JPH0222068A - Piezoelectric head - Google Patents

Abstract

PURPOSE:To improve the followability of a liquid fluid, to enhance the response of a movable member and to perform high speed printing having a sufficient printing stroke by providing an energizing means for energizing the movable part so as to compress the liquid fluid at the time of the non-operation of a piezoelectric element. CONSTITUTION:Magnification displacement is applied to a movable member 11 through a liquid fluid 8 by the strain of a piezoelectric element 2 at the time of operation to perform printing operation by a printing member 7. At the non-operative time of said piezoelectric element 2, the movable member 12 is energized by an energizing means 13 to compress the liquid fluid 8 preliminarily and the modulus of elasticity of said fluid 8 is enhanced. As a result, the followability of the fluid 8 to the operation of the piezoelectric element 2 can be improved and the response of the movable member 12 can be enhanced and high speed printing can be performed with a sufficient printing stroke.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a piezoelectric head that magnifies and transmits strain when a piezoelectric element is activated to a movable member provided with a printing member through a liquid fluid such as oil, the movable member when the piezoelectric element is activated. In a piezoelectric head that performs a printing operation by applying an enlarged displacement to a movable member through a liquid fluid due to distortion of a piezoelectric element during operation, at least when the piezoelectric element is not activated, The movable member is configured to include biasing means for biasing the movable member so that the liquid fluid is compressed.

[Industrial application field]

The present invention relates to a piezoelectric head for a dot printer that magnifies and transmits the strain caused when a piezoelectric element is activated to a movable member provided with a printing member via a liquid fluid such as oil.

Recently, with the demand for higher speed dot printers, a high-speed operation print head using a piezoelectric element is required in place of the electromagnetic method. As this piezoelectric element, for example, the one shown in Nikkei Mechanical, page 92, published March 12, 1984, is used. This piezoelectric element was obtained by laminating a plurality of piezoelectric ceramic green sheets each having a metal paste film formed on one surface thereof to serve as an internal electrode, and then firing them all together. When constructing a print head using such a piezoelectric element, a mechanism is required that efficiently magnifies minute displacements of the piezoelectric element.

[Conventional technology]

FIG. 2 is a side view showing an outline of the structure of a conventional print head (piezoelectric head) using displacement expansion using fluid pressure. In the figure, 1 is a cylinder containing a piezoelectric element 2 and a piston 3, and 4 is a movable member.

The piezoelectric element 2 has its base connected to the bottom of the cylinder 1 and its tip connected to the piston 3 via a connecting member 5.

The upper part of cylinder 1 has a smaller diameter (smaller cross-sectional area) than piston 3.
A communicating portion 6 is provided in a protruding manner, and a movable member 4 having a printing member (wire) 7 protruding from its upper end is supported within the communicating portion 6 so as to be slidable in the vertical direction. A liquid fluid 8 such as oil is stored in the cylinder 1 and fills the space between the piston 3 and the movable member 4.

When printing, the piezoelectric element 2 is energized for a predetermined period of time. Due to the strain caused in the piezoelectric element 2, the connecting member 5 is
1, and the piston 3 also moves by the same amount in the same direction. This movement of the piston 3 is transmitted to the movable member 4 via the liquid 8, and the movable member 4 moves upward. In this case, the amount of movement of the movable member 4 is defined as β-, and the outer diameter of the piston 3 is expressed as β-.

When the outer diameter of the movable member 4 is d, the following relationship holds true between ρW and Δp.

7! , w = D2/d 2XΔp That is, since D>d, an enlarged displacement is applied to the movable member 4.

By this movement of the movable member 4, printing is performed by the printing member 7, but energization to the piezoelectric element 2 is stopped immediately before the printing is completed, and the movable member 4, which has completed the printing operation, returns to its original state together with the piezoelectric element 2 and the piston 3. The state will be restored.

[Problem to be solved by the invention]

However, in such a piezoelectric head, the piezoelectric element 2 is several k
) lz, and the fluid 8 must follow it, but the compressibility of the fluid cannot be ignored for such fast movements, and the responsiveness of the movable member 4 is poor, making it difficult for the wire to be displaced sufficiently. was not obtained.

An object of the present invention is to provide a piezoelectric head that can improve the responsiveness of a movable member when the piezoelectric element is activated.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a piezoelectric head that performs a printing operation by applying an enlarged displacement to a movable member through a liquid fluid due to distortion of the piezoelectric element during operation, at least when the piezoelectric element is not activated. The movable member is configured to include a biasing means for biasing the movable member so that the liquid fluid is compressed at a certain time.

[For production]

Since the movable member is biased by the biasing means and the liquid fluid is compressed, the elastic modulus of the fluid is improved and the fluid follows the movement of the piezoelectric element better, thereby improving the response of the movable member. Sexuality improves.

〔Example〕

The invention will now be described in detail with reference to FIG.

FIG. 1 is a side view showing an outline of the structure of a piezoelectric element according to the present invention. In the figure, 11 is a cylinder, 12 is a movable member, and 13 is an opposing means. Note that the same reference numerals are given to the same members as in the conventional one.

The cylinder 11 is integrally provided with a pair of support parts 14.14, and each support part 14 has a leaf spring-like force means 1.
3 are each supported in a cantilevered manner. The tips of these force means 13 press against the upper surface of the movable member 12 to force the movable member 12 downward, and the liquid fluid 8 is compressed by this force. In this case, the piezoelectric element 2 is also compressed.

Therefore, the elastic modulus of the liquid fluid 8 is improved, the ability of the liquid fluid 8 to follow the movement of the piezoelectric element 2 during printing is improved, and the responsiveness of the movable member 4 is improved.

〔Effect of the invention〕

As described above, according to the present invention, printing is performed by compressing the liquid fluid by the force means and activating the piezoelectric element, so that the liquid fluid can be moved with good followability. The responsiveness of the member can be improved, and high-speed printing with a sufficient printing stroke becomes possible.

[Brief explanation of the drawing]

Fig. 1 is a side view showing an outline of the structure of a piezoelectric element according to an embodiment of the present invention, and Fig. 2 is a side view showing an outline of the structure of a conventional print head using a fluid pressure displacement enlarging method. , 7 is a printing member (wire), 8 is a liquid fluid, 11 is a cylinder, 12 is a movable member, and 13 is an enemy means.

Claims (1)

[Claims] Due to the strain of the piezoelectric element (2) during operation, liquid fluid (
8), in which the liquid fluid (8) is compressed at least when the piezoelectric element (2) is not activated; Movable member (12
) A piezoelectric head characterized in that it is provided with an activation means (13) for activation.