Film Transport - Canon EOS 55 Service Manual

Part 2: Technical Information
1.4 Film Transport
1) Overview
The film transport system uses a single motor (the same M 1 coreless motor used by the
EOS 5/A2E). By running in the normal or reverse mode, it performs the operations
shown in Table 2-6.
The motor performs these operations by having its driving power distributed according
to where the phase cam stops. During standby, the built-in flash pop-up phase is set.
This keeps the built-in flash ready to pop-up before the exposure is made.
The process from autoloading to film rewind is described below.
1. Auto film loading
After the film is loaded and the camera
back is closed, the camera reads the
film's DX code. The motor runs in the
normal mode (3) and sets the film
advance phase. The motor then runs
in reverse (2) to start autoloading.
After the photo reflector detects 28 per-
forations, the motor stops. The motor
runs in the normal mode (3) and sets
the built-in flash pop-up phase and
completes the autoloading. The frame
counter on the LCD panel indicates "l ".
2. Shutter release
Motor Mode
Normal
Reverse
Table 2-6 Motor Functions
Ooeration
(1) Mirror lifting
(2) Shutter cocking/ mirror down
(3) Mechanical phase switching
(1) Film Rewind
(2) Film Advance
(3) Flash pop-up
When the shutter is tripped, the motor runs in the normal mode and the following
occurs: The mirror goes up
(1),
the exposure is controlled, the shutter is cocked (2), and
the motor stops after setting the film advance phase. Then the motor runs
in
reverse (2)
and advances the film by one frame (8 perforations). Next, the motor runs in normal
mode (3) to set the built-in flash pop-up phase.
3. End of roll detection and automatic film rewind
After 36 exposures are taken or when the film runs out, the film starts to rewind auto-
matically. Before auto rewind starts, the motor runs in normal mode (3) and the mir-
ror's reflex action occurs once and the film rewind phase is set. When the motor runs in
reverse (
1),
film rewind starts.
4. Film rewind completion and return to standby mode
During film rewind, the film perforation is detected. After the frame count of
O
is detect-
ed and a preset delay elapses, the motor stops. Then the motor runs in normal mode
(3), the built-in flash pop-up phase is set. The rewind operation is thereby completed.
* If Custom Function No. 2 has been set to 1, the preset delay after the frame
count
O
is shortened so that the film leader is left outside the film cartridge.
2-13