JPS59124877A - Printing head retracting mechanism for thermal printer - Google Patents

Abstract

PURPOSE:To enable to retract a printing head without using a driving device for exclusive use, by rotating a carrier around a guide shaft in a direction for spacing away from a platen interlockedly with a movement in a returning direction of the carrier. CONSTITUTION:A lever 9 is provided with a gear 10 rotated coaxially with a driving shaft 2, and a planetary gear 11 is coupled to the gear 10. The lever 9 is provided also with a gear 12, and a sector gear 13 fixed to the guide shaft 3 is engaged with the gear 12. During a printing action, the driving shaft 12 is rotated counterclockwise, while the planetary gear 11 is maintained to be separated from the gear 12. At the time of a movement in the returning direction of the carrier, the shaft 2 is rotated clockwise, the planetary gear 11 performs a planetary motion in the direction of an arrow D to be engaged to the gear 12, which is rotated in the direction of an arrow E, and is moved upward along the sector gear 13.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a thermal print head printer, and particularly to a retraction mechanism for its print head.

(2) Background of the technology In a thermal printer, a carrier with a print head is supported on two parallel drive shafts (screw shafts) and a guide shaft (round bar shaft), and is slid along the platen by the rotation of the drive shafts. move. While the carrier is moving in one direction along the platen, the print head is pressed against the thermal paper or transfer ribbon on the platen to print. When the sliding movement of the carrier for one line at the printing position where the print head is pressed against the platen side is completed, the print head moves to the retracted position away from the platen, and the carrier slides in the return direction. Return to the first printing position.

(3) Conventional technology and problems In conventional thermal printers, the print head is mounted on the carrier so that it can be moved between two positions, the printing position and the retracted position, and the print head drive device is provided separately from the carrier drive device. With this print head driving device, the print head is in the printing position while the carrier is moving in the printing direction, and the print head is in the retracted position while the carrier is moving in the return direction.

In this way, using a dedicated drive device for the print head requires installation space, which is an obstacle to miniaturization of the device, and is also disadvantageous in terms of cost.

(4) Purpose of the Invention The present invention has been made in view of the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a print head retraction mechanism capable of retracting the print head with a simple structure without using a dedicated drive device. purpose.

(5) Structure of the Invention In order to achieve this object, in the present invention, a carrier having a print head facing a platen is supported on two shafts, a drive shaft and a guide shaft, and the print head of a thermal printer is retracted. In the mechanism, the drive shaft and the carrier are configured to be integrally rotatable in the direction away from the platen around the guide shaft in conjunction with the rotation of the drive shaft in the carrier return direction.

(6) Embodiment of the Invention FIG. 1 is a side view of a thermal printer according to the invention. The carrier l is supported on two parallel drive shafts 2 and guide shafts 3. The drive shaft 2 and the guide shaft 3 are connected to a common frame 4 at both ends thereof.
is attached and supported. The guide shaft 3 is supported by a side frame 5 fixed to the nonta main body. The print head 6 is fixed to the tip of the carrier 1. The print head 6 faces the platen 7, and 8 is thermal paper.
The carrier 1 is rotatable around the guide shaft 3 together with the frame 4 and the print head 6. During the printing operation, the carrier 1 presses the print head 6 toward the platen 7, and during the return operation, it rotates in the direction of the arrow 7 and prints. The head is moved away from the platen 7 and evacuated.

An example of a mechanism for retracting the print head in conjunction with the movement of the carrier is shown in FIG.
is installed. One end of the lever 9 is rotatably attached to the guide shaft 3. The lever 9 is equipped with a first gear 10 that rotates coaxially with the drive shaft 2. A planetary pawl 11 is connected to the first gear 10. Lever 9 also has a second
A gear 12 is provided. The second gear 12 meshes with a sector gear 13 fixed to the guide shaft 3. The planetary gear 11 and the second gear 12 engage with each other due to the planetary motion of the planetary gear 11, and the second tooth! When the second gear 12 rotates, the second gear 12 rolls on the sector gear 13, and the lever 9 rotates around the guide shaft 3 accordingly. The planetary gear 11 is provided with a suitable stopper mechanism or idle mechanism so that it can be held in a position sufficiently close to the second m-th gear 12 even during planetary movement in the direction away from the second tooth 7Jj12. The second gear 12 is provided with a suitable stopper mechanism or a nine-turn mechanism so as to stop after traveling a predetermined distance on the sector gear 13.

During printing operation, drive shaft 1 rotates counterclockwise,
The planetary gear 11 is held at a position apart from and close to the second gear 12, as shown in FIG. During the return movement of the carrier, the drive shaft 2 rotates clockwise (in the direction of arrow B), and the planetary gear 11 rotates in the direction of arrow C, performing planetary motion in the direction of the arrow. Therefore, the planetary gear 11 and the second tooth *12 engage, and the second gear 12 rotates in the direction of arrow E and rises along the sector gear 13. Therefore, the lever 9 rotates in the direction of arrow A around the guide shaft 3, and the lever 9
The carrier 1 rotates around the guide shaft 3, and the print head 6 moves away from the platen 7 and retreats.

(7) Detailed explanation of the invention As mentioned above, in the thermal printer according to the present invention, since the print head is retracted using the carrier driving means, a dedicated drive device for retracting the print head is required. Therefore, the structure of the IJ printer is simplified, the size can be reduced, and the cost can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a side view of a thermal printer according to the present invention, Fig. 2 is a side view of a thermal printer according to the present invention;
The figure is a configuration diagram of an example of a print head retraction mechanism according to the present invention. l...Carrier, 2...Drive shaft, 3...Guide shaft, 4...Frame, 5...Side frame, 6...Print head, 7...Platen, 9...
-Lever, -10...first gear, 11...planetary gear, 12...second gear, 13...sector gear.

Claims (1)

[Claims] 1. In a print head retraction mechanism of a thermal printer in which a carrier having a print head facing a platen is supported on two shafts, a drive shaft and a guide shaft. A print head for a thermal printer characterized in that the drive shaft and the carrier are integrally configured to be rotatable in a direction away from a platen in conjunction with the rotation of the drive shaft in the carrier return direction. Evacuation mechanism.