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| United States Patent | 4,862,979 |
| Borchard | Sept. 5, 1989 |
Combination dust cover and air screen
| Inventors: | Borchard; John S. (36 Whitney Tavern Rd., Weston, MA 02193). |
| Appl. No.: | 188,538 |
| Filed: | Apr. 29, 1988 |
| Intl. Cl.: | G01G 23/32; |
| U.S. Cl.: | 177/181.; 177/238.; |
| Field of Search: | 180;181;182;238 |
References Cited
U.S. Patent Documents
| 3,165,225 | Mar., 1963 | Reitzel | 220/331 |
| 3,882,947 | May, 1975 | Appius | 177/238 |
| 3,994,415 | Nov., 1976 | Hodge | 220/331 |
| 4,253,568 | Mar., 1981 | Long | 220/340 |
Primary Examiner: Marcus; Stephen
Assistant Examiner: Reece; Gilbert W.
Abstract
A hinged dust cover used in combination with an electronic balance whereby the cover converts to an air screen during weighing operations. In the fully closed position the cover protects the weighing pan and various controls and displays from the ingress of dust and other contaminants as well as inadvertent operation. In the fully open position full access by the balance's operator is available to the weighing pan and controls. In the cover's intermediate position, the cover forms an enclosure about the weighing pan thereby isolating the weighing pan and mass being weighed from dust and air movement while at the same time making the various controls fully available to the balance's operator.
6 Claims, 12 Drawing Figures
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