US3392252A

US3392252A - Momentary switch having normally engaged contacts actuated by a conductive member

Info

Publication number: US3392252A
Application number: US570206A
Authority: US
Inventors: Philip N Crawford; Walter E Taylor
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1966-08-04
Filing date: 1966-08-04
Publication date: 1968-07-09
Anticipated expiration: 1985-07-09
Also published as: DE1640043B1; CA814019A; FR1533649A; GB1131999A; JPS4418771B1

Description

y 9, 1953 P. N. CRAWFORD ETAL 3,392,252

MOMENTARY SWITCH HAVING NORMALLY ENGAGED CONTACTS ACTUATED BY A CONDUCTIVE MEMBER Filed Aug. 4, 1966 FIG 5 PH/L /P N. CRAWFGRD WAL TE E. TAYLOR INVENTORS United States Patent 3,392,252 MOMENTARY SWITCH HAVING NORMALLY ENGAGED CONTACTS ACTUATED BY A CONDUCTIVE MEMBER Philip N. Crawford and Walter E. Taylor, Rochester,

N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Aug. 4, 1966, Ser. No. 570,206 7 Claims. (Cl. 200-160) ABSTRACT OF THE DISCLOSURE A momentary break switch has normally engaged contacts which, upon actuation of a push button, are urged apart by a blade member of electrically conducting material. The electrical path between the contacts is maintained by the blade member until it passes from between the contacts, then allowing the contacts to spring together but interrupting the electrical path there-between prior to their re-engagment for a substantially uniform increment of time, regardless of the rate of actuation of the push button.

This invention relates to an electrical switch mech anism and more particularly to an electrical switch which is normally closed but is opened momentarily upon de pression of an associated push button.

The utilization of make and break switching arrangements has become increasingly important with the rapid development of electrical control systems. With the advent of increased technology and sophistication in systems of this type, a demand has been created for switches which will operate in a uniform manner during repetitive use over an extended period of time.

It is therefore an object of this invention to provide an improved electrical switch which is normally closed and which can be opened only momentarily and for a substantially uniform increment of time, upon movement of an associated push button or other actuating means, regardless of the rate of movement thereof.

It is a further object of this invention to provide a momentary break, electrical switch which is characterized by simplicity of construction and ease of operation, such switch during its normal operation cycle being continuously closed except for a brief predetermined increment of time while the associated push button is depressed.

These objectives have been attained in the present invention by providing a pair of normally engaged switch contacts which are urged apart upon depression of a push button or other actuating means by a blade member of electrically conducting material, said blade member being disengaged from the contacts as the push button reaches the end of its depressed path, thus allowing the contacts to spring together but interrupting the electrical contact therebetween prior to their re-engagement.

Other objects of the invention will appear from the following description, reference being made to the accompanying drawings wherein:

FIG. 1 is an isometric view of an electrical switch incorporating the elements of the invention disclosed herein;

FIGS. 2, 3, 4, and are schematic illustrations showing positions assumed by certain elements of the device of FIG. 1 during various stages in the operation thereof.

Referring now to FIG. 1, a base plate 10 is shown in phantom. Embedded in base plate 10 is a hollow circular guide member 11 open at the upper end thereof and closed at its bottom. Guide member 11 is constructed of plastic or any other non-conductive material. Reciprocatably mounted in guide member 11 for sliding movement therein is a circular base member 12 having a control button 13 projecting therefrom.

As may readily been seen, circular base member 12 has a hollow recess disposed at the lowermost end thereof which accommodates the upper portion of a coil compression spring 14. The lower portion of coil spring 14 rests on the bottom wall of circular guide member 11. Circular guide member 11 has

elongated slots

15, 16 on opposite sides thereof. Base member 12 has a pair of additional slots 15a, 16a and is positioned so that slot 15a is in alignment with elongated slot 15 and slot 16a is in alignment with slot 16. Projecting through all four slots is a blade 17 which is constructed of an electrically conductive material and is fixedly attached at one end thereof to the upper portion of coil spring 14 by any known expedient for the purpose which will be more fully disclosed below.

Attached to base plate 10 and positioned in the mannot illustrated are fixed switch contact 18 and movable switch contact 19, both of which are constructed of an electrically conductive material. Movable contact 19 in cludes contact plate 19a and a resilient L-shaped member 19b which is self-biased so as to be resiliently urged into abutting position with fixed contact 18.

The operation of the device will now be described. Referring now to FIGS. 1 and 2, the elements of the device are shown in their normal rest position. As described above, L-shapecl member 19b of movable contact 19 is in abutting position with fixed contact 18. Electrical current is thus free to flow through said contacts. Blade 17, under the resilient urging of coil spring 14, is yieldably positioned against fixed contact 18. As may most clearly be seen with reference to FIG. 2, the contacting portion of blade 17 is bent slightly so that the uppermost portion thereof is turned away from fixed contact 18. Upon depression of control button 13, blade 17 moves in a downward direction thereby camming resilient L-shaped member 19b of movable contact 19 in the direction indicated by the arrow in FIG. 2, away from fixed contact 18 and to a new position which may most clearly be seen in FIG. 3. Electrical current, however, continues to flow through fixed contact 18 and movable contact 19 by virtue of the fact that blade 17 is constructed of electrically conductive material. When blade 17 reaches the position illustrated in FIG. 4, resilient L-shaped member 19b jumps off the uppermost portion of blade 17 and moves to the position illustrated in solid lines. It is during this brief interval after the L-shaped member 19b jumps off blade 17 and before it hits fixed contact 18 that current flow is momentarily halted between fixed contact 18 and movable contact 19.

As the operator relieves pressure from control button 13, control button 13 and blade 17 are urged in an upward direction under the influence of coil spring 14. The outwardly bent end portion of blade 17 now moves in the direction of the arrow shown in FIG. 4, and rides over L-shaped member 19b in the manner shown in FIG. 5. During this return movement of control button 13 and blade 17, movable contact 19 and fixed contact 18 remain in abutting or engaged position thus allowing the flow of current to continue therebetween.

It will thus be seen that the time interval during which current fails to flow between contact 18 and contact 19 remains substantially constant, regardless of the speed with which control button 13 and blade 17 are depressed by the operator, since such time interval is determined only by the snapping action of L-shaped member 19b. In addition, the present arrangement, due to the wiping action of blade 17 as it moves between

contacts

18 and 19, provides for the maintenance of clean switch contact surfaces.

Having described the general form of the present invention, it should be understood that the form illustrated herein has been selected to facilitate the disclosure of the invention rather than to limit the number of forms which it may assume, and various modifications, adaptations, and alterations may be applied to the form shown to meet the requirements of practice without departing from the spirit or scope of the present invention. For example, the switch actuating means may be of any known type and need not be manually operable.

We claim:

1. In an electrical switch mechanism:

(a) a pair of normally abutting switch contacts;

(b) actuating means movable over a predetermined path from a first position to a second position and back to said first position;

(c) electrically conductive means responsive to movement of said actuating means for passing between said contacts as said actuating means moves from said first position to said second position thereby separating said contacts but maintaining a flow of electrical current between said contacts while between and engaging said contacts;

(d) said electrically conductive means and said contacts having means cooperating (1) to interrupt electrical current flow between said contacts for a predetermined time as said electrically conductive means passes wholly from between said contacts and (2) to maintain electrical current flow through said contacts after said predetermined time and as said actuating means returns to its said first position.

2. The electrical switch mechanism according to claim 1 wherein said electrically conductive means comprises a blade member having a bent end portion which is adapted to exert a camming action upon at least one f said contacts as said blade member passes between said contacts and which permits said contacts to snap together after passing therebetween, thereby briefly interrupting current flow between said contacts.

3. The electrical switch mechanism according to claim 1 wherein a single coil spring is provided for biasing said actuating means toward said first position and for yieldably maintaining said electrically conductive means on one of said contacts.

4. The electrical switch mechanism according to claim 1 wherein said electrically conductive means exerts a wiping action on the surfaces of said contacts as it passes therebetween.

5. An electrical switch having an open state and a closed state, said switch comprising two contacts biased toward one another so that said contacts are normally touching and the switch is normally closed; conductive means adapted to be inserted between said contacts to separate them while maintaining the switch in a closed state, and means for withdrawing said conductive means from said contacts along one of said contacts so that when said conductive means clears said one contact the switch is in an open state for a brief predetermined period of time.

6. In an electrical switch mechanism:

(a) a pair of normally engaged switch contacts;

(b) actuating means movable over a predetermined path from a first position to a second position;

(c) electrically conductive means responsive to movement of said actuating means for passing between said contacts as said actuating means moves from said first position to said second position thereby separating said contacts while maintaining the switch closed;

(d) said electrically conductive means and said contacts cooperating to interrupt electrical current flow between said contacts for a predetermined time as said electrically conductive means passes wholly from between said contacts.

7. An electrical switch hasing an open state and a closed state, said switch comprising two contacts at least one of which is biased toward the other for closing the switch; conductive means positionable between said contacts to separate them while maintaining the switch in a closed state, and means for withdrawing said conductive means from said contacts so that the switch is in an open state for a brief predetermined period of time.

References Cited UNITED STATES PATENTS 1/1937 Schellenger 200164 XR 4/1940 De Vincenzi 200