HP 220 - Manual (Page 42)

5Ć10 Functional Overview C3187Ć90000
Detectingthe Media Edges
Line Sensor
The plotter detects the left and right media edges using the line sensor located on the
carriage. The sensor is composed of
D Red LED
D Two lenses (caution required when handling)
D Collector plate
Operation
1 The sensor finds the left media edge when it detects the light from the red LED reflected
off the media surface. The black surface of the drive roller absorbs the light.
Excessive ink deposits on the driveĆroller can fool the sensor by reflecting the light.
2 The sensor goes on to find the right media edge.
3 The media is advanced and the sensor checks for media skew (crooked loading).
Other Functions
The line sensor on the cartridge carriage is also used to
D Detect and measure lines drawn on media when performing cartridge alignment
D Detect and measure lines drawn on media when performingaccuracy calibration
D Scan the setup sheet
Media Margins
HardĆclip side margins provide protection against writing on the drive roller due to media
expansion/contraction or skew. Top and bottom margins are set according to the physical
spacingbetween the pinchĆwheels, overdrive and writinghead. (Specifications ' chapter 1.)
Media Sizes
You can use a wide variety of media sizes, due to the
D Continuous roller
D Spacingof the pinchĆwheels and starĆwheels
D EdgeĆdetection capability
(Specifications ' chapter 1.)