Abstract:
Apparatus is disclosed for illumination of a keyboard in a computing device having a display contained in a portion of the computing device which is hingeably attached to a keyboard portion, the display having a backlight. The system comprises one or more translucent elements associated with the keyboard and one or more light-conducting fibers for conducting light from the backlight of the backlit display to the one or more translucent elements associated with the keyboard. The level of illumination is varied by means of the one or more light conducting fibers transmitting light through two portions of transparent material, the two portions of transparent material have an area of contact between them which may be varied. A color adjustment mechanism is also provided.

Description:
FIELD OF THE INVENTION 
     The present invention relates to computing devices having an integral light source for a display panel and to the use of light from that integral light source for illumination of the keyboard of the computing device. More particularly, the present invention relates to the provision of a light path between the light source and the keyboard and to an intensity control and a color control for such illumination. 
     BACKGROUND OF THE INVENTION 
     A conventional portable computer can be used in many places with its in-built power source without the need for attachment to an external power source. In some of the places where a portable computer can be used, there is a low ambient light level. Examples of such environments having low ambient light levels include conference rooms during presentations, on aircraft or in cars. In areas where there is a low ambient light level, the display may be clearly seen as the display on a portable computer is typically backlit. However, the keyboard and the individual keys making up the keyboard may not be able to be seen in such conditions. 
     There have been previous attempts to provide lit keyboards including the provision of a light to illuminate the keyboard and the use of fluorescent materials applied to the keys. The provision of a separate light suffers from the disadvantage that additional power is needed for the light and so the usage time of the portable computer between recharges from the external power source is reduced. The provision of fluorescent materials on the keys requires that the materials are “charged” by being illuminated for a period of time prior to use. Since a portable computer is typically closed when not in use, the recharging cannot be readily achieved by normal ambient light. 
     PCT Patent Application WO97/04437 discloses a portable computer having a keyboard which is lit for use in low ambient light locations. Two embodiments are disclosed, one in which light from the backlight of the display panel is routed via a light pipe coupler and a backlight panel into a hollow portion of the key and one in which a portion of the light from the display panel backlight is reflected onto the top of the key making up the keyboard. The light from the backlight is coupled through a light pipe coupler, which may restrict the angle of use of the display panel with respect to the keyboard. A gate is provided to restrict or prevent light from entering the backlight panel. The light from the backlight is always white and so the key illumination will also always be white. 
     So it would be desirable to provide an improved mechanism for directing light from a display backlight to keys in a portable computer. It would also be desirable to provide an improved mechanism for controlling the intensity of lighting and the color of lighting for the keys in a portable computer. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides apparatus for illumination of a keyboard in a computing device having a display contained in a portion of the computing device which is hingeably attached to a keyboard portion, the display having a backlight, the system comprising: one or more translucent elements associated with the keyboard; and one or more light-conducting fibers for conducting light from the backlight of the backlit display to the one or more translucent elements associated with the keyboard. 
     In an embodiment the level of illumination is varied by means of the one or more light conducting fibers transmitting light through two portions of transparent material, the two portions of transparent material have an area of contact between them which may be varied. 
     In another embodiment the level of illumination is varied by means of the one or more light conducting fibers have a coupling whereby the alignment of the fibers may be adjusted, thus altering the amount of light which is transmitted across the coupling. 
     In yet another embodiment the system further comprises a color adjustment mechanism having a prism for receiving light from the one or more light-conducting fibers and for splitting the received light according to the wavelength of the received light and a coupler for collecting all or a portion of the light split by the prism and for transmitting all the collected light to one or more light-conducting fibers. 
     Preferably, the prism is adapted to rotate in a cavity. 
     Further preferably, the internal surface of the cavity has at least a portion coated with a light reflecting material. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a portable computer according to the present invention; 
         FIG. 2  is a block diagram of the portable computer of  FIG. 1 ; 
         FIG. 3  is a side cross-section of apparatus for lighting the keyboard of the personal computer of  FIGS. 1 and 2  according to the present invention; 
         FIG. 4  shows a cross-section view of a key suitable for use in the present invention and forming part of the keyboard of the personal computer of  FIGS. 1 and 2 ; 
         FIG. 5  shows a first embodiment of an adjustment mechanism to adjust the amount of light which reaches the keyboard of the personal computer of  FIGS. 1 and 2 ; 
         FIG. 6  shows a second embodiment of an adjustment mechanism to adjust the amount of light which reaches the keyboard of the personal computer of  FIGS. 1 and 2 ; and 
         FIG. 7  shows a mechanism for controlling the color of light which is used to illuminate the keyboard of the personal computer of FIGS.  1  and  2 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a portable electronic device such as a laptop or notebook computer  100  having a base  102  and a cover  104 . The base  102  and cover  104  are rotatably connected by a hinge  106 . 
     The computer has a keyboard  108  having a number of keys  110 , each key generally having one or more characters applied to it. The computer also has a display  112  which is typically a backlit liquid crystal display. A control  114  is typically provided to adjust the contrast of the display. Keys  110  on the keyboard are pressed in order to generate and manipulate text and graphic images on the display  112 . 
       FIG. 2  shows a prior art portable computer  100 , comprising a keyboard  108 , a pointing device  213  and a display  112  having a backlight  248 , depicted in block diagram form. The portable computer  100  includes a system bus or plurality of system buses  221  to which various components are coupled and by which communication between the various components is accomplished. The microprocessor  222  is connected to the system bus  221  and is supported by read only memory (ROM)  223  and random access memory (RAM)  224  also connected to system bus  221 . In many typical computers the microprocessors including the 386, 486 or Pentium microprocessors (Intel and Pentium are trademarks of Intel Corp.). However, other microprocessors including, but not limited to, Motorola&#39;s family of microprocessors such as the 68000, 68020 or the 68030 microprocessors and various Reduced Instruction Set Computer (RISC) microprocessors such as the PowerPC chip manufactured by IBM, or other microprocessors from Hewlett Packard, Sun, Motorola and others may be used in the specific computer. 
     The ROM  223  contains among other code the Basic Input-Output System (BIOS) which controls basic hardware operations such as the interaction between the CPU and the disk drives and the keyboard. The RAM  224  is the main memory into which the operating system and application programs are loaded. The memory management chip  225  is connected to the system bus  221  and controls direct memory access operations including passing data between the RAM  224  and hard disk drive  226  and floppy disk drive  227 . The CD ROM  232  also coupled to the system  221  is used to store a large amount of data, e.g. a multimedia program or presentation. CD ROM  232  may be an external CD ROM connected through an adapter card or it may be an internal CD ROM having direct connection to the motherboard. 
     Also connected to this system bus  221  are various I/O controllers: the keyboard controller  228 , the pointing device controller  229 , the video controller  230  and the audio controller  231 . As might be expected, the keyboard controller  228  provides the hardware interface for the keyboard  108 , the pointing device controller  229  provides the hardware interface for pointing device  213 , the video controller  230  is the hardware interface for the display  112 , and the audio controller  231  is the hardware interface for the speakers  215   a  and  215   b . The power management controller  234  is connected to the system bus and receives power from a battery or from an external power supply which converts the ac voltage from a building supply to a predetermined lower dc voltage used to operate the portable computer  100 . An I/O controller  240  such as a Token Ring adapter card enables communication over a network  246  to other similarly configured data processor systems. These I/O controllers may be located on the motherboard within the portable computer or they may be located on adapter cards or cartridges which plug into the motherboard. The adapter cards may communicate with the motherboard using a PCI interface, an ISA or EISA interface or other interfaces. 
       FIG. 3  shows a side cross-section of apparatus for lighting the keyboard according to the present invention. One or more fiber-optic cables  302  transmit light from a display backlight  248  through the hinge  106  from the cover  104  to the base  102 . The fiber-optic cables  302  are typically manufactured of a plastic material, which is flexible and does not suffer from fatigue problems. The fiber-optic cable has a minimum bend radius and the connection through the hinge  106  from the cover  104  to the base  102  needs to ensure that this minimum bend radius is not breached. Provided this minimum bend radius is not breached, then there will be insignificant attenuation of the light by the bending of the fiber. The display backlight  248  typically provides around 5,000 Cd/m 2  of illumination to the display  112  and so the “leakage” of a small proportion of the light from the display backlight  248  to the fiber-optic cables  302  will not significantly affect the level of display illumination. The backlight  248  is typically provided with a reflector  304  to improve its efficiency. 
       FIG. 4  shows a cross-section view of a key  110  suitable for use in the present invention. The key includes a main portion  406  and a portion  402  containing the lettering, numeral, symbol or other marking on the keytop. The portion  402  and the main portion may be separate pieces attached during a manufacturing process or may be integral with each other. A transparent or translucent optical conducting portion  404  is provided to conduct light from the fiber  302  to the portion  402 . Portion  402  may be translucent over the whole of its area or it may be translucent or transparent only in the area occupied by the letter, numeral, symbol or other marking. Other means of lighting individual keys may be used in the present invention. 
     As has been discussed above, the present invention is aimed at improving the usability of a portable computer in environments having low ambient light levels. In some of these environments the ambient light is insufficient to be able to see keys on the keyboard, but only a small amount of additional lighting is needed or alternatively a large amount of additional lighting may be needed as the eyes of the user are adjusted to the level of ambient lighting. In other environments the ambient light may be very low or near to darkness, so the keys may need to be fully lit in order to be seen or they may only need a small amount of additional lighting as the eyes of the user are adjusted to the darkness. 
       FIG. 5  shows a first embodiment of an adjustment mechanism to adjust the amount of light which reaches the keyboard. This mechanism operates by aligning, misaligning or partially aligning the fiber-optic cables so as to implement an intensity control. Portions  502  and  504  are made of material which is substantially optically transparent. Light enters the adjustment mechanism at face  510 . Light leaves the adjustment mechanism at face  512 . Portion  504  is arranged to slide along portion  502  in the direction shown by arrow  506 . Typically, the movement of portion  504  may be achieved by means of a user control. A resilient means may apply pressure to either or both of surfaces  510 ,  512 , so as to encourage portions  504  and  502  in a direction opposite to that of arrow  506 . A user control force may then be applied in direction  506 . 
       FIG. 6  shows a second embodiment of the invention in which two optical fibers  602 ,  604  are merely positioned so that in one position they are aligned and in other positions along the axis of arrow  606  they are partially or entirely misaligned. 
     It is well known that certain colors of light are more suitable if it is desired to retain “night vision”, that is the ability to see dim points of light in the distance outside. Looking at brightly lit objects or at objects lit with white light can cause the eye to adjust for the brightly lit object and take some time to re-adjust so as to be able to see the less bright objects outside. Typically a red color is used, for example, on board ships. Similarly, it may be desired that a certain color of light is used for maximum legibility. In photographic darkrooms, it may be desirable to use a particular color of light in order to avoid exposure of undeveloped photographic films. 
       FIG. 7  shows a mechanism for controlling the color of light which is used to illuminate the keyboard. Light enters the mechanism  700  in the direction of arrow  708 . The light strikes a prism  704  and is split into various colors leaving the prism at face  712 . Coupler  706  receives all or a portion of the various colors of light and directs the received light to an optical fiber  710 . The fiber  710  then supplies the light to the keyboard for the purpose of illuminating the keyboard. Prism  704  may be rotated by a user control so as to provide white light illumination when substantially all of the light split by the prism is collected by coupler  706  or it may provide light of various colors according to whether coupler  706  is adjusted so as to receive those particular colors of light. The prism is located in a cavity  702  which may optionally have a coating  712  for the reflection of light so as to improve the efficiency of the color selection mechanism. In order to select the color of light, relative rotation of portions  706  and  704  is required, so either or both portions may be rotatable. 
     The display backlight has strong primary colors in its light spectrum as it needs to be able to display white on the display and so a wide range of colors are available for illumination of the keyboard. 
     While the preferred embodiments have been described here in detail, it will be clear to those skilled in the art that many variants are possible without departing from the spirit and scope of the present invention. In particular, the preferred embodiments have been described in terms of illuminating a keyboard, whereas the present invention may also be advantageously applied to illuminating other portions of the computer, such as for example, a pointing device, or even a manufacturer&#39;s logotype.