Cutlery – Cutting tools – With guard and/or guide
Patent
1997-01-28
1998-09-22
Payer, Hwei-Siu
Cutlery
Cutting tools
With guard and/or guide
30289, B43M 700
Patent
active
058096566
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a paper knife applicable as an envelope opener by means of which the envelope-closing fold is most conveniently opened.
BACKGROUND OF THE INVENTION
Previously known, from publication No. WO 9004525 , is a paper knife, the blade of which is protected in the body so that it cannot unintendenly hurt the user. The blade has a tip part, whose entering the envelope-closing fold is made still better by means of special flexible fingers.
The disadvantage of such an opening knife is that the user does not see whether the knife blade gets into the fold or not, as the device must always be held with the right side up in the hand upon cutting and the constructional length of the device is too short to attain a proper course in the cutting direction between device and envelope.
SUMMARY OF THE INVENTION
By means of a paper knife according to this invention a decisive improvement of the above presented disadvantages is reached.
The most significant advantage of this invention is that the material of the body walls, which protect the blade and the envelope fold, is transparent, whereat the blade and especially the location of its tip are visible when the blade tip is, at first, placed in the beginning of the fold. By means of a hole in the body, also a similar property is achieved. The constructional length of the knife is sufficient for an ergonomic grip and the fold can lean against the guiding surfaces of the knife and thus retain its cutting direction. The blades still remain well protected and so no involuntary damages can occur.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following the invention is presented in detail with reference to the enclossed drawing, where:
FIG. 1 is a longitudinal side section of the paperknife taken along the section line in FIG. 3;
FIG. 2 is the paperknife viewed from the blade side;
FIG. 3 is the paperknife viewed from one end; and
FIG. 4 is an alternative embodiment of the blade.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a paperknife with a longitudinal body, both ends of which are symmetric and furnished with sharpened blade portions 3. At both blade ends there are, side by side, body walls 6, which are better illustrated in the end view and in FIG. 2. Body walls 6 are at a suitable distance from each other for easy application of the envelope fold or, in most cases, the upper envelope edge between them. Anyhow, the distance is so small that there is not space enough to put a finger into it. Blade portion 3 with tip 2 are arranged between body walls 6 so that no portion of them reaches the upper level of body walls 6. Blade 1 is, as a whole, a symmetric double-blade. When at least the body walls 6 are made of transparent plastic or glass, tip 2 of blade portion 3 can be seen through these walls and tip 2 can be put accurately in the envelope from the start of fold and cutting can be started. Most conveniently, the tip 2 of blade portion 3 is flat and rounded and so it does neither penetrate the fold nor stick out through the fold while cutting. Still it is so sharp that at the end of cutting it breaks itself easily out through the envelope side fold. Cutting can be continued with the knife by cutting also the sidefold, whereby the tip 2 of the paperknife is turned into the sidefold from a suitable spot at the end of the closing fold. Dotted lines in FIG. 1 show a possible hole 12 in part 6 presenting an alternative for transparency. Through the hole it is possible to make same observations.
Blade tip 2 is most conveniently sharpened flat to enable an easy push under the folded envelope-closing flap. Mostly, the extreme ends of these flaps have no layer of glue and so the blade tip 2 can be pushed in. Generally, the sharpened blade portion 3 of blade 1 does not at this instant cut the fold open. This is because the direction of blade portion 3 is substantially the same as the direction of the fold, i.e. the cutting direction. Blade portion 3 comes to its end and the direction of blade 1 changes in the sharpened blade
REFERENCES:
patent: 436189 (1890-09-01), Prosinger
patent: 844770 (1907-02-01), Bauer
patent: 2255945 (1941-09-01), Shuler
patent: 2442694 (1948-06-01), Keiser
patent: 2610399 (1952-09-01), Adams et al.
patent: 3383768 (1968-05-01), Hamilton
patent: 3824688 (1974-07-01), Goffe
patent: 4455894 (1984-06-01), Roberts
patent: 5561905 (1996-10-01), Sherman
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