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Magnetic Actuator Key Mechanism

IP.com Disclosure Number: IPCOM000078615D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Stillings, WE: AUTHOR [+2]

Abstract

The key mechanism comprises an external housing 10 mounted to a board 11 and an internal actuator mechanism operable by manual pressure applied to button 12. Actuator cup 13 with switch element 14 carried thereby moves in response to downward displacement of plunger 15.

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Magnetic Actuator Key Mechanism

The key mechanism comprises an external housing 10 mounted to a board 11 and an internal actuator mechanism operable by manual pressure applied to button 12. Actuator cup 13 with switch element 14 carried thereby moves in response to downward displacement of plunger 15.

As shown in the force curve of Fig. 2, cup 13 remains in the position shown in Fig. 1 during pretravel displacement of plunger 15.

When the center lines of actuator magnets 16 and 17 become aligned, further displacement of plunger 15 causes cup 13 to follow the plunger to the point where the cup makes contact with the switch element on board 11. The subsequent downward overtravel of the plunger 15 is opposed by magnetic attraction forces between actuator magnets 16 and 17. Thus, the operator experiences a rapid increase in the force upon closing of the switch. Release of the plunger when in the overtravel position produces rapid upward displacement of plunger 15. Due to the attractive magnetic forces between the actuator magnets 16 and 17, cup 13 follows the plunger 15 and rapidly disconnects the switch.

As shown in the force displacement curve of Fig. 2, the force on plunger 15 is due to the combined action of coil spring 18 and bias magnets 19 and 20. The force on plunger 15, from the beginning of downward displacement, has a negative slope until the cup engages the switch and stops its downward motion. From that point further displacement of the plunger 15 is in...