Abstract:
A digital camera includes a first imaging section for acquiring subject image data, a movable mirror for guiding the light beam of the subject to a finder optical system, and a second imaging section for capturing the subject image data in the finder optical system. In this structure, the image acquired by the first imaging section and the image acquired by the second imaging section are switched and selectively displayed depending on the movement of the movable mirror. For example, the digital camera can be configured such that the first imaging section is used to acquire a shot image and the second imaging section is used to acquire a live image.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2005-148170, filed on May 20, 2005, the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a digital camera. More particularly, the present invention relates to the improvement of a digital camera capable of displaying on a display screen both an image being viewed and an image being shot.  
         [0004]     2. Description of the Related Art  
         [0005]     Digital cameras are commonly known, which form an optical image of a subject on an image pickup device from light coming from the subject and passing through a photographing optical system, photoelectrically convert the optical image into electric image signals through the image pickup device, and display the resulting image on the screen of an image display device, such as an LCD monitor, based on the electric image signals.  
         [0006]     As an example of such a camera displaying a subject image, a camera is known in which a movable mirror is formed as a half mirror to enable live-view display (for example, see Japanese Patent Laid-Open No. 2001-186401).  
         [0007]     A camera is also known in which a half mirror is arranged in a finder optical system to guide a light beam of a subject to an image pickup device for live-view display (for example, see Japanese Patent Laid-Open No. 2000-165730).  
         [0008]     The cameras described in Japanese Patent Laid-Open Nos. 2001-186401 and 2000-165730 are to display a live image during normal observation and a shot image at the time of shooting. Therefore, when sequential shootings are performed with these cameras, the live image and the shot image are frequently switched.  
       BRIEF SUMMARY OF THE INVENTION  
       [0009]     The digital camera of the present invention has a first imaging section for acquiring subject image data, a movable mirror for guiding a light beam of a subject to a finder optical system, and a second imaging section for capturing the subject image data in the finder optical system. The images acquired by the first and second imaging sections are switched and displayed in different forms distinguishable from each other in response to the movement of the movable mirror.  
         [0010]     For example, the digital camera can be configured such that the first imaging section is used to acquire a shot image and the second imaging section is used to acquire a live image. Thus, the switching of the images is synchronized with the movement of the movable mirror, and this makes it easy for a user to distinguish the two images.  
         [0011]     When a mat screen is provided in the finder optical system, the second imaging section can preferably be configured to capture an image formed on the mat screen.  
         [0012]     The second imaging section can also preferably be configured to acquire a focus frame on the mat screen or display information provided in the finder optical system together with the subject image data. In this case, the focus frame or the display information appear in the image acquired by the second imaging section, and this makes it easy for the user to distinguish the image from that acquired by the first imaging section.  
         [0013]     As a specific structural example of the present invention, the digital camera comprises: a finder optical system including a plurality of mirrors for observation of a subject; a first imaging section for converting a light beam, coming from a subject through a photographing lens, into electric signals; a movable mirror capable of being moved in or out of the imaging optical path of the first imaging section so that, when located in the imaging optical path, it will guide the light beam of the subject to the finder optical system; a display section for displaying image data acquired by the first imaging section; a second imaging section, different from the first imaging section, for converting the light beam of the subject guided to the finder optical system into electric signals; and a control section for switching over between the image data acquired by the first imaging section and the image data acquired by the second imaging section in response to the movement of the movable mirror to selectively display either of the image data on the display section. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0014]     These and other features, aspects, and advantages of the apparatus and methods of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:  
         [0015]      FIG. 1  is an outline perspective view showing the structure of a single-lens reflex digital camera to which an imaging device according to a first embodiment of the present invention is applied;  
         [0016]      FIG. 2  is a perspective view showing the structure of a finder optical system of the camera according to the first embodiment of the present invention;  
         [0017]      FIG. 3  is a block diagram showing a system configuration of the camera according to the first embodiment of the present invention;  
         [0018]      FIG. 4  is a timing chart for explaining the operation of the camera in a live view mode according to the first embodiment of the present invention;  
         [0019]      FIG. 5  is a timing chart for explaining the operation of the camera in a finder mode according to the first embodiment of the present invention;  
         [0020]      FIG. 6A  shows an example of a focusing screen  56  to explain an image observed in a viewfinder  43  and an image displayed on an LCD monitor  36 ;  
         [0021]      FIG. 6B  shows an example of a series of display images on the LCD monitor  36  to explain the image observed in the viewfinder  43  and the image displayed on the LCD monitor  36 ;  
         [0022]      FIG. 7  is an outline perspective view showing the structure of a single-lens reflex digital camera to which an imaging device according to a second embodiment of the present invention is applied;  
         [0023]      FIG. 8  is a perspective view showing the structure of a finder optical system of the camera according to the second embodiment of the present invention;  
         [0024]      FIG. 9  is a perspective view showing a drive mechanism of a fourth reflection mirror  103  according to the second embodiment of the present invention, in which an eyepiece shutter is open for observation of a subject;  
         [0025]      FIG. 10  is a perspective view showing the drive mechanism of the fourth reflection mirror  103  according to the second embodiment of the present invention, in which the eyepiece shutter is closed;  
         [0026]      FIG. 11  is a partially cutaway view showing an F/L mode switching lever  101  in the second embodiment of the present invention;  
         [0027]      FIG. 12  is a block diagram showing a system configuration of the camera according to the second embodiment of the present invention;  
         [0028]      FIG. 13A  shows an example of an image captured by an imaging device  61  for image display and displayed on the LCD monitor  36  according to the second embodiment of the present invention; and  
         [0029]      FIG. 13B  shows an example of a series of display images on the LCD monitor  36  according to the second embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]     Preferred embodiments of the invention are described below with reference to the accompanying drawings.  
       First Embodiment  
       [0031]      FIG. 1  is an outline perspective view showing the structure of a single-lens reflex digital camera to which an imaging device according to a first embodiment of the present invention is applied.  
         [0032]     In  FIG. 1 , the single-lens reflex digital camera (hereinafter simply called the “camera”)  1  consists principally of an interchangeable lens barrel  10  and a camera body  30 . In this structure, a desired lens barrel  10  is removably mounted on the front of the camera body  30 .  
         [0033]     A shutter button  31 , a mode dial  32 , a power switch lever  33 , a control dial  34 , etc. are provided on the top face of the camera body  30 .  
         [0034]     The shutter button  31  is to perform shooting preparation and exposure operations. The shutter button  31  consists of two-step switches, namely a first shutter release switch and a second shutter release switch. When the shutter button  31  is pressed halfway, the first shutter release switch is turned on to perform shooting preparation operations, such as photometering and distance measuring. Then, when the shutter button  31  is pressed fully, the second shutter release switch is turned on to make an exposure.  
         [0035]     The mode dial  32  is an operation part for allowing a user to set a shooting mode upon shooting. The mode dial  32  is rotated in a predetermined direction to set a shooting mode upon shooting. In the first embodiment, the mode dial  32  also has a function for switching over the image display in an LCD monitor between a finder mode and a live view mode as described in detail later. The power switch lever  33  is an operation part for allowing the user to power on or off the camera  1 . When the power switch lever  33  is moved, the main power supply of the camera  1  is turned on or off.  
         [0036]     The control dial  34  is an operation part for allowing the user to set shooting information. The user can set various shooting conditions upon shooting by operating the control dial  34 .  
         [0037]     Further, an LCD monitor  36  for displaying a shooting image, a menu, etc., a playback button  37 , a menu button  38 , an arrow pad  40 , an OK button  41 , a viewfinder  43  in an eyepiece optical system, etc. are arranged on the back face of the camera body  30 .  
         [0038]     The playback button  37  is to switch over the camera  1  to a playback mode capable of playing back a JPEG image file recorded in a flash ROM  84  or on a recording medium  85  as described in detail later. The menu button  38  is to display a menu screen on the LCD monitor  36 . The menu screen consists of menu items in a multi-layered structure. The user can select a desired menu item using the arrow pad  40  and confirm the selected item by pressing the OK button  41 .  
         [0039]      FIG. 2  is a perspective view showing the structure of a finder optical system of the camera according to the first embodiment of the present invention.  
         [0040]     A finder optical system  50  consists principally of a plurality of mirrors for guiding a light beam coming from a subject and passing through a photographing lens  11  in the lens barrel  10  to an eyepiece lens  57  constituting part of the viewfinder  43 , a focusing screen (matt screen)  56 , and the eyepiece lens  57 . The plurality of mirrors include a first reflection mirror  51 , a second reflection mirror  52 , a third reflection mirror  53 , and a fourth reflection mirror  54 .  
         [0041]     The first reflection mirror  51  is configured to be rotatable about an axis  51   a  in both directions indicated by arrow A in  FIG. 2 . Part of the first reflection mirror  51  is formed into a half mirror for an AF sensor unit to be described later. As shown in  FIG. 2 , when a photographer is looking into the viewfinder  43  ( FIG. 1 ) to observe a subject before shooting, the first reflection mirror  51  reflects a light beam incoming from the photographing lens  11  toward the second reflection mirror  52 , at an angle of approximately 90° with respect to the optical axis of the photographing lens  11 , that is, to the right in the camera body  30  as viewed from the lens barrel  10 . Then, upon shooting, the first reflection mirror  51  is withdrawn out of the photographing optical path so that the light beam from the subject will be guided to an image pickup device (not shown) located behind the first reflection mirror  51 .  
         [0042]     The light beam reflected on the reflection surface of the first reflection mirror  51  is incident on the second reflection mirror  52  through the focusing screen  56 . The second reflection mirror  52  is arranged in the optical axis of the reflected light from the first reflection mirror  51  and with its reflection surface tilted at a predetermined angle with respect to the optical axis of the reflected light from the first reflection mirror  51 . In the first embodiment, the light beam reflected from the first reflection mirror  51  and incident on the second reflection mirror  52  is reflected upward in the camera body  30  at an angle of approximately 90° with respect to the optical axis of the reflected light from the first reflection mirror  51 .  
         [0043]     The light beam reflected on the reflection surface of the second reflection mirror  52  is incident on the third reflection mirror  53  arranged in the reflective optical axis of the reflection surface of the second reflection mirror  52  and with its reflection surface tilted at a predetermined angle with respect to the reflective optical axis of the reflection surface of the second reflection mirror  52 . In the first embodiment, the light beam reflected from the second reflection mirror  52  and incident on the third reflection mirror  53  is reflected on the reflection surface of the third reflection mirror  53  at an angle of approximately 90° with respect to the reflective optical axis of the reflection surface of the second reflection mirror  52  in a direction opposite to the reflective direction of the reflection surface of the first reflection mirror  51 . In other words, the light beam reflected from the reflection surface of the second reflection mirror  52  is reflected on the reflection surface of the third reflection mirror  53  to the left in the camera body  30 . To sum up, the light beam reflected on the reflection surface of the first reflection mirror  51  is guided through the second and third reflection mirrors  52  and  53  as if it is turned back, and directed toward the fourth reflection mirror  54  because the reflective optical axis of the reflection surface of the third reflection mirror  53  is almost parallel to that of first reflection mirror  51 .  
         [0044]     The light beam reflected on the reflection surface of the third reflection mirror  53  is incident on the fourth reflection mirror  54  arranged in the reflective optical axis of the reflection surface of the third reflection mirror  53  and with its reflection surface tilted at a predetermined angle with respect to the reflective optical axis of the reflection surface of the third reflection mirror  53 . Then, the light beam reflected from third reflection mirror  53  and incident on the fourth reflection mirror  54  is reflected on the reflection surface of the fourth reflection mirror  54  at an angle of approximately 90° with respect to the reflective optical axis of the reflected light from the third reflection mirror  53 . In other words, the light beam reflected from the reflection surface of the fourth reflection mirror  54  is incident on the eyepiece lens  57  arranged on the reflective optical axis of the reflection surface of the fourth reflection mirror  54 .  
         [0045]     The focusing screen  56  has a diffusing surface for diffusing the light beam incident on it to form an optical image from the light beam incident in the finder optical system  50 . The focusing screen  56  is arranged in a position optically equivalent to the imaging plane of an image pickup device  67  for capturing an image upon shooting as described later.  
         [0046]     The second reflection mirror  52  and the fourth reflection mirror  54  are half mirrors. A photometric sensor  63  for measuring the brightness of the subject and a set of LEDs  64  for focused indication are arranged on the backside of the reflection surface of the second reflection mirror  52 . The set of LEDs  64  is to cause a superimpose display to indicate where a focusing point is located on the screen in the viewfinder or the LCD monitor  36 . On the other hand, an imaging lens  60  and an image pickup device  61  for producing a display image are provided on the backside of the reflection surface of the fourth reflection mirror  54 . The image pickup device  61  for producing a display image (hereinafter simply called “for image display”) is to be formed an image relayed from the image formed on the focusing screen  56  on it through the imaging lens  60 . Therefore, the image formed on the image pickup device  61  for image display is the same as that observed by a photographer&#39;s eye  58  except that the image formed on the image pickup device  61  is reversed left to right.  
         [0047]     The light beam of the subject from the photographing lens  11  is guided to the eyepiece lens  57  through the first to fourth reflection mirrors  51 - 54  so that the image in the viewfinder  43  will be an erect-unreversed image. Thus, the subject image formed on the focusing screen  56  can be observed by the photographer&#39;s eye through the eyepiece lens  57  (viewfinder  43 ).  
         [0048]     In the first embodiment, the first reflection mirror  51 , the second reflection mirror  52 , the third reflection mirror  53 , and the fourth reflection mirror  54  are all arranged to reflect the incident light beam at an angle of approximately 90°, but the present invention is not limited to this arrangement.  
         [0049]      FIG. 3  is a block diagram showing a system configuration of the camera according to the first embodiment of the present invention.  
         [0050]     In  FIG. 3 , the lens barrel  10  is removably mounted on the camera body  30  through a mount, not shown, provided on the front face of the camera body  30 . The lens barrel  10  includes the photographing lens  11 , an aperture  12 , a lens drive mechanism  13 , an aperture drive mechanism  14 , and a lens control microcomputer (hereinafter abbreviated as “L μcom”)  15 .  
         [0051]     The photographing lens  11  is driven along its optical axis by a DC motor (not shown) provided in the lens drive mechanism  13 . The aperture  12  is driven by a stepping motor (not shown) provided in the aperture drive mechanism  14 . The L μcom  15  controls each component in the lens barrel  10 , such as the lens drive mechanism  13  and the aperture drive mechanism  14 . The L μcom  15  is electrically connected to a body control microcomputer (hereinafter abbreviated as “B μcom”)  80  to be described later through a communication connector  20  so that it is controlled in accordance with instructions from the B μcom  80 .  
         [0052]     The camera body  30  is configured as follows.  
         [0053]     A light beam from a subject, not shown, passing through the photographing lens  11  and the aperture  12  in the lens barrel  10  is reflected by the first reflection mirror  51  as a movable mirror and is incident on the focusing screen  56 . Then, the light beam is guided to the eyepiece lens  57  through the second to fourth reflection mirrors  52 - 54  (see  FIG. 2 ) constituting part of the finder optical system  50  together with the first reflection mirror  51 . On the other hand, part of the light beam from the subject passes through the half mirror portion of the first reflection mirror  51 , is reflected by a sub-mirror  70  movable independently of the first reflection mirror  51 , and is guided to an AF sensor unit  71  for automatic distance measurement. In  FIG. 3 , although the first reflection mirror  51  is shown separately from the second to fourth reflection mirrors, it constitutes part of the finder optical system  50  together with the second to fourth reflection mirrors.  
         [0054]     A focal-plane type shutter  66  and the image pickup device  67  for capturing an image upon shooting (hereinafter simply called “for image capturing”) are provided behind the first reflection mirror  51  along the optical axis. The image pickup device  67  for image capturing is a photoelectric converter in an imaging optical system, such as a CCD, for photoelectrical conversion of light from a subject passing through the optical system to produce a subject image. In other words, when the first reflection mirror  51  is withdrawn out of the optical path, the light beam passing through the photographing lens  11  and the aperture  12  forms an image on the imaging plane of the image pickup device  67  for image capturing.  
         [0055]     Further, as mentioned above, the finder optical system  50  is configured such that the photometric sensor  63  and the set of LEDs  64  for focused indication are arranged near the second reflection mirror  52 , and the image pickup device  61  for image display is arranged near the fourth reflection mirror  54 . The image pickup device  61  for image display and the image pickup device  67  for image capturing are connected to an image processing controller  82  for image processing through an interface circuit  81 . The LCD monitor  36  is also connected to the image processing controller  82 . An SDRAM  83 , the flash memory  84 , the recording medium  85 , etc. as memory areas are further connected to the image processing controller  82 . The LCD monitor  36  and these memory areas are configured to allow the camera to provide an electronic recording/display function as well as an electronic imaging function.  
         [0056]     The recording medium  85  is an external recording medium such as one of various types of memory cards removably inserted into the camera body  30  through a camera interface, not shown, or an external hard disk drive (HDD).  
         [0057]     The image processing controller  82  is connected to the B μcom  80  for controlling each component of the camera body  30 . The photometric sensor  63  through a photometer circuit  87 , an AF sensor drive circuit  72 , a mirror drive mechanism  73 , a shutter charge mechanism  75 , a shutter control circuit  76 , and a nonvolatile memory (EEPROM)  88  are also connected to the B μcom  80 . An LCD control panel  90  for displaying the operating state of the camera, a camera operating-switch part (SW)  91 , and a battery  93  through a power supply circuit  92  are further connected to the B μcom  80 . The LCD control panel  90  is to provide a display screen to the photographer to show the operating state of the camera.  
         [0058]     The B μcom  80  and the L μcom  15  are electrically connected through the communication connector  20  when the lens barrel  10  is mounted on the camera body  30 . The L μcom  15  cooperates dependently with the B μcom  80  to operate the digital camera.  
         [0059]     The AF sensor drive circuit  72  is to control the drive of the AF sensor unit  71 , and the mirror drive mechanism  73  is to control the drive of the first reflection mirror  51 . The shutter charge mechanism  75  is to charge a spring for driving front and rear curtains, not shown, constituting the shutter  66 . The shutter control circuit  76  not only controls the traveling of the front and rear curtains of the shutter  66 , but also exchanges with the B μcom  80  a signal for controlling the opening/closing of the shutter and a signal synchronizing with the firing of an electronic flash. The photometer circuit  87  performs photometric processing based on an electric signal from the photometric sensor  63 .  
         [0060]     The nonvolatile memory  88  is a memory storing control parameters necessary for control of the camera as a storage area other than the SDRAM  83 , the flash memory  84 , and the recording medium  85 . The nonvolatile memory  88  is provided accessible from the B μcom  80 .  
         [0061]     The LCD control panel  90  is to provide a display screen to the photographer to show the operating state of the camera. The camera operating-switch part  91  is a group of switches including operation buttons necessary to operate the camera such as the shutter release switches, a mode change switch, a power switch, etc. The second shutter release switch in the shutter release switches is not only to instruct shooting but also to switch the position of the first reflection mirror  51  between the inside and outside of the shooting optical path. The mode change switch is to switch over between the shooting mode and an image display mode. The power supply circuit  92  is provided for converting the voltage of the battery  93  as a power source and supplying a voltage necessary for each circuit unit of the camera system.  
         [0062]     The following describes the basic shooting operation of the camera according to the first embodiment of the present invention with reference to timing charts of  FIGS. 4 and 5 .  
         [0063]      FIG. 4  is a timing chart for explaining the operation of the camera in the live view mode according to the first embodiment of the present invention.  FIG. 5  is a timing chart for explaining the operation of the camera in the finder mode according to the first embodiment of the present invention. In the timing charts of  FIGS. 4 and 5 , AE denotes automatic exposure, AF is auto focus, EXP is an actual exposure, MU and MD are the withdrawal and recovery of the first reflection mirror  51 , SC is shutter charge, E 1  is exposure information, C is image capturing (imaging), P is image processing, P 1  is an image captured by the image pickup device  67  for image capturing, and D 1  is an image captured by the image pickup device  61  for image display, respectively.  
         [0064]     The shooting operation in the live view mode will first be described.  
         [0065]     When the power switch lever  33  is operated to power on the camera  1 , the photometric sensor  63  and the AF sensor unit  71  repeat an AE and AF sequence at predetermined intervals. If the camera  1  is set in the finder mode, then the exposure information is displayed on the LCD monitor  36  provided on the back face of the camera body  30 . Then, when the mode dial  32  is operated at predetermined timing to switch over to the live view mode, the image pickup device  61  for image display starts operating so that a captured image will be processed and displayed on the LCD monitor  36 . After that, this sequence of operations is repeated.  
         [0066]     Then, when the shutter button  31  is pressed halfway to turn on the first shutter release switch (1RSW), the camera  1  starts the shooting preparation operation. In other words, the photographing lens  11  is driven to focus on the subject. When the photographing lens  11  comes to the focus range, one of the LEDs  64  for focused indication is turned on. Then, the camera  1  remains in this condition until the shutter button  31  is fully pressed to turn on the second shutter release switch (2RSW).  
         [0067]     After that, when the second shutter release switch is turned on, the first reflection mirror  51  is withdrawn out of the shooting optical path, and the aperture is narrowed to fit the image capturing. At the same time, the electric charge is flushed from the image pickup device  67  for image capturing. After completion of the actual exposure, data of the image captured is read and processed. On the other hand, after completion of the actual exposure (image capturing with the image pickup device  67 ), the first reflection mirror  51  is returned to the shooting optical path, and the shutter charge mechanism  75  charges the shutter. The image processed after captured by the imaging device  67  for image capturing appears on the LCD monitor  36  for a predetermined period of time. Then, when the predetermined period of time has passed, the image captured by the image pickup device  61  for image display is displayed again on the LCD monitor  36 .  
         [0068]     When the imaging device  67  for image capturing captures images continuously, for example, four times, the image to be displayed on the LCD monitor  36  is switched from the image captured by the imaging device  61  for image display to the image captured by the imaging device  67  for image capturing each time the imaging device  67  for image capturing performs image pickup. After that, when the first and second shutter release switches are turned off, the image captured by the imaging device  61  for image display appears on the LCD monitor  36 .  
         [0069]     The shooting operation in the finder mode will next be described with reference to  FIG. 5 .  
         [0070]     When the power switch lever  33  is operated to power on the camera  1 , the photometric sensor  63  and the AF sensor unit  71  repeat the AE and AF sequence at predetermined intervals. During this repetition, exposure information is displayed on the LCD monitor  36  provided on the back face of the camera body  30 . Then, when the shutter button  31  is pressed halfway at predetermined timing to turn on the first shutter release switch, the camera  1  starts the shooting preparation operation. In other words, the photographing lens  11  is driven to focus on the subject. When the photographing lens  11  comes to the focus range, one of the LEDs  64  for focused indication is turned on. Then, the camera  1  remains in this condition until the shutter button  31  is fully pressed to turn on the second shutter release switch (2RSW). During this shooting preparation operation, since the photographer is looking into the viewfinder  43  for shooting, nothing appears on the LCD monitor  36  to avoid unnecessary display for the purpose not only of saving energy, but also of allowing the photographer to focus attention on shooting.  
         [0071]     Then, when the second shutter release switch is turned on, the first reflection mirror  51  is withdrawn out of the shooting optical path, and the aperture is narrowed to fit the image capturing. At the same time, the electric charge is flushed from the image pickup device  67  for image capturing. After completion of the actual exposure, data of the image captured is read and processed. On the other hand, after completion of the actual exposure, the first reflection mirror  51  is returned to the shooting optical path, and the shutter charge mechanism  75  charges the shutter. The image processed after captured by the imaging device  67  for image capturing appears on the LCD monitor  36  for a predetermined period of time. Then, the LCD monitor  36  is turned off and remains off during preparation for the next shooting. After that, the next image processed after captured by the imaging device 4   67  for image capturing appears on the LCD monitor  36 .  
         [0072]     When the imaging device  67  for image capturing captures images continuously, for example, four times, an image captured each time the imaging device  67  performs image pickup is displayed on the LCD monitor  36 . Note that the imaging device  61  for image display is not in operation in the finder mode.  
         [0073]     The following describes an image observed in the viewfinder  43  and an image displayed on the LCD monitor  36  with reference to  FIGS. 6A and 6B .  
         [0074]      FIG. 6A  shows an example of the focusing screen  56 .  FIG. 6B  shows an example of a series of display images on the LCD monitor  36  in the live view mode.  
         [0075]     In  FIG. 6A , AF target marks (mark-off lines)  95  are imprinted on the surface of the focusing screen  56  as reference points for AF. The photographer looks into the viewfinder  43  to observe an image projected on the focusing screen  56  with the AF target marks  95  provided on it.  
         [0076]     On the other hand, a series of images of a subject are displayed as shown in  FIG. 6B  on the LCD monitor  36  provided on the backside of the camera body  30 . The images are updated in time from the leftmost frame to the rightmost frame. The images displayed on the LCD monitor  36  in the live view mode, for example, the live images  96   a  and  96   b  are displayed in such a manner to contain the images of the AF target marks  95  ( 97   a ,  97   b ,  97   c ). Then, when the first (1st) shutter release switch is turned on and the photographing lens is focused, one of the LEDs  64  for focused indication is lit to light a corresponding one of the AF target marks, for example,  97   a  in the live image  96   c.    
         [0077]     Under this condition, when the second (2nd) shutter release switch is turned on, an image  96   d  actually captured by the imaging device  67  for image capturing is displayed on the LCD monitor  36 . The image  96   d  remains displayed for a predetermined period of time. After the predetermined period has passed, a live image  96   e  with focus marks  97   a - 97   c  superimposed in it is displayed on the LCD monitor  36 . The display of the image  96   d  actually captured by the imaging device  67  for image capturing can be differentiated from that of live images, such as with a frame surrounding and enclosing the image  96   d  as shown.  
         [0078]     Thus, the image actually captured is displayed without the AF target marks  95 , and this makes it easy for the photographer to distinguish it from live images.  
       Second Embodiment  
       [0079]     In the first embodiment, a mode is selected with the operation of the control dial to switch over between a series of live images and an image actually captured. On the other hand, a second embodiment is such that a lever is switched directly between the two modes to switch over between a series of live images and an image actually captured.  
         [0080]     The following describes the structure and operation of the second embodiment. The basic structure and basic shooting operation of a digital camera according to the second embodiment are the same as those of the first embodiment shown in  FIGS. 1 through 6 . Therefore, portions common to those in the first embodiment are given the same reference numerals and their repetitive description will be omitted.  
         [0081]      FIG. 7  is an outline perspective view showing the structure of a single-lens reflex digital camera to which an imaging device according to the second embodiment of the present invention is applied.  
         [0082]     In  FIG. 7 , a finder/live view (F/L) switching lever  101  is provided on the top face of a camera body  100  to switch over between an actually captured image and a live image. For the finder mode, the F/L switching lever  101  is set at a position indicated by “F” on the top face of the camera body  100 . For the live view mode, it is set at a position indicated by “L.” Thus the photographer can switch over between the actually captured image, and the live image.  
         [0083]      FIG. 8  is a perspective view showing the structure of a finder optical system of the camera according to the second embodiment of the present invention.  
         [0084]     A finder optical system  102  includes the first reflection mirror  51  with part of the first reflection mirror  51  formed into a half mirror, the second reflection mirror  52  formed as a half mirror, the third reflection mirror  53 , a fourth reflection mirror  103  rotatable about an axis  103   a  in both directions B 1  and B 2  indicated by a double-headed arrow in  FIG. 8 , the focusing screen (mat screen)  56 , and the eyepiece lens  57 .  
         [0085]     The photometric sensor  63  is arranged on the backside of the reflection surface of the second reflection mirror  52 . An LCD  104  for displaying shooting information and the like is provided adjacent to the focusing screen  56 .  
         [0086]      FIGS. 9 and 10  are perspective views showing a drive mechanism of the fourth reflection mirror  103  according to the second embodiment of the present invention.  FIG. 9  shows a state in which an eyepiece shutter is open for observation of a subject.  FIG. 10  shows a state in which the eyepiece shutter is closed. In addition,  FIG. 11  is a partially cutaway view showing the F/L mode switching lever  101  in the second embodiment of the present invention.  
         [0087]     The fourth reflection mirror  103  is rotatably attached to a rotary shaft  108  (that is, which can rotate about the rotary shaft  108  in both directions B 1  and B 2  indicated by the arrow in  FIG. 8 ) near an eyepiece frame  105  on which an eyepiece  115  is mounted. A spring (toggle spring)  109  is wound around the rotary shaft  108 . One end of the spring is held by a spring trigger pin  110  provided irror  52  in a direction opposite to the reflective  05 , and the other end is caught by a spring trigger pin  111  provided on the rotary shaft  108 .  
         [0088]     An F/L detection switch  106  is provided near the opening of the eyepiece frame  105  to switch over between the finder/live view modes depending on the open/closed state of the fourth reflection mirror  103 . A detection portion  106   a  is provided on the F/L detection switch  106  in the form of a projection. As shown in  FIG. 10 , when pushed in by the fourth reflection mirror  103 , the detection portion  106   a  of the F/L detection switch  106  detects that the fourth reflection mirror  103  has been closed. On the other hand, when released, the detection portion  106   a  detects that the fourth reflection mirror  103  has been opened.  
         [0089]     The spring  109  is biased in a direction to open the fourth reflection mirror  103  (in the direction B 1  in  FIG. 9 ), so that the fourth reflection mirror  103  is normally in contact with a stopper  112  as shown in  FIG. 9 . Under this condition, a light beam guided through the second reflection mirror  52  and the third reflection mirror  53  is reflected by the fourth reflection mirror  103  to reach the eyepiece  105 . The stopper  112  is fixed, for example, on the top of a mirror box (not shown) in which the first reflection mirror  51  and the like are housed. The stopper  112  is eccentrically mounted so that a minor adjustment can be made to the angle of the fourth reflection mirror  103 .  
         [0090]     A projection portion  113  provided on the top of the rotary shaft  108  is interlocked with the F/L switching lever  101  shown in  FIG. 11  through an engagement member, not shown. In other words, when the F/L switching lever  101  is operated in a counterclockwise direction of arrow C in  FIG. 11 , the rotary shaft  108  is rotated along with the operation of the F/L switching lever  101  to rotate the fourth reflection mirror  103  in the direction of arrow B 2  shown in  FIG. 9 .  
         [0091]     As a result, as shown in  FIG. 10 , the fourth reflection mirror  103  comes in contact with the eyepiece frame  105  so that a subject image will be captured by the imaging device  61  for image display as a live image. At this moment, since an external light beam from the eyepiece  115  is blocked inside the eyepiece frame  115  by the fourth reflection mirror  103 , no light is incident into the camera body  30 . In addition, the B μcom  80  is informed that the eyepiece  115  is light-shielded with the operation of the F/L detection switch  106 .  
         [0092]     The F/L switching lever  101  can be provided with a known lock mechanism or a hook portion. Further, the F/L switching lever  101  and the rotary shaft  108  can be connected, for example, by an overcharge mechanism engaged through a spring, or directly with each other.  
         [0093]      FIG. 12  is a block diagram showing a system configuration of the camera according to the second embodiment of the present invention.  
         [0094]     In  FIG. 12 , the LCD  104  for information display arranged near the focusing screen  56  and the F/L detection switch  106  are connected to the B μcom  80 . The B μcom  80  controls the lighting state of the LCD  104  for information display depending on the detection state of the F/L detection switch  106 .  
         [0095]     The basic shooting operation of the camera according to the second embodiment is performed in the same way as that in the first embodiment according to the timing charts shown in  FIGS. 4 and 5 . A different point is that the switching between the live view mode and the finder mode is done in the first embodiment by selecting a mode with the operation of the control dial, whereas the switching between the live view mode and the finder mode is done in the second embodiment by switching the F/L mode switching lever  101  and detecting the switching of the F/L mode switching lever  101  through the F/L detection switch  106 .  
         [0096]     A description will next be made of images displayed on the LCD monitor  36  in the second embodiment with reference to  FIGS. 13A and 13B .  
         [0097]      FIG. 13A  shows an example of an image captured in the live view mode by the imaging device  61  for image display.  FIG. 13B  shows a series of display images on the LCD monitor  36 .  
         [0098]     In  FIG. 13A , the imaging device  61  for image display forms a finder image  120  consisting of a subject image display part  121  and a shooting information display part  122  according to the display image on the focusing screen  56  and the LCD  104  for information display. The photographer can see the captured finder image on the LCD monitor  36  to observe a subject image displayed in the subject image display part  121  while obtaining various kinds of information related to the shooting conditions, such as shutter speed and exposure, displayed in the shooting information display part  122 .  
         [0099]     As shown in  FIG. 13B , images  123   a  and  124   a  corresponding to the subject image display part  121  and the shooting information display part  122  are displayed on the LCD monitor  36  provided on the back face of the camera body  30  in the same manner as in  FIG. 6B . The images are updated in time from the leftmost frame to the rightmost frame in  FIG. 13B . The images displayed on the LCD monitor  36  in the live view mode, for example, live images  123   a ,  123   b  and the images  124   a ,  124   b  of the shooting information are displayed on the LCD monitor  36 . Then, when the first (1st) shutter release switch is turned on as mentioned above, the live images  123   c  and  124   c  appear on the LCD monitor  36 .  
         [0100]     Under this condition, when the second (2nd) shutter release switch is turned on, only an image  125  actually captured by the imaging device  67  for image capturing is displayed on the LCD monitor  36  instead of the finder image, consisting of the live image and the image of the shooting information at the side of the live image, which has been displayed just before the second (2nd) shutter release switch is turned on. Then, after the image  125  is displayed for a predetermined period of time, a live image  123   d  and a shooting information image  124   d  appear on the LCD monitor  36 .  
         [0101]     Thus, when a live view display is made, the shooting information is displayed together with a subject image, while when the display of an actually captured image is made, only the subject image is displayed. This makes it easy for the photographer to distinguish between the live image and the actually captured image.  
         [0102]     While there has been shown and described what are considered to be preferred embodiments of the invention, it will, of course, be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention not be limited to the exact forms described and illustrated, but constructed to cover all modifications that may fall within the scope of the appended claims.