Patent Publication Number: US-2020280923-A1

Title: Portable electronic device

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2019-035663 filed in Japan on Feb. 28, 2019 and Japanese Patent Application No. 2020-004181 filed in Japan on Jan. 15, 2020. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a portable electronic device. 
     2. Description of the Related Art 
     Conventionally, measurement terminals that calculate the amount of activity have been known. Japanese Patent No. 6049308 discloses an activity amount measurement terminal including a body motion detection unit that detects body motion of a user, a communication unit that communicates with an external device to receive personal data on the user and transmit measured or calculated data, a storage unit that stores therein the personal data on the user and the measured or calculated data, and an arithmetic unit that performs predetermined arithmetic operation based on a detection result of the body motion detection unit and the data in the storage unit. 
     In a portable electronic device that detects the amount of activity, it is desired to reduce power consumption. For example, in a period from when the portable electronic device is shipped until a user starts to use the portable electronic device, it is preferred to suppress power consumption in a sensor that detects a physical amount related to the amount of activity. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a portable electronic device capable of suppressing power consumption in a sensor that detects a physical amount related to the amount of activity. 
     In order to solve the above mentioned problem and achieve the object, a portable electronic device according to one aspect of the present invention includes a sensor configured to detect a physical amount; a communication unit configured to perform wireless communication; a controller configured to control supply of power to the sensor; and a storage unit configured to record, when pairing between the communication unit and an external device used by a user is executed, pairing information between the communication unit and the external device, wherein a permission condition under which the controller permits the supply of power to the sensor includes a condition that the pairing information is recorded in the storage unit. 
     The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating a portable electronic device according to an embodiment; 
         FIG. 2  is a block diagram of the portable electronic device according to the embodiment; 
         FIG. 3  is a diagram illustrating a first example of the flow until the supply of power to a sensor is permitted in the embodiment; 
         FIG. 4  is a diagram illustrating a second example of the flow until the supply of power to the sensor is permitted in the embodiment; 
         FIG. 5  is a diagram illustrating an acceleration sensor according to a first modification of the embodiment; 
         FIG. 6  is a block diagram of a portable electronic device according to a second modification of the embodiment; and 
         FIG. 7  is a flowchart according to the second modification of the embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A portable electronic device according to an embodiment of the present invention is described in detail below with reference to the drawings. The present invention is not limited by the embodiment. Components in the following embodiment include the ones that can be easily conceived by a person skilled in the art or the ones that are substantially the same. 
     Embodiment 
     Referring to  FIG. 1  to  FIG. 4 , an embodiment is described. The present embodiment relates to a portable electronic device.  FIG. 1  is a diagram illustrating a portable electronic device according to the embodiment.  FIG. 2  is a block diagram of the portable electronic device according to the embodiment.  FIG. 3  is a diagram illustrating a first example of the flow until the supply of power to a sensor is permitted in the embodiment.  FIG. 4  is a diagram illustrating a second example of the flow until the supply of power to the sensor is permitted in the embodiment. 
     An electronic watch  1  illustrated in  FIG. 1  is an example of the portable electronic device according to the embodiment. The electronic watch  1  has a function for performing wireless communication with an external device  3  and a function for calculating the amount of activity of a user. As illustrated in  FIG. 1 , the electronic watch  1  has an analog display unit  26  and an external case  29 . The external case  29  has a case main body  29   e  and four lugs  29   a  to  29   d . The shape of the case main body  29   e  is an annular shape, and, for example, a cylinder shape. The lugs  29   a  to  29   d  protrude from the outer peripheral surface of the case main body  29   e.    
     The analog display unit  26  is housed in an internal space in the case main body  29   e . The analog display unit  26  has a dial  26   a , a second hand  26   b , a minute hand  26   c , an hour hand  26   d , and a date dial  26   e . A crown  27  is disposed on the case main body  29   e . An end portion of the crown  27  protrudes from the side surface of the case main body  29   e.    
     As illustrated in  FIG. 2 , the electronic watch  1  further has a communication unit  22 , a controller  23 , a power supply unit  24 , a drive mechanism  25 , and a storage unit  28 . The communication unit  22  has an antenna  21 , a communication module  22   a , and a conversion unit  22   b . The antenna  21  transmits and receives radio waves of short-distance wireless communication. The antenna  21  is connected to the communication module  22   a . The communication module  22   a  is a communication control module that performs short-distance wireless communication with the external device  3 . For example, the communication module  22   a  communicates with the external device  3  by the protocol of Bluetooth (registered trademark). The conversion unit  22   b  converts a serial signal into a parallel signal, or converts a parallel signal into a serial signal. 
     The controller  23  controls various kinds of circuits and mechanisms in the electronic watch  1 . The controller  23  has a micro controller  23   a , a motor drive circuit  23   b , a non-volatile memory  23   c , and a real time clock (RTC)  23   d . The micro controller  23   a  has an arithmetic unit  23   e , a random access memory (RAM)  23   f , and a read only memory (ROM)  23   g.    
     The arithmetic unit  23   e  performs various kinds of information processing in accordance with computer programs stored in the ROM  23   g . For example, the arithmetic unit  23   e  calculates an internal time of the electronic watch  1  based on a clock signal output from the RTC  23   d . As described later, the arithmetic unit  23   e  in the present embodiment calculates the amount of activity of a user based on detection results of an acceleration sensor  4 . The RAM  23   f  functions as a work memory for the arithmetic unit  23   e . Information to be processed by the arithmetic unit  23   e  is written in the RAM  23   f.    
     The motor drive circuit  23   b  controls the drive mechanism  25  based on a clock internal time. The non-volatile memory  23   c  is a memory that holds information when power is not supplied from the power supply unit  24  to the controller  23  or when the electronic watch  1  is restarted. For example, data on the amount of activity calculated by the arithmetic unit  23   e  is recorded in the non-volatile memory  23   c.    
     The power supply unit  24  is a power source of the electronic watch  1 . The power supply unit  24  supplies power to the communication unit  22 , the controller  23 , the drive mechanism  25 , and the like. The power supply unit  24  has a power generation circuit  24   a , a battery  24   b , and a voltage detection circuit  24   c . The power generation circuit  24   a  is a power generation mechanism such as a solar cell, and stores generated power in the battery  24   b . The battery  24   b  is a rechargeable secondary battery. The voltage detection circuit  24   c  is a circuit that detects voltage of the battery  24   b . The detection result of the voltage detection circuit  24   c  is output to the micro controller  23   a.    
     The drive mechanism  25  in the present embodiment has three stepping motors  25   a ,  25   b , and  25   c . The stepping motor  25   a  is a motor that moves the second hand  26   b . The stepping motor  25   b  is a motor that moves the minute hand  26   c  and the hour hand  26   d . The stepping motor  25   c  is a motor that rotates the date dial  26   e . The stepping motors  25   a ,  25   b , and  25   c  are driven by drive signals output from the motor drive circuit  23   b.    
     The storage unit  28  is a storage device that stores therein pairing information and user profile information. The pairing information is information on pairing between the communication unit  22  and the external device  3 , and includes, for example, a pass key for pairing. Examples of the user profile information include the height and weight of the user. For example, the storage unit  28  is a non-volatile memory such as a flash memory and an EEPROM. 
     The electronic watch  1  in the present embodiment has the acceleration sensor  4  and a tilt switch  5 . The acceleration sensor  4  is a sensor that detects acceleration of the electronic watch  1 . For example, the acceleration sensor  4  detects three-dimensional acceleration of the electronic watch  1 . The acceleration sensor  4  outputs a signal of amplitude corresponding to the magnitude of the detected acceleration. For example, the amplitude of the signal output from the acceleration sensor  4  becomes larger as the absolute value of the detected acceleration becomes larger. 
     The tilt switch  5  is a sensor that detects a change in posture of the electronic watch  1 . The tilt switch  5  switches from the on state to the off state or from the off state to the on state depending on a change in tilt angle of the electronic watch  1 . The detection results of the acceleration sensor  4  and the tilt switch  5  are output to the controller  23 . The acceleration sensor  4  and the tilt switch  5  operate by power supplied from the power supply unit  24 . 
     The external device  3  illustrated in  FIG. 1  is a device owned by a user of the electronic watch  1 , and used by the user. The external device  3  is typically a portable terminal device such as a smartphone. The external device  3  has a function for executing short-distance wireless communication. The external device  3  has a function for communicating with an external server  200  through an Internet network  100 . The external device  3  has a casing  31  and a touch panel  32 . The touch panel  32  is overlapped on an image display surface. The user can operate the external device  3  through input operation on the touch panel  32 . 
     To perform wireless communication between the electronic watch  1  and the external device  3  for the first time, the user pairs the electronic watch  1  with the external device  3 . After pairing is executed, the electronic watch  1  and the external device  3  can automatically start wireless communication. To pair the electronic watch  1  with the external device  3 , the user performs pairing start operation on the electronic watch  1 . For example, the pairing start operation is predetermined operation on the crown  27 . The user performs pairing start operation on the external device  3 . For example, the pairing start operation on the external device  3  is performed through the touch panel  32 . 
     The external device  3  in the embodiment can execute an activity amount management application. The activity amount management application is an application for storing and managing the amount of activity of the user calculated by the electronic watch  1 . The external device  3  acquires activity amount data on the user from the electronic watch  1  by wireless communication. Pairing in the external device  3  may be executed by the activity amount management application. 
     When the pairing start operation is performed by the user, the controller  23  in the electronic watch  1  controls the communication unit  22  to execute pairing operation. The communication unit  22  performs pairing with the external device  3  along a predetermined procedure. For example, the communication unit  22  uses an authentication code to perform pairing authentication operation, and establishes a communication link with the external device  3 . 
     For example, after pairing authentication, the communication unit  22  forms a common code (for example, link key) to form a communication link. When the communication link with the external device  3  is formed, the communication unit  22  notifies the controller  23  of the completion of the pairing. 
     The controller  23  that has been notified of pairing completion acquires pairing information between the communication unit  22  and the external device  3  from the communication unit  22 . Examples of the pairing information include identification information on the external device  3  and a link key. The controller  23  records the acquired pairing information in the storage unit  28 . A communication link between the communication unit  22  and the external device  3  for the next time is formed based on the pairing information recorded in the storage unit  28 . In other words, as long as the pairing information is recorded in the storage unit  28 , the communication unit  22  can form a communication link with the external device  3  and start communication. When a communication link has not been formed between the communication unit  22  and the external device  3 , the controller  23  controls the communication unit  22  to form a communication link with the external device  3  based on the pairing information recorded in the storage unit  28 . When the formation of the communication link has failed, the controller  23  tries to form a communication link periodically until the formation of the communication is successful. 
     The supply of power from the battery  24   b  to the acceleration sensor  4  is controlled by the controller  23 . The controller  23  can further control the supply of power from the battery  24   b  to the tilt switch  5 . 
     The controller  23  in the present embodiment calculates the amount of activity of the user based on the detection result of the acceleration sensor  4 . Examples of the amount of activity of the user include the walk count of the user and calorie consumption of the user. Of the amounts of activity, the calorie consumption is calculated based on profile information on the user in addition to the detection result of the acceleration sensor  4 . The profile information on the user includes the height and the weight of the user. On the other hand, the walk count of the user can be calculated without referring to the profile information. The electronic watch  1  in the present embodiment is configured such that profile information on the user is acquired by wireless communication from the external device  3 . The electronic watch  1  records the acquired profile information in the storage unit  28 , and calculates the amount of activity of the user based on the acquired profile information. Thus, the electronic watch  1  cannot calculate the amount of activity requiring the profile information until the profile information is acquired from the external device  3 . 
     As described below, the electronic watch  1  in the present embodiment permits the supply of power to the acceleration sensor  4  when a predetermined permission condition is satisfied. In this manner, the electronic watch  1  in the present embodiment can suppress the supply of unnecessary power to the acceleration sensor  4 , and reduce power consumption by the acceleration sensor  4 . 
     The permission conditions in the present embodiment include a condition that pairing information with the external device  3  is recorded in the storage unit  28 . In other words, the controller  23  permits the supply of power to the acceleration sensor  4  under a permission condition that pairing between the electronic watch  1  and the external device  3  has been made. In this manner, for example, the power consumption in the acceleration sensor  4  is suppressed from when the electronic watch  1  is shipped until the user starts using the electronic watch  1 . 
     The permission conditions in the present embodiment include a condition that profile information on the user is recorded in the storage unit  28 . In other words, the controller  23  permits the supply of power to the acceleration sensor  4  under a permission condition that the profile information on the user has been acquired. In this manner, for example, the power consumption in the acceleration sensor  4  is suppressed until the electronic watch  1  can appropriately calculate the amount of activity. 
     Referring to  FIG. 3 , an example of the flow until the supply of power to the acceleration sensor  4  is permitted is described. 
     (1) The electronic watch  1  in factory default does not have pairing information and profile information. In other words, in factory shipping, pairing information and user profile information are not recorded in the storage unit  28 .
 
(2) The user inputs user profile information through an application on the external device  3 . In the example in  FIG. 3 , profile information is input before pairing is executed.
 
(3) The application on the external device  3  transmits the profile information to the external server  200 . The external server  200  stores the received profile information in a storage device or the like.
 
(4) When communicating the electronic watch  1  with the external device  3  for the first time, the user performs pairing start operation on the electronic watch  1  and the external device  3  to execute pairing.
 
(5) The controller  23  records pairing information in the storage unit  28 .
 
(6) When the pairing information is recorded in the storage unit  28 , the controller  23  permits the supply of power to the acceleration sensor  4 . When power is supplied to the acceleration sensor  4 , the amount of activity that does not require a user profile can be calculated.
 
(7) When the electronic watch  1  forms a communication link with the external device  3  based on the pairing information, the electronic watch  1  requests the external device  3  for profile information.
 
(8) The external device  3  transmits the profile information to the electronic watch  1 .
 
(9) The electronic watch  1  records the received profile information in the storage unit  28 . When the profile information is acquired, the amount of activity requiring the user profile can be calculated.
 
     The electronic watch  1  in the present embodiment performs the above-mentioned power supply control, and can suppress unnecessary power consumption in the electronic watch  1 . For example, in the electronic watch  1  in factory default, neither of pairing information and profile information is recorded in the storage unit  28 . Thus, the controller  23  does not permit the supply of power to the acceleration sensor  4 . As a result, power consumption by the acceleration sensor  4  is suppressed, and power consumption in the electronic watch  1  is reduced. 
     In factory default, the acceleration sensor  4  is prevented from operating, and hence unnecessary activity amount data is not calculated. For example, if the acceleration sensor  4  operates in a period from when the electronic watch  1  is shipped until the electronic watch  1  is delivered to a user, activity amount data irrelevant to the user is generated and accumulated in the electronic watch  1 . Furthermore, if the electronic watch  1  and the external device  3  are paired, the stored unnecessary activity amount data is transmitted to the external device  3 . On the other hand, in the electronic watch  1  in the present embodiment, unnecessary activity amount data is not generated. 
     Before the electronic watch  1  is shipped, factory inspection is performed for the acceleration sensor  4 . In the factory inspection, as described below, the supply of power to the acceleration sensor  4  is temporarily permitted. When the factory inspection is executed, the mode of the electronic watch  1  is set to a test mode. In the test mode, the supply of power to the acceleration sensor  4  is permitted even when pairing information or profile information is not recorded in the storage unit  28 . In the case where a sensor that detects a physical amount related to the amount of activity of the user other than the acceleration sensor  4  is mounted on the electronic watch  1 , the supply of power to the sensor is similarly permitted such that inspection can be performed. 
     When factory inspection is performed, pairing information and profile information for inspection may be recorded in the storage unit  28 . When the pairing information and profile information for inspection are recorded, the supply of power to the acceleration sensor  4  is permitted. In the case where a sensor that detects a physical amount related to the amount of activity of the user other than the acceleration sensor  4  is mounted on the electronic watch  1 , the supply of power to the sensor is similarly permitted such that inspection can be performed. After the factory inspection is completed, the pairing information and profile information for inspection are erased from the storage unit  28 . 
     In the example in  FIG. 3 , the user profile is input before pairing is executed. However, the profile information is not necessarily required to be input before pairing is executed. The user may perform processing for registering and storing a user profile in the electronic watch  1  when it is necessary to calculate the amount of activity requiring the user profile. 
     Referring to  FIG. 4 , a second example of the flow until the supply of power to the acceleration sensor  4  is permitted is described. The second example illustrated in  FIG. 4  is different from the first example illustrated in  FIG. 3  in that, for example, the supply of power to the acceleration sensor  4  is permitted after both pairing information and profile information are recorded. 
     (11) In factory default, neither of pairing information and profile information is recorded.
 
(12) The user inputs user profile information through an application on the external device  3 . Also in the example in  FIG. 4 , the profile information is input before pairing is executed.
 
(13) The external device  3  transmits profile information to the external server  200 .
 
(14) Pairing by the user is performed.
 
(15) The controller  23  records the pairing information in the storage unit  28 .
 
(16) In the storage unit  28 , the pairing information is recorded, but profile information is not recorded. Thus, the controller  23  does not allow the supply of power to the acceleration sensor  4 .
 
(17) The electronic watch  1  requests the external device  3  for profile information.
 
(18) The external device  3  transmits the profile information to the electronic watch  1 .
 
(19) The electronic watch  1  records the received profile information in the storage unit  28 .
 
(20) When the profile information is recorded in the storage unit  28 , the electronic watch  1  permits the supply of power to the acceleration sensor  4 .
 
     In this manner, the supply of power to the acceleration sensor  4  is not permitted until the user profile information is acquired, and hence power consumption in the electronic watch  1  is reduced. In other words, the electronic watch  1  in the present embodiment permits the supply of power to the acceleration sensor  4  after activity amount data using profile information can be calculated, thus reducing power consumption. For example, when calculating calorie consumption of the user as activity amount data, profile information such as the height and the weight is necessary. According to the present embodiment, the acceleration sensor  4  is prevented from being operated while information necessary for calculating activity amount data is insufficient. 
     In the electronic watch  1  in the present embodiment, the pairing information with the external device  3  can be erased. The pairing information is erased by operation by the user. Examples of the operation to erase the pairing information include predetermined operation on the crown  27 . When the operation to erase pairing information is performed by the user, the controller  23  in the present embodiment erases profile information together with pairing information from the storage unit  28 . In this manner, in the storage unit  28 , neither of the pairing information and the profile information is recorded. When the pairing information and the profile information are erased from the storage unit  28 , the controller  23  prohibits the supply of power to the acceleration sensor  4  until at least pairing information is recorded in the storage unit  28  next time. The controller  23  may prohibit the supply of power to the acceleration sensor  4  until both of pairing information and profile information are recorded. 
     When the state in which the amplitude of a signal output from the acceleration sensor  4  is lower than a predetermined value continues for a predetermined period, the controller  23  in the present embodiment stops the supply of power to the acceleration sensor  4 . For example, the above-mentioned predetermined value is determined based on an upper limit value of the amplitude of the signal output from the acceleration sensor  4  when the electronic watch  1  is not used. Alternatively, the above-mentioned predetermined value is determined based on an upper limit value of the amplitude of a signal output from the acceleration sensor  4  when the user wearing the electronic watch  1  is stationary. In other words, the controller  23  stops the supply of power to the acceleration sensor  4  when the state in which the electronic watch  1  is not in use continues for a predetermined period or when the state in which the user is substantially stationary continues for a predetermined period. In this manner, the controller  23  can reduce power consumption in the electronic watch  1 . 
     The controller  23  in the embodiment operates the tilt switch  5  when the supply of power to the acceleration sensor  4  is stopped. When determining that the posture of the electronic watch  1  has changed based on a detection result of the tilt switch  5 , the controller  23  restarts the supply of power to the acceleration sensor  4 . The acceleration sensor  4  consumes a larger amount of power than the tilt switch  5 . Thus, the electronic watch  1  in the present embodiment can reduce power consumption in the electronic watch  1  by minimizing the supply of power to the acceleration sensor  4 . 
     As described above, the electronic watch  1  in the embodiment has the acceleration sensor  4 , the communication unit  22 , the controller  23 , the storage unit  28 , and the arithmetic unit  23   e . The electronic watch  1  is an example of a portable electronic device. The acceleration sensor  4  is an example of a sensor that detects physical amount on the amount of activity of a user. The communication unit  22  is a circuit that performs wireless communication. The controller  23  is a control circuit that controls the supply of power to the acceleration sensor  4 . In the storage unit  28 , pairing information between the communication unit  22  and the external device  3  is recorded when pairing is executed between the communication unit  22  and the external device  3 . The arithmetic unit  23   e  is an example of a calculation unit that calculates the amount of activity of the user based on a detection result of the acceleration sensor  4 . 
     The permission condition under which the controller  23  in the present embodiment permits the supply of power to the acceleration sensor  4  includes a condition that pairing information is recorded in the storage unit  28 . In the electronic watch  1  in the present embodiment, the supply of power to the acceleration sensor  4  is not permitted when pairing information is not recorded in the storage unit  28 , and hence power consumption in the acceleration sensor  4  is suppressed. 
     In the electronic watch  1  in the present embodiment, when profile information on a user is acquired by wireless communication between the communication unit  22  and the external device  3 , the profile information is recorded in the storage unit  28 . The permission condition for permitting the supply of power to the acceleration sensor  4  may include a condition that the profile information is recorded in the storage unit  28 . In this case, the supply of power to the acceleration sensor  4  is not permitted when profile information is not recorded, and hence power consumption in the acceleration sensor  4  is further suppressed. 
     First Modification of Embodiment 
     A first modification of the embodiment is described.  FIG. 5  is a diagram illustrating an acceleration sensor according to the first modification of the embodiment. The first modification of the embodiment is different from the above-mentioned embodiment in that, for example, the acceleration sensor  4  includes a temperature detection unit  41 . As illustrated in  FIG. 5 , the acceleration sensor  4  according to the first modification of the embodiment has a temperature detection unit  41  and an acceleration detection unit  42 . The temperature detection unit  41  is a circuit that detects temperature. The acceleration detection unit  42  is a circuit that detects acceleration, and detects, for example, acceleration in three orthogonal axis directions. For example, detection results of the temperature detection unit  41  and the acceleration detection unit  42  are output to the controller  23 . 
     In the acceleration sensor  4 , a power supply line for the temperature detection unit  41  and a power supply line for the acceleration sensor  4  are shared. In other words, the acceleration sensor  4  is configured such that when power is supplied to the temperature detection unit  41 , power is also supplied to the acceleration detection unit  42 . The supply of power to the acceleration sensor  4  is controlled by a control IC  43 . The control IC  43  operates in response to an instruction from the controller  23 . 
     The controller  23  according to the first modification of the embodiment supplies power to the acceleration sensor  4  based on a sampling interval of the temperature detection unit  41 . For example, the sampling interval of the temperature detection unit  41  is 5 minutes. In this case, the controller  23  supplies power to the acceleration sensor  4  for every 5 minutes, so that temperature is detected by the temperature detection unit  41 . When power is supplied to the acceleration sensor  4 , the controller  23  may prevent the acceleration detection unit  42  from detecting acceleration. When the detection result is output from the temperature detection unit  41 , the controller  23  stops the supply of power to the acceleration sensor  4 . In other words, the controller  23  prohibits the supply of power to the acceleration sensor  4  in periods other than the period during which temperature is detected by the temperature detection unit  41 . 
     According to the first modification, the supply of power to the acceleration sensor  4  is permitted in a limited period necessary for temperature detection. Thus, the period during which power is supplied to the acceleration sensor  4  can be minimized to reduce power consumption in the electronic watch  1 . 
     Second Modification of Embodiment 
     A second modification of the embodiment is described.  FIG. 6  is a block diagram of a portable electronic device according to a second modification of the embodiment.  FIG. 7  is a flowchart according to the second modification of the embodiment. The second modification of the embodiment is different from the above-mentioned embodiment in that, for example, whether to recover from the power-saving mode is determined based on the presence/absence of pairing information or the presence/absence of profile information. 
     As illustrated in  FIG. 6 , an electronic watch  1  according to the second modification has a push button  30  and an optical sensor  6 . For example, the push button  30  is disposed adjacent to the crown  27 . The electronic watch  1  is configured to perform various kinds of processing and setting in response to operation on the push button  30 . A signal indicating operation on the push button  30  is output to the controller  23 . For example, the optical sensor  6  is disposed on the rear surface side of the dial  26   a . For example, the optical sensor  6  is a light receiving element that outputs a signal corresponding to the amount of received light. A signal indicating the detection result of the optical sensor  6  is output to the controller  23 . 
     The electronic watch  1  has a power-saving mode (PS state). The power-saving mode is a mode for suppressing power consumption in the electronic watch  1 . In the power-saving mode, the handling of at least one of the second hand  26   b , the minute hand  26   c , and the hour hand  26   d  is stopped. In the power-saving mode, for example, the handling of the second hand  26   b  is stopped, and the handling of the minute hand  26   c  and the hour hand  26   d  is executed. The controller  23  is configured to execute the shift determination to the power-saving mode and the recovery determination from the power-saving mode. 
     For example, the controller  23  shifts the electronic watch  1  to the power-saving mode when a predetermined shift condition is satisfied. For example, the shift condition is a condition that the amount of received light of the optical sensor  6  is equal to or smaller than a lower limit value. 
     Referring to  FIG. 7 , the shift to the power-saving mode and the recovery from the power-saving mode are described. When the shift condition is satisfied, the controller  23  executes control based on the flowchart illustrated in  FIG. 7 . At Step S 10 , the controller  23  instructs the motor drive circuit  23   b  to shift to the power-saving mode. In response to the instruction to shift to the power-saving mode, the motor drive circuit  23   b  executes the handling control in the power-saving mode. In the handling control in the power-saving mode, for example, the handling of the second hand  26   b  is stopped. For example, the motor drive circuit  23   b  stops the second hand  26   b  at the position of the hour. In the handling control in the power-saving mode, the motor drive circuit  23   b  may handle the minute hand  26   c  and the hour hand  26   d  in accordance with the internal time, and may stop the minute hand  26   c  and the hour hand  26   d . After Step S 10  is executed, the flow proceeds to Step S 20 . 
     At Step S 20 , the controller  23  determines whether operation by the user has been made. For example, the controller  23  determines whether operation on the crown  27  or the push button  30  has been detected. The flow proceeds to Step S 70  when positive determination that the user operation has been performed is made at Step S 20 , and the flow proceeds to Step S 30  when negative determination is made. 
     At Step S 30 , the controller  23  determines whether light has been detected. The controller  23  performs the determination at Step S 30  based on the detection result of the optical sensor  6 . For example, the controller  23  makes positive determination at Step S 30 , for example, when the amount of received light of the optical sensor  6  is equal to or more than a threshold. For example, the threshold is determined such that the amount of power generated by the power generation circuit  24   a  exceeds a predetermined lower limit value. As a result of the determination at Step S 30 , when positive determination that light has been detected is made, the flow proceeds to Step S 70 , and when negative determination is made, the flow proceeds to Step S 40 . 
     At Step S 40 , the controller  23  determines whether pairing information is present. The controller  23  makes positive determination at Step S 40  when pairing information is recorded in the storage unit  28 . As a result of the determination at Step S 40 , when positive determination that pairing information is present is made, the flow proceeds to Step S 50 , and when negative determination is made, the flow proceeds to Step S 20 . 
     At Step S 50 , the controller  23  determines whether profile information is present. The controller  23  makes positive determination at Step S 50  when profile information is recorded in the storage unit  28 . As a result of the determination at Step S 50 , when positive determination that profile information is present is made, the flow proceeds to Step S 60 , and when negative determination is made, the flow proceeds to Step S 20 . 
     At Step S 60 , the controller  23  determines whether the tilt switch  5  has detected motion. For example, the controller  23  makes positive determination at Step S 60  when the state of the tilt switch  5  has been switched from the on state to the off state or from the off state to the on state. As a result of the determination at Step S 60 , when positive determination that the tilt switch  5  has detected motion is made, the flow proceeds to Step S 70 , and when negative determination is made, the flow proceeds to Step S 20 . 
     At Step S 70 , the controller  23  releases the PS state of the electronic watch  1 . The controller  23  instructs the motor drive circuit  23   b  to recover from the power-saving mode to a normal handling mode. In response to the recovery instruction, the motor drive circuit  23   b  executes handling control in the normal handling mode. In the handling control in the normal handling mode, the motor drive circuit  23   b  handles all the second hand  26   b , the minute hand  26   c , and the hour hand  26   d  in accordance with the internal time. After Step S 70  is executed, this control flow is finished. 
     As described above, the controller  23  according to the second modification of the embodiment permits the recovery from the power-saving mode when a recovery condition is satisfied during the execution of the power-saving mode. The recovery condition includes a condition that pairing information is recorded in the storage unit  28  (S 40 —Y) and a condition that the tilt switch  5  has detected a change in tilt angle (S 60 —Y). The recovery from the power-saving mode is not permitted when pairing information is not recorded in the storage unit  28 , and hence power consumption in the electronic watch  1  is suppressed. For example, in the period from when the electronic watch  1  is shipped until the user executes pairing on the electronic watch  1 , the recovery from the power-saving mode is not permitted even when the tilt switch  5  detects the motion of the electronic watch  1 . In other words, even when the state of the tilt switch  5  is switched during transport, the power-saving mode is maintained and power consumption is suppressed. 
     The recovery condition includes a condition that profile information is recorded in the storage unit  28 . The recovery from the power-saving mode is not permitted when pairing information is not recorded in the storage unit  28 , and hence power consumption in the electronic watch  1  is suppressed. 
     In the flowchart in  FIG. 7 , Step S 40  or Step S 50  may be omitted. For example, in the case where Step S 40  is omitted, irrespective of whether pairing information is present, the recovery from the power-saving mode is permitted when profile information is present and when the tilt switch  5  has detected the motion of the electronic watch  1 . For example, in the case where Step S 50  is omitted, irrespective of whether profile information is present, the recovery from the power-saving mode is permitted when pairing information is present and when the tilt switch  5  has detected the motion of the electronic watch  1 . 
     Third Modification of Embodiment 
     Means for the electronic watch  1  to acquire the profile of a user is not limited to communication with the external device  3 . For example, profile information may be directly input to the electronic watch  1  by operation on an operation member provided to the electronic watch  1 . For example, the operation member that receives profile information may be a push button. When profile information is input by operation on the operation member, the electronic watch  1  records the profile information in the storage unit  28 . In this case, the electronic watch  1  can permit the supply of power to the acceleration sensor  4  at a time when necessary profile information is recorded in the storage unit  28 . 
     When operation to erase pairing information is performed by the user, the controller  23  may erase the pairing information and leave profile information without erasing the profile information. In this manner, when the user has changed the device model of the external device  3 , the user can change pairing information while the profile information is left in the storage unit  28 . 
     The permission condition is not necessarily required to include a condition that the profile information is recorded in the storage unit  28 . In other words, the controller  23  may permit the supply of power to the acceleration sensor  4  as long as pairing information is recorded in the storage unit  28  irrespective of whether profile information is recorded in the storage unit  28 . 
     The electronic watch  1  may be configured such that a user can prohibit the supply of power to the acceleration sensor  4 . In this case, for example, the supply of power to the acceleration sensor  4  may be stopped by operation by the user on the crown  27  or a push button. Alternatively, an instruction to stop the supply of power to the acceleration sensor  4  may be transmitted by wireless communication between the external device  3  and the electronic watch  1 . In this case, for example, the user stops the supply of power to the acceleration sensor  4  by operating an application on the external device  3 . In this manner, wasted power consumption in the electronic watch  1  can be reduced in a situation where the user does not need information from the acceleration sensor  4 . 
     The portable electronic devices in the above-mentioned embodiment and modifications are not limited to the exemplified electronic watches  1 . For example, the portable electronic device is not limited to an analog electronic watch that displays time by hands, and may be an electronic watch that displays time by digital display. The portable electronic device may be what is called smart watch. The portable electronic device is preferably a wristwatch type device, but may be a device other than the wristwatch type device. 
     The sensor that detects the amount of activity of a user is not limited to the acceleration sensor  4 , and may be, for example, a sensor that detects human body information such as a heartbeat sensor. The electronic watch  1  may have a position detection sensor such as a GPS and a sensor that detects ambient environments such as an ambient environment temperature sensor. The controller  23  may calculate the amount of activity of the user by using detection results of the position detection sensor and the sensor that detects ambient environments. The amount of activity of the user may be calculated in the external device  3 , or may be calculated by the external server  200 . 
     The contents disclosed in the above-mentioned embodiment and modifications can be executed in combination as appropriate. 
     The portable electronic device according to the embodiment includes: the sensor configured to detect a physical amount related to an amount of activity of a user; the communication unit configured to perform wireless communication; the controller configured to control supply of power to the sensor; the storage unit configured to record, when pairing between the communication unit and an external device used by the user is executed, pairing information between the communication unit and the external device; and the calculation unit that calculates the amount of activity of the user based on a detection result of the sensor. The permission condition under which the controller permits the supply of power to the sensor includes a condition that the pairing information is recorded in the storage unit. The portable electronic device according to the embodiment exhibits an effect that the supply of power to a sensor that detects the amount of activity is not permitted when pairing information is not recorded in the storage unit, and hence power consumption in the sensor can be suppressed. 
     Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.