Abstract:
A portable electronic apparatus ( 100 ) includes a ambient light sensor ( 112 ) for measuring ambient light levels, a display ( 106 ) for displaying text and icons, on a background, and a processor ( 304 ) coupled to the display ( 106 ), and the light sensor for causing indicia to be displayed on the display ( 106 ), and adjusting the color and/or size characteristics of the indicia and/or background according to the ambient light level measured through the ambient light sensor ( 112 )

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates in general to displays. More particularly, the present invention relates to displays for portable devices.  
         [0003]     2. Description of Related Art  
         [0004]     Portable electronic devices that include displays such as cellular telephones, portable digital assistants (PDA), and portable game consoles are widely used. Recently, devices having larger and higher resolution displays that are capable of displaying images with higher color fidelity have been introduced. Such displays generally allow for improved user interfaces.  
         [0005]     Such portable electronic device, are carried with their users indoors and outdoors, and operated under a wide variety of ambient light conditions. In places where the ambient light level is low, the information displayed on the display of a portable device, particular if it includes small high resolution icons, or text, may be difficult to read. One approach to increasing the readability of displays under low light conditions is to provide a display backlight. However, under intermediate light level conditions, in which the luminance of the backlight is comparable to the luminance of ambient reflected light, the effect of the backlight may be limited. Moreover, the battery drain associated with operating the backlight reduces battery life.  
         [0006]     It would be desirable to increase the usability of portable devices that include displays under varied ambient light conditions. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0007]     The present invention will be described by way of exemplary embodiments, but not limitations, illustrated in the accompanying drawings in which like references denote similar elements, and in which:  
         [0008]      FIG. 1  is a front view of a first embodiment of a wireless communication device;  
         [0009]      FIG. 2  is a cross sectional side view of the wireless communication device shown in  FIG. 1 ;  
         [0010]      FIG. 3  is a functional block diagram of the wireless communication device shown in  FIGS. 1-2 ;  
         [0011]      FIG. 4  is a flow chart of a method of operating the wireless communication device shown in  FIGS. 1-3 ;  
         [0012]      FIG. 5  is a flow chart of a method of operating the wireless communication device shown in  FIGS. 1-3 ;  
         [0013]      FIG. 6  is a depiction of a display of the wireless communication device shown in  FIGS. 1-3  in an alternate state; and  
         [0014]      FIG. 7  is a flow chart of a method of operating the wireless communication device shown in  FIGS. 1-3  according to another alternate embodiment. 
     
    
     DETAILED DESCRIPTION  
       [0015]     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting; but rather, to provide an understandable description of the invention.  
         [0016]     The terms a or an, as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and/or having, as used herein, are defined as comprising (i.e., open language). The term coupled, as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically.  
         [0017]     Although the invention is described below with reference to a wireless communication device, the invention is applicable to other portable electronic devices that include displays as well. Examples of wireless communication devices to which the invention is applicable include cellular telephones, and two-way radios.  
         [0018]      FIG. 1  is a front view of a wireless communication device  100  according to a first embodiment and  FIG. 2  is a cross sectional side view of the wireless communication device shown in  FIG. 1 . The wireless communication device  100  comprises a housing  102  that mechanically couples and supports a plurality of components including an antenna  104 , a keypad  108 , and a battery  202 . The housing  102  encloses a circuit board  204  that supports and electrically interconnects the keypad  108 , a plurality of electrical circuit components  206  that are part of one or more electrical circuits of the wireless communication device  100 , a display  106 , a microphone  208 , a speaker  210 , and an incoming communication alert  212 .  
         [0019]     The housing  102  also includes an ambient light sensor window  110 . An ambient light sensor  112  is connected to, and supported on the circuit board  204  in alignment with the light sensor window  110 . The light sensor  112  is used to measure ambient light levels, and the display  106  is operated according to the ambient light level in order to optimize readability, as described below in more detail.  
         [0020]      FIG. 3  is a functional block diagram of the wireless communication device  100  shown in  FIGS. 1-2 . As shown in  FIG. 3 , the wireless communication device  100  comprises a transceiver module  302 , a processor  304 , a first analog to digital converter (A/D)  306 , a key input decoder  308 , a work space memory  310 , a program memory  312 , a display driver  314 , an alert driver  316 , a digital to analog converter (D/A)  318 , and second A/D  320  coupled together through a digital signal bus  322 .  
         [0021]     Those skilled in the are will recognize that the processor can be implemented using discrete logic circuitry, programmable logic unit, a microprocessor, a mcirocontroller, a digital signal processor or the like.  
         [0022]     The transceiver module  302  is coupled to the antenna  104 . Carrier signals that are modulated with data, e.g., audio data, pass between the antenna  104 , and the transceiver  302 .  
         [0023]     The microphone  208  is coupled to the first A/D  306 . Audio, including spoken words, is input through the microphone  208  and converted to digital format by the first A/D  306 .  
         [0024]     The keypad  108  is coupled to the key input decoder  308 . The key input decoder  308  serves to identify depressed keys, and provide information identifying each depressed key to the processor  304 .  
         [0025]     The display driver  314  is coupled to the display  106 . The alert driver  316  is coupled to the alert  212 . The D/A  318  is coupled to the speaker  210 . The D/A  312  converts decoded digital audio to analog signals and drives the speaker  210 .  
         [0026]     The ambient light sensor  112  is coupled to the second A/D  320 , and through the second A/D to the processor  304 . Thus, the processor  304  is able to obtain ambient light readings, and as described below the execution of programs executed by the processor  304  is conditioned on such readings.  
         [0027]     The program memory  312  is used to store programs that control the first wireless communication device  100 . The programs stored in the program memory  316  are executed by the processor  304 . The program memory also stores fonts in one or more sizes, and icons in one or more sizes.  
         [0028]     The transceiver module  302 , the processor  304 , the first A/D  306 , the key input decoder  308 , the work space memory  310 , the program memory  312 , the display driver  314 , the alert driver  316 , the D/A  318 , the second A/D  320 , and the digital signal bus  322 , are embodied in electrical circuit components  206  shown in  FIG. 2 .  
         [0029]      FIG. 4  is a flow chart of a method of operating the wireless communication device  100  shown in  FIGS. 1-3  according to the first embodiment of the invention. A program embodying the method shown in  FIG. 4  is stored in the program memory  312 , and executed by the processor  304 . In block  402  the ambient light level (A.L.L.) is read, e.g., by the processor  208  through the signal bus  322 , and second A/D  320  from the ambient light sensor  112 . Block  404  is a decision block the outcome of which depends on whether the A.L.L exceeds a first threshold value (labeled THRESH — 1 in  FIG. 4 ). If so then in block  406  a font size variable that is to be used in displaying characters on the display  106  is set to a first font size, and in block  408  a scale factor, that determines the size of graphics, e.g., icons displayed on the display  106  is set to a first value. The first font size is the smallest of three font sizes that can be set by the method shown in  FIG. 4 . Similarly, the first value is the smallest of three values of the scale factor. Thereafter, in block  410  text is displayed on the display  106  according to the font size variable value, and in block  412  graphics e.g., icons are displayed on the display at a scale determined by the value of the scale factor.  
         [0030]     If on the other hand it is determined in decision block  404  that the A.L.L does not exceed the first threshold, then the method continues with decision block  414 , the outcome of which depends on whether the A.L.L exceeds a second threshold (labeled THRESH — 2 in  FIG. 4 ). The second threshold is lower than the first threshold. If it is determined in decision block  414  that the A.L.L. exceeds the second threshold, i.e., if the A.L.L. is between the first threshold, and the second threshold, then in block  416  the font size is set to a second font size, and in block  418 , the scale factor is set to a second value. The second font size is a medium font size among the three font sizes that are to be used in displaying characters on the display  106 , and the second value is an intermediate value among three values of scale factor that can be set by the method shown in  FIG. 4 . Thereafter the method continues to blocks  410 , and  412 .  
         [0031]     If on the other hand it is determined in decision block  414  that the A.L.L. does not exceed the second threshold, then in block  420  the font size variable is set a third (largest) value, and in block  422  the scale factor is set to a third (largest) value. Thereafter the method continues to blocks  410 ,  412 .  
         [0032]     Although the method shown in  FIG. 4  can be implemented using a variety of software platforms, as an example, in a Connected Limited Device Configuration (CLDC), Mobile Information Device Profile (MIDP), Java 2 Micro Edition (J2ME) environment, the font size parameter of the setFont method can be used to set different font sizes. With regard to graphics, different size versions of graphic icons can be stored in memory and selected per  FIG. 4 , or the graphics can be scaled as needed.  
         [0033]      FIG. 4  is an exemplary flow chart of a method according to a first embodiment of the invention. The invention should not be construed as limited to the particular exemplary logic flow illustrated in  FIG. 4 , as the logic flow, is dependent on the semantics of the programming language in which the method is implemented and the programming style of programmers implementing the method.  
         [0034]     The method shown in  FIG. 4  determines which of three ranges the A.L.L. falls. The first range is an open range having the first threshold as a lower bound, the second range is bounded by the first threshold, as the upper bound, and the second threshold as the lower bound. The third range has the second threshold as an upper bound. The method shown in  FIG. 4  selects one of three font sizes, and one of three graphic, e.g., icon scaling factors based on the ambient light level. As the ambient light level falls, two successively larger font sizes, and two successively larger graphic, e.g., icon, sizes are chosen in order to facilitate reading the display  106 , and reduce eye strain.  
         [0035]      FIG. 5  is a flow chart of a method of operating the wireless communication device  100  shown in  FIGS. 1-3  according to a second embodiment of the invention. A program embodying the method shown in  FIG. 5  can be stored in the program memory  312 , and executed by the processor  304 . In block  502 , the A.L.L. is read, e.g., by the processor  208  through the signal bus  322 , and second A/D  320  from the ambient light sensor  112 . Thereafter, in decision block  504 , the A.L.L. is compared to a threshold. If it is determined in block that the A.L.L. exceeds the threshold, the method continues with block  506  in which dark text and graphics are displayed on a light background. If on the other hand it is determined in block  504  that the A.L.L. does not exceed the threshold, then in block  508  light text and graphics are displayed on a dark background.  
         [0036]     Thus, under low light conditions the method shown in  FIG. 5  displays light text and graphics on a dark background in order to improve readability, and reduce eye strain.  
         [0037]      FIG. 6  is a depiction of the display  106  of the wireless communication device  100  shown in  FIGS. 1-3  in an alternate state. As shown in  FIG. 6  the display  106  is displaying a light color phone number, and a light colored signal strength indicator icon on a dark colored background. This is in contrast to the state shown in  FIG. 1  in which the phone number and signal strength indicator appear in a dark color on a light background.  
         [0038]      FIG. 7  is a flow chart of a method of operating the wireless communication device shown in  FIGS. 1-3  according to a third embodiment of the invention. A program embodying the method shown in  FIG. 7  can be stored in the program memory  312 , and executed by the processor  304 . In block  702  the ambient light level (A.L.L.) is read, e.g., by the processor  208  through the signal bus  322 , and second A/D  320  from the ambient light sensor  112 . Block  704  is a decision block the outcome of which depends on whether the A.L.L exceeds a first threshold value (labeled THRESH — 1 in  FIG. 7 ). If so then in block  706  indicia color variable that determines the color of one or more indicia (e.g., icons, text) displayed on the display  106  is set to a first predetermined color, and in block  708  a background color variable, that determines the color of a background displayed on the display  106  is set to a second predetermine value. The first and second predetermined values can be chosen by experimenting with human subjects to determine colors that work well under high ambient light conditions. Thereafter, in block  710  a background is displayed on the display  106  according to the background color variable value, and in block  712  indicia e.g., icons, and text are displayed on the display in a color determined by the value of the indicia color variable.  
         [0039]     If on the other hand it is determined in decision block  704  that the A.L.L does not exceed the first threshold, then the method continues with decision block  714 , the outcome of which depends on whether the A.L.L exceeds a second threshold (labeled THRESH — 2 in  FIG. 7 ). The second threshold is lower than the first threshold. If it is determined in decision block  714  that the A.L.L. exceeds the second threshold, i.e., if the A.L.L. is between the first threshold, and the second threshold, then in block  716  the indicia color variable is set to a third predetermined color, and in block  718 , the background color variable is set to a fourth predetermined color. The third and fourth predetermined color values can be chosen by experimenting with human subjects to determine a colors that work well under intermediate ambient light conditions, e.g., ambient light conditions obtaining at dusk. Thereafter the method continues to blocks  710 , and  712 .  
         [0040]     If on the other hand it is determined in decision block  714  that the A.L.L. does not exceed the second threshold, then in block  720  the indicia color variable is set a fifth predetermine color value, and in block  722  the background color variable is set to a sixth predetermined color value. Thereafter the method continues to blocks  710 ,  712 . The fifth and sixth predetermined color values can be chosen by experimenting with human subjects to determine colors that work well under at low ambient light levels.  
         [0041]      FIG. 7  shows is an exemplary flow chart of a method according to a first embodiment of the invention. The invention should not be construed as limited to the particular exemplary logic flow illustrated in  FIG. 7 , as the logic flow, is dependent on the semantics of the programming language in which the method is implemented and the programming style of programmers implementing the method.  
         [0042]     The method shown in  FIG. 7  determines which of three ranges the A.L.L. falls. The first range is an open range having the first threshold as a lower bound, the second range is bounded by the first threshold, as the upper bound, and the second threshold as the lower bound. The third range has the second threshold as an upper bound.  
         [0043]     Although as shown in  FIG. 7 , the A.L.L. is compared to two thresholds, alternatively the A.L.L. is compared to more than two thresholds, in order to determine which of more than three ranges, the A.L.L is in, and for each range, a particular background color, and/or indicia color is set.  
         [0044]     The method shown in  FIG. 7  selects background, and indicia colors based on the ambient light level. Depending on the light level one of three predetermined indicia colors, and one of three predetermined background colors is displayed on the display.  
         [0045]     As an example, in implementing the methods shown in  FIGS. 5,7  in a Java environment such as mentioned above, the setColor methods of the Canvas class, and the Font class can be used to set the color of the background and fonts.  
         [0046]     It is to be expected that optimum colors for the background, and indicia will vary from one display to another based on the characteristic of the display, such as whether it is reflective, or emissive, brightness, color range, however suitable values for the first through sixth predetermined color values can be determined through routine experimentation, with human subjects and a particular display, aimed at determining which colors lead to the best readability, least eye strain, and most pleasing image under different ambient light conditions. In as much as human perception is involved in the determination of color values, there is a degree of subjectivity in such a determination of predetermined color values.  
         [0047]     While the preferred and other embodiments of the invention have been illustrated and described, it will be clear that the invention is not so limited. Numerous modifications, changes, variations, substitutions, and equivalents will occur to those of ordinary skill in the art without departing from the spirit and scope of the present invention as defined by the following claims.