Photographic 120-size film roll

Details Photographic 120-size film roll Photographic 120-size film roll

1999-10-21

2001-03-06

Walsh, Donald P. (Department: 3653)

Winding, tensioning, or guiding

Wound storage package

Convolute coil

C242S348400, C396S512000

Reexamination Certificate

active

06196484

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a photographic 120-size film roll which is easily produced and highly protected from exposure to light.
BACKGROUND OF THE INVENTION
The well known 35 mm roll film is encased in a magazine and sold on market in that form. The encased 35 mm roll film is as such charged into a camera and exposed to light for every shooting. The encased 35 mm roll film is then taken out of the camera and processed in a darkroom to produce photographic images. Thus, the 35 mm roll film is highly protected from unintentional exposure to light in a magazine.
In contrast, a Brownie film of 120 size of 220 size is not encased in a magazine and is protected from exposure to light by a combination of a pair of light-shielding flanges equipped at both ends of a spool and a light-shielding backing or leader paper, respectively.
A typical structure of the photographic 120-size Brownie film roll is illustrated in
FIG. 1
in an extended form. A typical photographic 120-size film roll comprises a spool
13
which has a spool core
14
having a slit therein and a flange
15
at both ends of the spool core
14
and a photographic film
12
which is placed and fixed by an adhesive tape
21
on a continuous light-shielding backing paper
11
in which one end of the backing paper
11
is inserted into the slit of the spool core
14
and other portion of the backing paper
11
is would on the spool core
14
to form multiple convolutions. The outermost convolution of the backing paper
11
is fixed on its preceding convolution by a sealing tape
111
a
so that the photographic film
12
can be protected from exposure to light.
Although the photographic 120-size film is protected from exposure to light by a combination of a pair of the flanges and the light-shielding backing paper, it is liable to be exposed to light in its side area. The light sometimes enters through an unintentionally produced space or clearance between a side edge of the backing paper and a periphery of the flange to expose the side area of the photographic film.
In order to avoid the unintentional exposure of photographic film, the known backing paper is produced to have a width equal to or slightly larger than the distance between the two flanges of the spool. However, the use of a light-shielding backing paper having a width equal to or slightly larger than the distance between the two flanges sometimes disturbs smooth winding due to possible friction produced between the side edge of the backing paper and the inner surface of the flange. In that case, the photographic film roll wound on the spool core likely has a diameter or a height larger than the diameter or height of the flange. Thus formed photographic film roll is easily exposed to light when it is not placed within a light-shielding bag or a camera.
Japanese patent Provisional Publication No. H4-136842 describes a photographic film roll using a light-shielding backing paper which has a width (L
1
) satisfying the condition of (L
1
-L
2
)/L
1
=−1% −0.3% at
23° C., 50
% RH [L
2
is a distance between the two flanges] and which has one or two skived thinner side portions. The backing paper is adjusted to have a water content of 3 wt. % or less, wound on a spool, and made to have a water content of 4 to 9 wt. %. According to the description of the Publication, the backing paper has an increased width upon having the increased water content so that the side edges of the backing paper are brought into close contact with the inner surfaces of the flanges. Moreover, the skived side portion of the backing paper becomes more flexible to enable more close contact with the inner surface of the flange. For these reasons, a continuous photographic film is tightly wound on a spool and thus produced photographic film roll is highly protected from exposure to light. It seems that the disclosed photographic film roll is economically disadvantageous because an additional step for skiving the side portion(s) of the backing paper should be included in the preparation of the photographic film roll.
Japanese Patent Provisional Publication No. H9-288335 describes a photographic film roll in which a depression in the form of a ring is formed in a flange surface and a backing paper is adjusted to have a width larger than the distance between the two flanges by 50 to 100 &mgr;m. It is described that the wider backing paper is effective to keep the photographic film from exposure to light and the depressed flange assists smooth winding of the backing paper.
SUMMARY OF THE INVENTION
The present invention has an object to provide a photographic 120-size film roll which is easily produced and highly protected from exposure to light.
The invention resides in a photographic film roll comprising a spool which has a spool core having a slit therein and a flange at both ends of the spool core and a photographic 120-size film which is placed and fixed on a continuous light-shielding backing paper, in which one end of the backing paper is inserted into the slit of the spool core and other portion of the backing paper is wound on the spool core to form multiple convolutions, wherein the backing paper has at the center in its longitudinal direction a width less than the distance between the two flanges measured at the position of ½ of height of the flanges and has two wide areas of at least 10 cm long one of which is within 50 cm area measured from its one end and another of which is within 50 cm area measured from its another end, the width of each wide area being larger than the distance between the two flanges measured at the tops of the flanges.
In the photographic film roll of the invention, the width of each wide area of the backing paper preferably is larger than the width of the backing paper at the center by 0.02 to 0.2 mm, more preferably by 0.05 to 0.17 mm.


REFERENCES:
patent: 5049928 (1991-09-01), Tirone
patent: 5528326 (1996-06-01), Lawther
patent: 5845869 (1998-12-01), Makino
patent: 5855336 (1999-01-01), Inoue et al.
patent: 5934592 (1999-08-01), Makino
patent: 6022678 (2000-02-01), Makino
patent: 6048676 (2000-04-01), De Leener et al.

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