Patent Publication Number: US-2023156308-A1

Title: Image capturing apparatus

Description:
BACKGROUND 
     Field 
     The present disclosure relates to an image capturing apparatus that includes a heat dissipation structure for dissipating heat generated from a heat generating source. 
     Description of the Related Art 
     Recently, miniaturization and high density of components mounted inside an electronic device have become remarkable due to a demand for miniaturization of the device. 
     Meanwhile, a demand for higher functionality of an image capturing apparatus, particularly higher performance of moving image functions, has been increasing, so that the amount of heat generated in the apparatus tends to increase. 
     In a case where a moving image is captured in a high temperature environment, there is a high possibility that a rise in temperature inside the image capturing apparatus will cause mounted components to malfunction or deteriorate in performance, and eventually results in a malfunction of the image capturing apparatus. 
     Recently, an image capturing apparatus that performs blur correction by moving an image capturing element in a direction perpendicular to an optical axis direction has become widely used in order to improve image quality. 
     The image capturing apparatus that performs the above-described blur correction is also required to have sufficient heat dissipation performance since the heat generated by the image capturing element may affect the image quality at the time of driving a blur correction mechanism and the time of continuous imaging and moving image capturing. 
     Thus, in a case where an amount of heat dissipation by natural heat dissipation is not sufficient as compared to an amount of heat generated in an image capturing apparatus, a heat dissipation structure that uses forced air cooling by a fan is used. 
     According to Japanese Patent Application Laid-Open No. 2017-228876, an apparatus is discussed that generates convection of air taken into the apparatus by a fan and cools an image capturing element and a circuit board with a heat sink for the image capturing element and a heat sink for the circuit board that face each other. 
     In an image capturing apparatus using an image capturing element, an optical low-pass filter and an infrared ray cut filter are arranged on an object side of the image capturing element. It is known that in a case where a foreign substance such as dust adheres to a filter surface, the portion where the foreign substance has adhered is captured in an image as a black spot and deteriorates the quality of the captured image. 
     Japanese Patent Applications Laid-Open No. 2007-274663 discusses techniques for vibrating a cover glass to shake off adhered dust. Moreover, as a conventional technique to address this issue, Japanese Patent Applications Laid-Open No. 2004-264580 discusses techniques for shaking off adhered dust by vibrating a cover glass. 
     However, the apparatus discussed in Japanese Patent Application Laid-Open No. 2017-228876 can obtain a cooling effect using the fan, but the convection of the air inside the apparatus causes dust and dirt in the apparatus to fly up and adhere to a surface of the image capturing element. 
     Further, according to the apparatuses discussed in Japanese Patent Applications Laid-Open No. 2004-264580, only a relationship between an image capturing operation and an operation member of the image capturing apparatus is discussed regarding timing of dust removal, and timing of operation of the fan is not indicated. 
     SUMMARY 
     An aspect of the present disclosure is directed to the provision of an image capturing apparatus that can efficiently remove a foreign substance such as dust adhered to an image capturing element at effective timing while securing heat dissipation performance. 
     According to an aspect of the present disclosure, an image capturing apparatus includes an image capturing element, a fan configured to generate airflow for cooling the image capturing element, a foreign substance removal unit configured to remove a foreign substance from an exposure surface of the image capturing element on an object side of an imaging plane, and a control unit configured to operate the foreign substance removal unit to remove a foreign substance adhered to the exposure surface after driving the fan. 
     Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates a digital camera according to an exemplary embodiment of the present disclosure. 
         FIGS.  2 A and  2 B  are an exploded front perspective view and an exploded rear perspective view of an image capturing element unit, respectively, according to the exemplary embodiment of the present disclosure. 
         FIGS.  3 A and  3 B  are a rear view and a sectional view illustrating the image capturing element unit and a heat dissipation fan according to the exemplary embodiment of the present disclosure. 
         FIG.  4    is a block diagram illustrating a digital camera according to the exemplary embodiment of the present disclosure. 
         FIG.  5    is a flowchart illustrating operation timing of a foreign substance removal unit according to the exemplary embodiment of the present disclosure. 
         FIG.  6    is a flowchart illustrating another operation timing of the foreign substance removal unit according to the exemplary embodiment of the present disclosure. 
         FIG.  7    is a flowchart illustrating another operation timing of the foreign substance removal unit according to the exemplary embodiment of the present disclosure. 
         FIG.  8    is a flowchart illustrating another operation timing of the foreign substance removal unit according to the exemplary embodiment of the present disclosure. 
         FIG.  9    is a flowchart illustrating another operation timing of the foreign substance removal unit according to the exemplary embodiment of the present disclosure. 
         FIG.  10    is an exploded perspective view of an image capturing element according to the exemplary embodiment of the present disclosure. 
         FIGS.  11 A and  11 B  are a rear view and a schematic view illustrating the heat dissipation fan and the image capturing element unit according to the exemplary embodiment of the present disclosure. 
         FIG.  12    is a schematic view illustrating the heat dissipation fan and the image capturing element unit when viewed from the rear according to the exemplary embodiment of the present disclosure. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Exemplary embodiments of a technique according to the present disclosure will be described in detail below with reference to the attached drawings. 
     However, dimensions, materials, and shapes of components and their relative arrangements described below are to be changed as appropriate depending on the configuration and various conditions of an apparatus to which the present disclosure is applied. 
     Thus, the exemplary embodiments described below are not intended to limit the scope of the present disclosure thereto. 
     Commonly known techniques or the techniques in the public domain can be applied to a configuration and a process that are not particularly illustrated or described herein. In addition, redundant descriptions may be omitted. 
     In the drawings, the same or functionally similar elements are denoted by the same reference numerals. 
     Description of Exploded Rear Perspective View of Digital Camera  100   
     A first exemplary embodiment is described.  FIG.  1    is an exploded rear perspective view of a digital camera  100  as an image capturing apparatus according to the present disclosure. 
     As illustrated in  FIG.  1   , the digital camera  100  includes a rear cover  101 , a front base  102 , a top cover  103 , a bottom cover  104 , and a side cover  105 . 
     An image capturing element unit  106  that includes an image blur correction mechanism, a main board  107 , a shutter  108 , a finder  109 , and a chassis  110  are arranged inside the digital camera  100 . 
     The image capturing element unit  106  includes a movable unit that includes an image capturing element and a fixed unit and is arranged perpendicular to an optical axis. 
     The front base  102  is formed by using, for example, a magnesium die cast and a resin and includes a mount  102   a  for mounting an interchangeable lens. 
     The main board  107  includes a multi-layer substrate, and electronic components are mounted on both sides thereof. The main board  107  is fixed to the front base  102  and the metal chassis  110  with screws. 
     On the main board  107 , a control integrated circuit (IC)  107   a  for controlling an image capturing signal, a connector  107   b  for a storage medium for storing an external storage medium, and an external communication terminal  107   c  for connecting a connection cable to an external apparatus are mounted. 
     The external communication terminal  107   c  is covered with a terminal cover  105   a.    
     The image capturing element unit  106  is a member that particularly consumes a large amount of power and generates a large amount of heat among the components of the digital camera  100 , and the temperature of the member rises sharply. 
     An image capturing time length of the digital camera  100  is limited by an operation guarantee temperature of each member. 
     In order to maintain the image capturing time length as long as possible, it is necessary to take a measure to release the heat generated by the image capturing element unit  106 , which is a heat generating source, so that the temperature does not exceed the operation guarantee temperature. 
     The image capturing element unit  106  is fixed to the front base  102  with screws, and the heat of the image capturing element unit  106  is released to the front base  102 . 
     A heat dissipation fan  130  is arranged near the image capturing element unit  106  such that an air blowing direction is perpendicular to the optical axis. Air flows along the rear surface of the image capturing element unit  106 , which is the heat generating source, and prevents the image capturing element unit  106  from becoming locally hot (details will be described below). 
     According to the present exemplary embodiment, a centrifugal fan is used as the heat dissipation fan  130  serving as a blowing unit. However, the fan is not limited to this and, for example, an axial flow fan and the like can be used as long as heat dissipation can be achieved. 
     The main board  107  is also one of the heat generating sources, so that the heat dissipation fan  130  is arranged to face a ventilation opening  131   a  such that air blows between the image capturing element unit  106  and the main board  107 , thereby producing the heat dissipation effect on a plurality of the heat generating sources. 
     However, the ventilation opening  131   a  of the heat dissipation fan  130  is arranged at a position closest to the image capturing element unit  106  that generates more heat. 
     Detailed Description of Image Capturing Element Unit  106   
     The image capturing element unit  106  is described in detail with reference to  FIGS.  2 A and  2 B .  FIGS.  2 A and  2 B  are an exploded front perspective view and an exploded rear perspective view of the image capturing element unit  106 , respectively. 
     A movable unit  114  includes a coil unit  116  in which a coil and a Hall element for moving an image capturing element  115  are arranged and is held by a sensor holder  117 . 
     Three magnets  118  are held on a drive mechanism  113 , and the movable unit  114  is attracted to and held by the magnets  118 . 
     A ball (not illustrated) is placed in a ball holding unit  117   a  provided in the sensor holder  117  between the movable unit  114  and the drive mechanism  113 . 
     The movable unit  114  can be moved by changing the amount of energization to the coil unit  116 . Hand shake correction can be performed by moving the movable unit  114  in a direction where a shake of the main body of the digital camera  100  is canceled. 
     In the image capturing element  115 , a sensor chip (not illustrated) is bonded to an image capturing board  115   a  on which an image capturing circuit is mounted and is electrically connected to the image capturing board  115   a  by wire bonding. 
     The image capturing element  115  and the sensor holder  117  are bonded and fixed to each other with an adhesive. Elements (not illustrated)  115   b  such as a capacitor, a resistor, and a regulator of the image capturing circuit are mounted on the back of the surface of the image capturing board  115   a  where the sensor chip is attached. 
     The image capturing element unit  106  and the main board  107  are electrically connected to each other using a flexible wiring board. 
     An image capturing signal flexible wiring board  111  is provided with wiring for an image capturing signal output from the image capturing element  115  and for a control signal necessary for driving the image capturing element  115 , and the signals are transmitted to the control IC  107   a  on the main board  107 . 
     An image capturing power supply flexible wiring board  112  is a flexible wiring board that supplies power for driving the image capturing element  115 . An inter-board connector is used for connecting the image capturing board  115   a  and each of the flexible wiring boards. 
     The image capturing element  115  includes a foreign substance removal unit for removing dust adhered to the surface and is described with reference to an exploded perspective view of the image capturing element  115  in  FIG.  10   . 
     The image capturing element  115  includes an imaging unit  300 , a vibration unit  400  (also referred to as a foreign substance removal unit  400 ), and an urging member  115   i.    
     Light-shielding members  115   c  and  115   f  each have an opening corresponding to an effective area of the image capturing board  115   a.    
     An optical low-pass filter  115   d  is a known optical low-pass filter that cuts a signal in a high frequency region. 
     An image capturing element holding member  115   e  is made of a resin member having an opening corresponding to the effective area of the image capturing board  115   a , and an elastomer is integrally formed around the entire peripheral edge portion of the opening portion. 
     A cover glass  115   g  is coated with an optical coating such as infrared block coating and antireflection coating. 
     A piezoelectric element  115   h  is a known piezoelectric element and is fixed to the cover glass  115   g  by means such as a conductive adhesive. 
     The piezoelectric element  115   h  expands and contracts when a predetermined frequency voltage is applied thereto. With the expansion and contraction of piezoelectric element  115   h , flexion deformity periodically occurs in the cover glass  115   g , and thus dust and the like are shaken off from the cover glass  115   g.    
     The urging member  115   i  urges and fixes the imaging unit  300  and the vibration unit  400  described above to the image capturing board  115   a  fixed to the sensor holder  117 . 
     The urging member  115   i  and the elastomer of the image capturing element holding member  115   e  form a sealed space for preventing a foreign substance such as dust from entering in the image capturing element  115 . 
     Description of Rear View of Heat Dissipation Fan  130  and Image Capturing Element Unit  106   
       FIG.  3 A  is a perspective view illustrating a positional relationship of the heat dissipation fan  130 , the image capturing element unit  106 , and the main board  107 .  FIG.  3 B  is a cross-sectional view along an A-A line in  FIG.  3 A .  FIG.  12    is a schematic diagram illustrating a flow of air (airflow). 
       FIGS.  11 A and  11 B  are a rear view and a schematic view illustrating the heat dissipation fan  130  and the image capturing element unit  106 . 
     In  FIGS.  3 A and  3 B , the heat dissipation fan  130  is arranged between the image capturing element unit  106  and the main board  107  such that the ventilation opening  131   a  is substantially perpendicular to an image capturing optical axis. 
     Accordingly, air (airflow) passes between the image capturing element unit  106  and the main board  107  as illustrated in  FIG.  12    and thus can prevent the image capturing element unit  106 , which is the heat generating source, from becoming locally hot. 
     At the same time, the flow of air can also produce the heat dissipation effect on the main board  107 , which is one of the heat generating sources. 
     Further, the air (airflow) having passed between the image capturing element unit  106  and the main board  107  is swirled up by the bottom cover  104  as illustrated by the arrows in  FIG.  12    and is caused to circulate inside a housing. 
     The ventilation opening  131   a  does not necessarily need to be perpendicular to the image capturing optical axis. It is possible to increase the heat dissipation effect by tilting the ventilation opening  131   a  with respect to the image capturing optical axis to cause the air (airflow) to be applied more strongly to the image capturing element unit  106 . 
     Next, movement of the movable unit  114  of the image capturing element unit  106  and a positional relationship with respect to the heat dissipation fan  130  are described. The movable unit  114  can move perpendicular to the optical axis in a movement range  114   a  illustrated in  FIG.  11 B . 
     Further, a range  114   b  indicates a range in which the movable unit  114  always exists if the movable unit  114  moves. The range  114   b  is, in other words, a range in which the movable unit  114  exists even if the movable unit  114  moves to any position in the movement range  114   a.    
     Specifically, the ventilation opening  131   a  of the heat dissipation fan  130  is directed so that the air is blown to the range  114   b  in which the movable unit  114  always exists when the movable unit  114  moves. 
     An air blowing direction  131   a  is schematically illustrated in  FIG.  11 B . Since the air blowing direction  131   a  is within the range  114   b , the heat dissipation effect can be produced regardless of the position of the movable unit  114 , which is the heat generating source in the image capturing element unit  106 . 
     Further, the heat dissipation fan  130  is not physically connected to the movable unit  114 , so that the heat dissipation effect can be produced without impairing the hand shake correction function due to the movement. 
     According to the first exemplary embodiment, for example, the heat dissipation fan  130  is operated at a wind speed of 4.5 L/min. 
     The “liter per minute” (L/min) is a unit of a volumetric flow rate. The heat dissipation fan  130  incorporated in the digital camera  100  can cause the maximum achievable temperature of the image capturing element unit  106  to be lowered by 10° C. 
     Accordingly, the rise in the temperature of the heat generating source is prevented, and the digital camera  100  is less likely to reach a limit temperature at which the functions of the digital camera  100  stop due to heat generation. 
     Description of Block Diagram Illustrating Configuration Example of Digital Camera  400   
       FIG.  4    is a block diagram illustrating a configuration example of a digital camera  400  (also referred to as an image capturing apparatus  400 ) according to the present exemplary embodiment. 
     A shutter  410  is a focal-plane shutter that can freely control an exposure time of an image capturing unit  411  described below. The control is performed by a system control unit  420  described below. 
     The image capturing unit  411  is an image capturing device that has an imaging plane on which an object image (an optical image) having passed through a lens  501  is formed and outputs an electrical signal (an analog signal) photoelectrically converted from the optical image formed on the imaging plane. 
     As the image capturing unit  411 , a charge couple device (CCD) sensor or a complementary metal oxide semiconductor (CMOS) sensor is used. 
     An analog-to-digital (A/D) converter  412  is a signal conversion unit that is used to convert an analog signal output from the image capturing unit  411  into a digital signal. 
     An image processing unit  413  generates image data by performing predetermined pixel interpolation, resizing processing such as reduction, and color conversion processing on the digital signal from the A/D converter  412  or a digital signal from a memory control unit  422  described below. 
     The system control unit  420  controls the position of a diaphragm and the position of the lens  501  based on a calculation result obtained by the image processing unit  413 . 
     The image processing unit  413  further performs calculation processing using the above-described image data and through-the-lens (TTL) automatic white balance (AWB) processing based on the obtained calculation result. 
     The system control unit  420  is a control unit that includes at least one processor or circuit and controls the entire digital camera  400 . 
     The system control unit  420  executes a program stored in a nonvolatile memory  423 , which is described below, and thus realizes each processing according to the present exemplary embodiment. 
     A memory  421  is a storage unit that temporarily stores the digital signal obtained by the A/D converter  412  converting the analog signal obtained by the image capturing unit  411  and the image data generated by the image processing unit  413 . 
     The memory  421  has a storage capacity sufficient to store a predetermined number of still images, moving images and sound of a predetermined time length. 
     The memory control unit  422  is a memory control unit that controls transmission and reception of data controlled by the system control unit  420  to and from the A/D converter  412 , the image processing unit  413 , and the memory  421 . 
     The digital signal output from the A/D converter  412  is directly written to the memory  421  via the image processing unit  413  and the memory control unit  422  or only via the memory control unit  422 . 
     The nonvolatile memory  423  is an electrically erasable/recordable read-only storage unit and stores a constant, a program, and the like for operation of the system control unit  420 . 
     A system memory  424  is a readable and writable storage unit that stores a constant and a variable for the operation of the system control unit  420 , a program read from the nonvolatile memory  423 , and the like. 
     A system timer  425  is a time measurement unit that measures a time until auto power-off for turning off various display members, which are described below, is executed and also measures an exposure time. 
     The auto power-off has a function of turning off the various display members, which are described below, in a case where it is determined that a photographer has not operated the digital camera  400  in order to suppress battery consumption. 
     A power supply unit  430  includes a primary battery such as an alkaline battery and a lithium (Li) battery, a secondary battery such as a nickel-cadmium (NiCd) battery, a nickel-metal hydride (NiMH) battery and Li battery, and an alternate current (AC) adapter. 
     A power supply control unit  431  includes a circuit for detecting the power supply unit  430 , which is an electrical power source for driving the digital camera  400 , a direct current to direct current (DC-DC) converter, and a switch circuit for switching a power supply destination. 
     The power supply unit  430  detects whether the battery is installed, a type of battery, and the remaining amount of battery. 
     Further, the power supply control unit  431  controls the DC-DC converter based on the detection result and an instruction from the system control unit  420  to supply a required voltage to the supply destination at a required timing. 
     A communication terminal  440  is provided in the digital camera  400  and is electrically connected to a lens communication terminal  506  described below. 
     The communication terminal  440  is electrically connected to the lens communication terminal  506 , and thus the system control unit  420  that controls the entire digital camera  400  can communicate with a lens unit  500  described below. 
     A storage medium interface (I/F)  441  is an interface with a storage medium  600  described below. 
     An orientation detection unit  442  detects an orientation of the digital camera  400  with respect to the direction of gravity. 
     The orientation detection unit  442  can output orientation information indicating whether the image captured by the image capturing unit  411  is an image captured with the digital camera  400  held horizontally or an image captured with the digital camera  400  held vertically, based on the detected orientation. 
     The system control unit  420  can add the orientation information output from the orientation detection unit  442  to the image data. 
     As the orientation detection unit  442 , an acceleration sensor, a gyro sensor, or the like can be used. 
     In a case where the acceleration sensor or the gyro sensor is used as the orientation detection unit  442 , the orientation detection unit  442  can also detect operation of the digital camera  400  (pan, tilt, lifted, motionless, and the like). 
     An eyepiece unit  443  is a portion of the digital camera  400  where an eye (object)  700  of a photographer approaches, i.e., is proximate to the digital camera  400 . 
     An eye approach detection unit  444  is an eye approach detection sensor that detects the approach (proximity) and separation (departing) of the eye  700  to and from the eyepiece unit  443 . 
     The eye approach detection unit  444  detects whether the eye  700  has approached the eyepiece unit  443  depending on whether a light-receiving portion of an infrared proximity sensor (not illustrated) receives light. 
     After it is detected that the eye  700  has approached the eyepiece unit  443 , the system control unit  420  determines that the eyepiece unit  443  is in an eye approach state until the separation of the eye  700  from the eyepiece unit  443  is detected. 
     After it is detected that the eye  700  has separated from the eyepiece unit  443 , the system control unit  420  determines that the eyepiece unit  443  is in a non-eye-approach state until the approach of the eye  700  is detected. 
     The infrared proximity sensor is merely an example, and another sensor can be adopted to the eye approach detection unit  444  as long as the sensor can detect the approach of an eye or an object and determine that the eye is proximate to the eyepiece unit  443 . 
     The above-described memory  421  also serves as a memory (a video memory) for image display. 
     The digital signal and the image data written to the memory  421  are displayed by a rear surface display unit  450  and an electronic viewfinder (EVF)  451  via the memory control unit  422 . 
     The rear surface display unit  450  performs display corresponding to the signal from the memory control unit  422 . 
     In a case where the eye approach detection unit  444  detects the approach of the eye  700 , the EVF  451  performs display corresponding to the signal from the memory control unit  422 . 
     The digital signal that is obtained by the A/D converter  412  performing A/D conversion on the analog signal generated in the image capturing unit  411  and stored in the memory  421  is sequentially transmitted to the rear surface display unit  450  or the EVF  451  and displayed thereon. 
     Accordingly, live-view imaging display, which is real-time display, can be performed. 
     The system control unit  420  switches display (a display state)/non-display (a non-display state) of each of the rear surface display unit  450  and the EVF  451  in response to a state detected by the above-described eye approach detection unit  444 . 
     In the non-eye-approach state, the rear surface display unit  450  performs display, and the EVF  451  is brought into the non-display state. 
     On the other hand, in the eye approach state, the EVF  451  performs display, and the rear surface display unit  450  is brought into the non-display state. 
     An operation unit  460  includes various operation members as an input unit for receiving an operation from a user. 
     The operation unit  460  includes various operation members (a mode changeover switch  461 , a shutter button  462 , a first shutter switch  463 , a second shutter switch  464 , a touch panel  465 , and a power supply switch  466 ), which are described below. 
     Further, the operation unit  460  is an operation unit for inputting various operation instructions to the system control unit  420 . 
     The mode changeover switch  461  is an image capturing mode switching unit for switching an operation mode of the system control unit  420  to any of a still image mode and a moving image mode. 
     Image capturing modes included in the still image mode are an auto image capturing mode, an auto scene determination mode, and a manual image capturing mode. 
     The still image mode further includes an aperture priority (Av) mode (Av mode), a shutter speed priority mode (Time-value (Tv) mode or Tv mode), and a programmed automatic exposure (AE) mode (P mode) as the image capturing modes. 
     Similarly, the moving image mode may include a plurality of image capturing modes. 
     The shutter button  462  is an image capturing start unit for a photographer to issue an image capturing preparation instruction and an image capturing instruction and includes the first shutter switch  463  and the second shutter switch  464 . 
     The first shutter switch  463  is turned ON when the shutter button  462  provided in the digital camera  400  is in the middle of operation, i.e., the shutter button  462  is half-pressed (the image capturing preparation instruction, and first shutter switch  463  generates a first shutter switch signal SW 1 . 
     An image capturing preparation operation such as autofocus (AF) processing, AE processing, and AWB processing is started in response to the first shutter switch signal SW 1 . 
     The second shutter switch  464  is turned ON upon completion of the operation of the shutter button  462 , i.e., when the shutter button  462  is fully pressed (the image capturing instruction), and the second shutter switch  464  generates a second shutter switch signal SW 2 . 
     The system control unit  420  reads out the analog signal from the image capturing unit  411  and controls signal conversion processing to be performed by the A/D converter  412  and the image processing unit  413 , based on the second shutter switch signal SW 2 . 
     Further, the system control unit  420  starts an image capturing processing operation up to writing the image data temporarily stored in the memory  421  to the storage medium  600  described below. 
     The touch panel  465  is a device that detects a touch or drag operation performed by a photographer. 
     The touch panel  465  is integrated with the rear surface display unit  450 , and the photographer can operate the touch panel  465  by touching the display portion of the rear surface display unit  450  with a finger. 
     The power supply switch  466  is a switch for switching ON/OFF of the power supply. The power supply control unit  431  controls the power supply from the power supply unit  430  by a switching operation on the power supply switch  466 . 
     A heat dissipation fan  470  is controlled by the system control unit  420  and cools the heat generating source inside the digital camera  400 . 
     The lens unit  500  is an interchangeable lens that can be attached to and detached from the digital camera  400 . 
     The lens  501  is a lens group that generates an optical image (an object image) from object light reflected by an object and includes a plurality of lenses, but one lens is illustrated in  FIG.  4    for the sake of simplification. 
     The lens communication terminal  506  is a communication terminal for the lens unit  500  to communicate with the digital camera  400 . 
     When the lens communication terminal  506  is electrically connected to the communication terminal  440 , the lens unit  500  can communicate with the system control unit  420  that controls the entire digital camera  400 , as described above. 
     Accordingly, the system control unit  420  can communicate with a lens system control circuit  505  and a diaphragm drive circuit  504  and control the position of a diaphragm  503  and the focus state of a real image by shifting the lens  501 . 
     The storage medium  600  is a storage medium such as a memory card that can be attached to and detached from the digital camera  400  and stores a captured image. 
     Examples of the storage medium  600  include a secure digital (SD) card, an of memory that retains data in the absence of a power supply such as a FLASH® memory, and a hard disk. 
     As described above, the image capturing apparatus  400  according to the present exemplary embodiment includes the heat dissipation fan  130  (i.e., a fan) that generates an airflow for cooling the image capturing element unit  106  and the foreign substance removal unit  400  that removes a foreign substance adhered to an exposed surface of the image capturing element on the object side of the imaging plane. 
     The image capturing apparatus  400  according to the present exemplary embodiment includes the system control unit  420  (i.e., a control unit) that causes the foreign substance removal unit  400  to remove a foreign substance adhered to the exposed surface after the heat dissipation fan  130  is driven. 
     The ventilation opening  131   a  of the heat dissipation fan  130  faces an area sandwiched between the image capturing element unit  106  (i.e., an image capturing element board) on which the image capturing element is mounted and the main board  107  (i.e., a control board) on which the control IC  107   a  (i.e., a control circuit) for controlling the image capturing element is mounted. 
     Description of Flowchart Illustrating First Operation Timing 
       FIG.  5    is a flowchart illustrating first operation timing of foreign substance removal in the image capturing apparatus  400  according to the present disclosure. 
     In step S 101 , in a case where the shutter button  462  is pressed in a state in which the mode changeover switch  461  is set to the moving image mode, moving image capturing is started. 
     If the moving image capturing is started, the temperature of the image capturing element  115  rises as time passes. 
     In step S 102 , the temperature of the image capturing element  115  is monitored to determine whether the temperature of the image capturing element  115  has reached a predetermined value set in advance so that the temperature of the image capturing element  115  does not exceed the operation guarantee temperature of the image capturing element  115 . 
     In step S 102 , in a case where it is determined that the temperature of the image capturing element  115  exceeds the predetermined value (YES in step S 102 ), the processing proceeds to step S 103 , and driving of the heat dissipation fan  130  is started. In a case where it is determined that the temperature of the image capturing element  115  does not exceed the predetermined value (NO in step S 102 ), the processing proceeds to step S 104 . 
     In step S 103 , the heat dissipation fan  130  is driven, and the air (airflow) inside the image capturing apparatus  400  circulates thereby, and the image capturing element  115  is cooled by the circulation of the air. At the same time, dust inside the image capturing apparatus  400  is also stirred up and adheres to the cover glass  115   g  of the image capturing element  115  to some extent. 
     In step S 104 , it is determined whether the moving image capturing is completed. In a case where the moving image capturing is completed (YES in step S 104 ), the processing proceeds to step S 105 , whereas in a case where the moving image is still in process (NO in step S 104 ), the processing returns to step S 102 , and the processing in steps S 102  to S 104  is repeated. 
     In step S 105 , it is determined whether the heat dissipation fan  130  has a drive history. In a case where the heat dissipation fan  130  has the drive history (YES in step S 105 ), the processing proceeds to step S 106 , whereas in a case where the heat dissipation fan  130  does not have the drive history (NO in step S 105 ), the processing in the present flowchart is terminated. 
     In step S 106 , the temperature of the image capturing element  115  is monitored to determine whether the temperature of the image capturing element  115  is the predetermined value set in advance or less, that is, whether the temperature of the image capturing element  115  is sufficiently lowered. 
     In step S 106 , in a case where it is determined that the temperature of the image capturing element  115  is the predetermined value or less (YES in step S 106 ), the processing proceeds to step S 107 , and driving of the heat dissipation fan  130  is stopped. 
     In step S 108 , the system control unit  420  applies the predetermined frequency voltage to the piezoelectric element  115   h  to operate the vibration unit  400 . 
     Accordingly, the dust adhered to the cover glass  115   g  is shaken off, and the image capturing apparatus  400  can prepare for the next image capturing. 
     In the present flowchart, the foreign substance removal unit  400  is operated after the heat dissipation fan  130  is stopped, but the foreign substance removal unit  400  may be operated in a state in which the heat dissipation fan  130  is not stopped after the moving image capturing. 
     At the first operation timing, the foreign substance removal unit  400  is operated after the moving image capturing is stopped. In addition, the foreign substance removal unit  400  is operated after the heat dissipation fan  130  is stopped. 
     Description of Flowchart Illustrating Second Operation Timing 
       FIG.  6    is a flowchart illustrating operation timing different from the operation timing of the foreign substance removal illustrated in  FIG.  5    in the image capturing apparatus  400  according to the present disclosure. 
     Processing in steps S 201  to S 207  is the same as the processing in steps S 101  to S 107  in the flowchart of the operation timing in  FIG.  5   , and thus the description thereof is omitted. 
     In step S 208 , if the shutter button  462  is pressed again after the moving image capturing is stopped (moving image capturing detection is turned ON), the processing proceeds to step S 209 . In step S 209 , it is determined whether the heat dissipation fan  130  has the drive history. 
     In a case where the heat dissipation fan  130  has the drive history (YES in step S 209 ), the processing proceeds to step S 210 , whereas in a case where the heat dissipation fan  130  does not have the drive history (NO in step S 209 ), the processing proceeds to step S 211 . 
     In step S 210 , the system control unit  420  applies the predetermined frequency voltage to the piezoelectric element  115   h  to operate the vibration unit  400 . 
     Accordingly, the dust adhered to the cover glass  115   g  is shaken off. 
     After the foreign substance removal unit  400  is operated, the processing proceeds to step S 211 . Then in step S 211 , the moving image capturing is started. 
     In the flowchart of the operation timing in  FIG.  5   , the foreign substance removal unit  400  is operated after the moving image capturing operation is completed. 
     However, it can be assumed that some vibration or impact is applied to the image capturing apparatus during a period after the operation of the foreign substance removal unit  400  until the start of the next moving image capturing, and the dust inside the image capturing apparatus is stirred up thereby and adheres again to the cover glass  115   g.    
     According to the operation timing in the present flowchart, the foreign substance removal unit  400  is operated immediately before the moving image capturing, and thus it is possible to reduce a risk of deterioration in image quality caused by the dust adhered to the cover glass  115   g.    
     At the second operation timing, the operation of the foreign substance removal unit  400  is started upon detecting an instruction to start the moving image capturing. 
     Description of Flowchart Illustrating Third Operation Timing 
       FIG.  7    is a flowchart illustrating operation timing different from the operation timings of the foreign substance removal illustrated in  FIGS.  5  and  6    in the image capturing apparatus  400  according to the present disclosure. 
     Processing in steps S 301  to S 307  is the same as the processing in steps S 101  to S 107  in the flowchart of the operation timing in  FIG.  5   , and thus the description thereof is omitted. 
     In step S 308 , if the moving image mode is switched to the still image mode by the mode changeover switch  461 , the processing proceeds to step S 309 . Then in step S 309 , it is determined whether the heat dissipation fan  130  has the drive history. 
     In a case where the heat dissipation fan  130  has the drive history (YES in step S 309 ), the processing proceeds to step S 310 , whereas in a case where the heat dissipation fan  130  does not have the drive history (NO in step S 309 ), the processing in the present flowchart is terminated. 
     In step S 310 , the system control unit  420  applies the predetermined frequency voltage to the piezoelectric element  115   h  to operate the vibration unit  400 . 
     Accordingly, the dust adhered to the cover glass  115   g  is shaken off, and the image capturing apparatus  400  can prepare for still image capturing. 
     The dust adhered to the cover glass  115   g  greatly affects image quality in still image capturing compared to moving image capturing. Thus, it is very effective to remove the dust from the cover glass  115   g  before still image capturing. 
     At the third operation timing, the operation of the foreign substance removal unit  400  is started upon detecting an instruction to start the still image capturing. 
     Description of Flowchart Illustrating Fourth Operation Timing 
       FIG.  8    is a flowchart illustrating operation timing different from the operation timings of the foreign substance removal illustrated in  FIGS.  5 ,  6 , and  7    in the image capturing apparatus  400  according to the present disclosure. 
     Processing in steps S 401  to S 407  is the same as the processing in steps S 101  to S 107  in the flowchart of the operation timing illustrated in  FIG.  5   , and thus the description thereof is omitted. 
     In step S 408 , the moving image mode is switched to the still image mode by the mode changeover switch  461 . 
     Subsequently, in step S 409 , if the first shutter switch  463  of the shutter button  462  is pressed, then in step S 410 , it is determined whether the heat dissipation fan  130  has the drive history. 
     In a case where the heat dissipation fan  130  has the drive history (YES in step S 410 ), the processing proceeds to step S 411 , whereas in a case where the heat dissipation fan  130  does not have the drive history (NO in step S 410 ), the processing proceeds to step S 412 . 
     In step S 411 , the system control unit  420  applies the predetermined frequency voltage to the piezoelectric element  115   h  to operate the vibration unit  400 . 
     Accordingly, the dust adhered to the cover glass  115   g  is shaken off. 
     In step S 412 , if the second shutter switch  464  is pressed, the processing proceeds to step S 413 . In step S 413 , the still image capturing is started. 
     In the flowchart of the operation timing in  FIG.  7   , foreign substance removal is performed at the timing of switching to the still image mode. 
     However, it can be assumed that some vibration or impact is applied to the image capturing apparatus during a period after the operation of the foreign substance removal unit  400  until the start of the still image capturing, and the dust inside the image capturing apparatus is stirred up thereby and adheres again to the cover glass  115   g.    
     According to the operation timing in the present flowchart, the foreign substance removal unit  400  is operated immediately before the still image capturing, and thus it is possible to reduce a risk of deterioration in image quality caused by the dust adhered to the cover glass  115   g.    
     At the fourth operation timing, the operation of the foreign substance removal unit  400  is started upon detecting an instruction to start the still image capturing. 
     Description of Flowchart Illustrating Fifth Operation Timing 
       FIG.  9    is a flowchart illustrating operation timing different from the operation timings of the foreign substance removal illustrated in  FIGS.  5 ,  6 ,  7  and  8    in the image capturing apparatus  400  according to the present disclosure. 
     Processing in steps S 501  to S 508  is the same as the processing in steps S 101  to S 108  in the flowchart of the operation timing in  FIG.  5   , and thus the description thereof is omitted. 
     In step S 509 , if the moving image mode is switched to the still image mode by the mode changeover switch  461 , the processing proceeds to step S 510 . In step S 510 , it is determined whether the heat dissipation fan  130  has the drive history. 
     In a case where the heat dissipation fan  130  has the drive history (YES in step S 510 ), the processing proceeds to step S 511 , whereas in a case where the heat dissipation fan  130  does not have the drive history (NO in step S 510 ), the processing in the present flowchart is terminated. 
     In step S 511 , the system control unit  420  applies the predetermined frequency voltage to the piezoelectric element  115   h  to operate the vibration unit  400 . 
     In the present flowchart, the foreign substance removal is performed at both of the timing after the moving image capturing is completed and the timing of switching to the still image mode respectively. 
     Accordingly, it is possible to remove the dust adhered again to the cover glass  115   g  due to some vibration or impact applied to the image capturing apparatus during a period from when the foreign substance removal is performed after the moving image capturing until when the moving image mode is switched to the still image mode. 
     The operation of the foreign substance removal unit  400  that is performed after switching to the still image mode may be performed after pressing of the first shutter switch  463  described with reference to  FIG.  8   . 
     At the fifth operation timing, the foreign substance removal unit  400  is operated at the timing after stopping the moving image capturing and at the timing after switching to the still image mode and before starting the still image capturing. 
     The exemplary embodiments are described above, but the descriptions of the above-described exemplary embodiments and modifications are examples for describing the technique according to the present disclosure. 
     The technique according to the present disclosure can be implemented by appropriately changing or combining the above-described exemplary embodiments and modifications without departing from the spirit and the scope of the present disclosure. 
     Specifically, the present disclosure is not limited to a digital camera and can be widely applied to an electronic device and an image capturing apparatus having a moving image capturing function such as a video camera and a network camera. 
     The technique according to the present disclosure is applied to an electronic device and an image capturing system. 
     According to an aspect of the present invention, a fan can efficiently remove a foreign substance such as dust adhered to an imaging surface at more effective timings. 
     Embodiments of the present disclosure can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described Embodiments and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described Embodiments, and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described Embodiments and/or controlling the one or more circuits to perform the functions of one or more of the above-described Embodiments. The computer may include one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read-only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc™ (BD)), a flash memory device, a memory card, and the like. 
     While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2021-185818, filed Nov. 15, 2021, which is hereby incorporated by reference herein in its entirety.