Linear feel keyswitch with hysteresis
First Claim
1. An actuator assembly for use in a keyswitch comprising:
- a plunger;
first spring means having a substantially linear spring constant for urging said plunger into a non-actuated position;
a switch actuator extendibly coupled to said plunger;
said switch actuator includingsecond spring means comprising a resilient pad having a non-linear spring constant for providing resilient contact with a switching element when said plunger is moved to an actuated position; and
third spring means having a substantially linear spring constant between said plunger and said switch actuator for urging said switch actuator into an extended position,said first, second and third spring means cooperating to provide said actuator assembly with a linear force versus displacement characteristic.
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Accused Products
Abstract
A capactive keyswitch utilizes an arrangement of three spring forces to provide a linear feel, hysteresis, and overtravel. A telescoping plunger assembly includes an outer plunger shaft and an inner plunger shaft slideably mounted therewithin for telescopic extension therefrom. A first spring provides a return force to maintain the keyswitch in its non-actuated condition. A switch actuator is coupled to the inner plunger shaft and includes a resilient foam pad (second spring) to provide resilient contact with a switching element when the plunger is moved to an actuated position. A third spring between the outer plunger shaft and the switch actuator urges the switch actuator, and thereby the inner plunger shaft, into its fully extended position.
21 Citations
8 Claims
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1. An actuator assembly for use in a keyswitch comprising:
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a plunger; first spring means having a substantially linear spring constant for urging said plunger into a non-actuated position; a switch actuator extendibly coupled to said plunger;
said switch actuator includingsecond spring means comprising a resilient pad having a non-linear spring constant for providing resilient contact with a switching element when said plunger is moved to an actuated position; and third spring means having a substantially linear spring constant between said plunger and said switch actuator for urging said switch actuator into an extended position, said first, second and third spring means cooperating to provide said actuator assembly with a linear force versus displacement characteristic. - View Dependent Claims (2, 3)
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4. A linear feel keyswitch assembly with hysteresis for mounting over a switching element on a circuit board comprising:
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a housing; first and second springs having substantially linear spring constants K1 and K3 respectively; a plunger which is spring loaded by said first spring into a first position within said housing; a switch actuator extendibly mounted to said plunger and spring loaded by said second spring into its fully extended position from said plunger; and spring means coupled to said switch actuator and having a non-linear spring constant K2 for providing resilient contact with a switching element when said plunger is moved to an actuated position; whereby the total spring constant KT of said linear feel keyswitch assembly satisfies the equation
space="preserve" listing-type="equation">K.sub.T =K.sub.1 +K.sub.2 K.sub.3 /(K.sub.2 +K.sub.3). - View Dependent Claims (5, 6, 7, 8)
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Specification