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RECORDING SECTION
4.13.3 Ink detection method
There are two types of ink detection methods: a light-transmitting type
photo-interrupter method that uses an optical sensor and a reflecting-type
photo-interrupter method. A dot count method that uses software to count
the number of ink ejects (dot count) is incorporated in some products.
• Light-transmitting type photo-interrupter method
When the power is turned ON or at the end of printing, ink is ejected to the
optical axis between the LED (light-emitting section) and the photo-tran-
sistor (light-receiving section. The presence of ink is detected by the
change in photo-transistor output at this time. For the duration that ink is
present, the amount of light reaching the photo-transistor decreases by the
ejected ink. When there is no more ink, the amount of light reaching the
photo-transistor does not change.
4–62
BJ cartridge
Light-receiving
section
Ink detection sensor
(light-transmitting type photointerrupter)
Fig. 4-68 Light-transmitting Type Photo-interrupter Method
Light-emitting
section
Amount of arriving light
decreases.
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