| 发明名称 |
Auxiliary lens system for overhead projectors |
| 摘要 |
A pair of lenses placed one on each side of the projection head of a standard overhead projector can be utilized to change the focal length of the lens from 14 inches to 20 inches and produce the same image size at a projection distance of 15 feet as at a projection distance of only 9.4 feet.
|
| 申请公布号 |
US4350415(A) |
申请公布日期 |
1982.09.21 |
| 申请号 |
US19800183205 |
申请日期 |
1980.09.02 |
| 申请人 |
MINNESOTA MINING & MANUFACTURING COMPANY |
发明人 |
CONRAD, LAWRENCE H. |
| 分类号 |
G02B9/34;G02B15/10;(IPC1-7):G02B15/02;G02B17/00 |
主分类号 |
G02B9/34 |
| 代理机构 |
|
代理人 |
|
| 主权项 |
|
| 地址 |
|
