JPH02141255A - Moving coil type hammer - Google Patents

Abstract

PURPOSE:To increase working speed while keeping optimal printing energy by fixing a soft magnetic substance at the specified position of a member, one end of which is fastened to a base and to the other end of which a wire is fitted, in a magnetic field formed by a permanent magnet. CONSTITUTION:In a moving coil type hammer having a leaf spring 6, one end section of which is fixed to a base, a member 5, one end section of which is fastened to the other end section of the leaf spring 6 and to the other end section of which a printing wire 11 is fitted, a flat coil 7 fixed to the member 5, and permanent magnets 8, 9 generating magnetic flux crossing the flat coil 7, a soft magnetic substance 13 is fastened at the specified position of the member 5 existing in a magnetic field formed by the permanent magnets 8, 9. Consequently, when the member 5 constituting one part of the hammer moved at high speed intended to be spring out to the outside of the magnetic field, pulling- back force into the magnetic field works on the soft magnetic substance 13, the hammer shifted at high speed is decelerated, and kinetic energy is lowered. Accordingly, even when the hammer is driven at high speed, the hammer is deceleratted in the moment of printing, thus increasing the working speed of the moving coil type hammer while keeping optimal printing energy.

Description

[Detailed Description of the Invention] Overview Regarding the moving coil type hammer that constitutes the print head of a wire dot printer, the purpose of the present invention is to provide a moving coil type hammer that can achieve high speed while maintaining optimum printing energy. a member having one end fixed to the other end of the temporary spring and having a printing wire at the other end, a flat coil fixed to the member, and a member that crosses the flat coil. A moving coil type hammer equipped with a permanent magnet that generates magnetic flux is constructed by fixing a soft magnetic material to a predetermined position of the member that is present in the magnetic field formed by the permanent magnet.

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to a moving coil type hammer constituting a print head of a wire dot printer.

A wire dot printer uses a printing hammer having a plurality of thin wires to strike a platen through printing paper and an ink ribbon, thereby forming characters and graphics using schools of fish on the printing paper. Simultaneous copying is possible, and running costs are low because it does not require any type of printing paper, so it is widely used as an output device for office automation equipment and personal computers.

It is well known that the printing hammer used in this wire dot printer is driven by an electromagnetic force generated by energizing a coil in a magnetic field and an elastic force of a spring or the like. This hammer is called a moving coil type hammer because the coil moves together with the hammer in a magnetic field, and even when using various types of printing paper, the wire tip will not get caught and be damaged, making it highly reliable. There is a demand for a high printing hammer.

2. Description of the Related Art A conventional movable coil type hammer is constructed as shown in FIGS. 7 and 8, for example. Figure 7 shows ■-■ of Figure 8.
8 is a line sectional view, and FIG. 8 is a rear view of a conventional moving coil type hammer.

A coil base 10 has a printing wire 12, a recovery leaf spring 14, and an L-shaped portion 16, and is fixed to the coil base 10, and together with a flat coil 18 having a lead wire 20, constitutes a driver. 22 is a base having a botting hole 24, and this base 22 holds a permanent magnet 26 while maintaining a constant gap with respect to the flat coil 18;
It constitutes a magnetic circuit.

The recovery spring 14 is a plate spring formed integrally with the coil base 10, one end of which is inserted into a botting hole 24 of the base 22, and fixed by injecting a casting resin 28. Furthermore, two coil bases 10 are provided between the permanent magnets 26 for high-density mounting.

A wire guide 30 is fixed to the base 22 and guides the printing wire 12. The base 22 also has a backstop 32 on the side opposite to the wire guide 30.
It is provided so as to be in contact with the L-shaped portion 16 on the 0, and limits one side of the stroke of the printing wire 12, and also slightly elastically deforms the recovery plate spring 14 to apply initial pressure.

34 is an ink ribbon, 36 is a printing paper, and 38 is a platen.

However, when a pulsed drive current is applied to the flat coil 18 from a control circuit (not shown) via the lead wire 20, the coil base 10 rotates around the recovery leaf spring I4 due to electromagnetic force, and the printing wire 12 moves as a wire guide. Stick out along 30. The printing wire 12 hits the platen 38 via the ink ribbon 34 and the printing paper 36 to perform printing. Thereafter, the printing wire I2 is quickly returned by the reaction force at the time of impact and the restoring force of the restoring leaf spring 14, and the coil base 10
The upper L-shaped portion 16 collides with the backstop 32 and stops, preparing for the next drive. Note that since initial pressure is applied to the recovery leaf spring 14, the L-shaped portion 1 on the coil base 10
6 collides with the backstop 32, the printing wire 12 is prevented from jumping out again due to the reaction (rebound).

Printing is performed as described above, but an important factor when printing is the issue of printing energy.

Generally, the kinetic energy that a driving hammer has at the moment of impact is directly converted into printing energy, but the optimum printing energy is predetermined based on the printing wire diameter, printing force, etc. Therefore, the hammer needs to have kinetic energy to provide optimal printing energy, and therefore the weight of the movable part and the speed at impact are precisely designed.

Problems to be Solved by the Invention Currently, printing speeds are being increased in all types of printers, not just moving coil type hammers. As for wire dot impact printers, serial printers with a printing speed of 110 to 120 characters per second and line printers with a printing speed of 300 lines per minute are being commercialized one after another, and efforts are being made to further increase the speed. The same goes for wire dot printers that use moving coil type hammers, and efforts have been made to shorten the printing cycle.

The kinetic energy E at the moment the hammer strikes is Em-v”
It is expressed as /2 (m: weight of the hammer, V: speed of the hammer at the time of impact).

In order to increase the speed, it is necessary to increase the speed V, but the value of E needs to be kept constant in relation to the optimum printing energy, and if the speed V is increased, the weight of the moving part m also needs to be reduced considerably. It's coming. However, the weight of the flat coil and coil base that make up the movable part is so advanced that it cannot be easily reduced in weight, and the weight of the movable part is constant, the printing cycle is accelerated, and the motion equivalent to the optimum printing energy is required. Conserving energy has become an extremely difficult problem.

The present invention has been made in view of these points, and an object of the present invention is to provide a moving coil type hammer that can achieve high speed while maintaining optimum printing energy.

Means for Solving the Problems FIG. 1 is a diagram showing the principle of the present invention. Figure 1 shows the force acting on a piece of soft magnetic material in a magnetic field. Figure 1 (A) shows a state in which the piece of soft magnetic material is completely in a magnetic field, and Figure 1 (B) shows a state in which the piece of soft magnetic material is completely in a magnetic field.
, respectively, indicate a state in which a piece of soft magnetic material is about to jump out of the magnetic field. In the figure, 1.2 is a permanent magnet, 3 is a yoke, and 4 is a piece of soft magnetic material such as an iron piece. When the soft magnetic piece 4 is completely in the magnetic field as shown in FIG. 1(A),
Although the soft magnetic material piece 4 is not subjected to lateral force, as shown in FIG. 1(B)
As shown in the figure, when the soft magnetic material piece 4 tries to come out of the magnetic field,
A force that tries to pull it back into the magnetic field acts on the soft magnetic piece 4,
The soft magnetic piece 4 is returned into the magnetic field.

The present invention applies this principle to a moving coil hammer, a schematic diagram of which is shown in FIG. The present invention
A leaf spring 6 whose one end is fixed to the base, and this leaf spring 6
One end is fixed to the other end, and the printing wire 1 is attached to the other end.
1, a flat coil 7 fixed to the member 5, and a permanent magnet 8 that generates a magnetic flux across the flat coil 7.
．． 9, in which the member 5 is present in a magnetic field formed by a permanent magnet 8.9.
A soft magnetic material 13 is fixed at a predetermined position.

Since the soft magnetic material 13 is fixed to a part of the member 5 that is within the magnetic field formed by the working permanent magnet 8.9, the member 5 that forms part of the hammer that is moving at high speed is exposed to the magnetic field. When it tries to fly out, a force that tries to pull it back into the magnetic field acts on the soft magnetic body 13, and the hammer, which is moving at high speed, decelerates.
Kinetic energy decreases. Therefore, even if the hammer is driven at high speed, the hammer is decelerated at the moment of printing, so it is possible to increase the speed of the moving coil type hammer while maintaining optimal printing energy.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 3 to 6. 7 and 8 for explaining this example.
Components that are the same as those of the conventional device shown in the figures are designated by the same reference numerals, and a portion of their explanation will be omitted.

First, referring to FIGS. 3 and 4, FIG. 3 is a sectional view taken along the line III--III in FIG. 4, and FIG. 4 is a rear view of the embodiment. Two permanent magnets for high density mounting 26.26
Two drive elements 15, which each operate independently, are arranged in the gap defined by. The driver 15 is composed of a coil base 10, a printing wire 12 fixed thereto, a flat coil 18, and a lead wire 20. Inserted into the hole 24, the casting resin 2
It is fixed by 8. Iron pieces 40 are installed on both sides of the coil base 10 in accordance with the printing stroke and the width of the permanent magnet 26.
is fixed.

When a pulsed drive current is passed through the flattened coil 18 from the lead wire 20, an electromagnetic force is generated, and the driver 15 rotates against the spring force using the recovery plate spring 14 as a fulcrum. At this time, the electromagnetic force acting on the drive element 15 is increased to increase the speed of the hammer. Possible methods for increasing this electromagnetic force include increasing the effective length of the flat coil 18 in the magnetic field, increasing the magnetic flux density of the gap defined by the adjacent permanent magnets 26, and increasing the drive current. Since it is important not to increase the weight, it is effective to design the gap magnetic flux density to increase or control the drive current to increase.

When the hammer is driven at high speed by the above-described operation, the hammer moving at high speed moves with a kinetic energy considerably larger than the optimum kinetic energy (see FIG. 6), but the printing wire 12 is moved through the ink ribbon 34 and the printing paper 36. Just before striking the platen 38, the coil base 1 of the hammer
0 reaches the end of the permanent magnet 26,
Deceleration is performed by magnetic attraction (see Figure 5). Therefore, at the time of impact, the kinetic energy decreases and changes to a value corresponding to the optimum printing energy (see FIG. 6), making it possible to achieve high quality printing.

As described above, according to this embodiment, even if the hammer is moving with kinetic energy larger than a predetermined value in order to increase speed, it decelerates just before striking, so it is possible to strike the platen with optimal kinetic energy. This allows for high-quality printing without paper loss.

In the above-mentioned embodiment, an example in which the iron pieces 40 are fixed to both sides of the coil base lO is explained, but the iron pieces 40
may be fixed only to one side of the coil base 10.

Effects of the Invention Since the present invention is configured as detailed above, in order to increase the speed of the moving coil type hammer that constitutes the print head of a wire dot printer, the moving speed of the hammer is increased, and therefore the kinetic energy of the hammer is increased. Even if the r gear temporarily exceeds the optimum value, the moving speed of the hammer is slowed down by the magnetic attraction force acting between the magnetic field and the soft magnetic piece attached to the coil base of the hammer just before striking. , corrected to the optimal kinetic energy when hitting,
The effect is that printing can be performed with good printing quality and without damaging the printing paper. Further, according to the present invention, printing speed can be increased without changing the movable weight of the current moving coil type hammer.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the principle of the present invention, Fig. 2 is a schematic diagram of the application of the principle of the present invention to a moving coil type hammer, Fig. 3 is a sectional view taken along line mm in Fig. 4, and Fig. 4 is a diagram of the present invention. FIG. 5 is an explanatory diagram of the operation of the embodiment. FIG. 6 is a graph showing temporal changes in kinetic energy according to the embodiment of the present invention. FIG. 7 is a cross section taken along the line ■-■ in FIG. 8. FIG. 8 is a rear view of a conventional example. 0... Coil base, 4... Recovery plate spring, 2... Base, 4... Ink ribbon, 8... Platen, 2... Printing wire, 8... Flat coil, 6... ...Permanent magnet, 6...Printing paper, 0...Iron piece. Pot 1 master talent/＼゛ki (Jl child Koishi Motokuma haman (7 character wire guarashi body)

Claims (1)

[Claims] A plate spring (6) having one end fixed to a base, and a printing wire (11) having one end fixed to the other end of the plate spring (6). A movable coil hammer comprising a member (5), a flat coil (7) fixed to the member (5), and permanent magnets (8, 9) that generate magnetic flux across the flat coil (7). A moving coil type hammer, characterized in that a soft magnetic material (13) is fixed to a predetermined position of the member (5) that exists in the magnetic field formed by the permanent magnets (8, 9).