JP3655343B2 - Photo film, photo film cartridge, and method for manufacturing a lens-fitted photo film unit - Google Patents

Description

[0001]
[Industrial application fields]
More particularly, the present invention relates to a photographic film provided with a magnetic recording layer, a photographic film cartridge incorporating the photographic film, and a photographic film cartridge. The present invention relates to a method of manufacturing a loaded lens-fitted photo film unit.
[0002]
[Prior art]
A film unit with a lens is provided by the present applicant so that the user can easily take a picture without having a normal camera. Such a lens-fitted photo film unit is a unit that has an inexpensive photographic lens and an exposure imparting mechanism, and a photographic film with a patrone built in advance, so that an exposed photographic film is wound around the patrone every time a picture is taken. Therefore, after filming is complete, it can be submitted to the laboratory as it is, and troublesome film rewinding is unnecessary.
[0003]
Conventionally, a photographic film provided with a magnetic recording layer has been proposed (WO90 / 0425 (PCT / US89 / 04366)). In such a photographic film, various photographing information is recorded by cameras proposed in Japanese Patent Laid-Open Nos. 51-117632, 52-1333, 63-298233, and the like. These pieces of information are used for correction of exposure values at the time of printing, trimming, and the like so that a high-quality printed photograph that fully exhibits the functions of the camera and the performance of the photographic film can be obtained. Also, at the development laboratory, the data when printing, the format of the screen size, the number of prints, the print size, etc. are recorded on the magnetic recording layer of the photographic film, and the work when using the developed photographic film To improve efficiency.
[0004]
[Problems to be solved by the invention]
As described above, when magnetic information recording is performed consistently from photographing to development using a photographic film as a medium, a photographic film provided with a magnetic recording layer in a film unit with a lens must be used. Therefore, when such a photographic film is built in a lens-fitted photo film unit, there is a risk of causing trouble at a developing laboratory. Therefore, an erroneous signal such as noise is caused in the magnetic recording layer by a component mounting process or a photographic film loading process. It is necessary not to be recorded by etc.
[0005]
The present invention has been made in view of the above circumstances, and provides a photographic film, a photographic film cartridge, and a method of manufacturing a lens-fitted photo film unit that are improved in quality so that an erroneous signal such as noise is not recorded on a magnetic recording layer. For the purpose.
[0006]
[Means for Solving the Problems]
  In order to achieve the above object, in the method for producing a photographic film of the present invention, a photosensitive layer is coated on one surface of a long transparent support, and a transparent magnetic recording layer is coated on the entire other surface. A photo film manufacturing process for creating a strip-shaped photo film, and the photo film provided with the magnetic recording layer is cut in a predetermined length with a standard length / cutting means while being transported in one direction in a dark room. The photographic film strip is sent out by a standard length / cutting process, and an alternating magnetic field is formed by a magnetic field forming means in a coil arranged in a dark room, and the photographic film strip is passed through the coil at a constant speed. An erasing step of demagnetizing the magnetic recording layer by gradually converging the strength of the alternating magnetic field toward zero by separating the film strip from the coil. As a method for producing a photographic film cartridge, a strip-shaped photographic film is prepared by coating a photosensitive layer on one side of a long transparent support and a transparent magnetic recording layer on the entire other side. The photographic film manufacturing process to be performed, and the strip-shaped photographic film provided with the magnetic recording layer is cut in a certain length by a fixed length / cutting mechanism installed in a dark room while being transported in one direction, and then the photographic film is thinned. A standard length / cutting process for sending out a piece, and a photographic film strip fed from the standard length / cutting step is conveyed to a film winding unit, and the photographic film strip is wound around an empty cartridge by the film winding unit. A cartridge storing step for creating a cartridge, and a cartridge storing step that is arranged either before or after the cartridge storing step; The photographic film strip is passed through the coil disposed in the chamber or the photographic film cartridge is passed through the coil in which the alternating magnetic field is formed by the magnetic field forming means at a constant speed, and the alternating magnetic field strength is increased by moving away from the coil. And an erasing step of demagnetizing the magnetic recording layer by gradually converging toward zero.
[0007]
  Moreover, in the manufacturing method of the film unit with a lens,A photographic film manufacturing process for producing a strip-shaped photographic film by coating a photosensitive layer on one side of a long transparent support and a transparent magnetic recording layer on the entire other side, and the magnetic recording layer A standard length / cutting process in which the strip-shaped photographic film is cut in a certain length by a fixed length / cutting mechanism installed in a dark room while conveying the strip-shaped photographic film in one direction, and a cut piece of the photographic film after cutting is sent,SaidA patrone storage step for transporting the photographic film strip sent out from the standard length / cutting process to a film winding unit and winding the photographic film strip into an empty cartridge by the film winding unit to create a photographic film cartridge, and the cartridge A photo film cartridge obtained in the storing process is loaded into a unit body incorporating an exposure imparting mechanism to create a film unit with a lens, and an alternating magnetic field is formed in the coil by magnetic field forming means. The film unit with lens is passed through the coil at a constant speed, and the magnetic unit is demagnetized by gradually converging the strength of the alternating magnetic field toward zero by moving the film unit with lens away from the coil. And an erasing process to be performed. Also,As an erasing methodIsHow to give a magnetic field to an aggregate of several piecesLawis there. As a form at the time of erasure, any of a photographic film, a photographic film cartridge, and a film unit with a lens may be used. Further, a plurality of erasing steps may be arranged.
[0008]
As shown in FIG. 1, a film unit with a lens (hereinafter referred to as “film unit”) 10 includes an outer case 11 and a unit main body 12. The outer case 11 includes a photographing lens 13 and a shutter button. 14, an opening for exposing the winding knob 15, the finder 16, the number display window 17 and the like to the outside is formed. As the outer case 11, a paper box or a resin case is used.
[0009]
As shown in FIG. 2, the unit main body 12 includes a main body base 18, a rear cover 19, an exposure unit 20, and a front cover 21.
[0010]
An exposure unit 20 is detachably attached to the front surface of the main body base 18. The exposure unit 20 incorporates a photographing lens 13, a shutter mechanism, a film winding mechanism, a shutter charge mechanism, and the like, and these are unitized. The rear cover 19 is detachably attached to the back of the main body base 18 and stores the photographic film 22 with a cartridge in a light-tight manner between the rear cover 19 and the main body base 18.
[0011]
The front cover 21 is detachably attached to the front surface of the main body base 18 and sandwiches the exposure unit 20 with the main body base 18. On the upper surface of the front cover 21, there is provided a shutter button 14 that is formed by being cut out and elastically formed. The shutter mechanism of the exposure unit 20 is activated by pressing the shutter button 14.
[0012]
A cartridge storage chamber 25 for storing the cartridge 24 and a film roll chamber 27 for storing the unexposed photographic film 26 drawn out from the cartridge 24 in the form of a film roll 26a are integrally formed in the main body base 18. ing. The film roll 26 a is formed by winding around the outer periphery of the core 28, and is stored in the film roll chamber 27 while being wound around the core 28. The upper and lower ends of the core 28 are rotatably supported inside the film roll chamber 27 by fork members 29 and 30 provided on the rear cover 19. The core 28 may be omitted and only the film roll 26a may be stored. In this case, the fork member 29 can be omitted.
[0013]
The bottoms of the cartridge storage chamber 25 and the film roll chamber 27 are opened, and after being loaded with the photographic film 22 with a cartridge, they are closed by pull-top type bottom covers 31 and 32 provided on the rear cover 19, respectively. The bottom lid 31 serves as a lid when the cartridge 24 is taken out along the axial direction of the spool 35.
[0014]
The winding knob 15 is rotatably arranged on the upper surface of the cartridge storage chamber 25 and is engaged with a spool 35 of the cartridge 24 loaded in the cartridge storage chamber 25. A part of the winding knob 15 is exposed from the opening 36 of the rear cover 19, and the spool 35 is wound up by rotating the exposed part in the film winding direction (counterclockwise direction shown in the figure). The exposed photographic film 26 is wound in the cartridge 24 by rotating in the direction.
[0015]
A dark box 33 is provided between the cartridge storage chamber 25 and the film roll chamber 27. On the back side of the dark box 33, an exposure opening 37 (aperture) that is curved around the optical axis 13a of the photographing lens 13 is formed in order to correct the curvature of field of the photographing lens 13. An opening 34 is formed on the front side of the dark box 33. This opening 34 is for guiding the subject light transmitted through the photographing lens 13 to the exposure opening 37 when the exposure unit 20 is attached. Note that the dark box 33 may be provided in the exposure unit 20. Alternatively, the dark box 33 may be formed by dividing the dark box 33 and providing a part to the exposure unit 20, the other part to the main body base 18, and the exposure unit 20 to the main body base 18.
[0016]
As shown in FIG. 3, the photographic film 26 is locked to the spool 35, and as shown in FIG. 3, a film exposure part 26c used for photographing, a film leading end part 26b and a film trailing end part 26d that cannot be used for photographing, It is composed of In the film exposure section 26c, perforations 39 and 40 having different sizes along one side edge are alternately arranged at two intervals, and the perforations 39 and 40 arranged at short intervals are always arranged in pairs. The frame 38 is formed by performing exposure in a state where the center between the perforations 39 and 40 having a long interval is aligned with the center of the exposure opening in the film feeding direction (longitudinal direction). The perforations 39 and 40 are not limited to different sizes, and may be the same size.
[0017]
The photographic film 26 is created in advance in a state where the photographic film 26 is pulled out from the cartridge 24 by a length within one frame from the first frame 38b. As a result, the exposure opening 37 is brought into a state immediately before the first frame 38b of the photographic film 26 is set.
[0018]
As shown in FIG. 4, the photographic film 26 has a photosensitive layer 43 having a thickness of 2 to 4 .mu.m on one side of a support 42 having a thickness of 70 to 120 .mu.m, and a transparent magnetic film having a thickness of 10 to 14 .mu.m on the opposite side. Each of the recording layers 44 is applied. As the support 42, polyethylene naphthalate (PEN), annealed polyethylene naphthalate (A-PEN), and triacetyl cellulose (TAC) are used.
[0019]
Such a photographic film 26 is assumed to be loaded in a camera equipped with a recording head. Such a camera magnetically records various types of shooting information such as light source information, daytime synchro information, portrait information, backlight information, etc. at a position outside the range of the frame 38 for each shooting. These pieces of information are used at the time of printing at a developing laboratory. Since the transparent magnetic recording layer 44 is provided on the entire surface, it is not necessary to limit the recording position outside the range of the frame 38.
[0020]
【Example】
As shown in FIG. 5, the production of the film unit 10 is roughly divided into a photographic film manufacturing process, a cartridge storing process, and a lens-equipped film unit manufacturing process, and before the cartridge storing process and in the manufacturing process of the lens-equipped film unit. Each erase process is arranged.
[0021]
The photographic film manufacturing process is directly connected to the cartridge housing process. As shown in FIG. 6, the photographic film supply unit 48, the hole punching device 49, the standard length / cutting device 50, the sorting device 51, It is comprised from the film winding units 52-54. The film winding units 52 to 54 are composed of film winding devices 52a, 53a, 54a, cartridge supply / discharge devices 52b, 53b, 54b, and cartridge delivery devices 52c, 53c, 54c.
[0022]
A long photographic film is formed by applying the photosensitive layer 43 while drawing the support 42 in a strip shape. The long photographic film is coated with a magnetic recording layer 44. The support 42 may be coated with the magnetic recording layer 44 and then the photosensitive layer 43 may be applied. The photographic film 26 provided with the magnetic recording layer 44 is taken up on a reel 55. The reel 55 is set in the photographic film supply unit 48. The long photographic film 26 is drawn horizontally from the reel 55 with the photosensitive layer 43 side up, and perforations 39 and 40 are sequentially punched by a punching device 49.
[0023]
The standard cutting / cutting device 50 feeds the long photographic film 26 by a predetermined length with a standard feed roller 50a, and then cuts the strip photographic film 26 with a cutting mechanism 50b. create. At the time of this cutting, the rear end side in the transport direction of the long photographic film 26 is the most advanced shape of the photographic film 26 shown in FIG. 3, and the leading end side in the transport direction of the remaining long photographic film 26 is the photograph. Each of the holes 26e, 26f, and 26g is also formed at the same time so as to be adjusted to the shape of the rearmost end of the film 26 and to be engaged with the spool 35.
[0024]
Note that a sensor 50c for detecting pass / fail of the perforated perforations 39, 40 is disposed in the standard length / cutting device 50.
[0025]
The distribution device 51 distributes the photographic film 26 to each of the three film winding units 52 to 54. As a result of detection by the sensor 50c, when a perforation error in the perforations 39, 40 is detected, the photographic film 26 is distributed to the defective product carrying-out portion 56.
[0026]
The photographic film 26 distributed by the distribution device 51 is conveyed to the film winding units 52 to 54 through the conveyance chutes 57 to 59, respectively. These conveyance chutes 57 to 59 are arranged inside the dark room 60. These conveyance chutes 57 to 59 are each provided with an erasing process.
[0027]
In the erasing process, the magnetic recording layer 44 of the photographic film 26 is demagnetized by using an AC erasing method. As shown in FIG. 7, a tubular (tunnel-shaped) conductor 61, a coil 62, and an erasing circuit 63 are used. It is configured. The photographic film 26 passes through the conductor 61 at a constant speed. A plurality of coils 62 are wound around the outer periphery of the conductor 61, and a large alternating current flows from the erasing circuit 63. The erasing circuit 63 controls the alternating current so that the polarity of the magnetic field applied to the inside of the conductor 61 is successively reversed, thereby defocusing the magnetic recording layer 44 by smoothly converging the magnetic pole strength to zero.
[0028]
When passing through the conductor 61, the magnetic recording layer 44 of the photographic film 26 receives a strong alternating magnetic field and is once magnetized to a saturated state. Since this AC magnetic field is decreased while reversing the polarity several times in the positive and negative directions, when this photographic film 26 is conveyed in a constant direction at a constant speed, the magnetic recording layer 44 receives a gradually decreasing magnetic field and finally Is demagnetized to zero. The conductor 61 may have a square tube shape in addition to a circular tube. As an erasing method, the magnetic recording layer 44 may be demagnetized by a direct current erasing method.
[0029]
The film winding units 52 to 54 include film winding devices 52a, 53a, 54a, cartridge supply / discharge devices 52b, 53b, 54b, and cartridge delivery devices 52c, 53c, 54c. The cartridge 24 incorporating the spool 35 is supplied to the cartridge supply / discharge devices 52b, 53b, and 54b. The cartridge delivery devices 52c, 53c, and 54c supply the cartridge 24 supplied from the cartridge supply / discharge devices 52b, 53b, and 54b in the bright room to the film winding devices 52a, 53a, and 54a in the dark room. The film winding devices 52a, 53a, 54a are arranged in a dark room, capture the film rear end portion 26d of the photographic film 26 with an insert plate, and directly engage the spool 35 inside the cartridge 24 at the winding position. After locking, the spool 35 is rotated to wind the photographic film 26 around the outer periphery of the spool 35. As a result, the photographic film 26 is entirely stored in the cartridge 24. The photographic film cartridge containing the photographic film 26 is again discharged to the cartridge supply / discharge devices 52b, 53b and 54b.
[0030]
The discharged photographic film cartridges are classified into those that are commercially available and those that are loaded into the film unit 10. Commercially available photographic film cartridges are conveyed from the cartridge supply / discharge devices 52b, 53b, 54b to the packaging process and shipped. Moreover, what is loaded into the film unit 10 is supplied to the film unit manufacturing process.
[0031]
In the film unit manufacturing process, the unit body 12 is assembled. As the assembly of the unit main body 12, the exposure unit 20 is first assembled. The completed exposure unit 20 is attached to the main body base 18. Thereafter, the front cover 21 is attached to the main body base 18 and then sent to the photographic film loading process. The process for loading a photographic film with a patrone is a dark room, and a photographic film 22 with a patrone is supplied thereto.
[0032]
In the photographic film loading process, as shown in FIG. 8, the photographic film 26 is pulled out from the patrone 24 of the photographic film 26 with the cartridge, and a film roll 26a is created. The created film roll 26 a is loaded into the film roll chamber 27, and the cartridge 24 is loaded into the cartridge storage chamber 25. Thereafter, the rear cover 19 is attached, and the bottoms of the cartridge storage chamber 25 and the film roll chamber 27 are closed by the bottom lids 31 and 32, whereby the photographic film 22 with the cartridge is stored in a light-tight manner, and the unit body 12 is completed.
[0033]
At this time, the magnetic recording layer 44 may be magnetized by a magnetization source such as a photographic film cartridge loading step. For this reason, after erasing again in the erasing process, it is conveyed to the packaging process.
[0034]
The erasing process is to demagnetize the magnetic recording layer 44 of the photographic film 26 loaded by the AC erasing method, and has the same configuration as described in FIG. The difference is that the photographic film 26 is covered with a cover, that is, in the form of the unit main body 12, which is passed through the conductor 61 at a constant speed to demagnetize the magnetic recording layer 44.
[0035]
The unit main body 12 that has passed through the erasing process is transported to the packaging process, where after the outer case 11 is covered, the unit body 12 is shipped and shipped as a film unit 10.
[0036]
A user who has purchased the film unit 10 performs an operation as usual to perform shooting. In this operation, a film winding operation for rotating the winding knob 15 in the film winding direction is performed. By this film winding operation, the photographic film 26 is transferred from the film roll chamber 27 toward the cartridge storage chamber 25. Using this transfer, the intermittent sprocket engaged with the perforations 39 and 40 rotates, and the shutter charge mechanism charges the shutter mechanism using the rotation of the intermittent sprocket. By transferring the photographic film 26 for one frame, the film winding preventing mechanism prevents the rotation of the sprocket and the rotation operation of the winding knob 15. As a result, the first frame 38b is set in the exposure opening 37. During this time, the film counter mechanism advances the number display board by one scale and displays the remaining number of frames at that time in the number display window 17.
[0037]
When photographing, framing is performed and the shutter button 14 is pressed. As a result, the shutter mechanism operates, and during this operation, the subject light passes through the photographing lens 13 and enters the photographic film 26, and the first frame 38b is exposed. Since this shutter mechanism releases the operation of the film winding stop mechanism after the shutter release and allows the next film winding operation, the exposed photographic film 26 is then stored in the cartridge 24 by repeatedly taking pictures in the same manner. It will be rolled up.
[0038]
Thereafter, when photographing is finished on the last frame 38a of the photographic film 26, the film counter mechanism prevents the operation of the film winding stop mechanism. As a result, all the photographic films 26 can be stored inside the cartridge 24.
[0039]
The film unit 10 that has been photographed is submitted to the developing station as it is. Many photo film cartridges taken with a camera are also submitted to the laboratory. At the developing station, the outer case 11 of the film unit 10 is broken, the bottom cover 31 is opened, and the cartridge 24 is taken out. The exposed photographic film 26 is pulled out from the cartridge 24 taken out, and developed.
[0040]
The developed photographic film 26 is conveyed toward the film mask 71 of the printer processor 70 as shown in FIG. The developed photographic film 26 is continuously conveyed in a mixed manner without sorting the one photographed by the film unit 10 and the one photographed by the camera. This conveyance is controlled so that each frame 38 is automatically positioned at the opening of the film mask 71. In the process of sequentially transporting each frame 38 to the opening, the photographic information recorded on the magnetic recording layer 44 of the photographic film 26 is read from the photographic film 26 photographed by the camera having the magnetic recording function. . This shooting information is sent to the controller 74 via the decoder 73. In addition, the photographic information is not read from the photographic film 26 photographed by the film unit 10. Further, an arbitrary point of each frame 38 is subjected to three-color separation photometry by the photometric scanner 75 and sent to the controller 74 as photometric data. The controller 74 displays photographing information on a display unit such as the display 76 when each frame 38 is printed.
[0041]
The operator confirms the photographer's intention and the light source type from the displayed information, and performs a printing exposure amount correction operation from the keyboard 77 accordingly. If shooting information is not displayed, no correction is performed. The correction amount is recorded on the magnetic recording layer 44 by the recording head 78 after printing, and is used for reprinting. At this time, laboratory information such as a screen size format, the number of printed sheets, and a print size is also input from the keyboard 77 and recorded in the magnetic recording layer 44. Only the laboratory information is recorded on the developed photographic film 26 used in the film unit 10.
[0042]
At the time of printing, the controller 74 calculates an exposure value necessary for determining the printing light quantity from the photometric data, and corrects the exposure value when a correction operation is performed by the operator.
[0043]
Below the film mask 71, a light source 79 and a dimming / diffusing portion 80 are disposed. The light control diffusing unit 80 adjusts the light quality of the light source 79 based on the printing exposure amount and diffuses it uniformly. Further, a zoom lens 81 and a shutter 82 are disposed on the film mask 71. The zoom lens 81 forms an image of the print target frame 38 on the color paper 83. The exposure of the shutter 82 is controlled by the controller 74 so that the color paper 83 is appropriately exposed.
[0044]
The color paper 83 is wound up in a roll shape and is set at a print position by a paper feed roller pair 84. Then, after the controller 74 operates the shutter 82, the print-exposed color paper 83 is sent to the processor unit 85, where it is developed and dried, and then cut one frame later by the cutter 86, and the stacking unit 87 is discharged as a printed photograph.
[0045]
Note that there is a type in which photographing information is recorded in the magnetic recording layer 44 of the photographic film 26 even in a film unit with a lens. In this case, the processing is performed in the same manner as the photographic film 26 taken by the camera described above. By the way, when noise or the like is generated in the magnetic recording layer 44 of such a photographic film 26, for example, the exposure value, zoom magnification, or laboratory information may be erroneously read. First, by demagnetizing the magnetic recording layer 44 in advance at the factory, it is possible to prevent troubles caused by such erroneous reading. The same effect can be obtained with a commercially available photographic film 26 because the film is demagnetized in advance at the factory.
[0046]
The magnetic recording layer 44 may be demagnetized in the form of a photographic film cartridge, that is, a photographic film 22 with a cartridge in which the photographic film 26 is entirely stored. Moreover, you may demagnetize in the state which covered the outer case 11, ie, the form of the film unit 10. FIG. Further, in the middle of forming the photographic film cartridge 22 and the lens-fitted photo film unit 10.Degaussing in processMay be performed. Furthermore, the erasing process does not have to be incorporated in the line. For example, the magnetic recording layer may be demagnetized by applying a magnetic field to an aggregate of a plurality of pieces outside the line.
[0047]
【The invention's effect】
  As described above, in the present invention, the magnetic recording layer of the photographic film is passed through a coil that forms an alternating magnetic field at a constant speed through any one of the photographic film strip, the photographic film cartridge, and the lens-fitted photo film unit. Since an erasing process for demagnetizing is arranged, recording of erroneous signals such as noise can be surely prevented, and quality can be improved. Moreover, since the magnetic recording layer is demagnetized by passing through the coil, the erasing process can be incorporated into the manufacturing process, and the production efficiency is improved..
[Brief description of the drawings]
FIG. 1 is a perspective view showing an external appearance of a lens-fitted photo film unit.
FIG. 2 is an exploded perspective view of a unit main body.
FIG. 3 is a schematic explanatory view of a photographic film with a cartridge as seen from the emulsion surface side.
FIG. 4 is a cross-sectional view of a photographic film.
FIG. 5 is a flowchart showing the production process of a lens-fitted photo film unit.
FIG. 6 is a schematic explanatory diagram of a photographic film manufacturing process and a cartridge storing process.
FIG. 7 is a schematic explanatory diagram of an erasing process.
FIG. 8 is a schematic explanatory diagram of a photographic film loading process with a cartridge.
FIG. 9 is a schematic explanatory diagram of a printer processor.
[Explanation of symbols]
10 Film unit with lens
13 Shooting lens
24 Patrone
26 Photo film
44 Magnetic recording layer
52 Patrone Entrainment Unit
61 conductors
62 coils
63 Erase circuit

Claims (3)

A method for producing a photographic film having a magnetic recording layer for recording data,
A photographic film manufacturing process for producing a strip-shaped photographic film by coating a photosensitive layer on one side of a long transparent support and a transparent magnetic recording layer on the entire other side, and the magnetic recording layer A photographic film with a fixed length / cutting process in which the photographic film is cut into fixed lengths and cut at fixed lengths while being transported in one direction in the dark room, and the cut photographic film strips are sent to the dark room. An alternating magnetic field is formed in the coil by magnetic field forming means, the photographic film strip is passed through the coil at a constant speed, and the photographic film strip is separated from the coil so that the strength of the alternating magnetic field becomes zero. And a erasing step of demagnetizing the magnetic recording layer by gradually converging the magnetic recording layer. In a method for producing a photographic film cartridge in which a photographic film having a magnetic recording layer for recording data is stored in the cartridge,
A photographic film manufacturing process for producing a strip-shaped photographic film by coating a photosensitive layer on one side of a long transparent support and a transparent magnetic recording layer on the entire other side, and the magnetic recording layer A standard length / cutting step of feeding a strip of photographic film after being cut by a fixed length / cutting mechanism installed in a dark room while conveying the strip-shaped photographic film provided with a unidirectional direction, A patrone storage step for transporting the photographic film strip sent out from the standard length / cutting process to a film winding unit and winding the photographic film strip into an empty cartridge by the film winding unit to create a photographic film cartridge, and the cartridge The photographic film strip is placed in a coil which is arranged either before or after the storing process, forms an alternating magnetic field by the magnetic field forming means and is arranged in the dark room, The photographic film cartridge is passed at a constant speed through the coil in which the alternating magnetic field is formed by the magnetic field forming means, and the magnetic recording layer is gradually converged toward zero by moving away from the coil to demagnetize the magnetic recording layer. A photographic film cartridge comprising the erasing step. In a method of manufacturing a lens-fitted photo film unit preloaded with a photographic film cartridge and provided with an exposure mechanism, a photosensitive layer is provided on one side of a long transparent support, and a transparent magnetic recording is provided on the entire other side. A photo film manufacturing process for creating a strip-shaped photographic film by coating each layer, and a fixed length and cutting mechanism installed in a dark room while transporting the strip-shaped photographic film coated with the magnetic recording layer in one direction. A standard length / cutting process for cutting the photographic film strip after cutting and feeding the photographic film strip after cutting, and the photographic film strip sent from the standard length / cutting step is transported to the film winding unit, where the film winding unit takes a picture. A patrone storage process for creating a photographic film patrone by wrapping a film strip in an empty patrone, and a photograph obtained in the patrone storage process A film unit with a lens for creating a film unit with a lens by loading a film cartridge into a unit main body incorporating an exposure applying mechanism, and forming an alternating magnetic field in the coil by a magnetic field forming means, and the lens in the coil The erasing step is to demagnetize the magnetic recording layer by passing the attached film unit at a constant speed and gradually converging the strength of the alternating magnetic field toward zero by moving the attached film unit away from the coil. A method for producing a lens-fitted photo film unit.

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