JP5338732B2 - printer - Google Patents

Description

  The present invention relates to a printer that presses a platen roller against a print head.

  Conventionally, in a printer, printing paper sandwiched between a print head and a platen roller is conveyed by friction with a rotating platen roller. When the printing paper is not continuous paper (web) but single sheet paper (sheet), there is printing paper (single sheet paper) between the print head and the platen roller while the platen roller is rotating. And a state where there is no printing paper (cut sheet paper) between the print head and the platen roller are alternately repeated. When the printing paper (cut sheet paper) is not set, there is no printing paper (cut sheet paper) between the print head and the platen roller while the platen roller is rotating.

  As such, when there is no printing paper (cut sheet paper) between the print head and the platen roller, the print head and the platen roller are directly pressed without sandwiching the printing paper (cut sheet paper). The friction force generated between the print head and the platen roller becomes very large.

  Therefore, in the “thermal printer head pressure contact mechanism” described in Patent Document 1, the pressure pressure of the thermal head pressed against the platen roller is switched between printing and non-printing. When printing is not performed, the pressure is switched so that the pressure contact pressure is weak or no load is applied.

JP 2005-280017 A

  However, in a printer in which the platen roller is pressed against the print head, the relationship between the press-contacting side and the press-contacting side between the print head and the platen roller is “the head pressing mechanism of the thermal printer” described in Patent Document 1. Therefore, the “head pressing mechanism of a thermal printer” described in Patent Document 1 cannot be applied. Further, in the “thermal printer head pressure contact mechanism” described in Patent Document 1, the pressure contact mechanism is complicated, a gear for a pressure contact operation and a power source are required, and the apparatus becomes large.

  Therefore, in a printer in which the platen roller is pressed against the print head, if there is no printing paper (cut sheet paper) between the print head and the platen roller during rotation of the platen roller, the print head and the platen roller Since the frictional force generated between the platen roller and the platen roller continues to rotate, the motor serving as the driving force for the rotation has to be large.

  Accordingly, the present invention has been made in view of the above-described points, and is a printer that presses a platen roller against a print head, and does not have a sheet of paper between the print head and the platen roller. It is an object of the present invention to provide a printer that can suppress the fluctuation of the frictional force generated between the print head and the platen roller without complicating or increasing the size of the apparatus even when the printer is in a state. .

In order to solve this problem, the invention according to claim 1 is directed to a drive motor, a drive gear mechanism including one or a plurality of drive gears for transmitting a drive force of the drive motor, and the drive gear. adjacent mechanism, said either one of the driving gears constituting the driving gear and one platen gear combined, and a platen shaft as the rotational axis of the platen gear, a platen roller which is axially applied by the platen shaft, said A printer comprising: a print head disposed at a position facing the platen roller; and a pressure contact mechanism for pressing the platen roller against the print head, wherein the printer includes a print head and the platen roller. The drive gear mechanism is moved from the downstream side in the direction in which the cut sheet paper is conveyed by the rotation of the platen roller. The Rukoto adjacent to the Ngiya, said the direction in which the platen roller is pressed against the printing head is transmitted to the driving load in the opposite direction from the drive gear mechanism to the platen gear, said and said and said drive gear mechanism platen gear It is arranged on both sides of the platen roller .

  In the printer of the invention according to claim 1 having such a feature, since the platen roller is pressed against the print head by the press contact mechanism, the direction from the platen roller toward the print head (hereinafter referred to as “press contact direction”). Pressure) is generated between the print head and the platen roller. On the other hand, the cut sheet sandwiched between the print head and the platen roller is conveyed by friction with the rotating platen roller, but the drive gear mechanism is adjacent to the platen gear from the downstream side in the conveyance direction. . Therefore, at the portion where the drive gear mechanism and the platen gear mesh with each other, the driving force of the drive motor is transmitted from the drive gear mechanism to the platen gear in the direction opposite to the “pressure contact direction”.

  Therefore, when there is no sheet paper between the print head and the platen roller and the frictional force generated between the print head and the platen roller increases, the drive gear mechanism also has a large driving load. However, the large driving load (the force) is transmitted from the driving gear mechanism to the platen gear in the direction opposite to the “pressure contact direction”. Therefore, a force that is returned in a direction opposite to the “pressing direction” acts on the platen roller that is axially attached by the platen shaft that is the rotation shaft of the platen gear. And the balance relationship of each force mentioned above is formed, and the frictional force which became large between a print head and a platen roller will be settled in a moment, and will be in the stable state.

In the printer of the invention according to claim 1 having such characteristics, a driving gear mechanism and the platen gear that was disposed on both sides of the platen roller, the platen shaft is pivotally attached to the platen roller as a rotation shaft of the platen roller Is supported on both sides of a print head disposed at a position facing the platen roller.

  That is, in the present invention, the printer presses the platen roller against the print head, and even when the sheet paper is not in a state between the print head and the platen roller during the rotation of the platen roller. Therefore, it is possible to suppress the fluctuation of the frictional force generated between the print head and the platen roller without complicating and increasing the size of the apparatus.

  In the present invention, if the drive gear mechanism and the platen gear are arranged on both sides of the platen roller, the present invention can be applied even to a print head having a large print width. The large driving load applied to the gear mechanism can be halved.

FIG. 2 is a front view schematically illustrating the periphery of a thermal print head included in the printer according to the embodiment of the present invention. FIG. 2 is a plan view schematically illustrating the periphery of a thermal print head included in a printer according to an embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view schematically showing the periphery of a thermal print head 17 included in a printer according to an embodiment of the present invention.

  As shown in FIG. 1, the printer according to the present embodiment includes a drive motor 11, a gear 12 fitted on a shaft of the drive motor 11, a drive gear mechanism 13 meshed with the gear 12, and a drive gear mechanism 13. And a meshed platen gear 14. Accordingly, the driving force of the driving motor 11 is transmitted to the platen gear 14 via the gear 12 and the driving gear mechanism 13.

  The drive gear mechanism 13 may be composed of one gear or may be composed of two or more gears.

  Further, as shown in FIG. 1, the printer according to the present embodiment is arranged at a position facing the platen roller 16, a platen shaft 15 that is a rotation shaft of the platen gear 14, a platen roller 16 that is pivotally attached by the platen shaft 15. And a thermal print head 17 provided. The thermal print head 17 is fixed to the mounting plate 18. The mounting plate 18 constitutes a part of the transport path 19. On the transport path 19, the cut sheet S that is a printing sheet moves.

  Furthermore, as shown in FIG. 1, the printer according to the present embodiment includes a spring 20 for pressing the platen roller 16 against the thermal print head 17. The spring 20 urges the platen shaft 15, and the urged platen shaft 15 can move in the urging direction along the guide groove 23 provided in the plate 22 of the guide portion 21. It is.

  That is, in the printer according to the present embodiment, the platen shaft 15 is urged by the spring 20, and the platen roller 16 that is axially attached by the urged platen shaft 15 moves along the guide groove 23. The platen roller 16 is in pressure contact with the thermal print head 17.

  That is, the spring 20, the platen shaft 15, and the guide portion 21 constitute a “pressure contact mechanism”, and the platen roller 16 is pressed against the thermal print head 17 by the “pressure contact mechanism”. As a result, a downward pressure contact force F <b> 1 (and its reaction force F <b> 1) from the platen roller 16 toward the thermal print head 17 is generated between the thermal print head 17 and the platen roller 16. Yes.

  On the other hand, in the printer according to this embodiment, the cut sheet S sandwiched between the thermal print head 17 and the platen roller 16 is conveyed by the friction of the rotating platen roller 16. The rotation direction D1 of the platen roller 16 is clockwise in FIG. 1 due to the arrangement relationship described later between the drive gear mechanism 13 and the platen gear 14. Therefore, the conveyance direction D2 of the cut sheet S is from left to right in FIG.

  In the printer according to the present embodiment, as shown in FIG. 1, the drive gear mechanism 13 is disposed adjacent to the platen gear 14 from the downstream side in the conveyance direction D2 of the cut sheet S. Yes. In FIG. 1, the right side of the platen gear 14 and the left side of the drive gear mechanism 13 are adjacent to each other. Therefore, in the portion where the drive gear mechanism 13 and the platen gear 14 mesh, the driving force of the drive motor 11 is transmitted from the gear mechanism 13 to the platen gear 14 in the upward direction, which is the opposite direction to the downward direction.

  Therefore, in the printer according to the present embodiment, the cut sheet S is not present between the thermal print head 17 and the platen roller 16 and is generated between the thermal print head 17 and the platen roller 16. When the frictional force L1 is increased, a large driving load (force) L2 is also applied to the driving gear mechanism 13. However, the large driving load L2 is transmitted from the driving gear mechanism 13 to the platen gear 14 in the upward direction, which is opposite to the downward direction, and becomes a force F2 that pushes the platen gear 14 upward. Therefore, a force that returns to the upper direction, which is the opposite direction to the lower direction, acts on the platen roller 16 that is axially attached by the platen shaft 15 that is the rotation axis of the platen gear 14. And the balance relationship of each force F1, F2, L1, L2 mentioned above is formed, and the frictional force L1 which became large between the thermal type print head 17 and the platen roller 16 will be settled in a moment, and will be in the stable state.

  That is, the printer according to this embodiment is a printer that presses the platen roller 16 against the thermal print head 17, and the platen roller 16 is rotated between the thermal print head 17 and the platen roller 16 during rotation. Even when the cut sheet S is changed from being present, it is possible to suppress the fluctuation of the frictional force L1 generated between the thermal printing head 17 and the platen roller 16.

  That is, in the printer according to the present embodiment, when the frictional force L1 generated between the thermal print head 17 and the platen roller 16 is increased, the drive load (force) L2 applied to the drive gear mechanism 13 is also increased. At this time, however, the platen roller 16 moves in the direction of releasing from the thermal print head 17 (upward), and accordingly, the downward pressure contact force (force of the platen roller 16 toward the thermal print head 17). ) As F1 (and its reaction force F1) decreases, the frictional force L1 that increases between the thermal print head 17 and the platen roller 16 is also instantaneously accommodated. As a result, the platen roller 16 rotates under a state in which the above-mentioned forces F1, F2, L1, and L2 are balanced, so that the frictional force L1 generated between the thermal print head 17 and the platen roller 16 is reduced. Fluctuation is small, and in a state where the cut sheet S is sandwiched between the thermal print head 17 and the platen roller 16, the frictional force L1 generated between the thermal print head 17 and the platen roller 16 is present. Is not increased, and the downward pressure contact force F1 (and its reaction force F1) from the platen roller 16 toward the thermal print head 17 does not decrease, so printing is performed in an optimum state. It becomes possible.

  Thereby, even if it does not replace the drive motor 11 with a thing with a big driving force, since a platen roller can be rotated continuously, the increase in the emitted-heat amount and enlargement can be prevented.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning.

  For example, as shown in FIG. 2, the drive gear mechanism 13 and the platen gear 14 may be disposed on both sides of the platen roller 16. FIG. 2 is a plan view schematically illustrating the periphery of the thermal print head 17 included in the printer according to the embodiment of the present invention. In FIG. 2, the same parts as those in FIG.

  That is, in the printer having the configuration shown in FIG. 2, the drive gear mechanism 13 and the platen gear 14 are disposed on both sides of the platen roller 16, so that the platen roller 16 is axially attached as the rotation axis of the platen roller 16. A platen shaft 15 is supported on both sides of a thermal print head 17 disposed at a position facing the platen roller 16.

  Therefore, the thermal print head 17 having a large print width can be applied, and the large drive load L2 (see FIG. 1) applied to the two drive gear mechanisms 13 can be halved. Can do. In FIG. 2, the configuration for transmitting the driving force of the drive motor 11 to the drive gear mechanism 13 located on the opposite side of the drive motor 11 is omitted.

DESCRIPTION OF SYMBOLS 11 Drive motor 13 Drive gear mechanism 14 Platen gear 15 Platen shaft 16 Platen roller 17 Thermal print head 20 Spring D2 Single sheet paper conveyance direction S Single sheet paper

Claims (1)

A drive motor;
A drive gear mechanism composed of one or a plurality of drive gears for transmitting the drive force of the drive motor;
One platen gear combined with any one drive gear adjacent to the drive gear mechanism and constituting the drive gear;
A platen shaft that is a rotation shaft of the platen gear;
A platen roller mounted by the platen shaft;
A print head disposed at a position facing the platen roller;
A pressure contact mechanism for pressing the platen roller against the print head,
The Rukoto is adjacent the drive gear mechanism to the platen gear from the downstream side in the direction noncontinuous media sandwiched between the print head and the platen roller is conveyed by the rotation of the platen roller, the platen roller A driving load is transmitted from the driving gear mechanism to the platen gear in a direction opposite to the direction in which it is pressed against the print head;
A printer, wherein the drive gear mechanism and the platen gear are arranged on both sides of the platen roller .

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