GB2202070A - Map reading apparatus - Google Patents

Abstract

A map reading apparatus comprised a portable light box 13 having an internal light source adapted to illuminate a diffuser plate 14 attached to the light box and a map on a transparent sheet of plastics material (not shown), the arrangement being such that in use the map is placed over the diffuser plate 14. A set of maps can be kept in the box. Clip 15 is for holding the one selected for viewing. Adjustable protractor/arm 16/17 is provided. <IMAGE>

Description

Map Reading Apparatus This invention relates to a map reading apparatus, particulariy for outdoor use in confined spaces, for example, on board a yacht, in a car, or in an astronmical observatory.

In this context, the expression "map" is defined to be interpreted as including a geographical or astronomical representation, such as a conventional map or navigational chart or an astronomical chart, and also includes charts or representations for other purposes.

When trying to read a map or chart outdoors and at night time it is generally necessary to use a battery operated light source such as a torch. This can be inconvenient especially, for example, on board a yacht, while trying to navigate, and can even be dangerous when a passenger reads a map inside a car with the courtesy light on. Also, in wet weather or at sea, the map or chart may be damaged by rain or spray.

Another inconvenience of reading maps in such confined spaces is that the map or chart very often has to be folded to reveal a small part of the map at any one time.

It is an object of the present invention to provide apparatus which ameliorates the afore-mentioned problems.

According to the present invention there is provided apparatus for reading a map (as hereinbefore defined) comprising a portable light box having an internal light source adapted to illuminate a diffuser plate attached to the light box and a map on a transparent sheet of plastics material, the arrangement being such that in use the map is placed over the diffuser plate.

The light box preferably comprises a container with walls which may be opaque, and having a detachable translucent diffuser plate to enclose the box. The light source is preferably provided inside the box with an external switch to make contact with a battery inside the box, through an electrical circuit.

Means for varying the current to the light source may be included in the electrical circuit to allow the intensity of the light source to be varied.

The walls of the container may be coated inside with a reflective coating. A diffuser plate may be provided on both sides of the light box.

The detachable diffuser plate is preferably hinged to the container and may be held in a closed position by a spring clip arrangement between the plate and container.

A set of transparent sheets, which in combination may provide a large map, may be used with the apparatus. The spare sheets in a set are preferably contained within the light box, when the sheets are not in use.

Navigational aids such as a compass rose and bearing arm may be movably attached to the light box to allow controlled movement of the compass rose over any part of a map placed on top of the light box. As an example, a support arm may be slidable supported in a slideway for movement along the box, and the compass rose may be slidably mounted on the support arm for movement therealong across the box. The bearing arm may then be mounted for rotation about the axis of the compass rose.

For navigational applications the map reading apparatus may be the size of a standard brief case and may include a handle for portability. Alternatively, the apparatus may be small enough to fit into a glove compartment in a vehicle.

It is highly desirable that the apparatus be water proof. The walls of the light box may be manufactured from plastics material or from wood, and the diffuser plate is preferably made from plastics material.

Specific embodiments of the apparatus of the present invention will now be described, by way of example, with reference to the accompanying drawing in which: Figure 1 shows in perspective, an embodiment of the apparatus; and Figure 2 shows in perspective a second embodiment of the apparatus.

Referring to Figure 1, a map reading apparatus 1 comprises a light box 2 having an internal 6 watt incandescent light bulb connected inside the box to a battery via a switch 3 and a light dimmer control 4. A diffuser plate 6 made from smoked polystyrene is attached to a lid 7. The lid 7 is hinged to the box at a proximal end of the lid 7 by hinge 8, and is held in a closed position by an internal clasp between the lid 7 and the box 2 at the distal end of the lid 7. A handle 9 is attached to a side wall on the box 2, for carrying the apparatus 1.

A plastic clip 11 is attached to the top of the diffuser plate 6, in order to clip a transparent map 12 onto the diffuser plate 6.

In this embodiment the map 12 is on a transparent sheet of cellulose acetate.

When used in a dark confined space the light is first switched on and the dimmer control 4 is adjusted according to the ambient light level and the transparency of the map 12. The map 12, which is stored within the box 2 as part of a set of maps, is taken out of the box 2 and placed on top of the diffuser plate 6 using clip 11. The diffuser plate 6 provides a back lit surface which enables the transparent map to be read.

Figure 2 shows a second embodiment of the apparatus in which navigational aids are used in conjunction with the apparatus. A light box 13, has a diffuser plate 14, a light switch with a dimmer control (not shown), and a stainless steel spring clip 15.

The light box 13 further has a compass rose 16 and a bearing arm 17 mounted on an arm 18 extending across most of the width of the box 13. The arm 18 is attached to a slider 19 which is free to slide in a dovetail groove 21 extending longitudinally of the base. The compass rose 16 is slidably mounted on the arm 18 with downwardly extending lugs 19, in fixed orientation thereto, and the bearing arm 17 is mounted so that it is free to rotate about the compass rose 16.

On the reverse side of the light box 13 is a second diffuser plate (not shown), for use with a log and passage plan also on cellulose acetate sheets. A pen with erasable but water -indelible ink is used on the map and log sheets to plot a course directly. This ink can be removed from the sheets afterwards with spirit. The map is reproduced in such a manner that it remains permanently on the cellulose acetate sheet.

The navigational aids are all made from transparent polystyrene.

In use a map on a cellulose acetate sheet is clipped to the light box 13 and the compass rose 16 is positioned at any desired point on the map.

A second slider may be attached at the other end of the arm 18 to slide within a second dovetail groove to give the arm more stability.

The apparatus according to this embodiment has additional advantages over a standard navigation aid, for example, a conventional map used with a standard navigation aid on a small boat is usually folded up in a plastic cover so that the map does not get wet. This embodiment has the advantages that the lightbox and map are water proof and the map can be changed relatively easily by clipping an overlapping adjacent map onto the light box, instead of having to take the map out of its plastic cover, to refold and replace it in the cover.

In yet a further embodiment the slider may be positioned in a groove running North - South instead of East - West, ie across instead of along the box.

Claims (15)

1. A map reading apparatus comprising a portable light box having an internal light source adapted to illuminate a diffuser plate attached to the light box and a map on a transparent sheet of plastics material, the arrangement being such that in use the map is placed over the diffuser plate.

2. Apparatus according to claim 1, in which the light box comprises an opaque walled container having a detachable plate to enclose the box..

3. Apparatus according to claim 1, in which the light box source is provided inside the box with an external switch to make contact with a battery inside the box, through an electrical circuit.

4. Apparatus according to claim 3, in which means for varying the current to the light source are included in the electrical circuit to allow the intensity of the light source to be varied.

5. Apparatus according to any of the preceding claims, in which the opaque walls are coated inside with a reflective coating.

6. Apparatus according to any of the preceding claims, in which a diffuser plate is provided on both sides of the light box.

7. Apparatus according to any of the preceding claims, in which a set of transparent sheets, which in combination provide a large map, are used with the apparatus.

8. Apparatus according to claim 7, in which spare sheets in a set are preferably contained within the light box, when the sheets are not in use.

9. Apparatus according to any of the preceding claims, in which navigational aids such as a compass rose and bearing arm are attached to the light box to allow movement of the compass rose over any part of a map placed on top of the light box.

10. Apparatus according to claim 9, in which the map reading apparatus is the size of a standard brief case and includes a handle or portability.

11. Apparatus according to claim 9, in which the apparatus is small enough to fit into a glove compartment in a vehicle.

12. Apparatus according to any of the preceding claims, in which the apparatus is water-proof.

13. Apparatus according to any of the preceding claims, in which the walls of the light box and diffuser plate are made from plastics material.

14. Apparatus according to any of claims 1 to 12, in which the walls of the light box are made from wood.

15. Apparatus substantially as hereinbefore described with reference to Fig.l and Fig.2 of the accompanying drawing.