Patent Document

This application is a continuation of application Ser. No. 8/193,555 filed Feb. 8, 1994, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a camera adapted for films provided with magnetic storage portions and, in particular, to an improvement of information writing to the magnetic storage portion. 
     2. Related Background Art 
     Conventionally, U.S. Pat. No. 4,977,419 discloses a color negative film including a virtually transparent magnetic layer on a base surface of the film, and a camera having a magnetic head for magnetically recording information in the film or for reading the information recorded in the film. It also discloses to provide on an outside edge of the exposed face of the film a plurality of recording tracks in which the camera records information magnetically. This increases the amount of information to be recorded for individual frames by means of increasing the number of recording tracks. 
     Disclosed as the information recordable by the camera is photographing information such as the date of photographing, time, the type of illumination light source used upon photographing, pseudo zoom information, exposing time, diaphragm values or the like. 
     Alternatively, U.S. Pat. No. 4,878,075 discloses that a filmstrip is previously provided with film information written therein such as film sensitivity and film regulated frame number, and that a camera reads this information before exposure while it re-writes this information upon taking up the film after completion of exposure to record various types of information upon photographing. 
     To read film information previously written in a magnetic layer on a base side of the film or to write photographing information in the magnetic layer in cooperation with an exposing operation by using a magnetic head disposed in a camera, the film is required to be transported with the magnetic head being joined to the above mentioned magnetic layer. With this respect, typical cameras are so structured that a film is pinched by spring operation between the magnetic head disposed on the base side of the film and a pad disposed at a position opposing to said magnetic head on the emulsion-applied surface of the film. Accordingly, flaws or pressure marks (sensitizing due to pressure) are caused on sliding portions to the magnetic head because of the pressure required for pinching. As a result, reading of the film information and writing of the photographing data by the camera are made only at the peripheries of frames out of the frames of the film. 
     FIGS. 6 and 7 are views for use describing the above. FIG. 6 is a view illustrating operation of magnetic recording on the film. In FIG. 6, F represents a film including a magnetic film (hereinafter, simply referred to as a film), F 1  and F 2  represent exposed frames, F 3  represents an unexposed frame and P represents a perforation. T 0  represents a film information track previously magnetically recorded in the film F, in which film information such as an ISO sensitivity of the film is recorded. A reference numeral  101  represents a magnetic head of a camera. The magnetic head comprises a first magnetic track forming unit  102  and a second magnetic track forming unit  103 . T 1  and T 2  represent first and second photographing information tracks, respectively, for individual frames recorded by the first and the second track forming units  102  and  103  in place of the film information in the film information track T 0  (overwriting using saturation recording) before one frame of the film is transported in a direction depicted by an arrow A. 
     FIG. 7 is a vertical sectional view of a camera having the above mentioned magnetic head  101 . A reference numeral  111  represents a camera body provided with a well-known aperture opening  111   a , a pair of upper and lower outer rails  111   b ,  111   b , and a pair of upper and lower inner rails  111   c ,  111   c . A reference numeral  112  represents a platen abutted to the outer rail  111   b . The frame F travels through or stopped for exposure at a space (tunnel) defined by the outer rail  111   b , the inner rail  111   c  and the platen  112 . 
     The magnetic head  101  is secured to the platen  112  through a mounting plate  104  attached thereto and a vis  105 . The first and the second track forming arrangements  102  and  103  are located at a position sliding with the film F from a notch  112   a  of the platen  112 . In addition, the track forming arrangements  102  and  103  are laid out at a position outside the frame (depicted by C in the figure) by a photographing lens L. A reference numeral  113  represents a pad of an elastic material. The pad is secured to a receiving member  114   a  of a lever  114 . The lever  114  comprises elongated bores  114   b  and  114   c . Pins  115  and  116  are inserted into the elongated bores  114   b  and  114   c , respectively. The pins  115  and  116  are fixed to the camera body  111 . In addition, the lever  114  is forced rightward in the figure by a spring  117 . The spring force of the spring  117  and the pad  113  forces the traveling film F continuously to the first and second track forming arrangements  102  and  103  of the magnetic head  101 . (In FIG. 7, illustrated is a condition where the first and the second track forming arrangements are before forced.) 
     In this event, an alternating current adapted to a signal to be recorded flows through the first and the second track forming arrangements  102  and  103  to conduct magnetic recording. A magnetic field H generated in the track forming arrangements  102  and  103  are given by H∝T×A, where T represents the number of windings of a coil of the track forming arrangement while A represents a current value flowing through the coil. The magnetic field H to be required depends on the coercively of a medium subjected to the magnetic recording (the magnetic storage layer of the film F in this specification). A recording energy (i.e., the magnetic field generated at the track forming arrangement; the number of windings of the coil is involved in the direct current resistance, so that to increase H∝T×A corresponds to a power increase with respect to the device) applied by the device (the camera in this specification) to each track forming arrangement is normally constant. In view of reducing the energy for the device, the smaller recording energy is preferable as long as the coercive force of the medium can be withdrawn. 
     However, the above mentioned prior art has a disadvantage that the magnetic recording may be incomplete in the photographing information track (corresponding to T 1  in FIG. 6) at the transversal end of the film. This is because the film end is curled in the direction away from the magnetic head  101  as depicted by FC in FIG.  7 . Contact between the track forming arrangements  102 ,  103  and the film F is maintained by the spring  117  and the pad  113 . However, the curling force is slightly larger than the spring force and the pad  113  is insufficient for forcing the film. As a result, a small gap (depicted by S in FIG. 7) is generated at the position of the track forming arrangement  102  close to the film end. This spacing loss is mainly responsible for the incomplete magnetic recording. 
     In addition, as shown in right-hand portion of FIG. 7, the above mentioned problem may be solved by means of attaching the magnetic head  101  to the platen  112  inclined by an angle θ to the direction along the curling of the film, which is still not a complete solution to the above problem. 
     SUMMARY OF THE INVENTION 
     According to one aspect, the present invention is a camera adapted for films provided with magnetic storage portions or a magnetic recording apparatus for the camera of the type described comprising first information writing means for writing information in a first area of a magnetic storage portion of the film; and second information writing means for writing information in a second area of the magnetic storage portion, the second area being outside the first area of the first information writing means, in a transverse direction the second information writing means comprising means for elongating a distance to the second area of the magnetic storage portion of the film in which the second information writing means is capable of writing information than a distance to the first area of the magnetic storage portion of the film in which the first information writing means is capable of writing information. The present invention is thus directed to allow writing information in a film advantageously without causing increase of consumed energy, enlarging of the apparatus or degradation of writing performances. 
     Another aspect of the present invention will become more fully apparent from the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a structural diagram showing a magnetic recording circuit of a camera according to a first embodiment of the present invention; 
     FIG. 2 is an outer configuration of a magnetic head according to a second embodiment of the present invention; 
     FIG. 3 is a view showing an inner structure of the magnetic head according to the second embodiment of the present invention; 
     FIG. 4 is a structural diagram of a magnetic recording circuit of a camera implementing the magnetic head illustrated in FIGS. 2 and 3; 
     FIGS. 5A and 5B are enlarged representations of magnetic gap of a magnetic head according to a third embodiment of the present invention; 
     FIG. 6 is a view illustrating operation of magnetic recording on the film; and 
     FIG. 7 is a vertical sectional view of a camera having a magnetic head. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred of the present invention are now described with reference to the accompanying drawings. 
     FIG. 1 is a structural diagram of a magnetic recording circuit  1  of a camera according to a first embodiment of the present invention. In FIG. 1, reference numerals  2  and  3  represent first and second track forming arrangements. As in Related Background Art, the first track forming arrangement  2  is a track forming arrangement laid out at a position closer to the film transversal end relative to the second track forming arrangement  3 . The first track forming arrangement  2  comprises a core  2   a  and a coil  2   b . The core  2   a  is made of a material having high magnetic permeability on which the coil  2   b  is wound. Similarly, the second track forming arrangement  3  comprises a core  3   a  and a coil  3   b . Reference numerals  4  and  5  represent constant current circuits for use in providing currents I4 and I5 to the first and the second track forming arrangements  2  and  3 , respectively. The applied currents are set as I4&gt;I5. Reference numerals  6 ,  8 ,  10  and  12  represent NPN transistors while reference numerals  7 ,  9 ,  11  and  13  represent PNP transistors. A reference numeral  14  represents a control circuit. The control circuit  14  controls terminals  14   a  through  14   h  in synchronism with a magnetic signal to be recorded. The control circuit  14  forms two photographing information tracks (T 1  and T 2  in FIG. 6) in a magnetic storage layer of the film by providing positive and negative currents independently for the first and the second track forming arrangements  2  and  3 , respectively. Describing the first track forming arrangement  2 , the coil  2   b  is supplied with a positive current by setting  14   a =High (hereinafter, abbreviated as Hi),  14   b =Hi,  14   c =Low (hereinafter, abbreviated as Lo) and  14   d =Lo, thereby recording a positive magnetic field in the first photographing information track (T 1  in FIG. 6) of the film F through the core  2   a . On the contrary, the coil  2   b  is supplied with a negative current by means of setting  14   a =Lo,  14 =Lo,  14   c =Hi and  14   d =Hi, thereby recording a negative magnetic field in the first photographing information track of the film F through the core  2   a . Similarly, the second track forming arrangement  3  records positive and negative magnetic fields in the second photographing information track (T 2  in FIG. 6) through the coil  3   b  and the core  3   a  by controlling the terminals  14   e  through  14   h.    
     Let the number of windings of the coils  2   b  and  3   b  on the core be N, magnetic fields H1 and H2 generated at the first and the second track forming arrangements  2  and  3  are H1∝I4·N and H2∝I5·N, respectively. I4 is larger than I5, i.e., I4&gt;I5, so that H1&gt;H2 can be obtained. Accordingly, the magnetic recording at the first track forming arrangement  2  becomes positive or complete by increasing the magnetic field generated at the first track forming arrangement  2 , where otherwise the spacing loss may be caused. A like recording current may be supplied to the second track forming arrangement  3 . However, supplying larger current to the second track forming arrangement  3 , where no spacing loss is caused is a waste of energy and is not favorable considering the power of the camera operated by a small cell. 
     FIGS. 2 through 4 illustrate a second embodiment of the present invention. FIG. 2 is a view showing an outer configuration of a magnetic head according to this second embodiment while FIG. 3 is a view showing an internal structure thereof. 
     In FIGS. 2 and 3, a reference numeral  21  represents a magnetic head while a reference numeral  27  represents a mounting plate where the magnetic head  21  is secured. The mounting plate  27  is provided with mounting holes  27   a  and  27   b  for mounting the magnetic head  21  to the camera by screws. Reference numerals  22  and  23  are first and second track forming arrangements, respectively. As in the first embodiment, the first track forming arrangement  22  is laid out at the position closer to the film transversal end relative to the second track forming arrangement  23 . The first track forming arrangement  22  comprises a core  22   a , a coil  22   b , a bobbin  22   c  and bobbin terminals  22   d  (not shown) and  22   e . The bobbin  22   c  winds the coil thereon. The bobbin terminals are electrically connected to both ends of the wound coil to provide connection to a driving circuit of the camera. G1 represents a magnetic gap for use in recording the magnetic field generated at the core in the film F. Likewise, the second track forming arrangement  23  comprises a core  23   a , a coil  23   b , a bobbin  23   c , bobbin terminals  23   d  and  23   e  and a magnetic gap G2. In this event, let the number of windings of the coils of the first and the second track forming arrangements  22  and  23  be N1 and N2, respectively, N1&gt;N2 holds. 
     FIG. 4 is a view showing a structure of a magnetic recording circuit  26  of a camera using the magnetic head  21 . This figure is similar to FIG. 1, so that similar reference numerals refer to similar elements and description of such components will be omitted. A difference between FIGS. 1 and 4 is that I24 is equal to I25, i.e., I24=I25, provided that the first and the second track forming arrangements  22  and  23  are supplied with currents I24 and I25 by constant current circuits  24  and  25 , respectively. However, the magnetic fields H1 and H2 generated at the first and the second track forming arrangements  22  and  23  can be given by H1×I4×N1 and H2∝I5×N2. In this event, N1 is larger than N2, i.e., N1&gt;N2, so that H1&gt;H2 holds. Accordingly, the magnetic recording at the first track forming arrangement  22  becomes positive or complete by increasing the recording energy at the first track forming arrangement  22 , where otherwise the spacing loss may be caused. The number of windings of the coil  23   b  of the second track forming arrangement  23  may be increased as in the first track forming arrangement  22 . However, increasing the number of windings results in increase of a head cost and enlargement of the magnetic head. Accordingly, it is not favorable by that considerations to apply this to the second track forming arrangement  23  where no spacing loss is caused. 
     FIGS. 5A and 5B illustrate a third embodiment of the present invention. FIG. 5A is an enlarged representation of a magnetic gap portion of a first track forming arrangement  32  while FIG. 5B is an enlarged representation of the magnetic gap portion of a second track forming arrangement  33 . In this embodiment, the first track forming arrangement  32  is also laid out at the position closer to the film transversal end relative to the second track forming arrangement  33 . In the figure, F represents a film illustrated with a spacing (a gap between the film F and the track forming arrangement) at a distance S being formed. Reference numerals  32   a  and  33   a  represent cores of the first and the second track forming arrangements  32  and  33 , respectively. G1 and G2 represent magnetic gaps generated at the first and the second track forming arrangements  32  and  33 , respectively. In this event, G1 is larger than G2, i.e., G1&gt;G2. With the wider magnetic gap, the magnetic field generated at the magnetic gap is capable of acting on a position further away from the magnetic gap. P1 and P2 are qualitative representations of isomagnetic field lines. Accordingly, it becomes possible with G1&gt;G2 to render the first track forming arrangement  32  less sensitive to the spacing, allowing positive or complete magnetic recording at the first track forming arrangement  32 , where otherwise the spacing loss may be caused. Increasing the magnetic gap is highly effective to enhancing the track forming arrangement against the spacing loss problem where the generated magnetic field may be reduced or the frequency characteristics tends to be degraded. In this respect, it is not favorable to apply this to the second track forming arrangement  33  where no spacing loss is generated. 
     While the above mentioned first through third embodiments have thus been described in conjunction with the case where two track forming arrangements are provided, the present invention is not limited to those specific illustrative embodiments. Instead, the present invention can be applied to a similar apparatus having three or more track forming arrangements. For example, with three track forming arrangements, I1&gt;I2 and/or I3 or I1&gt;I2&gt;I3 holds in the first embodiment, where I1, I2 and I3 are current values supplied to the first through third track forming arrangements from the one closer to the film end. 
     In the second embodiment, N1&gt;N2 and/or N3 or N1&gt;N2&gt;N3 holds, where N1, N2 and N3 are the number of windings of the coils of the first through third track forming arrangements from the one closer to the film end. 
     In the third embodiment, G1w&gt;G2w and/or G3w or G1w&gt;G2w&gt;G3w holds, where G1w, G2w and G3w are widths of magnetic gaps G1, G2 and G3, respectively of the first through third track forming arrangements from the one closer to the film end. All of the above embodiments accord with the spirit of the present invention to overcome the problem of the spacing loss more likely generated at the track forming arrangement closer to the transversal end of the film. 
     As mentioned above, according to the present invention, reliable magnetic recording can be made at all track forming arrangements by: (1) flowing much current through; (2) increasing the number of windings of the coil of; (3) increasing the width of the magnetic gap generated at the track forming arrangement of a plurality of track forming arrangement that is farthest to the exposed frame than others. 
     While the above mentioned embodiments have thus been described in conjunction with the case where the information is written in the magnetic storage layer of the film, the present invention can equally be applied to reading the information out of the magnetic storage layer of the film, thereby improving reading ability against generation of the spacing loss between the magnetic storage layer of the film. 
     In addition, it is apparent that the present invention can equally be applied to an image recording medium other than films or to recording or reading other than the magnetic recording or reading. 
     Further, the present invention can also be applied to an apparatus for recording or reading information similarly other than a camera. 
     Further, the present invention may be achieved as a combination of two or more embodiments, if necessary, or the technical components thereof. 
     The individual components shown in schematic or block form in the Drawings are all well-known in the camera arts and their specific construction and operation are not critical to the operation or best mode for carrying out the invention. 
     While the present invention has been described with respect to what is presently considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Technology Category: 3