In order to allow the use of such an electronic appliance in a sparsely illuminated or dark environment, the display device is usually provided with background illumination.

Alternatively, the display device is provided with several miniature light bulbs mounted at the edges of the display device illuminating the entire display device. The illumination of the display device is considered an significant factor of the user friendliness of electronic appliances such a mobile handheld telephones. Therefore, it is important to provide this functionality. On the other hand however, the electrical power for the operation of mobile handheld telephones and other electronic appliances is supplied by primary or secondary batteries having a restricted capacity. This battery capacity is mainly used to provide an extended operation time of the appliance (longer talk time and standby time). Nevertheless, additional functions like the illumination of the display device are considered to be an indispensable, mandatory features in userfriendly handheld telephones or similar devices.

In view of the above, the object underlying the present invention is to maintain or even increase the number of functions related to userfriendliness, especially the illumination of the display device, while the power consumption of the electronic appliance (talk time and

standby time in the context of a mobile handheld telephone) should be affected to the least degree possible.

To achieve this, the invention teaches to provide a mobile electronic appliance such as a mobile handheld telephone comprising a display device such as a liquid crystal display (LCD) for displaying alphanumerical or graphical information for a user of said mobile electronic appliance, said display device being provided with at least one illumination device, and a control circuit for providing drive signals for said display device and said at least one illumination device, wherein said display device is divided into a plurality of display areas, at least one of said display areas being provided with a illumination device illuminating said display area in response to a drive signal from said control circuit.

The invention has realized the drawback of prior art mobile electronic appliances where the backgrund illumination or the miniature light bulbs are provided to illuminate the entire surface area of the display device irrespective of whether or not information is displayed on the display, and in case information is displayed on the display, the illumination is not taking into account the location of the displayed information on the display device.

According to the invention, only those areas of the display device are illuminated in which alphanumerical or graphical information for the user of said mobile electronic appliance is displayed. This has the advantage of the power consumption being reduced considerably. Moreover, the appearance of the displayed information is even more userfriendly, as the displayed alphanumerical or graphical information can be "highlighted"in accordance to its relevance or importance to the user. Hence, the invention also provides an improved way of presenting alphanumerical or graphical information to the

user and an improved display device'to carry out this presentation.

In a presently preferred embodiment of the invention, the or each illumination device is mounted at the side of the display device which is not visible to a user. Alternatively, it is also possible to provide the or each illumination device at the edge of the display device and to have segments of light conveying material provided on the surface of the display device visible to the user that feeds the light to the respective area of the display device which is to be illuminated.

Preferably, the or each illumination device is a light emitting diode (LED) or an array of light emitting diodes. It is also possible to use miniature light bulbs to illuminate the display device. However, they have a relatively higher power consumption and are less reliable than LEDs.

According to the invention, each illumination device or groups of illumination devices are only activated by drive signals from said control circuit, when at the same the display device is activated to display alphanumerical or graphical information for a user in the display area the respective illumination device or group of illumination devices is associated with. This ascertains the minimum consuption of power used to illuminate the display device while at the same time drawing the attention of the user the those fields or areas of the display device which presently contain information of importance or relevance for the user.

In order to more evenly distribute light emitted by said illumination device or said groups of illumination devices before said light passes through said display device, a scattering disk is provided between each illumination device or groups of illumination devices and said display device.

At least one of said illumination devices or groups of illumination devices are arranged to provide visible light of different wavelengthes responsive to drive signals from said control circuit. This allows for the possibility to change the background color of specific areas of the display device.

It is also possible to assign certain meanings to certain colours (e. g. the display field of a mobile telephone where the signal strength indicator changes its background light colour from red to yellow to green with an increasing signal strength, or the battery status indicator changes its background light colour from green to yellow to red (and blinking red) with a decreasing battery charging status.

Further features, advantages and possible modifications from the above-described invention will become readily appearent to a person skilled in the art upon studying the subsequent description of a presently preferred embodiment with reference to the drawing.

Fig. 1 shows a schematic three-dimensional drawing of a display device of an electronic appliance, such as a handheld mobile telephone including the invention.

A display device 10 such as a liquid crystal display (LCD) is provided for displaying alphanumerical or graphical information for a user of the mobile electronic appliance. In the present embodiment, the electronic appliance is a handheld mobile telephone. Hence, the display device 10 has a field or area 12 for alphanumerical or graphical information and a number of additional fields containing pictograms (14 = signal strength indicator; 16 = battery charging status; 18 = Roaming; Indicator 20 = Mail received etc.). The display device 10 is provided with illumination devices 12a, 14a, 16a, 18a, 20a etc. Each of said illumination devices is associated with the respective field 12 to 20 in order to allow for illumination of the respective field or area 12 to 20. The illumination devices 12a to 20a are connected to a

control circuit 24 for providing drive signals for the respective illumination devices.

In the present embodiment, the illumination devices are light emitting diodes. In order to illuminate larger fields or areas like the field or area 12 for alphanumerical or graphical information, an array of light emitting diodes having a number of light emitting diodes mounted in a plane under the LCD-display and which are spatially separated from each other (not shown in detail) can be utilised. In one embodiment of the invention, each LED of such an array of LEDs is provided to correspond to a different position of an alphanumerical display field having one or more rows/columns. The LED under a position of the alphanumerical display field is activated only if an alphanumerical character is displayed in the respective position field. If the user enters alphanumerical data via a key pool (not shown), it is also possible to illuminate the next position of the alphanumerical display, where the next character to be entered will be displayed. Thus, the user has a clear indication of the important portions of the display field. As shown in relation with field or area 20, it is also possible to use two or more LEDs to illuminate the respective field of the display device corresponding to these LEDs.

In other words, the illumination device or groups of illumination devices associated with the fields in the display device 10 are activated by drive signals from the LED control circuit 24 when at the same the display device 10 is activated by a LCD control circuit 26 to display alphanumerical or graphical information for a user in the display area. The LED control circuit 24 is activated by the LCD control circuit 26 via lines 32 to drive the respective LEDs which correspond to the fileds of the LCD display.

Between the illumination devices or groups of illumination devices and the display device, a scattering disk 30 is

provided to more evenly distribute the emitted light. This allows also to use relatively small LEDs having a very low power consumption.

In order to increase the awareness of the user to critical or important information, LEDs capable of generating light having different colours can be utilised. One example is the battery status indicator field 16 which is illuminated with green light when the battery is full, with yellow light when the battery is half empty and with red when the battery is 90% empty and with red blinking light when the battery is 95% empty. Another example is the Roaming indicator. Here, the colour of the light illuminating the field can change according to the prizes for a call the various service providers in the country where the mobile telephone uses vary.

As is appearent from the above, a reduced power consumption is achieved and the userfriendliness of the appliance is improved by the invention.