WO2009106146A1

WO2009106146A1 - Changeable pattern in a structure

Info

Publication number: WO2009106146A1
Application number: PCT/EP2008/052538
Authority: WO
Inventors: Kenichi Hashizume; Hiroharu Kitaura
Original assignee: Nokia Corporation
Priority date: 2008-02-29
Filing date: 2008-02-29
Publication date: 2009-09-03

Abstract

A structure comprises first (23) and second light guide layers (24), each comprising a pattern of photo luminescent material; and a light source (28a, 28b) configured to direct light into the first and second light guide layers to selectively illuminate the patterns of the first and second light guide layers. A light shielding layer (25) may be provided between the light guide layers to prevent the light from one layerfrom enteringthe other layer. The structure may be used in a keypad, in which case the patterns may be character sets. The structure may also be used for a cover of an electronic device. The structure may comprise further light guide layers providing further character sets or decorative patterns.

Description

CHANGEABLE PATTERN IN A STRUCTURE

Technical Field

The invention relates to the provision of a changeable pattern in a structure. More particularly, but not exclusively, the invention relates to a keypad having changeable key character sets or a cover for an electronic device having a changeable decorative pattern.

Background Art Developers and manufacturers of mobile terminal include more and more different applications in mobile terminals to compete for customers. Different applications require different key functionalities. Customers also tend to prefer smaller mobile terminals, which leaves less space for keys. This problem is often solved by keys having different functions in different applications. For example, a key may be used to enter a plurality of letters as well as a number. The function of the key is usually indicated graphically on or above the key. Showing all the functions at the same time can confuse the user about which function a key has in a particular application.

One solution to this problem involves illuminating each character set with light of a different colour. However, this solution requires a large number of LEDs and results in increased power consumption. It is also difficult to have optically separates structures within a small key. Moreover, to hide multiple character sets from a user's view, optical filters having 10 to 30% or less transparency are sometimes used, which results in less light penetrating through the filters and a brighter backlight being required. Again, this means that the number of LEDs have to be increased which in turn results in increased power consumption.

Another solution to this problem involves having a touch pad or a display element underneath each key which shows a different graphical indication in each application. It is also desirable to provide mobile terminals comprising covers with changeable patterns in order to attract customers. This has been solved in the past by supplying mobile terminals with removable and interchangeable covers having different colours and patterns.

The invention aims to improve on the prior art solutions.

Summary

According to the invention, there is provided a structure comprising: first and second light guide layers, each comprising a pattern of photo luminescent material; and a light source configured to direct light into the first and second light guide layers to selectively illuminate the patterns of the first and second light guide layers.

The structure may comprise a light shielding layer between the first and second light guide layers for preventing light for one of the first and the second light guide layers to enter the other one of the first and the second light guide layers. The light shielding layer may have a lower refractive index than the first and the second light shielding layers.

The light source may comprise a first and a second light emitting diode (LED). The first light guide layer comprises means for receiving light from the first LED and the structure may further comprise a light shielding portion positioned in a recess in the first light guide layer for preventing light from the second LED from entering the first light guide layer. The means for receiving light from the first light source may be a hole for receiving the first LED. The structure may further comprise a light shielding portion positioned with respect to the first LED to prevent light from the first LED from entering the second light guide layer. The second light guide layer may comprise a hole for receiving the second LED and the structure may further comprise a light shielding portion positioned with respect to the second LED such that it prevents light from the second LED from escaping to other layers and a further light shielding portion for positioning in a recess in the second light guide layer for preventing light from the second light guide layer from escaping through the side of the second light guide layer. The LEDs may be Ultraviolet light LEDs.

The photo luminescent material may comprise a transparent photo luminescent material. The photo luminescent material may comprise a nano-composite material based on cerium, terbium or europium. The pattern may be printed and light guide material may be coated thereon.

The structure may comprise a third light guide layer comprising an embedded pattern of photo luminescent transparent material and a light shielding layer shielding the third light guide layer from the second light guide layer.

The structure may further comprise a top film for protecting the light guide layers.

According to the invention, there is provided a keypad comprising the structure set out above. The pattern of the first and the second light guide layer may comprise a first and a second character set. The keypad may comprise an input sensing structure having an input sensing element for each character of the character sets. The input sensing structure may comprise a keypad dome layer having a dome for each key, and a printed wire board (PWB) comprising an electronic structure for each dome, the dome being provided in a position corresponding to the position of each character in the first and the second character set.

According to the invention, there is also provided a device comprising a processor for running a plurality of applications; and a keypad as set out above, the processor being configured to operate the light source for directing light into the first and second light guide layers to selectively illuminate the patterns of the first and second light guide in dependence on the application being run by the processor. The device may be a mobile telephone. According to the invention, there is also provided a cover for an electronic device comprising the structure as set out above. The invention also provides a device comprising a processor and the cover, the processor being configured to operate the light source for directing light into the first and second light guide layers to selectively illuminate the patterns of the first and second light guides. The device may be a mobile telephone.

Brief Description of Drawings Embodiments of the invention will now be described by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a mobile device in a network;

Figure 2 is a schematic diagram of circuitry for use in the device of Figure 1;

Figures 3 illustrates an example of the structure of a keypad according to the invention;

Figures 4a and 4b show the assembled keypad in two different operational states;

Figures 5a and 5b shows an example of a mobile device according to the invention in two different operational states;

Figures 6a and 6b shows another example of a mobile device according to the invention in two different operational states;

Figure 7 illustrates an example of the structure of the cover of a mobile terminal according to the invention.

Figure 8 is a perspective view of a mobile device with a changeable cover according to one embodiment of the invention.

Detailed Description

With reference to Figure 1, a mobile device in the form of a mobile telephone handset 1 comprises a cover 2, an earpiece 3, a microphone 4, a keypad 5, further keys comprising soft keys 6a, 6b, keys for initiating and ending a telephone call 6c, 6d and a navigation key 6e, an LCD display 7 and an internal antenna (not shown). The handset is operable to communication via a base station 8 with one or more individual land mobile networks 9, which may include but are not limited to GSM, GPRS and CDMA networks.

Figure 2 illustrates the major circuit components of the handset 1. The circuit components are powered by the battery 10. Signal processing is carried out under the control of a processor in the form of a digital microcontroller 11. The processor has an associated memory 12, which may comprise a flash memory. Electrical analogue audio signals are produced by microphone 4 and amplified by pre-amplifier 13. Similarly, analogue audio signals are fed to the speaker 3 through an amplifier 14. The microcontroller 11 receives instruction signals from the keypad 5 and further keys 6 and controls operation of the LCD display 7.

Information about the identity of the user is held on a smart card 15 which may be in the form of a GSM SIM card. The SIM card is removably received in a SIM card reader 16 connected to the microcontroller 11.

The handset circuitry includes a codec 17 and a radiofrequency (rf) stage 18 connected to an antenna 19. The codec 17 receives analogue signals from the microphone amplifier 13, digitizes them into a GSM signal format and feeds them to the rf stage 18 for transmission through the antenna 19 to the network 9. Similarly, signals received from the network 9 are fed through the antenna 19 to be demodulated in the rf stage 18 and fed to codec 17, so as to produce analogue signals fed to the amplifier 14 and earpiece 3.

The memory stores application programs such as a browser, various games, and a music player. The memory may also store graphical and audio data for running the browser and playing the games. It may further store music tracks for the music player. Different functions of the keys of the keypad 5 are required for different applications. For example, when the handset is used to make a telephone call, the keys of the keypad can be used to enter the numbers 1 to 9 and when the handset is used to play music tracks the keys of the keypad may be used to play, stop, forward and rewind a track.

To allow the user to remember the function of each key of the keypad, the keypad is arranged to show an indication of the associated function. The indication changes in dependence on the specific function the key has in a particular application.

With reference to Figure 3, the keypad comprises a plurality of layers including a Printed Wire Board (PWB) 20, a key dome sheet 21, a mask sheet 22, first and second light guide layers 23, 24, separated by a shell layer 25 and a top protective layer 26. In this example, the layers are formed from flexible materials to provide a flexible keymat. However, it should be understood that the layers can also be formed from rigid materials.

The PWB 20 comprising one electrical circuit structure 27 for each key and two light emitting diodes (LEDs) 28a and 28b, located in one end of the PWB 20. The PWB communicates with the processor 11. The key dome sheet 21 comprises one dome 29 for each key in a position corresponding to the position of an associated electrical circuit structure 27 of the PWB. The key dome sheet 21 is flexible and each dome can be depressed by a user. In this example, the dome key sheet is made of metal and the dome completes a circuit in the associated electrical structure 27 when depressed to indicate to the controller 11 that a key has been pressed. The key dome sheet further comprises two holes 30a, 30b located in one end of the key dome sheet, for receiving the LEDs 28a, 28b.

The mask sheet 22 is a light shielding layer provided above the key dome sheet

21 to prohibit light from the light guide layers from being reflected from the key dome sheet 21 and going to unnecessary parts of the keypad 5. The mask sheet

22 typically has a dark colour to improve masking properties. The mask sheet 22 comprises two holes 31a, 31b along one end of the mask sheet for receiving the LEDs 28a and 28b.

The first light guide layer 23 comprises a first character set 32 printed by photo luminescent transparent material. In this example, a transparent photo luminescent polymer is embedded in the sheet 23 by printing and coating light guide material on the printed pattern. The polymer may be printed on the mask sheet 22, using the mask sheet as a substrate, and the light guide material can then be coated thereon. Alternatively, the polymer may be printed on a carrier film as a temporary substrate before the light guide material is formed around the printed polymer and the temporary substrate is removed. It should be understood that any suitable process for embedding a printed polymer in a light guide layer may be used. The layer comprises one hole 33a in a position corresponding to the position of one of the LEDs 28a on the PWB for receiving light from the LED 28a. A blind piece 34 comprising a hole 33b for the other LED 28b is provided in a recess 35 in the first light guiding layer 23. The shape of the recess 35 corresponds to the shape of the blind piece 34. The blind piece 34 ensures that the light from the second LED 28b does not enter the first light guide layer 23. Another blind piece 36 is positioned above the hole 33a for the first LED 28a to stop the light for the first light guide layer 23 to enter upper layers, including the second light guide layer 24.

Above the first light guide layer there is provided a transparent shell sheet 25. The transparent shell sheet has a higher reflectance than the light guide layers 23, 24 and is provided to prevent light from one light guide layer to enter the other light guide layer. By laminating the shell sheet between the light guide layers, the light in the light guide layers can be encapsulated within the light guide layers. The transparent shell layer 25 therefore comprises a film of any suitable material with a lower refractive index than the material of the light guide layer, such that most rays from the LED are totally internally reflected. The second light guide layer 24 comprises a second character set 37. The character set is printed using a transparent photo luminescent polymer and the polymer is coated by a light guide material. The second light guide layer 24 comprises an opening 38 along one end of the second light guide layer for receiving light from the second LED 28b, to direct the light from the second LED into the second light guide layer 24. A blind piece 39 with a shape corresponding to a recess 40 in the second light guide layer 24 is provided to prohibit light leakage through the side of the light guide layer 24. A further blind piece 41 is provided to prohibit light leakage from the second LED to the top layer 26. The blind pieces 34, 36, 39, 41 have a dark colour to absorb light incident thereon. Blind pieces 34 and 39 also have different heights to blind pieces 36 and 41 to take into account the height of the light guide layers 23, 24. The blind pieces may be made of any material that shields light well, including, but not limited to, paper, polymers, metal, ceramic and textiles having high enough density to shield light. Examples of suitable polymers include PET, acrylic resin and polycarbonate.

The top cover film 26 may be formed from any material that protects the other layers and improves surface quality and image quality. The top cover film 26 may include, but is not limited to, polyacrylic resins, Polyethylene terephthalate (PET) and polycarbonate. Silicon hard coating materials may also be used.

Although the photo luminescent material has been described above to be provided as a polymer, this is just an example. The photo luminescent material may, for example, also be provided as an oligomer or monomer. Examples of suitable materials include any optic use polymer such as Polymethyl methacrylate (PMMA), silicone polymer or cyclo poly olefin. Epoxy resins or photocurable acrylic monomers may also be used. The polymer, monomer or oligomer may be an organic or inorganic nano-composite material based on a rare earth element as the chromophore. The rare earth element may include, but is not limited to, Cerium, Terbium or Europium. In some embodiments, the LED emits UV light such that the emitted visible light from the printed pattern does not cause the printed pattern in another layer to be excited. The visible light generated by the photo luminescent material in one layer does not have high enough energy to excite the electrons in the photo luminescent polymer in another layer.

Although the keypad has been described to include a PWB and metal key dome sheet, it is possible to use any other suitable mechanism for recognising that a key has been pressed including, but not limited to, touch panels, capacitive sensors and pressure sensors.

Moreover, although the keypad has been described to comprise two layers, this is just an example and the keypad may comprise further layers to provide further key character sets. A shell sheet may be sandwiched between each light guide layer comprising a new character set in order to avoid light from one light guide layer entering another light guide layer.

The assembled keypad is shown in Figures 4a and 4b. As shown in Figure 4a, when the first LED is on, the first character set can be seen through the top cover 26. As shown in Figure 4b, when the second LED is on, the second character set can be seen through the top cover. The first character set is suitable for a music player application whereas the second character set is suitable for dialling a telephone number. The keypad is consequently provided with a changeable character set without any electronics for key illumination except conventional circuit for the key pad and the LEDs.

With reference to Figures 5a and 5b, a mobile phone having a keypad according to one example of the invention is shown in two different operational states. When a user opens a new application, the processor 11 operates the appropriate LED 28a, 28b to illuminate a character set suitable for the application. The character set shown in Figure 5a is suitable for a music player application whereas the character set shown in Figure 5b is suitable for dialling a telephone number or sending a short message service (SMS) message.

In other embodiments of the invention, one of the light guide layers can have a decorative pattern instead of a character set. Moreover, the decorative pattern may be shown in addition to or instead of the character set. With reference to Figure 6a, a mobile telephone having a keypad with a character set comprising letters and numbers is shown. The character set may be embedded in a light guide layer as described with reference to Figure 3 and displayed when the light guide layer is illuminated with a first LED. With reference to Figure 6b, the keypad now also has a background pattern. The background pattern may be embedded in a second light guide layer and displayed when the second light guide layer is illuminated with a second LED.

Another embodiment of the invention will now be described with reference to Figures 7 and 8. Figure 7 illustrates the structure of a cover of a mobile telephone. The cover comprises a plurality of layers comprising a mask sheet 42, three light guide layers 43, 44, 45, two shell sheets 46 and 47 sandwiched between the light guide layers and a top layer 48. The structure further comprises three LEDs 49a, 49b, 49c on a Printed Wire Board (PWB) 50. The top film, the light guide layers and the mask sheet have a larger surface area than the PWB to cover the outside of the mobile device. The layers may be flexible and moulded to fit around corners of the mobile handset 1.

Each of the three light guide layers comprises an embedded pattern 51, 52, 53 printed with a photo luminescent transparent material, as described with respect to Figure 3.

The mask sheet 42 comprises three holes 54a, 54b, 54c for receiving the LEDs. The mask sheet ensures that the light from the LEDs does not enter other parts of the device in which the cover is used. The mask sheet 42 has similar properties to the mask sheet 22 described with respect to Figure 3 and will not be described in more detail here.

The first light guide layer 43 comprises a hole 55a for receiving light from the first LED 49a for illuminating the pattern 51 in the first light guide layer. A blind piece 56, having two holes 55b, 55c for receiving light from the second and third LEDs 49b, 49c respectively, is shaped to fit into a recess 57 in the first light guide layer 43. The blind piece 56 ensures that the light from the second and third LEDs 49b, 49c does not enter the first light guide layer 43. A further blind piece 58 is provided to be positioned above the hole 55a for the first LED 49a to stop the light from the first LED 49a to enter upper layers, including the second and third light guide layers 44, 45. The further blind piece 58 may be thinner than the blind piece 56 comprising the holes for the second and third LEDs to provide a level surface.

The second light guide layer 44 comprises a hole 59a for receiving light from the second LED 49b for illuminating the pattern 52 in the second light guide layer 44. A blind piece 60, having a hole 59b for receiving light from the third LED 49c, is shaped to fit into a recess 61 in the second light guide layer 44. The blind piece 60 ensures that the light from the third LED 49c does not enter the second light guide layer 44. Another blind piece 62, shaped to fit into another recess 63 in the second light guide layer 44 in a position over the first LED 49a, ensures that light from the second LED does not escape through the side of the second light guide layer 44. A third blind piece 64 is provided to be positioned above the hole 59a for the second LED 49b in the second light guide layer 44 to stop the light from the second LED 49b to enter upper layers, including the third light guide layer 45. The third blind piece 64 may be thinner than the blind piece 60, comprising the hole 59b for the third LED, and the blind piece 62, for preventing the light from escaping through the side of the second light guide layer, in order to provide a level surface and minimise the air gaps between the second light guide layer 44 and the shell sheet 47 positioned above the second light guide layer 44. The third light guide layer 45 comprises an opening 65 for receiving light from the third LED 49c for illuminating the pattern 53 in the third light guide layer. A blind piece 66, shaped to fit into a recess 67 in a position over the first and the second LEDs 49a, 49b, ensures that light from the third LED does not escape through the side of the third light guide layer 45. A further blind piece 68 is provided to be positioned above the opening 65 for the third LED 49c in the third light guide layer 45 to prevent light from the third LED 49c from entering the top layer 48. To compensate for the height of the third light guide layer 45, the further blind piece 68 may be thinner than the blind piece 66 for preventing the light from the third LED from escaping through the side of the third light guide layer. The blind pieces 56, 58, 60, 62, 64, 66, 68 may have a dark colour to absorb light incident thereon.

The shell sheets 46, 47 are sandwiched between the light guide layers 42, 43, 44 to prevent light from one light guide layer from entering a neighbouring light guide layer. The shell sheets 46, 47 have similar properties to the shell sheet described with reference to Figure 3 and will not be described in detail again.

The top cover film 48 may be formed from any material that protects the other layers and improves surface quality and image quality. It has similar properties to the top cover film 26 described with respect to Figure 3.

In some embodiments, a mobile telephone 1 comprising the cover of Figure 7 is provided with a menu for selecting one of the patterns 51, 52, 53. A selection using the menu causes the LED for illuminating the layer with the selected pattern to be turned on and the other LEDs to be switched off. One of the LEDs may be turned on by default when the mobile phone 1 is first turned on.

With reference to Figure 8, a handset comprising an example of a cover 2 according to one embodiment of the invention is shown. The cover 2 has a light guide layer comprising a pattern of feathers. Since in the embodiments described above, the patterns in the light guide layers are transparent, no optical filter is required to hide the multiple character sets from view. Consequently, fewer LCDs and lower processing power is required to illuminate the structure. However, the invention may also comprise character sets that are semi-transparent or not transparent at all.

Although the keypad with multiple character sets and the cover with multiple patterns have described as separate embodiments of the mobile handset, it should be understood that they can form part of the same embodiment of a mobile phone.

Moreover, it will be understood that while the keypad and the cover have been described and illustrated with respect to a mobile handset, this is merely a specific example of the invention, and the structure with changeable patterns could be incorporated in any electronic device.

Claims

1. A structure comprising: first and second light guide layers, each comprising a pattern of photo luminescent material; and a light source configured to direct light into the first and second light guide layers to selectively illuminate the patterns of the first and second light guide layers.

2. A structure according to claim 1 further comprising a light shielding layer between the first and the second light guide layers for preventing light for one of the first and the second light guide layers to enter the other one of the first and the second light guide layers.

3. A structure according to claim 2, wherein the light shielding layer has a lower refractive index than the first and the second light shielding layers.

4. A structure according to any one of the preceding claims, wherein the light source configured to direct light into the first and second light guide layers to selectively illuminate the patterns of the first and second light guide layers comprises a first and a second light emitting diode (LED).

5. A structure according to claim 4 wherein the first light guide layer comprises means for receiving light from the first LED and the structure further comprises a light shielding portion positioned in a recess in the first light guide layer for preventing light from the second LED from entering the first light guide layer.

6. A structure according to claim 5, wherein the means for receiving light from the first light source is a hole for receiving light from the first LED.

7. A structure according to claim 5 or 6, wherein the structure further comprises a light shielding portion positioned with respect to the first LED to prevent light from the first LED from entering the second light guide layer.

8. A structure according to any one of claims 4 to 7, wherein the second light guide layer comprises an opening for receiving light from the second LED and the structure further comprises a light shielding portion positioned with respect to the second LED such that it prevents light from the second LED from escaping to other layers and a further light shielding portion for positioning in a recess in the second light guide layer for preventing light from the second light guide layer from escaping through the side of the second light guide layer.

9. A structure according to any one of claims 4 to 8, wherein the LEDs emit Ultraviolet light.

10. A structure according to any one of the preceding claims, wherein the photo luminescent material comprises a transparent photo luminescent material.

11. A structure according to claim 7, wherein the pattern is printed and light guide material is coated on the printed pattern.

12. A structure according to any one of the preceding claims comprising a third light guide layer comprising an embedded pattern of photo luminescent transparent material and a light shielding layer shielding the third light guide layer from the second light guide layer.

13. A structure according to any one of the preceding claims, further comprising a protective film for protecting the light guide layers.

14. A structure according any one of the preceding claims, wherein the photo luminescent material comprises a nano-composite material based on cerium, terbium or europium.

15. A keypad comprising the structure according to any one of claims 1 to 14.

16. A keypad according to claim 15, wherein the pattern of the first and the second light guide layer comprises a first and a second character set.

17. A keypad according to claim 15 or 16, comprising an input sensing structure having an input sensing element for each character of the character sets.

18. A keypad according to claim 17, wherein the input sensing structure comprises a keypad dome layer having a dome for each key, and a printed wire board comprising an electronic structure for each dome, each dome being provided in a position corresponding to the position of a character in the first and the second character set.

19. A device comprising a processor for running a plurality of applications; and a keypad according to any one of claims 15 to 18, the processor being configured to operate the means for selectively illuminating the first and second light guide layers in dependence on the application being run by the processor.

20. A cover for an electronic device comprising the structure of any one of claims 1 to 14.

21. A device comprising a processor and a cover according to claim 20, the processor being configured to operate the means for selectively illuminating the first and second light guide layers.

22. The device according to claim 18 or 21, being a mobile telephone.

23. A keypad comprising a plurality of light guide layers, each comprising an embedded character set of photo luminescent transparent material and each having an associated LED for illuminating the embedded photo luminescent material; at least one light guide layer sandwiched between the plurality of light guide layers; and a key recognising structure, comprising a key recognising element in a position corresponding to the position of a character in the embedded character sets.