US 6,383,721 Bl May 7, 2002
(54) MARKING METHOD AND MARKED RESIN MOLDED PIECE
(75) Inventors: Yoshihiko Kamimura; Hirofumi Kikuda, both of Tsuruga (JP)
(73) Assignee: Matsushita Electric Industrial Co., Ltd., Osaka (JP)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.
(21) Appl. No.: 09/442,437
(22) Filed: Nov. 17, 1999
(30) Foreign Application Priority Data
Nov. 17, 1998 (IP) 10-326371
(51) Int. C I. B41M 5/00
(52) U.S. CI 430/320; 430/346; 430/945;
(58) Field of Search 430/346, 945,
(56) References Cited
U.S. PATENT DOCUMENTS
4,307,047 A 12/1981 Edinger et al.
4,391,764 A 7/1983 Edinger et al.
4,578,329 A 3/1986 Holsappel
Marks having clearly divided plural colors can be formed on a resin molded piece at low cost. A resin molded piece with marks having clearly divided plural colors is obtained. A resin molded piece is formed by combining plural base materials molded and processed by using a mixture of resins and fillers changing in different colors by irradiation with energy ray, and the surface of this resin molded piece is irradiated with energy ray to mark the irradiated positions with plural colors, and forming a marked resin molded piece. Preferably, the resin molded piece is a keytop of keyboard used in an electronic appliance.
25 Claims, 5 Drawing Sheets