PAPER KNIFE

Abstract: A knife for cutting a fold in paper, especially designed for opening an envelope with the said knife, whereat at least one end of the knife comprises two adjacent body walls (6) with a blade (3) placed between them and guiding means (7, 10) in the body to guide the fold while cutting. At least, body walls (6) of the knife are made of transparent material or furnished with a control hole (12) to facilitate arrangement of tip (2) into starting position for cutting.

Description: PAPER KNIFE This invention relates to a paper knife applicable as an envelope opener by means of which the envelope-closing fold is most conveniently opened. Previously known, a.o. 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, 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. By means of a paper knife according to this invention a deci¬ sive improvement of the above presented disadvantages is reach-ed and the invention is characterized in what is disclosed in the patent claims. 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 especial¬ ly 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 nife is sufficient for an ergo- nomic 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. 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 Fig. 2 is the paperknife viewed from the blade side Fig. 3 is the paperknife viewed from one end Fig. 4 is an embodiment of the blade Figure 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 figure 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 dis¬ tance is so small that there is not space enough to put a finger into it. Blade 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 con¬ veniently, the tip of blade 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 he envelope side fold. Cutting can be continued with the knife by cutting also the sidefold, whereby the tip of knife is turned into the side- fold from a suitable spot at the end of the closing fold. Dotted lines in figure 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 portion 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 changes in the sharpened blade portion 5, which actually cuts the fold. In the spot, where blade portions 3,5 change direct¬ ion, there is a guiding body section 7 most closely to the blade, at a distance of appr. 0,5-1 mm in the spot 11. This ensures that cutting is started immediatelly with blade portion 5. In the same way, from now on the body wall departs immediately from the blade and forms an opening 8 at blade portion 5. The opening prevents blockings and ensures proper cutting. Blade tip 2 projects substantially farther to the end of knife than part 7. The rounded tip of part 7 works as a stopper and prevents the blade from from beeing pushed too deep in the envelope and easens also putting the blade under the folded flap restricting the blade range to the envelope surface. Below blade portion 3 there is also a sharpened bevelling 4 which helps to put blade tip 2 and the blade into starting position for cutting if the fold is glued up to the edge or almost to the edge. In addition, it facilitates the blade tip to penetrate the envelope wall at the final stage of cutting, whereby the the tip extrudes the side fold of the envelope when one does not want to cut the side fold. The metal blade 1 is fixed by some known means to body 9, for instance with glue, screws or it is put in the mould when the body is casted. Due to the double-blade construction of the knife, it is well fit for use both by right-handed and left- handed and still always in proper cutting position. In the body center there is a guiding section 10 against which the cut fold edges are gliding and the envelope keeps easily its direction during cutting. Figure 2 shows the knife viewed from one side of blade 1. In the right-hand end of the knife bevellings 13 are made to guide envelope surface towards the blade at the beginning of cutting, whereby it is easy to get the blade tip 2 under the flap in envelope. Figure 4 shows a simple embodiment of blade 14 without angle portion in its cutting edge. In addition to opening an envelope, the knife can be used to cut paper, the paper must, however, be folded at first along the cutting line. The knife body is well fit for printing of images and is therefore also ideal as a sales promotion gift. One end of the knife can be designed as a key-holder, bottle opener etc, if the symmetric form is not required.

Claims: PATENT CLAIMS 1. A knife for cutting a fold in paper, especially designed for opening an envelope with the said knife, whereat at least one end of the knife comprises two adjacent body walls (6)with a blade (3,14) placed between these walls and guiding means (7,10) in the body to guide the fold while cutting, charac¬ terized in that at least body parts(6) are made of transparent material or furnished with a control hole (12) to facilitate arrangement of tip (2) into starting position for cutting. 2. A knife according to patent claim 1 characterized in that the cutting blade is substantially comprised of a blade portion (3) in the fold direction and, as its extension, a blade portion (5) deviating 10 - 45° from the fold direction. 3. A knife according to patent claims 1 or 2 characterized in that the knife is substantially symmetric comprising blades in both ends. 4. A knife according to patent claims 1 or 2 characterized in that one end of the knife is designed as a bottle opener, key holder or similar.

Inventors: LINDBERG ARI, LINDBERG, ARI
Applicants: LINDBERG ARI, LINDBERG, ARI
Application year: 1995
Main classification: B43M7
IPC codes: B43M7