JPH0421591B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a printing wire driving device in which a tip end of a vibrating arm faces a rear end of a printing wire with a predetermined distance therebetween.

(Prior art) In the prior art, a vibrating arm is constantly vibrated at a constant amplitude and period by a vibration driving means, and the tip of the vibrating arm is connected to the rear end of a printing wire by a predetermined distance.
An electromagnetic switching device provided at the base of the vibrating arm selectively displaces the tip of the vibrating arm to a position where it can collide with the rear end of the printing wire and a position where it cannot collide. There is a printing wire drive device designed to do this (for example, Japanese Patent Publication No. 58-45954). However, according to this prior art, an electromagnetic switching device is indispensable for selectively displacing the tip of the vibrating arm to a position where it can collide with the rear end of the printing wire and a position where it cannot collide. However, the disadvantage was that the configuration was complicated.

Therefore, in order to eliminate this drawback, the vibrating arm is vibrated continuously and at a constant frequency within a range that does not allow it to collide with the printing wire, and the amplitude is increased when it is desired to form a dot. It is conceivable to perform control.

(Problems to be Solved by the Invention) However, in this case, although it has the advantage of being able to be driven with a small current, it has the disadvantage that it takes time to rise.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a printing wire drive device that can quickly start up when forming dots and has a simple configuration.

(Means for Solving the Problems) The present invention is characterized by a vibrating arm, an electromagnetic drive means,
and a first and second switching circuit, and the tip of the vibrating arm faces the rear end of the printing wire and is supported in a cantilever manner so as to be able to vibrate in the sliding direction of the printing wire. The electromagnetic drive means includes a magnetic flux generating means including a permanent magnet, and a coil that generates a magnetic flux that acts magnetically with the magnetic flux of the magnetic flux generating means, and the magnetic flux generating means and the coil One of them is provided on the vibrating arm and the other is provided on the fixed member, and the first switching circuit receives a clock signal and intermittently applies a voltage to the coil. When forming a dot, the vibrating arm is vibrated within a range that does not collide with the rear end of the printing wire, and a second switching circuit receives a dot formation signal and superimposes a bias voltage to the coil on the voltage. When a dot is to be formed, the vibrating arm collides with the rear end of the printing wire.

(Example) An embodiment of the present invention will be described below.

As shown in FIG. 1, the diaphragm 1 is integrally formed with a plurality of (seven in this embodiment) vibrating arms 3 extending radially inward from an annular base 2 on the outer periphery. There is a base 2 between adjacent vibrating arms.
Auxiliary vibrating arms 4 extending radially inward from the housing are also integrally formed. The vibrating arm 3 is equipped with a mass 5 at its tip for adjusting its natural frequency, and the auxiliary vibrating arm 4 is also equipped with a mass 6 for balancing with the vibrating arm 3. The base 2 of the diaphragm 1 has a second
As shown in the figure, each vibrating arm 3 is supported by a support member 8 via a screw 7, and each vibrating arm 3 is supported in a cantilever manner, and the mass 5 at the tip thereof is connected to the rear end of the printing wire 9 (printing pin 10) in a predetermined manner. The printing wires face each other with an interval of , and can vibrate in the sliding direction of the printing wire. Each vibrating arm 3 is vibrated and driven via an electromagnetic drive device 11. The electromagnetic drive device 11 is composed of a magnetic flux generating means attached to a support plate 12 as a fixed member, and a moving coil 16 fixed to the middle part of the vibrating arm 3.
It is composed of a cylindrical outer yoke 13, a permanent magnet 14 fixed to the inner bottom of the outer yoke, and a disk-shaped inner yoke 15 fixed to the front surface of the permanent magnet. The outer yoke 13 and the inner yoke 15 are magnetized with different polarities by a permanent magnet 14, and the moving coil 16 is inserted into the magnetic space of both yokes, and magnetically interacts with the magnetic flux of this magnetic flux generating means. It generates magnetic flux that cooperates with the magnetic flux.

At normal times, that is, when no dots are formed, each vibrating arm 3 vibrates continuously and at a constant period with an amplitude within a range that does not allow its tip to collide with the printing pin 10, with the neutral position of vibration being at the position shown by the solid line in FIG. is driven by vibration. On the other hand, when it is desired to form a dot, the neutral position of the vibration moves forward to the position indicated by the chain line in FIG. This collision causes the printing wire 9 to advance and print.

FIG. 3 shows a drive circuit that drives and controls the vibrating arm 3 as described above, and each of the moving coils 16 is connected to the drive circuit shown in FIG. That is, one end of the moving coil 16 is connected to the power supply circuit, and the other end is connected to the transistor Tr1 constituting the first switching circuit.
It is connected to the emitter terminal of a transistor Tr2 constituting the second switching circuit, and resistors R1 and R2 are connected to the collector terminals of both transistors Tr1 and Tr2, respectively. At the base terminal A of the transistor Tr1,
A clock signal (print timing signal) as shown in FIG. 4A is supplied. The period of this clock signal is determined based on the natural frequency of the vibrating arm 3 of the diaphragm 1, and the print head is scanned in synchronization with this signal. During normal times, that is, when no dots are formed, a drive current is periodically applied to the moving coil 16 each time the transistor Tr1 is turned on by the clock signal.
In FIG. 2, the magnetic flux between the inner and outer yokes 13, 15 and the moving coil 16 cooperate to vibrate the vibrating arm 3. At this time, the tip of the vibrating arm 3 is vibrating around the neutral position indicated by the solid line in FIG. 2, and the opposing distance between the mass 5 and the rear end of the printing pin 10 is vibrated by the clock signal Since the amplitude is larger than that of the tip, it does not collide with the printing pin 10 and no dots are formed.

Next, at the base terminal B of the transistor Tr2,
As shown in FIG. 4B, a dot formation signal is supplied when it is desired to form a dot. By supplying this signal to the transistor Tr2, the neutral position of vibration of the vibrating arm 3 moves to the position shown by the chain line in FIG. 2, and the vibrating arm 3 vibrates around this advanced neutral position. In this state, the opposing distance between the mass 5' and the rear end of the printing pin 10 is smaller than the amplitude of the tip of the vibrating arm 3, so the tip of the vibrating arm 3 collides with the printing pin 10. , the printing wire 9 advances and a dot is formed.

To explain this point in detail, as shown in FIG. 4C, when a dot forming signal is supplied to the base terminal B of the transistor Tr2, the voltage V ₁ ( A voltage V ₀ biased by the transistor Tr2 is superimposed on FIG. 4A), and this superimposed voltage V ₂ is applied to the moving coil 16.

In this way, during head scanning, the transistor Tr
When a dot forming signal is supplied to the base terminal B of 2, the neutral position of the vibration of the vibrating arm 3 is advanced, and the tip of the vibrating arm 3 hits the printing wire 9, forming a 5 x 7 dot matrix pattern, for example. Characters can be formed arbitrarily at very high speeds.

(Effects of the Invention) As described above in detail, according to the present invention, when not forming dots, the vibrating arm is vibrated at an amplitude within a range that does not collide with the rear end of the printing wire,
When forming dots, the neutral position of the vibration is moved forward to strike the printing wire, so the vibrating arm rises quickly, and therefore the printing wire starts striking quickly, with low current consumption and extremely high speed. Printing operation becomes possible.

[Brief explanation of drawings]

Figure 1 is a front view of the print wire drive device of the print head, Figure 2 is a sectional view taken along the line shown in Figure 1, Figure 3 is a drive circuit diagram shown as an example, and Figures 4A, B, and C are current waveform diagrams. It is. 1... Vibration plate, 2... Base, 3... Vibrating arm, 9
... Printing wire, 10 ... Printing pin, 11 ... Electromagnetic drive device, 12 ... Fixing member (support plate), 1
3, 14, 15...Magnetic flux generating means (13...outer yoke, 14...permanent magnet, 15...inner yoke),
16... Coil, Tr1... First switching circuit (transistor), Tr2... Second switching circuit (transistor).

Claims (1)

[Scope of Claims] 1. A vibrating arm whose distal end faces the rear end of the printing wire and is supported in a cantilever manner so as to vibrate in the sliding direction of the printing wire, and a magnetic flux generating means including a permanent magnet. , comprising the magnetic flux of the magnetic flux generating means and a coil that generates a magnetic flux that acts magnetically, and one of the magnetic flux generating means and the coil is provided on the vibrating arm, and the other is provided on the fixed member. a first switching device that intermittently applies a voltage to the coil in response to a clock signal, and vibrates the vibrating arm within a range that does not collide with the rear end of the printing wire during non-dot formation; a second switching circuit that receives a dot formation signal and applies a bias voltage superimposed on the voltage to the coil, causing the vibrating arm to collide with the rear end of the printing wire when a dot is to be formed; A printing wire drive device comprising: