Photography – Camera detail – Detachable or removable film holder unit
Reexamination Certificate
1999-09-09
2001-02-13
Rutledge, D. (Department: 2851)
Photography
Camera detail
Detachable or removable film holder unit
C396S583000
Reexamination Certificate
active
06186680
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a self-developing photo film unit. More particularly, the present invention relates to a self-developing photo film unit in which a trap member is reliably capable of capturing a surplus part of developing solution without enlarging a size of a portion wrapping the trap member.
2. Description Related to the Prior Art
There is a mono-sheet type of self-developing photo film unit for use with an instant camera. The photo film unit is constituted by a combination of a photosensitive sheet, a mask sheet, a cover sheet and the like. After the photosensitive sheet is exposed, a developing solution pod is squeezed and torn by spreader rollers of the instant camera. Developing solution, contained in the developing solution pod, is spread between the photosensitive sheet and the cover sheet. There occurs a surplus part of the developing solution in a small amount. The surplus developing solution remains in a bendback edge portion of the mask sheet. A trap member is enveloped in the bendback edge portion, and traps or captures the surplus developing solution.
There are various examples of photo film units different in size, including Photorama Film (trade name) manufactured by Fuji Photo Film Co., Ltd. with a size of 97×102 mm, Joycam Film (trade name) manufactured by Polaroid Corporation with a size of 64×111 mm, and Xiao Film (trade name) manufactured by Polaroid Corporation with a size of 30×160 mm.
Recently there has been an idea of reducing the overall size of the photo film unit in consideration of reduction of the size of an instant camera. At the same time, a frame size of the photo film unit should be kept sufficiently large. Thus it is desired to reduce a width of the bendback edge portion containing the trap member. In the course of taking an instant photograph, the surplus developing solution is absorbed immediately after the developing solution is spread. The developing solution exists in the vicinity of the trap member in a temporary manner with high fluidity. Swelling of the trap member requires comparatively much time. If a user manually grasps the trap member immediately after the development, the surplus developing solution is very likely to flow out of gas vents or air holes.
Although the above-mentioned various sizes exist for the photo film units, there is no known photo film unit easy to be handled for preservation after taking an exposure. To facilitate the handling, the size of the photo film unit should be reduced further. However excessive smallness of a photo film unit causes reduction of the frame size. If a number of people are photographed in a single frame, it is likely that faces of those people cannot be recognized clearly by viewers.
SUMMARY OF THE INVENTION
In view of the foregoing problems, an object of the present invention is to provide a self-developing photo film unit in which a trap member can trap surplus developing solution without enlarging a bendback edge portion wrapping the trap member.
Another object of the present invention is to provide a self-developing photo film unit which is easy to be handled after being exposed and also with a sufficiently large frame size.
In order to achieve the above and other objects and advantages of this invention, a self-developing photo film unit has a photosensitive sheet, first and second spacer rail members, a cover sheet, a mask sheet, a developing solution pod, and a strip-shaped trap member. The mask sheet has a mask portion and first and second bendback edge portions defined by being bent along first and second bend lines. The mask portion has an aperture. The developing solution pod contains developing solution and is squeezed and enclosed between the first bendback edge portion and the mask portion. After the photosensitive sheet is provided with an exposure, the developing solution is spread from the developing solution pod between the photosensitive sheet and the cover sheet while being regulated between the first and second spacer rail members. The trap member is squeezed and enclosed between the second bendback edge portion and the mask portion, and captures surplus part of the developing solution after the developing solution is spread. In the self-developing photo film unit, the trap member comprises non-woven fabric having a porosity of 70% or more, including acid polymer impregnated therein, and having first and second surfaces. The first surface is opposed to the second bendback edge portion, and has the acid polymer impregnated more than the second surface. A securing region is disposed along one of two longer side lines of the trap member nearer to the aperture, coated with adhesive agent, for securing the trap member to the second bendback edge portion.
By the construction with the porosity of 70% or more, the surplus developing solution can be reliably trapped. By the acid polymer impregnated in the non-woven fabric, spaces between fibres in the fabric can be reduced so as to prevent the surplus developing solution from passing out of the trap member. As the acid polymer is impregnated more in the first surface than in the second surface, the second surface can be provided larger spaces between fibres so as to ensure trapping of the surplus developing solution. Also the first surface can be provided with smaller spaces between fibres so as to block passage of surplus developing solution out of the trap member. By the securing region of the trap member secured to the second bendback edge portion, the surplus developing solution is prevented from leaking out of gas vents or air holes of the photo film unit.
In a preferred embodiment, the second surface has a rougher texture than the first surface.
The self-developing photo film unit has a size of an ID-1 type card according to an external size of length varying from approximately 85.6 mm to 125 mm, height of approximately 53.98 mm to 88.0 mm, and thickness of approximately 0.76 mm, and a ratio of an area of the aperture to an area of a margin portion defined outside the aperture is 1.4 or more.
By this construction, the photo film unit is easy to be handled after being exposed and also with a sufficiently large frame size.
The adhesive agent is pressure-sensitive adhesive agent.
According to one aspect of the present invention, the trap member comprises non-woven fabric having porosity of 70% or more, including acid polymer impregnated therein, being produced by a wet process, and including fibres, and the fibres including 3-20 wt. % of pulp.
The fibres further include an ester type of fibres.
By the inclusion of 3-20 wt. % of the pulp, it is possible in the course of the wet process to keep moisture effectively and avoid dewatering and failure in the production of the non-woven fabric.
According to another aspect of the present invention, a hot-melt adhesive layer is overlaid on an inner surface of the second bendback edge portion opposed to the trap member. A single heat sealing region is disposed along one of two longer side lines of the trap member nearer to the aperture, and secured to the second bendback edge portion by application of heat and pressure to the hot-melt adhesive layer through the second bendback edge portion.
By the single heat sealing region of the trap member secured to the second bendback edge portion, the surplus developing solution is prevented from leaking out of gas vents or air holes of the photo film unit.
According to still another aspect of the present invention, the second bendback edge portion includes a first edge, the trap member being disposed between the first edge and the second bend line, the first edge being secured to the cover sheet. The photosensitive sheet and the second bendback edge portion satisfy a condition of:
0.5 mm≦
D
1
−D
3
≦0.8 mm
where D
3
is a distance from the second bend line to the first edge, and D
1
is a distance from the photosensitive sheet to the first edge while the second bendback edge portion is substantially straightened from the mask portion.
By the
Fuji Photo Film Co. , Ltd.
Rutledge D.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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