JPH0968778A - Spool for photographic film and winding structure for photographic film - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To easily wind a film around a spool in a dark room, reduce a loss of a filmable area of the film, and reduce a spool outer diameter or a film base. A spool for photographic film and a winding structure for photographic film that can increase the winding length on the spool without protruding the end of the film from the spool that causes pressure fog even if it is thinned and can increase the number of shots. A spool 13 for a photographic film, on which a photographic film 11 is wound on a winding shaft 13a, is provided with a pair of locking projections 14 and 15 exposed on the outer circumference of the winding shaft 13a. On the front side of the pair of locking projections 14 and 15 in the winding direction, the wound film 11 is wound.
The convex portion 23 having a smooth surface is formed on the outer periphery so that the protrusions 23 do not hit the locking protrusions 14 and 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographic film in which a photographic film is wound on a winding shaft by engaging a pair of locking projections provided on the winding shaft with locking holes at the end portions of the photographic film. The present invention relates to a spool and a winding structure of a photographic film using the spool.

[0002]

10 to 13 show a photographic film 1 and a spool disclosed in Japanese Utility Model Publication No. 60-35068 as a conventional example of a photographic film wound on a spool rotatably supported in a cartridge. 3 is shown. The photographic film 1 shown here is a film having a film width of 35 mm and is used for a so-called 35 mm camera or a camera called a half size camera.

In this photographic film 1, as shown in FIG. 10, the front end portion 1a is formed in a narrow width by cutting off one side edge at a portion to be inserted into the groove of the take-up reel on the camera side.
The end portion 1b is formed to have a narrow width by cutting off both side edges at the engaging portion for the spool 3, and two engaging holes 2a, 2b for engaging with the spool 3 are spaced apart in the film width direction. It is provided. The two locking holes 2a and 2b have an oval shape elongated in the longitudinal direction of the film. Further, the width W of the end portion 1b is set to about 15 to 17 mm.

On the other hand, as shown in FIGS. 11 to 13, the spool 3 is provided with flanges 4a and 4b near both ends of a winding shaft 3a around which the photographic film 1 is wound. The winding shaft 3a has a film insertion opening. 5 are provided. The film insertion port 5 penetrates in one diameter direction of the winding shaft 3a, and among the upper and lower walls 6 and 7 forming the insertion port 5, the upper wall 6 has a substantially center in the longitudinal direction of the insertion port 5. A film pressing rib 8 is formed on the lower wall 7, and two locking claws 9 and 10 are formed on the lower wall 7. Further, ribs 6a and 7a (7a is not shown) extending along the axial direction of the winding shaft 3a are provided at substantially the center of the outer sides of the upper and lower walls 6 and 7, respectively.

With the above structure, the photographic film 1
As shown in the arrow (a) in FIG. 11, when the end portion 1b of the end portion 1b is inserted into the insertion opening 5, both side portions of the end portion 1b follow the inclined portions 9b and 10b of the two locking claws 9 and 10. And is guided obliquely upward, and the central portion is guided obliquely downward by the inclined surface 8b of the film pressing rib 8, so that the end portion 1
b is pressed downward at the center in the width direction and is in a curved state. Then, when the photographic film 1 is further inserted, the inclined portions 9b and 10b of the two locking claws 9 and 10 start to be caught in the corresponding two locking holes 2a and 2b, and the shoulder portions 1c and 1c of the photographic film 1 are wound. As shown in FIG. 12, when the shaft 3a is inserted to a position where it hits the cylindrical portions at both ends, the two locking claws 9 and 10 are restored by the restoring force of the curved photographic film 1 itself.
Engage with the two locking holes 2a, 2b. The engaged end portion 1b has two locking claws 9 by the film pressing ribs 8,
It is pushed into the root side of 10.

[0006]

In order to wind the photographic film on the spool 3, the photographic film must be wound in a dark room so that the photographic film 1 is not exposed to light.
However, in the structure of the conventional photographic film and spool described above, inserting the film end portion 1b into the film insertion opening 5 provided in the winding shaft 3a of the spool 3 in the dark room is
It was very difficult and required skill, and even if it tried to automate it, it was not easy to control it. Further, the film end portion 1 is inserted into the film insertion opening 5 provided on the winding shaft 3a.
The portion where b is inserted or the portion where the end portion 1b is narrowed becomes the loss of the imageable area. This is a slight one for each photographic film product, but is significant for high volume producers. By reducing the loss of the photographable area of the photographic film, it is possible to manufacture one product with the same number of shots as the conventional one while reducing the amount of raw materials used. In other words, the same amount of raw materials can produce more products than ever before.

Further, the photographic film wound around the spool 3 has been used for taking 12 sheets, for taking 24 sheets, and for 3 sheets so far.
The spool 3 of the photographic film 1 having different winding lengths such as for taking 6 sheets has been commercialized, and the required number of sheets can be selected according to the application. However, recently, the emergence of films with a larger number of shots is required. However, since the size of the cartridge that accommodates the spool 3 is determined by the standard, it is necessary to increase the number of images to be taken for 36 or more by reducing the diameter of the spool 3a of the spool 3 or for taking photographs. New measures such as reduction of the thickness of the film 1 itself are required.

However, if the diameter of the winding shaft 3a of the spool 3 is simply reduced, or the thickness of the photographic film 1 itself is reduced, serious defects may occur. For example, when an attempt is made to increase the number of images to be taken by reducing the outer diameter of the spool 3, as shown in FIG. 14, the end portion 1b of the photographic film 1 is on the side opposite to the insertion port 5 of the spool 3. Since the protruding film end 1b abuts on the film 1 which is projected to the end and is wound around the outer periphery of the spool 3, a defect such as pressure fog is likely to occur.

Further, in order to increase the number of images to be taken by reducing the thickness of the photographic film 1 itself, a film support coated with a light-sensitive emulsion (hereinafter, also referred to as a film base) has a thickness larger than that of a conventional one. When a film having a small size is used, the tensile strength of the film support will be lower than before. The locking force of the film end portion 1b with respect to the spool 3 is standardized by an international standard (ISO standard, ANSI standard, etc.) (for example, the ISO standard specifies that the locking force is 4 kgf). Those that do not meet these standards cannot be shipped to the market as products.

When the one having a small thickness dimension is adopted, in order to satisfy the above international standard, the shortest distance L (from the periphery of each locking hole 2a, 2b in the film end portion 1b to the film end is inevitable. It is necessary to increase (see FIG. 11) to compensate for the decrease in the locking force. However, if the shortest distance L from the peripheral edge of the locking holes 2a and 2b to the film end is increased in this way, as in the case of reducing the outer diameter of the spool 3 (as shown in FIG. 14), the film end 1b is reduced. Is projected on the opposite side of the insertion port 5 of the spool 3 and the film end 1b projected on the film 1 wound around the outer periphery of the spool 3 is abutted, so that pressure fog is likely to occur. After all, the increase in the number of photographed images cannot be realized simply by making the photographic film 1 thin or reducing the diameter of the spool 3.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems, and it is easy to wind a film around a spool in a dark room, and it is possible to reduce the loss of the filmable area of the film, and the spool. Even if the outer diameter is reduced or the film base is made thin, there is no protrusion of the film end from the spool that causes pressure fog, and the winding length on the spool can be increased to increase the number of shots. To provide a spool and a photographic film winding structure.

[0012]

SUMMARY OF THE INVENTION The above object of the present invention is to wind a photographic film on a winding shaft by engaging a pair of locking protrusions provided on the winding shaft with locking holes at the end portions of the photographic film. A spool for a photographic film to be mounted, wherein the pair of locking projections are provided so as to be exposed on the outer periphery of the winding shaft, and the pair of locking projections are provided in front of the pair of locking projections in the film winding direction. Is achieved by a spool for photographic film, characterized in that a convex portion having a smooth surface is formed on the outer periphery so that the wound film does not hit the locking projection.

Further, in the above photographic film spool, a film end accommodating groove for inserting a film end edge is formed along the axial direction of the winding shaft at the base of the convex portion on the side of the locking protrusion. The above object can be achieved even when the film end accommodating groove restricts the warp of the film end edge in the outer diameter direction.

Further, the above object of the present invention is a photographic film winding structure using the above spool, wherein the perforation formed at the side edge portion of the photographic film is located closest to the end of the film. The present invention is also achieved by a photographic film winding structure characterized in that the photographic film is wound by engaging a pair of locking projections on the spool winding shaft as locking holes at the end of the film. .

Further, in the above-described photographic film winding structure, the photographic film wound on the spool has a thickness of 85 to 85 as a film base to which a photosensitizer is applied.
In the range of 95 μm, the tear strength in the longitudinal direction of the film is 110 to 155 g, and the tear strength in the width direction is 75 to 1
50g, Young's modulus in the longitudinal direction of the film is 530-690
kg / mm ² , Young's modulus in the width direction is 550 to 750 kg
The above object can be achieved even when a film material having physical properties of / mm ² is used and the shortest distance from the periphery of the locking hole at the end of the film to the end of the film is set in the range of 1 to 4 mm. Is something that can be done.

Further, in the above photographic film winding structure, the above object can be achieved even if the corners of the perforations used as the locking holes are set to arcs having a radius of curvature of 0.5 mm or more. Is something that can be done.

[0017]

According to the above-described structure of the present invention, since the locking projections provided on the spool are provided on the outer circumference of the winding shaft, the film end portion is locked to the winding shaft in a posture circumscribing the winding shaft. become. That is, as compared with the conventional structure in which the film end is inserted into the film insertion opening provided in the axial direction of the winding shaft, the winding operation is facilitated in a dark room, and the end portion inserted into the film insertion opening is The loss of the recordable area decreases as much as it disappears. Moreover, since the film wound around the winding shaft can avoid contact with the locking projections due to the convex portion of the smooth surface formed on the outer circumference of the winding shaft, the photographic film to be wound and the locking projections can be prevented. It is possible to prevent the inconvenience of pressure fog caused by the contact force.

Further, a film end accommodating groove for inserting a film end edge is formed along the axial direction of the winding shaft at the base of the convex portion formed on the outer periphery of the spool of the spool on the side of the locking projection. When the film end accommodating groove is used to restrict the warp of the film end edge in the outer diameter direction of the winding shaft, the problem of pressure fog caused by the protrusion of the film end edge from the outer circumference of the winding shaft can be prevented more reliably. You will be able to do it.

Further, the perforations formed on the side edges of the photographic film, which are located closest to the film end, are engaged with a pair of locking projections on the spool shaft as locking holes at the film end. Thus, when the photographic film is wound, the end portion of the film has a simple shape, and the process of cutting off the side edge of the film is unnecessary, and the yield of the film can be improved. Since the mounting position of the stop projection is outside the photographing area on the film (that is, the position of the perforation), it is possible to more reliably avoid the possibility that the locking projection hits the film wound around and causes the pressure fog.

The photographic film wound on a spool has a thickness of 85 to 95 μm as a film base to which a photosensitizer is applied, a tear strength in the longitudinal direction of the film of 110 to 155 g, and a width direction. Tear strength of 75-150g, Young's modulus in the longitudinal direction of the film is 5
30-690 kg / mm ² , Young's modulus in the width direction is 550
When a film material having physical properties of up to 750 kg / mm ² is used, the film base itself has higher tensile strength and the like than polyethylene terephthalate (PET) which is generally used as a film base for conventional photographic film. Since a high-strength film material that can obtain a stopping force is used, even if the thickness is reduced, the distance from the peripheral edge of the locking hole at the film end to the film end is equal to or smaller than the conventional size. It is possible to secure a sufficient locking force that can satisfy the standard.

At that time, the shortest distance from the periphery of the locking hole at the end of the film to the end of the film is 1 to 4
By setting it in the range of mm, while securing a sufficient locking force that can satisfy the standard, it is possible to reduce the loss of the imageable area and reduce the outer diameter of the spool reel. Even in this case, it is possible to suppress the protrusion of the film end edge toward the outer circumference of the winding shaft and prevent the pressure fog caused by the film end protrusion. The corner of the perforation used as the locking hole has a radius of curvature of 0.
When the arc is set to 5 mm or more, the locking force can be prevented from being concentrated on a part of the locking hole, and a large locking force satisfying the standard can be easily obtained.

[0022]

1 to 4 show an embodiment of a photographic film spool and a photographic film winding structure according to the present invention. FIG. 1 shows a spool around which the photographic film 11 is wound. 13 is a perspective view showing the structure of FIG. 13, FIG. 2 is a sectional view showing the engaged state of the photographic film 11 and the spool 13, FIG. 3 is a plan view showing the entire structure of the photographic film 11 of one embodiment, and FIG. 3 is an enlarged view of a film end portion of the photographic film 11 shown in FIG.

The photographic film 11 of this embodiment is a film having a film width of 35 mm and is used for a so-called 35 mm camera or a camera called a half size camera.

Further, the photographic film 11 has two locking projections 14 and 15 on the winding shaft 13a of the spool 13 rotatably supported in the cartridge, and two locking holes 17 formed in the film end portion 1b. , 18 to engage the winding shaft 13
The film base coated with a photosensitizer has a thickness of 85 to 95 μm and a tear strength of 110 to 15 in the longitudinal direction of the film.
5 g, tear strength in the width direction of 75 to 150 g, Young's modulus in the longitudinal direction of the film of 530 to 690 kg / mm ² ,
A film material having physical properties of Young's modulus in the width direction of 550 to 750 kg / mm ² is used. As the film material having such physical properties, for example, polyethylene naphthalate (PEN) or the like is applicable.

Conventionally, polyethylene terephthalate has generally been used as a film base for a 35 mm film. The physical properties of this polyethylene terephthalate are a thickness dimension of 130 μm and a tear strength in the longitudinal direction of the film of 90 to 110 g. The tear strength in the width direction is 70 to 90 g, and the Young's modulus in the film longitudinal direction is 43.
0-520 kg / mm ² , Young's modulus in the width direction is 430
It is about 520 kg / mm ² , and the film material used in one example is superior to the conventional polyethylene terephthalate in tensile strength and the like, and even if the film thickness is thinner than the conventional one, a higher locking force than the conventional one is obtained. It will be possible.

Further, in the photographic film 11 of this embodiment, the film front end portion 19 is a portion to be inserted into the groove of the take-up reel on the camera side, and one side edge is cut off as in the case of the conventional film. It has a narrow form. And, as a characteristic, as shown in FIG. 3 and FIG. 4, the shortest distance L from the periphery of the locking holes 17 and 18 in the film end portion 1b to the film end is set in the range of 1 to 4 mm. . The locking holes 17 and 18 are square holes having rounded corners, and the curved contours of the corners are arcs having a radius of curvature R of 0.5 mm or more.
Further, the guide perforations 20 formed on the side edges of the film 11 at positions closest to the film end are used as the locking holes 17 and 18.

In the photographic film 11 described above, the distance L from the periphery of the locking holes 17 and 18 to the film ends at the film end portion 1b and the radius of curvature R of the curved contour of the locking holes 17 and 18 are as follows. Based on the results of investigating the relationship between the various values of L and R with the locking force, the optimum range that can satisfy the international standard was obtained. FIG.
Is the relationship between the distance L from the periphery of the locking holes 17 and 18 in the film end portion 1b to the film end and the locking force,
It was investigated by changing the conditions of the film base. The horizontal axis is the distance L (unit: mm), and the vertical axis is the locking force (unit: kg).
f) is taken. The curve f ₁ in the figure shows the case where a polyethylene naphthalate film having a thickness of 130 μm is used as the film base, and the curve f ₂ is 90 μm as the film base.
The case where m-thickness polyethylene naphthalate is used is shown, and the curve f ₃ shows the case where 130 μm-thickness polyethylene terephthalate (conventional material) is used as the film base.

As described above, when the film base is polyethylene naphthalate, even if the film thickness is reduced to 90 μm as compared with the conventional product using 130 μm thick polyethylene terephthalate, if the L dimension is 1 mm, for example, Locking force 4kgf specified by ISO standard
The above locking force can be secured. According to experiments conducted by the inventors of the present application, although not shown, when a film material having the same strength as polyethylene naphthalate is used, the film thickness is selected from the range of 85 to 95 μm.
It has been confirmed that if the L is selected in the range of 1 to 4 mm, a sufficient locking force that can satisfy the international standard can be secured.

Further, FIG. 6 shows the relationship between the radius of curvature R of the curved contours of the locking holes 17 and 18 in the film end portion 1b and the locking force under different conditions of the film base. The radius R (unit: mm) is plotted on the horizontal axis, and the locking force (unit: kgf) is plotted on the vertical axis. The curve g ₁ in the figure shows the case where a 90 μm thick polyethylene naphthalate is used as the film base, and the curve g ₂ shows the case where a 130 μm thick polyethylene terephthalate (conventional material) is used as the film base.

As described above, when the film base is made of polyethylene naphthalate, R is 0.2 mm or more even if the film thickness is reduced to 90 μm as compared with the conventional product using polyethylene terephthalate having a thickness of 130 μm. For example, it is possible to secure a sufficient locking force that can satisfy the ISO standard, for example. According to another experiment by the inventors of the present application, although not shown, in the case of using a film material having the same strength as polyethylene naphthalate,
It was confirmed that if the film thickness is selected from the range of 85 to 95 μm and the R is selected to be 0.5 mm or more, a sufficient locking force satisfying the international standard can be secured.

On the other hand, the spool 13 has flanges 21 and 22 at both ends of the winding shaft 13a, and the photographic film 11 is wound on the winding shaft 13a between the flanges 21 and 22. However, as shown in FIGS. 1 and 2, there are two locking protrusions 1 that engage with the locking holes 17 and 18.
4, 15 are provided so as to be exposed on the outer surface of the winding shaft 13a. Further, on the winding shaft 13a, the wound film 11 is prevented from hitting the locking projections 14 and 15 on the front side of the pair of locking projections 14 and 15 in the film winding direction. Therefore, a smooth convex portion 23 is formed on the outer peripheral surface of the winding shaft 13a. The spool 13 shown in FIGS. 1 and 2 will be described in more detail. A recessed portion 25 is formed by recessing the outer peripheral surface of the outer peripheral circle (outer diameter D) of the winding shaft 13a, and is locked in the recessed portion 25. The protrusions 14 and 15 were provided, and the refraction portion formed by the outer circumference circle (outer diameter D) and the depression portion 25 was used as the protrusion 23. Then, the depth dimension of the recessed portion 25 (from the tips of the locking projections 14 and 15 to the recessed portion 25
Of the film) K is set to be larger than the dimension L of the film end portion 1b. The structure of the locking projections 14 and 15 and the convex portion 23 of the spool 13 used in this embodiment is as described above.
If the distance M from the center O of the winding shaft 13a to the outermost contour of the convex portion 23 is longer than the distance m to the outermost contour of the locking projections 14 and 15 and the convex portion 23 is not shown, It may have other shapes.

In order to lock the film end portion 1b of the photographic film 11 of the above-described embodiment on the spool 13, the procedure shown in FIG.
As shown in FIG.
5 is fed to the base of the convex portion 23 so as to circumscribe the upper end surface of the film 5, and when the tip of the film end portion 1b hits the base of the concave convex portion 23, the photographic film 11 is locked by the projections 14,
If you pull it back while pressing it to the 5 side,
The tips of the locking projections 14 and 15 projecting to the 3 side are fitted into the locking holes 17 and 18, and the engagement is completed.

In the above-described embodiment, since the locking projections 14 and 15 provided on the spool 13 are provided on the outer surface of the winding shaft 13a, the film end portion 1b is circumscribed by the winding shaft 13a. Will be locked in. That is, as compared with the conventional structure in which the film end portion 1b is inserted into the film insertion opening 5 provided in the axial direction of the winding shaft 13a, the winding operation in the dark room becomes easier, and the film insertion opening 5 is inserted. The loss of the imageable region is reduced by the amount of the removed end portion 1b. In addition, the film 11 wound around the winding shaft 13a is prevented from coming into contact with the locking projections 14 and 15 by the convex portion 23 having a smooth surface formed on the outer circumference of the winding shaft 13a. It is possible to prevent the inconvenience of pressure fog caused by the contact force between the film 11 and the locking projections 14 and 15.

Further, the perforations 20 formed on the side edges of the photographic film 11 at the position closest to the film end are the locking holes 17, 1 of the film end 1b.
As shown in FIG. 8, the photographic film 11 is wound by engaging the pair of locking protrusions 14 and 15 on the winding shaft 13a of the spool 13 to wind the photographic film 11. Therefore, the film end portion 1b has a simple shape as shown in FIG. The process of cutting off the side edge of the film is not necessary, the yield of the film 11 can be improved, and the mounting positions of the locking protrusions 14 and 15 are outside the photographing area on the film 11 (that is, perforation 2).
Since the locking projections 14 and 15 come into contact with the film wound around, the possibility of causing pressure fog is also avoided.

Further, the photographic film 11 wound on the spool 13 has a thickness of 85 to 95 μm as a film base on which a photosensitizer is applied, a tear strength of the film in the longitudinal direction of 110 to 155 g, and a width. Tear strength in the direction of 75 to 150 g, Young's modulus in the longitudinal direction of the film is 530 to 690 kg / mm ² , Young's modulus in the width direction is 550 to 750 kg / mm ² , and the film material has higher strength than the conventional case. Therefore, even when the wall thickness is reduced, the locking hole 1 in the film end portion 1b is used.
Even if the distance from the periphery of 7, 18 to the end of the film is equal to or less than the conventional size, it is possible to secure a sufficient locking force that can satisfy the standard, and by making the film base thinner. It is also possible to increase the number of shots.

Further, the shortest distance from the periphery of the locking holes 17 and 18 in the film end portion 1b to the film end is 1
Since it is limited to a relatively small range of ~ 4 mm, it is possible to secure a sufficient locking force that can satisfy the standard, while reducing the loss of the imageable area,
Further, even when the outer diameter of the winding shaft 13a of the spool 13 is reduced, the film end edge is prevented from protruding to the outer circumference of the winding shaft 13a,
It becomes possible to prevent the pressure fog caused by the protrusion of the film end. Therefore, it is possible to effectively increase the number of photographed images by both reducing the outer diameter of the winding shaft 13a and thinning the film base. According to experiments by the inventors of the present application, the outer diameter (diameter) of the winding shaft is 10 mm in the conventional case.
However, according to the present invention, pressure fog does not occur even if the outer diameter of the winding shaft 13a is reduced to about 5 mm,
It has become possible to increase the number of shots by the reduced diameter. Further, since the corner portions of the perforations 20 used as the locking holes 17 and 18 are set to have an arc with a radius of curvature of 0.5 mm or more, the locking force is set to the locking holes 17 and 1.
It is possible to avoid concentrating on a part of 8, and it is easy to obtain a large locking force that satisfies the standard.

7 and 8 show another embodiment of the spool according to the present invention. FIG. 7 is a perspective view showing the structure of the spool 33 of another embodiment, and FIG. It is sectional drawing which shows the engagement state with the film 11. The spool 33 of the other embodiment has a protrusion 23 on the winding shaft 13a.
A film end accommodation groove 24, through which the film end edge is inserted, is formed along the axial direction of the winding shaft 13a at the base of the locking projections 14 and 15 side of the film. The spool 13 is configured to restrict the warp to the outside, and is the same as the spool 13 of the embodiment except that the film end accommodation groove 24 is provided. Further, the photographic film 11 wound around the spool 33 has the same structure as that of the one embodiment.

In order to engage the film end portion 1b of the photographic film 11 with the spool 33 of the other embodiment, as shown in FIG.
As shown in FIG. 3, the film end portion 1b is fed into the film end accommodation groove 24, and when the tip of the film end portion 1b hits the inner depth of the film end accommodation groove 24, the photographic film 11 is moved to the locking projections 14, 15 side. When pulled back in the pressed state, the tips of the locking projections 14 and 15 projecting to the film end accommodation groove 24 side are fitted into the locking holes 17 and 18, and the engagement is completed. Spool 3 of another embodiment
3, the film end edge is formed by the film end receiving groove 24.
With this configuration, when the warp of the film end edge in the outer diameter direction of the winding shaft 13a is restricted, it is possible to more reliably prevent the inconvenience of pressure fog due to the protrusion of the film end edge from the outer circumference of the winding shaft. It will be. In the embodiment described above, the perforation 20 is attached to the locking hole 1.
However, as shown in FIG. 9, separate locking holes 17 and 18 may be provided separately from the perforations 20.

The film base used in the photographic film of the present invention has a thickness of 85 to 95 μm.
Tear strength in the longitudinal direction of the film is 110-155
g, the tear strength in the width direction is 75 to 150 g, the Young's modulus in the longitudinal direction of the film is 530 to 690 kg / mm ² , and the Young's modulus in the width direction is 550 to 750 kg / mm ² . It is not limited to polyethylene naphthalate.

[0040]

According to the spool for a photographic film and the winding structure for a photographic film of the present invention, since the locking protrusions provided on the spool are provided on the outer peripheral surface of the winding shaft, the spool is provided in the axial direction of the winding shaft. Compared with the conventional structure in which the end of the film is inserted into the film insertion port, the winding operation in a dark room is easier and the end of the film insertion port is eliminated, resulting in loss of the recordable area. I have less minutes. Moreover, since the film wound around the winding shaft can avoid contact with the locking projections due to the convex portion of the smooth surface formed on the outer circumference of the winding shaft, the photographic film to be wound and the locking projections can be prevented. It is possible to prevent the inconvenience of pressure fog caused by the contact force. Further, a film end accommodating groove for inserting the film end edge is formed along the axial direction of the winding shaft at the base of the protrusion formed on the outer circumference of the spool of the spool on the side of the locking protrusion. When the groove is configured to restrict the warp of the film end edge in the outer diameter direction of the winding shaft, it is possible to more reliably prevent the inconvenience of pressure fog caused by the projection of the film end edge from the outer circumference of the winding shaft. become.

Further, the perforations formed on the side edges of the photographic film, which are located closest to the film end, are engaged with a pair of locking projections on the spool shaft as locking holes at the film end. Thus, when the photographic film is wound, the end portion of the film has a simple shape, and the process of cutting off the side edge of the film is unnecessary, and the yield of the film can be improved. Since the mounting position of the stop projection is outside the photographing area on the film (that is, the position of the perforation), it is possible to more reliably avoid the possibility that the locking projection hits the film wound around and causes the pressure fog. The photographic film wound on the spool has a thickness of 85 to 95 as a film base to which the photosensitizer is applied.
In the range of μm, the tear strength of the film in the longitudinal direction is 1
10-155g, tear strength in the width direction is 75-150
g, Young's modulus in the longitudinal direction of the film is 530 to 690 kg
/ Mm ² , Young's modulus in the width direction is 550 to 750 kg / m
When a film material having a physical property of m ² is used, the film base itself has higher tensile strength and the like than polyethylene terephthalate which is generally used as a film base for conventional photographic film, and a high locking force can be obtained. Even if the thickness is reduced, the distance from the edge of the locking hole at the end of the film to the end of the film should be the same as or smaller than the conventional size, because the film material with high strength is used. It is possible to secure a sufficient locking force that can be achieved, and it is possible to increase the number of shots by thinning the film base.

At that time, the shortest distance from the periphery of the locking hole at the end of the film to the end of the film is 1 to 4
By setting it in the range of mm, while securing a sufficient locking force that can satisfy the standard, it is possible to reduce the loss of the imageable area and reduce the outer diameter of the spool reel. Even in this case, it is possible to suppress the protrusion of the film end edge toward the outer circumference of the winding shaft and prevent the pressure fog caused by the film end protrusion. Therefore, it is possible to increase the number of photographed images by both reducing the outer diameter of the winding shaft and thinning the film base. Also, when the corners of the perforations used as the locking holes are set to arcs with a radius of curvature of 0.5 mm or more, it is possible to avoid the locking force from concentrating on part of the locking holes, and the standard It becomes easy to obtain a satisfactory large locking force.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an embodiment of a spool according to the present invention.

FIG. 2 is a cross-sectional view taken along the line BB of FIG. 1, showing the engaged state of the photographic film and the spool according to the embodiment of the present invention.

FIG. 3 is a plan view showing the overall configuration of an embodiment of a photographic film according to the present invention.

FIG. 4 is an enlarged view of a film end portion of the photographic film shown in FIG.

FIG. 5 is a characteristic curve diagram showing the relationship between the distance L from the periphery of the locking hole to the film end and the locking force in one embodiment.

FIG. 6 is a curvature radius R of the curved portion of the locking hole in the embodiment.
It is a characteristic curve figure which shows the relationship between a locking force and.

FIG. 7 is a perspective view showing the configuration of another embodiment of the spool according to the present invention.

FIG. 8 is a cross-sectional view taken along the line CC of FIG. 1, showing the engaged state of the photographic film and the spool according to another embodiment of the present invention.

FIG. 9 is a structural explanatory view of a film end portion of another embodiment of the photographic film according to the present invention.

FIG. 10 is a view showing an end shape of a conventional photographic film.

11 is a perspective view of a conventional spool for locking the photographic film shown in FIG.

12 is a perspective view in which a part of the spool shown in FIG. 11 is cut away to expose a locking form.

13 is a cross-sectional view taken along the line AA of FIG.

FIG. 14 is an explanatory diagram of a problem when the number of wound films is increased by a conventional structure for locking a photographic film on a spool.

[Explanation of symbols]

 11 Photographic Film 13,33 Spool 13a Winding Spindle 1b Film End 17,18 Locking Hole 19 Film Tip 20 Perforation 23 Convex 24 Film End Storage Groove R Radius of Curvature

Claims (5)

[Claims] 1. A spool for a photographic film, wherein a pair of locking projections provided on a winding shaft is engaged with a locking hole at an end portion of the photographic film to wind the photographic film on the winding shaft. The pair of locking projections are provided so as to be exposed on the outer circumference of the winding shaft, and a wound film is provided on the front side of the pair of locking projections in the film winding direction. A spool for photographic film, characterized in that a convex portion with a smooth surface is formed on the outer periphery so as not to hit the 2. A film end accommodating groove into which a film end edge is inserted is formed along the axial direction of the winding shaft at the base of the convex portion on the side of the locking protrusion, and the film end accommodating groove allows the film end edge to be inserted. The spool for photographic film according to claim 1, wherein the protrusion of the spool in the outer diameter direction is restricted. 3. A photographic film winding structure using the spool according to claim 1 or 2, wherein a perforation formed at a side edge of the photographic film is located at a position closest to a film end. A photographic film winding structure, characterized in that the photographic film is wound by engaging a pair of locking protrusions on the winding shaft of the spool as locking holes at the end portion. 4. The photographic film wound on a spool has a thickness of 85 to 95 μm as a film support to which a photosensitizer is applied, a tear strength in the longitudinal direction of the film of 110 to 155 g, and a width. Tear strength of 7
5 to 150 g, Young's modulus in the longitudinal direction of the film is 530 to
690 kg / mm ² , Young's modulus in the width direction is 550 to 75
A film material having a physical property of 0 kg / mm ² is used, and the shortest distance from the periphery of the locking hole at the film end portion to the film end is set within a range of 1 to 4 mm. The wrapping structure of the photographic film described in. 5. The photographic film winding structure according to claim 3, wherein the corner portion of the perforation used as the locking hole is set to an arc having a radius of curvature of 0.5 mm or more.