Patent Publication Number: US-9852672-B2

Title: Method and apparatus for controlling brightness in a portable terminal

Description:
PRIORITY 
     This application claims the benefit under 35 U.S.C. §119(a) of a Korean patent application filed on Mar. 21, 2011 in the Korean Intellectual Property Office and assigned Serial No. 10-2011-0025019, the entire disclosure of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method and apparatus for controlling brightness in a portable terminal. More particularly, the present invention relates to a method and apparatus for controlling brightness in a portable terminal according to a change of at least one of temperature and illuminance, thereby preventing or reducing a drop of the lifespan of a display unit by controlling the brightness of the display unit. 
     2. Description of the Related Art 
     Because of recent rapid technical advances in information and communication technologies, semiconductor technologies, and the like, portable terminals have been widely distributed and used. Such portable terminals generally include a display unit such as a Liquid Crystal Display (LCD), an Organic Light Emitting Display, or the like. 
     The properties of the display unit tend to change over time. For example, the properties such as brightness, contrast ratio, and the like deteriorate over time. That is, the properties of the display unit such as brightness, contrast ratio, and the like are gradually deteriorated. Consequently, such a display unit cannot be used after a certain amount of time (e.g., after a lifetime of the display unit). The deterioration of the properties of the display unit is affected by temperature and brightness. For example, the lifespan of the display unit is reduced at high temperatures, and the lifespan of the display unit is more quickly reduced as the brightness increases. However, conventional portable terminals are generally maintain the brightness of the display unit at a brightness which is set by users regardless of whether there is a temperature change. In addition, conventional portable terminals generally maintain the brightness of the display unit at a brightness which is automatically set regardless of whether there is a temperature change. As such, the lifespan of the display unit of such portable terminals according to the related art is quickly reduced at high temperatures. 
     The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention. 
     SUMMARY OF THE INVENTION 
     Aspects of the present invention are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a method and apparatus for controlling brightness in a portable terminal, which can appropriately control the brightness of the display unit according to a change of at least one of temperature and illuminance. 
     Another aspect of the present invention is to provide a method and apparatus for controlling the brightness of a portable terminal which can increase the lifespan of a display unit by limiting the brightness of the display unit so as not to exceed the maximum brightness in response to a temperature change with reference to a brightness table in which the maximum brightness, which can be set according to the temperature and illuminance, is mapped and stored. 
     Another aspect of the present invention is to provide a method and apparatus for controlling brightness in a portable terminal, which informs a user of a limitation of brightness in order to prevent the decrease of the lifespan of the display unit. 
     In accordance with an aspect of the present invention, a method for controlling brightness in a portable terminal is provided. The method includes measuring temperature according to a preset period, extracting a brightness value mapped to the measured temperature from a stored brightness table, and changing a brightness of the portable terminal to correspond to the extracted brightness. 
     In accordance with another aspect of the present invention, an apparatus for controlling brightness in a portable terminal is provided. The apparatus includes a display unit, a temperature sensor for measuring temperature, a storage unit for storing a brightness table which stores a mapping of temperature and brightness, and a controller that extracts a brightness value mapped to the measured temperature from the brightness table, and that changes the brightness of the display unit to correspond to the extracted brightness value. 
     In accordance with another aspect of the present invention, a non-transitory computer-readable storage medium of a portable terminal is provided. The non-transitory computer-readable storage medium stores a program for controlling brightness in a portable terminal. The program includes instructions to cause a computer to measure a temperature according to a preset period, extract a brightness value mapped to the measured temperature from a stored brightness table, and change a brightness of the portable terminal to correspond to the extracted brightness value. 
     Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a block diagram schematically illustrating a configuration of a portable terminal according to an exemplary embodiment of the present invention; 
         FIG. 2  is a flowchart illustrating a method of controlling brightness of a portable terminal at a manual mode according to an exemplary embodiment of the present invention; 
         FIG. 3  is a flowchart illustrating a method of controlling brightness of a portable terminal at an automatic mode according to an exemplary embodiment of the present invention; 
         FIG. 4  is a flowchart illustrating a method of setting brightness of a portable terminal according to an exemplary embodiment of the present invention; 
         FIG. 5  is a series of screen shots illustrating a method of setting brightness of a portable terminal according to an exemplary embodiment of the present invention; and 
         FIG. 6  is a flowchart illustrating a method of operating brightness setting of a portable terminal according to an exemplary embodiment of the present invention. 
     
    
    
     Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness. 
     The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention is provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
     It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces. 
       FIG. 1  is a block diagram schematically illustrating a configuration of a portable terminal according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 1 , a portable terminal  100  according to an exemplary embodiment of the present invention includes an illuminance sensor  180 , a temperature sensor  170 , an audio-processing unit  160 , an input unit  140 , a display unit  130 , a storage unit  120 , and a controller  110 . As an example, the portable terminal  100  having such a configuration may appropriately adjust brightness of the display unit  130  according to a temperature change. The temperature change may be measured through a temperature sensor  170 . According to an exemplary embodiment of the present invention, the portable terminal  100  may decrease the brightness of the display unit  130  if temperature increases. For example, because the lifespan of the display unit  130  quickly decreases as temperature increases, and/or as the brightness gets higher, the portable terminal may monitor the temperature of the display unit  130 . In other words, the portable terminal  100  offsets a decrease of the lifespan due to the temperature increase by an increase of the lifespan due to the decrease of the brightness. Accordingly, as the temperature increases, the portable terminal  100  offsets the decreased of the lifespan caused by the temperature increase with a corresponding increase in the lifespan caused by decreasing the brightness of the display unit  130 . As such, the portable terminal  100  according to exemplary embodiments of the present invention shows an effect of improving the lifespan of the display unit  130  relative to the portable terminals of the related art. Hereinafter, each component of the portable terminal  100  will be explained in detail. 
     The audio processing unit  160  may be formed as an acoustic component. The audio processing unit  160  transmits and receives audio signals, and encodes and decodes the audio signals. For example, the audio processing unit  160  may include a CODEC and an audio amplifier. The audio processing unit  160  is connected to a Microphone (MIC) and a Speaker (SPK). The audio processing unit  160  converts analog voice signals inputted from the Microphone (MIC) into digital voice signals, generates corresponding data for the digital voice signals, and transmits the data to the controller  110 . Further, the audio processing unit  160  converts digital voice signals inputted from the controller  110  into analog voice signals, and outputs the analog voice signals through the Speaker (SPK). Further, the audio processing unit  160  may output various audio signals generated in the portable terminal  100  through the Speaker (SPK). For example, the audio processing unit  160  can output audio signals according to an audio file (e.g. MP3 file) replay, a moving picture file replay, and the like through the speaker. In particular, the audio processing unit  160  according to exemplary embodiments of the present invention can output an alarm which informs of properties associated with a brightness of the display unit  130 . For example, the audio processing unit  160  may output an alarm indicating a limitation of the brightness of the display unit  130 . 
     The illuminance sensor  180  may sense external illuminance (brightness), and transmit a light sensing signal corresponding to the sensed external illuminance to the controller  110 . The illuminance sensor  180  may be an optical sensor including a light sensor device such as a transistor, a photo diode, or the like. A detailed explanation of the method of automatically controlling brightness of the display unit  130  through the illuminance sensor  180  will be omitted because the method may be apparent to those skilled in the art. 
     The temperature sensor  170  measures temperature using devices having different resistance values according to, or as a function of, temperature. As an example, a metal wire, a semiconductor, or the like may have different resistance values according to temperature. That is, the temperature sensor  170  may be any sensor which can measure temperature. For example, the temperature  170  may be a thermister. The thermister is a kind of a temperature sensor, and has properties whose resistance value is changed according to temperature. Using such properties, if the thermister and resistance are serially connected, and if certain voltage is applied, then the voltage between the thermister and resistance is also changed due to a change of the resistance value of the thermister according to a temperature change. That is, the controller  110  can receive a transmitted signal corresponding to the voltage value between the thermister and resistance, and measure temperature. 
     The input unit  140  may include input keys and function keys for receiving a user input. For example, the input unit  140  may include input keys and function keys for receiving an input of numbers or various sets of letter information, setting various functions, and controlling functions of the portable terminal  100 . For example, the input unit  140  may include a calling key for requesting a voice call, a video call request key for requesting a video call, a termination key for requesting termination of a voice call or a video call, a volume key for adjusting output volume of an audio signal, a direction key, and the like. In particular, the input unit  140  according to exemplary embodiments of the present invention may transmit to the controller  110  signals related with automatic mode setting which automatically adjusts brightness of the display unit  130  using at least one of a temperature sensor  170  and an illuminance sensor  180 . Such an input unit  140  may be formed by one or a combination of input means such as a touch pad, a touch screen, a button-type key pad, a joystick, a wheel key, and the like. 
     The display unit  130  displays information inputted by user or information to be provided to user as well as various menus of the portable terminal  100 . For example, the display unit  130  may provide various screens according to a user of the portable terminal  100 , such as an idle screen, a message writing screen, a calling screen, and the like. In particular, the display unit  130  according to exemplary embodiments of the present invention can display a brightness setting menu screen. As an example, the display unit  130  can output an alarm message that informs a user of brightness properties of the display unit  130 . For example, the display unit  130  may output an alarm message that informs of limitation of brightness of the display unit  130 . The display unit  130  may inform the user of the brightness properties (e.g., the limitations of brightness of the display unit  130 ) in the form of a pop-up window, or in the form of an output of an alarm icon in the indicator area. The detailed explanation thereof will be explained later with reference to  FIGS. 4 and 5 . The display unit  130  can be formed as a Liquid Crystal Display (LCD), an Organic Light Emitting Diode (OLED), an Active Matrix Organic Light Emitting Diode (AMOLED), and the like. However, exemplary embodiments of the present invention are not limited to these examples. For example, exemplary embodiments of the present invention can be applied to all display devices which are sensitive to temperature. In other words, exemplary embodiments of the present invention may be applied to all display devices having a lifespan that is sensitive to or otherwise varies with the temperature. For example, exemplary embodiments of the present invention may be applied to all display devices whose lifespan decrease speed gets faster in high temperatures. Further, the display unit  130  can perform the function of the input unit  140  if the display unit  130  is formed as a touch screen. 
     The storage unit  120  can store user data, and the like, as well a program which performs operating functions according to an exemplary embodiment of the present invention. For example, the storage unit  120  may store a program for controlling general operation of a portable terminal  100 , an Operating System (OS) which boots the portable terminal  100 , and application program for performing other optional functions such as a camera function, a sound replay function, an image or video replay function, a Near Field Communication (NFC) function, and the like. Further, the storage unit  120  may store user data generated according to a user of the portable terminal, such as, for example, a text message, a game file, a music file, a movie file, and the like. In particular, the storage unit  120  according to exemplary embodiments of the present invention may store a brightness table which stores a mapping of illuminance, temperature, and brightness. An example of such a brightness table is shown in the Table 1 below. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Brightness table 
               
            
           
           
               
               
               
            
               
                   
                 Manual 
                 Automatic mode (cd/m 2 ) 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Temperature 
                 mode 
                 Outdoor 
                 Outdoor 
                 Indoor 
                 Indoor 
                   
               
               
                 (° C.) 
                 (cd/m 2 ) 
                 2 
                 1 
                 2 
                 1 
                 Night 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Less than 40 
                 300 
                 300 
                 220 
                 160 
                 110 
                 40 
               
               
                 (room 
               
               
                 temperature) 
               
               
                 40 or more~ 
                 250 
                 250 
                 220 
                 160 
                 110 
                 40 
               
               
                 less than 45 
               
               
                 45 or more~ 
                 160 
                 160 
                 160 
                 160 
                 80 
                 40 
               
               
                 less than 50 
               
               
                 50 or more~ 
                 100 
                 100 
                 100 
                 100 
                 80 
                 40 
               
               
                 less than 54 
               
               
                 54 or more 
                 40 
                 40 
                 40 
                 40 
                 40 
                 40 
               
               
                   
               
            
           
         
       
     
     In the Table 1 above, the manual mode refers to a mode in which the brightness of the display unit  130  is maintained at a brightness which is set by user regardless of external illuminance, and the automatic mode refers to a mode in which the brightness of the display unit  130  is automatically adjusted according to the external illuminance which is recognized through the illuminance sensor  180 . Referring to the Table 1 above, the brightness table is divided into the manual mode and the automatic mode. The automatic mode has 5 levels of temperature sections. Further, as shown in Table 1, the brightness of the display unit  130  is mapped according to a temperature section. Further, in the Table 1 above, five levels of temperature sections have been used. However, exemplary embodiments of the present invention are not limited to this example. That is, the temperatures may be variously divided into two or more levels depending on, for example, a designer&#39;s or manufacturer&#39;s intention. Further, the external illuminance according to the automatic mode is divided into five levels. However, the external illuminance may also be variously divided into two or more levels depending on, for example, the designer&#39;s or the manufacturer&#39;s intention. Further, the Table 1 above illustrates an example, and the brightness table may be variously modified according to the type of the display unit  130  and according to, for example, the designer&#39;s intention or the manufacturer&#39;s intention. Controlling the brightness of the display unit  130  using the brightness table will be explained later in detail with reference to the controller  110 . 
     The controller  110  may control general operation of the portable terminal  100 . For example, the controller  110  may control operation of the various components or units included in the portable terminal  100 . The controller  110  may transmit a signal to the various components included in the portable terminal  100  and control a signal flow between internal blocks of the portable terminal  100 . In particular, the controller  110  according to exemplary embodiments of the present invention can control brightness of the display unit  130  according to a change of temperature and illuminance. To this end, the controller  110  may measure temperature through the temperature sensor  170 , and extract a corresponding brightness value mapped according to the temperature measured through the brightness table stored in the storage unit  120 . Thereafter, the controller  110  may confirm whether the current brightness exceeds the extracted brightness value by comparing the current brightness of the display unit  130  with the extracted brightness value. If the portable terminal  100  is operating in the manual mode, then the current brightness can be brightness which is preset by user, and if the portable terminal  100  is operating in the automatic mode, then the current brightness can be brightness which is automatically set according to the external illuminance recognized through the illuminance sensor  180 . Hereinafter, the method of controlling brightness will be explained in more detail by dividing the method into the manual mode and the automatic mode. 
     First, according to the manual mode, if the brightness, which is preset by user, exceeds the extracted brightness value, the controller  110  can change the brightness of the display unit  130  to correspond to the extracted brightness value. That is, the controller  110  can limit brightness of the display unit  130  in order to prevent the decrease of the lifespan of the display unit  130  which occurs at high temperatures. Further, if the preset brightness does not exceed the extracted brightness value, then the controller  110  may maintain the brightness of the display unit  130  at the preset brightness by user. For example, if the brightness of the display unit  130  has been manually set to be 270 cd/m 2 , and if the brightness table such as, for example, the above Table 1 is stored, then if the measured temperature is less than 40° C., because the preset brightness 270 cd/m 2  is smaller than the extracted brightness 300 cd/m 2 , the controller  110  may maintain the brightness of the display unit  130  at preset brightness 270 cd/m 2 . In contrast, if the temperature is between 40° C. and 45° C., because the preset brightness 270 cd/m 2  exceeds the extracted brightness 250 cd/m 2 , the controller  110  changes the brightness of the display unit  130  to the extracted brightness 250 cd/m 2 . Similarly, if the temperature is between 45° C. and 50° C., because the preset brightness 270 cd/m 2  exceeds the extracted brightness 160 cd/m 2 , the controller  110  changes the brightness of the display unit  130  to the extracted brightness 160 cd/m 2 . Here, the brightness of the display unit  130  can be performed by controlling voltage or current supplied to the emitting device of the display unit  130 , or by adjusting an on/off time of the emitting device. Such a method of controlling brightness may be apparent to those skilled in the art, and thus the detailed description thereof is omitted here. 
     Further, while operating the portable terminal  100  based on the manual mode, if the mode is changed to the automatic mode according to user&#39;s request, then the controller  110  can control to apply the brightness value according to the current state to the display unit  130  regardless of the brightness value which is set in the manual mode. For example, if the automatic mode setting corresponds to “Outdoor 1” and if the current temperature is less than 40° C., then even though the brightness value for the manual mode is set to 300 cd/m 2 , if the brightness adjustment mode is changed from the manual mode to the automatic mode, then the brightness value of the display unit  130  can be controlled to be automatically adjusted to 220 cd/m 2  which corresponds to the brightness value associated with the automatic mode setting “Outdoor 1” for the current temperature of less than 40° C. If the brightness value of the display unit  130  for the manual mode was set as 300 cd/m 2 , and if the mode is changed to the automatic mode, then such a function can be a function for setting the brightness of the portable terminal  100  so that the brightness value becomes a highly visible value while also securing the lifespan of the display unit  130 . Further, if an input signal for a request to change the mode from the automatic mode to the manual mode is generated, then the controller  110  can be controlled to change the mode to the preset manual mode. 
     Further, if the portable terminal is operating under the automatic mode, then the controller  110  may control the brightness of the display unit  130  in response to at least one of a temperature change and an external illuminance change. That is, if the external illuminance is constant, and if the temperature is changed, then the controller  110  may control to change the brightness by comparing the current brightness with a brightness value stored in the brightness table such as, for example, according to the brightness table corresponding to the illuminance in the Table 1. For example, if the current brightness value (e.g., illuminance value) is measured to be the brightness value (e.g., illuminance value) corresponding to the automatic mode setting “Outdoor 2”, and if the temperature is changed, then the controller  110  can compare the brightness value corresponding to the new temperature with the current brightness based on the brightness table corresponding to the automatic mode setting “Outdoor 2”, and control the brightness adjustment according to the result of the comparison. That is, the controller  110  may control the brightness change so that the current brightness of the display unit  130  can be less than 300 cd/m 2 , 250 cd/m 2 , 160 cd/m 2 , 100 cd/m 2  and 40 cd/m 2 , respectively according to a temperature change in the external illuminance environment corresponding to the automatic mode setting “Outdoor 2”. 
     Further, if the temperature is constant, and if the external luminance is changed, then the controller  110  may control to automatically change the brightness of the portable terminal  100  with reference to the stored brightness table such as, for example, the brightness table of Table 1, according to an illuminance change. For example, if the current temperature is less than 40° C., then the controller  110  may adjust the current brightness of the display unit  130  to be less than 300 cd/m 2 , 220 cd/m 2 , 160 cd/m 2 , 110 cd/m 2  and 40 cd/m 2 , respectively, according to a illuminance change corresponding to the automatic mode settings “Outdoor 2”, “Outdoor 1”, “Indoor 2”, “Indoor 1” and “Night”, etc. Likewise, the controller  110  according to exemplary embodiments of the present invention may control a brightness (e.g., an illuminance) change to be performed based on a temperature and an illuminance change. 
     Further, in the above explanation, the values in the brightness table corresponding to the automatic mode settings “Outdoor 2”, “Outdoor 1”, “Indoor 2”, “Indoor 1” and “Night”, etc. are values corresponding to a certain brightness (e.g., illuminance value), respectively. The values may be the experimental average in a certain area. Specifically, in the case of the external illuminance, the external illuminance values may vary depending on the area, and there may be a difference in the external illuminance depending on the date and time. Hence, the brightness value (e.g., illuminance value) corresponding to the automatic mode setting “Outdoor 2” and “Outdoor 1” can be measured and determined for each area and time. Here, the values corresponding to the automatic mode setting “Outdoor 2” and “Outdoor 1” are values for distinguishing time slots. For example, the value corresponding to the automatic mode setting “Outdoor 1” may be a brightness value (e.g., an illuminance value) corresponding to a certain time slot such as, for example, a brightness value corresponding to morning, noon, or afternoon. The value corresponding to the automatic mode setting “Outdoor 2” may be a brightness value (e.g., an illuminance value) corresponding to a certain time slot, such as, for example, a brightness value corresponding to morning or afternoon. The values corresponding to the automatic mode settings “Indoor 2” and “Indoor 1” are values corresponding to the brightness value (e.g., illuminance value) measured indoors, which can also vary depending on the area. For example, there can be an area at which a relatively bright interior illumination is used, or an area at which a relatively dark interior illumination is used. Further, the values corresponding to the automatic mode settings “Outdoor 2 and “Outdoor 1” can be brightness values (e.g., illuminance values) for each time slot. That is, the values corresponding to the automatic mode settings “Outdoor 2 and “Outdoor 1” reflect the fact that illuminance can be changed according to external environment, that is, time slots corresponding to noon, the morning or the afternoon. As an example, such a distinction may be made even indoors. As explained above, the brightness values (e.g., the illuminance values), which are given certain titles, may vary depending on the area, time, and culture. Accordingly, it may be preferable to calculate the overall average for a design. Additionally, it may be preferable to measure the brightness values (e.g., the illuminance values) differently for each area and each time slot. The measured brightness values may be applied differently for each area and each time slot. 
     If the illuminance of the display unit  130  exceeds the brightness which is manually set by user or the brightness which is automatically set according to the external illuminance, that is, if the brightness of the display unit  130  exceeds the preset brightness value and is limited by high temperature, the user of the portable terminal  100  may be notified of such a context or fact. For example, the portable terminal  100  may inform or communicate such a fact to a user through visible, auditory or tactile means. For example, the controller  110  may output an alarm message, which informs a user that the brightness of the display unit  130  has been limited. The alarm message may be output at one end of the display unit  130  in the form of a pop-up window. As another example, the controller  110  may output an alarm icon in the indicator area. Further, the controller  110  may output an alarm sound through an audio processing unit  160 , or generate a vibration through a vibration motor (not shown). 
     The controller  110  can output the brightness setting menu screen in the display unit  130  when executing the brightness setting mode. The user may select which mode under which to operate the portable terminal  100 . For example, the user may select whether to operate the portable terminal  100  under the automatic mode or the manual mode through the brightness setting menu. If the user selects the manual mode, then the controller  110  may set the brightness of the display unit  130  at the brightness which is set by user. At this time, the controller  110  may set a limit so that user cannot set the brightness of the display unit  130  to exceed the brightness mapped with the current temperature. Further, if the user requests the brightness change of the display unit  130  to a brightness that exceeds the mapped brightness, then the controller  110  may output a warning message. The detailed explanation thereof will be described later with reference to  FIGS. 4 and 5 . 
     Further, although not illustrated in  FIG. 1 , the portable terminal  100  according to exemplary embodiments of the present invention may further optionally include components for providing additional functions, such as a camera module for taking an image or a moving picture, a broadcast reception module for broadcast reception, a digital music source replay module such as an MP3 module or the like for replay of music or media files, a near field communication module for near field communication, a proximity sensor for proximity sensing, and the like. Such components may be variously modified, and thus not all such modified components are listed here. The portable terminal  100  according to exemplary embodiments of the present invention may further include components of the same level as that of the above mentioned components. 
       FIG. 2  is a flowchart illustrating a method of controlling brightness of a portable terminal at a manual mode according to an exemplary embodiment of the present invention. With regard to the description of  FIG. 2 , it is assumed that the brightness of the display unit  130  is preset by user. 
     Referring to  FIG. 2 , the controller  110  according to an exemplary embodiment of the present invention may periodically measure the temperature, according to a preset period, through the temperature sensor  170  at step  201 . The controller  110  may extract the brightness mapped to the measured temperature from the brightness table stored in the storage unit  120  at step  203 . The controller  110  may compare the preset brightness of the display unit  130  with the extracted brightness at step  205 , and may determine whether the preset brightness of the display unit  130  exceeds the extracted brightness at step  207 . If the preset brightness of the display unit  130  exceeds the extracted brightness, then the controller  110  may change the brightness of the display unit  130  to the extracted brightness at step  209 . At this time, though not illustrated, the controller  110  may notify user that the brightness of the display unit  130  has been limited due to the high temperature. For example, the notification may be performed through at least one of a visible means (e.g., an alarm message or an icon output), an auditory means (e.g., an alarm sound output), and a tactile means (e.g., a vibration output). Further, if the brightness of the preset display unit  130  is less than the extracted brightness, then the controller  110  can maintain the brightness of the display unit  130  at the preset brightness at step ( 211 . For example, if it is assumed that the brightness of the display unit  130  is set to 270 cd/m 2 , and the brightness table corresponds to the brightness table provided in Table 1 above, and if the temperature measured through the temperature sensor  170  is less than 40° C., then the controller  110  may maintain the brightness of the display unit  130  at the preset brightness 270 cd/m 2  because the brightness 270 cd/m 2  of the preset display unit  130  is smaller than the extracted brightness 300 cd/m 2 . In contrast, if the temperature is between 40° C. and 45° C., then because the preset brightness 270 cd/m 2  of the display unit  130  exceeds the extracted brightness 250 cd/m 2 , the controller  110  changes the brightness of the display unit  130  to the extracted brightness 250 cd/m 2 . If the temperature is between 45° C. and 50° C., then because the preset brightness 270 cd/m 2  of the display unit  130  exceeds the extracted brightness 160 cd/m 2 , the controller changes the brightness of the display unit  130  to the extracted brightness 160 cd/m 2 . The brightness control of the display unit  130  according to such a temperature change can be repeated until the power of the portable terminal  100  is turned off, the display unit  130  is turned off, or the mode under which the portable terminal  100  operates is changed to the automatic mode. 
     Further, it was explained above that the brightness of the display unit  130  is controlled by comparing the preset brightness of the display unit  130  with the extracted brightness. However, exemplary embodiments of the present invention are not limited to this example. That is, the controller  110  may measure the temperature, and may change the brightness of the display unit  130  to the brightness mapped to the measured temperature, which is prevents or reduces the load on the controller  110  by simplifying the brightness controlling process. 
     Likewise, exemplary embodiments of the present invention can prevent rapid lifespan deterioration of the display unit which is generated by maintaining the constant brightness at high temperatures by controlling to decrease the brightness of the display unit  130  as the temperature increases. 
       FIG. 3  is a flowchart illustrating a method of controlling brightness of a portable terminal at an automatic mode according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 3 , the controller  110  according to an exemplary embodiment of the present invention can periodically measure the temperature and illuminance according to a preset period using a temperature sensor  170  and a illuminance sensor  180  at step  301 . The controller  110  can determine whether at least one of the temperature and illuminance is changed at step  303 . If neither the temperature nor the illuminance is changed, then the controller  110  can remain at step  303 . In contrast, if at least one of the temperature and the illuminance is changed, then the controller  110  can extract the brightness value according to changed elements with reference to the brightness table at step  305 . For example, if the illuminance value is changed from a value corresponding to the automatic mode setting “Outdoor 2” to a corresponding to the automatic mode setting “Outdoor 2” and the temperature is less than 10° C., then the controller adjusts the extracted brightness value from 300 cd/m 2  to 220 cd/m 2 . 
     Next, the controller  110  compares the adjusted extracted brightness value and the preset brightness value of the display unit  130  at step  307 . As a result of the comparison, if the brightness value of the display unit  130  is smaller than the adjusted extracted brightness value, then the controller  110  can control to maintain the brightness value of the display unit  130  which is currently set at step  311 . For example, if the brightness value of the preset display unit  130  is 160, then the controller  110  can control to maintain the preset brightness value of the display unit  130 . 
     Further, if the currently set brightness value of the display unit  130  is larger than the adjusted extracted brightness value, then the controller can control to adjust the brightness value of the display unit  130  to the extracted value at step  309 . For example, if the brightness value of the preset display unit  130  is 250 cd/m 2 , then the controller  110  can control to adjust the preset brightness value of the display unit  130  to 220 cd/m 2 . 
     At this time, the controller  110  can notify the user that the brightness of the display unit  130  has been limited due to high temperatures or according to a high illuminance change. For example, the controller  110  may notify the user through a visible, auditory, or tactile means that the brightness of the display unit  130  has been limited due to high temperatures or according to a high illuminance change. For example, the controller  110  can output an alarm message, which informs that the brightness of the display unit  130  has been limited, in the form of a pop-up window, or output an alarm icon in the indicator area. The indicator area may be an area which outputs battery life or status, received signal strength, and the like, in the form of icons. 
     The brightness control of the display unit  130  according to such a temperature and illuminance change can be repeated until the power of the portable terminal  100  is turned off, or the display unit  130  is turned off. 
     As explained above, exemplary embodiments of the present invention exhibit an effect of improving the lifespan of the display unit  130  by appropriately controlling the brightness of the display unit  130  according to a change of at least one of temperature and illuminance in the automatic mode state. 
       FIG. 4  is a flowchart illustrating a method of setting brightness of a portable terminal according to an exemplary embodiment of the present invention.  FIG. 5  is a series of screen shots illustrating a method of setting brightness of a portable terminal according to an exemplary embodiment of the present invention. 
     Referring to  FIGS. 4 and 5 , the controller  110  according to an exemplary embodiment of the present invention can sense the execution of the brightness setting mode at step  401 . If the brightness setting mode is executed, the controller  110  can control the display unit  130  to output the brightness setting menu screen at step  403 . For example, the controller  110  may control the display unit  130  to output a brightness setting menu screen such as, for example, a screen shot indicated by reference numeral  510  of  FIG. 5 . The brightness setting menu can include an automatic mode menu  10  which can set the automatic mode, a brightness adjustment menu  20  which can manually adjust the brightness, a confirmation key  30  which performs a brightness setting completion function, and a cancelation key  40  which performs a cancellation function. The user can set the automatic mode by touching or otherwise selecting the box of the automatic mode menu  10 . When touching or selecting the box of the automatic mode menu, the controller  110  can output a check mark or other indicia in the box to notify that automatic mode has been set. If the automatic mode is set, then the brightness adjustment menu  20  can be displayed as the inactivated state such that the user cannot provide input to adjust the brightness. For example, the brightness adjustment menu  20  may be displayed as the inactivated state such that the user cannot perform a touch input. If the check mark or other indicia is displayed in the box of the automatic mode menu  10 , and if the automatic mode menu  10  is touched, then the controller  110  can remove the check mark or other indicia, and thereby cancel the selection of the automatic mode. 
     The brightness adjustment menu  20  may include a state bar  24  indicating the overall brightness and a process bar  23  indicating the current brightness. The state bar  24  can be divided into a first brightness area  21  indicating selectable brightness and a second brightness area  22  indicating non-selectable brightness. The sizes of the first brightness area  21  and the second brightness area  22  vary depending on the temperature. The first brightness area  21  includes brightness levels corresponding to permissible levels of brightness of the display unit  130  and the second brightness area  22  includes brightness levels corresponding to impermissible levels of brightness of the display unit  130  at the measured temperature. That is, the boundary between the first brightness area  21  and the second brightness area  22  can be brightness mapped to temperature. For example, if the current temperature is between 45° C. and 50° C., then the boundary between the first brightness area  21  and the second brightness area  22  can be set in the position indicating the brightness of 160 cd/m 2 . Further, it may be desirable for the display unit  130  to display a screen so that the first brightness area  21  can be visibly distinguished from the second brightness area  22 , through which user can easily recognize brightness which can be currently set. In order to distinguish the first brightness area  21  from the second brightness area  22 , the controller  110  can measure temperature and extract the brightness mapped to the measure temperature from the brightness table when executing the manual mode. 
     If the brightness setting screen is being output by the display unit  130 , then the controller  110  can determine whether a brightness change is requested at step  405 . If the brightness change is not requested, then the controller  110  can perform a corresponding function at step  407 . For example, when a touch occurs in the automatic mode menu  10 , the controller  110  can output a check mark or other indicia in a box, and change the brightness adjustment menu  20  to an inactivated state. Further, in response to the cancellation key  40  input (e.g., a touch), the controller  110  can return to the previous step. In contrast, if the brightness change is required, then the controller  110  can determine whether the change-requested brightness exceeds the brightness corresponding to the boundary between the first area  21  and the second area  22 , that is, the brightness mapped to the current temperature at step  409 . If the change-requested brightness exceeds the mapped brightness, then the controller  110  can output a warning message that informs the user that it is not possible to set to the change-requested brightness at step  411 , and the process bar  23  can be moved to a position corresponding to the mapped brightness at step  413 . For example, as shown in a screen shot corresponding to reference numeral  520  of  FIG. 5 , if user touches the second area  22  for a brightness change, the controller  110  can output the process bar  23  after moving the process bar  23  to the touched position as shown in the screen shot corresponding to reference numeral  530 , output a warning message  25  that informs the user that it is not possible to change to the requested brightness as shown in the screen shot corresponding to reference numeral  540 , and output the process bar  23  after moving the process bard  23  to the boundary between the first area  21  and the second area  22 . Further, the process associated with the screen shot corresponding to reference numeral  530  may be omitted. That is, when a touch occurs in the second area  22 , the controller  110  can move the process bar  23  to the boundary between the first area  21  and the second area  22 , and output a warning message. 
     Further, it was illustrated in  FIG. 5  that brightness is changed through a touch. However, exemplary embodiments of the present invention are not limited to this example. For example, the user can change brightness by a drag while touching the process bar  23 . As another example, the user may change the brightness by otherwise manipulating the input  140  so as to input corresponding instructions for changing the brightness. 
     If the change-requested brightness does not exceed the mapped brightness, then the controller  110  can move the process bar  23  to the touch position and change brightness of the display unit  130  to a brightness corresponding to the touched position at step  415 , and can move to step  417 . The controller  110  may determine whether the brightness setting has been completed. In other words, the controller  110  may determine whether the confirmation key  30  has been inputted at step  417 . In case the brightness setting has not been completed, the controller  110  can return to step  405 . In case the brightness setting has been completed, the controller  110  can terminate the brightness setting mode of the display unit  130 . 
       FIG. 6  is a flowchart illustrating a method of operating brightness setting of a portable terminal according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 6 , according to the method of setting brightness of a portable terminal  100  according to exemplary embodiments of the present invention, first, if power is supplied to a portable terminal  100 , the controller  110  may control to initialize each configuration of the portable terminal  100 . If the initialization process is completed, then the controller  110  may output the idle screen according to preset schedule information at step  601 . 
     Thereafter, the controller  110  checks brightness setting mode at step  603 , and determines whether the currently set brightness setting mode is the manual mode at step  605 . If the currently set brightness setting mode is the manual mode, then the controller  110  measures the current temperature at step  607 . Thereafter, the controller  110  can control to check the extracted brightness value of manual mode as provided in the stored brightness table such as, for example, the brightness table shown in Table 1 according to the measured current temperature, compare the preset brightness value of the display unit  130  with the extracted brightness value of manual mode according to the current temperature, and adjust brightness according to a result of the comparison at step  609 . That is, if the preset brightness value of the display unit  130  is larger than the extracted brightness value corresponding to the manual mode according to the temperature, then the controller  110  may control the brightness value of the display unit  130  to be adjusted to the brightness value corresponding to the manual mode, and if the preset brightness value of the display unit  130  is smaller than the extracted brightness value corresponding to the manual mode according to the temperature, then the controller  110  may control to maintain the brightness value of the display unit  130 . 
     Further, as a result of checking the brightness setting mode at step  605 , if the mode is set to be the automatic mode, then the controller  110  measures the current temperature and illuminance at step  611 . Further, the controller  110  may extract the extracted brightness value corresponding to the automatic mode which corresponds to the measured temperature and illuminance with reference to the already stored brightness table at step  613 . Thereafter, the controller  110  may adjust the brightness value of the display unit  130  to correspond to the extracted brightness value corresponding to the automatic mode. 
     Further, the controller  110  may control to determine whether the mode change has occurred at step  615 , and if the mode change has occurred, then the controller  110  may control to adjust the brightness value according to the mode change at step  617 . Specifically, if the mode is changed from the manual mode to the automatic mode, the controller  110  may control to change the brightness value of the display unit  130 , which is set by user, to the brightness value of the automatic mode, which corresponds to the current temperature and illuminance. Further, if the mode is changed from the automatic mode to the manual mode, then the controller  110  may control to change the brightness value of the display unit  130  to the brightness value which is set by the user at previous manual mode. At this time, the controller  110  may support to set the brightness value of the display unit  130  to the extracted brightness value corresponding to the manual mode which corresponds to the corresponding temperature by measuring the current temperature. If no brightness value has been previously set, then the controller  110  may control to have a certain brightness value set as a default brightness value. If a separate mode change has not occurred at step  615 , then the controller  110  may control to support adjusting the brightness according to the currently-set mode at step  619 . 
     Thereafter, the controller  110  may control to return to step  601  and output the idle screen, or to support the user function of the portable terminal  100  corresponding to an input signal inputted from the input unit  140 , or the like. 
     A method for controlling brightness according to exemplary embodiments of the present invention may be implemented in an executable program command form by various computer means and be recorded in a non-transitory computer readable recording medium. The computer readable recording medium may include a program command, a data file, and a data structure individually or a combination thereof. The program command recorded in a recording medium may be specially designed or configured for exemplary embodiments of the present invention, or may be known to a person having ordinary skill in a computer software field. 
     The computer readable recording medium includes Magnetic Media such as hard disk, floppy disk, or magnetic tape, Optical Media such as Compact Disc Read Only Memory (CD-ROM) or Digital Versatile Disc (DVD), Magneto-Optical Media such as floptical disk, a hardware device such as ROM, RAM, flash memory storing and executing program commands, and the like. Further, the program command includes a machine language code created by a compiler and a high-level language code executable by a computer using an interpreter. The foregoing hardware device may be configured to be operated as at least one software module to perform an operation of exemplary embodiments of the present invention. 
     As explained above, a method and apparatus for controlling brightness in a portable terminal according to an exemplary embodiment of the present invention can prevent a decrease of the lifespan of a display unit by appropriately controlling the brightness of the display unit according to a change in temperature and illuminance. That is, exemplary embodiments of the present invention can improve the lifespan of the display unit. Further, exemplary embodiments of the present invention can improve user&#39;s convenience by displaying the maximum brightness which can be set at the current temperature, limiting the brightness of the display unit so that user cannot set the brightness to a value which exceeds the maximum brightness, and informing user that the brightness of the display unit has been limited. 
     While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.