DEVICE FOR DISPLAYING CARTOGRAPHIC INFORMATION

Abstract: A device for displaying cartographic information comprises a transparent display panel (5) behind which a map (6) can be placed and by means of which computed coordinates can be imaged graphically (9, 10) in the form of, for example a dot, a spot (cursor) or a point of intersection (10) of intersecting (hair) lines (9). By starting from existing, conventional maps (6) for presentation of the map data, a comparatively simple and inexpensive display panel (5) is sufficient to display a fully graphic image of computed coordinate data.

Description: Device for displaying cartographic information. The invention relates to a device for displaying cartographic information, comprising a processing unit for computing and generating specific coordinates and a display unit to which the coordinates are applied in the form of an electric signal and by means of which the coordinates are imaged. A device of this type is often used as a navigation means, for example in a global positioning system which is capable of determining the actual position of the device and to display its coordinates, or in the form of a route planner with which a trajectory from start to finish is determined and is displayed in the form of a series of coordinates. For displaying the coordinates, some existing devices use an alpha- numerical display unit on which the relevant coordinates are displayed in the form of numbers. Such a display unit has the advantage that it may be comparatively simple and thus relatively inexpensive, but it has the drawback that the average user does not gain much insight from the information provided. It will often be necessary for the user to consult also a conventional map so as to gain a topographic insight into the position of the relevant coordinates. Other devices of the type described in the opening paragraph use a graphic display unit for displaying a graphic image of the computed coordinates as being embedded in a display of the associated map. With such a device the user acquires the desired information at a glance, but such a device requires additional storage means for storing the map data and a comparatively complicated graphic image display device, both of which have a considerable cost-increasing effect. It is, inter alia an object of the invention to provide a device of the type described in the opening paragraph which combines the afore-mentioned advantages of the systems described whilst avoiding the afore-mentioned drawbacks. According to the invention, a device of the type described in the opening paragraph is therefore characterized in that the display unit comprises a transparent electro- optical display panel, in that the display panel is capable of displaying a graphic two- dimensional image of the coordinates, and in that the device comprises identification means for determining the identity of a map upon the latter's being juxtaposed to said device. In the device according to the invention an existing map in the form of a map street, a page from an atlas, or the like is used for representing the map data. The map may be printed according to conventional technology an juxtaposed to the device, and n particular placed behind the display panel. Therefore, the device according to the invention need not comprise means for electrically storing map data or a complicated image display unit for displaying a complete map. The map when placed behind the display panel in the device according to the invention, remains visible through the transparent display panel. The display panel displays the computed coordinates as a graphic image in the form of, for example a dot, a spot (cursor) or a point of intersection of two crosshairs. A comparatively simple and inexpensive display unit is sufficient for this purpose. Thus, the user acquires direct insight into the desired cartographic information. To ensure that the indicated position on the map corresponds to the computed coordinates, the identity of the map is determined in advance by identification means, for example in terms of a set of absolute coordinates of the relevant map. The image display panel may be, for example a liquid crystal image display device comprising two transparent substrate layers which have each transparent drive electrodes and enclose a layer of liquid crystalline material. Under the influence of an electric field, such a layer of liquid crystalline material is capable of changing the direction of polarization of light which has been coupled in. To visualize such a modified direction of polarization, at least one of the two substrates is provided with a polarization filter, so that differences in the direction of polarization become manifest as differences in brightness. A drawback of such a device is that the use of a polarization filter will reduce the transparency of the display panel, which detracts from the visibility and readability of the map. To avoid this, a preferred embodiment of the device according to the invention uses an image display panel comprising two parallel transparent substrates which have transparent drive electrodes and enclose an electro-optical layer which is capable of switching between an at least substantially transparent state and an at least substantially scattering state under the influence of an electric field. A layer having such properties is known to those skilled in the art and may comprise, for example a polymer (network) in which liquid crystalline material is dispersed in the form of droplets. Dependent on its specific composition, such a material is known as PDLC (Polymer Dispersed Liquid Crystal), P LC (Polymer Network Liquid Crystal) or NCAP (Nematic Curvilinear Aligned Phase). Another example of such a material is a scattering gel or a dynamically scattering liquid crystalline material. Such layers have in common that they do not require a polarization filter to visualize an image, so that the display panel equipped with these layers may be considerably brighter than a conventional liquid crystal display panel. During operation, such a display panel is everywhere fully transparent, except for the part which is being driven such that locally scattering occurs. Consequently, captured light is scattered back towards the user, which is observed as a luminous part of the panel. The coordinates can thus be displayed as a luminous dot or spot or as a point of intersection of two luminous crosshairs. In a further preferred embodiment, at least one of the two substrates comprises a transparent synthetic material plate which is provided with a fluorescent dye and the image display panel is laterally provided with a light source which, during operation, emits visible or invisible light which is capable of causing the dye to fluoresce. In this embodiment the light from the light source is captured laterally by the display panel and due to internal reflection it will remain trapped within the panel, unless it is locally scattered by the electro-optical layer. At that location the light emerges, which is observed as a local fluorescence of the synthetic material plate. In such an embodiment an adequate contrast can already be realised with a small quantity of light so that a high efficiency is achieved and the device may be comparatively economical in energy. Instead of visible light, UV light may be used. To obtain a homogeneous lighting, TL lighting extending substantially across at least one entire side of the panel is preferred. In order to function as a global positioning system, a particular embodiment of the device according to the invention is further provided with a receiving unit and a localizing unit for determining the actual position of the device from received navigation signals. The receiving unit generally has an antenna which can receive high- frequency navigation signals which are continuously transmitted by a plurality of geostationary satellites. The actual position of the device is computed by the localizing unit from the received signals and graphically displayed on the map. The map can be identified by means of a keyboard, for example by entering the coordinates of two calibration points. A userfriendly embodiment has the rear side of the display panel provided with means for inserting a map and in that the identification means comprise a scanner which is capable of reading an identification mark of the map when the map is inserted into the insertion means. The invention also relates to a map which is specially suitable for use in this device and to this end it is characterized in that the map has an identification mark, for example in the form of a bar code. When such a map is inserted into the device, it is automatically identified and the device is immediately ready for use. The identification mark comprises, for example the absolute coordinates of two vertices, or the absolute coordinates of one vertex, plus the scale and orientation of the map. Preferably, the map has the form of a rectangular or square sheet of a suitable material, while it may fit in each of a plurality or orientations in an appropriate spacing behind the display panel. In that case, each respective orientation corresponds to a particular unique indication. Each orientation will cause its associated indication to pass along, or to be juxtaposed to an appropriate detector. Thereby, the device can identify the map in question and also detect its orientation. In consequence, the device will be able to correlate each position on the map with its corresponding location in topographical space, this raise the convenience to a user person. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. In the drawing Fig. 1 is a front elevational view of a portable type of the device according to the invention in the form of a global positioning system; Fig. 2 shows a map according to the invention which is specially suitable for use in the device of Fig. 1; Fig. 3 discloses are particular way to show a cross-like shape on the display. The drawing is diagrammatic and not to scale. For the sake of clarity, certain dimensions are shown exaggerated. The device shown comprises a global positioning system and to this end it is equipped with a receiving unit having a satellite antenna 1 and a localizing unit accommodated in a closed housing 2. The housing further accommodates a processing unit and an electric power supply in the form of a plurality of batteries or one battery. The housing also comprises a keyboard 3 with which numerical information can be entered, and an alpha-numerical liquid crystal image display panel 4 on which the entered information can be read and checked and with which coordinate data can be displayed alpha-numerically. For brevity, the global positioning method and hardware therefor will not be discussed further. Moreover, the device according to the invention has a transparent image display panel 5 behind which a conventional map can be placed. Any existing map, either or not specialized for a given purpose, such as, for example a road map, a waterway map or an aviation map may be used. Consequently, the device according to the invention can be used in a universal and flexible way. In this embodiment the image display panel comprises two transparent plates 7, 8 of synthetic material which enclose a layer of scattering gel. At their sides facing each other, the substrate plates are provided with transparent drive electrodes, for example of indium tin oxide or antimony tin oxide. The electrodes on the two substrates 7, 8 are arranged as parallel rows and parallel columns, respectively, and jointly constitute a passive matrix with which two intersecting lines 9 or a dot or a spot can be imaged in a simple manner. Such a relatively simple and inexpensive display panel 5 is sufficient for the device according to the invention. In principle, the scattering gel may be replaced by another electro-optical medium such as, for example purely liquid crystalline material or liquid crystalline material dispersed in a polymer (matrix) such as, for example a PDLC, PNLC or NCAP material. However, the use of a scattering gel has the advantage that the layer is fully transparent in the absence of an electric field, contrary to purely liquid crystalline material. Moreover, it does not require a polarization filter to visualize the lines 9 so that the map is always satisfactorily visible. Where a sufficiently high electric field is applied across the layer, the layer changes from a bright, transparent state to a scattering state so that light captured at that area is scattered back towards the user, which is observed as a luminous part of the panel. The device is thus capable of imaging two luminous crosshairs 9. Before use, the map is identified by entering two points of calibration and the scale of the map via the keyboard. If desired, an identification by means of only one point of calibration in combination with the scale and the orientation of the map, for example the geographical north. The device is capable of capturing navigation signals by means of the antenna 1, which signals are continuously transmitted by a plurality of geographic satellites. The actual position of the device, and hence of the user, is derived from the signals transmitted by a number of such satellites. A processing unit applies the computed position in the form of an electric signal to the image display panel 5 which images the position graphically in the form of, for example a dot, a spot (cursor) or, as in the relevant case, as the point of intersection 10 of two intersecting hair lines 9. Due to the previous calibration of the map, the position indicated on the map corresponds, within the measuring accuracy of the device, to the user's actual position. Moreover, the computed coordinates can be displayed on the alpha-numerical display panel 4. Although the device can be used for any arbitrary map and is thus universally applicable, a map 6 according to the invention, as shown in Fig. 2, is preferably used. The dimensions of such a map 6 correspond to the inner dimensions of the means 11 for inserting the map, which means are arranged at the rear side of the image display panel. In the device of Fig. 1 the means for inserting the map are constituted by a slot 11 into which the map 6 can be inserted. The map 6 according to the invention also has an identification mark 13, in this example a bar code which is read by an optical scanner 12 of the device of Fig. 1 as soon as the map is inserted into the slot 11. The bar code 13 comprises the data required for identification of the map 6 so that these data need not be separately entered via the keyboard 3. Thus, a user-friendly system is obtained. If the map is made insertable in a plurality of different orientations (such as two or four), the orientation may be chosen to correspond more or less close to the direction of navel of a user person. Two or four orientations are advantageous possibilities, although or other number, such as three of six, would be feasible. Although the invention has been described with reference to one embodiment, it will be evident that the invention is certainly not limited to this embodiment. Those skilled in the art will be able to conceive many variations and designs with the scope of the invention. For example, a display panel can be used with which a dot or a spot is imaged as a mark of the computed position and instead of several (hair) lines, multiple parallel lines can be imaged by simultaneously driving contiguous drive electrodes, which enhances the visibility of the lines. Moreover, the invention may not only be used for a global positioning system but also for a route planner, in which case the invention provides graphic and hence direct and comprehensible route information, or for other purposes for which relatively simple information is to be added to a map or to another image. The route planner may be based on GDS technology. Another field of use, in particular in the environment of motor vehicle, may be based on a combination of sensor, such as odomemeter and compass. Accuracy then may be raised by resetting to allowable onroad positions. When used in situations where ambient light is scarce or absent, the device may be further equipped with a light source with which the display panel can be illuminated laterally. An elongate TL lamp is preferably used, which extends substantially across at least one complete side of the panel and uniformly illuminates the panel with visible or invisible light. In a special embodiment, at least the face plate 7 of the panel is provided with a fluorescent dye which is distributed, for example homogeneously in the plate or is provided in the form of a coating, and during operation the light source emits light which is capable of causing the dye to fluoresce. Thus, an adequate contrast is reached already at a low light intensity, which contributes to the lifetime of the batteries. A magnetic mark instead of an optical identification mark may be used, in which case the device is equipped with a magnetic scanner. Moreover, the identification mark may be provided at the rear side of the map instead of at the front side so as not to reduce the useful map surface. The rear side of the map may further provide space for additional topographical information and/or advertisements or commercials. Alternatively, another map may be imaged on the rear side of the map. The device shown comprises two separate display panels 4, 5. However, it is possible to integrate the two display panels by reserving a part of the transparent display panel 5 for alpha-numerical display. Figure 3 discloses a particular way to show a cross-like shape on the display. If the map is generally light-coloured, white crosshairs may prove somewhat difficult to see. Moreover, it may prove advantageous to display a cross, rather than a crosshair fully across the dimensions of the image. The realization will be explored with reference to Figure 3. Once generated, the cross may be imaged mtermittedly, or its size may be made to very periodically of course, as long as actual position is constant, the origin of the cross is steady. The Figure shows five groups of row conductors 21-25, and five groups of column conductors 26-30. Each group may have one or more conductors. The groups 23 and 28 determine the thickness of the cross. The groups 22 and 24 determine the height of the cross. Groups 27 and 29 determine the width of the cross. Blanking of the image is done through voltage variation. Expanding and contracting of the cross is effected through changing the numbers of conductors in groups 22, 24 (for the height) and in groups 27, 29 for the width. Each group now gets a particular voltage. The PDLC effect at zero volts causes scattering, whereas at a voltage of V volts or higher, the material is translucent. The following driver voltages are provided: -V,0, V, 2V. For the discussion hereinafter, the value of V is inconsequential. In the Figure, there are eight regions, as follows. Regions A, B, C, D have been indicated and occur in every quadrant, albeit with different sizes. E is the cross it self (shown black) with its centre G (shown whit). Region F is the extension of the cross in horizontal (•*-) and vertical * directions. The following voltages and voltage differences are present now: Generally, the invention provides a very user-friendly and versatile device for displaying cartographic information, in which a relatively simple display panel is sufficient to present the coordinate data in a completely graphical way by starting from existing, conventional maps or images for the presentation of map data.

Claims: Claims: 1. A device for displaying cartographic information, comprising a processing unit for computing and generating specific coordinates and a display unit to which the coordinates are applied in the form of an electric signal and by means of which the coordinates are imaged, characterized in that the display unit comprises a transparent electro- optical image display panel, in that the display panel is capable of displaying a graphic two dimensional image of the coordinates, and in that the device comprises identification means for determining the identity of a map upon the latter 's being juxtaposed to said device. 2. A device as claimed in Claim 1, characterized in that the image display panel comprises two parallel transparent substrates which have transparent drive electrodes and enclose an electro-optical layer which is capable of switching between an at least substantially transparent state and an at least substantially scattering state under the influence of an electric field. 3. A device as claimed in Claim 2, characterized in that the electro-optical layer comprises a scattering gel which is at least substantially transparent in the absence of an electric field. 4. A device as claimed in Claim 2, characterized in that at least one of the two substrates comprises a transparent synthetic material plate which is provided with a fluorescent dye and in that the display panel is laterally provided with a light source which, during operation, emits visible or invisible light which is capable of causing the dye to fluoresce. 5. A device as claimed in Claim 4, characterized in that the light source comprises a TL lamp which extends at least substantially across at least one complete side of the display panel. 6. A device as claimed in any one of the preceding Claims, characterized in that the device is further provided with a receiving unit and a localizing unit for determining the actual position of the device from received navigation signals. 7. A device as claimed in Claim 6, characterized in that the rear side of the display panel is provided with means for inserting a map and in that the identification means comprise a scanner which is capable of reading an identification mark of the map when the map is inserted into the insertion means. 8. A device as claimed in Claim 2 and comprising a first set of substantially parallel electrodes and a second set of substantially parallel electrodes running across said first set, said device having selection wears for through selective driving among said first and second sets displaying a cross of predetermined line thickness, predetermined height, and predetermine width on said display panel. 9. A map for use in a device as claimed in Claim 7 and provided with an identification mark that juxtaposes with said scanner upon the map being inserted into said means for inserting. 10. A map as claimed in Claim 9 and fitting in each of a plurality of orientations into said means for inserting and comprising for each of said plurality of orientations a respective identification mark that juxtaposes with said scanner upon the map being inserted into said means for inserting in the associated orientation. 11. An image display panel for use in the device as claimed in any one of Claims 1 to 8.

Inventors: BERGMAN ANTHONIE HENDRIK, NEIJZEN JACOBUS HERMANUS MARIA, SCHOEREN HUBERTES JOHANNES BER, BERGMAN, ANTHONIE, HENDRIK, NEIJZEN, JACOBUS, HERMANUS, MARIA, SCHOEREN, HUBERTES, JOHANNES, BERNARDES
Applicants: PHILIPS ELECTRONICS NV, PHILIPS NORDEN AB, PHILIPS ELECTRONICS N.V.
Application year: 1995
Main classification: G01C21
IPC codes: G01C21, G01S5, G02F1, G08G1, G09B29