JPH0740554A - Printing head - Google Patents

Abstract

PURPOSE:To provide a printing head which is capable of controlling the vibration of a printing head and thereby preventing the head from malfunctioning with regard to a piezoelectric printing head with the back surface in a longitudinal direction of an actuator fixed to a cylindrical ring. CONSTITUTION:This printing head consists of an actuator 2 which generates a displacement locally due to energization, a displacement magnifying mechanical part 3 which has printing wire 13 and magnifies the local displacement of the actuator 2 to allow the printing wire 13 to protrude, printing elements 1 which consist of a base part 4 to which the actuator 2 and the displacement magnifying mechanical part 3 are connected and has a surface in parallel with the protruding direction of the printing wire 13, and a cylindrical installation ring 15 of specified length with the faces, of the base 4 positioned in parallel with the protruding direction of the printing wire 13, each of which is radially fixed inward to the center. The local area is displaced by energizing the actuators 1 selectively, and the displacement is magnified by the displacement magnifying mechanical part 3 to drive the printing wire 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head for a wire dot printer using a laminated piezoelectric element or the like, and more particularly, a print head in which a back surface of a base portion parallel to an actuator is fixed to a cylindrical ring. It is about.

Recently, as the printing speed of wire dot printers has increased, multilayer piezoelectric elements suitable for high speed driving have been used to drive the wires of the print head. In such a print head, the laminated piezoelectric element is equipped with an enlarging mechanism because the displacement is minute, but the vibration during driving affects the print wires and the performance of the print head deteriorates and the print quality deteriorates. Therefore, a mechanism that can prevent this is desired.

[0003]

2. Description of the Related Art A piezoelectric print head will be described with reference to FIGS. FIG. 3 shows a printing element using a laminated piezoelectric element. As shown in the figure, the printing element 1a includes an actuator 2a, a displacement magnifying mechanism 3a, and an actuator.
It is composed of a base portion 4a that connects the displacement magnifying mechanism portion 3a with 2a.

As shown in FIG. 4 (a), the actuator 2a includes a laminated piezoelectric element 5, blocks 6 and 7 and a laminated piezoelectric element 5 which are made of steel and attached to both ends of the laminated piezoelectric element 5. It consists of elastic plates 8a and 8b that give a preload (compressive force), and a spring 10a is attached to a movable block 9 attached to the block 6.
However, the block 7 is joined to the base portion 4a.

The displacement magnifying mechanism 3a has an armature 11 and springs 10a and 10b for supporting the ends of the armature 11,
The spring 10b is supported by the protrusion 40 of the base 4a. A print wire 13a is fixed to the armature 11 via a beam 12. Further, both ends of elastic plates 8a, 8b along two opposite side surfaces of the laminated piezoelectric element 5 are fixed to the side surfaces of the blocks 6, 7 by, for example, laser welding.

As shown in FIG. 4 (b), the laminated piezoelectric element 5 is formed by laminating piezoelectric elements 50a, 50b, ... Made of ceramic plates and connecting positive and negative poles to each other. As shown in a), lead wires 14a and 14b are drawn out.

As shown in FIG. 5, the printing element described above.
A plurality of (for example, 24) 1a are respectively fixed to the mounting ring plate 15a formed of steel at the tip end surface of the pace portion 4a radially with screws 16 at equal angular intervals with the print wires 13a inside. The plurality of printing wires 13a gathered at the central portion of the mounting ring plate 15a are guided by the wire guides 17 and 18 at the intermediate position and the tip portion, and the tips are arranged in two rows.

With such a structure, when the printing element 1a is driven, a drive voltage is applied to the lead wires 14a and 14b to generate a strain of several tens of μm in the laminated piezoelectric element 5 and block 6 Armature by pushing up
11 rotates about the center of the springs 10a and 10b as the center of rotation to expand the operation and move the printing wire 13a in the direction of arrow A to several hundred μm.
Make it protrude.

Therefore, when a voltage is selectively applied to the plurality of printing elements 1a in accordance with the printing pattern, the printing wire 13a collides with the platen via the ink ribbon and the printing paper (not shown), and the printing paper 13a Form a dot print.

[0010]

According to the above conventional method, the printing element is radially fixed to the mounting ring plate at the upper end surface of the base with the printing wire inside, and when the printing head is driven, printing is performed. Since the vibration generated by the collision of the wire with the platen affects between the printing elements, the rigidity of the mounting ring is increased to suppress the vibration, but the mounting position is restricted and the thickness of the mounting ring plate is limited. Is thin (for example, about 2 mm)
Moreover, as shown in FIG. 5 (b), since the vibrating direction B when printing the printing wire and the mounting surface S1 are orthogonal to each other, the mounting ring easily vibrates, and vibration is completely suppressed even if the rigidity is increased. However, there is a problem in that a slight vibration remains, which affects the driving of other print wires, resulting in poor performance and poor print quality.

An object of the present invention is to provide a print head capable of suppressing vibration of the print head and preventing deterioration of operating performance.

[0012]

FIG. 1 shows the principle of the present invention. In the figure, 13 is a print wire, 2 is provided on each of a plurality of print elements 1, an actuator that locally displaces when energized, 3 is provided on each of a plurality of print elements 1, has a print wire 13, and has an actuator 2 Displacement magnifying mechanisms 4 for magnifying the local displacement of the printing wire 13 and projecting the printing wire 13 are respectively provided in the plurality of printing elements 1, and connect the actuator 2 and the displacement magnifying mechanism 3 in the projecting direction of the printing wire 13. A base portion having parallel surfaces, 1 is a printing element including an actuator 2, a displacement magnifying mechanism portion 3 and a base portion 4, and 15 is a surface of the base portion 4 parallel to the protruding direction of the printing wire 13 with respect to the center. It is a cylindrical mounting ring of a predetermined length that is radially mounted inside.

Therefore, the plurality of actuators 1 are selectively energized corresponding to the printing pattern to displace the local portion, and the displacement is magnified by the displacement enlarging mechanism portion 3 to enlarge the printing wire 13.
Is configured to drive.

[0014]

[Function] The cylindrical mounting ring 15 to which the base portion 4 is mounted has a predetermined length so that it can have rigidity, and when the printing wire 13 is driven, the direction in which the printing wire 13 projects, that is, Since the vibration direction of the print wire 13 and the surface of the attachment ring 15 having the predetermined length on which the base portion 4 is attached are parallel, the vibration of the print wire 13 is absorbed and the vibration is not transmitted to other print elements 1. The operation of the wire 13 is stable, and the performance of the print head can be improved.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to the print head described in the conventional example will be described below with reference to FIG. 2A and 2B are configuration diagrams showing an embodiment of the present invention. FIG. 2A is a perspective view with a part omitted, and FIG. 2B is a side sectional view with a part omitted. The same reference numerals as those in FIGS. 3 to 5 denote the same objects.

As shown in FIG. 2, a plurality of printing elements 1a direct the printing wires 13a inside, inside a cylindrical mounting ring 15b having a length substantially equal to the length of the back surface of the base portion 4a of the printing element 1a. Are arranged radially at equal angular intervals with respect to the center, and screws 16 are provided on the back surface of the base portion 4a.
It is attached at a. The mounting ring 15b is formed of a material having a small thermal expansion, for example, Invar alloy (Super Invar: iron-Ni-Co alloy).

With such a structure, the length of the cylindrical mounting ring 15b is substantially the length of the back surface of the base portion 4a, so that the mounting ring 15b can have rigidity and can be printed. Since the protruding direction of the wire 13a and the mounting surface S2 of the base portion 4a to the mounting ring 16b are substantially parallel to each other, when the printing element 1a is energized to drive the printing wire 13a, the tip collides with the platen. The generated vibration direction B of the printing wire 13a becomes substantially parallel to the mounting surface S2, and the generated vibration is caused by the mounting ring.
It is absorbed by 15b and is not transmitted to another printing wire 13a.

Therefore, the influence of vibration during driving is eliminated between the print wires 13a, the print performance of the print head is stabilized, and the print quality can be improved. In the above example, the case of the piezoelectric type print head has been described, but it may be applied to other dot impact type print heads, for example, it can be applied to the case of an electromagnetic type print head and the like, and the same effect can be obtained.

[0019]

As described above, according to the present invention, since the length of the cylindrical mounting ring is substantially the same as the length of the back surface of the base portion, the mounting ring has rigidity. Since the protruding direction of the printing wire and the mounting surface of the base part to the mounting ring are almost parallel, when the printing wire is driven,
The vibration generated in the print wire is absorbed by the mounting ring and is difficult to be transmitted to other print wires. Therefore, there is an effect that the influence of vibration at the time of driving between the print wires is reduced, the operation performance of the print head is stabilized, the print quality can be improved, and the malfunction of the print head can be reduced.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a configuration diagram showing an embodiment of the present invention.

FIG. 3 is a side view showing a printing element.

FIG. 4 is an explanatory diagram of an actuator

FIG. 5 is a configuration diagram showing a conventional piezoelectric type print head.

[Explanation of symbols]

1,1a is a printing element, 2,2a is an actuator,
3,3a is a displacement magnifying mechanism, 4,4a is a base, 1
3,13a is a print wire, 15,15b is a mounting ring, 15a
Is the mounting ring plate

Claims (1)

[Claims] 1. Displacement which comprises an actuator (2) that locally displaces upon energization and a printing wire (13), and expands the displacement of the local part of the actuator (2) to project the printing wire (13). A plurality of enlargement mechanisms (3), and a base section (4) connecting the actuator (2) and the displacement enlargement mechanism section (3) and having a surface parallel to the protruding direction of the printing wire (13) Printing element (1)
And the base portion parallel to the protruding direction of the printing wire (13)
The surface of (4) is provided with a cylindrical mounting ring (15) of a predetermined length that is fixed radially inwardly to the center respectively, and the plurality of actuators (1) are selectively energized to locally The print head is characterized in that the print wire (4) is driven by displacing the print wire and magnifying the displacement by the displacement magnifying mechanism section (3).