JPS6189064A - Platen driving device for printer - Google Patents

Abstract

PURPOSE:To make attachment/detachment of a platen feasible and also make the whole printer compact by providing a rotary surface wave motor at least at one edge of the platen and giving rotary drive to the platen with the help of the motor. CONSTITUTION:A surface wave motor 207 has a support member 17 fixed to a frame 4a with an adhesive, etc., an elastic ring 15 and piezo electric element 14 fixed to the external circumferential surface of the elastic ring 15. The internal circumferential surface of the elastic ring 15 is fixed to the right of a platen 1 and the external circumferential surface of a rotary piece 16 formed in truncated cone is pressed by a spring 13. The piezoelectric element 14 oscillates by applying a high frequency voltage to generate a surface wave processing in the circumferential direction of the elastic ring 15. Thus the rotary piece 16 pressed to the elastic ring 15 by the spring 13 rotates in a prearranged direction, giving rotary drive to the platen 1 integrally formed with the rotary piece 16.

Description

[Detailed description of the invention] sailing keel The present invention relates to a platen drive device for a printer.

Mame lj town wire dot impact printer, daisy printer,
For printers such as inkjet printers, thermal transfer printers, or thermal printers.

A platen is provided so that predetermined printing can be performed by wrapping paper around the paper, and this platen is rotationally driven by a drive device.

FIGS. 6 and 7 show an example of the platen 1 and a conventional drive device for driving the platen. Platen 1 is its shaft 2
is rotatably supported by frames 4, 4a on both sides via bearings 3, 3a, and a knob 6 is provided at the left end of the shaft 2 for supplying and discharging printing paper such as letter paper and continuous forms. ing. The drive device for the platen 1 consists of a driven boot I fixed to the right end of the shaft, I5, and a frame 4a.
The motor 7 is supported by a motor 7 , a drive pulley 81 is fixed to the output shaft of the motor 7 , and a belt 9 is wound around both pulleys 5 and 8 so that the rotation of the motor 7 is transmitted to the platen 1 . Further, the conventional drive device shown in FIG. 8 includes a motor 107 having a rotor 11 fixed to a shaft 2 on the right end side of the platen, and a stator 10 on the frame 4a side.
The rotation of the platen 1 is controlled by this motor 107.

As the above-mentioned motor, a permanent magnet type or hybrid type stepping motor is used because it is necessary to obtain a predetermined rotational resolution, rotational torque, and speed according to the printer's line feed specifications, and also to perform forward and reverse rotation. was common.

Incidentally, regardless of the type of printer, it is desirable that the platen used in a printer be constructed so that it can be easily attached and detached for purposes such as cleaning and maintenance. However, when the drive device shown in FIGS. 6 and 7 is used, it is necessary to remove the belt 9 from the pulleys 5 and 8 when removing the platen 1.

At this time, since the belt 9 is stretched with a predetermined initial tension, it is necessary to remove the mounting screw of the driven pulley 5, which is a very complicated operation. Furthermore, the device constituted by the pulleys 5, 8, belt 9, and motor 7 is difficult, making it difficult to downsize the printer. A drive device using a transmission device consisting of gears instead of a transmission device consisting of a boob and a belt is also known, but although it is relatively easy to attach and detach the platen in this device, there is backlash between the gears. Therefore, there is an unavoidable drawback that the rotational angle precision of the platen and, by extension, the paper feeding precision are reduced. In the drive device shown in FIG. 8, due to the structure of the motor 107, its axial size is increased, and the frame 4,
The distance L between the plates 4a and 4a has to be long, and the platen 1
It cannot be said that the problem of the difficulty in attaching and detaching can be solved.

(5) An object of the present invention is to provide a platen drive device for a printer that eliminates the above-mentioned conventional drawbacks.

The present invention proposes a configuration in which a rotary surface wave motor is provided at at least one end of the platen, and the platen is rotationally driven by this motor.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a shaft 2 on the left side of a platen 1 is rotatably supported by a frame 4 via a bearing 3, as in the prior art. Further, a pressurizing spring 13 is disposed between a thrust bearing l2 made of, for example, lubricating resin, which is in close contact with the bearing 3 of the shaft 2, and the end surface of the platen 1.
The platen 1 is urged by the spring 13 toward the right in the figure as indicated by an arrow P. Spring 1
3, a wave temporary spring or the like can be used as appropriate in addition to the compression spring shown. A knob 6 is provided at the left end of the shaft 2 as in the conventional case.

A rotary surface wave motor 207 according to the present invention is provided on the right end side of the platen 1. The surface wave motor 207 shown in FIG. 1 includes a support member 17 made of resin such as acrylic and fixed to the frame 4a with an adhesive or the like, and a support member 17 that is similarly fixed and held to the support member 17 with an adhesive or the like. The piezoelectric body 14 is fixed to the inner circumference of the elastic ring 15 and the right end of the platen 1, and is formed into a truncated conical shape. The outer circumferential surface of the rotating body 16 is pressed against the pressing force of the spring l3. The elastic ring 15 is made of metal such as brass, and the piezoelectric body 14 is formed into a ring shape by arranging a plurality of segment-shaped piezoelectric elements in the circumferential direction. By applying a high frequency voltage at the timing of
vibrates, causing a surface wave (progressive wave) that travels in the circumferential direction of the elastic ring 15. As a result, the rotating body 16 pressed against the elastic ring 15 by the spring 13 rotates in a predetermined direction, and the platen 1 integrated with the rotating body 16 is rotationally driven. A good feature of the surface wave motor itself is that the rotation direction and rotation angle of the platen 1 can be controlled by controlling the phase, voltage value, frequency, application timing, time, etc. of the high-frequency voltage applied to the piezoelectric body 14. As is known.

The rotating body 16 is fixed to the end surface of the platen 1 with a key and a keyway, or with an adhesive or the like.

The material of the rotating body l6 is selected from rubber, synthetic resin, etc. so that the rotational driving force from the elastic ring 15 is efficiently transmitted. In this case, in order to achieve efficient transmission, it is necessary to increase the hardness of the rotating body 16 to a certain extent, and on the other hand, the platen 1 is fixed to the type of printer in which it is used, e.g. Alternatively, due to the demands of various types of printers such as thermal transfer printers, it is necessary to make the rubber hardness suitable for these printers. When the required hardnesses match or almost match, the platen itself can be brought into pressure contact with the elastic ring 15 without providing an independent rotating body 16. In this way, it is possible not only to reduce costs but also to improve dimensional accuracy.

As described above, if the drive device composed of the spring 13 and the surface wave motor 207 is used, the platen and the motor 207 can be attached and detached by simply separating the platen 1 from the elastic ring 15 when removing the platen 1. In addition, the motor 207 can be configured to have a small size, so the distance between the frames 4 and 48 can also be reduced, and transmission devices such as pulleys, belts, and gears are no longer required, making the drive device and the entire printer more compact. can be converted into

In the embodiment shown in FIG. 1, the elastic ring 15 is formed in the shape of a cup with a hole in the center, and the piezoelectric body 14 is disposed on the outer peripheral surface of the elastic ring 15, so that the shape of the piezoelectric body 14 is also cup-shaped. It becomes somewhat difficult to manufacture each piezoelectric element. Therefore, in the embodiment shown in FIG. 2, the right end of the elastic ring 15 is formed flat, and the piezoelectric body 14
to be fixed. In this way, the overall shape of the piezoelectric body 14 can be made into a flat disk shape, and its manufacture can be facilitated.

In the surface wave motor 207 shown in FIG. 3, the piezoelectric body 14, the elastic ring 15. The arrangement of the rotating body 16 is reversed to that shown in FIG.
It is arranged on the inner circumferential surface of.

For this reason, the piezoelectric body 14 is covered from the outside by the elastic ring 15, and when a hand or a jig or the like inadvertently comes into contact with the piezoelectric body 14 when assembling the printer, a shock may be applied to the piezoelectric body 14, or it may be damaged. You can prevent the inconvenience caused by

In each of the embodiments described above, the rotating body 16 and, therefore, the platen 1 are supported by the elastic ring 15 by forming conical surfaces on the rotating body 16 and the elastic ring 15. However, in the embodiment shown in FIG. Shaft 2 on the right side of platen I
is rotatably supported on a frame 4a via a bearing 3a as in the conventional case. Therefore, the elastic ring 15, the rotating body 16, and the piezoelectric body 14 of the motor 207 can all be formed into a flat ring shape or a cylindrical shape, and the piezoelectric body 14 can be manufactured easily.

However, in the 11th embodiment, the platen 1 is connected to the frame 4a.
When removing the shaft 2 from the frame 4a, make sure that the shaft 2 does not interfere with the elastic ring 15 and the piezoelectric body 14 fixed to the frame 4a side.
It is necessary to move the platen 1 along with the shirt I-2 to the left in the axial direction by ΔQ1, and such a relief phenomenon Δfl,
If this is necessary, it becomes necessary to increase the distance between the frames 1.4.4a.

The embodiment shown in FIG. 5 is an improvement on this, in which the frame 4a is drawn so that the shirt 1 to support portions of the frame 4a protrude toward the platen 1.

In this way, the amount of shift ΔQ2 of the platen required when attaching and detaching the platen 1 can be made smaller than ΔIII+ (FIG. 4), and the distance between the frames 4 and 4a can be made smaller.

The other configurations in FIGS. 2 through 5 are the same or substantially the same as in FIG. 1. That is, the support member 17, the elastic ring 15, and the piezoelectric body 14 are fixed to the frame 4a side, and the rotating body 16 is fixed to the platen 1 side, and the rotating body 16 is pressed against the elastic ring 15 by the spring 13. In this case, the elastic ring 15 may be fixed to the support member 17 as shown in FIGS. 1 to 3, and the piezoelectric body 14 may be fixed to the ring 15, or the piezoelectric body 14 may be fixed to the ring 15 as shown in FIGS. 4 and 5. Alternatively, the piezoelectric body 14 to which the elastic ring 15 is fixed may be fixed to the support member 17. Of course, it is also possible to fix and support both the piezoelectric body 14 and the elastic ring 15 directly on the support member 17.

In each of the above embodiments, the surface wave motor 207 is provided only on one side of the platen l, but a surface wave motor is also provided on the other side, and the elastic ring is connected to the platen itself or this by using another pressurizing spring. It is also possible to press a fixed rotating body and use both motors selectively, for example, the first motor is used for forward rotation of the platen, and the second motor is used for reverse rotation. It is. Further, as is known per se, the present invention can be applied without any problem even when the shaft 2 of the platen and the knob 6 are connected via a clutch.

The concept of the present invention itself is applicable not only to the platen of a printer but also to a device that drives a rotating drum such as a copying machine.

Hiromi According to the present invention, the platen can be easily attached and detached.

Moreover, the entire printer can be made more compact.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view showing an example of a platen and a drive device according to the present invention, and FIGS. 2 to 5 are views. 6 is a partial sectional front view similar to FIG. 1 showing a conventional configuration example, and FIG. 7 is a right side of FIG. 6 with the frame removed. side view,
FIG. 8 is a partially sectional front view similar to FIG. 6 showing another conventional example. 1...Platen 207...Surface wave motor Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8

Claims (2)

[Claims] (1) A platen drive device for a printer, characterized in that a re-platen is rotationally driven by a rotary surface wave motor provided on at least one end side of the platen. (2) The platen drive device according to claim 1, wherein the surface wave motor includes an elastic ring fixed to a frame and a piezoelectric body.