You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
FIELD OF THE INVENTION 
       [0001]    The invention relates to an electronic key, and more specifically, to an electronic key used to remotely lock and unlock the doors of a vehicle. 
       BACKGROUND OF THE INVENTION 
       [0002]    In recent years, a passenger vehicle is often equipped with a so-called smart entry key system capable of locking/unlocking doors of the vehicle without using a mechanical key. The smart entry key system is mainly comprises a device mounted on the vehicle (hereinafter “on-board device” and “host vehicle” respectively) and an electronic key (hereinafter referred to as a “smart key”) carried by a user. When the user carrying the smart key, for example, approaches the host vehicle, the on-board device collates an ID code of the smart key. Then, when the on-board device confirms that the user is an authorized user of the host vehicle, the user can lock/unlock the doors of the host vehicle without using a mechanical key. 
         [0003]    It should be noted that the on-board device and the smart key transmit/receive signals to thereby collate the ID code in the smart entry key system. More specifically, the on-board device transmits a request signal within a predetermined range. Further, the request signal is a signal for requesting the smart key to transmit an ID code. 
         [0004]    When the user carrying the smart key approaches the host vehicle (enters the aforementioned predetermined range), the smart key receives the request signal transmitted by the on-board device. Upon receiving the request signal, the smart key transmits a response signal that includes an ID code to the on-board device. The on-board device receives the response signal and then determines whether the ID code included in the response signal matches a stored ID code registered in advance. 
         [0005]    The smart key constantly performs a reception operation to transmit/receive the signals as mentioned above to/from the on-board device. Thus, a battery (cell) integrated with the smart key is gradually exhausted, and that the doors of the host vehicle cannot be locked/unlocked when the battery runs out. It should be noted that in such a case, the user replaces the battery of the smart key or inserts the mechanical key (hereinafter referred to as an emergency key) accommodated in a smart key body into a cylinder lock of the host vehicle to lock/unlock the doors. 
         [0006]    For example, Japanese Patent Application Publication No. 2007-277927 (JP-A-2007-277927) discloses an art in which the function of a smart key is changed in accordance with whether an authenticated or an unauthenticated mechanical key is accommodated in the smart key. 
         [0007]    More specifically, the art described JP-A-2007-277927 turns off the power supply of the smart key when an unauthenticated mechanical key (e.g., someone else&#39;s mechanical key) is accommodated in the smart key body. That is, the art described, in JP-A-2007-277927 enables the smart key functions only when the authenticated mechanical key is accommodated in the smart key. 
         [0008]    However, the power supply of the smart key is constantly on to transmit/receive signals to/from the on-board device, and the smart key does not include a switch for turning the power supply off. Thus, when the smart key is not in use (i.e., when there is no need to transmit/receive signals to/from the on-board device), the power supply of the smart key is not turned off. Further, if the smart key includes a power supply switch, it becomes difficult to reduce the size of the smart key. 
         [0009]    Further, the art described in JP-A-2007-277927 does not turn off the power supply of the smart key when the smart key is not in use. In other words, the function of the smart key may be restricted (the power supply of the smart key can be turned off) only if an unauthenticated, mechanical key is accommodated in the smart key body. 
       SUMMARY OF THE INVENTION 
       [0010]    The invention provides an electronic key (a smart key) capable of changing, with a simple construction, a function as the smart key by means of an authenticated mechanical key accommodated in an electronic key (smart key) body. 
         [0011]    A first aspect of the invention relates to an electronic key. The electronic key includes an electronic key body that executes a function to communicate with and control a controller for an on-board device to drive a device mounted on a vehicle, and a mechanical key that fits a cylinder lock provided on the vehicle. The electronic key body includes an accommodation portion is formed in the electric key body to accommodate the mechanical key through insertion of the mechanical key, and a changeover device that changes over or restricts the function of the electronic key body. Further, the accommodation portion accommodates the mechanical key in a first accommodation mode or a second accommodation mode different from the first accommodation mode. The changeover device is operated only when the mechanical key is accommodated in the accommodation portion in the second accommodation mode. 
         [0012]    In the above electronic key, the function of the electronic key can be changed over or restricted by simply changing the insertion orientation of the mechanical key with which the electronic key body is equipped. Accordingly, the electronic key (the smart key) whose function as the smart key can be changed by the authenticated mechanical key accommodated in the electronic key (smart key) body with a simple construction can be provided 
         [0013]    The changeover device may open a power supply circuit in the electronic key body is equipped to disable the function of the electronic key body. 
         [0014]    Depending on the accommodation mode of the mechanical key, the power supply circuit may be opened to disable the function of the electronic key body. That is, based on the accommodation mode of the mechanical key, the power supply of the electronic key can be turned on or off. Therefore, there is no need to provide a separate power supply switch in the electronic key body. 
         [0015]    The changeover device may change an identification code which is assigned to the electronic key body, and which indicates whether the electronic key is an electronic key corresponding to the controller. 
         [0016]    In the above-described electronic key, if, for example, there is a vehicle A that is equipped with an on-board device with an ID code A registered, in advance and a vehicle B equipped with an on-board device with an ID code B registered in advance, the same electronic key may be used for the two vehicles simply by changing the accommodation mode of the mechanical key. 
         [0017]    The mechanical key may include a key plate and a shank, which serves as a handle of the mechanical key. The shank may be formed in a shape that is asymmetrical with respect to a longitudinally extending center line of the key plate. 
         [0018]    The mechanical key may include a key plate and a shank, which serves as a handle of the mechanical key, and the shank may assume a shape that differs depending on whether the mechanical key is accommodated in the first accommodation mode or the second accommodation mode. when viewed from the electronic key body. 
         [0019]    According to this electronic key, the difference between the first accommodation mode and the second accommodation mode can be recognized simply by taking a glance at the electronic key. Further, for example, a user can perceptually recognize the difference between accommodation of the mechanical key in the first accommodation mode and accommodation of the mechanical key in the second accommodation mode when holding the entire electronic key. Accordingly, there is no need to additionally provide means for indicating the difference between accommodation of the mechanical key in the first accommodation mode and accommodation of the mechanical key in the second accommodation mode. 
         [0020]    The function of the electronic key body may be remote keyless entry. 
         [0021]    The second accommodation mode may be realized by inverting the mechanical key accommodated in the first accommodation mode with respect to a longitudinal axis of symmetry of the key plate. 
         [0022]    According to this electronic key, a changeover between the first accommodation mode and the second accommodation mode is made simply by inverting the mechanical key with respect to a line parallel to a direction in which the mechanical key is inserted into the accommodation portion. Therefore, the function of the electronic key body can be easily changed over or restricted. 
         [0023]    The electronic key body may include an indicator that is identified from outside of the electronic key when the mechanical key is accommodated in the accommodation portion in the second accommodation mode. 
         [0024]    The indicator may be designed to project beyond an edge of the electronic key body. 
         [0025]    The electronic key body may further be equipped with a hooked member that turns so as to protrude outward from an edge of the electronic key body through abutment of a front end of the mechanical key on the hooked member when the mechanical key is accommodated in the accommodation portion in the second accommodation mode. 
         [0026]    According to the electronic key described above, the difference between the first accommodation mode and the second accommodation mode can be recognized simply by taking a glance at the electronic key. Further, for example, the user can perceptually recognize the difference between accommodation of the mechanical key in the first accommodation mode and accommodation of the mechanical key in the second accommodation mode when holding the entire electronic key. Accordingly, there is no need to additionally provide means for indicating the difference between accommodation of the mechanical key in the first accommodation mode and accommodation of the mechanical key in the second accommodation mode. 
         [0027]    A second aspect of the invention relates to a method of controlling an electronic key. In this case, the electronic key includes an electronic key body that executes a function to communicate with and control a controller for an on-board device to drive a device mounted on a vehicle, a mechanical key that fits a cylinder lock provided on the vehicle, and an accommodation portion that is formed in the electronic key body to accommodate the mechanical key. The method includes inserting the mechanical key in the accommodation portion in a first accommodation mode or a second accommodation mode; and executing an alternate function that is executed by the electronic key body when the mechanical key is inserted in the second accommodation mode. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The foregoing and further features and advantages of the invention will become apparent from the following description of example embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein: 
           [0029]      FIG. 1  is a block diagram showing the configuration of a smart entry key system including a smart key according to the embodiments of the invention; 
           [0030]      FIG. 2  shows the internal structure of a smart key body and an emergency key according to the first embodiment of the invention; 
           [0031]      FIG. 3  shows an example of an accommodation mode of the emergency key according to the first embodiment of the invention; 
           [0032]    FIG  4  shows the internal structure of a smart key body and an emergency key according to the second embodiment of the invention; and 
           [0033]      FIG. 5  shows an example of an accommodation mode of the emergency key according to the second embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0034]    A electronic key (hereinafter “smart key”)  10  according to the first embodiment of the invention will be described hereinafter with reference to the drawings.  FIG. 1  is a block diagram of the configuration of a smart entry key system that includes the smart key  10  according to this embodiment of the invention. It should be noted that in the following description, the smart entry key system is described in the context of use with a vehicle (e.g., a passenger vehicle which will be referred to hereinafter as an “host vehicle”). 
         [0035]    In  FIG. 1 , the smart key  10  according to this embodiment of the invention is a smart key that is carried by a user of the host vehicle to, for example, lock/unlock doors of the host vehicle. In addition, the host vehicle may also be equipped with a security device  2  and a vehicle control device  3 . 
         [0036]    First, the outline of the smart key  10  according to this embodiment of the invention will be described. 
         [0037]    The smart key which can remotely operate the locking/unlocking of the doors of the vehicle, is driven with a battery serving as a power supply. Further, the smart key  10  includes a mechanical key (hereinafter “emergency key”) that may be inserted into a cylinder lock of the host vehicle to lock/unlock the doors. The smart key  10  according to this embodiment of the invention may, for example, turn on/off the power supply of the smart key  10  in accordance with the accommodation mode of the emergency key within the smart key  10 . 
         [0038]    In  FIG. 1 , the smart key  10  is a smart key carried by the user of the host vehicle. The security device  2 , mounted on the host vehicle, receives signals transmitted from the smart key  10  and issues a command to the vehicle control device  3  of the host vehicle. Further, the security device  2  is connected to the vehicle control device  3  of the host vehicle. It should be noted that the smart key  10  is equivalent to an example of the electronic key according to the invention. 
         [0039]    First, the construction of the smart key  10  according to this embodiment of the invention will be described. As shown in  FIG. 1 , the smart key  10  according to this embodiment of the invention includes an emergency key  111 , a changeover switch  13 , a battery  14 , a transceiver  15 , a microcomputer  16 , an operation button  17 , and the like. 
         [0040]    The emergency key  111  is a mechanical key that is inserted into a key cylinder of the host vehicle to lock/unlock the doors. It should be noted that the emergency key  111  is utilized, for example, when the battery  14  integrated with the smart key  10  is exhausted. Therefore, the emergency key  111  is accommodated in a body of the smart key  10 . The emergency key  111  may be regarded as the mechanical key according to the invention. 
         [0041]    The changeover switch  13  opens and closes an electric circuit (not shown) including the microcomputer  16 , which is incorporated in the body of the smart key  10 . Although the details of the changeover switch  13  will be described later, the changeover switch  13  is operated by the emergency key  111  when the emergency key  111  is inserted into the body of the smart key  10  in the appropriate orientation. It should be noted that the changeover switch  13  may be regarded as the changeover device according to the invention. 
         [0042]    The battery  14  is a power supply for driving the transceiver  15  and the microcomputer  16 . The battery  14  may be a primary battery such as a button type battery or the like, or a rechargeable secondary battery. 
         [0043]    The transceiver  15  allows communication between the smart key  10  and the security device  2 , and transmits an ID code assigned to the smart key  10  to a transceiver  22  of the security device  2 . Further, the transceiver  15  receives a request signal transmitted by the security device  2 , and transmits to the security device  2  a response signal to the request signal. 
         [0044]    The microcomputer  16  includes memory in which the ID code assigned to the smart key  10  and the like are stored. For example, the microcomputer  16  transmits the ID code stored in the memory to the security device  2  via the transceiver  15 . The security device  2  then authenticates the smart key  10  if the ID code registered in advance in the security device  2  corresponds with the ID code transmitted from the smart key  10 . The microcomputer  16  of the smart key  10  may also transmit additional information, such as information regarding the remaining capacity of the battery  14  and the like to the security device  2 . 
         [0045]    The smart key  10  is carried by the user to, for example, lock/unlock the doors of the host vehicle. In general, therefore, an ID code that corresponds to the ID code registered in the on-board security device  2  provided in the host vehicle (hereinafter referred to as a corresponding ID code) is stored in the memory of the microcomputer  16  of the smart key  10 . 
         [0046]    Furthermore, an additional ID code may be stored in the memory of the microcomputer  16  of the smart key  10 . The smart key  10  according to this embodiment may transmit the additional ID via the transceiver  15 . 
         [0047]    The operation button  17 , when pressed, may operate various devices installed on the host vehicle. More specifically, after the security device  2  authenticates the smart key  10 , the user of the host vehicle may press the operation button  17  to transmit a command signal from the transceiver  15  of the smart key  10  to the security device  2 . The security device  2  then issues a command to the vehicle control device  3  of the host vehicle. In the smart entry key system, the locking/unlocking of the door locks of the host vehicle is a representative action resulting from the pressing of the operation button  17 . That is, the user may remotely lock/unlock the door locks of the host vehicle by pressing the operation button  17 . 
         [0048]    The action executed when the operation button  17  is depressed is not limited to the locking/unlocking of the door locks of the host vehicle. For example, the smart entry key system may instead lock/unlock a luggage compartment door or open/close power sliding doors of the host vehicle when the operation button  17  is pressed. The function executed by pressing of the operation button  17  will be referred to hereinafter as a remote keyless entry (RKE) function. 
         [0049]    Further, the locking/unlocking of the door locks of the host vehicle by the smart key  10  is not limited to the RKE function. For example, when a response signal transmitted to the security device  2  from the smart key  10  is authenticated by the security device  2 , the security device  2  may, for example, lock/unlock the door locks. That is, when the user of the host vehicle possesses the smart key  10  corresponding to the host vehicle and approaches the host vehicle, the security device  2  may automatically, for example, lock/unlock the door locks. A function exerted without the user&#39;s operation (i.e., a function equivalent to the function resulting from the pressing of the operation button  17 ) will be referred to hereinafter as a smart function. 
         [0050]    Next, the security device  2  mounted on the host vehicle will be described. It should be noted, as described above, that the security device  2  is connected to the vehicle control device  3  of the host vehicle. 
         [0051]    As shown in  FIG. 1 , the security device  2  includes a security electronic control unit (ECU)  21 , the transceiver  22 , and the like. 
         [0052]    The security ECU  21  includes at least an information processing circuit, such as, for example, a central processing unit (CPU) and a memory for storing data. The security ECU  21  authenticates the ID code transmitted by the transceiver  15  of the smart key  10  based on the ID code (the corresponding ID code) stored in the memory of the security ECU  21 . 
         [0053]    The transceiver  22  receives the signal including the ID code that is transmitted, by the transceiver  15  of the smart key  10 . Further, the transceiver  22  may constantly or periodically send out a request signal within a predetermined distance. 
         [0054]    If the security ECU  21  determines that authentication has been correctly carried out (i.e., when the ID code sent out by the smart key  10  coincides with the aforementioned corresponding ID code), various functions of the smart key  10  are enabled. For example, the security ECU  21  transmits a request signal to the smart key  10  via the transceiver  22  within a predetermined distance from the host vehicle. When the smart key  10  (the user possessing the smart key  10 ). enters the predetermined distance, it transmits a response signal to the security device  2 . 
         [0055]    In this case, when the smart key  10  has been authenticated, the security ECU  21  issues a command to the vehicle control device  3  to lock/unlock the doors of the host vehicle. Alternatively, the security ECU  21  may enable the function resulting from the pressing of the operation button  17  of the smart key  10  (the user presses the operation button  17  to lock/unlock the doors of the host vehicle). 
         [0056]    The vehicle control device  3  is connected to the security device  2  and mounted on the host vehicle. More specifically, the vehicle control device  3 , for example, releases electric door locks. of the host vehicle in accordance with a command from the security device  2 . 
         [0057]    Next, the internal structure of the body of the smart key  10  and the emergency key  111  according to this embodiment of the invention will be described with reference to  FIG. 2 . It should be noted in the following description that the portion of the smart key  10  in which the emergency key  111  is accommodated (in other words, the portion of the smart key  10  that serves as a case of the emergency key  111 ) is referred to as a smart key body  101 . That is, the assembly of the smart key body  101  and the emergency key  111  is referred to as the smart key  10 . It should be noted that the smart key body  101  may be regarded as the smart key body according to the invention. 
         [0058]      FIG. 2  shows the internal structure of the body of the smart key  10  and the emergency key  111  according to this embodiment of the invention. Further,  FIG. 2  shows entire views of the smart key body  101  and the emergency key  111  for the sake of explanation. It should be noted that when the user carries the smart key  10 , the emergency key  111  is usually accommodated in the smart key body  101 . Then, for example, when the battery  14  runs out, the user removes the emergency key  111  from the smart key body  101 , and inserts the emergency key  111  into the cylinder lock of the host vehicle to lock/unlock the doors. 
         [0059]    The internal structure of the smart key body  101  will be described with reference to  FIG. 2 . As shown in  FIG. 2 , an emergency key accommodation portion  121  is provided within the smart key body  101 . Further, the changeover switch  13  is provided at a distal end of the emergency key accommodation portion  121 . It should be noted that a line extending through the centers of short sides of the smart key body  101  shown in  FIG. 2  and parallel to long sides thereof is defined as broken lines A-A for the sake of explanation. 
         [0060]    The emergency key accommodation portion  121  is a space provided within the smart key body  101  (the broken lines of  FIG. 2 ) to accommodate the emergency key  111 . The changeover switch  13  is slid by the emergency key  111  when the emergency key  111  is accommodated in the emergency key accommodation portion  121 . 
         [0061]    It should be noted that the changeover switch  13  slides in a direction parallel with the broken lines A-A as indicated by a bidirectional arrow in  FIG. 2 . More specifically, the changeover switch  13  is urged toward the entrance of the emergency key accommodation portion  121 . That is, if the emergency key  111  is inserted in the emergency key accommodation portion  121 , the changeover switch  13  at the distal end of the emergency key accommodation portion  121  is depressed. On the other hand, if the emergency key  111  is removed from the emergency key accommodation portion  121 , the changeover switch  13  is released. 
         [0062]    It should be noted that the battery  14 , the transceiver  15 , the microcomputer  16 , as well as the emergency key accommodation portion  121  and the changeover switch  13  are provided inside the smart key body  101  as described above, but are not described or illustrated in the drawings. 
         [0063]    In FIG,  2 , the emergency key  111  will next be described. As shown in  FIG. 2 , the emergency key  111  includes a key plate portion  122  and a shank  123 . A line extending past the center of the key plate portion  122  and parallel to long sides of the key plate portion  122  is defined as broken lines B-B in  FIG. 2 . 
         [0064]    The key plate portion  122  is a mechanical key made of a metal or the like, has a key groove (not shown), and is inserted into the cylinder lock of the host vehicle to lock/unlock the doors. Further, the shank  123  (a grip held by the user when using the emergency key  111 ) is provided at the rear end of the key plate portion  122 . 
         [0065]    Further, as shown in  FIG. 2 , a region of a front end of the key plate portion  122  assumes a protrusive shape (the protrusive region of the front end will be referred to hereinafter as a protrusion  124 ). More specifically, as shown in  FIG. 2 , when the key plate portion  122  is divided along the broken lines B-B, one of the divided regions of the key plate portion  122  is longer than the other. That is, the front end of the key plate portion  122  is asymmetrically shaped with respect to the symmetry axis shown by the broken lines B-B. 
         [0066]    It should be noted in the following description that the direction parallel to the broken lines A-A and broken lines B-B shown in  FIG. 2  is referred to as a lateral direction, and that the direction perpendicular to the broken lines A-A and broken lines B-B shown in  FIG. 2  is referred to as a longitudinal direction. 
         [0067]    Further, the lateral width of the space of the emergency key accommodation portion  121  (the length in the direction parallel to the broken lines A-A provided inside the smart key body  101 ) is set in accordance with the lateral width of the key plate portion  122  (the length of the sides parallel to the broken tines B-B) such that the key plate portion  122  may fit within the emergency key accommodation portion  121 . 
         [0068]    However, as indicated by broken lines of  FIG. 2 , the shape of the emergency key accommodation portion  121  coincides with the shape of the key plate portion  122  when the key plate portion  122  is accommodated in the emergency key accommodation portion  121  in a predetermined orientation. In other words, a space is formed in the region of the emergency key accommodation portion  121  in which the protrusion  124  is fitted. That is, when the emergency key  111  shown in  FIG. 2  is inverted along the broken lines B-B, the shape of the key plate portion  122  does not coincide with the shape of the emergency key accommodation portion  121 . In this case, when the key plate portion  122  is inserted in the emergency key accommodation portion  121 , the protrusion  124  abuts the changeover switch  13  at the distal end of the emergency key accommodation portion  121 , thereby sliding and pressing the changeover switch  13 . 
         [0069]    A more concrete description will be given hereinafter using a diagram of an internal structure of the smart key body  101  and the emergency key  111  shown in  FIGS. 3A and 3B .  FIG. 3A  is a diagram showing an example in which the emergency key  111  is inserted in an orientation such that shape of the key plate portion  122  coincides with the shape of the emergency key accommodation portion  121 . As shown in  FIG. 3A , the emergency key  111  is inserted in an orientation where the shape of the key plate portion  122  coincides with the shape of the emergency key accommodation portion  121 . Accordingly, the changeover switch  13  is not actuated by the protrusion  124  of the key plate portion  122  when the emergency key  111  is inserted. 
         [0070]    On the other hand,  FIG. 3B  is a diagram showing an example in which the emergency key  111  shown in  FIG. 2  is inverted along the broken lines B-B before being inserted into the emergency key accommodation portion  121 . As shown in  FIG. 3B , when the emergency key  111  is thus inserted, the shape of the key plate portion  122  does not coincide with the shape of the emergency key accommodation portion  121 . Accordingly, the protrusion  124  abuts and actuates the changeover switch  13  into the distal end of the emergency key accommodation portion  121 . 
         [0071]    That is, the smart key  10  according to this embodiment of the invention is structured as described above, and hence can operate the changeover switch  13  (slide or refrain from sliding the changeover switch  13 ) in accordance with the accommodation mode in which the emergency key  111  is accommodated in the emergency key accommodation portion  121 . 
         [0072]    Further, as described above, the changeover switch  13  is designed to open or close the electric circuit that includes the microcomputer  16  incorporated in the body of the smart key  10 . Thus, for example, in designing the smart key body  101 , the changeover switch  13  may slide and turn the power supply of the smart key body  101  off (or turn power supply of the smart key body  101  on). In this design, the power supply of the smart key body  101  may. be turned on/off in accordance with the accommodation mode of the emergency key  111  the emergency key accommodation portion  121 . 
         [0073]    More specifically, the power supply of the smart key  10  is set to be turned off when the changeover switch  13  is depressed ( FIG. 3B ). In this manner, the power supply may be turned off simply by changing the accommodation mode of the smart key  10 . That is, the emergency key  111  may be used as a switch for the smart key  10  without requiring the installation of a separate switch. 
         [0074]    It should be noted that the changeover switch  13  is not limited in function to the turning on/off of the power supply of the smart key body  101 . For example, the RKE function is set to be turned off when the changeover switch  13  is depressed. In this manner, the operation of the operation button  17  may be nullified simply by changing the accommodation mode of the emergency key  111 . Alternatively, for example, the smart function is turned off when the changeover switch  13  is depressed. In this manner, the smart function may be turned off simply by changing the accommodation mode of the smart key  10 . 
         [0075]    Further, the function that is executed by pressing of the operation button  17  may be changed when the changeover switch  13  is depressed. For example, the default function of the operation button  17  may be set to operate the door locks of the host vehicle through the pressing of the operation button  17 . However, when the changeover switch  13  slides, the electric circuit including the microcomputer  16  incorporated in the body, of the smart key  10  is closed. Then, when the user of the host vehicle presses the operation button  17 , a command signal to open/close the doors (instead of locking/unlocking the door locks) is transmitted from the transceiver  15  of the smart key  10  to the security device  2 . In this manner, the function itself executed by pressing the operation button  17  may be changed (the locking/unlocking of the door locks/the opening/closing of the doors) simply by changing the accommodation mode of the emergency key  111 . As a result, the smart key  10  can be endowed with a variety of functions. 
         [0076]    Furthermore, an ID code originally assigned to the smart key  10  (referred to as an ID code A) may be changed when the changeover switch  13  is depressed. The microcomputer  16  transmits, for example, a new ID code instead of the ID code originally assigned to the smart key  10  (hereinafter, the new ID code will be referred to as “ID code B”) via the transceiver  15 , for example, when the changeover switch  13  slides. In this manner, if there are an host vehicle A, that is equipped with the security device  2  in which the ID rode A has been registered, and an host vehicle B (which is mounted with the security device  2  in which the ID code B is registered in advance), the host vehicle A and the host vehicle B may both be operated using the same smart key  10  simply by changing the accommodation mode of the emergency key  111 . 
         [0077]    That is, alternative functions of the smart entry key system may be enabled simply by changing the insertion orientation of the emergency key  111  in the smart key  10 . Thus, eliminating the need to provide a separate changeover switch in the smart key  10  for selecting the alternate functions. 
         [0078]    Further, the shank  123  of the emergency key  111  shown in  FIG. 2  is positioned asymmetrically with respect to the symmetry axis indicated by the broken lines B-B. For example, the power supply of the smart key body  101  may be set on when the emergency key  111  is oriented as shown in  FIG. 3A , and on the other hand, that the power supply of the smart key body  101  may be set off when the emergency key  111  is oriented as shown in  FIG. 3B . As shown in  FIG. 3B , the emergency key accommodation portion  121  is located above the broken lines (near an edge of the smart key body  101 ). Therefore, the shank  123  extends beyond the edge of the smart key body  101  when the power supply is off. Thus, the user can visually confirm that the power supply of the smart key body  101  is off. 
         [0079]    Because the shank  123  of the emergency key  111  is positioned asymmetrically with respect to the symmetry axis indicated by the broken lines B-B the different orientations of the emergency key  111 . shown in  FIG. 3A  and  FIG. 3B  may also be distinguished by feel. Thus, for example, if the smart key  10  is in a pocket, the user can determine whether the power supply of the smart key body  101  is off simply by touch. It should be noted that the internal structure of the smart key body  101  and the shape of the emergency key  111  as shown are merely examples. The emergency key accommodation portion  121  may be located at any suitable position and the shank  123  may be formed in any shape as long as a change in insertion orientation of the emergency key  111  is recognizable. 
         [0080]    Next, a smart key  11  according to the second embodiment of the invention will be described. In the first embodiment of the invention, the changeover switch is pressed by the front end of the emergency key to slide the mechanical key (see  FIG. 2 ). In the second embodiment of the invention, the changeover switch  13  is actuated perpendicularly to the direction in which the mechanical key is inserted via a hooked member. 
         [0081]    It should be noted in this embodiment of the invention as well as the first embodiment of the invention that the description is given on the assumption that a smart entry key system including the smart key  11  according to the second embodiment of the invention is used for a vehicle. 
         [0082]    The internal structure of a body of the smart key  11  and an emergency key  112  according to the second embodiment of the invention will be described below with reference to  FIG. 4 . 
         [0083]      FIG. 4  is a diagram showing the internal structure of the smart key body  102  and the emergency key  112  according to this embodiment of the invention. 
         [0084]    As shown in  FIG. 4 , an emergency key accommodation portion  121 , a hooked member  125 , a turning shaft  126 , and the changeover switch  13  are provided within the smart key body  102 . It should be noted in this embodiment, as well as the first embodiment, that the battery  14 , the transceiver  15 , the microcomputer  16 , and the like as well as the aforementioned components are provided inside the smart key body  101  but are not described or illustrated in the drawings. Further, for the sake of explanation, a line extending past the centers of short sides of the smart key body  102  shown in  FIG. 4  and parallel to long sides thereof is defined as broken lines C-C. 
         [0085]    The hooked member  125  may be an L-shaped member that is attached to the turning shaft  126  and Moves in the direction indicated by arrow of  FIG. 4 . Further, the hooked member  125  has a region extending perpendicularly from one end of the hooked member  125  in the direction of long sides. Then, when the protrusion  124  of the emergency key  112  abuts is pressed against the hook, the hooked member  125  turns around the turning shaft  126 , and actuates, at the other end, the changeover switch  13  perpendicularly to the direction in which the emergency key  112  slides (perpendicularly to the broken lines C-C); 
         [0086]    A more specific description will be given below using a diagram of the internal structure of the smart key body  102  and the emergency key  112  shown in  FIGS. 5A and 5B .  FIG. 5A  shows an example in which the emergency key  112  is inserted in an orientation in which the protrusion  124  of the emergency key  112  does not abut on the hooked member  125 . As shown in  FIG. 5A , in this manner, the protrusion  124  of the emergency key  112  is located below the region of the hooked member  125  that extends perpendicularly from one end in the direction of the long sides thereof. Therefore, the emergency key  112  may be accommodated without causing actuation of the hooked member  125  by the protrusion  124 . 
         [0087]    However,  FIG. 5B  shows an example in which the emergency key  112  shown in  FIG. 4  is inverted along broken lines D-D and inserted into the emergency key accommodation portion  121 . As shown in  FIG. 5B , in this manner, the front end of the protrusion  124  of the emergency key  112  abuts on a lateral face of that region of the hooked member  125 , which extends perpendicularly from one end in the longitudinal direction thereof. That is, when the emergency key  112  is inserted in the emergency key accommodation portion  121 , the front end of the protrusion  124  of the emergency key  112  abuts the region of the hooked member  125  and turns the hooked member  125  in the direction indicated by an arrow of  FIG. 5B . In addition, the changeover switch  13  is the other end of the hooked member  125  simultaneously pushed downward. 
         [0088]    As described above, the smart key  11  according to this embodiment of the invention operates the changeover switch  13  via the hooked member  125  in accordance with the accommodation mode of the emergency key  112  in the emergency key accommodation portion  121 . 
         [0089]    It should be noted in the first and second embodiments of the invention that the power supply of the smart key body  101  is turned off by sliding the changeover switch  13 . 
         [0090]    In addition, according to this embodiment of the invention, the emergency key accommodation portion  121  of the smart key  11  is located above the broken lines C-C of  FIG. 4  (close to the edge of the smart key body  102 ). As shown in  FIG. 5B , therefore, the hooked member  125  protrudes past the edge of the smart key body  102 . Thus, the user may visually confirm that the power supply of the smart key body  102  is off. 
         [0091]    It should be noted in both the first and second embodiments of the invention the shank  123  of the emergency key  112  assumes an asymmetrical shape with respect to the symmetry axis as depicted by the broken lines D-D. However, the invention is not restricted to this construction. That is, the shank  123  may assume any shape, as long as a change in the accommodation mode of the emergency key  112  is recognizable. 
         [0092]    For example, if the user of the host vehicle is given two emergency keys (one of which is a spare key) that may be accommodated in the smart key body when the host-vehicle is purchased, the shank of one of the emergency keys may have a different shape. Further, the user may be given a dedicated emergency key used to slide the changeover switch. 
         [0093]    As described above, according to the first and second embodiments of the invention, the series of the functions with which the smart key is endowed may be changed or restricted simply by changing the accommodation mode of the emergency key. 
         [0094]    The smart key according to each embodiment of the invention may be utilized as an smart key that, for example, locks/unlocks the door locks of a vehicle and can change, with a simple construction, the function as the smart key even when the authenticated mechanical key is accommodated in the body of the smart key. 
         [0095]    While the invention has been described with reference to the example embodiments thereof, it is to be understood that the invention is not limited to the described embodiments or constructions. To the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the disclosed invention are shown in various example combinations and configurations, other combinations and configurations, including more, less or only a single element, are also within the scope of the appended claims.

Summary:
An electronic key includes an electronic key body that executes a function to communicate with and control a controller for an on-board device to drive a device mounted on a vehicle, and a mechanical key that fits a cylinder lock provided on the vehicle. The electronic key body includes an accommodation portion that accommodates the mechanical key through insertion of the mechanical key, and a changeover device that changes over or restricts the function of the electronic key body. The mechanical key may be inserted into the accommodation portion in a first accommodation mode or a second accommodation mode, and the changeover device is operated only when the mechanical key is inserted in the accommodation portion in the second accommodation mode.