JPS59202872A - Impact-type printing head - Google Patents

Abstract

PURPOSE:To reduce high-frequency vibration and vertical and horizontal vibration by a method wherein a prescribed inertia mass which has a printing wire is mounted and fixed on a movable plate provided to the center of an elastic plate and a piezo-porcelain plate, which is divided into two and has electrode layers on its front and back surfaces, is solidly jointed with the elastic plate. CONSTITUTION:When an inertia mass 10 returns to a balancing position at a high speed, it is given a repulsion force from the whole surface contacting with a base plate 19 so that the movement of the inertia mass 10 becomes rebounding motion with straight component and rotation component. In order to reduce this phenomenon, a cut slot 24 is provided to an upper plate 23 which is also used as a clamp for printing hammer to form a pivot 25, which is provided to a suitable position corresponding to the position of a pivot 21 of the base plate 19. With this composition, the straight movement of the inertia mass 10 is completely restrained and the rebounding motion due to the remaining rotation component force is also reduced to be almost negligible.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an electrostrictive drive type print head that utilizes piezoelectric strain such as a piezoelectric ceramic as a drive source in an impact type print head used in an output device such as a computer. The present invention relates to an impact type print head.

The main goal in print head research and development is high speed.

This means lower power consumption and lower noise. In order to achieve this goal, so-called electrostrictive drive print heads that utilize ferroelectric materials have recently begun to be reconsidered.

However, as is well known, the electrostrictive drive print head, which replaces the electromagnetic print head that currently dominates the market, suffers from the reliability of porcelain and the lack of established design methods for its application.
There are still many problems remaining in practical application.

Recently, most of the electrostrictive methods that have been proposed are making efforts to obtain large displacements as a result of increasing the mechanical compliance of the printing hammer of the printing head.
In order to obtain the initial acceleration, impact force, and high dot frequency of a printing hammer equivalent to that of the electromagnetic type, improvements are still needed, and the present invention specifically relates to an improvement of the printing hammer of an impact type print head.

[Prior art]

Hereinafter, an electrostrictive printing hammer of a conventional impact printing head will be mainly explained based on the drawings.

FIG. 1 is a schematic side sectional view of a conventional printing hammer, in which 1 is a piezoelectric ceramic, 2 is an elastic plate, 3 is a printing hammer with an asymmetric bimorph configuration in which the piezoelectric ceramic 1 and the elastic plate 2 are bonded together, and 4 is a printing hammer. A power supply lead wire to the piezoelectric ceramic 1 of the hammer 3, 5 a printing wire attached to the free end side of the printing hammer 3, 6 a platen, 7 a printing paper wrapped around the platen 6, 8 a printing paper 7 and This is an ink ribbon interposed between printing wires 5.

A indicates the fixed point of the printing hammer 3, the X axis indicates the longitudinal direction of the printing hammer 3, and the z axis indicates the axial direction of the printing hammer 3 in the thickness direction. Located on the midplane.

The approximate performance of the printing hammer 3 is as follows: wire stroke (platen gap) 〉0.4 mm, impact printing stress of 14 KV-, and repetition dot frequency 〉700 Hz.
etc. are set as necessary conditions.

Next, the operation of the conventional printing hammer 3 configured as described above will be explained.

A voltage V(t) is applied to both electromagnetic surfaces of the piezoelectric magnet 1 through a lead wire 4 leading from a power source.

Then, the printing hammer 3 rotates around point A, accelerates the initial printing wire 5, and transfers the ink of the ink ribbon 8 onto the printing paper 7 wound around the platen 6.

Printing is performed in this way, and the lateral vibration 11+(xl t ) of the printing hammer 3 with one end fixed and the other end free is t, where t is a normal function representing the width distribution of the printing hammer 3. This is an eigenvalue that satisfies the eigenvalue determination method formula (3) derived by substituting boundary conditions.

In addition, Jt, 4: Elastic compliance of porcelain 2 elastic plate, ρ1. ρ2: each density, d: piezoelectric constant, kl: electromechanical coupling coefficient, t: hammer length, A1: area moment of hammer per unit width with respect to porcelain, hl, h2: each plate thickness, b
lI2110: Moment of inertia of the area of the porcelain 2 elastic plate and moment of inertia of the area of the porcelain alone of the printing hammer 3 per unit width, V(t): Applied voltage, t: Time.

Therefore, the steady displacement/position t) of the wire point with the time term set to zero from equation (1) is given by (4). Note that ve is the applied voltage in a steady state.

The theoretical value expressed by equation (4) is calculated, and a comparison with actual measurement data of an actually prototype sample will be explained based on FIG. 2.

FIG. 2 is a graph showing a comparison between the theoretical steady-state displacement of the same mathematical model and actually measured data. In addition, hl=0.3=, A〒=
(5,9X 1010) ”m2//N,,cL1=
3. IX10-10m/V, Ve=200V
, l = 3' Omyn, "2 = (2,06X
10) m/N.

As shown in the graph, under a constant voltage, the smaller the value of 1 (Z), the larger 1 (Z) becomes, which also makes w (t) the maximum. It turns out that it gets bigger.

Next, the theoretical solution and actually measured waveform of the transient flight behavior of the printing hammer 3 shown by equation (1) will be explained using xll f parameters shown in FIG. Note that kl-0°33, and the other constants are the same as those explained in FIG. 2 above.

FIG. 3 is a comparison graph of the lateral vibration solution of the printing hammer 3 of the same mathematical model and measured data.

As shown in the graph, the high-order vibration mode of the electrostrictively driven printing hammer 3 has an adverse effect on the impact printing behavior between the printing wire 5 and the printing medium (ink ribbon 8, printing paper I, and platen 6). ing.

However, in reality, by attaching an appropriate mass to the free end of the printing hammer 3 shown in FIG. 2, the initial acceleration of the printing hammer 3 during driving is sacrificed; A method is used to suppress higher-order vibration modes to a smaller level using inertia effects.

In the printing hammer 3 that does not use this method, due to the high-order vibration mode generated, the speed of the printing wire 5 attached to the tip changes during flight, as shown by the waveform of x4 = 1 in the graph of FIG. Even if the distance between the printing wire 5 and the platen 6 changes slightly, the impact force will fluctuate greatly.

As is clear from the above, the vibration form of the printing system in which the printing hammer 3 performs printing is strictly dependent on the first vibration mode, and higher vibration modes have negative effects on the printing mechanism such as the generation of noise. Simply giving this will create a condition that is not suitable for printing.

Next, the impact behavior when the tip of the printing wire 5 contacts the printing medium (ink ribbon 8, printing paper 7, and platen 6) will be described.

The impact force generated by the collision of the print wire 5 with the print medium is a unique longitudinal elastic wave determined by the material, length, diameter, etc. of the print wire 5. This longitudinal elastic wave of the printing wire 5 propagates from the tip of the printing wire 5 through the inside and reaches the printing hammer 3.

This longitudinal elastic wave induces transverse vibration of the printing hammer 3.

However, in general, the longitudinal vibration of the printing wire 5 as in this model,
In a collision system involving coupled lateral vibration of the printing hammer 3, 1. As long as the printing wire 5 does not buckle, the effect of this longitudinal vibration on printing can be almost ignored. That is 1,
This is because the stiffness of the printing medium is very small compared to the longitudinal stiffness of the printing wire 5, and the bending stiffness of the printing hammer 3, which is connected in series with the printing wire 5, is also small.

Therefore, it can be considered that the impact force propagated from the printing wire 5 acts directly on the printing hammer 3, which causes the printing hammer 3 to generate transverse vibrations having a relatively large amplitude distribution.

The amplitude distribution of the printing hammer 3 is small if the bending stiffness of the printing hammer 3 is small, and the glaze becomes large, resulting in negative effects such as a decrease in printing force, a longer contact time between the printing wire 5 and the printing medium, and a delay in the return of the printing wire 5. to occur.

The conventional impact-type printing hammer using electrostrictive drive has been described above, but as a result, the following drawbacks arise.

If the thickness of the material of the printing hammer 3 is made thinner in order to obtain the large flight distance and high-speed operation required for printing, the bending stiffness of the printing hammer 3 will also be reduced, which will reduce the large impact force during printing. ``This is a drawback that inevitably occurs due to the inconsistency of the printing mechanism that cannot be used.

[Purpose of the invention]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the contradictions in the conventional printing mechanism by completely forming a flexible insulating layer on the piezoelectric magnetic surface and the back surface of the elastic plate, which constitute the main part of the printing hammer.

[・Structure of the invention]

Its structure is as follows.

A flexible insulating layer is formed on the back surface of an elastic plate having a movable plate in the center, and a predetermined inertial mass having a printing wire is mounted and fixed on the plate of the elastic plate.

On the other hand, a flexible insulating layer similar to the elastic plate is formed on the surface of a piezoelectric ceramic which is divided into two pieces and has electrode layers on the front and back sides, and the inertial mass is mounted and fixed on the elastic plate through the center. The upper plate and the base plate are provided above and below with notched grooves and pivots that support the rotation of an inertial mass that rotates together with the elastic plate.

By doing this, it is possible to attenuate the high-order vibration generated in the printing hammer and the resulting lateral and longitudinal vibrations by the two inertia masses, the elastic plate, and the flexible insulation layer formed piezomagnetically. .

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

FIG. 4 is an exploded perspective view of the printing/SS mother showing two embodiments of the present invention, FIG. 5 is an enlarged side sectional view of the bimorph part, and FIG.
The figure is a perspective view showing the assembled state, and FIG. 7 is a side sectional view showing the operating state.

In the figure, 9 is a printing wire, and 10 is an inertial mass that is fixed to the printing wire 9 and faces high-order vibrations.

11 is an elastic plate; 12 is a cutout hole formed in the center of the elastic plate 11 by curving both sides of the tip; 13 is a movable plate protruding from the curved portion of the cutout hole 12 into the cutout hole 12; 14;
is an elastic support portion for the rotation of the elastic plate 11, and an inertial mass 10 having a printing wire 9 is mounted and fixed on the plate 13 of the elastic plate 11 over the entire opposing surface by welding or gluing.

15 is a piezoelectric magnet, and an inertial mass 1 is placed on the elastic plate 11.
Glue with 0 in the center and print an asymmetrical bimorph type.
It constitutes the main part of the market.

Here, this bimorph will be explained based on FIG.

16 is a ferroelectric material P provided on both main surfaces of the piezoelectric magnet 15.
An electrode layer such as ZT, 17 is a high-strength and very thin bonding layer that is mated with the piezoelectric magnet 15 having the elastic plate 11 and the electrode layer 16, and 1B is the front surface of the elastic plate 11 and the back surface of the piezo magnet 15. The flexible insulating layer 18 provided therein acts to quickly attenuate high-order transverse vibrations and longitudinal vibrations that occur, as will be explained later.

Returning to the above description, 19 is a base plate, 20 is a cutout groove provided in the base plate 19 for the rotation of the inertial mass 10, and 21 is a pivot that supports the rotation of the inertial mass 10, and 21 is a pivot that supports the rotation of the inertial mass 10. The main part of the bimol type printing hammer is mounted on the printer.

22 is a spacer for clamping placed on the piezoelectric magnet 15, 23 is an upper plate that also serves as a clamp for the main printing hammer, 24 is a cutout groove provided in the upper plate 23 for rotation of the inertial mass 10, and 25 is an inertial spacer. This is a pivot that supports the rotation of the mass 10, and the pivot 25 of the upper plate 23 and the pivot 21 of the base plate 19 are formed to face each other.

Incidentally, c-c' indicates an inflection point in the rotational deflection curve near the elastic support portion 14 of the elastic plate 11, and since this is a location that receives relatively large bending stress, the notch hole 12 in this portion is As shown, it forms an appropriate curve.

Next, a description will be given of the longitudinal vibration in addition to the lateral vibration of the printing hammer, which is generated due to discontinuity of internal stress when a voltage is applied between the electrodes 16 of the piezoelectric magnet 15.

For example, if we take the rectangular printing hammer as mentioned above as an example, its longitudinal vibration u, (xlt) is! Hail to you. Note that Ui is a normal function that satisfies the boundary conditions.

In this way, as described in the conventional example, the flight of the printing hammer for printing must be based on the first vibration mode of transverse vibration. However, in addition to inducing the transverse vibration component of the first to infinite mode by applying voltage, it also induces the longitudinal vibration shown in equation (5), which adversely affects the flight behavior of the printing hammer. Additionally, it can be a source of annoying noise. The present invention eliminates the generated undesirable high-order transverse vibration and longitudinal vibration by using the inertial mass 10, the elastic plate 11, and the piezoelectric ceramic 15.
It can be quickly attenuated by the flexible insulating layer 18 provided on the top.

One drive of the printing hammer of the present invention will be explained below.

First, when a voltage is applied between both electrode layers 16 of the piezoelectric ceramic 15, the piezoelectric ceramic 15 and the elastic plate 11 rotate approximately around one end of the clamping spacer 22 and start flying, as shown in FIG. This is because one of the inertial masses 10 is loosely fitted into a notched groove 20 formed in the base plate 19 and the other is loosely fitted into a notched groove 24 formed in the upper plate 23, so that the inertial mass 10 rotates about the pivot 21 of the base plate 19. By doing so, the printing wire 9 is driven to perform printing.

At this time, approximately c-d of the elastic support portion 14, which is both remaining portions of the elastic plate 11 with respect to the notch hole 12, becomes an inflection point in the deflection curve, and becomes a location receiving relatively large bending stress. . For this reason, the elastic support portions 14 of the notch holes 13 forming the elastic support portions 14 are designed to be appropriately curved to avoid fatigue failure due to stress concentration.

As mentioned above, the inertial mass 10 performs rotational motion using the piezoelectric force as a forcing force, but the natural frequency of the rotational vibration system of the inertial mass 10 is much smaller than the frequency component of this piezoelectric forcing force. Therefore, the rotational movement mainly corresponds to the first vibration mode of the piezoelectric forcing force. Therefore, high-order vibration components that are undesirable for printing behavior, which was a drawback of the conventional method, are removed by such a motion system, and the inertial mass 10 can fly stably without including high-order components, and the attached printing wire 9 This means that a constant flight speed can be maintained even if the platen gap changes slightly.

Next, the impact behavior in which the printing wire 9 collides with the printing medium to form printing pixels will be explained.

As explained in the conventional example, this impact behavior is determined using parameters such as the impact force and the contact time between the wire and the medium, and will not be explained again, but it occurs when the bending stiffness of the hammer is small. Since the high-order vibration caused by this is suppressed by using the inertial mass 10 to hammer the bending stiffness which is larger than that of the conventional method, a sufficient effect can be exerted on the impact behavior of the printing wire 9. This is because the large bending stiffness of the hammer can be regarded as a collision between the rigid body and the printing medium, and this eliminates the occurrence of undesirable vibrations in the hammer, reducing the contact time between the printing wire 9 and the printing medium. Print wire 9
This results in a sinusoidal wave-like high peak value of printing force.

At this time, it goes without saying that in the inertial mass 10, it is desirable that the tip of the printing wire 9 and the fulcrum supported by the pivot 21 be in a center-of-impact relationship with each other, and this can be easily achieved. For this reason, in the embodiment of the present invention, a suitable cutout groove 20 is provided in the base plate 19.

Furthermore, next, the behavior of the inertial mass 10 until it returns to the equilibrium position of the hammer after the impact is completed will be explained.

In the conventional model, the return movement includes a high-order lateral vibration component caused by the impact, which causes rebound even after returning to the equilibrium position9, and causes fluctuations in the impact movement due to the next drive. This was a major factor in causing breakage of piezoelectric ceramics.

However, in the embodiment of the present invention, a stable return operation can be realized due to the strong return kinetic energy of the inertial mass 1o and the damping effect of the flexible insulating layer 18.

However, when the inertial mass 10 returns to the equilibrium position at high speed, the entire contact surface with the base plate 19 receives a repulsive force, and the motion of the inertial mass 10 becomes a rebound with a linear component and a rotational component. .

In order to reduce this phenomenon, in the present invention, a notch groove 24 is provided in the upper plate 23, which also serves as a clamp for the printing hammer, to form a pivot 25, which is connected to the base plate 19.
By installing the inertial mass 10 at an appropriate position corresponding to the position of the pivot 21, the linear motion of the inertial mass 10 is completely restrained, and the rebound due to the remaining rotational component force can be reduced to the point where it can be almost ignored.

However, if a more complete stationary state is required, it is also possible to perform braking by applying voltage to the piezoelectric magnet 15 again at an appropriate timing during the return process of the inertial mass 10.

In the embodiment of the present invention, one of the plurality of printing hammers installed in the printer is used as a representative.

〔Effect of the invention〕

As explained above in detail, in the present invention, a flexible insulating layer is formed on the back side of an elastic plate having a movable plate in the center, and a predetermined inertial mass having a printing wire is mounted and fixed on the plate. On the other hand, a flexible insulating layer similar to the elastic plate is formed on the surface of the piezoelectric magnet having electrode layers on the front and back sides of the piezoelectric material divided into two pieces, and the inertial mass is mounted and fixed on the elastic plate through the center. ．． The printing hammer has an upper plate and a base plate that have a notch groove and a pivot that support the rotation of the inertial mass that rotates with the elastic plate above and below, so the following effects can be achieved in printing and driving. able to demonstrate.

This is due to the noise caused by the high-order vibration components of the electrostrictive drive type printing hammer and the inevitable contradiction. This can be solved by increasing the vibration and absorbing high-order lateral vibration by the flexible insulating layer, which has the effect of driving the hammer quickly and smoothly.

This has the effect of reducing the harsh noise that occurs in conventional printing hammers, stabilizing the operation of the printing hammer during its initial flight, and
Since it is not affected by the high-order lateral vibration component of the hammer induced by impact, it has the effect of obtaining a sinusoidal wave-like high printing force peak value, and the effect of stabilizing the return operation after impact and increasing the repetition frequency. .

Due to these effects, printing hammers that can achieve high output equivalent to electromagnetic types and can be driven with low power consumption are used mainly in print heads of printers used in computer output devices, as well as electromagnetic relays and high-speed relays. It can be particularly usefully used for high-density printing of Chinese characters, image output, graphic output, etc., which are currently in high demand on the market.

[Brief explanation of the drawing]

Figure 1 is a schematic side sectional view of a conventional printing hammer, Figure 2 is a graph showing a comparison between the theoretical value steady displacement of the mathematical model and measured data, and Figure 3 is the lateral vibration solution of the printing hammer based on the mathematical model and the measured data. 4 is an exploded perspective view of a printing hammer showing an embodiment of the present invention, FIG. 5 is an enlarged partial sectional view of the bimorph part, FIG. 6 is a perspective view showing the assembled state, and FIG. 7 FIG. 2 is a side sectional view showing an operating state. 9... Printing wire 10... Inertial mass 11... Elastic plate 12... Notch hole 13... Plate 15.
... Piezoelectric magnetism 16... Electrode layer 18... Flexible insulating layer 19... Base plate 20... Notch groove 2
1... Pivot 22... Spacer 23... Upper plate 24... Notch groove 25... Pivot Patent Applicant Oki Electric Industry Co., Ltd. Representative Patent Attorney Takashi Kanakura Time (ms) q4D 3 @6r2 Procedural Amendment (Voluntary) November 7, 1980 Director-General of the Houne Agency Kazuo Wakasugi Showing several items 3, 1981 Patent Application No. 079037 Title Related to the case of a person who uses an impact type print head Patent applicant: 1-7-12 Toranomon, Minato-ku, Tokyo Name (029) Oki Electric Industry Co., Ltd.
Nankai Danrijin 7 Contents of amendment 1 We will amend the full text of the specification as attached. Details: 1. Name of the invention: Impact-type printing head 2. Claim 1: An asymmetrical printing head made by fixing a piezoelectric ceramic having a pair of electrode surfaces on both main surfaces to an elastic plate having a printing wire fixed to one end. In an impact type print head configured as a bimorph type printing machine, a movable plate is formed in the center of the elastic plate, and a predetermined inertial mass having a printing wire is fixed to the plate of the elastic plate, while the piezoelectric A 'filfj percussion type print head, characterized in that the piezoelectric ceramic is mounted and fixed on an elastic plate by dividing the porcelain into two parts and placing the inertial mass in the center. 3. Detailed Description of the Invention [Technical Field] The present invention relates to gXJm used in output devices such as computers.
Among the type print heads, the present invention relates to electrostrictive drive type impact type print heads that utilize piezoelectric strain such as piezoelectric ceramics as a driving source. The main goal in print head research and development is high speed. This means lower power consumption and lower noise. In order to achieve this goal, so-called electrostrictive drive print heads that utilize ferromagnetic bodies have recently begun to be reconsidered. However, as is well known, the reliability of porcelain and the design method for its application have not yet been established for direct drive print heads, which replace the electromagnetic print heads that currently dominate the market.
There are still many problems remaining in practical application. Recently, most of the electrostrictive methods that have been proposed have been made in an effort to achieve great success as a result of increasing the compliance of the printing hammer of the print head.
In order to obtain the initial acceleration, impact force, and high dot frequency of the printing hammer C equivalent to that of the electromagnetic type, there is still a need for improvement, and the present invention specifically relates to an improvement of the printing hammer of the hook type print head. [Prior Art] Below, an electrostrictive drive type printing hammer of a conventional impact type printing head will be explained based on the drawings. Fig. 1 is a cross-sectional view of the conventional printing hammer from the open side. Piezoelectric ceramic, 2 is an elastic plate, 3 is a printing hammer with an asymmetric groove bottom made by laminating the piezoelectric ceramic 1 and the elastic plate 2 together, 4 is a printing hammer 3
The power supply lead wire to the piezoelectric ceramic 1, 5 is the printing wire attached to the free fiitA '11Ill of the printing machine 3, 6 is the platen, 7 is the printing paper wrapped around the platen 6, 8 is the printing paper 7 The ink ribbon is interposed between the printing wire 5 and the printing wire 5. A indicates the fixed point of the printing hammer 3, and the X axis indicates the printing hammer 3.
The longitudinal direction of the printing hammer 3 and the Z axis indicate the axial direction of the thickness direction of the printing hammer 3, and the intersection of the X-Z axes is located on the neutral plane of the printing hammer 3. In addition, the approximate performance of the above printing number 3 is as follows: wire stroke (platen gap) ≧Q, 4 am, impact printing stress =:= 14 K9/1tn2, and repeating dot frequency>700) (Z, etc.) are set as necessary conditions. Next, the operation of the conventional printing machine 3 configured as described above will be explained.A voltage V (t) is applied to both electrode surfaces of the piezoelectric ceramic 1 through the lead wire 4 leading from the power supply. - The printer 3 begins to rotate around point A, accelerating the printing wire 5, and transfers ζ78 ink per day onto the printing paper 7 wrapped around the flatten 6. In this way, printing is performed. This wall is fixed at one end,
Rectangular printing with free other end
Therefore, /c) L satisfies the eigenvalue determination method % formula % (3) derived by substituting the conditions It is an eigenvalue. Furthermore, Elastic Compliance of Porcelain, 5$ Elastic Plate, /) 1. J! l'2', each density, d 1
', piezoelectric constant, kl: electromechanical coupling coefficient, L: /% length, A1: area moment of hammer per unit width, h. A2. Each plate thickness, 11. I2. Io: Moment of inertia of area of the printing hammer 3 per unit width similar to the elasticity of porcelain 9 and moment of inertia of area of porcelain alone, V(t): Applied voltage, t: Time. Therefore, from equation (1), the steady displacement *w<t, ) at the wire point with the time term set to zero is given by . . . (・1). Note that Ve is the applied voltage in a constant peak state. Next, a theoretical value expressed by equation (4) is calculated, and a comparison with actually measured data of a prototype sample will be explained based on FIG. 2. FIG. 2 is a graph showing a comparison between the theoretical steady-state displacement of the same mathematical model and actually measured data. Direction, hl = 0.3mm,
d"j = (5,9X 1 olo)-1n, 2/
N, dl--3, I X 10-10m/V,, Ve
= 200 V, l = 3 Q tnra, n, = (
z,o6 It can be seen that the value of .
degree. The theory of flight behavior and the actually measured C countershape are shown in the third example using 't/l as a parameter and will be explained using ζ. Nao, n1-
〇:33 must be 9, and the other constants are the same as those in Figure 2 on the previous ξ. Figure 3 is a comparison graph with the slight vibration level and sub-data of the print//73 of the same mathematical model. This shows that the mode has an adverse effect on the printing behavior between the printing wire 5 and the printing medium (ink ribbon 8, printing paper 1, and platen 6).However, in reality, the By attaching an appropriate mass to the free end of the printing machine 3, the initial acceleration of the printing machine 3 during driving will be sacrificed, but
The inertia effect of the mass is used to suppress higher-order vibration modes. In the printing hammer 3 that does not use this method, the high-order vibration mode generated by the printing hammer 3 causes the printing wire 5 previously installed at the tip to
As shown by the waveform of J/-1 in the graph of FIG. The power will fluctuate greatly. As is clear from the above, the vibration form of the printing thread used for printing by the printing hammer 3 depends on the first vibration mode, and the higher vibration mode is caused by the printing mechanism such as the generation of noise. This will only give a bad impression to the user and create a condition that is not suitable for printing. Next, the impact behavior when the tip of the printing wire 5 contacts the printing medium (ink ribbon 8, printing paper 7, and platen 6) will be described. The impact force generated by the collision of the printing wire 5 with the printing medium becomes a unique longitudinal elastic wave determined by the material, length, diameter, etc. of the printing wire 5. This longitudinal elastic wave of the printing wire 5 propagates from the tip of the printing wire 5 through the inside and reaches the printing hammer 3. This longitudinal elastic wave induces transverse vibration of the printing hammer 3. However, in general, the longitudinal vibration of the printing wire 5 as in this model,
In a collision system involving coupled transverse vibration of the printing hammer 3, the influence of this longitudinal vibration on printing can be almost ignored unless buckling occurs in the printing wire 5. That is, the stiffness of the printing medium is very small compared to the longitudinal stiffness of the printing wire 5, and the stiffness of the printing hammer 3 connected in series with the printing wire 5 is also small. It can be considered that the impact force propagated from the printing hammer 5 acts directly on the printing hammer 3, which causes the printing hammer 3 to generate transverse vibrations having a relatively large amplitude distribution. The smaller the bending stiffness of the printing hammer 3, the larger the amplitude distribution of the printing hammer 3 becomes. cause harm. The conventional impact-type printing hammer using electrostrictive drive has been described above, but as a result, the following drawbacks arise. If the thickness of the material of the printing hammer 3 is made thinner in order to obtain the large flying penetration and high-speed operation required for printing, the bending stiffness of the printing hammer 3 will also be reduced, which will reduce the large 148° in printing. The inconsistency of the printing mechanism, in which the printing force cannot be obtained, is a drawback that inevitably occurs. [Object of the Invention] Therefore, the purpose of the present invention is to solve the contradictions of the conventional printing mechanism by adding an inertial mass to obtain a high peak printing force, and to reduce high-order vibration components that cause problems in printing. It was done in order to [Structure of the invention] The structure is as follows. A predetermined inertial mass ffi k having a printing wire is mounted and fixed on a movable plate formed at the center of the elastic plate. On the other hand, a piezoelectric ceramic that is divided into two pieces and has electrode layers on the front and back sides is joined to an elastic plate to integrate it, and the inertial mass rotates with the grate of the elastic plate above and below! $IJ'? - The structure includes a base plate and a heat/% plate with a notch and pivot for possible support. By doing so, it is possible to reduce high-order vibrations occurring in the printing hammer and the resulting lateral vibrations and longitudinal vibrations. [Example] An example of the present invention will be described below based on the drawings. FIG. 4 is an exploded perspective view of a printing hammer showing an embodiment of the present invention, FIG. 5 is an enlarged partial side sectional view of the bimorph section, FIG. 6 is a perspective view showing the assembled state, and FIG. 7 is an operating state. FIG. In the figure, 9 is a printing wire, and 10 is an inertial mass that opposes high-order vibrations to which the printing wire 9 is fixed. 11 is an elastic plate; 12 is a notch hole formed in the center of the elastic plate 11 by bending both sides of the tip; 13 is a flexible HDable grate formed protruding from the curved portion of the notch hole 12 into the notch hole 12;
14 refers to the rotation of the sex plate 11.
/l: Support 1, I'! '11i, printed soy-\'
9γ ゛ イ］］ / Ko 10 property IT1: 10 & J: The entire opposite area on the plate 13 with elastic elasticity 1 is exploded or adhesive, etc. 15 is a polarized piezoelectric ceramic made of a ferroelectric material such as PZT, which is bonded onto the elastic plate 11 with the inertial mass 10 in the center, and constitutes all the main parts of the asymmetric bimorph type printing hammer. . Here, this bimorph will be explained based on FIG. 1G is an electrode layer provided on both main surfaces of the piezoelectric ceramic 15, and 17 is a high-strength and very thin bonding layer that bonds the elastic plate 11 and the piezoelectric ceramic 15 having the electrode layer 16. Reference numeral 18 denotes a flexible insulating layer provided on the back surface of the elastic plate 11 and the surface of the piezoelectric ceramic 15, and the flexible insulating layer 18 prevents high-order transverse vibrations and longitudinal vibrations that occur, as will be explained later. Although it is effective for quickly reducing grief, it does not need to be provided. Returning to the above description, 19 is a base plate, 20 is a notch provided in the base plate 19 for rotation of the inertial mass 10, and 21 is a pivot that supports the inertial mass 1o, and the base plate The main part of the bimorph type printing hammer is mounted on 19. 22 is a spacer for a clamp placed on the piezoelectric ceramic 15, 23 is an upper plate that also serves as a clamp for the main printing hammer, 24 is a notch provided in the upper plate 23 for the rotation of the inertia IT 10, and 25 is a spacer for clamping. It is a pivot that supports rotation of the inertial mass 10, and the upper plate 23
pivot 25 of the base plate 19 and pivot 2 of the base plate 19
1 are formed so as to form opposing positions. Incidentally, c-c' indicates an inflection point in the rotational deflection curve near the elastic support part 14 of the elastic plate 11, and since this is a point that receives relatively large bending stress, the notch hole 1 in this part is
2 (forms an appropriate curvature as described above).Next, when a voltage is applied between both electrodes 16 of the piezoelectric ceramic 15, the horizontal vibration of the printing hammer caused by the discontinuity of the internal stress The additional vertical vibration will be explained.For example, if we take the rectangular printing hammer as mentioned above as an example, its vertical vibration ucx,t) will be reduced by . Note that U is a normal function that satisfies the boundary condition (f). As mentioned in the conventional example, the flight of the printing hammer for printing must be based on the first vibration mode of transverse vibration. However, the voltage In addition to inducing transverse vibration components of the first order to infinite modal mode, the application of It also becomes a source of harsh noise.The present invention
The generated high-order lateral vibrations and vibrations that are not heavy on the vehicle can be reduced by the inertial mass 10, and can be quickly damped by the flexible insulating layer 18 provided on the elastic plate 11 and the piezoelectric ceramic 15. . Below, driving of the printing hammer of the present invention will be explained. When a voltage is applied between the two electrodes 16 of the piezoelectric ceramic 15, the piezoelectric ceramic 15 and the elastic plate 11 rotate approximately 101 around one end of the clamping spacer 22 as shown in FIG. Start flying. This is because one of the inertial masses 10 is loosely fitted into the notched groove 20 formed in the base plate 19 and the other is loosely fitted into the notched groove 24 of the upper plate 23.
By rotating about the pivot 21 of the base plate 19, the printing wire 9 is driven and printing is performed. At this time, the two remaining portions of the elastic support portion 14 relative to the notch hole 12 of the elastic plate 11, near the dog B and 4 cmc', are the inflection points in the deflection curve, and are places subject to relatively large bending stress. Become. For this reason, the elastic support portions 14 of the notch holes 13 forming the elastic support portions 14 are designed to be appropriately curved to avoid lateral breakage due to the stress flux. As mentioned above, the inertial mass 10 performs rotational movement by using the piezoelectric force as a forcing force, but the rigidity 1 of the rotational vibration system of the inertial mass 1o
Since one frequency is far smaller than the frequency component of this piezoelectric force, the rotational movement mainly corresponds to the first vibration mode of the piezoelectric force. Therefore, high-order vibration components that are undesirable for printing behavior, which was a drawback of the conventional method, are removed by such a motion system, and the inertial mass 10 can fly stably without including the open wave component, and the attached printing The wire 9 can maintain a constant flight speed even if the platen gap changes slightly. Next, the impact behavior in which the printing wire 9 collides with the printing medium to form printing pixels will be explained. This impact behavior is determined using parameters such as the impact force and the contact time between the wire and the medium, as explained in the conventional example, and will not be explained again, but if the bending stiffness of the hammer is small, Since high-order vibrations with a large amplitude distribution are suppressed by being hammered with large bending stiffness by the inertial mass 10, the printing wire 9
It is also possible to exhibit sufficient effects in terms of impact behavior. This is because the large bending stiffness of the hammer can be regarded as a disconnect between the rigid body and the printing medium.
This eliminates the occurrence of undesirable vibrations of the hammer, thereby shortening the contact time between the printing wire 9 and the printing medium, and resulting in a high peak printing force value of the printing wire 3 having a sine a shape. At this time, it goes without saying that in the inertial mass 10, it is desirable that the tip of the printing wire 9 and the fulcrum supported by the pivot 21 be in a centripetal relationship with each other, and this can be easily achieved. For this reason, in the embodiment of the present invention, a suitable cutout groove 20 is provided in the base plate 19. Furthermore, next, the behavior of the inertial mass 10 until it returns to the equilibrium position of the hammer after the impact is completed will be explained. In conventional models, the return movement includes a high-order lateral vibration component caused by the impact, which causes rebound even after returning to the equilibrium position, which usually causes fluctuations in the impact movement caused by the next drive. This was also a major factor in causing breakage of piezoelectric ceramics. However, in the embodiment of the present invention, a stable return operation can be realized due to the strong return kinetic energy of the inertial mass 10 and the damping effect of the flexible insulating layer 18. However, when the inertial mass 10 returns to the equilibrium position at high speed, the entire contact surface with the base plate 19 receives a repulsive force, and the movement of the inertial mass 10 becomes a rebound with a linear component and a rotational component. In order to reduce this phenomenon, in the present invention, a notch groove 24 is provided in the upper plate 23, which also serves as a clamp for the printing hammer, to form a pivot 25, which is connected to the base plate 19.
By installing it at an appropriate position corresponding to the position of the pivot 21, the straight door movement of the inertial member 10 can be completely restrained, and the rebound due to the remaining rotational component effort can be reduced to almost negligible. However, if a more complete stationary state is required, it is also possible to perform braking by applying voltage to the piezoelectric ceramic 15 again at an appropriate timing during the return process of the inertial mass 10. . In the embodiment of the present invention, one of the plurality of printing hammers installed in the printer is used as a representative. [Effects of the Invention] As described in detail above, in the present invention, a predetermined inertial mass having a printing wire is mounted and fixed on a movable plate formed in the center of an elastic plate, and electrodes are placed on the front and back sides of the two divided plates. A piezoelectric ceramic having a layer is joined and integrated with the elastic plate, and a notch groove and a pivot that support the rotation of the inertial mass that rotates together with the plate of the elastic plate are provided above and below it.・Since the printing hammer is made up of a two-plate and a base plate, the following effects can be achieved in printing drive. This is due to the noise caused by the intermittent vibration component of the electrostrictive drive type printing hammer and the inevitable contradiction of the printing hammer, which has a constant relationship between the force-operation time and the impact, and the increase in bending stiffness due to the inertial mass. This has the effect of making the hammer move quickly and smoothly. This has the effect of reducing the harsh noise that occurs in conventional printing hammers, stabilizing the operation of the printing hammer during its initial flight, and
Since it is not affected by the high-order lateral vibration component of the hammer induced by impact, it has the effect of obtaining a sinusoidal wave-like high printing force peak value, and the effect of stabilizing the return operation after impact and increasing the repetition frequency. Become. Due to these effects, printing machines that can achieve high output equivalent to electromagnetic types and drive with low power consumption can be used in the print heads of printers used in computer output devices, and are currently available on the market. It can be particularly useful for high-density printing, image output, and graphic output printers that require high-density printing. In addition, electromagnetic relays,
Applications to related relays and many other types of actuators are also possible. 4. Brief explanation of the drawings Fig. 1 is a schematic side sectional view of a conventional printing hammer, Fig. 2 is a graph showing a mathematical model (fffl Figure 4 is an exploded perspective view of a printing hammer showing an embodiment of the present invention, 'fJ
5 is an enlarged partial cross-sectional view of the bimorph part, FIG. 6 is a perspective view showing the assembled state, and FIG. 7 is a side sectional view showing the moving state. 9. Printing wire 10. Inertial property Heavy 11... Elastic plate 12... Notch hole 13... Plate 15 Piezoelectric ceramic 16... Electrode layer 18... Flexible insulating layer
19...Base play) 20...Notch a 21.
22...Spacer 23...Upper plate 24...Notch groove 25...Pivot patent applicant Oki Denki Kogyo Co., Ltd. Agent Rokusho Buraji Suzume Kutsu

Claims (1)

[Claims] 1. In an impact type print head configured with an asymmetrical bimorph type printing hammer formed by fixing a piezoelectric magnet having a pair of electrode surfaces on both main surfaces to an elastic plate having a printing wire fixed to one end, A flexible insulating layer is formed on the back surface of a movable plate, and a predetermined inertial mass having printed wires is fixed to the plate of the elastic plate, while the piezoelectric magnetism is divided into two parts, and a flexible insulating layer similar to the above is formed on the surface of the movable plate. An impact type print head characterized in that the piezoelectric magnetism is mounted and fixed on an elastic plate via an insulating layer formed in the center of the inertial mass.