
lens assembly. The lens is installed below a focal plate
potentiometer until the error is nulled and the proper slit
having a variable slit (shutter). A double-dove prism
width and diaphragm opening combination is attained.
driven by the scan motor (fig. 2-6) rotates in front of the
Therefore, in taking a photograph, the exposure level is
lens on an axis parallel to both the slit and the line of
directly proportional to the light level of the object, the
length of time that the object is imaged on the film and
description of the optics system.
the speed of the film (aei).
b. The adjustable components of the automatic
(5) The power flow for the system is controlled by
exposure control system (aec) are an aperture assembly
the POWER switch. In the ON position the switch
and the moveable section of the slit in the focal plate.
permits the live power to flow through the circuit
The motor in the servo system adjusts the width of the
breakers to the power supply and voltage regulator. The
slit, the opening of the aperture, and the positioning of a
POWER lamp is illuminated when the POWER switch is
feedback potentiometer. The electronic circuits include
ON and power is present.
a photocell assembly that is mounted adjacent to the
(6) The OPERATE switch initiates the functional
prism. The balance of the electronic parts are mounted
operation of the system by energizing the coil of the
on the aec assembly, which is installed in the camera
operate relay. A delay circuit is used in conjunction with
the operate relay in order to provide a delayed turn-off
description of automatic exposure control operation.
to the scan drive circuit. The OPERATE lamp flashes
c. The scan drive system consists of a dc drive
once during each picture cycle or will light continuously
motor, a dc tachometer-generator with a tachometer
to indicate that the film supply has been exhausted.
(7) The end of film switch is placed in the film path
which drives the prism, the image motion compensation
and is controlled by the film pressure mechanism.
(imc) mechanism, the puck and sprockets of the film
Hence, if the film runs out or breaks, the end of film
transporting system, and the operation of the puck
switch opens and the +22 volt regulated control voltage
to the scan control relay is removed causing the scan
The parts comprising the electrical circuits are board
motor to stop. When the end of film switch is open, the
mounted and installed in the camera control.
control voltage (+22 vdc) is fed back to the OPERATE
lamp to indicate the end of film supply or film breakage.
d. The imc mechanism is a shaft assembly which
(8) The recording head assembly (rha), housed in
includes a cam, drag brake, coupling, and spur gear. It
the camera, receives its coded information from the
is positioned below the lens carriage and mounted with
This information is then applied
the cam inserted into a cam follower on the carriage.
photographically to the film.
The coupling and the rotating spur gear are brought into