JPH02103155A - Wire dot printing head - Google Patents

Abstract

PURPOSE:To obtain a wire dot printing head prevented from an increase of a driving current by arranging a permanent magnet at the center to form a magnetic circuit from the permanent magnet, a magnet yoke, an armature, a core and a core yoke. CONSTITUTION:A core plate 22 and a magnet yoke 23 are connected to the permanent magnet 21 arranged to the central part of a head. The core plate 22 is provided vertically and a demagnetizing coil 25 is wound around a core 24. The magnetic flux generated from the permanet magnet 21 arranged to the central part of the head passes through the magnet yoke 23 and the first acting gap with a biasing leaf spring 27 to enter an armature 29 and passes through the second acting gap 32 and the core 24 in the same way to return to the permanent magnet. Since there is no first yoke, the magnetic resistance between adjacent magnets 33, 34 becomes high. As a result, the quantity of the demagnetizing flux 35 generated in the demagnetizing coil 25 of the magnet 33 to flow in the adjacent magnet 34 is reuded to a large extent. Therefore, the magnetic interference between the adjacent magnets is reduced to a large extent and a wire dot printing head prevented from an increase of a driving current is obtained.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a wire dot print head in a serial printer, in particular, an armature having a print wire at the tip is attracted to a core by a permanent magnet, and the permanent magnet generates The present invention relates to the structure of a wire dot print head that generates a magnetic flux in the opposite direction to the magnetic flux generated by a coil to open the armature, and prints by driving the print wire at that time.

(Prior Art) In recent years, impact printers, especially wire dot printers, which are capable of high-speed copying on various print media and are inexpensive, have been widely used as man-machine interfaces, including peripheral terminal devices of information processing systems, office computers, and personal computers. It has come to be widely used in, etc.

In particular, in recent years there has been a demand for even faster printing, more print heads with more bins, higher printing power, etc., and spring-charged printers with excellent initial acceleration have become the mainstream of wire dot printers (especially (Refer to Publication No. 58-56354).

A sectional view of the main parts of the above conventional wire dot print head is shown in Fig. 6.
As shown in the figure.

In the figure, l is an armature, 2 is a first yoke, 3 is a magnetic spacer, 4 is a second yoke, 5 is a permanent magnet that generates magnetic flux to attract the armature l to the core 6, and 7
is the degaussing coil wound around the core 6, and 8 is the armature l.
9 is an armature supporter, and IO is a printing wire fixed to the first tip of the armature.

Here, the operation of the wire dot print head will be briefly explained.

First, when the degaussing coil 7 is not excited, the permanent magnet 5
The magnetic flux of the second yoke 4, the magnetic spacer 3, the first yoke 2
A magnetic circuit is formed through the armature 1 and the core 6, and the armature 1 is attracted to the end surface of the core 6 while biasing the bias leaf spring 8 due to the magnetic attraction force generated at this time.

In this state, when the degaussing coil 7 is then excited, the degaussing coil 7 generates a magnetic flux in the opposite direction to the magnetic flux of the magnetic circuit, thereby canceling the magnetic flux of the permanent magnet 5, which was in a biased state. The bias leaf spring 8 is released from the core 6. At this time, the energy stored in the bias leaf spring drives the wire 10 fixed to the tip of the armature I in the direction of the arrow shown in the figure, striking the print medium through the ink ribbon (not shown), and printing is done on it. It will be done.

Subsequently, the armature 1 starts to return due to the force generated during printing and collides with the end face of the core 6.

At this time, the armature I is again attracted to the end surface of the core 6 by the magnetic attraction force of the permanent magnet 5, completing one printing operation.

(Problems to be Solved by the Invention) By the way, during the printing operation of the conventional spring-charged wire dot print head, a large number of pins are operated simultaneously.

FIG. 7 is an explanatory diagram of a magnetic circuit in a conventional wire dot printing lead.

Here, the first yoke 2 and the core 6 on the armature l are integrally formed, and the armature 1, the core 6,
and a set of magnets 11 consisting of the first yoke 2,
As shown in the figure, a magnetic circuit is formed between the adjacent magnets 12. In other words, the demagnetizing magnetic flux 13 generated by the demagnetizing coil 7 of the magnet 11 flows into the adjacent magnet 12 and demagnetizes the magnet 12. magnetic flux 14
Since the magnetic flux is in the opposite direction, the magnetic flux 1 due to the permanent magnet 5
The apparent demagnetizing flux 14 for canceling out the magnetic flux 5 is reduced.

In other words, the inductance of the degaussing coil 7 decreases, and the drive current increases.ii The drive current is
This increases as the number of print wires that operate simultaneously increases, and as a result, the power consumption of the wire dot print head increases and the amount of heat generated by the print head increases. Then, when the temperature of the print head rises and exceeds a permissible limit, printing is stopped and the number of prints per unit time is reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a spring-charged wire dot print head in which the drive current does not increase due to magnetic interference between adjacent magnets.

(Means for Solving the Problems) For this purpose, the present invention provides an armature having a printing wire fixed to its tip, a core provided opposite to the armature, and the armature being joined and supported in a cantilevered manner. a bias plate spring; a permanent magnet that generates magnetic flux and attracts the armature against the elastic force of the bias plate spring; In a wire dot print head consisting of a coil that cancels the magnetic flux of the permanent magnet and opens the armature, the permanent magnet is arranged at the center of the wire dot print head. Then, a magnetic yoke that attracts the armature is arranged above the permanent magnet, and a core yoke is arranged below, and a magnetic circuit is formed by the permanent magnet, the magnet yoke, the armature, the core, and the core yoke, so that the flow flows into the adjacent magnet. It is intended to reduce magnetic flux.

(Function) According to the present invention, as described above, a permanent magnet is arranged at the center of the wire dot print head, and a magnet yoke that attracts the armature is arranged above the permanent magnet, and a core four is arranged below. By forming a magnetic circuit with a permanent magnet, a magnet yoke, an armature, a core, and a core yoke, magnetic flux flowing into adjacent magnets is reduced, so magnetic interference between the magnets is reduced.

(Embodiment) FIG. 1 is a sectional view of a main part of a wire dot print head showing an embodiment of the present invention, and FIG. 2 is a perspective view of a main part of a wire dot print head of the present invention.

In the figure, a permanent magnet 21 is placed in the center of the head,
A core plate 22 and a magnet yoke 23 are bonded to the permanent magnet 21 by adhesive or the like. Further, a core 24 is provided upright on the core plate 22, and a demagnetizing coil 25 is wound around the core 24.

On the other hand, a bias plate spring support 26, a bias plate spring 27, and a bias plate spring holding yoke 28 are attached to the outer periphery of the core plate 22 by adhesive or screw tightening. An armature 29 is joined to the tip of the bias plate spring 27 by laser welding or the like, so that it can swing.

Here, the seating surface of the bias plate spring support 26 and the suction surface of the core 24 have a certain level difference, and the surface of the magnet yoke 23 is finished to the same height as the suction surface of the core 24.

In the above wire dot print head, the magnetic flux 30 generated by the permanent magnet 21 located in the center passes through the magnet yoke 23 and the first working gap 31 between this and the bias leaf spring 27 joined to the armature 29. through which it enters the armature 29 and likewise into the second working cavity 32.
It passes through the core 24 and returns to the permanent magnet 21.

At this time, two of the first working gap 31 and the second working gap 32
Since the branching force is generated at the point ai, the suction force can be increased compared to the prior art shown in FIG. 6, which generates the suction force in one working gap.

At this time, since the bias leaf spring support base 26 and the bias leaf spring holding yoke 28 do not constitute a magnetic circuit, they can be constructed from a non-magnetic material.

FIG. 3 is an explanatory diagram of the magnetic circuit in the wire dot print head of the present invention.

In the wire dot printhead of the present invention, the absence of the first yoke increases the magnetic reluctance between adjacent magnets 33,34. Therefore, for example, the amount of demagnetizing magnetic flux 35 generated in the demagnetizing coil 25 of the magnet 33 and flowing into the adjacent magnet 34 is significantly reduced, so that the demagnetizing magnetic flux generated by the magnet 34 to cancel the magnetic flux 36 of the permanent magnet 21 is reduced. 37 no longer decreases, and the inductance increases. As a result, compared to conventional wire dot print heads, the current required when the print heads are operated simultaneously is significantly reduced, making it possible to significantly reduce power consumption. FIG. 4 shows a comparison diagram of the drive currents of the prior art and the present invention.

In the figure, when the drive voltage and drive time of the print head are constant, the horizontal axis represents the number of print wires that operate simultaneously, and the vertical axis represents the peak value l of the drive current at that time.

In the case of a conventional wire dot print head, as the number of print wires operating simultaneously increases, the peak value 19 of the drive current increases. The peak current mLl when they operate simultaneously! will increase by 1.8 times.

On the other hand, in the case of the wire dot print head of the present invention, L+expo/ip+=1.16 only, and the drive by magnetic interference'! This means that the flow increased by the lid is significantly reduced.

Next, FIG. 5 shows a comparison diagram of the suction forces of the prior art and the present invention.

Here, the horizontal axis represents the displacement of the tip of the printing wire, and the vertical axis represents the suction force of the armature at the wire point.

Up to a wire tip displacement of about 0.5 m, the suction force in the wire dot print head of the present invention is larger than that of the conventional one. This is because suction force is generated.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, in the wire dot print head according to the present invention, the first permanent magnet is arranged in the center of the print head to form a magnetic circuit between adjacent magnets.
Because the yoke is removed, when adjacent magnets are driven simultaneously, the magnetic flux that flows into each other is significantly reduced.

Therefore, magnetic interference between adjacent magnets is significantly reduced, making it possible to reduce power consumption.

In addition, the suction of the armature is caused by the first working space 111j13.
Since the printing is performed at two locations, the first and second working gaps 32, the attractive force due to the magnetic flux of the permanent magnet increases, and the strain energy stored in the spring can be increased, making it possible to speed up printing. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a wire dot print head showing an embodiment of the present invention, FIG. 2 is a perspective view of a main part of a wire dot print head of the present invention, and Figures 'IJ & 3 show the magnetic circuit in the wire dot print head of the present invention. 4 is a comparison diagram of the drive current of the prior art and the present invention, FIG. 5 is a comparison diagram of the attraction force of the prior art and the present invention, FIG. 6 is a sectional view of the main part of the conventional wire dot print head, and FIG. The figure is an explanatory diagram of a magnetic circuit in a conventional wire dot print head. 1.29... Armature, 2... First yoke, 3
...Magnetic spacer, 4...Second yoke, 5.21.
...Eternal 61 stones, 6.24...Core, 7,25...
Degaussing coil, 8, 27... Bias leaf spring, 9...
・Armature supporter, lO...printing wire, 11
．． 12.33.34...Magnet, 13, 14.3
5.37... Demagnetizing magnetic flux, 15.30.36... Magnetic flux, 22... Core plate, 23... Magnet yoke, 26... Leaf spring support for bias, 28... For bias Yoke for holding the plate spring, 31...first working gap, 32...second working gap. Patent Applicant Oki Electric Industry Co., Ltd. Agent Patent Attorney Makoto Kawai (1 other person) 1. 234 567 θ q to tt
t2! ! 1N! Motion writing wire Danbo HL Izumi Eda and Koniro's IE trade 319 comparison 2 Fig. 4 6j; Support 1 length υhi comparison diagram

Claims (1)

[Claims] An armature having a printing wire fixed to its tip, a core provided opposite to the armature, a bias leaf spring to which the armature is joined and supported in a cantilevered manner, a permanent magnet that is generated and attracts the armature against the elastic force of the bias leaf spring; In a wire dot print head consisting of a coil that opens, (a) the permanent magnet is placed in the center of the wire dot print head, (b) a magnet yoke that attracts the armature is placed above the permanent magnet, and a core yoke is placed below. (c) A magnetic circuit is formed by a permanent magnet, a magnetic yoke, an armature, a core, and a core yoke.