1. Field of the Invention
The present invention relates generally to the field of hand-held implements and more particularly to the type of instrument in which a unit is reciprocated longitudinally between retracted and extended positions in response to axial oscillation of a portion of the instrument housing.
2. Description of the Prior Art
The prior art is replete with proposals for hand-held implements of the type having an elongate housing with a cap, sleeve, ring or similar manually accessible actuating portion which is rotated back and forth (axially oscillated) by the user to shift (reciprocate) a writing, marking or similar unit longitudinally between a retracted (concealed) position within the housing and an extended (point exposed) position projecting through the lower (writing) end of the housing.
Several of these prior proposals have met with some degree of commercial acceptance. Even the more successful structures, however, have been relatively complex and hence difficult and expensive to produce and somewhat inconvenient to use and maintain. For instance, U.S. Pat. Nos.:
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are representative of various prior art proposals for implements with oscillable type mechanisms which not only are complicated and expensive in terms of the number and complexity of parts and their manufacture and assembly, but in some instances require special units, special unit adapters, or special handling procedures.
The design disclosed in U.S. Pat. No. 4,025,204 eliminates the need for special units or unit adapters or handling procedures, and otherwise provides various structural and functional improvements over the aforementioned prior art. Thus, while comprising a significant advance over such prior art, the mechanism of U.S. Pat. No. 4,025,204 still requires the manufacture and assembly of a number of discrete components--some of which involve relatively close dimensions and tolerances.
Although not specifically directed to oscillable type mechanisms, various attempts have been made in the past to utilize the resiliency or flexibility of certain synthetic resins by combining various of the components used in retractable type writing and marking instruments. For instance, U.S. Pat. Nos. 2,898,887, 3,200,792, 3,298,357 and 3,458,264 propose plastic components having integral hinges or spring sections. In each instance, however, the suggested design involves only a simple hinge-like or compressive movement as those in the art would consider to be applicable primarily to push button or push clip type mechanisms involving simple transmission of linear forces.
U.S. Pat. No. 3,850,531 illustrates a pencil with an automatic lead feed mechanism in which the head of a drive screw is disposed between and revolved in step-like increments by a pair of opposed sets of angularly projecting rachet teeth. While suggesting conversion of reciprocal to rotary motion, this Patent does not hint at an integrant drive member, conversion of oscillating to reciprocating motion, or links mounted to swivel in a complex motion between folded and erect positions to alternately move a pair of sleeve sections toward and away from each other.
The devices illustrated in U.S. Pat. Nos.:
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utilize helically arranged resilient plastic strips as spring elements for biasing a valve head, or the like, toward a closed position. Upon flexure, the resilient strips would be expected to impart a slight oscillatory motion to the valve head as it is moved in and out during use. Such an incidental and minor oscillatory motion, however, would not suggest an integrant drive member comprising a pair of sleeve sections, one being manually oscillable to reciprocate the other via a pair of links which swivel between folded and erect positions.
U.S. Pat. No. 3,771,881 illustrates a dispenser having a propel-repel mechanism utilizing a pleated web which unfolds in an "accordion" fashion to transmit rotary motion from a base member directly to a carrier to move the carrier up a helix or thread. The web is described as being of sufficient width and thickness to transmit rotary force without undue bending about its axis, but otherwise it obviously is not involved in support of the carrier. Such support is provided entirely by the helix or thread. Accordingly, the pleated web is in no way suggestive of links which are longitudinally stiff and which serve as the sole means of supporting a reciprocal sleeve portion against an axially applied pressure.