JPH0445348B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a circular spring-charge type dot print head used in an impact printer.

[Prior Art] As a conventional circular spring charge type dot printing head, for example, the armature and yoke are arranged closer to the core of the electromagnet than the leaf spring that firmly supports the armature, and the shape of the yoke is changed so that the yoke does not exist. Some devices suppress high-order vibrations of the leaf spring by forming the leaf spring into a shape that is almost the same as the deflection curve when the leaf spring is attracted to the core.

However, in a dot printing head with such a configuration, the fixing point of the leaf spring is located in the opposite direction to the support point of the armature, that is, on the outer periphery of the head. Either the size must be reduced or the effective spring portion of the leaf spring must be shortened, but in the former case it is difficult to obtain an appropriate printing pressure, and in the latter case the spring stress becomes too large. It has drawbacks such as the leaf spring breaking due to repeated bending movements.

In recent years, in order to realize a compact dot printing head that suppresses the high-order vibrations of the leaf spring and is capable of high-speed printing, an armature with a dot wire attached to the tip pointing toward the center of the head has been developed. Dot printing having a structure in which the rear part is fixed to a leaf spring, the leaf spring extends from the fixed part toward the center of the head, and the center part is fixed to a yoke forming a side magnetic path of the armature. A head is proposed.

However, in this dot printing head, due to its structure, there is a force couple M (M=P・r) at the fixed part of the leaf spring and the armature, where P is the spring force at the tip of the armature, and r is the length from the fixed part of the armature to the tip of the armature. Due to this, a large stress is applied to the armature fixing portion of the leaf spring during the printing operation, resulting in the leaf spring breaking.

[Purpose of the invention]

The present invention was made in order to solve the above-mentioned drawbacks of the prior art, and it is a circular spring that prevents the leaf spring from breaking and prolongs the life of the head, and also enables high-speed printing and miniaturization. The object is to realize a charge type dot printing head.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention integrally forms a plurality of leaf springs in a radial manner to form a leaf spring assembly plate, a hole is provided in the center of the plate, and each leaf spring is provided with an H-shaped plate. A slit is provided, and the rear part of an armature whose tip is directed toward the hole is fixed to the outer periphery of each of these leaf springs, and a dot wire passing through the hole is attached to the tip of each armature,
In addition, each leaf spring is shaped like a petal whose width increases from the center toward the outer periphery, thereby reducing the stress acting on the leaf spring during printing operations.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a partially cutaway front view showing an embodiment of a circular spring charge type dot printing head according to the present invention, FIG. 2 is a side view with one half of the same embodiment in cross section, and FIG. FIG. 4 is an exploded perspective view of the same embodiment, and FIG. 4 is an enlarged plan view of a leaf spring assembly plate used in the same embodiment.

First, to describe its structure, in Figs. 1 to 4, 1 is a disc-shaped base yoke;
A ring-shaped permanent magnet 2 having the same outer diameter as the base yoke 1 is fixed on the base yoke 1, and a ring-shaped intermediate yoke 3 is fixed on the permanent magnet 2 as well. Also, in the inner position of this,
A plurality of columnar cores 4 are implanted or integrally formed in the base yoke 1 so as to form a substantially circular shape,
Each core 4 is individually wound with an electromagnetic coil 5, and the core 4 and the electromagnetic coil 5 constitute an electromagnet.

Reference numeral 6 denotes a printed circuit board laminated on the rear surface side of the base yoke 1, and each of the electromagnetic coils 5 is soldered to this printed circuit board 6 so as to receive electricity from a power source (not shown).

Reference numeral 7 denotes a ring-shaped spacer similar to the permanent magnet 2, etc., and this spacer 7 is inserted between the intermediate yoke 3 and a disc-shaped yoke to be described later to connect the core 4 of the electromagnet and the armature to be described later. A predetermined suction gap is created between the two.

Reference numeral 8 denotes a disk-shaped yoke having an outer diameter equivalent to that of the spacer 7, etc., and the surface on which the leaf spring assembly plate (to be described later) is fixed, that is, the front surface, is processed to be a flat surface, and the yoke extends from the center toward the outer periphery. A plurality of grooves 9 are formed radially.

Reference numeral 10 denotes a leaf spring assembly plate, which is made up of a plurality of leaf springs 11 extending radially from the center toward the outer periphery as shown in FIG.
are joined at the center, and a substantially circular hole 12 is formed in the center. Each of the leaf springs 11 in this leaf spring assembly plate 10 is approximately petal-shaped with its width increasing from the center side toward the outer circumferential side, and each leaf spring 11 is provided with an H-shaped slit 13. The slit 13 forms tongue pieces 14a and 14b whose tips are opposed to each other.

15 is an armature, and this armature 15
The tip is directed toward the hole 12 of the leaf spring assembly plate 10, and the rear portion thereof is fixed to the outer peripheral portion of the leaf spring 11 including the tongue piece 14a by, for example, laser welding. In addition, in Figs. 3 and 4, armature 1
Although only one numeral 5 is shown, it is fixed to each leaf spring 11 in the same manner as described above.

In this way, the armature 15 fixedly supported by each leaf spring 11 is formed by fixing the leaf spring assembly plate 10 and the disc-shaped yoke 8 in the grooves of the disc-shaped yoke 8 by laser welding or the like on the center side thereof. 9 and is operably loosely fitted within. Each of these armatures 15
is formed in advance to have the same thickness as the disk-shaped yoke 8 with the fixed surface to the leaf spring assembly plate 10 being a flat surface, and the plate spring assembly plate 10 and the disc-shaped yoke 8 are fixed together. After that, the rear surfaces of each armature 15, that is, the surfaces that are attracted to the core 4, can be made to have the same height by polishing or the like, and by doing this, the disk-shaped yoke 8 can be placed on the intermediate yoke 3. When stacked with spacers 7 in between, the suction stroke between each core 4 and armature 15 can be made uniform.

In FIG. 4, reference numeral 16a indicates a fixed point between the leaf spring 11 and the armature 15, and 16b indicates a fixed point between the leaf spring assembly plate 10 and the disc-shaped yoke 8.

17 is a dot wire attached to the tip of each armature 15, and each dot wire 17 is passed through a hole 12 provided in the leaf spring collecting plate 10 from the rear to the front.

Reference numeral 18 denotes a guide frame, in which guide holes 19 are formed in a predetermined array in the center thereof, and the tips of the dot wires 17 are positioned in a predetermined array by the guide holes 19.

Reference numeral 20 denotes a clamp spring, and the above-mentioned parts are assembled into one whole by means of this clamp spring 20. That is, a spacer 7 is stacked on a unit consisting of a base 1, a permanent magnet 2, an intermediate yoke 3, a core 4, an electromagnetic coil 5, and a printed circuit board 6, and a disc-shaped yoke 8, a leaf spring collecting plate 10, and an armature 15 are placed on top of the spacer 7. and dot wires are stacked so that each armature 15 and each core 4 face each other, and the guide frame 18 is further stacked on top of the units, and then these are fixed together with a clamp spring 20. A circular spring-charged dot print head is constructed.

Next, the operation of the above-described configuration will be explained with reference to FIG. FIG. 5A is a sectional view of the main part when the armature is opened.

First, when the electromagnetic coil 5 is not energized, the magnetic flux of the permanent magnet 2 flows through the magnetic circuit consisting of the intermediate yoke 3, the spacer 7, the disc-shaped yoke 8, the armature 15, the core 4, and the base yoke 1. By passing through and returning to the permanent magnet again, the leaf spring collecting plate 1 is formed between the core 4 and the armature 15.
Since the suction force that overcomes the spring force of the leaf spring 11 at zero acts, each armature 15 fixedly supported by the leaf spring 11 is attracted to the tip of the corresponding core 4.
At this time, as shown in FIG. 4, a couple M (M=
P r) acts on the armature 15, and a rotational fulcrum 15a is created between the fixed point 16a with the leaf spring 11 and the part adsorbed to the core 4, and the armature 15 rotates around this rotational fulcrum 15a. Therefore, the outer peripheral side of each leaf spring 11 is connected to the armature 1.
5 is bent in the opposite direction to the direction in which it is attracted to the core 4,
It is held in a state where strain energy is stored.

Next, when the electromagnetic coil 5 is energized, the permanent magnet 2
A magnetic flux is generated that cancels the magnetic flux of
It begins to rotate about the rotational fulcrum due to the restoring force due to the strain energy. At this time, the leaf spring 11
The surfaces of the disk-shaped yoke 8 on both sides facing the disk-shaped yoke 8 are flat surfaces, and the fulcrum portion of the leaf spring is fixed to this surface. As the armature 15 moves away from the core 4, the area of contact with the disc-shaped yoke 8 gradually increases and returns to a state without distortion. As a result, the high-order vibration of the leaf spring 11 is restrained, and the dot wire 17 fixed to the tip of the armature 15
is driven, enabling high-speed, energy-efficient printing.

Also, at this time, the tongue piece 1 on the center side of the leaf spring 11
The tip of 4b is the rotation fulcrum 15 of the armature 15.
Since it extends above a, this rotation fulcrum 15a
This has the effect of restraining the vertical vibration of the dot wire 17, that is, the vibration that occurs when the tip of the dot wire 17 collides with a printing medium (not shown) or when the armature 15 is again attracted to the core 4 and collides with it.
At the same time, a leaf spring 11,
If the mass distribution of the system consisting of the armature 15 and the dot wire 17 is made to coincide with the impact center,
The vertical vibration of the rotation fulcrum 15a can be further reduced.

As is well known, the electromagnetic coils 5 are energized selectively to each electromagnetic coil 5, thereby driving one or more dot wires 17 at the same time to guide their tips. Desired printing can be performed by protruding forward of the head from the guide hole 19 of the frame 18 and striking the print medium through an ink ribbon (not shown).

Next, other embodiments of the leaf spring assembly plate used in the present invention are shown in FIGS. 5A and 5B.

The leaf spring assembly plate 10 in the above-described embodiment has a uniform thickness as a whole, but the leaf spring assembly plate 10 shown in FIG. It is divided into three areas: , common part c, and the thickness of the spring effective part b is thinner than that of the other armature fixed part a and the common part c, which improves the planar shape and installation with other parts. The relationship is the same as that in FIG.

In this way, by making the plate thickness of the effective spring part B thinner than the plate thickness of other parts, the stress distribution becomes even more uniform and breakage becomes less likely. In other words, by doing this, the stress is not concentrated at the deepest part of the H-shaped slit 13, and the maximum stress is generated almost uniformly in the spring effective part, so that the leaf spring 11 becomes difficult to break.

In this case, since the thickness is partially different, the overall structure is more complicated than that shown in FIG. 4, but it can be easily manufactured by etching or the like.

〔Effect of the invention〕

As explained above, in the present invention, each of the leaf springs of the leaf spring assembly plate is approximately petal-shaped, that is, the width of the leaf spring on the side where the armature is fixed is widened, where the couple acting on the leaf spring is large. The stress on the leaf spring can be reduced, thereby preventing the leaf spring from breaking, which has the effect of prolonging the life of the printing head.

In addition, since the rotation fulcrum of the armature can be held down by the leaf spring itself, the number of parts is small and high-speed printing is possible.Also, there is almost no waste when the whole is configured in a circular shape, so even if the same performance is This has the effect of realizing a circular dot printing head with a small diameter.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway plan view showing a circular spring charge type dot printing head according to the present invention;
The figure is a side view of the same embodiment with one side cut away, FIG. 3 is an exploded perspective view of the same embodiment, FIG. 4 is an enlarged plan view of a leaf spring assembly plate used in the same embodiment, and FIG. 5 is the same. FIG. 6 is a diagram for explaining the operation of the embodiment, in which A is a cross-sectional view of the main part when the armature is released, B is a cross-sectional view of the main part when the armature is suctioned, and FIG. 6 shows another structural example of the leaf spring assembly plate. In the figure, A is an enlarged sectional view, B
is a sectional view of a portion thereof. 1...Base yoke, 2...Permanent magnet, 3...
Intermediate yoke, 4...core, 5...electromagnetic coil, 8
... Disc-shaped yoke, 9 ... Groove, 10 ... Leaf spring assembly plate, 11 ... Leaf spring, 12 ... Hole, 13 ... Slit, 14a, 14b ... Tongue piece, 15 ... Armature, 17 ...Dot wire.

Claims (1)

[Claims] 1. When the electromagnetic coil wound around the outer periphery of the core is not energized, the armature is attracted to the core by the magnetic flux of the permanent magnet, the leaf spring that firmly supports the armature is bent, and the electromagnetic coil is Circular spring charge type dot printing that cancels the magnetic flux of the permanent magnet by energizing and releases the armature from the core, and the restoring force of the leaf spring at this time drives the dot wire fixed to the tip of the armature to print. In the head, a plurality of leaf springs are integrally formed in a radial pattern to form a leaf spring assembly plate, a hole is provided in the center of the plate, and an H-shaped slit is provided in each leaf spring to allow each leaf spring to Attach the rear part of an armature with its tip facing the hole to the outer periphery of the armature, attach a dot wire passing through the hole to the tip of each armature, and change the shape of each leaf spring from the center side to the outer periphery side. A circular spring-charged dot printing head characterized by a roughly petal-like shape that widens towards the end.