Sensor (2Nd Transfer Roll Hp); Printhead Assembly - Lexmark X940e Service Manual

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Sensor (2nd transfer roll HP)

The sensor (2nd transfer roll HP) is used to detect the home position of the 2nd transfer roll assembly.

Sensor (2nd transfer

roll retract HP)

The printhead scans the four drum surface with four laser beams. It consists of four components: laser diode

(LD) card assembly, printhead motor, polygon mirror, and four start of scan card assemblies.

1. LD card assembly – generates a laser beam with the four LDs. The beam is turned on or off according to

a print data signal. The printhead contains 4 LD card assemblies for the colors CMY & K.

2. Printhead motor/polygon mirror – the polygon mirror is mounted to the shaft of the printhead motor, and is

rotated at a high speed by the printhead motor. The mirror rotation shifts the incidence and reflection

angles of a laser beam to scan the laser beam in the drum axial direction. The laser beam reaches the

polygon mirror as it passes through multiple lenses, mirrors, and windows. The laser beam then arrives at

the drum surface.

3. SOS card assembly – when a laser beam hits the SOS sensor on the SOS card assembly, the beam is

converted to an electrical signal (SOS signal), and detects the initial position where a scan starts on each

When a laser beam is scanned across the drum surface from one end to the other while turning on and off the

beam, one line of latent image is created. If the scanning by the laser beam is repeated while rotating the drum,

a two-dimensional image is created. The resolution in the scanning direction (from right to left) is determined by

the rotational speed of the printhead motor, depending on how quickly the laser is adjusted. The resolution in the

process direction (from top to bottom) is determined by the rotational speed of the printhead motor. (The higher

the scanning speed becomes, the sooner the scanning of the next row can be started.)

Service Manual

2nd transfer

roll assembly

Transfer belt

2nd transfer roll

retract motor