JP2004262104A - Dot impact printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dot impact printer which can deal with such a print sheet as the thickness varies locally. <P>SOLUTION: The dot impact printer employs such a platen 10 as shaped to absorb a difference in the thickness of a print sheet S by decreasing the diameter depending on the part of the print sheet S where the thickness varies. Since the effect of thickness of the sheet is eliminated along the longitudinal direction of the platen 10, print density can be made uniform while eliminating an unprinted part. Furthermore, catching of the print sheet due to difference in the thickness is lessened and jamming of sheet can be reduced. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention belongs to the technical field of a dot impact printer, and more particularly, to a dot impact printer that responds to a change in the thickness of a printing sheet as a printing target.
[0002]
[Prior art]
In general, a dot impact printer mounts printing paper on a platen, draws out an ink ribbon on the printing paper, and strikes a head pin from a print head toward the ink ribbon, so that a printing paper as a printing target is printed. It is configured to perform printing.
[0003]
In the dot impact printer, when printing paper having a difference in paper thickness is used, a place where printing is not performed or a difference in printing density occurs. For this reason, a part of the outer peripheral surface of the platen is made to be a metal part, and the facing part of the platen with the print head is freely switched to the metal part or the other part by the fixing bracket according to the number of copy slip sheets. A configuration is known (for example, see Patent Document 1). There is also known a printer having a mechanism for automatically adjusting a gap between a print head and a sheet (for example, see Patent Document 2).
[0004]
[Patent Document 1]
Japanese Patent No. 25655088 [Patent Document 2]
JP-A-6-155853
[Problems to be solved by the invention]
The dot impact printer described in Patent Document 1 described in the related art can secure sufficient print density even when the number of copy slip sheets is large, and also prevents the occurrence of breakage of the ink ribbon even when the number of sheets is small, Although it is possible to selectively use the platen material effectively according to the number of copy slip sheets, it cannot cope with printing paper in which the thickness of paper locally changes. For example, it is not possible to solve the problem that a printing density difference occurs in the longitudinal direction of the platen with respect to printing paper in which the paper thickness locally changes due to the turn of the paper stapler or the thickness of the glue. Further, the dot impact printer described in Patent Document 2 can accurately adjust the gap between the print head and the paper. Can not respond.
[0006]
The present invention has been made in view of such a problem, and an object of the present invention is to provide a dot impact printer that can cope with printing paper in which the paper thickness changes locally.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a dot impact printer according to the present invention includes a platen having a shape that absorbs a difference in paper thickness of printing paper by reducing a diameter corresponding to a portion where the paper thickness of the printing paper changes. Characterized by using.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0009]
FIG. 1 is an explanatory view showing an example of a platen used in a dot impact printer according to the present invention. This platen is used in a general dot impact printer for printing a copy slip or the like. That is, the platen is rotatably mounted at a predetermined position facing the print head of the printer. An ink ribbon is movably arranged between the platen and the print head, and printing paper such as a copy slip is supplied onto the platen, and printing is performed on the printing paper by ejecting head pins from the print head. Is
[0010]
While the conventional platen has a uniform roller diameter in the longitudinal direction, the platen 10 shown in FIG. 1 has a shape in which small-diameter portions 12 are provided at both ends of a central portion 11 having a normal diameter. The platen 10 is a type used for a dot impact printer that prints on a printing sheet S (copy slip) having a thicker sheet on both sides. As shown in FIG. The roller diameter is correspondingly reduced. That is, the outer diameter of the corresponding portion is reduced in order to make the portion where the sheet thickness changes escape. Specifically, good printing is performed on the entire printing paper by strictly measuring the thickness of the printing paper and changing the diameter of the platen based on the measured value.
[0011]
As a printing sheet having a thicker sheet on both sides, there is a copy slip bound with a paper stapler. FIG. 2 shows a partially enlarged view of a copy slip using this paper stapler. In FIG. 2, 1 is a slip sheet, 2 is a marginal punch for conveyance provided on both sides of the slip sheet, and 3 is a U-shaped notch that functions as a paper stapler. By making a cut, the slip sheet 1 is bound. The slip sheet 1 stapled with such a paper stapler may be turned up during the sheet conveyance and the thickness of the sheet locally changes. Therefore, good printing can be performed in response to a change in the sheet thickness.
[0012]
FIGS. 3 and 4 are explanatory views showing another example of the platen used in the dot impact printer according to the present invention. The illustrated platen allows a plurality of rollers to be divided and assembled in the longitudinal direction. As a connecting means between the rollers, a known means such as a screw or fitting may be used.
[0013]
The platen 20 shown in FIG. 3 has three rollers 21, 22, and 23 connected to correspond to a convex portion in the middle of the transport direction of the printing paper S. As shown in FIG. Assembling is performed with the small-diameter roller 22 interposed between the rollers 21 and 23. The platen 30 shown in FIG. 4 is assembled by connecting five rollers 31, 32, 33, 34, 35 corresponding to two large and small convex portions in the middle of the transport direction of the printing paper S. In addition, as shown in the figure, small-diameter rollers 32 and 34 having different diameters corresponding to the large and small convex portions are interposed between the normal-diameter rollers 31, 33 and 35, respectively. As described above, since the platen shown in FIGS. 3 and 4 has a shape corresponding to a place where the thickness of the printing paper to be hung on the printer is different, by using this platen, Good printing can be performed in response to a change in paper thickness.
[0014]
In addition, the dot impact printer of the present invention makes it possible to use a replaceable platen to handle various types of printing paper having different places where the thickness of the paper changes, using the corresponding platen.
[0015]
FIG. 5 is an explanatory diagram showing a specific example of a platen used in the dot impact printer according to the present invention. The platen 40 is used when printing on a form 50 with a card, and is configured by connecting four rollers 41, 42, 43, and 44 in the longitudinal direction.
[0016]
A form 50 with a card to be printed is a form in which a card 54 such as a credit card or a cash card is affixed to the bottom sheet 51 and three sheets 51, 52, 53 are bound at one end with glue 55. When the card 54 is mailed to an individual, predetermined items such as an address are printed by a dot impact printer. The illustrated platen 40 is used at the time of printing, and combines rollers 42 and 44 having normal diameters and rollers 41 and 43 having small diameters in correspondence with a portion where the paper thickness changes due to the card 54 and the glue 55. It is configured. By using the platen 40, good printing can be performed in response to a change in the sheet thickness of the form 50 with a card.
[0017]
As described above, the embodiments of the present invention have been described in detail. However, the dot impact printer according to the present invention is not limited to the above embodiments, and various changes may be made without departing from the spirit of the present invention. What is possible is obvious.
[0018]
【The invention's effect】
The dot impact printer according to the present invention is characterized by using a platen shaped so as to absorb the difference in the paper thickness of the printing paper by reducing the diameter corresponding to the portion where the paper thickness of the printing paper changes. Since there is no influence of the thickness of the sheet along the longitudinal direction of the platen, not only a place where no printing is performed but also a uniform printing density can be achieved. Further, the catch of the printing paper due to the difference in the paper thickness is reduced, and the occurrence of paper jam can be reduced.
[0019]
In addition, by making the platen replaceable, the diameter of the platen can be changed according to the paper thickness, so that an optimum print density can be obtained, and the versatility that a place where the paper thickness differs is not specified. Can be made.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an example of a platen used in a dot impact printer according to the present invention.
FIG. 2 is a partially enlarged view of a copy slip using a paper stapler.
FIG. 3 is an explanatory diagram showing another example of a platen used in the dot impact printer according to the present invention.
FIG. 4 is an explanatory diagram showing another example of a platen used in the dot impact printer according to the invention.
FIG. 5 is an explanatory diagram showing a specific example of a platen used in the dot impact printer according to the invention.
[Explanation of symbols]
S Printing paper 1 Slip paper 2 Marginal punch 3 Cut 10 Platen 11 Central part 12 Small diameter part 20 Platen 21, 22, 23 Roller 30 Platen 31, 32, 33, 34, 35 Roller 40 Platen 41, 42, 43, 44 Roller 50 Forms with cards 51, 52, 53 Paper 54 Card 55 Glue

Claims (2)

A dot impact printer comprising a platen having a shape that absorbs a difference in the thickness of printing paper by reducing a diameter corresponding to a portion where the thickness of printing paper changes. The dot impact printer according to claim 1, wherein a platen is replaceable.

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