Print Registration Control — Closed-Loop Color Alignment

Press Line

Web speed 180 m/min

Tension disturbance 12 µm/s

Controller gain K_p 0.60

Registration Error

Cyan e_C

0.0 µm

Magenta e_M

0.0 µm

Yellow e_Y

0.0 µm

Key e_K

0.0 µm (ref)

Print Quality

Registration quality100%

Open-loop — color units drift freely under web-tension disturbance.

How it works

A web offset press prints cyan, magenta, yellow and key(black) from four separate plate cylinders as the paper web races underneath at up to a few hundred m/min. Each unit's impression must land within a few microns of the others, or the print shows visible color fringing. Web tension and speed fluctuations constantly push each unit's phase off target:

de/dt = w(t) − K_p · e(t)

w(t)  = random tension disturbance (µm/s)
e(t)  = registration error of that color vs. the key plate
K_p   = servo controller gain (0 = open loop)

Optical registration-mark sensors read each color's mark position relative to the key plate thousands of times per second. A servo motor then advances or retards that cylinder's rotational phase by a proportional amount, Δφ = K_p·e ⁄ r (r = cylinder radius), continuously cancelling the drift — this is the closed-loop feedback loop this simulator animates for cyan, magenta and yellow against a fixed black reference.

Web speed — faster webs need faster correction cycles to hold the same tolerance.
Tension disturbance — models mechanical noise from splices, roller eccentricity and tension-zone coupling.
K_p and the Closed-loop toggle — the higher the gain, the harder the servo pulls error back to zero; with the loop off, error random-walks unchecked.
The dot trail on the web shows each color stamped only once it has passed under its own cylinder — misalignment between the four colors on a given trail segment is the registration error, exactly as it appears on a real printed sheet.

Cyan unit Magenta unit Yellow unit Key (black, reference)

⚠ Couldn't load the 3D engineThree.js failed to load from the CDN. Check your connection and reload.