Abstract:
A camera for thrusting a film from a film cartridge by rotationally driving a spool in the film cartridge has a measuring construction for measuring the amount of the film thrust from the film cartridge, a sensing construction for sensing the position of a leader of the film thrust from the film cartridge, and a determining circuit for determining whether the film is moving properly, based on the measured thrust amount of the film and the sensed position of the leader of the film.

Description:
This application is a continuation application Ser. No. 08/561,290 filed Nov. 21, 1995, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a camera capable of sensing a film jam. 
     2. Description of the Related Art 
     A well-known type of patrone is loaded in a camera in a state where the leading end (leader) of a film protrudes therefrom. In general, when the patrone is set in a patrone chamber, the leader is drawn out to a take-up spool and a rear cover of the camera is closed, automatic loading of the film is started to take up the film. At this time, if the amount of the leader to be drawn out is too large or too small, automatic loading ends in failure, or the film is inadvertently overdrawn and exposed to light. Furthermore, when prints are obtained from an exposed and developed film (negative or positive), particularly by an automatic printing machine, they may be contrary to the intention of the photograph since the photographing conditions are not known to a photo laboratory. 
     Accordingly, there has recently been proposed a new type of film and film cartridge. 
     FIG. 3 is a perspective view showing a cartridge chamber  14  of a camera using such a film, and a cartridge  10 . A leading portion (leader) of the film is completely wound in the cartridge  10  without protruding outside. When the cartridge  10  is inserted in the cartridge chamber  14  of the camera, a cover (not shown) of the cartridge chamber  14  is closed for shading. 
     FIG. 6 is a perspective view showing the states of the cartridge  10  and the film inside the camera. Numerals  13 ,  19   a ,  19   b  . . .  21   a , and 16 to 18 respectively denote a film, perforations previously provided on the film, and frame areas to be exposed which are so defined corresponding to two perforations as illustrated that an image is formed therein. The film leader does not protrude from the cartridge  10  before loading as shown in FIG.  3 . When the cartridge  10  is loaded in the camera, a fork  15  is rotated by a motor in an extruding direction (in the clockwise direction in FIG. 3) to rotate a spool  23  in the cartridge  10 , by which the film  13  is extruded from the cartridge  10 . This motion for extruding the film  13  from the cartridge  10  is referred to as “thrusting”. Areas  24  to  26  capable of magnetic recording are provided for their respective frames, and can record in the exposed frame which the type of light source, exposure value, the date and the like. 
     This type of cartridge is provided with a disc, referred to as “data disc”, on which the type of the film, the number of frames to be exposed and the ISO speed are recorded in a bar code. FIG. 4 is a plan view of a data disc  22 , and FIG. 5 is a longitudinal sectional view of a part of the cartridge  10  adjacent to the data disc  22 . The data disc  22  is fixed on the spool  23  to rotate in a one-to-one relation to the rotation of the spool  23 . A photoreflector  3  is placed at a position shown in FIG. 5, and information on the data disc  22  is read based on signals from the photoreflector  3  while rotating the fork  15  in the rewind direction. 
     The use of the above-mentioned type of film eliminates the disadvantages of the prior art. 
     When the cartridge is loaded in the camera, the film wound in the cartridge is thrust and slid between a pressure plate and a guide rail. The film leader, which has reached the take-up spool in the camera, is wound on the take-up spool and the film is taken up in correlation to the rotation of the take-up spool. This automatic loading ends in response to sensing of the first frame. During thrusting, the film may be caught somewhere (referred to as “jammed”), which results in loading failure. 
     U.S. patent application Ser. No. 670278/1991, now U.S. Pat. No. 5,521,667, suggests reducing the time taken to recover from loading failure by detecting a jam from the change in film transport speed by using a film transport speed detector located near an aperture, once rewinding the film when the jam occurs while the film is being thrust, and restarting thrusting of the film before the film is completely wound in the cartridge. 
     However, realization of the above suggestion requires the film transport speed detector, which increases the size and cost of the camera. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, there is provided a camera comprising a measuring construction for measuring the thrust amount of a film from a film cartridge, and a sensing construction for sensing the position of a leader portion of the film, wherein the camera judges that a jam has occurred when the measuring construction measures a predetermined thrust amount of the film and the sensing construction does not sense that the leader portion of the film has moved to a predetermined position. 
     Accordingly, it is possible to detect a jam simply and accurately. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing a first embodiment of the present invention; 
     FIG. 2 is a transverse sectional view showing the principal part of a camera according to the first embodiment; 
     FIG. 3 is a perspective view showing a cartridge chamber of the camera shown in FIG. 2 and a film cartridge to be loaded therein; 
     FIG. 4 is a plan view showing a data disc of the film cartridge; 
     FIG. 5 is a longitudinal sectional view of FIG. 3; 
     FIG. 6 is a perspective view showing a state in which a film is thrust from the film cartridge shown in FIG. 3; 
     FIG. 7 consisting of FIGS. 7A and 7B, is a flowchart showing the operation of the first embodiment; 
     FIG. 8 is a flowchart showing the processing at jam detection in the operation shown in FIG. 7; 
     FIG. 9 is a flowchart showing the processing at jam detection in the operation shown in FIG. 7; 
     FIG. 10 consisting of FIGS. 10A and 10B, is a flowchart showing the operation of a second embodiment; 
     FIG. 11 is a flowchart showing the processing at jam detection in the operation shown in FIG. 10; 
     FIG. 12 is a flowchart showing the processing at jam detection in the operation shown in FIG. 10; 
     FIG. 13 is a transverse sectional view showing a camera according to a third embodiment of the present invention; and 
     FIGS.  14 ( a ),  14 ( b ),  14 ( c ), and  14 ( d ) are transverse sectional views showing the operation of the third embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A detailed description of preferred embodiments of the present invention will now be given in conjunction with the accompanying drawings. 
     FIG. 1 is a block diagram showing a first embodiment of the present invention. Referring to FIG. 1, a microcomputer  1  exerts control on operations of various circuits, including time management and computations. A transport motor  7  switches an unillustrated idle gear by its normal and reverse rotations to perform film take-up and rewind operations, and a motor control circuit  6  controls the rotation of the motor  7 . A photoreflector  3  sends data on the film type, the number of frames to be exposed and the ISO speed, which are recorded in a bar code made up of black and white lines on a data disc  22 , as signals 0 and 1 to the microcomputer  1 . Photoreflectors  4  and  5  detect the position of the film based on the presence or absence of reflected light. Since the outputs of the photoreflectors  4  and  5  change depending on the presence or absence of the film thereat, the microcomputer  1  judges, based on the change, the arrival of the film leader and positions of perforations. Numerals  9  and  8  denote a magnetic head and a control circuit for driving the magnetic head  9 , respectively. A switch  2  is used to determine whether a cover of a cartridge chamber is opened or closed, and may be adopted to both a case in which the cover is manually closed by a user and a case in which the cover is closed electrically and automatically by the camera. 
     FIG. 2 is a transverse sectional view showing the principal part of the camera in film transport. Referring to FIG. 2, a photoreflector  5  detects the position of a film  13  to be exposed. The frame is placed in an exposure position by stopping the take-up operation when a perforation  20   a  or  19   a  formed on the right and below the frame reaches the photoreflector  5 . After exposure, when a perforation  20   b  or  19   b  passes through a photoreflector  4  in the operation for rewinding the film in the cartridge  10 , data on exposure conditions is written by the magnetic head  9 . The photoreflector  4  detects the position of the film  13  when data writing is started. The photoreflectors  4  and  5  each detect the film position by using the perforations on the film. 
     In automatic film loading, a fork  15  is rotated in a thrust direction to rotate a spool  23 , thereby sliding the film  13  between a thrust pressure plate  11  and a guide rail. The film  13  is passed through the photoreflector  4 , the magnetic head  9  and the photoreflector  5  in order while still thrusting, and taken up by a take-up spool  12  subsequent to the arrival of the film leader at the take-up spool  12 . When the first frame is sensed, automatic loading is completed. 
     However, if the film does not travel straight unfortunately, it may not slide between the pressure plate  11  and the guide rail, or may be caught by the magnetic head  9  and thereby prohibited from advancing. The following flowcharts show how quickly to sense such states and how to start thrusting over again. 
     FIG. 7 is a flowchart showing an automatic loading (AL) operation of this embodiment. 
     In Step # 2 , a cartridge is inserted and the cover of the cartridge chamber is closed manually by the user or automatically by the camera. After it is confirmed that the cover is closed, the transport motor  7  is rotated in the rewind direction in Step # 3 , by which the power is transmitted to the fork  15  and the spool  23  through an unillustrated gear and the data disc  22  fixed on the spool  23  is also rotated. During this rotation, the contents of the bar code recorded on the data disc  22  are read by the photoreflector  3 . 
     When the transport motor  7  is rotated in the take-up direction in Step # 4 , thrusting is started. Based on the number of frames read from the data disc  22 , the typical film thickness, the thickness of the spool  23  on which the film  13  is wound, and the like, the thrust length of the film  13  needed to make the film leader reach the first photoreflector  4  is calculated in Step # 5 . Since the rotation amount of the data disc  22  and the length of the thrust film are proportional to each other, the above predetermined length is converted into a rotation amount, or the rotation amount is found from fixed values in a preset table according to the number of frames. This rotation amount is taken as R1. An actual rotation amount of the data disc  22  is measured in Step # 6  by reading the bar code on the data disc  22  by the photoreflector  3 . This rotation amount is taken as a first measured rotation amount R2. If the first measured rotation amount R2 is larger than the predetermined rotation amount R1, it is judged in Step # 7  that the film could not reach due to a jam caused upstream from the first photoreflector  4 , and then, error handling is performed in Step # 19 . 
     When it is confirmed in Steps # 8  and # 9  that the film leader has passed through the photoreflector  4 , the rotation amount of the data disc  22  needed to make the film leader reach the second photoreflector  5  is calculated in Step # 10 , or the rotation amount is found from a fixed value table. The obtained rotation amount is taken as a final rotation amount R3. In Step # 11 , an actual rotation amount of the data disc  22  is measured by reading the bar code on the data disc  22  by the photoreflector  5 . This rotation amount is taken as a second measured rotation amount R4. If the second measured rotation amount R4 is larger than the final rotation amount R3, it is determined in Step # 12  that the film could not reach due to a jam caused upstream from the second photoreflector  5 , and error handling is performed in Step # 20 . 
     When it is confirmed in Steps # 13  and # 14  that the film leader has passed through the photoreflector  5 , the film take-up spool  12  is rotated to take up the film  13  in Step # 15 . Thrusting is ended in # 16 , and automatic loading is also ended if the first frame is sensed in Step # 17 . If the first frame is not sensed, error handling is performed in Step # 21 . 
     FIG. 8 is a flowchart showing the process of error handling (1) in a case in which the film leader could not reach the first photoreflector  4  due to a film jam. Film rewinding is immediately started by rotating the transport motor  7  in the reverse direction (rewind direction) in Step # 100 . At this time, the rewinding is performed while photoreflector  3  detects in Steps # 102  and # 103  whether the data disc  22  is rotating. If the data disc  22  is not rotating, although it is almost improbable, the film  13  is caught somewhere due to a jam and rewinding is impossible. Since the cartridge used in this embodiment can be, as distinct from the conventional patrone, taken out of the camera by the user only when the film is completely wound in the cartridge, there is nothing the camera itself can do. In this case, a warning to repair the camera is indicated in Step # 110 , and other operations of the camera are prohibited. However, in this case, it is better to allow a main switch to be turned off. When the data disc  22  is rotating, it is determined in Steps # 104  and # 105  whether the film has been wound into the cartridge. After winding is completed, the number of jams which have occurred, including this jam, is stored in a memory or the like of the microcomputer  1  in Step # 106 . If it is determined in Step # 107  that the stored number of jams is larger than a preset number, the user is given a warning to take this film out since it cannot be used. When the number of jams is below the preset number, thrusting is restarted, and the process returns to Step # 5  in FIG.  7 . If the preset number is set at 0, the cartridge is to be taken out without returning to Step # 5  whenever a jam is detected. 
     FIG. 9 is a flowchart showing the process of error handling in a case in which the occurrence of a jam is detected after the film leader has passed through the second photoreflector  5 . Film rewinding is immediately started by rotating the transport motor  7  in the reverse direction (rewind direction) in Step # 121 . At this time, rewinding is performed while the photoreflector  3  detects in Steps # 122  and # 123  if the data disc  22  is rotating. If the data disc  22  is not rotating, although it is almost improbable, the film is caught somewhere due to a jam and cannot be rewound. Since the cartridge used in this embodiment can be, as distinct from the conventional patrone, taken out of the camera by the user only when the film is completely wound in the cartridge, there is nothing the camera itself can do. In this case, a warning to repair the camera is indicated in Step # 130 , and other operations of the camera are prohibited. However, in this case, it is better to allow the main switch to be turned off. When the data disc  22  is rotating, it is determined in Steps # 124  and # 125  whether the film leader has passed through the photoreflector  4 . If the film leader has passed, the number of jams which have occurred in this film, including this jam, is stored in the memory or the like of the microcomputer  1  in Step # 126 . If it is determined in Step # 127  that the stored number of jams is larger than a preset number, the film is wound into the cartridge while seeing if the data disc  22  is rotating in Steps # 131  and # 132  in the same manner as above. When winding is completed in Step # 134 , the user is given a warning to take this film out since it cannot be used. If the rotation of the data disc  22  is stopped during the film winding, a warning to repair the camera is indicated in Step # 131  similarly to Step # 122 . When the number of jams is below the preset number, thrusting is performed again, and the process returns to Step # 10  or # 15  in FIG.  7 . 
     FIG. 10 consisting of FIGS. 10A and 10B, is a flowchart showing an automatic loading operation in a second embodiment of the present invention. In this embodiment, it is assumed that the photoreflector for reading data on the data disc  22  is not provided. After it is confirmed in Step # 2  that a cartridge is inserted and the cartridge chamber is closed, thrusting is started by rotating the transport motor  7  in the take-up direction in Step # 4 . At this time, the transport motor  7  is rotated at constant speed regardless of battery consumption and temperature by duty driving. 
     While the motor is being rotated (the fork is being rotated at constant speed), the thrust amount of the film needed to make the film reader reach the first photoreflector  4  is obtained in Step # 5 ′. Since the driving time of the motor  7  and the thrust amount of the film are proportional to each other, a probable thrust amount is converted into time, or the thrust time is found from fixed values in a preset table. This predetermined thrust time is taken as T1. In Step # 6 ′, the driving time of the motor is measured as T2. If the measured time T2 is longer than the predetermined thrust time T1, it means that the film could not reach due to a jam caused upstream from the first photoreflector  4 , and error handling is performed in Step # 19 ′. When it is confirmed in Steps # 8  and # 9  that the film leader has passed through the photoreflector  4 , the motor driving time taken to make the film leader reach the second photoreflector  5  is obtained in Step # 10 ′, or read from a fixed value table. The obtained time is taken as a final thrust time T3. In Step # 11 ′, an actual driving time of the motor  7  is measured. This driving time is taken as a final measured time T4. If the final measured time T4 is longer than the final thrust time T3, it is judged in Step # 12 ′ that the film could not reach the second photodetector due to a jam caused upstream from the photoreflector  5 , and error handling is performed in Step # 20 ′. When it is confirmed in Steps # 13  and # 14  that the film leader has passed through the second photoreflector  5 , the take-up spool  12  is rotated to take up the film in Step # 15 . Thrusting is ended in Step # 16 , and automatic loading is also ended when the first frame is sensed in Step # 17 . If the first frame is not sensed, error handling is performed in Step # 21 ′. 
     FIG. 11 is a flowchart showing the process of error handling in a case in which the film leader could not reach the first photoreflector  4  due to a film jam in the second embodiment. This flowchart is almost the same in sequence as that of FIG. 8, and different in that the rotation of the data disc  22  cannot be detected. Film rewinding is immediately started by rotating the transport motor  7  in the reverse direction (rewind direction) in Step # 101 . It is determined in Steps # 104  and # 105  whether the film has been wound into the cartridge. After winding is completed, the number of jams caused in this film, including this jam, is stored in a memory or the like in Step # 106 . If it is determined in Step # 107  the number of jams is larger than a preset value, the user is given a warning to take out this film since it cannot be used. When the number of jams is below the preset value, thrusting is restarted and the process returns to Step # 5 ′ in FIG.  10 . If the preset value is set at 0, the cartridge is taken out without returning to Step # 5 ′ whenever a jam is sensed. 
     FIG. 12 is a flowchart showing the process of error handling in a case in which a jam is detected after the film leader passes through the first photoreflector  4  in the second embodiment. This flowchart is also almost the same in sequence as that of FIG. 8, and different in that the rotation of the data disc  22  cannot be detected. Film rewinding is immediately started by rotating the transport motor  7  in the reverse direction (rewind direction) in Step # 121 . It is determined in Steps # 124  and # 125  whether the film leader has passed through the second photoreflector  5 . If the film leader has passed, the number of jams caused in this film, including this jam, is stored in a memory or the like in Step # 126 . When it is determined in Step # 127  that the number of jams is larger than a preset value, the film is wound into the cartridge. After winding is completed in Step # 134 , the user is given a warning to take out this film since it cannot be used. If the number of jams is below the preset value, thrusting is restarted and the process returns to Step # 10 ′ or # 15  in FIG.  10 . 
     FIGS. 13 to  14 ( a ),  14 ( b ),  14 ( c ),  14 ( d ) show a third embodiment of the present invention. In this embodiment, a photoreflector  27  is added near an exit of a film passing slit of a cartridge  10  as shown in FIG. 13, and connected to a microcomputer in a similar manner to other photoreflectors  3  to  5  in FIG. 1, although not shown in a block diagram. FIG. 14 is an enlarged view of a circled portion in FIG.  13 . FIG.  14 ( a ) shows a state in which a film  13  does not protrude from the cartridge  10 . At this time, since infrared light emitted from the photoreflector  27  does not return thereto due to the absence of the film  13 , which reveals that the film  13  is not out. When thrusting is started and the film  13  comes out of the cartridge  10 , since the infrared light is reflected and returned by the film  13 , it is known that the film  13  has come out. If the film  13  does not come out, since some accident happens to the cartridge  10 , appropriate processing is performed. When the film  13  is thrust normally and inserted between a pressure plate and a guide rail, a state shown in FIG.  14 ( b ) is obtained. However, if the film  13  is caught somewhere, the film  13  is positioned too close to or too apart from the photoreflector  27  as shown in FIG.  14 ( c ) or  14 ( d ). The photoreflector can sense a jam since no infrared light returns thereto if it is too close to or too apart from an object to be sensed. When the jam is sensed, the processing shown in the flowchart of FIG. 8 is executed. 
     According to the above-mentioned embodiments, since it can be determined by a means for sensing the passage of the film, for example, an optical sensing means such as a photoreflector whether the film passes in a good condition, it is possible to achieve smaller size and lower cost of the camera than the conventional method of judging the state of automatic loading by detecting the film speed. 
     Furthermore, the thrust amount of the film needed to make the film leader reach a sensing position can be estimated by utilizing a data disc provided in the film cartridge, and the state of film passage can be judged reliably with a simple structure based on the estimated amount. 
     Still further, if something is wrong with film thrusting, film rewinding is automatically carried out, and therefore, the user of the camera does not have to perform a special operation. At this time, it is unnecessary to return all the thrust film into the cartridge. For example, by returning the film to a position, where the film passage could be confirmed, and restarting thrusting, the time taken to complete automatic loading can be reduced 
     Furthermore, it is possible to sense that the film is not thrust out of the film cartridge itself.