| United States Patent | 5,812,314 |
| Kuriaki, et. al. | Sept. 22, 1998 |
Abstract
A lens contamination preventive device comprises a gas jetting device for jetting out gas and a gas suction device for suctioning gas which are disposed to face each other with respect to an optical axis of light emitted through a lens. The gas jetting device and the gas suction device are disposed so as to form a layer of gas jet stream in the vicinity of a surface of the lens. The gas jetting device has a gas jetting port, a width of which is greater than a diameter of the lens. The gas suction device has a rate of suction greater than a rate of jet from the gas jetting device.
| Inventors: | Kuriaki; Hiroyuki (Kaga, JP); Hirasawa; Kazusige (Kawanishi, JP). |
| Assignee: | Matsushita Electric Industrial Co., Ltd. (Osaka, JP). |
| Appl. No.: | 803,178 |
| Filed: | Feb. 19, 1997 |
| Feb. 29, 1996 [JP] | 8-042569 |
| Intl. Cl. : | G02B 7/18, B23K 9/02 |
| Current U.S. Cl.: | 359/507; 219/121.5; 219/121.68; 359/808; 359/894 |
| Field of Search: | 359/507, 509, 667, 808, 811, 894, 809; 219/121.5, 121.51, 121.6, 121.63, 121.67; 15/300.1, 320-322 |
| 3,696,230 | Oct., 1972 | Friedrich | 359/509 |
| 4,778,693 | Oct., 1988 | Drozdowicz et al. | 219/121.6 |
| 4,987,286 | Jan., 1991 | Allen | 219/121.6 |
| 63-9175 | Jan., 1988 | JP | 359/509 |
| 2-73141 | Mar., 1990 | JP | 359/509 |