1. Field of the Invention
The present invention relates to a cutter for cutting continuous paper with one portion thereof uncut and a thermal printer having the above cutter.
2. Description of the Related Art
There is known a paper cuter for cutting a roll of continuous paper having been printed on with one portion left uncut. Such devices have been installed in, for example, an order input device and the like for printing out menu items ordered by a customer in a fast food restaurant, a family restaurant, and the like. Hereafter, this type of cut is referred to as a partial cut.
The partial cut is used for various purposes, such as for preventing full cut paper from falling down into the device from the outlet, or for aligning several sheets of paper with the contents of orders printed in a sequence of orders while being connected by one portion, by supplying the paper without tearing off the uncut portion according to the partial cut when receiving the orders sequentially, and the like.
Generally, the paper appearing from the outlet after a partial cut is divided into individual sheets by a user's pulling the paper and tearing off the uncut portion. In case of a partial cut in which an uncut portion of the paper is left on the right side, when a user pulls the paper, holding the left side of the paper, the cut portion of the paper is opened and a force concentrates on the root, thereby making it easy to tear off the uncut portion.
However, when a user pulls the paper straight while holding the side of the uncut portion of the paper, even if the width of the uncut portion is small, a force is dispersed in this portion, and therefore, in some cases, the uncut portion cannot be torn off easily even if a user pulls on it forcefully. When this occurs, there is also a possibility of reeling out the connected paper from the device. When the paper is reeled out, various problems may occur, including an increase the space on the top of the paper at the next print-out operation and the possibility that the paper will be skewed swayed at a forwarding time.
Generally, a thermal printer clamps paper between a printing head and a platen for printing, and these components are provided in a prior stage of the cutter for performing the partial cut, such that the paper is being held by the pressure of the printing head and the platen while being cut. When the paper is pulled in a state of being uncut with a force stronger than this clamping force, the paper will be reeled out. Recently, however, there has been a tendency for the pressure between the printing head and the platen to become lower, and therefore, the problem of reeling out the paper by pulling the partial cut paper has become more serious.
An object of the present invention is to provide a paper cutter and a thermal printer which enables a user to tear off the paper easily and prevent reeling out of the paper from the device, even when a user pulls the partial cut paper straightly by the uncut portion.
In order to achieve the above object, the invention provides a paper cutter having a guide for guiding continuous paper and cutting means for cutting the continuous paper passing through the guide with one portion thereof left uncut, wherein the guide is provided with resistance adding means for adding a resistance to the continuous paper when a tensile force works on the continuous paper passing through the guide.
By the foregoing structure, even if the paper is pulled in a state in which it is difficult to tear, the resistance adding means can add a resistance to the paper, thereby tearing off the paper easily. This can prevent reeling out of the paper.
More specifically, the resistance adding means may be provided in a position corresponding to an uncut portion of the continuous paper left behind without being cut by the cutting means. This structure can add a resistance to the uncut portion of the paper efficiently, and by providing the above means only in a peripheral portion for passing the uncut portion, it is possible to prevent the paper from clogging (paper jam) due to obstructing the passage of the paper in the guide.
The resistance adding means may be formed by a plurality of projections for bending the continuous paper in contact with the both surfaces of the continuous paper passing through the guide. According to this structure, there is not much resistance imparted when the paper simply passes straight through the guide, and only when the paper is pulled and stretched straightly, resistance is added to the paper. Further, the above means can advantageously be formed at a low cost.
More specifically, two projections may be provided, one being provided facing one surface of the continuous paper and the other being provided facing the other surface thereof, the respective projections being formed in a shape having such an inclination that a protruding degree is small on a side of an inlet of the guide and large on a side of an outlet of the guide. According to this structure, the projections do not obstruct the passage of the paper along the guide by are formed with the optimum structure to obtain a suitable resistance when pulling of the paper occurs.
The inventive paper cutter is especially useful when adopted in a thermal printer comprising a printing device for printing by clamping continuous paper between a printing head having a plurality of heating elements for dot printing and a platen and a paper feed mechanism for feeding the continuous paper while rotating the platen, and the paper cutter for cutting the continuous paper fed from the printing device to the guide.
For a better understanding of the present invention, reference is made of a detailed description to be read in conjunction with the accompanying drawings, in which:
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The thermal printer 1 of the embodiment is comprised of a printing mechanism 10 for printing on continuous paper such as roll paper, and a cutter 20 for partially cutting the continuous paper fed from the printing mechanism 10.
The printing mechanism 10 performs printing while urging the continuous paper between a printing head 11 and a platen 12, as illustrated in
The cutter 20 comprises a guide 21 for introducing the paper discharged from a space between the printing head 11 and the platen 12, to a cutting position, and a fixed blade 24 and a movable blade 25 for clipping and cutting the paper passing through the guide 21. The guide 21 is designed to surround both surfaces of the paper by its two walls, which are wider than the paper, and keep into contact with the both sides of the paper by its right and left convex pieces 21a, 21a so as not to sway the paper. Further, the passage length of the guide 21 is fairly short (for example, 6 to 10 mm). Along the guide 21, two projections 2a and 2b are provided as resistance adding means for adding a resistance to the paper when the paper is pulled from the outside.
The movable blade 25 and the fixed blade 24 constitute a cutting tool and are respectively as least as long as the width of the paper or a little longer than that. The movable blade 25 moves back and forth in the direction indicated by the arrow A in
The fixed blade 24 is arranged so as not to overlap the right end portion of the paper passage and, as a result of this arrangement, the right end portion of the paper remains as it is without being cut. Namely, the range L1 from the right end portion of the fixed blade 24 to the convex piece 21a on the right side of the guide 21 is served to leave the paper behind as an uncut portion.
Two projections 2a and 2b are provided in the guide 21 upstream of the cutting tool and are provided at a position corresponding to the portion having an uncut portion of the paper left behind in the horizontal direction (direction of the width of the paper), as illustrated in
In this embodiment, the two projections 2a and 2b are designed to have an inclination such that a protruding degree can be relatively smaller on the side of the inlet of the guide 21 and relatively larger on the side of the outlet thereof (inclined about 30° to the wall surface of the guide 21) and that the sum of the maximum protruding degrees (widths) c of the guide 21 (a+b>c).
The inclination provided in the two projections 2a and 2b makes it easy to pass the paper R when the paper R is forwarded from the printing mechanism 10, and as illustrated in
Further, in the lower projection 2b, the edge portion E of the maximum protruding degree is cut off like an arc, so that the contact area of this edge portion E and the paper can become larger in a state of pulling the paper R.
According to the above paper cutter 20, the paper is discharged out with the uncut portion left behind in one portion on the right side of the paper, according to the partial cut of the cutter 20. When the paper is straightly pulled by the uncut portion in a state of being discharged, the tightly stretched paper is bent in shape of an S against the two projections 2a and 2b, in the lower portion of the uncut portion of the paper, and a frictional drag is generated in the edge portion of these two projections 2a and 2b.
Namely, the maximum static friction obtained when pulling the paper from the outside is the sum of the static friction f0 in the pressing portion of the platen 12 and the printing head 11 and the static friction (f1+f2) in the edge portions of the two projections 2a and 2b.
Accordingly, even when the paper is pulled in a state incapable of tearing off the uncut portion easily, since the static friction becomes larger compared with the guide without the projections 2a and 2b, it becomes easier to tear off the uncut portion of the paper, and therefore, occurrence of a disadvantage of reeling out the paper from the device can be restrained.
Further, when a tensile force F1 capable of straightly pulling and tearing off the uncut portion of the paper is a little beyond the static friction f0 of the pressing portion of the platen 12 and the printing head 11, the total of the static friction can be larger than the tensile force F1 by adding the static friction of the projections 2a and 2b (f1+f2). Thus, the uncut portion of the paper never fails to be torn off before reeling out the paper.
As the resistance adding means, three projections may be provided in the guide 21, as illustrated in
When the maximum protruding degrees of the projections 2e, 2f, and 2g are respectively defined as e, f, and g and the width of the interstice between the both walls of the guide 21 is defined as c, the maximum protruding degrees of the three projections 2e, 2f, and 2g are formed in a way of satisfying the relationship (c<e+f) and (c<f+g). Further, the maximum protruding degree of the upper projection 2e is formed smaller than the lower projection 2g (e<g), so as not to disturb the discharge and the cutting processing of the paper R.
Namely, the lower projection 2g and the middle projection 2f may be formed to have such a protruding degree as to prevent a paper jam (paper clogging) and obtain a desired friction drag, and the upper projection 2e may be formed to have such a protruding degree so as not to cause the paper jam and disturb a cut of the paper. The respective projections 2e to 2g may be formed in any shape as long as they can obtain a desired friction drag and they do not disturb the passage of the paper.
The invention is not restricted to the above embodiments, but various modifications are possible. For example, the following modification can be considered as the resistance adding means for adding a resistance to the paper when the paper is pulled from the outside.
In this embodiment, as the resistance adding means, a movable projection 2c installed in a vertically movable state and a fixedly installed projection 2a are provided on the side walls of the guide 21. When the paper R is forwarded upwardly according to the rotation of the platen 12, the movable projection 2c is positioned at the lower portion by a weak spring force since no strong force works on the paper R, so to pass the paper R through the guide 21 (
A guide groove 3 may be provided on the side wall of the guide 21 for guiding movement of the movable projection 2c, and an engagement portion 4 may be provided on the side portion of the movable projection 2c to slidably engage the engagement portion 4 in the guide groove 3 in a vertically movable way. When a printer at use stands like that shown in
In this embodiment, as the resistance adding means, a rotary member 2d rotatable around a supporting point 5 in an elbowed shape and a fixedly installed projection 2a are provided on the side walls of the guide 21. When the paper R is forwarded upwardly according to the rotation of the platen 12, the paper R moves easily through the guide 21 since a strong force is not applied on a lower arm of the rotary member 2d (
Moreover, the resistance adding means may be formed to add a resistance to the paper by pushing the paper by an electric drive from the end of the cutting processing to the beginning of the next printing processing, or even in the case of providing a projection in the guide, the shape and the number of the projections is not restricted to the above-mentioned embodiments, but various modifications are possible.
In the embodiments, although the description has been made by way of example of the paper cutter of the type of cutting the paper by pinching it between the movable blade moving back and forth and the fixed blade, the invention can be adopted to a cutter of any type including a rotary cutter for cutting the paper while moving a rotary blade along the width direction of the paper and the like.
As set forth hereinabove, according to the invention, the resistance adding means adds a resistance to the paper, which makes it easy to tear off the paper, and therefore, it is effective in preventing reeling out of the paper.
Since the resistance adding means is formed by two projections for bending the passage of the continuous paper while making contact with the both surfaces of the continuous paper and these projections are tapered, nothing obstructs the passage of the paper along the guide and the optimum quality can be obtained such that a proper resistance is added to the paper when pulling the paper.
Number | Date | Country | Kind |
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2002-062144 | Mar 2002 | JP | national |
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Number | Date | Country | |
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20030172792 A1 | Sep 2003 | US |