Abstract:
The present invention provides a camera system including a camera head and a camera body provided with a disengagement operation detecting section and a recording control section. The disengagement operation detecting section detects operation of disengaging the camera head from the camera body in the state where image information can be transmitted from the camera head to the camera body. The recording control section stops recording of image information in response to operation of disengaging the camera head from the camera body being detected by the disengagement operation detecting section.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a camera system having a camera head which is provided with an image taking optical system and an image pickup device to generate image information, and a camera body which receives image information from the camera head detachably attached thereto to record image information in a recording medium.  
         [0003]     2. Description of the Related Art  
         [0004]     In the movie industry, one frame (cut) is taken from a movie film as a still image to be used, for example, as a poster. As it is convenient for a user to be able to take a still image from a moving image, some video cameras are configured to be able to take a still image from a moving image (for example, see Japanese Patent Application Publication No. 6-189169). The technique disclosed in Japanese Patent Application Publication No. 6-189169 teaches obtaining high-quality still image of fine pixels by incorporating shooting at a fast shutter speed into a movie shooting. However, this technique has a problem in which a high-capacity recording medium is required for a high-quality image of fine pixels included in a moving image. Thus, there is a recent trend that a high-capacity medium such as a hard disc or a DVD which are in common use for computers, is used to record a moving image. Using such a high-capacity medium allows recording of large amounts of image data and thereby storing various image information in one recording medium.  
         [0005]     Amid the situation in which large amounts of image information can be stored in one recording medium, concerns are that all the image information recorded in one recording medium will be lost if the recording medium is mistakenly taken out during recording. Thus, some video cameras are provided with protection functions. For example, Japanese Patent Application Publication No. 2001-143371 teaches locking mechanism to prevent pulling out of a recording medium during recording, and Japanese Patent Application Publication No. 9-231683 teaches a protection function to protect a writing head against impact or vibration when an image information recording apparatus falls or is subject to vibration, thereby preventing destruction of image data.  
         [0006]     However, due to the recent trend for a digital camera capable of movie shooting, in one type of such a digital camera, a camera head is separated from a camera body and is attached to the camera body during shooting. In a camera system of such a digital camera, if a camera head is disengaged from a camera body during recording of image information, all the image information in a recording medium including the one being recorded will be lost even if the protection function described above is provided. This is because, when a camera head is disengaged from a camera body while image information is recorded, connection is instantly cut between the electric contacts of a camera head and those of a camera body and thus the surge voltage with large peak-to-peak values is applied from the electric contacts to the inner circuits of both the camera head and the camera body.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention has been made in view of the above circumstances, and provides a camera system which, even when a camera head is disengaged from a camera body while image information is recorded in the camera body, prevents destruction of the image information in a recording medium including the image information being recorded.  
         [0008]     A camera system of the present invention has a camera head which is provided with an image taking optical system and an image pickup device to generate image information, and a camera body which receives image information from the camera head detachably attached thereto to record image information in a recording medium, the camera system including;  
         [0009]     a disengagement operation detecting section which detects operation of disengaging the camera head from the camera body in the state where image information can be transmitted from the camera head to the camera body; and  
         [0010]     a recording control section which stops recording of image information in response to operation of disengagement of the camera head being detected by the disengagement operation detecting section.  
         [0011]     Therefore, the disengagement operation detecting section detects operation of disengagement of the camera head before it occurs, and upon the detection the recording control section stops recording of image information.  
         [0012]     As recording of image information is stopped before disengagement of the camera head, it is possible to prevent the case where application of surge voltage to the inner circuits upon disengagement of the camera head results in destruction of recording of image information being recorded or already recorded in a recording medium such as DVD.  
         [0013]     Preferably, the camera body includes a locking button and a fastening unit which is adapted to fasten the camera head to the camera body so that the camera head cannot be disengaged, and to allow the camera head to be disengaged from the camera body by operation of the locking button, and the disengagement operation detecting section may detect the operation of the locking button.  
         [0014]     Accordingly, the recording control section is informed of operation of the locking button for disengaging the camera head from the camera body, through the disengagement operation detecting section, and stops recording of image information before the camera head is disengaged.  
         [0015]     In other words, even if the camera head is disengaged from the camera body during image information is recorded, destruction of image information can be prevented including the one being recorded.  
         [0016]     More preferably, the fastening unit is adapted to allow the camera head to be disengaged from the camera body, in response to a full press of the locking button up to a predetermined position, and the disengagement operation detecting section detects a half press of the locking button prior to the full press.  
         [0017]     Even when the locking button is fully pressed in one action, as the disengagement operation detecting section detects the half press of the locking button and informs the recording control section of the detection, information recording is stopped before the camera head is disengaged from the camera body.  
         [0018]     It is also preferable that the camera head and the camera body respectively include image information transmitting electric contacts which transmit image information while the camera head is attached to the camera body, and a disengagement detecting electric contact whose state changes before the image information transmitting electric contacts become electrically discontinuous, in response to operation of disengaging the camera head from the camera body, and that the disengagement operation detecting section detects the change of the disengagement detecting electric contact.  
         [0019]     Even when the camera head is rotated to be disengaged while image information transmitting electric contacts are electrically continuous, the state of the disengagement detecting electric contacts change earlier than image information transmitting electric contacts and the change is detected by the recording control section. Accordingly, it is possible to prevent the case where the camera head is disengaged while image information is transmitted through electric contacts.  
         [0020]     It should be also noted that change in the state of the disengagement detecting electric contact is applied to both a case where the disengagement detecting electric contact becomes detached from its counterpart in response to operation of disengaging the camera head from the camera body, and a case where the disengagement detecting electric contact is detached from its counter part when the camera head is attached to the camera body and becomes in contact with its counterpart in response to disengaging operation. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  is a perspective external view of a camera system viewed obliquely from above, according to an embodiment of the present invention;  
         [0022]      FIG. 2  is a schematic sectional view illustrating an internal configuration of the periphery of a locking button according to the embodiment;  
         [0023]      FIG. 3  illustrates a process performed by a camera body CPU to stop information recording.  
         [0024]      FIG. 4  illustrates a configuration for activating a release switch without fail before a camera head is disengaged from a camera body;  
         [0025]      FIG. 5  illustrates a configuration of electric contacts for transmitting image information and electric contacts for detecting disengagement which are provided on both the camera head and the camera body; and  
         [0026]      FIG. 6  shows a process performed by the camera body CPU to stop information recording. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]     An embodiment of the present invention will be described below with reference to the attached drawings.  
         [0028]      FIG. 1  is a perspective external view of a camera system  1  viewed obliquely from above according to the embodiment of the present invention.  
         [0029]      FIG. 1  shows that a camera head  1   a  is about to be detachably attached to a camera body  1   b  provided with an image taking optical system and an image pickup device which receives image signals from the camera head  1   a  to perform signal processing.  
         [0030]     As shown in  FIG. 1 , a head mounting section  10   b  having multiple mounting contacts is disposed in the substantial center of the camera body  1   b , so that a rear end of the camera head  1   a  can be attached to the head mounting section  10   b . Although not shown in  FIG. 1 , the rear end of the camera head  1   a  and the head mounting section  10   b  respectively have three or four claws formed thereon so as to be engaged with each other in a bayonet mount configuration.  
         [0031]     Accordingly, when the rear end of the camera head  1   a  is attached to the head mounting section  10   b  by being rotated and engaged therein, the camera head  1   a  is securely engaged with and at the same time is electrically connected with the camera body  1   b , through connection between multiple mounting contacts.  
         [0032]     In the camera system  1 , the camera body  1   b  is provided with a battery which supplies power to the camera body  1   b , and to the camera head  1   a  through electric contacts out of multiple mounting contacts respectively provided in the camera body  1   b  and the camera head  1   a . When the camera head  1   a  receives power supplied from a battery in the camera body  1   b  through the electric contacts, both the camera head  1   a  and the camera body  1   b  enter into operating state.  
         [0033]     Additionally, a release button  13   b  and a mode dial  14   b  are provided on the top of the camera body  1   b . Image taking operation is performed by selecting a shooting mode using the mode dial  14   b  and then by pressing the release button  13   b . Upon image taking operation, image information is transmitted from the camera head  1   a  through the electrical contacts of the head mounting section  10   b  to the camera body  1   b . The mode dial  14   b  includes, other than the shooting mode, items such as replay mode and power ON/OFF switch, and is rotated when selecting one of the items. The camera body  1   b  also has AWB sensor  11   b  and flash emitting window  12   b  on its front.  
         [0034]     In the camera system  1  of the present invention, locking button  19   b  is provided in the camera body  1   b . Engaging pin  192   b  is provided in the head mounting section  10   b , which retracts into the camera body  1   b  in sync with press operation of the locking button  19   b.    
         [0035]     The engaging pin  192   b  partly constitutes a bayonet mount configuration provided in the camera system  1  of the present invention. Bayonet mount configuration, which is a well known technique, corresponds to a fastening unit of the present invention.  
         [0036]     When the camera head  1   a  is attached to the camera body  1   b , the engaging pin  192   b  provided in the bayonet mount section advances toward the camera head  1   a  and is engaged in an opening formed in the camera head  1   a . Accordingly, the camera head  1   a  can be securely fastened to the camera body  1   b  so as not to rotate relative to the camera body  1   b.    
         [0037]     Spring  193   b  (see  FIG. 2 ) is provided inside the camera body  1   b , which press the locking button  19   b  toward the front of the camera body  1   b . In order to disengage the camera head  1   a  from the camera body  1   b , the locking button  19   b  is pressed down against the spring  193   b  to disengage the engaging pin  192   b  from the opening in the camera head  1   a.    
         [0038]     Now, explanation will be made referring to  FIG. 2 .  
         [0039]      FIG. 2  is a schematic sectional view illustrating an internal configuration of the periphery of the locking button  19   b  provided in the camera body  1   b.    
         [0040]      FIG. 2  shows the camera head  1   a  in the left (represented by dotted lines) which is to be attached to the head mounting section  10   b , and the locking button  19   b  provided in the downside of the head mounting section  10   b . The locking button  19   b  has a two-segmented cylindrical configuration consisting of an operating portion  190   b  and a fitting portion  191   b  in which the operating portion  190   b  has larger radius than the fitting portion  191   b . The operating portion  190   b  is pressed by the spring  193   b , which is wound around the fitting portion  191   b , toward the front of the camera body  1   b  to protrude therefrom. The fitting portion  191   b  is fitted into an opening  110   b  formed in fixed section  111   b  of the camera body  1   b  so as to allow the fitting portion  191   b  to slidably move. Additionally, the spring  193   b  is arranged between the operating portion  190   b  and the fixed section  111   b , and an engaging piece  1921   b  provided in the engaging pin  192   b  is placed in contact with the boundary between the operating portion  190   b  and the fitting portion  191   b . Accordingly, the engaging pin  192   b  is also urged by the spring  193   b  toward the front of the camera body  1   b  to protrude therefrom. Therefore, when the camera head  1   a  is not attached to the camera body  1   b , the engaging pin  192   b  as well as the locking button  19   b  are pressed by the spring  193   b  to protrude from the front of the camera body  1   b . When the camera head  1   a  is rotated to be engaged in a ring groove formed in the head mounting section  10   b  in order to be attached to the camera body  1   b , the engaging pin  192   b  is at first pressed into the inside of the camera body  1   b . As the camera head  1   a  is further rotated, the opening of the camera head  1   a  arrives in the position facing the engaging pin  192   b  to receive the engaging pin  192   b . Thus, with the engaging pin  192   b  fitted into the opening, the camera head  1   a  is securely engaged with the camera body  1   b  such that the camera head  1   a  cannot move relative to the camera body  1   b . On the other hand, in order to disengage the camera head  1   a  from the camera body  1   b , the locking button  19   b  is pressed to retreat the engaging pin  192   b  into the camera body  1   b.    
         [0041]      FIG. 2  shows the camera head  1   a  securely attached to the camera body  1   b , in which the engaging pin  192   b  protrudes from the front of the camera body  1   b  and is fitted into the opening of the camera head  1   a . When image taking operation is preformed under such condition, image information, which is generated in an image pickup device of the camera head  1   a , is recorded in a recording medium (not shown) through recording section  102   b  of the camera body  1   b . If the locking button  19   b  is pressed, during image taking operation, to disengage the camera head  1   a  from the camera body  1   b , release switch  101   b  provided on the end of the locking button  19   b  inside the camera body  1   b  is activated to notify camera body CPU  100   b  that the camera head  1   a  is about to be disengaged just before it is disengaged. Upon the notification, the camera body CPU  100   b  instructs the recording section  102   b  to stop recording processing.  
         [0042]     Accordingly, even when the camera head  1   a  is disengaged from the camera body  1   b  during image information recording in a recording medium by the recording section  102   b , it is possible to prevent the case where surge voltage is applied from electric contacts on the head mounting section  10   b  to a recording medium or the like.  
         [0043]     In other words, even when the camera head  1   a  is about to be disengaged from the camera body  1   b  during recording processing of image information in the camera body  1   b , the recording section  102   b  is caused to stop the recording processing before the camera head  1   b  is disengaged. Thus, the camera system  1  of the invention can prevent destruction of image information in the recording medium including the information being recorded.  
         [0044]     Now, referring to  FIG. 3 , explanation will be made regarding the camera body CPU  100   b  which corresponds to a recording control section according to the invention.  
         [0045]      FIG. 3  illustrates a process for the camera body CPU  100   b  to stop information recording.  
         [0046]     The process starts when the release button  13   b  shown in  FIG. 1  is pressed.  
         [0047]     After the release button  13   b  is pressed, it is determined in step S 301  whether the locking button  19   b  shown in  FIGS. 1 and 2  is pressed or not. When it is determined that the locking button  19   b  is pressed (Yes), the flow goes to step S 302  to stop recording processing in the recording section in  FIG. 2 .  
         [0048]     Accordingly, the camera system  1  of the invention can prevent destruction of image information in the recording medium including the information being recorded, even when the camera head  1   a  is disengaged from the camera body  1   b  while image information is recorded by the recording section  102   b  in the camera body  1   b.    
         [0049]     However, it should be also noted that the release switch  101   b  may be activated in sync with disengagement of the camera head  1   a  from the camera body  1   b , depending on the size of relevant parts and fitting condition thereof, if full press of the locking button  19   b  takes place in one action. Therefore, the camera system should have a configuration to ensure that the release switch is activated before disengagement of the camera head  1   a  from the camera body  1   b.    
         [0050]      FIG. 4  illustrates such a configuration.  
         [0051]      FIG. 4  shows an internal configuration of the camera body  1   b ; before the locking button  19   b  is pressed in Part (a) of  FIG. 4 ; when the locking button  19   b  is half pressed in Part (b) of  FIG. 4 ; and when the locking button  19   b  is fully pressed in Part (c) of  FIG. 4 .  
         [0052]     As shown in Part (c) of  FIG. 4 , the size of the operation portion  190   b  and fitting portion  191   b  and the position of the fixed section  111   b  (see  FIG. 2 ) are configured such that disengagement of the camera head  1   a  is enabled only after the locking button  19  is fully pressed and the engagement pin  192   b  becomes flush with the front of the camera body  1   b.    
         [0053]     In other words, the camera head  1   a  can be disengaged from the camera body  1   b  only after the locking button  19   b  is fully pressed (to reach a predetermined position relative to the release switch  101   b ) as shown in Part (C) of  FIG. 4  according to the invention. In addition, the release switch  101   b , which corresponds to a disengagement operation detecting section of the invention, is adapted to detect the position of the locking button  19   b  when it is half-pressed as shown in Part (b) of  FIG. 4 .  
         [0054]      FIG. 5  illustrates a configuration of electric contacts for transmitting image information and an electric contact for detecting disengagement which are provided on both the camera head  1   a  and the camera body  1   b . Part (a) of  FIG. 5  shows a configuration of image information transmitting electric contacts  103   b  and disengagement detecting electric contact  1031   b  provided in the camera body  1   b . Part (b) of  FIG. 5  shows a configuration of electric contacts  100   a  for transmitting image information and detecting disengagement provided in the camera head  1   a . Part (c) of  FIG. 5  shows the state in which the image information transmitting electric contacts  103   b  and the disengagement detecting electric contact  1031   b  of the camera body  1   b  are in contact with electric contacts  100   a  of the camera head  1   a.    
         [0055]     As shown in Part (a) of  FIG. 5 , spacing between the disengagement detecting electric contact  1031   b  and one of the image information transmitting electric contacts  103   b  is adapted to differ from that between the image information transmitting electric contacts  103   b . Accordingly, when the camera head  1   a  is rotated in the direction indicated by the arrow in Part (c) of  FIG. 5  to be disengaged from the camera body  1   b , the state of the disengagement detecting electric contact  1031   b  will change (to the off state by being detached) prior to any of other image information transmitting electric contacts  103   b , so that the camera body CPU  100   b  (see  FIG. 2 ) can detect the change in the state of the disengagement detecting electric contact  1031   b  and cause the recording section  102   b  (see  FIG. 2 ) to stop recording processing.  
         [0056]     In other words, when the camera head  1   a  is to be disengaged from the camera body  1   b  in the state where the disengagement detecting electric contact and the image information transmitting electric contacts provided on both the camera head  1   a  and the camera body  1   b  are in contact with one another, the disengagement detecting electric contact  1031   b  of the camera body  1   b  changes its state to become electrically discontinuous before the image information transmitting electric contacts  103   b  become electrically discontinuous, such that the camera body CPU  100   b , which also corresponds to the disengagement operation detecting section according to the invention, can detect the change.  
         [0057]      FIG. 6  shows a process performed by the camera body CPU when disengagement detecting electric contact changes its state.  
         [0058]     The flow shown in  FIG. 6  starts when the release button  13   b  is pressed.  
         [0059]     While image information is recorded in a recording medium after the release button  13   b  is pressed, in step S 601 , it is determined whether continuity of the disengagement detecting electric contact  1031   b  of  FIG. 5  is in off state or not, thereby finding if the camera head  1   a  is about to be disengaged or not. If the disengagement detecting electric contact  1031   b  is determined to be in off state (Yes), the flow goes to step S 602  where recording processing in the recording section  102   b  (see  FIG. 2 ) is caused to stop.  
         [0060]     As described above, even if the camera head  1   a  is disengaged from the camera body  1   b  while recording processing is performed in the camera body  1   b , the camera system  1  of the invention can prevent destruction of image information recorded in a recording medium including the one being recorded.  
         [0061]     Additionally, although Part (a) of  FIG. 5  shows only one disengagement detecting electric contact  1031   b , the number of disengagement detecting electric contact  1031   b  may be more than one.