US4523379A — Knife with retractable sheath

Claim 1

Independent Claim 121 words

An implement comprising: a handle having a hollow interior with an opening at one end; a tool fixedly attached to the handle at the opening; a sheath slidably mounted within the hollow interior of the handle to reciprocate between an extended position where said sheath covers the tool and a retracted position where the tool is exposed; a compressible elastic member disposed between the sheath and the tool so that said elastic member is relaxed when the sheath is fully retracted and compressed when the sheath is extended; and means for releasably securing the sheath in its fully extended position, whereby when the sheath is released, the elastic member will extend and impel the sheath into the interior of the handle.

Claim 2

Dependent Claim 121 words

An implement comprising: a handle having a hollow interior with an opening at one end; a tool fixedly attached to the handle at the opening; a sheath slidably mounted within the hollow interior of the handle to reciprocate between an extended position where said sheath covers the tool and a retracted position where the tool is exposed; a compressible elastic member disposed between the sheath and the tool so that said elastic member is relaxed when the sheath is fully retracted and compressed when the sheath is extended; and means for releasably securing the sheath in its fully extended position, whereby when the sheath is released, the elastic member will extend and impel the sheath into the interior of the handle.

Claim 3

Dependent Claim 90 words

An implement as in claim 1, wherein the means for releasably securing the sheath comprises: an elongate latching member slidably mounted within the handle and having a fork at the end proximate the tool, said fork including a pair of tines capable of engaging the sheath when it is in its fully extended position and preventing the sheath from being retracted by the elastic member; and means mounted within the handle cavity for collapsing the tines inward to release the sheath when the latching member is urged toward the tool.

Claim 4

Dependent Claim 47 words

An implement as in claim 2, wherein the latching member includes a button at the end remote from the tool, said button extending out of the handle so that a user can depress the button to urge the latching member toward the tool and release the sheath.

Claim 5

Dependent Claim 14 words

An implement as in claim 3, wherein the button is recessed in the handle.

Claim 6

Dependent Claim 70 words

An implement as in claim 2, wherein each tine on the fork terminates in an inclined surface, and wherein the means for collapsing the fork tines inward comprises a pair of inclined surfaces fixedly mounted in the handle, said inclined surfaces on the collapsing means mating with the inclined surfaces on the tines so that the tines are forced inward as the latching member is urged toward the collapsing means.

Claim 7

Dependent Claim 17 words

An implement as in claim 2, further comprising means for retaining the sheath in its retracted position.

Claim 8

Dependent Claim 16 words

An implement as in claim 6, wherein the retaining means comprises detents on the latching member.

Claim 9

Dependent Claim 15 words

An implement as in claim 1, wherein the compressible elastic member is a coil spring.

Claim 10

Dependent Claim 51 words

An implement as in claim 8, wherein the coil spring is secured at one end relative to the tool and is free at its other end to engage the sheath as it is extended, said spring not extending a sufficient distance to engage the sheath when the sheath is fully retracted.

Claim 11

Dependent Claim 124 words

A safety knife comprising: an elongate handle having a hollow interior with openings at each end; a knife blade fixedly secured in one opening of the handle by at least one post, the periphery of the blade being spaced apart from the interior wall of the opening; a protective sheath having four side walls and being open at either end, said sheath having slots in a pair of opposite side walls, which slots are received on the post to allow the sheath to slide between an extended position where the knife blade is fully covered and a retracted position where the sheath is fully received within the handle; and means for retracting the sheath from its fully extended position to its fully retracted position.

Claim 12

Dependent Claim 124 words

A safety knife comprising: an elongate handle having a hollow interior with openings at each end; a knife blade fixedly secured in one opening of the handle by at least one post, the periphery of the blade being spaced apart from the interior wall of the opening; a protective sheath having four side walls and being open at either end, said sheath having slots in a pair of opposite side walls, which slots are received on the post to allow the sheath to slide between an extended position where the knife blade is fully covered and a retracted position where the sheath is fully received within the handle; and means for retracting the sheath from its fully extended position to its fully retracted position.

Claim 13

Dependent Claim 65 words

A safety knife as in claim 10, wherein the means for retracting the sheath comprises: a compressible elastic member mounted inside the handle so that said member is compressed as the sheath is extended; and means for releasably securing the sheath in its fully extended position, whereby when the sheath is released, the elastic member will extend and impel the sheath into its retracted position.

Claim 14

Dependent Claim 92 words

A safety knife as in claim 11, wherein the means for releasably securing the sheath comprises: an elongate latching member slidably mounted within the sheath and having a fork at one end proximate the knife blade, said fork including a pair of tines capable of engaging the sheath when it is in its fully extended position and holding the sheath against the force of the compressed elastic member; and means mounted in the handle for collapsing the tines inward to release the sheath as the latching member is urged toward the blade.

Claim 15

Dependent Claim 50 words

A safety knife as in claim 12, wherein the latching member includes a button at the end remote from the knife blade, said button extending out of the handle so that a user can depress the button to urge the latching member toward the knife blade and release the sheath.

Claim 16

Dependent Claim 15 words

A safety knife as in claim 13, wherein the button is recessed in the handle.

Claim 17

Dependent Claim 71 words

A safety knife as in claim 12, wherein each tine on the fork terminates in an inclined surface, and wherein the means for collapsing the fork tines inward comprises a pair of inclined surfaces fixedly mounted in the handle, said inclined surfaces on the collapsing means mating with the inclined surfaces on the tines so that the tines are forced inward as the latching member is urged toward the collapsing means.

Claim 18

Dependent Claim 18 words

A safety knife as in claim 10, further comprising means for retaining the sheath in its retracted position.

Claim 19

Dependent Claim 16 words

A safety knife as in claim 16, wherein the retaining means comprises detents or latching member.

Claim 20

Dependent Claim 16 words

A safety knife as in claim 11, wherein the compressible elastic member is a coil spring.

Claim 21

Dependent Claim 52 words

A safety knife as in claim 18, wherein the coil spring is secured at one end relative to the tool and is free at its other end to engage the sheath as it is extended, said spring not extending a sufficient distance to engage the sheath when the sheath is fully retracted.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1988-06-17	1988-12-17	1989-06-18	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1992-06-17	1992-12-17	1993-06-18	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1996-06-17	1996-12-17	1997-06-18	$7700.00	Window Closed / Lapsed

Knife with retractable sheath

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