JPH0373469B2 - - 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 perspective view illustrating the structure of a printing element according to the present invention. A piezoelectric body 2 whose lower end is fixed to a metal mounting member 1 is a driving source for printing operation. The upper end of the piezoelectric body 2 is fixed to a metal coupling member 3. Both of the metal movable members 4 and 5 are provided to act as levers to magnify and transmit the displacement when they receive displacement from the piezoelectric body 2. The lower end portions of the movable members 4 and 5 are respectively connected to the mounting member 1 and the coupling member 3 via plate-shaped connecting portions. Furthermore, a transmission member 6 of a metal plate is provided at the upper end of each of the movable members 4 and 5.
and 7 are fixed, and the other ends of the transmission members 6 and 7 are fixed to predetermined positions on the movable member 8, respectively. A metal rod wire 9 for dot printing is attached and fixed to the tip of the movable member 8.

When a driving voltage is applied through the lead 10 between a pair of electrodes provided on both sides of the piezoelectric body 2, the piezoelectric body 2 expands due to the electrostrictive effect, causing dimensional distortion, pushing up the coupling member 3, and causing the movable member 4 and Give displacement to 5. In response to this displacement, movable members 4 and 5 each act as a lever, causing displacement in the directions indicated by broken line arrows A and B at their respective upper ends. When these two displacements in opposite directions are transmitted via the transmission members 6 and 7, the movable member 8 causes a rotational movement, and the wire moves in the direction of the dashed arrow C to perform the dot printing operation. I do.

In such conventional printing elements, the dimensions and angles of each part of the displacement transmission path must be set to appropriate values so that the plate surfaces of the transmission members 6 and 7 do not undergo complicated bending during the printing operation, causing excessive bending stress. The plate surfaces of the transmission members 6 and 7 are designed to bend in a simple arc shape when viewed from the side. This is intended to prevent excessive bending stress from acting on the transmission members 6 and 7 and causing them to break or break. However, the transmission members 6 and 7 bend into a simple shape as described above until just before the wire 9 impacts the printing surface, but upon impact, the reaction force from the wire 9 bends the transmission members 6 and 7 into a complex shape. Bending occurs and excessive bending stress is applied, often resulting in breakage and breakage.

That is, the conventional printing element has the disadvantage that the reaction force that the wire 9 receives from the printing surface upon impact causes complex bending of the transmission members 6 and 7, which causes excessive bending stress to act on the transmission members 6 and 7, resulting in easy breakage. be.

SUMMARY OF THE INVENTION An object of the present invention is to provide a printing element which eliminates the above-mentioned drawbacks and prevents the plate surface of the transmission member from being bent or broken even upon impact.

The element of the present invention includes a piezoelectric body that generates dimensional distortion in response to a printing voltage, a mounting member that fixes one end of the piezoelectric body, and a plate-like member that is connected to the other end of the piezoelectric body and the mounting 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 whose respective ends are fixed to the first and second movable members, and whose respective other ends are fixed to the first and second movable members; a third movable member that generates rotational movement in response to the transmitted first and second angular displacements; and a wire that has one end fixed to the third movable member and that performs a printing operation in response to the rotational movement. and a printing member disposed such that the center of the rotational movement substantially coincides with the center of impact against the reaction force transmitted from the printing surface via the wire at the time of impact.

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

FIG. 2 is a partial side view for explaining the principle of the present invention. As mentioned above, during operation, the transmission member 6
and 7 are designed to produce simple bends. In this case, in the transmission members 6 and 7, the length of the line segment connecting points E and F intermediate between the boundary points fixed to the movable members 4 and 5 and the boundary points fixed to the movable member 8 does not change during operation. The length remains constant. That is, when displacements are transmitted from the movable members 4 and 5 to the transmission members 6 and 7, respectively, the line segment connecting points E and F moves correspondingly while keeping the length constant. The motion of this line segment is equal to the combination of two components: translation and rotation. Of these, the component of parallel movement is
Since the transmission members 6 and 7 are not bent,
All you have to do is focus on the rotational component. Point R, which is the center of rotation of this rotational component, is usually located near the line segment connecting points E and F. One end of each of the transmission members 6 and 7 is fixed to each predetermined location of the movable member 8, and is connected to a point E.
When the line segment connecting F and R rotates around point R while maintaining a constant length, the transmission members 6 and 7 bend in a simple circular arc shape and transmit displacement to the movable member 8 to wire the wire. 9 to perform the printing operation. When a reaction force in the direction of the dashed arrow D is transmitted from the wire 9 at the time of impact, the movable member 8 performs a rotational movement about a point J, which is the center of the impact against the point H. If the main axis of the conventional moment passing through point G, which is the center of gravity of the movable member 8, is shown by a broken line K, and the point H on which the reaction force acts on the broken line K is shown, then the point J is connected to the broken line K.
and the product of the length between points G and H and the length between points G and J is equal to the square of the radius of inertia about the center of gravity. If the wire 9 is attached near the lower end of the movable member 8 as shown in this figure, and therefore the point H is near the lower end of the movable member 8, then the point J will be the point G.
It is located inside the movable member 8 near to. In this way, the point R, which is the center of rotation caused by the displacement transmitted from the movable members 4 and 5, and the point J, which is the center of rotation caused by the reaction force at the time of impact, are separated from each other. In this case, two rotations with different centers are added, resulting in complex bending of the transmission members 6 and 7. In the element of the present invention, by configuring the point R and the point J to substantially coincide with each other, the transmission members 6 and 7 are prevented from being complicatedly bent, thereby preventing breakage and breakage.

FIG. 3 is a partial side view showing the first embodiment of the present invention. In this embodiment, one end of each of the transmission members 6 and 7 is fixed to the movable member 8 so that the main axis of the moment of inertia of the movable member 8 (indicated by the broken line K) passes through the point R, and furthermore, the center of impact with respect to the point H is The attachment location of the wire 9 is selected so as to coincide with point R. Note that point R is the center of rotation caused by the displacement transmitted from movable parts 4 and 5, as in the case of FIG. Compared to the case shown in FIG. 2, the attachment point of the wire 9 is closer to the center of gravity, point G, and accordingly, the center of impact on point H (i.e., point J) is farther away from point G, and the movable member It is outside of 8. By aligning point R and point J in this way, the rotation caused by the displacement transmitted from the movable parts 4 and 5 and the rotation caused by the reaction force at the time of impact are both at the same point R.
(i.e. J), even when these two rotations are added, only simple bending occurs in the transmission members 6 and 7, and excessive bending stress as in the conventional case does not occur. Breakage and damage can be prevented.

FIG. 4 is a partial side view showing a second embodiment of the present invention. In this embodiment, a mass adding member 11 is additionally provided at the lower end of the movable member 8 in the first embodiment shown in FIG. By adding the mass adding member 11, the center of gravity of the movable member 8 to which it is added, that is, point G, is shifted downward compared to the case of the previous embodiment, and the radius of inertia around the center of gravity is increased compared to the case of the previous embodiment. . Therefore, point H is adjusted so that the center of the blow (that is, point J) coincides with point R.
When selecting , the point H can be shifted downward compared to the case of the previous embodiment, which means that the attachment point of the wire 9 can be brought closer to the lower end of the movable member 8, so that the displacement transmitted to the wire 9 can be increased. There is an advantage that the stroke during the printing operation can be made longer than in the previous embodiment. A comparative example of the magnitude of stress acting on the transmission members 6 and 7 for both a conventional printing element not provided with the mass adding member 11 and the printing element of this embodiment provided with the mass adding member 11 is shown below. Shown below. In either case, the plate width of the transmission member 6 is 1.7 mm, the plate length is 15 mm, and the plate thickness is 0.26 mm, and the plate width of the transmission member 7 is 2.2 mm,
The plate length is 7mm and the plate thickness is 0.2mm. Further, the plate surfaces of the transmission members 6 and 7 form an angle of 10°. When printing with a maximum printing force of 6 Newtons,
The maximum stress acting on the transmission members 6 and 7 according to the reaction force received from the wire 9 (0.25φ) is
In the conventional example, they are 27Kg/mm ² and 81Kg/mm ² , and in this example, they are 18Kg/mm ² and 35Kg/mm ² . Therefore, the material for the transmission members 6 and 7 has a fatigue limit.
In the conventional example, when a steel material of ^{approximately} 40 kg/mm2 is used, the stress acting on the transmission member 7 greatly exceeds the fatigue limit of the material, resulting in breakage during repeated operations, whereas in this example, the transmission member 7 Since the stresses acting on 6 and 7 are both below the fatigue limit of the material, no breakage occurs.

As is clear from the above description, the present invention has the effect of realizing a printing element that can prevent the transmission member from breaking and breaking by preventing complicated bending of the plate surface of the transmission member at the time of impact.

[Brief explanation of drawings]

FIG. 1 is a perspective view illustrating the structure of a printing element according to the present invention, FIG. 2 is a partial side view illustrating the principle of the present invention, and FIGS. 3 and 4 are examples of the present invention. This is a partial side view showing . 1... Mounting member, 2... Piezoelectric body, 3... Coupling member,
4, 5, 8...Movable member, 6, 7...Transmission member, 9...
Wire, 10... Lead, 11... Mass adding member.

Claims (1)

[Scope of Claims] 1. A piezoelectric body that generates dimensional distortion in response to an applied voltage, a mounting member to which one end of the piezoelectric body is fixed, and a plate-like member attached to the other end of the piezoelectric body and the mounting member, respectively. first and second movable members that are connected to each other through the piezoelectric body and generate first and second angular displacements in opposite directions in response to the dimensional strain applied from the piezoelectric body through the plate-like member; , plate-shaped first and second transmission members having one end of each fixed to the first and second movable members, and the other ends of the first and second transmission members fixed to each other; a third movable member that generates rotational motion in response to the first and second angular displacements transmitted through the third movable member; and a printing member arranged so that the center of the rotational movement and the center of impact against the reaction force transmitted from the printing surface via the wire at the time of impact substantially coincide with each other. A printing element that 2. The third movable member has a mass adding member provided at an end opposite to the side to which each end of the first and second transmission members is fixed when viewed from the attachment point of the wire. Printing elements described in range 1.