JPS62292444A - Wire dot recorder - Google Patents

Abstract

PURPOSE:To enhance a response of a recording head and a speed of recording action, by a construction wherein a coil attracting a rocking lever in a direction of an electromechanical conversion element and the aforesaid coil is connected to a part of a discharge path of a circuit driven due to the charge/discharge of the electromechanical conversion element. CONSTITUTION:In a construction, a rebound-preventing coil L1 is serially connected between a transistor Tr2 forming a charge-path of a piezoelectric element Pz1 and a transistor Tr3 forming a discharge-path of the piezoelectric element Pz1. To drive the rebound-preventing coil L1, a terminal A is again brought into a high-level condition; this operation results in the conduction to a transistor Tr1 and the transistor Tr3, thus electric charges stored in the piezoelectric element Pz1 are discharged to an earthing electric potential through the coil L1 and the transistor Tr3. Additionally, by being driven immediately after the tip end of a wire 12 reaches a recording medium, the coil L1 attracts an armature 14 so that the return speed of a lever 10 and the wire 12 can be doubled. In this manner, a speed of recording action can be more enhanced.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a recording device, particularly an impact type recording device, which uses an electromechanical transducer such as a piezoelectric element or an electrostrictive element. This invention relates to a wire dot recording device.

[Prior Art] Various impact printers such as wire dot matrix printers and type impact printers have been known.

In particular, in wire dot matrix type printers, in addition to drive methods using springs and solenoids, drive methods using piezoelectric elements or electrostrictive elements are known. More specifically, piezoelectric or electrostrictive elements can be classified into transverse effect type and longitudinal effect type depending on the operating principle.

[Problems to be Solved by the Invention] The structure of a recording head using the former transverse effect type piezoelectric element is shown in FIG. 2. (mentioned) 1 is constructed by laminating piezoelectric elements la and lb made of a material such as ceramic. The piezoelectric element 1 has a substantially triangular shape, and a dot matrix recording wire 2 is fixed to the apex of the piezoelectric element 1. Also, the bottom part of the element is fixed to the head.
In the above configuration, when an electric field is first applied in the direction in which one piezoelectric element la extends, the other piezoelectric element 1b contracts, and the entire element 1 is displaced in the direction a in the figure. Subsequently, when an electric field is applied in the opposite direction to the above, the piezoelectric element 1a, which had been extended earlier, contracts, and the piezoelectric element 1b, which had been contracted, expands.Therefore, the entire element 1 is displaced in the b direction, and the wire 2 The recording operation is completed by rapidly advancing toward the illustrated recording medium and bringing the tip of the wire 2 into contact with the recording medium through a printing material such as an ink ribbon.

On the other hand, the configuration of a recording head using a longitudinal effect type piezoelectric element is shown in Fig. 3. In Fig. 3, the element indicated by the reference numeral 3 is a longitudinal effect type piezoelectric element, which expands in the C direction when a driving voltage is applied. do. The elongation of the piezoelectric element 3 is converted into a rotational moment about the support 4a of the casing, causing the casing 4 to be displaced in the d direction at the support plate 5.

A lever 7 having a substantially L-shape is fixed on the support plate 5, and the housing 4 and the lever 7 are connected to the L-shape of the lever 7.
They are connected by a support plate 6 at the inner part of the shape. Therefore, the displacement of the support plate 5 generates a rotational moment of the lever 7 about the support plate 6, and as a result, the wire 8 attached to the tip of the lever 7 is displaced in the direction C to perform a recording operation.

A recording head using a transverse effect type piezoelectric element as shown in FIG. 2 has a simple structure and requires low driving power, but has the drawbacks of slow response speed5 and low energy during recording.

In addition, a configuration using a longitudinal effect type piezoelectric element as shown in Fig. 3 has excellent energy efficiency and response speed, but since the amount of displacement of the piezoelectric element is minute (about several pm), A mechanism for enlarging the amount of displacement is required, the structure of the head becomes complicated, a high degree of component precision and machining precision is required, and there are problems in that adjustment is difficult. In addition, with m* as shown in FIG. 3, stress tends to concentrate at the fulcrum of the rotational moment, which poses a problem in terms of durability.

FIG. 4 shows a simpler conventional structure of a recording head using longitudinal effect type piezoelectric elements. In Figure 3,
A lever 10 supporting a recording wire 12 is rotatably supported by the housing 9 via a shaft 11. The L-shaped housing 9 and the lever 10 are connected by a spring 13, so that the lever 10 and the wire 12 are always urged downward in the figure by the spring 13.

Further, a longitudinal effect type piezoelectric element 3 is provided between the lever lO and the bottom part of the casing 9, and the lever 10 is brought into contact with the piezoelectric element 3 by a protruding piece 10a formed approximately at the center thereof. ing.

When the piezoelectric element 3 is driven in such a configuration, the piezoelectric element 3 expands in the f direction. The amount of displacement of the piezoelectric element 3 at this time is about several JLm at most, but the driving force is 1
The impact force generated by this is quite large. This impact force causes the lever lO
receives a driving force from the protruding piece 10a, the entire lever 10 rotates around the shaft 11, and as a result, the wire 12
move rapidly forward in a direction. Here, the protruding piece 10a of the lever lO
It is the distance from the part where the wire is fixed to the lever 10 to the shaft 11.
Then, the lever ratio γ is 2/411, and the wire is 12
When viewed from the side, the impact force is 1/γ of the piezoelectric element, but the amount of displacement is γ times that of the piezoelectric element.

When the driving of the piezoelectric element 3 is completed, the wire 12 and the lever are returned to their initial positions by the biasing force of the spring 13.

FIG. 5 shows the displacement g of the lever 10 in relation to the time t. In FIG. 5, when the piezoelectric element 3 is driven at time 1=0, the wire 12 advances due to the above operation, and the tip of the wire 12 collides with the recording medium at time 1=0.

Thereafter, the wire 12 tries to return to the initial position due to the repulsive force of the recording medium and the urging force of the spring 13, but at time t
1, after the wire 12 returns to the initial position, the wire 1
2 causes a rebound on the piezoelectric element 3, which is caused by the lever 1
This is because the protruding piece 10a of 0 collides with the piezoelectric element 3 rapidly.

Therefore, for example, at time t2, the protruding piece 10a of the lever 10 is separated from the piezoelectric element 3, and even if the piezoelectric element is driven at this position, recording operation under the predetermined conditions cannot be guaranteed, and therefore the rebound as shown in FIG. In view of the problem of 0 or more, in which the next recording drive cannot be performed until the problem subsides, and high-speed operation is impossible, a configuration as shown in FIG. 6 has been devised.

In the configuration shown in FIG. 6 as well, the wire 12 is fixed to the lever 10, and the lever 10 is in contact with the piezoelectric element 3 by the protrusion 10a at the center thereof.

Further, the lever lO is biased by a spring 13. The base of the lever 10 is composed of an armature 14 made of a ferromagnetic material, etc.
By rotatably supporting the lever IO on the shaft 11, the entire lever IO is supported by the housing.

The shaft 11 is fixed to a yoke 16 formed from a soft magnetic material and formed at the upper end of the L-shape of the housing 9. As shown in the figure, the yoke 16 has two arm-shaped parts 16a at its upper end. , 16a are formed to sandwich the armature 14, and the portion of the yoke 16 fixed to the housing 9 has a projecting portion 16b extending in the direction of the piezoelectric element 3 by approximately the same length as the arms 16a, 16a. A coil 15 is formed on the projecting portion 16b of the yoke 16.
is wrapped. When this coil 15 is driven, the armature 14 is attracted by the attraction force generated by the coil 15 and the yoke 16, and as a result, the lever 10 swings downward in the figure. This coil 15 is for preventing the rebound of the lever lO shown in connection with FIG.

FIG. 7 shows a circuit configuration for driving the recording head shown in FIG. 6.

In FIG. 7, a transistor Tri is a control transistor that drives a piezoelectric element P according to a drive signal input from a terminal A.
The switching transistor Tr2.zl (3 above) drives the switching transistor Tr2. Controls on/off of Tr3. PNP and NPN transistors Tr2 and T connected in series
A rated voltage VPP for driving the piezoelectric element is applied to the transistor Tr3, and the collector of the transistor Trl and the transistor Tr2. This same voltage is input to the base of Tr3 via current limiting resistor R1. Piezoelectric element Pzl is connected between the connection point between the emitters of transistors Tr2 and Tr3 and the ground potential.

On the other hand, the coil Ll (15) on the right side of FIG. 7 is driven by the transistor Tr4. The corephthalmic emitter of the transistor Tr4 and the coil LL are connected in series, and a rated voltage VCP for driving the coil is applied to this series connection. A drive control signal for the coil Ll is input from the terminal B to the base of the transistor Tr4. A circuit composed of a diode D1 and a Zener diode D2 connected to the coil L1 absorbs the back electromotive force generated from the coil L1 when the coil L1 is turned off, and the transistor T
This is to protect r4.

To perform a recording operation in the above configuration, first, the terminal A is set to high level, the transistor Trl is turned on, the power supply voltage input through the bias resistor R1 is absorbed by the transistor Tri, and the base current of the transistor Tr2 is cut off. do. This turns the transistor Tr2 off. Further, when charge is stored in the piezoelectric element P21, the transistor Tr3 is turned on, and the piezoelectric element Pzl
The charge stored in is released.

Subsequently, in order to perform wire dot recording by deforming the piezoelectric element, the transistor Tri is turned off from the above state. As a result, the radio wave from the drive power source that passes through the bias resistor R1 flows to the base of the transistor Tr2, and as a result, the transistor Tr2 is turned on. At this time, the transistor Tr3 of opposite polarity is turned off, so a voltage is applied to the piezoelectric element Pzl, and the piezoelectric element 3 becomes
As a result, the lever 10 and the wire 12 suddenly move forward in the g direction, as described in the conventional example section, and the tip of the wire 12 comes into contact with the recording medium.

After that, when the wire 12 returns to the initial position due to the repulsive force of the recording medium and the biasing force of the spring 13, the protruding piece 10a collides with the piezoelectric element 3. At this time, by setting the terminal B to a high level and turning on the transistor Tr4, a current is applied to the coil L1.As a result, the yoke 16 attracts the armature 14 downward in FIG. to prevent rebound.

In the above configuration, the drive circuit consists of two independent circuits (with different power supplies), one for the piezoelectric element and one for the rebound prevention coil, which makes circuit routing and control complicated. There's a problem. The complexity of such a drive circuit becomes a major obstacle when constructing a recording head with a large number of pins (dots), such as in a Kanji printer, for example.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, the swinging position of the swinging lever to which the recording wire is fixed is adjusted to
In a wire dot recording device that performs wire dot recording by controlling a wire dot to collide with a wire recording Q medium using a mechanical transducer, a coil is provided that attracts the swinging lever in the direction of the electrical/mechanical transducer, and the electrical/mechanical A configuration is adopted in which the coil is connected to a part of the discharge path of a circuit that is driven by charging and discharging the conversion element.

[Function] According to the above configuration, electricity in the drive circuit /4I! A coil connected to the discharge path of the mechanical transducer is driven when the electrical/mechanical transducer is discharged, and attracts the swinging lever toward the electrical/mechanical transducer to prevent the lever from rebounding.

[Example] Hereinafter, details of embodiments of the present invention will be described.

FIG. 1 shows the configuration of a drive circuit for a wire dot recording head according to the present invention. The circuit shown in FIG. 1 is for driving the wire dot recording head shown in FIG. 6, and in this embodiment, the drive circuit for the piezoelectric element P21 and the rebound prevention coil L1 are integrated. The configuration of FIG. 1 is similar to the circuit on the left side of FIG. 7, and the piezoelectric element Pzl
The transistor Tr2 and the piezoelectric element Pz form a charging path of
The coil LL for preventing rebound is connected in series between transistors Tr3 forming one discharge path. The piezoelectric element Pzl is connected between the connection point between the transistor Tr2 and the coil L1 and the ground potential. The circuit for driving the transistors Tr2 and Tr3 is composed of a current limiting resistor R1 and a transistor Tri as in the case of FIG.

In order to perform wire pit recording in the above configuration, as in the conventional configuration described above, terminal A is set to high level, transistor Tri is made conductive, and the power supply voltage input via resistor R1 is passed to the transistor Tri side. , cuts off the base current of transistor Tr2. by this,
Transistor Tr2 is turned off. At this time, if charge is stored in the voltage element Pzl, the transistor Tr
By turning on transistor Tr3, the charge stored in the voltage element is discharged via transistor Tr3.

Next, from the above state, a low level potential is input to the terminal A to turn the transistor Tri off. As a result, the current from the drive power supply that passes through the bias resistor R1 flows to the base of the transistor Tr2, turning on the transistor Tr2 and turning off the transistor Tr3 of the opposite polarity.

As a result, a voltage is applied to the piezoelectric element Pzl, and the piezoelectric element 3 extends in the direction f in FIG.
The leading end of the dot moves forward and contacts the recording medium to perform dot recording.

Subsequently, in this embodiment, the terminal A is brought to a high level again in order to drive the rebound prevention coil Ll. As a result, the transistors Tri and Tr3 become conductive, and the charge stored in the piezoelectric element Pzl is discharged to the ground potential via the coil L1 and the transistor Tr3. At this time, since current flows through the coil LL, the yoke 16 attracts the armature 14, and the lever 10 is prevented from rebounding on the piezoelectric element 3.

As described above, the same recording operation and rebound prevention effect as shown in connection with FIG. 6 can be obtained.
Since the circuit configuration is much simpler than that shown in FIG. 7 and the number of parts is reduced, the device configuration can be made simpler and cheaper. Furthermore, as is clear from a comparison with FIG. 7, the number of input signal lines required for a drive circuit for one dot is halved. Therefore, the wiring around the recording head can be further simplified, and the number of parts and manufacturing costs can be significantly reduced in this respect as well. Such a configuration is particularly effective for recording heads having 24 pins or more drive wires, such as those for Kanji printers.

In the configuration shown in FIG. 1, the coil drive voltage is the piezoelectric element drive voltage VPP at the initial stage of coil drive;
It decreases as the piezoelectric element discharges. On the other hand, in the configuration shown in FIG. 1, the coil drive voltage is a constant voltage VCP, so in order to obtain the same rebound prevention characteristics as in FIG. 7, it is preferable to adjust the diameter or number of turns of the winding of the coil L1.

In addition, in the configuration shown in Fig. 1, the coil L is included in the drive circuit of the piezoelectric element.
1 is inserted, there is a delay in the rise of the piezoelectric element drive current due to the time constant of the bias resistor R1 and the coil L1, but by anticipating this delay and giving the coil drive signal early, it is possible to Equal or better responsiveness can be ensured.

Furthermore, in the above embodiment, the coil Ll (15) was driven only to prevent rebound of the lever 10;
The armature L is driven by driving the coil L1 immediately after the tip of the wire 12 reaches the recording medium.
4 can also be aspirated to double the return speed of the lever 10 and wire 12. This makes it possible to further speed up the recording operation.

Of course, the piezoelectric element 3 (Pzl) may be replaced with another mechanical/electric conversion element driven by charging and discharging.

[Effect] As is clear from the above description, according to the present invention, the swinging position of the swinging lever to which the recording wire is fixed is controlled using an electric/mechanical conversion element to cause the wire to collide with the recording medium. ,
A wire dot recording device that performs wire dot recording is provided with a coil that attracts the swinging lever in all directions of the electric/mm conversion element, and is part of a discharge path of a circuit that drives the electric/mechanical conversion element by charging and discharging it. Since the coil is connected to the coil, the recording head drive circuit is simplified, the structure around the recording head is greatly simplified, and a recording head with a large number of pins can be easily configured. This has the excellent effect of improving performance and speeding up recording operations.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a drive circuit for a wire dot recording head according to the present invention, and FIG. 2 and subsequent figures explain the conventional structure. An explanatory diagram of the basic structure. Figure 3 is a perspective view of the main parts of a wire dot recording head using longitudinal effect type piezoelectric elements. Figure 4 is a perspective view showing different configurations of the wire dot recording head using longitudinal effect type piezoelectric elements. 5 is a line diagram explaining the drawbacks of the configuration of FIG. 4, FIG. 6 is a perspective view showing a recording head structure that is an improvement over the configuration of FIG. 4, and FIG. 7 is a diagram of the recording head of FIG. 6. FIG. 2 is a circuit diagram showing the configuration of a drive circuit of FIG. 3, Pzl...Piezoelectric element lO...Lever 12...
・Wire 13...Spring 15, Ll
...Coil Tri-Tr3...Transistor R1...Resistance

Claims (1)

[Claims] Electrically adjust the swing position of the swing lever to which the recording wire is fixed.
In a wire dot recording device that performs wire dot recording by colliding a wire with a recording medium under control using a mechanical transducer, a coil is provided that attracts the swing lever in the direction of the electrical/mechanical transducer; / A wire dot recording device characterized in that the coil is connected to a part of a discharge path of a circuit that is driven by charging and discharging a mechanical transducer element.