U.S. Patent No. 4,677,798

Patent No. 4677798, page 1

Patent No. 4677798, page 2Patent No. 4677798, page 3Patent No. 4677798, page 4Patent No. 4677798, page 5Patent No. 4677798, page 6Patent No. 4677798, page 7Patent No. 4677798, page 8