Abstract:
A mobile electronic apparatus includes a memory that stores a search range of an object and a processor that executes a process. The process includes acquiring a moving speed of the mobile electronic apparatus, determining the search range of the object on a basis of the moving speed, detecting the object existing within the search range, detecting whether a display unit of the mobile electronic apparatus is in an active state, and notifying that the object is detected when the display unit is detected to be in the active state and the object existing within the search range is detected.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2011-162528 filed on Jul. 25, 2011, the entire contents of which are incorporated herein by reference. 
       FIELD 
       [0002]    The embodiments discussed herein are related to a mobile electronic apparatus, a danger notifying method, and a medium for storing a program. 
       BACKGROUND 
       [0003]    In recent years, more users of mobile electronic apparatuses, such a mobile phone, keep looking at a display unit of the mobile phone while walking, and many users of the mobile electronic apparatus collide against obstacles, for example, oncoming walkers. There is a proposition of a mobile electronic apparatus that detects an obstacle to be avoided by using a mounted camera or the like to avoid collision with the obstacle. 
       PATENT DOCUMENT 
       [0004]    Japanese Laid-open Patent Publication No. 2004-304297 
         [0005]    Regarding the conventional mobile electronic apparatus, a detection range for detecting an obstacle to be avoided is fixed regardless of a walking speed of a user. As a result, depending on the walking speed of the user, obstacle collision may not be sufficiently avoided. 
         [0006]    The disclosed technique avoids collision that occurs when the user of the mobile electronic apparatus is walking while looking at a display unit. 
       SUMMARY 
       [0007]    According to an aspect of the invention, a mobile electronic apparatus includes a memory that stores a search range of an object and a processor that executes a process. The process includes acquiring a moving speed of the mobile electronic apparatus, determining the search range of the object on a basis of the moving speed, detecting the object existing within the search range, detecting whether a display unit of the mobile electronic apparatus is in an active state, and notifying that the object is detected when the display unit is detected to be in the active state and the object existing within the search range is detected. 
         [0008]    The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
         [0009]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1  is an entire diagram of a mobile phone according to a first embodiment; 
           [0011]      FIG. 2  is a back side diagram of a lower housing according to the first embodiment; 
           [0012]      FIG. 3  is a hardware configuration diagram of the mobile phone according to the first embodiment; 
           [0013]      FIG. 4  is a functional block diagram of the mobile phone according to the first embodiment; 
           [0014]      FIG. 5  is a graph of a relational formula of an activity intensity and a walking speed according to the first embodiment; 
           [0015]      FIG. 6  is a threshold value table in which the walking speed corresponds to a threshold value according to the first embodiment; 
           [0016]      FIG. 7  is a flowchart of a collision avoiding process according to the first embodiment; 
           [0017]      FIG. 8  is an explanatory diagram of an idea of foot landing period of a walking user according to the first embodiment; 
           [0018]      FIG. 9  is a functional block of a mobile phone according to a second embodiment; 
           [0019]      FIG. 10  is a flowchart of a display process of a collision avoiding method according to the second embodiment; 
           [0020]      FIGS. 11A and 11B  are overview diagrams illustrating a display content of the mobile phone according to the second embodiment; 
           [0021]      FIGS. 12A and 12B  are overview diagrams illustrating a display content of a display of the mobile phone according to the second embodiment; and 
           [0022]      FIG. 13  is a back side diagram of a lower housing according to a third embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
       [0023]    With reference to  FIGS. 1 to 8 , a first embodiment will be described. 
         [0024]    [Hardware of Mobile Phone] 
         [0025]      FIG. 1  is an entire diagram of a mobile phone  1  according to the first embodiment.  FIG. 2  is a back side diagram of a lower housing  20  according to the first embodiment.  FIG. 3  is a hardware configuration diagram of the mobile phone  1  according to the first embodiment. 
         [0026]    As illustrated in  FIGS. 1 to 3 , the mobile phone  1  according to the first embodiment includes an upper housing  10  that is touched to a user&#39;s ear and a lower housing  20  that is held by a user&#39;s hand. The upper housing  10  and the lower housing  20  are coupled with each other to be foldable at a hinge part  30  in the center. As described below, a surface that is hidden when the mobile phone  1  with the upper housing  10  and the lower housing  20  are folded is referred to as a surface, and a surface that is exposed when the mobile phone is folded is referred to as a back surface. 
         [0027]    The mobile phone  1  includes a Central Processing Unit (CPU)  51 , a memory  52 , a communication unit  53 , a flash memory  54 , a display  55 , a speaker  56 , a vibrator  57 , a camera  58 , an operation key  59 , a microphone  60 , a distance meter  61 , an acceleration meter  62 , a mouth piece  64 , and an ear piece  63 . 
         [0028]    The CPU  51 , the memory  52 , the communication unit  53 , the flash memory  54 , the display  55 , the speaker  56 , the vibrator  57 , the camera, the operation key  59 , the microphone  60 , the distance meter  61 , and the acceleration meter  62  are coupled with each other by a bus  65 . 
         [0029]    By reading out various programs stored in the flash memory  54 , developing the programs in the memory  52 , and executing the programs developed in the memory  52 , the CPU  51  achieves various functions described below. 
         [0030]    The memory  52  stores the various programs read out from the flash memory  54  by the CPU  51  and the data that is used to execute the various functions by the CPU  51 . The communication unit  53  is used as an interface that is radio-coupled to a mobile phone network. 
         [0031]    The flash memory  54  stores various programs such as a data acquiring program  71 , a whole control program  72 , an input control program  73 , an output control program  74 , a speed calculating program  75 , a threshold value acquiring program  76 , and a data storing program  77 . Regarding the flash memory  54 , the area for arbitrary use is used as a data storage unit  150  described below. 
         [0032]    The display  55  is mounted on the surface of the upper housing  10  and displays, for example, various programs such as a menu display. The display  55  displays obstacle information that notifies the user of the existence of the obstacle described below. 
         [0033]    The speaker  56 , which is provided inside the upper housing  10 , emits a voice from, for example, a conversation destination through the ear piece  63 . Furthermore, the speaker  56  emits an alarm sound to notify the user of the existence of the obstacle. 
         [0034]    The vibrator  57  generates vibration to notify the user of an incoming call. Furthermore, the vibrator  57  generates vibration to notify the user of the existence of the obstacle, for example. 
         [0035]    The camera  58 , which is mounted on the lower housing  20 , photographs the front of the lens  58   a  allocated on the back surface of the lower housing  20 . The operation key  59  is used as, for example, a push button that is used to input a telephone number or as a selection button that is used to select a function. The microphone  60  is provided inside the lower housing  20  and receives voice from a user through the ear piece  63 . 
         [0036]    The distance meter  61  meters the distance to an obstacle. The distance meter  61  may employ an ultrasonic method, an optical method, or the like. For example, a stereo camera  611  includes a lens  61   a  and a lens  61   b  and photographs the front of the lenses  61   a  and  61   b,  respectively. The acceleration meter  62 , which is provided inside the upper housing  10  or the lower housing  20 , detects (samples) acceleration values Xi, Yi, and Zi in XYZ directions that are mutually orthogonal in a predetermined period of time. 
         [0037]    [Functional Block of Mobile Phone] 
         [0038]      FIG. 4  is a functional block diagram of the mobile phone  1  according to the first embodiment. 
         [0039]    As illustrated in  FIG. 4 , the mobile phone  1  includes a control unit  100 , a display start determining unit  110 , a distance metering unit  120 , an activity intensity calculating unit  130 , a communication unit  140 , and a data storage unit  150 . The control unit  100  further includes a whole control unit  101 , a data acquiring unit  102 , an input control unit  103 , and an output control unit  104 . 
         [0040]    The whole control unit  101  includes a walking determining unit  101   a,  a speed calculating unit  101   b,  a threshold value acquiring unit  101   c,  and a comparing unit  101   d.  The various functions of the whole control unit  101  are executed by the CPU  51  based on the whole control program  72 . 
         [0041]    Based on the below-described activity intensity stored in the data storage unit  150  and on the existence of periodicity and the acceleration value and the frequency stored in the data storage unit  150 , the walking determining unit  101   a  determines whether or not the user of the mobile phone  1  is walking 
         [0042]    Based on the activity intensity calculated by the activity intensity calculating unit  130  and on the below-described parameter stored in the data storage unit  150 , the speed calculating unit  101   b  acquires the maximum value of walking speed of the user of the mobile phone  1 . In the first embodiment, since the walking speed is calculated based on the activity intensity, walking that is almost like stepping is measured as the activity intensity. Therefore, according to the first embodiment, the maximum value of walking speed indicates the walking speed in a case where the user is assumed to be walking forward. The details will be described below. 
         [0043]    Based on the walking speed acquired by the speed calculating unit  101   b  and on the threshold table described below stored in the data storage unit  150 , the threshold value acquiring unit  101   c  acquires the distance, as a threshold value, to detect an obstacle to be avoided. 
         [0044]    The comparing unit  101   d  compares the distance to the obstacle to be avoided metered by the distance metering unit  120  to the threshold value acquired by the threshold value acquiring unit  101   c.  That is, the comparing unit  101   d  detects an obstacle existing closer than the threshold value in cooperation with the distance metering unit  120 . 
         [0045]    The data acquiring unit  102  sends a request to start processing to the display start determining unit  110 , the distance metering unit  120 , and the activity intensity calculating unit  130 , respectively, and receives processing results from the display start determining unit  110 , the distance metering unit  120 , and the activity intensity calculating unit  130 , respectively. The data acquiring unit  102  is achieved by the CPU  51  based on the data acquiring program  71 . 
         [0046]    The input control unit  103  controls the input device such as the operation key  59  and the like. The input control unit  103  is achieved by the CPU  51  based on the input control program  73 . 
         [0047]    The output control unit  104  controls output devices such as the display  55 , the speaker  56 , and the vibrator  57 . The output control unit  104  is achieved by the CPU  51  based on the output control program  74 . 
         [0048]    Based on the display start information stored in the data storage unit  150 , the display start determining unit  110  determines whether or not the display  55  is in an active state. The active state means that a power of the display  55  or a back light of the display  55  is turned on. Therefore, the display start information means whether the power of the display  55  or the back light (not illustrated) of the display  55  is turned on or off. Based on the device driver of the display  55 , the display start information stored in the data storage unit  150  is rewritten by the CPU  51  when the power of the display  55  or the back light of the display  55  is turned on or off. 
         [0049]    If the display start determining unit  110  determines that the display  55  is in the active state and if the walking determining unit  101   a  determines that the user is walking, the distance metering unit  120  meters the distance to the obstacle in front of the user of the mobile phone  1  based on the photograph information that is photographed by the distance meter  61 , for example, the stereo camera  611 . At this time, the distance metering unit  120  may meter the distance to the obstacle by applying, for example, a principal of triangulation or the like to two pieces of the photograph information photographed by the lenses  61   a  and  61   b  of the stereo camera  611 . 
         [0050]    Based on the acceleration value metered by the acceleration meter  62 , the activity intensity calculating unit  130  calculates the activity intensity of the user of the mobile phone  1 . For example, the activity intensity calculating unit  130  may calculate the activity intensity of the user by using Formula [1]. According to Formula [1], “n” is the number of samplings of acceleration value per unit time, and “X”, “Y,” and “Z” indicate acceleration values in the X, Y, and Z directions, respectively. The unit of the acceleration value is not particularly limited. According to the first embodiment, the unit is, for example, m/second 2 . 
         [0000]    
       
         
           
             
               
                 
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         [0051]    Regarding Formula [1], g (x) is a liner function that calculates an activity intensity [Mets] based on a plurality of acceleration values that is sequentially obtained. 
         [0052]    Specifically, from among the plurality of acceleration values stored in the data storage unit  150 , the activity intensity calculating unit  130  substitutes the acceleration values Xi, Yi, and Zi (i=0, 1, etc. and n) for the number n of the samplings into Formula [1]. The number “n” of samplings and the acceleration values Xi, Yi, and Zi are stored in the data storage unit  150 . 
         [0053]    The formula for calculating the activity intensity is not limited to Formula [1]. For example, the formula is expressed as a function f of “Xi,” “Yi,” and “Zi” (i=0, 1, etc., and n), that is, f (X0, X1, etc., and Xn, Y0, Y1, etc., and Yn, and Z0, Z1, etc., and Zn). When the number “n” of samplings of the acceleration value per unit time and the acceleration values “Xi,” “Yi,” and “Zi” (i=0, 1, etc., and n) are input into the X direction, the Y direction, and the Z direction in each of the samplings, other formulas except Formula [1] may be employed if the formula calculates the activity intensity per unit time. Formula [1] is an example of the function f. 
         [0054]    The communication unit  140  is radio-coupled to the mobile phone network to achieve communication functions such as a telephone conversation, a mail, and the Internet. 
         [0055]    The data storage unit  150  stores the acceleration values “Xi,” “Yi,” and “Zi” (i=0, 1, etc., and n) detected by the acceleration meter  62 , and the number “n” of samplings of the acceleration value per unit time. If the number of detection by the acceleration meter  62  reaches the number “n” of samplings, every time another acceleration value is detected, the latest acceleration value may be stored after the oldest acceleration value may be deleted, that is, upgrading may be performed. 
         [0056]    The data storage unit  150  stores the activity intensity calculated by the activity intensity calculating unit  130  in correspondence to calculation time. The data storage unit  150  further stores an average landing period obtained when a walker lands his/her foot. According to the first embodiment, the range of the landing period is, for example, 1 Hz/second to 2 Hz/second. 
         [0057]    The data storage unit  150  further stores the parameter of the relational formula of the activity intensity and the walking speed of an average walker. The parameter will be simply described below. 
         [0058]      FIG. 5  is a graph of a relative formula of the activity intensity and the walking speed according to the first embodiment. 
         [0059]    As illustrated in  FIG. 5 , if the activity intensity is plotted on an X axis and the walking speed is plotted on a Y axis, the activity intensity and the walking speed of an average walker satisfy Formula [2]. Therefore, the data storage unit  150  according to the first embodiment stores an inclination  14 , as a parameter, of the straight line  14  expressed by Formula [2] and a coordinate C (2.5, 53) where a straight line A passes. 
         [0000]      [Numeral 2] 
         [0000]        y− 53=14( x− 2.5)   [2]
 
         [0060]    The data storage unit  150  further stores a threshold value table in which the walking speed of an average walker corresponds to the detection range of an obstacle, that is, the threshold value. The threshold value table will be described below. 
         [0061]      FIG. 6  illustrates the threshold value table in which the walking speed corresponds to the threshold value according to the first embodiment. 
         [0062]    As illustrated in  FIG. 6 , in the threshold value table, the walking speed “Less than 3.0 km/h” corresponds to the threshold value “2,” and the walking speed “3.0 km/h or more, less than 3.5 km/h” corresponds to the threshold value “2.5 m”. Moreover, the walking speed “3.5 km/h or more, less than 4 km/h” corresponds to the threshold value “3 m,” the walking speed “4 km/h or more, less than 4.5 km/h” corresponds to the threshold value “3.5 m,” and the walking speed “4.5 km/h or more” corresponds to the threshold value “4m.” 
         [0063]    [Collision Avoiding Process] 
         [0064]      FIG. 7  is a flowchart of the collision avoiding process according to the first embodiment. 
         [0065]    When the power of the mobile phone  1  is turned on, as illustrated in  FIG. 7 , the activity intensity calculating unit  130  starts calculating the activity intensity of the user of the mobile phone  1  based on the acceleration value metered by the acceleration meter  62  (Operation S 201 ). The activity intensity is calculated in a predetermined period of time, for example, 40 m seconds and is then sequentially stored in the data storage unit  150 . 
         [0066]    Based on the activity intensity calculated by the activity intensity calculating unit  130  and on the landing period stored in the data storage unit  150 , the walking determining unit  101   a  determines whether or not the user of the mobile phone  1  is walking (Operation S 202 ). The determination will be simply described below. 
         [0067]      FIG. 8  is an explanatory diagram of an idea of landing period of a foot of a walking user according to the first embodiment. 
         [0068]    As illustrated in  FIG. 8 , a landing period indicates a period of time after the landing of a foot F 1 , one foot of the user, before the landing of a foot F 2 , the other foot of the user. 
         [0069]    If the determination indicates that the user is walking (Yes in Operation S 202 ), the display start determining unit  110  determines whether or not the display  55  is in the active state based on the display start information stored in the data storage unit  150  (Operation S 203 ). The display start information stored in the data storage unit  150  is updated by the device driver of the display  55 , for example, every time the power of the display  55  or the back light of the display  55  is turned on or off. 
         [0070]    On the other hand, if the determination indicates that the user is not walking (No in Operation S 202 ), queuing processing is performed for a predetermined period of time, for example several hundred milli seconds, to calculate the activity intensity again (Operation S 201 ). 
         [0071]    If the determination indicates that the display  55  is in the active state (Yes in Operation S 203 ), the distance metering unit  120  meters the distance to the obstacle in front of the stereo camera  611  based on two pieces of the photograph information photographed by the distance meter  61 , for example, the lenses  61   a  and  61   b  of the stereo camera  611  (Operation S 204 ). The distance to the obstacle is metered in a predetermined period of time, for example, several hundred milli seconds. 
         [0072]    On the other hand, if the determination indicates that the display  55  is not in the active state (No in Operation S 203 ), the queuing processing is performed for a predetermined period of time, for example, several hundred milli seconds (Operation S 211 ). The activity intensity calculating unit  130  calculates the activity intensity again (Operation S 201 ). 
         [0073]    Based on the activity intensity calculated by the activity intensity calculating unit  130  and on the parameter of the relational formula of the activity intensity and the walking speed stored in the data storage unit  150 , the speed calculating unit  101   b  calculates the walking speed of the user of the mobile phone  1  (Operation S 205 ). That is, by using the relational formula of the activity intensity and the walking speed, the speed calculating unit  101   b  calculates the walking speed of the user of the mobile phone  1  corresponding to the activity intensity calculated by the activity intensity calculating unit  130 . According to the first embodiment, for example, the inclination  14  of the straight line A expressed in [Numeral 2] and a coordinate C (2.5, 53) where the straight line A passes are used as a parameter. 
         [0074]    Based on the walking speed calculated by the speed calculating unit  101   b  and on the threshold table stored in the data storage unit  150 , the threshold value acquiring unit  101   c  acquires the detection range in which the obstacle to be avoided is detected, that is, the threshold value (Operation S 206 ). For example, as illustrated in  FIG. 6 , if the walking speed calculated by the speed calculating unit  101   b  is approximately 3.0 [km/m], the threshold value used to detect the obstacle is 2.5 [m] and if the walking speed calculated by the speed calculating unit  101   b  is approximately 4.0 [km/m], the threshold value used to detect the obstacle is 3.5 [m]. 
         [0075]    The comparing unit  101   d  compares the distance to the obstacle metered by the distance metering unit  120  to the threshold value acquired by the threshold value acquiring unit  101   c  (Operation S 207 ). 
         [0076]    If the distance to the obstacle is smaller than the threshold value (Yes in Operation S 207 ), the output control unit  104  outputs an alarm signal to one of the display  55 , the speaker  56 , and the vibrator  57  (Operation S 208 ). Based on the alarm signal, at least one of the display  55 , the speaker  56 , and the vibrator  57  notifies the user that the obstacle is coming close. On the other hand, if the distance to the obstacle is larger than the threshold value (No in Operation S 207 ), the output control unit  104  performs the queuing processing for a predetermined period of time, for example, several hundred milli seconds (Operation S 212 ). The activity intensity calculating unit  130  calculates the activity intensity again (Operation S 201 ). 
         [0077]    Based on the display start information of the display  55  stored in the data storage unit  150 , the display start determining unit  110  determines whether the display  55  is in the active state (Operation S 209 ). 
         [0078]    If the determination indicates that the display  55  is not in the active state (No in Operation S 209 ), the control unit  100  ends the collision avoiding process. On the other hand, if the determination indicates that the display  55  is in the active state (Yes in Operation S 209 ), the display start determining unit  110  performs the queuing processing for a predetermined period of time, for example, several hundred m seconds (Operation S 213 ). The activity intensity calculating unit  130  calculates the activity intensity again (Operation S 201 ). 
         [0079]    As described above, according to the first embodiment, depending on the walking speed of the user of the mobile phone  1 , the detection range in which the obstacle to be avoided is detected, that is, the threshold value is changed. As a result, regardless of the walking speed of the user of the mobile phone  1 , the collision with the obstacle may be avoided. 
         [0080]    According to the first embodiment, simply if the determination indicates that the display  55  of the mobile phone  1  is in the active state, that is, simply if the user easily fails to pay attention to the front while looking at the display  55 , the obstacle to be avoided is detected. Therefore, if the user is not looking at the display  55 , that is, if there is no need to notify the user of the existence of the obstacle to be avoided, the collision avoiding process may be stopped. 
         [0081]    Furthermore, according to the first embodiment, simply if the obstacle is coming close to the user of the mobile phone  1 , the user is notified of the existence of the obstacle to be avoided. That is, according to the first embodiment, the mobile phone  1  does not provide the user with the existence information of the obstacle by displaying the front image on the display  55  all the time. Therefore, the user may pay attention to the obstacle when the obstacle is coming close. In other cases, the user may not keep paying too much attention to the obstacle. 
         [0082]    According to the first embodiment, based on the activity intensity of the user of the mobile phone  1  and on the relation between the activity intensity and the walking speed, the walking speed of the user is calculated. Therefore, the walking speed of the user is easily calculated. Moreover, since the maximum value of the walking speed is acquired, the collision with the obstacle may be avoided more reliably. 
         [0083]    In the first embodiment, the mobile phone  1  has been described as an example of mobile electronic apparatus. However, the present invention is not limited to the first embodiment. For example, a portable navigation device is used as a mobile electronic apparatus. 
         [0084]    According to the first embodiment, the power supply of the mobile phone  1  as a trigger starts the collision avoiding process. However, the present invention is not limited to the first embodiment. For example, the power supply of the display  55  or the back light of the display  55  as a trigger may start the collision avoiding process. If the power supply of the display  55  or the back right of the display  55  as a trigger starts the collision avoiding process, the activity intensity is acquired while the user is looking at the display  55 . That is, when it is estimated that the user is not looking at the display  55 , the activity intensity is not acquired. As a result, the power saving of the mobile phone  1  may be achieved. 
         [0085]    Furthermore, hand-operated power supply of the mobile phone  1  as a trigger may start the collision avoiding process. If the collision avoiding process is started when the power of the mobile phone  1  is manually turned on, the collision avoiding process is not started unless the power of the display  55  or the back light of the display  55  is hand-operated supplied even if the power of the display  55  or the back light of the display  55  is set to be supplied. That is, simply if it is estimated that the user is assumed to be looking at the display  55 , the collision avoiding process may be started. As a result, the power saving of the mobile phone  1  is further achieved. 
         [0086]    According to the first embodiment, the mobile phone  1  starts the collision avoiding process when the power of the display  55  or the back light of the display  55  is supplied as a trigger. However, the present invention is not limited to the first embodiment. For example, simply if the power of the display  55  or the back light of the display  55  is supplied and if the determination indicates that the user is walking, the mobile phone  1  may start the collision avoiding process. The mobile phone  1  may achieve the flow of the collision avoiding process by using a power flag that is set when the power of the display  55  or the back light of the display  55  is supplied and a walking flag that is set when the determination indicates that the user is walking If either the power flag or the walking flag is set, checking if the other flag is set may be performed. 
         [0087]    In the first embodiment, the stereo camera  611  is used to meter the distance to the obstacle in front of the mobile phone  1 . However, the present invention is not limited to the second embodiment. For example, an ultrasound distance meter or an optical distance meter may be used. The ultrasound meter or the optical meter may meter the distance between the mobile phone  1  and the obstacle based on a transmission time of an ultrasound beam or a laser beam and on a reception time of the ultrasound beam or the laser beam that is reflected by the obstacle. By changing the reflection angle of the ultrasound beam or the laser beam, the distance from the mobile phone  1  to the obstacle is detected for each of the reflections angles. The obstacle to be avoided may be detected in a wide range of the front of the mobile phone  1 . 
         [0088]    In the first embodiment, the type of the obstacle to be avoided is not specified. However, the present invention is not limited to the first embodiment. For example, to avoid the collision with an oncoming walker, the collision avoiding process may be started simply if a human face or a part of the human face is detected within the detection range by using an image recognizing technique. 
         [0089]    According to the first embodiment, the stereo camera  611  is mounted on the lower housing  20 . If the stereo camera  611  may photograph at least the front of the user when the user is walking while looking at the display  55  of the mobile phone  1 , the mounting position and the mounting form of the stereo camera  611  are not limited. 
         [0090]    In the first embodiment, to notify the user of the obstacle coming close to be avoided, one of the display  55 , the speaker  56 , and the vibrator  57  is used. However, the present invention is not limited to the first embodiment. For example, a light-emitting body such as a Light Emitting Diode (LED) mounted on the mobile phone  1  may be used. 
         [0091]    In the first embodiment, based on the acceleration value detected by the acceleration meter  62 , the activity intensity of the user of the mobile phone  1  is calculated. However, the present invention is not limited to the first embodiment. In the similar manner, according to the first embodiment, based on the activity intensity calculated by the activity intensity calculating unit  130 , the walking speed of the user of the mobile phone  1  is calculated. However, the present invention is not limited to the first embodiment. 
       Second Embodiment 
       [0092]    With reference to  FIGS. 9 to 12 , a second embodiment will be described below. If the configurations and functions are equivalent to the first embodiment, the description may be omitted. 
         [0093]    The mobile phone  1  according to the first embodiment notifies the user of the existence of the obstacle by at least one of the display  55 , the speaker  56 , and the vibrator  57 . The mobile phone  1  according to the second embodiment displays the position of the obstacle, the collision avoiding method, or the like on the display  55 . 
         [0094]      FIG. 9  is a functional block diagram of the mobile phone  1  according to the second embodiment. 
         [0095]    As illustrated in  FIG. 9 , a whole control unit  101 M according to the second embodiment further includes a distance calculating unit  101   e  and a comparing unit  101   f.  A distance metering unit  120 M meters an angle θ 1  of the obstacle O 1  obtained based on the walk path P of the user of the mobile phone  1  as a standard. 
         [0096]    When the distance metering unit  120 M meters a distance by using the ultrasound distance meter or the optical distance meter, the angle θ 1  is equal to the reflection angle obtained by metering the distance from the mobile phone  1  to the obstacle O 1  based on the transmission time and on the reception time of the reflection wave that is reflected by the obstacle. The acceleration meter  130  may meter the distance of each reflection angle by changing the reflection angle with respect to simply a horizontal direction. If the stereo camera is used, the outlines of the objects of two images are recognized and compared with each other, so that the distance may be calculated according to a shift of a dot position. In this case, the angle θ 1  is desired according to the dot position of each of the outlines. If a distance such as several meters is metered, the base line length may be several centimeters. The acceleration meter may meter the distance for each of the reflection angles by changing the reflection angle with respect to simply the horizontal direction. Regarding the range of the angle θ 1 , the threshold value may vary according to the speed. 
         [0097]    Regarding the change of the threshold value, for example, the walking speed “Less than 3.0 km/h” corresponds to the threshold value “±90° ahead,” the walking speed “3.0 km/h or more, less than 3.5 km/h” corresponds to the threshold value “±70° ahead,” the walking speed “3.5 km/h or more, less than 4 km/h” corresponds to the threshold value “±60° ahead,” the walking speed “4 km/h or more, less than 4.5 km/h” corresponds to the threshold value “±50° ahead,” and the walking speed “4.5 km/h or more” corresponds to the threshold value “±40° ahead.” 
         [0098]    The walk path P is assumed to be a path on which the user walks. Therefore, when the user holds the mobile phone and looks at the display, the display is not vertical in most cases. Therefore, the upper direction of the display is the front direction, and the path extending forward in a straight line is the walk path P. Furthermore, according to the moving speed, the data storage unit  150  stores the distance, as a threshold value d 0 , in which the user does not collide against the obstacle O 1  while walking on the walk path P. 
         [0099]    Based on a distance L 1  to the obstacle O 1  and on the angle θ 1  of the obstacle O 1 , the distance calculating unit  101   e  calculates the distance d 1  between the obstacle O 1  and the walk path P. For example, by multiplying the distance L 1  to the obstacle O 1  metered by the distance metering unit  120 M by the sine of the angle θ 1  of the obstacle O 1  metered by the distance metering unit  120 M, that is, sin θ 1 , the distance calculating unit  101   e  calculates the distance d 1  between the obstacle O 1  and the walk path P. 
         [0100]    The comparing unit  101   f  compares the distance d 1  calculated by the distance calculating unit  101   e  to the threshold value d 0  stored in the data storage unit  150 . 
         [0101]    Based on a comparison result obtained by comparing the distance d 1  calculated by the distance calculating unit  101   e  to the threshold value d 0  stored in the data storage unit  150 , an output control unit  104 M displays the obstacle information such as a position, a direction of the obstacle, the collision avoiding method, and the like on the display  55 . 
         [0102]    [Generating Process of Collision Avoiding Method] 
         [0103]      FIG. 10  is a flowchart of a display process of a collision avoiding method according to the second embodiment.  FIGS. 11A and 11B  illustrate the display content of the display  55  of the mobile phone  1  according to the second embodiment.  FIG. 11A  illustrates a positional relation of a user U, the walk path P, and the obstacle O 1 .  FIG. 11B  illustrates the display content of the display  55  corresponding to  FIG. 11A .  FIGS. 12A and 12B  illustrate the display content of the display  55  of the mobile phone  1  according to the second embodiment.  FIG. 12A  illustrates a positional relation of the user U, the walk path P, and the obstacle O 1 , and the obstacle O 2 .  FIG. 12B  illustrates the display content of the display  55  corresponding to  FIG. 12A . 
         [0104]    In the second embodiment, if the distance from the mobile phone  1  to the obstacle is larger than the threshold value (No in Operation S 207  according to the first embodiment), as illustrated in  FIG. 10 , the distance calculating unit  101   e  calculates the distance d 1  of the perpendicular to the obstacle O 1  and the walk path P based on the distance L 1  to the obstacle O 1  and on the angle θ 1  of the obstacle O 1  metered by the distance metering unit  120 M (Operation S 301 ). 
         [0105]    The comparing unit  101   f  compares the distance d 1  calculated by the distance calculating unit  101   e  to the threshold value d 0  stored in the data storage unit  150  (Operation S 302 ). 
         [0106]    If the distance d 1  between the obstacle O 1  and the walk path P is smaller than the threshold value d 0  (Yes in Operation S 302 ), the output control unit  104  desires another walk path P 1  and displays an arrow P 1  indicating the walk path P 1  on the display  55  as illustrated in  FIG. 11  (Operation S 303 ). 
         [0107]    At this time, by comparing the distance between the obstacle O 1  and the walk path P to the threshold value d 0  for each angle while gradually shifting the angle of the walk path P by 5 degrees, the output control unit  104  may acquire another walk path P 1  on which the user does not collide against the obstacle O 1 . 
         [0108]    The output control unit  104  may display character information, for example, “Turn aside 30° on the right!” corresponding to the walk path P 1 , on the display  55 . The output control unit  104  may display a mark of the user, for example, “Me”, a mark of the obstacle O 1 , for example, “Obstacle”, a distance to the obstacle O 1 , and a direction of the obstacle O 1  on the display  55 . The output control unit  104  may display a mark of the user, for example, “Me”, a mark of the obstacle O 1 , for example, “Obstacle”, a distance to the obstacle O 1 , and a direction of the obstacle O 1  on the display  55 . 
         [0109]    If there is another obstacle O 2  in front of the user and if a distance d 2  between the walk path P 1  and the obstacle O 2  is smaller than the threshold value d 0  (Yes in Operation S 302 ), the letter information suggesting the user to stop walking, for example, “Stop!” may be displayed on the display  55 . Alternatively, the walk path P 2  in which the distance d 2  from the obstacle O 2  is larger than the threshold value d 0  may be acquired and, as illustrated in  FIG. 12(   b ), an arrow P 2  indicating the walk path P 2  may be displayed on the display  55 . 
         [0110]    On the other hand, if the distance d 1  between the obstacle O 1  and the walk path P is larger than the threshold value d 0  (No in Operation S 302 ), the user does not collide against the obstacle O 1  even if the user of the mobile phone  1  walks on the walk path P. Therefore, the output control unit  104  does not display the collision avoiding method or the like. 
         [0111]    As described above, according to the second embodiment, the distance to the obstacle to be avoided and the direction of the obstacle are displayed on the display  55  of the mobile phone  1  that the user is looking at. Therefore, even if the user pays attention on the display  55  of the mobile phone  1 , the user may surely recognize the existence of the obstacle. 
         [0112]    According to the second embodiment, if the obstacle is sufficiently far away from the walk path P, the display  55  does not display the collision avoiding method. Therefore, the display  55  does not display useless information that does not affect the walk of the user, so that the display area in use is not reduced. 
       Third Embodiment 
       [0113]    With reference to  FIG. 13 , a third embodiment will be described. If the configuration and function are equivalent to the first and second embodiments, the description is omitted. 
         [0114]      FIG. 13  is a diagram of a back surface of a lower housing  20 M according to the third embodiment. 
         [0115]    As illustrated in  FIG. 13 , the mobile phone  1  according to the third embodiment further includes a left stereo camera  66  and a right stereo camera  67  in a left part and a right part of the mobile phone  1 , respectively. The left stereo camera  66  and the right stereo camera  67  are provided inside the lower housing  20  of the mobile phone  1  and photograph the front of lenses  66   a  and  66   b  and lenses  67   a  and  67   b,  respectively. The lenses  66   a  and  66   b  and the lenses  67   a  and  67   b  are allocated on inclined surfaces  21  and  22  that are formed on the right side and the left side of the lower housing  20 , respectively. The inclined surfaces  21  and  22  incline against the back surface of the lower housing  20  as a standard. Therefore, the left stereo camera  66  and the right stereo camera  67  having the lenses  66   a  and  66   b  and the lenses  67   a  and  67   b,  respectively, photograph the direction that is different from the direction of the stereo camera  611 . 
         [0116]    The mobile phone  1  according to the third embodiment, the collision avoiding process is executed for each photograph information photographed by the stereo camera  611 , the left stereo camera  66 , and the right stereo camera  67 , respectively. That is, if the obstacle photographed by one of the stereo camera  611 , the left stereo camera  66 , and the right stereo camera  67  is within a detection range (threshold value), an alarm signal is output to at least one of the display  55 , the speaker  56 , and the vibrator  57 . Based on the alarm signal, at least one of the display  55 , the speaker  56 , and the vibrator  57  notifies the user of the obstacle coming close. Accordingly, the collision avoiding may be achieved in a wider range that includes not simply the front of the mobile phone  1  but also the right side and the left side of the mobile phone  1 . 
         [0117]    All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present inventions have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.