JPS6256155A - Printing head - Google Patents

Abstract

PURPOSE:To provide a small-sized high-speed printing head with a good printing quality and reduced noise, by constituting a rotational displacement generating mechanism of a rotational displacement generating part supported at the predetermined center of rotation in a freely revolvable manner and a transmission means transmitting linear displacement to a predetermined point of the rotational displacement generating part. CONSTITUTION:A laminated type piezoelectric element 1 being a displacement generating means is fixed to a frame 2 at one end thereof and a top piece 3 is connected to the other end of said piezoelectric element 1. A rotational displacement generating part 4 is mounted to the frame 2 so as to be made freely revolvable around the center 2c of rotation and leaf springs 2a, 2b are provided between the rotational displacement generating part 4 and the frame 2 while leaf springs 3a, 3b are provided between the top piece 3 and the rotational displacement generating part 4. When voltage is applied to the piezoelectric element 1, the top piece 3 is displaced in the direction shown by an arrow F nd the rotational displacement generating part 4 is rotated in the direction shown by an arrow G around the center 2a of rotation and printing operation is performed by a printing wire 6 through a lever 5. The relative position of the top piece 3 and the center 3a and that of the frame 2 and the center 2c of rotation are kept constant and the ratio of an arm length L to an interval D, that is, a displacement magnification ratio is large.

Description

TECHNICAL FIELD This invention relates to printheads, and more particularly to printheads for use in dot matrix printers.

Recent PCs have print heads that print characters, figures, etc. using multiple print wires.

Due to the OA boom, many multi-core print heads that are compact and capable of printing in Mincho typeface have been developed. In response to market demands, higher density, smaller size, and lower cost are becoming increasingly necessary. Conventionally, most print heads of this type have the basic configuration of an electromagnet as a means for driving the print wire.

Since the conventional print head mentioned above uses electromagnets, magnetic interference occurs between the individual drive means, characteristics vary depending on the number of driven wires, and there are restrictions on use due to the heat generated by the coil. Therefore, there were drawbacks such as difficulty in high-speed printing and unsatisfactory printing quality. In addition, it is not possible to downsize the device due to restrictions such as magnetic flux saturation and coil mounting, and furthermore, there are disadvantages in that wear and noise occur due to collisions of the magnetic attraction parts.

On the other hand, methods using displacement generating elements such as piezo elements have been proposed as means for driving the wire, but this has the disadvantage that the characteristics necessary for printing cannot be obtained as is because the displacement generated is minute.

SUMMARY OF THE INVENTION The present invention has been made to eliminate the drawbacks of the above-mentioned conventional devices, and its purpose is to efficiently expand the minute displacement of the piezo element to achieve a compact size, high speed, and high printing quality. The objective is to provide a good print head.

Another object of the present invention is to provide a highly reliable, low-noise print head that eliminates collision and friction areas within the head.

Structure of the Invention The print head according to the present invention is a print head that magnifies the linear displacement of a minute displacement generating element and transmits it to the print wire, and has a rotational displacement generating mechanism that converts the linear displacement into a rotational displacement. However, this rotational displacement generation mechanism includes a rotational displacement generation part rotatably supported at a predetermined rotation center;
It is characterized by comprising a transmission means for transmitting the linear displacement to a predetermined point of the rotational displacement generating section.

Example Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a perspective view of a drive means assembly of a print head according to the present invention, FIGS. 2 and 3 are side and front views of FIG. 1, and FIG. 4 is a rotational displacement generation shown in FIG. It is an enlarged view of part 4.

A laminated piezo element 1, which is a displacement generating means, has one end fixed to a frame 2, and a top piece 3 joined to the other end. Further, the rotational displacement generating section 4 is attached to the frame 2 so as to be rotatable about the rotation center 2C (indicated by arrow G in FIG. 4), and for this purpose, the plate springs 2a and 2b
is provided between the rotational displacement generating section 4 and the frame 2 as shown in FIG.

In order to transmit the linear displacement of the piezo element 1 shown by the arrow F (see FIG. 4) to a predetermined point 3C of the rotational displacement generating section 4, the leaf spring 3
a and 3b are provided between the top piece 3 and the rotational displacement generating section 4 as shown.

5 and 6 are partial sectional views of a side view and a rear view of a print head according to the present invention, in which a plurality of drive means assemblies shown in FIG. 1 are arranged on the circumference, and a frame 2 is It has an integral structure all around.

In the above structure, as shown in Fig. 4, the leaf spring 2
Between the center of rotation (point of action of linear displacement F) 2C of the rotational displacement generating section 4 formed by a and 2b and the center of rotation 3c of the rotational displacement generating section 4 formed by the leaf springs 3a and 3b,
They are separated by a certain distance, and the straight line E connecting the rotation centers 2c and 3c is configured to be approximately perpendicular to the displacement direction F of the piezo element.

With the above configuration, when a voltage is applied to the piezo element 1, the top piece 3 is displaced in the direction of the arrow F shown in FIG. As a result, the rotational displacement generating section 4 rotates in the direction of arrow G about the center point 2C, and a printing operation is performed by the printing wire 6 via the lever 5. Here, since the relative position between the top piece 3 and the center 3C and the relative position between the frame 2 and the center 2C are kept constant, it is possible to reduce the above-mentioned distance, and the arm length The ratio to the spacing, that is, the displacement magnification rate is increasing.

In addition, by forming the frame 2 parallel to the displacement direction of the piezo element 1 from ceramic, the structure has a structure in which the coefficient of thermal expansion is almost the same as that of the piezo element even when the temperature changes, so that the characteristics do not change much. This makes it possible.

In order to further expand the minute displacement of the piezo element 1, a rotational displacement generation mechanism exactly the same as that shown in FIG. It is possible to further expand minute displacements by the stage expansion mechanism. It is obvious that if a multi-stage enlarging mechanism is installed in the same way, the minute displacement will be further enlarged.

As explained above, according to the present invention, a small, high-speed print head with good print quality can be provided by efficiently magnifying minute displacements of piezo elements without distortion. Another effect is that since there are no collision parts or friction parts inside the head, a highly reliable and low-noise print head can be provided. Furthermore, the present invention has the advantage that it is possible to provide a low-cost print head that has a simple structure, a small number of parts, and is easy to assemble.

[Brief explanation of drawings]

1 is a perspective view of a printed wire drive means assembly according to the present invention, FIG. 2 is a side view of the assembly of FIG. 1, FIG. 3 is a front view of the assembly of FIG. 1, and FIG. An enlarged view of a part of Figure 2,
FIG. 5 is a side view of the embodiment of the present invention, and FIG. 6 is a rear view thereof. Explanation of symbols of main parts 1...Piezo element 2...Frame 4...Rotational displacement generating section 5...Arm 6...Print wire

Claims (1)

[Claims] The print head is configured to magnify the linear displacement of a minute displacement generating element and transmit it to the print wire, and has a rotational displacement generation mechanism that converts the linear displacement into rotational displacement, and this rotational displacement generation mechanism has a predetermined rotational displacement. A print head comprising: a rotational displacement generating section rotatably supported at a rotation center; and a transmission means for transmitting the linear displacement to a predetermined point of the rotational displacement generating section.