JPS61106265A - Printing head - Google Patents

Abstract

PURPOSE:To enable a high printing force to be generated, by a method wherein a repulsive force obtained by collision with a repulsive member is imparted to a electrostrictive vibrator. CONSTITUTION:When a driving voltage is impressed on a electrostrictive element 10B of the electrostrictive vibrator 10 by a driving circuit 11, the element 10B is contracted, so that the vibrator 10 is bent and is displaced in the direction from a position A before impressing the voltage to a position B at a velocity v1 to collides against the repulsive member 13. Simultaneously, the driving voltage is cut off, so that due to the repulsion on collision against the member 13 and the elasticity of the vibrator 10 itself, the vibrator 10 is returned toward the position A at a velocity -ev1 to give an impact on a non-printing side end of a printing wire 5. The velocity of the vibrator 10 at this time is -(ev1+v2). As a result, the vibrator 10 remains stationary at the position A, while the wire 5 starts to solely move on receiving the impact from the vibrator 10, and the tip thereof protrudes from a tip bearing 7 to give an impact on an ink ribbon and a printing paper. After the impact, the wire is returned by the repulsive forces of the ribbon and the paper and an elastic force of a return spring 8 to make contact with a stopper 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a print head, and more particularly to a print head for a wire dot printer.

[Background of the invention]

Conventional printheads for dot printers include print wires for constructing a dot matrix of desired letters, numbers, and symbols. An electromagnet is generally used as a driving source for this printing wire. This type of print head has the advantage of being easy to operate at high speeds and having high reliability, but on the other hand, when operating at high speeds, it consumes a lot of power and requires a large number of parts. Therefore, in recent years, a new drive structure has been required to replace the electromagnetic drive.

In view of these circumstances, a type in which the printing wire is driven by a bimorph type electrostrictive vibrator is proposed, for example, in JP-A-57-
It is disclosed in Japanese Patent No. 22075.

In print heads that use bimorph electrostrictive vibrators that have been proposed so far, the electrostrictive vibrators have piezoelectric elements with opposite polarities bonded to both sides of a metal plate. It is configured to generate bending vibration by switching the applied voltage. In this type of print head, the applied voltage applied to the piezoelectric element is consumed by the bending energy of the electrostrictive vibrator itself, so that sufficient printing force cannot be exerted.

[Purpose of the invention]

The present invention has been made based on the above-mentioned problems, and an object of the present invention is to provide a print head using an electrostrictive vibrator that can obtain high printing power.

[Summary of the invention]

In order to achieve the above object, the present invention has a print head that prints letters, numbers, or symbols by a collection of dots using a print wire, in which one end of an electrostrictive vibrator that gives displacement to the print wire is fixed, and the other end is fixed. is a free moving end, this electrostrictive vibrating body is composed of an elastic member and a piezoelectric element provided on one surface of this elastic member, and a power source is connected to this piezoelectric element through a drive circuit, and the electrostrictive vibrating body is A repulsion member is provided at a position facing the surface of the anti-printing wire at the free moving end to provide a repulsion force to the electrostrictive vibrator upon collision with the electrostrictive vibrator, and the repulsion force of the repulsion member and the return of the strain deformation of the electrostrictive vibrator are combined. The electrostrictive vibrator is displaced by the deer.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the print head of the present invention.
In this figure, 1 is the head body, 2 is a guide frame provided on the head body 1, 3 is a lid body provided on the frame 2 with a screw 4, and 5 is a cover body provided on the wire guide 6 and the tip bearing 7 of the guide frame 2. The held printing wire, 8 is a return spring for returning the printing wire 5, 9 is the printing wire 5
This is a stopper that regulates the return position of the Reference numeral 10 denotes a bimorph electrostrictive vibrator for applying printing force to the printing wire 5, and one end of this electrostrictive vibrator 10 is connected to the head body 1 and the lid body 3.
The other end, ie, the free end, faces the opposite end of the printing wire 5. Electrostrictive vibrator 10
It is composed of an elastic member 10A such as a metal plate, and a nine electrostrictive element 10B installed on the surface opposite to printing of the elastic member 10A.

The electrostrictive element 10B is connected to the power source 12 through the entire drive circuit 11. The drive circuit 11 includes a switch IIA and a time setter 11 for turning on and off the switch IIA.
It is equipped with B. A repulsive member 13 made of, for example, rubber is provided on the inner surface of the lid 3 described above to apply a repulsive force to the free end of the electrostrictive vibrator 10. From the viewpoint of imparting a repulsive force, it is desirable that the repulsive member 13 be installed so as to collide with a node of vibration near the free end of the electrostrictive vibrator 10. Further, the aforementioned time setting device 11B sets the time until the free end of the electrostrictive vibrator 10 collides with the repulsion member 13.

This time depends on the shape and material of the electrostrictive vibrator 10.

It can be determined by the magnitude of the applied voltage and the distance traveled.

Next, the operation of one embodiment of the print head of the present invention described above will be explained with reference to FIGS. 2, 3, and 4.

FIG. 2 shows the displacement amount P of the electrostrictive vibrating body 10 and the displacement amount P of the printing wire 5 with respect to the driving voltage V in the print head of the present invention.
In this figure, D1 is the displacement waveform of the electrostrictive vibrating body 10, Pl is the displacement waveform of the printing wire 5, S is the position of the printing paper, and 0 is the initial rest of the printing wire 5 and the electrostrictive vibrating body 10. Position and Q represent the position of the tip of the repulsive member 13.

Now, when the electrostrictive vibrator 10 is stationary at position A, as shown by the solid line in FIGS. 1 and 3, the driving voltage shown in FIG. 2 is applied to the electrostrictive vibrator by the drive circuit 11. 10 electrostrictive elements 10B (in this case, apply in the polarization direction of the electrostrictive element 10B, t and b in the positive direction)
As the electrostrictive element 10B contracts, the electrostrictive moving body 10 bends as shown by the two-dot chain line in FIG. , and collides with the repulsion member 13 . Since the driving voltage is cut off at the same time as this electrostrictive vibrator 10 collides with the repulsive member 13, the electrostrictive vibrator 10 is caused to move due to the repulsion caused by the collision with the repulsive member 13 and the elasticity of the electrostrictive vibrator 10. Velocity (eV
x), return it to the position A before applying the voltage, and strike the end of the printing wire 5 on the side opposite to printing. Electrostrictive vibrator 1 at this time
The speed of 0 is -(evt+vz). As a result, the electrostrictive vibrating body 10 comes to rest at the initial position A, while the printing wire 5 receives a blow from the electrostrictive vibrating body 10 and begins to move independently as shown by the dotted line P1 in FIG.

Then, the tip of the printing wire 5 comes out of the tip bearing 7 and hits an ink ribbon (not shown) and printing paper to print. After the impact, the printing wire 5 returns due to the repulsive force between the ink ribbon and the printing paper and the spring force of the return spring 8, contacts the stopper 9, and settles at the initial position.

As described above, according to the embodiment of the present invention, the electrostrictive vibrator 10 collides with the repulsive member 13 to increase its speed, so that printing force can be increased. Furthermore, since the displacement of the electrostrictive vibrator 10 and the displacement of the printing wire 5 are independent, the displacement at the free end of the electrostrictive vibrator 10 can be reduced. As a result, printing speed can be increased.

FIG. 5 shows another embodiment of the print head of the present invention, and in this figure, the same reference numerals as in FIG. 1 are the same parts. In this embodiment, a collision detector 1 is mounted on the repulsion member 13 in order to detect the timing of the collision of the electrostrictive vibrator 100 with the repulsion member 13.
4 is provided, and the detection signal from the collision detector 14 is transmitted to the drive circuit as a signal for turning off the drive voltage. As the collision detector 14 mentioned above, a conductive rubber or other mechanical switch can be used.

With this configuration, the driving voltage can be cut off when the electrostrictive vibrator 10 collides with the repulsive member 13, so that the repulsive force of the repulsive member 13 can be effectively transmitted to the electrostrictive vibrator 10. Can be done.

As a result, the printing force value can be kept constant and the printing speed can be increased.

In the embodiment described above, the piezoelectric element 10B is provided on the side opposite to the printing surface of the elastic member 10A due to its strength, but it may be provided on the printing surface side of the elastic member 10A. Furthermore, although the electrostrictive vibrating body 10 and the printing wire 5 are constructed separately, the printing wire 5 may be joined to the free end of the electrostrictive vibrating body 10 as shown in FIG.

Furthermore, it is also effective to provide a wear-resistant material on the surface of the repulsion member 13 that comes into contact with the electrostrictive vibrator 10. Further, according to the embodiment of the present invention, the electrostrictive vibrator 10 is moved and displaced by its elastic force and the repulsive force of the repulsive member 13, so that the copying ability is improved to the extent that it can print on four sheets of plain paper compared to the conventional one. It has the following.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to give the electrostrictive vibrator the repulsive force obtained by colliding with the repulsive member, so that high printing force can be generated.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of the print head of the present invention, and FIG. 2 is the relationship between the displacement amount of the electrostrictive vibrator and the print wire with respect to the drive voltage in the print head of the present invention shown in FIG. 3 and 4 are diagrams illustrating the operation of the electrostrictive vibrator in the print head of the present invention, and FIG. 5 is a longitudinal sectional view showing another embodiment of the print head of the present invention. FIG. 6 is a longitudinal sectional view showing another example of a print head to which the present invention is applied. 1...Head body, 2...Guide frame, 3...
・Lid body, 5... Printing wire, 10... Electrostrictive vibrator,
10A... Bullet and other members, 10B... Piezoelectric element, 11.
...Drive circuit, 11A...Switch, 11B...Time setting device, 12...Pole 10 No. 2 (2) Fig. 3

Claims (1)

[Claims] 1. In a print head that prints letters, numbers, or symbols by a collection of dots formed by a printing wire, one end of an electrostrictive vibrator that displaces the printing wire is fixed, and the other end is freely movable. The electrostrictive vibrating body is made up of an elastic member and a piezoelectric element provided on one surface of the elastic member, and a power source is connected to the piezoelectric element through a drive circuit, and the free moving end of the electrostrictive vibrating body is In the position where the anti-printing wire faces the surface,
A print head characterized by being provided with a repulsion member that applies a repulsion force to an electrostrictive vibrator upon collision with the vibrator. 2. The print head according to claim 1, wherein the piezoelectric element is provided on the surface of the elastic member opposite to the print wire. 3. The print head according to claim 1, wherein the piezoelectric element is provided on the surface of the elastic member on which the print wire is located. 4. The drive circuit according to claim 2 or 3, characterized in that the drive circuit includes a switch for connecting and disconnecting the piezoelectric element and a power source, and a time setting device for setting the on/off time of this switch. print head. 5. The print head according to claim 4, wherein the off time in the time setting device is set to the time during which the electrostrictive vibrator comes into contact with the repulsive member. 6. A patent characterized in that the drive circuit is equipped with a switch that connects and disconnects the piezoelectric element and a power source, and a time setting device that sets the off time of this switch based on a signal from a collision detector provided in a repulsive member. A print head according to claim 2 or 3.