Novel exposure system using light-emitting diodes and an optical fiber array for printing serial numbers and code marks

Abstract

Feasibility of a novel exposure system to print serial numbers and two-dimensional code marks was demonstrated. The new system used light-emitting diodes (LEDs) combined with an optical fiber matrix array as a light source. At first, as preparatory experiments, code mark patterns were printed using a prototype exposure system without using the optical fiber array but using the combination of arrayed LEDs with a central wavelength of 428 nm, spherical lenses, and rod lenses. Although the code mark patterns were successfully printed, it took too much exposure time. For this reason, bullet-type LEDs with a high power and a shorter wavelength of 405 nm were used and the optical fiber matrix array was adopted. Because the emitted light rays were efficiently taken into the fiber, and the resist sensitivity was improved, practically available short exposure time of less than 2 s was obtained.

Readability dependence on lithography conditions for printing code marks using a squared optical fiber matrix and light-emitting diodes

“…For this reason, a new exposure method using an LED matrix as an exposure source was proposed in past research. [12][13][14] In addition, optical fibers with squared ends were developed for improving the shapes of mark cells, 15) and the optical fibers were bound in a matrix. 16) Because bright and dark codemark cells with a square shape are directly assigned by simply lighting and extinguishing LEDs, this combination of LED and fiber matrices is very effective for printing arbitrary code marks easily but precisely.…”