JPH03247464A - Piezoelectric actuator for impact printer - Google Patents

Abstract

PURPOSE:To make the rate of enlargement bigger and to make therewith structure of a printing head compact by a method wherein a spring member with a piezoelectric element connected thereto at its other end, a first lever that is extending toward the other end of a fixing base plate with the spring member connected thereto at its other end, a second lever that is connected to the other end of the fixing base plate with the first lever connected thereto at its other end and a printing wire connected to the second lever are provided. CONSTITUTION:One end of a first lever 4 is connected to one end 2a of a fixing base plate 2, and the other end of a spring member 3 is connected to the lever 4. One end of a second lever 5 is connected to the other end 2b of the fixing base plate 2, and the other end of the lever 4 is connected to the lever 5, and a printing wire 6 is connected to the other end of the lever 5. As voltage is applied to an electrode of a piezoelectric element 1, the other end 1b of the piezoelectric element 1 moves diagonally toward upper left by longitudinal piezoelectric effect, and thereby the curvature of the spring member 3 becomes large, making the angle of the lever 4 to its original position widened by theta1, and the angle of the lever 5 to its original position is widened therewith by theta2, making the front end of the printing wire 6 displaced upward. As the above-mentioned is a structure of two-stage enlargement, the rate of englargement can be made sufficiently large.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a piezoelectric actuator for impact printers.

[Conventional technology] Conventionally, piezoelectric materials are used to generate expansion and contraction due to the piezoelectric longitudinal effect according to the voltage applied to the electrodes, and this small displacement is
There is a piezoelectric actuator that uses a first-stage lever and a second-stage lever to enlarge and transmit the signal to the printing wire (for example, Japanese Patent Laid-Open No. 58-188672, Japanese Patent Laid-Open No. 59-1999)
230672, etc.).

[Problem to be solved] In the above conventional example, the differential amplitude is expanded in two stages.
The magnification ratio is not very large, two piezoelectric bodies must be used in series, and the print head becomes large. Furthermore, the displacement of each piezoelectric body is approximately 8 μm, and the displacement of two piezoelectric bodies in series is approximately 15 μm.
The displacement is on the order of μm, and the displacement of the wire is expanded to approximately 0.4 mm.

Although this finally satisfies the wire stroke required for printing, it is still not sufficient.

If the stroke of the printing wire is small, the positional accuracy of the gap with the platen is strictly required, and recording paper, ribbon, etc. must be placed in this narrow gap.

However, the advantage of impact-type printers is that they can print on multiple stacked sheets of non-carbon paper, but this requires larger gaps and larger print wire strokes.

Therefore, the purpose of the present invention is to increase the magnification ratio compared to the conventional one, increase the stroke of the printing wire with a margin, and increase the reliability of the operation.Even one piezoelectric element is sufficient, and it is also possible to use two piezoelectric elements. The object of the present invention is to obtain a larger stroke and to achieve a smaller print head.

[Means for Solving the Problems] In order to achieve the above object, the piezoelectric actuator of the present invention includes a piezoelectric element that expands and contracts due to a piezoelectric longitudinal effect according to a voltage applied to an electrode, and a piezoelectric element at one end. A fixed substrate that fixes and supports one end; a spring portion that has one end connected to one end of the fixed substrate and the other end of the piezoelectric element connected to the center; and a spring portion that has one end fixed and supported. A first lever is connected to one end of the base plate and is connected to the other end of the spring portion and extends toward the other end of the base plate; A second lever is connected to the other end of the first lever and extends in the opposite direction to the first lever, and the second lever is fixed to the other end of the second lever. It is equipped with a printing wire.

Further, the other end of the second lever is connected to a third lever, which has one end connected to one end of the fixed substrate and extends in the same direction as the first lever. By fixing the printing wire to the other end of the lever, a three-stage enlarging mechanism is constructed for further enlarging.

In addition, as a configuration for obtaining greater magnification, an L-shaped fixed substrate having a fixed part protruding from the center is provided, and the end parts are fixed to the fixed parts by extending toward both ends of the fixed substrate, and the voltage is applied to the electrodes. A pair of piezoelectric elements that expand and contract due to the piezoelectric longitudinal effect in response to voltage, and a pair of piezoelectric elements that have one end connected near both ends of a fixed substrate and the other ends of both piezoelectric elements connected to the center. a spring portion, one end portion of which is connected to both ends of the fixed substrate, and the other end portions of both spring portions are connected to each other, and first and second spring portions extend toward the respective other ends of the fixed substrate.
a third lever having one end fixed to the other ends of the first and second levers and extending in the opposite direction to the first lever;
A three-stage enlarging mechanism includes a lever and a printing wire fixed to the other end of the third lever.

As a configuration that can obtain a larger expansion than this configuration, the other end of the third lever is connected to the end of the fixed board on the same side as the first lever. It is connected to a fourth lever extending in the same direction as the lever, and a printing wire is fixed to the other end of the fourth lever, thereby forming a four-stage enlarging mechanism.

[Example code] Embodiments of the present invention will be described below based on the drawings.

As shown in FIG. 1, the piezoelectric element 1 has both ends 1a,
A voltage is applied through an electrode provided at 1b, and expansion and contraction occurs in a direction parallel to the applied voltage due to the piezoelectric longitudinal effect. The fixed substrate 2 has a frame shape with an opening on the upper side, and a fixing part 2 for fixing the piezoelectric element 1 on one end 2a side.
C is provided. One end portion 1a of the piezoelectric element 1 is supported by this fixed portion 2C.

One end portion of an arc-shaped spring portion 3 is connected to one end portion 2a of the fixed substrate 2 on the side of the fixed portion 2a. The other end portion 1b of the piezoelectric element 1 is connected to the center portion of the spring portion 3.

One end portion of a first lever 4 extending in the direction of the other end portion 2b of the fixed substrate 2 is connected to one end portion 2a of the fixed substrate 2. The ends are connected.

One end of a second lever 5 extending in the opposite direction to the first lever 4 is connected to the other end 2b of the fixed substrate 2. , the other end of the first lever 4 is connected to one end of the second lever 5.

A printing wire 6 extending vertically is connected to the other end of the second lever 5 .

With this structure, as shown in the second diagram, when a voltage is applied to the electrode of the piezoelectric element 1, the other end 1b of the piezoelectric element 1 moves diagonally upward to the left due to the piezoelectric longitudinal effect, and this displacement As a result, the curvature of the spring portion 3 increases, and the first lever 4
The angle with respect to the original position is expanded by an angle θ1, and due to this expansion, the second lever 5 is expanded by an angle θ2 with respect to the original position.

As a result, the tip of the printing wire 6 is displaced upward.

This configuration is a two-stage enlargement mechanism, and the enlargement ratio can be sufficiently large.

Furthermore, the second embodiment shown in FIG. 3 is provided with a three-stage enlarging mechanism, in which piezoelectric elements 11. Fixed substrate 12. Spring part 13. 1st. The construction of each second lever 14.15 is substantially the same as its respective counterpart in the first embodiment. One end 12a of the fixed substrate 12 extends upward as it is, and one end of a third lever 17 is further connected to its tip. The third lever 17 extends in the same direction as the first lever 14, and the other end of the second lever 15 is connected to one end of the third lever 17.

A vertically extending printing wire 16 is connected to the other end of the third lever 17 .

With such a structure, as described in the first embodiment, after the second lever 15 is expanded by the two-stage expansion mechanism, the third lever 17 is further expanded by three stages at its connecting portion. Since the eye enlargement mechanism is configured, the third lever 17 is enlarged. As a result, the tip of the printing wire 16 is largely displaced upward. This configuration has a three-stage enlarging mechanism and can provide a sufficiently large enlargement ratio.

Next, a third embodiment shown in FIG. 4 will be described.

First, the fixed substrate 22 is formed in an L-shape, and a fixed part 2 for fixing a pair of piezoelectric elements extends inward from a central corner.
2c is provided. The fixed portion 22c includes fixed substrates 2, 2.
A pair of piezoelectric elements 21A and 2 extend toward both ends of the
1B is supported at one end thereof.

Both ends 2 of the fixed board 22 at a position away from the fixed part 22c
In the vicinity of 2a and 22b, one end portion of a pair of spring portions 23A and 23B, which are formed by curving thin metal spring plates into an arcuate shape, is fixed. A piezoelectric element 21A is placed in the center of both spring parts.
, 21B are connected at the other ends.

One end portions of first and second levers 24.25 are respectively connected to both ends of the fixed substrate 22 so as to extend toward the other ends of the fixed substrate, and both levers 24.25 have spring portions 23A. , 23B are connected at the other ends. The other ends of the first lever 24 and the second lever 24 are connected to one end of a third lever 27 extending in the opposite direction to the first lever 24 . A printing wire 26 extending vertically is connected to the other end of the third lever 27 .

Since it has such a structure, the piezoelectric element 21A.

When a voltage is applied to each electrode of the piezoelectric element 21B, the other end of the piezoelectric element 21A moves diagonally upward to the left and the other end of the piezoelectric element 21B moves diagonally downward to the right due to the piezoelectric longitudinal effect, and this displacement causes the spring portion 23A to , 23B become large, the right end of the first lever 24 expands upward, and the upper end of the second lever 25 expands rightward. In response to this expansion of both levers, the third lever 27 expands greatly. As a result, the tip of the printing wire 26 is displaced upward. In this configuration, between the spring portion 23A and the first lever 24, between the spring portion 23B and the second lever 25, and between the first lever 23A and the first lever 24, and between the spring portion 23B and the second lever 25. Second. It is a three-stage enlargement mechanism at the connection part of the third lever, and the enlargement ratio can be sufficiently large.

Furthermore, the fourth embodiment shown in FIG. 5 is provided with a four-stage enlarging mechanism, including piezoelectric elements 31A and 31B, a fixed substrate 32. The configurations of the spring portions 33A and 33B and the first to third levers 34, 35, 37 are substantially the same as their respective counterparts in the third embodiment. Fixed board 32
One end 32a extends upward as it is, and a fourth lever 38 (p) is further connected to its tip.The fourth lever 38 extends in the same direction as the first lever 34. ,
The other end of the third lever 37 is connected to the vicinity of one end of the fourth lever 38 . At the other end of the fourth lever 38,
A vertically extending printing wire 36 is connected.

With such a structure, as described in the third embodiment, after the third lever 37 is expanded by the three-stage expansion mechanism, it is further expanded to the fourth stage at the connection part of the fourth lever 38. Since the enlargement mechanism is configured, the fourth lever 38 is enlarged. As a result, the tip of the printing wire 36 is largely displaced upward. This configuration has a four-stage enlarging mechanism, and it is possible to obtain a sufficiently large enlargement ratio.

As described above, according to the present invention, even with a single piezoelectric element, the expansion ratio of the displacement amount of the printing wire relative to the displacement amount of the piezoelectric element can be increased compared to the conventional method, and the stroke of the printing wire can be made with a margin. , the reliability of printer operation can be increased. It also contributes to the miniaturization of print heads.

In all the above embodiments, the fixed substrate and the spring part.

The lever may be integrally and continuously formed from one metal plate by pressing, or the fixed base plate and the lever may be formed in one piece.
It may be formed integrally and continuously from a sheet of metal by punching, and only the spring portion may be formed from another thin metal plate, which may be curved and connected at a predetermined position. Then, by supporting the piezoelectric element and fixing the printing wire to the last lever, assembly is completed. At this time, the printing wire does not have to be perpendicular to one end of the lever as in this embodiment.

Note that the shape of the spring portion is not limited to a circular arc shape, but may be appropriately formed such as an elliptical shape or a parabolic shape.

This mechanism is a 2- to 4-stage differential wave amplitude mechanism for the displacement of the piezoelectric element, and the magnification rate of the displacement of the printing wire with respect to the displacement of the piezoelectric element is affected by the length of the lever, etc. The device of the present invention allows for significant expansion compared to the conventional device.

[Effects] The piezoelectric actuator for an impact printer of the present invention configured as described above can greatly increase the magnification ratio of the displacement amount of the printing wire with respect to the displacement amount of the piezoelectric element compared to the conventional one. The printing wire can be driven with a sufficient stroke, and the reliability of the printer operation can be increased. Moreover, although one piezoelectric element is sufficient, an even more significant expansion can be achieved by using two.
Even further miniaturization of the print head can be achieved.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; Fig. 1 is a front view of the first embodiment, Fig. 2 is a route diagram explaining the enlarged state during operation, and Fig. 3 is a diagram of the second embodiment. 4 is a front view of the third embodiment, and FIG. 5 is a front view of the fourth embodiment. 1.11.21A, 21B. 31A, 31B... Piezoelectric element, 2.12, 22.32... Fixed substrate, 2a, 1
2a, 22a, 32a...one end, 2b, 12b,
22b, 32b...other end, 3.13.23A, 2
3B. 33A, 33B・・Spring part, 4.14, 24, 34ψφ・Italian first lever 5, '15
, 25. 35. - Second lever 6, 16. 26
．． 36 ・ 17.27 37 ・ 22c, 32c ・ 38 ・Fourth lever/printing wire, ・Third lever/fixing part, Applicant Seiko Co., Ltd. Toneri Patent attorney Kazuko Matsuda No. 4 Figures 22b, 32b・ToX^Syoshishin 3B 2b

Claims (4)

[Claims] (1) A piezoelectric element that expands and contracts due to a piezoelectric longitudinal effect in response to a voltage applied to an electrode; a fixed substrate that fixes and supports one end of the piezoelectric element at one end; a spring part connected to one end and the other end of the piezoelectric element connected to the center part; one end connected to the one end of the fixed substrate; a first lever, the other end of which is connected to the other end of the fixed substrate, and which extends in the direction of the other end of the fixed substrate; A second lever is connected to the other end of the lever and extends in a direction opposite to the first lever, and a printing wire is fixed to the other end of the second lever. A piezoelectric actuator for impact printers featuring: (2) In claim 1, the other end of the second lever has one end connected to the one end of the fixed substrate, and a third lever extending in the same direction as the first lever. A piezoelectric actuator for an impact printer, characterized in that the piezoelectric actuator is connected to a lever, and the printing wire is fixed to the other end of the third lever. (3) an L-shaped fixed substrate having a fixed part protruding from the center; one end part is fixed to the fixed part in such a way as to extend toward both ends of the fixed substrate; A pair of piezoelectric elements that expand and contract due to the piezoelectric longitudinal effect, one end of which is connected near both ends of the fixed substrate, and the other ends of both piezoelectric elements are connected to the center of the fixed substrate.
a pair of spring parts; one end of which is connected to both ends of the fixed substrate; the other end of both spring parts are connected to each other; and a second lever; a third lever having one end fixed to the other end of the first and second levers and extending in the opposite direction to the first lever; A piezoelectric actuator for an impact printer, comprising a printing wire fixed to the other end. (4) In claim 3, the other end of the third lever has one end connected to an end of the fixed board on the same side as the first lever, and in the same direction as the first lever. 1. A piezoelectric actuator for an impact printer, characterized in that the piezoelectric actuator is connected to a fourth lever extending in the direction of the arrow, and the printing wire is fixed to the other end of the fourth lever.