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United States Patent 4,862,978
Borchard Sept. 5, 1989

Combination dust cover and air screen

Inventors: Borchard; John S. (36 Whitney Tavern Rd., Weston, MA 02193).
Appl. No.: 309,183
Filed: Feb. 13, 1989
Intl. Cl.: G01G 21/28;
U.S. Cl.: 177/180.; 177/238.;
Field of Search: 126;180-182;238

References Cited

U.S. Patent Documents

4,762,190 Aug., 1988 Meixner 177/181
4,789,034 Dec., 1988 Luchinger et al. 177/181
4,798,250 Jan., 1989 Knothe et al. 177/181

Foreign Patent Documents

1100342 Jan., 1968 GBX 177/126

Primary Examiner: Miller, Jr.; George H.


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.

8 Claims, 12 Drawing Figures

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