JPS6351148A - Printing head of wire dot printer - Google Patents

Abstract

PURPOSE:To increase a printing speed and to arrange printing pins at high density, by bonding a cantilevered type bimorph vibrator to one end of each of C-shaped actuators having the printing pins. CONSTITUTION:When a current is made to flow to a C-shaped actuator 10 in such a state that an electric field is applied, the actuator 10 is displaced while bimorph vibrators 14, 15 are elastically deformed by electromagnetic force and a printing pin 11 protrudes to record an ink dot. When voltage is applied to the vibrators 14, 15 for a definite time when the pin 11 retracts to a stationary position by the elasticity of the vibrators 14, 15, both vibrators 14, 15 act so as to brake the vibrations of the vibrators themselves. Therefore, the actuator 10 stops immediately at the almost stationary position. Actuators 34, 35 are arranged so that the printing pins 36, 37 engaged with the guide holes 38a, 38b fixed to said actuators are arranged so as to approach each other. When a plurality of the actuators are successively arranged so as to form two rows approaching each other in the direction vertical to the surface of paper, the printing pins can be arranged at high density.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a print head for a low-noise wire dot printer.

[Conventional technology]

Currently, wire dot printers used as computer output devices are mainly of the clapper type.

In this clapper type, an armature is placed at the rear end of the wire, and when this armature is attracted by an electromagnet, the rear end of the wire is struck, the tip of the wire protrudes from the print head against the spring, and the ink ribbon is Dots are struck on the recording paper from behind.

This flapper type produces a lot of noise due to the impact of the armature, so there is a desire to develop a low-noise wire dot printer. As a low-noise type wire dot printer, the electrodynamic type described in Japanese Patent Application Laid-Open No. 60-206669 is considered to be promising.

In this electrodynamic type, a printing pin is attached to the tip of a leaf-shaped actuator wire so as to form a figure 7 shape, and the rear end is fixed. By placing this actuator wire in a magnetic field and passing a current through it, the generated electromagnetic force displaces the actuator wire into an elongated shape, causing the printing pin to protrude.

Therefore, since this type of print head does not use impact force to move the print pin, it has advantages such as almost no noise within the print head and a simple structure.

[Problem that the invention seeks to solve]

In the electrodynamic print head mentioned above,
High-speed printing was not possible. One of the factors that impede this high-speed printing is damped vibration (bound) of the printing pin. In other words, when the printing pin returns to the resting position after dotting, the printing pin vibrates attenuated around the resting position due to the elasticity of the actuator wire, but if during this damped oscillation, electricity is applied to the 7 actuator wires to do dotting. ,
This is because the desired amount of movement and power cannot be obtained, so a time period for the damped vibration to stop is ensured within the printing cycle (actual cycle) of one character. Note that if a large electromagnetic force is applied to speed up the movement of the printing pin, the bounce will naturally increase, causing the printing pin to hit twice, resulting in two misaligned ink dots being recorded. will be done. Another factor is that the resonant frequency of the actuator wire is low, and this is due to the low stiffness (spring constant) of the actuator wire.

In addition, in conventional print heads, the actuator wires protrude horizontally in the form of leaves, so the
If a large number of pins is achieved by arranging ~12 printing pins in two rows in a staggered manner, the left and right actuator lines will hit each other, making it impossible to arrange the printing pins in high density. Therefore, since it is necessary to increase the distance between the two rows of printing pins, there arises an inconvenience that alignment of ink dots during printing becomes difficult.

SUMMARY OF THE INVENTION An object of the present invention is to provide a print head for a wire dot printer that can increase printing speed and arrange printing pins in high density.

[Means for solving problems]

In order to achieve the above object, the present invention has a U-shaped actuator, a printing pin is fixed to the tip side thereof, and at least one cantilever bimorph vibrator is used as a supporting member of the actuator. be.

The bimorph vibrator is deflected to one side by applying a voltage when the printing pin retreats to a predetermined position after the printing point,
The elastic force is canceled out and the brake is applied. As a result, the damped vibration of the printing pin is stopped, so the printing cycle becomes shorter. Further, since the two cantilevered bimorph oscillators also function as supporting members for the actuator, the rigidity of the movable part consisting of the actuator and the bimorph oscillator can be increased. This increases the resonant frequency of the movable part, improves response frequency characteristics, and enables high-speed printing.

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

〔Example〕

In FIG. 1 and FIG. 2, the actuator 10 includes:
Arm parts 10a, 10b and a mounting part 10c for joining the printing pin 11 are formed.

One end of a plate-shaped bimorph vibrator 14.15 is connected to each of the arm portions 10a and 10b of the actuator 10 via an electrically insulating material 12.13. As shown in FIG. 3, this bimorph vibrator 14 is composed of a metal elastic plate (electrode plate) 16 and piezoelectric +ff117.18 bonded to both sides of the metal elastic plate (electrode plate). It is fixed to the main body 19. Further, the bimorph resonator 15 has the same structure, and is driven simultaneously by the driver 20.

As shown in FIG. 4, a U-shaped magnet holder 22 is arranged to surround the arm portion 10a of the actuator 10. As shown in FIG. Magnets 23 and 24 are attached to opposite sides of the magnet holder 22, respectively, and apply a magnetic field perpendicular to the arm portion 10a. In addition, arm 6; l
: By applying a magnetic field in the opposite direction to 10b to generate an electromagnetic force, the movement of the actuator 10 can be made faster. In this case, the magnets 26 and 27 may be placed on the magnet holder 25 so as to face each other.

A guide plate 30 is provided to guide the printing pin 11, and the printing pin 11 is fitted into a guide hole 30a of the guide plate 30. In front of the guide plate 30,
An ink ribbon 31 and a recording paper 32 mounted on a platen roller (not shown) are arranged.

The actuator 10 is made of an aluminum plate with a thickness of 0°2, the arm parts 10a and 10b are each 30 m in length, and the width of the arm 10a and 10b is 30 m, and the width of the 3 parts is adjusted so that the length of the part 10c is 101 times. Punch out a U-shape and use it vertically. A stainless steel wire with a diameter of 0.251 m is used as the printing pin 11, and one end thereof is soldered to the tip side of the actuator 10. Bimorph oscillator 1
4.15 is an elastic plate with a thickness of 0.3 mm and a width of 4. A phosphor bronze plate is used, and piezoelectric plates of zircon/lead titanate, for example, are bonded to both sides of the plate. The bimorph vibrator 14.15 and the actuator 10 are bonded together using an adhesive, such as an epoxy resin, that constitutes the electrical insulating material 12.13.

Next, the operation of the above embodiment will be explained with reference to FIG. When printing, 1. With an electric field applied, a pulsed current ■ is passed through the actuator 10 in the direction of the arrow at time t1. When this pulsed current flows, the generated electromagnetic force acts on the actuator 10. As shown in FIG. 2, the actuator 10 is displaced while elastically deforming the bimorph vibrators 14 and 15, and the travel stage is started. In this travel stage, the printing pin 11 protrudes in conjunction with the displacement of the actuator 10.

When the printing pin 11 moves forward, it collides with the recording paper 32 via the ink ribbon 31. In this collision stage, the ink applied to the ink ribbon 31 is transferred to the recording paper 32, so that ink dots corresponding to the size of the printing pins 11 are recorded on the recording paper 32.

Since the pulse current ■ is supplied only at the initial stage of the travel stage, when the kinetic energy is lost due to the collision of the actuator 10, the printing pin 11 begins to return toward the rest position due to the elasticity of the bimorph oscillators 14 and 15. . In this recovery stage, when the printing pin 11 has retreated to the rest position shown in FIG. 1, the driver 20 applies a voltage to the bimorph vibrator 14.1.5 for a certain period of time. To drive the bimorph vibrators 14 and 15, as shown in FIG. 3, a voltage equal to the polarization is applied to the piezoelectric plate 17, and a voltage opposite to the polarization is applied to the piezoelectric plate 18. For this,
Since the piezoelectric plate 17 contracts and the piezoelectric plate 18 expands, the bimorph vibrator 14,15 acts to damp its own vibrations. Thus, the actuator 10 is prevented from overshooting beyond the rest position due to its inertia and immediately stops at the rest position. Here, if the deformation of the bimorph oscillators 14 and 15 is increased, there is a risk that the printing pin 11 will move forward again and strike twice, so it is necessary to give sufficient deformation to cancel the inertia of the actuator 10. .

As shown in FIG. 5, from time ti when the travel stage starts to time t2 when the recovery stage ends.
The period up to this point is the actual period (printing cycle) required to print one dot. Here, if the bimorph oscillators 14 and 15 are not driven, the printing pin 11 causes damped vibration as shown by the two-dot chain line, so the recovery stage takes time t3.
Therefore, the actual period becomes considerably longer than when the bimorph oscillators 14 and 15 are not driven.

In addition, since the bimorph oscillator 14.15 is used as the spring plate of the second cantilever, the rigidity of the movable part is higher than that of the conventional leaf-shaped actuator wire, and the resonance frequency can be improved. can.

FIG. 6 shows an example of the arrangement of actuators when a large number of pins are used. The two actuators 34, 35 are arranged so that the printing pins 36, 37 fixed thereto are closely aligned. The printing pins 36 and 37 are fitted into guide holes 38a and 38b formed in the guide plate 38, respectively.

When arranging nine printing pins in two rows in a staggered manner, they are spaced a little apart in the direction perpendicular to the paper surface so that the two actuators 34 and 35 are arranged alternately. In this state, the plurality of actuators are sequentially arranged at a constant pitch in two adjacent rows in a direction perpendicular to the paper surface. In this case, it is preferable to interpose a thin insulating film between each actuator wire adjacent to each other in the direction perpendicular to the plane of the paper to prevent the actuator wires from interfering with each other.

FIG. 7 shows an embodiment in which one end of the actuator is supported by a bimorph vibrator, and the same members as in FIG. 1 are given the same reference numerals. In this embodiment, the printing pin 11
The amount of movement can be increased.

In the above embodiment, one of the bimorph oscillators is extended and the other is contracted, but instead, both may be contracted and one of them may be released from the contraction and warped when braking. In addition, if the bimorph vibrator is bent in the retreating direction of the printing pin and held at the most retreated position, and the voltage application is released at the start of the travel stage, the elastic force of the bimorph vibrator will also act on the travel stage. The printing pin can be made to protrude quickly. Furthermore, in the recovery stage of the printing pin, it is desirable to flow a current in the opposite direction to the actuator and also utilize electromagnetic force to increase the retraction speed.

〔Effect of the invention〕

As explained in detail above, in the present invention, a U-shaped actuator is used, at least one cantilevered bimorph vibrator is joined to one end of the actuator, and when the printing pin returns to a predetermined position, the bimorph Since the vibrator is curved to one side, damped vibration of the printing pin can be eliminated and the recovery stage can be shortened. Further, since the bimorph vibrator is used as an elastic support member of the actuator, the rigidity of the movable part can be increased and the moving speed of the printing pin can be increased. Therefore, the present invention:
These improvements can improve printing speed.

Further, in the present invention, since the printing pins are attached to the tip side of the U-shaped actuator, by arranging the actuators in opposite directions, a large number of printing pins can be arranged at high density.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an outline of the present invention. FIG. 2 is an explanatory diagram showing the dot state. FIG. 3 is an explanatory diagram showing the configuration of a bimorph oscillator. FIG. 4 is an enlarged sectional view of the rV-rV cotton shown in FIG. 1. FIG. 5 is a waveform diagram showing the operating state of the present invention. FIG. 6 is an explanatory diagram of the main part showing a state in which printing pins are arranged in two rows. FIG. 7 is a plan view showing an embodiment modified from FIG. 1. 10... Actuator 11... Printing pin 14.15... Bimorph vibrator 22... Magnet holder 23.24... Magnet 25... Magnet holder 26.27... Magnet 31... Ink ribbon 32 ... Recording paper 34.35 ... Actuator 36.37 ... Printing pin.

Claims (3)

[Claims] (1) A wire dot printer print head in which a conductive actuator is placed in a magnetic field, a current is passed through the actuator, and the generated electromagnetic force causes a printing pin to protrude and dot a point. A printing pin is fixed to the tip side, and a cantilevered bimorph vibrator is joined to at least one end of the actuator, and when the printing pin retreats to a predetermined position after printing, a voltage is applied to the bimorph vibrator to warp it to one side. A print head for a wire dot printer, characterized in that the printing pin is braked by this. (2) Claim 1, characterized in that the bimorph vibrator is joined to both ends of an actuator, respectively.
The print head of the wire dot printer described in section. (3) The print head for a wire dot printer according to claim 1 or 2, wherein the actuator is a U-shaped aluminum plate.