Abstract:
A thin video camera using an optical disc, comprises an image pick-up optical system for taking up image data to be picked up, and a view finder for displaying the image data, and an optical disc unit for recording the image data on an optical disc, wherein the optical disc unit is arranged in a plane which faces the optical disc and which is laid in parallel with the optical disc, without being overlapped with the image pick-up optical system.

Description:
INCORPORATION BY REFERENCE  
         [0001]    The present application claims priority from Japanese application JP2003-136689 filed on May 15, 2003, the content of which is hereby incorporated by reference into this application.  
         BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to a video camera, and in particular to a video camera using an optical disc as a recording medium.  
           [0003]    In stead of a magnetic tape which has been conventionally used, a vide camera using an optical disc as a recording medium has been commercially available, as disclosed in JP-A-2001-111877. Such a vide camera uses a DVD-RAM having a diameter of 80 mm as the optical disc. In this video camera, a camera lens and a view finder are arranged in a direction perpendicular to the surface of an optical disc, being overlapped with an optical disc and an optical disc unit.  
           [0004]    Referring to FIGS. 5 and 6 which are a side view and a front view, respectively, illustrating a conventional vide camera in an image pick-up mode, using an optical disc, explanation will be made of a positional relationship among the optical disc unit, the camera lens and the view finder in a conventional video camera using an optical disc. In these figures, X-, Y- and Z-axial directions correspond to the longitudinal direction, the widthwise direction and the heightwise direction of the vide camera, respectively.  
           [0005]    In FIGS. 5 and 6, there are shown a camera housing  1  incorporating components of the video camera using an optical disc, a camera lens  2  for taking up image data to be picked up, a view finder  3  and a liquid crystal display unit  4  on which the image data is displayed so that the user can confirm an image to be picked up, an optical disc unit  4  for recording the image data taken up by means of the camera lens on an optical disc  5 , a camera circuit board  6  mounted thereon with a circuit for controlling the camera lens  2 , a chassis  8  holding components of the optical disc unit  4 , a spindle motor  9  for rotating the optical disc  5 , and an optical head  10 B for irradiating a light beam onto the optical disc  5  in order to record the image data on the optical disc  5 . The optical head  10 B is guided and moved along guide bars  11  by a power which is transmitted to the optical head  10 B from a seek motor  12  through the intermediary of a lead screw  14  and a rack  15 . The circuit board  13  is mounted thereon with a circuit for controlling the optical disc unit  4 , and is connected to the optical head  10 B by means of a flexible cable  16 .  
           [0006]    The optical disc unit  4  is composed of the chassis  8 , the spindle motor  9 , the optical head  10 B, the guide bars  11 , the seek motor  12 , the circuit board  13 , the lead screw  14 , the rack  15  and the flexible cable  16 . The optical disc  5  is removably loaded on the optical disc unit  4 .  
           [0007]    In the camera housing  1 , the camera lens  2  and the view finder  3  are arranged, being aligned with each other in the X-axial direction. Both camera lens  2  and view finder  3  are juxtaposed with the optical disc unit  4  in the Y-axial direction. In general, the cameral lens  2  and the view finder  3  are arranged in the X-axial direction, coaxial with each other, in the upper section of the camera housing  1  (as viewed in the Z-axial direction) in view of easy handling the video camera using an optical disc. Accordingly, the camera circuit board  6  and the liquid crystal display unit  7  are laid below the camera lens  2  and the view finder  3 . A zoom lens is used as the camera lens  2 , and cannot be small-sized greatly, in view of such a fact that a predetermined degree of exposure should be ensured. Thus, the camera lens occupies a space having a diameter of about 40 mm, and a length greater than the diameter. The view finder  3  also has the same size as that of the camera lens  2 .  
           [0008]    The optical disc unit  3  records picked-up data on the optical disc  5 . Specifically, a light beam is irradiated onto the optical disc  5  which is mounted on the spindle motor  9  for rotation by the optical head  10 B that is connected to the circuit board  13  through the intermediary of the flexible cable  16  so as to record and reproduce the image data thereon and therefrom.  
           [0009]    The optical head  10 B is mounted on the chassis  8  by the two guide bars  11  spaced from each other by a distance L 2  (about 60 mm). Since the rack  15  is meshed with the lead screw  14  of the seek motor  12 , the optical head  10 B can be moved in the radial direction of the optical disc  11  when the seek motor  12  is rotated.  
           [0010]    It is noted that there has been known a video camera using an optical disc, in which the seek motor  12  and the lead screw  14  are laid above the optical head  10 B although, in the above-mentioned vide camera using a optical disc, they are laid therebelow (for example, refer to a JP-A-2000-32309).  
           [0011]    Referring to FIGS. 7 and 8 which are a plan view and a sectional view, respectively, illustrating the optical head  10 B, explanation will be made of the configuration of the optical head  10 B used in the above-mentioned prior art (Refer to, for example, JP-A-09-180240).  
           [0012]    A laser beam  19  emitted from a laser diode  18  attached to a casing  17 , passes through a polarized. beam splitter  30  and is then incident upon a collimating lens  21  so as to be turned into a parallel ray beam which is then reflected upon a rise-up mirror  22 , then passes through a polarization diffraction grating  23 , and is converged by an objective lens  24  so as to be focused on the optical disc  5 . A reflected beam from the optical disc  5  passes through the above-mentioned optical path in a reverse order, and is then reflected by the polarized beam splitter  20  onto a photo detector  30 . Data from the optical disc  5  is reproduced by an output from the photo detector  30 , and a positional deviation signal between the focused point of the laser beam  19  and a recording surface of the optical disc  5  are detected, and a positional deviation signal between the focused point and a recording track on the optical disc  5 .  
           [0013]    The polarization diffraction grating  23  and the objective lens  24  is attached to a laser holder  25  which is suspended on four bar suspensions  26 , that is, the four bar suspensions  26  are secured at one end thereof (first end) to the lens holder  25 , and at the other end thereof (second end) to a holder  27  fixed to the casing  17 . The lens holder  25  is attached thereon with a coil (which is not shown) with which a yoke  28  and a magnet  29  are combined so as to constitute a voice coil motor. These components constitute the so-called two-dimensional actuator, and when a current is applied to the coil, the lens holder  25  resiliently held by the bar suspensions  16 , and the objective lens  24  and the polarization diffraction grating  23  which are integrally incorporated with the lens holder  25  can be displaced in a two-dimensional plane defined by a direction (Y-axial direction) perpendicular to the surface of the optical disc  5  and the radial direction (X-axial direction) of the optical disc  5 . Explanation will be made of the technology of the two dimensional actuator used for the conventional optical head.  
           [0014]    For example, as disclosed in JP-A-2001-216665, the lens holder  25  is displaced in the above-mentioned two-dimensional space in response to the above-mentioned two positional deviation signals so as to position the focus point of the laser beam  19  onto a recording track on the recording surface of the optical disc  5 .  
           [0015]    In the above-mentioned video camera using an optical disc, the camera lens  2  is located at a position which is spaced in the Y axial direction from the optical disc  5  by a distance of about 15 mm with the optical head  10 B, the guide bars  11  and the seek motor  12  being interposed therebetween, and also, the view finder  3  is located at a position spaced from the optical disc  5  by a distance of about 15 mm in the Y-axial direction with the seek motor  12  and the circuit board  13  being interposed therebetween. As a result, the thickness W 2  of the video camera using an optical disc is about 50 mm.  
           [0016]    With the above-mentioned configuration, if the height (the dimension in the Z-axial direction) of the camera housing  1  is set to about 90 mm which is near to the diameter (80 mm) of the optical disc  5 , the video camera using an optical disc can have a shape which is easily handled by the human hands.  
           [0017]    In general, it is desired to miniaturize and thin a video camera in view of easy handling and portability. However, in the conventional video camera using an optical disc, since the camera lens and the view finder are overlapped with the optical disc unit, the thickness W 2  (dimension in the Y-axial direction) of the vide camera becomes larger due to this overlapping. In order to thin the video camera (reduction of the dimension in the Y-axial direction), it would be preferable to thin the seek motor itself and the optical head itself with the overlapping portion. However, it is difficult to greatly thin these parts.  
         SUMMARY OF THE INVENTION  
         [0018]    The present invention is devised in view of the problems inherent to the above-mentioned conventional technologies, and accordingly, an object of the present invention is to provide a vide camera using an optical disc, which has a reduced width.  
           [0019]    According to the present invention, there is provided a vide camera using an optical disc, comprising a pick-up optical system including a camera lens for taking up image data to be picked up and a view finder for displaying the image data, and an optical disc unit for recording the image data onto an optical disc, wherein the optical disc unit is located in a plane facing the optical disc in parallel with the latter, without overlapping with a part of the pick-up optical system.  
           [0020]    According to one specific form of the present invention, the above-mentioned optical disc unit is located without overlapping with the camera lens of the pick-up optical system.  
           [0021]    According to another specific form of the present invention, the above-mentioned optical disc unit is located without overlapping with the view finder of the pick-up optical system.  
           [0022]    According to further another specific form of the present invention, the optical disc unit is located without overlapping with both camera lens and view finder.  
           [0023]    In addition to the above-mentioned features and technical effects and advantages, other features and technical effects and advantages of the present invention will become apparent in the following description of preferred embodiments which will be explained with reference to the accompanying drawings in which:  
           [0024]    Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings.  
       
    
    
     BRIEF SUMMARY OF SEVERAL VIEWS OF THE DRAWING  
       [0025]    [0025]FIG. 1 is a side view illustrating an internal configuration of a vide camera using an optical disc in an embodiment of the present invention;  
         [0026]    [0026]FIG. 2 is a front view illustrating the internal configuration of the vide camera shown in FIG. 1;  
         [0027]    [0027]FIG. 3 is a plan view illustrating an optical head in the vide camera shown in FIG. 1:  
         [0028]    [0028]FIG. 4 is a sectional view illustrating the optical head shown in FIG. 3;  
         [0029]    [0029]FIG. 5 is a side view illustrating an internal configuration of a conventional vide camera using an optical disc;  
         [0030]    [0030]FIG. 6 is a front view illustrating the internal configuration of the conventional vide camera shown in FIG. 5;  
         [0031]    [0031]FIG. 7 is a plan view illustrating a conventional optical head; and  
         [0032]    [0032]FIG. 8 is a sectional view illustrating the optical head shown in FIG. 7. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]    Referring to FIGS.  1  to  4 , detailed explanation will be hereinbelow made of an embodiment of the present invention. Like reference numerals will be used to denote components having functions like to those of the conventional video camera which has been explained with reference to FIGS.  5  to  8  so as to omit detailed description thereof.  
         [0034]    Referring to FIGS. 1 and 2 which are a side view and a front view (viewed in the X-axial direction), respectively, illustrating a video camera using an optical disc in an image pick-up mode, a camera lens  2  and a view finder  3  are arranged in a camera housing  1 , being coaxial with each other in the X-axial direction above an optical disc unit  4  (as viewed in the Z-axial direction), and camera circuit boards  6  and a liquid crystal display unit  7  are arranged, being juxtaposed with the optical disc unit  4  in the Y-axial direction.  
         [0035]    An optical head  10 A will be explained with reference to FIGS. 3 and 4. In the optical head  10 A, a laser beam  19  emitted from a laser diode  18  attached to a casing  17 , is deflected in its advancing direction by a mirror  31  from the X-axial direction into the Z-axial direction, then, passing through a polarized beam splitter  20 , and is turned into a parallel ray beam by a collimating lens  21 . Then it is reflected into the Y-axial direction by a rise-up mirror  22 , passing through a polarization diffraction grating  23 , and is focused onto an optical disc  5  by an objective lens  24 . A reflected beam from the optical disc  5  passes through the optical path in a reversed order with respect to the incident light beam, and is reflected by the polarized beam splitter  20  onto a photo detector  30 . Data on the optical disc  5  is reproduced and a positional deviation signal between the focus point of the laser beam  19  and the recording surface of the optical disc  5  and a positional deviation signal between the focus point and a recording track are detected with the use of an output from the photo detector  30 .  
         [0036]    The polarization diffraction grating  23  and the objective lens  24  are mounted on a lens holder  25  of an objective lens actuator, and four bar suspensions  26  are secured at one end to the lens holder  25  and at the other end to a holder  27  fixed to the casing  17 . The lens holder  25  is attached thereto with a coil which is not shown, which constitutes a voice coil motor in combination of a yoke  28  and a magnet  29 .  
         [0037]    In the vide camera using an optical disc in this embodiment, the optical disc unit  4  is laid without overlapping with the camera lens  2  and the view finder  3  in a direction perpendicular to the optical disc  5  (Y-axial direction). With this arrangement, the thickness W 1  of the camera housing  1  can been reduced to about 40 mm in comparison with the thickness W 2  (about 50 mm) of the conventional vide camera shown in FIGS.  5  to  8 .  
         [0038]    Further, in the vide camera using an optical disc in this embodiment, the optical head  10  is small-sized, and the seek motor  12  is located on one side of the optical head  10 A, remote from the camera lens  2 . With this configuration, the height of the camera housing  1  in this embodiment can be substantially equal to that of the conventional one shown in FIG. 5. That is, this value does not exceed the diameter (80 mm in this embodiment) of the optical disc by about 10 mm. With this configuration, the optical disc unit  4  can be laid without overlapping with the camera lens  2  and the view finder  3  in the direction perpendicular to the optical disc (Y-axial direction) without changing the height of the video camera using an optical disc. Thus, in addition to the effect of thinning, the effect of miniaturization can also be obtained since it is not required to increase the height hereof, thereby it is possible to enhance easy handling and portability.  
         [0039]    The optical head  10 A in this embodiment is small-sized so that the space L 1  between the two guide bars  11   a , 11   b  can be set to about 40 mm which is narrower than that in the optical head  10 B shown in FIGS.  5  to  8 . That is, a relationship L 1 &lt;L 2  can be given. The object lens  24  has to be displaced between the inner periphery and the outer periphery of the optical disc  5  in the radial direction of the optical disc  5 . As shown in FIG. 1, when the optical head  10 A is displaced between the inner periphery and the outer periphery of the optical disc  4 , the direction of displacement of the optical head  10 A is preferably set to be in parallel with the X-axial direction in order to minimize the height (in the Z-axial direction) of the video camera. Accordingly, the objective lens  24  is positioned on a straight line which is passing through the center of the spindle motor  9  and which is in parallel with the X-axial direction.  
         [0040]    By decreasing the space L 1  between the two guide bars  11   a ,  11   b , the height of the camera housing  1  measured from the center of the optical disc  5  to the end of the video camera housing  1  has not to be changed even though the seek motor  12  is located on one side of the optical head  10 A, remote from the camera lens  2  and the view finder  3 . Further, by decreasing the space L 1  between the two guide bars  11   a ,  11   b , the distance from the objective lens  24  to the upper guide bar  11   a  can be decreased, and accordingly, the height of the chassis  8  can be decreased to a value substantially equal to that of the upper part of the periphery of the spindle motor  9  since the distance from the objective lens  24  to the upper guide bar  11   a  can be decreased.  
         [0041]    With this configuration, the optical head  10 A and the chassis  8  can be juxtaposed with the camera lens  2  in a X-Y plane without the Z-axial dimension of the camera housing  1  being increased, and accordingly, since the camera lens  2  and the optical disc unit  4  are not overlapped with each other in the thicknesswise direction (Y-axial direction), the optical disc  5  can be relatively approached by the camera lens  2 . In order to prevent the optical disc  5  from making contact with the camera lens  2  upon loading or unloading of the optical disc  5 , the provision of a wall is required between the optical disc  5  and the camera lens  2 . In the configuration of this embodiment, the distance between the optical disc  5  and the camera lens  2  can be deceased to about 4 mm in comparison with the video camera shown in FIGS.  5  to  8 , in which this distance is about 15 mm.  
         [0042]    Similarly, the optical disc  5  can be approached by the view finder  3  which is therefore prevented from being overlapped with the optical disc unit  4  since the seek motor  12  is located on the side of the objective lens, remote from the camera lens, and since the circuit board  13  and the chassis  8  can be miniaturized.  
         [0043]    It is noted that the miniaturization of the circuit board can be materialized by enhancing the packaging density of components and by using miniaturized components.  
         [0044]    As stated above, since the camera lens  2  and the view finder  3  are not overlapped with the optical disc unit  4 . The widths can be greatly decreased to about 11 mm in this part.  
         [0045]    Referring to FIGS. 3 and 4, explanation will be hereinbelow made of the configuration of the optical head  10 A incorporated in the video camera using an optical disc. FIG. 3 is a plan view illustrating the optical head  10 A, and FIG. 4 is a sectional view along the center line thereof in the XY plane.  
         [0046]    Although the laser beam emitted from the semiconductor laser  18  is directly incident upon the collimator lens  21  in the optical head  10 B shown in FIGS.  5  to  8 , the optical path in the optical head  10 A in this embodiment is intermediately folded in order to miniaturize the optical head  10 A. In this configuration, the semiconductor laser  18  is arranged so that the light beam emitted therefrom is advanced in a direction which is not the Z-axial direction but in the X-axial direction, and a mirror  31  is additionally provided so that the laser beam in the X-axial direction emitted from the semiconductor laser  18  is folded by the mirror  31  from the X-axial direction into a direction toward the collimator lens  21 , that is, the Z-axial direction. With this configuration, the distance from the objective lens  24  to the guide bar  11   b  on the side remote from the camera lens  2  can be decreased from L 2  to L 1 .  
         [0047]    Further, the provision of the holder  27  on the optical path of the lease beam  19  is different from the configuration of the optical head  10 B. Thus, the distance from the objective lens  24  to the guide bar  11   a  on the camera lens side can be decreased.  
         [0048]    It is noted here that should the holder  27  be arranged on the side of the objective lens remote from the camera lens, it would interfere with the collimator lens  21 , and the laser beam  9  is partly blocked. In order to arrange the holder  27  on the side remote from the camera lens without increasing the thickness of the optical head  10 A, the holder  27  is additionally formed with a run-off part  32  for the collimator lens  21  and a cutout  33  for passing the lease beam therethrough, thereby it is possible to prevent the holder  27  making contact with the collimator lens  21  and to prevent the holder  27  from blocking the laser beam  19 . Since should the thickness of the optical head  10  be increased, the thickness of the vide camera using an optical disc would be increased, the above-mentioned configuration also contribute to the thinning of the video camera using an optical disc.  
         [0049]    In the above-mentioned embodiment, although the explanation has been hereinabove made of such a configuration that the optical disc unit is arranged in a plane in parallel with the optical disc without being overlapped with both camera lens  2  and view finder  3 , the present invention should not be limited to this configuration, but there may be used such a configuration that the optical disc unit is prevented from being overlapped with at least one of the camera lens  2  and the view finder  3 , which has a thickness smaller than that of the other. Even with this configuration, it is possible to aim at thinning the video camera.  
         [0050]    In the embodiment stated hereinabove, although explanation has been made of such a configuration that the camera lens  2  and the view finder  3  are located in the upper part of the video camera, the camera lens  2  and the view finder  3  may be arrange in the lower part thereof. In this case, the arrangement of the components is reversed to that of the embodiment stated above. That is, the seek motor  12  is arranged on the upper side of the optical head  10 A while the holder  21  is arranged on the upper side of the objective lens  24 . With this configuration, technical effects and advantages similar to those obtained by the embodiment stated above can be obtained.  
         [0051]    In the embodiment stated above, although explanation has been made of the seek motor  12  used in the displacing mechanism for the optical head  10 , the invention should not be limited to this configuration. For example, a motor and a lead screw coupled with each other by a gear may be used, instead of the seek motor. Further, a linear voice coil motor may be used.  
         [0052]    In the above-mentioned embodiment, although explanation has been made of the seek motor  12  and the guide bar  11   b  which are separated from each other, the present invention should not be limited this configuration. For example, the lead screw  14  of the seek motor  12  may be used as the guide bar  11   b . That is, instead of the guide bar  11   b , the lead screw  12  may be extended through the optical head  10  so as to serve as the guide bar  11   b . In this case, even though the distance from the objective lens  24  to the guide bar  11   b  on the seek motor  12  side is not decreased without using the mirror  31  between the semiconductor laser  18  and the collimator lens, the optical head  10  may be possibly located below the camera lens  2  and the view finder  3  without increasing the height of the camera housing  1 .  
         [0053]    According to the present invention, it is possible to aim at thinning the video camera using an optical disc.  
         [0054]    It should be further understood by those skilled in the art that although the foregoing description has been made on embodiments of the invention, the invention is not limited thereto and various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims.