2-LASER TRIPLE-CHECK SYSTEM

Matt BradyJames GalloJon LesnerAlex Quehl

Engineering-Design 100, Section 10Group 2Xinli Wu

The Pennsylvania State University

The Problem

Need for a more accurate velocity measurement allows for: Higher-quality picture (micron tolerances) Better handling of paper while being printed

Due to wear and tear, centripetal velocity of rollers changes as time progresses

Without accurate velocity, distorted picture is likely

The Solution

Design measuring paper velocity Measures velocity 3 times:

Time beam of laser 1 is blocked from sensor 1 Time beam of laser 2 is blocked from sensor 2 Time between lasers

Paper length and distance between lasers are both constant

Time /distance = velocity Finds the mean of all 3, minimizing chance for

a flawed calculation

The Prototype

2 rollers in front 2 rollers in back 2 lasers located between front and back

rollers Fixed distance is needed to find velocity Sensor corresponding to each laser Baffle to guide the paper Framing

Example

Internal clock able to measure to the millisecond

First, it takes 4 time measurements, then calculates 3 velocities, using d /∆t (distance / change in time), where: d1 = d2 = 279.4 mm (i.e., length of paper) d3 = 63.5 mm (i.e., distance between sensors) ∆t1 = tb – ta

∆t2 = td – tc

∆t3 = tc - ta

Example (Cont.)

Start Time of Sensor 1 (ta)

End Time of Sensor 1 (tb)

Start Time of Sensor 2 (tc)

End Time of Sensor 2 (td)

3:06:23:125 3:06:23:741 3:06:23:267 3:06:23:893

Velocity 1 Velocity 2 Velocity 3 Mean Velocity

279.4 mm 0.616 s

279.4 mm0.626 s

63.5 mm0.142 s

v1 + v2 + v3

3

453.57 mm/s 446.33 mm/s 447.18 mm/s

449.03 mm/s

∆t1 = tb - ta

∆t2 = td – tc

∆t3 = tc - ta

0.616 s 0.626 s 0.142 s

Conclusion

Optimal accuracy, considering the relatively small number of resources used

Eliminates the risk that comes with taking just one measurement

Ideal for a printer with such a great need for super-precise calculations