Abstract:
A heating apparatus which forms an image by heating a sheet-form material carrying image data. The heating apparatus comprises a heater, which is disposed at an axial center portion of the sheet-form material, for directly heating the sheet-form material to a temperature suitable for heat developing processing, and rings or a cylinder for rotating and allowing the sheet-form material to be exposed to the heater. The sheet-form material can be rotated on either an inner or outer surface of the rings or an inner surface of the cylinder. In addition, a plurality of rings can be used which correspond to differing widths of sheet-form material.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a heat developing apparatus, and more precisely, to a heating apparatus which forms an image by heating a sheet-form material, which carries image data thereon. 
     2. Description of the Related Art 
     A lithographic film (a photosensitive material) has been used for a long time for printing newspaper, magazines, and the like. In the same way as a photographic film, an image can be formed on a photosensitive material such as the lithographic film, by carrying out processing (wet processing) such as developing and fixation. However, when each processing such as developing and fixation, is carried out by wet processing, the developing processing becomes complicated. Moreover, since each processing is carried out by soaking the lithographic film in processing tanks in sequence, each of which stores a processing solvent (e.g., a developer or a fixer), there has been a problem with this method in that control of each processing is troublesome, and deterioration of a heat developing apparatus itself is accelerated by dirt or the like adhering to the heat developing apparatus. 
     In contrast, a heat developing apparatus capable of developing processing on photosensitive materials such as the lithographic film without complicated processing (the wet processing) such as development and fixation, has been proposed. This heat developing apparatus carries out developing processing by superposing a photosensitive material, on which an image has been exposed, and an image receiving material one on top of the other, heating them for a certain period of time, and then peeling the photosensitive material from the image receiving material, and drying them (i.e., so-called dry processing is carried out). 
     As shown in FIG. 8, a photosensitive material  126 , on which an image has been exposed by an exposure device  102  provided adjacent to a heat developing apparatus  100 , is inserted into the heat developing apparatus  100  from an insertion opening  104 , and is conveyed by plural transport rollers  106 . A water application section  108  and a heat developing section  110  are provided along the direction the photosensitive material  126  is conveyed. At the water application section  108 , water is applied onto the photosensitive material  126 , so that the adhesion between the photosensitive material  126  and a processing sheet (i.e., the above-described image receiving material)  112  can be improved. A heating drum  114  is provided in the heat developing section  110 . A heater  116 , which is contained inside the heating drum  114 , raises the temperature of the rotating heating drum, and the photosensitive material  126  and the processing sheet  112  conveyed along the outer peripheral surface of the heating drum  114  are heated for a predetermined period of time (i.e., heat developing processing is carried out). At this time, the photosensitive material  126  and the processing sheet  112 , which have been superposed one on top of the other, are conveyed in a state in which they are attached by pressure. After completion of heat developing processing, the photosensitive material  126  is peeled from the processing sheet  112 , and is dried by plural fans  118 . 
     Moreover, as shown in FIG. 9, a heat developing section  110 A may be structured such that plural heating plates  120 A to  120 E are provided in a circular arc configuration in order to restrict the height of a heat developing apparatus  100 A. A flat heater (not shown) and a flat temperature sensor (also not shown) are built into the heating plates  120 A to  120 E, and the heating plates  120 A to  120 E are heated so as to be a suitable temperature for heat developing processing. That is, heat developing processing is carried out by conveying the photosensitive material  126  and the processing sheet  112 , which have been laminated together, along the circular arc configuration of the heating plates  120 A to  120 E through a belt  124 . 
     Therefore, since a liquid containing chemicals, such as a processing solvent, is not used, nuisances such as liquid storing, replenishment control, and apparatus cleaning can be avoided, and maintenance properties of the apparatus can be improved. 
     However, in the heat developing apparatus  100  shown in FIG. 8, heat developing processing is carried out by conveying the photosensitive material  126  and the processing sheet  112  along an outer peripheral surface of the heating drum  114  set in the heat developing section  110 , and by attaching the photosensitive material  126  and the processing sheet  112  onto the outer peripheral surface of the heating drum  114  from pressure by a pressing belt  122 . Moreover, in the heat developing apparatus  100 A shown in FIG. 9, heat developing processing is carried out by conveying the photosensitive material  126  and the processing sheet  112  along the circular arc configuration of the heating plates  120 A to  120 E through the belt  124 . That is, heat developing processing is carried out in a state in which the photosensitive material  126  and the processing sheet  112  laminated together are caused to contact with and to be attached by pressure to the heating drum  114  or the belt  124  wound around the heating plates  120 A to  120 E. 
     Accordingly, since a mechanism for causing the photosensitive material  126  and a processing sheet  112  to contact with and to be attached by pressure to the heating drum  114  or the belt  124  wound around the heating plates  120 A to  120 E is needed, there is a problem with this method in that the inner structure of the heat developing apparatus becomes complicated. 
     In the heat developing apparatus  100  shown in FIG. 8, the heater  116  is built in the heating drum  114 , and the photosensitive material  126  and the processing sheet  112  are heated via the heating drum  114 . Moreover, in the heat developing apparatus  100 A shown in FIG. 9, the flat heater is built into the heating plates  120 A to  120 E, and the photosensitive material  126  and the processing sheet  112  are heated by the heating plates  120 A to  120 E and by the belt  124  wound around the heating plates  120 A to  120 E. In this way, since the conventional heat developing apparatuses  100 ,  100 A are structured such that the photosensitive material  126  and the processing sheet  112  are heated indirectly, not only the photosensitive material  126  and the processing sheet  112 , but also the heating drum  114  and the heating plates  120 A to  120 E need to be heated, so that a heater of a large capacity must be built thereinto. Accordingly, there is another problem in that manufacturing costs of the heat developing apparatus increase. 
     Further, the heating drum  114  and the heating plates  120 A to  120 E are cooled gradually. Therefore, there is a problem in that when heat developing processing is carried out continuously on the photosensitive material  126 , the temperature of the heating drum  114  and the heating plates  120 A to  120 E is unstable, and it is difficult to adjust the temperature to a value suitable for heat developing processing. Moreover, there is another problem in that an uneven developing is caused by the shapes of the heating drum  114  and the heating plates  120 A to  120 E, so that an image cannot be formed accurately. 
     In contrast, there is a method for heating a photosensitive material without using the heating drum  114  and the heating plates  120 A to  120 E. In such a method, a heater is provided so as to face the photosensitive material conveyed linearly, so that the photosensitive material is heated by relative movement of the photosensitive material and the heater. 
     However, when this method is used, it takes considerable time to heat the photosensitive material. Moreover, when the heater is moved, the heater is cooled by the air flow generated around the heater, and the heating temperature of the photosensitive material becomes unstable, so that failures such as breaking of filaments or the like easily occur inside the heater. Furthermore, since a mechanism for moving the heater is needed, there is a problem in that the inner structure of the apparatus becomes complicated, and the apparatus itself becomes larger. 
     SUMMARY OF THE INVENTION 
     The present invention is provided so as to solve the aforementioned problems, and an object of the present invention is to provide a heating apparatus which carries out heat processing such as heat developing processing on sheet-form materials by effectively utilizing heat generated by heating means. 
     In order to achieve the aforementioned object, a heating apparatus of the present invention, which forms an image by heating a sheet-form material carrying image data thereon, comprises a pair of winding means disposed at positions corresponding to both transverse direction ends of the sheet-form material, one of the pair being fixed and the other being movable along the transverse direction of the sheet-form material, and heating means disposed at an axial center portion of the sheet-form material wound around along the winding means, the heating means directly heating the sheet-form material so that the temperature becomes a value suitable for heat developing processing for example, in the range of from 80° C. to 250° C. preferably from 100° C. to 140° C. 
     In a first aspect of the present invention, the pair of winding means is provided at the positions corresponding to at least the both transverse direction ends of the sheet-form material such that when the sheet-form material is wound around along the winding means, the sheet-form material is curved in a circular arc shape. The winding means is formed, for example, in a ring shape which corresponds with an area of the sheet-form material where no image data is carrieed thereon, and the inner circumferential surface of the sheet-form material is open at least in an area where image data is carried thereon. 
     Moreover, the heating means for heating the sheet-form material so that the temperature becomes the value suitable for heat developing processing is provided at an axial center portion of the curved sheet-form material. In a case, for example, in which the winding means formed in a ring shape is provided as described above, the heating means is provided at the center position of the winding means. The heating means is provided along the transverse direction of the sheet-form material, and the inner circumferential surface of the sheet-form material is open, thereby allowing the sheet-form material to be heated directly. 
     In this way, since the sheet-form material is directly heated by the heat generated by the heating means, there is no need for a large-capacity heater for carrying out heat developing processing on the sheet-form material, and no need for a heating drum or a heating plate. Accordingly, heat processing can be carried out on the sheet-form material by effectively utilizing the heat generated by the heating means. Moreover, the inner structure of the heating apparatus can be simplified, and manufacturing costs of the heating apparatus can be reduced. Further, since there is no need for a heating drum or a heating plate, the temperature can easily be adjusted during heat developing processing, and heat processing can be carried out without causing uneven developing. 
     The winding means of the present invention may be a type which contacts an internal surface side of the two transverse direction ends of the sheet-form material curved in a circular arc shape, or one which contacts an outer peripheral surface of the sheet-form material curved in a circular arc shape. 
     That is, as the winding means, substantially ring-shaped members can be provided at positions facing the both transverse direction ends of the sheet-form material, and the ring-shaped members can be either the type where the sheet-form material is wound around an outer peripheral surface thereof, or the type where the sheet-form material is curved along an inner circumferential surface thereof. 
     In a case in which the pair of winding means is provided facing the two transverse direction ends of the sheet-form material, at least one of the pair of winding means may be movable along the transverse direction of the sheet-form material. 
     For example, one of the pair of winding means is fixed at a position corresponding to a transverse direction end of the sheet-form material, and the other one of the pair of winding means is movable along the transverse direction of the sheet-form material in correspondence with the width dimension of the sheet-form material. In this way, heat processing of a plurality of sheet-form materials with various width dimensions can be carried out. 
     Moreover, one of the winding means, which is used commonly by the plurality of sheet-form materials with various width dimensions, may be provided at a transverse direction end of the sheet-form material, and the winding means may be provided at each position corresponding with each of the other transverse direction ends of the sheet-form materials with various width dimensions. That is, at least three of the winding means are provided, at positions corresponding with the two transverse direction ends of each of the plurality of the sheet-form materials with various width dimensions, thereby making possible elimination of the trouble of moving the winding means in accordance with the width dimension of the sheet-form material to be heated. In this case, it is preferable that the winding means is formed with a material such as a heat-resisting glass which transmits the heat emitted from the heating means. 
     When such winding means is used, reflecting means for reflecting heat emitted by the heating means toward the sheet-form material, which has been curved in a circular arc shape by being wound around along the winding means, may be provided. 
     An aluminum plate, for example, or the like is provided as the reflecting means, and is provided along the outer peripheral surface of the sheet-form material wound around along the winding means. In this way, the heat emitted from the heating means and transmitted through the sheet-form material is effectively reused to heat the sheet-form material. Accordingly, the thermal efficiency of the heat emitted from the heating means while heating the sheet-form material can be improved. 
     Moreover, the winding means of the present invention may comprise a cylindrical member, and the sheet-form material may be curved along an inner circumferential surface of the cylindrical member. 
     That is, the sheet-form material is curved in a circular arc shape by being disposed along the inner circumferential surface of the cylindrical member. This allows the winding means to work as the above-described reflecting means, so that the thermal efficiency while heating the sheet-form material can be improved. 
     In this way, since heat processing can be carried out by curving, with the winding means, the sheet-form material in a circular arc shape in a state in which the inner circumferential surface thereof is open, the sheet-form material can directly be heated by the heat emitted from the heating means. Accordingly, when heat developing processing, for example, and the like is carried out on the sheet-form material, there is no need for heating means with a large capacity, and no need for a heating drum or heating plate. Therefore, the inner structure of the heat developing apparatus can be simplified, and manufacturing costs of the heat developing apparatus can be reduced. Further, since there is no need for the heating drum or the heating plate, the temperature can easily be adjusted during heat developing processing, and heat developing processing can be carried out without causing uneven developing. In accordance with the above, heat developing processing on the sheet-form material can be carried out by effectively utilizing the heat emitted from the heating means. 
     It is preferable that the present invention further comprises a heat adjusting means, which is provided so as to cover an outer peripheral surface of the heating means, for adjusting a heating state of the sheet-form material by the heating means. 
     In accordance with the present invention, the heat adjusting means is provided between the sheet-form material wound around along the winding means and the heating means. When the heat emitted from the heating means is not uniform, the heat adjusting means adjusts the heat so that the sheet-form material is heated uniformly. 
     In this way, the sheet-form material can be heated uniformly by the heat emitted from the heating means, so that when heat developing processing, for example, is carried out, the material can be heated uniformly, thereby preventing uneven developing, which is due to unevenness in the heating temperature and the like, from being caused. 
     As such, heat adjusting means, which comprises a substantially cylindrical heat insulating member, in which a slit-form opening portion with a certain width is formed along the transverse direction of the sheet-form material, may be used. 
     In a case in which the state of heat distribution of the heat emitted from the heating means is uneven, the state of heat distribution during the heating process of the sheet-form material can easily be made uniform by adjusting the width of the slit-form opening portion on the heat insulating member in accordance with the state of heat distribution of the heating means. Moreover, because of the width adjustment of the slit-form opening portion on the heat insulating member, the heating time for the sheet-form material, by which the sheet-form material becomes a predetermined heated state, is also adjustable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a structural view showing a schematic structure of a heat developing apparatus of the present invention. 
     FIG. 2A is a first structural view showing a detailed structure of a heat developing section according to a first embodiment of the present invention, and is a perspective view of the heat developing section in particular. 
     FIG. 2B is a second structural view showing a detailed structure of the heat developing section according to the first embodiment of the present invention, and shows a cross sectional view of FIG. 2A along the line  2 B— 2 B. 
     FIG. 3A is a diagram showing a heating portion of a heater and a schema of the heating temperature dependent on the heating portion of the heater. 
     FIG. 3B is a diagram showing a movable shutter forming an opening corresponding with the heating temperature of the heater and a schema of the heating temperature dependent on the heater accommodated in the movable shutter. 
     FIG. 4A is a first structural view showing a detailed structure of a heat developing section according to another embodiment of the present invention, and is a perspective view of main portions of the heat developing section. 
     FIG. 4B is a second structural view showing a detailed structure of the heat developing section according the other embodiment of the present invention, and shows a cross-sectional view of FIG. 4A along the line  4 B— 4 B. 
     FIG. 5 is a schematic structural view showing a schematic structure of a heat developing section according to still another embodiment of the present invention. 
     FIG. 6A is a first structural view showing a detailed structure of a heat developing section according to a second embodiment of the present invention, and is a perspective view of the heat developing section. 
     FIG. 6B is a second structural view showing a detailed structure of the heat developing section according to the second embodiment of the present invention, and shows a cross-sectional view of FIG. 6A along the line  6 B— 6 B. 
     FIG. 7 is a perspective view of main portions, showing another example of the heat developing section according to the second embodiment of the present invention. 
     FIG. 8 is an inner structural view showing a heat developing apparatus of the prior art in which a heating drum is provided. 
     FIG. 9 is an inner block diagram showing a heat developing apparatus of the prior art in which a plurality of heating plates are provided. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
     In FIG. 1, a schematic inner structure of a heat developing apparatus  12 , to which the present invention is applied, is illustrated. The heat developing apparatus  12  comprises a face section  26 , a heat developing unit  28 , a photosensitive material take-up section  30 , and an image receiving paper loading section  32 . A color measurement sensor  34 , a temperature-humidity sensor  36 , and the like are also provided as the need arises. 
     In the heat developing apparatus  12 , an image exposure device (not shown) is provided in the vicinity of the side of the face section  26 . The image exposure device exposes an image on a photosensitive material  16  used as one of sheet-form materials, and conveys it into the heat developing apparatus  12 . The heat developing apparatus  12  may be structured integrally with the image exposure device to form an image forming device. 
     The photosensitive material  16  can either be an elongated sheet wound up in a roll form, or a sheet cut into a certain length. That is, the photosensitive material  16  can either be a roll or a sheet of photosensitive material as long as it has a sheet form. Below, an explanation will be given that assumes that the roll of elongated photosensitive material is used as the photosensitive material  16 . 
     For example, silver salt sensitive materials sensitive to light in a visible range, PS plates (planograpnic printing plates) sensitive to UV (ultraviolet) light, B (blue) light, and G (green) light, thermosensible materials sensitive to near infrared light, and the like can be used as the photosensitive material  16 . 
     In the image exposure device (not shown), a light beam is used to scan and expose the photosensitive material  16 , based on image data. At this time, in the image exposure device, the image data is calibrated based on temperature and humidity within the image processing device  12  detected by the temperature-humidity sensor  36  provided in the heat developing apparatus  12 , and on color of the image recorded on the photosensitive material  16 , on which heat developing processing has been carried out, detected by the color measurement sensor  34 . The photosensitive material  16  is then scanned and exposed based on the corrected image data. 
     The photosensitive material  16  is fed into the face section  26  of the heat developing apparatus  12 . A diverging guide (not shown) which is operated by a solenoid is provided in the face section  26 . The diverging guide can be switched between a horizontal state and a vertical state. When the diverging guide is switched to the vertical state, the photosensitive material  16  falls slack and sags between transport rollers  42  as indicated by an imaginary line in FIG.  1 . In this way, a difference in speed between the processing rate of the heat developing apparatus  12  and that of the image exposure device may be adjusted. Moreover, the driving of the transport rollers  42  is controlled by a control unit  94  provided in the lower portion of the heat developing apparatus  12 . 
     The image receiving paper loading section  32  is provided below the face section  26 . An image receiving paper  40  wound around a paper winding shaft  44  is loaded into the image receiving paper loading section  32  and is conveyed therefrom by the transport rollers  42  in a predetermined direction. 
     The heat developing unit  28  is provided at the downstream side in the direction the photosensitive material  16  is conveyed. A water application tank  80  filled with water, which is used as an image forming solvent for the photosensitive material  16 , is provided in the heat developing unit  28 . The water application tank  80  is structured such that water is supplied via a pump (not shown) from a water tank  82  provided in a lower portion of the heat developing apparatus  12 . Application of water onto the photosensitive material  16  improves the adhesion between the image receiving paper  40  and the photosensitive material  16  when they are superposed one on top of the other. 
     A heat developing section  46  is provided in the heat developing unit  28  to carry out heat developing processing. The heat developing section  46  comprises a pair of winding rings  48  to wind the photosensitive material  16  and the image receiving paper  40 , a heater  50  for heating the photosensitive material  16  and the image receiving paper  40 , and a movable shutter  52  to adjust the heating condition of the photosensitive material  16  and the image receiving paper  40 , which are heated by heat generated by the heater  50 . Referring now to FIGS. 2A and 2B, a detailed structure of the heat developing section  46  will be described. 
     As shown in FIG. 2A, the winding rings  48  comprise a fixed ring  48 A, which is fixed by fixing means (not shown), and a movable ring  48 B, which can be slid along the transverse direction of the photosensitive material  16  and the image receiving paper  40  (the direction indicated by arrow A or B in FIG.  2 A). That is, the movable ring  48 B is to be slid according to the width dimension of the photosensitive material  16  and the image receiving paper  40 , which are to be wound around the winding rings  48 . 
     A stopper portion  49 A and a winding portion  49 B are formed on each of the winding rings  48 . An outer diameter of the stopper portion  49 A is formed larger than an outer diameter of the winding portion  49 B so that both edges of the photosensitive material  16  and the image receiving paper  40  wound around the winding portion  49 B of the winding rings  48  are held in position by the stopper portion  49 A. In this way, misalignment of the photosensitive material  16  and the image receiving paper  40  in the transverse direction during their conveyance is prevented. 
     The cylindrical heater  50  is provided at a center position of the winding rings  48 . The heater  50  is provided along the transverse direction of the photosensitive material  16  and the image receiving paper  40 , and can heat the photosensitive material  16  and the image receiving paper  40  to a proper temperature for the processing during heat developing processing. In the present embodiment, a far infrared radiation heater emitting a far infrared light is used for the heater  50 . 
     The movable shutter  52 , in which an opening portion  52 A is formed along the transverse direction of the photosensitive material  16  and the image receiving paper  40 , is provided in the outer periphery of the heater  50  so as to cover the outer peripheral surface of the heater  50 . The movable shutter  52 , for example, is formed by rolling up a strip-shaped flat plate made of a heat insulating material into a circular shape so that a gap (referred to as “opening portion  52 A” hereafter) of a certain width is formed between one end and the other end of the flat plate. By providing the movable shutter  52  in the outer periphery of the heater  50 , the heat (far infrared radiation) generated by the heater  50  is emitted only from the opening portion  52 A formed on the movable shutter  52 , and directly irradiates and heats the photosensitive material  16  and the image receiving paper  40 . 
     Moreover, the movable shutter  52  is provided so that the shutter  52  can rotate in the directions of arrow C shown in FIGS.  2 A and  2 B. The heating state of the photosensitive material  16  and the image receiving paper  40  by the heat generated by the heater  50  is adjusted by the width of the opening of the opening portion  52 A and by the rotating speed of the movable shutter  52 . For example, the heating time of the photosensitive material  16  and the image receiving paper  40  can be adjusted by controlling the rotating speed and the like of the movable shutter  52 . 
     A photosensitive material peeling member  88  which peels apart the photosensitive material  16  and the image receiving paper  40  which were laminated together, and an image receiving paper peeling member  90  which peels the image receiving paper  40  from the winding rings  48  are provided at the downstream side of the heat developing section  46  in the direction the photosensitive material  16  and the image receiving paper  40  are conveyed, as shown in FIG.  1 . 
     The photosensitive material  16  peeled from the image receiving paper  40  by the photosensitive material peeling member  88  is wound around a winding shaft  92 , which is provided in the photosensitive material winding section  30 , and is then disposed of as waste. Further, the color measurement sensor  34  is provided at the downstream side in the direction to which the image receiving paper  40 , which has been peeled from the winding rings  48  by the image receiving paper peeling member  90  and on which an image has been formed, is conveyed. The color measurement sensor  34  measures the color of the image which has been formed on the image receiving paper  40 , then outputs to an image exposure device (not shown) the correction data having been provided from a correction data forming device (not shown) to which the measured data is input. The image receiving paper  40 , which has been subjected to color detection by the color measurement sensor  34 , is then discharged from the heat developing apparatus  12  to the outside of the apparatus  12 . 
     Operation of the first embodiment of the present invention will be described hereinafter. 
     The image exposure device (not shown) scans and exposes the photosensitive material  16  with the light beam, on the basis of the image data. The photosensitive material  16  already scanned and exposed is then conveyed to the heat developing apparatus  12 . The photosensitive material  16  is fed from the face section  26  into the heat developing apparatus  12  and soaked in water in the water application tank  80  provided in the heat developing unit  28  for water application. Subsequently, in the heat developing apparatus  12 , the photosensitive material  16  is conveyed to the heat developing section  46 . 
     In the heat developing apparatus  12 , synchronizing with the conveyance of the photosensitive material  16 , the image receiving paper  40  is drawn out from the image receiving paper loading section  32  and conveyed to the heat developing section  46  in the heat developing unit  28 . In this way, the photosensitive material  16  and the image receiving paper  40  are superposed one on top of the other, and heat developing processing is carried out in the heat developing section  46 . 
     The winding rings  48  comprising the fixed ring  48 A and the movable ring  48 B are provided in the heat developing section  46 , and the two transverse direction ends of the photosensitive material  16  and the image receiving paper  40  are wound around the fixed ring  48 A and the movable ring  48 B, respectively. Moreover, when it is sensed that the photosensitive material  16  and the image receiving paper  40  have touched the winding rings  48 , for example, the control unit  94  instructs the motion of the movable ring  48 B, and the movable ring  48 B is moved by moving means (not shown) in correspondence with the width dimension of the photosensitive material  16  and the image receiving paper  40 . In this way, the photosensitive material  16  and the image receiving paper  40  wound around the winding rings  48  are prevented from being misaligned in the transverse direction when they are conveyed. 
     Further, only the two transverse direction ends of the photosensitive material  16  and the image receiving paper  40  are wound around the winding rings  48 . Heat developing processing is carried out on the photosensitive material  16  and the image receiving paper  40  by the heater  50  in a state in which the photosensitive material  16  and the image receiving paper  40  are wound around the winding rings  48 . While heat developing processing is carried out, the heating time for the photosensitive material  16  and the image receiving paper  40  is adjusted by rotating the movable shutter  52  provided near the outer periphery of the heater  50  at a predetermined speed. Moreover, since heat developing processing is carried out on the photosensitive material  16  and the image receiving paper  40  in such a manner that only the two transverse direction ends thereof are wound around the winding rings  48 , the photosensitive material  16  and the image receiving paper  40  can be heated directly by the heat generated by the heater  50  via the opening portion  52 A formed in the movable shutter  52 . 
     In this way, the photosensitive material  16  and the image receiving paper  40  are heated to form an image on the image receiving paper  40 . The photosensitive material  16 , on which heat developing processing has been carried out, is wound around the photosensitive material take-up section  30 , and is then disposed of as waste. On the other hand, the image receiving paper  40  on which an image has been formed is discharged from the heat developing apparatus  12  and conveyed to devices of subsequent processes such as a printing processing device. 
     Since heat developing processing is carried out in such a manner that only the two transverse direction ends of the photosensitive material  16  and the image receiving paper  40  are wound around the winding rings  48 , the photosensitive material  16  and the image receiving paper  40  can be heated directly by the heat generated by the heater  50  in the heat developing section  46 . Accordingly, since there is no need for a large-capacity heater, manufacturing costs of the heat developing apparatus can be reduced, and heat developing processing can be carried out by effectively utilizing the heat generated by the heater  50 . Moreover, since heat developing processing is carried out in such a manner that only the two transverse direction ends of the photosensitive material  16  and the image receiving paper  40  are wound around the winding rings  48 , there is no need for a mechanism for causing the photosensitive material and the image receiving paper to contact with, or to be attached by pressure to a heating drum and a heating plate, so that the structure of the heat developing apparatus can be simplified. Further, since there is no need for a heating drum or a heating plate, the temperature can easily be adjusted to a value suitable for heat developing processing, and a stable heat developing processing can be realized without causing an uneven developing and the like. 
     Although the present embodiment describes a case in which the opening portion  52 A is formed along the transverse direction of the photosensitive material  16  and the image receiving paper  40  in the movable shutter  52  provided near the outer periphery of the heater  50 , the form of the opening portion  52 A is not limited to the same. For example, in a case in which the state of heat distribution is not uniform, a movable shutter can be provided, wherein the movable shutter is capable of adjusting the heat generated by the heater such that the state of heat distribution becomes uniform by forming the opening portion into a shape corresponding with the state of heat distribution, or by providing a shielding plate. 
     That is, a heating portion  50 A of the cylindrical heater  50  emits substantially uniform heat in the center portion along the longitudinal direction, while the heating value lowers at the two longitudinal direction end portions. Therefore, as shown in FIG. 3A, when the length of the heating portion  50 A coincides with the heating area, the heating temperature lowers at the two ends of the heating area which face the two transverse direction end portions of the heating portion  50 A. Accordingly, when the longitudinal direction of the heating portion  50 A of the heater  50  is disposed along the transverse direction of the photosensitive material  16  and the image receiving paper  40 , and the heater  50  heats the photosensitive material  16  and the image receiving paper  40 , the heating temperature at the two transverse direction ends of the photosensitive material  16  and the image receiving paper  40  is lower than that of the central portion thereof. 
     In order to prevent the heating temperature from lowering in the areas facing the two end portions of the heating portion  50 A of the heater  50  of the above description, the heater  50  which has the heating portion  50 A longer than the width dimension of the photosensitive material  16  and the image receiving paper  40  must be used, and the photosensitive material  16  and the image receiving paper  40  must be heated in an area where the heating value is uniform. Accordingly, the apparatus becomes larger, and the thermal efficiency lowers. 
     In contrast, as shown in FIG. 3B, the opening portion  52 A of the movable shutter  52  is modified in accordance with the quantity of heat emitted from the heater  50 . That is, the width of the opening at the two end portions of the heating portion  50 A, where the quantity of heat is low, is made wider than that in the middle portion along the longitudinal direction in accordance with the heating temperature change. 
     In this way, the heating temperature by the middle portion of the heating portion  50 A and by the two end portions thereof can be made substantially the same, and the heating temperature of the photosensitive material  16  and the image receiving paper  40  can be made substantially uniform even if the length of the heating portion  50 A of the heater  50  is substantially the same with the transverse length of the photosensitive material  16  and the image receiving paper  40 . Therefore, the uniform heating of the photosensitive material  16  and the image receiving paper  40  along the transverse direction can securely prevent uneven developing from being caused, and form a finished image of high quality on the image receiving paper  40 . 
     Although the present embodiment describes a case in which a far infrared radiation heater is used as the heater, the present invention is not limited to the same, and any heater which is capable of heating the photosensitive material and the image receiving paper can be used. However, when silver salt photosensitive materials sensitive to light in a visible range, PS plates sensitive to UV (ultraviolet) light, B (blue) light, and G (green) light, photo-thermosensitive materials sensitive to a near infrared light, and the like are used as the photosensitive material, it is preferable that a far infrared radiation heater is used. 
     Moreover, as shown in FIGS. 4A and 4B, a circular arc-shaped reflector  54  can be provided along the outer peripheral surface of the photosensitive material  16  and the image receiving paper  40  wound around the winding rings  48 . In this way, the heat, which has been emitted from the heater  50  via the opening portion  52 A of the movable shutter  52  and has transmitted thorugh the photosensitive material  16  and the image receiving paper  40 , is reflected by the reflector  54  to be reused for heat developing processing. Accordingly, heat developing processing on the photosensitive material  16  and the image receiving paper  40  can be carried out while effectively utilizing the heat generated by the heater  50 . 
     Further, although the winding rings  48  according to the present embodiment comprises the fixed ring  48 A and the movable ring  48 B, and can be adjusted such that the space therebetween corresponds with the width dimension of the photosensitive material  16  and the image receiving paper  40  by moving the movable ring  48 B, the present invention is not limited to the same. For example, as shown in FIG. 5, a winding ring  51 A, which is used commonly by all photosensitive materials and image receiving papers with plural and different width dimensions, can be disposed in a position which corresponds with one transverse direction end of the photosensitive material and the image receiving paper, and winding rings  51 B and  51 C can be provided respectively in a position which corresponds with each of the other transverse direction ends of the photosensitive material and the image receiving paper with different width dimensions. 
     That is, it can be structured such that the winding rings corresponding with the width dimension of the photosensitive material  16  and the image receiving paper  40  are selected, and the photosensitive material  16  and the image receiving paper  40  are wound around the appropriate winding rings. In this case, it is preferable that each of the winding rings  51 A,  51 B,  51 C is formed as a winding ring with a uniform outer diameter unlike the winding ring  48  according to the present embodiment, which has the winding portion  49 A and the stopper portion  49 B being formed thereon. It is also preferable that the winding rings  51 A,  51 B,  51 C are formed with a material such as heat-resisting glass which transmits far infrared radiation emitted from the heater  50 . 
     Second Embodiment 
     A second embodiment of the present invention will be described hereinafter. Since the basic structure of the second embodiment is the same as that of the above-described first embodiment, the same reference numerals are used to designate elements which are the same as those of the first embodiment and detailed description thereof will be omitted. 
     FIGS. 6A and 6B illustrate a schematic structure of a heat developing section  150  according to the second embodiment. The heat developing section  150  may be used, for example, in place of the heat developing section  46  of the above-described first embodiment. 
     The heat developing section  150  comprises a cylindrical winding member  152 . The inside of the winding member  152  is hollow. 
     The heater  50  is provided at an axial portion of the winding member  152  such that the axial direction thereof is parallel to the longitudinal direction of the winding member  152 . Moreover, the periphery of the heater  50  is surrounded by the movable shutter  52 , and the heat generated by the heater  50  is radiated from the opening portion  52 A of the movable shutter  52 . 
     A slit-shaped insertion opening  154  and a slit-shaped outlet opening  156  are formed adjacent to each other along the axial direction of the winding member  152  at an outer peripheral portion thereof such that the respective longitudinal directions are parallel to each other. The length of the insertion opening  154  and the outlet opening  156  corresponds with the width dimension of the photosensitive material  16  and the image receiving paper  40  which are to be processed in the heat developing section  150 , so that the photosensitive material  16  and the image receiving paper  40  can be inserted from the insertion opening  154  in a state in which they are superposed one on top of the other, and the photosensitive material  16  and the image receiving paper  40  inserted in the winding member  152  can be drawn out from the outlet opening  156 . 
     In the heat developing section  150 , an insertion guide  158  is provided so as to face the insertion opening  154  of the winding member  152 , and an outlet guide  160  is provided so as to face the outlet opening  156  as shown in FIG.  6 B. The insertion guide  158  and the outlet guide  160  are formed such that the sectional form along the direction the photosensitive material  16  is conveyed is a substantially circular arc, and the tip portions thereof respectively face the insertion opening  154  and the outlet opening  156 . 
     Moreover, as shown in FIG.  6 A and FIG. 6B, stopper portions  162  are formed at the two axial direction ends of the winding member  152 , and the stopper portions  162  prevent the photosensitive material  16  and the image receiving paper  40  from being misaligned in the transverse direction. 
     Leading edges of the photosensitive material  16  and the image receiving paper  40  conveyed to the heat developing section  150  are guided to the insertion opening  154  of the winding member  152  by the insertion guide  158  in a state in which the photosensitive material  16  and the image receiving paper  40  are superposed one on top of the other, and are inserted from the insertion opening  154  into the winding member  152 . Being further conveyed into the winding member  152 , the photosensitive material  16  and the image receiving paper  40 , whose leading edges have been inserted into the insertion opening  154 , are moved along the curved inner circumferential surface of the winding member  152  toward the outlet opening  156  in a state in which the photosensitive material  16  and the image receiving paper  40  are superposed one on top of the other. 
     In this way, the photosensitive material  16  and the image receiving paper  40  are wound around along the inner circumferential surface of the winding member  152  in a state in which they are curved in a circular arc shape. At this time, due to tenacity/toughness of the photosensitive material  16  and the image receiving paper  40 , the photosensitive material  16  and the image receiving paper  40  closely contact each other and also with the inner circumferential surface of the winding member  152 . 
     Moreover, in the heat developing section  150 , when heat developing processing is completed in the winding member  152 , the photosensitive material  16  and the image receiving paper  40  are drawn out from the winding member  152 . At this time, the photosensitive material  16  and the image receiving paper  40  are further conveyed, for example, from the insertion opening  154  side into the winding member  152 . Accordingly, the leading edges of the photosensitive material  16  and the image receiving paper  40  in the winding member  152  protrude from the outlet opening  156 , and are guided toward the discharging direction by the outlet guide  160 . Subsequently, the photosensitive material  16  and the image receiving paper  40  in the winding member  152  are conveyed through the outlet opening  156 , and the image receiving paper  40  is peeled from the photosensitive material  16  by peeling means (not shown) and discharged. 
     In the heat developing section  150  structured in this way, heat developing processing is carried out by heating the photosensitive material  16  and the image receiving paper  40  by the heater  50  in a state in which the photosensitive material  16  and the image receiving paper  40  are wound around along the inner circumferential surface of the winding member  152 . 
     At this time, since the heater  50  is contained inside the cylindrically formed winding member  152 , this structure can prevent the temperature from being changed under the influence of outside air, and can heat each of the photosensitive material  16  and the image receiving paper  40  uniformly. Moreover, since the winding member  152  also works as a reflector due to being formed cylindrically, the thermal efficiency of the heater  50  while heating the photosensitive material  16  and the image receiving paper  40  can be improved. When the air inside the winding section  152  must be discharged or ventilation inside the winding section  152  is necessary, ventilating holes may be provided at the two axial direction ends, or ventilating means may be provided. 
     In this way, in the heat developing section  150 , a simple structure utilizing the winding member  152  of a substantially cylindrical form as winding means can heat the photosensitive material  16  and the image receiving paper  40  efficiently to carry out developing processing. 
     Although the second embodiment of the present invention describes a case in which the winding member  152  of a substantially cylindrical form is used as the winding means, and the photosensitive material  16  and the image receiving paper  40  are curved in a circular arc shape by being positioned along the inner circumferential surface of the winding member  152 , any mechanism which causes the photosensitive material  16  and the image receiving paper  40  to be curved in a circular arc shape by contacting at least the two transverse direction ends of the photosensitive material  16  and the image receiving paper  40  can be used as the winding means. 
     Winding rings  170  shown in FIG. 7, for example, can be used as such winding means. The winding ring  170  comprises a stopper portion  172  and a winding portion  174 , and the winding rings  170  are provided at the two transverse direction ends of the photosensitive material  16  and the image receiving paper  40  so as to oppose each other. 
     In the winding ring  170 , a slit  176  used for inserting the photosensitive material  16  and the image receiving paper  40  into the winding portion  174 , and a slit  178  used for discharging the same from the winding portion  174  are formed. Moreover, an inner diameter of the stopper portion  172  is formed smaller than an inner diameter of the winding portion  174 , so that when the photosensitive material  16  and the image receiving paper  40  are set inside the winding portions  174 , movement in the transverse direction is restrained. 
     When the leading edges of the photosensitive material  16  and the image receiving paper  40  are inserted from the slits  176 , the winding rings  170  guide the photosensitive material  16  and the image receiving paper  40  along the inner circumferential surface of the winding portions  174 . In this way, the photosensitive material  16  and the image receiving paper  40  are curved in a circular arc shape while the two transverse direction ends thereof are within the winding portions  174 . 
     When the two transverse direction ends of the photosensitive material  16  and the image receiving paper  40  are curved, the center portion thereof is curved accordingly, so that the portion of the photosensitive material  16  and the image receiving paper  40  between the two winding rings  170  becomes substantially cylindrical. In this way, the photosensitive material  16  and the image receiving paper  40  can be heated uniformly by the heater  50  disposed at an axial portion of the winding rings  170 . 
     Even in a case in which the winding rings  170  described above are used, heat developing processing of the photosensitive material  16  and the image receiving paper  40  of various sizes becomes possible by fixing one of the winding rings  170  and by moving the other movable winding ring  170  along the axial direction (the direction indicated by arrow A and arrow B) in accordance with the width dimension of the photosensitive material  16  and the image receiving paper  40 . 
     Moreover, processing of the photosensitive material  16  and the image receiving paper  40  of various types with different width dimensions becomes possible by disposing a plurality of winding rings (not shown), which are each structured only with the winding portion  174 , without the stopper portion  172 , and by moving the winding rings. Furthermore, the reflector  54  may be disposed so as to cover the photosensitive material  16  and the image receiving paper  40 , which have been curved in a substantially circular arc shape between the winding rings  170 . 
     Although in the above-described first and second embodiments of the present invention, the photosensitive material  16  and the image receiving paper  40  of the elongated type are used as sheet-form materials, the present invention is not limited to the same, and the photosensitive material  16  and the image receiving paper  40  may be a cut sheet which has been cut into a certain length. Moreover, the heating apparatus of the present invention is not limited to use for heating the photosensitive material  16  and the image receiving paper  40 , and can be applied to heating apparatuses which heat other photosensitive materials. Furthermore, the present invention can be used in heating apparatuses which heat various sheet-form materials not limited to photosensitive materials. 
     In accordance with the present invention described above, since heat developing processing is carried out by heating means by directly heating a sheet-form material wound around along winding means, which is provided at positions corresponding with the two transverse direction ends of a sheet-form material, it has an advantage such that heat developing processing can be carried out on the sheet-form material by effectively utilizing the heat generated by the heating means.