Patent Abstract:
An electronic device is provided that includes a housing, a waterproof air-permeable membrane, a door, an air pressure gauge and a watertightness detector. The housing defines an opening and includes an air vent. The waterproof air-permeable membrane blocks off the air vent. The door is shiftably coupled to the housing and movable between a first position that uncovers the opening and a second position that covers the opening. The door and the housing form a watertight structure when the door is in the second position. The air pressure gauge is disposed inside the watertight structure. The watertightness detector is configured to determine whether the housing and the door have maintained a watertight state based on changes in the air pressure inside the watertight structure when the door moves from the first to the second position. The changes in the air pressure are measured by the air pressure gauge.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2011-063830, filed on Mar. 23, 2011 and Japanese Patent Application No. 2011-174222, filed on Aug. 9, 2011. The entire disclosure of Japanese Patent Application No. 2011-063830 and Japanese Patent Application No. 2011-174222 are hereby incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The technology disclosed herein relates to an electronic device and an imaging device equipped with an air pressure sensor. 
     2. Background Information 
     It is conventionally known in the art to test the watertightness (whether or not a watertight state is maintained) of a housing having a watertight structure. For instance, in Japanese Laid-Open Patent Application 2010-135429, a separate apparatus had to be connected in order to test the device in question. 
     SUMMARY 
     It has been discovered that the aforementioned conventional method for testing is difficult to apply while an ordinary user is using an electronic device. 
     Accordingly, one object of technology disclosed herein is to provide a device in which a testing for watertightness can be performed with a simple structure. 
     In accordance with one aspect of the technology disclosed herein, an electronic device is provided that includes a housing, a waterproof air-permeable membrane, a door, an air pressure gauge and a watertightness detector. The housing defines an opening and includes an air vent. The waterproof air-permeable membrane blocks off the air vent. The door is shiftably coupled to the housing and movable between a first position that uncovers the opening and a second position that covers the opening. The door and the housing form a watertight structure when the door is in the second position. The air pressure gauge is disposed inside the watertight structure. The watertightness detector is configured to determine whether the housing and the door have maintained a watertight state based on changes in the air pressure inside the watertight structure when the door moves from the first to the second position. The changes in the air pressure are measured by the air pressure gauge. 
     These and other features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred and example embodiments of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Referring now to the attached drawings which form a part of this original disclosure: 
         FIG. 1A  and  FIG. 1B  are front oblique views of the digital camera  1  pertaining to an embodiment; 
         FIG. 2  is a rear oblique view of the digital camera  1  pertaining to an embodiment; 
         FIG. 3  is a front view of a housing  10  pertaining to an embodiment; 
         FIG. 4  is a rear oblique view of the housing  10  pertaining to an embodiment; 
         FIG. 5  is an exploded oblique view of the housing  10  pertaining to an embodiment; 
         FIG. 6  is a cross section along the A-A line in  FIG. 3 ; 
         FIG. 7  is a function block diagram of the digital camera  1  pertaining to an embodiment; 
         FIG. 8  is a function block diagram of a controller  110  pertaining to an embodiment; 
         FIG. 9  is a flowchart illustrating the operation of a system-on-a-chip  100 ; 
         FIG. 10  is a flowchart illustrating the operation of a watertightness detector  115 ; and 
         FIG. 11A  and  FIG. 11B  are graphs of the relation between the open/closed state of a door  12  and the air pressure inside the housing  10 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Selected embodiments will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
     In the following embodiments, a digital camera will be used as an example in describing an imaging device. In the following description, using a digital camera in its landscape orientation as a reference, the subject side will be referred to as the “front,” the opposite side from the subject as the “rear,” the vertically upward part as “upper,” the vertically downward part as “lower,” the right side in a state of facing the subject head on as the “right,” and the left side in a state of facing the subject head on as the “left.” “Landscape orientation” is the orientation when the long-side direction of a captured image substantially coincides with the horizontal direction in the captured image. 
     Simplified Configuration of Digital Camera  1   
     The simplified configuration of the digital camera  1  pertaining to the embodiment will be described through reference to the drawings.  FIG. 1A  and  FIG. 1B  are front oblique views of the digital camera  1  pertaining to the embodiment.  FIG. 1A  shows the state when the door  12  is closed, and  FIG. 1B  shows the state when the door  12  is open.  FIG. 2  is a rear oblique view of the digital camera  1  pertaining to the embodiment. 
     The digital camera  1  comprises a housing  10 , a door  12 , a front cover  20 , a rear cover  30 , a manipulation unit  40 , an optical system  50 , a liquid crystal monitor  60 , a flash  65 , a card slot  93 , and an open/closed detector switch  150 . 
     The housing  10  is a holding vessel that constitutes a watertight structure along with the door  12 . The housing  10  deforms under water pressure when immersed in water. Specifically, the amount of deformation of the housing  10  increases in proportion to the water depth. This housing  10  is preferably made of a material that is flexible and elastic. The housing  10  has an opening  10   a  and a frame  10   b . The opening  10   a  is formed taller than it is wide on the side face of the housing  10 . The frame  10   b  is formed so as to surround the opening  10   a  on the side face of the housing  10 . The opening  10   a  is blocked off when the door  12  is snugly fitted to the frame  10   b.    
     The door  12  can be opened by sliding an open/close switch  12   a  provided to the door  12  in the “open” direction during replacement of a memory card  93   b , a battery  97 , etc. The door  12  is connected to the housing  10  via a hinge  12   d . The door  12  rotates with the hinge  12   d  as its rotational center, which allows it to transition between an “open” state of not covering the opening  10   a  and a “closed” state of covering the opening  10   a . A gasket  12   b  is disposed surrounding the inner face of the door  12  and fits snugly against the frame  10   b  of the housing  10 , which puts the housing  10  in a watertight state in the “closed” state. Thus, the door  12  is provided so that the opening  10   a  of the housing  10  can be opened and closed, and constitutes a watertight structure along with the housing  10  in its “closed” state of covering the opening  10   a.    
     The card slot  93  is used to removably insert the memory card  93   b . The battery  97  supplies power for operating the digital camera  1 . The memory card  93   b  and the battery  97  are on the inside of the frame  10   b , and can be removed when the door  12  is opened. 
     A protrusion  12   e  is disposed in the bounded region of the inner face of the door  12 , the bounded region is bounded by the gasket  12   b . The open/closed detector switch  150  is provided on the inside of the opening  10   a  surrounded by the frame  10   b  of the housing  10 . The protrusion  12   e  is provided at a location where it will press on the open/closed detector switch  150  when the door  12  is closed. In this embodiment, the protrusion  12   e  and the open/closed detector switch  150  constitute a means for detecting whether the door is open or closed. When the door  12  is closed, the open/closed detector switch  150  is pressed by the protrusion  12   e , that is, the open/closed detector switch  150  enters its ON state, and a controller  110  (discussed below) detects that the door  12  has been closed. When the door  12  is opened, the open/closed detector switch  150  enters its OFF state, and the controller  110  detects that the door  12  has been opened. 
     The front cover  20  is attached to the front face of the housing  10 . The rear cover  30  is attached to the rear face of the housing  10 . The operation unit  40  is attached to the rear face of the housing  10 , and is exposed from the rear cover  30 . 
     The operation unit  40  handles various inputs from the user. In this embodiment, the operation unit  40  handles the selection of the water depth measurement mode as one of the imaging modes. The optical system  50  is attached to the front face of the housing  10 , and is exposed from the front cover  20 . The optical system  50  lets external light into the interior of the housing  10  during imaging. The liquid crystal monitor  60  is attached to the rear face of the housing  10 , and is exposed from the rear cover  30 . Captured images are displayed on the liquid crystal monitor  60 . The flash  65  is attached to the front face of the housing  10 , and is exposed from the front cover  20 . 
     Internal Configuration of Housing  10   
       FIG. 3  is a front view of the housing  10  pertaining to the embodiment.  FIG. 4  is a rear oblique view of the housing  10  pertaining to the embodiment.  FIG. 5  is an exploded oblique view of the housing pertaining to the embodiment.  FIG. 6  is a cross section along the VI-VI line in  FIG. 3 . In  FIGS. 3 and 4 , the door  12  is attached to the housing  10 . 
     The housing  10  is constituted by a front panel  70  and a rear panel  80 , and a control board  90  is disposed in the interior of the housing  10 . The front panel  70  and rear panel  80  are fitted snugly together in order to ensure the watertightness of the housing  10 . Although not depicted in the drawings, a concave component constituting the opening  10   a  is formed on the right side face of each of the front panel  70  and rear panel  80 . The control board  90  is sealed in between the front panel  70  and the rear panel  80 . 
     The front panel  70  has an air vent  71  and a waterproof air-permeable membrane  72 . The air vent  71  communicates between the inside and outside of the housing  10 . The waterproof air-permeable membrane  72  blocks off the air vent  71 . The waterproof air-permeable membrane  72  is made from a material that is air-permeable. Accordingly, when the digital camera  1  is located in the air, the air pressure inside the housing  10  coincides with the atmospheric air pressure. Also, the waterproof air-permeable membrane  72  is made from a material that is waterproof. Accordingly, when the digital camera  1  is located in water, infiltration by water through the air vent  71  is suppressed. An example of a material that can be used for the waterproof air-permeable membrane  72  is Gore-Tex® made by W.L. Gore &amp; Associates. 
     The air pressure change inside the housing  10  will now be described through reference to the drawings.  FIG. 11A  and  FIG. 11B  show the relation between the open/closed state of the door  12  and the air pressure inside the housing  10 .  FIG. 11A  is a graph of the change in air pressure inside the housing  10  when the door  12  has been closed from its open state. Time is plotted on the horizontal axis, and the air pressure inside the housing  10  on the vertical axis. The solid line indicates an example of the change in air pressure inside the housing  10  when the housing  10  maintains a watertight state. The one-dot chain line indicates an example of the change in air pressure inside the housing  10  when the housing  10  does not maintain a watertight state.  FIG. 11B  is a graph of the state of the open/closed detector switch  150 . The open/closed detector switch  150  changes from OFF to ON at time A in synchronization with the timing at which the air pressure inside the housing  10  suddenly rises. 
     In this embodiment, a watertight state is maintained, and immediately after the door  12  is closed (the open/closed detector switch goes ON), there is a slight rise in the air pressure inside the housing  10  (time A). After this, air flows in and out through the waterproof air-permeable membrane  72 . However, the flow of air through the waterproof air-permeable membrane  72  is less than when the watertight state is not being maintained with the door  12  closed, that is, when the gasket  12   b  and the frame  10   b  are not fitted snugly together. Accordingly, when a watertight state is maintained, the time it takes for the air pressure inside the housing  10  to equalize with atmospheric pressure after the door  12  has been closed is longer than when a watertight state is not being maintained (time C; in this embodiment, the elapsed time from time A is approximately 1 minute). However, if foreign matter clings to the gasket  12   b  of the door  12 , for example, the gasket  12   b  and the frame  10   b  will not fit snugly together, and there will be a gap. Since air flows out through this gap, the watertightness inside the housing is lost and the rise in air pressure when the door  12  is closed is less than when a watertight state is maintained, and also the time it takes the air pressure inside the housing  10  to equalize with atmospheric pressure is shorter (time B; in this embodiment, the elapsed time from time A is approximately 2 seconds). The time it takes for the air pressure inside the housing  10  to equalize with atmospheric pressure is greatly affected by the size of the air vent  71  and the air permeability of the waterproof air-permeable membrane  72 . 
     A waterproof tape (not shown) is attached between the front plate  70  and the optical system  50  and flash  65 . A gasket (not shown) is attached between the rear plate  80  and the operation unit  40  and liquid crystal monitor  60 . 
     The control board  90  has a board main body  91 ; a sensor unit  92 , a card slot  93 , and an AFE (analog front end)  94  installed on the front face of the board main body  91 ; and a system-on-a-chip  100  installed on the rear face of the board main body  91 . 
     The board main body  91  is a flat member on which various electronic parts can be installed. 
     As shown in  FIG. 6 , the sensor unit  92  has an air pressure sensor  92   a  and a temperature sensor  92   b . The air pressure sensor  92   a  detects the internal pressure inside the housing  10 . When the digital camera  1  is located in the air, the detected air pressure value P detected by the air pressure sensor  92   a  is in agreement with atmosphere pressure. When the digital camera  1  is located under water, the detected air pressure value P detected by the air pressure sensor  92   a  rises in proportion to the water depth of the housing  10 , that is, in proportion to the decrease in volume inside the housing  10 . The temperature sensor  92   b  detects the temperature inside the housing  10 . 
     The card slot  93  is used to removably insert a memory card. The AFE  94  subjects image data produced by a CCD image sensor  95  (one example of an “imaging means” discussed below) to noise suppression processing, processing for amplification of the input range width of an A/D converter, A/D conversion processing, and so forth. 
     The system-on-a-chip  100  provides overall control over the operation of the various electronic parts comprised by the digital camera  1 . The configuration of the system-on-a-chip  100  will be discussed below. 
     Functional Configuration of Digital Camera  1   
       FIG. 7  is a function block diagram showing the functional configuration of the digital camera  1  pertaining to the embodiment. In the following description, the configuration other than that discussed above will mainly be described. 
     The optical system  50  has a focus lens  51 , a zoom lens  52 , an aperture  53 , and a shutter  54 . The focus lens  51  adjusts the focus state of the subject. The zoom lens  52  adjusts the field angle of the subject. The aperture  53  adjusts the amount of light incident on the CCD image sensor  95 . The shutter  54  adjust the exposure time of the light incident on the CCD image sensor  95 . The focus lens  51 , the zoom lens  52 , the aperture  53 , and the shutter  54  are each driven by a DC motor, a stepping motor, or another such drive unit according to a command signal send from a controller  110 . 
     The CCD image sensor  95  is an example of the “imaging means” pertaining to the embodiment. The CCD image sensor  95  produces image data by opto-electrical conversion. 
     The system-on-a-chip  100  has the controller  110 , an image processor  120 , a buffer memory  130 , and a flash memory  140 . 
     The controller  110  provides overall control of the operation of the entire digital camera  1 . The controller  110  is constituted by a ROM, a CPU, etc. The ROM contains programs for file control, autofocus control (AF control), automatic exposure control (AE control), and operational control over the flash  65 , as well as programs for the overall control of the operation of the entire digital camera  1 . 
     In this embodiment, the controller  110  has a mode detector  111 , an air pressure value corrector  112 , a differential calculator  113 , and a water depth calculator  114  and a watertightness detector  115 . If the user has selected water depth measurement mode with the manipulation unit  40 , the controller  110  calculates the water depth D of the housing  10  on the basis of the air pressure P detected by an air pressure sensor  92   a . The controller  110  here reads a reference air pressure value P 0  and a reference air temperature value t 0  from a flash memory  140 . Also, if the controller  110  detects that the open/closed detector switch  150  is ON, that is, that the door  12  has transitioned from its open state to its closed state, then the watertightness detector  115  decides whether or not the housing  10  is in a watertight state. The functional configuration and operation of the controller  110  will be discussed below. 
     The controller  110  can also be constituted by a hard-wired electronic circuit or a microprocessor that executes programs. 
     The image processor  120  subjects the image data that has undergone various processing by the AFE  94  to white balance correction, color reproduction correction, gamma correction, smear correction, YC conversion processing, electronic zoom processing, and other such processing. In this embodiment, the image processor  120  subjects the image data to white balance correction, color reproduction correction, and gamma correction when the water depth value D of the housing  10  exceeds a specific water depth (such as about 3 meters). Here, the image processor  120  performs the white balance correction, color reproduction correction, and gamma correction so as to minimize an increase in blueness in the captured image (that is, a decrease in redness in the captured image). 
     The image processor  120  can also be constituted by a hard-wired electronic circuit or a microprocessor that executes programs. 
     The buffer memory  130  is a volatile storage medium that functions as a working memory for the controller  110  and the image processor  120 . In this embodiment, the buffer memory  130  is a DRAM. 
     The flash memory  140  is an internal memory of the digital camera  1 . The flash memory  140  is a non-volatile storage medium. In this embodiment, the reference air pressure value P 0  and reference air temperature value t 0  are stored in the flash memory  140 . 
     Measuring Water Depth Value D from Detected Air Pressure Value P 
     The waterproof air-permeable membrane  72  blocks off the air hole  71  in the digital camera  1 . When atmospheric pressure changes occur in the atmosphere, the internal pressure inside the housing  10  is changed in accordance with the atmospheric pressure due to the air permeability of the waterproof air-permeable membrane  72 . Consequently, the air pressure inside the housing  10  is equal to the atmospheric pressure. 
     Then the digital camera  1  is gradually lowered in altitude and the air pressure inside the housing  10  becomes substantially equal to the atmospheric pressure at the altitude of the water surface just after the digital camera  1  drops under a water surface. After this, as the camera is submerged in the water, there is no change in the air pressure inside the housing  10 , assuming the housing  10  is not deformed by water pressure. In actual practice, however, the housing  10  of the digital camera  1  is gradually deformed by the water pressure, which increases along with the water depth. This deformation is accompanied by a gradually rise in the air pressure inside the housing  10 . The external water pressure (the water depth value D) can be estimated by measuring the air pressure change inside the housing  10 . This is how the water depth value D is measured (estimated) with the digital camera  1  in this embodiment. 
     Specifically, air pressure change inside the housing  10  attributable to deformation of the housing  10  by water pressure is measured by the air pressure sensor  92   a , and the water pressure (the water depth value D) can be estimated on the basis of this air pressure change. The relation between the air pressure change inside the housing  10  and the water pressure (the water depth value D) can be approximated by a specific nonlinear function (hereinafter referred to as a “water depth calculation function”). 
     Functional Configuration of Controller  110   
       FIG. 8  is a function block diagram of the functional configuration of the controller  110  pertaining to the embodiment. 
     The controller  110  has the mode detector  111 , the air pressure value corrector  112 , the differential calculator  113 , and the water depth calculator  114  and the watertightness detector  115 . 
     The mode detector  111  decides whether or not the camera is in water depth measurement mode. Setting and unsetting of the water depth measurement mode are performed with the operation unit  40 . If the mode detector  111  decides that the camera is in water depth measurement mode, a notification to that effect is sent to the air pressure value corrector  112 . 
     The air pressure value corrector  112  performs temperature correction on the detected air pressure value P detected by the air pressure sensor  92   a  on the basis of the reference air temperature value t 0  stored in the flash memory  140  and the detected temperature value t detected by the temperature sensor  92   b . More specifically, the air pressure value corrector  112  calculates the corrected air pressure value P′ from the following formula (I).
 
 P′=P ×(273.2+ t   0 )÷(273.2+ t )  (1)
 
     The differential calculator  113  calculates the differential ΔP between the reference air pressure value P 0  stored it the flash memory  140  and the corrected air pressure value P′ calculated by the air pressure value corrector  112 . This differential ΔP is the relative amount of change in air pressure relative to the reference air pressure value P 0 . 
     The water depth calculator  114  calculates the water depth value D on the basis of the differential ΔP found by a differential detector  102  and the water depth calculation function. The water depth calculator  114  displays the calculated water depth value D on the liquid crystal monitor  60 . Also, the water depth calculator  114  notifies the image processor  120  when the calculated water depth value D exceeds the specific water depth (such as about 3 meters). The image processor  120  subjects the image data to white balance correction, color reproduction correction, and gamma correction according to the notification from the water depth calculator  114 . 
     Upon detecting that the open/closed detector switch  150  is ON, that is, that the door  12  is in its closed state, the watertightness detector  115  decides whether or not the housing  10  is in a watertight state on the basis of the change in the air pressure value P detected by the air pressure sensor  92   a . If it is decided that the housing  10  is not in a watertight state, a warning is displayed on the liquid crystal monitor  60 . 
     Operation of System-on-a-Chip  100   
     The operation of the system-on-a-chip  100  pertaining to the embodiment will be described through reference to the drawings.  FIG. 9  is a flowchart illustrating the operation of the system-on-a-chip  100 . In the following description, we will assume that the water depth measurement mode has been detected by the mode detector  111 . 
     In step S 10 , the controller  110  reads the reference air pressure value P 0  and reference air temperature value t 0  stored in the flash memory  140 . 
     In step S 20 , the controller  110  decides whether or not the water depth measurement mode is continuing. If the water depth measurement mode is continuing, the processing proceeds to step S 30 . If the water depth measurement mode has been switched off by the mode detector  111 , the water depth measurement processing is ended. 
     In step S 30 , the controller  110  detects the detected air pressure value P outputted from the air pressure sensor  92   a , and the detected temperature value t outputted from the temperature sensor  92   b.    
     In step S 40 , the controller  110  finds the temperature-corrected air pressure value P′ from the reference air temperature value t 0  read in step S 10  and the detected air pressure value P and the detected temperature value t detected in step S 30 . 
     In step S 50 , the system-on-a-chip  100  calculates the differential ΔP between the reference air pressure value P 0  read in step S 10  and the temperature-corrected air pressure value P′ calculated in step S 40 . 
     In step S 60 , the controller  110  finds the water depth value D by using the water depth calculation function and the differential ΔP found in step S 50 . 
     In step S 70 , the controller  110  displays the water depth value D found in step S 60  on the liquid crystal monitor  60 . 
     In step S 80 , the controller  110  decides whether or not the water depth value D found in step S 60  exceeds the specific water depth (such as about 3 meters). If the specific water depth is exceeded, the processing proceeds to step S 90 . If the specific water depth is not exceeded, the processing proceeds to step S 20 . 
     In step S 90 , the image processor  120  performs white balance correction, color reproduction correction, and gamma correction on the image data. 
     Operation of Watertightness Detector  115   
     The operation of the watertightness detector  115  pertaining to this embodiment will be described through reference to the drawings.  FIG. 10  is a flowchart illustrating the operation of the watertightness detector  115 . The following description is of the operation in a state in which power has been switched on to the digital camera  1  and the door  12  is in its closed state, that is, a state in which “off” has been detected by the open/closed detector switch  150 . 
     In step S 101 , the watertightness detector  115  decides whether the open/closed detector switch  150  is ON or OFF. If OFF, the state of the open/closed detector switch continues to be monitored. If ON, the flow moves to step S 102 . 
     In step S 102 , the watertightness detector  115  starts a counter. 
     In step S 103 , the watertightness detector begins sampling the air pressure value of the air pressure sensor  92   a . More specifically, the air pressure value of the air pressure sensor  92   a  is acquired for each processing performed in step S 103 , and this is stored in the flash memory  140 . The flash memory  140  stores the air pressure values acquired a specific number of times in the past (such as the last 10 times). 
     In step S 104 , an evaluation is made as to whether the change in the air pressure value is a specific value or lower on the basis of the air pressure values stored in step S 103 . In this embodiment, more specifically, the air pressure values acquired a certain number of times are compared, and if the change falls within a specific range that can be considered to be substantially no change, then the air pressure inside the housing and the air pressure outside are considered to be equal, and the flow moves to step S 105 . For example, the differences between two consecutively acquired air pressure values are found successively for the last ten air pressure values that have been acquired, and if the total value is below a specific threshold, the air pressure inside the housing can be considered equal to the air pressure outside. If the air pressure value is not within the specific range, the counter is increased by one, and the flow returns to step S 103 . 
     In step S 105 , the counter value is checked. If the counter value is at least a specific value, it is determined that a watertight state is being maintained, and the flow moves to step S 106 . If the counter value is less than the specific value, it is determined that foreign matter or the like has stuck to the door and the watertight state has been lost, and the flow moves to step S 107 . 
     In step S 106 , the watertightness detector  115  displays on the liquid crystal monitor  60  that the status is normal, and notifies the user that a watertight state is in effect. Furthermore, the watertightness detector  115  automatically starts the operation of watertightness testing by moving the open/closed detector switch from OFF to ON, regardless of the intention of the user. Therefore, if the status is normal, the processing of step S 106  may be omitted. 
     In step S 107 , the watertightness detector  115  displays a warning on the liquid crystal monitor  60 , and notifies the user that the housing is not in a watertight state. 
     EFFECTS OF THE INVENTION 
     (1) The digital camera  1  pertaining to an embodiment comprises the housing  10  having the opening  10   a  and the air vent  71 , the waterproof air-permeable membrane  72  provided so as to block off the air vent  71 , the door  12  that constitutes a watertight structure along with the housing  10  by entering a closed state of covering the opening  10   a , the air pressure sensor  92   a  provided inside the watertight structure, and the watertightness detector  115  that determines whether or not the housing  10  and the door  12  are maintaining a watertight state on the basis of the change in the air pressure within the watertight structure as measured by the air pressure sensor  92   a.    
     Thus, whether or not the housing  10  and the door  12  are maintaining a watertight state is determined on the basis of the change in the air pressure within the watertight structure, so whether or not a watertight state is being maintained can be determined with just the digital camera  1 . Also, an electronic device and imaging device can be provided with which a test for watertightness can be performed with a simple structure. 
     (2) The digital camera  1  pertaining to an embodiment comprises the open/closed detector switch  150  that detects that the door  12  is in a closed state and that the door  12  is in an open state (and not a closed state), and the watertightness detector  115  determines that a watertight state is not being maintained when the change in the air pressure measured by the air pressure sensor  92   a  drops below the specific value within a specific length of time after the open/closed detector switch  150  has detected that the door  12  has changed from its open state to its closed state. 
     Thus, whether or not the digital camera  1  is maintaining a watertight structure can be determined from whether or not there is a change (reduction) in the air pressure inside the housing  10  within a short time after the door  12  has been closed. 
     Other Embodiments 
     The present invention is described by the embodiment above, but this should not be interpreted to mean that the text and drawings that form part of this disclosure limit this invention. Various substitute embodiments, working examples, and implementation techniques will probably be obvious to a person skilled in the art from this disclosure. 
     (A) In the above embodiment, the controller  110  began calculation processing for the water depth value D when the user has selected the water depth measurement mode, but this is not the only option. The calculation of the water depth value D may be begun when entry of the housing  10  into water has been detected if the digital camera  1  comprises a water entry detector for detecting the entry of the housing  10  into water. In this case, since entry into water can be detected automatically, the water depth value D can be measured more accurately than when the calculation processing for the water depth value D is begun in response to operation by the user. Furthermore, the controller  110  may have a water entry detector that detects the entry of the housing  10  into water in response to a change in voltage between a pair of electrodes provided on the outer surface of the housing  10 . 
     (B) In the above embodiment, the controller  110  used specific values stored in the flash memory  140  as the reference air pressure value P 0  and the reference air temperature value t 0 , but this is not the only option. 
     For example, the controller  110  may use as the reference air pressure value P 0  the detected air pressure value P when selection of the water depth measurement mode has been detected. In this case, the water depth value D can be calculated by referring to how high the atmospheric pressure is at the point when calculation processing is started for the water depth value D. Accordingly, the water depth value D can be calculated more accurately. 
     Also, the controller  110  may use as the reference air pressure value P 0  the detected air pressure value P when entry of the housing  10  into water has been detected by the above-mentioned water entry detector. In this case, the detected air pressure value P at the point of water entry can be used as a reference, so the water depth value D can be calculated more accurately. 
     Furthermore, the controller  110  may use as the reference air pressure value P 0  the detected air pressure value P at a point in time designated by the user. In this case, the point of water entry can be accurately ascertained even if the above-mentioned water entry detector is not provided, so the water depth value D can be calculated more accurately. 
     (C) In the above embodiment, the image processor  120  performed white balance correction, color reproduction correction, and gamma correction when the water depth value D exceeded the specific water depth, but this is not the only option. For example, the image processor  120  may gradually increase the strength of the white balance correction, color reproduction correction, and gamma correction as the water depth value D becomes larger. In this case, since the correction strength can be altered according to the water depth value D, the quality of a captured image can be further improved. 
     Also, the image processor  120  may perform just one correction from among white balance correction, color reproduction correction, and gamma correction in order to minimize the increase in blueness of the captured image. 
     (D) In the above embodiment, the water depth calculator  114  calculated by the water depth value D, but this is not the only option. The water depth calculator  114  may calculate a “water pressure value” instead of the water depth value D. This “water pressure value” can be calculated from the water depth calculation function described in the above embodiment, or a similar function. 
     (E) In the above embodiment, the digital camera  1  (an example of an “imaging device”) was given as an example of an “electronic device,” but this is not the only option. Examples of the “electronic device” include video cameras, portable telephones, IC recorders, and so forth. 
     (F) In the above embodiment, whether the door  12  was open or closed was detected by the open/closed detector switch  150 , but the present invention is not limited to this. When the air pressure measured by the air pressure gauge  92   a  first rises from a steady state air pressure value (=atmospheric pressure) and reaches a maximum value and then drops back down to the steady state air pressure value, it may be determined that a watertight structure is not being maintained if the time between reaching a maximum value and the return to a steady state air pressure value is no more than a specific length of time. More specifically, when watertightness testing mode is selected by the user through the manipulation unit  40 , the watertightness detector  115  begins sampling with the air pressure sensor  92   a . A display is made on the liquid crystal monitor  60  to close the door  12  (after first opening the door  12  if the door  12  was closed), after when the system goes into standby mode. If the watertightness detector  115  detects a maximum value by monitoring the change in the air pressure value, that point in time is determined to be the instant when the door was closed, and the counter is started. In detecting the maximum value, for example, if after the start of sampling, a rise begins from a steady state (that is, atmospheric pressure) in which the air pressure value is held constant, and then a decrease begins, the maximum air pressure value within that range can be termed the maximum value. The processing after this is the same as that starting with step S 103  in  FIG. 10 . 
     (G) In the above embodiment, the watertightness detector  115  compared the air pressure values acquired a certain number of times as in steps S 103  and S 104 , and if the change fell within a specific range that could be considered to be substantially no change, then the air pressure inside the housing and the air pressure outside were considered to be equal, but the present invention is not limited to this. For instance, the air pressure value (that is, atmospheric pressure) acquired from the air pressure sensor  92   a  in a state in which the door  12  is open (when the open/closed detector switch  150  is OFF) is stored ahead of time, and if the air pressure value from the air pressure sensor  92   a  is equal to atmospheric pressure (or if the difference between the air pressure value and the atmospheric pressure is equal to or lower than a specific value) after the door  12  has been closed (after the open/closed detector switch  150  has changed from OFF to ON), the flow may proceed to step S 105 . 
     (H) In the above embodiment, the watertightness detector  115  measured time by means of a counter value, but the present invention is not limited to this. The digital camera  1  may be equipped with a clock, so that the watertightness detector  115  acquires and stores the start time in step S 102 , in step S 105  the difference between the current time and the start time is acquired as the elapsed time, and if the elapsed time is at least a specific value, it is determined that a watertight state is being maintained. 
     (I) In the above embodiment, the watertightness detector  115  displayed the determination result on the liquid crystal monitor  60  as the method for notifying the user of the result of determining watertightness, but the present invention is not limited to this. For example, in step S 106  the watertightness detector  115  may notify the user of whether or not a watertight state is being maintained by reproducing a sound from a speaker or the like. In this case, no sound is reproduced if the status is normal, and a certain sound may be reproduced only if there is a problem (if a watertight state is not being maintained). 
     Thus, the present invention of course includes various embodiments and the like that are not discussed herein. Therefore, the technological scope of the present invention is not limited to just the specific inventions pertaining to the appropriate claims from the descriptions given above. 
     General interpretation of Terms 
     In understanding the scope of the present disclosure, the term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. Also, the terms “part,” “section,” “portion,” “member” or “element” when used in the singular can have the dual meaning of a single part or a plurality of parts. Also as used herein to describe the above embodiment(s), the following directional terms “forward”, “rearward”, “above”, “downward”, “vertical”, “horizontal”, “below” and “transverse” as well as any other similar directional terms refer to those directions of a electronic device and an imaging device. Accordingly, these terms, as utilized to describe the present invention should be interpreted relative to a electronic device and an imaging device. 
     The term “configured” as used herein to describe a component, section or part of a device includes hardware and/or software that is constructed and/or programmed to carry out the desired function. 
     The terms of degree such as “substantially”, “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. 
     While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. For example, the size, shape, location or orientation of the various components can be changed as needed and/or desired. Components that are shown directly connected or contacting each other can have intermediate structures disposed between them. The functions of one element can be performed by two, and vice versa. The structures and functions of one embodiment can be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

Technology Classification (CPC): 6