JPH0376227B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing element, and particularly to a printing element for performing dot printing using a piezoelectric material as a driving source.

FIG. 1 is a side view showing an example of the structure of a printing element according to the present invention. A connecting member 2 connected to the inner bottom of a metal base member 1 via a plate-like member.
A columnar piezoelectric body 4 whose lower and upper ends are fixed to a metal connecting member 3 provided in a gap above the base member 1 is a driving source for printing operation. The metal movable members 9 and 10 provided above the base member 1 operate as levers in response to the displacement given by the piezoelectric body 4 to magnify and transmit the displacement. The connection member 3 is further connected to a plate-shaped coupling member 5 via a plate-shaped member.
and 6 to the lower ends of movable members 9 and 10. Further, the lower end portions of the movable members 9 and 10 are connected to plate-shaped coupling members 7 and 8 provided at a predetermined distance from the coupling members 5 and 6, respectively.
It is connected to the upper end of the base member 1 via. One end of transmission members 11 and 12 made of metal plates is fixed to the upper end of each of the movable members 9 and 10, and the other end of each transmission member 11 and 12 is fixed to a predetermined location of the movable member 13, respectively. A metal bar wire 14 for dot printing is attached to the tip of the movable member 13.

When a driving voltage is applied to the piezoelectric body 4, the length of the piezoelectric body 4 is extended due to the electrostrictive effect, causing dimensional distortion.
Push up the connecting member 3. The corresponding displacement is guided via coupling members 5 and 6 to movable members 9 and 10, respectively, which act as levers and have their respective upper ends aligned in the directions indicated by dashed arrows A and B. causes displacement. These two displacements in opposite directions cause the transmission members 11 and 12
The rotational motion is transmitted to the movable member 13 via the rotary member 13, and the wire 14 moves in the direction of the broken line arrow C to perform a dot printing operation.

In the conventional printing element, in order to smoothly transmit the displacement generated in the movable members 9 and 10 to the movable member 13, the plate thickness of the transmitting members 11 and 12 is made thinner, so that the transmitting members 11 and 12 are circular during displacement transmission. It is designed to produce a simple arc-shaped bend. However, at the same time, higher-order mode mechanical vibrations are generated in the transmission members 11 and 12 that are unnecessary for their operation.
This has the drawback that excessive stress acts on the transmission members 11 and 12, making them susceptible to breakage during repeated operations.

FIG. 2 is a partial side view illustrating the bent state of the transmission members 11 and 12 during operation of a conventional printing element. During operation, the transmission members 11 and 12 undergo simple bending in an arc shape as shown by the broken line, as well as bending due to unnecessary vibrations in higher-order modes, and the two overlap to form a complex shape as shown in the solid line. Becomes bent. The magnitude of the stress that acts with such complex bending is considerably increased compared to the case of only simple bending. Usually, the magnitude of the stress exceeds the fatigue limit of the material of the transmission members 11 and 12, causing breakage and fracture during repeated operations.

SUMMARY OF THE INVENTION An object of the present invention is to provide a printing element that eliminates the above-mentioned drawbacks and prevents the plate-shaped transmission member from generating unnecessary vibrations in higher-order modes during operation, thereby preventing breakage and destruction of the transmission member. .

The element of the present invention includes a piezoelectric body that generates dimensional distortion in response to an applied voltage, a base member to which one end of the piezoelectric body is fixed, and a plate-like member interposed between the other end of the piezoelectric body and the base member. first and second movable members that are connected to each other and generate first and second angular displacements in opposite directions in response to the dimensional strain applied from the piezoelectric body through the plate member; plate-shaped first and second transmission members each having one end fixed to the first and second movable members; the other end of each of the first and second transmission members being fixed to the first and second movable members; a third movable member that generates a third angular displacement in response to the first and second angular displacements that are transmitted, and provides a printing operation to the printing wire; The ratio of the thickness of at least one of the transmission members to the length of the transmission member is 0.05 or more.

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

3 and 4 are a partial perspective view and a characteristic diagram, respectively, for explaining the principle of the present invention.
Assume that one of the plate-shaped transmission members 11 and 12, for example, the transmission member 12 as shown in FIG. 3, has a thickness of t, and a length between the two end portions where they are joined.
FIG. 4 shows that the transmission member 12 (or 11) is a metal plate, and the Young's modulus of the metal material is 2×10 ⁴
In the case of Kg/mm ² , it indicates a dimensional range in which the transmission member 12 (or 11) does not cause unnecessary vibration during displacement transmission. In other words, when the length l of the transmission member 12 (or 11) is within the range of 4 to 10 mm, if the minimum value of the thickness t that does not cause unnecessary vibration is determined by experiment (or simulation), the solid line M The broken line shown is obtained. The range of thickness t that does not cause unnecessary vibrations is the hatched area (here, 〇 marks are dimensional combinations that do not cause unnecessary vibrations, and × marks are dimensional combinations that cause unnecessary vibrations.)Thickness If we draw a broken line L indicating the combination of dimensions where the dimension ratio t/l between t and length l is equal to 0.05, the hatched area is the area above the broken line L, that is, the formula t/l. Substantially coincides with the area satisfying ≧0.05.

The element of the invention comprises transmission members 11 and 1
The dimension ratio t/l of at least one of the transmission members 11 and 12 is selected to be 0.05 or more to prevent unnecessary vibrations from occurring during operation, thereby preventing the excessive stress caused by unnecessary vibrations from acting as in the conventional transmission members 11 and 12. This is to prevent breakage and breakage. Transmission member 1
1 and 12 are linked together with movable members 9, 10 and 13, so if the dimensional ratio t/l of at least one of them is set to 0.05 or more to prevent unnecessary vibrations, the other Unnecessary vibrations are also prevented.

As an embodiment of the present invention, the material of the transmission members 11 and 12 has a fatigue limit of 40
We will explain the case where steel material with a weight of about Kg/mm ² is used. For example, when the length l between the joints at both ends of the transmission member 12 shown in FIG. 3 is 7.5 mm, the thickness t of the transmission member 12 is 0.45 mm, and the dimension ratio t/l is selected to be 0.06. , the transmission member 12 does not cause unnecessary vibration during operation, and the maximum stress acting on it is approximately 30
Kg/mm ² , which is below the fatigue limit of the material, so it will not break or break even if it is operated repeatedly. However, if the thickness t is reduced and the dimension ratio t/l is 0.05 or less, for example, the length l remains 7.5 mm and the thickness t
to 0.35mm (therefore, the dimension ratio t/l is 0.047)
0.05 or less), the transmission member 12 will cause unnecessary vibration during operation, and the maximum stress that will be applied will be approximately
It reaches 53Kg/mm ² and exceeds the fatigue limit of the material, so there is a high probability of breakage during repeated operation.

As described above, the present invention has the effect of providing a printing element in which the plate-shaped transmission member does not generate unnecessary vibration during operation, thereby preventing the transmission member from breaking or breaking during repeated operations.

[Brief explanation of drawings]

FIG. 1 is a side view showing an example of the structure of a printing element according to the present invention, FIG. 2 is a partial side view illustrating the operating state of a conventional printing element, and FIGS. FIG. 2 is a partial perspective view and a characteristic diagram for explaining the principle. 1...Base member, 2, 3...Connection member, 5~
8... Connecting member, 9, 10, 13... Movable member,
11, 12...Transmission member, 14...Wire.

Claims (1)

[Claims] 1 A piezoelectric body that generates dimensional distortion in response to an applied voltage, a base member to which one end of the piezoelectric body is fixed, each connected to the other end of the piezoelectric body and the base member via a plate-like member. first and second movable members that respectively produce first and second angular displacements in opposite directions in response to the dimensional strain applied from the piezoelectric body through the plate member; First and second plate-shaped transmission members are fixed to the first and second movable members; the other ends of the first and second transmission members are fixed to the first and second movable members; a third movable member that generates a third angular displacement in response to the first and second angular displacements to apply a printing operation to the printing wire; A printing unit characterized in that the ratio of the thickness of at least one plate to the length of the plate is 0.05 or more.