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Magnetic Keyboard Actuator

IP.com Disclosure Number: IPCOM000049600D
Original Publication Date: 1982-Jun-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 106K

Publishing Venue

IBM

Related People

Aaron, RT: AUTHOR [+5]

Abstract

A magnetic keyboard actuator is utilized to produce a reliable keyboard having simple scanning electronics, the keyboard further providing tactile feedback to the operator indicating key operation.

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Magnetic Keyboard Actuator

A magnetic keyboard actuator is utilized to produce a reliable keyboard having simple scanning electronics, the keyboard further providing tactile feedback to the operator indicating key operation.

Fig. 1 depicts a key actuator in its unactuated position, and Fig. 2 depicts the same actuator in its actuated position. The actuator consists of keybutton 11, compression spring 12, keybutton guide 13, magnetic field shunt 14, magnet 15, steel ball 16, keyboard support bracket and bearing guide 17, membrane switch 18, membrane support bracket 19, and telescopic switch plunger 20.

As depicted in Fig. 1, keybutton 11 is supported by energy stored in compression spring 12. Spring 12 is preloaded and positioned between keybutton 11 and plunger 20. The vertical position of plunger 20 is controlled by the location of steel ball 16. The inner spring cavity wall of keybutton 11 locates plunger 20 in the horizontal direction. Steel ball 16 is suspended above membrane switch 18 and held in position by the magnet forces from magnet 15, consisting of a magnetized material such as magnetic rubber.

As keybutton 11 is depressed (Fig. 2), it is supported laterally and directed vertically by guide 13. Plunger 20 at first remains in the position shown in Fig. 1 and telescopes into spring cavity 21 as keybutton 11 moves in the vertical direction. Vertical forces on keybutton 11 and plunger 16 increase as spring 12 is compressed until a breakaway force is generated. When the threshold force (magnetic breakaway force) is reached, steel ball 16 is driven into membrane switch 18 by plunger 20. The steel ball 16 is guided to membrane 18 by bearing guide 17. As membrane 18 is compressed between steel ball 16 and support bracket 19,...