WO1996013821A1

WO1996013821A1 - Display device

Info

Publication number: WO1996013821A1
Application number: PCT/GB1995/002525
Authority: WO
Original assignee: Stubenrauch, Bernhard, Wilhelm, August
Priority date: 1994-10-26
Filing date: 1995-10-26
Publication date: 1996-05-09
Also published as: AU3705895A

Abstract

A device (10, 22) comprises a substrate (18, 34) on which there is provided printed information (42, 46) such as questions and answers, a transparent layer (16, 30) overlying the substrate, and means for rendering a selected portion (44) of the layer overlying the answers non-transparent except when it is exposed to a selected stimulus such as applied pressure or the temperature of a user's finger. The selected portion (44) is rendered transparent only during exposure to the stimulus. The display device (10, 22) can be written on with a dry-marker pen and the correctness of the user's response checked by the user against the printed answers according to the educational system of: look, cover, write, check.

Description

DISPLAY DEVICE

This invention concerns a display device, in particular a device for displaying information in response to an action by a user, especially in an educational situation.

According to a first aspect of the present invention there is provided a display device comprising a substrate on which there is provided visually apprehendable information, a transparent layer overlying the substrate, and means for rendering a selected portion of the layer non-transparent except when it is exposed to a selected stimulus, said selected portion being rendered transparent only during exposure to the stimulus.

In one embodiment of the invention the means for rendering said selected portion non-transparent may be provided by a thermo-chromatic layer applied to said selected portion, the thermo- chromatic layer being adapted to become transparent only when exposed to a temperature stimulus at a selected temperature above ambient temperature, and to become non-transparent at temperatures below said selected temperature. The selected temperature is preferably at near body temperature. The thermo-chromatic layer may be provided by a thermo-chromatic ink applied to said selected portion.

In a second embodiment of the invention the means for rendering said selected portion of the transparent layer non-transparent may be provided by a pressure-sensitive or twisting- sensitive layer applied to said selected portion, the pressure-sensitive or twisting- sensitive layer being adapted to become transparent only when exposed to an applied pressure or twisting stimulus at a selected pressure or degree of twisting, and to become non-transparent when the applied pressure or twisting stimulus is removed.

The transparent layer is preferably a foil of plastics material. The foil may encapsulate the substrate. The plastics material may be such that it may be drawn on or written on with a wipe-away marker device.

Alternatively, the transparent layer may be covered with an outer layer of clear film that is capable of being drawn on or written on with a wipe-away marker device. The substrate is preferably paper, the information being printed on it.

The thermo-chromatic ink will contain at least one chemical substance that has the property of changing colour or intensity in response to temperature changes. Such chemical substances are well known.

The pressure-sensitive layer may be, for example, provided by a laminate including two films, at least one of which has light polarising properties, and, between the films, a layer of liquid crystals whose polarisation changes with respect to applied pressure or twisting. Hence, in one configuration, i.e. no applied pressure to or twisting of, the area, the polarisations of the film and liquid crystals are at right angles so that no light is able to pass through the laminate, and in another configuration, i.e. applied pressure or twisting, the polarisation of the liquid crystals is parallel to that of the film so that the laminate becomes transparent in that region.

Although thermo-chromatic ink will be preferred for most purposes, it will be appreciated that in some circumstances the much quicker response of the pressure-sensitive or twisting-sensitive layer may be more desirable.

Hence, for example in an educational situation, the information printed on the paper may be sets of data such as series of questions and answers, a first set of data, i.e. the questions, always being visible through a permanently transparent region of the overlying layer of plastics foil, and a second set of data, i.e. the answers, lying under other regions of the overlying layer that are coated with a thermo-chromatic ink which, at room temperature, is opaque.

When a user touches such a coated region adjacent a question printed on the paper, the heat from his finger raises the temperature of the coated region to a level where the thermo- chromatic ink becomes transparent, thus rendering visible the answer or other pre¬ determined message relating to the adjacent permanently visible question. When the user removes his finger from the coated region the temperature of the region where his finger was placed falls and the thermo-chromatic ink once more becomes opaque.

There may be provided on the device a test area coated with a type of thermo-chromatic material that changes colour according to the temperature, so that a user may test first whether his finger is warm enough before using the device for a question and answer session.

Because the plastics foil is capable of being written upon with, for example a wipe-away marker pen, the user may also write or indicate his answer to a question using the marker, and then compare his answer with the correct one by touching the appropriate thermo-chromatically coated region. The writing made by the marker may then be wiped off and the device re-used. Thus, the system enables the user to verify his answers himself without recourse to a teacher.

According to a second aspect of the present invention there is provided a display device comprising a substrate on which there is provided visually apprehendable information, the substrate being encapsulated in a transparent film which is capable of being drawn on or written on with a wipe-away marker means or the like.

The substrate is preferably paper on which the information is printed. As in the first aspect, the display device of the second aspect may be in the form of an educational placemat on which children or others may draw or write with wipe-away markers in order to answer written questions or questions asked verbally by a teacher. The paper of the substrate may feature various standard learning elements such as time, arithmetical tables, spelling, geography, languages, history, or the like. As with the first aspect, the encapsulation permits writing or drawing by the marker to be wiped off and the placemat re-used. Again, the user may be able to verify his answer by reference to matter printed on the paper of the substrate, thus enabling the user to implement the learning system of:

1. The learner looks at a pre-printed question and answer.

2. The learner covers the pre-printed answer from view.

3. The learner writes down what he thinks is the correct response to the question.

4. The learner uncovers the pre-printed answer and compares the correct answer with his own response.

According to a third aspect of the present invention there is provided a re-usable write-on wipe-off display device containing printed questions which can be answered by a user by writing on the device using an erasable marker, the device also containing printed correct answers to the questions and incorporating a layer which hides said correct answers from view, the layer being adapted to reveal a said correct answer only when exposed to a stimulus applied by the user, hence enabling the user to verify his response to the question during the application of the stimulus.

Preferably, as in the first aspect, the layer incorporates thermo-chromatic material which becomes transparent only when exposed to the stimulus of heat from the user's finger. Alternatively, the layer may incorporate pressure-sensitive or twist-sensitive material which becomes transparent only when exposed to a pressure or twisting stimulus applied by the user.

The invention according to the several aspects will now be described with reference by way of example only to the accompanying non-scale diagrammatic drawings in which,

Figure 1 is a section through a first embodiment of a portion of a display device according to the first aspect of the invention,* Figure 2 is a section through a second embodiment of a portion of a display device according to the first aspect of the invention;

Figure 3 is a plan view of an educational device utilising the display device of either Figure 1 or Figure 2; and

Figure 4 is a section through a display device according to the second aspect of the invention.

Referring to Figure 1 of the drawings, a first embodiment of the first and third aspects of the invention, there is shown a portion of a display device 10 comprising a laminate 12 consisting of, reading from the top to the bottom, a top transparent protective polyester film 14, a middle layer of thermo-chromatic ink 16, a paper substrate 18, and a bottom polyester support or backing layer 20.

The thermo-chromatic ink 16, one example of which is made by USP Transfers GmbH of Klagenfurt, Austria, is designed with the property of being opaque to visible light at temperatures a few degrees less than body temperature, but of becoming transparent when raised to the temperature of the external surface of a human finger, and reverting to opacity when it cools below that temperature.

The paper substrate 18 is provided on its top surface with sets of printed data, e.g. questions and answers. The layer 16 of thermo- chromatic ink is positioned so that only the answers are concealed by the ink and the questions are not covered by the layer 16 and so are always visible.

Referring now to Figure 2 there is shown a portion of a display device 22 according to a second embodiment of the first and third aspects of the invention, comprising a pressure- sensitive laminate 24 consisting of a protective top layer 26 of transparent polyester film, a transparent film 28 having light polarising properties, a layer 30 of liquid crystals whose polarisation changes with respect to applied pressure or twisting of the area, a transparent film 32, a paper substrate 34 having data printed on its top surface, and a bottom polyester support or backing layer 36.

The light polarising arrangements of the film 28 and liquid crystal layer 30 are at right angles so that when no finger pressure or twisting is applied to the surface of the laminate 24 light is not transmitted through layers 28 and 30. Any data printed on the paper substrate 34 beneath layer 30 is therefore concealed from view. However, when finger pressure is applied to the surface of the laminate, or the laminate is twisted, the polarisation of the liquid crystal layer 30 changes to that of layer 28 so that light is able to pass through layers 28 and 30, thus enabling data on the paper substrate to be read.

The film 32 may be a simple protective film to contain the liquid crystal layer 30, or it may also possess light polarising properties the same as those of layer 28.

As in Figure 1, the paper substrate 34 is provided on its top surface with sets of printed data. The liquid crystal layer 30 is positioned so that one set of data only is covered by the liquid crystal layer and concealed by the opposite polarisations of layers 28 and 30, and the other set of data is not so covered. Hence, by applying finger pressure to the laminate 24, the polarisation of the liquid crystal layer 30 can be changed to that of layer 28 (and possibly layer 32 if that is also polarised) as to enable light to pass through all layers above the paper substrate 34 and permit the first set of data printed on the paper substrate to be inspected.

Referring to Figure 3 there is shown a "placemat" or mat 38 which incorporates a laminate 12 or 24 as shown in the embodiments of Figure 1 or Figure 2. The mat 38 has a first area 40 of data 42 which is printed on substrate 18 or 34 as the case may be and is not covered by the respective layer 16 or 30. Hence the data 42 revealed in area 40 is always visible. Further areas 44 of data 46 are covered by a respective layer 16 or 30. Hence the data 46 in areas 44 cannot be seen unless the user applies a finger to an area 44. If that area 44 is covered by a thermo-chromatic layer 16 then the heat from the user's finger will render that layer transparent and enable the data 46 to be read and compared with the user's answer. If the area 44 is covered by a liquid crystal layer 30 then the pressure of the user's finger, or twisting of the relevant area, will change the light polarisation and enable light to pass through to the substrate 34, thus enabling the data 46 to become visible. In either case, removal of the user's finger from the laminate will cause the process to reverse and render the data 46 concealed again. In the case of the thermo-chromatic arrangement of Figure 1 it is convenient to provide on the mat 38 a test area 48 comprising a thermo- chromatic layer which changes colour according to the temperature of the user's finger when he touches the area 48. This is to accommodate a situation where the user's finger may be initially too cold to activate the thermo- chromatic layer 16 and thereby give him advance warning.

The invention as described with reference to Figures 1 -3 may be used in the earlier stages of a child's education where basic elements such as time, arithmetical tables and spelling are taught.

In one method of teaching children or other pupils, a method known as the "look, cover, write, check" method, the device 10 or 22 may be used as follows:

1. A child touches the thermo-chromatic or pressure area 44 adjacent a question in area 42 with his finger: the answer appears as the heat from his finger, or finger pressure, causes the area to become transparent. The child is thus able to see the answer. 1-2

2. The child stops touching the area 44: the answer disappears as the area cools or the pressure is released.

3. The child writes the answer on the mat 10 or 22 in a boxed area reserved for the purpose.

4. The child touches the area 44 again: the answer reappears.

5. The child checks its own written answer with the correct answer as revealed in the touched area.

The invention according to the first aspect may also be used to provide information in low-level security situations where an authorised user needs easy access to information but it is not desired that the information should be permanently on display.

The invention according to the first aspect may also be used in the design of board games.

Referring now to the second aspect of the invention, there is shown in Figure 4 a display device 50 provided by a laminate 52 comprising a substrate 54 of paper or similar material on which there is provided visually apprehendable material such as printed data. The substrate 54 is encapsulated in a transparent polyester film 56 which is capable of being drawn or written on with a wipe-away marker pen or the like.

As in the first aspect of Figures 1 - 3, the display device 50 of the second aspect may be in the form of an educational placemat on which children or others may draw or write with wipe- away markers in order to answer written questions or questions asked verbally by a teacher. The paper of the substrate may feature various standard learning elements such as time, arithmetical tables, spelling, geography, languages, history, or the like. As with the first aspect, the encapsulation permits writing or drawing by the marker to be wiped off and the placemat re-used.

Claims

C ATMfi

1. A display device comprising a substrate on which there is provided visually apprehendable information, a transparent layer overlying the substrate, and means for rendering a selected portion of the layer non-transparent except when it is exposed to a selected stimulus, said selected portion being rendered transparent only during exposure to the stimulus.

2. A display device according to claim 1 wherein the means for rendering said selected portion non-transparent is provided by a thermo- chromatic layer applied to said selected portion, the thermo-chromatic layer being adapted to become transparent only when exposed to a temperature stimulus at a selected temperature above ambient temperature, and to become non-transparent at temperatures below said selected temperature.

3. A display device according to claim 2 wherein the selected temperature is at or near body temperature.

4. A display device according to claim 2 or 3 wherein the thermo-chromatic layer is provided by a thermo-chromatic ink applied to said selected portion. 1-2

5. A display device according to claim 1 wherein the means for rendering said selected portion of the transparent layer non-transparent is provided by a pressure-sensitive or twisting- sensitive layer applied to said selected portion, the pressure-sensitive or twisting- sensitive layer being adapted to become transparent only when exposed to an applied pressure or twisting stimulus at a selected pressure or degree of twisting, and to become non-transparent when the applied pressure or twisting stimulus is removed.

6. A display device according to any preceding claim wherein the transparent layer is provided by a foil of plastics material.

7. A display device according to claim 6 wherein the foil is adapted to encapsulate the substrate.

8. A display device according to claim 6 or 7 wherein the plastics material is such that it may be drawn on or written on with a wipe-away marker device.

9. A display device according to claim 6 or 7 wherein the transparent layer is covered with an 11

outer layer of clear film that is capable of being drawn on or written on with a wipe-away marker device.

10. A display device according to claim 1 wherein the substrate is paper, the information being printed on it.

11. A display device according to claim 4 wherein the thermo-chromatic ink contains at least one chemical substance that has the property of changing colour or intensity in response to temperature changes.

12. A display device according to claim 5 wherein the pressure-sensitive or twisting- sensitive layer is provided by a laminate including two films, at least one of which has light polarising properties, and, between the films, a layer of liquid crystals whose polarisation changes with respect to applied pressure or twisting.

13. A display device according to any preceding claim wherein the display device is in the form of a mat in which the information printed on the paper comprises a first set of data which is always visible -through a permanently transparent region of the overlying layer of plastics foil, S

and a second set of data lying under other regions of the overlying layer that are opaque until touched by a user.

14. A display device as claimed in claim 13 wherein the mat is provided with a test area coated with a thermo-chromatic material that changes colour to indicate temperature, so that the user may test the temperature of his finger before using the device.

15. A display device comprising a substrate on which there is provided visually apprehendable information, the substrate being encapsulated in a transparent film which is capable of being drawn on or written on with a wipe-away marker means or the like.

16. A display device according to claim 15 wherein the substrate is paper on which the information is printed.

17. A display device according to claim 15 or 16 wherein the display device is in the form of a mat on which a user may draw or write with a wipe-away marker in order to answer written questions or questions asked verbally by a teacher. 13.

18. A re-usable write-on wipe-off display device containing printed questions which can be answered by a user by writing on the device using an erasable marker, the device also containing printed correct answers to the questions and incorporating a layer which hides said correct answers from view, the layer being adapted to reveal a said correct answer only when exposed to a stimulus applied by the user, hence enabling the user to verify his response to the question during the application of the stimulus.

19. A re-usable write-on wipe-off display device as claimed in claim 18 wherein the layer incorporates thermo-chromatic material which becomes transparent only when exposed to the stimulus of heat from the user's finger.

20. A re-usable write-on wipe-off display device as claimed in claim 18 wherein the layer incorporates pressure-sensitive or twist- sensitive material which becomes transparent only when exposed to a pressure or twisting stimulus applied by the user.

21. A display device substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings. 2Ω

22. A re-usable write-on wipe-off display device substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.

23. A display device substantially as hereinbefore described with reference to Figure 4 of the accompanying drawings.