US 3571544 A
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United States Patent Inventor Hilary William Sheehan 1408 Leneva Lane, Pasadena, Tex. 77502 769,189
Oct. 21, 1968 Mar. 23, 1971 Appl. No. Filed Patented MAGNETIC KEY OPERATED SWITCH FOR ELECTRICALLY OPERATED HAND TOOLS 2 Claims, 5 Drawing Figs.
References Cited UNITED STATES PATENTS 3/1916 Meriwether 2,625,630 1/1953 Eckles 200/164 2,735,908 2/1956 Peretti et al. 200/157 2,767,278 10/1956 Collins 335/302X FOREIGN PATENTS 1,140,952 12/1 962 Germany ZOO/61.58
1,138,123 12/1968 Great Britain 335/205 Primary Examiner-Robert K. Schaefer Assistant Examiner-Robert A. Vanderhye Attorney-Ranseler O. Wyatt ABSTRACT: This invention relates to a switch for electrically operated hand tools, and the like, wherein the contact points of the switch are normally maintained yieldably separated,
and one arm of said points is movable, and a ring is provided,
for the user of the device having a magnetized key, shaped to fit the particular key opening of the tool, so that when the key, mounted on a ring worn on a finger of the user, is inserted into the key opening, the movable arm will be moved into closed position, completing an electrical circuit through the motor of the tool, and upon removal of the key, for any reason, the tool will be immediately deactivated.
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/ w I I I 1a 0 1111] 6 .1 I 11111 1111. j I I l MAGNETIC KEY OPERATED SWITCH FOR ELECTRICALLY OPERATED HAND TOOLS SUMMARY OF THE INVENTION A switch for electrically operated hand tools comprising a fixed and a movable contact arm, contact points mounted on the extended ends of said arms, a key, opening in the housing of the hand tool and a magnetized key, having the same contour as the key opening, mounted on a finger ring and adapted to be inserted into said key opening to move said movable arm and to move said contact points into contact with each other and to maintain said contact until said key is removed from said key opening.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the key mounted on a ring and showing a finger to receive said ring in dotted lines.
FIG. 2 is a side elevational view of the ring key.
FIG. 3 is a side elevational view, insection, showing the switch mounted in a housing and showing the key in the key opening in dotted lines.
FIG. 4 is an elevational perspective view of a hand tool having the key opening to receive the magnetized key.
FIG. 5 is an electrical diagramillustrating the circuit employed.
DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings, the numeral l designates a tool housing such as the handle of an electric drill in which a key opening 2 is formed of a particular, selected contour. A block of mag netized metal, contoured to exactly fit the contour of the opening 2, forms the key 3, which is mounted on a finger ring.
In the housing 1 is mounted the electric circuit control plange 4 and the spring loaded movable contact arm 5. A control arm 6 is mounted on the extended end of the contact arm 5, and is formed of a metal responsive to the magnetic force of the magnetized key 3, the extended end of the control arm 6 being positioned opposite the key opening 2. A fixed contact arm 7.is mounted in the housing 1 as the contact terminal 9. Mounted on the arm 5 is the pivotal contact member 8 which is yieldably urged in one direction by the spring 13 to provide a wiping action as the contact members 8, 9 are brought together and separated. An electric cord, as 10, extends through the housing 1 and the wires thereof are connected to the respective contact arms. The circuit is carried through the plate 4 to the motor 14.
The ring 11 on which the key 3 is mounted may be worn on the finger of the user, or expanded to be worn over the glove 12 of the user. When the key 3 is inserted in the opening 2, the control arm 6 will be drawn to the key 3 and the arm 5 pivoted to place the contact point 8 into contact with the point 9, thus completing the circuit through the motor and activating the tool. In the event the user drops the tool, or it becomes disengaged from his hand in any manner, the key 3 will be removed from the opening 2, and the arm 5 will move the point 8 out of contact with the point 9, and the motor of the tool will be deactivated.
I. In a switch for electrically operated hand tools, a switch housing, a spring mounted movable arm and a fixed arm, said arms being mounted in said housing and connected into an electrical circuit from a source of power through an electrically operated motor, contact points on said arms, a control arm on said movable arm formed of magnetic responsive metal, an opening in said housing adjacent said control arm and a magnetized key insertable into said opening to move said movable arm into contact with said fixed arm, the said key being mounted on a finger ring to be worn by the user.
2. The device defined in claim 1 wherein the key is mounted on a finger ring which may be adjusted to be mounted on the gloved finger of the user.