JP2008006677A - Double-sided printing thermal printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double-sided printing thermal printer which can smoothly perform conveyance of a thermal paper even if outer diameters of platens are not strictly managed in the case of driving the two platens by the same driving motor. <P>SOLUTION: The double-sided printing thermal printer is equipped with a feeding mechanism 23 which supplies the thermal paper P along a paper conveyance path 22, a first thermal head 51 set along the paper conveyance path 22, a first platen roller 52 arranged by holding the paper conveyance path 22 between it and the first thermal head 51, a second thermal head 61 set along the paper conveyance path 22, a second platen roller 62 arranged by holding the paper conveyance path 22 between it and the second thermal head 61, a one-way gear 54 which cuts a driving force from a driving motor 41 only when the first platen roller 52 rotates to a supply side of the thermal paper P, and a one-way gear 64 which cuts the driving force from the driving motor 41 only when the second platen roller 62 rotates to a discharging side of the thermal paper P. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a double-sided printing thermal printer that performs printing on both sides of a thermal paper, and more particularly to a technique that can smoothly carry a sheet.

  A double-sided printing thermal printer for performing double-sided printing on thermal paper is known (see, for example, Patent Document 1). In such a double-sided printing thermal printer, in order to print on both sides of the thermal paper, two thermal heads are provided corresponding to each side.

Each thermal head is provided with a platen. The thermal paper passes between the thermal head and the platen, and printing is performed on the thermal paper by heat applied to the thermal head.
Japanese Patent Laid-Open No. 11-286147

  The double-sided printing thermal printer described above has the following problems. That is, the two platens are generally driven by the same drive motor. In such a case, unless the outer diameters of both platens are strictly controlled, the thermal paper is pulled or loosened. There was a risk of problems in printing.

  Accordingly, the present invention provides a double-sided printing thermal printer capable of smoothly transporting thermal paper without strictly managing the outer diameter of the platen when two platens are driven by the same drive motor. The purpose is that.

  In order to solve the above problems and achieve the object, the duplex printing thermal printer of the present invention is configured as follows.

  A thermal paper transport mechanism for transporting the thermal paper along the paper transport path, a first thermal head provided along the paper transport path and disposed opposite to the first surface of the paper transport path, and the first thermal head. A first platen roller disposed with respect to the thermal head across the paper conveyance path; provided along the paper conveyance path and on the thermal paper supply side with respect to the first thermal head; A second thermal head disposed opposite to the second surface side of the sheet conveying path; a second platen roller disposed across the sheet conveying path with respect to the second thermal head; the first platen roller; A drive mechanism for driving the second platen roller, and a first selective rotational force transmission mechanism for cutting the drive force from the drive mechanism only when the first platen roller rotates to the thermal paper supply side; the above 2 the platen roller only when rotating in the discharge side of the thermal paper, characterized in that a second selective torque transmission mechanism which disconnects the driving force from the drive mechanism.

  According to the present invention, when two platens are driven by the same drive motor, the thermal paper can be smoothly conveyed without strictly managing the outer diameter of the platen.

  FIG. 1 is a longitudinal sectional view schematically showing a duplex printing thermal printer 10 according to an embodiment of the present invention, and FIG. 2 is a side view showing a main part of a printing mechanism 30 incorporated in the duplex printing thermal printer 10. . In addition, P in FIG. 1 has shown the thermal paper which has a printing surface on both surfaces.

  The double-sided printing thermal printer 10 includes a casing 11, and includes a casing main body 12 that houses each mechanism, and an open / close lid 13 that can be opened and closed with respect to the casing main body 12.

  In the housing 11, a thermal paper roll R around which the thermal paper P is wound is rotatably supported, a thermal paper supply unit 20 that supplies the thermal paper P, and a printing mechanism that performs printing on the supplied thermal paper P. 30 are accommodated.

  The thermal paper supply unit 20 includes a holding unit 21 that holds the thermal paper roll R, and a feed mechanism 23 that transports the thermal paper P from the holding unit 21 to the printing mechanism 30 along the paper transport path 22.

  The printing mechanism 30 includes a driving mechanism 40, a first printing unit 50, a second printing unit 60, and a cutting mechanism 70 provided along the paper transport path 22.

  The drive mechanism 40 includes a drive motor 41 and a gear mechanism 42 that transmits the rotational force generated by the drive motor 41 to each part.

  The first printing unit 50 includes a first thermal head 51 disposed to face one side (first surface side) orthogonal to the extending direction of the sheet conveyance path 22, and the sheet conveyance path 22 to the first thermal head 51. The first platen 52 arranged opposite to each other, the spring 53 for urging the first thermal head 51 toward the first platen 52, and the rotational force from the gear mechanism 42 are selectively transmitted to the first platen 52. One-way gear 54 is provided. When the first platen 52 rotates in the reverse conveyance direction of the thermal paper P (arrow G in the figure), the one-way gear 54 becomes free rotation (free state) and cuts the rotational force, thereby conveying the thermal paper P in the conveyance direction (see FIG. When rotating in the middle arrow F), the gear mechanism 42 is engaged (locked state), and the rotational force is transmitted.

  The second printing unit 60 includes a second thermal head 61 disposed opposite to the other side (second surface side) orthogonal to the extending direction of the sheet conveyance path 22, and the sheet conveyance path 22 to the second thermal head 61. The second platen 62 disposed opposite to each other, the spring 63 that urges the second thermal head 61 toward the second platen 62, and the rotational force from the gear mechanism 42 are selectively transmitted to the second platen 62. And a one-way gear 64. When the second platen 62 rotates in the conveyance direction of the thermal paper P (arrow Q in the figure), the one-way gear 64 becomes free rotation (free state), cuts the rotational force, and reversely conveys the thermal paper P (see FIG. When rotating in the middle arrow F ′), it meshes with the gear mechanism 42 (locked state), and the rotational force is transmitted.

  The double-sided thermal printer 10 configured as described above performs printing as follows. That is, when an external print command is input, the drive motor 41 rotates in a certain direction. The rotation of the drive motor 41 drives the feed mechanism 23 via the gear mechanism 42 and drives the thermal paper P in the discharge direction.

  The gear mechanism 42 further rotates the first platen 52 in the conveyance direction of the thermal paper P. On the other hand, the rotational force of the second platen 62 is cut by the one-way gear 64 and is merely driven. As a result, a tensile force by the first platen 52 acts on the thermal paper P, and regardless of the outer diameter dimensions of the first platen 52 and the second platen 62, a constant tension is always maintained in the discharge direction. Be transported.

  In such a state, the thermal paper P is conveyed to the second printing unit 60. The second printing unit 60 starts printing on the second surface P2 of the thermal paper P. When the thermal paper P reaches the first printing unit 50, printing on the first surface P1 of the thermal paper P is started.

  Note that, when the thermal paper P is reversely conveyed for alignment of the printing position, the gear mechanism 42 rotates the second platen 62 in the reverse conveyance direction of the thermal paper P. On the other hand, the first platen 52 has a rotational force cut by the one-way gear 54 and is merely driven. As a result, a tensile force by the second platen 62 acts on the thermal paper P, and the reverse conveying direction is always maintained with a constant tension irrespective of the outer diameter dimensions of the first platen 52 and the second platen 62. It is conveyed to.

  When printing on both sides of the thermal paper P is completed, the thermal paper P is sent to the cutting mechanism 70 and cut.

  As described above, according to the double-sided printer 10 according to the present embodiment, printing can be performed on both sides of the thermal paper P, and the first platen 52 and the second platen 62 are driven by the same drive motor 41. In this case, even if the outer diameters of the first platen 52 and the second platen 62 are not strictly managed, the thermal paper P can be smoothly conveyed and reversely conveyed.

  It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

1 is a longitudinal sectional view schematically showing a double-sided printing thermal printer according to an embodiment of the present invention. The side view which shows the principal part of the printing mechanism integrated in the double-sided printing thermal printer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Duplex printing thermal printer, 20 ... Thermal paper supply part, 22 ... Paper conveyance path, 23 ... Feed mechanism (thermal paper supply mechanism), 30 ... Printing mechanism, 40 ... Drive mechanism, 50 ... 1st printing part, 51 ... First thermal head 52 ... first platen 53 ... first actuator 54 ... one-way gear 60 ... second printing section 61 ... second thermal head 62 ... second platen 64 ... one-way gear 70 ... cutting mechanism.

Claims (2)

A thermal paper transport mechanism for transporting thermal paper along the paper transport path;
A first thermal head provided along the paper transport path and disposed opposite to the first surface of the paper transport path;
A first platen roller disposed with respect to the first thermal head across the paper conveyance path;
A second thermal head provided along the paper conveyance path and on the thermal paper supply side with respect to the first thermal head, and disposed opposite to the second surface side of the paper conveyance path;
A second platen roller disposed across the paper transport path with respect to the second thermal head;
A drive mechanism for driving the first platen roller and the second platen roller;
A first selective rotational force transmission mechanism that cuts the driving force from the driving mechanism only when the first platen roller rotates to the thermal paper supply side;
A double-sided printing thermal system comprising: a second selective rotational force transmission mechanism that cuts the driving force from the driving mechanism only when the second platen roller rotates toward the thermal paper discharge side. Printer.   2. The duplex printing thermal printer according to claim 1, wherein at least one of the first selective rotational force transmission mechanism and the second selective rotational force transmission mechanism includes a one-way gear.

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