JP2008006679A - Double-side printing thermal printer - Google Patents

Abstract

When two platens are driven by the same drive motor, thermal paper can be smoothly conveyed without strictly managing the outer diameter of the platen.
A feed mechanism for supplying thermal paper P along a paper conveyance path, a first thermal head provided along the paper conveyance path, and a paper conveyance path with respect to the first thermal head. The first platen 52 disposed with the sheet 22 interposed therebetween, the second thermal head 61 provided along the sheet conveyance path 22, and the second plate disposed with the sheet conveyance path 22 interposed between the second thermal head 61 and the second thermal head 61. The product of the outer diameter and the rotation angle of the platen 62 and the first platen 52 is formed larger than the product of the outer diameter and the rotation angle of the second platen 62, and the driving force from the first platen 52 to the thermal paper P is the second. The driving force from the platen 62 to the thermal paper P is set larger.
[Selection] Figure 2

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 conveyance path, a second platen roller disposed across the sheet conveyance path with respect to the second thermal head, the first platen, and the second platen roller A drive mechanism for driving the two platens, wherein the product of the outer diameter and the rotation angle of the first platen is formed larger than the product of the outer diameter and the rotation angle of the second platen, and the heat sensitivity from the first platen. Drive to paper There, characterized in that it is larger than the driving force to the thermal paper from said second platen.

  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 the figure, P indicates a thermal paper having a printing surface on both sides.

  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. In the figure, F indicates the transport direction and F ′ indicates the reverse transport direction.

  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 and the spring 53 for urging the first thermal head 51 toward the first platen 52 are provided. The first platen 52 is driven by the gear mechanism 42.

  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. A second platen 62 arranged opposite to each other and a spring 63 for urging the second thermal head 61 toward the second platen 62 are provided. The second platen 62 is driven by the gear mechanism 42.

  The first winding angle θ <b> 1 of the thermal paper P to the first platen 52 is set to be larger than the second winding angle θ <b> 2 to the second platen 62. For this reason, the driving force from the first platen 51 to the thermal paper P becomes larger than the driving force from the second platen 62 to the thermal paper P.

  On the other hand, the peripheral speed of the first platen 52 is set so that the peripheral speed of the second platen 62 becomes faster. Specifically, the outer diameter dimension of the first platen 52 is set larger than the outer diameter dimension of the second platen 62, and the gears are set so that the rotational angular velocities of the first platen 52 and the second platen 62 are the same. It is set by the mechanism 42.

  In the above-described example, the case where the rotation angular velocities of the first platen 52 and the second platen 62 are the same has been described. That is, the product of the rotation angle and the outer diameter of the first platen 52 only needs to be set larger than the rotation angle, the outer diameter and the product of the second platen 62.

  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 and the second platen 62 in the conveyance direction of the thermal paper P. As described above, the peripheral speed of the first platen 52 is faster than the peripheral speed of the second platen 62, and the first winding angle θ <b> 1 of the thermal paper P to the first platen 52 is set to the second platen 62. It is set to be larger than the 2-winding angle θ2.

  Thereby, the driving force by the first platen 52 mainly acts on the thermal paper P, and the driving force by the second platen 62 becomes subordinate. Further, since the peripheral speed of the first platen 52 is larger than the peripheral speed of the second platen 62, the conveyance speed of the thermal paper P substantially coincides with the peripheral speed of the first platen 52. The thermal paper P between the two platens 62 is conveyed while generating a slight tensile force. When the tensile force acting on the thermal paper P becomes excessive, slip occurs between the thermal paper P on the second platen 62 side due to the difference between the first winding angle θ1 and the second winding angle θ2, and the thermal sensitivity is increased. There is no possibility that the paper P is torn.

  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.

  When the thermal paper P is conveyed in the reverse direction for the purpose of positioning the printing position, the first platen 52 and the second platen 62 rotate in the reverse direction. At this time, since the peripheral speed of the first platen 52 is set to be faster than the peripheral speed of the second platen 62, the thermal paper P is loosened, but the transport amount in the reverse direction is small. There is no practical problem.

  When printing on both sides of the thermal paper P is finished, the thermal paper P is sent to the cutting mechanism 70 by the feed mechanism 23 and cut.

  As described above, according to the double-sided printing thermal 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 connected by the same drive motor 41. In the case of driving, the occurrence of slack in the thermal paper P can be eliminated by always applying an appropriate tensile force to the thermal paper P between the first platen 52 and the second platen 62.

  FIG. 3 is a side view showing a main part of a printing mechanism 80 according to a modification of the printing mechanism 30 described above. 3, the same functional parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The printing mechanism 80 includes a pinch roller 81 that is disposed along the paper conveyance path 22 and adjacent to the first thermal head 51 and biases the thermal paper P toward the first platen 52. For this reason, the driving force from the first platen 51 to the thermal paper P becomes larger than the driving force from the second platen 62 to the thermal paper P.

  Accordingly, the driving force by the first platen 52 mainly acts on the thermal paper P, and the driving force by the second platen 62 becomes subordinate. Further, since the peripheral speed of the first platen 52 is larger than the peripheral speed of the second platen 62, the conveyance speed of the thermal paper P substantially coincides with the peripheral speed of the first platen 52. The thermal paper P between the two platens 62 is conveyed while generating a slight tensile force.

  Even in such a configuration, as described above, when the first platen 52 and the second platen 62 are driven by the same drive motor 41, the thermal sensitivity between the first platen 52 and the second platen 62 is always maintained. By applying a tensile force to the paper P, the occurrence of slack in the thermal paper P can be eliminated.

  In the printing mechanism 80, similarly to the printing mechanism 30, the first winding angle θ <b> 1 of the thermal paper P to the first platen 52 is set larger than the second winding angle θ <b> 2 to the second platen 62. However, the driving force from the first platen 51 to the thermal paper P may be made larger than the driving force from the second platen 62 to the thermal paper P only by the urging force of the pinch roller 81.

  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. The side view which shows the modification of the principal part of the printing mechanism.

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 ... 1st thermal head 52 ... 1st platen 53 ... 1st actuator 60 ... 2nd printing part 61 ... 2nd thermal head 62 ... 2nd platen 70 ... Cutting mechanism.

Claims (4)

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 and the second platen;
The product of the outer diameter and the rotation angle of the first platen is formed larger than the product of the outer diameter and the rotation angle of the second platen,
A double-sided thermal printer characterized in that a driving force from the first platen to the thermal paper is set to be larger than a driving force from the second platen to the thermal paper.   The double-sided printing thermal printer according to claim 1, wherein a first winding angle of the thermal paper to the first platen is set larger than a second winding angle of the second platen.   A double-sided printing thermal printer, characterized in that an urging member is provided along the sheet conveyance path and adjacent to the first thermal head and urges the thermal paper toward the first platen.   The double-sided printing thermal printer according to claim 3, wherein the urging member is a pinch roller.

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