Patent Publication Number: US-9406262-B2

Title: Mobile electronic device with luminance control according to surrounding brightness and contact

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of U.S. application Ser. No. 13/335,386, filed on Dec. 22, 2011, which claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2010-288565, filed on Dec. 24, 2010, and entitled “MOBILE TERMINAL, METHOD FOR CONTROLLING BRIGHTNESS, AND PROGRAM FOR CONTROLLING BRIGHTNESS”. The content of each of these applications is incorporated by reference herein in its entirety. 
    
    
     FIELD 
     Embodiments of the present disclosure relate generally to mobile electronic devices, and more particularly relate to controlling brightness of a display on a touch panel of a mobile electronic device. 
     BACKGROUND 
     A user may perform an operation on a touch panel of a mobile electronic device at an initial brightness of the touch panel. If the user performs repeated operations on the touch panel, the initial brightness may be maintained throughout the repeated operation. However, brightness surrounding the touch panel may affect visibility of the touch panel. For example, when the user operations on the touch panel are being performed repeatedly while the user moves the mobile electronic device from a bright location to a dark location, the touch panel is illuminated at the same luminance used in the dark location. 
     SUMMARY 
     A luminance control device and method are disclosed. A surrounding brightness of a touch panel is measured to obtain a measured surrounding brightness. A luminance of the touch panel is controlled during a first time period starting from when the measured surrounding brightness changes from a first condition to a second condition, during which the measured surrounding brightness decreases by an amount equal to or greater than a threshold value. The luminance of the touch panel is maintained at a first luminance corresponding to the first condition when the measured surrounding brightness changes from the second condition to the first condition. The luminance of the touch panel is controlled to change to a second luminance corresponding to the second condition, when the measured surrounding brightness has not changed from the second condition to the first condition. 
     In an embodiment, a mobile electronic device comprises a touch panel, an optical sensor, and a luminance control module. The optical sensor is operable to measure a surrounding brightness of the touch panel to provide a measured surrounding brightness. The luminance control module is operable to control a luminance of the touch panel during a first time period starting from when the measured surrounding brightness changes from a first condition to a second condition, during which the measured surrounding brightness decreases by an amount equal to or greater than a threshold value. The luminance control module is also operable to maintain the luminance of the touch panel at a first luminance corresponding to the first condition when the measured surrounding brightness changes from the second condition to the first condition. The luminance control module is further operable to control the luminance of the touch panel to change to a second luminance corresponding to the second condition, when the measured surrounding brightness has not changed from the second condition to the first condition. 
     In another embodiment, a luminance control method measures a surrounding brightness of a touch panel to obtain a measured surrounding brightness. The luminance control method further controls a luminance of the touch panel during a first time period starting from when the measured surrounding brightness changes from a first condition to a second condition, during which the measured surrounding brightness decreases by an amount equal to or greater than a threshold value. The luminance control method further maintains the luminance of the touch panel at a first luminance corresponding to the first condition when the measured surrounding brightness changes from the second condition to the first condition. The luminance control method further controls the luminance of the touch panel to change to a second luminance corresponding to the second condition, when the measured surrounding brightness has not changed from the second condition to the first condition. 
     In a further embodiment, a computer readable storage medium comprises computer-executable instructions for performing a method for communicating using a plurality of antennas. The method executed by the computer-executable instructions measures a surrounding brightness of a touch panel to obtain a measured surrounding brightness. The method executed by the computer-executable instructions further controls a luminance of the touch panel during a first time period starting from when the measured surrounding brightness changes from a first condition to a second condition, during which the measured surrounding brightness decreases by an amount equal to or greater than a threshold value. The method executed by the computer-executable instructions further maintains the luminance of the touch panel at a first luminance corresponding to the first condition when the measured surrounding brightness changes from the second condition to the first condition. The method executed by the computer-executable instructions further controls the luminance of the touch panel to change to a second luminance corresponding to the second condition, when the measured surrounding brightness has not changed from the second condition to the first condition. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present disclosure are hereinafter described in conjunction with the following figures, wherein like numerals denote like elements. The figures are provided for illustration and depict exemplary embodiments of the present disclosure. The figures are provided to facilitate understanding of the present disclosure without limiting the breadth, scope, scale, or applicability of the present disclosure. 
         FIG. 1A  is an illustration of a top view of an exemplary mobile electronic device at a bright location according to an embodiment of the disclosure. 
         FIG. 1B  is an illustration of the top view of the exemplary mobile electronic device of  FIG. 1A  showing a user&#39;s finger partially covers surrounding light on a touch panel thereof. 
         FIG. 2  is an illustration of a top view of an exemplary mobile electronic device at a dark location according to an embodiment of the disclosure. 
         FIG. 3  is an illustration of an exemplary functional block diagram of a mobile electronic device according to an embodiment of the disclosure. 
         FIG. 4  is an illustration of top view of an exemplary mobile electronic device showing a position on a touch panel thereof according to an embodiment of the disclosure. 
         FIG. 5  is an illustration of an exemplary flowchart showing a luminance control process according to an embodiment of the disclosure. 
         FIG. 6  is an illustration of an exemplary graph showing detection results from a contact detection module, determination results from a condition determination module, and timing of changes in luminance of a touch panel according to an embodiment of the disclosure. 
         FIG. 7  is an illustration of an exemplary functional block diagram of a mobile electronic device according to an embodiment of the disclosure. 
         FIG. 8  is an illustration of an exemplary flowchart showing a luminance control process according to an embodiment of the disclosure. 
         FIG. 9  is an illustration of an exemplary flowchart showing a luminance control process according to an embodiment of the disclosure. 
         FIG. 10  is an illustration of an exemplary functional block diagram of a mobile electronic device according to an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is presented to enable a person of ordinary skill in the art to make and use the embodiments of the disclosure. The following detailed description is exemplary in nature and is not intended to limit the disclosure or the application and uses of the embodiments of the disclosure. Descriptions of specific devices, techniques, and applications are provided only as examples. Modifications to the examples described herein will be readily apparent to those of ordinary skill in the art, and the general principles defined herein may be applied to other examples and applications without departing from the spirit and scope of the disclosure. The present disclosure should be accorded scope consistent with the claims, and not limited to the examples described and shown herein. 
     Embodiments of the disclosure are described herein in the context of one practical non-limiting application, namely, a mobile electronic device such as a mobile phone. Embodiments of the disclosure, however, are not limited to such mobile phone, and the techniques described herein may be utilized in other applications. For example, embodiments may be applicable to digital books, digital cameras, electronic game machines, digital music players, personal digital assistance (PDA), personal handy phone system (PHS), lap top computers, TV&#39;s, Global Positioning Systems (GPSs) or navigation systems, pedometers, health equipment, display monitors, or other electronic device that uses a display screen or a touch panel for displaying information. 
     As would be apparent to one of ordinary skill in the art after reading this description, these are merely examples and the embodiments of the disclosure are not limited to operating in accordance with these examples. Other embodiments may be utilized and structural changes may be made without departing from the scope of the exemplary embodiments of the present disclosure. 
       FIG. 1A  is an illustration of a top view of an exemplary mobile electronic device such as a mobile phone  100  at a bright location according to an embodiment of the disclosure.  FIG. 1B  is an illustration of the top view of the exemplary the mobile phone  100  of  FIG. 1A  showing a user&#39;s finger partially covers surrounding light on a touch panel thereof.  FIG. 2  is an illustration of a top view of an exemplary mobile electronic device at a dark location according to an embodiment of the disclosure. 
     The mobile phone  100  may generally comprise: a speaker  1 , a microphone  2 , the touch panel  110 , and an optical sensor  120 . The mobile phone  100  may be a straight-type terminal. The mobile phone  100  is operable to control a luminance of the touch panel  110  based on an actual surrounding brightness thereof. 
     The touch panel  110  is operable to display objects such as icons, or other object thereon. 
     The optical sensor  120  is operable to measure the surrounding brightness of the touch panel  110 . If the measured surrounding brightness changes between a first condition, in which the surrounding brightness is equal to or greater than a threshold value, and a second condition, in which the surrounding brightness is less than the threshold value, the mobile phone  100  changes the luminance of the touch panel  110  within a time period after the surrounding brightness changes if there are no further changes in the surrounding brightness. This is because if the user moves the mobile phone  100  from a bright location to a dark location, the surrounding brightness measured by the optical sensor  120  should stabilize in a post-change condition. 
     For example, when the mobile phone  100  is in a bright location, the optical sensor  120  may receive a shadow of a hand of the user due to the user operations on the touch panel  110 , and the surrounding brightness measured by the optical sensor  120  is assumed to have changed from the first condition to the second condition. 
     If the user operations end within a prescribed time from the first condition to the second condition and the user stops the operations for example by releasing their finger from the touch panel  110 , the shadow of the hand of the user disappears, and the optical sensor  120  measures the actual surrounding brightness. 
     If the mobile phone  100  is continuously in a bright location, the surrounding brightness measured by the optical sensor  120  changes to the first condition, and it is therefore not necessary for the mobile phone  100  to change the luminance of the touch panel  110 . 
     On the other hand, if the mobile phone  100  is moved to a dark location, the surrounding brightness measured by the optical sensor  120  is maintained in the second condition, and the mobile phone  100  may therefore decrease the luminance of the touch panel  110 . 
     In this manner, the mobile phone  100  may control the luminance of the touch panel  110  according to whether there is another change in brightness surrounding the touch panel  110  within the prescribed time period from a previous change in the brightness measured by the optical sensor  120 . The mobile phone  100  can prevent inappropriate control of the luminance caused by the user operations on the touch panel  110 , and if user operations on the touch panel  110  are being performed repeatedly, the mobile phone  100  can assure the touch panel  110  is visible when the actual surrounding brightness has decreased. 
     The prescribed time period is referred to as a “time window”, and the luminance corresponding to the first condition is referred to as the “first luminance” and the luminance corresponding to the second condition is referred to as the “second luminance”. 
     The mobile phone  100  controls the luminance of the touch panel  110  according to whether or not the condition of the brightness measured by the optical sensor  120  changes again within a time window to assure visibility of the display screen. For example, as a result of user operations on the touch panel  110 , the brightness measured by the optical sensor  120  may differ from the actual surrounding brightness. For another example, due to light being received at the optical sensor  120 , the brightness measured by the optical sensor  120  may differ from the actual surrounding brightness. 
       FIG. 3  is an illustration of an exemplary functional block diagram  100  (system  100 ) of a mobile electronic device such as the mobile phone  100  according to an embodiment of the disclosure. The mobile phone  100  comprises the touch panel  110 , the optical sensor  120 , a first clock module  130 , a second clock module  131 , a third clock module  132 , a memory module  140 , a control module  150 , and a processor module  160 . 
     A practical embodiment of the system  100  may comprises additional components and elements configured to support known or conventional operating features that need not be described in detail herein. The system  100  may have functions, material, and structures that are similar to the mobile phone  100  in  FIG. 1 . Therefore common features, functions, and elements may not be redundantly described here. 
     The touch panel  110  comprises a display module  111 , an input module  112 , and an illumination module  113 . 
     The display module  111  comprises a Liquid Crystal Display (LCD), and receives an instruction from the control module  150  to display images of characters, icons, and other information, on the LCD. The input module  112  detects a contact made by the user. While detecting the contact made by the user, at each unit time (e.g., 25 ms), the input module  112  sends coordinate values (x, y) of a position of the contact by the user to the control module  150 . The input module  112  comprises a capacitive touch sensor, or other sensor. 
     The coordinate values of a top left corner of the touch panel  110  in  FIG. 1A  are (0, 0), and the coordinate values of a bottom right corner of the touch panel  110  in  FIG. 1A  are (479, 799). However, other coordinate values may also be used. 
     A contact comprises conditions in which a body part of the user such as a finger, a touch pen, or other contact mean is in contact with the touch panel  110 . A contact may also comprise conditions in which an object that changes a capacitance of the touch panel  110 , such as the finger or other body part of the user, or a touch pen, approaches the touch panel  110  to a degree that changes the capacitance of the touch panel  110  to become equal to or greater than a prescribed threshold value. 
     The illumination module  113  is known as a backlight, and in accordance with instructions from the control module  150 , it is able to light the luminance of the display module  111  to a luminance (first luminance or second luminance) instructed by the control module  150 . 
     The optical sensor  120  detects the surrounding brightness, and can output signals of voltage levels corresponding to the detected brightness to the control module  150 . The optical sensor  120  may comprise photodiodes. 
     The first clock module  130  starts keeping time after receiving an instruction from the control module  150 . The second clock module  131  keeps the current time (e.g., in 1 ms units). 
     The third clock module  132  starts keeping time after receiving an instruction from the control module  150 , and when the third clock module  132  keeps time for a preset time period, it notifies the control module  150 . The preset time period that is kept by the third clock module  132  is abbreviated as the third time period. The third time period may be, for example, about 2 seconds, and may be set arbitrarily. 
     The first clock module  130 , the second clock module  131 , and the third clock module  132  comprise, for example, a timer and a counter. 
     The processor module  160  may be implemented, or realized, with a general purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. In this manner, a processor may be realized as a microprocessor, a controller, a microcontroller, a state machine, or the like. 
     A processor may also be implemented as a combination of computing devices, e.g., a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration. In practice, the processor module  160  comprise processing logic that is configured to carry out the functions, techniques, and processing tasks associated with the operation of the system  100 . 
     In particular, the processing logic is configured to support the luminance control method described herein. Furthermore, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in firmware, in a software module executed by processor module  160 , or in any practical combination thereof. 
     The memory module  140 , may be realized as a non-volatile storage device (non-volatile semiconductor memory, hard disk device, optical disk device, and the like), a random access storage device (for example, SRAM, DRAM), or any other form of storage medium known in the art. The memory module  140  may be coupled to the processor module  160  respectively such that the processor module  160  can read information from, and write information to, memory module  140 . 
     As an example, the processor module  160  and memory module  140 , may reside in their respective ASICs. The memory module  140  may also be integrated into the processor module  160 . In an embodiment, the memory module  140  may include a cache memory for storing temporary variables or other intermediate information during execution of instructions to be executed by processor module  160 . The memory module  140  may also include non-volatile memory for storing instructions to be executed by the processor module  160 . 
     The memory module  140  may include a database for storing the contact information table  10  and positional information  20  in accordance with an embodiment of the disclosure. The memory module  140  may also store, a computer program that is executed by the processor module  160  respectively, an operating system, an application program, tentative data used in executing a program processing, and the like. 
     The contact information table  10  is a table in which information composed of the time and coordinate values of when contact on the touch panel  110  is detected (hereinafter referred to as “contact information”) is registered. The positional information  20  is information indicating a specific position  21  on the touch panel  110 . 
     The specific position  21  indicates a position on the touch panel  110  that may decrease the brightness measured by the optical sensor  120  when the user attempts to operate the touch panel  110  and, for example, their finger, comes into contact. 
     Those skilled in the art will understand that the various illustrative blocks, modules, circuits, and processing logic described in connection with the embodiments disclosed herein may be implemented in hardware, computer-readable software, firmware, or any practical combination thereof. To clearly illustrate this interchangeability and compatibility of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps are described generally in terms of their functionality. 
     Whether such functionality is implemented as hardware, firmware, or software depends upon the particular application and design constraints imposed on the overall system. Those familiar with the concepts described herein may implement such functionality in a suitable manner for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. 
       FIG. 4  is an illustration of top view of an exemplary mobile electronic device such as the mobile phone  100  showing a position on the touch panel  110  thereof according to an embodiment of the disclosure. The coordinate values (xa, ya) of the top left corner of the specific position  21  indicated by the shaded area are, for example, (320, 610), and the coordinate values (xb, yb) of the bottom right corner are, for example, (479, 799). 
     The positional information  20  comprises the coordinate values (xa, ya) of the top left corner of the specific position  21  indicated by the shaded area as well as the coordinate values (xb, yb) of the bottom right corner. 
     Other functions of the mobile phone  100  are described below in conjunction with  FIG. 3 . 
     In addition to various functions comprised in a general mobile phone that comprises display control functions, the control module  150  comprises functions that controls the luminance of the illumination module  113  of the touch panel  110  based on signals output from the optical sensor  120 . The control module  150  further comprises a contact detection module  151 , a condition determination module  152 , and a luminance control module  153 . 
     By receiving coordinate values from the input module  112  of the touch panel  110 , the contact detection module  151  is able to detect contact by, for example, the finger of the user on the touch panel  110 . 
     Upon receiving the coordinate values from the input module  112 , the contact detection module  151  acquires the time of reception from the second clock module  131 . The contact detection module  151  registers the acquired time and the received coordinate values (i.e., the contact information) in the contact information table  10  of the memory module  140 . 
     Based on signals output from the optical sensor  120 , the condition determination module  152  determines whether or not the surrounding brightness is in the first condition or the second condition. 
     For example, if the brightness corresponding to the signals output from the optical sensor  120  is equal to or greater than the prescribed threshold value, it is determined to be in the first condition, and if it is less than the prescribed threshold value, it is determined to be in the second condition. The prescribed coordinate value is a value for distinguishing the brightness of the sunshine outdoors (e.g., about 100,000 lux) from the brightness of a normal indoor area (e.g., white fluorescent light of about 40 W) (e.g., about 500 lux), and may be a value corresponding to about “1,000 lux”, for example. The prescribed value is not limited to 1,000 lux, and may be set arbitrarily. 
     When the determination results from the condition determination module  152  changes, the luminance control module  153  starts the timekeeping by the first clock module  130  and the third clock module  132 . If the determination results from the condition determination module  152  do not change again by the time the first clock module  130  finishes keeping the time window, the luminance control module  153  also sends an instruction to the illumination module  113  of the touch panel  110  to change to the luminance corresponding to the post-change condition. 
     If the determination results from the condition determination module  152  change, based on the contact information table  10  and the positional information  20  of the memory module  140 , the luminance control module  153  determines whether there was any contact by the, for example, finger of the user, on the specific position  21  of the touch panel  110  during a period from the second time period before the change to the third time period after the change. 
     The luminance control module  153  defines the default value of the time window as the first time period, and in this determination, if there has been contact, the luminance control module  153  changes the time window to a fourth time period that is longer than the first time period. 
     In this example, the first time period will be “about 3 seconds”, the fourth time period maybe “about 5 seconds”, and the second and third time periods may each be “about 2 seconds”. The first time period, the second time period, the third time period, and the fourth time period are not limited to these numbers, and may be set to any appropriate number. 
       FIG. 5  is an illustration of an exemplary flowchart showing a luminance control process  500  (process  500 ) that can be performed by the mobile phone  100  according to an embodiment of the disclosure. The various tasks performed in connection with the process  500  may be performed by software, hardware, firmware, a computer-readable medium having computer executable instructions for performing the process method, or any combination thereof. The process  500  may be recorded in a computer-readable medium such as a semiconductor memory, a magnetic disk, an optical disk, and the like, and can be accessed and executed, for example, by a computer CPU such as the processor module  160  in which the computer-readable medium is stored. 
     The luminance control process  500  may begin when power of the mobile phone  100  is turned ON, and may end when the power is turned OFF. 
     The first time period, the second time period, the third time period, and the fourth time period are noted as “t 1 ”, “t 2 ”, “t 3 ”, and “t 4 ”, respectively. 
     When the power of the mobile phone  100  is turned ON, the control module  150  initializes the contact information table  10  (i.e., deletes all registered contact information). 
     Furthermore, asynchronously from the luminance control process  500 , when the contact detection module  151  detects contact by, for example, the finger of the user, on the touch panel  110 , it may register contact information in the contact information table  10 . 
     The condition determination module  152  determines whether the brightness measured by the optical sensor  120  is in either the first condition or the second condition. The luminance control module  153  specifies the luminance (first luminance or second luminance) corresponding to this determination result for the illumination module  113  of the touch panel  110 . The illumination module  113  starts illumination with the specified luminance (task s 1 ). 
     If the brightness measured by the optical sensor  120  is equal to or greater than the prescribed threshold value, the condition determination module  152  determines that it is in the first condition, and if it is less than the threshold value, the condition determination module  152  may determine that it is in the second condition. 
     The condition determination module  152  determines whether the brightness measured by the optical sensor  120  is in either the first condition or the second condition, and the luminance control module  153  determines whether the determination result has changed from the previous determination result (task s 2 ). 
     If there is no change from the previous determination result (task s 2 : NO), the process of task s 2  is repeated. If the condition has changed since the previous determination result from the first condition to the second condition or from the second condition to the first condition (task s 2 : YES), the luminance control module  153  sets the time window to the first time period (task s 3 ). The luminance control module  153  starts timekeeping by the first clock module  130  and the third clock module  132 . The luminance control module  153  acquires the current time from the second clock module  131 . Furthermore, if the first clock module  130  and the third clock module  132  are already keeping time, the luminance control module  153  may start timekeeping after resetting them. 
     Based on the contact information table  10  and the positional information  20  in the memory module  140 , the luminance control module  153  determines whether there has been any contact in the specific position  21  (hereinafter referred to as “specific contact”) in the period from the second time period before the time acquired from the second clock module  131  to the acquired time (task s 5 ). 
     For example, if the coordinate values comprised in the contact information that comprises the times from the second time period before the acquired time to the acquired time are comprised within the rectangular area (specific position  21 ) identified by the top-left coordinate values (xa, ya) and bottom-right coordinate values (xb, yb) in the positional information  20 , a positive determination (task s 5 : YES) is made. 
     If a positive determination is made (task s 5 : YES), the luminance control module  153  sets the time window to the fourth time period (task s 6 ). 
     The luminance control module  153  acquires the time period being kept by the first clock module  130 , and determines whether or not the time window has elapsed since the first clock module  130  started keeping time (i.e., since the determination result of the condition determination module  152  changed in task s 2 ) (task s 7 ). 
     If the time window has elapsed (task s 7 : YES), the luminance control module  153  specifies the luminance (first luminance or second luminance) corresponding to the most recent determination result from the condition determination module  152  for the illumination module  113  of the touch panel  110 . The illumination module  113  changes to the specified luminance to perform illumination (task s 9 ). The luminance control module  153  repeats the processes from (task s 2 ). 
     If the time window has not elapsed (task s 7 : NO), the condition determination module  152  determines whether the brightness measured by the optical sensor  120  is in either the first condition or the second condition. The luminance control module  153  determines whether or not the determination result has changed from the previous determination result (task s 8 ). 
     If there has been no change from the previous determination result (task s 8 : NO), the luminance control module  153  repeats the processes from task s 7 . If the condition has changed from the previous determination result from the first condition to the second condition or from the second condition to the first condition (task s 8 : YES), the luminance control module  153  repeats the processes from task s 2 . 
     In (task s 5 ), if a negative determination is made (task s 5 : NO), the luminance control module  153  determines whether there has been any specific contact after the time acquired in task s 4  based on the contact information table  10  and the positional information  20  in the memory module  140  (task s 10 ). 
     For example, if the coordinate values comprised in the contact information that comprises the times subsequent to the time acquired in task s 4  are comprised in the rectangular area (specific position  21 ) identified by the top-left coordinate values (xa, ya) and the bottom-right coordinate values (xb, yb) in the positional information  20 , the luminance control module  153  makes a positive determination (task s 10 : YES). 
     If a positive determination is made (task s 10 : YES), the luminance control module  153  proceeds to the process of task s 6 , and if a negative determination is made (task s 10 : NO), it determines whether the third time period has elapsed since the third clock module  132  started keeping time (i.e., since the determination result of the condition determination module  152  changed in task s 2 ) (task s 11 ). 
     If there is a notification from the third clock module  132  that time has been kept for the third time period, the luminance control module  153  determines that the third time period has elapsed (task s 11 : YES) and proceeds to the process of task s 7 . 
     If there is no notification from the third clock module  132  that time has been kept for the third time period, the luminance control module  153  determines that the third time period has not elapsed (task s 11 : NO), and the condition determination module  152  determines whether the brightness measured by the optical sensor  120  is in either the first condition or the second condition. The luminance control module  153  determines whether the determination result of the condition determination module  152  has changed from the previous determination result (task s 12 ). 
     If there has been no change in the determination result from the condition determination module  152  (task s 12 : NO), the luminance control module  153  repeats the processes from task s 10 . If the condition has changed from the previous determination result from the first condition to the second condition or from the second condition to the first condition (task s 12 : YES), the luminance control module  153  repeats the processes from task s 2 . 
     The operations of the mobile phone  100  described above will be described in detail using the example shown in  FIG. 6 . 
       FIG. 6  is an illustration of an exemplary graph showing detection results from a contact detection module  151 , determination results from a condition determination module  152 , and timing of changes in luminance of the touch panel  110  according to an embodiment of the disclosure. 
     The shaded area in the timing of the detection results from the contact detection module  151  indicates that there has been specific contact. 
     The time T 17  indicates the time when the user possessing the mobile phone  100  moved from a bright location (e.g., sunny outdoor area) to a dark location (e.g., a normal indoor area). The time T 20  indicates the time when the user possessing the mobile phone  100  moved from a dark location to a bright location. 
     The time T 10  indicates the timing when the power of the mobile phone  100  was turned ON. 
     In the embodiment shown in  FIG. 6 , because the mobile phone  100  is in a bright location, the condition determination module  152  determines that the brightness measured by the optical sensor  120  is in the first condition. The luminance control module  153  causes the illumination module  113  to start illumination at the first luminance (task s 1 ). 
     At the time T 11 , the brightness measured by the optical sensor  120  changes to the second condition, and the luminance control module  153  therefore determines that the determination result from the condition determination module  152  has changed from the previous determination result (first condition) (task s 2 : YES). The luminance control module  153  sets the time window to the first time period (task s 3 ). The luminance control module  153  causes the first clock module  130  and the third clock module  132  to start timekeeping, and acquires the current time (time T 11 ) from the second clock module  131  (task s 4 ). 
     The luminance control module  153  determines that there was no specific contact in the period from the second time period before the acquired time T 11  and the time T 11  (task s 5 : NO). The luminance control module  153  determines whether or not there was any specific contact after the acquired time T 11  (task s 10 ). 
     At the time T 12  that is before the third time period elapses from the acquired time T 11 , there is specific contact (task s 10 : YES). Therefore, the luminance control module  153  sets the time window to the fourth time period (task s 6 ). 
     At the time T 13  that is before the time period being kept by the first clock module  130  elapses the time window (t 4 ) from the time T 11 , the brightness measured by the optical sensor  120  changes to the first condition. The luminance control module  153  determines that the determination result from the condition determination module  152  has changed from the previous determination result (second condition) (task s 7 : NO, task s 8 : YES). 
     At the time T 4 , the luminance control module  153  determines that the determination result from the condition determination module  152  has changed from the first condition to the second condition (task s 2 : YES). The luminance control module  153  sets the time window to the first time period (task s 3 ), and resets and then starts the timekeeping by the first clock module  130  and the third clock module  132 . The luminance control module  153  acquires the current time (time T 14 ) from the second clock module  131  (task s 4 ). 
     The luminance control module  153  determines that there was no specific contact in the period from the second time period before the acquired time T 14  to the time T 14  (task s 5 : NO). The luminance control module  153  determines that the determination result from the condition determination module  152  changed from the second condition to the first condition at the time T 15  that is before the third time period elapses from the acquired time T 14  (S 12 : YES). 
     Next, at the time T 16 , the luminance control module  153  determines that the determination result from the condition determination module  152  changed from the first condition to the second condition (task s 2 : YES). The luminance control module  153  sets the time window to the first time period (task s 3 ). The luminance control module  153  resets and then starts the timekeeping by the first clock module  130  and the third clock module  132 , and acquires the current time (time T 16 ) from the second clock module  131  (task s 4 ). 
     The luminance control module  153  determines that there was specific contact at the acquired time T 16  (task s 5 : YES), and sets the time window to the fourth time period (task s 6 ). 
     In the embodiment shown in Figure, until the time T 18 , when the time period being kept by the first clock module  130  elapses the time window (t 4 ) from the time T 16 , the brightness measured by the optical sensor  120  remains in the second condition (task s 8 : NO). The luminance control module  153  determines that the time window (t 4 ) has elapsed at the time T 18  (task s 7 : YES). Consequently, the luminance control module  153  causes the illumination module  113  to change to the luminance (second luminance) corresponding to the most recent determination result from the condition determination module  152  and perform illumination (task s 9 ). 
     From the time T 19  to the time T 21 , the sun was hitting the optical sensor  120 . 
     At the time T 19 , the luminance control module  153  determines that the determination result from the condition determination module  152  changed from the second condition to the first condition (task s 2 : YES). The luminance control module  153  sets the time window to the first time period (task s 3 ), and resets and then starts the timekeeping by the first clock module  130  and the third clock module  132 . The luminance control module  153  acquires the current time (time T 19 ) from the second clock module  131  (task s 4 ). 
     The luminance control module  153  determines that there was no specific contact in the period from the second time period before the acquired time T 19  to the time T 19 , or in the period from the acquired time T 19  to the third time period later (task s 5 : NO, task s 10 : NO, task s 11 : YES). 
     Until the time T 22 , when the time period being kept by the first clock module  130  has elapsed the time window (t 1 ) from the time T 19 , the brightness measured by the optical sensor  120  remains in the first condition (task s 8 : NO). The luminance control module  153  determines that the time window (t 1 ) has elapsed at the time T 22  (task s 7 : YES). 
     Consequently, the luminance control module  153  causes the illumination module  113  to change to the luminance (first luminance) corresponding to the most recent determination result from the condition determination module  152  and perform illumination (task s 9 ). 
     As described above, even if the brightness measured by the optical sensor  120  changes to the second condition due to a user operation on the touch panel  110  in a bright location (e.g., time T 11 , time T 14 , etc. in  FIG. 6 ), the mobile phone  100  is able to maintain the luminance of the touch panel  110  at the first luminance, and is therefore able to secure visibility. 
     If user operations on the touch panel  110  are being performed repeatedly, when the mobile phone  100  moves from a bright location to a dark location, it is able to change the luminance of the touch panel to the luminance corresponding to the dark location (in this example, the second luminance) (e.g., time T 18 , etc. in  FIG. 6 ). 
     If reflected light is hitting the optical sensor  120 , when the mobile phone  100  moves from a dark location to a bright location, it is able to change the luminance of the touch panel to the luminance corresponding to the bright location (first luminance) (e.g., time T 22 , etc. in  FIG. 6 ). 
     In other words, the mobile phone  100  is able to change the luminance of the touch panel  110  to a luminance corresponding to the actual surrounding brightness, and is able to secure visibility. 
     The luminance control module  153  has been described as one that, in a case in which the brightness measured by the optical sensor  120  changes between the first condition and the second condition, when there is no specific contact on the touch panel  110  in the period from the second time period before the change to the third time period after the change, waits for the time window to elapse and then changes the luminance of the touch panel  110  to the luminance corresponding to the post-change condition (refer to task s 5 : NO, task s 10 : NO, task s 11 : YES, task s 7 : YES, and task s 9  in  FIG. 5 ). 
     The luminance control module  153  is described above as one that, in a case in which the brightness measured by the optical sensor  120  changes between the first condition and the second condition, when there is specific contact on the touch panel  110  in the period from the second time period before the change to the third time period after the change, extends the time window from the first time period to the fourth time period (refer to task s 5 : YES, task s 10 : YES, and task s 6  in  FIG. 5 ). 
     In the embodiment shown in  FIG. 6 , the luminance control module  153  does not extend the time window, and in a case in which the brightness measured by the optical sensor  120  changes between the first condition and the second condition, when there is no contact (including contact other than specific contact) on the touch panel  110  in the period from the second time period before the change to the third time period after the change, it is able to issue an instruction to change the luminance of the touch panel  110  to the luminance corresponding to the post-change condition without waiting for the time window to elapse. The second embodiment will be described with a focus on modules that have been changed compared to the mobile phone  100  of the first embodiment. Items assigned the same symbol numbers and numbers as those in the first embodiment indicate functions or processes similar to those described in the first embodiment. 
       FIG. 7  is an illustration of an exemplary functional block diagram  200  (system  200 ) of a mobile electronic device such as a mobile phone  200  according to an embodiment of the disclosure. The system  200  may have functions, material, and structures that are similar to the system  100 . Therefore common features, functions, and elements may not be redundantly described here. 
     The mobile phone  200  comprises the touch panel  110 , the optical sensor  120 , the first clock module  130 , the second clock module  131 , the third clock module  132 , a memory module  210 , and a control module  220 . The mobile phone  200  differs from the mobile phone  100  in that it has the memory module  210  and the control module  220  instead of the memory module  140  and the control module  150  of the mobile phone  100 . 
     The memory module  210  is a memory region capable of storing the contact information table  10 . The memory module  210  differs from the memory module  140  in that it does not store the positional information  20 . 
     The control module  220  comprises the contact detection module  151 , the condition determination module  152 , and a luminance control module  221 . This differs from the control module  150  in that it has the luminance control module  221  instead of the luminance control module  153  comprised in the control module  150 . 
     Details of the luminance control module  221  is described in more detail with reference to  FIG. 8  below. 
       FIG. 8  is an illustration of an exemplary flowchart showing a luminance control process  800  (process  800 ) that can be performed by a mobile electronic device such as the mobile phone  200  according to an embodiment of the disclosure. The various tasks performed in connection with the process  800  may be performed by software, hardware, firmware, a computer-readable medium having computer executable instructions for performing the process method, or any combination thereof. The process  800  may be recorded in a computer-readable medium such as a semiconductor memory, a magnetic disk, an optical disk, and the like, and can be accessed and executed, for example, by a computer CPU such as the processor module  160  in which the computer-readable medium is stored. 
     The first time period, the second time period, and the third time period are indicated as “t 1 ”, “t 2 ”, and “t 3 ”, respectively. 
     As with the mobile phone  100 , when the power of the mobile phone  200  is turned ON, the processes of task s 1 , task s 2 , and task s 4  are performed. In other words, the control module  220  performs an initialization process of the contact information table  10 . The luminance control module  221  performs a start process for illumination at the luminance corresponding to the determination result from the condition determination module  152 , as well as a determination process regarding whether the determination result from the condition determination module  152  has changed (task s 1 , task s 2 ). If the determination result from the condition determination module  152  has changed (task s 2 : YES), the luminance control module  221  performs a clock starting process and an acquisition process for the current time (task s 4 ). 
     Based on the contact information table  10  in the memory module  210 , the luminance control module  221  determines whether or not there has been contact on the touch panel  110  in the period from the second time period before the acquired time to the acquired time (task  13 ). If there is contact information including a time from the period from the second time period before the acquired time to the acquired time, the luminance control module  221  makes a positive determination (task s 13 : YES). The luminance control module  221  acquires the time period being kept by the first clock module  130 , and determines whether or not the first time period has elapsed (task s 14 ). 
     If the first time period has elapsed (task s 14 : YES), the luminance control module  221  performs a process to change the illumination to the luminance corresponding to the most recent determination result from the condition determination module  152  (task s 9 ). The luminance control module  221  repeats the processes from task s 2 . 
     If the first time period has not elapsed (task s 14 : NO), as with the mobile phone  100 , the luminance control module  221  performs a determination process regarding whether the determination result from the condition determination module  152  has changed (task s 8 ). 
     On the other hand, in task s 13 , if there is no contact information including a time from the period from the second time period before the time acquired by the luminance control module  221  to the acquired time, the luminance control module  221  makes a negative determination (task s 13 : NO). Based on the contact information table  10  in the memory module  210 , the luminance control module  221  determines whether or not there was contact on the touch panel  110  subsequent to the time acquired in task s 4  (task s 15 ). 
     If there is contact information including a time subsequent to the time acquired in task s 4 , the luminance control module  221  makes a positive determination (task s 15 : YES). The luminance control module  221  proceeds to the process of (task s 14 ). 
     If there is no contact information including a time subsequent to the time acquired in task s 4 , the luminance control module  221  makes a negative determination (task s 15 : NO). The luminance control module  221  determines whether or not the third time period has elapsed (task s 16 ). 
     If there has been a notification from the third clock module  132  that the third time period has been kept, the luminance control module  221  determines that the third time period has elapsed (task s 16 : YES) and proceeds to the process of (task s 9 ). 
     If there has been no notification from the third clock module  132  that the third time period has been kept, the luminance control module  221  determines that the third time period has not elapsed (task s 16 : NO). The luminance control module  221  performs a determination process regarding whether the determination result from the condition determination module  152  has changed (task s 12 ). 
     In the above, the mobile electronic device of the present invention has been described based on the first embodiment and the second embodiment, but it is possible to make modifications such as the following, and of course, the present invention is not limited to a mobile phone such as those described in the first embodiment and the second embodiment. 
     The mobile phone  200  has been described as differing from the mobile phone  100  in that: (a) it does not extend the time window; (b) it is not limited to specific contact; and (c) it changes the luminance of the touch panel  110  to the luminance corresponding to the post-change condition without waiting for the time window to elapse. 
     However, the mobile phone  200  may be a mobile phone in which at least 1 of the above points (a) through (c) has been applied to the mobile phone  100 . For example, the mobile phone  200  may be a mobile phone in which only the item (a) has been applied from among the items (a) through (c). 
     The second embodiment has been described as one in which, if the brightness measured by the optical sensor  120  changes between the first condition and the second condition, the luminance of the touch panel  110  is controlled based on whether or not there was contact on the touch panel  110  in all periods from the second time period before the change to the third time period after the change. However, the luminance of the touch panel  110  may be controlled based on whether or not there was contact in either the period from the second time period before the change to the change, or the period from the change to the third time period after the change. 
     The first embodiment has been described as one in which, if the brightness measured by the optical sensor  120  changes between the first condition and the second condition, when there is specific contact on the touch panel  110  in the period between the second time period before the change to the third time period after the change, the luminance control module  153  extends the time window. 
     However, without being limited to all periods from the second time period before the change to the third time period after the change, the luminance control module  153  may extend the time window based on whether or not there was specific contact in either the period from the second time period before the change to the change, or the period from the change to the third time period after the change. For example, the luminance control module  153  may determine whether to extend the time window based on whether or not there was specific contact in the period from the second time period before the change to the change, from among all periods from the second time period before the change to the third time period after the change. 
     In the first embodiment and the second embodiment, the brightness measured by the optical sensor has been described as having the two conditions of the first condition and the second condition, but it may have three or more conditions. 
     In this case, if the number of conditions is defined as n (n being a natural number that is 3 or greater), (n−1) number of threshold values is required. For example, if the number of conditions n is 3, 2 threshold values are required. For example, a second threshold value (e.g., a value corresponding to “5,000 lux”) that is greater than the prescribed threshold value described in the embodiments and variations (e.g., a value corresponding to “1,000 lux”; described as the “first threshold value” in this section) is determined, and the conditions in which the brightness measured by the optical sensor  120  is equal to or greater than the second threshold value, less than the second threshold value and equal to or greater than the first threshold value, and less than the first threshold value may be defined as the third condition, the first condition, and the second condition, respectively. 
     In the following, operations of a mobile phone  300  in a case in which there is the third condition in addition to the first and second conditions are described. 
       FIG. 9  is an illustration of an exemplary flowchart showing a luminance control process  900  (process  900 ) that can be performed by a mobile phone  300  according to an embodiment of the disclosure.  FIG. 10  is an illustration of an exemplary functional block diagram of the mobile phone  300  according to an embodiment of the disclosure. 
     The various tasks performed in connection with the process  900  may be performed by software, hardware, firmware, a computer-readable medium having computer executable instructions for performing the process method, or any combination thereof. The process  900  may be recorded in a computer-readable medium such as a semiconductor memory, a magnetic disk, an optical disk, and the like, and can be accessed and executed, for example, by a computer CPU such as the processor module  160  in which the computer-readable medium is stored. 
     The luminance control process of the mobile phone  300  differs in that, instead of the processes of (task s 2 , task s 8 , and task s 12 ) of the luminance control process of the mobile phone  100  (refer to  FIG. 5 ), it comprises the processes of (task s 20 ), (task s 21 ), and (task s 23 ), and has added the processes of (task s 22 ) and (task s 24 ). 
     Consequently, in the following, the luminance control process of the mobile phone  300  will be described with a focus on these areas of difference. Furthermore, the mobile phone  300  may have the functions of the mobile phone  100  and the mobile phone  200 . For example, the control module  301  described later may have the functions of the control module  150  or the control module  220 . In  FIG. 9  and  FIG. 10 , items assigned the same symbol numbers and numbers as those in the first embodiment or the second embodiment indicate functions or processes similar to those described in the first embodiment or the second embodiment. 
     As with the mobile phone  100 , when the power of the mobile phone is turned ON, the control module  301  of the mobile phone  300  performs an initialization process of the contact information table  10 . The condition determination module  302  determines whether the brightness measured by the optical sensor  120  is in the first state, the second state, or the third state. The luminance control module  303  specifies the luminance corresponding to the determination result (first luminance, second luminance, or third luminance) for the illumination module  113  of the touch panel  110 , and the illumination module  113  starts illumination with the specified luminance (task s 1 ). 
     Next, the luminance control module  303  performs a determination process regarding whether the determination result from the condition determination module  302  has changed (task s 20 ). 
     If there has been a change from the first condition to either the second or third condition, or from the second condition to either the first or third condition, or from the third condition to either the first or second condition (task s 20 : YES), as with the luminance control module  153 , the luminance control module  303  performs a setting process for the time window, a start process for timekeeping, and an acquisition process for the current time (task s 3 , task s 4 ). 
     Next, as with the luminance control module  153 , the luminance control module  303  performs a determination process regarding whether or not there was contact on the touch panel  110  in the period from the second time period before the acquired time to the acquired time (task s 5 ). If there was contact (task s 5 : YES), the luminance control module  303  performs a resetting process for the time window and a determination process regarding whether or not the time window has elapsed (task s 6 , task s 7 ). 
     If the time window has elapsed (task s 7 : YES), as with the luminance control module  153 , the luminance control module  303  specifies the luminance corresponding to the most recent determination result from the condition determination module  302  (first luminance, second luminance, or third luminance) for the illumination module  113  of the touch panel  110 . The illumination module  113  changes to the specified luminance and performs illumination (task s 9 ), and the processes from task s 20  are repeated. 
     If the time window has not elapsed (task s 7 : NO), as with the luminance control module  153 , the luminance control module  303  performs a determination process regarding whether the determination result from the condition determination module  302  has changed (task s 21 ). If the determination result has changed (task s 21 : YES), the luminance control module  303  determines whether or not the post-change condition is the condition corresponding to the current luminance (task s 22 ). 
     For example, the luminance control module  303  makes a positive determination (task s 22 : YES) if, when the current luminance is the first luminance, the post-change condition is the first condition, or if, when the current luminance is the second luminance, the post-change condition is the second condition, or if, when the current luminance is the third luminance, the post-change condition is the third condition. 
     If a positive determination is made (task s 22 : YES), the processes from (task s 20 ) are performed, and if a negative determination is made (task s 22 : NO), the processes from (task s 3 ) are performed. 
     On the other hand, in (task s 5 ), if there was no contact on the touch panel  110  in the period from the second time period before the acquired time to the acquired time (task s 5 : NO), as with the luminance control module  153 , the luminance control module  303  performs a determination process regarding whether or not there was contact on the touch panel  110  subsequent to the time acquired in (task s 4 , task s 10 ). 
     If there was contact (task s 10 : YES), the luminance control module  303  proceeds to the process of task s 6 . If there was no contact (task s 10 : NO), as with the luminance control module  153 , the luminance control module  303  performs a determination process regarding whether or not the third time period has elapsed (task s 11 ). 
     As with the luminance control module  153 , if the third time period has elapsed (task s 11 : YES), the luminance control module  303  proceeds to the process of (task s 7 ). If the third time period has not elapsed (task s 11 : NO), the luminance control module  303  performs a determination process regarding whether the determination result from the condition determination module  302  has changed (task s 23 ). 
     If the determination result has changed (task s 23 : YES), as with the process of (task s 22 ), a determination is made as to whether or not the post-change condition is the condition corresponding to the current luminance (task s 24 ). 
     If a positive determination is made (task s 24 : YES), the processes from (task s 20 ) are performed, and if a negative determination is made (task s 24 : NO), the processes from (task s 3 ) are performed. 
     Furthermore, in  FIG. 5  and  FIG. 8 , it is described that if the condition changed in task s 8  (task s 8 : YES) or if the condition changed in task s 12  (task s 12 : YES), the luminance control module  303  repeats the processes from (task s 2 ), but it may perform the processes from task s 3 . 
     However, in this case, in the process of task s 9 , if the post-change luminance matches the current luminance, the luminance control module  303  may maintain the current luminance and make no change. 
     In the above description, the process of task s 22  is performed if the condition has changed in (task s 21 ) (task s 21 : YES), and the process of task s 24  is performed if the condition has changed in task s 23  (task s 23 : YES), but if the condition has changed in (task s 21 ) (task s 21 : YES) or if the condition has changed in task s 23  (task s 23 : YES), the processes from task s 3  may be performed without performing the processes of (task s 22 ) or (task s 24 ). 
     In this case, in the process of task s 9 , if the post-change luminance matches the current luminance, the luminance control module  303  may maintain the current luminance and make no changes. 
     The above has been a description on the luminance control process of the mobile phone  300 . 
     In the descriptions of the first embodiment and the second embodiment, if the brightness measured by the optical sensor  120  changes from being equal to or greater than a prescribed threshold value (e.g., a value corresponding to “1,000 lux”) to being less than that threshold value, the condition determination module determines that it has changed from the first condition to the second condition, and if the brightness measured by the optical sensor  120  changes from being less than the threshold value to being equal to or greater than the threshold value, the condition determination module determines that it has changed from the second condition to the first condition. 
     However, if the amount of decrease within a unit time in the brightness measured by the optical sensor  120  changes from being less than the prescribed threshold value (e.g., a value corresponding to “1,000 lux”) to being equal to or greater than the threshold value, the condition determination module may determine that it has changed from the first condition to the second condition. If the amount of increase within a unit time in the brightness measured by the optical sensor  120  changes from being less than the threshold value to being equal to or greater than the threshold value, the condition determination module may determine that it has changed from the second condition to the first condition. 
     The prescribed threshold value (e.g., a value corresponding to “1,000 lux”) shown in the first embodiment and the second embodiment is one example and may be another value, and it may be, for example, set by the user to any value. 
     In the first embodiment and the second embodiment, the first time period is described as “about 3 seconds”, the second and third time period are described as “about 2 seconds”, and the fourth time period is described as “about 5 seconds”, but these are examples, and each time period may be determined to meet the conditions of “the fourth time period&gt;the first time period&gt;the second and first time periods&gt;the third time period”. Alternatively, the first time period, the second time period, the third time period, and the fourth time period may be set by the user to meet the conditions of “the fourth time period&gt;the first time period&gt;the second and first time periods&gt;the third time period”. 
     The second time period and the third time period may be identical time periods or different time periods. 
     In the first embodiment and the second embodiment, the optical sensor  120  is described as being arranged on the lower module (near the microphone  2 ) of the touch panel  110 , but the arrangement of the optical sensor  120  may be changed appropriately. However, because the optical sensor  120  is used to change the luminance of the touch panel  110  according to the actual surrounding brightness, it is preferably arranged near the touch panel  110 . 
     Furthermore, if the arrangement of the optical sensor  120  is changed, the specific position  21  indicated by the positional information  20  may be changed to match that arrangement. 
     In the first embodiment and the second embodiment, the specific position  21  indicated by the positional information  20  is described as being a rectangular area, and the positional information  20  is described as being set in advance. However, at the start of operation of the mobile phone of the first embodiment and the second embodiment, for example, it is possible to have the user perform operations on the touch panel  110  multiple times, identify a position on the touch panel  110  where the brightness measured by the optical sensor  120  decreases by a prescribed threshold value or more, and store the identified position as the positional information  20  in the memory module  140 . 
     This positional information  20  may be a rectangular area determined in a way to comprise the identified position, or may be a group of 1 or more coordinate values indicating the identified position. 
     The mobile phone of the first embodiment and the second embodiment has been described as being a straight-type mobile phone, but it may be a mobile phone with another external appearance, such as a folding-type or sliding-type mobile phone. 
     In a folding-type or sliding-type mobile phone, the chassis on which the touch panel  110  is arranged and the chassis on which the optical sensor  120  is arranged may be the same chassis or different chasses. 
     The mobile phone of the first embodiment and the second embodiment have been described as including one set of the display module  111  and the illumination module  113 , but it may further comprise one or more sets of display modules and illumination modules. The illumination by each illumination module may be controlled in a manner similar to that described in the first embodiment and the second embodiment. 
     The one or more sets of display modules and illumination modules added in this variation may configure the touch panel. 
     The input module of the touch panel  110  of the first embodiment and the second embodiment has been described as being realized by a capacitive touch sensor, but for the capacitive touch sensor, any appropriate type may be used, such as: a projection-type that forms multiple electrode patterns on a substrate of plastic or glass, etc. and makes distinctions by measuring the ratios of the amount of current from multiple electrode patterns near a contact point; or a surface-type that is configured to comprise a conducting layer and a substrate, provides electrodes on the corners of the substrate, forms an even electric field created by the conducting layer, and distinguishes contact positions by measuring the ratios of the amount of current from the electrodes on the corners caused by contact by a finger, etc. 
     The input module of the touch panel  110  is not limited to being realized by a capacitive touch sensor, and may be realized by, for example: an electromagnetic induction system using a specialized pen, such as an electronic pen; a matrix switch system composed of a two-layer structure of transparent electrodes; a resistive film system that applies a voltage to one of two resistive films and detects a voltage corresponding to the operated position on the other resistive film; a surface acoustic wave system that detects the bouncing back of oscillating waves through voltage changes in piezoelectric elements and detects contact by a finger, etc.; an infrared system that detects a position touched by a finger, etc. based on infrared rays that have been shielded; or an optical sensor system that builds in optical sensors into a screen and detects contact positions. 
     In various embodiments, the shape of the LCD of the display module of the touch panel  110  is described as a roughly rectangular shape, but it may be, for example, a circular shape or another polygonal shape. 
     For the various components described in the first embodiment and the second embodiment, the functions thereof may be realized through cooperation with a processor comprised in the mobile phone. 
     A program for causing the processor to execute the luminance control processes described in the first embodiment and the second embodiment (refer to  FIG. 5  and  FIG. 8 ) may be stored in a storage medium and circulated and distributed via various communication paths, etc. Examples of this storage medium comprise an IC card, a hard disk, an optical disk, a flexible disk, a ROM, or a flash memory, etc. The circulated and distributed program is provided for use by being stored in a memory, etc. that is readable by the processor in the equipment, and the various functions of the mobile phone described in the first embodiment and the second embodiment are realized when the processor executes this program. 
     Part or all of the details of the present disclosure may be combined and applied to the mobile phone  100 , the mobile phone  200 , and the mobile phone  300 , with no distinction between the first embodiment and the second embodiment. 
     In the following, the configuration of a mobile electronic device according to an illustrative embodiment of the present invention will be described, as will variations thereof and the respective effects of each. 
     The mobile electronic device according to this illustrative embodiment of the present embodiment is a mobile electronic device including functions for adjusting the luminance of a touch panel according to the surrounding brightness, and comprises: an optical sensor that is arranged near the touch panel and measures the surrounding brightness; and a luminance control module that, if the brightness measured by the optical sensor changes from a first condition to a second condition, in which it decreases by an amount equal to or greater than a threshold value for controlling and changing the luminance of the touch panel, maintains the luminance of the touch panel at a luminance corresponding to the first condition if, by the time a first time period elapses from the change, the brightness measured by the optical sensor changes from the second condition to the first condition, or controls the luminance of the touch panel to change to a luminance corresponding to the second condition if, by the time the first time period elapses from the change, the brightness measured by the optical sensor has not changed from the second condition to the first condition. 
     Generally, a single user operation on the touch panel (e.g., operations such as a click, a double-click, or a drag) often ends within a relatively short time period. 
     Consequently, if the optical sensor enters the shadow of the hand of the user due to a user operation on the touch panel and the brightness measured by the optical sensor changes from the first condition to the second condition, the optical sensor is likely to return to measuring the actual surrounding brightness within a relatively short time period after the change. 
     Therefore, if the brightness measured by the optical sensor changes from the first condition to the second condition due to a user operation on the touch panel, when there is no change in the actual surrounding brightness, the brightness measured by the optical sensor returns to the first condition, and when the actual surrounding brightness has decreased, the brightness measured by the optical sensor is maintained in the second condition. 
     In a case in which the brightness measured by the optical sensor changes from the first condition to the second condition, when the brightness measured by the optical sensor returns to the first condition within a first time period from the change, the mobile electronic device maintains the luminance of the touch panel at the luminance corresponding to the first condition, and when the brightness measured by the optical sensor is maintained in the second condition throughout the first time period from the change, the mobile electronic device changes the luminance of the touch panel to the luminance corresponding to the second condition. 
     Consequently, by using an appropriate first time period, according to this mobile electronic device, it is possible to prevent cases of inappropriate control of the luminance of the display screen caused by user operations on the touch panel, and to secure visibility of the display screen if the actual surrounding brightness changes during the user operation on the touch panel. 
     (b) If the brightness measured by the optical sensor has changed from the first condition to the second condition, when there is no contact on the touch panel in the period from the second time period before the change to the change, the luminance control module may change the luminance of the touch panel to the luminance corresponding to the second condition without performing the control. 
     If there is no contact on the touch panel in the period from the second time period before the brightness measured by the optical sensor changes to the second condition to the change, the cause of the change is likely to be a decrease in the actual surrounding brightness. 
     According to this mobile electronic device, in addition to enjoying the above effects of (a), if there is a high likelihood that the actual surrounding brightness has decreased, it is possible to immediately change the luminance of the touch panel to the luminance corresponding to the second condition and secure visibility without waiting for the first time period to elapse from the change to the second condition. 
     (c) If the brightness measured by the optical sensor changes from the first condition to the second condition and there is no contact on the touch panel in the period from the second time period before the change to the change, and only if there has been no contact on the touch panel by the end of a third time period that is no longer than the first time period from the change, the luminance control module may change the luminance of the touch panel to the luminance corresponding to the second condition. 
     If there has been no contact on the touch panel in the periods before and after the brightness measured by the optical sensor changes to the second condition, the cause of the change is very likely to be a decrease in the actual surrounding brightness. 
     According to this mobile electronic device, in addition to enjoying the above effects of (a), if there is a very high likelihood that the actual surrounding brightness has decreased, it is possible to change the luminance of the touch panel to the luminance corresponding to the second condition and secure visibility once the third time period that is shorter than the first time period elapses, without waiting for the first time period to elapse from the change to the second condition. 
     (d) The optical sensor is arranged on approximately the same plane as the display surface of the touch panel, and the mobile electronic device further comprises a memory module that stores positional information indicating a position on the touch panel where the brightness measured by the optical sensor may decrease due to contact. If the brightness measured by the optical sensor changes from the first condition to the second condition, when there has been contact on the position on the touch panel indicated by the positional information in the period from the second time period before the change to the change, the luminance control module changes the first time period to a longer time period and performs the control, and when there has been no contact on the position on the touch panel indicated by the positional information, the luminance control module may change the luminance of the touch panel to the luminance corresponding to the second condition without performing the control. 
     In the period from the second time period before the brightness measured by the optical sensor changes to the change, if there is no contact on a position on the touch panel That may decrease the brightness measured by the optical sensor, the cause of the change is likely to be a decrease in the actual surrounding brightness. 
     According to this mobile electronic device, in addition to enjoying the above effects of (a), if there is a high likelihood that the actual surrounding brightness has decreased, it is possible to immediately change the luminance of the touch panel to the luminance corresponding to the second condition and secure visibility without waiting for the first time period to elapse from the change to the second condition. 
     (e) The mobile electronic device may further comprise a condition determination module that: if the brightness measured by the optical sensor changes from being equal to or greater than the threshold value to being less than the threshold value, determines that it has changed from the first condition to the second condition; and if the brightness measured by the optical sensor changes from being less than the threshold value to being equal to or greater than the threshold value, determines that it has changed from the second condition to the first condition. 
     According to an embodiment, because it is possible to determine whether or not the brightness measured by the optical sensor has changed between the first condition and the second condition by simply setting a threshold value, implementation is easy. 
     (f) The mobile electronic device may further comprise a condition determination module that: if the amount of decrease within a unit time in the brightness measured by the optical sensor changes from being less than the threshold value to being equal to or greater than the threshold value, determines that it has changed from the first condition to the second condition; and if the amount of increase within a unit time in the brightness measured by the optical sensor changes from being less than the threshold value to being equal to or greater than the threshold value, determines that it has changed from the second condition to the first condition. 
     According to an embodiment, if the amount of change (amount of decrease or increase) within a unit time in the brightness measured by the optical sensor changes by an amount equal to or greater than the threshold value, it is determined that the brightness measured by the optical sensor has changed between the first condition and the second condition. 
     Consequently, according to this mobile electronic device, it is possible to change the luminance of the touch panel according to the actual brightness without setting an absolute value of the brightness measured by the optical sensor as the threshold value. 
     (g) Furthermore, in a case in which the brightness measured by the optical sensor changes from the second condition to the first condition, if the brightness measured by the optical sensor changes from the first condition to the second condition by the time the first time period elapses from the change, the luminance control module may maintain the luminance of the touch panel at the luminance corresponding to the second condition, and if there is no change from the first condition to the second condition, the luminance control module may control the luminance of the touch panel to change to the luminance corresponding to the first condition. 
     In a case in which the brightness measured by the optical sensor has changed from the second condition to the first condition, if the brightness measured by the optical sensor returns to the second condition within the first time period from the change, the mobile electronic device maintains the luminance of the touch panel at the luminance corresponding to the second condition, and if the brightness measured by the optical sensor is maintained in the first condition throughout the first time period from the change, the mobile electronic device changes the luminance of the touch panel to a luminance corresponding to the first condition. 
     Consequently, by using an appropriate first time period, according to this mobile electronic device, it is possible to prevent cases of inappropriate control of the luminance of the display screen caused by reflected light, etc. hitting the optical sensor, and to secure visibility of the display screen if the actual surrounding brightness becomes high while the reflected light, etc. is hitting the optical sensor. 
     The luminance control method of the mobile electronic device may be realized by the mobile phone described in, for example, the first embodiment or the second embodiment (in particular, refer to the procedures of the luminance control processes described with reference to  FIG. 5  and  FIG. 8 ). 
     In this document, the terms “computer program product”, “computer-readable medium”, and the like may be used generally to refer to media such as, for example, memory, storage devices, or storage unit. These and other forms of computer-readable media may be involved in storing one or more instructions for use by the processor module  160  and/or the control module  150 / 220 / 301  to cause the processor module  160  and/or the control module  150 / 220 / 301  to perform specified operations. Such instructions, generally referred to as “computer program code” or “program code” (which may be grouped in the form of computer programs or other groupings), when executed, enable a method of using a system. 
     Terms and phrases used in this document, and variations hereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing: the term “including” should be read as meaning “including, without limitation” or the like; the term “example” is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof; and adjectives such as “conventional,” “traditional,” “normal,” “standard,” “known” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future. 
     Likewise, a group of items linked with the conjunction “and” should not be read as requiring that each and every one of those items be present in the grouping, but rather should be read as “and/or” unless expressly stated otherwise. Similarly, a group of items linked with the conjunction “or” should not be read as requiring mutual exclusivity among that group, but rather should also be read as “and/or” unless expressly stated otherwise. 
     Furthermore, although items, elements or components of the present disclosure may be described or claimed in the singular, the plural is contemplated to be within the scope thereof unless limitation to the singular is explicitly stated. The presence of broadening words and phrases such as “one or more,” “at least,” “but not limited to” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent. The term “about” when referring to a numerical value or range is intended to encompass values resulting from experimental error that can occur when taking measurements.