WO1993015919A1

WO1993015919A1 - Eraser for white- or blackboards

Info

Publication number: WO1993015919A1
Application number: PCT/DK1993/000052
Authority: WO
Inventors: Jørgen THUESEN
Original assignee: Thuesen Joergen
Priority date: 1992-02-13
Filing date: 1993-02-12
Publication date: 1993-08-19
Also published as: AU3493593A; DK17692D0

Abstract

The eraser for white- or blackboards comprises an inner and an outer cupular member (2, 1), each of which has a bottom with two substantially straight, parallel sides from each of which a side wall (10, 3) extends, the inner member (2) being designed to be received and retained in the outer member (1) in a closed position so that the side walls (3, 10) are pairwise juxtaposed in such a manner that the two members form between them a substantially closed hollow space. The eraser further includes means (5, 6) for retaining the two members (1, 2) against opening of the hollow space in a half-open, mutual position in which there is a distance between the respective pairwise adjacent side walls (3, 10).

Description

ERASER FOR WHITE- OR BLACKBOARDS.

The invention relates to an eraser for white- or blackboards comprising an inner and an outer cupular member, each of which has a bottom with two subs¬ tantially straight, parallel sides from each of which a

5 side wall extends, the inner member being designed to be received and retained in the outer member in a closed position so that the side walls of the two mem¬ bers are pairwise juxtaposed in such a manner that a side wall of one member at least along an edge is ad-

10 jacent to the corresponding side wall of the second member, the two members forming between them a substan¬ tially closed hollow space.

Such an eraser is disclosed in US patent No. 2 648 863. When the two members are in their closed

15 position, a web-shaped eraser material may be fastened distended across the bottom of the inner member, the ends of the eraser material being kept squeezed between the adjacent side walls. In this prior art eraser supplementary internal side walls in the outer member

20 ensure that the eraser material is not merely pushed away upen assembling the two members but is squeezed effectively firmly. The hollow space between the two members may be used as a magazine for a roll of the web-shaped material, when the web-shaped material

25 distended across the bottom of the inner member is to be replaced after use, the two members must be dis¬ assembled, the used eraser material be removed and a new piece be laid across the bottom of the inner member, be folded around the side walls of the member, ft^*.

30 following which the two members are reassembled.

The object of the present invention is to pro¬ vide an eraser for white- or blackboards of the above mentioned type in which the eraser material distended across the bottom of the inner member may be renewed in a simple manner without having to completely separate the two members, thereby involving the risk that a magazine roll of eraser material might fall out of the hollow space of the eraser. This is achieved according to the invention by means of an eraser for white- or blackboards that is characteristic in comprising means for retaining the two members against opening of the hollow space in a half-open mutual position in which there is a distance between the respective pairwise adjacent side walls. This provides for obtaining an intermediate position between closed and open eraser, in which intermediate position the eraser material is not retained but may be removed and renewed, the eraser being concurrently not so open that a roll of eraser material in the hollow space between the two members is able to fall out.

In a preferred embodiment the bottom of the inner member has a slit at one of the parallel sides. This makes it possible to pass the web of eraser mater- ial from a magazine roll in the hollow space between the members beyond the side wall of the inner member remote in relation to the slit, across the bottom of said member, up through the slit and around the near side wall of the inner member as compared to the slit. The end of the web-shaped material will thus stretch between two of the pairwise adjacent side walls and upon pull at this end, the two members of the eraser being in their half-open mutual position, a new eraser material is pulled out from the magazine roll across the bottom of the inner member, thereby renewing the eraser material.

In a perferred embodiment the inner member is retained in the closed position in the outer member by wedging the side walls of the inner member in between the side walls of the outer member. The side walls thus serve the double purpose of retaining the web-shaped material as well as retaining the two members in their closed mutual position.

In a preferred embodiment each of the two mem¬ bers includes end walls which connect the respective side walls, said end walls comprising each per se pro¬ jections adapted to engage projections on the adjacent end wall of the other member when the members are in their half-open mutual position.

In a preferred embodiment one side wall of at least the outer member has a sharp and/or serrated tear edge for tearing-off a used eraser material from the material web.

In a further embodiment a magnet is embedded in the external bottom face of the inner member. The eraser may thus be fastened on a white- or blackboard, the basic material of which is ferromagnetic or on a ferromagnetic object in the vicinity of the board.

In a further embodiment a thin, flexible layer covers the external bottom face of the inner member. In use, such a layer contributes to keep the eraser mater¬ ial in contact with the white- or blackboard across a substantial portion of the bottom face of the inner member.

Eventually, in one embodiment the two members are separate whereas in a second embodiment they are hinged to each other and have a hinge axis extending along and close to the bottom of the inner member and along and close to the lateral walls of one pair.

The invention will now be described in detail by means of an example with reference to the drawings, in which

Fig. 1 is a vertical section along the line I-I in Fig. 2 through an eraser for a white- or blackboard according to the invention, illustrated in a half-open position,

Fig. 2 is a section along the line II-II in Fig. 1, and Fig. 3 is a sectional view corresponding to Fig. 2, but showing the eraser in a closed position.

In the illustrated example the eraser for a white- or blackboard consists of a box of rectangular shape with an upper part 1 which as a lid fits over a lower part 2. The upper part has two side walls 3 and two end walls 4. The end walls 4 are provided with projections 5 designed to engage corresponding projections 6 on end walls 7 of the lower part 2. The side walls 3 of the upper part diverge towards the opening of the upper part 1 and is completed by a sharpened and serrated tear edge 8.

The lower part 2 comprises a bottom 9, end walls 7 and side walls 10 that are relatively low in comparison with the end walls 7. A slit 11 exten¬ ding substantially throughout the length of the eraser is provided at the bottom 9 close to one of the side walls 10. In the illustrated example the bottom 9 has a depression 12 in which a magnet is positioned. The upper part 1 and the lower part 2 are dimensioned in such a manner in relation to each other that the side walls 10 of the lower part 2 may be wedged in between the divergent side walls 3 of the upper part 1 in a closed position of the white-or blackboard illustrated in Fig. 3. In the illustrated embodiment the side walls 3 include individually an internal bulge 19 operating as stop for the side walls 10 when the upper and lower parts are pushed together to the closed position. The upper part 1 and the lower part 2 may from the position illustrated in Fig. 3 be separated from one another to the position illustrated in Figs 1 and 2, in which the projections 5 and 6 on the upper part and on the lower part, respectively, engage each other and prevent complete disassembling of the eraser. Due to the flexibility of the material of the eraser it is, however, possible to curve the end walls 4 and 7, thereby totally separ¬ ating the components of the eraser 2.

Figs 2 and 3 illustrate a magazine roll 14 of a web-shaped material 15 embedded in the hollow space provided between the upper part 1 and the lower part 2 when assembled. The web-shaped material which is a disposable eraser material is, as appears from Figs 2 and 3, passed from the magazine roll 14 over one side wall 10 of the lower part 2, across the bottom 9 thereof, up through slit 11 and further over the other side wall 10 of the lower part 2. When the upper part and the lower part are in the half-open, mutual position illustrated in Fig. 2, there is nothing to squeeze the web-shaped material 15 so as to pre- vent it from being pulled forward as illustrated by the arrow 16. On the contrary, when the upper part and the lower part are pushed together to the closed posi¬ tion illustrated in Fig. 3, the web-shaped material 15 is firmly squeezed between the side walls 3 of the upper part 1 and the side walls 10 of the lower part 2, thereby fastening the part of the web-shaped material 15 extending across the bottom 9. The web- shaped material 15 is likewise firmly squeezed bet¬ ween the upper edges of the side walls 10 and the bulges 19 where the pressure and thus the squeezing force increase when the eraser in use is pressed against a white- or blackboard. Upon closing this por¬ tion of the material 15 is further tightened up at the side of the eraser where the web due to friction against the adjacent side wall 3 is passed up over the side wall and out.

The closed position illustrated in Fig. 3 is the use position of the eraser and in this position the eraser may thus be used for wiping a white- or black- board clean. When the web-shaped material 15 distend¬ ed across the bottom is replaced after use, the upper part and the lower part are separated, to the position illustrated in Figs 1 and 2. The web-shaped material 15 is then released and its free end 17 is exposed and may- thus be caught and pulled forward until the eraser material has been replaced. Then the upper part and the lower part are reassembled, thereby firmly squeezing the material 15 between the side walls 3 and 10, following which the used eraser material pulled out may be torn off along the closest tear edge 8. When the magazine roll 14 is empty, the upper part and the lower part are completely separated, following which a new roll may be placed in the white- and black¬ board eraser.

Many different materials may be used as eraser material, merely on the condition that they have a suf- ficent strength in their longitudinal direction to withstand the pull while being advance . A very suit¬ able material is disposable mop cloth with a smooth side and a piled side. The smooth side is used for wiping whereas the piled side has an elastic effect contributing when in use to keep the eraser material in contact with the white- or blackboard. An example of such a disposable mop cloth is the product DERMALIN marketed by NOVODAN KEMI A/S, An alternative of a material with a piled sur¬ face is a thin flexible layer to be applied to the external surface of the bottom 9.

The white- and blackboard eraser according to the present invention is in particular appropriate for wiping clean so-called whiteboards comprising a layer of paint or enamel on a steel plate. In such a case the eraser may, when not in use, fasten to the board by virtue of the magnet 13 and is thus always within easy reach. Even though the eraser for white- or blackboards according to the present invention is described above with a separate upper part and a separate lower part, these parts may as well be hinged to each other, for instance by a hinge axis, as illustrated by 18 in Fig. 3, i.e. approximately coinciding with the corner between one side wall 10 and the bottom 9. By such an embodiment the above described function of the eraser would also be achieved, i.e. it would be open- able in two stages, firstly to a half-open position in which the web-shaped material 15 may be pulled for- ward to be renewed and secondly to a completely open position in which a new magazine roll 14 may be embedded.

Claims

P A T E N T C L A I M S

1. An eraser for white- or blackboards com¬ prising an inner and an outer cupular member (2, 1), each of which has a bottom with two substantially straight, parallel sides from each of which a side wall (10, 3) extends, the inner member (2) being designed to be received and retained in the outer member (1) in a closed position so that the side walls (3, 10) are pairwise juxtaposed in such a manner that a side wall (10) of one member (2) at least along an edge is ad- jacent to the corresponding side wall (3) of the second member (1) , the two members forming between them a substantially closed hollow space, characterized by comprising means (5, 6) for retaining the two members (1, 2) against opening of the hollow space in a half- open mutual position in which there is a distance bet¬ ween the respective pairwise adjacent side walls (3, 10) .

2. An eraser for white- or blackboards according to claim 1, characterized in that the bottom (9) of the inner member (2) has a slit (11) at one of the parallel sides (10) .

3. An eraser for white- or blackboards according to claim 1 or 2, characterized in that the inner member (2) is retained in the closed position in the outer member (1) by wedging the side walls (10) of the inner member (2) in between the side walls (3) of the outer member.

4. An eraser for white- or blackboards according to claims 1 to 3, characterized in that each of the two members (1, 2) includes end walls (4, 7) which connect the respective side walls (3, 10), said end walls (4, 7) comprising each per se projections (5, 6) adapted to engage projections (6, 5) on the adjacent end wall (7, 4) of the other member (2, 1) when the members are in their half-open position.

5. An eraser for white- or blackboards according to claims 1 to 4, characterized in that at least one side wall (3) of the outer member (1) has a sharp and/or serrated tearing edge (8).

6. An eraser for white- or blackboards according to claims 1 to 5, characterized in that a magnet (13) is embedded in the external bottom face (9) of the inner member (2) .

7. An eraser for white- or blackboards according to claims l to 6, characterized in that a thin flexible layer covers the external bottom face (9) of the inner member.

8. An eraser for white- or blackboards according to claims 1 to 7, characterized in that the two members (1, 2) are separate.

9. An eraser for white- or blackboards according to claims 1 to 7, characterized in that the two members (1, 2) are hinged to each other and have a hinge axis (18) extending along and close to the bottom (9) of the inner member (2) and along and close to one pair of side walls (3, 10) .