Abstract:
A portable electronic device includes a housing, a drop detection part located on the housing that detects when the device is dropped into water, a light emission part located within the housing, and a light-emission control circuit located within the housing that controls emission of light from the light emission part when the drop detection part detects that the device is dropped into the water. The device is configured to have a buoyancy, and the buoyancy and a center of gravity of the device are configured to let the device float stably in a left-right lateral direction.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present application is a continuation application of U.S. patent application Ser. No. 12/896,215 filed on Oct. 1, 2010, entitled “PORTABLE ELECTRONIC DEVICE,” which is related to, claims priority from and incorporates by reference Japanese Patent Application No. 2010-183656, filed on Aug. 19, 2010. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a portable electronic device and particularly to a portable electronic device that can float on water even if it is dropped into the water. 
       BACKGROUND 
       [0003]    There are many portable electronic devices used close to water such as marine transceivers and the like. Since this type of electronic devices can be accidentally splashed with water or dropped into the water, water-proof devices so that water cannot enter the insides have been put into practice. Also, if the device sinks in the water when being dropped into the water, it cannot be recovered. A floating-type device to stay afloat when being dropped into the water is also proposed, as disclosed by Japanese Laid-Open Patent Application Publication No. H04-135038. 
         [0004]    However, at night or when visibility is poor, even if an electronic device floats on the water surface, it is likely that the device cannot be found. In such case, there has been a problem that the electronic device cannot be recovered even though it is floating on the water. 
         [0005]    The present invention has an object to provide a portable electronic device that can be easily found on the water surface even at night or if visibility is poor. 
       SUMMARY 
       [0006]    A portable electronic device of the present invention includes a housing, a drop detection part located on the housing that detects when the device is dropped into water, a light emission part located within the housing, and a light-emission control circuit located within the housing that controls emission of light from the light emission part when the drop detection part detects that the device is dropped into the water. The device is configured to have a buoyancy, and the buoyancy and a center of gravity of the device are configured to let the device float stably in a left-right lateral direction. 
         [0007]    In a preferred embodiment of the present invention, the light emission part is disposed on the side to be turned up by buoyancy when the device is dropped into the water, and the drop detection part is disposed on the side to be turned down when the device is dropped into the water. 
         [0008]    In a preferred embodiment of the present invention, the electronic device has the buoyancy by which at least the light emission part comes up to the water surface when the device is dropped into the water. 
         [0009]    In a preferred embodiment of the present invention, an antenna is disposed on a front side of the top face, and a speaker is disposed on the front face, the drop detection part is disposed inside a speaker grill that covers the front of the speaker, and the light emission part is disposed on the bottom face. 
         [0010]    In a preferred embodiment of the present invention, the light-emission control circuit includes a delay circuit that keeps the light emission part emitting light for a predetermined time after the drop detection part does not detect drop into the water any longer. 
         [0011]    In a preferred embodiment of the present invention, the electronic device has a housing including a front housing, a rear housing and a gasket fitted to a joined part of the front housing and the rear housing, furthermore. And the light emission part includes a translucent section formed at a part of the gasket and a light emitting semiconductor element disposed inside the housing. 
         [0012]    According to this invention, since the light emission part emits light when the portable electronic device is dropped into the water, even at night or if visibility is poor, a user can easily find the portable electronic device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1A  is a appearance view of a transceiver, which is an embodiment of the present invention. 
           [0014]      FIG. 1B  is a appearance view of the transceiver. 
           [0015]      FIG. 1C  is a appearance view of the transceiver. 
           [0016]      FIG. 2A  is a structural diagram of the vicinity of a speaker grill of the transceiver. 
           [0017]      FIG. 2B  is a structural diagram of the vicinity of a speaker grill of the transceiver. 
           [0018]      FIG. 3A  is a structural diagram of the vicinity of the speaker grill of the transceiver. 
           [0019]      FIG. 3B  is a structural diagram of the vicinity of the speaker grill of the transceiver. 
           [0020]      FIG. 4  is an internal structural diagram of a lower part of the transceiver. 
           [0021]      FIG. 5  is a circuit diagram of an LED lighting control circuit of the transceiver. 
           [0022]      FIG. 6  is a diagram illustrating an attitude when the transceiver is dropped into the water. 
           [0023]      FIG. 7A  is a diagram illustrating another embodiment of the vicinity of the speaker grill of the transceiver. 
           [0024]      FIG. 7B  is a diagram illustrating another embodiment of the vicinity of the speaker grill of the transceiver. 
       
    
    
     EXPLANATION OF REFERENCE NUMERALS 
       [0025]    “ 1 ” transceiver 
         [0026]    “ 11 ” housing 
         [0027]    “ 11 A” front housing 
         [0028]    “ 12 ” antenna 
         [0029]    “ 13 ” gasket 
         [0030]    “ 13 A” translucent section 
         [0031]    “ 16 ” speaker grill 
         [0032]    “ 21 A” projection (of housing) 
         [0033]    “ 30 ” speaker 
         [0034]    “ 32 ” fin (of speaker grill) 
         [0035]    “ 35 ” electrode 
       DETAILED DESCRIPTION 
       [0036]      FIG. 1  are appearance views of a transceiver, which is an embodiment of the present invention.  FIG. 1A  is a front view of the transceiver,  FIG. 1B  is a left side view of the transceiver, and  FIG. 1C  is a bottom view of the transceiver. 
         [0037]    This transceiver  1  is a hand-held device for maritime communications. A feature of this transceiver  1  is that the transceiver does not sink but floats even if it is dropped into the water and when it is dropped into the water, a part of a housing flashes so that a user can easily find it even at night or if visibility is poor. 
         [0038]    The transceiver  1  presents an appearance having a main body  10  including a housing  11  and an antenna  12  disposed on the top face of the housing  11 . The housing  11  has a front housing  11 A and a rear housing  11 B. The front housing  11 A and the rear housing  11 B are joined with a gasket  13  between them. 
         [0039]    The front housing  11 A includes a substantially planar front panel  20 , and a left face plate  21 , a right face plate  22 , an top face plate  23  and a bottom face plate  24  rising rearward substantially at a right angle from a peripheral edge of the front panel  20 . On edges of the left face plate  21 , the right face plate  22 , the top face plate  23 , and the bottom face plate  24 , grooves into which the gasket  13  is inserted are formed. The rear housing  11 B has a shape of a lid in which upper, lower, right and left rims gently rise to the front from the rear face on which a clip  15  is disposed. In the edges of the rims, grooves into which the gasket  13  is inserted are formed. 
         [0040]    By joining the front housing  11 A and the rear housing  11 B together with the gasket  13  in their respective groove parts between them, intrusion of water into the inside of the housing  11  through the joined part between the front housing  11 A and the rear housing  11 B is prevented. 
         [0041]    The gasket  13  is in the loop shape and is sandwiched over the entire periphery between the edge of the front housing  11 A and the edge of the rear housing  11 B. The gasket  13  is exposed to the outside substantially over the entire periphery between the front housing  11 A and the rear housing  11 B, but the left face plate  21  and the right face plate  22  have projections  21 A and  22 A on the edges close to their bottoms, and the gasket  13  is hidden from the outside only for the parts of the projections  21 A and  22 A. 
         [0042]    The loop-shaped gasket  13  consists of a translucent section  13 A of milk white and a opaque section  13 B of blue. The gasket  13  is attached to the housing  11  so that the translucent section  13 A is located closer to the bottom face than the projections  21 A and  22 A and the opaque section  13 B is located closer to the top face than the projections  21 A and  22 A. As a result, a spot where color is roiled at the boundary between the translucent section  13 A and the opaque section  13 B is hidden behind the projections  21 A and  22 A, and appearance is maintained while color separation to two colors of the gasket  13  is realized. 
         [0043]    On the lower part inside the main body  10  (housing  11 ), an LED  41  (See  FIG. 4 ) is disposed, and when the transceiver  1  is dropped into the water, the LED  41  flashes. By means of the light, the translucent section  13 A of the gasket  13  becomes bright seen from the outside. The LED  41  and the translucent section  13 A correspond to the light emission part of the present invention. 
         [0044]    The antenna  12  is disposed closer to the front face on the top face of the housing  11 , that is, on the top face of the front housing  11 A, directed upward. The antenna  12  is a rod-shaped antenna having a coil-shaped antenna wire contained in a resin pipe. The antenna wire is a copper wire or an iron wire, which has a weight. By means of the weight of the antenna  12 , the weight balance of the entire transceiver  1  is biased to the upper front. 
         [0045]    On the front panel  20  of the front housing  11 A, a speaker grill  16 , a display  17 , and a plurality of keys  18  are disposed in above order. Also, a PTT switch  19  is disposed on the right face plate  22 , a charging connector  14  covered by a water-proof cap on the left side of the antenna  12  on the top face plate  23 , and a clip  15  at the center of the rear housing  11 B, respectively. Inside the speaker grill  16  of the front panel  20 , as shown in  FIGS. 2 and 3 , a speaker  30  and a pair of electrodes  35  that detects drop of the transceiver  1  into the water are disposed. 
         [0046]    A configuration in the vicinity of the speaker grill  16  of the front housing  11 A will be described referring to  FIGS. 2 and 3 .  FIGS. 2 and 3  show different embodiments in which mounting forms of the electrodes  35  are different from each other.  FIGS. 2A and 3A  are left sectional views in the vicinity of the speaker grill  16  of the front housing  11 A, while  FIGS. 2B and 3B  are views of the vicinity of the speaker grill  16  of the front housing  11 A seen from behind the speaker  30 . 
         [0047]    On the upper part of the front panel  20  of the front housing  11 A, a grill fitting hole  111 ,which is approximately square is formed on the outer surface of the front housing  11 A with a depth of approximately half of a thickness of the front housing  11 A. Also, on the inner surface of the front housing  11 A opposing the grill fitting hole  111 , a speaker fitting hole  112  is formed circularly into which the speaker  30  is fitted. The speaker fitting hole  112  is formed opposing the center of the grill fitting hole  111  smaller than the grill fitting hole  111 . By forming of the grill fitting hole  111  and the speaker fitting hole  112 , a circular opening part in the shape of the speaker  30  is formed in the front housing  11 A. 
         [0048]    The speaker grill  16  is fitted in and fixed to the grill fitting hole  111  from outside the front housing  11 A. The speaker grill  16  has an inverted U-shaped frame  33  and a plurality of fins  32  formed in the lateral direction inside the frame  33 . In the speaker fitting hole  112 , a dust proof net  31  and a water-proof speaker  30  are fitted, and an adhesive  34  is applied on the outer periphery of the speaker  30 . By means of this adhesive  34 , the speaker  30  and the net  31  are fixed to the front housing  11 A, and a gap is blocked. Moreover, the pair of electrodes  35  are disposed, which leads from the inside of the fin  32  to the inside of the front housing  11 A are disposed. 
         [0049]    In the embodiment in  FIG. 2 , the shape of the electrode  35  is a straight pin shape. The pair of electrodes  35  are disposed linearly penetrating two through holes  113  formed right and left of the speaker fitting hole  112  of the front housing  11 A, respectively. The through hole  113  is formed on the grill fitting hole  111 , that is, on the back side of the speaker grill  16  and at a position outside the speaker fitting hole  112 . Also, an adhesive  36  is applied on the periphery of the through hole  113  inside the front housing  11 A. The adhesive  36  fixes the electrodes  35  and also seals intrusion of water through the through hole  36 . 
         [0050]    In the embodiment in  FIG. 3 , the pair of electrodes  35  are aligned vertically on the right side of the speaker  30  seen from the inside of the front housing  11 A, and each tip of the electrodes  35  respectively protrudes to the inside of the two fins  32  aligned vertically. Each electrode  35  consists of a conductor strip, and is formed in a stair-like shape having two steps by folding up and down the conductor strip. The tip of the electrode  35  penetrates the through hole  113  and protrudes to the outside of the housing  11 , and the first step face is brought into contact with the back side of the front housing  11 A so as to prevent removal of the electrode  35  to the outside of the housing  11 . Also, the adhesive  36  is applied on the periphery of the through hole  113  inside the front housing  11 A. The adhesive  36  fixes the electrode  35  and seals intrusion of the water through the through hole  113 . By attaching the electrode  35  in this way, the second step face of the electrode  35  is located in the air floating from the inside of the front housing  11 A. As a result, even if the lead wire is soldered on the second step face, the front housing  11 A is not melted. 
         [0051]    In either of the embodiments in  FIGS. 2 and 3 , the pair of electrodes  35  are disposed with a distance or in a positional relationship such that both are electrically conducted when they sink under the water and not electrically conducted at such wet of some of droplets. The pair of electrodes  35  corresponds to the drop detection part of the present invention. 
         [0052]      FIG. 4  is a diagram for explaining a partial internal structure of the transceiver  1 . This diagram is that of the inside of the housing  11  seen from the left side. A print circuit board  40  on which various circuits are mounted is disposed on the front face side inside the housing  11  (in the front housing  11 A), and the LED  41  is mounted on the lower end part thereof. The LED  41  is a self-flashing type LED and its turning-on (flashing)/turning-off is controlled by a lighting control circuit shown in  FIG. 5 . Since the self-flashing LED has a flashing circuit inside, an optical axis  42  is inclined, and as shown in the figure, only by mounting the LED  41  upright to the board, the optical axis  42  can be exactly directed to the direction of the translucent section  13 A of the gasket  13 . As a result, when the LED  41  is turned on, the translucent section  13 A of the gasket  13  is directly illuminated by the light, and it appears from the outside that the translucent section  13 A emits light. 
         [0053]      FIG. 5  is a diagram illustrating a lighting control circuit of the LED  41 . This lighting control circuit corresponds to a light-emission control circuit of the present invention. This lighting control circuit is a circuit constituted such that a Pch MOS field-effect transistor (FET) Q 1  and an NPN transistor Q 2  are turned on when the pair of electrodes  35  ( 35 A and  35 B) are electrically conducted each other, and the LED  41  connected between a collector of the transistor Q 2  and a power source is made to flash (lighted). 
         [0054]    The power source (lithium-ion battery) and this circuit are directly connected to each other without through a power switch, and even if the power switch is off, the LED  41  is made to flash if the transceiver  1  is dropped into the water. A resistor R 1 , a resistor R 2  and the pair of electrodes  35  ( 35 A and  35 B) are connected in series between the power source and the ground. A connection point between the resistor R 1  and the resistor R 2  is connected to the gate of the FET Q 1 . The source of the FET Q 1  is connected to the power source, and a forward-direction diode D 1  and a capacitor C 1  are connected in series between the drain of the FET Q 1  and the ground. A connection point between the diode D 1  and the capacitor C 1  is connected to the base of the transistor Q 2 . The transistor Q 2  is a transistor for digital operation that incorporates a resistor, and a resistor is connected in series to the base. The LED  41  is connected between the collector of the transistor Q 2  and the power source, and the emitter of the transistor Q 2  is grounded. 
         [0055]    When the transceiver  1  is dropped into the water and the electrodes  35 A and  35 B are electrically conducted to each other, a power voltage divided at the resistors R 1  and R 2  is applied to the gate of the FET Q 1 . As a result, the FET Q 1  is turned on, and the capacitor C 1  is quickly charged through the diode D 1 . By the charging of the capacitor C 1 , a base voltage of the transistor Q 2  is raised, and the transistor Q 2  is turned on. By the turning-on of the transistor Q 2 , an electric current flows through the LED  41  and the LED  41  is made to flash. 
         [0056]    When the transceiver  1  is taken out of the water and the electrical conduction between the electrodes  35 A and  35 B is shut off, the FET Q 1  is turned off, but since the capacitor C 1  has been charged close to the power voltage, the transistor Q 2  is kept in the ON state until the capacitor C 1  is discharged through the base/emitter of the transistor Q 2 . The capacitor C 1  is chosen based on the capacitance so as to keep Q 2  in the ON state for 30 to 60 seconds after shut-off of the electrodes  35 A and  35 B. As a result, even if a user takes up the transceiver  1  out of the water surface in a dark environment, the LED  41  keeps flashing so as not to miss the transceiver. The transistor Q 2  and the capacitor C 1  correspond to the delay circuit of the present invention. 
         [0057]    Since the transceiver  1  has been saved an entire weight by using a large capacity lithium-ion battery with a light weight as a power source and the like and has the housing  11  of the water-proof structure, the transceiver floats on the water surface without sinking even if it is dropped into the water. Also, as shown in  FIGS. 1 to 4 , since components with weights such as the speaker  30 , the print circuit board  40 , the antenna  12  and the like are disposed on the front face side in a biased manner, the center of gravity of the transceiver  1  is close to the front face, and on the water surface, as shown in  FIG. 6 , the transceiver floats in an attitude with the upper front side down and the lower rear side up. With this attitude, since the electrodes  35  sink in the water, they are electrically conducted by conductivity of water. As a result, the LED  41  flashes. By the flashing of the LED  41 , the translucent section  13 A on the lower part of the gasket  13  flashes. Since the translucent section  13 A is on the water surface and also directed upward, its presence can be displayed such that a user who dropped the transceiver  1  into the water can easily find it. 
         [0058]      FIGS. 7  are diagrams illustrating another installation form of the electrodes  35 .  FIG. 7A  is a left sectional view of the vicinity of the speaker grill  16  of the front housing  11 A, and  FIG. 7B  is a diagram of the vicinity of the speaker grill  16  of the front housing  11 A seen from behind the speaker  30 . 
         [0059]    In the embodiment in  FIG. 7 , a through hole exclusively for the electrode  35  is not opened, but the electrode  35  is made to pass through a gap between the speaker fitting hole  112  and the speaker  30 . The electrode  35  is formed in a stair-like shape having one step. The electrode  35  reaches the outside from the inside of the front housing  11 A (speaker  30  and the net  31 ) along the outer periphery of the speaker fitting hole  112  and then, bends to the center side of the speaker  30  and reaches the front face of the speaker  30  and bends again and protrudes to the back side of the fin  32 . 
         [0060]    In above embodiments, a self-flashing LED is used as the LED  41 , but a normal LED may be used, and a flashing circuit may be disposed outside of the LED separately. 
         [0061]    In above embodiments, a handy transceiver for maritime communications was explained as an example, but the portable electronic device of the present invention is not limited to the handy transceiver. 
         [0062]    Also, the transceiver  1  of above embodiments have a structure which is water-proof and floats on the water (has a specific gravity smaller than water), but the present invention can be also applied to a portable electronic device with the specific gravity equal to or larger than water.