The pump encoder is a photo-interruptive type sensor. It reads the slits on the pump motor's encoder film to control the amount of pump motor rotation.

Valve open/closed detection sensor

The photo-interrupter-type valve open/closed detection sensor detects the valve cam state.

When the link that operates in conjunction with the valve cam shields light, this sensor detects that the ink supply valve has been opened.

Ink detection sensor

Presence of absence of ink in the ink tank is detected according to whether the two hollow needles are electrically connected.

When the ink level in the ink tank lowers below the wall around the hollow needle at the air passage, this hollow needle is electrically disconnected form the hollow

needle located on the ink supply side, thus detecting that the printer has run out of ink.

Head management sensor

The photo-transmission-type sensor detects that the printhead is discharging ink.

The carriage moves to and stops at the detection positions for individual nozzle arrays. When the carriage is at a stop, nozzles discharge ink on after another.

The sensor detects each nozzle due to the voltage change caused when ink discharged from the nozzle blocks the sensor light.

Non-discharging nozzle detection is carried out at the following timings:

- After the execution of Cleaning 1, Cleaning 2, Cleaning 3, Cleaning 6 or Cleaning 10

- After the number of copies that has been set by the user menu choice Nozzle Check Frequency have been printed

If more than a specified number of non-discharging nozzles have been located in one session of non-discharging nozzle detection, the normal cleaning sequence is

launched before a second session of non-discharging nozzle detection is conducted. If more than a specified number of non-discharging nozzles are located in the

second session of non-discharging nozzle detection, the normal (High) cleaning session is launched before a third session of non-discharging nozzle detection is

conducted.

If 30 or more non-discharging nozzles and less than 100 non-discharging nozzles per train are located as a result of the third session of non-discharging nozzle

detection, the print operation can resume after the message display as needed. If 100 or more non-discharging nozzles are located, a head replacement prompt

message is displayed.

2-82

F-2-76

Ink tank

Needle (ink supply)

F-2-77

Printhead

Nozzle unit

Head management

sensor unit

F-2-78

Slits