JP3690476B2 - Paper guide unit and printing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a paper guide unit for guiding print paper to a platen, and a printing apparatus equipped with the paper guide unit.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a printing apparatus that feeds paper by winding printing paper around a cylindrical platen has a driven roller that is elastically contacted with the platen, and the platen is rotated by a fixed angle by a driving source such as a motor, while the driven is driven. The roller is elastically contacted with the peripheral surface of the platen by elastic urging means such as a spring. The printing paper is nipped between the platen and the driven roller and fed by the frictional force. When a continuous paper having a feed hole such as a field paper is used, a paper transport device composed of a sprocket or a tractor is used as disclosed in Japanese Utility Model Publication No. 60-14504.
[0003]
Incidentally, in order to guide the printing paper to the platen, a paper guide unit is usually provided below the platen. An opening recess is formed in the paper guide unit, and a driven roller is disposed in the opening recess. The printing paper is guided between the platen and the driven roller in the paper conveyance direction while being sandwiched, and the printing paper can be wound around the outer peripheral surface of the platen.
[0004]
[Problems to be solved by the invention]
However, in the above conventional technique, since there is a large gap between the inner wall surface of the opening recess formed in the paper guide unit and the roller holder that holds the driven roller, the leading edge of the printing paper is caught in the gap during paper conveyance. There is a problem that paper breaks and paper jams occur. Further, when the printing paper is a continuous paper, there is a perforation (fold), so that the perforation is caught in the gap, and similarly, there is a problem that paper folding or paper jam occurs.
[0005]
An object of the present invention is to provide a paper guide unit that can prevent the leading edge or perforation of the printing paper from being caught in the gap between the roller holder and the inner wall surface of the opening recess, and a printing apparatus equipped with the paper guide unit. That is.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a driven roller held by a roller holder is provided in an opening recess provided in a paper guide surface of a paper guide unit main body. A paper guide unit that guides the printing paper in the paper conveyance direction while sandwiching the printing paper with a platen opposite to the platen, and winds the printing paper around the outer peripheral surface of the platen. The roller holder has an upper surface in the paper conveyance direction. And the upstream end of the holder is formed close to the upstream inner wall surface of the opening recess, and is conveyed on the paper guide surface of the paper guide unit main body. It formed a tip or folds to direct the driven roller is received by the upper surface of the holder tip, before the sheet guide surface of the sheet guide unit body A guide rib is provided on the upstream side of the opening recess, and extends in the paper conveyance direction in a straight line with the front end of the holder. At the downstream end of the guide rib, the guide rib is at the same height as the guide rib and in the main scanning direction. A ridge that is wider than the guide rib and that is inclined so that the upstream side is lowered toward the upstream side is provided so as to be wider than the tip of the holder .
[0007]
According to the present invention, the holder front end portion of the roller holder is formed close to the upstream inner wall surface of the opening recess, and the front end of the printing paper transported on the paper guide surface of the unit body is used as the holder. Since it is formed so that it is received on the upper surface of the leading end and guided to the driven roller, the leading end of the printing paper is not caught in the gap of the full opening recess during paper conveyance, and paper breaks and paper jams occur. Can be prevented.
[0008]
The invention according to claim 2 of the present application is characterized in that, in the paper guide unit according to claim 1, a first protrusion toward the holder tip is formed on the inner wall surface of the opening recess. It is what. According to the present invention, it is possible to further increase the degree of approach, that is, to further reduce the gap, by the first protrusion, and it is possible to reliably prevent the printing paper from being caught.
[0009]
According to a third aspect of the present invention, in the paper guide unit according to the second aspect, a guide rib extends on the paper guide surface of the unit main body in the paper transport direction, and the first protrusion is The guide rib and the inner wall surface are formed in series. According to the present invention, the printing paper guided and conveyed from the lower side to the guide rib of the unit main body is further guided by the guide rib and the series of rib-shaped first protrusions and received on the upper surface of the roller front end portion. Therefore, the sheet can be smoothly conveyed in the unit portion, and the occurrence of the catch can be further prevented.
[0010]
According to a fourth aspect of the present invention, in the paper guide unit according to any one of the first to third aspects, a second protrusion that faces the roller surface of the driven roller is formed on the inner wall surface of the opening recess. It is characterized by being. According to the present invention, since the gap between the outer peripheral surface of the driven roller and the inner wall surface of the opening recess is made small as well as the gap between the roller holder and the inner wall surface of the opening recess, printing is performed in the unit portion during paper conveyance. The leading edge of the paper and the perforation are not caught in the gap, and the occurrence of paper folding and paper jam can be prevented.
[0011]
The invention according to claim 5 of the present invention is a printing apparatus that has a cylindrical platen, winds printing paper around the platen, rotates the platen, and performs printing while feeding the printing paper. The sheet guide unit according to any one of Items 1 to 4 is mounted. According to the printing apparatus according to the present invention, it is possible to prevent the printing paper from being folded or from being jammed, so that printing can be performed smoothly.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a longitudinal sectional view showing a paper transport mechanism of a printing apparatus according to the present invention, FIG. 2 is an external perspective view of the paper transport mechanism, FIG. 3 is an external perspective view of a paper guide unit, and FIG. 4 is an enlarged view of the paper guide unit. FIG. 5 is an enlarged perspective view of the main part of the paper guide unit according to the first embodiment, and FIG. 6 is an enlarged perspective view of the main part of the paper guide unit according to the second embodiment.
[0013]
(Embodiment 1)
As shown in FIGS. 1 and 2, the paper transport mechanism of the printing apparatus according to the present invention includes a push-in tractor 1, a printing unit 2, and a paper discharge unit 3. The push-type tractor 1 is provided with two belts 1A. The belt 1 </ b> A has a large number of pins 1 </ b> B around the belt 1 </ b> A, and these pins 1 </ b> B are fitted into holes at both end portions of a printing paper (not shown). The printing paper can be conveyed by rotating the belt 1A with a driving source (not shown). The push-in tractor 1 is also provided on the opposite side of the printing unit 2.
[0014]
The printing unit 2 is provided with a paper guide unit main body 4 and a cylindrical platen 5. As shown in FIGS. 3 and 4, the upper surface of the sheet guide unit main body 4 has a flat surface 4A on the upstream side (upper right side in FIG. 3) along the sheet conveyance direction, and a concave curved surface on the downstream side of the flat surface 4A. 4B is provided. On the flat surface 4A and the concave curved surface 4B constituting the paper guide surface, a plurality of guide ribs 4R that directly support and guide the print paper are extended in parallel in the paper transport direction at a predetermined interval. The curvature of the concave curved surface 4B is formed approximately equal to the curvature of the platen 5.
[0015]
In the present embodiment, the paper guide unit main body 4 is formed with four opening recesses 4C along the width direction, and each of the opening recesses 4C is provided with driven rollers 6 and 7 along the paper transport direction. It is arrange | positioned in the state hold | maintained rotatably. The platen 5 is rotationally driven by a fixed angle by a drive source (not shown), and conveys printing paper (not shown) sent from the push-in tractor 1 while being sandwiched between the driven rollers 6 and 7. . The paper guide unit main body 4 guides the printing paper to the platen 5 side with the concave curved surface 4B and winds the printing paper around the outer peripheral surface of the platen 5 in a U shape.
[0016]
Further, as shown in FIG. 1, a print head 8 is provided to face the outer peripheral surface of the platen 5. The print head 8 is reciprocally movable in the direction perpendicular to the paper surface of FIG. 1. During printing, the print head 8 is in close contact with the printing paper wound in a U shape around the outer peripheral surface of the platen 5 so as to print on the printing paper. It has become.
[0017]
The paper discharge unit 3 is provided with a paper discharge drive roller 9 and a paper discharge driven roller 10. The paper discharge driving roller 9 and the paper discharge driven roller 10 are rotatably supported by the paper discharge unit frame 11. The printing paper printed by the print head 8 is conveyed while being sandwiched between the paper discharge driving roller 9 and the paper discharge driven roller 10, and passes through the space 14 between the paper discharge unit frame 11 and the paper discharge unit cover 13. It is designed to be carried out through.
[0018]
In the present embodiment, as shown in an enlarged view in FIG. 5, the roller holder 15 has an upper surface 15B formed in a shape along the paper conveyance direction, that is, a substantially concave curved surface shape. Further, the holder tip 15A on the upstream side in the sheet conveying direction of the roller holder 15 is formed close to the upstream inner wall surface 16 of the opening recess 4C. Due to this approach structure, the front end or perforation (fold) of the printing paper conveyed on the paper guide surface (flat surface 4A, concave surface 4B) of the paper guide unit main body 4 is received by the upper surface of the holder front end portion 15A. It is formed so as to be guided to the driven roller 6.
[0019]
In the present embodiment, a first protrusion 4D directed to the holder tip 15A is integrally formed on the inner wall surface 16 of the opening recess 4C. That is, the first protrusion 4 </ b> D is formed at a position facing the both end portions 15 </ b> A of the roller holder 15. Further, the first protrusion 4D is formed in a rib shape on the inner wall surface 16 in series with the guide rib 4R provided on the paper guide surface of the paper guide unit main body 4. That is, two first protrusions 4D are provided in the vertical direction on the upstream inner wall surface 16 of the opening recess 4C in the conveyance direction of the printing paper.
[0020]
Thus, since the first protrusion 4D is formed on the inner wall surface 16 of the opening recess 4C, the gap between the tip 15A of the roller holder 15 and the inner wall surface 16 of the opening recess 4C is reduced, and the sheet guide unit body The leading edge or perforation of the printing paper conveyed through the four paper guiding surfaces is received by the upper surface 15B of the holder leading end portion 15A and guided to the driven roller 6. Accordingly, it is possible to avoid the leading edge or perforation of the printing paper from being caught in the gap during paper conveyance, thereby preventing the printing paper from being folded or jammed.
[0021]
(Embodiment 2)
Next, another embodiment will be described. The protruding portion such as the first protrusion 4D can be formed not only at a position facing the holder tip 15A of the roller holder 15 but also at a position facing the outer peripheral surface of the driven roller 6. That is, in the second embodiment, as shown in FIG. 6, a wide first width substantially equal to the axial length of the driven roller 6 is provided at a position facing the outer peripheral surface of the driven roller 6 on the inner wall surface of the opening recess 4C. Two protrusions 4E are formed integrally with the paper transport unit main body 4. Further, a protrusion 4F wider than the first protrusion 4D in the first embodiment is formed at a position facing the front end 15A of the roller holder 15.
[0022]
If comprised in this way, not only the clearance gap between the holder front-end | tip part 15A of the roller holder 15 and the inner wall face 16 of the opening recessed part 4C but the clearance gap between the outer peripheral surface of the driven roller 6 and the inner wall face 16 of the opening recessed part 4C is made small. Therefore, it is possible to more reliably prevent the occurrence of paper folding and paper jam of the printing paper.
[0023]
In the first and second embodiments, the first protrusion 4D, the protrusion 4F, and the second protrusion 4E are formed integrally with the paper transport unit main body 4, but the first protrusion 4D and the protrusion 4F are formed. Alternatively, the second protrusion 4E may be formed of a member different from the paper transport unit 4 and fixed to the inner wall surface 16 of the opening recess 4C by bonding or the like.
[0024]
【The invention's effect】
As described above, according to the present invention, since the gap between the holder tip of the roller holder and the inner wall surface of the opening recess is small, the leading edge of the printing paper and the perforation are not caught in the gap during paper conveyance. Therefore, it is possible to prevent paper breakage and paper jam. As a result, printing can be performed smoothly.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a paper transport mechanism of a printing apparatus according to the present invention.
2 is an external perspective view of the paper transport mechanism of FIG. 1. FIG.
FIG. 3 is an external perspective view of a paper guide unit.
FIG. 4 is an enlarged cross-sectional view of a paper guide unit.
FIG. 5 is an enlarged perspective view of a main part of the paper guide unit according to the first embodiment of the present invention.
FIG. 6 is an enlarged perspective view of a main part of a paper guide unit according to Embodiment 2 of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Push-in tractor 2 Printing part 3 Paper discharge part 4 Paper guide unit main body 4C Opening recessed part 4D 1st protrusion 4E 2nd protrusion 4F Projection 5 Platen 6, 7 Driven roller 8 Print head 15 Roller holder 15A Holder front-end | tip part

Claims (5)

A driven roller held by the roller holder is provided in an opening recess provided in the paper guide surface of the paper guide unit main body, and guides the paper in the paper conveyance direction while sandwiching the printing paper by the driven roller and the platen facing the driven roller. A paper guide unit for winding the printing paper around the outer peripheral surface of the platen,
The roller holder has an upper surface formed in a shape along the sheet conveyance direction, and a holder tip portion on the upstream side is formed close to an upstream inner wall surface of the opening recess, and the sheet guide unit Formed to receive the leading edge or fold of the printing paper conveyed through the paper guide surface of the main body at the upper surface of the tip of the holder and guide it to the driven roller,
On the upstream side of the opening concave portion of the paper guide surface in the paper guide unit main body, a guide rib extends in the paper transport direction in a straight line with the holder tip,
At the downstream end of the guide rib, a ridge that is the same height as the guide rib, is wider than the guide rib in the main scanning direction, and is inclined so that the upstream side is lowered toward the upstream side from the tip of the holder. A paper guide unit having a wide width .  The sheet guide unit according to claim 1, wherein a first protrusion toward the tip of the holder is formed on the inner wall surface of the opening recess.  3. The paper guide surface of the paper guide unit main body according to claim 2, wherein a guide rib is extended in the paper transport direction, and the first protrusion is formed on the inner wall surface in series with the guide rib. Paper guide unit.  4. The sheet guide unit according to claim 1, wherein a second protrusion that faces the roller surface of the driven roller is formed on the inner wall surface of the opening recess. 5.  The paper according to any one of claims 1 to 4, wherein the paper has a cylindrical platen, the printing paper is wound around the platen, and printing is performed while feeding the printing paper by rotating the platen. A printing apparatus equipped with a guide unit.

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