Abstract:
An eraser mover for use with a power eraser comprising mechanical means for sliding the eraser out of its holder by inserting prongs into the eraser and moving the prongs outwardly.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an improvement in power erasers. Conventionally, cylindrically shaped erasers are held with a collet having a plurality of longitudinal slots. The outer end of the collet is flared to retain a collar and the outer surface of the collet is tapered slightly thereby forming a frustum of a cone with the base of the cone toward the outer end of the collet. Movement of a collar, which surrounds the collet, toward the outer end of the collet causes an eraser placed within the collet to be squeezed and held in place for use. These conventional features are shown in FIG. 1. 
     The above described apparatus is satisfactory except for an annoying problem which occurs from time to time as the power eraser is used. Occasionally, the operator will allow the eraser to become worn to the point where it cannot be conveniently gripped with the fingers and additional eraser material extracted for continued use. At this time, the user is reduced to poking a pointed instrument, such as a pair of dividers into one of the slots and forcing more eraser material out of the collet. The invention described herein is a feeding mechanism which solves this problem by adding means for sliding the eraser outwardly by inserting prongs into the eraser and moving the prongs outwardly. 
     Several species of the means for sliding the eraser outwardly are shown in the accompaning drawings and will be discussed in detail in the following material. 
     The problem of feeding the eraser when it is worn down to the collet has been recognized before. The solutions shown in the following patents all address the problem, however, this invention is unique in that it provides a feeder mechanism of simple construction. Furthermore, this invention can be retrofitted onto the conventional power erasers in use today. See: 
     Motor Driven Adjustable Eraser, C. Sturzenegger, U.S. Pat. No. 2,487,903 
     Eraser Control Apparatus, N. L. Stokes, U.S. Pat. No. 3,427,677 
     Eraser Molding Chuck and Eraser, L. J. Misuraca, U.S. Pat. No. 3,224,417 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a side view of a first embodiment of the invention. 
     FIG. 2 is a cross-sectional view of the first embodiment of the invention showing the arrangement of elements when the eraser is disengaged. 
     FIG. 3 is also a cross-sectional view of the first embodiment of this invention showing the arrangement of elements when the eraser is engaged. 
     FIG. 4 shows a side view of a second embodiment of the invention. 
     FIG. 5 is a cross-sectional view of the second embodiment of the invention. 
     FIG. 6 is a side view of a third embodiment of the invention. 
     FIG. 7 is a cross-sectional view of the third embodiment of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to FIG. 1 through 3, power eraser 100 and collet 101 are of conventional design. Collar 103, which slidably interacts with the exterior of collet 101 in a conventional manner to provide means for squeezing eraser 104, also has a groven 105 in its inner surface. Although groove 105 may take many shapes, it must have at least one portion which is radially less distant from the center of collar 103 than the remainder of groove 105. For example, groove 105 may be hexagonal shape or may be square. In the preferred embodiment, best shown in FIG. 2, it comprises parallel flat grooves 106 and 107 which are joined on each end by annular grooves 108 and 109. Clip 110, which is located within groove 105 and which may be made of any material having springlike characteristics, has at least one leg which extends into a longitudinal slot 112 in collet 101. In the preferred embodiment, clip 110 is &#34;D&#34; shaped and has a pair of legs 111 which extend into longitudinal slots 112 in collet 101. The outer ends 113 of legs 111 are in juxtaposition with eraser 104, but do not touch it when the feeding mechanism is not in use. In this position, the inner ends 114 of legs 111 are in the annular portions of groove 105. If collar 103 is rotated 90 degrees, as shown in FIG. 3, the flat parallel portions of groove 105 contact inner ends 114 of legs 111 and urge outer ends 113 of legs 111 against eraser 104. After engagement of eraser 104 by legs 111, longitudinal movement of collar 103 produces a corresponding movement of eraser 104. Rotation of collar 103 another 90 degrees allows legs 111 to retract and disengage eraser 104. 
     Another form of this invention (shown in FIGS. 4 and 5) comprises a conventional power eraser including a conventional collar 401 for squeezing the eraser plus addition collar 402 which also surrounds collet 101. Collet 402 is generally elliptical in shape in its relaxed position and may be made of any suitable flexible material. Legs 404 which protrude from the inner surface of collar 402 are located along the long axis of the ellipse and extend into longitudinal slots 112 in collet 101. As shown in FIG. 5, legs 404 do not engage eraser 104 when collar 402 is in the relaxed state. However, application of force on the collar at points adjacent to legs 404 will compress collar 402 and cause legs 404 to engage eraser 104. Longitudinal movement of collar 402, after engagement of legs 404, will cause corresponding movement of eraser 104. 
     A third embodiment of this invention is shown in FIGS. 6 and 7. Collar 601 is shown in this specific embodiment as being generally &#34;U&#34; shaped, however, it could take any functionally equivalent form. Collar 601 has an internal groove 602 into which &#34;D&#34; shaped clip 110 is inserted. Groove 602 follows the contour of the inner surface of collar 601 except at the ends of the &#34;U&#34; where the depth of the void is increased sufficiently to allow the outer ends 113 of legs 111 of &#34;D&#34; shaped clip 110 to disengage eraser 104 when inner ends 114 of legs 111 are in the deep portions of the voids. This position is shown in FIG. 7. Movement of collar 601 transversely causes clip 110 to be compressed and legs 111 to engage eraser 104. Longitudinal movement of collar 601 after engagement of eraser 104 by legs 111 will cause corresponding movement of eraser 104. 
     Other variations of this invention including reversal of the spring action so that a cam action is used to retract the prongs is within the contemplation of this invention.