Abstract:
A camera body includes a photographing lens. A barrier is supported on the camera body so as to be movable between a cover position covering the photographing lens and a retreat position retreated from the cover position in a first direction substantially parallel to an optical axis of the photographing lens and a second direction substantially perpendicular to the first direction. A rail mechanism is provided to guide relative movement between the camera body and the barrier in the first and the second directions of the barrier. The rail mechanism comprises a first slide projection, a second slide projection, a first cam portion and a second cam portion. The first slide projection has a predetermined projecting length and guides movement of the barrier. The second slide projection has a projecting length longer than the first slide projection and guides movement of the barrier. The first cam portion is slidably engaged with the first and the second slide projections and guides movement of the barrier in the second direction. The second cam portion, branched from the first cam means and slidably engaged with only the first slide projection, guides movement of the barrier in the first direction.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a camera, and particularly to a camera having a barrier movable along a rail mechanism between a position over a photographing lens and a position retreated from the photographing lens. 
     A compact camera having a barrier movable along a rail mechanism has been conventionally known. The purpose of the barrier is to protect the optical system, such as the photographing lens and the finder, when the camera is carried, and to cover the projecting portion to make the camera compact. 
     A number of camera makers have proposed a type of camera which has a barrier capable of simply moving linearly along a rail, a so-called “full barrier”. 
     Further, a camera having a barrier, called “a flat barrier”, is known as a more compact camera. The barrier of this type is movable along a rail mechanism also in a direction substantially parallel to the optical axis of the photographing lens, so that the front surface of the camera is flat when the barrier is closed. 
     For example, Jpn. UM Appln. KOKAI Publication No. 58-163938 discloses a camera which achieves the aforementioned objects by means of a barrier movable along a rail mechanism not only in the horizontal direction but also in the direction substantially parallel to the optical axis of the photographing lens. 
     The conventional camera of this type has a structure in which a barrier rail branches in the horizontal direction in front of the camera. While the barrier is traveling, a plurality of pins (claws) of the barrier are slid along the rail. 
     With the barrier rail having the basic structure described above, however, when the user is to manually slide the barrier, a pin of the barrier may be removed from a predetermined route of the rail while sliding, particularly, at a branch point of the rail. Otherwise, the pin may erroneously enter into another route. Thus, the barrier is easily caught in the rail. 
     In this state, even if the user simply continues the manual operation, the barrier cannot be moved successfully. 
     In this case, the user must first remove the barrier from the caught position by, for example, returning the barrier in the opposite direction, and then try to move it in the forward direction. 
     The conventional camera as described above has a problem in operation that the barrier cannot be moved successfully in only a single smooth operation. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention has been made to overcome the problem of the conventional art as described above, and an object of the present invention is to provide a camera having a compact and simple rail mechanism which can realize a successful barrier slide operation by a single smooth operation. 
     To achieve the above object, according to a first embodiment of the present invention, there is provided a camera comprising: 
     a camera body including a photographing lens; 
     a barrier supported on the camera body so as to be movable between a cover position covering the photographing lens and a retreat position retreated from the cover position in a first direction substantially parallel to an optical axis of the photographing lens and a second direction substantially perpendicular to the first direction; and 
     a rail mechanism for guiding relative movement between the camera body and the barrier in the first and the second directions of the barrier, 
     the rail mechanism comprising: 
     a first slide projection having a predetermined projecting length for guiding movement of the barrier; 
     a second slide projection, having a projecting length longer than the first slide projection, for guiding movement of the barrier; 
     first cam means, slidably engaged with the first and the second slide projections, for guiding movement of the barrier in the second direction; and 
     second cam means, branched from the first cam means and slidably engaged with only the first slide projection, for guiding movement of the barrier in the first direction. 
     According to another embodiment of the present invention, there is provided a camera comprising: 
     a camera body including a photographing lens and a rail formed of a shallow groove and a deep groove connected to each other; 
     a barrier supported on the camera body so as to be movable along the rail between a cover position covering the photographing lens and a retreat position retreated from the cover position; 
     a long projection provided on the barrier so as to be slidable along the rail and engageable with only the deep groove; 
     a short projection provided on the barrier so as to be engageable with both the deep groove and the shallow groove; and 
     urging means, elastically deformed when one of both ends of the barrier along a direction of movement of the barrier is brought into contact with the camera body, for urging the barrier so that the short projection can be inserted and removed from the shallow groove. 
     According to still another embodiment of the present invention, there is provided a camera comprising: 
     a camera body including a photographing lens; 
     a barrier supported on the camera body so as to be movable between a cover position covering the photographing lens and a retreat position retreated from the cover position in a first direction substantially parallel to an optical axis of the photographing lens and a second direction substantially perpendicular to the first direction; 
     a first slide projection having a short length formed on the barrier; 
     a second slide projection having a long length formed on the barrier; and 
     a rail for guiding movement of the barrier, 
     the rail comprising: 
     a common rail portion formed in the camera body, engaged in common with the first and the second slide projections, when the barrier is moved; 
     a first rail portion branched from a middle portion of the common rail portion and engaged with only the first slide projection; and 
     a second rail portion continuous to the common rail portion in a region where only the second slide projection can move, and engaged with the second slide projection. 
     According to a further embodiment of the present invention, there is provided a camera comprising: 
     a camera body including a photographing lens; 
     a movable barrier movable between a first position covering a front of the photographing lens, where the movable barrier and a front surface of the camera body are substantially on a same plane, and a second position retreated from the front of the photographing lens and projected from the front surface of the camera body to expose the photographing lens; 
     a long pin and a short pin, arranged in line with an axis of movement of the movable barrier and crossing an optical axis of the photographing lens, the long pin being closer to the photographing lens than the short pin; 
     a first cam groove, engaged with the long pin and bent so that the movable barrier comes closer to the photographing lens via the long pin, when the movable barrier moves from the second position to the first position; 
     a contact portion brought into contact with a distal end portion of the movable barrier when the movable barrier approaches the first position along the first cam groove; 
     a second cam groove, shallower than the first cam groove and branched from the first cam groove, for guiding the short pin together with the long pin engaged with the first cam groove, so that the movable barrier can be positioned at the first position. 
     According to a still further embodiment of the present invention, there is provided a camera comprising: 
     a camera body including a photographing lens; 
     a movable barrier movable between a first position covering a front of the photographing lens, where the movable barrier and a front surface of the camera body form a substantially flat surface, and a second position retreated from the front of the photographing lens and projected from the front surface of the camera body to expose the photographing lens; 
     a guide surface for guiding side surfaces of the movable barrier; 
     a cam groove bent so that the movable barrier is movable with respect to the guide surface between the first position and the second position; 
     a long pin and a short pin, engaged with the cam groove and arranged in line with an axis of movement of the movable barrier, the long pin being closer to the photographing lens in the axis of movement of the movable barrier; and 
     a contact portion brought into contact with a distal end portion of the movable barrier when the movable barrier moves from the second position to the first position; 
     wherein the cam groove comprises: 
     a first groove portion engaged with the long pin, when the movable barrier moves from the second position to the first position; and 
     a second groove portion, having a depth smaller than a length of the long pin and branched from the first groove portion, provided to be engaged with the short pin when the movable barrier is brought into contact with the contact portion. 
     Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention. 
     FIG. 1 is a perspective view of a camera according to a first embodiment of the present invention in which the barrier is closed; 
     FIG. 2 is a perspective view of a camera according to the first embodiment in which the barrier is opened; 
     FIG. 3 is an exploded perspective view of a camera according to the first embodiment; 
     FIG. 4 is a cross-sectional view of a main part of a case relating to the barrier; 
     FIG. 5 is an enlarged view of the main part relating to the barrier shown in FIG. 4; 
     FIG. 6 is a perspective view of a camera according to a second embodiment of the present invention in which the barrier is closed; 
     FIG. 7 is a perspective view of a camera according to the second embodiment in which the barrier is opened; and 
     FIG. 8 is an exploded perspective view of a camera according to the second embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the presently preferred embodiments of the invention as illustrated in the accompanying drawings, in which like reference characters designate like or corresponding parts throughout the several drawings. 
     First Embodiment 
     FIG. 1 is a perspective view of a camera according to a first embodiment of the present invention. 
     FIG. 1 shows a closed state of a barrier  30  seen obliquely from above the camera. 
     The camera has a wall member called “a flat barrier” slidably mounted on a front cover so as to be closed when the camera is not used. This barrier structure covers a main optical system of the camera, thereby forming a flat front surface which is safe and convenient to carry. 
     The camera comprises a front cover  10 , a barrier  30 , a barrier ornament  35 , a cover  40 , a rear cover  50  and a shutter button  80 . The front cover  10  covers a camera body  1  from the front. The barrier  30  is attached to the front surface of the camera body  1  so as to be movable in the directions indicated by the arrows, to shield an optical system such as a photographing lens  60  mounted on the camera body  1 . The barrier ornament  35  is attached to an end portion of the front surface of the barrier  30  along the vertical direction and projected forward, so that the user can slide the barrier  30  in the directions of the arrows by a finger. The cover  40  covers the front of, for example, a region held by the right hand of the user. The rear cover  50  covers the overall main portion of the camera from the side opposite to the front cover  10 . The shutter button  80  slightly projects upward above a right portion of the upper surface of the front cover  10 . 
     It is understood from FIG. 1 that, when the barrier  30  is closed, a front surface of the front cover  10  having a 90°-turned U shape, the cover  40  and the barrier  30  form a flat surface of the same level, as described above. 
     FIG. 2 is a perspective view of a camera according to the first embodiment in the case where the barrier  30  shown in FIG. 1 is opened. 
     When the barrier is slid by pressing the barrier ornament  35  leftward in the drawing, a power supply (not shown) is turned on in association with the slide movement, thereby supplying power to the camera body  1 . As a result, as shown in FIG. 2, a lens barrel of the photographing lens  60  hidden behind the barrier  30  projects forward along the optical axis and a finder  65  is exposed. 
     At this time, the barrier  30  is slid along barrier pin traveling grooves  15 , which are provided in upper and lower interior edge portions  17  of the front cover  10 . Each of the upper and lower barrier pin traveling grooves  15  has a predetermined form and predetermined two levels of depth. 
     A plurality of pins  31 ,  32 ,  33  and  34  are projected from inner portions of the barrier  30  (see FIG.  3 ). These pins are inserted in and travel along the barrier pin traveling grooves. 
     When the closed barrier  30  is slid to the left in the drawing, the barrier  30  is at first moved forward smoothly along the optical axis by a predetermined amount from the flat state, with the inner surface of the right end of the barrier  30  being kept in contact with a contact portion  16 . 
     Thereafter, the barrier  30  is moved parallel with the front surface of the camera body, keeping a predetermined distance from the initial flat state, and finally stopped at the left end of the camera body  1  so as to completely cover the front surface of the cover  40 . 
     Only after this state, the shutter button  80  can function to allow a photographing operation. 
     FIG. 3 is an exploded perspective view of a camera according to the first embodiment of the present invention. 
     Structures of the parts of the camera of the present invention will be described in detail with reference to FIG.  3 . The front cover  10  has a plurality of openings. 
     More specifically, the front cover  10  has an opening  11  for the photographing lens, through which the lens barrel of the photographing lens  60  is inserted so as to be movable along the optical axis. Further, it has an opening  12  for the finder corresponding to the position of the finder  65 , an opening  13  for a wall member (described later) to which a wall member  20  is attached, and an opening  14  for the shutter button through which the shutter button  80  is loosely inserted. 
     The barrier pin traveling groove  15  has two levels of depth, i.e., a shallower portion and a deeper portion. It further includes first and second branched cam means as will be described below. Thus, the barrier pin traveling groove  15  is constituted by four groove portions: grooves  15   a ,  15   b ,  15   c  and  15   d.    
     In a plan view, the deep groove (the longest groove, hereinafter referred to as the parallel groove)  15   b  extends parallel with the front surface of the cover  10  from an approximately left end of the camera body  1  to a middle portion of the lower interior edge portion  17 . The shallow groove (oblique groove)  15   a  is branched from the parallel groove  15   b  and extends obliquely backward. The deep groove (oblique groove)  15   c  is branched from the right end of the parallel groove  15   b  and extends backward parallel with the oblique groove  15   a . The deep groove (oblique groove)  15   d  forms the distal end portion of the oblique groove  15   c.    
     The deep grooves and the shallow grooves have depths respectively corresponding to the lengths of the long pins  31  and  32  and short pins  33  and  34  of the barrier  30 . The short pins  33  and  34  constitute a first sliding projection and the long pins  31  and  32  constitute a second sliding projection, as will be described later. 
     The contact portion  16  is a slightly projected portion having a trapezoidal cross section. The surface of the contact portion  16  is smoothed. 
     Like the barrier pin traveling groove  15  formed in the lower interior edge portion  17  as described above, a branched barrier pin traveling groove  15  is also formed in the upper interior edge portion, as indicated by a broken line. 
     A side wall  10   a  has two holes h 1  and h 2 . A partition wall  10   b  is formed in the vertical direction between the upper and lower interior edge portions  17  of the front cover  10  to the left of the center of the camera in the drawing. The partition wall  10   b  have two holes h 3  and h 4 . Thus, the two walls have the four holes h 1  to h 4 . 
     The four holes h 1 , h 2 , h 3  and h 4  respectively correspond to attachment holes  24 ,  25 ,  22  and  23  for attaching a wall member  20  (described below) to the walls  10   a  and  10   b.    
     The wall member  20  has the attachment holes  22  to  24  in four corner portions and a boss hole  21  made through a portion near the central thereof. 
     In the wall member  20 , a rectangular region formed in a central portion thereof is thicker than edge portions in which the attachment holes are made. 
     The wall member  20  is attached from the rear side of the opening  13  for the wall member of the front cover  10 , so that the opening  13  is closed by the rectangular region of the wall member  20 . 
     The wall member  20  is fixed to the partition wall  10   b  and the side wall  10   a  by screwing fixing screws  72   a ,  72   b ,  73   a  and  73   b  (see FIG. 4) into the four holes h 3 , h 4 , h 1  and h 2 . 
     The partition wall  10   b  and the side wall  10   a  respectively have positioning holes  18  and  19  for determining the position of the cover  40  as will be described later. 
     The barrier  30  has a shape approximate to the U shape of the recess formed in the front surface of the front cover  10 . The length in the longitudinal direction of the barrier  30  plus the cover  40  is the same as the length of the recess. 
     Further, as shown in FIG. 3, the barrier  30  has four edge portions  30   a ,  30   b ,  30   c  and  30   d  slightly projecting in the thickness direction of the barrier. Long and short cylindrical barrier pins  33 ,  34 ,  31  and  32  are projected from the edge portions in the vertical direction. The barrier pins  33  and  34  constitute a first slide projecting portion and the barrier pins  31  and  32  constitute a second slide projecting portion. 
     The barrier  30  has the barrier ornament  35  projected forward in a left end portion of the surface. 
     When the barrier  30  is closed and fitted in the recess of the cover  10 , the surface of the camera body  1  is flat as a whole together with the front cover  10  and the cover  40 . 
     The cover  40  has a boss  41  near the center of the rear surface thereof. A bottomed small hole  41   a  is formed in the center of the boss  41 . 
     Positioning pins  42  and  43  are projected from two end portions on a diagonal of the rear surface of the cover  40 , as shown in FIG.  3 . 
     The cover  40  is located at a portion usually held by the right hand of the user, and covers the front right portion of the camera body  1 , when the barrier  30  is closed. Therefore, it is preferable that the cross section of the cover  40  taken in the longitudinal direction be substantially trapezoidal, having obtuse corners. 
     FIG. 4 is a cross-sectional view of the front cover  10  having the above barrier  30   e.    
     When the elements described above are assembled, the barrier  30  is inserted in the opening  13  from the inner side of the front cover  10  so as to be in front of the front cover  10 , before the rear cover  50  shown in FIGS. 1 and 2 is fitted to the front cover  10 . 
     At this time, the barrier pins  31  and  32  are inserted in the barrier pin traveling grooves  15 , so that the barrier  30  is slid to the position in front of the opening  11  for the photographing lens. Further, the barrier pins  33  and  34  are inserted in the barrier pin traveling grooves  15 . 
     Then, the barrier  30  is completely closed. Thereafter, the boss  41  of the cover  40  is inserted in the boss hole  21  of the wall member  20 , such that the front cover  20  is sandwiched between the cover  40  and the wall member  20 . 
     At this time, the cover  40  is positioned with respect to the cover  10  by inserting the positioning pins  42  and  43  on the diagonal line of the rear surface of the cover  40  into the positioning holes  18  and  19  formed in the partitioning wall  10   b  and the side wall  10   a  of the front cover  10 . 
     A boss screw  71 , such as a self-tapping tight screw, is screwed into the bottomed small hole  41   a  formed in the boss  41  of the cover  40  from the rear side. As a result, the wall member  20  and the cover  40  are fixed to each other with the front cover  10  sandwiched therebetween. 
     Thus, the front portion of the camera body  1  is assembled. 
     The barrier pin traveling grooves  15  formed in the front cover  10  will now be described in detail with reference to FIG.  4 . 
     The parallel groove  15   b  extends, in the horizontal direction, from the neighborhood of the position where the wall member  20  is fixed by the fixing screws  73   a  and  73   b  to the position before the center of the opening  11  for the photographing lens. At this position, the deep parallel groove  15   b  is continuous to the oblique groove  15   c  of the same depth which forms an angle of about 300 to 45° with the groove  15   b , and then to the oblique end groove  15   d  at the distal end of the same depth. 
     It is understood from the cross-sectional view of FIG. 4 that the oblique end groove  15   d  reaches a portion near the center of the opening  11  for the photographing lens in the horizontal direction. 
     The oblique groove (shallow groove)  15   a , branched from the parallel groove  15   b , extends substantially parallel with the oblique groove  15   c  from the neighborhood of the position where the wall member  20  is fixed by the fixing screws  72   a  and  72   b . The length of the oblique groove  15   a  is substantially the same as that of the oblique groove  15   c.    
     It is also understood from the cross-sectional view of FIG. 4 that the contact portion  16  is slightly projected in the direction along the optical axis. 
     As described above, when the wall member  20  and the cover  40  are attached to the front cover  10  from the front and the rear sides, gaps are formed between the front cover  10  and the upper and the lower sides of the cover  40 . The four edge portions projecting in the thickness direction of the barrier  30  can travel horizontally along the gaps. 
     At this time, the long pins  31  and  32  and the short pins  33  and  34  are slid in the barrier traveling grooves  15 . 
     FIG. 5 is an enlarged view of the characteristic part relating to the barrier  30  shown in FIG.  4 . 
     The following is a more detailed explanation of the barrier pin traveling groove  15  and the long pins  31  and  32  and the short pins  33  and  34  of the barrier  30  which travel along the barrier pin traveling grooves  15 . 
     The shallow oblique groove  15   a  of the barrier pin traveling groove  15  is branched from a middle portion of the longest deep groove  15   b  extending parallel with the front surface of the camera body  1 . 
     The parallel groove (deep groove)  15   b  is continuous to the oblique groove  15   c  of the same depth extending in the direction substantially parallel to the oblique groove  15   a . The oblique groove  15   c  is continuous to the oblique end groove  15   d  extending substantially parallel to the groove  15   b.    
     The barrier pin (long pin)  32  of the barrier  30  travels straight from the neighborhood of the partition wall in the parallel groove (deep groove)  15   b . It changes the direction of travel, proceeds into the oblique groove (deep groove)  15   c , and stops in the oblique end groove (deep groove)  15   d.    
     In the same manner, the barrier pin (long pin)  31  is slid along the barrier pin traveling groove  15  provided in the upper edge of the front cover  10 . 
     The barrier pin (short pin)  34  first travels in the parallel groove (deep groove)  15   b . After passing the partition wall, it enters into the oblique groove (shallow groove)  15   a  branched from the parallel groove  15   b  and stops at the distal end of the groove  15   a.    
     In the same manner, the barrier pin (short pin)  33  is slid along the barrier pin traveling groove  15  provided in the upper edge of the front cover  10 . 
     At this time, as indicated by the broken line in FIG. 5, the surface of the barrier  30  is slightly inclined to the direction substantially parallel to the optical axis of the photographing lens  60  (shown in FIG.  2 ), with the lowermost end of the barrier  30  being kept in contact with the contact portion  16 . 
     The pins  34  and  32  of the barrier  30  enter the corresponding oblique grooves  15   a  and  15   c . At this time, the contact point in the contact portion  16  serves as a fulcrum for “a single-point support”. 
     As a result, the barrier  30  also moves in the direction substantially parallel to the optical axis of the photographing lens  60  (shown in FIG.  2 ). At the position where the barrier  30  finally stops, the front surface of the camera body  1  is flat. 
     In an actual barrier closing operation by a finger of the user, at the same time that lateral force F 1  for sliding the barrier in the lateral direction acts, pressing force F 2  for pressing the barrier in the direction of the optical axis acts. 
     The resultant force F at this time causes the barrier  30  to be pressed from the front so as to be integrated with the front surface of the cover  10 . 
     Thus, when the recess of the front cover  10  is completely closed by the barrier  30 , the front surface of the camera body  1  becomes flat. 
     As described above, according to the first embodiment of the present invention, the front cover has a rail structure having shallow and deep grooves continuous at a stepped branch point. Further, the first embodiment is characterized in that the barrier has long pins (inner pins) of such a length as to be prevented from entering the shallow groove at the stepped point and allowed to enter only in the deep groove, and short pins (outer pins) of such a length as to be allowed to enter both the deep and shallow grooves. 
     In the operation of closing the barrier by the combination of the front cover and the barrier, when the short pin is located at the branch point, force is applied so that the distal end of the barrier elastically functions as a spring, and the short pins smoothly enter the shallow grooves without fail. 
     As described above, the purpose of providing the distal end of the barrier with the elastic function is to insert the short pins in the shallow grooves without fail. However, the distal end of the barrier does not necessarily have the elastic function, if the dimensions are precise. 
     In short, the barrier has the combination of two kinds of pins different in length and the rail including two kinds of grooves different in depth. With this combination, it is possible to realize a camera in which the pins can travel smoothly along the grooves of the predetermined depths without being caught by the rails. 
     Although the above description mainly relates to the process of closing the barrier to be flat, the barrier  30  can be smoothly moved in the opposite direction to an open state. In the opening operation also, the combination of the characteristic barrier  30  and the barrier pin traveling grooves serving as rails and the elastic force of the distal end of the barrier function in the same manner as described above, that is, the correct barrier pins are selected at the branch points, so that the barrier can be moved smoothly in the direction along the optical axis and then travel along the rails smoothly without being caught by the rails. 
     As described above, according to the first embodiment of the present invention, it is possible to provide a camera having a compact and simple rail mechanism which can realize a successful barrier slide operation by a single smooth operation. 
     Second Embodiment 
     A second embodiment of the present invention will now be described. 
     The second embodiment is different from the first embodiment in the positions of the grooves and the positions of the pins. Since the other portions of the second embodiment are the same as those of the first embodiment, descriptions thereof will be omitted. 
     FIG. 6 is a perspective view of a camera according to the second embodiment, particularly showing a closed state of a barrier  30  seen obliquely from above the camera. 
     In the closed state, the camera of the second embodiment has substantially the same elements as those of the first embodiment. However, the second embodiment differs from the first embodiment in the following respects. 
     First, a barrier  30  movably attached in front of a camera body  1  has no barrier ornament, and the cross section taken along the vertical direction is channel-shaped. 
     Secondly, the front surface of the camera body  1  is completely flat. 
     FIG. 7 is a perspective view of the camera shown in FIG. 6 in the case where the barrier is opened. 
     In this case, when the barrier  30  is slid leftward in the drawing with the upper and the lower sides held between fingers of the user, the power supply (not shown) is turned on. As a result, as shown in FIG. 7, the lens barrel of a photographing lens  60  hidden behind the barrier  30  projects forward along the optical axis and the finder  65  is exposed. 
     At this time, the barrier  30  is slid along barrier pin traveling grooves  15 , which are provided in upper and lower interior edge portions  17 ′ of the front cover  10 . 
     As in the first embodiment, each of the upper and lower barrier pin traveling grooves  15  has a predetermined form and predetermined two levels of depth. 
     Two pairs of long and short pins are projected from inner portions of the barrier  30  (for details, see FIG.  8 ). The pins are inserted in and travel along the barrier pin traveling grooves  15 . 
     When the closed barrier  30  is slid to the left, the barrier  30  is at first moved forward smoothly along the optical axis by a predetermined amount from the flat state, with the inner surface of the right end of the barrier  30  being kept in contact with a contact portion  16 . 
     Thereafter, the barrier  30  is moved parallel, keeping a predetermined distance from the initial flat state, and finally stopped at the left end of the camera body  1  so as to completely cover the front surface of the cover  40 . 
     Only after this state, the shutter button  80  can function to allow a photographing operation. 
     FIG. 8 is an exploded perspective view showing the relationship between the barrier and the front cover  10  of the camera body  1  according to the second embodiment. 
     Referring to FIG. 8, as in the first embodiment, the front cover  10  has an opening  11  for the photographing lens, an opening  12  for the finder and an opening  14  for the shutter button, through which the lens barrel of the photographing lens  60 , the finder  65 , and the shutter button  80  are respectively inserted. 
     The projected contact portion  16  is arranged in the recess portion of the front cover  10  in the same manner as in the first embodiment. 
     In the second embodiment, the barrier pin traveling grooves  15  are arranged symmetrically in the upper and lower interior edge portions  17 ′. 
     The cover  40  is formed integrally with a front left portion of the front cover  10  as one piece. 
     As shown in FIG. 8, the barrier pin traveling groove  15  comprises an oblique groove (shallow groove)  15   a , a parallel groove (deep groove)  15   b , an oblique groove (deep groove)  15   c , and an oblique groove (deep groove)  15   d , as in the first embodiment. 
     The formal characteristic of the barrier  30  is understandable from FIG.  8 . The barrier pin (long pin)  31  and the barrier pin (short pin)  33  are projected downward from the upper edge portion of the barrier  30 . The barrier pin (long pin)  32  and the barrier pin (short pin)  34  are projected upward from the lower edge portion of the barrier  30 . 
     When a camera body is assembled, the barrier  30  is attached to the cover  40  so as to overlap it. At this time, the long pins  31  and  32  are first inserted in the barrier traveling grooves  15 . Thereafter, the short pins  33  and  34  are inserted therein following the long pins. 
     As a result, the barrier  30  can be freely slid along the grooves rightward in the drawing. 
     As described above, the second embodiment of the present invention has a simpler structure and a less number of members as compared to the first embodiment. For example, the positioning holes, the wall member, the boss hole, the attachment holes, the barrier ornament, etc., are not required in the second embodiment. 
     Further, the same effect and advantage as those of the first embodiment can be obtained by the barrier traveling grooves  15  formed in the upper and lower edge portions  17 ′ of the front cover  10  and the barrier having a channel-shaped cross section along the vertical direction. 
     Furthermore, the barrier and the cover can be worked easily due to the simple shape, and assembled easily and firmly by utilizing the elastic force of the material of the barrier. 
     If the barrier  30  is opened and closed reliably and smoothly without using the contact portion  16  in the front cover  10 , the contact portion  16  need not be formed. 
     Thus, according to the second embodiment, it is possible to provide a camera comprising a barrier which has a simple and compact rail structure. 
     Other Modifications 
     The limitations of the camera relating to “left and right”, “in and out”, and “upper and lower” are not necessarily restricted to those of the embodiments described above. 
     Further, the present invention is applicable not only to a compact camera but to any type of camera. 
     In the above description, the barrier pin grooves, the shallow grooves and the deep grooves are not necessarily bottomed grooves. It is easily conceivable that they may be replaced by cams or cam means with which a projecting member can be engaged. 
     As has been described above in detail, the present invention can provide a camera having a compact and simple rail mechanism which can realize a successful barrier slide operation by a single smooth operation. 
     Additional embodiments of the present invention will be apparent to those skilled in the art from consideration of the specification and practice of the present invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope of the present invention being indicated by the following claims.