JPH0225341A - Piezoelectric actuator - Google Patents

Abstract

PURPOSE:To obtain a sufficient displacement without necessity of the considerable force of a piezoelectric element by providing a rotatable lever brought at its one end into contact with the protrusion side of a leaf spring near at least either one end, and the element connected to the other end. CONSTITUTION:A leaf spring 11 is reversibly bent, and supported at its both ends to a foundation 14. A lever 12 is connected at its base to the foundation 14, supported, a piezoelectric element 13 is secured at its base to the foundation 14, and connected at its upper end to the vicinity of the base of the lever 12 through a connecting member 16. The element 13 is not energized at the time of no printing, the lever 12 is positioned in a state as designated by a solid line, and the spring 11 is positioned in a recess state designated by a solid line. In case of printing, when the element 13 is energized for a predetermined period of time, the element 13 is elongated vertically, the lever 12 is moved to a position designated by broken lines, the pressure contact force of one end of the lever 12 to the spring 11 is reduced, the spring 11 is reversed to a state designated by a broken line by its recoiling strength, and a printing is executed by a printing member 15.

Description

[Detailed Description of the Invention] [Summary] Regarding the piezoelectric actuator used in wire dot printers, the purpose of this piezoelectric actuator is to obtain a sufficient displacement without requiring much force from the piezoelectric element. a leaf spring supported at both ends; a printing member fixed substantially at the center of the convex side of the leaf spring in a free state; and a printing member fixed to the convex side of the leaf spring near at least one end. A rotatable lever having one end in pressure contact with the lever, and a piezoelectric element connected to the other end of the lever and biasing the lever in a direction in which the pressure contact force of the one end with respect to the leaf spring is changed by displacement during operation. composition.

[Industrial application field]

The present invention relates to piezoelectric actuators used in wire dot printers.

In recent years, OA (office automation)
As devices become faster, printers, which are output devices, are also required to be faster. However, the electromagnetic method using springs used in wire dot print heads used in conventional printers has a limit to the driving frequency.
As an alternative to this, actuators using piezoelectric elements have been developed. The piezoelectric element used in this case is, for example, as shown in Nikkei Mechanical, page 92, published on March 12, 1984. The piezoelectric ceramic green sheets are laminated and then fired all at once. However, since the amount of displacement of this piezoelectric element is very small, a mechanism is required to efficiently expand this amount of displacement.

[Conventional technology]

One of the conventional piezoelectric element displacement magnification mechanisms uses buckling of a leaf spring. This type of piezoelectric actuator is disclosed in, for example, Japanese Patent Application Laid-Open No. 59-175386, and its structure and operation will be explained below with reference to FIG.

In FIG. 3, 1 is a piezoelectric element, 2 and 2 are a pair of levers, and 3 is a leaf spring. The levers 2 . 2 are rotatably connected to the fixed base 4 via connecting members 55 at their middle portions, and are connected above the piezoelectric element 1 .

The lower end is connected to the lever 2, respectively via a connecting member 6.6.
Connected to one end of 2. The leaf spring 3 is fixed at each end to the other end of the lever 2.2. At the center of the convex side (left side in the figure) of the leaf spring 3, a base portion of a printing member (wire) 7 extending in the left-right direction in the figure is fixed.

FIG. 3 shows the piezoelectric actuator having such a configuration in a non-operating state, in which the leaf spring 3 is engaged with a stopper 8 provided on the base 4 and is positioned in a desired state. When printing, the piezoelectric element 1 is energized for a predetermined period of time. This causes a displacement in the direction of the arrow in the piezoelectric element 1, and this displacement is magnified by the levers 2, 2, which rotate in the direction of the arrow.

Due to this enlarged displacement, the leaf spring 3 buckles in a convex state to the left, and the printing member 7 moves to the left as indicated by the arrow, so that the printing member 7 performs printing.

The energization to the piezoelectric element 1 is stopped immediately before the completion of printing, and the printing member that has completed printing moves the piezoelectric element 1, each lever 2.
It returns to its original state together with the leaf spring 3.

[The problem that the problem is trying to solve]

However, in the conventional piezoelectric actuator having such a configuration 1 effect, a sufficient magnification ratio cannot be obtained unless the lever ratio of the lever 2 is large, and the mass and rigidity of the lever 2 greatly affect the characteristics. That is, in order to effectively utilize the force generated by the piezoelectric element 1, it is necessary to increase the rigidity of the lever 2. Increasing this rigidity increases the mass of the lever 2, making it unsuitable for high-speed operation.

An object of the present invention is to provide a piezoelectric actuator that can obtain sufficient displacement without requiring much force from the piezoelectric element.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention includes: a leaf spring that is reversibly curved and supported at both ends; a printing member fixed approximately at the center of the convex side of the leaf spring in a free state; A rotatable lever is connected to the convex side of the leaf spring, one end of which presses against at least one end of the lever, and the lever is connected to the other end of the lever, and the lever is moved against the leaf spring by displacement during operation. The structure includes a piezoelectric element that opposes in the direction in which the pressure contact force at one end changes.

[For production]

When a piezoelectric actuator with this configuration is not printing,
The leaf spring is positioned in a concave state by the pressing force of one end of the lever, but at this time, the piezoelectric element is in an inactive state (corresponding to the first embodiment described later, when the lever is supported at the other end). (corresponding to the second embodiment described below, in which the lever is supported between one end and the other end to which the piezoelectric element is connected).

When printing, the state of the piezoelectric element is changed; specifically, in the former case (first embodiment), the piezoelectric element is energized to be activated, and in the latter case, the piezoelectric element is stopped energized. to make it inactive.

As a result, the lever rotates in a direction in which the pressing force against the leaf spring decreases, and the leaf spring is reversed by its restoring force and assumes a convex state. By this reversing operation of the leaf spring, printing is performed by the printing member.

The state of the piezoelectric element is returned to its original state just before printing is completed (in the former case, it becomes inactive, and in the latter case, it becomes active), and after printing is completed, the printing member returns to its original state together with the lever. to return to.

At this time of return, the temporary spring is also reversed in the opposite direction to the above-described direction due to the increase in the pressing force at one end of the lever, and returns to the original concave state.

〔Example〕

The present invention will now be described in detail with reference to FIGS. 1 and 2.

A first embodiment is shown in FIG.

FIG. 1 is a side view showing the structure of a piezoelectric actuator according to the present invention. In the figure, 11 is a temporary spring, 12 is a lever, and 13 is a piezoelectric element.

The leaf spring 11 is reversibly curved, and both ends are supported by the base 14. This figure shows an example in which one end is fixed and the other end is rotatably supported.

A printing member (wire) 15 is fixed to the center of the upper side (convex side in the free state) of the leaf spring 11 and extends upward.

The base (other end) of the lever 12 is connected to the base 14.

Supported.

The piezoelectric element 13 has its base fixed to the base 14 and its upper end connected to the vicinity of the base of the lever 12 via the connecting member 16 .

When a piezoelectric actuator with this configuration is not printing,
The piezoelectric element 13 is not energized (inactive state), and the lever 1
2 is positioned as shown by the solid line, and the leaf spring 11 is
It is pressed by one end of the lever 12 near the end on the free support side and is positioned in the concave state shown by the solid line. 1
A stopper 7 is provided on the base 14 and locks the leaf spring 11 in a concave state.

When printing, the piezoelectric element 13 is energized for a predetermined period of time to be activated. As a result, the piezoelectric element 13 is displaced (stretched) in the vertical direction indicated by the arrow, and this displacement causes the lever 12 to receive the enemy's force counterclockwise in the figure and move to the position indicated by the dotted line. As a result, the pressing force of one end of the lever I2 against the leaf spring 11 is reduced, and the leaf spring 11 is reversed to the state shown by the dotted line due to its restoring force, and by this reversal action, printing is performed by the printing member 15. The energization to the piezoelectric element 13 is stopped immediately before printing is completed, and as a result, the piezoelectric element 1
3 returns to its original state, so the printing member 15 that has completed printing is moved along with the leaf spring 11, which is reversed to its original concave state by one end of the lever 12, which returns to the position indicated by the solid line by the return of the piezoelectric element 13. Return to original position.

During these operations, printing is performed by the restoring force of the leaf spring 11, and the enemy force on the piezoelectric element 13 only reduces the pressing force of one end of the lever 12 against the leaf spring 11 to the extent that the leaf spring 11 is restored. Since it does not need to be too large, high-speed printing with sufficient displacement (printing stroke) is possible without increasing the lever rigidity as in the past.

FIG. 2 shows a second embodiment.

In this example, the intermediate part of the lever 21 is supported by the base 22, and the upper end of the piezoelectric element 13 is connected to the lever 21 via the connecting member 23.
It is connected to the base (other end) of 1.

FIG. 2 shows a non-printing state of the piezoelectric actuator having such a configuration. In this state, the piezoelectric element 13 is energized, and one end of the lever 2 presses the vicinity of the end of the leaf spring 11 to release the leaf spring. 11 is positioned in a concave state.

During printing, power supply to the piezoelectric element 13 is stopped for a predetermined period of time. As a result, the lever 21 rotates a predetermined amount counterclockwise from the position shown in the figure, the pressure of the lever 21 against the leaf spring 11 decreases, and the leaf spring 11 is reversed into a convex state by its restoring force.

By this reversing operation, printing by the printing member 15 is performed. The energization stop to the piezoelectric element 13 is canceled immediately before printing is completed, and the lever 21 is thereby returned to the illustrated position under the force of the displaced piezoelectric element 13. After completing printing, the printing member 15 is pressed by one end of the returning lever 21 and returns to its original state together with the leaf spring 11 which is reversed to a concave state.

In the case of this example as well, the enemy force of the piezoelectric element I3 only reverses the leaf spring 11 and does not need to be very large, so that the same effect as in the previous example can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, a sufficient printing stroke can be obtained without requiring much force from the piezoelectric element, and high-speed printing can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a side view showing the structure of a piezoelectric actuator according to a first embodiment of the present invention, FIG. 2 is a side view showing the structure of a piezoelectric actuator according to a second embodiment of the present invention, and FIG. This is a side view showing the structure of a piezoelectric actuator. In the figure, 11 is a leaf spring, 12.21 is a lever 13 is a piezoelectric element, and 15 is a printing member.

Claims (1)

[Claims] A leaf spring (11) that is reversibly curved and supported at both ends; and a printing member (15) fixed approximately at the center of the convex side of the leaf spring (11) in a free state. and a rotatable lever (1) having one end pressed against the convex side of the leaf spring (11) near at least one of the ends.
2), and a piezoelectric element (13) connected to the other end of the lever (12), which biases the lever (12) in a direction in which the pressure contact force of one end against the leaf spring (11) is changed by displacement during operation. )
A piezoelectric actuator for a wire dot printer, characterized by comprising: