JP2014133628A - Tension application mechanism and printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tension application mechanism capable of keeping tensions applied to a recording sheet substantially constant in a recording sheet transport operation of a printer.SOLUTION: A tension application mechanism 40 for a recording sheet P unloaded from a roll sheet R and transported by transport means 20, includes: tension application member 42 slidably contacting the transported recording sheet P, and movable in a first direction D1 crossing the recording sheet P; and an elastic member 45 urging the tension application member 42 in the first direction D1. The tension application member 42 includes: a pulley 50 movable in a second direction D2 crossing the first direction D1; and an end belt 60 wound around an outer circumferential portion of the pulley 50. One end 60a of the end belt 60 wound around the pulley 50 is fixed in a direction along the first direction D1, and the other end 60b thereof is fixed in a direction along the second direction D2 at a predetermined distance from a position at which the one end 60a is fixed across the elastic member 45.

Description

  The present invention relates to a recording paper tension applying mechanism and a printer including the same.

  Printers that print information on long recording paper are known. In this type of printer, roll paper having a configuration in which long recording paper is wound into a roll is used. The roll paper is stored in a roll paper storage unit of the printer in a rollable state, and the recording paper is fed out from the roll paper by a conveying unit. The recording paper is conveyed to the printing position, and information is printed by the printing means at the printing position.

  When the recording paper conveyance load fluctuates, uneven feeding, meandering, etc. occur in the recording paper conveyance, and the recording paper conveyance accuracy decreases. As a result, the print quality also deteriorates. Therefore, a part of the recording paper that is fed from the roll paper and reaches the conveying means is laid over a tension guide that is urged by an elastic member to hold the recording paper in a tensioned state, and to change the conveyance load. Has been proposed (see, for example, Patent Document 1).

JP 2009-269399 A

  However, in recent years, higher-precision printing quality is required and higher-speed printing is required. In addition, from the viewpoint of increasing the amount of information to be printed and improving work efficiency such as roll paper replacement, there is a tendency to use wide recording paper or large diameter roll paper. For this reason, the influence of the inertia of the roll paper at the time of printing becomes large, and it has become difficult to reduce the load fluctuation of the recording paper conveyance.

  In the above-described printer, it is conceivable to stabilize the tension by increasing the stroke of the tension guide that applies tension. However, when the stroke is increased, the force for applying tension (the generated force of the elastic member) also increases due to the change in the stroke. This force acts as a resistance force for recording paper conveyance. If the resistance of the recording paper conveyance changes, it becomes difficult to ensure the recording paper conveyance accuracy, which may lead to a decrease in printing quality.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  (Application Example 1) A tension applying mechanism for a recording sheet fed out and conveyed from a roll sheet by a conveying unit, which is in sliding contact with the recording sheet to be conveyed and moves in a first direction intersecting the recording sheet A tensioning member that is capable of being moved and an elastic member that biases the tensioning member in the first direction, the tensioning member being movable in a second direction that intersects the first direction. A pulley and an endless belt that is looped around the outer periphery of the pulley, and the end belt that is looped around the pulley has one end fixed in a direction along the first direction, The tension applying mechanism, wherein the end is fixed at a position spaced apart from the position where the one end is fixed via the elastic member in a direction along the second direction.

  According to this configuration, in the recording paper tension applying mechanism, the force generated by the elastic member is transmitted to the tension applying member via the belt and the pulley. Therefore, when the recording paper is transported by the transporting means, the tension applying member can be moved in the first direction intersecting the recording paper in order to alleviate rapid fluctuations in the transporting load due to the inertia of the roll paper. . As the tension applying member moves, the tension of the belt exerted on the pulley becomes unbalanced, and the pulley moves in the second direction while rotating. At this time, the pulley corresponds to the force point of the generated force of the elastic member, the contact portion between the tension applying member and the recording paper corresponds to the action point, and the point where the recording paper drawn from the roll paper contacts the tension applying member corresponds to the fulcrum. .

  As the pulley moves in the second direction, the distance between the force point and the action point from the fulcrum changes. At this time, the change in the distance between the action point and the fulcrum can be made smaller than the change in the distance between the force point and the fulcrum. Therefore, even when the force generated by the elastic member changes due to the movement of the tension applying member, the tension on the recording paper can be kept constant. As a result, it is possible to reduce the generation force of the elastic member from being a resistance force for conveying the recording paper. Therefore, it is possible to reduce the load fluctuation during the recording paper conveyance and to convey the recording paper stably.

  (Application Example 2) The tension applying member includes a curved surface portion with which the recording paper comes into sliding contact, and the pulley is provided at a position excluding the curved surface portion of the tension applying member in the width direction of the recording paper. A tension applying mechanism as described above.

  According to this configuration, the tension applying member can obtain a moving force by the pulley while holding the recording paper at the curved surface portion.

  (Application Example 3) The pulley includes a main body portion having a disk shape and a shaft protruding from the center of the main body portion, and the endless belt is wound around an outer peripheral portion of the main body portion, The tension applying mechanism according to claim 1, wherein the shaft is fitted into a groove formed in a direction along the second direction of the tension applying member.

  According to this configuration, the pulley can rotate because the tension of the belt to be stretched becomes unbalanced as the tension applying member moves. As a result, the pulley can move in the second direction within the tensioning member.

  (Application Example 4) The tension applying mechanism according to claim 1, wherein a pinion gear is formed on an outer peripheral portion of the shaft of the pulley, and a rack gear is formed in a part of the groove of the tension applying member.

  According to this configuration, the pulley can reliably move in the second direction inside the tension applying member.

  (Application Example 5) A roll paper storage unit that stores roll paper in which a long recording paper is wound in a roll shape, a transport unit that unwinds the recording paper from the roll paper and transports the recording paper along a transport path, A printer comprising: a printing unit that prints information on the conveyed recording paper; and the tension applying mechanism that applies tension to the recording paper.

  According to this configuration, the printer can reduce the load fluctuation when the recording paper is conveyed, and can stably convey the recording paper. Therefore, the printing quality of the printer can be improved.

1 is a cross-sectional view illustrating a schematic configuration of a printer to which a tension applying mechanism according to an embodiment is applied. Schematic which shows the structure of a tension | tensile_strength provision mechanism. The schematic diagram explaining operation | movement of a tension | tensile_strength provision mechanism. The graph which showed typically the relationship between the movement of the tension | tensile_strength provision member in a tension | tensile_strength provision mechanism, and the force which generate | occur | produces.

  Hereinafter, the present embodiment will be described with reference to the drawings. In the drawings referred to in the following description, the vertical and horizontal scales of members or portions may be expressed differently from actual ones for convenience of description and illustration.

(About overall printer configuration)
First, the overall configuration of the printer will be described with reference to FIG. FIG. 1 is a cross-sectional view illustrating a schematic configuration of a printer to which a tension applying mechanism according to the present embodiment is applied. The X direction shown in FIG. 1 indicates the conveyance direction of the recording paper in the conveyance path, the Z direction indicates the width direction of the recording paper, and the Y direction indicates a direction orthogonal to the X direction and the Z direction.

  As shown in FIG. 1, the printer 10 includes a roll paper storage unit 12, a transport unit 20, a printing unit 30, a main body frame 18, and a tension applying mechanism 40. The roll paper storage unit 12 is provided at the lower portion of the main body frame 18 in the Y direction and includes a roll paper holder 14. A roll core 16, which is the center of a roll paper R obtained by winding a long recording paper P in a roll shape, is loaded into the roll paper holder 12 in a rollable state.

  A recording paper discharge port 15 is formed on one side surface of the main body frame 18 (a surface developed in the YZ direction in FIG. 1). The recording paper P is fed out from the roll paper R stored in the roll paper storage unit 12, transported along the transport path 22 via a tension applying mechanism 40 described later, and discharged from the recording paper discharge port 15. Conveying means 20 and printing means 30 are arranged in the conveying path 22 in order from the upstream side in the conveying direction.

  The transport unit 20 includes a transport roller 24 and a presser roller 26. The transport roller 24 has a cylindrical shape whose outer peripheral portion is covered with rubber or the like, and is disposed on the lower side of the transport path 22 in the Y direction. The presser roller 26 is formed in a cylindrical shape having a length substantially the same as that of the transport roller 24, for example, of a plastic material, and is rotatably disposed at a position facing the transport roller 24 across the transport path 22. The transport roller 24 rotates by obtaining a driving force from a transport motor (not shown). Therefore, the recording paper P sandwiched between the transport roller 24 and the press roller 26 is transported in the X direction along the transport path 22.

  The printing unit 30 is disposed on the downstream side of the conveying unit 20 and in the vicinity of the recording paper discharge port 15, and includes a printing head 32 and a platen 34. As the print head 32, for example, an ink jet head that ejects ink as droplets is suitably used. The print head 32 is disposed above the transport path 22 in the Y direction with a nozzle (not shown) that ejects ink facing downward in the Y direction. The platen 34 is disposed at a position facing the print head 32 across the transport path 22 and defines a printing position on the recording paper P.

  In the printer 10 having the above-described configuration, the recording paper P fed from the roll paper R stored in the roll paper storage unit 12 is transported along the transport path 22 by the transport unit 20 and is transported by the printing unit 30. The desired information is printed on P and discharged from the recording paper discharge port 15. The recording paper P on which information is printed may be cut to a desired length by an auto cutter (not shown) and issued as a single sheet.

(About the structure of the tensioning mechanism)
Next, the configuration of the tension applying mechanism will be described with reference to FIG. 2A and 2B are schematic views showing the configuration of the tension applying mechanism, FIG. 2A is a schematic side view of the tension applying mechanism, and FIG. 2B is a schematic view of FIG. 2A viewed from the Z direction. is there. Note that the X direction, Y direction, and Z direction shown in FIG. 2 indicate the same directions as the X direction, Y direction, and Z direction shown in FIG. In the present embodiment, two tension applying mechanisms are provided across the recording paper P in the paper width direction (Z direction) of the recording paper P. Since both have the same structure, the structure on one side will be described below for ease of explanation.

  As shown in FIG. 2, the tension applying mechanism 40 includes a tension applying member 42, a coil spring 45 as an elastic member, a pulley 50, and an end belt 60. As described above, the tension applying mechanism 40 is provided at both ends of the tension applying member 42.

  In this embodiment, the tension applying member 42 is formed in a cylindrical shape having a curved surface portion 42a having a length and a curvature in the width direction (Z direction) of the recording paper P that is sufficient for the recording paper P to be in sliding contact with the central portion of the outer peripheral portion. Has been. The tension applying member 42 is guided by a guide (not shown), and a first direction (for example, an arrow D1 direction in the figure, hereinafter referred to as a first direction) intersects the conveyance direction (arrow D3 direction in the figure) of the recording paper P in the curved surface portion 42a. It can be moved in the direction D1). Further, the tension applying member 42 has a structure that can swing within a predetermined range in the arc direction of the curved surface portion 42a.

  At both ends in the Z direction of the tension applying member 42, notches (hereinafter referred to as spaces 44) having a predetermined width are formed outside the width of the recording paper P. Furthermore, a second direction (for example, an arrow D2 direction in the figure, hereinafter referred to as a second direction D2) intersecting the moving direction (first direction D1) of the tension applying member 42 on both sides in the Z direction across the space 44. Are formed with grooves 46 and 47 having a predetermined length and width.

  The pulley 50 includes a main body 52 having a disk shape and shafts 54 and 55 projecting from the center of the main body 52 to both sides. In the pulley 50, the main body 52 is disposed in the space 44 of the tension applying member 42, and the shafts 54 and 55 are fitted in the grooves 46 and 47 of the tension applying member 42. In the pulley 50, the main body 52 is rotatable in the space 44, and in a second direction D 2 that intersects the moving direction (first direction D 1) of the tension applying member 42 along the grooves 46 and 47. It is movable. In addition, the endless belt 60 mentioned later is wound around the outer peripheral part of the main-body part 52 of the pulley 50. As shown in FIG.

  The endless belt 60 is formed of a material such as rubber, for example, and is wound around the outer peripheral portion of the main body 52 of the pulley 50 described above. An end portion of the endless belt 60 that is wound around the pulley 50 is stretched in the moving direction (first direction D1) of the tension applying member 42, and one end 60a is fixed to the wall surface of the main body frame 18. The other end 60b of the endless belt 60 is fixed to one end of a coil spring 45 as an elastic member. The other end of the coil spring 45 is fixed at a position separated by a predetermined distance from the position where one end 60a of the endless belt 60 on the wall surface of the main body frame 18 is fixed. In other words, the other end 60 b of the endless belt 60 is also fixed to the wall surface of the main body frame 18 via the coil spring 45.

(Operation of tensioning mechanism)
Here, the operation of the tension applying mechanism will be described with reference to FIGS. FIG. 3 is a schematic diagram for explaining the operation of the tension applying mechanism. FIG. 3A shows a case where the recording paper is traveling at a constant speed or a stopped state, and FIG. FIG. 3A shows a case where the recording paper is accelerated from the state of FIG. FIG. 4 is a graph schematically showing the relationship between the position of the tension applying member and the generated force in the tension applying mechanism. Note that the X direction, Y direction, and Z direction shown in FIG. 3 indicate the same directions as the X direction, Y direction, and Z direction shown in FIG.

  As shown in FIG. 3A, in the printer 10 shown in FIG. 1, when the recording paper P is traveling at a constant speed or in a stopped state (hereinafter referred to as a stable state), the tension of the tension applying mechanism 40 The load force L1 (force toward the recording paper discharge port 15) applied to the recording paper P at the boundary of the curved surface portion 42a of the applying member 42 and the resultant force L (component in the X direction) of the load force L2 of the roll paper R and the coil spring 45 The tension T (component in the X direction) generated by the generated force F is balanced and is in a so-called stable state. At this time, the generated force F of the coil spring 45 is F = k (spring constant) x, where x is the displacement of the coil spring 45.

  As shown in FIG. 3B, when the recording paper P is accelerated by the conveying unit 20 from the above-described stable state or when the rolling load of the roll paper R becomes large (hereinafter referred to as a load fluctuation state), Load force L1 ′ applied to the recording paper P with the curved surface portion 42a of the tension applying member 42 as a boundary (force toward the recording paper discharge port 15) and resultant force L ′ (component in the X direction) of the load force L2 ′ of the roll paper R Becomes larger (L ′> T). Along with this, the tension applying member 42 is pulled by the recording paper P and moves to the left in the X direction in the drawing from the position shown in FIG.

  The generated force of the coil spring 45 in this load fluctuation state (FIG. 3B) is defined as F ′. The generated force F ′ of the coil spring 45 is F ′ = k (spring constant) x ′ (x ′> x) when the displacement of the coil spring 45 is x ′. Therefore, in this state, an increase in the generated force F ′ of the coil spring 45 becomes a resistance force, which causes a load fluctuation.

  Here, the force points at which the generated forces F and F ′ of the coil spring 45 are transmitted to the tension applying member 42 are P and P ′, and the action points of the tensions T and T ′ are points O and O ′. Then, since the fulcrums of the force points P and P ′ and the action points O and O ′ are considered to be points where the recording paper P drawn from the roll paper R contacts the tension applying member 42, the fulcrums are indicated by C and C ′ ( (Refer FIG. 3 (a), (b)). Further, the distance between the force points P and P ′ and the fulcrums C and C ′ is m in the stable state and m ′ in the load fluctuation state. In addition, the distance between the action points O and O ′ and the fulcrums C and C ′ is r in a stable state and r ′ in a load fluctuation state.

  In the stable state shown in FIG. 3A, the moment around the fulcrum C due to the generated force F of the coil spring 45 is equal to the moment around the fulcrum C due to the tension T. In the load fluctuation state shown in FIG. 3B, the moment around the fulcrum C ′ due to the generated force F ′ of the coil spring is equal to the moment around the fulcrum C ′ due to the tension T ′. Accordingly, the tension T is expressed as T = mF / r (Expression 1), and the tension T ′ is expressed as T ′ = m′F ′ / r ′ (Expression 2).

  The tension applying mechanism 40 described above has a load force L1 applied to the recording paper P, a load force L2 of the roll paper R, and a resultant force L when the conveyance state of the recording paper P shifts from the stable state to the load fluctuation state. Changes, the tension applying member 42 moves in the first direction D1. At this time, the generated force F of the coil spring 45 against the resultant force L is transmitted to the tension applying member 42 via the pulley 50 around which the endless belt 60 fixed to the main body frame 18 is stretched at a predetermined interval. . Since the tension applying member 42 moves, the coil spring 45 is displaced, and the tension of either one of the endless belts 60 wound around the pulley 50 changes. Therefore, a rotational force acts on the pulley 50.

  The pulley 50 is movable along grooves 46 and 47 formed along a second direction D2 that intersects the first direction D1. Further, the tension applying member 42 has a structure that can swing within a predetermined range in the arc direction of the curved surface portion 42a. Therefore, the pulley 50 moves along the grooves 46 and 47 of the tension applying member 42 by the amount rotated in the second direction D2.

  As a result, the distance m between the force point P and the fulcrum C of the tension applying mechanism 40 changes. On the other hand, the distance r between the action point O and the fulcrum C does not change greatly. As shown in FIGS. 3, 1, and 2, even when the tension applying member 42 moves and the generated force F of the coil spring changes to F ′ (increases in FIG. 3), the pulley 50 is driven by the endless belt 60. Is moved in the second direction D2 within the tension applying member 42, and the distance m between the force point P and the fulcrum C is changed to m ′ (decrease in FIG. 3). Since the distance r between the action point O and the fulcrum C is r ′ with little change, it is possible to change (increase / decrease) k (constant) / r contrary to the change (increase / decrease) of the coil spring 45. That is, this makes it possible to keep the tension T applied to the recording paper P constant even when the force F generated by the coil spring 45 changes due to the movement of the tension applying member 42.

  FIG. 4 shows the generated force F of the coil spring 45 as an elastic member with respect to the movement of the tension applying member 42, the tension T on the recording paper P, the distance m between the force point P and the fulcrum C, and the distance r between the action point O and the fulcrum C. The change of is shown typically. As shown in FIG. 4, the generated force F of the coil spring 45 increases as the tension applying member 42 moves leftward (first direction D1). On the other hand, the distance m between the force point P and the fulcrum C decreases. The change in the distance r between the action point O and the fulcrum C is very small. As a result, the tension T applied to the recording paper P with respect to the movement of the tension applying member 42 can be made substantially constant.

  That is, in the paper transporting operation of the printer 10, the recording paper P accelerates or the rolling load of the roll paper R increases, and the tension applying member 42 that functions as a tension guide moves and resists the tension applying member 42. Even if the displacement of the coil spring 45 as an elastic member for imparting increases, the tension applying mechanism 40 according to the present invention can make the tension T applied to the recording paper P substantially constant. Therefore, the recording paper P can be stably conveyed. As a result, the conveyance accuracy of the recording paper P can be ensured, and the printing quality can be improved.

  As mentioned above, although the Example of this invention was described, various deformation | transformation can be added with respect to the said Example in the range which does not deviate from the meaning of this invention. For example, modifications other than the above embodiment are as follows.

  (First Modification) The above embodiment has been described by taking as an example the case where the pulley 50 moves in the second direction D2 while rotating by friction along the grooves 46 and 47 provided in the tension applying member 42. It is not limited to. In the movement of the pulley 50 in the second direction D2, a rack gear is formed on one long side of the grooves 46 and 47, and a pinion gear is formed on a part of the outer peripheral portion of the shafts 54 and 55 of the pulley 50 in the axial direction. A so-called rack and pinion system in which both are engaged may be employed. In this case, the movement of the pulley 50 in the second direction D2 can be ensured.

  (Other Modifications) In the above embodiment, the case where the columnar tension applying member 42 is employed has been described as an example, but the present invention is not limited to this. The tension applying member 42 includes a curved surface portion 42a having a length and a curvature in the width direction (Z direction) of the recording paper P that is sufficient for the recording paper P to be in sliding contact with the central portion of the outer peripheral portion, and is movable in the first direction D1. In addition, it is only necessary to have a structure that can swing within a predetermined range in the arc direction of the curved surface portion 42a.

  DESCRIPTION OF SYMBOLS 10 ... Printer, 12 ... Roll paper accommodating part, 18 ... Main body frame, 20 ... Conveyance means, 22 ... Conveyance path, 30 ... Printing means, 32 ... Print head, 40 ... Tension applying mechanism, 42 ... Tension applying member, 42a ... Curved surface portion 45 ... Coil spring as elastic member, 46, 47 ... groove, 50 ... pulley, 54, 55 ... shaft, 60 ... end belt, D1 ... first direction, D2 ... second direction, P ... recording Paper, R ... roll paper.

Claims (5)

A tension applying mechanism for recording paper that is fed from a roll paper and conveyed by a conveying means,
A tension applying member that is in sliding contact with the recording paper to be conveyed and is movable in a first direction intersecting the recording paper;
An elastic member that urges the tension applying member in the first direction,
The tension applying member is
A pulley movable in a second direction intersecting the first direction;
And an endless belt wound around the outer periphery of the pulley,
One end of the endless belt wound around the pulley is fixed in a direction along the first direction, and the other end is fixed in the second direction from a position where the one end is fixed via the elastic member. A tension applying mechanism, wherein the tension applying mechanism is fixed at a predetermined interval in a direction along the direction. The tension applying member includes a curved surface portion with which the recording paper comes into sliding contact,
The tension applying mechanism according to claim 1, wherein the pulley is provided at a position excluding the curved surface portion of the tension applying member in the width direction of the recording paper. The pulley has a main body portion having a disk shape, and a shaft protruding from the center of the main body portion,
The end belt is wound around the outer periphery of the main body,
The tension applying mechanism according to claim 1 or 2, wherein the shaft is fitted into a groove formed in a direction along the second direction of the tension applying member. A pinion gear is formed on the outer periphery of the shaft of the pulley,
The tension applying mechanism according to any one of claims 1 to 3, wherein a rack gear is formed in a part of the groove of the tension applying member. A roll paper storage unit for storing roll paper in which a long recording paper is wound into a roll; and
Conveying means for delivering the recording paper from the roll paper and conveying along the conveying path;
Printing means for printing information on the transported recording paper;
A printer, comprising: a tension applying mechanism according to claim 1 that applies tension to the recording paper.

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