BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to human body communications, and particularly to a technology for providing easily understandable notification of a status of a human body communication. 
         [0003]    2. Description of the Related Art 
         [0004]    In recent years, a human body communication system which communicates through a user&#39;s human body has been developed. For example, according to Japanese. Patent Application Laid-Open No. 2004-120097, an operating error such as an inadvertent operation is prevented by providing an electrode of a human body communication integrated with a switch and performing ID matching only when the switch is pressed. Additionally, according to Japanese Patent Application Laid-Open No. 2002-9710, a body-worn human body communication device supplies power to a circuit after receiving of a start signal from its partner&#39;s human body communication device so that energy consumption is reduced when communication is not being performed. 
       SUMMARY OF THE INVENTION 
       [0005]    In the technologies according to the above documents, although communication is enabled when a user touches an electrode, the user cannot know a status of the human body communication after touching the electrode. A separate display device may be provided to give notification of a communication status. However, in this case, a user cannot know communication status without changing the user&#39;s view direction to watch the display device. The present invention is made in view of these problems, and is intended to allow a user&#39;s body to sense a status of human body communication from the neighborhood of a part which the body touches. 
         [0006]    A communication device according to the present invention includes a contact part which contacts a human body, a communication section which performs data communication through the human body in contact with the contact part, an energy generating section which generates energy including at least one of mechanical energy, heat energy, and light energy to apply the energy to the contact part, a status detection section which detects a status of the data communication of the communication section, and a communication status notification section which controls start, continuation, or stop of the energy generation of the energy generating section depending on the status of the data communication detected by the status detection section. 
         [0007]    This allows a user to sense a communication status from energy such as mechanical power, heat, or light applied to a contact part which contacts the user&#39;s body. 
         [0008]    Preferably, the energy generating section includes a vibration generating section which generates vibration force. 
         [0009]    Preferably, the energy generating section includes a heat radiating section which radiates heat to a human body contacting side of the contact part. 
         [0010]    Preferably, the energy generating section includes a heat absorbing section which absorbs heat from a human body contacting side of the contact part. 
         [0011]    Preferably, the energy generating section includes an absorption section which sticks the human body in contact with the contact part to the contact part. 
         [0012]    Preferably, the communication device further includes a projecting part configured to be projectable to a human body contacting side of the contact part and be retractable to a human body non-contacting side of the contact part, wherein the energy generating section includes a drive section which drives operation of projection or retraction of the projecting part. 
         [0013]    Preferably, the energy generating section includes a light emitting section which emits light to a human body contacting side of the contact part. 
         [0014]    Preferably, the communication status notification section controls start or stop of the energy generation of the energy generating section depending on detection of start or end of the data communication by the status detection section. 
         [0015]    Preferably, the communication status notification section controls the energy generation to be continued since the status detection section detects the start of the data communication until the status detection section detects the end of the data communication. 
         [0016]    Preferably, the communication status notification section changes a pattern of the energy generation of the energy generating section depending on the status of the data communication detected by the status detection section. 
         [0017]    This allows a user to sense a communication status from a pattern of energy generation from the contact part. 
         [0018]    A communication device according to the present invention includes a contact part which contacts a human body, a communication section which performs data communication through the human body in contact with the contact part, a light emitting section which irradiates light to a neighborhood of a human body contacting side of the contact part, a status detection section which detects a status of the data communication of the communication section, and a communication status notification section which controls start, continuation, or stop of light emission of the light emitting section depending on the status of the data communication detected by the status detection section. 
         [0019]    This allows a user to sense a communication status from light of the neighborhood of the contact part. 
         [0020]    A communication status notification method according to the present invention is a communication status notification method used in a communication device including a contact part which contacts a human body and a communication section which performs data communication through the human body in contact with the contact part, the method including the steps of detecting a status of the data communication of the communication section, and generating energy including at least one of mechanical energy, heat energy, and light energy to apply the energy to the contact part depending on the detected status of the data communication. 
         [0021]    A communication status notification method according to the present invention is a communication status notification method used in a communication device including a contact part which contacts a human body and a communication section which performs data communication through the human body in contact with the contact part, the method including the steps of detecting a status of the data communication of the communication section, and irradiating light to a neighborhood of a human body contacting side of the contact part depending on the detected status of the data communication. 
       ADVANTAGE OF THE INVENTION 
       [0022]    According to the present invention, a user can easily sense a communication status from energy such as mechanical power, heat, or light applied to a contact part which contacts the user&#39;s body or from light irradiated to a neighborhood of the contact part. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  is a block diagram of a communication system; 
           [0024]      FIG. 2  is a human body communication section according to a first embodiment; 
           [0025]      FIG. 3  is a flowchart which shows a flow of communication processing according to the first embodiment; 
           [0026]      FIG. 4  is a flowchart which shows a flow of communication processing according to a second embodiment; 
           [0027]      FIG. 5  is a block diagram of a human body communication section according to a third embodiment; 
           [0028]      FIG. 6  is a flowchart which shows a flow of communication processing according to the third embodiment; 
           [0029]      FIG. 7  is a block diagram of a human body communication section according to a forth embodiment; 
           [0030]      FIG. 8  is a block diagram of a human body communication section (in which a protrusion is not formed) according to a fifth embodiment; 
           [0031]      FIG. 9  is a block diagram of the human body communication section (in which a protrusion is formed) according to the fifth embodiment; and 
           [0032]      FIG. 10  is a block diagram of a human body communication section according to a sixth embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
       [0033]      FIG. 1  shows one example of a configuration of a communication system  100  according to a preferred embodiment of the present invention. The communication system  100  includes a first communication device  101 - 1  and a second communication device  101 - 2 . The first communication device  101 - 1  or the second communication device  101 - 2  may be, for example, a mobile telephone, a PDA, a wristwatch, an automobile or an intelligent key thereof, a notebook computer, a television, an electronic photo stand, or the like, and may be configured in any specific manner and used in any form. For example, it may be configured to be attachable to a human body. 
         [0034]    The first communication device  101 - 1  and the second communication device  101 - 2  have respective human communication sections  102  which send/receive data each other through a user&#39;s human body  2 . 
         [0035]    For example, while the user touches the human communication section  102  of the first communication device  101 - 1  with one of the user&#39;s hands, the user touches the human communication section  102  of the second communication device  101 - 2  with the other of the user&#39;s hands. Then, the first communication device  101 - 1  and the second communication device  101 - 2  are electrically connected through the user&#39;s human body  2  and communicate necessary data each other. 
         [0036]      FIG. 2  is a block diagram of the human body communication section  102  according to the first embodiment. The human body communication section  102  has a human body contact part  11   a  which contacts the human body  2 , a transceiver  12 , a vibration generator  13 , a control section  14 , a storage section  15 , and a touch sensor  16 . 
         [0037]    The human body contact part  11   a  is an electrode composed of, for example, an electrically conductive member. The human body contact part  11   a  may also be hereinafter referred to as an electrode  11   a.  The transceiver  12  modulates a digital signal which indicates various information to several tens to several hundreds kHz as a weak current of several hundred microamperes and transmits the modulated signal to the human body communication section  102  of the other party through the human body  2  in contact with the electrode  11   a.  Alternatively, the transceiver  12  receives a weak current from the human body communication section  102  of the other party and demodulates it into a digital signal. This allows data communication at several ten kbps between the human body communication sections  102 , and therefore, for example, 128-bit information can be transmitted in several ten milliseconds. Preferably, information is transmitted several times or several ten times redundantly because a communication status of the transceiver  12  depends on a contact condition between the human body  2  and the electrode  11   a.    
         [0038]    The vibration generator  13  is a small device composed of a piezoelectric element, a-motor, or the like which generates vibration force. The vibration generator  13  is configured to transmit vibration force generated by the vibration generator  13  only to the electrode  11   a  by, for example, contacting a vibrating plate stuck to an electrode of a piezoelectric element with the electrode  11   a.    
         [0039]    The control section  14  is composed of a CPU and the like, and centrally controls operation of each part. Such operations include start and end of sending/receiving of information by the transceiver  12 , start and end of vibration of the electrode  11   a  by the vibration generator  13 , and the like. The storage section  15  is composed of a flash memory, a RAM, or the like, and temporarily or continuously stores various data and programs required for processing by the control section  14 . 
         [0040]    The touch sensor  16  is, for example, a capacitance type sensor formed on the electrode  11   a.  When the touch sensor  16  detects, from change of capacitance or the like, that the human body  2  contacts the electrode  11   a  or that contact of the human body  2  is released, the touch sensor  16  outputs a contact sense signal or a contact release sense signal to the control section  14 . 
         [0041]    The transceiver  12  notifies the control section  14  of start/end of data sending from the transceiver  12  itself, start/end of data receiving from the other party, occurrence of an error during data sending and receiving, or other communication statuses. The control section  14  detects a communication status of the transceiver  12  by the communication status notification from the transceiver  12 . 
         [0042]      FIG. 3  is a flowchart which shows a flow of communication processing performed by the human body communication section  102 . 
         [0043]    In S 1 , the control section  14  continuously determines whether or not a contact sense signal is outputted from the touch sensor  16 . When the control section  14  determines that the sense signal is outputted, the processing proceeds to S 2 . 
         [0044]    In S 2 , the control section  14  controls the transceiver  12  to start sending/receiving of desired data. In addition, the control section  14  controls the vibration generator  13  to start generation of vibration force by controlling a driver or the like (not shown) connected to the vibration generator  13 . Control of the start of data sending/receiving of the transceiver  12  may be started immediately when it is determined that a contact sense signal is outputted from the touch sensor  16 , or may be synchronized with control of the start of generation of vibration force. The vibration generator  13  continues the generation of vibration force until the vibration generator  13  is controlled to stop the generation of vibration force by the control section  14 . 
         [0045]    In S 3 , the control section  14  determines whether communication of the desired data by the transceiver  12  is terminated or not. This can be determined by, for example, whether or not the self transceiver  12  sends the desired data and receives a signal from the human body communication section  102  of the other party which indicates it received the desired data. When the control section  14  determines that the communication of the data is terminated, the processing proceeds to S 4 . 
         [0046]    Alternatively, it may be determined that the communication of the data is terminated when it is determined that a contact release sense signal is outputted from the touch sensor  16  or when it is determined that a communication error of the transceiver  12  occurs. 
         [0047]    In S 4 , the control section  14  controls the transceiver  12  to disconnect its communication and controls the vibration generator  13  to stop the generation of vibration force. 
         [0048]    According to the above described processing, since a user can sense that communication is being performed from vibration force transmitted from the electrode  11   a  when the user contacts the user&#39;s human body  2  with the electrode  11   a,  the user can intuitively know start, continuation and end of the communication between the first communication device  101 - 1  and the second communication device  101 - 2  through the human body  2 . 
       Second Embodiment 
       [0049]    Although, in the first embodiment, generation of vibration force is continued as long as communication is continued, vibration force may be generated only when communication is started and/or terminated. 
         [0050]      FIG. 4  is a flowchart which shows a flow of communication processing performed by the human body communication section  102 . 
         [0051]    In S 11 , the control section  14  continuously determines whether or not a contact sense signal is outputted from the touch sensor  16 . When the control section  14  determines that the sense signal is outputted, the processing proceeds to S 12 . 
         [0052]    In S 12 , the control section  14  controls the transceiver  12  to start sending/receiving of desired data. 
         [0053]    In S 13 , the control section  14  selects vibration pattern data corresponding to “communication start” that is a latest communication status detected by the transceiver  12  from among vibration pattern data stored in the storage section  15 . Then, the control section  14  controls vibration generator  13  to vibrate with a pattern based on the selected vibration pattern data only within a predetermined time. Thus, the control section  14  clocks a duration time of generation of vibration force. When the control section  14  determines that the duration time arrives at the predetermined time (for example, 2 seconds), the control section  14  controls the vibration generator  13  to stop the generation of vibration force. 
         [0054]    In addition, if the vibration pattern data corresponding to the “communication start” defines a vibration that continues for only a few tenths of a second, an effect similar to a click feeling can be provided to the human body  2 . 
         [0055]    In S  14 , the control section  14  determines whether communication of the desired data by the transceiver  12  is terminated or not. When the control section  14  determines that the communication of the data is terminated, the processing proceeds to S 15 . 
         [0056]    In S 15 , the control section  14  controls the transceiver  12  to disconnect its communication. 
         [0057]    In S 16 , the control section  14  selects vibration pattern data corresponding to “communication end” that is a latest communication status detected by the transceiver  12  from among vibration pattern data stored in the storage section  15 . Then, the control section  14  controls vibration generator  13  to vibrate with a pattern based on the selected vibration pattern data only within a predetermined time. The control section  14  clocks a duration time of generation of vibration force. When the control section  14  determines that the duration time arrives at the predetermined time (for example, 2 seconds), the control section  14  controls the vibration generator  13  to stop the generation of vibration force. Preferably, a vibration pattern corresponding to the “communication start” is different from a vibration pattern corresponding to the “communication end”. For example, both vibration patterns may have a difference in strength, rhythm, rate, duration, or the like of a vibration. 
         [0058]    In addition, when it is determined that a communication error of the transceiver  12  occurs, vibration pattern data corresponding to “error end” that is a current status of the transceiver  12  is selected, and vibration generator  13  is controlled to vibrate with a pattern based on the selected vibration pattern data within a predetermined time. If the ;vibration pattern data corresponding to the “error end” has a stronger vibration force pattern than a vibration patterns corresponding to the “communication start” and the “communication end”, the human body  2  can sense that communication is terminated due to an error. 
         [0059]    According to the above described processing, when the user contacts the user&#39;s human body  2  with the electrode  11   a,  the user can intuitively know communication statuses such as start, continuation and end by a vibration pattern transmitted from the electrode  11   a.    
       Third Embodiment 
       [0060]      FIG. 5  is a block diagram of the main part of a human communication section  102  according to the third embodiment. The human communication section  102  includes a heating device  17  composed of a peltier element, a heating wire, or the like instead of the vibration generator  13 . Other components are similar to those of  FIG. 2 , and illustrations and descriptions thereof are omitted. 
         [0061]    The electrode  11   a  is composed of an electrically conductive and heat conductive member. Heat generated by the heating device  17  is conducted to the human body  2  in contact with the electrode  11   a.  Although the heating device  17  and the electrode  11   a  are separately provided in  FIG. 5 , if the heating device  17  is composed of an electrically conductive member such as a heating wire, the heating device  17  and the electrode  11   a  can be integrated in a common structure. 
         [0062]      FIG. 6  is a flowchart which shows a flow of communication processing performed by the human body communication section  102 . 
         [0063]    In S 21 , the control section  14  continuously determines whether or not a contact sense signal is outputted from the touch sensor  16 . When the control section  14  determines that the sense signal is outputted, the processing proceeds to S 22 . 
         [0064]    In S 22 , the control section  14  controls the transceiver  12  to start sending/receiving of desired data. In addition, the control section  14  controls the heating device  17  to start generation of heat by controlling a driver or the like (not shown) connected to the heating device  17 . Control of the start of data sending/receiving of the transceiver  12  may be started immediately when it is determined that a contact sense signal is outputted from the touch sensor  16 , or may be synchronized with control of the start of heat generation. The heating device  13  continues the heat generation until the heating device  13  is controlled to stop the heat generation by the control section  14 . 
         [0065]    In S 23 , the control section  14  determines whether communication of the desired data by the transceiver  12  is terminated or not. When the control section  14  determines that the communication of the data is terminated, the processing proceeds to S 24 . 
         [0066]    Alternatively, it may be determined that the communication of the data is terminated when it is determined that a contact release sense signal is outputted from the touch sensor  16  or when it is determined that a communication error of the transceiver  12  occurs. 
         [0067]    In S 24 , the control section  14  controls the transceiver  12  to disconnect its communication and controls the heating device  17  to stop the heat generation. In addition, if the heating device  17  is composed of a peltier element, the control section  14  may control the heating device  17  to stop the heat generation and further start heat absorption or cooling. 
         [0068]    According to the above described processing, since a user can sense that communication is being performed from heat conducted from the electrode  11   a  when the user contacts the user&#39;s human body  2  with the electrode  11   a,  the user can intuitively know start, continuation and end of the communication between the first communication device  101 - 1  and the second communication device  101 - 2  through the human body  2 . 
         [0069]    Particularly, if heat generation is started at the start of communication and heat absorption is started at the end of communication, termination of the communication can be clearly recognized. 
       Fourth Embodiment 
       [0070]      FIG. 7  is a block diagram of the main part of a human communication section  102  according to the fourth embodiment. The human body communication section  102  includes an electrode  11   a  which is an electronically conductive member that is fairly bent and formed in a concave shape, and a pressure reducing device  11   b  which reduces pressure by absorbing air from the concave space of the electrode  11   a.  Other components are similar to those of  FIG. 2 , and illustrations and descriptions thereof are omitted. 
         [0071]    When the human body  2 , e.g., a finger is pushed into the concave portion of the electrode  11   a,  the concave portion is closely contacted with the human body  2  so that a space S which is almost cut off from the outside world is formed. The pressure reducing device  11   b  absorbs air of the space S so that the space S is in an almost vacuum state and therefore the concave portion is more closely contacted with the human body  2 . 
         [0072]    When a touch sense signal is outputted from the touch sensor  16 , the control section  14  controls the pressure reducing device  11   b  to absorb air of the space S, and also controls the transceiver  12  to start sending/receiving of desired data. The user can sense that communication is stared in response to the human body  2  being pulled. 
         [0073]    In addition, when the control section  14  determines that the communication of the data is terminated, the control section  14  controls the pressure reducing device  11   b  to flow air into the space S so as to release the contact between the electrode  11   a  and the human body  2 . The user can sense that the communication is terminated in response to detaching of the human body  2  from the electrode  11   a.    
       Fifth Embodiment 
       [0074]      FIG. 8  is a block diagram of the main part of a human communication section  102  according to the fifth embodiment. The human communication section  102  includes a flat-plate electrode  11   a  through which a hole  11   a -H is formed in a central or another portion thereof, a projecting part  11   c  which is a convex-shaped member arranged to be projectable to a human body  2  contacting side of the electrode  11   a  through the hole  11   a -H, and an operation device  11   d  which performs operations of projection and retraction of the projecting part  11   c.  Other components are similar to those of  FIG. 2 , and illustrations and descriptions thereof are omitted. 
         [0075]    The operation device is composed of a mechanical power generating device such as a motor or piezo element. 
         [0076]    The projecting part  11   c  projects from the hole  11   a -H so as to form a protrusion R on the human body  2  contacting side of the flat-plate electrode  11   a,  and therefore contacts the human body  2  ( FIG. 9 ). When the projecting part  11   c  is retracted through the hole  11   a -H, the protrusion R on the electrode  11   a  is disappeared, and the electrode  11   b  forms its original flat-plate shape ( FIG. 8 ). 
         [0077]    When a contact sense signal is outputted from the touch sensor  16 , the control section  14  controls the operation device  11   d  to project the projecting part  11   c  from the hole  11   a -H, and also controls the transceiver  12  to start sending/receiving of desired data. The user can sense that communication is started in response to the human body  2  in contact with the protrusion R. 
         [0078]    Additionally, as in the first embodiment, the operation device  11   d  may generate vibration force to transmit it to the projecting part  11   c  after the projecting part  11   c  is projected. The user can easily sense that communication is being performed since vibration is transmitted from the protrusion R to the human body  2  in contact therewith. 
         [0079]    In addition, when the control section  14  determines that the data communication is terminated, the control section  14  controls the operation device  11   d  to retract the projecting part  11   c  through the hole  11   a -H. The user can sense that the communication is terminated in response to the human body  2  away from the protrusion R. After the projecting part  11   c  is retracted, vibration force generation of the operation part  11   d  is stopped. 
       Sixth Embodiment 
       [0080]      FIG. 10  is a block diagram of the main part of a human communication section  102  according to the sixth embodiment. The human body communication section  102  includes an electrode  11   a,  and a light emitting device  11   e  which cause a light emitting section  11 L to emit light. The light emitting section  11 L is composed of an LED, a fluorescent tube, an organic EL element, or the like. Other components are similar to those of  FIG. 2 , and illustrations and descriptions thereof are omitted. 
         [0081]    The electrode  11   a  is composed of an electrically conductive member through which light is transmitted from the light emitting section  11 L. The member may be a transparent electrode film or ITO film commonly used for a touch panel and the like, or a conductor embedded in a film in a mesh or lattice pattern. The electrode  11   a  and the touch sensor  16  may be integrated in a common member. 
         [0082]    The light emitting section  11 L and the light emitting device  11   e  are provided on the side which the human body  2  does not contact, and light is transmitted through the electrode  11   a  from the human body  2  non-contacting side to the human body  2  contacting side. However, if the light emitting section  11 L is able to irradiate light to a neighborhood of a portion which the human body  2  contacts, the light emitting section  11 L may be provided on the human body  2  contacting side. 
         [0083]    When a touch sense signal is outputted from the touch sensor  16 , the control section  14  controls the light emitting device  11   e  to cause the light emitting section  11 L to emit light, and also controls the transceiver  12  to start sending/receiving of desired data. Since the user looks at the electrode  11   a  when contacting the human body  2  with the electrode  11   a,  the user can sense that communication is started from light emission from the light emitting section  11 L without especially changing the user&#39;s view direction. 
         [0084]    In addition, when the control section  14  determines that the communication of the data is terminated, the control section  14  controls the light emitting device  11   e  to stop light emission of the light emitting section  11 L. The user can sense that the communication is terminated from the stop of light emission from the light emission  11 L without changing the user&#39;s view direction. 
       Seventh Embodiment 
       [0085]    The human body communication section  102  may be composed of a combination of at least two of the above described components, that is, the electrode  11   a,  the pressure reducing device  11   b,  the projecting part  11   c,  the operation device  11   d,  the light emitting section  11 L and light emitting device  11   e,  the vibration generator  13 , and the heating device  17 . In this case, a common structure of the combination of blocks may be integrated. For example, the operation section  11   d  and the vibration generator  13  may be composed of the same piezo element. 
         [0086]    Alternatively, the light emitting section  11 L and the heating device  17  may be composed of a halogen lamp, which has a wide radiation spectrum from visible light to mid- and far-infrared rays and is used as a heat source as well as lighting, and therefore the light emitting section  11 L and the heating device  17  may be integrated so that the number of parts is reduced.
The communication device according to an aspect of the present invention comprises a contact part which contacts a human body, a communication section which performs data communication through the human:body in contact with the contact part, an energy generating section which generates energy including at least one of mechanical energy, heat energy, and light energy to apply the energy to the contact part, a status detection section which detects a status of the data communication of the communication section, and a communication status notification section which controls start, continuation, or stop of the energy generation of the energy generating section depending on the status of the data communication detected by the status detection section.