发明名称 |
Temperature compensating lens system for projection television |
摘要 |
In a projection lens device having at least two plastic lenses for magnification-projecting an original image displayed on a display screen onto a screen, one of the two plastic lens is convex at a center thereof toward the screen and concave at a periphery thereof, and the other lens has a weak positive refractive power toward the screen at a center thereof and a stronger positive refractive power at a periphery thereof. A variation of a lens power due to a change of a surrounding environment is cancelled out by the concave shape at the periphery of the one lens and the positive refractive power at the periphery of the other lens.
|
申请公布号 |
US5272540(A) |
申请公布日期 |
1993.12.21 |
申请号 |
US19910759518 |
申请日期 |
1991.09.13 |
申请人 |
HITACHI, LTD. |
发明人 |
HIRATA, KOJI;YOSHIKAWA, HIROKI;NUMATA, TOORU;WADA, KIYOSHI;MURANAKA, MASAYUKI;YOSHIZAKI, ISAO;YOSHIDA, TAKAHIKO;INAOKA, SHIGERU |
分类号 |
G02B3/12;G02B13/16;G02B13/18;H04N9/31;(IPC1-7):H04N5/74 |
主分类号 |
G02B3/12 |
代理机构 |
|
代理人 |
|
主权项 |
|
地址 |
|