JPS6337973A - Preventer for deformation of platen in printer - Google Patents

Abstract

PURPOSE:To enable the drive motor of a cam body to be used both as the drive motor of a platen, by a method wherein the movable component capable of moving a printing head at both a printing position and a separate position is provided, and the printing head is moved to the separate position only when a platen is rotated in the direction reverse to a printing paper feed direction. CONSTITUTION:When a printer is used, the platen 1 is rotated in the arrow A direction. A cam body 8 is controlled with a stopper 10 and at the same time a printing head is at the printing position where it is pressed by the platen 1. When the platen 1 is rotated by a specified angle theta in the reverse A direction after the finish of printing, the cam body 8 is also rotated together with the platen 1 via a one-way clutch 9 and that rotary position is held. The printing head 5 is pressed by this cam body 8, is separated from the platen 1 and reaches a separate position. Thereby, the cam body 8 can be driven with the drive motor 4 of the platen 1 and the motor exclusively used for driving the cam body 8 becomes not to be required.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a device for preventing deformation of a platen in, for example, a thermal line printer.

(Conventional Technique v/4) Conventionally, in a thermal line printer, characters are printed by pressing a print head (using a heating element) onto printing paper that is guided and supported by a platen. In this case, the platen is in a deformed state because it is pressed against the print head. In particular, when the printer is not used for a long time, this deformed state continues, and there is a risk that the platen will be permanently deformed.

In order to solve this problem, conventionally, as shown in FIGS. 5 and 6, the print head 5, which is pressed against the platen 1 by a spring 7, is rotated by the rotation of the cam body 8 when the printer is not in use. It is now separated from the

(Problems to be Solved by the Invention) However, since the dedicated motor 11 for driving the cam body 8 is provided separately from the platen drive motor 4, the manufacturing cost increases and the structure becomes complicated. was there.

The present invention solves this problem by improving the cam body drive motor so that it can also be used as a platen drive motor.

Structure of the Invention (Means for Solving Problems) That is, the present invention includes a rotatable platen that guides and supports printing paper, a print head that prints characters on the printing paper on this platen, and a rotatable platen that rotates this platen. a platen drive motor, and a platen drive mechanism between the platen and the drive motor moves the print head between a print position where the print head is in pressure contact with the platen and a separate position where the print head is separated from the platen. A movable member is provided, and an actuating member is provided that operates the movable member so as to move the print head at the printing position to the separated position only when the platen rotates in a direction opposite to the printing paper feeding direction. be.

(Function) When the printer is used, the platen is rotated in the print paper feeding direction by the platen drive motor, and the print head is at the printing position where it is pressed against the platen. After printing is completed, if the platen rotates in the opposite direction to the printing paper feed direction,
Does it work? The movable member moves the print head from the print position to the separated position by the action of the A shrine. This causes the print head to separate from the platen. When the platen rotates again from this printer usage state, the printer returns to the printer usage state and printing can be started.

(Example) First, a first example of the present invention will be described with reference to FIGS.

The platen 1 is attached to a rotation center shaft 2, and is rotated by a platen drive motor 4 interlocked with the rotation center shaft 2 via a platen drive deceleration mechanism 3 (details are omitted). This platen drive motor 4 is capable of forward and reverse rotation and has self-holding torque. The print head 5 is attached to the support shaft 6
When the printer shown in FIG. When the platen drive motor 4 rotates forward, the platen 1 rotates in the direction of arrow A to guide and support the printing paper P. The print head 5 prints characters on the print paper P on the platen 1 at the printing position.

A cam body 8 (movable member) is supported on the rotation center shaft 2 of the platen 1 via a one-way clutch 9 (actuating member), and this cam body 8 is not shown in FIG. 4 rotates in the opposite direction and the platen 1 moves together with the platen 1 only when the platen 1 rotates in the direction opposite to the printing paper feeding direction A. By this rotation of the cam body 8, the print head 5 is pushed against the elasticity of the spring 7, and is separated from the platen 1 by a certain gap G. Even if the power to the platen drive motor 4 is turned off at this separated position of the print head 5, the rotational position of the cam body 8 is maintained by its self-holding torque.

Further, a stopper 10 is provided corresponding to the cam body 8,
When the platen 1 rotates in the printing paper feeding direction A when the printer shown in FIG. The rotation of the is now regulated. The angle θ at which the cam body 8 rotates from the state shown in FIG. 1 to the state shown in FIG. 2 is determined by the rotation speed of the platen drive motor 4.

Now, when the printer shown in FIG. 1 is used, the platen 1 rotates in the direction of arrow A, the cam body 8 is regulated by the stopper 10, and the print head 5 is in pressure contact with the platen 1 at the printing position.

After printing is completed, when the platen 1 rotates by a certain angle θ in the direction of the arrow A, the cam body 8 also rotates together with the platen 1 via the one-way clutch 9, and the rotation position is adjusted. is retained. The print head 5 is connected to this cam body 8.
is pushed away from the platen 1 to a separated position.

When the platen 1 rotates again in the direction of arrow A from the printer operating state shown in FIG. 2, it returns to the state shown in FIG.
Printing can be started.

In particular, in the first embodiment, the cam body 8 can be driven by the drive motor 4 of the platen 1, and a dedicated motor for driving the cam body 8 is not required.

In the second embodiment shown in Fig. 3.4, the cam body 8 of the first embodiment is changed and the strips 1 to 10 are eliminated, and the cam body 8 has four corners of a square shaped like a flat surface. It has a chamfered shape.

When the printer shown in FIG. 3 is used, the pressing parts 8a at the four corners of the cam body 8 are separated from the print head 5, the print head 5 is in the printing position where it is pressed against the platen 1, and the platen 1 is
Even if it rotates in the direction of the arrow, the cam body 8 does not rotate due to the action of the one-way clutch 9.

After printing is completed, when the platen 1 rotates 90 degrees in the direction of arrow A, as shown in FIG. It is in contact with the print head 5 and its rotational position is maintained. The print head 5 is pushed by this pressing portion 8a to a separated position away from the platen 1. When the platen 1 is further rotated 90 degrees in the direction of arrow A from the printer operating state shown in FIG. 4, it returns to the state shown in FIG.
Printing can be started.

In particular, in the second embodiment, the cam body 8 is similar to the first embodiment.
Not only does this eliminate the need for a drive motor, but also the platen drive motor 4 does not require a self-holding torque, making the motor 4 inexpensive.

Effects of the Invention In short, according to the present invention, the platen drive motor can also be used as the drive motor for the cam body, so there is no need for a dedicated motor for driving the cam body, reducing lJ'IN costs and making the structure simple. effective.

[Brief explanation of drawings]

Fig. 1 is an explanatory view of the operation showing the printer usage state in the first embodiment, Fig. 2 is an action explanatory diagram showing the printer usage state in the same manner, and Fig. 3 is an action explanatory diagram showing the printer usage state in the second embodiment. , FIG. 4 is an explanatory view of the operation of the printer, and FIGS. 5 and 6 are explanatory views of the operation of the conventional printer, respectively. In the drawing, 1 is a platen, 2 is a platen rotation center shaft, 3 is a platen drive reduction mechanism, 4 is a platen drive motor, 5 is a print head, 8 is a cam (a movable member), 9 is a one-way clutch (operating member), P is the printing paper, A is the printing paper feeding direction, and G is the gap.

Claims (1)

[Claims] 1. A rotatable platen that guides and supports printing paper, a print head that prints characters on the printing paper on this platen, and a platen drive motor that rotates this platen, comprising: The platen drive mechanism between the drive motor is provided with a movable member capable of moving the print head between a printing position where the print head is in pressure contact with the platen and a separate position where the print head is separated from the platen. A device for preventing platen deformation in a printer, comprising: an operating member that operates the movable member to move the print head at the printing position to the separated position only when the platen is rotated in a direction opposite to the paper feeding direction. 2. The platen deformation prevention device in a printer according to claim 1, wherein the platen drive motor is capable of forward and reverse rotation. 3. The printer according to claim 1, wherein the movable member is a cam body supported on the rotation center axis of the platen, and the operating member is a one-way clutch provided between the rotation center axis and the cam body. Platen deformation prevention device.