Title: Switch assembly having movable contact face configuration for penetrating frost or ice layer on adjacent contact surface

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Claims: I claim:

1. An automatic door operator having a control circuit connected to an electrically controlled motor means for controlling door movement in a freezing environment wherein frost forms on the surfaces within the environment, comprising a control switch adapted to be connected in said control circuit and having a pair of opposed electrical contacts, said contacts having opposed contact faces and said contacts solely moving on a line essentially perpendicular to said contact faces for opening and closing an electrical conductive path therebetween in response to the movement directly toward and away from each other on the line through said contacts, a first of said contacts having the contact face formed with a pimple and the other of said contacts having the contact face with a plurality of serrations defining a series of sharp contact peaks, said pimple defining a penetrating means to disrupt frost on said serrations of the other of said contacts and permit said pimple to move into conductive engagement with said second contact.

2. The automatic door operator of claim 1 wherein said pimple is a sharp pin-like projection centrally located on the contact and substantially spaced from the outer periphery of the contact.

3. The automatic door operator of claim 1 wherein said pimple is a sharp pin-like member terminating in a sharp point adjacent said serrations, said serrations including a plurality of parallel, generally triangular shaped serrations defining upper or outer ridge line surfaces.

4. The automatic door operator of claim 1 wherein said switch includes a rating on the order of 4 amps, at 24 volts of 60 Hertz alternating power.

Other info:

Inventors: Runft, Arthur J. (Mequon, WI, US)

Application Number: 629057
Filing Date: 1975-11-05
Publication_date: 1978-02-14
Assignee: Kelley Co., Inc. (Milwaukee, WI)
Primary Class(es): 200/279 200/52R, 200/237, 200/239, 200/244
Other Classes:
US Patent Ref:

1892008	Dec, 1932	Ross	200/244.
2490020	Dec, 1949	Enzler	200/242.
2788420	Apr, 1957	Mathews et al.	200/279.
3168165	Feb, 1965	Bagnusco	200/61.
3297851	Jan, 1967	Jaquet	200/244.
3531799	Sep, 1970	Rendler	200/253.
3842221	Oct, 1974	Dayet et al.	200/52.
3922814	Dec, 1975	Runft	200/279.

Other Refs:
Primary Examiner: Scott, James R.
Assistant Examiner:
Attorney: Andrus, Sceales, Starke & Sawall