JPH0750211Y2 - Thermal printer - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a thermal printer, and in particular, makes it possible to reliably prevent electric field corrosion and the like of a thermal head that stands by while a voltage is applied to a heating element. Regarding a thermal printer.

[Conventional technology]

2. Description of the Related Art Conventionally, many thermal printers have been widely used which directly print on a thermal paper by a thermal head having a heating element formed thereon, or melt an ink ribbon to deposit ink on the paper to perform desired printing.

In such a thermal printer, for example, a cylindrical platen is rotatably arranged by a drive motor, and a thermal head having a heating element formed in the vicinity of the platen is contacted with and separated from the outer periphery of the platen by the heating element portion. It is arranged to be free.

Then, for example, a thermal paper is inserted between the platen and the thermal head, the drive motor is driven, the thermal head is brought into pressure contact with the paper, and a heating element of the thermal head is driven based on a predetermined print signal. Desired printing is performed by energizing and generating heat, and the platen is rotated by the rotational drive of the drive motor to feed the paper.

In such a conventional thermal printer, even if there is a blank sheet portion where printing is not performed at the end portion or the middle portion of the sheet in the sheet feeding direction, in order to improve the printing efficiency, a voltage is applied to the heating element of the thermal head. In some cases, the paper is fed in the state of being applied and is held in a standby state where printing is not performed. However, if the heating element is held in this standby state for a long time, there is a problem that the thermal head is corroded by the electric field because the heating element is pressed against the platen via the paper.

Therefore, conventionally, a cam mechanism driven by the reverse rotation of the drive motor is attached, and the drive motor is reversely rotated in the standby state to drive the cam to separate the thermal head from the platen.

[Problems to be solved by the device]

However, the conventional thermal printer requires many components such as a cam mechanism for separating the thermal head and the platen during standby of the thermal head to prevent electric field corrosion of the thermal head. Is complicated, and it is necessary to process and assemble each of these components with high accuracy, which makes it difficult to manufacture and increases the manufacturing cost.

The present invention has been made in view of these points, and it is possible to operate the heating element of the thermal head and the platen at a low cost with a simple structure during standby, and reliably prevent electric field corrosion of the thermal head. It is an object of the present invention to provide a thermal printer that can be used.

[Means for Solving the Problems]

To achieve the above object, the thermal printer according to the present invention comprises a cylindrical platen rotatably arranged by a drive motor, and a thermal head having a heating element formed in the vicinity of the platen. It is arranged so that it can freely come into contact with and separate from the outer periphery of the sheet, and inserts a sheet between the platen and the thermal head to cause the heating element of the thermal head to generate heat based on a predetermined print signal to achieve desired printing. A thermal printer that performs rotation of the drive motor in one direction, comprising: a bearing having an arcuate hole that rotatably supports the rotation shaft of the platen; and a gear that transmits the rotation of the drive motor to the rotation shaft of the platen. Is applied so that the rotation axis of the platen is located at one end of the arc hole and the platen is pressed against the heating element of the thermal head. A standby position where the rotation axis of the platen is located at the other end of the arc hole when the drive motor is rotated in the opposite direction, and the platen is separated from the heating element of the thermal head. It is characterized in that a platen position switching support mechanism for moving up to is provided.

[Action]

According to the present invention, when printing is performed, by rotating the drive motor in one direction, the rotation force applied to the rotation shaft of the platen supported by the platen position switching support mechanism causes the rotation shaft of the platen to rotate. The platen located at one end of the arc hole is moved and held to a printing position where the platen is pressed against the thermal head, and pressed against a heating element of the thermal head. On the other hand, when waiting without printing, the drive motor is rotated in the opposite direction to rotate the platen in the opposite direction to that during printing, so that the rotational force applied to the rotary shaft of the platen causes the platen to rotate. The rotary shaft is located at the other end of the arc hole, and the platen is moved to a standby position where the platen is separated from the thermal head, and is separated from the heating element of the thermal head.

Therefore, by positioning the rotary shaft of the platen at both ends of the arc hole of the platen position switching support mechanism according to the rotation direction of the drive motor, the platen can be reliably moved between the printing position and the standby position. Therefore, it is possible to reliably prevent electric field corrosion that occurs when the thermal head is brought into pressure contact during standby.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

1 and 2 show an embodiment of the present invention. A rotary shaft 2 is integrally fixed to both ends of a cylindrical platen 1, and both ends of the rotary shaft 2 are fixed to each other. Each has a rotary gear 3 attached thereto. The rotary shaft 2 of the platen 1 is rotatably supported so as to penetrate through each of the circular arc holes 4 of the bearing 5 that constitutes the platen position switching support mechanism. The arcuate hole 4 is formed in an arcuate shape around the transmission shaft 6 that is the rotation center of the transmission gear 7 that meshes with the rotary gear 3, and when the rotary shaft 2 is located at one end of the arcuate hole 4. (Solid line in FIG. 1) shows the heating element 11 of the thermal head 10.
The platen 1 is pressed against the print position, and the arc hole 4
When located at the other end of the head (chain line in Fig. 1)
The ten heating elements 11 and the platen 1 are set to a standby position where they are separated from each other. Further, in this embodiment, the transmission shaft 6 has substantially the same length as the rotary shaft 2, and the transmission gears 7 are provided at both ends thereof.
Is installed. A drive motor 8 is arranged on one end side of the platen 1, and a drive gear 9 that meshes with one of the transmission gears 7 is attached to an output shaft of the drive motor 8. . Further, the thermal head 10 is disposed so as to be able to come in contact with and separate from the outer peripheral surface of the platen 1, and the heat generating element 11 of the thermal head 10 presses the outer periphery of the platen 1 at the printing position of the platen 1. It is pressed by 13 so that it can abut.

Next, the operation of this embodiment will be described.

In this embodiment, as shown in FIG. 3, a thermal paper 12 is inserted between the platen 1 and the thermal head 10,
The drive motor 8 is rotationally driven in the forward direction (counterclockwise direction in FIG. 1). As a result, the transmission gear 7 rotates clockwise, and the rightward rotational force of the transmission gear 7 is applied to the rotation gear 3, and the platen 1 moves the rotation shaft 2 rightward along the arc hole 4. Is reached to the print position at the right end of the arc hole 4, and is rotated in the counterclockwise direction while being held at that position. At the same time, the heating element 11 of the thermal head 10 is brought into pressure contact with the platen 1. In this state, the heating element 11 of the thermal head 10 is caused to generate heat on the basis of a predetermined print signal, and the platen 1 is rotated by the rotation drive of the drive motor 8 to send the heat-sensitive paper 12 to the heat-sensitive paper 12. Apply the desired print.

When the thermal head 10 stands by with a voltage applied, as shown in FIG. 4, the drive motor 8 is rotated in the reverse direction, and the platen 1 is rotated via the transmission gear 7 and the rotary gear 3. Rotate in the opposite direction to when printing. As a result, the rotating shaft 2 of the platen 1 is moved to the standby position at the opposite end portion at the time of printing along the circular arc hole 4 of the bearing 5 by the rotational force in the reverse direction given to the platen 1, Is a heating element of the thermal head 10.
Separated from 11.

When printing is performed again, by rotating the drive motor 8 in the forward direction, the rotary shaft 2 of the platen 1 is printed along the arc hole 4 of the bearing 5 by the rotational force applied to the platen 1. Move to position, platen 1
Are pressed against the heating element 11 of the thermal head 10.

Therefore, in this embodiment, when the voltage is applied to the thermal head 10, the platen 1 is moved to a position separated from the heating element 11 of the thermal head 10 only by changing the rotation direction of the drive motor 8 that drives the platen 1. Since it is moved, it is possible to reliably prevent electric field corrosion that occurs when the thermal head 10 is brought into pressure contact during standby. Further, since the platen 1 can be separated by only changing the shape of the bearing 5 of the platen 1,
No extra components are required, the structure is simple, the processing and assembling work can be easily performed, and the manufacturing cost can be remarkably reduced.

Although the platen position switching support mechanism is formed by the arcuate hole 4 of the bearing 5 centered on the transmission shaft 6 in the above embodiment, it is rotated by a swing arm (not shown) centered on the transmission shaft 6. While supporting the shaft 2 rotatably,
The platen 1 may be swingably supported. Further, it can be similarly applied to a thermal printer that performs printing using an ink ribbon.

Further, the present invention is not limited to the above-mentioned embodiments, but can be modified as necessary.

[Effect of device]

As described above, in the thermal printer according to the present invention, the platen is held by the platen position switching mechanism,
Holds the platen at the printing position during printing,
Since the platen is held in the standby position by rotating the platen in the opposite direction to that during printing during standby, electric field corrosion of the thermal head can be reliably prevented. In addition, no extra components are required, the structure is simple, and processing and assembly work can be performed easily.
Moreover, there is an effect that the manufacturing cost can be remarkably reduced.

[Brief description of drawings]

1 to 4 show an embodiment of the thermal printer of the present invention. FIG. 1 is a side view, FIG. 2 is a perspective view of a platen portion, and FIG. FIG. 4 is a perspective view of a part during standby. 1 ... Platen, 2 ... Rotation axis, 3 ... Rotation gear, 4 ...
... Arc hole, 5 ... Bearing, 6 ... Transmission shaft, 7 ... Transmission gear, 8 ... Drive motor, 9 ... Drive gear, 10 ... Thermal head, 11 ... Heating element, 12 ... Paper.

Claims (1)

[Scope of utility model registration request] 1. A cylindrical platen is rotatably disposed by a drive motor, and a thermal head having a heating element formed in the vicinity of the platen is configured so that the heating element portion can be brought into contact with and separated from the outer periphery of the platen. In the thermal printer that performs desired printing by inserting a sheet between the platen and the thermal head and causing the heating element of the thermal head to generate heat based on a predetermined print signal, the rotation of the platen A bearing having an arcuate hole that rotatably supports the shaft and a gear that transmits the rotation of the drive motor to the rotation shaft of the platen, and the rotation of the platen when the drive motor is rotated in one direction. The shaft is located at one end of the arc hole to move the platen to a printing position where the platen is pressed against the heating element of the thermal head, and the drive motor is moved. A platen position switching support mechanism for moving the platen to a standby position where the rotation axis of the platen is located at the other end of the arc hole and is separated from the heating element of the thermal head when rotation in the opposite direction is applied. A thermal printer characterized by being provided.