JPS63144054A - Printing head - Google Patents

Abstract

PURPOSE:To obtain a reliable printing head free of damage by a method in which a screw to adjust the compressive stress of an expandible piezoelectric element and a plate spring to be moved by receiving forces from finger are provided, and the piezoelectric element is held in the U-shaped groove of a base plate and given a compressive force in such a way as to regulate the compressive force. CONSTITUTION:A piezoelectric element 4 is always compressed by an adjusting screw 3 and a finger 2 to eliminate damage by tension forces. The compressive force of the element 4 is adjusted by the deforming amount of the finger 2 by the screw 3, and the clamping can also be adjusted within the range of non-tensile force during the action of the element 4. When the screw 3 is clamped, the finger 2 is deformed, and compressive force to the element 4 is increased, energy generated in the element 4 is partly consumed in the finger 2 and partly converted into the moving energy of the plate spring 6 having a printing needle 5. Printing energy can be adjusted by the screw 3, and the dispersion of printing density in the printing head consisting of a number of printing hammers can be regulated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a print head used in a printer.

[Conventional technology]

Conventionally, electromagnetic actuators have been widely used as drive sources for print heads. This electromagnetic actuator generates a magnetic field by passing current through a coil.
Since the magnetic force is used to drive the movable parts, copper loss and iron loss occur, which not only requires a large amount of energy, but also
There were problems such as heat generation and magnetic interference. Therefore, in recent years,
A printing hammer for printers as shown in Figure 4, which uses a piezoelectric element with high electrical/mechanical energy conversion efficiency, low power consumption, low heat generation, and no magnetic interference, has been reported (IEICE Mechanism Division Study Group Material EMC84). -49>.

FIG. 4 is a schematic side view of a printing hammer for a printer showing an example of a conventional piezoelectric actuator. In the same figure, the printing hammer is a flat hammer that is supported by a leaf spring 6 whose one end is fixed to the substrate 20, at the tip of the piezoelectric element 4 whose one end is fixed to the substrate 20 in the direction of extension (in the direction of arrow A). 19
are arranged so that they are in contact with each other. The flight hammer 19 is provided with a printing wire 14 for printing dots.

In this printing hammer, when a voltage is applied to the piezoelectric element 4, the flight hammer 19 is accelerated by receiving force from the piezoelectric element 4 due to the high-speed expansion operation of the piezoelectric element 4.
Fly away. Then, the printing wire 14 collides with the platen 7 via the ink ribbon 8 provided in front and the paper 9 to print dots on the paper 9. Thereafter, the flight hammer 19 returns to the piezoelectric element 4 due to the repulsive force from the platen 7 and the return force of the leaf spring 6. By repeating this action, characters and figures are expressed as a collection of dots.

[Problem that the invention seeks to solve]

In the conventional printer printing hammer described above, in order to speed up the printing operation, it is necessary to increase the natural frequency of the vibration system composed of the leaf spring 6, the flight hammer 19, and the printing wire 14. For this purpose, the spring constant of the leaf spring 6 must be increased. However, when the spring constant of the leaf spring 6 is increased, the proportion of the energy transmitted from the piezoelectric element 4 to the flight hammer 19 that is spent on deforming the leaf spring 6 increases, so the kinetic energy of the flight hammer 19 decreases. , the density of the printed dots becomes lighter.

Therefore, in order to achieve faster printing operations without reducing print density, it is necessary to increase the energy transmitted from the piezoelectric element 4 to the flight hammer 19. By increasing this transmitted energy, the spring constant of the leaf spring 6 can be increased to increase the speed and ensure the desired print density.

In order to increase the transmitted energy, the energy generated by the piezoelectric element 4 can be increased, and the applied voltage can be increased. However, when the applied voltage is increased, the acceleration of the piezoelectric element 4 increases, and the piezoelectric element 4 itself Internal stress caused by inertial force increases, which may lead to destruction, reducing reliability.

Furthermore, in such a printing hammer, the leaf spring 6
is arranged so as to be pressed against the piezoelectric element 4, but if the amount of pressing varies depending on the dimensional accuracy of the parts, the energy generated by the piezoelectric element 4 is consumed in proportion to the amount of pressing of the leaf spring 6. This causes variations in printing power. As a result, print density also becomes uneven, resulting in deterioration of print quality.

An object of the present invention is to provide a print head that solves these problems.

[Means for solving problems]

The print head of the present invention includes a substrate having a U-shaped groove in which a finger portion is provided on one side wall, and a substrate that is sandwiched within the U-shaped groove corresponding to the finger portion. a piezoelectric element that is attached to the substrate and expands and contracts in the width direction of the U-shaped groove; and a compressive stress of the piezoelectric element that is attached to the finger portion from the other side wall of the U-shaped groove of the substrate. and a leaf spring, one end of which is fixed to the substrate and is a free end, and the other end of which is provided with a printing needle moves in response to force from the finger portion.

[Effect]

In the present invention, a piezoelectric element is sandwiched in a U-shaped groove of a substrate, and a compressive force is applied to the piezoelectric element in the direction of expansion and contraction, so that even if a voltage is applied and the piezoelectric element expands and contracts, a compressive force is always generated in the piezoelectric element. Make it. Piezoelectric elements are strong against compressive force but extremely weak against tensile force, so by constantly generating compressive force,
The reliability of piezoelectric elements is greatly increased.

Further, a leaf spring having a printing needle at its free end is fixed to the front surface of the finger part, and the free end of the leaf spring is brought into contact with the finger part so that force can be transmitted thereto.

In such a configuration, when a voltage is applied to the piezoelectric element, the piezoelectric element causes a small displacement but sudden movement, applying an impact force to the free end of the leaf spring through the finger part, and the free end of the leaf spring responds to the impact force. fly forward. Due to the flight, the printing needle also moves forward and performs printing operation.

At this time, the kinetic energy of the leaf spring having the printing needle is given by the energy generated by the piezoelectric element, but is also consumed by the finger portion as a preloading means. The energy of this finger portion is necessary to prevent damage to the piezoelectric element, and by adjusting this energy, the kinetic energy of the leaf spring can be adjusted.

That is, the adjustment screw deforms the finger section and applies compressive force to the piezoelectric element, and by adjusting the amount of deformation of the finger section by the adjustment screw, the energy consumed by the finger section is adjusted. Through this adjustment, the energy transmitted from the finger portion to the leaf spring having the printing needle can also be adjusted, and the energy for printing can also be adjusted. As a result, print density can also be adjusted. A dot impact printer is composed of a plurality of print heads, and it is necessary to uniformly adjust the print density. According to the present invention, it is possible to easily adjust the print density even if there are dimensional variations between head parts.

As described above, the present invention has the effect of preventing damage to the print head and providing a print head with good print quality.

〔Example〕

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

FIG. 1(a) is a sectional view of a print head according to a first embodiment of the present invention, and is a diagram for explaining the usage pattern. Figure 1 (b
) is a perspective view of the embodiment shown in FIG. 1(a), which is shown as a print head for a line printer. Figure 1 (a> and (
In b), one side wall of the U-shaped grooved substrate 1 is formed into a comb shape, and a plurality of finger portions 2 are provided. An adjustment screw 3 is attached to each of the finger parts 2 through the U-shaped groove, and the finger parts 2 are deformed within the substrate 1 so as to be pulled inward. At this time, the piezoelectric element 4 is also inserted and mounted in the U-shaped groove corresponding to each finger part 2, and the piezoelectric element 4 is compressed by the finger part 2 and the adjustment screw 3 that deforms the finger part 2 in the direction of expansion and contraction. Power is given.

This piezoelectric element 4. A plate spring 6 having a printing needle 5 is fixed in correspondence with each finger portion 2 to a substrate 1 including an adjustment screw 3, and the plate spring 6 is positioned with respect to the substrate 1 by means such as a positioning pin. In the print head configured in this manner, displacement is transmitted to the finger portion 2 by excitation of the piezoelectric element 4, and further transmitted to the leaf spring 6 via the finger portion 2. The response of the piezoelectric element 4 is a small displacement of several microns, but the response speed is as large as several tens of kilohertz. Due to this sudden rise, an impact force is applied from the finger portion 2 to the leaf spring 6, and the leaf spring 6 flies forward freely. , the printing needle 5 on the leaf spring 6 touches the ink ribbon 8 on the platen 7.
．． The paper 9 is struck and characters are drawn on the paper 9 using a dot matrix.

The piezoelectric element 4 is constantly compressed by the adjustment screw 3 and the finger portion 2, and damage due to the action of tensile force as in the conventional case is eliminated. Furthermore, the compressive force of the piezoelectric element 4 can be adjusted by the amount of deformation of the finger portion 2 by the adjustment screw 3, and the tightening can be adjusted within a range where no tensile force is applied during operation of the piezoelectric element 4. When the adjustment screw 3 is tightened to deform the finger portion 2 and increase the compressive force on the piezoelectric element 4, part of the energy generated by the piezoelectric element 4 is consumed by the finger portion 2. The remaining energy is converted into kinetic energy of the leaf spring 6 having the printing needle 5, that is, energy for printing. Therefore, the printing energy can be adjusted using the adjustment screw 3. Through this adjustment, it is possible to adjust the variation in print density of the print head composed of a plurality of print hammers.

The print head is composed of a plurality of printing hammers, and it is common to adjust the print to compensate for variations in component dimensions.The present invention can perform this print adjustment in a short time, and can be used at low cost and without damage. A print head with excellent properties can be obtained.

FIG. 2 is a side sectional view of a serial printer print head according to a second embodiment of the present invention. The substrate 10 that holds the piezoelectric element 4 and the adjustment screw 3 therebetween has a cylindrical shape and is composed of a radial finger portion 11 (not shown, but radial when viewed from the front) and a cover 12 at the back. The substrate 10 and the piezoelectric element 4 in the cover 12 are fixed by applying compressive force by the finger portions 11 and adjustment screws 3, respectively. In addition, a plurality of leaf springs 13 are arranged radially in front of the finger portion 11 so as to correspond to the finger portion 11.
A printing wire 14 is provided at the free end of 3. Further, the plurality of printing wires 14 are bundled at their tip portions by a wire guide 15. Even in such a serial printer print head, the piezoelectric element 4 is always compressed, so there is no damage and reliability is improved, and the print density can be adjusted using the adjustment screw 3, so that a print head with good print quality can be obtained.

FIG. 3 is a side view of a print head showing a third embodiment of the present invention. In FIG. 3, the comb-shaped finger portion 16
The piezoelectric element 4 is sandwiched within a U-shaped substrate 17 having a cylindrical shape, and a compressive force is applied to the piezoelectric element 4 by deforming the finger portion 16 using the adjustment screw 3 above the piezoelectric element 4. The finger portion 16
A leaf spring 18 having a printing wire 14 is provided at the front. Even in such a configuration, the first. and the second fruit tJI
! , the same effect as the example can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, compressive force is applied to the piezoelectric element by sandwiching the piezoelectric element between the U-shaped grooves of the substrate, and the compressive force of the piezoelectric element is adjusted using the adjustment screw, thereby providing reliability without damage. In addition to being able to obtain a print head with good quality, it is also possible to easily adjust the print density, and to obtain a piezoelectric print head with good print quality at a low cost.

[Brief explanation of the drawing]

1(a) and (b) are respectively a sectional view and a perspective view of a first embodiment of the present invention, FIG. 2 is a side sectional view of a second embodiment of the present invention, and FIG. 3 is a sectional view of a second embodiment of the present invention. FIG. 4 is a schematic side view showing a conventional print head. 1.10.17... Substrate, 2.11.16... Finger portion, 3... Adjustment screw, 4... Piezoelectric element, 5...
... Printing needle, 6, 13. 18... Leaf spring, 7... Platen, 8... Ink ribbon, 9... Paper, 12...
...Cover, 14...Printing wire, 15...Wire guide. , Tobi・-? . Agent: Susumu Uchihara, Patent Attorney, ii7:. ('i Man1st Z shape 1;゛ne (Shinman20 plan 3 figure

Claims (1)

[Claims] A substrate having a U-shaped groove in which a finger portion is provided on one side wall; a piezoelectric element that expands and contracts in the width direction of the U-shaped groove; and an adjustment screw that is attached to the finger portion from the other side wall of the U-shaped groove of the substrate and adjusts the compressive stress of the piezoelectric element. and a leaf spring, one end of which is fixed to the substrate and is a free end, and the other end, on which a printing needle is provided, moves in response to a force from the finger portion.