US1934843A - Blackboard eraser - Google Patents

Description

' BLACKBOARD ERASER Filed April 8, 1951 Patented Nov. 14, 1933 BLAoKBoAaD EnAsER j Charles E.'.Daniel, Sandusky, Ohio, assignor to The American; Crayon Company, Sandusky, Ollio, a. corporation of Ohio 'Application Abril 8,1931. serial No. 528,518

1 claim. (c1. 15-228) This invention relates to ank instrument for cleaning blackboards made of wood, slate, suitable composition or other material having aV smooth writing surface, and the invention has for .its object and purpose to provide an improved eraser by means of which to rub vout writings, drawings, characters, etc., ,made with chalk, crayons, or the 1ike,'and for the purpose of removing the grayish chalk from the surface of the board therebyputting the blackboard back into its original dense, black-colored condition.

. With the use of the customary cloth or lfelt erasers, smudges ofthe chalk or crayon are usually left on the board after the erasing operation, and itis only withgreat diiculty that the board is really cleaned and put into its original or initial dense, black-colored condition.. Smudging ofthe chalk upon the blackboard produces in general a grayish eiect so that when the chalk is again applied, the whiteness or other color of thechalk Vis not as pronounced Yagainst such a grayish background as it is in a case where the board has been properly cleaned.

To bring about the desired cleaning, ythe instrument ofthe present invention involves the provision of a mass or package of paper sheets bound together ior convenient handling and so as Vto provide a rubbing surface composed of a multiplicity of free scraping edges having a springy action. In the act of cleaning the board, the free edges impinge upon the particles of the chalk smudges and by reasonof `the resilient nature of the impingement the chalk particles are separated from the blackboard itself. The removed particles may in some instances be thrown completely away from the board, While in other instances they are caught between the respective sheets of paper and held therebetween o until removed by cleaning the eraser itself.

A further object of the invention is to provide an reraser of simple and inexpensive construction, which will be convenient to handle and which is capable of removing the chalk smudges and cleaning the board with a minimum of labor and with dispatch.

The nature of the invention, its general principles and objects above referred to, as Well as other objects and advantages, and the Vmanner in which the new and novel features oiconstruction and operation may be embodied in practical `form and means, will be hereinafter more fully described with reference to the example illustrated in the accompanying drawing, in whicht- Figure 1 represents a perspective View of an package; and in the present instance a cloth or Vfabric 12 is. shown for such purpose, the same eraser` made Yin accordance with the invention; n Fig 2 is anend.view of the eraser; Y

Fig. 3 is an endview on alarger scale, illustrating the packagel of sheetsflared or bent under pressure exerted on the eraser during the act of cleaning the board; v Fig. 4 is a diagramma'tical represention, illustrating kthe removal of a chalk particle by the springy free edge portions-of the sheets;` and Fig. 5 is a cross sectional view through the eraser, taken on the line 5,-5 oi Fig. 1

Referring to the drawing, the improved blackboard .eraser consists of a package or mass of 'paper sheets or leaves l, arrangedl in face flatwise contact and standing upon one longitudinal edge, the package of sheetsbeing bound together at or near the top orgbackl edge thereof Yby a threadcr-line of stitching l1. Backing means may also -beprovi`ded for thetop portionor^ the extending across the top of the package and for a distance down over the faces of the outermost leaves at the oppositesides of the package.

Over the top of thepackage of papers, which is thusheldytogether by the stitching 11 and fabric 12, a box-like container 13 is placed so as to provideV a convenient holder for the eraser. This container may be made of cardboard, veneer-like board or any suitable material. Preferably the interior dimensions of the boxlike holder 13 are such as to be very slightly smaller than the exterior dimensions lof the package as bound and held together by the thread 11 and the fabric 12, so that when the .90 holder 13 is placed upon the top of the bundle of papers, it will'be maintained thereon by fric-V tional engagement. Mucilage cement or the like, may, of course, be employed Vto make a permanent connection; but preferably the package and holder aresepa'rable so that the holder may be used for a newpackage whenever it is desired tofdiscard the old one when the latter becomes too worn for efficient use.

The leaves or pieces of paper, which' make up the package, are rectangular in form, with the long dimensions of the leaves extending in parallel relation.V The leaves being flexible and being bound in tight compacted condition only. at the top, the lower portions thereof are free for flexing and bending movements and the opposite corner portions 15 of the package iiare outwardly or in a direction away from, the center of the mass. v

When an eraser is used upon a blackboard as 16 (Fig. 3), application of pressure upon the holder 13 will bring about a distortion or bending of the leaves which may thereupon assume the condition depicted in Fig. 3 when carrying out an erasing or cleaning operation. The particular distortion and bending of the leaves in any instance, depends naturally upon the manner in which pressure is applied and the locality where it is applied on the holder 13. With the pressure applied in the direction indicated by the arrow 17 (Fig. 3), the forward leaves are spaced from the blackboard as indicated by the gap 18and certain of the leaves are in the act of reflexing as indicated at 19, while the group or main portion of the leaves as indicated at 20, which receives the application of pressure, are bent upon the board and trailed thereon in a rearward direction. If the eraser is moved over the board in this manner, the particles of chalk adhering to the blackboard 16 will be encountered by the sharp edges of thevgroup 19; and by reason of the resiliency of the members of this group, due to their engagement with the board and to their consequent forward rebounding to a position as shown by the dotted outline at 19', a chalk particle 22 will be impinged and propelled away from the blackboard 16. This chalk particle may be thrown away from the blackboard or it may be projected among" the respective leaves of the eraser.

In the use of the eraser of the invention, very little pressure and effort will bring about an effacement of the `chalk and chalk smudges, leaving the board clean and bright.

The leaves or pieces of paper are of a size suitable for producing a package or bundle convenient to handle. Preferably the leaves are about live inches in length and one and one-quarter inchesin width. The free edges of the leaves may be uniformly smoothed oiT by holding them against a polishing or grinding machine of suitable kind. The number of leaves employed in a bundle are suiiicient to give the bundle from front to rear, when reasonably compressed, a transverse dimenf sion of about two inches.

The resilient character of the papers when under pressure, and the smoothness ofthe free ends thereof, result in the provision of a very efcient rubbing and cleaning instrument.

The terms and expressions employed are used as terms of description and not of limitation, and I have no intention, in the use of such terms and expressions, of excluding any mechanical equivalents of the features shown and described, or portions thereof, but recognize that various structural features are possible within the scope of the invention claimed.

I claim:-

A blackboard eraser comprising a mass of thin wafer-like Yflexible paper members of elongated rectangular form, having inherent and resilient rebounding characteristics each paper member contacting with the Yadjacent paper member and being normaly in full face contact therewith, all of said members in respect of their elongated length extending lengthwise the eraser and in respect of their breadth being vertically disposed, means at the tops of the members securing the top marginal portions thereof in a rm unitary assembly and uniformly compressing the same together for the entire distance of their length'into a relatively solid top and leaving the members otherwise wholly free for their full length for flexing laterally from their normal face contact, with the individual bottoms of said members affording sharp erasing edges and these edges in combination constituting an erasing surface which is substantially rounded from one longitudinal side of the eraser to the other, adapting the members, when the sharp edges are moved in contact with the blackboard surface, to freely and resiliently 110 iiex individually from normal contact and form along the length of the eraser open gaps in which forcibly Vto react and rebound for impinging and removing chalk particles by the sharp edges, and a cover engaging the relatively solid top, entirely 115 concealing the securing means and adapted to afford a hand grip for wielding the eraser so as to effect the described resilient flexing and reaction of said members.

CHARLES n. DANIEL.` 12o

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