JPS63276558A - High-speed print head with fulcrum structure - Google Patents

Abstract

PURPOSE:To achieve high speed printing and enhance productivity and reliability, by providing the fulcrum brought into contact with the effective elastic part of a leaf spring, which drives an armature toward a printing medium by allowing a current to flow to an electromagnetic coil, to the base body of a printing head. CONSTITUTION:When a current is allowed to flow to each of coils 9 and the magnetic flux due to a permanent magnet 11 is cancelled by a core attracting surface 82, the core attracting surface 82 and a yoke upper surface 121 are set to reference planes and a plate is laminated thereon to be assembled and, therefore, positional accuracy is easy to take and productivity is enhanced. When attraction force F acts on the armature 1, reaction forces R1, R2 are respectively generated at the fulcrum and a fixed end. The reaction force R2 becomes the same direction as the attraction force F and the reaction force R1 of the fulcrum part becomes the sum of F and R2 in a static balanced state. This fulcrum reaction force R1 prevents the separation of a leaf spring from the fulcrum even when the attraction force F is extremely strong and impact force acts on the end of a wire in a printing manner and the armature can be stably operated at a high speed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a print head for a wire dot printer in which an armature equipped with a print head is attracted by the attractive force of a permanent magnet and is driven by the biasing force of a leaf spring. In particular, the present invention relates to a high-speed print head capable of high-speed printing.

[Conventional technology]

■ A conventional wire dot print head, in which the biasing force of a leaf spring overcomes the attractive force of a permanent magnet to perform printing, has a plurality of dots connected to a base made of an annular plate, as described in Japanese Patent Laid-Open No. 56-37176. Each of the plurality of armatures, each of which has a printing wire fixed to its tip, is attached to a leaf spring body constituted by tongues regularly adjacent to each other and extending toward the center of the base. There is a method of simply fixing the base part of the leaf spring body by fixing it on the extended side of the leaf spring body.

This method has the advantage of being able to configure the leaf spring as a single leaf spring body and is highly productive, but on the other hand, the supporting rigidity of the armature of the leaf spring in the armature movement direction is low, and the impact force during printing is This causes complex vibrations in the leaf spring, which tends to deteriorate the return characteristics of the armature, making it unsuitable for high-speed print heads. (2) In an attempt to improve this, there is a method of providing a rotational fulcrum at the end of the armature, as described in Japanese Utility Model Publication No. 57-57977 and Japanese Patent Publication No. 58-56354. However, in this method, when the armature is attracted to the core, it deforms into an S-shape, so if the leaf spring length is short, stress is high and reliability is low. For this reason,
In order to reduce the stress and obtain the necessary displacement of the print head, the leaf spring must be made longer, resulting in a larger print head. Therefore, it has to be limited to operation within a limited range of speeds, and is not suitable for high-speed print heads.・■For this reason, for high-speed printing heads (for example, those that print approximately 2000 dots or more per second per printing wire), the cross spring method described in JP-A No. 52-49119 has been considered. Such a print head has a complicated structure and a large number of parts, resulting in poor productivity.

■Also, as described in JP-A No. 55-84682, a structure having a first fulcrum that freely rotates at the end of the leaf spring and a second fulcrum that is formed in contact with the elastic part of the leaf spring. A print head was also considered. However, since this method has a structure in which the end portions of the leaf springs rotate freely, each leaf spring cannot be integrally formed, and the number of parts is large, resulting in poor productivity.

[Problem that the invention seeks to solve]

The above conventional technology has a print head capable of high-speed printing.
Not enough consideration was given to productivity, reliability, or miniaturization.

An object of the present invention is to provide a print head that achieves high-speed printing, improves productivity, has sufficient reliability, and does not need to be enlarged.

[Means for solving problems]

A printing wire is fixed to the tip of a leaf spring body consisting of a plurality of tongues from a base made of annular plate material regularly adjoining each other and extending toward the center of the base. Each of the plurality of armatures is fixed on the extension side of each of the tongues, and the magnetic attraction force of the permanent magnet attracts the attraction member of the armature to deflect the effective elastic part of the tongue, thereby causing current to flow through the electromagnetic coil. In the print head that cancels the magnetic attraction force and drives the armature toward the print medium by the biasing force of the leaf spring, a support point that comes into contact with the effective elastic portion of the leaf spring is provided on the print head base. achieved.

[Effect]

According to the present invention, since the fulcrum is formed by contacting the effective elastic part of the leaf spring, complex vibrations are not generated in the leaf spring elastic part even by impact force during printing, and the return characteristics of the armature are good. Yes, high-speed printing is possible (■).

Further, since a leaf spring elastic portion is also present between the fulcrum and the armature fixing portion, the spring length can be made longer than in the conventional invention. Therefore, compared to conventional technology, the thickness of the leaf spring can be increased to obtain the necessary displacement of the printing wire, reducing stress on the leaf spring and improving reliability (■)
. Furthermore, by making the stress equivalent to that of the conventional invention, the distance between the base of the leaf spring body and the fulcrum can be shortened, and the print head can be downsized (■).

Furthermore, in the present invention, the entire leaf spring body can be integrally formed, and can be assembled in a laminated structure on the mounting plane of the print head base, resulting in high assembly accuracy and high productivity (■■).

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 21.

[First Embodiment] FIG. 1 is a sectional view showing the overall structure of a print head embodying the present invention, and FIG. 2 is a perspective view showing the main operating parts of FIG. 1. The leaf spring body 5 extends from a base part 51 made of a plate material having an annular shape toward the annular center of the base part such that a plurality of tongue pieces 52 are regularly adjacent to each other. Tongue piece 5
2, print wire 2 and lever integrated 3 in order from the tip.
The armature 1 to which the suction member 4 is fixed is fixed.

Between the armature fixing part of the tongue 52 and the base border of the leaf spring body 5 there is an effective elastic part 53 of the tongue. core 8
is the insertion part 8 of the coil 9 corresponding to each armature 1
1, and has a suction surface 82 on its upper surface for suctioning the suction member of the armature, and each core 8 is integrated at a core outer peripheral portion 83.

A permanent magnet 11 and a yoke 12 are stacked on the outer peripheral portion 83 of the core and fixed to the casing 131 . The suction surface 82 of the core 8 and the upper surface 121 of the yoke 12 are finished on the same plane. The coil 9 is wound around a bobbin 91. The terminal 92 of the coil is brought out from the casing 131 to the outside of the print head.

Further, on the yoke upper surface 121, a side yoke 14 formed of a plate material and a fulcrum forming member 15 are laminated to form a print head base, and a leaf spring body 5 and a casing 132 are further laminated, not shown. It is fixed with screws or other means. Wire guides 61 and 62 that support the printing wire 2 are fixed to the casing 132.

The base portion 51 of the leaf spring body 5 is sandwiched between the fulcrum forming member 15 and the casing 132, and serves as a fixed end of a tongue piece 52 extending from the base portion 51. The front edge of the fulcrum forming member 15 comes into contact with the effective elastic portion 53 of the tongue piece 52 to form a rotation fulcrum 151 of the armature 1 .

The suction member 4 is inserted into the groove 141 of the side yoke. Then, the yoke 12, the side yoke 14, the suction member 4
A magnetic circuit is formed by the core 8, and the armature 1 is attracted to the core attraction surface 82 at the attraction member 4 by the attraction force of the permanent magnet 11. At this time, the effective elastic portion 53
deforms and stores strain energy, ready to generate a biasing force that returns the armature 1.

[Second Embodiment] FIG. 3 is a diagram showing a second embodiment, and is a sectional view showing the overall structure of a print head. Unlike the first embodiment, the tongue piece 5
2 is fixed to the entire surface of the core side of the suction member 4, and a fulcrum forming member 15 is laminated on the upper surface 121 of the yoke 12 to form a print head base, and further a leaf spring body 5, a side yoke 14, and a casing are attached. They are stacked in the order of 132 and fixed by means such as screws (not shown). The rotation fulcrum 151 is formed by the effective elastic portion 53 coming into contact with the front edge of the fulcrum forming member 15, as in the first embodiment. The attraction member 4 is inserted into the groove 141 of the side yoke, and a magnetic circuit is formed by the yoke 12, the fulcrum forming member 15, the leaf spring base 51, the side yoke 14, the attraction member 4, and the core 8, and the permanent magnet 1
1, the armature 1 is attracted to the core suction surface at the suction member 4. At this time, similarly to the first embodiment, the effective elastic portion 53 deforms and stores strain energy, allowing the armature to return to its original position and ready to generate a biasing force.

Next, the effects of the first and second embodiments will be explained. When a current corresponding to the recorded image signal is passed through each coil 9 and the magnetic flux generated by the permanent magnet 11 is canceled by the core attraction 82, the magnetic attraction force is reduced and the biasing force of the leaf spring becomes a magnetic attraction force. As a result, the strain energy stored in the effective elastic part of the leaf spring is released, and the armature 1 moves to the pivot point 15.
1, the wire protrudes from the wire guide 61, and strikes a printing medium such as an ink ribbon or printing paper (not shown) to print dots.

Immediately before or after striking, the current in the coil is cut off, and the armature returns to its initial position due to the reaction force upon striking the printing medium and the restored magnetic attractive force.

As described in the first and second embodiments shown in FIGS. 1 to 3, according to the present invention, the core adsorption surface 82 and the yoke upper surface 1
21 is used as a reference plane, and since planar plates are stacked and assembled on this plane, positional accuracy can be easily achieved and productivity can be improved.

[Effects of stress reduction and miniaturization]

The effects of the present invention will be explained with reference to FIGS. 4 and 5 based on the first embodiment. FIG. 4 is a cross-sectional view of the main parts of the first embodiment shown in FIG. 1 and a drawing showing the moment distribution of the leaf spring.

The armature and leaf spring body shown by solid lines in FIG. 4(a) are in a neutral position where no external force is acting on them, and those shown by broken lines are in a state where a suction force F is applied to the suction member.
The leaf spring is deflected and the armature is rotated.

In FIG. 4(a), the length of the armature 1 is La,
Let Lsx be the length of the effective elastic portion 53 from the armature attachment end to the fulcrum, Lc2 be the length from the fulcrum to the fixed end, and Lc be the distance from the point of application of the suction force F to the fulcrum.

When the suction force F acts, reaction forces R and R2 are generated at the fulcrum and the fixed end, respectively. The reaction force R2 acting on the fixed end is
It has the same direction as the attraction force F, and in a static balance state, the fulcrum partial reaction force R1 is the sum of F and R2. This fulcrum reaction force R
1 is a force generated as a result of the suction force F strongly pressing the leaf spring toward the fulcrum, and in the present invention, this pressing force is very strong, and a striking force acts on the wire end in terms of printing. This also enables stable, high-speed movement of the armature that moves the leaf spring away from the fulcrum.

Assuming that the height of the fulcrum is the same as the height of the fixed end of the leaf spring, the shape of the effective elastic part is rectangular, and the thickness of the leaf spring is constant, R1 and R2 are as follows.

2LS□ 2LS□ From this result, the bending moment of the effective elastic part of the leaf spring is
As shown in Fig. 4(b), -F at the armature mounting part
(Lc Ls□), -FLc at the fulcrum and FLc/2 at the fixed end. By dividing this bending moment by the section modulus, the stress in the leaf spring can be determined.

The stress reduction effect of the present invention will be explained below using numerical calculations.

In Figure 4, we will examine what happens to the stress generated in the leaf spring when the distance Lc from the armature mounting end to the fulcrum is changed while keeping the suction force F and the printing wire displacement δ constant. In order to avoid enlarging the shape of the print head, here, the sum of the armature length a and the distance LSt between the armature mounting part of the effective elastic part 53 and the fulcrum is set to 17 discs (constant), and similarly the distance between the fulcrum and the fixed end is set to 17 (constant). The distance LS2 was 5 m, the distance Lc between the suction force application point and the fulcrum was 8.4 nn, and the leaf spring shape was rectangular with a width of 4.5 mm (constant). Under the above conditions, the leaf spring stress is evaluated by the stress at the fulcrum part where the value is the largest.

FIG. 5 is a drawing showing the calculation results, where the horizontal axis is the distance LS□ from the fulcrum at the armature mounting part, the thickness of the leaf spring is shown as a broken line, and the stress of the leaf spring is shown as a solid line.

When Ls□ is O, that is, when it is the same as the conventional technology ■, the leaf spring thickness is approximately 0.26 mm and the stress is approximately 670 MP.
a (68 kg/mm”).Lengthening LSx essentially increases the spring length. Therefore,
If the design is based on the condition that the spring constant is set to be the same, the thickness of the leaf spring can be increased, resulting in a reduction in stress. For example, when Ls□ is II, the plate thickness is approximately 0.0
31nn, and as a result, the stress is 480MPa (approximately 4
9 kg/mn”).Ls□
The longer it is, the lower the splashing stress can be, but in a print head with limited dimensions, there may be positional interference with the suction member, and the upper limit is about 5nn+. Dew.

In addition, in the above explanation, the spring constant was assumed to be the same in order to maintain a predetermined wire displacement when the suction force was applied, but this spring constant may vary depending on various conditions regarding the operating characteristics of the armature. It should be set to a value that is reasonable. Therefore, the matters explained in Figures 4 and 5 are as follows:
The above description is by way of example, without limitation to the values set forth above.

As described above, according to the embodiment of the present invention, the stress of the leaf spring can be lowered compared to the conventional one, and reliability can be improved.

Since the stress of the leaf spring may be set to be less than the breaking strength in repeated operations, if there is an allowance for the stress, the length of the leaf spring can be shortened according to the extent of the allowance. That is, specifically, the distance LS2 from the fulcrum of the effective elastic portion to the fixed end can be shortened, and the shape of the print head can be made smaller than in the past.

[Effects of operation waveforms and high-speed printing]

FIGS. 6 and 7 show operating waveforms in the first or second embodiment of the present invention.

The conditions for obtaining this operating waveform are that the equivalent mass of the armature at the printing wire position is approximately 34cm, and the armature length is La.
is 16 mm, leaf spring length LS1 is 1 mm, and LS2 is 5 mm.
, the leaf spring width is 4.5 m, the leaf spring thickness is 0.30 m, and the spring constant at the printing wire position is approximately 3100 N/m (3
20g/nn+). At this time, the center of impact (center of impact) of the armature when struck with the end of the printing wire is located at 4.7I on the printing wire side from the fulcrum. The neutral position of the leaf spring is located at a position where the print wire is attached to the armature and is displaced by 0.61 TITI with respect to when the core is attracted.

The conditions in FIG. 6 are that the printing medium is placed with a gap of about 0.2 mm from the end face of the wire so that the wire is displaced by about 0.3 mm.

The waveforms in Figure 6 are shown in order from top to bottom, with time plotted on the horizontal axis.
Response displacement waveform of the printing wire, (b) Impact force of the printing wire on the printing medium, (c) Stress at the fixed end of the leaf spring, (d) Stress at the leaf spring fulcrum, (e) Stress at the leaf spring armature attachment part It shows. After the current is applied to the coil, there is a time delay, but after starting, the armature leaves the core suction surface 81 and comes into contact with the printing medium in about 140 μs, and printing force starts to be generated, and the printing medium is further drawn. Distort the field by approximately 0.1. The peak value of the printing impact force at that time is approximately 5N (500 gf). Immediately before this, the current pulse of the coil is cut off, and the armature quickly returns to its initial position, the core attraction surface, due to the attraction force of the restored permanent magnetic force and the reaction force of the striking force. Thereafter, further current pulses are applied and printing is performed continuously by the spring force. The stress in each part of the leaf spring is also low at a maximum amplitude of about 300 MPa, and the printing wire has good responsiveness. The printing wire completes printing one dot in 280 μs, and is capable of printing approximately 3500 dots per second.

This indicates that the fulcrum formed in contact with the leaf spring effective elastic portion is operating effectively as a fulcrum.

FIG. 22, which is shown as a comparative example with respect to the operating waveform of this embodiment, is a diagram showing the operating waveform of the first conventional example (Prior art column ■). The armature and the elastic part of the leaf spring do not have a fulcrum that is formed by contacting them.

The armature used in the experiment shown in Fig. 22 is
The leaf spring used is exactly the same as that explained in the figure, and since its support form is completely different from that of the present invention, the leaf spring thickness is increased to 0.5 mm, and the spring constant of the leaf spring is approximately The condition was the same as that shown in FIG. FIG. 22 shows the response waveform of the printing wire and the impact force on the printing medium when the printing wire and the printing medium are separated by 0.2 mm.

In the return characteristic of the armature after printing shown in FIG. 22, the wire displacement remains stationary while striking the paper, and the return characteristic is delayed. The peak value of the impact force on the paper at this time is also lower than that in FIG. 6, and its range is also wider. This is because the supporting steel of the leaf spring is poor and the pivot point of the armature is not clearly defined when the paper is struck, resulting in the armature escaping from the print medium. The time required for the wire to stroke approximately 0.3+nm is 350
The number of dots per second is 2860 dots, which is more than 20% slower than the example shown in FIG.

[Challenges in operating waveforms and high-speed printing]

The conditions in FIG. 7 are such that the print medium is placed with a gap of approximately 0.4 TIn from the end face of the wire so that the wire is displaced by approximately 0.5 mm.

The waveforms in Fig. 7 are, from top to bottom, (a) response waveform of the printing wire, (b) displacement waveform at the fulcrum of the leaf spring, and (c)
It shows the impact force of the printing wire on the printing medium, and (d) the stress of the armature attachment part of the leaf spring.

The printing wire operates normally until it hits the printing medium, but after hitting the printing medium, the leaf spring lifts up from the fulcrum, the return characteristics of the printing wire are poor, and the stress in the leaf spring is high, so we are not satisfied. does not exhibit the characteristics it should have.

As a wire dot printer print head, the gap between the print head and the print medium is 0, 2n, which is the condition shown in Figure 6.
wn is also sufficient.

In order to prevent the situation shown in Figure 7, it is necessary to keep the wire stroke below a predetermined value by, for example, installing a stopper at the tip of the lever, thereby maintaining good return characteristics and reducing the stress on the leaf spring. is possible.

However, it is generally desirable for the wire to be able to make a longer stroke, and the dynamic behavior of the armature under the conditions shown in FIG. 7 will be mechanically studied using FIG.

FIG. 8 is a diagram schematically showing the operation of this embodiment, showing the main part of the print head in a side view. In Figure 8, 2
0 is the print medium. FIG. 8(a) shows a state in which the leaf spring effective elastic portion 53 is bent by the suction force F, and the armature 1 is rotated from the neutral position. At this time, the leaf spring 53
, a bending moment M=19-, which is a biasing force that restores the armature 1, is generated. Further, as described above, the suction force F acts on the fulcrum reaction force R and the reaction force R' that presses the leaf spring against the fulcrum. Next, when a current is passed through the coil,
As shown in FIG. 8(b), the suction force F decreases, the bending moment M of the leaf spring overcomes the armature, the armature begins to rotate in the direction of the print medium, and the wire speed reaches this point. When the armature strikes the printing medium a considerable amount before the neutral position of the leaf spring as in the condition shown in Fig. 6, the condition shown in Fig. 8(b)
As shown in FIG. 2, there is a force R' pressing the leaf spring at the fulcrum, and the leaf spring 53 does not lift up from the fulcrum 151 even if a printing force is applied to the end of the printing wire. However, when the armature moves to a point very close to the leaf spring neutral position, as in the printing conditions shown in Figure 7, the fulcrum reaction force R is the force that holds the leaf spring at the fulcrum as shown in Figure 8 (c). R' is very small, and a moment M is generated by the impact force P during printing and the inertia force F1 of the armature, and this force rotates the armature around the center of impact as shown in FIG. 8(d). The leaf spring 53 is lifted off the fulcrum 151. For this reason, when the stroke of the wire is large, the armature does not perform the desired rotational movement, causing unnecessary vibrations in the elastic part of the leaf spring, resulting in high stress and poor return characteristics.

[Third Embodiment] Therefore, since a method has been devised to match the center of impact and the pivot point, the dynamic behavior of a third embodiment in which the present invention is applied to this method will be discussed.

In order to match the center of impact and the rotational fulcrum,
6354, it is necessary for the suction member to extend beyond the fulcrum, and the member has approximately the same cross section as the armature suction member of the second embodiment described in FIGS. 6 and 7. was extended 81m+ to the fulcrum side. LSl
is 1+nm, so the armature has a fulcrum of 7m.
It exceeds n. The shape of the leaf spring is the same as the previous condition.

At this time, the equivalent mass of the wire attachment part around the fulcrum is approximately 42 cm, and the center of impact is completely aligned with the fulcrum.

[Operating waveform]

Similar to FIG. 7, FIG. 9 shows a response waveform when the distance between the print head and the print medium is approximately 0.4 mm.

As shown in FIG. 9(a), the wire is displaced by about 0.5 mm. The responsiveness of the wire is good, and the printing force is normal as shown in FIG. 9(c). At this time, the printing wire is approximately 490μ
One dot is printed in s, approximately 200 dots per second.
It is possible to print 0 dots.

However, as shown in FIG. 9(b), when the printing medium is hit,
When the armature returns to its initial position on the core suction surface, the leaf spring 53 lifts up from the fulcrum due to the impact force, and at this time, as shown in FIG. 9(d), a large stress is applied to the armature attachment part of the leaf spring. occurs.

In Figure 10, the distance between the print head and print medium is 0.2 mm.
The response waveform when the center of impact coincides with the fulcrum is shown by a solid line, and for comparison, the waveform in FIG. 6 is shown by a broken line. The operating characteristics are slower than in the case shown in Fig. 6 due to the increased moment of inertia of the armature, and as in Fig. 9, when the armature returns, the plate will move as shown in Fig. 10 (e). Generates large stress at the spring armature attachment part.

Further, the time required to print one dot is 320 μs, and the number of dots per second is about 3100 dots, so the response characteristics are more than 10% slower than in the case of FIG.

FIG. 11 is a diagram schematically showing the operation of the third embodiment of the present invention. FIG. 11(a) shows a state in which the printing wire 2 returns at a speed of □ after hitting the printing medium. The rear end of the armature 1 extending from the fulcrum 151 toward the spring fixed end is moving at a speed ν2 in a direction opposite to the direction in which the wire moves. Furthermore, the armature continues to move,
It collides with the core 81 as shown in FIG. 11(b). At this time, since the armature extends toward the rear end, the inertia force F1 at the rear end of the armature generates a bending moment M shown by the arrow in the figure, and this force moves the leaf spring 53 toward the fulcrum 15.
Raise it from 1. For this reason, the leaf spring does not undergo the desired deformation, and excessive stress is applied to the armature mounting portion of the leaf spring.

Therefore, the method of extending the armature toward the spring-fixed end has good return characteristics after the printing wire hits the printing medium, but the stress is high when the core collides, and the response speed is reduced due to an increase in the moment of inertia of the armature. There is room for improvement.

[Fourth Embodiment] FIG. 12 shows a fourth embodiment of the present invention, in which FIG. 12(a) is a partially sectional side view showing the main parts of the print head, FIG. 12(b) is a moment distribution diagram at the spring neutral position, and FIG. 12(c) is a moment distribution diagram when the armature is attracted to the core. In FIG. 12, the fulcrum forming member is formed so that the fulcrum 151 of the fulcrum forming member 15 is higher than the base surface of the leaf spring of the fulcrum forming member 15, as shown in FIG. 12(a). Therefore, even in the neutral position of the leaf spring where no biasing force acts on the armature, the armature is held in a biased state as shown in FIG. 12(a). At this time, reaction forces R1 and R2 are generated at the leaf spring fulcrum and the fixed end, respectively, and in a static balanced state, R1 and R2 are equal. At this time, the moment of the leaf spring is 0 at the fulcrum and R1Ls2 at the fixed end, as shown in the moment distribution diagram in FIG. 12(b). When the suction force F acts on the armature as shown in Fig. 4,
) is added to the moment distribution in FIG. 12(b), resulting in the result as shown in FIG. 12(c). According to this embodiment, since the reaction force R exists at the fulcrum even when the leaf spring is in its neutral position, even if the force that presses the leaf spring acts and the printing wire is displaced close to the neutral point, the leaf spring will move away from the fulcrum. The floating armature has good return characteristics, and since there is no increase in the moment of inertia of the armature, the response is quick. However, the fulcrum 151 is worn out due to the printing operation of tens of millions of dots by the armature. In the case of this embodiment, the fulcrum 151 is formed in a protruding manner on a plate-shaped fulcrum forming member, and the deflection amount of the leaf spring is determined by the height of the fulcrum 151. Therefore, when the fulcrum height decreases due to wear, the armature core The leaf spring force of the leaf spring when it is attracted to the paper is significantly reduced from a predetermined value, making it impossible to perform the desired printing operation.

Therefore, in this embodiment, it is necessary to use a material with excellent wear resistance for the fulcrum member.

[Fifth Embodiment] FIGS. 13 and 14 show the fifth embodiment of the present invention. FIG. 13 schematically shows a side view of the main part, and FIG. It is an enlarged view of the vicinity of the fulcrum part of the figure. In this embodiment, the suction member 4 of the second embodiment is extended to the vicinity of the fulcrum, and a spring means 22 facing the fulcrum is provided to press the armature against the fulcrum. According to this embodiment, the stress of the leaf spring and the equivalent mass of the armature do not increase significantly, and the leaf spring can be prevented from lifting off from the fulcrum, so that a print head with quick response can be provided.

However, as shown in Fig. 14, when the armature rotates by an angle θ, if the thickness of the leaf spring and the suction member is h, then
A slip of hO occurs at the pressure point of the spring means 22. For this reason, there is a problem that the armature and the spring means are easily worn out, and a frictional force is generated, making the printing characteristics unstable. Therefore, the suppressing portion of the spring means needs to be a low-friction, low-wear member.

[Sixth Embodiment] FIGS. 15 to 18 describe a sixth embodiment of the present invention.

FIG. 15 schematically shows the embodiment of FIG.
FIG. 3 is a sectional view of the main part of printing. This embodiment is an improvement on the first embodiment, and a spring means 22 is provided on the opposite side of the leaf spring 53 to the fulcrum part 151, and the leaf spring 53 is pressed against the fulcrum 151 by the spring means 22. As shown in FIG. 1S, the printing wire 2 hits the printing medium 20 near the neutral position of the leaf spring, and the impact force P and the armature inertia force F create a moment M that lifts the leaf spring 53 from the fulcrum.
Even if this occurs, the pressing force FP of the spring means 22 can prevent the leaf spring from lifting off from the fulcrum.

FIG. 16 is a side view, partially in section, of the print head of the sixth embodiment, and FIG. 17 is a perspective view showing the main parts of the print head. The spring means 22 is configured as a leaf spring and extends from the base 221 to a plurality of tongues 222 of the spring members.
extend regularly adjacent to each other. A protrusion 223 is formed at the tip 222 of the tongue of the spring member so as to protrude toward the fulcrum so as to press the leaf spring elastic portion 53 at the fulcrum position. Spring means tongue piece 222 and leaf spring tongue piece 52
are fixed at their respective bases in a stacked manner so as to overlap each other at the same position.

[Operating waveform]

FIG. 18 shows a diagram in which the armature described in FIGS. 6 and 7 is used, each leaf spring elastic portion is pressed by a spring means with a pressing force FP of 5 N, and the wire end surface is approximately 0.0
．． The solid line shows the operating characteristics when the printing medium is placed with a gap of 4 mm, and for comparison, the waveform of FIG. 9 in which the center of impact and the fulcrum coincide with each other is shown by the dashed-dotted line.

As is clear from Fig. 18, the printing wire in the sixth embodiment operates at high speed, and it takes 430 μS to print one dot, and the number of dots per second is 2300 dots, which is the case in Fig. 9. The response speed is 60 μs, the number of dots is 300 dots faster, and the printing speed can be increased by 15%. This shows good characteristics, with no lifting of the leaf spring at the fulcrum and low leaf spring stress at the armature attachment part.

Furthermore, as is clear from this embodiment, since the present invention has a fulcrum on the leaf spring, the leaf spring can be directly pressed by the spring means, and the slippage between the tip 223 of the spring means tongue piece and the spring 53 can be avoided. It is very small, and its wear and friction are negligible compared to the conventional invention or the fifth embodiment.

Wear of the fulcrum 151 affects the deflection amount and bias force of the leaf spring, as in the fourth embodiment. However, for the first to sixth embodiments, excluding the fourth embodiment,
A fulcrum is formed at the front edge of the fulcrum member 15, and even if wear of the front edge progresses toward the base of the leaf spring, the height of the front edge remains constant, so the fulcrum remains at the base of the leaf spring. This is equivalent to moving to the side. Therefore, at this time, L9 shown in FIG. 4 is longer than the initial setting value, and LS2 is shorter than the initial setting value. The former has the effect of decreasing the spring constant, and the latter has the effect of increasing the spring constant, and since these have the effect of canceling each other out, the influence of fulcrum wear is slight compared to the fourth embodiment.

In the sixth embodiment, the tongue piece extends inward from the center of the annular base of the spring means, but the tongue piece extends outside the base of the spring means, and the tip of the tongue piece of the spring means may be pressed against the fulcrum position of the plate spring effective elastic portion 53 to fix the base portion of the spring means to the printing rad casing.

[Seventh Embodiment] FIGS. 19 and 20 are drawings showing the seventh embodiment. FIG. 19 is a side view showing the main parts of the print head in cross section, and FIG. 20 is a side view showing the armature and plate. This is a perspective view showing main parts such as a spring.

In FIG. 19, the suction member 4 is configured to sandwich the film 25 and contact the core suction surface 82 with the entire surface of the suction surface 82. The film 25 is for preventing wear between the suction member 4 and the core suction surface 82, and has a thickness of, for example, 25.
A µm polyimide resin film is used. By doing this, the situation where the core of the suction member hits unevenly as shown in the first embodiment etc. is eliminated, and the wear resistance of the suction member and the core is improved. Furthermore, the average value of the gap between the attraction member and the core attraction surface can be reduced, and the magnetic attraction force is improved.

However, in this embodiment, the suction surface of the suction member and the plate spring mounting surface are no longer parallel, so there is a problem that it becomes difficult to maintain high positional accuracy.

Therefore, the leaf spring base portion 51 is divided into a common base portion 512 and an individual base portion 511, the tongue piece 52 is extended from the individual base portion, and an elastic portion 53 is formed in the tongue piece portion 52. The common base portion is formed with projections and depressions that guide and engage the individual base portions, thereby positioning the individual base portions. This leaf spring member
Similarly to the embodiments described above, the print head is formed by stacking and fixing other members in a laminated manner.

According to this embodiment, a leaf spring tongue piece is fixed to each armature. Therefore, in order to improve positional accuracy, the suction surface of the suction member can be ground individually using each leaf spring as a reference plane. The thickness of the common base portion 512 is as follows:
Because it is necessary to firmly fix the individual base portion 511 to the print head base, the individual base portion 5
It is better if the casing 132 is slightly thinner than 11, and the casing 132 is
It is better to have multi-core flexibility.

[Eighth Embodiment] FIG. 21 is a diagram showing an eighth embodiment of the present invention, showing a main part of printing in a perspective view. As shown in the moment distribution diagram in FIG. 4, the moment applied to the fulcrum is the largest. Therefore, as shown in FIG. 21, if the width of the leaf spring at the fulcrum part of the leaf spring effective elastic part 53 is made widest,
The stress applied to each part is more uniform than in the previous implementation, and if the spring constant is kept constant, the maximum value of stress is reduced, and reliability can be improved.

Alternatively, each part of the leaf spring can be adjusted by drilling a roughly diamond-shaped hole between the fulcrum and the fixed end of the effective elastic part of the leaf spring, such that the point where the static moment becomes O becomes the apex of the diamond. The stress becomes uniform and the maximum value of stress can be reduced.

〔Effect of the invention〕

321 According to the present invention, since the fulcrum is formed in the effective elastic part of the leaf spring, the stress of the leaf spring can be lowered compared to the conventional invention, and the print head can be made smaller (Prior art column ■).
It is possible to minimize wear on the fulcrum, which has traditionally been a problem with armature-supported print heads with a fulcrum structure, and improve reliability.

In addition, even if the center of impact of the armature does not necessarily coincide with the fulcrum, it is possible to maintain good return characteristics of the armature, and it is possible to operate at a higher speed than in the conventional technology (same column ■).

The present invention has the above-mentioned high speed and reliability, and because it assembles plate materials such as leaf spring members to the print head base in a laminated structure, it is easy to achieve positional accuracy and improve productivity (same column ■■
), it is possible to provide a high-responsive print head with good characteristics with little variation.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention, with FIG. 1 being a partial sectional view showing the overall structure of the print head, and FIG. 2 being a perspective view showing the main parts. FIG. 3 is a partial sectional view showing the embodiment of FIG. 2. FIG. 4 is a drawing showing the main parts and moment distribution of the first embodiment, and FIG. 5 is a drawing showing its effect. FIGS. 6 and 7 are diagrams showing operating waveforms in the first and second embodiments. FIG. 8 is a drawing schematically showing the operations of FIGS. 6 and 7 in a side view showing a main part of the print head partially in section. Figures 9 and 10 are
Drawings showing dynamic characteristics in the third embodiment, and the first
FIG. 1 is a diagram schematically showing the operation similar to FIG. 8. FIG. 12 is a side view showing a main part of the print head partially in section, showing a fourth embodiment. FIGS. 18 and 14 show a fifth embodiment in which the main part of the print head is shown in cross section. 15 to 17 show a sixth embodiment of the present invention, FIG. 15 is a side view schematically showing the main parts, and FIG. 16 is a diagram showing the overall structure of the print head. FIG. 17, which is a side view shown in a partial cross section, is a drawing showing a main part in a perspective view. FIG. 18 shows the operating characteristics of the embodiment of FIG. FIGS. 19 and 20 show a seventh embodiment, in which FIG. 19 is a side view showing a main part partially in section, and FIG. 20 is a perspective view. FIG. 21 shows the eighth embodiment, and is a perspective view of the main parts. FIG. 22 is a diagram showing operating waveforms of the prior art for comparison with the operating waveforms of FIG. 6. Explanation of symbols 1... Armature, 2... Printing wire,
4... Suction member, S... Leaf spring, 8...
Core, 15... Fulcrum forming member, 20...
...printing medium, 22...spring means, 51...
- Leaf spring base, 52... Leaf spring tongue piece, 53...
- Leaf spring effective elastic part, 151... Fulcrum, 222... Tongue piece, 223... Projection part.

Claims (1)

[Claims] 1. For a leaf spring body constituted by a plurality of tongue pieces from a base made of a plate material having an annular shape, regularly adjoining each other and extending toward the center of the base. , each of a plurality of armatures having a printing wire fixed to the tip thereof is fixed on the extension side of each tongue, and the effective elastic portion of the tongue is deflected by attracting the suction member of the armature by the magnetic attraction force of the permanent magnet. In the print head that drives the armature toward the printing medium by the biasing force of the leaf spring, the magnetic attraction force is canceled by applying current to the electromagnetic coil, and a fulcrum that contacts the effective elastic part of the leaf spring is printed. A high-speed print head with a fulcrum structure, which is characterized by being installed on the head base. 2. A high-speed printing head with a fulcrum structure according to claim 1, characterized in that the center of impact of the armature is substantially aligned with the fulcrum. 3. In claim 1, facing the fulcrum,
A high-speed print head with a fulcrum structure, which has a spring member that presses the armature toward the fulcrum from the opposite side of the armature. 4. In claim 1, facing the fulcrum,
A fulcrum structure high-speed print head having a spring member that presses the leaf spring effective elastic portion as a fulcrum from a side opposite to the fulcrum of the leaf spring effective elastic portion. 5. In claim 1, the spring member has a shape in which a plurality of tongues extend adjacent to each other from the base, and a supporting point in which the tip of the tongue of the spring member presses the leaf spring elastic part. Structure high speed print head. 6. In claim 1, the base part of the leaf spring body is divided into a continuous common base part and individual base parts integrally formed with the plurality of tongue pieces, and the common base part A high-speed print head with a fulcrum structure in which the individual base portions are guided and engaged with the formed uneven portions to form a leaf spring member. 7. The high-speed print head with a fulcrum structure according to claim 1, wherein the width of the leaf spring elastic portion that contacts the fulcrum is substantially widest at the fulcrum.