Instruction manual

AccuBeam 3 Digital Line Guide Sensor

Profile’s memory. For the material used in this example the parameters will be set to the

following values:

a) Pattern is set to Lt-Dk-Lt (Light-Dark-Light) because the registration line is darker than

the surrounding background.

b) Scan Direction is set to R-to-L (Right-to-Left) so that the sensor will evaluate objects in its

field of view beginning with those on the far right. As it scans from right to left, the first

line it encounters that satisfies the Min/Max width rules (described in the next step) will be

the narrow line closest to the right edge of the web – the line we want to track.

c) Max Center is set to 12 and Min Center is set to 9. These parameters define the

maximum and minimum acceptable widths of the registration line. To accommodate

some variation in line width the Max Center value is set 12.5% larger than the nominal

width and the Min Center value is set 12.5% smaller than the nominal width.

Note: Refer to page 71 for more information about the Min/Max parameters.

Note: The settings for the Min/Max parameters range from 0 to 127 and are scaled in

units of “pixels”, or 0.0049” [0.124 mm].

d) Min Left and Min Right are both set to 36. These parameters define the minimum widths

of the white areas covered by the selection window adjacent to the registration line. To

accommodate some variation in these widths they are both set 12.5% smaller than their

nominal widths.

e) Max Left and Max Right are both set to 127. These parameters define the maximum

widths of the white areas adjacent to the registration line. Setting them to 127 removes

any restriction on the maximum width of these areas, so either one could extend beyond

the edge of the sensor’s field of view.

f) LED Color is set to Red. Auto-calibration will select the lighting color that produces the

greatest contrast between the registration line and background. For black and white

patterns (like the one in this example) any LED color will work well, but for colored lines

and backgrounds there will often be one particular LED color that produces a significantly

greater contrast.

g) LED Angle is set to Diffuse. This lighting angle provides the best contrast between the

registration line and background on dull, non-glossy materials like the one used in this

example. To track a dark line printed on metallized film or to track the edge of glossy film

material, the best angle would be Reflective. For certain holographic materials the Side

setting may work best.

h) Filter is set to 4. This parameter helps the sensor ignore scratches, smudges, and other

stray marks by deliberately blurring the image. Higher settings create more blurring, so

the auto-calibration routine will select the highest setting that blurs the edges of the

registration line without totally obscuring it. Generally, higher settings will be selected only

for wider registration lines.

i) Threshold is set to 10 - a value that is approximately 50% of the contrast value of the

registration line’s edges. This will filter out other edges in the sensor’s field of view that

fall below this value.