JP4607314B2 - Printer or ribbon cassette for printer - Google Patents

Description

[0001]
[Technical field to which the present invention pertains]
The present invention relates to a printer using a thermal method and a ribbon cassette for a printer.
[0002]
[Prior art]
FIG. 5 shows a schematic configuration of a transfer unit in a conventional ribbon cassette and printer. The ink ribbon R is drawn from the ribbon cassette 3 toward the thermal print head 2 via a rotatable ribbon guide roller (not shown). When the heating elements of the print head 2 are selectively heated based on print data from a control device (not shown), the ink is transferred to the recording medium P.
[0003]
The transferred ink ribbon R is accommodated in a cassette case via a rotatable ribbon guide roller 105. Ribbon guide rollers 105 provided before and after the print head provided in the ribbon cassette have a straight cylindrical shape as shown in the figure, and are fitted into a shaft 3 d protruding from the case of the ribbon cassette 3.
[0004]
[Problems to be solved by the invention]
An outline of the cause of the problem in the case of using a conventional ribbon cassette will be described. In a printer that uses a long print head and a wide ink ribbon such as a printer that prints on a plastic plate described in Japanese Patent Application Laid-Open No. 11-198478, the ink ribbon R is formed when printing close to the maximum width is performed. The meandering phenomenon was easy to occur.
[0005]
When this meandering becomes large, the ink ribbon R may fall off from the heat generating part of the print head 2 as shown in the X part in the figure, and the image may be lost. Further, if the center portion of the ribbon guide roller bends in addition to the meandering of the ink ribbon, wrinkles may occur and an image may be lost as shown by a Y portion in the figure. Furthermore, when the end portion of the ink ribbon R falls off from the end portion of the ribbon guide roller 105 as indicated by the Z portion in the drawing, the end portion may come into contact with the cassette case and lead to cutting. The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent ink ribbon conveyance failure and provide a high-quality image.
[0006]
[Means for Solving the Problems]
In order to achieve the above-described object, a printer according to the present invention is a printer that forms an image by sandwiching and transporting a printing medium and an ink ribbon between a print head using a thermal method and a platen roller. The outer diameter of the central part of the ribbon guide roller provided before and after the supply is D, the outer diameters of both ends are d1 and d2, the print guarantee area width of the print head is WH, the width of the ink ribbon is WR, and the ribbon guide roller center. When the length of the external part D of the LC is LC,
D> d1 = d2,
WR>LC> WH
It is characterized by the following relationship.
Further, when the total length of the ribbon guide roller is LA and the lengths of the outer diameters d1 and d2 of the ribbon guide roller end portions are L1 and L2,
LA> (LC + L1) = (LC + L2)>WR>LC> WH
It is characterized by becoming.
[0007]
The ribbon cassette for a printer of the present invention is mounted on a printer for forming an image by sandwiching and transporting a printing medium and an ink ribbon between a print head using a thermal method and a platen roller, and supplying the ink ribbon of the print head. In a ribbon cassette for a printer provided with a ribbon guide roller for stretching an ink ribbon before and after, the outer diameter of the central portion of the ribbon guide roller is D, the outer diameters of both ends are d1 and d2, respectively, and the print guarantee area of the print head When the width is WH, the width of the ink ribbon is WR, and the length of the outer shape D part at the center of the ribbon guide roller is LC,
D> d1 = d2,
WR>LC> WH
It is characterized by the following relationship .
Further, when the total length of the ribbon guide roller is LA and the lengths of the outer diameters d1 and d2 of the ribbon guide roller end portions are L1 and L2,
LA> (LC + L1) = (LC + L2)>WR>LC> WH
It is characterized by becoming.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 show an example of a ribbon cassette for a printer according to the present invention. The printer shown in FIG. 1 is a thermal printer, and a platen roller 1 serving as a member for transporting the print medium P is arranged to be driven to rotate at a predetermined process speed by a driving means (not shown). . The platen roller 1 is composed of a metal core made of metal such as stainless steel and a surface layer such as urethane rubber, and the hardness is 60 to 70 in the spring type hardness A type. Degree.
[0009]
The print head 2 disposed above the platen roller 1 in the vertical direction is held by a holding member (not shown) and moves up and down by driving means (not shown). The print head 2 is pressed against the platen roller 1 with a predetermined pressure by a tension of a head pressure spring (not shown).
[0010]
On the other hand, the ribbon cassette 3 winds and accommodates an ink ribbon R in a rotatable supply core 3 a inside the ribbon cassette 3, and the ink ribbon R passes through a plurality of rotatable rollers 6 and a rotatable pre-transfer ribbon guide roller 4. Then, it is pulled out toward the print head 2 outside the cassette case. The ink ribbon R drawn out from the cassette case passes between the print head 2 and the platen roller 1 and passes through a rotatable post-transfer ribbon guide roller 5 to a winding core 3b that is rotationally driven by a driving means (not shown). It is wound up.
[0011]
The print head 2 descends at the same time as the print medium P conveyed by the conveyance means 7 and 8 provided before and after the print head 2 is conveyed to the transfer point N, and the ink ribbon R and the print medium P are moved to the platen roller. The heating element is selectively heated based on print data transferred from a control device (not shown), and the ink is transferred from the ink ribbon R to the print medium P.
[0012]
The ribbon guide rollers 4 and 5 are made of resin or metal and have a cylindrical shape as shown in FIG. 3, and the relationship between the outer diameter D at the center and the outer diameters d1 and d2 at both ends is D> d1 = d2. These values are set to be related.
[0013]
Next, the state of the ink ribbon R during printing in the ink ribbon cassette 3 will be described. As shown in FIG. 1, the normal ink ribbon R is conveyed so that its center passes through the center of the ribbon guide rollers 4 and 5, but the alignment of the ribbon guide rollers 4 and 5 is displaced due to the dimensional accuracy of each part. , It was offset in the left or right direction of the figure.
[0014]
Here, since the ribbon guide rollers 4 and 5 have smaller outer diameters d1 and d2 than the outer diameter D at the center, the peripheral speed VD at the center (outer diameter D) of the ribbon guide rollers 4 and 5 is small. , And the peripheral speed Vd of both end portions (outer diameter d1d2 portion), a relationship of VD> Vd is established.
[0015]
Since the ink ribbon R is attracted to the side having a higher peripheral speed, a force to return the ink ribbon R to the center position acts on the ink ribbon R due to the difference in peripheral speed. Therefore, as shown in FIG. 4, when the end portion of the ink ribbon R protrudes from the position S where the outer diameter changes, a force to return to the center position works, and the movement from the A direction to the B direction starts.
[0016]
Here, the ink ribbon R is not transported while repeating the movements in the A and B directions, but is transported while maintaining a balance at a certain position depending on the alignment shift amount of the ribbon guide rollers 4 and 5. Accordingly, it is possible to prevent the ink ribbon R from dropping from the print region even though it is offset in any one of the A and B directions shown in FIG.
[0017]
The ribbon guide rollers 4 and 5, the ink ribbon R, and the print head 2 are arranged in the width direction as shown in FIG. 1 where the print guarantee area width of the print head 2 is WH, the width of the ink ribbon R is WR, and the ribbon guide roller. If the total length of 4 and 5 is LA, the length of the central portion of the ribbon guide rollers 4 and 5 is LC, and the lengths of the outer diameters d1 and d2 of the ribbon guide roller end portions are L1 and L2, LA> (LC + L1) = ( These values are set so that the relationship LC + L2)>WR>LC> WH is established.
[0018]
The width WR of the ink ribbon R is increased with respect to the central length LC of the ribbon guide guide rollers 4 and 5 (WR> LC), and both ends of the ink ribbon R take up both ends of the ribbon guide rollers 4 and 5. As a result, an effect of pulling the ink ribbon R toward both ends can be obtained, and image defects due to wrinkles at the center of the ink ribbon R can be prevented.
[0019]
Further, one of the length L1 or L2 of the end portions (outer diameters d1 and d2) of the ribbon guide rollers 4 and 5 is added to the center length LC of the ribbon guide rollers 4 and 5 with respect to the width WR of the ink ribbon R. In addition to increasing the length (LC + L1 = LC + L2> WR), due to the effect obtained from the relationship of D> d1 = d2 described above, contact of the ink ribbon R with the cassette case 7 can be avoided, and both ends of the ink ribbon R To prevent damage.
[0020]
Further, by making the print guarantee area width WH of the print head 2 smaller than the center length LC of the ribbon guide rollers 4 and 5 (LC> WH), it is possible to reliably prevent the image end portion from being missing.
[0021]
In this embodiment, the guide roller central portion outer diameter D is set to φ6 mm, both end portion outer diameters d1 and d2 are set to φ5 mm, the print head guarantee area width WH is 54 mm, the ink ribbon width WR is 60 mm, the ribbon The total length LA of the guide roller is set to 59 mm, the center length LC of the ribbon guide roller is set to 68.6 mm, and the lengths L1 and L2 of the end portions (outer diameters d1 and d2) of the ribbon guide rollers 4 and 5 are set to 5.3 mm. ing. As a result, even a printer using a combination of a wide thermal head and a wide ink ribbon can stably convey the ink ribbon and reliably provide a high-quality image.
[0022]
In particular, when an ink ribbon cassette is used, an ink ribbon having a limited capacity has a tendency to make the ink ribbon thinner, so that the effect appears more remarkably.
[0023]
The ribbon guide rollers 4 and 5 of the present embodiment can be rotated by fitting with pins protruding from the cassette case side. Instead, they are provided at both ends of the ribbon guide roller shown in FIG. The same effect can be obtained for the type in which the shaft is inserted into the cassette case.
[0024]
Furthermore, although the ribbon guide roller provided in the ink ribbon cassette is described in the present embodiment, the present invention can be similarly applied to a printer that holds the ink ribbon in an open reel system. In this case, the same effect can be achieved by making the shape of the ribbon guide roller arranged before and after the print head and the width direction dimension of the ribbon guide roller equal to the conditions in the ribbon cassette.
[0025]
In this embodiment, the present invention is limited to the ribbon guide rollers arranged before and after the print head, but the present invention is also applicable to all rollers related to the conveyance of the ink ribbon, for example, the roller 6 in FIG. It is desirable.
[0026]
【The invention's effect】
As described above, according to the present invention, the relationship between the outer diameter d of both ends with respect to the outer diameter D of the central portion of the guide roller is set so that D> d, so that the ink ribbon always returns to the central position. A force to try to act acts to prevent the ink ribbon from falling off the printing area.
[0027]
In addition, the print guarantee area width of the print head is WH, the width of the ink ribbon is WR, the overall length of the guide roller is LA, the length of the outer shape D portion at the center of the guide roller is LC, and the outer diameter of the guide roller from one end surface to the other By setting these values so that the relationship LA>Ls>WR>LC> WH is established when the length to the location where the change occurs is Ls, the effect of attracting the ink ribbon to both ends can be obtained. In addition, it is possible to reliably prevent image defects due to wrinkles at the center of the ink ribbon and missing prints at the edge of the image. Furthermore, it is possible to avoid contact of the ink ribbon with the cassette case and prevent damage to both ends of the ink ribbon.
[Brief description of the drawings]
FIG. 1 is an enlarged view of a ribbon cassette and a printer transfer portion of the present invention.
FIG. 2 is a cross-sectional view showing a schematic configuration of a printer equipped with a ribbon cassette.
FIG. 3 is a diagram illustrating a shape of a ribbon guide roller and a conveyance state of an ink ribbon R;
FIG. 4 is a diagram showing the shape of another ribbon guide roller.
FIG. 5 is a diagram showing a state of an ink ribbon during printing in a conventional printer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Platen roller 2 Print head 3 Ink ribbon cassette 3a Supply core 3b Winding core 4 Ribbon guide roller 5 Ribbon guide roller 6 Roller 7 Conveying means 8 Conveying means P Recording medium R Ink ribbon

Claims (2)

A print head for forming an image on a print medium;
A platen roller that sandwiches and conveys a print medium and an ink ribbon between the print head, and
A ribbon cassette for storing the ink ribbon;
With
In the ribbon cassette,
A first ribbon guide roller for guiding an ink ribbon toward the print head;
A second ribbon guide roller for guiding an ink ribbon downstream from the print head;
Is provided,
Each of the first and second ribbon guide rollers is formed in a cylindrical shape,
It is rotatably supported by a fitting pin provided in the cassette case,
The first and second ribbon guide rollers are:
Roller total length is LA,
The outer diameter of the central part is D ,
The outer diameters at both ends are d1, d2,
LC, the length of the central part having the outer diameter D,
The length of both ends is L1, L2,
The print guarantee area width of the print head is WH,
The width of the ink ribbon is WR,
When you and,
D> d1 = d2,
WR>LC> WH ,
LA> (LC + L1) = (LC + L2)>WR>LC> WH,
A printer characterized in that the above relationship is established . A ribbon cassette containing an ink ribbon for forming an image on a printing medium,
Cassette case,
Placed in this cassette case,
A supply core wound with the ink ribbon;
Winding core,
A first ribbon guide roller for guiding an ink ribbon toward a print head that forms an image on a print medium;
A second ribbon guide roller for guiding an ink ribbon downstream from the print head;
Consisting of
Each of the first and second ribbon guide rollers has a cylindrical shape and is rotatably fitted to the cassette case.
The first and second ribbon guide rollers are
Roller total length is LA,
The outer diameter of the center is D,
The outer diameters at both ends are d1, d2,
LC, the length of the central part having the outer diameter D
The length of both ends is L1, L2,
The print guarantee area width of the print head is WH,
The width of the ink ribbon is WR,
When you and,
D> d1 = d2,
WR>LC> WH ,
LA> (LC + L1) = (LC + L2)>WR>LC> WH,
A ribbon cassette for a printer, characterized in that the above relationship is established .

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