Abstract:
Proposed is a bracelet-type transmission/reception device comprising: a cartilage conduction vibration source provided in a portion to be attached to a wrist; a speaker; a variable directional microphone; and a control unit which sets the directivity of the variable directional microphone to the back side of a hand when the speaker is used and sets the directivity of the variable directional microphone to the palm side of the hand when the cartilage conduction vibration source is used. The bracelet-type transmission/reception device is provided together with a display means for information relating to a transmission/reception method or a handling explanation medium or advertising medium having the information relating to the transmission/reception method. An example of a method for use thereof is to conduct the vibration of the cartilage conduction vibration source to a thumb and to bring the thumb into contact with a tragus in a state where the back of the hand faces forward. The cartilage conduction vibration source is also used as a vibration source of an incoming vibrator, and when the cartilage conduction vibration source vibrates for cartilage conduction, a vibrational component in a low-frequency range that induces a sense of vibration is cut. The cartilage conduction vibration source vibrates for notification by announcement voice data in a storage unit.

Description:
TECHNICAL FIELD 
     The present invention relates to wristband-type handsets and wristband-type alerting devices. 
     BACKGROUND ART 
     Patent Document 1 proposes, as a method for using a bone-conduction speaker having a vibrating surface to be put on the tragus, adjusting by manual operation the pressure with which the vibrating surface is put on the tragus in order to adjust the proportions of cartilage-conducted sound information and air-conducted sound information according to the level of ambient noise (Patent Document 1). Patent Document 2 proposes conducting vibration generated by an actuator from a diaphragm to the human body, then conducting the vibration of the diaphragm from the wrist to a finger by bone conduction, and then putting the finger into the ear canal or the like so that an audio signal can be heard (Patent Document 2). In Patent Document 3, the present inventors propose converting, via a ring worn on a user&#39;s finger, an audio signal into cartilage-conducted vibration, which is then conducted to the finger. In this way, the audio signal in the form of vibration of the finger conducts, as cartilage-conducted sound, to the cartilage around the ear canal, producing air-conducted sound inside the ear canal so as to conduct to the eardrum, and partly conducting directly to the inner ear via the cartilage (Patent Document 3). Patent Document 4 proposes taking out a wrist watch attachment connected to a cable wound up on a cord reel inside a wrist watch-type mobile telephone, wearing the attachment on a fingertip, and putting the fingertip into the earhole so that vibration of a vibration-conducting device fitted to the wrist watch attachment is conducted directly to the ear (Patent Document 4). Patent Document 5 proposes, as an alerting device, an incoming-call sensing accessory for a mobile telephone in which a vibration-generating device that vibrates on detecting an incoming-call signal is built into an ornamental accessory such as a wristband (Patent Document 5). 
     LIST OF CITATIONS 
     Patent Literature 
     [Patent Document 1] Japanese Patent No. 4541111 
     [Patent Document 2] Japanese Patent Application Publication No. 2002-111822 
     [Patent Document 3] Japanese Patent Application Publication No. 2012-178695 
     [Patent Document 4] Japanese Patent Application Publication No. 2000-324217 
     [Patent Document 5] Japanese Patent Application Publication No. H11-163980 
     SUMMARY OF THE INVENTION 
     Technical Problem 
     However, with respect to handsets that achieve cartilage conduction via vibration of a hand, there still remain many issues to be addressed. With respect to speech-receiving methods and handsets that achieve cartilage conduction, there still remain many issues to be addressed. With respect to alerting devices, there still remains many issues to be addressed. 
     Against the background discussed above, one object of the present invention is to provide more effective handsets that achieve cartilage conduction via vibration of a hand, and another object of the present invention is to provide effective alerting devices for mobile telephones. 
     Means for Solving the Problem 
     According to one feature of the present invention, a wristband-type handset includes: a worn part worn on a wrist; a cartilage conduction vibration source provided in the worn part; a speaker; a variable-directivity microphone; and a controller for switching the directivity of the variable-directivity microphone according to which of the cartilage conduction vibration source and the speaker is used. Specifically, the wristband-type handset is configured as a wrist watch, a bracelet, a wristband, or the like. According to a specific feature, the controller directs the directivity of the variable-directivity microphone toward the back of a hand when the speaker is used, and directs the directivity of the variable-directivity microphone toward the palm of a hand when the cartilage conduction vibration source is used. 
     According to another specific feature, the wristband-type handset is offered along with explanatory information explaining a method of use involving putting the hand on which the worn part is worn in contact with an ear cartilage. According to a more specific feature, the explanatory information is offered by a means for displaying information on a speech-transmitting and -receiving method. The explanatory information may instead be offered in the form of an instruction manual medium containing information on a speech-transmitting and -receiving method. The explanatory information may instead be offered in the form of an advertisement medium containing information on a speech-transmitting and -receiving method. 
     In one example of a method of use according to a specific feature, vibration of the cartilage conduction vibration source is conducted to a thumb, and, with the back of the hand pointing frontward, the thumb is put in contact with a tragus to conduct the vibration of the cartilage conduction vibration source further to the tragus so that sound is heard by cartilage conduction. 
     According to another feature, a wristband-type handset includes: a worn part worn on a wrist; and a cartilage conduction vibration source provided in the worn part to produce vibration in an audible frequency range. The cartilage conduction vibration source is used also as a vibration source for an incoming-call vibrator. When the cartilage conduction vibration source is vibrated for cartilage conduction, the vibration component in a low frequency range arousing the sense of vibration is cut off. 
     According to a specific feature, when the cartilage conduction vibration source is vibrated for the incoming-call vibrator, the vibration component in the audible frequency range is cut off. According to another specific feature, there is provided a limiter for inhibiting vibration exceeding an intensity low enough not to arouse the sense of vibration when the cartilage conduction vibration source is vibrated for cartilage conduction. 
     According to another feature, a wristband-type alerting device includes: a storage for previously storing a plurality of pieces of alert audio data; a vibration source for vibrating for cartilage conduction; a near-field communicator for receiving an instruction signal from a mobile telephone; and a controller for selecting, according to the instruction signal received by the near-field communicator, a corresponding piece of alert audio data stored in the storage, and for making the vibration source vibrate in a frequency range of an audio signal for cartilage conduction according to the selected piece of alert audio data. According to another specific feature, the wristband-type alerting device is controlled by the controller so as to produce alert vibration in a frequency range arousing the sense of vibration according to the instruction signal received by the near-field communicator. 
     According to a specific feature, the wristband-type alerting device first produces alert vibration in the frequency range arousing the sense of vibration according to the instruction signal received by the near-field communicator, and then switches to vibration by the vibration source based on the audio data in the frequency range of an audio signal in order to allow the user to confirm the cause of the alert vibration. According to a more specific feature, the instruction signal contains information indicating that the battery of the mobile telephone is low, and the audio data contains an announcement indicating that the battery of the mobile telephone is low. According to another specific feature, the instruction signal contains information indicating that the mobile telephone is located outside the telephone service area, and the audio data contains an announcement indicating that the mobile telephone is located outside the telephone service area. 
     Advantageous Effects of the Invention 
     According to the present invention, it is possible to provide more effective handsets that achieve cartilage conduction via vibration of a hand, and to provide effective alerting devices. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view showing a system configuration of a first embodiment (Embodiment 1) of the present invention; 
         FIG. 2  is a diagram showing screens displayed on a watch display to explain call-conducting postures in Embodiment 1: 
         FIG. 3  is a diagram showing other screens displayed on a watch display to explain call-conducting postures in Embodiment 1; 
         FIG. 4  is a diagram showing still other screens displayed on a watch display to explain call-conducting postures in Embodiment 1; 
         FIG. 5  is a block diagram of Embodiment 1; 
         FIG. 6  is a flow chart showing the function of a controller of a wrist watch-type handset in Embodiment 1; 
         FIG. 7  is a flow chart showing, from another perspective, the function of a controller of a wrist watch-type handset in the Embodiment 1; 
         FIG. 8  is a diagram showing a screen displayed to explain a call-conducting posture in a wrist watch-type handset according to a second embodiment (Embodiment 2) of the present invention, accompanied by exterior views of a handset  104  in a worn state; 
         FIG. 9  is a system block diagram of Embodiment 2; 
         FIG. 10  is a diagram showing a screen displayed to explain a call-conducting posture in a wrist watch-type handset according to a third embodiment (Embodiment 3) of the present invention, accompanied by exterior views of a handset in a worn state; 
         FIG. 11  is an exterior perspective view of a wrist watch-type handset according to a fourth embodiment (Embodiment 4) of the present invention, accompanied by exterior views of a handset in a worn state; 
         FIG. 12  comprises exterior views of a wrist watch attachment-type handset, in a worn state, according to a fifth embodiment (Embodiment 5) of the present invention; 
         FIG. 13  is a system block diagram of Embodiment 5; 
         FIG. 14  is a perspective view showing a system configuration of a sixth embodiment (Embodiment 6) of the present invention; 
         FIG. 15  is a block diagram of Embodiment 6; 
         FIG. 16  is a flow chart showing the function of a controller of a wristband-type handset in Embodiment 6; 
         FIG. 17  is a flow chart showing the details of step S 58  in  FIG. 16 ; and 
         FIG. 18  is a flow chart showing the details of step S 64  in  FIG. 16 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiment 1 
       FIG. 1  is a perspective view showing a system configuration according to a first embodiment, Embodiment 1, of the present invention. Embodiment 1 is configured as a system comprising a mobile telephone  2  and a wrist watch-type handset  4 . The mobile telephone  2  is configured as a so-called smartphone having a display  6  with GUI (graphical user interface) capabilities. An operation panel  8  including a numeric keypad is displayed on the display  6 , and is operated on a GUI basis through touching and sliding operations on the display  6  with a finger. An infrared light emitter  12  and an infrared light receiver  14  constitute a proximity sensor for detecting the mobile telephone  2  being put on the ear. The mobile telephone  2  further includes an earphone  16 , a microphone  18 , and a front videophone camera  20 . The mobile telephone  2  also includes a rear main camera, though not illustrated in  FIG. 1 , behind the display  6 , and can communicate with the wrist watch-type handset  4  by near-field communication (NFC) using a radio wave  22  of a near-field communication system such as Bluetooth (a registered trademark). The mobile telephone  2  further includes a speaker for sounding ringtones and for delivering videophone sound, and for distinction from it, the other speaker on which the ear is put is referred to as the “earphone  16 ” as mentioned above. 
     The wrist watch-type handset  4  has a wrist watch body  26  and a belt  28 . The wrist watch body  26  is provided with a watch display  30  comprising a reflective liquid crystal display device, and provides ordinary time display as well as various other kinds of display as will be described later. The watch display  30 , of a touch panel-type, has a touch panel  30   a  on its display surface, and allows the user to operate the wrist watch-type handset  4 . The wrist watch body  26  is provided with a handset speaker  32 , and communicates with the mobile telephone  2  by near-field communication to allow the user to engage in a telephone call while viewing the wrist watch-type handset  4  even with the mobile telephone  2  stuck in, for example, a picket. A handset microphone will be described later. The wrist watch body  26  is further provided with a camera  34 , which shoots the face of the user him or herself viewing the watch display  30  while the face of the person at the other side is displayed on the watch display  30 , allowing the user to engage in a videophone call. 
     The wrist watch body  26  is provided with a cartilage conduction vibration source  36  comprising a piezoelectric bimorph element or the like, so that vibration for cartilage conduction is conducted from the reverse side of the wrist watch body  26  to the wrist. Likewise, the belt  28  too is provided with cartilage conduction vibration sources  38  and  40  each comprising a piezoelectric bimorph element or the like, so that vibration for cartilage conduction is conducted from the reverse side of the belt  28  to the wrist. The belt  28  is also provided with a conducting segment  41 , which is formed of a material having an acoustic impedance close to that of the wrist, and the cartilage conduction vibration sources  38  and  40  are arranged on or in the conducting segment  41 , so that their vibration conducts via the conducting segment  41 . Thus, from the wrist watch-type handset  4 , vibration for cartilage conduction is conducted over a large area around the wrist. A configuration like this, in which vibration is conducted from around the wrist over a large area, is effective in absorbing differences in the position suitable for vibration conduction among individual users, displacements of the wrist watch-type handset  4  while it is being worn, and so forth. Conducting vibration from around the wrist over a large area also helps conduct vibration for cartilage conduction to the arm more effectively. 
     Now, cartilage conduction will be explained. Cartilage conduction is a phenomenon discovered by the present inventors, and denotes the phenomenon in which vibration conducted to the cartilage around the entrance of the ear canal, such as that in the tragus, makes the surface of the cartilage part of the ear canal vibrate, producing air-conducted sound inside the ear canal. The air-conducted sound produced inside the ear canal travels on deeper into it to reach the eardrum. Thus, the greater part of the sound heard by cartilage conduction is the sound heard via the eardrum. However, here, the sound heard via the eardrum is not ordinary air-conducted sound, i.e., sound that has entered the ear canal from outside it, but air-conducted sound that is produced inside the ear canal. 
     The cartilage conduction vibration sources double as a vibration source for an incoming-call vibrator, and serve to notify an incoming call by conducting vibration to the wrist by vibrating when fed with an incoming call signal by near-field communication with the mobile telephone  2 . As will be described later, for cartilage conduction, the cartilage conduction vibration sources are vibrated in a frequency range of an audio signal (frequencies around 1000 Hz), and the vibration is conducted to the wrist with a frequency range that arouses the sense of vibration (e.g., 20 Hz or less) cut off so that no uncomfortable vibration may be sensed at the wrist. On the other hand, when vibrated as an incoming-call vibrator, the cartilage conduction vibration sources are vibrated around a frequency that arouses the sense of vibration (e.g., 20 Hz or less), with an audible frequency range cut off so that the vibration may not be heard by someone around. 
     The belt  28  is provided with a tightening mechanism  42 , which allows the user to loosen the belt  28  when wearing or removing the wrist watch-type handset  4 , and to tighten the belt  28  to keep the wrist watch-type handset  4  in a normal worn state. With the tightening mechanism  42 , the user can tighten the belt  28  further from the normal state within a range in which the user does not feel pain or discomfort to more reliably obtain cartilage conduction to the wrist. Such switching from the normal state to the cartilage conduction state by the tightening mechanism  42  can be made to take place by the user making a touch panel operation, pressing a switch  44  displayed on the watch display  30 . The user&#39;s action to press the switch  44  involves pressing the wrist watch body  26  onto the wrist, and thus serves as an action to bring the vibration of the cartilage conduction vibration source  36  in closer contact with the wrist. Needless to say, so long as sufficient cartilage conduction is obtained in the normal worn state, the user can conduct a call without pressing the switch  44 . 
     The belt  28  is further provided with a variable-directivity microphone  46  for the handset. In the videophone mode mentioned above, as indicated by an arrow  48 , the directivity of the variable-directivity microphone  46  is directed toward the back of the hand, so as to collect sound from in front of the watch display  30 . On the other hand, during a telephone call using cartilage conduction, as indicated by an arrow  50 , the directivity of the variable-directivity microphone  46  is so switched as to collect sound from the direction of the palm of the hand (typically the left hand) on which the wrist watch-type handset  4  is worn. This permits the user to conduct a telephone call in a posture as will be described later. The belt  28  is provided with vibration-isolating segments  52  and  54 , which are formed of a material having a different acoustic impedance than mentioned above, so that vibration from the cartilage conduction vibration sources  36 ,  38 , and  40  may not conduct to the variable-directivity microphone  46 . Along the belt  28 , an antenna  56  is provided so as to be wound around the wrist. 
       FIG. 2  is a diagram showing screens displayed on the watch display  30  to explain call-conducting postures in Embodiment 1 shown in  FIG. 1 . These screens are displayed each time the power switch of the wrist watch-type handset  4  is turned ON, but if that is annoying, a setting is also possible to skip those screens.  FIG. 2(A)  shows a screen explaining a call-conducting posture for a videophone call, in which posture the user conducts a videophone call while viewing the watch display  30  with the mobile telephone  2  placed in, for example, a pocket. In this posture, the directivity of the variable-directivity microphone  46  is directed toward the back of the hand as indicated by the arrow  48  in  FIG. 1 . 
       FIG. 2(B)  shows a screen explaining a posture for a cartilage-conduction call, in which posture the user conducts a telephone call with the forefinger of the hand (e.g., the left hand) on which the wrist watch-type handset  4  is worn put on the tragus (ear cartilage) of the ear (e.g., the left ear) on the same side. In this posture, so long as the finger does not close the earhole, the user can hear cartilage-conducted sound while also hearing outside sound. Incidentally, by pressing the tragus so hard as to close the earhole, the user can hear cartilage-conducted sound louder due to a closed ear canal effect. In this call-conducting posture, the vibration for cartilage conduction that is introduced at the wrist conducts to the forefinger, whose vibration then conducts to the tragus (ear cartilage). The user can thus hear the other side&#39;s voice well by cartilage conduction, while the user&#39;s own voice is conveyed to the other side by being collected by the variable-directivity microphone  46  which has its directivity directed toward the palm of the hand as indicated by the arrow  50  in  FIG. 1 . In this posture, the camera  34 , the handset speaker  32 , and the watch display  30  are kept OFF. These are automatically turned OFF in response to an acceleration sensor provided in the wrist watch body  26  detecting a change in posture from  FIG. 2(A)  to  FIG. 2(B) . 
       FIG. 3  is a diagram showing other screens displayed on the watch display  30  to explain call-conducting postures in Embodiment 1 shown in  FIG. 1 .  FIG. 3(A)  shows a screen explaining how, in the cartilage-conduction posture shown in  FIG. 2(B) , the user can press the switch  44  shown in  FIG. 1  with the right hand.  FIG. 3(B)  shows a screen explaining another posture using cartilage conduction, in which posture the user puts the thumb of the hand (e.g., the left hand) on which the wrist watch-type handset  4  is worn on the tragus (ear cartilage) of the ear (e.g., the left ear) on the same side. Also in this call-conducting posture, the user&#39;s own voice can be conveyed to the other side by being collected by the variable-directivity microphone  46  which has its directivity directed toward the palm of the hand. 
       FIG. 4  is a diagram showing still other screens displayed on the watch display  30  to explain call-conducting postures in Embodiment 1 shown in  FIG. 1 .  FIG. 4(A)  shows a screen explaining a call-conducting posture relying on cartilage conduction in which the user holds the arm (e.g., the left arm) on which the wrist watch-type handset  4  is worn across the face to put the forefinger on the tragus (ear cartilage) of the ear (e.g., the right ear) on the opposite side.  FIG. 4(B)  shows a screen explaining yet another call-conducting posture relying on cartilage conduction in which the user puts the bulge in a lower part of the palm of the hand (e.g., the left hand) on which the wrist watch-type handset  4  is worn on the ear (e.g., the left ear) on the same side. In this case, the bulge on the palm makes contact with the cartilage around the earhole over a large area. By hard pressing, the earhole can be closed. In both of the postures shown in  FIGS. 4(A) and 4(B) , the user&#39;s own voice can be conveyed to the other side by being collected by the variable-directivity microphone  46  which has its directivity directed toward the palm oft hand. 
       FIG. 5  is a block diagram of Embodiment 1 shown in  FIG. 1 ; there, such parts as appear also in  FIG. 1  are identified by common reference signs, and no overlapping description will be repeated unless necessary. The mobile telephone  2  is controlled by a controller  60 , which operates according to a program stored in a storage  58 . The storage  58  also can temporarily store data needed for the control by the controller  60 , and can store various kinds of measurement data and images. The display  6  provides display based on display data held in a display driver, under the control of the controller  60 . The display  6  has a display backlight, of which the brightness the controller  60  adjusts according to the ambient illumination. The display  6  has a touch panel, so that by touching the display  6 , the user can operate the mobile telephone  2 . 
     A speech transmission processor  62 , a microphone  18 , a speech reception processor  64 , and an earphone  16  constitute a telephone function section  66 , which can connect to a wireless communication network via a telephone communicator  68 , which is under the control of the controller  60 . Under the control of the controller  60 , a speaker  70  sounds ringtones, offers various kinds of audible guidance, and delivers the other side&#39;s voice during a videophone call. The audio delivered from the speaker  70  is not delivered from the earphone  16 . Under the control of the controller  60 , an image processor  72  processes the images shot by the front videophone camera  20  and the rear main camera  74 , and feeds the processed images to the storage  58 . 
     The mobile telephone  2  includes a near-field communicator  76  for communication with the wrist watch-type handset  4 , and an operation panel  78  including, among others, a main switch for turning ON and OFF the main power. The entire mobile telephone  2  is supplied with electric power from a power supply  80 , which has a rechargeable battery, which is charged by a contactless charger  82 . 
     The wrist watch-type handset  4  includes a near-field communicator  77  for communication with the mobile telephone  2 . The wrist watch-type handset  4  also includes a watch function section  84  for ordinary watch functions. An acceleration sensor  86  detects upward movement of the wrist watch-type handset  4  from  FIG. 1(A)  to (B) and downward movement of the wrist watch-type handset  4  from  FIG. 1(B)  to (A) to automatically switch the camera  34 , the handset speaker  32 , and the watch display  30  accordingly. 
     A power supply  88  of the wrist watch-type handset  4  and the power supply  80  of the mobile telephone  2  can be charged in a contactless fashion by the contactless charger  82  and a contactless charger  90  respectively. The wrist watch-type handset  4  and the mobile telephone  2  share information on each other&#39;s charge status by near-field communication to achieve coordination between them. Moreover, a GPS processor  92  detects movement of the user who is wearing the wrist watch-type handset  4 , and each time it does, it checks whether or not the mobile telephone  2  is left behind without being carried around, thereby to secure coordination between the wrist watch-type handset  4  and the mobile telephone  2 . Specifically, the GPS processor  92  checks whether or not the mobile telephone  2  has moved out of the near-field communication range as a result of the user&#39;s movement. 
     A driver  94  drives the cartilage conduction member  36  of the wrist watch body  26  and the cartilage conduction members  38  and  40  of the belt  28  all together to conduct vibration for cartilage conduction from around the wrist over a large area. In response to an instruction from a controller  98 , a sound processor  96  switches whether to make the driver  94  generate vibration for cartilage conduction or to make the speaker  32  generate air-conducted sound. In response to an instruction from the controller  98  via the sound processor  96 , the variable-directivity microphone  46  switches its directivity. The sound processor  96  also switches whether to make the driver  94  output an audio signal having a frequency range arousing the sense of vibration cut off or a vibration signal arousing the sense of vibration and having an audible frequency range cut off. The controller  98  operates according to a program stored in a storage  99 . The storage  99  also can temporarily store data needed for the control by the controller  98 , and can store various kinds of measurement data and images. 
     An operation panel  100  includes a button or the like for turning ON the main power, originating a call, and responding to a call. The watch display  30  is of a touch panel type as mentioned earlier, and has a touch panel  30   a , on which the switch  44  or the like is displayed. By touching the watch display  30 , the user can operate the mobile telephone  2 . 
       FIG. 6  is a flow chart showing the function of the controller  98  of the wrist watch-type handset  4  in Embodiment 1. The flow in  FIG. 6  focuses on operation for functions related to cartilage conduction; in reality, the wrist watch-type handset  4  involves operation of the controller  98  that does not appear in the flow in  FIG. 6 , such as for ordinary wrist watch functions for instance. Specifically,  FIG. 6  focuses on, among functions related to cartilage conduction, those for controlling the directivity of the variable-directivity microphone  46 , for switching between a frequency range arousing the sense of vibration and an audible frequency range, and for controlling the tightening of the belt  28 . To avoid complication, the other functions that have been described with reference to  FIGS. 1 to 5  are also omitted from illustration and description. 
     The flow in  FIG. 6  starts when the main power is turned ON on the operation panel  100  of the wrist watch-type handset  4 . At step S 2 , a start-up procedure is gone through, the functions of relevant blocks are checked, and ordinary watch display on the watch display  30  is started. Next, at step S 4 , explanations of different methods of use as shown in  FIGS. 2 to 4  are presented in a slide show. On completion of the explanations, the flow proceeds to Step S 6 . 
     At step S 6 , to make the cartilage conduction vibration sources  36 ,  38 , and  40  vibrate chiefly around a frequency that arouse the sense of vibration (e.g., 20 Hz or less) so that the incoming-call vibration may be not heard by someone around, the circuit is so switched as to cut off an audible frequency range from the driving signal, the flow then proceeding to Step S 8 . At this time, the cartilage conduction vibration sources  36 ,  38 , and  40  are not yet driven. If Step S 6  is reached with an audible frequency range already cut off, nothing is done at step S 6 , and the flow proceeds to Step S 8 . 
     At step S 8 , a sense-of-vibration inhibiting volume limiter is turned OFF, and the flow proceeds to Step S 10 . As will be described later, the sense-of-vibration inhibiting volume limiter is a limiter that operates, when the cartilage conduction vibration sources  36 ,  38 , and  40  are vibrated in an audible frequency range, to keep the sound volume under a predetermined level to prevent vibration in a low-frequency range that is not completely cut off from arousing an uncomfortable sense of vibration. The sense-of-vibration inhibiting volume limiter is provided in the sound processor  96 . When the cartilage conduction vibration sources  36 ,  38 , and  40  are vibrated as an incoming-call vibrator, the vibration is meant to arouse the sense of vibration. Accordingly, then, the sense-of-vibration inhibiting volume limiter is turned OFF, so that the sound volume can be raised to the maximum. If Step S 8  is reached with the sense-of-vibration inhibiting volume limiter in an OFF state, nothing is done at step S 8 , and the flow proceeds to Step S 10 . 
     At step S 10 , it is checked whether or not the operation panel  100  of the wrist watch-type handset  4  has been operated in response to an incoming-call signal delivered from the mobile telephone  2  by near-field communication, or whether or not a call-originating operation made on the operation panel  100  of the wrist watch-type handset  4  has been delivered to the mobile telephone  2  by near-field communication and a notice that the other side has responded to it has been delivered from the mobile telephone  2  by near-field communication. In a case where an incoming-call signal has been delivered, the cartilage conduction vibration sources  36 ,  38 , and  40  are vibrated as an incoming-call vibrator; here, these are vibrated with an audible frequency range cut off on the basis of the operation at step S 6 . If an operation responding to the incoming call has been made on the operation panel  100 , or if the call originated from the mobile telephone  2  has been responded to, this means that the mobile telephone  2  has started a call with the other side, and thus the flow proceeds to Step S 12 . 
     At step S 12 , the display of the other side&#39;s face on the watch display  30 , the shooting of the user&#39;s own face by the camera  34 , and the generation of air-conducted sound by the speaker  32  are all turned ON, and in addition the directivity of the variable-directivity microphone  46  is directed toward the back of the hand, the flow then proceeding to Step S 14 . At this time, the cartilage conduction vibration sources  36 ,  38 , and  40  are OFF. If Step S 12  is reached already with the watch display  30  ON, the camera  34  ON, the speaker  32  ON, and the directivity of the variable-directivity microphone  46  directed toward the back of the hand, nothing is done at step S 12 , and the flow proceeds to Step S 14 . Next, at step S 14 , the belt  28  is brought into a normal tightened state, and the flow proceeds to Step S 16 . If Step S 14  is reached with the belt  28  already in a normal tightened state, nothing is done at step S 14 , and the flow proceeds to Step S 16 . In this way, a call is started initially in a videophone mode, with the belt  28  in a normal tightened state. In the case of a voice-only call instead of a videophone call, out of the operations mentioned above, the display of the other side&#39;s face and the turning ON of the camera  34  are omitted. 
     At step S 16 , it is checked whether or not the acceleration sensor  86  has detected upward movement of the wrist watch-type handset  4  from  FIG. 2(A)  to (B). If so, then, at step S 18 , the display of the other side&#39;s face on the watch display  30 , the shooting of the user&#39;s own face by the camera  34 , and the generation of air-conducted sound by the speaker  32  are all turned OFF, and instead the cartilage conduction vibration sources  36 ,  38 , and  40  are turned ON. In addition, the directivity of the variable-directivity microphone  46  is directed toward the palm of the hand, and the flow proceeds to Step S 18 . If Step S 18  is reached already with the watch display  30  OFF, the camera  34  OFF, the cartilage conduction vibration sources  36 ,  38 , and  40  ON, and the directivity of the variable-directivity microphone  46  directed toward the palm of the hand, nothing is done at step S 18 , and the flow proceeds to Step S 20 . 
     At step S 20 , the cartilage conduction vibration sources  36 ,  38 , and  40  are vibrated in a frequency range of an audio signal (frequencies around 1000 Hz), with frequencies arousing the sense of vibration (e.g., 20 Hz or less) cut off so that no uncomfortable vibration may be sensed at the wrist, and the flow proceeds to Step S 22 . If Step S 20  is reached with a sense-of-vibration arousing frequency range already cut off, nothing is done at step S 20 , and the flow proceeds to Step S 22 . At step S 22 , the sense-of-vibration inhibiting volume limiter mentioned earlier is turned ON, and the flow proceeds to Step S 24 . If Step S 22  is reached with the sense-of-vibration inhibiting volume limiter already ON, nothing is done at step S 22 , and the flow proceeds to Step S 24 . 
     At step S 24 , whether or not the switch  44  is being pressed is checked. If so, then, at step S 26 , the tightening force of the belt  28  is increased, and the flow proceeds to Step S 28 . On the other hand, if the switch  44  is not detected being pressed, then, at step S 30 , the ordinary tightening force is restored, and the flow proceeds to Step S 28 . 
     At step S 28 , it is checked whether or not the acceleration sensor  86  has detected downward movement of the wrist watch-type handset  4  from  FIG. 2(B)  to (A), and if so, then at step S 12 , the videophone mode is restored. On the other hand, if, at step S 28 , no downward movement is detected (this state persists so long as a cartilage conduction call continues), the flow proceeds to Step S 32 , where whether or not the call has been disconnected is checked. If the call has not been disconnected, the flow returns to Step S 16 . Thereafter, until the call is detected having been disconnected at step S 32 , Steps S 12  through S 32  are repeated, so that switching between a cartilage-conduction call and a videophone call is performed to cope with change in posture, and the tightening force is changed according to whether or not the switch  44  is operated. If, at step S 32 , the call is detected having been disconnected, the flow proceeds to Step S 36 . 
     At step S 36 , it is checked whether or not the main power of the wrist watch-type handset  4  has been turned OFF. If not, the flow returns to Step S 6 , and thereafter, until the main power is detected having been turned OFF, Steps S 6  through S 36  are repeated. On the other hand, if, at step S 36 , the main power is detected having been turned OFF, the flow ends. 
       FIG. 7  is a flow chart showing, from another perspective, the function of the controller  98  of the wrist watch-type handset  4  in the Embodiment 1. Here again, the flow in  FIG. 7  focuses on operation for functions related to cartilage conduction; in reality, the wrist watch-type handset  4  involves operation of the controller  4  that does not appear in the flow in  FIG. 7 , such as for ordinary wrist watch functions for instance.  FIG. 7  focuses on, among functions related to cartilage conduction, those for controlling the directivity of the variable-directivity microphone  46 , for achieving coordination with the mobile telephone  2 , and so forth. To avoid complication, the other functions that have been described with reference to  FIGS. 1 to 5 , and the functions already described with reference to  FIG. 6 , are also omitted from illustration and description. For convenience&#39; sake, different functions appear separately in  FIGS. 6 and 7 ; in practice, the functions in  FIGS. 6 and 7  can be implemented in an integrated manner. 
     The flow in  FIG. 7  starts when the main power of the wrist watch-type handset  4  is turned ON. At step S 862 , a start-up procedure is gone through, the functions of relevant blocks are checked, and ordinary watch display on the watch display  30  is started. Next, at step S 864 , explanations of different methods of use as shown in  FIGS. 2 to 4  are presented in a slide show. On completion of the explanations, the flow proceeds to Step S 866 , where it is checked whether or not the GPS processor  92  has detected user movement. 
     If no user movement has been detected, then, at step S 868 , it is checked whether or not a scheduled time (e.g., occurring every five seconds) has arrived at which to secure coordination with the mobile telephone  2 . If so, the flow proceeds to Step S 870 . On the other hand, if, at step S 866 , the GPS processor  92  has detected user movement, the flow proceeds directly to Step S 870 . At step S 870 , it is checked whether or not the mobile telephone  2  has moved out of the near-field communication range, and if it is inside the near-field communication range, the flow proceeds to Step S 872 . At step S 872 , by near-field communication with the mobile telephone  2 , the power status of the wrist watch-type handset  4 , which is steadily displayed on the watch display  30 , is checked, and the result is transmitted to the mobile telephone  2 . The transmitted information is displayed on the mobile telephone  2 . Then, at step S 874 , information on the power status of the mobile telephone  2  is received by near-field communication, and the result is displayed on the watch display  30 , the flow then proceeding to Step S 876 . On the other hand, if, at step S 868 , a scheduled time has not arrived, the flow proceeds directly to Step S 876 . 
     At step S 876 , it is checked, by near-field communication, whether or not the mobile telephone  2  has received an incoming call, or whether or not a call-originating operation on the operation panel  6509  of the wrist watch-type handset  4  has been responded to by the other side. If either is the case, this means that a call with the other side has been started on the mobile telephone  2 , and thus the flow proceeds to Step S 878 , where the display of the other side&#39;s face on the watch display  30 , the shooting of the user&#39;s own face by the camera  34 , and the generation of air-conducted sound by the speaker  32  are all turned ON, and in addition the directivity of the variable-directivity microphone  46  is directed toward the back of the hand, the flow then proceeding to Step S 880 . At this time, the cartilage conduction vibration sources  36 ,  38 , and  40  are OFF. In this way, a call is started initially in a videophone mode. In the case of a voice-only call instead of a videophone call, out of the operations mentioned above, the display of the other side&#39;s face and the turning ON of the camera  34  are omitted. 
     At step S 880 , it is checked whether or not the acceleration sensor  86  has detected upward movement of the wrist watch-type handset  4  from  FIG. 2(A)  to (B). If so, then, at step S 882 , the display of the other side&#39;s face on the watch display  30 , the shooting of the user&#39;s own face by the camera  34 , and the generation of air-conducted sound by the speaker  32  are all turned OFF, and instead the cartilage conduction vibration sources  36 ,  38 , and  40  are turned ON. In addition, the directivity of the variable-directivity microphone  46  is directed toward the palm of the hand, and the flow proceeds to Step S 884 . 
     At step S 884 , it is checked whether or not the acceleration sensor  86  has detected downward movement of the wrist watch-type handset  4  from  FIG. 2(B)  to (A), and if so, then at step S 878 , the videophone mode is restored. On the other hand, if, at step S 884 , no downward movement is detected (this state persists so long as a cartilage conduction call continues), the flow proceeds to Step S 886 , where whether or not the call has been disconnected is checked. If the call has not been disconnected, the flow returns to Step S 880 . Thereafter, until the call is detected having been disconnected at step S 886 , Steps S 878  through S 886  are repeated, so that switching between a cartilage-conduction call and a videophone call is performed to cope with change in posture. On the other hand, if, at Step S 886 , the call is detected having been disconnected, the flow proceeds to Step S 888 . If, at step S 876 , no call is detected having been started, the flow proceeds directly to Step S 888 . 
     At step S 888 , it is checked whether or not a mobile telephone search operation has been made on the operation panel  100 . This operation is made, for example, when a user who is about to go out cannot find the mobile telephone  2 . When this operation is made, the flow proceeds to Step S 890 , where, by near-field communication with the mobile telephone  2 , an instruction signal is transmitted to the mobile telephone  2  to make it sound a ringtone (or actuate the vibrator), and the flow proceeds to Step S 892 . 
     On the other hand, if, at step S 870 , the mobile telephone  2  is detected having moved out of the near-field communication range, the flow proceeds to Step S 894 , where an indication is displayed to warn that the mobile telephone  2  is not being carried around, the flow then proceeding to Step S 892 . By various means as described above, coordination between the wrist watch-type handset  4  and the mobile telephone  2  is secured. 
     At step S 892 , it is checked whether or not the main power of the wrist watch-type handset  4  has been turned OFF, and if not, the flow returns to Step S 866 , so that thereafter, until the main power is detected having been turned OFF at step S 892 , Steps S 866  through S 892  are repeated. On the other hand, if, at step S 892 , the main power is detected having been turned OFF, the flow ends. 
     The various features of Embodiment 1 described above can be implemented not only in Embodiment 1 but also in any other embodiment so long as they provide their advantages. Moreover, as will be discussed below by way of some examples, the various features of Embodiment 1 can be implemented with various modifications. Modified features can be implemented in appropriate combinations with each other and with unmodified features. 
     For example, the vibration of the cartilage conduction vibration sources  38  and  40  conducts, via the conducting segment  41  in the belt  28 , also to the part of the belt  28  where the cartilage conduction vibration sources  38  and  40  are not located; thus, in a case where the conducting segment  41  has high conduction efficiency, one of the cartilage conduction vibration sources  38  and  40  may be omitted. A configuration is also possible where the vibration of the cartilage conduction vibration source  36  of the wrist watch body  26  is conducted to the conducting segment  41 . This configuration permits delivery of vibration from around the wrist over a large area even with the cartilage conduction vibration sources  38  and  40  both omitted. Conversely, a configuration is also possible where the conducting segment  41  is extended to the reverse side of the wrist watch body  26  so as to conduct to it the vibration of one or both of the cartilage conduction vibration sources  38  and  40 . This configuration permits even the cartilage conduction vibration source  36  to be omitted. In this way, so long as vibration for cartilage conduction can be conducted substantially over a large area around the wrist, a smaller number of cartilage conduction vibration sources, or a single cartilage conduction vibration source, will do. Conversely, a larger number of cartilage conduction vibration sources than in Embodiment 1 may be provided to boost the conduction of vibration for cartilage conduction from around the wrist over a large area. 
     Instead of the switch  44  being displayed on the watch display  30 , a button having a similar function may be provided at a position corresponding to the cartilage conduction vibration source  38  or  40  in the belt  28 . Also with this design, an action to press the button serves as an action to bring the cartilage conduction vibration source  38  or  40  in close contact with the wrist. The tightening force does not necessarily have to be switched manually in this way; a configuration is also possible where the tightening force is increased automatically when an upward acceleration is detected at step S 16  in  FIG. 6 . In that case, a brief voice message saying “the belt will be tightened” may be sounded before the speaker  32  is turned OFF at step S 18  so as not to surprise the user. For simplicity&#39;s sake, the tightening mechanism may be omitted, in which case the cartilage conduction vibration source  38  or  40  is brought into close contact with the wrist simply by the action of pressing the switch  44 . In this case, the switch  44  can be assigned a function of turning ON the vibration of the cartilage conduction vibration sources  38  and  40  for sound conduction. The switch  44  itself may be omitted, in which case guidance can be displayed on the watch display  30  to instruct the user to press somewhere near where the cartilage conduction vibration sources  38  and  40  are located. 
     Furthermore, Embodiment 1 is configured so as to conduct vibration from around the wrist over as large an area as possible, and so as to absorb differences in the position suitable for vibration conduction among individual users, displacements of the wrist watch-type handset  4  while it is being worn, and so forth. As another, contrastive embodiment, a configuration is also possible where the point of effective vibration conduction is measured for each individual so that vibration concentrates at the optimal position. Even in that case, with consideration given to displacements during use, some margin is allowed for with respect to the conduction area in which to concentrate vibration. 
     Instead of the variable-directivity microphone  46  in Embodiment 1, a wide-angle microphone may be adopted that can collect sound both from the direction of the back of the hand and from the direction of the palm of the hand. 
     Embodiment 2 
       FIG. 8  is a diagram showing a screen displayed to explain a call-conducting posture in a wrist watch-type handset  104  according to another embodiment, Embodiment 2, of the present invention, accompanied by exterior views of the handset  104  in a worn state. The wrist watch-type handset  104  according to Embodiment 2 shares the basic configuration with Embodiment 1 shown in  FIGS. 1 to 7 ; accordingly, in the following description, as to the basic configuration, complementary reference is made to  FIG. 1 , etc. as necessary. 
     Like Embodiment 1, Embodiment 2 is configured as a system comprising a mobile telephone  2  and a wrist watch-type handset  104  as shown in  FIG. 1 . The mobile telephone  2  here is similar to that in Embodiment 1, and therefore its description will be omitted. The wrist watch-type handset  104  too has much in common with its counterpart; therefore, common parts are identified by common reference numerals, and no overlapping description will be repeated unless necessary. 
     In Embodiment 2, as in Embodiment 1, screens for explaining call-conducting postures for the wrist watch-type handset  104  are displayed on a watch display  30 .  FIG. 8(A)  is a diagram showing a screen explaining a call-conducting posture for the wrist watch-type handset  104  according to Embodiment 2, and this call-conducting posture is basically similar to that shown in  FIG. 3(B)  in Embodiment 1. However, in Embodiment 2, the wrist watch-type handset  104  is configured differently: it is provided with a collapsible prop  105  which can be unfolded so as to rise from a palm-side part of a belt  128  along the inner side of the thumb  103 , and at a tip end part of the collapsible prop  105 , a cartilage conduction member  138  comprising a piezoelectric bimorph element or the like is supported.  FIG. 8(A)  shows a screen explaining a call-conducting posture in which the user obtains cartilage conduction by pressing the cartilage conduction member  138  onto the tragus with a tip end part of the thumb  103  while holding a middle part of the collapsible prop  105  between the base of the thumb  103  and the forefinger. As will be described later, the collapsible prop  105  is formed of a flexible sheet-form material such as plastic. When held between the base of the thumb  103  and the forefinger, the collapsible prop  105  develops a slight twist, which makes its tip end part fit along the ball of the thumb  103 . 
       FIGS. 8(B) to 8(D)  are enlarged views that focus on and around the hand out of the explanation screen, illustrating the operation of raising the collapsible prop  105  from a retracted state to a cartilage conduction state as seen from in front of the palm. That is,  FIGS. 8(B) to 8(D)  show a state where the wrist has been rotated by 180 degrees from the state in  FIG. 8(A) .  FIG. 8(B)  shows a retracted state, where the collapsible prop  105  is folded up into the belt  128  to lie along the belt  128 , with substantially no protrusion from it. Here, the cartilage conduction member  138  is in contact with the belt  128 , and, as in Embodiment 1, when used as a vibration source for an incoming-call vibrator, it conducts incoming-call vibration to the wrist via the belt  128 . 
       FIG. 8(C)  shows a state where the collapsible prop  105  has been unfolded halfway on the way before being raised fully. As will be understood from  FIG. 8(C) , the collapsible prop  105  divides into a base part  105   a  fastened to the belt  128 , a middle part  105   b , and a support part  105   c . At a tip end part of the support part  105   c , the cartilage conduction member  138  is supported. Between the base part  105   a  and the middle part  105   b  is a twist-bendable part, and between the middle part  105   b  and the support part  105   c  is a foldable part. The collapsible prop  105  is formed of a sheet-form material that is flexible and durable to repeated bending, such as plastic, so that the twist-bendable part and the foldable part are durable to repeated folding and unfolding. In  FIG. 8(C) , a hook  105   d  has been disengaged from a hook  105   e , so that the middle part  105   b  has been unfolded from the support part  105   c.    
     In  FIG. 8(D) , a hook  105   f  has been disengaged from a hook  105   g , and the middle part  105   b  has been twist-bent 90 degrees relative to the base part  105   a  (hidden in  FIG. 8(D) ) at the twist-bendable part. In this way, the middle part  105   b  and the support part  105   c  are raised to extend along the thumb  103 . Holding a middle part of the collapsible prop  105  between the base of the thumb  103  and the forefinger against the resilience of the collapsible prop  105  makes the collapsible prop  105  as a whole twist slightly, and this permits the cartilage conduction member  138 , supported at the tip end part of the support part  105   c , to fit along the ball of the thumb  103 . Thus, when the tip of the thumb  103  is pressed onto the tragus as shown in  FIG. 8(A) , the cartilage conduction member  138  is held between the thumb  103  and the tragus, achieving satisfactory cartilage conduction from the cartilage conduction member  138  to the tragus. 
     To collapse the collapsible prop  105 , the above procedure is gone through in the reverse direction, from  FIG. 8(D)  to  FIG. 8(B) : while the collapsible prop  105  is folded, the hook  105   f  is engaged with the hook  105   g , and then the hook  105   d  is engaged with the hook  105   e . The above-described operation for raising and collapsing the collapsible prop  105  can be performed, for example in a case where the wrist watch-type handset  104  is being worn on the left hand as shown in  FIG. 8 , with the right hand alone. 
     For the sake of convenience, the operation of raising the collapsible prop  105  from the state in  FIG. 8(B)  to the state in  FIG. 8(D) , and of collapsing the collapsible prop  105  from the state in  FIG. 8(D)  to the state in  FIG. 8(B) , is illustrated and described in multiple steps. The operation does not necessarily have to be performed in separate steps as in  FIG. 8 , but the whole operation can be performed as a continuous sequence performed with a part around the cartilage conduction member  138  held in the right hand; that is, it can be performed substantially in a single action. 
     The collapsible prop  105  can be formed of a plastic with a shape memory property so that it memorizes a shape halfway between the retracted state and the raised state and assumes this shape when left alone. Then, both when raised from the retracted state and when collapsed from the raised state, the collapsible prop  105  suggests how it is going to change shape toward the final one. This saves the user the trouble of figuring out how to operate, and facilitates the operation from the memorized shape to the final shape. 
       FIG. 9  is a system block diagram of Embodiment 2 shown in  FIG. 8 .  FIG. 9  has much in common with  FIG. 5 , which is a system block diagram of Embodiment 1; therefore, common parts are identified by common reference signs, and no overlapping explanation will be repeated unless necessary. In particular, the mobile telephone  2  in  FIG. 9  has the same configuration as in  FIG. 2 , and therefore its description will be completely omitted. 
     The wrist watch-type handset  104  in Embodiment 2 in  FIG. 9  differs from the wrist watch-type handset  4  in Embodiment 1 in  FIG. 1  in the additional provision of the collapsible prop  105  and in aspects associated with it. When the collapsible prop  105  is in the retracted state in  FIG. 8(B) , a switching prompter  107  detects the state and feeds a retraction detection signal to a controller  198 . In response to the retraction detection signal, the controller  198  controls the sound processor  96  such that the driver  94  makes the cartilage conduction member  138  vibrate around a frequency that arouses the sense of vibration (e.g., 20 Hz or less), with an audible frequency range cut off so that the vibration may not be heard by someone around. Thus, the cartilage conduction member  138  is used as a vibration source for an incoming-call vibrator. Moreover, in response to the retraction detection signal, the controller  198  controls the sound processor  96  such that the speaker  32  delivers an audio signal. Furthermore, in response to the retraction detection signal, the controller  198  controls the sound processor  96  such that the directivity of the variable-directivity microphone  46  is directed toward the back of the hand, and turns ON the watch display  30 . 
     On the other hand, when the collapsible prop  105  is detected being in the raised state in  FIG. 8(D) , the switching prompter  107  feeds a protraction detection signal to the controller  198 . In response to the protraction detection signal, the controller  198  controls the sound processor  96  such that the driver  94  makes the cartilage conduction member  138  vibrate in a frequency range of an audio signal (frequencies around 1000 Hz), with frequencies that arouse the sense of vibration (e.g., 20 Hz or less) cut off so that no uncomfortable vibration is sensed at the thumb  103 . Moreover, in response to the protraction detection signal, the controller  198  controls the sound processor  96  such that the speaker  32  is turned OFF, and that the directivity of the variable-directivity microphone  46  is directed toward the palm of the hand. At this time, the watch display  30  is turned OFF. 
     Embodiment 3 
       FIG. 10  is a diagram showing a screen displayed to explain a call-conducting posture in a wrist watch-type handset  204  according to yet another embodiment, Embodiment 3, of the present invention, accompanied by exterior views of the handset  204  in a worn state. The wrist watch-type handset  204  according to Embodiment 3 has much in common with Embodiment 2 shown in  FIG. 8 ; therefore, common parts are identified by common reference numerals, and no overlapping description will be repeated. 
     Like Embodiment 2, Embodiment 3 is configured as a system comprising a mobile telephone  2  and a wrist watch-type handset  204  as shown in  FIG. 1 . Also in Embodiment 3, as in Embodiment 2, screens explaining call-conducting postures for the wrist watch-type handset  204  are displayed on the watch display  30 .  FIG. 10(A)  shows a screen explaining a call-conducting posture for the wrist watch-type handset  204  according to Embodiment 3, and this call-conducting posture is similar to that in  FIG. 8(A) . 
     Embodiment 3 differs from Embodiment 2 in the configuration of a collapsible prop  205 . As in Embodiment 2, the collapsible prop  205  rises from a palm-side part of the belt  128  along the inner side of the thumb  103 , and at a tip end part of the collapsible prop  205 , a cartilage conduction member  238  comprising a piezoelectric bimorph element or the like is supported; however, the collapsible prop  205  here differs in some aspects such as structure and how it achieves cartilage conduction. Specifically, as shown in  FIG. 10(A) , the vibration of the cartilage conduction member  238 , comprising a piezoelectric bimorph element or the like, supported at the tip end part of the collapsible prop  205  is conducted to the base of the thumb  103 , and the vibration conducts farther on along the thumb  103  to reach a tip end part thereof. With the tip end part of the thumb  103  put on the tragus, cartilage conduction is achieved. In that vibration is conducted via the tissue of the hand, Embodiment 3 is similar to Embodiment 1. Accordingly, the collapsible prop  205  is shorter than in Embodiment 2, and has a simpler structure, having a single bendable part. 
       FIGS. 10(B) and 10(C)  are, as in Embodiment 2, enlarged views that focus on and around the hand out of the explanation screen, illustrating the operation of raising the collapsible prop  205  from a retracted state to a cartilage conduction state as seen from in front of the palm.  FIG. 10(B)  shows a retracted state, where, as in Embodiment 2, the collapsible prop  205  is folded up into the belt  128  to lie along the belt  128 , with substantially no protrusion from it. Here, the cartilage conduction member  238  is in contact with the belt  128 , and, as in Embodiment 2, when used as a vibration source for an incoming-call vibrator, it conducts incoming-call vibration to the wrist via the belt  128 . 
     As will be clear from  FIG. 10(B) , the collapsible prop  205  divides into a base part  205   a  fastened to the belt  128  and a support part  205   b , and the cartilage conduction member  238  is supported at a tip end part of the support part  205   b . Between the base part  205   a  and the support part  205   b  is a twist-bendable part. As in Embodiment 2, the collapsible prop  205  is formed of a sheet-form material that is flexible and durable to repeated bending, such as plastic, so that the twist-bendable part is durable to repeated folding and unfolding. 
       FIG. 10(C)  shows a state in which a hook  205   c  has been disengaged from a hook  205   d , so that the support part  205   b  has been twist-bent 90 degrees relative to the base part  205   a  (hidden in  FIG. 10(D) ) at the twist-bendable part. In this way, the support part  205   b  is raised toward the base of the thumb  103 . Holding a middle part of the collapsible prop  205  between the base of the thumb  103  and the forefinger against the resilience of the collapsible prop  205  makes the collapsible prop  205  as a whole twist slightly, and this permits the cartilage conduction member  238 , supported at the tip end part of the support part  205   c , to fit along the ball of the thumb  103 . Thus, when the tip of the thumb  103  is pressed onto the tragus as shown in  FIG. 10(A) , the vibration conducted from the cartilage conduction member  238  to the base of the thumb  103  conducts to the tragus in contact with the tip end of the thumb, achieving satisfactory cartilage conduction. 
     To collapse the collapsible prop  205 , the above procedure is gone through in the reverse direction, from  FIG. 10(C)  to  FIG. 10(B) : while the collapsible prop  205  is folded, the hook  205   c  is engaged with the hook  205   d . The above-described operation for raising and collapsing the collapsible prop  205  can be performed, for example in a case where the wrist watch-type handset  204  is being worn on the left hand as shown in  FIG. 10 , with the right hand alone. 
     Embodiment 4 
       FIG. 11  is an exterior perspective view of a wrist watch-type handset  304  according to still another embodiment, Embodiment 4, of the present invention, accompanied by exterior views of the handset  304  in a worn state. The wrist watch-type handset  304  according to Embodiment 4 has much in common with Embodiment 2 shown in  FIG. 8 ; therefore, common parts are identified by common reference signs, and no overlapping description will be repeated. 
     Like Embodiment 2, Embodiment 4 is configured as a system comprising a mobile telephone  2  and a wrist watch-type handset  304  as shown in  FIG. 1 . Embodiment 4 differs from Embodiment 2 in the provision of a support belt  305  in place of a collapsible prop  205 . As in Embodiment 2, the support belt  305  rises from a palm-side part of a belt  328  along the inner side of the thumb  103 , and at a tip end part of the support belt  305 , a cartilage conduction member  338  comprising a piezoelectric bimorph element or the like is supported; however, the support belt  305  here differs from the collapsible prop  205  in structure. 
       FIG. 11(A)  is an exterior perspective view of the wrist watch-type handset  304  according to Embodiment 4, showing a structure where the support belt  305  is detachably wound around the outer side of the belt  328 . In  FIG. 11(A) , solid lines indicate a state where the support belt  305  is wound around the outer side of the belt  328 , and in this state, the wrist watch-type handset  304  has an exterior appearance no different from that of an ordinary wrist watch. In this state, the support belt  305  is locked on a wrist watch body  326  by interlocked latches  309 . The interlocked latches  309  are provided respectively at opposite sides of the wrist watch body  326  (the one at the farther side is invisible, and is not shown). The interlocked latches  309  are so structured as to unlock when pressed in from opposite sides simultaneously but not to unlock even when only one of them is pressed in inadvertently. Unlocking the interlocked latches  309  makes the support belt  305  loose, at opposite ends, from the wrist watch body  326 . As in Embodiment 2, the support belt  305  is formed of a flexible sheet-form material. 
     In  FIG. 11(A) , dash-and-dot lines indicate a state of the support belt  305  where it has come loose from the wrist watch body  326  and has been at one end unwound rightward as seen in the diagram. At its other end, the support belt  305  is slidably coupled, via a pin  311  with an oval cross-section, into a slit  313  in the belt  328 . Thus, even in the state indicated by the dash-and-dot lines, the support belt  305  does not drop off the wrist watch body  326 . Owing to the combination of the pin  311  with an oval cross-section and the slit  313 , the support belt  305  can be slid only in the direction along the belt  328  so as to be drawn out from the state in  FIG. 11(A)  farther rightward as seen in the diagram. At one end (in the diagram, the right end) of the support belt  305 , the cartilage conduction member  338  is supported. 
       FIG. 11(B) to 11(E)  are, as in Embodiment 2, enlarged views that focus on and around the hand out of the explanation screen, illustrating the operation of raising the support belt  305  from a retracted state to a cartilage conduction state as seen from in front of the palm.  FIG. 11(B)  shows a retracted state, where, as in Embodiment 2, the support belt  305  lies along the belt  328 . Thus, as shown in  FIG. 11(A) , the belt  328  as a whole has an exterior appearance of an ordinary belt. Here, the cartilage conduction member  338  is in contact with the belt  328 , and, as in Embodiment 2, when used as a vibration source for an incoming-call vibrator, it conducts incoming-call vibration to the wrist via the belt  328 . The slit  313  has at one end a bent part  313   a , which guides the support belt  305  such that, as will be described later, it can rise along the thumb  103  and remain in that position. 
       FIG. 11(C)  shows a state (corresponding to the state in  FIG. 11(A) ) in which unlocking the interlocked latches  309  has made only one end of the support belt  305  loose from the wrist watch body  326 . Here, unlike in  FIG. 11(A) , the support belt  305  in a state still mostly wound around the wrist and pointing toward the little finger is viewed from in front of the palm, and thus the support belt  305  appears shorter than it really is. 
       FIG. 11(D)  shows a state where the support belt  305  has been drawn rightward as seen in the drawing, and the pin  311  with an oval cross-section has reached an end of the slit  313 . Up to this state, as described above, owing to the combination of the pin  311  with an oval cross-section and the slit  313 , the support belt  305  can slide only in the direction along the belt  328 . Once in the state in  FIG. 11(D) , the support belt  305  can be rotated in the counter-clockwise direction as seen in the diagram. 
       FIG. 11(E)  shows a state where, from the state in  FIG. 11(D) , the support belt  305  has been rotated farther and raised toward the thumb  103 . In this state, the pin  311  with an oval cross-section fits in the bent part  313   a , and prevents the support belt  305  from rotating farther from the state in  FIG. 11(E) . In this state, holding a middle part of the support belt  305  between the base of the thumb  103  and the forefinger against the resilience of the support belt  305  makes the support belt  305  as a whole twist slightly, and this permits the cartilage conduction member  338 , supported at the tip end part of the support belt  305 , to fit along the ball of the thumb  103 . Thus, when the tip of the thumb  103  is pressed onto the tragus, the cartilage conduction member  338  is held between the thumb  103  and the tragus, achieving satisfactory cartilage conduction from the cartilage conduction member  338  to the tragus. 
     For the sake of convenience, the operation of raising the support belt  305  from the state in  FIG. 11(C)  to the state in  FIG. 11(E) , and of putting away the support belt  305  from the state in  FIG. 11(E)  to the state in  FIG. 11(C) , is illustrated and described in multiple steps. The operation does not necessarily have to be performed in separate steps as in  FIG. 11 , but the whole operation can be performed as a continuous sequence performed with a part around the cartilage conduction member  338  held in the right hand; that is, it can be performed substantially in two actions, namely one action to unlock the interlocked latches  309  and another to raise the support belt  305 . 
     To retract the support belt  305 , the above procedure is gone through in the reverse direction, from  FIG. 11(E)  to  FIG. 11(B) : the support belt  305  is slid, and a part of the support belt  305  in which the cartilage conduction member  338  is provided is pressed onto the wrist watch body  326 ; this locks the interlocked latches  309 , and thus the support belt  305  is at opposite ends locked on the wrist watch body  326 . During the operation, the other end part of the support belt  305  slides toward the wrist watch body  326  while the pin  311  with an oval cross-section is guided along the bent part  313   a . Thus, no conscious positioning is required. The above-described operation for raising and retracting the support belt  305  can be performed, for example in a case where the wrist watch-type handset  304  is being worn on the left hand as shown in  FIG. 11 , with the right hand alone. 
     Embodiment 5 
       FIG. 12  comprises exterior views of a wrist watch attachment-type handset  404 , in a worn state, according to still another embodiment, Embodiment 5, of the present invention. The wrist watch attachment-type handset  404  according to Embodiment 5 has much in common with Embodiment 2 shown in  FIG. 8 ; therefore, common parts are identified by common reference signs, and no overlapping description will be repeated. 
     Like Embodiment 2, Embodiment 5 is configured as a system comprising a mobile telephone  2  and a wrist watch attachment-type handset  404  as shown in  FIG. 1 . Embodiment 5 differs from Embodiment 2 in that the handset is configured not as a wrist watch-type one but a wrist watch attachment-type one. A specific description follows. 
       FIG. 12(A)  to  FIG. 12(D)  are exterior views of a wrist watch  400  worn on the left hand as seen from in front of the palm.  FIG. 12(A)  shows an ordinary wrist watch  400  in a state where a belt  428  is visible from in front of the palm. On the other hand,  FIG. 12(B)  shows a state where the wrist watch attachment-type handset  404  according to Embodiment 5 has been attached to a palm-side part of the belt  428  from outside. Except that the wrist watch attachment-type handset  404  according to Embodiment 5 is a wrist watch attachment-type one, it has the same configuration for cartilage conduction as in Embodiment 2 in  FIG. 8 , and  FIGS. 12(B) to 12(D)  correspond to  FIGS. 8(B) to 8(D)  respectively. Therefore, corresponding parts are identified by common reference signs, and no overlapping description will be repeated. In Embodiment 5, the wrist watch  400  itself constitutes no part of a handset, and a whole configuration for speech transmission and reception by cartilage conduction in coordination with the mobile telephone  2  is implemented in the wrist watch attachment-type handset  404 . As for the exterior appearance in  FIG. 12 , the wrist watch attachment-type handset  404  is provided with a microphone  446 . 
       FIG. 13  is a system block diagram of Embodiment 5 shown in  FIG. 12 . As mentioned above, except that Embodiment 5 is a wrist watch attachment-type handset, it shares common features with Embodiment 2, and thus its system block diagram has much in common with that of Embodiment 2. Embodiment 5 has no functions for a wrist watch and exclusively has functions needed for a handset and an incoming-call vibrator relying on cartilage conduction. Accordingly, the configuration shown in  FIG. 13  is simpler than the configuration of Embodiment 2 shown in  FIG. 9 . Even so, such parts in  FIG. 13  as are identified by the same reference signs as in  FIG. 9  are similar to those in Embodiment 2, and therefore no overlapping description will be repeated unless necessary. 
       FIG. 13  differs from  FIG. 9  in the following aspects. An attachment detector  415  detects the wrist watch attachment-type handset  404  being attached to the wrist watch  400 ; it then turns the power ON automatically, and establishes near-field communication with the mobile telephone  2  automatically. It is also possible to turn ON and OFF the power and to establish near-field communication by separate manual operations. 
     As in Embodiment 2, in Embodiment 5 in  FIG. 13 , the vibration of the cartilage conduction member  138  is used as a vibration source for both cartilage conduction and an incoming-call vibrator. Specifically, with the collapsible prop  105  in the retracted state as shown in  FIG. 12(B) , the vibration of the cartilage conduction member  138  is used as a vibration source for a incoming-call vibrator. In Embodiment 5, on sensing the vibration of the incoming-call vibrator at the wrist, the user, without raising the collapsible prop  105 , that is, while leaving it in the state shown in  FIG. 12(B) , can put the thumb on the tragus as shown in  FIG. 3(B) . This change in posture is detected by the acceleration sensor  86 . Notified of the detection by the acceleration sensor  86 , a controller  498  switches the vibration of the cartilage conduction member  138  from vibration for an incoming-call vibrator to cartilage conduction vibration based on electronic voice in an audio data storage  417 . As a result, vibration conveying a brief voice message such as “a call from Mr. X” conducts from the cartilage conduction member  138  to the wrist. This vibration conducts farther from the wrist to the thumb, and with the tip of the thumb put on the tragus, the user can hear the voice message by cartilage conduction. Thus, before raising the collapsible prop  105 , the user can determine whether or not the call is from a person involved in an urgent matter and has to be responded to immediately. 
     To achieve that function, a storage  499  stores, in addition to operation programs and operation data for the entire wrist watch attachment-type handset  404 , telephone directory data for the mobile telephone  2 . The telephone directory data is updated as necessary by near-field communication with the mobile telephone  2 . The audio data in the audio data storage  417  is coordinated with the telephone directory data in the storage  499 , and is updated as necessary along with the telephone directory data. With this configuration, when the near-field communicator  77  receives from the mobile telephone  2  the ID of the person who has originated the call, it is checked against the telephone directory data in the storage  499 , and the corresponding audio data is output from the audio data storage  417 , so that the cartilage conduction member  138  is driven to produce sound. 
     As described above, in Embodiment 5, with the wrist watch attachment-type handset  404  attached to the belt  428  of an ordinary wrist watch  400 , the user can sense an incoming call to the mobile telephone  2  as vibration at the wrist. Moreover, with the thumb put on the tragus, the user can know, in an easy way by cartilage conduction, who has originated the call. If the call needs to be responded to, the user can the raise collapsible prop  105  and engage in the call by cartilage conduction. In this way, all the necessary actions can be coped with without taking out the mobile telephone  2 . 
     The various features of the embodiments described above can be implemented not only in those specific embodiments but also in any other embodiment so long as they provide their advantages. Moreover, the various features of the embodiments can be implemented with various modifications. Modified features can be implemented in appropriate combinations with each other and with unmodified features. 
     For example, in Embodiment 2, in a case where the collapsible prop  105  is formed of a plastic with a shape memory property, its shape in the raised state can be memorized so that it assumes that shape when left alone. Then, with the hooks  105   d  to  105   g  disengaged, the collapsible prop  105  automatically rises to the state in  FIG. 8(D) . The twist-bendable part and the foldable part can each be given a hinge structure and be fitted with a spring that biases it in the rising direction. Also with this design, with the hooks  105   d  to  105   g  disengaged, the collapsible prop  105  automatically rises to the state in  FIG. 8(D) . 
     In Embodiment 2, raising the cartilage conduction member  138  onto the thumb  103  requires unfolding at two places, and in Embodiment 3, raising the cartilage conduction member  238  onto the base of the thumb  103  requires unfolding at one place. This, however, is not meant to limit the folding structure. For example, so long as a necessary length can be secured, a configuration is also possible where raising a cartilage conduction member onto the thumb requires unfolding at one place, or depending on the retracting structure, a configuration is also possible where raising a cartilage conduction member onto the base of the thumb requires unfolding at a plurality of places. To permit a cartilage conduction member to be raised onto the base of the thumb, a support belt  305  like the one in Embodiment 4 may be adopted. In that case, considering an ample length that can be secured, the slide structure using the slit  313  may be omitted, so that only the structure for rotation between  FIG. 11(D)  and  FIG. 11(E)  is adopted. 
     Embodiment 6 
       FIG. 14  is a perspective view showing the system configuration of still another embodiment, Embodiment 6, of the present invention. Embodiment 6 is configured as a system comprising a mobile telephone  2  and a wristband-type handset  504 . In Embodiment 6 in  FIG. 14 , the mobile telephone  2  has the same configuration as in Embodiment 1; therefore, common parts are identified by the same reference signs as in  FIG. 1 , and no overlapping description will be repeated. As in Embodiment 1, the mobile telephone  2  and the wristband-type handset  504  can communicate with each other by near-field communication such as Bluetooth (a registered trademark). 
     The wristband-type handset  504  according to Embodiment 6 has a belt  528 , which is an elastic member formed of a material having an acoustic impedance similar to that of the wrist. The belt  528  is provided with vibration sources  536 ,  538 ,  540 , and  542  each comprising a piezoelectric bimorph element or the like, so that incoming-call vibration as well as vibration for cartilage conduction is conducted from the reverse side of the belt  528  to the wrist. Thus, from the wristband-type handset  504 , incoming-call vibration as well as vibration for cartilage conduction is conducted over a large area around the wrist. A configuration like this, where vibration is conducted from around the wrist over a large area, is effective in absorbing differences in the position suitable for vibration conduction among individual users, displacements of the wristband-type handset  504  while it is being worn, and so forth. Moreover, conducting vibration from around the wrist over a large area also helps conduct incoming-call vibration as well as vibration for cartilage conduction to the arm more effectively. Depending on the design, incoming-call vibration as well as vibration for cartilage conduction can be conducted over a large area around the wrist with the vibration of the entire belt  528 . This makes it possible to adopt a simple configuration with a reduced number of vibration sources as necessary (with a single vibration source at the minimum). 
     For cartilage conduction, the vibration sources  536 ,  538 ,  540 , and  542  are vibrated in a frequency range of an audio signal (frequencies around 1000 Hz), and the vibration is conducted to the wrist with a frequency range that arouses the sense of vibration (e.g., 20 Hz or less) cut off so that no uncomfortable vibration is sensed at the wrist. On the other hand, when vibrated as an incoming-call vibrator, the vibration sources  536 ,  538 ,  540 , and  542  are vibrated in and around a frequency range that arouses the sense of vibration (e.g., 20 Hz or less) with an audible frequency range cut off so that the vibration is not heard by someone around. Along the belt  528 , an antenna  556  of an near-field communicator is provided so as to be wound around the wrist. These features are common to Embodiment 1. The driving of the vibration sources  536 ,  538 ,  540 , and  542  and the near-field communication with the mobile telephone  2  via the antenna  556  are performed by a circuit unit  530 . 
     In Embodiment 6 configured as described above, when the mobile telephone  2  receives an incoming call or the like, the vibration sources  536 ,  538 ,  540 , and  542  start to vibrate in a frequency range that arouses the sense of vibration, and the vibration is conducted to the wrist. The user can thus notice the incoming call. Next, when the user needs more information, the user assumes any posture, like those in  FIGS. 2(B), 3(B), 4(A) , and  4 (B), in which a finger or hand is put in contact with the ear cartilage. This change in posture is automatically detected by an acceleration sensor provided in the circuit unit  530 . As a result, the vibration of the vibration sources  536 ,  538 ,  540 , and  542  is switched to a frequency range of an audio signal, and information about the other side based on audio data previously stored in the circuit unit  530  is output as sound vibration. Thus, with a finger or hand put in contact with the ear cartilage, by cartilage conduction, the user can obtain information as to who has originated the call, whether the call is a voice call or a text message (mail), and so forth. The cartilage conduction vibration output is, for example, an announcement such as “a phone call from Mr. Yamada” or “a text message from Mr. Suzuki”. Once an announcement is started, it is repeated until the user makes, on the mobile telephone  2 , an operation to start the call or an operation to stop vibration manually. 
     Vibration in a frequency range that arouses the sense of vibration, and vibration in a frequency range of an audio signal, can be started in response to near-field communication with the mobile telephone  2  not only on receiving an incoming call but also on starting communication with the mobile telephone  2  with any unread text message received before the start of communication, on detecting low battery on the mobile telephone  2 , on detecting the mobile telephone  2  having moved out of the telephone service area, and so forth. When the wristband-type handset  504  has low battery, the just-mentioned vibration can be started under the control of the controller of the wristband-type handset  504  itself. The user can recognize the causes of the vibration in those different occasions by assuming, as described above, any posture, such as those in  FIGS. 2(B), 3(B), 4(A) , and  4 (B), in which a finger or hand is put in contact with the ear cartilage. 
       FIG. 15  is a block diagram of Embodiment 6 shown in  FIG. 14 , and there, such parts as appear also in  FIG. 1  are identified by the same reference numerals as in  FIG. 1 , and no overlapping description will be repeated unless necessary. Except for the vibration sources  536 ,  538 ,  540 , and  542 , the block of the wristband-type handset  504  in  FIG. 15  corresponds to the details of the circuit unit  530  in  FIG. 14 . The block of the mobile telephone  2  is the same as in  FIG. 5 ; therefore, the same parts are identified by the same reference numerals, and no description will be repeated. 
     The wristband-type handset  504  has a near-field communicator  77  for communication with the mobile telephone  2 . In Embodiment 6, conveyed from the mobile telephone  2  via the near-field communicator  77  is one of the following pieces of information: the fact that there is an incoming call; whether or not the call is a voice call or a text message; the identity of the person who is originating the voice call or the text message; the fact that the battery is low on the mobile telephone  2 ; and the fact that the mobile telephone  2  is outside the telephone service area. In response, the vibration sources  536 ,  538 ,  540 , and  542  start to be vibrated. Between the mobile telephone  2  and the wristband-type handset  504 , information is exchanged via the near-field communicator  77  to share telephone directory information. When a new item of telephone directory information is added on the mobile telephone  2 , it is conveyed via the near-field communicator  77  to the wristband-type handset  504 , and is stored in the storage  99 . In this way, information about the person who is originating a voice call or a text message is, as simple ID information, conveyed from the mobile telephone  2  to the wristband-type handset  504 , and is checked against the previously stored telephone directory information. This makes it possible to make an announcement about the person who is originating a voice call or a text message. 
     The wristband-type handset  504  is controlled by a controller  598 . In an initial state, that is, in a state where the main power has just been turned ON on an operation panel  500 , the controller  598  selects, via a switch  591 , a vibration signal generator  593  to make, via a driver  594 , the vibration sources  536 ,  538 ,  540 , and  542  vibrate in a frequency range that arouses the sense of vibration. Accordingly, when one of an incoming-call signal, a telephone directory ID of the person who is originating the voice call or the text message, a signal indicating the presence of an unread text message, an indication of low battery on the mobile telephone  2 , and an indication of the mobile telephone  2  being outside the telephone service area is conveyed from the mobile telephone  2  via the near-field communicator  77 , vibration based on the vibration signal generator  593  is generated. 
     On the other hand, when a change in posture is detected by the acceleration sensor  86 , the switch  591  selects, via the switch  591 , an audio processor  596 . Then, audio data stored in an audio data storage  595  is processed by the audio processor  596 , and based on its output, the vibration sources  536 ,  538 ,  540 , and  542  are vibrated via the driver  594 . Thus, an announcement can be heard by cartilage conduction via a hand or finger put in contact with the ear cartilage. The audio data to be processed by the audio processor  596  is selected by the controller  598  based on the information conveyed from the mobile telephone  2 . 
       FIG. 16  is a flow chart showing the function of the controller  598  of the wristband-type handset  504  in Embodiment 6. The flow in  FIG. 6  starts when the main power is turned ON on the operation panel  500  of the wristband-type handset  504 . At step S 42 , a start-up procedure is gone through, and the functions of relevant blocks are checked. Next, at step S 44 , it is checked whether or not the wristband-type handset  504  and the mobile telephone  2  are in a mutually communicable state (whether or not they are paired together), and if so, the flow proceeds to Step S 46 . 
     At step S 46 , the vibration signal generator  593  is selected. Then, at step S 48 , it is checked whether or not a new item of telephone directory information has been received from the mobile telephone  2 . If a new item of telephone directory information has been received, then, at step S 50 , the new item of telephone directory information is stored in the storage  99 , and audio data for reading aloud the name of a person in the new item of telephone directory information is created and stored, along with a telephone directory ID, in the audio data storage  595 , the flow then proceeding to Step S 52 . If, at step S 48 , no new item of telephone directory information is detected having been received, the flow proceeds directly to Step S 52 . 
     At step S 52 , whether or not there is an incoming call or the like is checked. Here, “an incoming call or the like” can be a voice call or a text message that is being received or a text message that was received in the past and has been left unread up to the time point that step S 52  is reached as a result of a pair being newly established at step S 44 . If there is no incoming call or the like, then, at step S 54 , it is checked whether or not the battery is low on the mobile telephone  2  proper or on the wristband-type handset  504 . If neither is the case, then, at step S 56 , it is checked whether or not the mobile telephone  2  proper has moved out of the telephone service area. 
     If, at step S 52 , there is an “incoming call or the like”, or if, at step S 54 , a battery is detected being low, or if, at step S 56 , the mobile telephone  2  proper is detected having moved out of the telephone service area, then the flow proceeds to Step S 58 . At step S 58 , an alert vibration starting process is performed to make the vibration sources  536 ,  538 ,  540 , and  542  vibrate based on a vibration signal from the vibration signal generator  593 . The process will be described in detail later. On completion of the alert vibration starting process, the flow proceeds to Step S 60 . 
     At step S 60 , it is checked whether or not the acceleration sensor  86  has detected an upward acceleration as the user moves a hand to assume a posture for putting a finger or hand on the ear cartilage. If an upward acceleration is detected, then, at step S 62 , the switch  591  is instructed to perform switching to select the audio processor  596 , the flow then proceeding to Step S 64 . At step S 64 , an audio driving starting process is performed to make an announcement based on an audio signal from the audio processor  596 . The process will be described in detail later. On completion of the audio driving starting process, the flow proceeds to Step S 66 . If, at step S 60 , no upward acceleration is detected, the flow proceeds directly to Steps S 66 . In this case, no switching from the vibration signal generator  593  to the audio processor  596  is performed, and thus vibration is continued in a frequency range that arouses the sense of vibration. 
     At step S 66 , it is checked whether or not a manual vibration stopping operation has been made on the operation panel  500 . If no vibration stopping operation is detected, then, at step S 68 , it is checked whether or not a call starting operation has been made on the mobile telephone  2  proper. If, at Step S 66 , a vibration stopping operation is detected, or if a call starting operation is detected having made on the mobile telephone  2  proper, then, at step S 70 , vibration based on an audio signal or vibration in a frequency range that arouses the sense of vibration is stopped, and the flow proceeds to Step S 72 . If, at step S 56 , the mobile telephone  2  proper is not detected having moved out of the telephone service area, the flow proceeds directly to Step S 70 . Here, if there is no vibration, nothing is done at step S 70 , and the flow proceeds to Step S 72 . On the other hand, if, at step S 68 , no call staring operation is detected on the mobile telephone  2  proper, the flow returns to Step S 60 , and thereafter, until a vibration stopping operation is detected at step S 66 , or until a call starting operation is detected on the mobile telephone  2  proper at step S 68 , Steps S 60  through S 68  are repeated. Meanwhile, vibration in a frequency range that arouses the sense of vibration or, if switching has taken place, vibration based on an announcement signal from the audio processor  596  is continued. 
     Incidentally, if, at step S 44 , no pair is detected having been established (including when one has been unpaired), the flow immediately proceeds to Step S 72 . At step S 72 , it is checked whether or not the main power has been turned OFF on the operation panel  500 , and if the main power is detected having been turned OFF, the flow ends. On the other hand, if, at step S 72 , the main power is not detected having been turned OFF, then the flow returns to Step S 44 , so that thereafter, until the main power is detected having been turned OFF at step S 72 , Steps S 44  through S 72  are repeated. In this way, a newly established pair is coped with and, if a pair has already been established, various changes in situation that require new generation of vibration are coped with. 
       FIG. 17  is a flow chart showing the details of the alert vibration starting process at step S 58  in  FIG. 16 . When the alert vibration starting process starts, at step S 82 , whether or not vibration has already been started is checked. If vibration has already been started, the flow immediately ends, and the flow in  FIG. 16  is resumed from Step S 60 . If no vibration has yet been started, then, at Step S 84 , it is checked whether or not an incoming call has been received. If no incoming call has been received, then, at Step S 86 , it is checked whether or not there is any unopened text message. Step S 86  allows detection of a text message that was received before establishment of a pair and has been left unread since. If, at Step S 84 , an incoming call is detected, or if, at Step S 86 , an unopened text message is detected, the flow proceeds to Step S 88 . 
     At Step S 88 , it is checked whether or not the other side is a “response-suspendible caller”, that is, a person from whom an incoming call does not need to be responded to immediately. If not, the flow proceeds to Step S 90 . A person who does not require so much attention as to rely on the wristband-type handset  504  can be, even if an incoming call from him or her is missed, coped with later with reference to an incoming-call history. Thus, by classifying a person who is not involved in an urgent matter as a response-suspendible caller, it is possible to avoid the annoyance of the wristband-type handset  504  vibrating unnecessarily. 
     At Step S 90 , it is checked whether the incoming call is a voice call. If it is a voice call, then, at Step S 92 , incoming-call alert vibration is started with a pattern that indicates a voice call, and the flow ends. On the other hand, if, at Step S 90 , the incoming call is not detected being a voice call, it means that it is a text message; thus then, at Step S 94 , incoming-call alert vibration is started with a pattern that indicates a text message, and the flow ends. 
     If, at Step S 86 , no unopened text message is detected, the flow proceeds to Step S 96 . Even if, in Step S 84 , an incoming call is detected or, at Step S 86 , an unopened text message is detected, if, at Step S 88 , it is detected being from a response-suspendible caller, the flow proceeds to Step S 96 . In this way, it is possible to avoid the wristband-type handset  504  vibrating unnecessarily for a person who is not involved in an urgent matter. 
     At Step S 96 , it is checked whether or not the battery is low on the mobile telephone  2  proper or on the wristband-type handset  504 . If either is the case, then, at Step S 98 , whether or not the battery of the mobile telephone  2  proper is low is checked. If the battery of the mobile telephone  2  proper is low, then, at Step S 100 , low battery alert vibration is started with a pattern indicating that the battery of the mobile telephone  2  proper is low, and the flow ends. On the other hand, if, at Step S 98 , the battery of the mobile telephone  2  proper is not detected being low, it means that the battery of the wristband-type handset  504  is low; thus then, at Step S 102 , low battery alert vibration is started with a pattern indicating that the battery of the wristband-type handset  504  is low, and the flow ends. 
     If, at Step S 96 , no low battery is detected, it means that the flow in  FIG. 17  has started so as to correspond to Step S 56  in  FIG. 16 . Accordingly, in this case, the flow proceeds to Step S 104 , where out-of-service-area alert vibration is started with a pattern indicating that the mobile telephone  2  proper is outside the telephone service area, and then flow ends. In either case, on completion of the flow in  FIG. 17 , the flow in  FIG. 16  is resumed from Step S 60 . The alert vibration starting process described above permits the user to recognize the cause that has started vibration. 
       FIG. 18  is a flow chart showing the details of the audio driving starting process at Step S 64  in  FIG. 16 . When the audio driving starting process starts, at Step S 112 , it is checked whether or not vibration has already been started. If vibration has already been started, the flow immediately ends, and the flow in  FIG. 16  is resumed from Step S 66 . If no vibration has yet been started, then, at Step S 114 , it is checked whether or not the flow in  FIG. 18  has started in response to an incoming call. If not, then, at Step S 116 , it is checked whether or not the flow in  FIG. 18  has started on detection of an unopened text message. If the check at either Step S 114  or Step S 116  results YES, the flow proceeds to Step S 118 . 
     At Step S 118 , it is checked whether or not the other side is classified as a “response-suspendible caller”. If not, the flow proceeds to Step S 120 . At Step S 120 , the ID of the other side notified from the mobile telephone  2  is checked against the telephone directly data stored in the storage  99 . Then, at Step S 122 , it is checked whether or not there is any telephone directory data in the storage  99  which corresponds to the other side. If there is no such telephone directory data, then, at Step S 124 , an announcement indicating that the person who has originated a voice call or a text message is unidentified is set, and the flow proceeds to Step S 126 . An unidentified caller can be a troublesome one, but can also be one that will turn out to be important in the future or one that is in fact important but has somehow been left out of the telephone directory data, and thus the announcement is made after Step S 126 . Out of similar consideration, in  FIG. 17 , a caller that is not in the telephone directory data cannot be classified as a response-suspendible caller, and thus the flow proceeds to alerting by vibration. If, at Step S 122 , there is telephone directory data in the storage  99  which corresponds to the caller, the flow proceeds directly to Step S 126 . 
     At Step S 126 , it is checked whether or not the incoming call is a voice call. If it is a voice call, then, at Step S 128 , a call originator announcement, such as saying “a phone call from Mr. Yamada” is started, and the flow ends. Here, if an unidentified caller announcement has been set at Step S 124 , an announcement like “a phone call from an unregistered caller” is made. Of such audio data, the part “a phone call from” is selected when the incoming call is a voice call, the part “Mr. Yamada”, for instance, is selected according to the ID from the mobile telephone  2 , and the part “an unregistered caller” is selected depending on the setting at Step S 124 . 
     On the other hand, if, at Step S 126 , the incoming call is not detected being a voice call, it means that the incoming call is a text message; thus then, at Step S 130 , a message sender announcement, such as saying “a text message from Mr. Suzuki” is started, and the flow ends. Here, if an unidentified caller announcement has been set at Step S 124 , an announcement like “a text message from an unregistered caller” is made. Of such audio data, the part “a text message from” is selected when the incoming call is a text message, the part “Mr. Suzuki”, for instance, is selected according to the ID from the mobile telephone  2 , and the part “an unregistered caller” is selected depending on the setting at Step S 124 . 
     If, at Step S 116 , no unopened text message is detected, the flow proceeds to Step S 132 . Even if, at Step S 114 , an incoming call is detected or, at Step S 115 , an unopened text message is detected, if, at Step S 118 , it is detected being from a response-suspendible caller, the flow proceeds to Step S 132 . 
     At Step S 132 , it is checked whether or not the flow in  FIG. 18  has started as a result of low battery on mobile telephone  2  proper or on the wristband-type handset  504 . If either is the case, then, at Step S 134 , it is checked whether or not the battery of the mobile telephone  2  proper is low. If the battery of the mobile telephone  2  proper is low, then, at Step S 136 , a telephone charge announcement, such as saying “charge the telephone”, is started, and the flow ends. On the other hand, if, at Step S 134 , the battery of the mobile telephone  2  is not detected being low, it means that the battery of the wristband-type handset  504  is low; thus then, at Step S 138 , a wristband charge announcement, such as saying “charge the wristband”, is started, and the flow ends. 
     If, at Step S 132 , no low battery is detected, it means that the flow in  FIG. 18  has started so as to correspond to Step S 56  in  FIG. 16 . Accordingly, in this case, the flow proceeds to S 140 , where an out-of-service-area announcement, such as saying “you have moved out of the telephone service area”, is started, and the flow ends. In any case, when the flow in  FIG. 18  ends, the flow in  FIG. 16  is resumed from Step S 66 . In the audio driving starting process described above, by putting a hand or a finger on the ear cartilage on sensing incoming-call vibration, the user, even if he or she does not remember what causes are signified by which vibration patterns, can reliably recognize the cause of vibration from the announcement. 
     The various features of the embodiments described above can be implemented not only in those specific embodiments but also in any other embodiment so long as they provide their advantages. Moreover, the various features of the embodiments can be implemented with various modifications. Modified features can be implemented in appropriate combinations with each other and with unmodified features. 
     For example, Step S 60  in  FIG. 16 , which is provided in Embodiment 6 to achieve switching to announcements, may be replaced with a step for checking whether or not a switch has been operated manually, instead of detecting an upward acceleration for automatic switching, or the flow may be configured such that the switching can be performed both automatically, on detecting an upward acceleration, and manually. The various features of Embodiment 6 can be implemented not only in a simple wristband having no watch functions but also in a wrist watch as in Embodiments 1 to 5 shown in  FIGS. 1 to 13 . 
     Moreover, in Embodiment 6, the alert vibration starting process may be simplified such that a single vibration pattern is used for all causes, or different vibration patterns are used only to distinguish whether the cause is an incoming call or anything else, with the cause of vibration announced in the audio driving starting process. Moreover, in Embodiment 6, a configuration is also possible where, when a manual vibration stopping operation is made on the operation panel  500  at Step S 66  in  FIG. 16 , it is transmitted to the mobile telephone  2  so that, without the incoming call being responded to, communication is disconnected. In Embodiment 6, the vibration sources  536 ,  538 ,  540 , and  542  are all shared for both incoming-call vibration driving and audio signal driving; instead, an ordinary eccentric-mass motor or the like may be adopted for dedicated use as an incoming-call vibration source, and a piezoelectric bimorph element may be adopted for dedicated use for audio signal driving, in which case a configuration is possible where, at Step S 58  in  FIG. 16 , the eccentric-mass motor starts to be driven and, at Step S 64  in  FIG. 16 , the eccentric-mass motor stops being driven and instead the piezoelectric bimorph element starts to be driven. Although Embodiment 6 is implemented as a wristband, its features may be implemented in a finger ring instead. 
     Overview 
     To follow is an overview of the features of various embodiments disclosed herein. 
     According to one embodiment disclosed herein, a wrist watch-type handset includes: a worn part worn on a wrist; a cartilage conduction vibration source provided in the worn part; a speaker; a variable-directivity microphone; and a controller for switching the directivity of the variable-directivity microphone according to which of the cartilage conduction vibration source and the speaker is used. Thus, the user can comfortably conduct both a call by cartilage-conducted sound and a call by air-conducted sound. According to a specific feature, the controller directs the directivity of the variable-directivity microphone toward the back of a hand when the speaker is used, and directs the directivity of the variable-directivity microphone toward the palm of the hand when the cartilage conduction vibration source is used. 
     According to another embodiment disclosed herein, a wrist watch-type handset includes: a worn part worn on a wrist; a cartilage conduction vibration source provided in the worn part; and a presenting means for presenting information explaining a method of use involving putting the hand on which the worn part is worn in contact with an ear cartilage. Thus, the user can enjoy the benefits of cartilage conduction without confusion. According to a specific feature, the presenting means is a means for displaying information on a speech-transmitting and -receiving method. According to another specific feature, the presenting means is an instruction manual medium containing information on a speech-transmitting and -receiving method. According to yet another specific feature, the presenting means is an advertisement medium containing information on a speech-transmitting and -receiving method. 
     According to another feature of one embodiment disclosed herein, a wrist watch-type handset includes: a worn part worn on a wrist; a cartilage conduction vibration source provided in the worn part; and a conducting part for conducting vibration of the cartilage conduction vibration source to around the wrist. Thus, suitable vibration can be conducted to the wrist irrespective of differences among individual users and displacements of the handset worn. 
     According to another feature of one embodiment disclosed herein, a wrist watch-type handset includes: a worn part worn on a wrist; and a cartilage conduction vibration source provided in the worn part. The cartilage conduction vibration source is used also as a vibration source for an incoming-call vibrator, and when it is vibrated for cartilage conduction, the vibration component in a low frequency range arousing the sense of vibration is cut off. Thus, cartilage conduction can be achieved without causing an uncomfortable sense of vibration. 
     According to a specific feature, when the cartilage conduction vibration source is vibrated for the incoming-call vibrator, the vibration component in an audible frequency range is cut off. Thus, the user can sense an incoming call without someone around noticing it. 
     According to another specific feature, a limiter is provided for inhibiting vibration exceeding the intensity low enough not to arouse the sense of vibration when the cartilage conduction vibration source is vibrated for cartilage conduction. Thus, cartilage conduction can be achieved without causing an uncomfortable sense of vibration. 
     According to another feature of one embodiment disclosed herein, a wrist watch-type handset includes: a worn part worn on a wrist; a cartilage conduction vibration source provided in the worn part; a microphone; and a buffer segment for preventing conduction of vibration between the cartilage conduction vibration source and the variable-directivity microphone. Thus, satisfactory cartilage conduction can be achieved without the microphone collecting vibration. 
     According to one embodiment disclosed herein, a method for receiving speech includes: holding a cartilage conduction member between the ball of a thumb and a tragus with the back of a hand pointing frontward to conduct vibration of the cartilage conduction member to the tragus so that sound is heard by cartilage conduction. Thus, the user can receive speech by cartilage conduction in a natural posture similar to that in telephone conversation with a gesture. 
     According to a specific method, the worn part worn on the wrist is used to support the cartilage conduction member on the worn part. Thus, the user can receive speech by cartilage conduction in a wearable fashion. According to a more specific method, a support part for supporting the cartilage conduction member with a fulcrum at the worn part is held between the base of the thumb and the forefinger. Thus, natural, stable cartilage conduction can be achieved. 
     According to another specific method, the cartilage conduction member, when not in contact with the tragus, is laid along the worn part. Thus, the user can be ready for cartilage conduction in a wearable fashion without feeling awkward when not using it. According to a more specific method, the cartilage conduction member folded up into the worn part is used as a vibration source for an incoming-call vibrator. Thus, the cartilage conduction member can be used effectively even when not used as such. 
     According to another method based on one embodiment disclosed herein, vibration is conducted to a thumb, and, with the back of a hand pointing frontward, the thumb is put in contact with a tragus to conduct the vibration to the tragus so that sound is heard by cartilage conduction. According to a specific method, the vibration is conducted to the thumb by conducting vibration to the wrist from a cartilage conduction vibration source provided in a worn part worn on the wrist. According to another specific method, the vibration is conducted to the thumb by putting in contact with the thumb a cartilage conduction member supported on a worn part. Also with these methods, the user can receive speech by cartilage conduction in a natural posture similar to that in telephone conversation with a gesture. According to a more specific method based on the latter method, the vibration is conducted to the thumb by putting the cartilage conduction member in contact with the base of the thumb. According to a further specific method, the cartilage conduction member is held between the base of the thumb and the forefinger. Thus, natural, stable cartilage conduction can be achieved. 
     According to another feature of one embodiment disclosed herein, a handset includes: a worn part worn on a wrist; a support part raisable along an inner side of a thumb with a fulcrum at the worn part; and a cartilage conduction member supported on the support part. Thus, the user can receive speech by cartilage conduction in a wearable fashion. According to a specific feature, the support part is movable between a raised position where it rises along the inner side of the thumb and a retracted position where it lies along the worn part. Thus, the user can be ready for cartilage conduction in a wearable fashion without feeling awkward when not using it. According to a more specific feature, the support part is foldable in the retracted position. According to a more detailed feature, the support part is formed of a shape memory material. According to another more specific feature, the support part is so structured as to be wound around the outer circumference of the worn part. According to a more detailed feature, the support part is slidable relative to the worn part between the raised position and the retracted position. 
     According to another specific feature of one embodiment disclosed herein, the support part permits the cartilage conduction member to rise onto the ball of the thumb. According to another specific feature, the support part permits the cartilage conduction member to rise onto the base of the thumb 
     According to another specific feature, a handset disclosed herein has a near-field communicator, for communication with a mobile telephone, and a microphone, and is configured as a wrist watch. According to yet another specific feature, a handset disclosed herein has a near-field communicator, for communication with a mobile telephone, and a microphone, and is configured as an attachment for a wrist watch. 
     According to one embodiment disclosed herein, an alerting device wearable on the human body includes: a storage for previously storing a plurality of pieces of alert audio data; a vibration source for vibrating for cartilage conduction; a near-field communicator for receiving an instruction signal from a mobile telephone; and a controller for selecting, according to the instruction signal received by the near-field communicator, a corresponding piece of alert audio data stored in the storage, and for making the vibration source vibrate in a frequency range of an audio signal for cartilage conduction according to the selected piece of alert audio data. Thus, the user can confirm the specific content of a notification by cartilage conduction on the basis of the instruction signal received from the mobile telephone. 
     According to a specific feature, an alerting device disclosed herein is configured as a wristband. More specifically, the wristband is formed of a material having an acoustic impedance similar to that of the wrist. The wristband may instead be formed of an elastic material, Thus, vibration of the vibration source can be conducted to the wrist effectively. 
     According to another specific feature, an alerting device disclosed herein is controlled by the controller so as to produce alert vibration in a frequency range arousing the sense of vibration according to the instruction signal received by the near-field communicator. Thus, the user can confirm the specific content of a notification by cartilage conduction on the basis of the instruction signal received from the mobile telephone, and can also recognize the receipt of the instruction signal by the sense of vibration based on the instruction signal from the mobile telephone. According to a more specific feature, the vibration source for cartilage conduction is used also as a vibration source for the alert vibration. According to another more specific feature, a vibration source for the alert vibration is provided separately from the vibration source for cartilage conduction. 
     According to another more specific feature, an alerting device disclosed herein first produces alert vibration in a frequency range arousing the sense of vibration according to the instruction signal received by the near-field communicator, and then switches to vibration by the vibration source based on the audio data in a frequency range of an audio signal in order to allow the user to confirm the cause of the alert vibration. Specifically, the instruction signal is an incoming-call signal indicating that the mobile telephone has received an incoming call. According to a more specific feature, the instruction signal contains information about the caller the incoming call is from, and the audio data contains an announcement about the caller. According to yet another specific feature, the instruction signal contains information indicating whether the incoming call is a voice call or a text message, and the audio data contains an announcement indicating whether the incoming call is a voice call or a text message. 
     According to another feature of one embodiment disclosed herein, an alerting device includes: a storage; a vibration source; a near-field communicator for receiving an incoming-call signal from a mobile telephone; and a controller for making the vibration source vibrate according to the incoming-call signal received by the near-field communicator. A particular communication partner can be previously stored in the storage so that, if the incoming-call signal contains information about the particular communication partner, even when the incoming-call signal is received from the mobile telephone, the vibration source is not vibrated. Thus, the user can avoid the annoyance of the vibration source vibrating for a partner that does not require an urgent response. 
     According to another feature of one embodiment disclosed herein, an alerting device wearable on the human body includes: a vibration source; a near-field communicator for receiving from a mobile telephone information indicating that the mobile telephone has low battery; and a controller for making the vibration source vibrate according to the information received by the near-field communicator. Thus, the user can recognize that the mobile telephone has low battery on the basis of the instruction signal received from the mobile telephone. According to a specific feature, the controller makes the vibration source vibrate with a particular pattern indicating that the mobile telephone has low battery. 
     According to another feature of one embodiment disclosed herein, an alerting device wearable on the human body includes: a vibration source; a near-field communicator for receiving from a mobile telephone information indicating that the mobile telephone is located outside the telephone service area; and a controller for making the vibration source vibrate according to the information received by the near-field communicator. Thus, the user can recognize that the mobile telephone is located outside the telephone service area on the basis of the instruction signal received from the mobile telephone. According to a specific feature, the controller makes the vibration source vibrate with a particular pattern indicating that the mobile telephone is located outside the telephone service area. 
     INDUSTRIAL APPLICABILITY 
     The present invention finds applications in wrist watch-type and wrist watch attachment-type handsets. The present invention finds applications also in alerting devices that operate in coordination with mobile telephones. 
     LIST OF REFERENCE SIGNS 
     
         
         
           
               28 ,  30 ,  41  worn part 
               36 ,  38 ,  40  cartilage conduction vibration source 
               32  speaker 
               46  variable-directivity microphone 
               98  controller 
               28  belt 
               26  wrist watch body 
               41  conducting part 
               42  adjusting means 
               96  limiter 
               52 ,  54  buffer segment 
               138 ,  238 ,  338  cartilage conduction member 
               128 ,  328 ,  428  worn part worn on a wrist 
               105 ,  205 ,  305  support part 
               36 ,  38 ,  40  cartilage conduction vibration source 
               104 ,  204 ,  304  wrist watch 
               404  attachment for a wrist watch 
               98  storage 
               536 ,  538 ,  540 ,  542  vibration source 
               22  instruction signal 
               77  near-field communicator 
               598  controller 
               528  wristband