Abstract:
Provided is an underwater lighting device and underwater electronic device which are comparatively inexpensive yet durable enough for long-term use. An underwater lighting unit  10 , which has an internally provided light source  11  and a gas-tight case  12  with a window  13  for allowing the passage of light from the light source  11 , is connected to a land-based unit  30  by a gas-sending tube  40 . Air is sent from the land-based unit  30  to the underwater lighting unit  10  to maintain the pressure inside the underwater lighting unit  10  at a value slightly higher than the water pressure at the location. A power line for supplying power to the underwater lighting unit  10  and a signal line for controlling the emission of their light are installed in the gas-sending tube  40 . Even if the gas-tight state of one underwater lighting unit  10  is broken, water cannot enter the underwater lighting unit  10 . Furthermore, the thereby generated bubbles help users locate the underwater lighting unit  10  in which the gas-tight state has been broken. If a plurality of underwater lighting units  10  are provided, they should preferably be connected in the form of a loop or matrix to the land-based unit  30.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a lighting device and an electronic device which can be placed under water. 
       BACKGROUND ART 
       [0002]    Various kinds of submersible lighting devices which can be placed under water have conventionally been devised for casting light from under water to a space above the water surface or for illuminating natural or artificial objects under water. One conventional lighting device has a lighting system which is divided into a plurality of lighting units. Those lighting units can be arranged in various forms, and each lighting unit can be independently controlled so as to emit light with different shades of color and levels of brightness (Non Patent Literature 1). 
       CITATION LIST 
     Non Patent Literature 
       [0003]    Non Patent Literature 1: “19-Inchi Rakku-maunto Shouhin—Shuuhen-kiki On Rain Shoppu: Chichuu Maisetsu-gata, Suichuu, Suibotsu, Funsui-you, Gaaden Raito, Wooru Wosshaa Raito, RGB Raito (Online Shop of 19-Inch Rack-Mount Products: Underground Buried Light, Underwater Light, Submersible Light, Fountain Light, Garden Light, Wall Washer Light, and RGB Light”, Kabushiki Kaisha Z-Communications, [searched on Sep. 10, 2013], the Internet 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    To use such a lighting device under water for a long period of time, its container must be highly water-tight to prevent water from entering and damaging the light source or electric systems. Meanwhile, any lighting device needs to have at least a portion of its container made of a transparent glass or resin cover to allow the passage of light. Attempting to ensure high water-tightness at the joining portion between the transparent part and a metallic or hard-resin casing used for ensuring sufficient physical strength makes the device extremely expensive. Therefore, this type of lighting device has been unsuitable in such an application where a large number of units are installed over the entire area of a pond or pool. Similar problems also arise in the case where an electronic unit containing a camera or other electronics is used underwater. 
         [0005]    The problem to be solved by the present invention is to provide an underwater lighting device and underwater electronic device which are comparatively inexpensive yet durable enough for long-term use. 
       Solution to Problem 
       [0006]    An underwater lighting device according to the present invention aimed at solving the previously described problem includes: 
         [0007]    a) an underwater lighting unit having an internally provided light source and a gas-tight case with a window for allowing the passage of light from the light source; 
         [0008]    b) a gas-sending tube to be connected to an opening provided in the gas-tight case; and 
         [0009]    c) a land-based gas-supply system for sending gas into the gas-sending tube. 
         [0010]    In the underwater lighting device according to the present invention, the light source may be supplied with power from a battery (primary or secondary battery) provided inside the underwater lighting unit. However, it is more preferable to supply the power from a land-based power source. In this case, the line for supplying the power may be provided separately from the gas-sending tube or be passed through the gas-sending tube. 
         [0011]    In the underwater lighting device according to the present invention, it is preferable to connect a signal line for transmitting a signal for controlling an emission of light from the light source (such as blinking, emission intensity or color of light). If the aforementioned power supply line is provided, the signal line should preferably be laid with or bundled with the power supply line. If the power supply line is passed through the gas-sending tube in the aforementioned manner, the signal line should also be passed through the same tube. 
         [0012]    In the case where the signal line and the power line are passed through the gas-sending tube, it is possible to transmit the signal in a superposed form on the power line instead of separately passing the two lines. Naturally, the emission control signal can also be superposed on the power line in the case of installing the power line separately from the gas-sending tube. 
         [0013]    Furthermore, it is preferable to provide the gas-supply system with a pressure sensor, a controller and a pump, and to configure the controller so as to control the operation of energizing and deactivating the pump based on a detection result obtained by the pressure sensor. The “pressure sensor” in this context does not only include a sensor for measuring a pressure value (this type of sensor is hereinafter called the “pressure value sensor”) but also a sensor which produces a signal in every predetermined range of pressure as well as a pressure switch which turns ON or OFF every time the pressure reaches a predetermined value. 
         [0014]    It is also possible to provide the gas-supply system with a gas divider in such a manner that the gas is sent through the gas divider to a plurality of underwater lighting units in parallel. 
         [0015]    Each of the aforementioned plurality of underwater lighting units arranged parallel to each other may be a plurality of underwater lighting units serially interconnected by the gas-sending tube. 
         [0016]    The plurality of underwater lighting units may be serially connected by the gas-sending tube and further connected to the gas-supply system (or the gas divider) to form a loop-like shape. 
         [0017]    The plurality of underwater lighting units may be connected to the gas-supply system (or the gas divider) by a plurality of gas-sending tubes configured like a network (or matrix). 
         [0018]    The controller of the gas-supply system should preferably be configured so as to generate an alarm when the rate of decrease in the pressure detected by the pressure value sensor is higher than a predetermined rate. The reason for this is because a sudden decrease in the pressure is most likely to be due to an occurrence of abnormal leakage of gas. As the alarm, a sound and/or light may be generated on the spot, or an e-mail or the like may be sent to a predetermined external terminal (e.g. mobile phone or personal computer). 
         [0019]    If the pressure sensor is a pressure switch which turns ON or OFF every time the pressure reaches a predetermined value, or if a similar ON/OFF control is performed using a pressure value sensor, it is preferable to configure the controller so as to generate an alarm when the situation in which the pressure is equal to or lower than a predetermined value continues for a predetermined period of time or longer (i.e. when the pump is operating for a predetermined period of time or longer). This is also because the situation is most likely to be due to an occurrence of abnormal leakage of gas. 
         [0020]    While a similar control is being performed, when the pressure is restored to a value equal to or higher than the predetermined value by the pumping operation, the pump is deactivated. After that, if the pressure once more decreases to a value equal to or lower than the predetermined value within a predetermined period of time and causes the pump to be energized once more, it is also most likely to be due to an occurrence of an abnormal leakage of gas. Therefore, in such a case, the controller should also generate an alarm. 
         [0021]    The present invention can also be used to solve the previously described problem for the aforementioned electronic unit containing a camera or other electronics. That is to say, an underwater electronic device according to the present invention includes: 
         [0022]    a) an underwater electronic unit having a gas-tight case with a window for allowing the passage of light; 
         [0023]    b) a gas-sending tube to be connected to an opening provided in the gas-tight case; and 
         [0024]    c) a land-based gas-supply system for sending gas into the gas-sending tube. 
         [0025]    The underwater electronic device according to the present invention can be transformed into the various previously described modes of the underwater lighting device (with various forms relating to the power supply, signal line, pump control, gas-supply system, gas-sending-tube configuration and/or alarm generation) by merely replacing its underwater electronic unit with an underwater lighting unit of the underwater lighting device. 
       Advantageous Effects of the Invention 
       [0026]    In the underwater lighting device or underwater electronic device according to the present invention, by sending gas into the gas-tight case of the underwater lighting unit (or the underwater electronic unit; the same shall apply hereafter), the pressure inside the gas-tight case can be maintained at higher values than the (water) pressure in the water in which the underwater lighting unit is placed. By this operation, even if the gas-tight state of the case is broken, the high gas pressure prevents water from entering the underwater lighting unit, whereby the light source, its circuit and other elements inside the case are prevented from being damaged. Furthermore, since the difference between the internal and external pressures is decreased due to the increase in the inner pressure, it is possible to use, as the gas-tight case, a simple waterproof case made of metal, plastic or other materials with a waterproof level of IP67 or so. 
         [0027]    The use of the system for supplying power from land to the light source through the line passed through this gas-supplying tube or installed separately from the gas-sending tube enables the device to be continuously used for a long period of time. 
         [0028]    In the case where the gas-supply system (or gas divider) and a plurality of underwater lighting units are connected in the form of a loop or matrix, each underwater lighting unit is supplied with gas through two gas-sending tubes. As a result, even if a gas leakage occurs at one location in the gas-sending tubes, each underwater lighting unit is assuredly supplied with gas from at least one of the gas-sending tubes, so that the water cannot enter any underwater lighting unit. 
         [0029]    Furthermore, by appropriately generating an alarm according to the detection value of a pressure sensor or similar information, users can detect in early stages a breakage or similar problem of the underwater lighting unit or gas-sending tube and take appropriate measures. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0030]      FIG. 1  is a schematic configuration diagram of a multi-series underwater lighting system as the first embodiment of the present invention. 
           [0031]      FIG. 2A  is a plan view of the underwater lighting unit in the same embodiment, and  FIG. 2B  is a sectional view at line X-X′. 
           [0032]      FIG. 3  is a sectional view (at line Y-Y′ in  FIG. 2B ) of the gas-sending tube in the same embodiment. 
           [0033]      FIG. 4  is a schematic configuration diagram of a land-based unit in the same embodiment. 
           [0034]      FIG. 5  is a schematic configuration diagram of a multi-series underwater lighting system as the second embodiment of the present invention. 
           [0035]      FIGS. 6A and 6B  are plan views of underwater electronic units in another embodiment of the present invention, where  FIG. 6A  is a unit which only includes a camera and  FIG. 6B  is a unit which includes a camera and a light source. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
       [0036]    A multi-series underwater lighting system, which is the first embodiment of the present invention, is hereinafter described with reference to  FIGS. 1-4 .  FIG. 1  is a schematic configuration diagram of the entire system. The present system roughly consists of a land-based unit  30  to be placed on land and a set of underwater equipment to be placed under water W. The underwater equipment includes a large number of underwater lighting units  10 , which are divided into a plurality of series each of which consists of a predetermined number of sequentially connected underwater lighting units. In the case of  FIG. 1 , the large number of underwater lighting units  10  inside the broken-line frame are serially connected as one series  20  by a gas-sending tube  40  (which will be described later). In the example of  FIG. 1 , more such series are connected parallel with the series  20 . 
         [0037]    Initially, the underwater lighting units  10  are described in detail.  FIG. 2A  is a plan view of one underwater lighting unit  10 , and  FIG. 2B  is a sectional view at line X-X′ in  FIG. 2A . In this example, 24 full-color LED elements  11  are used as the light source. The number of LED elements  11  can be arbitrarily chosen. It is also possible to use LED elements in which RGB colors are independently produced. An incandescent bulb or fluorescent lamp may also be used. 
         [0038]    The underwater lighting unit  10  in the present embodiment has a roughly disc-shaped metallic case  12  having an upper opening in which a glass plate  13  is placed via an O-ring. The glass plate  13  is pressed onto the case  12  by a threaded window cover  14  to create a gas-tight structure. A simple waterproof case made of metal, plastic or other materials with a waterproof level of IP67 or so can be used as the case  12 , since it does not need to be extremely gas-tight (or water-tight). A case which is entirely or partially made of resin or similar material may possibly float due to buoyancy when air is introduced inside in a manner which will be described later. In such a case, the case may be partially made of metal or a weight may be attached to its bottom or circumferential side. 
         [0039]    A small side opening is formed in each of the two sides of the case  12 . A pipe joint  15  is attached to each opening. The underwater lighting unit  10   x  located at the end of the series has the pipe joint  15  attached to only one side opening (on the side connected to the previous underwater lighting unit  10 ); the pipe joint  15  on the other side opening (at the extremity of the series) is hermetically closed by a hollow screw and an O-ring. A gas-sending tube  40  made of rubber or plastic is fitted into each pipe joint  15 . By this gas-sending tube  40 , each underwater lighting unit  10  is connected to the neighboring underwater lighting unit  10  or to the divider  34  in the land-base unit  30  (which will be described later). 
         [0040]    As shown in  FIG. 3 , a power line  41  for supplying power to be used in each underwater lighting unit  10 , a signal line  42  for transmitting control signals for controlling the blinking, emission intensity and color of the light generated by the LED elements  11 , and a common ground line  43 , are passed through the gas-sending tube  40  so as to send electric power and control signals to the plurality of underwater lighting units  10  belonging to one series  20 . There are various other wiring forms adoptable, such as a two-line system with the signals superposed on the power line  41  or a four-line system including two separate signal lines for sending and receiving signals, respectively. In the case where the signals are superposed on and transmitted through the power line  41 , a signal superposition circuit should be added to a divider circuit  36  (which will be described later). 
         [0041]      FIG. 4  shows the configuration of the land-based unit  30 . The land-based unit  30  has a power supply device (Power)  31 , a control circuit (Cont)  32 , a compressor (Comp)  33 , a divider (Div)  34  and an air drier (Dry)  35 . The power supply device  31  supplies an electric power to all the underwater lighting units  10  and to each component in the land-based unit  30 . The power may be obtained from either a commercial power supply, a private electric generator, or a large-scale electrical storage device. 
         [0042]    The control circuit  32  produces signals for controlling the blinking, emission intensity and emission color of the LED elements  11  in the underwater lighting units  10 . Those signals are sent to the underwater lighting units  10  via the divider circuit  36  (which will be described later). 
         [0043]    The compressor  33  begins or discontinues its operation under the control of the control circuit  32  so as to supply a required amount of compressed air to the divider  34  when necessary. 
         [0044]    Normally, the temperature inside the underwater lighting unit  10  placed under water is lower than the air temperature on land. Therefore, if the air on land is directly sent into the underwater lighting unit  10 , dew condensation may possibly occur inside the underwater lighting unit  10  and damage the LED elements  11 , the circuit  16  ( FIG. 2B ) and other components. Accordingly, a dehumidification system for removing moisture (humidity) from the air on land should be provided between the compressor  33  and the divider  34  (in the example of  FIG. 4 , the air dryer  35  using silica gel is provided). 
         [0045]    The divider  34  is a hermetically sealed container having a predetermined capacity for receiving air supplied from the compressor  33  and for equally sending the air to each series  20  through the gas-sending tube  40 . The divider  34  is provided with the same number of pipe joints  38  as the maximum required number of series. The joint for receiving air from the compressor  33  is provided with a check valve  37 . The divider  34  is provided with a pressure sensor P. The signal generated by the pressure sensor P is sent to the control circuit  32 . If air leakage occurs in one of the underwater lighting units  10 , the air leakage will appear as a decrease in the air pressure inside the underwater lighting unit  10 , which in turn will appear as a decrease in the air pressure inside the divider  34 , to be eventually detected by the pressure sensor P. Upon detecting this, the controller  32  energizes the compressor  33  to send air through the divider  34  to all the underwater lighting units  10 . This air is intensively distributed to the underwater lighting unit  10  in which the pressure has decreased due to the air leakage, whereby the decrease in the pressure in this unit is compensated for. 
         [0046]    More specifically, the control circuit  32  energizes the pump in the compressor  33  when the detection value Pm of the pressure sensor P has become lower than a predetermined value P 1 , and deactivates the pump when the detection value Pm has become higher than another predetermined value P 2  (&gt;P 1 ). P 1  should be set at a value slightly higher than the water pressure Pa in the water in which the underwater lighting units  10  are placed. 
         [0047]    In place of the pressure sensor P for continuously measuring the pressure value, it is possible to use a pressure switch which produces three different signals according to whether the pressure value is (1) equal to or lower than the predetermined value P 1 , (2) between P 1  and P 2 , or (3) equal to or higher than P 2 . A two-value switch which turns on and off according to the pressure value may also be used. For example, in the case where a pressure switch which opens when the pressure value has exceeded the predetermined value P 1  is used, the pump is energized when the pressure switch turns OFF and is deactivated when the pressure switch turns ON. 
         [0048]    The control circuit  32  may also be configured so as to generate an alarm according to the state and/or transition of the pressure sensor P or the pressure switch in addition to performing the control of the pump (compressor  33 ). For example, the alarm should preferably be generated when the rate of decrease in the detection value Pm of the pressure sensor P has exceeded a predetermined value S, since this situation may be the result of an abnormal leakage of air. The alarm may be generated on the spot by the control circuit  32  using sound and/or light. Additionally, a notifying e-mail or the like may be sent to a remote device (e.g. mobile phone or personal computer) via private lines, mobile phone networks, the Internet or other communication lines. Alternatively, or additionally, an alarm may also be generated when the pressure value has continuously remained at values equal to or lower than a first predetermined value P 1  for a period of time equal to or longer than a predetermined length (i.e. when the operation time of the pump has exceeded a predetermined length of time). A similar measure can also be taken in the case where the pressure switch is a two-value switch. 
         [0049]    The divider  34  also contains a power division circuit for distributing the power from the power supply device  31  to the row of underwater lighting units  10  included in each series  20  as well as a signal division circuit for distributing the previously described control signals to those units. The electric power from the power supply device  31  and the control signals from the control circuit  32  are divided into powers and signals for the plurality of series  20  by the divider circuit  36  which includes the power division circuit and the control signal division circuit, to be delivered to each underwater lighting unit  10  through the lines  41 ,  42  and  43  installed in the gas-sending tubes  40 , as already explained. The DMX or similar communication protocol can be used for the transmission of emission control signals to the underwater lighting units  10 . As already noted, in the case where the control signals are superposed on and transmitted through the power line to the underwater lighting units  10 , a signal superposition circuit and a signal separation circuit should be added to the divider circuit  36  and each underwater lighting unit  10 , respectively. 
         [0050]    Thus, in the underwater lighting units  10  according to the present embodiment, since all the underwater lighting units  10  are serially interconnected by the gas-sending tubes  40  in each series  20 , the air pressure inside the case  12  of each underwater lighting unit  10  can be arbitrarily set by supplying air from the land-based divider  34 . The air supply pressure is controlled so as to be slightly higher than the calculated or measured pressure which acts on the underwater lighting unit  10  placed at the deepest level (i.e. under the highest water pressure). Therefore, even if the gas-tight state of one of the underwater lighting units  10  is broken, it merely results in a leakage of air from the underwater lighting unit  10  to the outside; the inner space of this underwater lighting unit  10  is assuredly protected from any entry of water. Furthermore, when the gas-tight state of one underwater lighting unit  10  is broken, the air leaking from this underwater lighting unit  10  turns into bubbles, which help users locate the underwater lighting unit  10  in which the leakage has occurred. 
         [0051]    A pressure sensor may also be provided in each underwater lighting unit  10  as well as in the divider  34  of the land-based unit  30 . This configuration makes it possible to detect breakage of the gas-tight state of each underwater lighting unit  10  in earlier stages and energize the compressor  33  more promptly. 
         [0052]    If the underwater lighting units  10  are placed at a depth of 10 m or less, the pressure of the air to be supplied into those units only needs to be 1 kg/cm 2  or less; besides, the amount of air supply can be so low as to merely compensate for the leakage. Therefore, the compressor  33  may be a low-capacity type. Accordingly, it does not need to be a common piston type; there are many other choices, such as a tubular pump or bellows type. 
         [0053]    When the compressor  33  is energized and the necessary (trace) amount of air is supplied to the underwater lighting unit  10  in question, the pressure in this underwater lighting unit  10  is immediately restored to a proper level. This is detected with the pressure sensor in the underwater lighting unit  10  or the pressure sensor P in the divider  34 , and the compressor  33  is deactivated. Thus, unnecessary consumption of the electric power is avoided. 
         [0054]    In the previously described embodiment, the land-based unit  30  is configured to independently perform necessary functions. It is also possible to connect its control circuit  32  to a personal computer or similar controller directly or via communication lines, and run a software program on the computer to temporally control the amount and/or color of luminescence of each underwater lighting unit  10 . In this case, the lighting can be more freely controlled by appropriately programming the computer. 
         [0055]    As shown in the previous embodiment, the present invention can suitably be applied in a system having a plurality of underwater lighting units  10 . However, the present invention itself does not always require the use of a plurality of underwater lighting units  10 ; it can naturally be carried out for a single underwater lighting unit  10 . 
       Second Embodiment 
       [0056]    A multi-series underwater lighting system as the second embodiment of the present invention is shown in  FIG. 5 . Each component in  FIG. 5  which is denoted by a number equal to 40 plus a number given to a component in the first embodiment shown in  FIG. 1  is identical to this component in the first embodiment, and therefore, will not be hereinafter described. 
         [0057]    In the present embodiment, each series  60  composed of a plurality of underwater lighting units  50  consists of a loop-like underwater lighting unit series  61  and a matrix-like underwater lighting unit series  62 . In the loop-like series  61 , a plurality of underwater lighting units  50  are connected to the divider  74  by the gas-sending tubes  80  in the form of a loop. In the matrix-like series  62 , the gas-sending tubes  80  and the underwater lighting units  50  are connected to the divider  74  in the form of a loop, and additionally, some of the gas-sending tubes  80  are interconnected via T-shaped air joints  91  and cross-shaped air joints  92  so as to form a network (matrix) of gas-sending tubes  80 . 
         [0058]    In the multi-series underwater lighting system of the present embodiment, each underwater lighting unit  50  is connected with two gas-sending tubes  80  and supplied with air from both gas-sending tubes  80 , regardless of whether it is in the loop-like series  61  or the matrix-like series  62 . Therefore, even if air leakage occurs in one gas-sending tube  80 , the air supply from the other gas-sending tube  80  continues, whereby water is prevented from entering the underwater lighting unit  50 . 
         [0059]    The underwater lighting unit  10  or  50  in the previous embodiments can be replaced with an underwater electronic unit containing a camera (which may be either a still camera or movie camera). It may also be replaced by an underwater electronic unit having a camera and a lighting device.  FIGS. 6A and 6B  respectively show plan views of underwater electronic units in an underwater electronic device as one embodiment of the present invention corresponding to those cases. In these figures, each component denoted by a number whose last two digits are the same as a number given to a component in the underwater lighting unit  10  shown in  FIG. 2A  is identical to this component in the underwater lighting unit  10 , and therefore, will not be hereinafter described. 
         [0060]    The underwater electronic unit  110  shown in  FIG. 6A  has a camera  117  placed in it. For example, this underwater electronic unit  110  can be used for taking underwater pictures of farmed fish. 
         [0061]    The underwater electronic unit  210  shown in  FIG. 6B  has, in addition to the camera  217 , a number of LED elements  211  for illuminating the target of imaging. This underwater electronic unit  210  allows taking pictures under water by night or at a depth where no light can reach. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           10 ,  10   x ,  50  . . . Underwater Lighting Unit 
           11 ,  211  . . . LED Element 
           12  . . . Case 
           13 ,  113 ,  213  . . . Glass Plate 
           14 ,  114 ,  214  . . . Window Cover 
           15 ,  115 ,  215  . . . Pipe Joint 
           16  . . . Circuit (inside the Underwater Lighting Unit) 
           20 ,  60 ,  61 ,  62  . . . Underwater Lighting Unit Series 
           30 ,  70  . . . Land-Based Unit 
           31 ,  71  . . . Power Supply Device 
           32 ,  72  . . . Control Circuit 
           33 ,  73  . . . Compressor 
           34 ,  74  . . . Divider 
           35 ,  75  . . . Air Drier 
           36  . . . Divider Circuit 
           38  . . . Pipe Joint 
           40 ,  80 ,  140 ,  240  . . . Gas-sending Tube 
           41  . . . Power Line 
           42  . . . Signal Line 
           43  . . . Ground Line 
           110 ,  210  . . . Underwater Electronic Unit 
           117 ,  217  . . . Camera 
         P . . . Pressure Sensor