Abstract:
A recording apparatus for a camera using a photographic film bearing a magnetic recording medium comprises a magnetic head capable of assuming a recording position with the magnetic head pressed to the film and a retracted position with the magnetic head away from the film. When the magnetic head is at the recording position, a reference pin engages an edge of the film. To move the magnetic head to the retracted position, a drive mechanism moves the magnetic head in a direction along the film width, thereby disengaging the reference pin from the edge of the film, and then moves the magnetic head in a direction away from the film plane.

Description:
This is a continuation of application Ser. No. 08/134,544 filed Oct. 12, 1993, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a drive mechanism for a magnetic recording head for a camera which uses a silver salt film bearing a magnetic recording medium. 
     2. Related Background Art 
     A system comprising a film having a magnetic track provided thereon in addition to an optical image recording area and a camera for using it has been recently proposed. It is intended to read film information (such as a film sensitivity and a photographed frame count) which has been prerecorded on a magnetic track into a control circuit of a camera and write photographing information (such as a diaphragm value and a shutter speed) onto the magnetic track. 
     In this system, a magnetic head arranged on the camera is pressed to the magnetic track of the film, but since a load to feed the film is high if the film is fed while the magnetic head is pressed to the film, it has been proposed to retract the magnetic head from the film surface when it does not record the information. 
     In order to prevent positional offset of the magnetic head relative to the width of the magnetic track, it has also been proposed to provide a reference member which is substantially integral with the magnetic head and apply a biasing force to continuously abut the reference member against a film edge so that the magnetic head follows even if the film shifts widthwise, to prevent the offset from the magnetic track. 
     However, in this mechanism, if the film is retracted from the pressed position to the film when the film is to be fed, the position of the magnetic head may be shifted due to the widthwise shift of the film under feeding. Since the reference member is biased to abut against the film edge, the reference member interferes with the film surface when the magnetic head is to be moved into the pressed position after the magnetic head has been retracted so that the reference member has been away from the film edge. Thus, the movement of the magnetic head is impeded. 
     In order to prevent this problem, it may be possible to make the reference member sufficiently long to assure that it does not leave the film edge even when the magnetic head is in the retracted position, but this is not preferable because the biasing force which is continuously applied to the film edge from the reference member acts as a load in feeding the film. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, the movement of the recording head between the recording position at which the recording head is pressed to the film and the retracted position is carried out by movement which is away from the film plane and movement along the film width. 
     When the magnetic head is to be moved from the recording position to the retracted position, it is first moved outwardly in a direction the film width so that a reference member is disengaged from the film edge, and then it is moved away from to the film plane to retract. On the other hand, when the magnetic head is to be moved from the retracted position to the recording position, it is first moved toward to the film plane to contact the film and then it is moved inwardly along the film width direction to engage with the film edge the reference member. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a perspective view of an embodiment of the present invention; 
     FIG. 2 shows a front view of a portion of the embodiment of the present invention; 
     FIG. 3 shows a cam plate of the embodiment; 
     FIG. 4 shows a side view of the cam plate of the embodiment; 
     FIG. 5 shows a rear view of the cam plate of the embodiment; 
     FIG. 6 shows a side view of a magnetic head of the embodiment in a retracted position; 
     FIG. 7 shows a side view of the magnetic head of the embodiment in an abutment position; 
     FIG. 8 shows a front view of the magnetic head of the embodiment in the retracted position; 
     FIG. 9 shows a front view of the magnetic head of the embodiment in the abutment position; 
     FIG. 10 shows a front view of a film and a cartridge pertinent to the present invention; and 
     FIG. 11 shows a block diagram of the embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a schematic diagram of an embodiment of the present invention. A film 51 of a cartridge 50 loaded in a camera body 1 is wound up onto a spool 2. The winding operation is carried out by a known powered winding device and the rewinding operation of the film into the cartridge 50 after the completion of the photographing is also carried out by a known rewinding device. The film 51 has a magnetic track 51b provided on one edge of a rear surface thereof as shown in FIG. 10 so that magnetic information may be recorded thereon by a magnetic head to be described later. FIG. 1 shows a retracted position of the magnetic head 16. 
     A base plate 3 which covers an aperture (not shown) is fixed in an intermediate area la between the cartridge 50 and the spool 2. Aperture peripheries 1b, 1c and the base plate 3 form a film path to direct the film 51 into an exposure position. A hole 3a is formed in the base plate 3 at a position facing the magnetic head 16 so that the magnetic head 16 can be pressed to the film 51. 
     A rotary base plate 4 is rotatably pivoted to bearings 3b and 3c of the base plate 3 and it is biased counterclockwise by an actuation device 5. A slidable plate 6 is mounted at a center portion 4a of the plate 4 and a roller 7 is fixed to an end 4b of the plate N. A cam plate 8 is a worm wheel gear rotatably pivoted to a shaft 9 on the base plate 3. It meshes with a worm gear 11 fixed to the shaft of a motor 10 and is driven counterclockwise at a reduced speed by the power of the motor 10. A brush 12 is fixed to the base plate 3 and detects a phase of the cam plate 8 as will be described later. 
     FIG. 2 shows a rear side of the rotary base plate 4, as viewed from the film position. The slide plate 6 is slidably mounted on to the rotary base plate 4 by shafts 13 and 14 and is biased downwardly by an actuation member 15. The magnetic head 16 is fixed to a top 6a thereof and a reference pin 17 is fixed to an end 6b. A fixed pin 18 is fixed at a central portion 6c. 
     A lever 19 is rotatably pivoted to a shaft 20 on the base plate 3. A right end 19a thereof engages with the fixed pin 18 and a left end 19b thereof engages with a second cam 22 of the cam plate 8. 
     FIGS. 3, 4 and 5 show the cam plate 8 and the members engaging therewith. FIG. 3 shows a front view of the cam plate 8. An outer periphery 8a thereof is a worm wheel gear which meshes with the worm gear 11. A first cam 21 having an axial level step is provided at the intermediate area. The first cam 21 has a high area 21a, a low area 21b and intermediate areas 21c and 21d connecting the areas 21 and 21b. Conductive patterns 23a and 23b are arranged at an interval of 180 degrees at a center 8b. The brush 12 abuts against the patterns to connect and disconnect the two brush parts 12a and 12b. FIG. 3 shows a conducting position. 
     FIG. 4 shows a side view of the cam plate 8 showing the high area 21a, the low area 21b and the sloped area 21c of the first cam 21. 
     FIG. 5 shows the second cam 22 on the rear of the cam plate 8. The second cam 22 has a high area 22a which is a portion of a circumference, a low area 22b of a smaller diameter and intermediate areas 22c and 22d connecting the areas 22a and 22b. 
     Phases of the first cam 21 and the second cam 22 are set as follows. In FIG. 3, the roller 7 is mounted on the high area 21a of the first cam 21 and the lever 19 is mounted on the high area 22a of the second cam 22 as shown in FIG 5. As the cam plate 8 is rotated clockwise from that position, the lever 19 is on the high area 22a until the roller 7 reaches the low area 21b. After one half revolution, the roller 7 stays in the low area 21b and the lever 19 also reaches the low area 22b. As the cam plate 8 is further rotated, the lever 19 first reaches the high area 22a and then the roller 7 mounts on the high area 21a from the low area 21b to complete one revolution. 
     FIG. 11 shows a block diagram for the control which comprises a CPU 100, a magnetic information recording control unit 101, a magnetic head 16, a phase detector 102, a motor 10 and a motor control unit 103. The phase detector 102 includes the brush 12, and the conductive patterns 23a, 23b and 23. Other known blocks relating to the film feed control and the exposure control are omitted. 
     An operation of the present embodiment is now explained. FIG. 1 shows the retracted position of the magnetic head 16 as described above. FIG. 6 shows a top view of the rotary base plate 4 and the cam plate 8. The roller 7 is mounted on the high area 21a of first cam 21 so that the magnetic head 16 floats from the film 51. 
     When the recording of the magnetic information is desired and the control circuit issues a signal to command the pressing of the magnetic head 16, the motor 10 is driven, the cam plate 8 is rotated by one half revolution and it is stopped when the brush 12 is contracted by the conductive pattern 23. In this stroke, the roller 7 first falls to the lower area 21b of the first cam 21 so that the rotary base plate which is biased counterclockwise as shown in FIG. 7 follows it. The magnetic head 16 presses the film 51 before the roller 7 falls in the lower area 21b, so the magnetic head 16 is pressed with a constant force by the biasing of the rotary base plate 4. Numeral 24 denotes a pad fixed to the body 1. 
     The position of the second cam 22 and the lever 19 so far is shown in FIG. 8. Since the lever 19 is still on the high area 22a of the second cam 22, the right end 19a of the lever 19 acts as a limit to the fixed pin 18 and the reference pin 17 is kept floated from the film edge 51a. 
     In the next half of the rotation of the cam plate 8, the lever 19 falls in the lower area 22b of the second cam 22 as shown in FIG. 9 so that the slide plate 6 which is biased downwardly is moved downwardly until the reference pin 17 abuts against the edge 51a of the film to vertically position the magnetic head 16. By the biasing to the slide plate 6, the magnetic head 16 is positioned to the magnetic track 51b with a constant force. 
     When the magnetic head 16 is to be retracted and the control circuit issues a signal to command the retraction of the magnetic head 16, the motor 10 is driven and the cam plate 8 is rotated by another half revolution. When the brush 12 is contracted by the conductive pattern 23, the motor 10 is stopped. In this stroke, the opposite operation to that described above is carried out. Namely, since the lever 19 is mounted on the high area 22a of the second cam 22, the lever 19 is rotated counterclockwise and the right end 19a thereof lifts slide plate 6 through the fixed pin 18 to move the reference pin 17 away from the film edge 51a. Then, in the next stroke the roller 7 mounts on the high area 21a of the cam 21 so that the rotary base plate 4 is rotated clockwise against the biasing force and the magnetic head 16 is moved away from the film plane. 
     In the present embodiment, a plurality of strokes are carried out by unidirectional rotation of the motor, although a similar operation may be attained by a forward-reverse rotation. While the positioning and retraction of the magnetic head are carried out in one half revolution in the present embodiment, they may be attained in a smaller revolution. 
     As to the drive source of the head, instead of a separate motor arranged on the same base plate as that for the magnetic head in the present embodiment, another motor in the body, such as a film feed motor, may be used or the cam plate may be directly driven as a rotor of a stepping motor. 
     While the head is a record-only head in the present embodiment, it may be a recording and reproducing head. 
     In accordance with the present invention, when the magnetic head is to be pressed to the film, the magnetic head is first pressed to the film while the reference pin which abuts against the film edge is kept off the edge along the width of the film and then is moved inwardly along the width. Accordingly, the abutment of the reference pin, which is to contact to the film edge, against the film plane to disable the pressing of the magnetic head is prevented.