[54] PROJECTOR
[75] Inventors: Yasumasa Sawai, Sakai; Nobuo Mushiake, Osaka; Hakuzo Tani,
Takatsuki, all ol Japan
[73] Assignee: Minolta Co., Ltd., Osaka, Japan
[ * ] Notice: This patent issued on a continued prosecution application filed under 37 CFR 1.53(d), and is subject to the twenty year patent term provisions ol 35 U.S.C. 154(a)(2).
[21] Appl. No.: 08/958,826
[22] Filed: Oct. 28, 1997
[30] Foreign Application Priority Data
Oct. 31, 1996 [JP] Japan 8-290844
Oct. 31, 1996 [JP] Japan 8-290845
[51] Int. CI.7 G03B 21/26; G03B 21/00
[52] U.S. CI 353/30; 353/31; 353/33
[58] Field of Search 353/30, 31, 33,
353/34, 37, 81, 69; 349/8, 9; 359/833, 834,
836, 837
[56] References Cited
U.S. PATENT DOCUMENTS
5,097,323 3/1992 Sato et al 358/60
An optical device includes four prisms joined into one body to combine light beams, a first type ol multilayer coating being provided between joining surfaces ol the four prisms, and a second type ol multilayer coating being provided on at least one non-joining surface ol the lour right-angle prisms. Each prism bears the first type ol multilayer coating and the second type ol multilayer coating on two or less surfaces thereol. The optical device is lurther provided with liquid crystal image panels to combine optical images and project a combined optical image to a screen.
12 Claims, 7 Drawing Sheets
