Photographic film cassette with light-trapping members and method for treating light-trapping members

Abstract: A photographic film cassette (3) whose leading end (5a) of a photographic film (5) is initially positioned in a cassette shell (7) and advanced through a film passageway (4) out of the cassette shell (7) by rotation of a spool (6). Light-trapping members (2a,2b) are attached to upper and lower surfaces of the film passageway (4). After assembling the photographic film cassette (3), the leading end (5a) is advanced through the film passageway (4) out of the cassette shell (7) and returned to an inside of the cassette shell (7) so that tips of piles of the light-trapping members (2a,2b) are arranged in order to push against each other with the tips inclined in a film moving direction. In a preferred embodiment, a sheet member is inserted into and drawn from a film passageway to arrange the piles so as to make them incline in a film advancing direction.

Description: The present invention relates to a method of manufacturing a photographic film cassette of the type as described in the preamble of claim 1. A photographic film cassette manufactured by a method of this type is described in EP-A-0 421 097. The known film cassette includes a passageway for the film to be advanced out of a film cassette, which passageway is provided with light-trapping members attached to opposite sides thereof. The light-trapping members include a velvet or plush material having piles extending forward in an overlapping relationship to the piles of the light-trapping member attached to the opposite surface of the passageway. The piles remain parallel to each other and rectangular to the opposite surfaces of the passageway until the film will be advanced out of the cassette shell for exposure. EP-A-0 378 169 describes a photographic film cassette having a passageway for the film to be advanced out of the film cassette. The passageway is provided with light-trapping members attached to opposite sides thereof. The light-trapping members include a pile-like material consisting of short, close fine fibres or hairs. The fibres are inclined generally in the moving direction of the film when the film is advanced out of the cassette shell for exposure. The fibres or hairs are adapted to engage the film leader to prevent its casual creep, particularly rearward, in the film passageway. The method of providing the pile-like material with the inclined fibres is not disclosed. EP-A-0 440 240, published after the priority date of the present application, describes a photographic film cassette having two light-trapping members arranged on opposite surfaces of a passageway for the film out of the cassette shell. The light-trapping members have been made of a pile fabric treated to incline the piles in the moving direction of the film. The treatment of the light-trapping members takes place by a brushing process and before the members have been inserted into the cassette shell and the cassette shell has been assembled. The known film cassette is one of the well-known photographic film cassettes wherein a spool is rotated in an unwinding direction so as to propel a leading end of a photographic film through a film passage mouth to the outside of a cassette shell. In such photographic film cassettes, it is very important to reduce resistance of light-trapping members against the form leading end in order to facilitate the smooth advancement of the film leading end to the outside of the film passage mouth. In order to reduce the necessary torque for advancing the film, it has been proposed in the post-published EP 440 240 to provide a photographic film cassette with light-trapping members wherein the piles of the light-trapping members attached to a film passageway of a cassette shell are inclined toward a film passage mouth. However, it is technically difficult to manufacture light-trapping members so that piles always have a predetermined constant inclination. Discrepancy of the inclination effects the thickness of the light-trapping members. If the thickness of the light-trapping members becomes small, ambient light would enter the cassette shell through the film passage mouth, while if that becomes large, the film propelling resistance would Increase. Besides, when cutting the light-trapping members out of a web, a lot of dirt particles are yielded as tips of the piles being inclined are cut. Furthermore, it is necessary to attach the light-trapping members to the film passageway such that the inclination of the piles is directed toward the outside of the film passage mouth, which is rather troublesome and results in a low product efficiency. It is an object of the present invention to provide a method of manufacturing a photographic film cassette and a method for treating light-trapping members wherein a leader of a photographic film can be propelled out of a cassette shell with a small torque. It is another object of the present invention to provide a method of manufacturing a photographic film cassette having treated light-trapping members which prevents ambient light invasion and generation of dirt particles. These needs are fullfilled by the method according to claim 1. According to the present invention, first, light-trapping members are attached to the upper and lower surfaces of a film passageway which is defined in a port portion of a cassette shell so that the tips of piles of the light-trapping members are overlapped each other at a predetermined depth. Next, the cassette shell with the light-trapping members and the spool with the photographic film wound thereon are assembled to complete the photographic film cassette. After the assembly, as a first alternative step, a leading end of the photographic film is once advanced through a film passageway out of a film passage mouth by rotation of the spool. Then, the spool is rotated in a winding direction so as to wind the leading end of the film again into the inside of the cassette shell. As a result, the tips of the piles of the light-trapping members are arranged so as to press against each other relative to the film moving direction. As a second alternative step, after the assembly, a sheet member is inserted from the film passage mouth into the film passageway and thereafter pulled out therefrom so that the tips of the piles of the light-trapping members are arranged so as to press against each other relative to the film advancing direction. According to the present invention, it is possible to perform arrangement of the piles with an easy operation so that the leading end of the film is advanced out of the cassette shell with a small torgue, keeping a sufficient light-trapping function. The above objects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments when read in connection with the accompanying drawings, in which: Fig. 1 is a cross section of a photographic film cassette with light-trapping members according to an example 1 of the present invention; Fig. 2 illustrates a weave of the light-trapping members; Fig. 3 is an enlarged cross section illustrating the state of the light-trapping members before a leading end of a photographic film is passed through a film passageway; Fig. 4 illustrates the shape of the leading end of the photographic film; Fig. 5 is a graph illustrating the relationship between a value X and a film advancing torque; Fig. 6 is an enlarged cross section illustrating the state of the light-trapping members after the photographic film was passed in the film passageway; Fig. 7 illustrates a weave of light-trapping members according to an example 2 of the present invention; Fig. 8 is a perspective view of a sheet member with holes on its one end according to an example 3 of the present invention which is inserted into and drawn from the film passageway; Fig. 9 is an enlarged view of the film passageway into which the sheet member is inserted; Fig. 10 is an enlaged view of the film passageway after the sheet member is drawn; Fig. 11 is a perspective view of a sheet member with an corrugated end; Fig. 12 is a perspective view of a sheet member with fillings on both surfaces of its one end; and Fig. 13 is a perspective view of a sheet member with double-coated adhesive tapes attached on both surfaces of its one end. Referring to Fig. 1, a photographic film cassette 3 comprises a cassette shell 7 constituted of shell halves 7a and 7b and a spool 6 with a photographic film 5 wound thereon. Annular ridges 8 and 9 are provided on the inner circumferential surfaces of the shell halves 7a and 7b to prevent a photographic film 5 from loosening. A separation claw 8a is formed on the end of the ridge 8 for separating a leading end 5a of the photographic film 5 from the outermost turn of the rolled photographic film 5. The respective shell halves 7a and 7b have channel-like port portions 10a and 10b. When the shell halves 7a and 7b are integrated, a film passageway 4 is formed by the port portions 10a and 10b. Light-trapping members 2a and 2b are attached to the inside surfaces of the port portions 10a and 10b by an adhesive. A trailing end of the photographic film 5 is secured to the spool 6 and a leading end 5a is cut in a shape illustrated in Fig. 4, in which angles  1 and  2 are e.g., 45° and 30° respectively. The shell halves 7a and 7b and the spool 6 are molded of plastic. The light-trapping members 2a and 2b are attached to the shell halves 7a and 7b. After the spool 6 with the photographic film 5 wound thereon is contained between the shell halves 7a and 7b, the shell halves 7a and 7b are attached to each other by the ultrasonic welding. Several examples and comparative examples will be raised to describe the present invention in detail hereinafter. Example 1 A velvet fabric was woven by a needle loom, having a weave construction as illustrated in Fig. 2, in which hatched cells show that warp threads overlie weft threads and blank cells show that weft threads overlie warp threads. Cross-hached cells show that pile threads float over the weft threads. Each pile thread is inlaid in the vertical direction so that roops are formed between adjacent cells. In Fig. 2, only two pile threads P 1 and P 2 are illustrated and each loop of the pile threads P 1 and P 2 is cut at its center. A nylon thread of 11,11 tex (100 denier) consisting of 48 filaments was used for pile threads. Two twisted antistatic nylon threads of 5,56 tex (50 denier)/10 filaments were used for warp threads while an antistatic nylon thread of 8,33 tex (75 denier)/24 filaments was used for weft threads. The woven velvet fabric was dyed with an acid dye and dried while being blushed so that piles of the velvet fabric were raised approximately perpendicularly. The velvet fabric was then cut by a predetermined size so as to obtain the light-trapping members 2a and 2b. When attaching the light-trapping members 2a and 2b to the inside surfaces of the port portions 10a and 10b, there was used a hot-melt adhesive mixed with a sticky type adhesive which has stickness somewhat at room temperature. Just after the attachment, the piles P of the light-trapping members 2a and 2b were entangled alternately with each other, as illustrated in Fig. 3. The SUPER HG 400 film (trade name: Fuji Photo Film Co., Ltd.) was used as a photographic film 5. As described above, the spool 6 with the photographic film 5 wound on is interposed between the shell halves 7a and 7b, which are then adhered to form the photographic film cassette 3. A height H of the film passage mouth 11 was 2.3 mm. A thickness of the light-trapping members 2a and 2b which was measured by the Peacock thickness meter under a load of 5 g/cm 2 was 1.7 mm. At this time, a value X representing the collapsed amount of the pile threads P of each of the light-trapping members 2a and 2b was 0.55 mm. As illustrated in Fig. 5, when the value X becomes smaller, an advancing torque becomes larger, since the pile threads P tend to easily return to the initial alternately entangled condition. On the contrary, when the value X becomes larger under the condition that the thickness of the light-trapping members 2a and 2b is in a range from 1 mm to 3 mm, the advancing torque becomes rapidly larger at the value X of 1.20 mm or more. Accordingly, it is preferable to set the value X in a range from 0.3 mm to 1.2 mm. It is noted that the results of Fig. 5 were obtained in the following manner. The leading end 5a of the photographic film 5 contained in the cassette shell 7 was once propelled through the film passage mouth 11 out of the cassette shell 7, and thereafter again contained therein. Then, the photographic film cassette 3 was vibrated under 10 Hz, and subjected to measurement. The spool 6 of the photographic film cassette 3 was coupled with a shaft of a film winding device (not illustrated) having a large torque so as to rotate the spool 6 in a direction indicated by an arrow in Fig. 1 thereby to cause the leading end 5a of the photographic film 5 to exit through the film passageway 4 and the film passage mouth 11 to the outside of the cassette shell 7. Thereafter, the spool 6 was rotated in the opposite direction to wind the film 5 again and contain it up to the leading end 5a inside the cassette shell 7. As a result, the condition of the pile threads P changed from Fig. 3 wherein the respective pile threads P of the light-trapping members 2a and 2b are entangled alternately to Fig. 6 wherein the respective tips of the pile threads P push against each other to incline in the film moving direction. When the leading end 5a of the photographic film 5 advances through the film passageway 4, it pushes pile threads extending in the opposite direction to the film advancing direction toward the film width direction by the inclined edges of the leading end 5a. Therefore, the pile threads extending in the opposite direction will not hinder the advancement of the leading end 5a. Example 2 A web was formed of a velvet fabric which was woven by a needle loom so as to have a weave construction as illustrated in Fig. 7. The pile, warp and weft threads of the light-trapping members 2a and 2b were a nylon thread of 11,11 tex (100 denier)/40 filaments, a rayon thread of 16,67 tex (150 denier)/24 filaments and a rayon thread of 13,33 tex (120 denier)/20 filaments respectively. The thickness of the light-trapping members 2a and 2b, the mouth height H and the value X were 1.8 mm, 2.3mm and 0.65 mm respectively. The web was dyed, then dried while being blushed and cut at the predetermined size to obtain the light-trapping members 2a and 2b in the same manner as in the Example 1. The obtained light-trapping members 2a and 2b were adhered to the shell halves 7a and 7b, which was then integrated to form the photographic film cassette 3. Thereafter, the pile threads were arranged by the unwinding and winding operations of the photographic film 5. Example 3 Similarly to the Example 1, the photographic film cassette 3 as shown in Fig. 1 was assembled. Next, a sheet member 13 was inserted from the film passage mouth 11 into the film passageway 4 as illustrated in Fig. 9 and drawn out therefrom. An end of the sheet member 13 was formed with holes 13a to 13c for catching the pile threads P. The drawing of the sheet member 13 from the film passage mouth 11 causes the pile threads P of the light-trapping members 2a and 2b to be inclined toward the outside of the film passage mouth 11. In place of the sheet member 13, there may be used sheet members as illustrated in Figs. 11 to 13. In Fig. 11, an end of a sheet member 14 has corrugations 14a so as to drag the pile threads P toward the film passage mouth 11. A sheet member 15 of Fig. 12 has fillings on both surfaces of its one end of a base 15a. A sheet member 17 of Fig. 13 has double-coated adhesive tapes 16 attached to both surfaces of its one end. The pile threads P are touched by the sticky surfaces of the adhesive tapes during the drawing of the sheet member 17 and inclined toward the film passage mouth 11. Comparative Example 1 The light-trapping members 2a and 2b the same as in the Example 1 were attached to a photographic film cassette having a mouth height of 2.6 mm. The thickness of the light-trapping members 2a and 2b and the value X were 1.7 mm and 0.4 mm respectively. The leading end 5a of the photographic film 5 was not once projected out of the photographic film cassette. The arrangement condition of the pile threads P was the same as in Fig. 3. Comparative Example 2 A photographic film cassette was the same structure as in the Example 1. However, the leading end 5a of the photographic film 5 contained in the film cassette was not once projected out of the photographic film cassette. In each photographic film cassette of the Examples 1 to 3 and the Comparative Examples 1 to 2, an advancing torque was measured as shown in Table 1 when advancing the leading end 5a of the film 5 through the film passage mouth 11 out of the cassette shell 7 by rotation of the spool 6. An advancing torque after giving vibrations to each photographic film cassette under 10 Hz for one hour was also measured. As apparent in the Table 1, the respective advancing torques of the Examples 1 to 3 were small and were little increased even when measured after giving vibrations. Besides, entanglement and twist of the pile threads P were not observed after the vibrations. On the contrary, in the Comparative Examples 1 and 2, the advancing torques were high. Therefore, it is expected that the leading end 5a could not be propelled through the film passage mouth 11 out of the cassette shell 7 in a camera with a drive shaft having a small advancing torque or with decreased electric power. In order to perform the initial advancement of the leading end 5a of the photographic film 5 to the outside of the cassette shell 7 in a camera smoothly and securely, it is necessary to limit the advancing torque. For this reason, it is necessary to conduct the testing of the advancing torque for the photographic film cassette 3 after assembling. This testing process can be combined with the process of the Example 1 for arranging the piles of the light-trapping members. At this time, it is preferable to repeat the advancement of the leading end 5a of the photographic film 5 through the film passageway 4 out of the cassette shell 7 twice in order to measure the advancing torque at the second time since the advancing torque is stabilized at the second time. Therefore, the exact arrangement control is performed at the second time. Besides, if a lubricant such as silicon is applied to the pile areas, a friction coefficient between the pile threads of the light-trapping members 2 can be lowered to reduce the advancing torque at the first time. Although the present invention has been described as above with reference to the accompanying drawings, various changes and modifications will be apparent to those having skill in this field. Therefore, unless otherwise these changes and modifications depart from the scope of the present invention, they should be construed as included therein.

Claims: A method of manufacturing a photographic film cassette (3) including a cassette shell (7), a spool (6) and a photographic film (5) wound on said spool (6), a leading end (5a) of said photographic film (5) being adapted to be propelled through a film passageway (4) formed in said cassette shell (7) out of said cassette shell (7) by rotation of said spool (6), said method comprising the steps of: attaching light-trapping members (2a,2b) to upper and lower surfaces of said film passageway (4), said lighttrapping members (2a,2b) having piles (P); and assembling said cassette shell (7) with said light-trapping members (2a,2b) to contain said spool (6) with said photographic film (5) wound thereon, tips of said piles (P) overlapping each other at a predetermined depth (X); characterised by the step of: treating said two light-trapping members (2a,2b), after the assembly of said cassette (3) and before advancing said film (5) for exposure, for arranging the tips of said piles (P) so as to push against each other with the tips inclined in the moving direction of the film (5) when advanced out of the cassette shell (7) for exposure by advancing and retracting the leading end (5a) of the film (5) into and from said film passageway (4) or advancing a sheet member (13,14,15,17) into and out of said film passageway (4) of said cassette shell (7). A method as defined in claim 1, wherein said cassette shell (7) consists of two shell halves (7a,7b). A method as defined in claim 1 or 2, wherein the leading end (5a) of said photographic film (5) is cut in a V-shape, so that the leading end (5a) of said photographic film (5) disperses piles (P) inclined toward the inside of said cassette shell (7) into a film width direction when advancing said photographic film (5) out of said cassette shell (7). A method as defined in any one of claims 1 to 3, wherein said treating step is performed by advancing and retracting the leading end (5a) by rotation of said spool (6). A method as defined in any one of claims 1 to 3, wherein one end of said sheet member (13) has a plurality of holes (13a,13b) for catching said piles (P). A method as defined in any one of claims 1 to 3, wherein one end of said sheet member (14) is corruaated (at 14a) so that said piles (P) are dragged. A method as defined in any one of claims 1 to 3, wherein said sheet member (15) has fillings (15b) on both surfaces of its one end for catching said piles (P). A method as defined in any one of claims 1 to 3, wherein said sheet member (17) has double-coated adhesive tapes (16) which are attached to both surfaces of one end thereof so as to catch said piles (P). A method as defined in any one of claims 1 to 8, wherein said light-trapping members (2a,2b) are a velvet fabric. A method as defined in any one of claims 1 to 9, wherein a lubricant is applied to said piles (P) of said light-trapping members (2a,2b) so as to decrease friction coefficients between said light-trapping members (2a,2b) and both surfaces of said photographic film (5).

Inventors: MIZUNO KAZUNORI, MIZUNO, KAZUNORI, MIZUNO, KAZUNORI, C/O FUJI PHOTO FILM CO., LTD.
Applicants: FUJI PHOTO FILM CO LTD, FUJI PHOTO FILM CO., LTD.
Application year: 1992
Main classification: G03B17
IPC codes: G03C3, G03B17, D03D27, D03D1