This invention relates to apparatus for use as an educational aid or plaything, to enable a child to reproduce an image (a picture, lettering or the like) .

A well known tool in the practice of graphics and photography is a light box, which is predominantly used to assist in visualizing transparencies and reprographic work via a tracing. Essentially such a light box consists of a boxed container with a translucent light diffuser on the top. The basic components of a light box are a filament or fluorescent lamp as light source, and a switched, and protected, electrical power source (which for industrial or professional use is normally taken direct from the mains) .

It is also known to provide paper, during its manufacture, with permanent indicia or marking (sometimes called a "marque"), such as to be substantially invisible under reflected light, but visible from one side when illuminated by a light source on the other side. Watermarking is one process for making marqued paper.

In the educational field, it is known to provide aids for young children and others, such as the mentally handicapped, to assist them to draw or paint, or to write lettering, by following lines or colouring in areas which are printed on the paper so as to be clearly visible under reflected light. This has the disadvantage that the original printing used as a guide for the user usually remains visible even after the work has been completed.

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An object of this invention is to provide an apparatus for assisting young children and others with limited or no drawing or writing ability, or imagination, to produce images on paper (or other sheet material) without the drawbacks of known aids.

According to the invention, an apparatus for use as an educational aid or plaything is characterised by (a) support means including a sheet holder having retaining means, for removably locating at least one sheet of translucent material bearing indicia such as to be substantially invisible under reflected light but visible from one side when illuminated on the other side, and (b) a light source disposed behind the retaining means so that a said sheet or sheets, when located by the latter, are in overlying relationship with the light source.

The support means may include a base box, the sheet holder comprising a base box cover carrying the retaining means. The retaining means then preferably comprises a groove in a top housing of the cover.

The sheet holder may comprise a translucent plate having an outer surface to support the said sheet or sheets, the light source being disposed behind the said outer surface. The translucent plate is preferably a diffuser.

The support means may be in the form of a light box including mounting means for mounting the light source in the support means. However, the light source may take any convenient form, as may the support means.

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One embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings, in which.--

Figure 1 is general view of a support means, in the form of a light-box, in an apparatus according to the invention;

Figure 2 is a perspective view of the same light-box with the cover removed;

Figure 3 is an exploded view showing various components of the light-box of Figure 2;

Figure 4, again an exploded view, shows the remainder of the components of the box in Figure 2;

Figure 5 shows the cover, illustrating its sheet holder;

Figure 6 is a scrap sectional view seen generally in the direction indicated by the arrows X-X in Figure 5;

Figure 7 is a simplified electrical circuit diagram of the light-box; and

Figure 8 shows a typical marking on a sheet of translucent material for use with such a light-box.

The apparatus comprises a support means 1 for marqued sheets, which in this example is in the form of the light-box shown in Figure 1, comprising a base part 10, Figures 2 to , and a cover 12 which fits removably over the base box, i.e. the body 14 of the base part 10. The cover 12 comprises a top housing 16 having a top panel 17 in which a rectangular opening is formed with a continuous groove 19, Figure 6, so that a

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translucent plate 18 can be supported by the top housing 16, to be slid in and out of the latter as required, as shown in Figure 5. The plate 18 may be made removable or otherwise.

The plate 18 is a diffuser, which may be of glass or suitable plastics material.

A base plate 28, Figure 3, is carried in the base box 14 and itself carries a set of reflector supports 29, on which reflector strips 30, which may for example be in the form of mirrors, are mounted in V-shaped formation as seen in Figures 2 and 3. In the bottom of each V formed by the reflectors, a mount 31 is arranged for carrying locating clips 32 for a respective fluorescent tube 33, the arrangement being such that the tubes 33 lie behind the translucent diffuser 18.

Associated with the fluorescent tubes are a heat sink 24 and starter gear 25, mounted with a switch 22 and low-voltage DC supply socket 23 on one wall of the base box 14. Also housed in the latter is a set of battery holders 26 for holding a set of dry batteries 27. The electrical components are connected as generally indicated in Figure 7.

Since the apparatus is for use by children among others, the electrical supply is preferably (and where safety regulations so require, it must be) at low voltage, though a mains input, not shown, may be provided where permitted, being connected through a transformer in the base 10. In the present example, the tubes 33 are of a low-voltage type and may be powered either by the batteries 27 or from the mains,

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through a suitable remote transformer/rectifier unit and the low voltage input socket 23.

The top housing 16 and the base box 14 may be made of any suitable material, being preferably injection moulded in a suitable strong plastics material such as ABS or acrylic.

As shown in Figure 6, the width of the groove 19 is such that a sheet of translucent material 40 can be inserted in the grooves, lying on the diffuser 18. This sheet is then retained in the grooves but can be slid out from the back. It. may also be removed from any other direction simply by bending the sheet. The sheet 40 is of paper or other suitable translucent material of the kind that bears indicia such as to be substantially invisible under reflected light, but visible from one side when illuminated on the other side, i.e. in this case when illuminated by the tubes 33. The indicia may be in the form of a watermark, or the paper sheets may be of the kind sold under the Trade Mark CUSTOMARQUE by G. F. Smith & Son (London) Ltd. of Lockwood Street, Hull HU2 0HL.

The indicia or marque on the sheet may take any required form whatsoever. Typical examples are simple drawings, letters and numbers (for example

"cop ^r rplate" script letters for use in teaching children elementary handwriting) and so on. Figure 8 shows a typical sheet for use in teaching small children to learn letters and their association with words.

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In use, a sheet 40 is laid on the sheet 18 and inserted with it into the top housing 16. The switch 22 is closed so that the tubes 33 illuminate the sheet 40 from behind, whereupon the marques on the latter become visible. The reflectors concentrate the emission of light through the diffuser 18. The child can then, using a suitable writing or other marking implement, trace or otherwise reproduce the marque on the front of the sheet 40, for example by tracing lettering to obtain writing practice or a picture to obtain drawing practice. The child can also use paints or other colouring media to colour in the spaces. After removal from the light-box, only the markings made by the child are then visible.

The means for retaining the sheet 40 can take any suitable form, the groove 19 being merely a preferred example. A spring-loaded frame or bar may for example be provided, which can be pulled back to release the sheet in known manner. More than one sheet 40 may be placed on the apparatus simultaneously, overlaid on each other, so that either marques on two or more sheets will be visible together when lit from behind, or the top sheet may be a blank sheet thus avoiding spoiling the marqued sheet, which is then re-usable.

The light source may take any suitable form: in one example it may be incorporated in the plate 18, for example by making the latter with a suitable fluorescent layer with connections to the low-voltage power supply. The plate 18 may then be opaque behind the fluorescent layer, and the support means of the apparatus can be simplified and made thinner.

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