US PATENT SUBCLASS 400 / 491
.~.~ Including cushioning means (e.g., yieldable surface)

Current as of: June, 1999
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400 /   HD   TYPEWRITING MACHINES

472  DF  KEY-BOARD OR KEY LEVER-ACTUATING MECHANISM {12}
490  DF  .~ Key-cap or key-stem structure {5}
491.~.~ Including cushioning means (e.g., yieldable surface) {2}
491.1  DF  .~.~.~> Including underlying air cushion
491.2  DF  .~.~.~> Including spring supporting key cap or key stem {1}

DEFINITION

Classification: 400/491

Including cushioning means (e.g., yieldable surface):

(under subclass 490) Subject matter wherein either said key* cap or said key stem includes means that tends to absorb some of the force exerted by the typist's fingers as the key elements are pressed during typing.

(1) Note. In this subclass the cushion is usually a yieldable or resilient pad.