Abstract:
An interchangeable lens camera including a lens barrel and a camera body. The lens barrel is attached to the camera body via a body side mount and a lens side mount. The lens barrel mounting mechanism, including the body side mount and the lens side mount, is capable of moving along the optical axis of the camera so as to move from a position where the lens barrel is completely collapsed within the camera body to a position where the lens barrel is fully extended for zoom photography. The shortest state of the camera is when the lens barrel is detached from the camera. The lens barrel includes a set tube that is movable along the optical axis, lens units for focusing light onto a film in the camera body, and lens protection elements that open or close depending upon the state of the lens barrel, i.e., detached or attached, collapsed or extended. The camera body includes a control circuit that controls the movement of the lens barrel based upon the state of several switches, some of which are located in the lens barrel.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of Ser. No. 08/686,361 filed Jul. 25, 1996, abandoned. 
     This application is based upon and claims priority from Japanese Patent Application No. 07-189059 filed Jul. 25, 1995, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an interchangeable lens camera with a lens barrel detachably disposed in a camera body, and in particular, it relates to a mounting device for a lens barrel in an interchangeable lens camera which can detachably mount, and in addition cause to collapse, the interchangeable lens barrel in the camera body. 
     2. Description of the Related Art 
     In interchangeable lens cameras, generally, the lens barrel is mounted to be freely detachable with respect to the camera body. A screw-in type lens barrel attached by a screw mount is known as is a detachably spring-mounted type lens barrel attached by a bayonet mount. 
     Namely, in the screw-in type lens barrel, the structure was such that screw portions were disposed on the lens receiving aperture portion of the camera body and the rear end side of the lens barrel. The lens barrel (interchangeable lens) was caused to rotate by causing both screw portions to engage and be joined, and thus, it was freely detachable with respect to the camera body. 
     In the spring-mounted type lens barrel, the structure was such that the lens barrel, by causing rotary movement in a predetermined angular direction with respect to the camera body, was also freely detachably mounted. 
     In interchangeable lens cameras with such an interchangeable type lens barrel that is freely detachably mounted in the camera body, a small size, light weight design is also known in which the lens barrel collapses within the camera body. For example, such a camera is disclosed in Japanese Laid-Open Patent Publication JPA-56-91224. 
     In this interchangeable lens camera, the lens barrel is freely detachably disposed in a mounting unit on the front surface side of the camera body. Also, this lens barrel is formed so as to move back and forth along the optical axis direction with respect to this mounting unit. In this camera, in order to make the lens barrel capable of extension within the camera body, a lens type shutter is adopted. In addition, in the forward direction of the film surface within the camera body, when movement of the lens barrel lead to removal thereof, for example opening and closing by coupling the lens barrel during rotation of a bayonet coupling, a screening plate device is disposed to screen off the light path towards the film surface. 
     Then, the construction was to cause collapsing, causing this screening plate device to pass through, leaving this screening plate device open, coupling by rotary movement during mounting of the lens barrel to the camera body, and also to cause the lens barrel to move extending on the film surface side along the optical axis direction. 
     However, in the above interchangeable lens cameras, the mounting member of the lens barrel had to be formed in the outer circumferential portion of the lens barrel which was the front surface portion of the camera body. In particular, not only did it become a hindrance to obtain a good external appearance, but the drive mechanism of the lens barrel became unnecessarily large due to the fact that the mounting member was larger than the diameter of the lens barrel. As a result, this construction has become an obstacle to miniaturization. 
     Because of this, it was desirable to adopt measures for improving the mounting unit structure for the camera body side, making the lens barrel freely detachably interchangeable, thus bringing about an improvement in the external appearance of the camera, and in addition, allowing the camera to be designed with a smaller size. 
     For example, in a known detachable lens camera, it is known for the mounting unit of the lens barrel to be movable back and forth in the optical axis direction within the camera body. However, such a camera causes a photographic lens focusing action by movement in the optical axis direction while rotating the mounting unit itself, thus requiring a special mechanism in order to cause the lens barrel to move in the optical axis direction. This requirement complicates the structure. 
     Moreover, in such a structure, the external appearance was excellent when the mounting unit of the lens barrel was assembled in the camera body. However, because the mounting unit itself rotated when moving in the optical axis direction, there was a problem that the transmission of motive power or the transmission of electrical signals between the camera body and the lens barrel was difficult. The problem had to be taken into account for improving the mounting unit structure. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to overcome the above problems of the above known cameras. 
     It is also an object of the present invention to obtain an interchangeable lens camera which is designed for a small-sized camera body, and which can simply and accurately mount a lens barrel to a camera body. 
     Furthermore, another object of the present invention is to provide an interchangeable lens camera having a lens barrel that can collapse within the camera body by a movement along the optical axis direction, without limitation to the external appearance of the camera. 
     Objects of the present invention are achieved by an interchangeable lens camera comprising a mounting device for interchangeably mounting a lens barrel on a camera body, the mounting device being disposed to prevent rotation about an optical axis and to move back and forth in an optical axis direction, and the mounting device, by moving in the optical axis direction, receiving the lens barrel in the camera body. 
     Still further objects of the present invention are achieved by an interchangeable lens camera comprising a camera body, a lens barrel with focusing lenses, a first mounting device disposed in the lens barrel, and a second mounting device disposed in the camera body, wherein the first and second mounting devices act to mount the lens barrel to the camera body and to electrically and mechanically connect the lens barrel and the camera body, and wherein the lens barrel is movable along an optical axis of the focusing lenses so as to be movable from a first fully collapsed position where the lens barrel is fully collapsed within the camera body to a second fully extended telephoto position. 
     Objects of the present invention are also achieved by an interchangeable lens camera wherein a lens barrel mounting device is prevented from rotating around the optical axis within the camera body, and is movable in the optical axis direction. When the lens barrel is in a state in which it has moved as far as an extended position in the camera body, in this state a retracting movement of the mounting device is caused by movement back and forth in the camera body. An electrical drive member of a lens barrel side and a control circuit of the camera body side are electrically connected by causing the mounting device to move as far as the collapsed position. 
     Moreover, objects of the present invention are also achieved by an interchangeable lens camera which allows the lens barrel mounting device to move linearly as far as an extended position along the optical axis direction within the camera body. Also, the shortest length of the camera is when the lens barrel is detached from the camera body. 
     Furthermore, at the time of removal of the lens barrel from the camera body, a lens protection member, which opens and closes a photographic optical path at the front surface side of the lens barrel, is closed. 
     The lens barrel mounting device is for example constituted by a body side mount and a lens side mount. Moreover, the back and forth movement, for example, is accomplished by a set tube. Furthermore, the electrical mechanism units on the camera body side are, for example, a control circuit or units connected to the control circuit, motors used for focus drive, and a zooming motor. As mechanical mechanism units, there are, for example, coupling gears for use in zoom driving. 
     Moreover, a shutter and a focusing drive unit, which are connected via an electrical transmission device by connection pins and the like formed of electrically conductive materials, serve as the electrical drive members within the lens barrel. Furthermore, the lens protection member, for example, is formed of a light shielding plate disposed in an aperture portion of the camera body. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects, features, and characteristics of the present invention, along with methods of operation and manufacture, will become apparent to one skilled in the art from a study of the following detailed description and the appended claims and drawings, all of which form a part of this specification. In the drawings: 
     FIG. 1 is a schematic cross sectional diagram showing a camera according to a preferred embodiment of the present invention in a state with a lens barrel received within a camera body; 
     FIG. 2 is a schematic cross sectional diagram showing a camera according to a preferred embodiment of the present invention in a state with the lens barrel removed from the camera body; 
     FIG. 3 is a schematic cross sectional diagram showing a camera according to a preferred embodiment of the present invention in a state with the lens barrel mounted by a rotar, bayonet coupling in the camera body; 
     FIG. 4 is another schematic cross sectional diagram showing a camera according to a preferred embodiment of the present invention in a state with the lens barrel mounted by a rotary bayonet coupling in the camera body; 
     FIG. 5 is a schematic oblique diagram showing the relationship of a detachment knob of a lens, barrel and a light screening device, in the preferred embodiment of the present invention; 
     FIG. 6 is a schematic oblique diagram showing the state when, operating the detachment knob in the lens mounting position, the light screening device operates to open, in the preferred embodiment of the present invention; 
     FIGS. 7 a  and  7   b  are schematic diagrams showing the relationship of a phase of a cam groove of a set tube in the lens barrel and an inclined cam surface of the detachment knob, wherein FIG. 7 a  is an oblique diagram of the set tube, and FIG. 7 b  is an oblique diagram of the inclined cam surface; 
     FIG. 8 is a perspective oblique view, partially cut away, illustrating the movement of a barrier opening and closing mechanism disposed in the lens barrel in an interchangeable lens camera according to a preferred embodiment of the present invention; 
     FIG. 9 is a perspective oblique view showing the state when the barrier opening and closing mechanism mounted on the lens barrel is opened, in an interchangeable lens camera according to a preferred embodiment of the present invention; 
     FIG. 10 is a cross sectional view showing the barrier opening and closing mechanism of FIG. 8, enlarged, in an interchangeable lens camera according to a preferred embodiment of the present invention; 
     FIG. 11 is a cross sectional view showing the barrier opening and closing mechanism of FIG. 8, enlarged, in an interchangeable lens camera according to a preferred embodiment of the present invention; 
     FIG. 12 is a diagram showing the relationship of engagement portions, which are disposed in a lens side mount and a leg in order to cause opening and closing action of a barrier in the barrier opening and closing mechanism of FIG. 8, in an interchangeable lens camera according to a preferred embodiment of the present invention; 
     FIGS. 13 a - 13   c  are diagrams showing the relationship of a zoom position detection switch in the lens barrel in an interchangeable lens camera according to a preferred embodiment of the present invention, wherein FIG. 13 a  shows the collapsed state, FIG. 13 b  shows the state at the Wide end, and FIG. 13 c  shows the state at the Tele end; 
     FIG. 14 a  is a bottom view of an interchangeable lens camera according to a preferred embodiment of the present invention showing the detachment knob which acts jointly as a power supply switch; 
     FIG. 14 b  is a table showing the relationship between positions shown in FIG. 14 a  and the state of switches SW 1  and SW 2  in the interchangeable lens camera according to a preferred embodiment of the present invention; and 
     FIG. 15 is a block diagram illustrating a control circuit in an interchangeable lens camera according to a preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1-4 show the configuration of a preferred embodiment of an interchangeable lens camera according to the present invention. In these Figures, FIG. 1 shows the state in which the interchangeable type lens barrel is received within a camera body. FIG. 2 shows the state in which the interchangeable lens barrel is extended from the camera body. FIG. 3 shows the state at the time at which the same interchangeable type of lens barrel, mounted by a generally widely known bayonet coupling of the camera body side, is caused to rotate. FIG. 4 shows the state when zooming has operated from the state of FIG.  1 . 
     In these Figures, camera body  1 , of which only a portion is shown in the Figures, has an integral guide tube  2  which constitutes a lens barrel holding unit set in the optical axis direction in the camera central portion. A guide groove  2   a  is formed along the optical axis direction in a portion of a guide tube  2 . The guide groove  2   a  is such as to guide only in the optical axis direction a follower pin  3   a  of a mount  3  on the camera body side which constitutes a mounting device of the lens barrel disposed freely moveable along the optical axis direction in the internal circumference of the guide tube  2 . 
     Set tube  4 , fitted for free rotation on the outer circumference of the guide tube  2 , is disposed such that movement in the optical axis direction is regulated by a fixed ring  5 . A cam groove  4   a  is formed in the inner circumference of this set tube  4 , connected via the guide groove  2   a  with the end of the follower pin  3   a . This cam groove  4   a , for example as shown in FIG. 7 a , in the inner circumference of set tube  4  in the optical axis direction, is formed with a portion having a predetermined inclination and a portion at right angles to the optical axis. 
     Then, by use of the engagement of the guide groove  2   a  with the follower pin  3   a  and cam groove  4   a , the follower pin  3   a  moves along the cam groove  4   a , extending and retracting in the optical axis direction. 
     Aperture  1   a  denotes an aperture portion formed in a center portion back surface side of the camera body  1 . Film  6  is a photosensitive material which travels along a film travel path of this back surface side. Pressure plate  7  supports the back surface side of the film  6 . 
     Coupling gear  8  is used in zoom driving, and is a mechanical unit disposed in the camera body side, which has been located in a portion of the back surface side of the body side mount  3  by the rim portion of the aperture portion  1   a . Coupling gear  8  is in gear engagement with an electric motor (not shown in the drawing), and is constructed to transmit the rotational force of this motor to a cam tube (described hereinafter) of a lens barrel  30 . A coupling side end  8   a  of the lens barrel side of the coupling gear  8  connects into a hole portion  3   b  (FIG.  2 ), which is formed in the camera body side mount  3 . Coupling gear  8  is constructed so as to perform rotational transmission, in engagement with a coupling gear  42  (described hereinafter) of the lens barrel side. 
     Connecting pin  9  is formed of an electrically conductive material and comprises an electrical transmission circuit that performs transmission of electrical control signals between the camera body  1  and the lens barrel  30 . The connecting pin  9  is located in a position which has been displaced in the circumferential direction with respect to the coupling gear  8 , and is used for zoom driving of the body side. The connecting pin  9  is formed so as to perform electrical connection with a lens side mount (described hereinafter) of the lens barrel. The end of pin  9  penetrates a hole portion  3   c  formed in the body side mount  3 . Moreover, the base end portion of connecting pin  9  connects to an electrically conductive spring  10 . Pin  9  is connected via this electrically conductive spring  10  to a control circuit  11  disposed at a suitable position within the camera body cover  19  by a flexible printed wiring board  12 . 
     Light screening device  13  is disposed facing the peripheral portion of the aperture portion  1   a  of the camera body  1 . Details of this structure are shown in FIGS. 5 and 6. 
     As shown in FIG. 2, plural light screening plates  14 ,  15 ,  16  (three plates in this embodiment), moveable to open and closed positions, have been located in front of the aperture  1   a  in order to screen light from the film  6 . These screening plates  14 ,  15 ,  16  are respectively actuated in an up and down direction in the Figures, accompanying the ring motion of opening and closing legs  17 ,  18  (FIG. 5 et seq.). Opening and closing legs  17  and  18  form two parallel rings which are coupled to screening plates  14 ,  15 , and  16  via pivots  14   a ,  15   a ,  16   a ,  14   b ,  15   b ,  16   b , to open and close the aperture portion  1   a . Moreover, in the Figures, pivot shafts  17   a ,  18   a  are connected to the camera body  1  side of the opening and closing legs  17 ,  18 . 
     In this manner, the opening and closing of the screening device  13  is performed by a detachment knob  20  located for undisturbed sliding operation in the lower portion of the camera as shown in FIG.  1  and FIG. 14 a . The detachment knob  20  is constructed as a sliding switch for undisturbed sliding operation in the camera bottom, namely the bottom portion of the camera body cover  19 . Knob  20  also functions as a power supply switch knob which is the camera main switch. 
     With reference to FIGS. 1,  5  and  6 , the detachment knob  20  has a support portion  21  which has an inclined cam surface  21   a  contacting a follower pin  17   b  disposed on the leg  17 , which is one side of the opening and closing legs  17 ,  18 . A tension spring  22  is then mounted to exert an urging force such that, in the opening and closing leg  17 , the follower pin  17   b  is in a normally pressing contact state on the inclined cam surface  21   a.    
     In such a construction, when the detachment knob  20  is moved, for example, in the direction of the arrow in FIG. 5, the follower pin  17   b  moves correspondingly along on the inclined cam surface  21   a  of the support portion  21  upper end, and rotates the opening and closing arms  17 ,  18 . Due to this rotation, the light screening plates  14 ,  15 ,  16  move downward when the detachment knob  20  moves as far as the position shown in FIG. 6, and the aperture  1   a  opens. 
     The motion of this follower pin  17   b  on the inclined cam surface  21   a  is shown in FIG. 7 b . The light screening device  13  is in the closed state at the positions denoted by the symbols A, B, while the light screening device  13  is in the open state at the positions denoted by the symbols C, D. Namely, when mounting the lens barrel  30  in the camera body  1  at the position shown by the symbol A in FIG. 7 b , the detachment knob  20  slides to the position D via the position C from the position B, the follower pin  17   b  engages the inclined cam surface  21   a , and the light screening device  13  moves from the closed state to the open state. 
     At one side of the upper surface of the detachment knob  20 , a rack  20   a  is formed along the left and right direction of the camera. Rack  20   a  is in toothed engagement with a gear  4   b  formed in a portion of the outer circumference of the set tube  4 . Accordingly, if the set tube  4  is rotated, the rotation of the body side mount  3  around the optical axis is prevented. Movement in the optical axis direction can be actuated, and retraction of the lens barrel  30 , as mentioned below, is possible along the optical axis direction into the body. 
     interchangeable lens barrel  30  is disposed retractably from an open aperture  19   a  of the front surface, center of the camera body cover  19  in the guide tube  2  of the camera body  1 . The lens barrel  30  is disposed to be freely detachable with respect to the body side mount  3  which constitutes the mounting device movable in the optical axis direction within the guide tube  2 . 
     Namely, lens barrel  30  is freely detachable with respect to the camera body  1 , and also is constructed such that it can collapse and be received in the camera body  1 , a so-called interchangeable lens type camera is used. 
     In lens barrel  30 , first and second lens groups  31 ,  32 , which form a zoom lens, are respectively disposed in a state supported by first and second group lens frames  33 ,  34 , respectively. In the first lens group support frame  33 , an actuator (not shown in the drawings) is built in. The actuator performs opening and closing of the back surface side shutter  35 . In addition, a lens compartment member  36 , which is assembled with the first lens group  31 , causes rotation via a leg member  37 , which has been disposed to protrude from a drive ring disposed in the interior of compartment member  36 . Compartment member  36  is constructed by the threaded engagement of a male screw  36   a , which was formed on the outer circumference of the compartment member  36 , and a female screw  33   b , which was formed in the first lens group frame  33 . Focusing is performed by the extension and retraction of the first lens group  31 . 
     Moreover, compression spring  38  prevents backlash between the male screw  36   a  and the female screw  33   b  by urging the lens compartment member  36  in one direction. 
     Lens barrel  30  has a cam tube  40  with cam grooves  40   a ,  40   b , which engage a cam follower  33   a  of the first lens group support frame  33  and a cam follower  34   a  of the second lens group support frame  34 . 
     Lens barrel  30  also includes fixed tube  41  located on the outer circumference of the cam tube  40 . A guide groove  41   a  of the cam followers  33   a ,  34   a  is formed in cam tube  40 , in the optical axis direction. 
     In the rear end of the fixed tube  41 , a lens barrel side coupling gear  42  is shaft supported to rotate freely in engagement with a gear portion  40   c  which was formed in the rear end of the cam tube  40 . In addition, a lens side mount  43  is disposed at the rear end of fixed tube  41 . 
     In the lens side mount  43 , corresponding to the body side mount  3 , a connecting member is disposed which connects both lens side mount  43  and body side mount  3  when the lens barrel  30  has been mounted in the camera body  1 . Namely, in the body side mount  3  and the lens side mount  43 , there is a disengaged state in the assembly position at the time of assembly of the lens barrel  30 , from which lens barrel  30  is assembled to contact and engage by making a predetermined angular rotation. Lens barrel  30  is equipped with a rotation restriction device (not shown in the drawing) which prevents pulling out of the lens barrel  30 , and engagement claws  43   d ,  43   d.    
     In the lens side mount  43 , the shaft end portion  42   a  of the coupling gear  42  is disposed penetrating in a position opposite the hole portion  3   b  perforated in the body side mount  3 . Then, as shown in FIG. 1, the shaft end portion  42   a , at the time when the lens barrel  30  is mounted, engages the coupling side front end  8   a  of the body side coupling gear  8  so as to transmit rotation. 
     In the lens side mount  43 , the hole portion  43   a  is formed in the portion corresponding to the hole portion  3   c  for use with the connecting pin  9  of the body side mount  3 . A printed board  44  is interposed between this lens side mount  43  and the end of fixed tube  41  at the interior side of hole  43   a , with a relay flexible printed board  45  being connected to the printed board  44  in order to perform electrical connection of the shutter  35 . The drive member is also electrically connected via the printed boards  44  and  45 , with the drive member performing focusing drive and being disposed within the lens barrel  30  with a body side control device. The relay flexible printed board  45  has a folded up portion such that lens groups  31 ,  32  may move for zooming action. 
     A conductive layer is formed on the surface which fronts on the lens side mount  43  of the printed board  45 , and is exposed within the hole portion  43   a . Then, at the time when the lens barrel  30  is mounted, the connecting pin  9  is inserted in this hole  43   a . Via this connecting pin  9 , by one end thereof coming into contact with the conductive layer, the lens barrel side  30  is connected via the flexible wiring board  12  to the control circuit  11 . 
     As shown, for example, in FIG. 1, spring  46  prevents backlash of the cam followers  33   a ,  34   a  with respect to the cam grooves  40   a ,  40   b  by urging the second lens group support frame  34  in one direction. 
     Lens barrel outside cover  47  forms the outer shell of the lens barrel  30  and supports the cam tube  40  for free rotation in the fixed tube  41 . 
     Barrier opening and closing mechanism  50  is a lens protection member disposed so as to open and close the photographic light path at the front end of photographic lenses  31 ,  32  within the lens barrel  30 . The barrier opening and closing mechanism  50  includes a pair of barrier vanes  51 ,  52  which shield the front surface portion of the first lens group  31  at the front surface portion of the lens barrel  30 . As shown in FIGS. 8 and 10, the barrier vanes  51 ,  52  are closed when the lens barrel  30  is detached from the camera, and, as shown in FIGS. 9 and 11, the vanes  51 ,  52  are open when the lens barrel  30  is mounted in the camera. 
     As shown in FIGS. 8-11, this kind of barrier mechanism  50  is equipped with a barrier opening and closing drive ring  53 . A leg  53   a  extends from a portion of barrier opening and closing ring  53  in a direction along the outer circumferential portion of the lens barrel  30  towards the rear end side. The leg  53   a  engages in the engagement portion  43   e  of the lens side mount  43  when the whole length of the lens barrel  30  is shortest, opposes the urging force of a tension spring  54 , and, as shown in FIG. 12, moves upwards in this Figure. In this manner, this barrier opening and closing drive ring  53  rotates the forward portion of the lens barrel  30  to arrive at the state shown in FIGS. 8 and 10, and the barrier vanes  51 ,  52  close by the action of tension springs  55 ,  56 . 
     Namely, in a case in which the lens barrel  30  is detached from the camera body  1 , the detaching action having been performed after causing the lens to collapse, the whole length of the lens barrel  30  becomes shortest, and due to this the barrier vanes  51 ,  52  close. 
     Mounting the lens barrel  30  on the camera body  1  extends the lens barrel  30  to a state in which photography is possible. The engagement of the leg  53   a  with the lens side mount  4  is removed, and the barrier opening and closing drive ring  53  rotates in a clockwise direction in the Figure due to the tension force of the tension spring  54 . Thus, each barrier vane  51 ,  52  is also extended outside from support shafts  51   a ,  52   a  to the fixed portion of the lens barrel  30  located at the action end by engagement pins  51   b ,  52   b . Barrier vanes  51 ,  52  engage the engagement portions  53   b ,  53   c  by the notch of the barrier opening and closing ring  53 , and rotate in the opening direction opposing the tension force of the respective tension springs  55 ,  56  and are thus in the open state as shown in FIGS. 9 and 11. 
     As shown in FIGS. 1,  8 , and  9 , lens barrel inside cover  58  is disposed so as to protect the outside of first lens group support frame  33  at the time that the lens barrel  30  is mounted when the lens groups  31 ,  32  and the like are in the photographic standard stall shown in FIG.  9 . Lens barrel inside cover  58  extends from the front end portion of the barrel. At this time, the barrier vanes  51 ,  52  open. 
     As shown in FIGS. 8 and 9, in a camera with an interchangeable lens barrel mounted therein, a release button  61  is disposed at the upper end surface in a portion approaching one side in the camera body case  19  which covers the outer surface. Furthermore, a window  62  and a strobe light generation window  63  are disposed side by side at the upper side of an open aperture  19   a , at which the lens barrel  30  is mounted. Moreover, a generally known photometric device, rangefinding device, and viewfinder are arranged inside the window  62 . Moreover, zoom switches, comprising a zoom up switch ZUS and a zoom down switch ZDS, are disposed in the upper portion of the back surface side of the camera, in order to provide drive control of the zoom lens (by lens groups  31 ,  32 ). 
     In the above construction, as shown in FIGS. 5 and 6, a detection switch  25  is mounted in the detachment knob  20  in order to detect the operating position of the detachment knob  20 . Sliding member  26  is disposed on a portion of the detachment knob  20  by brushes. Each brush of the sliding member  26  slides on printed board  27 . The operating position of the detachment knob  20  can be detected by the slide contact position of conductive patterns  27   a ,  27   b ,  27   c  formed on the board  27 . 
     Namely, a first position detection switch SW 1  is formed by the conductive pattern  27   a  of the GND side and the conductive pattern  27   b , and a second position detection switch SW 2  is formed by the conductive pattern  27   a  of the GND side and the conductive pattern  27   c.    
     For example the lens barrel  30 , from the state shown in FIG. 2 to that shown in FIG. 3, mounting causes a predetermined angular rotation in the body side mount  3  on the camera body  1  side. In this state, the detachment knob  20  operates and moves to position “B” of FIG. 14 a  as a set state. Thereupon, the light screening plates  14 ,  15 ,  16 , as described previously, are moved away and open the aperture portion  1   a . Further, the body side mount  3  with rotation around the optical axis in the stopped state, moves back and forth along the optical axis. By moving as far as the collapsed position, as shown in FIGS. 1 and 13 a , the lens barrel  30  side and camera body  1  side coupling gears  42 ,  8  are coupled. Moreover, the shutter  35  and electrical signal relay board  44 , for focusing drive use, and the connecting pin  9  come into contact when the lens barrel is mounted to the camera body. The state of the camera becomes one where the camera parts can be moved in preparation for photography. 
     After this, when the detachment knob  20  is operated to the “C” position in FIG. 14 a , a zoom drive motor (not shown in the drawing) drives, via the coupling gears  8 ,  42 , the cam tube  40 . The cam tube  40  rotates the lens group support frames  32 ,  33  to extend the lens barrel  30  in the optical axis direction and stops at the Wide end (W end) position. This state is shown in FIG.  4  and FIG. 13 b.    
     At this time, as shown by the double dot chain lines of FIG. 12, the leg  53   a  of the drive ring  53  undergoes a tension force downwards by spring  54 . In this manner, as shown in FIG. 11, the drive ring  53  rotates in a clockwise direction in the Figure. Via engagement pins  51   b ,  52   b  of the action end of the barrier vanes  51 ,  52 , the barrier vanes  51 ,  52  rotate, opposing the tension force of the tension springs  55 ,  56 , around the support shafts  51   a ,  52   a , and open. 
     As shown in FIG. 14 b , by the operation of the detachment knob  20 , which also acts as a battery switch and is arranged in the bottom surface portion of the camera, the state becomes as follows. Namely, in the case of position “A”, the body side mount  3  is in an extension position in order to detach the lens barrel  30 . In the case of position “B”, the body side mount  3  retracts within the guide tube  2  of the camera body  1 , and the electrical and mechanical coupling with the lens barrel  30  has been completed. In the case of position “C”, the power supply switch is ON, and the camera has reached a state in which photography is possible. 
     Then, the possible positions of the switches  51  and  52  at positions A, B, and C are either ON or OFF. Accordingly, the signal levels from the switches are “H” or “L”, as can be confirmed from FIG. 14 b . In this manner, by use of the control circuit as shown in FIG. 15, control is performed of the operation of the camera. 
     FIGS. 7 a  and  7   b  show the relationship of the phases of the inclined cam surface  21   a  in the detachment knob  20  with respect to the cam groove  4   a  or the set tube  4 . When detaching the lens barrel  30 , the body side mount  3  moves as far as the guide tube  2  front end portion of the camera body  1  (position shown by A in FIGS. 7 a  and  7   b ). At this time, the lens barrel is detached. At this time, the screening device  13  is in a closed state. 
     By inserting the lens barrel  30  in the optical axis direction into the camera body  1  from the state shown in FIG. 2, and also causing a predetermined angular rotation, as shown in FIG. 3, both mounts  43 ,  3  are caused to engage. When the detachment knot)  20  is operated in this state, as shown in FIGS. 7 a  and  7   b , the detachment knob  20  may be caused to move to the B position, the C position, and the D position. Thus, the lens barrel  30 , because this lens side mount  43  is coupled to the body side mount  3 , is retracted into the camera body  1 , and the state of the camera becomes the collapsed state shown in FIG.  1 . 
     In the state shown in FIG. 1, by using the zooming motor (shown by symbol  72  in FIG.  15 ), via the coupling gears  8 ,  42 , the cam tube  40  is rotated, and as shown in FIG. 4, each lens group  31 ,  32  is driven in the optical axis direction, and photography becomes possible at the required zoom magnification. 
     FIGS. 13 a ,  13   b , and  13   c  show the zoom drive state of the lens barrel  30 . FIG. 13 a  shows the collapsed state, FIG. 13 b  shows the Wide end state, and FIG. 13 c  shows the Tele end state. Moreover, the construction is such that movement of the lens barrel  30  in this manner, i.e. zooming, is detected by the zoom position detection switch SW 3 , which comprises brushes and a conductive pattern. Switch SW 3  is interposed between the cam tube  40  and fixed tube  41 . 
     FIG. 15 is a block diagram showing the control circuit in a camera according to a preferred embodiment of the present invention. In FIG. 15, the same or equivalent portions as shown in FIGS. 1-14 are given the same reference symbols, and therefore a further description is omitted. 
     As shown in FIG. 15, a CPU  70  is disposed in the camera. The shutter  35 , focusing drive motor  71 , and zooming motor  72  are connected to the control circuit  11 . Control circuit  11  in turn is operatively connected to CPU  70 . The photometer device  73 , rangefinding device  74 , and strobe circuit  75  are connected directly to the CPU  70 . Moreover, a switch formed by the release button  61 , the operating position detection switches SW 1 , SW 2  of the detachment knob  20 , the zoom up switch ZUS, and the zoom down switch ZDS are connected to CPU  70 . Furthermore, the zoom position detection switch SW 3  in the lens barrel  30  as shown in FIG. 13 is connected to CPU  70 . The required photographic operation is performed according to the position of each switch. 
     By an interchangeable lens camera according to the above-described embodiment, the body side mount  3 , as the mounting device for detachably mounting the lens barrel  30  in the camera body  1 , constitutes a movement device which causes the lens barrel  30  to move back and forth in the optical axis direction. A set tube  4 , a coupling gear  8  or connection pin  9  and the like are provided to perform electrical and mechanical transmission at the time when a body side mount  3  has reached a collapsed position of the film surface side. Then, a set tube  4  moves back and forth in the optical axis direction by rotation caused by movement of detachment knob  20  via the engagement of a follower pin  3   a  and guide groove  2   a  and cam groove  4   a . The lens barrel  30  is received in the camera body  1   a  body side mount  3  which constitutes a mounting device disposed so as to prevent rotation around the optical axis and also to move back and forth in the optical axis direction. 
     For example, in the assembled state of the lens barrel with respect to the camera body  1  via the body side mount  3 , when the body side mount  3  has retracked to the collapsed position within the camera body  1 , the electrical drive members (shutter, focusing drive motor, zooming motor) of the lens barrel  30  side are capable of electrical connection to the control circuit  11  of the camera body side. 
     According to the above preferred embodiments of the present invention, the camera includes the body side mount  3 , which is a mounting device, and which moves linearly along the optical axis direction as far as an operating position (see FIG.  3 ). Also the shortest length of the interchangeable lens camera is when the lens barrel is detached from the mount  3 . At this time, the vanes  51 ,  52  of barrier opening and closing device  50 , which is a lens protection member that opens and closes the photographic optical path at the front surface side of the lens barrel  30 , become closed by the engagement of the leg  53   a  of the barrier opening and closing drive ring  53  and the lens side mount  4 . 
     Moreover, the present invention is not limited to the structure of the above-described embodiments. Suitable changes or modifications can be carried out on the configuration, structure and the like of each part of an interchangeable lens camera, and it goes without saying that various further alternative examples are possible. Essentially, the mounting device constituted with a freely detachable lens barrel  30 , prevents rotation about the optical axis within the camera body  1 , and also moves back and forth in the optical axis direction. 
     The interchangeable lens camera, according to the above preferred embodiments of the present invention as described hereinabove, is equipped with a mounting device in order to interchangeably mount a lens barrel in a camera body. This mounting device prevents rotation about the optical axis within the camera body and also moves back and forth in the optical axis direction. Moving this mounting device in the optical axis direction allows for the camera body to receive the lens barrel in the camera body. Moreover, the mounting device, in order to collapse in the camera body, does not come out in the outer part of the camera body. Accordingly, the outer side of the lens barrel can easily be used as a cover, without any restrictions on the design. 
     Moreover, in accordance with the above preferred embodiments of the present invention, because the mounting device of a lens barrel can be made equal in diameter to that of the lens barrel or smaller, a larger region than that of the diameter of the lens barrel is not required and it is possible to avoid increases in size of the camera. Furthermore, it is possible to completely collapse the lens barrel within the camera body, and because the lens barrel does not project it is more convenient to transport. 
     Moreover, in the interchangeable lens camera according to the above preferred embodiments of the present invention, the lens barrel, when in a state where the lens barrel has been mounted relative to the camera body via a mounting device, the electrical mechanisms of the lens barrel and the camera body can be reliably connected when the lens barrel reaches the completely collapsed state because the electrical drive member of the lens barrel side can be electrically connected to the control circuit of the camera body side. Likewise, reliable connections can be achieved between the mechanical mechanism units of the lens barrel and camera body. 
     Moreover, in an interchangeable lens camera according to the above preferred embodiments of the present invention, when the lens barrel is detached from the mounting device, if the camera is operating in a state in which the mounting device is moved in the camera body as far as the extension position along the optical axis, the lens barrel itself is able to freely expand and contract in the optical axis direction. Further, when the lens barrel is detached from the mounting device, thus having the shortest length possible, a lens protection member disposed in the photographic light path closes the photographic light path of the photographic lens front surface side in the lens barrel. As mentioned above, the mounting of the lens barrel to the camera body can be accomplished both simply and accurately, and the lens barrel can be caused to collapse within the camera body by a backward and forward motion in the optical axis direction. 
     Although a few preferred embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.