JPS5814765A - Impact printer head - Google Patents

Abstract

PURPOSE:To utilize a longitudinal effect so as not to generate excessive tension, and to reduce driving power by mounting a stopper regulating motion to a lever transmitting the expansion operation of a piezo-electric body or an electrostrictive ceramic utilizing the longitudinal effect. CONSTITUTION:When voltage is applied to the external terminals 18, 19 of the piezo-electric or electrostrictive ceramic 10, elongation strain is generated to push up the lever 14, and a pin 16 is driven. The breakdown of the piezo-electric body 10 can be prevented without giving strong tensile force to the piezo-electric body by the excessive revolution of the lever 14 because the motion of the lever 14 is limited within a predetermined range by means of the stopper 17 at that time. With the piezo-electric body 10, electrodes 22, 23 are arranged alternately to a piezo-electric material, and it is brought to an extended state when the direction of polarization 26 and the direction of an electric field agree. The piezo-electric or electrostrictive ceramic 10 utilizing such a longitudinal effect is inserted between cap-shaped connecting mechanisms 11, 12, the degradation of strength in a joined section is prevented, and the ceramic is protected by means of the stopper 17.

Description

[Detailed description of the invention] The present invention relates to an impact printer head.

Conventional printer heads that utilize the transverse effect of piezoelectric or electrostrictive ceramics are shown in Figures 1 (a) and (b).
It consists of a transverse effect type electrostrictive vibrator 1 and a pin 2 attached to the tip 1a of this vibrator 1. In such a configuration, in order to obtain a predetermined displacement and speed, a bias voltage is applied in advance to displace the tip of the electrostrictive vibrator 1 in the direction opposite to the platen 7 to the position laiα, and then a voltage opposite to the bias voltage is applied. is applied, and by displacing the tip 1a of the electrostrictive vibrator 1 to the position β, the scissor 2 is moved to the platen 7.
It is colliding with

However, such a printer head has the advantages of low driving power and a simple structure, but has the drawbacks of slow printing speed and a large required volume of the piezoelectric or electrostrictive ceramic. .

SUMMARY OF THE INVENTION The object of the present invention is to eliminate the above-mentioned drawbacks and to provide an impact printer with a small volume requirement of piezoelectric or electrostrictive ceramics and a high printing speed.

The main feature of impact printer heads is the use of longitudinal effect piezoelectric or electrostrictive ceramics. The piezoelectric or Fi electrostrictive ceramic mentioned here includes piezoelectric materials such as zircon and lead titanate, and electrostrictive materials such as manganese and lead niobate. The difference between piezoelectric materials and electrostrictive materials is that the former causes polarization, whereas the latter does not. These piezoelectric or electrostrictive ceramics usually have two effects: a transverse effect and a longitudinal effect.
There are two physical phenomena that can be used. Transverse effect refers to the strain effect in the direction perpendicular to the direction of the electric field applied to the electrostrictive material,
Longitudinal effect means a strain effect in a direction parallel to the direction of the electric field.

The magnitude of distortion due to the transverse effect and the longitudinal effect is approximately the ratio of Poisson's ratio, that is, approximately 1:3 when comparing the same materials. If this is compared with the mechanical energy stored in the piezoelectric or electrostrictive ceramic, it will be the square of the strain, that is, a ratio of 1:9. Therefore, conversely, the volume of piezoelectric or electrostrictive ceramic required to store the required energy is the inverse ratio of the above ratio, or 9:1. That is, the piezoelectric or electrostrictive ceramic volume required to obtain the same mechanical energy is 1/9 when using the longitudinal effect compared to when using the transverse effect.

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

FIG. 2 is a diagram explaining the present invention in detail. In FIG. 2, the mechanical strain generated in the longitudinal effect piezoelectric or electrostrictive ceramic 10 is transferred to the first connecting mechanism 11 and the third connecting mechanism 12.
are transmitted to the vicinity of one end of the lever 14 and the fixing member 15, respectively. On the other hand, the second connecting mechanism 13 that is joined to the first connecting mechanism 11 is arranged between the lever 14 and the fixing member 15. Bin 16 is joined to one end of lever 14. Excitation electrode terminals 18 and 19 are bonded to both sides of the piezoelectric or electrostrictive ceramic 10, and a predetermined voltage is applied thereto. The stopper 17 is used to limit the movement of the lever 14 within a predetermined range and prevent the piezoelectric body 10 from being destroyed.

Next, the effect of the stopper 17 will be explained using FIG.

FIG. 3 (al represents a transient phenomenon of the movement of the lever 14 in the direction of arrow A. The stopper 17 limits the amplitude of the movement of the lever 14 from A1 to A2.

FIG. 3(b) shows the time course of the force applied to the piezoelectric body 10 in connection with this. When a voltage is applied from the outside, the piezoelectric body 10 tries to expand and is therefore subjected to a compressive force Flt-, but in response to the movement of the lever 14, the compressive force is gradually relaxed and the piezoelectric body 10 subsequently receives a tensile force.

In this case, the presence or absence of the stopper 17 acts to control the maximum value of the tensile force. That is, when the stopper 17 is not present, the maximum value F2 of the tensile force is approximately equal to the compressive force F1, but when the stopper 17 is present, the maximum value F3 of the tensile force is a fraction of F2. FIG. 3(C) shows the applied voltage at this time.

As a specific numerical example, when the impact energy of the impact member is ff16000 erg, F z = 20K
F3 is 5KiI for gK. On the other hand, if the cross-sectional dimension of the piezoelectric body is t-2-X3 mm, the strength f of a normal piezoelectric body is
If calculated using 300Kt/-, the strength is 18111I
Thus, the piezoelectric material is destroyed at F2, but it is not destroyed at F3 even if the voltage is applied repeatedly.

5- Thus, the presence or absence of the stopper 17 is of decisive importance for an impact printer head using a longitudinal effect piezoelectric material.

Generally, when this impact printer head is installed in a printer, if the impact printer head is in a normal state, even if the stopper 17 is not present, the collision member will remain on the paper, so that it will have the same effect as a stopper and there will be no problem.

However, if the stopper 17 is missing, the arm will be in a free state or a state close to it when operating only with the head or during adjustment to adjust the distance between the head and the platen to set the appropriate surface printing pressure. This makes it inappropriate as a practical printer.

FIG. 4 shows a basic unit 100 constituting the head of the present invention.
FIG. In the figure, a piezoelectric or electrostrictive ceramic 10 is sandwiched between a first connection mechanism 11 and a third connection mechanism 12. First and third connection mechanisms 11
and 12, as shown in Fig. wt5, includes a cap structure, and is firmly fixed to the piezoelectric and electrostrictive ceramic 10 by adhesive or soldering 61 or the like. This structure is very effective in preventing deterioration of strength at the joint for relatively fragile materials such as piezoelectric or electrostrictive ceramics. 4th again
Referring to the figure, the first and third connecting mechanisms 11 and 12 are joined to a lever 14 and a fixing member 15, respectively. A second connection mechanism 13 adjacent to the first connection mechanism 11
is joined to the lever 14, and the other end of the second connection mechanism 13 is joined to the fixing member 15. A pin 16 is connected to one end of the lever 14. The stopper 17 is attached to the fixed member 15, and its tip end is connected to the lever 14.
They are arranged so as to maintain a predetermined space from each other.

FIG. 6 shows a state in which the unit 100'fr shown in FIG. 4 is fixed to the mounting member 21. Pin 16 of unit 100
is disposed through a hole provided in a stopper 17 which also serves as a guide for the pin 16.

FIG. 7 is a diagram explaining the operation of the unit 100 shown in FIG. (al is the case when no voltage is applied between the external terminals 16 and 17, (bl is the case when the same voltage is applied.) Due to the voltage application, the piezoelectric body 10 generates an elongation strain, and as a result, the lever 14t- is pushed up. Excite rotation in the θ direction.

If the stopper 17 were not present, the lever 14 would exceed the rotation angle corresponding to the elongation strain of the piezoelectric body 10, producing a strong tensile force on the piezoelectric body.

In the case of FIG. 7, since it hits the stopper 17, there is no need to apply extra tensile force to the piezoelectric body.

Figure 8 shows the structure of the piezoelectric or electrostrictive ceramic 10. Electrodes 22 and 23 are arranged alternately on a piezoelectric material such as lead, and these electrodes 22 and 23 are connected to external electrodes 24 and 25, respectively.Reference numeral 26 indicates the direction of polarization; is reversed for each layer.

The direction of the electric field due to the voltage applied between the external terminals 18 and 190 is indicated by reference numeral 27, and in this figure the piezoelectric material 10 is in an elongated state since the polarization direction and the electric field direction coincide.

FIG. 8 (bl shows the case of manganese-lead niobate isoelectrostrictive material.

The difference from Figure 8 (al) is that there is no polarization.

In this case, the electrostrictive material stretches as the voltage is applied, regardless of the direction of the voltage between the external terminals 18 and 19. A feature of electrostrictive materials is that they have no hysteresis. (Fig. 8+8), (In piezoelectric or electrostrictive ceramics having a layered electrode structure like bl, the required strain can be obtained with a low applied voltage.

As described above, according to the present invention, since the longitudinal effect of piezoelectric or electrostrictive ceramic is utilized, an impact printer head with a simple structure and low driving power can be obtained.

[Brief explanation of the drawing]

Figures 1 and 18 (bl) are perspective views showing the conventional impact printer head tube, Figure 2 is a principle diagram of the basic unit used, Figures 3 (18) to (e) are diagrams explaining the effect of the stopper, Figures 4 and 5 are perspective views showing the basic unit and explanatory diagrams of its parts, Figure 6 is a diagram explaining the operation of the 10-knit, and Figures 8 (Si) and (b).
) is a perspective view showing a piezoelectric and electrostrictive ceramic. In FIG. 6, 21... unit mounting member;
14...Lever, 10...Piezoelectric or electrostrictive ceramic, 15...Fixing member, 11-1
3... Connector 10- (a no (b) dream/mon Fig. 2

Claims (1)

[Claims] A plurality of piezoelectric bodies, each consisting of a piezoelectric body utilizing a longitudinal effect, a means for transmitting the expansion and contraction motion of this piezoelectric body, a lever that responds to the expansion and contraction motion via this transmission means, and a companion printing pin attached to this lever. and a unit fixing means having means for fixing the plurality of printing units, guiding the pins of each unit, and controlling the lever so that it is driven within a predetermined range. impact printer head.