US4543680A — Blackboard eraser handle

Claim 1

Independent Claim 149 words

A detachable handle for an eraser having an absorbing material attached to a flat rigid rectangular backing plate having edgewalls of predetermined thickness and used to erase chalk or grease pen marks from black boards, white boards and the like, comprising a unitary, resiliently rigid structure having a predetermined transverse width and a predetermined longitudinal length related to the width and length of said backing plate, said structure including a "C" shaped strap in the longitudinal direction and having two "C" shaped notches along opposite edges thereof perpendicular to said longitudinal direction and disposed to face one another for overlying clamping engagement with opposite edgewalls of said rigid backing plate and wherein the untensioned longitudinal dimension between the interior endwalls of said notches is slightly less than the dimension of said backing plate between said engaged edgewalls thereof, said handle structure being under tension when engaged on said eraser.

Claim 2

Dependent Claim 149 words

A detachable handle for an eraser having an absorbing material attached to a flat rigid rectangular backing plate having edgewalls of predetermined thickness and used to erase chalk or grease pen marks from black boards, white boards and the like, comprising a unitary, resiliently rigid structure having a predetermined transverse width and a predetermined longitudinal length related to the width and length of said backing plate, said structure including a "C" shaped strap in the longitudinal direction and having two "C" shaped notches along opposite edges thereof perpendicular to said longitudinal direction and disposed to face one another for overlying clamping engagement with opposite edgewalls of said rigid backing plate and wherein the untensioned longitudinal dimension between the interior endwalls of said notches is slightly less than the dimension of said backing plate between said engaged edgewalls thereof, said handle structure being under tension when engaged on said eraser.

Claim 3

Dependent Claim 27 words

A detachable handle for an eraser as described in claim 1 wherein the "C" shaped strap forms a symmetrical arch over said backing plate when engaged thereto.

Claim 4

Dependent Claim 38 words

A detachable handle for an eraser as described in claim 1 wherein the central section of said "C" shaped strap forms an angle with said backing plate to provide a comfortable grasp angle during use of said eraser.

Claim 5

Dependent Claim 74 words

A detachable handle for an eraser as described in claim 1 wherein each said "C" shaped notch comprises a vertical back section, an upper section adjoining and substantially perpendicular to said back section, and a lower section ajoining said back section wherein the distance between said upper section and said lower section generally corresponds to the thickness of the edgewall of said backing plate about which said "C" shaped notched portion may be clamped.

Claim 6

Dependent Claim 58 words

The detachable handle for an eraser as described in claim 4 wherein said lower section tapers away from said back section to form a relatively sharp lower edge and wherein the interior surface of said lower section is slightly undercut so that said lower edge engages the underside of said backing plate along the length of said notch.

Claim 7

Dependent Claim 38 words

The detachable handle for an eraser as described in claim 1 wherein said "C" shaped strap includes storage compartment means for providing a storage compartment for at least one marking implement for use in conjunction with said eraser.

Claim 8

Dependent Claim 33 words

The detachable handle for an eraser as described in claim 1 and formed of a material selected from the group including metal, rigidly resilient plastic such as PVC, ABS, and fiberglass reinforced plastic.

Claim 9

Dependent Claim 118 words

A detachable handle for an eraser having an absorbing material attached to a flat, rigid generally rectangular backing plate and used to erase chalk or grease pen marks from blackboards, white boards and the like comprising a unitary structure including a rigid base plate, a "C" shaped handle grip attached to the upper side of said base plate and clamping means for clamping the lower side of said base plate to said eraser backing plate, said clamping means comprising "J" shaped sides facing each other and depending from opposite edges of said base plate, said facing sides including interior opposed notches sized and spaced to receive opposite edgewalls of said base plate in overlying frictional clamping engagement therewith.

Claim 10

Dependent Claim 118 words

A detachable handle for an eraser having an absorbing material attached to a flat, rigid generally rectangular backing plate and used to erase chalk or grease pen marks from blackboards, white boards and the like comprising a unitary structure including a rigid base plate, a "C" shaped handle grip attached to the upper side of said base plate and clamping means for clamping the lower side of said base plate to said eraser backing plate, said clamping means comprising "J" shaped sides facing each other and depending from opposite edges of said base plate, said facing sides including interior opposed notches sized and spaced to receive opposite edgewalls of said base plate in overlying frictional clamping engagement therewith.

Claim 11

Dependent Claim 61 words

A detachable handle for an eraser as recited in claim 8 wherein the opposed interior faces of said notches formed in said "J" shaped sides facing each other are spaced apart slightly less than the thickness of said eraser backing plate at the edgewalls thereof, said notches thereby providing said frictional clamping engagement of said handle with said eraser backing plate.

Claim 12

Dependent Claim 41 words

A detachable handle for an eraser as recited in claim 8 wherein the handle grip further comprises a "C" shaped rigid strap with one or both ends connected to said base plate and its central section elevated above said base plate.

Claim 13

Dependent Claim 23 words

A detachable handle for an eraser as recited in claim 10 wherein said rigid strap forms a symmetrical arch over said base plate.

Claim 14

Dependent Claim 39 words

A detachable handle for chalkboard erasers as recited in claim 10 wherein one end of said central section is elevated higher than the other end so that said central section forms an ergonometrically comfortable angle with said base plate.

Claim 15

Dependent Claim 37 words

The detachable handle for an eraser as described in claim 8 wherein said handle grip includes storage compartment means for providing a storage compartment for at least one marking implement for use in conjunction with said eraser.

Claim 16

Dependent Claim 33 words

The detachable handle for an eraser as described in claim 8 and formed of a material selected from the group including metal, rigidly resilient plastic such as PVC, ABS and fiberglass reinforced plastic.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1988-09-30	1989-04-01	1989-10-01	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1992-09-30	1993-04-01	1993-10-01	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1996-09-30	1997-04-01	1997-10-01	$7700.00	Window Closed / Lapsed

Blackboard eraser handle

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