JPS62236757A - Printing head of printer - Google Patents

Abstract

PURPOSE:To miniaturize a head as a whole, by forming the inner peripheral edge part of a permanent magnet in a circular form concentric to the arrangement circle of cores and forming the outer peripheral edge part thereof into an almost polygonal shape having one side almost parallel to a printing line and the other side crossing the same at an almost right angle. CONSTITUTION:The outer peripheral edge part of a permanent magnet 9 is formed into an almost square shape. Therefore, even if the width of the permanent magnet 9 in the radius direction becomes small at the central part of each side of the square shape, the width of the permanent magnet 9 becomes sufficiently large at the corner part thereof and the area of the permanent magnet can be taken sufficiently largely as a whole and, by this structure, magnetic force necessary for holding an armature 17 at a stop position against the energizing force of an elastic member 14 can be secured.

Description

Detailed Description of the Invention (Industrial Application Field) This invention relates to a printer, and in particular, uses the magnetic force of a permanent magnet to attract an armature toward a core, accumulate biasing force in an elastic member, and stop a printing wire. The present invention relates to a print head that is held in position and is configured to cancel the magnetic path caused by the permanent magnet and move the print wire to the print position by the biasing force of the elastic member based on energization of each coil.

(Prior art and problems to be solved by the invention) Conventionally,
In order to increase the arrangement density within a limited space, this type of print head has multiple cores wrapped with coils arranged in a circle, and an annular yoke member arranged around the outer periphery of each core. Then, an annular permanent magnet is attached to the yoke member to form the entire head into a substantially cylindrical shape, and the armature equipped with the printing wire is pushed against the biasing force of the elastic member by the magnetic force of the permanent magnet. There is a device in which the printing wire is held at the rest position and the magnetic force is canceled by energizing the coil to move the printing wire together with the armature to the printing position.

However, in this conventional configuration, when the print head is downsized, the permanent magnets are also downsized, so the area of the permanent magnet per armature decreases, and the armature cannot be moved to the rest position against the elastic member. There was a risk that it would not be possible to secure the magnetic force necessary to hold the

(Object of the Invention) This invention was made in order to solve the above problems, and its purpose is to create a printer that can reduce the overall size of the head while ensuring the magnetic force necessary for the operation of the armature. Our goal is to provide print heads for

(Means for Solving the Problems) In order to achieve the above object, in the present invention, the inner peripheral edge of the permanent magnet is formed concentrically with the arrangement circle of the core, and the outer peripheral edge is formed in the printing line. A substantially polygonal configuration is adopted, with one side substantially parallel to the other side and the other side substantially orthogonal to that side.

(Function) Therefore, even if the radial width of the permanent magnet becomes small at the center of each side of the polygon, it becomes sufficiently large at the corner.
The area of the permanent magnet as a whole can be large enough,
As a result, magnetic force for each armature can be ensured. In addition, since the dimensions of the print head can be reduced in the direction almost parallel to and perpendicular to the print line while maintaining the magnetic force, the height and width of the printer body can be reduced when the print head is installed in the printer. .

(Example) Hereinafter, an example embodying the present invention will be described in detail with reference to the drawings.

As shown in FIG. 2, a print head 2 is disposed in front of a platen 1 extending left and right within the frame of the printer so as to be movable along a print line on the platen 1. As shown in FIG. As shown in FIGS. 1 to 3, the head body 3 of the print head 2 is formed of a magnetic material into a bottomed cylindrical shape having a circular recess 3a open toward the platen, and the outer periphery of the open end is A flange 4 is provided. The flange 4 is formed into a rectangular shape with two upper and lower sides extending parallel to the printed lines and two left and right sides perpendicular to these sides.

The outer peripheral wall of the head body 3 including the flange 4 constitutes a rear yoke. A plurality of electromagnetic devices 5 (24 in this embodiment) are arranged in a circle on the bottom surface of the recess 3a. Each electromagnetic device 5 includes a core 6 integrally formed to project from the head body 3 at equal angular intervals, and a coil 8 wound around the core 6 via a coil bobbin 7.

A permanent magnet 9 is bonded and fixed to the front side surface of the flange 4. This permanent magnet 9 is composed of a pair of left-right symmetrical plate-shaped divided pieces 9a, 9b, and each divided piece 9a, 9
b are joined and fixed at opposite ends, and the outer shape thereof is the same as the outer shape of the flange 4. Also,
An opening 9C is formed in the center of the permanent magnet 9 and is concentric with the circle in which the cores 6 are arranged. A front yoke 11 is bonded and fixed to the front side of the permanent magnet 9 via a spacer 10 made of a magnetic material, and a plurality of slits 12 are formed in the front yoke 11 to face each electromagnetic device 5 and extend radially. ing.

On the front side of the front yoke 11, an elastic member 14 is formed of an elastic plate material and has a plurality of support pieces 13 extending radially opposite each of the slits 12. A pair of elastic members 14 made of a magnetic material A plurality of armatures 17 made of a magnetic material are swingably supported by each support piece 13 of the elastic member 14 at its base end. The base end of each armature 17 is disposed within each slit 12, and the printing wire 18, which is converged in the center of the head body 3 and extends toward the platen l, is disposed at its base end. It is attached.

That is, a plurality of protrusions 20 that protrude radially between the armatures 17 are integrally formed on the outer circumferential annular portion of the elastic member 14, forming one continuous annular comb-like base portion 19. . Further, a first torsion bar portion 21 is integrally formed as a bridge between each of the protrusions 20. An armature fixing part 22 extending radially inward is integrally formed in the center of each first torsion bar part 21, and a pair of second torsion bar parts protruding laterally is provided at the tip of each fixing part 22. 23 are integrally formed. In addition, on both sides of the armature fixing part 22, each protrusion 20 and each second torsion lever part 23 are integrally connected by a pair of leaf spring parts 24.

And the first. The second torsion bar parts 21 and 23, the armature fixing part 22, and the leaf spring part 24 constitute a support piece 13 for one armature 17, and each armature 17 is superimposed on each armature fixing part 22. , each armature 17 is fixed to each support piece 13 by irradiating an electron beam or the like to the positions indicated by circles in FIGS. 3 and 4.

Further, each of the spacers 15 and 16 includes the elastic member 14.
A protrusion 25 is integrally formed to overlap the protrusion 20, and each protrusion 25 holds the proximal end portions of a pair of leaf spring portions 24 adjacent to each other inwardly from the spring portion 21. A pair of clamping portions 26 are formed. A flat plate portion 27 and a nose portion 28 are provided on the front side of the spacer 16.
A covering body 29 having a cover body 29 is fixedly joined at its flat plate portion 27, and each of the printing wires 18 is movably inserted into the nose portion 28.

As shown in FIG. 1, four positioning protrusions 30 that protrude rearward are integrally formed at the four corners of the flat plate part 27, and the tip thereof has a temporary lock that can be engaged with the rear surface of the flange 4. Piece 30a is integrally formed. On the other hand, the flange 4
．． Permanent magnet9. Spacer 10. Front yoke 11. At the four corners of the spacer 15° 16 and the elastic member 14, there are recesses 31, 3 of approximately the same shape that fit into each of the positioning protrusions 30.
2, 33, 34, etc. are formed respectively. and,
Each positioning protrusion 30 is attached to each member 4.9°10.11.
15. With each recess 31 to 34 etc. of 16 fitted,
Each of the members 4.9, 10.11, 15 is attached to the flat plate portion 27.
．． 16 are stacked one on top of the other in a predetermined order and are fixed together by appropriate connecting means.

In the print head configured as described above, when the coil 8 of each electromagnetic device 5 is not energized, the spacer 10 is moved by the permanent magnet 9 as shown by the two-dot chain line in FIG.
．． Front yoke 11. Armature 17. A magnetic path is formed through the core 6 and the flange 4, whereby each armature 17 is attracted to the entire end face of the core 6, each printing wire 18 is placed in a rear rest position, and the elastic member 14
Each support piece 13 is displaced rearward, each torsion bar portion 21, 23 is torsionally deformed, and each leaf spring portion 24 is bendingly deformed to accumulate biasing force.

In this state, when the coil 8 of each electromagnetic device 5 is selectively energized and the core 6 is temporarily excited so as to cancel the magnetic path, the first
After the armature 17 is swung around the torsion bar portion 21 to the printing position, it is swung back to the printing position based on the magnetic force of the permanent magnet 9 and held at the rest position. Due to the reciprocating movement of the printing wire 18 accompanying the reciprocating swing of the armature 17, the printing paper (none of which is shown) on the platen l is passed through the printing pump between the print head 2 and the platen l.
Dots are formed on the surface.

In this embodiment, since the outer peripheral edge of the permanent magnet 9 is formed into a substantially square shape, even if the radial width of the permanent magnet 9 at the center of each side of the square becomes small, the permanent magnet 9 The width becomes sufficiently large at the corners, and the area of the permanent magnet as a whole can be sufficiently large, thereby ensuring the magnetic force necessary to hold the armature 17 in the rest position against the biasing force of the elastic member 14. can do.

(Another Embodiment) Next, another embodiment embodying the present invention will be described with reference to FIG. The center portions of the top and bottom sides, which extend almost parallel to the printed line, are slightly curved toward the top and bottom, and the center portions of the left and right sides, which are approximately perpendicular to the top and bottom sides, are each slightly curved toward the left and right. It differs from the previous embodiment in that it is formed.

Therefore, in this other example as well, as in the previous embodiment, the corners and the center portions of each side of the permanent magnet 40 can be effectively utilized to make the area of the permanent magnet as a whole sufficiently large. The overall size of the head can be reduced while ensuring the magnetic force necessary to hold the head in the rest position against the biasing force of the elastic member 14.

Note that this invention is not limited to the above embodiments, and the configuration of each part may be arbitrarily changed without departing from the spirit of the invention, such as forming the outer peripheral edge of the permanent magnet into an octagonal shape. It is also possible.

(Effects of the Invention) As detailed above, in this invention, even if the radial width of the permanent magnet becomes small at the center of each side of the polygon, it becomes sufficiently large at the corners, and the area of the permanent magnet as a whole is sufficiently large. As a result, magnetic force for each armature can be secured. In addition, since the dimensions of the print head can be reduced in the direction almost parallel to and perpendicular to the print line while maintaining the magnetic force, the height and width of the printer body can be reduced when the print head is installed in the printer. It has this excellent effect.

[Brief explanation of drawings]

1 to 4 show an embodiment embodying the present invention, in which FIG. 1 is a partially exploded perspective view of the print head;
Figure 2 is a partially cutaway side view of the print head;
The figure is a sectional view taken along the line ■--■ in FIG. 2, and FIG. 4 is a partially enlarged exploded perspective view showing the armature support structure. FIG. 5 is a perspective view of a permanent magnet in another embodiment embodying the invention. In the figure, 2 is a printing head, 4 is a flange forming a yoke member, 6 is a core, 8 is a coil, 9°40 is a permanent magnet, 14 is an elastic member, 17 is an armature, and 18 is a printing wire. Patent applicant Brother Industries, Ltd. Agent
Patent Attorney On 1) Hironobu Drawing Part 2 il [1■

Claims (1)

[Claims] 1. A plurality of cores (6) arranged in a circle, and each core (6).
), a yoke member (4) arranged around the outer periphery of each core (6), and an elastic member ( a plurality of armatures (17) each swingably supported via a plurality of armatures (14); a printing wire (18) attached to each armature (17) at one end and converged at the other end; and the yoke. each core (6) attached to the member (4);
a permanent magnet (9) forming a magnetic path passing through each armature (17) and the yoke member (4);
) attracts the armature (17) to the core side and accumulates a biasing force in the elastic member (14),
The printing wire (18) is held at the rest position, and the magnetic path caused by the permanent magnet (9) is canceled out by energizing each of the coils (8), and the printing wire (18) is moved by the urging force of the elastic member (14). 18) in which the print head (2) is moved relative to the printing position along the printing line, the inner peripheral edge of the permanent magnet (9) is arranged in a concentric circle with the arrangement circle of the core (6). 1. A print head for a printer, characterized in that the outer periphery is formed into a substantially polygonal shape having one side substantially parallel to the printing line and the other side substantially perpendicular thereto. 2. The print head for a printer according to claim 1, wherein the outer peripheral edge of the permanent magnet (9) is approximately square. 3. The printer print head according to claim 2, wherein the yoke member (4) has a substantially square outer peripheral edge and a circular inner peripheral edge in a portion where the permanent magnet (9) is attached. .