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RECORDING SECTION
• Reflecting-type photo-interrupter method + dot count method
When the power is turned ON or at the end of printing, light is emitted
from the LED (light-emitting section) in the direction of the ink tank filled
with liquid ink (black), and the reflected light is detected by the photo-
transistor (light-receiving section). The presence of liquid ink is detected
by the photo-transistor output at this time.
For the duration that there is liquid ink, light is absorbed by the ink, and
does not reach the photo-transistor. When there is no more liquid ink, light
is reflected onto the reflector plate (white) provided inside the ink tank,
and reaches the photo-transistor. Note, however, at the point where the ink
tank runs out of liquid ink, ink still remains absorbed by the ink sponge
and the ink tank has not completely run out of ink. Counting of the number
of ink ejects is started after the no liquid ink state has been detected, and it
is judged that there is completely no more ink when the ink eject count
reaches a specified number.
4–64
Ink detection sensor
(reflecting-type photo-interrupter)
Fig. 4-70 Reflecting-type Photo-interrupter Method
Liquid ink
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