Abstract:
A camera arranged to automatically open and close the cover of a film cartridge chamber includes a gear member having a gear part arranged to rotate for feeding and rewinding a film by engaging a supply spool of a film cartridge, a revolving member arranged to engage the gear part and to be caused to revolve by the rotation of the gear member, an opening operation member provided for opening the cover of the film cartridge chamber, and a lock member arranged to lock the cover in a closed state or to unlock the cover. In the camera, the lock member moves from outside of a revolving travel locus of the revolving member to inside of the revolving travel locus of the revolving member in association with an operation of the opening operation member, and the lock member is driven by a revolving motion of the revolving member to unlock the cover.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an improvement on a camera or a like apparatus having a device for opening and closing the cover of a film cartridge chamber provided in the camera or the like. 
     2. Description of Related Art 
     Some of cameras commercialized during recently years are arranged such that, when a film cartridge in which a whole film including its fore end part, i.e., a leader part, is completely wound within there is loaded in a film cartridge chamber, a fork is driven to cause the film to be pulled out from the film cartridge and taken up and wound around on a spool shaft of the camera. 
     A problem with the camera of this kind lies in that, if the cover of the cartridge chamber is inadvertently opened by the user while the film is in process of being pulled out from the film cartridge within the cartridge chamber, the film would be exposed to light. To solve this problem, various devices has been developed. For example, In a camera disclosed in Japanese Laid-Open Patent Application No. HEI 8-286245, a lock member is provided in a part of a film transport gear train for locking the cover of the cartridge chamber. The lock member is arranged to be kept in a lock position to make the cover of the cartridge chamber unopenable by preventing an opening operation on a knob provided for opening and closing the cartridge chamber, when the film is in process of being wound and rewound. 
     In the case of this camera, however, the lock member is in an unlocking position for the opening-and-closing knob while the rotating direction of a film transport motor is in process of being changed from a film winding direction over to a film rewinding direction. Therefore, at the time of this change-over, the opening-and-closing knob might happen to be inadvertently operated to open the cover of the cartridge chamber. In view of this shortcoming, in U.S. patent application No. 09/105,755 (Japanese patent application No. HEI 9-/190789), there is disclosed a device as an improvement on the camera of this kind, in which the cover of the cartridge chamber is arranged to be not openable without performing a film winding action and a film rewinding action respectively once and, after that, to become openable by rotation in the film feeding or winding direction (hereinafter sometimes referred to as the thrust direction). 
     Meanwhile, with a camera arranged to use a film cartridge of the kind having a data disk, when the camera is loaded with the film cartridge, the camera performs a reading action to read data provided on the data disk by rotating a film winding spool of the film cartridge in the film rewinding direction before the above-stated driving in the thrust direction (thrust driving). 
     Therefore, in a case where a film cartridge of this kind is to be used for the camera which is provided with the above-stated improvement disclosed in U.S. patent application No. 09/105,744, it has been impossible to read data from the data disk, because the film winding action and the film rewinding action are arranged to be performed respectively once before opening the cartridge chamber cover by the thrust driving. More specifically, it has been impossible to read the data because the cartridge chamber cover would be opened if the thrust driving is performed after data reading from the data disk. 
     BRIEF SUMMARY OF THE INVENTION 
     It is a first object of the invention to provide an apparatus having a device for opening and closing a film cartridge chamber cover arranged such that, as long as an opening operation member for the cartridge chamber cover is not operated, the cartridge chamber cover can not be opened even if a film winding spool of the film cartridge or a fork gear is caused to rotated forward or backward. In other words, the cartridge chamber cover is arranged to be openable only by operating the opening operation member. 
     Therefore, data can be read from the data disk by rotating the film winding spool in the direction of film rewinding before the thrust driving. Besides, in a case where the camera is loaded with a film cartridge which is used halfway, an unexposed frame can be searched out and then the film can be temporarily rewound to set the unexposed frame again at an exposure (aperture) position. 
     It is a second object of the invention to provide an apparatus having a cartridge chamber cover opening-and-closing device which is capable of preventing the setting of the film using state obtained at the end of rewinding from being varied by an unlocking action on the cartridge chamber cover. 
     It is a third object of the invention to provide an apparatus having a cartridge chamber cover opening-and-closing device which is capable of bringing a revolving member back to its standby position even under an irrational condition such as having an opening operation member for the cartridge chamber cover left inadvertently in an operated state, so that a film rewinding action can be carried out even under such an irrational condition. 
     To attain the above objects, in accordance with an aspect of the invention, there is provided a device for opening and closing a cover of a film cartridge chamber, comprising a gear member ( 11 ) having a gear part arranged to rotate for feeding and rewinding a film by engaging a supply spool of a film cartridge, a revolving member ( 12 ) arranged to engage the gear part and to be caused to revolve by rotation of the gear member, an opening operation member ( 7 ) provided for opening the cover, and a lock member ( 2 ,  3  and  5 ) arranged to lock the cover in a closed state or to unlock the cover, wherein the lock member moves from outside of a revolving travel locus of the revolving member to inside of the revolving travel locus of the revolving member in association with an operation of the opening operation member, and the lock member is driven by a revolving motion of the revolving member to unlock the cover. When the opening operation member is not operated, the lock member is located outside of the revolving travel locus. With the lock member at this position, therefore, the cover of the film cartridge chamber is never caused to open by film feeding (transport) and rewinding actions. 
     The device according to the invention further comprises a detection switch for detecting an operation position, for opening the cover, of the opening operation member, and a motor for driving and causing the gear part to rotate, wherein the motor causes the gear part to rotate when the opening operation member has been detected by the detection switch to be at the operation position. 
     In the device, the motor is arranged to rotate the gear part in the direction of feeding the film. 
     The device according to the invention further comprises a first detection switch arranged to detect whether or not the lock member is at an unlocking position, a second detection switch arranged to detect presence or absence of the film, and a motor provided for driving the gear part to rotate, wherein the motor drives the gear part to rotate in the direction of rewinding the film when the lock member has been detected by the first detection switch to be at a locking position and the film has been detected by the second detection switch to be absent. 
     The device further comprises an urging member arranged to urge the lock member to move toward a locking position thereof. 
     The device further comprises first and second restricting members arranged to define a movable range of the revolving member, and the revolving member is allowed to move within the movable range. 
     These and further objects and features of the invention will become apparent from the following detailed description of a preferred embodiment thereof taken in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     FIG. 1 is a perspective view showing a camera according to an embodiment of the invention. 
     FIG. 2 is a perspective view showing the camera according to the embodiment of the invention. 
     FIG. 3 is a simplified view of essential parts of the camera according to the embodiment of the invention. 
     FIG. 4 is a simplified view of essential parts of the camera according to the invention. 
     FIG. 5 is a simplified view of essential parts of the camera according to the embodiment of the invention. 
     FIG. 6 shows the arrangement of parts of the camera as viewed from the right side of FIG.  3 . 
     FIG. 7 shows the arrangement of parts of the camera as viewed from the right side of FIG.  4 . 
     FIGS.  8 ( a ) and  8 ( b ) show one state of each part of the camera obtained after the commencement of unlocking the cover of the cartridge chamber of the camera before completion of the process of unlocking. 
     FIGS.  9 ( a ) and  9 ( b ) show another state of each part of the camera obtained after the commencement of unlocking the cover of the cartridge chamber of the camera before completion of the process of unlocking. 
     FIGS.  10 ( a ) and  10 ( b ) show a further state of each part of the camera obtained after the commencement of unlocking the cover of the cartridge chamber of the camera before completion of the process of unlocking. 
     FIGS.  11 ( a ) and  11 ( b ) show a further state of each part of the camera obtained after the commencement of unlocking the cover of the cartridge chamber of the camera before completion of the process of unlocking. 
     FIGS.  12 ( a ) and  12 ( b ) show a further state of each part of the camera obtained after the commencement of unlocking the cover of the cartridge chamber of the camera before completion of the process of unlocking. 
     FIGS.  13 ( a ) and  13 ( b ) show a further state of each part of the camera obtained after the commencement of unlocking the cover of the cartridge chamber of the camera before completion of the process of unlocking. 
     FIGS.  14 ( a ) and  14 ( b ) show a still further state of each part of the camera obtained after the commencement of unlocking the cover of the cartridge chamber of the camera before completion of the process of unlocking. 
     FIGS.  15 ( a ) and  15 ( b ) show one state of the camera obtained during a period between loading the camera with the film cartridge and the commencement of film rewinding after completion of photo-taking. 
     FIGS.  16 ( a ) and  16 ( b ) show another state of the camera obtained during a period between loading the camera with the film cartridge and the commencement of film rewinding after completion of photo-taking. 
     FIGS.  17 ( a ) and  17 ( b ) show a further state of the camera obtained during a period between loading the camera with the film cartridge and the commencement of film rewinding after completion of photo-taking. 
     FIGS.  18 ( a ) and  18 ( b ) show a still further state of the camera obtained during a period between loading the camera with the film cartridge and the commencement of film rewinding after completion of photo-taking. 
     FIGS.  19 ( a ) and  19 ( b ) show a state of the camera obtained when an irrational operation is performed at the commencement of film rewinding. 
     FIGS.  20 ( a ) and  20 ( b ) show another state of the camera obtained when an irrational operation is performed at the commencement of film rewinding. 
     FIG. 21 is a block diagram showing the electrical arrangement of essential parts of the camera according to the embodiment of the invention. 
     FIG. 22 is a flow chart showing in part a flow of processes to be executed by the camera including processes of unlocking the cover of the cartridge chamber. 
     FIG. 23 is a flow chart showing another part of the flow of processes executed by the camera continuing from processes shown in FIG.  22 . 
     FIG. 24 is a flow chart showing a further part of the same flow of processes continuing also from the processes shown in FIG.  22 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, a preferred embodiment of the invention will be described in detail with reference to the drawings. 
     FIGS. 1 and 2 are skeleton perspective views showing a camera according to the embodiment of the invention. FIGS. 3 to  7  schematically show the arrangement of essential component parts of the camera. FIGS.  8 ( a ) and  8 ( b ) to FIGS.  20 ( a ) and  20 ( b ) show the actions of the essential component parts by further simplifying FIGS. 3 to  7 . Of these figures, FIG. 6 shows the parts shown in FIG. 3 as viewed from on the right side of FIG.  3 . FIG. 7 shows the parts shown in FIG. 4 as viewed from on the right side of FIG.  4 . FIG. 5 shows the parts shown in FIGS. 3 and 4 by omitting in part a camera body  1  and an operation knob. 
     In FIGS. 1 to  7 , reference numeral  1  denotes the body of the camera. A hook lever  2  is carried by a shaft  1   a  of the camera body  1  to be swingable thereon. A hook  2   a  provided on the hook lever  2  is arranged to be hooked on a claw part  6   a  of a cartridge chamber cover  6  to keep the cartridge chamber cover  6  in a locked state. A driving lever  3  is carried by the shaft  1   a  of the camera body  1  also to be swingable thereon, as in the hook lever  2 . A torsion spring  5  which is carried by the shaft  1   a  of the camera body  1  is disposed between a shaft  3   a  secured to the driving lever  3  and a shaft  2   a  secured to the hook lever  2 . The torsion spring  5  is thus arranged to urge the hook lever  2  to swing clockwise. Therefore, if no other force is acting on the driving lever  3 , the driving lever  3  is caused by the urging force of the torsion spring  5  to be abutting on a bent-up part  2   c  of the hook lever  2 . 
     As shown in FIG. 6, a sector lever  19  is carried by a shaft  1   g  of the camera body  1  to be swingable on the shaft  1   g.  A torsion spring  20  is arranged between a shaft  19   b  on the sector lever  19  and a shaft  1   h  on the camera body  1  to constantly urge the sector lever  19  to swing counterclockwise. Therefore, an abutting part  19   a  of the sector lever  19  abutting on the hook lever  2  is constantly urging the hook lever  2  to swing clockwise as viewed in FIG.  5 . The hook lever  2  is thus abutting on a stopper shaft if of the camera body  1 . Under this condition, completion of locking the cartridge chamber cover  6  can be detected, when the hook lever  2  comes to push a contact piece  17   a  of a lock completion switch  17  into contact with another contact piece  17   b  of the switch  17  to bring about a conductive state. This clockwise urging force is arranged to be stronger than the urging force of the torsion spring  5 . Therefore, as will be described in detail later, when an operation knob  7  is operated, the driving lever  3  is alone allowed to swing counterclockwise on the shaft  1   a  to be set into a set position. A hook claw  4  is made of plastic having elasticity and is secured to the hook lever  2  by thermal fusion with positioning shafts  4   a  and  4   b.  Therefore, the hook claw  4  works together with the hook lever  2 . The hook claw  4  is arranged to be in a free state while the cartridge chamber cover  6  is locked but to have its claw part  4   c  hooked on a lock  1   e  of the camera body  1  to maintain an unlocked state when the cartridge chamber cover  6  is unlocked. 
     The operation knob  7  which is provided for opening the cartridge camber cover  6  is arranged to be slidable to the right and left along a guide (not shown) with respect to the camera body  1 . The operation knob  7  has an operation part  7   a  and shafts  7   b,    7   c  and  7   d.  A tension spring  10  is arranged between the shaft  7   b  of the operation knob  7  and a shaft  1 b of the camera body  1  to constantly exert an urging force leftward as viewed in FIG.  3 . Under this urging force, the operation knob  7  is abutting on a stopper of a guide part (not shown) which is provided on the camera body  1 . The shafts  7   c  and  7   d  have a switch contact piece  8  mounted thereon. The fore end part of the switch contact piece  8  is arranged to come into contact with a printed circuit board  9 . When the operation knob  7  is abutting on the stopper of the leftward guide of the camera body  1  under the urging force of the tension spring  10 , patterns  9   a  and  9   b  of the printed circuit board  9  are set in a conductive state by the switch contact piece  8  in such a way as to indicate that the operation knob  7  is not operated. 
     When the operation knob  7  is operated rightward against the urging force of the tension spring  10 , the switch contact piece  8  renders patterns  9   a  and  9   c  of the printed circuit board  9  conductive to permit detection of that the operation knob  7  is in an operation completed state. A leaf spring  15  is secured to the operation knob  7 . When the operation knob  7  is operated to the right from its position of FIG. 3 to a position as shown in FIG. 4, an elastic part  15   a  of the leaf spring  15  pushes a shaft  3   b  secured to the driving lever  3  to cause the driving lever  3  to abut on a stopper part  2   d  of the hook lever  2  by swinging counterclockwise against the urging force of the torsion spring  5 . The hook lever  2  is thus set into a setting position where the cartridge chamber cover  6  can be unlocked by the rotation of a fork gear  11  as will be described later. To ensure setting into this setting position, the urging force of the leaf spring  15  is arranged to be stronger than the force of the torsion spring  5  and weaker than the rotative urging force of the torsion spring  20  of the sector lever  19 . Therefore, the leaf spring  15  is thus arranged to warp, as shown in FIG. 4, after the driving lever  3  abuts on the stopper part  2   d  of the hook lever  2 . 
     The fork gear  11  is arranged to rotate on a fork  22 . In transmitting rotation to the fork  22 , an abutting part  11   a  of the fork gear  11  abuts on an abutting part  22   a  of the fork  22  to enable the fork  22  to rotate along with the fork gear  11 . FIG. 6 shows the fork gear  11  in a state of rotating counterclockwise to enable the fork  22  to rotate together therewith. When the fork gear  11  rotates clockwise from the state of FIG. 6, the abutting parts  11   a  and  22   b  do not abut on each other again until the fork gear  11  rotates clockwise at least 180 degrees, which is arranged as an idle rotation angle range. This idle rotation angle range of 180 degrees is provided for carrying out an unlocking action on the cartridge chamber cover  6 . 
     A planet gear  12  is carried by a planetary lever  14  on its shaft  13  to be revolvable with rolling friction in mesh with the fork gear  11 . Therefore, when a rotation torque of a film transport motor  28  (see FIG. 2) is transmitted to the fork gear  11  through a gear train (gears  23  to  27 ), the planet gear  12  is caused to revolve by the rolling friction. With the camera in the state of FIG. 6, when the fork gear  11  rotates counterclockwise, the planet gear  12  revolves also counterclockwise. Then the shaft  13  comes to abut on a stopper  1   d  of the camera body  1  which corresponds to an abutting position on one side. The stopper  1   d  thus brings the revolution of the planet gear  12  to a stop. Further, when the fork gear  11  rotates clockwise from the state of FIG. 6, the planet gear  12  revolves also clockwise to intermesh with an inner gear  18 , so that the planet gear  12  comes to rotate while continuing to revolve. This increases the revolving torque of the shaft  13  to make it possible to unlock the cartridge chamber cover  6 . When the planet gear  12  further continues its revolution, the planet gear  12  ceases to be in mesh with the inner gear  18  after completion of the process of unlocking the cartridge chamber cover  6 . Then, the planet gear  12  comes to make only its revolution until the shaft  13  comes to abut on another stopper  1   c  of the camera body  1  which is located on the opposite side of the stopper  1   d.  The revolution of the planet gear  12  thus comes to a stop at the other abutting position. 
     A cartridge presence/absence detecting switch  16  is arranged to detect that the camera is loaded with a film cartridge when a projection of one contact piece  16   b  is pushed upward by the film cartridge into contact with the other contact piece  16   a.    
     A gear  21  is arranged to open and close a light-lock door  21  set at the film cartridge and is arranged to be driven by the rotation of the sector lever  19 . The details of this gear  21  are the same as those disclosed in U.S. patent application No. 09/105755 and are, therefore, omitted from the description given here. 
     FIGS.  8 ( a ) and  8 ( b ) to FIGS.  14 ( a ) and  14 ( b ) show the states of various parts obtained during a period between the commencement and completion of unlocking the cartridge chamber cover  6 . 
     In the state shown in FIGS.  8 ( a ) and  8 ( b ), the cartridge presence/absence detecting switch  16  in an off-state. Therefore, the camera is loaded with no film cartridge. In this state, the shaft  13  of the planet gear  12  is abutting on the stopper  1   d  of the camera body  1  and the fork gear  11  is in a standby position which is equivalent to a film rewinding completing position. 
     The shaft  13  of the planet gear  12  does not abut on the driving part  3   c  of the driving lever  3  even if the fork gear  11  is rotated in the direction of thrust, i.e., in the clockwise direction, under the condition shown in FIGS.  8 ( a ) and  8 ( b ). Therefore, the unlocking action on the cartridge chamber cover  6  is not performed. Further, since the lock completion switch  17  is in its on-state, a control IC of the camera detects that the cartridge chamber cover  6  is locked. 
     When the operation knob  7  is moved to the right from its position shown in FIG.  8 ( a ) and  8 ( b ) to change a condition of having the patterns  9   a  and  9   b  in their on-states to a condition of having the patterns  9   a  and  9   c  in their on-states, preparation for unlocking the cartridge chamber cover  6  is completed as shown in FIGS.  9 ( a ) and  9 ( b ). When the state of the switch  9  of the operation knob  7  thus changes, the elastic part of the leaf spring  15  secured to the operation knob  7  pushes the shaft  3   b  of the driving lever  3  to cause the driving lever  3  to swing alone counterclockwise against the force of the torsion spring  5 . The driving lever  3  thus comes to abut on the stopper part  2   d  of the hook lever  2 . The elastic part of the leaf spring  15  then deforms as shown in FIG.  9 ( a ). 
     In this instance, with the condition of having the patterns  9   a  and  9   b  in their on-states having changed to the condition of having the pattern  9   a  and  9   c  in their on-states, the control IC of the camera causes the motor  28  to be driven to rotate the fork gear  11  in the thrust direction, i.e., in the clockwise direction. 
     In the state of FIG.  9 ( b ), the driving part  3   c  of the driving lever  3  is located in the revolving locus of the shaft  13  of the planet gear  12 . Therefore, the fork gear  11  is rotated clockwise, i.e., in the direction of thrust, to cause the driving part  3   c  of the driving lever  3  to abut on the shaft  13  of the planet gear  12 , as shown in FIGS.  10 ( a ) and  10 ( b ). Then, the fork gear  11  is allowed to go on rotating clockwise to have the state of FIGS.  11 ( a ) and  11 ( b ) and further to have the state of FIGS.  12 ( a ) and  12 ( b ). The cartridge chamber cover  6  is thus unlocked as shown in FIG.  12 ( a ). 
     In the state of FIGS.  12 ( a ) and  12 ( b ), the cartridge chamber cover  6  is completely unlocked. The hook claw  4  then has its claw part  4   c  hooked on the lock part  1   e  of the camera body to keep the unlocked state. However, since the shaft  13  of the planet gear  12  is abutting on the driving part  3   c  of the driving lever  3  in this state, the clockwise rotation of the fork gear  11  continues still further to bring about the state of FIGS.  13 ( a ) and  13 ( b ) and to change it further into the state of FIGS.  14 ( a ) and  14 ( b ) until the shaft  13  of the planet gear  12  comes to abut on the stopper  1   c  of the camera body  1 . This control can be accomplished by causing an energizing timer to count the time of energizing of the film transport motor  28  from the time when the lock completion switch  17  turns off from its on-state. The control arrangement gives a sufficient allowance for the angle of idle rotation after the commencement of rotation of the fork gear  11  until the fork  22  comes to rotate. 
     In the state of FIGS.  14 ( a ) and  14 ( b ), the abutting parts  11   a  and  22   a  of the fork gear  11  and the fork  22  are away from each other as shown in FIG.  14 ( b ). Therefore, the cartridge chamber cover  6  can be unlocked and the shaft  13  of the planet gear  12  can be caused to about on the stopper  1   c  of the camera body  1  within the range of the idle rotation angle. Further, in this state, the claw part  4   c  of the hook claw  4  is hooked on the lock part  1   e  of the camera body  1  to keep the hook part  2   a  of the hook lever  2  and the hook part  6   a  of the cartridge chamber cover  6  in their unlocking positions. 
     This state of the camera enables its user to load it with a film cartridge by fully opening the cartridge chamber cover  6 . 
     FIGS.  15 ( a ) and  15 ( b ) to FIGS.  18 ( a ) and  18 ( b ) show the states of the camera obtained during a period from the end of photo-taking after the film cartridge is loaded until the commencement of film rewinding. 
     FIGS.  15 ( a ) and  15 ( b ) show the camera in a state obtained immediately after the cartridge chamber cover  6  is closed with the camera having been loaded with the film cartridge. Since the camera is loaded with the film cartridge, the cartridge presence/absence detecting switch  16  is in an on-state, in which the contact piece  16   a  is in contact with the contact piece  16   b.  With the cartridge chamber cover  6  closed, the claw part  4   c  of the hook claw  4  is pushed to elastically deform by the hook part  6   a  of the cartridge chamber cover  6 . In the deformed shape, the claw part  4   c  is detached from the lock part  1   e  of the camera body  1 . Since the hook lever  2  is urged by the torsion spring  20  of the sector lever  19  to swing clockwise as viewed in FIG.  15 ( a ), the instant the claw part  4   c  of the hook claw  4  detaches from the lock part  1   e,  the hook lever  2  swings clockwise to bring about a state shown in FIGS.  16 ( a ) and  16 ( b ). In this state, the hook part  2   a  of the hook lever  2  and the hook part  6   a  of the cartridge chamber cover  6  interlock. The hook lever  2  abuts on the stopper shaft if of the camera body  1  and pushes the contact piece  17   a  of the lock completion switch  17  to render the contact pieces  17   a  and  17   b  conductive to enable the control IC of the camera to detect that the cartridge chamber cover  6  is closed. Under this condition, since both the lock completion switch  17  and the cartridge presence/absence detecting switch  16  are in their on-states, the control IC of the camera detects that the camera is loaded with the film cartridge. The control IC then comes to make preparations for photo-taking. 
     For changing the state of FIG.  15 ( b ) to the state of FIG. 16 ( b ), the fork gear  11  is driven by the film transport motor  28  to rotate clockwise after the lock completion detecting switch  17  is turned on. The clockwise rotation of the fork gear  11  causes the abutting parts  11   a  and  22   a  of the fork gear  11  and the fork  22  to abut each other. The fork gear then drives the fork  22  to rotate clockwise to thrust the film forward and thus to complete the photo-taking preparations. 
     FIGS.  17 ( a ) and  17 ( b ) show a state obtained upon completion of photo-taking on all the frames of the film and immediately before either the commencement of automatic film rewinding or the commencement of rewinding the film in a halfway used state. 
     After several frames of the film have been exposed for photo-taking, the film winding speed of the camera becomes faster than the film thrusting speed of the fork gear  11 . This brings about a state in which the abutting part  22   a  of the fork  22  comes to push the abutting part  11   a  of the fork gear  11 . In that state, the fork gear  11  is caused to rotate no longer by the film transport motor  28  but by the fork  22 . Any difference resulting from this change is absorbed by a one-way mechanism (not shown). 
     In the state of FIGS.  17 ( a ) and  17 ( b ), when the fork gear  11  is caused to rotate counterclockwise by energizing the film transport motor  28  in the direction of film rewinding, the planet gear  12  comes to revolve also counterclockwise. The planet gear  12  is then driven to change its position of FIG.  18 ( b ) to its position shown in FIG.  8 ( b ). Then, the film rewinding action comes to an end upon completion of setting an indication showing the using state of the film cartridge. In this instance, since the driving part  3   c  of the driving lever  3  is of course not located within the revolving locus of the shaft  13  of the planet gear  12 , the shaft  13  never abuts on the driving part  3   c.    
     FIGS.  19 ( a ) and  19 ( b ) and FIGS.  20 ( a ) and  20 ( b ) show states obtained when an irrational operation is performed at the commencement of the film rewinding action. 
     In the case of FIGS.  19 ( a ) and  19 ( b ), the shaft  3   b  of the driving lever  3  is caused to be pushed with the elastic part  15   a  of the leaf spring  15  by operating the operation knob  7 . The driving lever  3  is thus caused to swing counterclockwise against the urging force of the torsion spring  5  until the driving lever  3  abuts on the stopper part  2   d  of the hook lever  2 . The driving lever  3  is thus set in a set position where the cartridge chamber cover  6  can be unlocked by the rotation of the fork gear  11 . The driving part  3   c  of the driving lever  3  is then set within the revolving locus of the shaft  13  of the planet gear  12 . After that, the film rewinding action is allowed to be performed. The shaft  13  then of course comes to abut on the driving part  3   c  of the driving lever  3 . However, when the film rewinding action is carried on under this condition as shown in FIGS.  20 ( a ) and  20 ( b ), the elastic part  15   a  of the leaf spring  15  is elastically deformed to allow the shaft  13  of the planet gear  12  to revolve further, so that the state of the FIGS.  20 ( a ) and  20 ( b ) can be shifted to the state of FIGS.  8 ( a ) and  8 ( b ). This enables the camera to carry out the film rewinding action irrespective of the irrational operation. 
     Further, after the display indication is set to indicate the using state of the film cartridge to complete the film rewinding action, the operation knob  7  is operated for taking the film cartridge out from the camera body  1  to shift the state of FIGS.  8 ( a ) and  8 ( b ) to the state of FIGS.  11 ( a ) and  11 ( b ). In that instance, if the cartridge chamber cover  6  is irrationally held, for example, by the hand or the like to prevent the cartridge chamber cover  6  from being opened, the state of the camera shifts from the state of FIGS.  11 ( a ) and  11 ( b ) to the state of FIGS.  15 ( a ) and  15 ( b ) and further to the state of FIGS.  16 ( a ) and  16 ( b ) in such a way as to lock the cartridge chamber cover  6  again before the cartridge chamber cover  6  opens. Under such a condition, the lock completion switch  17  alone turns off from its on-state and then again turns on, while the cartridge presence/absence detecting switch  16  is left in its on-state. The turning-off-and-on state of the switch  17  enables the control IC of the camera to find that the film cartridge has not been taken out as yet. The control IC then causes the fork gear  11  to be driven counterclockwise to bring the planet gear  12  back to its standby position shown in FIGS.  8 ( a ) and  8 ( b ). 
     At this time, even if the operation knob  7  is operated while the switch contact piece  8  is in its on-state, the planet gear  12  can be brought back to the standby position without fail in the same manner as in the cases of FIGS.  19 ( a ) and  19 ( b ) and FIGS.  20 ( a ) and  20 ( b ). However, if the action of bringing the planet gear  12  back to the standby position is repeated many times, the idle rotation allowance for the fork gear  11  and the fork  22  becomes unstable. This problem can be solved and the idle rotation allowance for the fork gear  11  and the fork  22  can be stably set by always setting the using state of the film cartridge in bringing the planet gear  11  back to its standby position. 
     In the above-stated case, the operation knob  7  is operated not particularly as an irrational operation. However, the embodiment is arranged such that, after the action of bringing the planet gear  12  back to the standby position is performed as the cartridge chamber cover  6  fails to open, for example, due to some malfunction, the unlocking action on the cartridge chamber cover  6  is not allowed to be carried out unless the patterns  9   a  and  9   c  of the switch contact piece  8  are found to be turned on after they are turned off once, even if the operation knob  7  is operated while the patterns  9   a  and  9   c  of the switch contact piece  8  are in their on-states. This arrangement effectively prevents an attempt to perform the unlocking action on the cartridge chamber cover  6  from being uselessly carried on until the electric energy of a power supply comes to exhaust. A safety effect can be enhanced by arranging the cartridge chamber cover unlocking action to be inhibited unless the patterns  9   a  and  9   c  of the switch contact piece  8  are detected to be turned on again after the patterns  9   a  and  9   b  are turned on, not only after having the contacts  9   a  and  9   c  turned off once. 
     Other conceivable irrational operations include a case where the operation knob  7  is operated while the camera is in process of performing some action. In such a case, possible dangers are avoidable by suspending the action of the camera when the patterns  9   a  and  9   b  of the switch contact piece  8  are turned off. The camera action does not have to be suspended in the case of the action of bringing the planet gear  12  into the standby position by rotating the fork gear  11  in the direction of film rewinding, because no trouble arises in this case. However, when the fork gear  11  rotates clockwise as in the case of thrust driving from the standby position, the cartridge chamber cover  6  might be unlocked. In that case, the camera action is suspended until the patterns  9   a  and  9   b  of the switch contact piece  8  turn on. 
     FIG. 21 is a block diagram showing the electrical arrangement of only such parts that essentially relate to the embodiment of the invention. 
     Referring to FIG. 21, the control IC  100  of the camera is arranged to control various actions. A battery  101  is used as a power supply for the camera. A motor driver  102  is arranged to drive the film transport motor  28 . The cartridge presence/absence detecting switch  16  has contact pieces  16   a  and  16   b.  The lock completion switch  7  has contact pieces  17   a  and  17   b.  The patterns  9   a,    9   b  and  9   c  are arranged together with the switch contact piece  8  (not shown in FIG. 21) to detect the operated state of the operation knob  7 . The switch contact piece  8  is arranged to turn on the patterns  9   a  and  9   b  when the operation knob  7  is not operated and to turn on the patterns  9   a  and  9   c  when the operation knob  7  is operated. These states of the operation knob  7  are expressed herein, for the sake of expedience, as “the patterns  9   a  and  9   b  are on” and “the patterns  9   a  and  9   c  are on”. 
     FIGS. 22,  23  and  24  are flow charts showing a flow of operation of the embodiment including the unlocking action on the cartridge chamber cover  6 . The operation is described below with reference to these flow charts. 
     At a step S 1 , a check is made by the control IC  100  to find if the cartridge presence/absence detecting switch  16  (hereinafter referred to simply as the switch  16 ) is in an on-state or off-state. In other words, the check is made to find whether or not the camera is loaded with a film cartridge. If the switch  16  is found to be in its off-state thus indicating the absence of the film cartridge, the flow proceeds to a step S 2 . At the step S 2 , the flow waits until the patterns  9   a  and  9   c  turn on. In other words, the flow of operation remains in a standby state until the operation knob  7  is operated to open the cartridge chamber cover  6 . When the camera is not loaded with any film cartridge, the fork gear  11  is always in a standby position. In that case, it is not necessary to make a check for the on-states of the patterns  9   a  and  9   b.  Therefore, in that case, the check is made only for the on-state of the patterns  9   a  and  9   c  as mentioned above without making any check for the states of the patterns  9   a  and  9   b.    
     When the patterns  9   a  and  9   c  turn on, the flow proceeds from the step S 2  to a step S 3 . At the step S 3 , the film transport motor  28  is driven through the motor driver  102  to rotate the fork gear  11  in the direction of thrust. By this, the unlocking action on the cartridge chamber cover  6  is caused to begin. The planet gear  12  then begins to revolve clockwise. The driving lever  3  and the hook lever  2  which are located within the locus of revolution come to swing counterclockwise. Then, the lock completion switch  17  (hereinafter referred to simply as the switch  17 ) which has been in its on-state eventually comes to turn off, as shown in FIGS.  11 ( a ) and  11 ( b ). At the next step S 4 , the flow waits for turningoff of the switch  17 . When the switch  17  turns off, the flow proceeds from the step S 4  to a step S 5 . At the step S 5 , the flow waits for completion of a predetermined count by a timer. Meanwhile, the planet gear  12 , the driving lever  3 , etc., are moving from the state of FIGS.  12 ( a ) and  12 ( b ) to the state of FIGS.  13 ( a ) and  13 ( b ) and further to the state of FIGS.  14 ( a ) and  14 ( b ), as mentioned in the foregoing. The above-stated use of timer may be replaced, for example, with some other arrangement to detect the rotational frequency of the film transport motor  28 . 
     Upon completion of the predetermined count by the timer, the flow proceeds from the step S 5  to a step S 6  as the camera has already reached by then the state of FIGS.  14 ( a ) and  14 ( b ). At the step S 6 , the driving action of the film transport motor  28  is brought to a stop. At this time, the cartridge chamber cover  6  has already been unlocked. The cartridge chamber cover  6  is then caused to be fully opened by swinging the cartridge chamber cover  6  on a hinge shaft (not shown) under the urging force of a spring (not shown). The camera can be loaded with a film cartridge in this state. At the next step S 7 , the flow waits until the switch  17  turns on. When the switch  17  turns on thus indicating that the cartridge chamber cover  6  is closed, the flow proceeds to a step S 8 . At the step S 8 , a check is made through the state of the switch  16  to find if the camera is actually loaded with the film cartridge. If the switch  16  is found to remain in its off-state, it indicates either that the cartridge chamber cover  6  is closed again without loading the film cartridge or that the cartridge chamber cover  6  is irrationally prevented from opening by the hand at the time of unlocking the cartridge chamber cover  6 . In such a case, the flow proceeds from the step S 8  to steps S 9 , S 10  and S 11  one after another. At these steps S 9 , S 10  and S 11 , the planet gear  12  is brought back to its standby position by driving the motor  28  for a predetermined period of time to cause the fork gear  11  to rotate in the direction of film rewinding. At steps S 12  and S 13 , the flow waits until the patterns  9   a  and  9   c  turn off and, after that, the patterns  9   a  and  9   b  turn on. The flow then comes to an end. The steps S 12  and S 13  are provide as a safety measure for preventing a restart of operation with the operation knob  7  left at an operated position. 
     In a case where the camera is found at the step S 1  to have already been loaded with a film cartridge, the flow proceeds from the step S 1  to a step S 14  (FIG.  23 ). At the step S 14 , the flow waits until the operation knob  7  is operated for taking out the film cartridge. In other words, a check is made to find if the patterns  9   a  and  9   c  turn on. If so, the flow proceeds to a step S 15 . At the step S 15 , the motor  28  is driven to rotate the fork gear  11  in the direction of thrust for unlocking the cartridge chamber cover  6 . At the step S 16 , the flow waits until the switch  17  turns off, that is, waits for the state of FIGS.  11 ( a ) and  11 ( b ). When the switch  17  turns off, the flow proceeds to a step S 17 . At the step S 17 , the flow waits until completion of a predetermined count by the timer for the shift of the state of FIGS.  11 ( a ) and  11 ( b ) to the state of FIGS.  14 ( a ) and  14 ( b ). The state of the switch  17  is thus checked during this waiting period. The step S 17  is provided in consideration of possibility of having the cartridge chamber cover  6  in a state of being prevented by the hand from opening when the cartridge chamber cover  6  is unlocked, as mentioned above. In a case where the cartridge chamber cover  6  is kept closed by an irrational operation or the like, the switch  17  turns on before completion of the predetermined count. In that case, the hook claw  4  fails to be hooked on the lock part  1   e  of the camera body  1  to cause the driving lever  3  and the hook lever  2  to come back to their positions of FIGS.  16 ( a ) and  16 ( b ), even when the state of FIGS.  14 ( a ) and  14 ( b ) shifts to the state of FIG.  15 ( a ) and  15 ( b ). 
     If the switch  17  is found at the step S 18  to be in its on-state, the flow proceeds to a step S 20  and, then, a step S 20 - 1 . At the steps S 20  and S 20 - 1 , in order to bring the planet gear  12 , etc., back to their standby positions, the film transport motor  28  is driven to rotate the fork gear  11  in the direction of film rewinding for a period of a predetermined count by the timer. After that, at steps S 21  and S 22 , since the idle rotation allowance for the fork  22  and the fork gear  11  might have disappeared by then, the film using state is set again. After completion of this setting, the flow proceeds from the step S 22  to a step S 23 . At the step S 23 , the driving action of the motor  28  is brought to a stop. At steps S 24  and S 25 , the flow waits until the patterns  9   a  and  9   c  turn off and then the patterns  9   a  and  9   b  turn on. After that, the flow comes to an end. 
     Further, in a case where the predetermined count by the timer is found at the step S 17  to have finished without having the switch  17  turn on before the end of the count which indicates the shift of the state of FIGS.  11 ( a ) and  11 ( b ) to the state of FIGS.  14 ( a ) and  14 ( b ), the flow proceeds from the step S 17  to a step S 26 . At the step S 26 , the driving action of the film transport motor  28  which has begun at the step S 15  is brought to a stop. At the next step S 27 , a check is made for the state of the switch  16  to find whether or not the film cartridge is taken out. If the switch  17  is turned on without turning off the switch  16 , this state indicates a case where the film cartridge is not taken out and the cartridge chamber cover  6  is closed, despite the fact that the cartridge chamber cover  6  is unlocked and opened in a normal manner. In that case, therefore, the flow proceeds from the step S 28  to the step S 20 . Then, the processes of the steps S 21  to S 25  are executed, including setting the planet gear  12  in its standby position, setting the film using state, etc., before the flow is terminated. 
     If the switch  16  is found at the step S 27  to be in its off-state thus indicating that the film cartridge is taken out in a normal manner. The flow proceeds from the step S 27  to a step S 29 . At the step S 29 , the control IC  100  resets information on the film using state stored in a memory disposed therein. The flow then proceeds to the step S 7  of FIG. 22 to wait for closing of the cartridge chamber cover  6 . 
     Further, if the switch  16  is found at the step S 8  of FIG. 22 to be in its on-state thus indicating that the camera is loaded with a film cartridge, the flow proceeds from the step S 8  of FIGS. 22 to a step S 30  of FIG.  24 . At the step S 30 , the film transport motor  28  is driven to rotate the fork gear  11  in the direction of thrust. At the next step S 31 , the using state of the film cartridge, such as a unexposed state, a halfway exposed state, etc., of the film cartridge, is detected by detecting the phase of a data disk provided on the film cartridge. The method for making this detection is well known and, therefore, the details of the detecting method are omitted from the description. The reading action on the data disk may be performed by driving the film in the direction of film rewinding. At a step S 32 , the result of detection of the state of the film is checked to find if the film is usable. If not, i.e., in the event of a developed film or a film having all frames thereof already exposed, the flow proceeds from the step S 32  to a step S 40 . At the step S 40 , the motor  28  is driven to rotate the fork gear  11  in the direction of film rewinding. At the next step S 41 , the flow waits for completion of film rewinding. At a step S 42 , information on the film using state is set. At a step S 43 , the driving action of the film transport motor  28  is brought to a stop. After the step S 43 , the flow proceeds to steps S 44  and S 45  to wait until the patterns  9   a  and  9   c  turn off and then the patterns  9   a  and  9   b  turn on. After that, the flow is terminated. 
     If the film is found at the step S 32  to be a usable film, such as a new film or a halfway exposed film, the flow proceeds from the step S 32  to a step S 33 . At the step S 33 , information on the film of varied kinds, such as the prescribed number of frames of the film, an ISO sensitivity value of the film, etc., is read from the data disk. At the next step S 34 , a check is made to find if the film is a new film. If so, the flow proceeds to a step S 35 . At the step S 35 , an automatic loading action is performed to set the first frame of the film at an aperture position. At a step S 36 , the driving action of the film transport motor  28  is brought to a stop. At a step S 37 , a normal photo-taking action is performed. The photo-taking action is performed until all the prescribed number of frames are found to have been exposed at a step S 39 . However, in a case where a manual rewinding switch is found at a step S 38  to be turned on while the photo-taking action is performed only on an intermediate frame, i.e., only halfway on the film, the flow proceeds from the step S 38  to the step S 40  to rewind the film in the manner as described above before termination of the flow. Further, in the case of completion of the photo-taking action on all the prescribed number of frames, the flow proceeds from the step S 39  also to the step S 40  to rewind the film before termination of the flow. 
     Further, if the film with which the camera is currently loaded is found at the step S 34  to be a halfway used (exposed) film, the flow proceeds from the step S 34  to steps S 46  and S 47 . At the steps S 46  and S 47 , a leader frame among other unexposed frames is set at the aperture position in accordance with a known method by using a magnetic head (not shown). After that, the motor  28  is brought to a stop. In this instance, the motor  28  is allowed to overrun to an extent corresponding, for example, to about one frame before the motor  28  comes to a stop. Therefore, at subsequent steps S 48  to S 53 , the leader frame among unexposed frames is precisely set at the aperture position by rewinding a two-frame amount of the film including the overrunning frame and, after that, by winding the film to an extent corresponding to one frame. 
     After rewinding the two-frame amount of film, the thrust winding action is performed at the step S 52 . However, since the fork gear  11  rotates from a film rewinding side to the trust direction for this action, if the operation knob  7  happens to be operated at this time, the cartridge chamber cover  6  would be unlocked to cause the film to be accidentally exposed to light. To prevent this trouble in thrust-driving the fork gear  11  after the two-frame rewinding rotation, therefore, it is necessary to monitor and ensure, at the step S 51 , that the patterns  9   a  and  9   b  are in their on-states, i.e., to ensure that the operation knob  7  is not operated during this process. If the operation knob  7  is irrationally operated during this process, the patterns  9   a  and  9   b  turn off. In that event, the flow proceeds from the step S 51  back to the step S 50  to stop the film transport motor  28  from rotating to stop the cartridge chamber cover  6  from being unintentionally unlocked. 
     When the patterns  9   a  and  9   b  turn on again with the operation knob  7  released from an operation thereon, the flow proceeds from the step S 51  to the next step S 52 . At the step S 52 , the film transport motor  28  is driven to cause the fork gear  11  to rotate again in the direction of thrust. At the step S 53 , a check is made to find if the leader of unexposed frames is completely set in the aperture position. If so, the flow proceeds from the step S 53  to the step S 36 . At the step S 36 , the motor  28  is stopped from rotating by deenergizing the motor  28  and the flow comes to do the normal photo-taking action. 
     A series of processes thus comes to an end. 
     The advantages of the embodiment of the invention are recapitulated as follows. 
     1) After the operation knob  7  is operated for opening the cartridge chamber cover  6 , the fork gear  11  is rotated to cause the planet gear  12  to revolve. The revolution of the planet gear  12  causes the hook lever  2  and the driving lever  3  to move from their state shown in FIGS.  10 ( a ) and  10 ( b ) to the state of FIGS.  11 ( a ) and  11 ( b ) and, then, to the state of FIGS.  12 ( a ) and  12 ( b ) in such a way as to permit unlocking the cartridge chamber cover  6 . When the operation knob  7  is not operated, no restriction is imposed on the rotating direction of the film winding spool of the film cartridge. Under this condition, therefore, the spool is rotated in the direction of film rewinding before thrust driving, so that data provided on the data disk can be read. In a case where the camera is loaded with a halfway-used film cartridge (containing a film having some frames left unexposed or unused), a search is made for unexposed frames. Upon completion of the search, the film is rewound once and, after that, the leader of unexposed frames can be adequately set in position. 
     2) The fork  22  which engages the film supply spool of the film cartridge and the fork gear  11  which drives the fork  22  are arranged to have a predetermined idle rotation angle. In rotating the fork gear  11  for unlocking the cartridge chamber cover  6  after the operation knob  7  is operated, the fork gear  11  is arranged not to drive the fork  22 , as shown in FIGS.  9 ( a ) and  9 ( b ) to FIGS.  15 ( a ) and  15 ( b ). This arrangement effectively prevents information on the film using state set upon completion of film rewinding from being varied by the unlocking action on the cartridge chamber cover  6 . 
     3) The driving lever  3 , etc., which are provided for moving the cartridge chamber cover  6  to an unlocking position through the rotation of the fork gear  11  after the operation of the operation knob  7  are arranged to be set in position by means of the leaf spring  15  which is an elastic member. Therefore, even under such an irrational operation that the operation knob  7  is left at its operated position, the driving lever  3 , etc., can be brought back to their standby positions by deforming the leaf spring  15 . That arrangement permits film rewinding even under such a condition. 
     4) The cartridge chamber cover  6  might happen to be held by the hand to prevent the cartridge chamber cover  6  from opening after completion of the unlocking action performed on the cartridge chamber cover  6  by the rotation of the fork gear  11  with the operation knob  7  operated. In such a case, the fork gear  11  is arranged to be rotated back to the standby position which is obtained before the operation knob  7  is operated. That arrangement permits a prompt restart under such an irrational operation, so that the operability of the camera can be enhanced. 
     5) In the case of Para. 4) above, the rotation of the fork gear  11  with the cartridge chamber cover  6  not opened is arranged to be made in the direction of film rewinding. Therefore, the film is never thrust-driven again, so that a restart can be promptly made to enhance the operability of the camera. 
     6) In a case where the camera is loaded with a film cartridge when the driving lever, etc., are brought back to their standby positions, the embodiment is arranged to reset the display indication of a film using state. The arrangement enhances the reliability of the display indication of the film using state. 
     7) The arrangement for unlocking the cartridge chamber cover  6  by causing the fork gear  11  to rotate after the operation knob  7  is operated is not only applicable to a camera but can be simply made applicable also to any other apparatuses of the kind to be loaded with a film cartridge with a minor modification. 
     8) The embodiment is arranged to bring the rotation of the fork gear  11  to a stop when the operation knob  7  is found to be operated while the fork gear  11  is rotating, i.e., while the planetary gear mechanism is in process of revolution. The arrangement thus effectively prevents any malfunction from taking place in a case where the cartridge chamber cover  6  should not be opened. 
     9) In the event of Para. 8) above, the fork gear  11  is inhibited from rotating only in the direction of thrusting the film winding speel forward to prevent any malfunction in a case where a malfunction is possible. If there is no possibility of a malfunction, the rotation of the fork gear  11  in that direction is not brought to a stop, so that the operability of the camera can be enhanced. 
     10) In the event of such a trouble that the cartridge chamber cover  6  is, for example, held by the hand and cannot be opened, despite completion of unlocking the cartridge chamber cover  6  by the rotation of the fork gear  11  with the operation knob  7  operated, the fork gear  11  is rotated to bring the state of the camera back to a state obtained before the operation knob  7  is operated. However, if the operation knob  7  still remains in its operated state, the unlocking action on the cartridge chamber cover  6  is not performed until detection of the fact that the operation on the operation knob  7  is temporarily cancelled. By this arrangement, the action of bringing the camera back to its standby state can be canceled at once, so that the action of bringing back to the standby state does not have to be repeated until the electric energy of the power supply exhausts even in a case where the operation knob  7  is caused to become immovable by some reason. 
     While the invention is applied to a camera in the case of the embodiment disclosed, the invention is not limited to cameras but is applicable to any apparatus that is arranged to use a film cartridge. 
     In the case of the embodiment, the shaft  13  of the planet gear  12  is arranged to act as a cartridge chamber cover unlocking member to cause the driving lever  3  to swing from its position where it is brought into the locus of revolution of the planet gear  12  with the operation knob  7  operated. However, the invention is not limited to such an arrangement. The unlocking action may be arranged to be carried out by means of a planetary lever or the like. Such a modification is possible even in a case where the revolution of the planet gear is arranged to be made on one side which differs 180 degrees from the revolving side in the embodiment disclosed above. 
     As described above, when a cartridge chamber cover opening knob, i.e., the operation knob  7 , is not operated, no limitation is imposed on the direction of rotating the film winding spool of the film cartridge. Under this condition, the data of a data disk can be read by rotating the film winding spool in the direction of film rewinding before performing a thrust driving action on the film. Besides, in a case where the camera is loaded with a halfway-used film cartridge, the cartridge chamber cover opening-and-closing device according to the invention permits the camera to temporarily rewind the film upon detection of an unexposed frame, and after that, to set the unexposed frame accurately at an aperture (exposure) position.