JPH05185612A - Wire dot printing head - Google Patents

Abstract

PURPOSE:To make the title head into structure through which minaturization and low pricing are possible and a high-speed and high-printing energy are obtained. CONSTITUTION:The title printing head is comprised by interposing a spacer 5 constituted of an annular outside spacer 5A formed of a magnetic substance through which magnetic flux of a permanent 7 passes and an annular inside spacer 5B which is formed of a nonmagnetic substance and arranged on the inside of the outside spacer 5A between a leaf spring 4 for bias and the permanent magnet 7 and a tonguelike projected piece which is extended up to a position becoming a turning fulcrum of an armature 13 in an air gap between the left spring 4 for bias and a subcore 23 and arranged under an eliminated state of the air gap is provided on the inside spacer 5B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a wire dot print head in a serial printer.

[0002]

2. Description of the Related Art Conventionally, an impact printer which drives a print wire, impacts a print medium through an ink ribbon, and prints by the force has a high degree of freedom in the print medium and is relatively inexpensive. It is used in various fields including output devices such as processing systems. In addition, this impact printer has a plunger type, spring charge type,
There is a clapper type. Among them, in the spring charge type, an armature to which a print wire is fixed is swingably supported by a bias leaf spring, and this armature is resisted against the elastic force of the bias leaf spring by the magnetic flux of a permanent magnet. The structure is such that it is attracted to the core side, and when printing, the coil wound around the core is excited and a magnetic flux is generated in this coil in a direction opposite to that of the permanent magnet, and the armature is released. .. In recent years, this spring-charged wire dot print head has been widely used because of its high-speed response.

FIG. 9 is a side view showing an example of a conventionally known wire dot type print head with a half side sectioned. In the figure, this print head 51 is a spring charge type print head, and includes a guide frame 52, an armature yoke 53, a bias leaf spring 54, and a magnetic spacer 5.
5, magnet yoke 56, permanent magnet 57, yoke 5
8, base yoke 59, printed circuit board 60, guide nose 61, dot wire 62 for printing, armature 6
3, a coil assembly 71 including a wire guide 64, a fin 65, a clamp spring 66, a degaussing exciting coil 68 wound around a bobbin 67, a bar-shaped core 69 having a trapezoidal cross section, and a pair of terminals 70, etc. It is composed of.

The print head 51 is driven by turning on / off the current to the exciting coil 68. When the printing is not performed, the current to the exciting coil 68 is cut off (off), and the current is passed when the printing is performed. (On) is set. That is, in the non-printing state in which the exciting coil 68 is not energized, the magnetic flux of the permanent magnet 57 is
The yoke 58, the base yoke 59, the core 69, the bias leaf spring 54, the armature 63, and the armature yoke 5.
3, the magnetic spacer 55, the magnet yoke 56, and the permanent magnet 57. Further, the magnetic attraction force generated at this time causes the armature 63 to be attracted to the core 69 while displacing the biasing leaf spring 54, whereby the entire dot wire 62 is pulled inside the guide frame 52. On the other hand, when a current is passed through the exciting coil 68 for excitation, a magnetic flux opposite to the magnetic flux of the permanent magnet 57 is generated in the core 69. As a result, the magnetic flux of the permanent magnet 57 is canceled out, and the bias leaf spring 54 that is attracted to the core 69 in a biased state is released. Then, the elastic reaction force of the bias leaf spring 54 causes the armature 6 to move.
3 rotates about this other end to the platen side (not shown), and the dot wire 62 attached to the free end instantly projects. Then, the projected dot wire 62 impacts a print medium (not shown) via an ink ribbon (not shown), and printing is performed. Also, the armature 63
After once releasing, the excitation coil 68 is de-energized again, and the armature 63 is adsorbed and held on the core 69 side together with the dot wire 62 that has returned after impacting the print medium. Therefore, when this operation is selected for each of the plurality of dot wires 62 and is performed while moving the print head 51 in the row direction, characters and graphic patterns having dot configurations are printed on the print medium.

FIG. 10 is a side view showing another example of a conventionally known wire dot type print head with its half side sectioned. In FIG. 10, the same reference numerals as those in FIG. 9 denote the same parts as those in FIG. In the print head 81, the yoke 82 extends from the base yoke 59.
And the sub core 83 are integrally formed.

FIG. 11 shows the print head 81 shown in FIG.
FIG. Therefore, the main part of the print head 81 will be further described with reference to FIG. 11. The bias plate spring 54 includes two spring effective parts 54a and 54a and a front end side fixing part 54b and a rear end side for fixing the armature 63. The fixed portion 54c and the armature yoke 53 on the base end side.
And an outer edge portion 54d fixed to the magnetic spacer 55 and the like integrally. The armature 63 is fixedly attached to the bias leaf spring 54 so as to abut on the bias leaf spring 54 while straddling the front end side fixed portion 54b and the rear end side fixed portion 54c.
And a lever portion 63b which is extended from one end of the fixing portion 63a and has the dot wire 62 fixed to the tip portion thereof, which are integrally provided.
The fixing portion 63a and the bias leaf spring 54 are fixed by welding. The magnetic spacer 55 has a base end portion 55 corresponding to the base end portions of the spring effective portions 54a, 54a of the bias leaf spring 54.
a, 55a and the outer edge portion 54d of the bias leaf spring 54,
And an outer edge portion 55 fixed to the magnet yoke 56 and the like.
and b together. Also, this magnetic spacer 55
Then, the gap between the base end portions 55a, 55a is formed larger than the width dimension of the fixed portion 63a of the armature 63,
It is in a state where it does not hinder the movement of the armature 63. The armature yoke 53 has a groove portion 84 for receiving the armature 63 with a small gap, and the outer edge portion 5
3a is fixed to the outer edge portion 54d of the bias leaf spring 54. The base 59 has a stepped shape in which the tip of the sub-core 83 is arranged so as to face the rear end side fixed portion 54 c of the bias leaf spring 54, and the magnetic spacer 55 is avoided. The height of the upper end surface 83a of the sub core 83 is substantially the same as the upper surface of the magnet yoke 56 and the upper surface 69a of the core 69 which are attached to the yoke 82 via the permanent magnets 57. The gap between the leaf spring 54 and the rear end side fixed portion 54c is formed to be substantially the same as the gap of the magnetic spacer 55.

FIG. 12 is a diagram showing the flow of magnetic flux in the print head 81. Therefore, the operation of the print head shown in FIGS. 10 and 11 will be described with reference to FIG. First, the print head 81 is driven by turning on / off the current to the exciting coil 68. When the printing is not performed, the current to the exciting coil 68 is cut off (off), and when the printing is performed, the current is passed (on. ) Is configured as. Then, in the non-printing state in which the energizing coil 68 is not energized, the magnetic flux generated from the N pole of the permanent magnet 57 leaks to the outer periphery from the portion a shown in FIG. 12, and the rest is the yoke 82 and the base yoke 59. Through, and is further branched into a sub-core 83 and a core 69 at a portion indicated by reference sign b.
Then, the magnetic flux flowing in the sub core 83 is further branched at the point c, and the bias leaf spring 54 and the sub core 83 are provided on one side.
The bias leaf spring 54 passes through the space e between
And flows toward the armature 63 side to attract the bias leaf spring 54 and the armature 63, and the other side returns to the permanent magnet 57. On the other hand, the magnetic flux flowing through the core 69 passes through the portion d and the core 69 and the bias leaf spring 54.
It flows to the bias leaf spring 54 and the armature 63 through the air gap f between and. Then, the bias leaf spring 54 and the armature 63 are attracted, and further merge with the magnetic flux that has passed through the inside of the armature 63 and passed through the sub core 83 at the portion indicated by the reference sign g, and passes through the void h to further wet the portion i. It merges with the magnetic flux and returns to the S pole of the permanent magnet 57. Therefore, in this state, the armature 6 is magnetically attracted to the sub-core 83 and the core 69.
3 and the bias leaf spring 54 are biased to the core 69 side, and the entire dot wire 62 is pulled inside the guide frame 22.

On the other hand, when a current is passed through the exciting coil 68 for excitation, a magnetic flux opposite to the magnetic flux of the permanent magnet 57 is generated in the core 69. As a result, the magnetic flux of the permanent magnet 57 is canceled and the bias leaf spring 54, which is attracted to the sub core 83 and the core 69 in a biased state, is released. Then, the elastic reaction force of the bias leaf spring 54 causes the armature 63 to rotate around this other end toward the platen (not shown), and the dot wire 62 attached to the free end is instantly projected. Then, the projected dot wire 62 impacts a print medium (not shown) via an ink ribbon (not shown), and printing is performed. Further, after the armature 63 is once released, the excitation coil 68 is de-energized again, and the armature 63 is adsorbed and held by the sub-core 83 and the core 69 side together with the dot wire 62 returning after impacting the print medium. Therefore, this operation is selected for each of the plurality of dot wires 62, and the print head 5
When 1 is performed while moving in the line direction, characters and graphic patterns having dot configurations are printed on the print medium.

Next, considering the ease of flow of magnetic flux in the print head 81 as the relative magnetic permeability, iron is about 3400, permanent magnet 57 is about 1, and air is 1, so in FIG. , F portion, g portion and the permanent magnet 57 are the main causes of preventing the magnetic flux generated in the exciting coil 68.

Therefore, the flow of the magnetic flux shown in FIG.
3 and FIGS. 14 (a) and 14 (b) are represented as an equivalent circuit, and when the difficulty as the magnetic flux is viewed as the magnetic resistance,
The magnetic resistances in the voids e, f, g and the permanent magnet 57 are represented by R1, R2, R in FIGS.
3 and R4 respectively. Magnetic resistance R1 here
R4 is inversely proportional to the magnetic permeability and the area of the void, and is also proportional to the length of the void. Here, assuming that the total amount of magnetic flux generated by the permanent magnet 57 is NI1, the magnetic flux flowing when attracting the core 69 and the sub-core 83 is equivalent to the currents i1 and i2 in FIGS. 14 (a) and 14 (b). expressed. Further, as shown in FIG. 14B, the magnetic flux NI2 generated from the exciting coil 68 when the exciting coil 68 is energized is
9 and currents i3 and i4 of the sub core 83. Further, the magnetic fluxes of the core 69 and the sub-core 83 are superposed and become (i1-i3), (i2 + i4), and the core 6
The magnetic flux (i1-i3) flowing in 9 approaches 0 sooner as more magnetic flux i3 flows with respect to the magnetomotive force NI2 of the exciting coil 68. Therefore, it is better that the combined resistance in the equivalent circuit of FIG. 14B is smaller, and the magnetic resistance R4 becomes smaller by including the sub-core 83, so that the total combined resistance becomes smaller.
The magnetic flux flowing through the core 69 can be canceled with a small magnetomotive force NI2. As a result, the print head 5 shown in FIG.
It can be understood that the print head 81 shown in FIG. 10 can release the bias leaf spring 54 with a smaller current than that of the print head 81, and the power consumption can be reduced.

FIGS. 15A and 15B show a print head 81.
In the above, the armature 63 and the bias leaf spring 5 when attracted by the core 69 and the sub core 83
4 shows the operating state of No. 4. In the print head 81, the armature 63 has a core 69 and a sub core 83.
When it is sucked into, sinking occurs. In this case, FIG.
As shown in (a), when the armature 63 is pulled by the core 69 and the sub-core 83, the bias leaf spring 54 to which the armature 63 is attached is displaced by the dimension G at a point separated from the fixed end by the dimension L1. , Armature 63
Rotates about a point separated from the fixed end by the dimension L2. However, due to the attractive force generated by the magnetic flux flowing from the core 69 and the sub core 83, a moment is generated around the point A. Then, due to this force,
As shown in (b), the bias leaf spring 54 deforms and the armature 63 sinks, and this sinking causes the armature 63 to rotate about a position separated from the fixed end by a dimension L3.

FIG. 16 is a diagram showing the movement of the biasing leaf spring 54 in the print head 81. The left side is a perspective view and the right side is a sectional view. The movement of the bias leaf spring 54 here is the state in which the bias leaf spring 54 and the armature 63 are not vibrated in the same figure (a), and the armature 63 is rotated clockwise in the same figure (b). In the basic vibration mode state, the armature 63 of FIG. 7C is rotated counterclockwise to a higher order (2
Next, it is explained by the sum of vibration mode states.

17A and 17B show the displacement amount G and the vibration speed V of the bias leaf spring 54 in the print head 81 together with the change in time (T). 16B, the vertical axis represents the displacement (G) at the point A shown in FIG. 16, the horizontal axis represents time (T), the vertical axis in FIG. 17B represents the velocity (V), and the horizontal axis represents the time (T). T) is shown. The waveform shown by the solid line in FIG. 17A shows the vibration waveform of the mode in FIG. 16B at the point A in FIG. 16, and the movement when the bias leaf spring 54 is released is It is indicated by a dotted line. Here, originally,
Since the bias leaf spring 54 operates only in the dotted line portion in FIGS. 17 (a) and 17 (b), when it is displaced by a certain displacement amount G millimeter (mm), it is possible to operate it in time T1 seconds. It takes time T2 seconds, and the speed V is originally the speed V
What becomes 1 will increase only to the speed V2. Further, the printing energy E at this time is E = 1/2 mV ² from the equivalent mass m of the bias leaf spring 54 and the armature 63 and the speed V at the time of printing. Therefore, when the speed is slow, the printing energy becomes small. Therefore, in the efficiency of printing energy / input energy when releasing the same bias leaf spring 54,
Originally, the spring strain energy of the bias leaf spring 54 is not fully used as printing energy, resulting in poor efficiency.

FIG. 18 shows an example in which a fulcrum spring is used as the bias leaf spring 54 in the print head 81. Here, the armature 63 and the bias leaf spring 54 are used to form the bias leaf spring 5.
It is designed to be operated by a high-order (second-order) vibration of No. 4. When this fulcrum spring is used, superposition of vibrations is eliminated, and the efficiency of printing energy / input energy is improved. However, when the print head 81 is downsized, when the bias leaf spring 54 is made smaller, stress concentrates on the deformed portion of the bias leaf spring 54,
The bias leaf spring 54 is broken, which is not suitable for downsizing and cost reduction.

Therefore, in the print head for the purpose of downsizing and cost reduction, in order to effectively convert the spring strain energy into the printing energy, the bias leaf spring 54 as shown in FIG. 15B is used. It is necessary to eliminate the sinking of the armature 63 due to the secondary vibration and to operate by the basic vibration of the bias leaf spring 54 as shown in FIG.

[0016]

However, as shown in FIG. 15 (a), when the bias leaf spring 54 is to be operated by the fundamental vibration, the dimension L2 is larger than the fixed end of FIG. 15 (a). If the fulcrum of the armature 63 is attached to the lower side at a distance (hereinafter, this position is called the "center of rotation"),
The problem as shown in FIG. 19 arises. That is, FIG.
(A) is a cross section of the print head 81 and the permanent magnet 57.
19B is a magnetic flux generated by the magnetic head 55. When the magnetic spacer 55 is extended to the "rotation center" of the armature 63 with respect to the print head 81, FIG. It is used as a spacer. Among them, in the case of FIG. 19A, similarly to the case described with reference to FIG. 12, there is a problem that the efficiency cannot be effectively used as the spring strain energy of the bias leaf spring 54 and the efficiency is deteriorated. On the other hand, in the case of FIG.
The void of the void portion e existing in the structure shown in FIG. 19A disappears. Therefore, the magnetic flux easily flows, and the sub core 83
The magnetic flux flowing through the core 69 increases, which reduces the magnetic flux flowing through the core 69. That is, the bias leaf spring 5
The root of No. 4 is strongly attracted, but the tip is only slightly attracted, so the attraction force of the entire bias leaf spring 54 is reduced, and only the bias leaf spring 54 having a weak spring constant can be attracted. there were. On the other hand, FIG.
In the case of (c), a non-magnetic material is used as the magnetic spacer 55, but the magnetic flux shown by the dotted line in FIG. 19B, that is, the magnetic flux that has passed through the bias leaf spring 54 and the armature 63 flows. I will not be able to. For this reason,
There is a problem that only the leakage magnetic flux that does not contribute to the attraction force of the bias leaf spring 54 increases, and the bias leaf spring 54 cannot be attracted.

Therefore, in the conventional print head, when the bias leaf spring 54 is operated, the bias leaf spring 5 is used.
Due to the higher-order vibration component generated in 4, the bias leaf spring 5
4 and the armature 63 have a problem in that the printing speed is reduced, and it is difficult to downsize. The problem of poor energy conversion efficiency due to sinking of the armature similarly occurs in the print head having no sub-core shown in FIG. 9 due to the magnetic flux flowing from the core.

The present invention has been made in view of the above problems, and an object thereof is to provide a wire dot print head having a structure that can be downsized and reduced in cost, and that can obtain high speed and high printing energy. Especially.

[0019]

In order to achieve the above object, a wire dot printing head according to the first invention comprises a pair of main and sub cores magnetized by a permanent magnet, and an armature to which the dot printing wire is attached. It is attracted against the biasing force of the leaf spring for bias, the magnetic flux of the exciting coil mounted around the main core cancels the magnetic flux of the permanent magnet to release the armature, and the dot wire is projected to print. The bias leaf spring is a spacer formed of a ring-shaped outer spacer made of a magnetic material and a ring-shaped inner spacer formed of a non-magnetic material and arranged inside the outer spacer. And the permanent magnet, and at the inner spacer, the armature of the armature in the gap between the bias leaf spring and the sub core is provided. Is extended until the rolling as a fulcrum position,
The tongue-shaped protruding piece is provided in a state where the void is eliminated.

In the wire dot print head according to the second aspect of the present invention, the core magnetized by the permanent magnet is used to rotate the armature to which the dot wire is attached against the biasing force of the bias leaf spring to attract the armature. The magnetic flux of the exciting coil mounted around the core cancels the magnetic flux of the permanent magnet to release the armature, and the dot wire is projected to perform printing, and the bias leaf spring is used. A spacer, which is arranged in a ring shape on the opposite side of the armature and has a first tongue-shaped protruding piece protruding to the position of the rotation fulcrum of the armature, and a ring shape is arranged on the opposite side of the bias leaf spring with respect to the spacer. And a yoke having a second tongue-shaped projecting piece for preventing the first tongue-shaped projecting piece from bending.

[0021]

According to the first construction, the protruding piece of the inner spacer is arranged in the gap between the bias leaf spring and the sub core, and the bias leaf spring corresponding to the portion serving as the rotation fulcrum of the armature is provided. Since the parts are arranged in contact with each other, when released, the lower side of the bias leaf spring is rotationally moved in contact with the protruding piece, and the bias leaf spring and the armature may not sink. It becomes possible to move with the basic component. Therefore, the bias leaf spring and the armature can be reliably moved and printed in a short time, so that the printing time can be shortened. In addition, the magnetic flux that has passed through the bias leaf spring and armature returns to the permanent magnet side through the outer peripheral spacer, and the leakage flux that tries to return from the sub core to the permanent magnet side without passing through the bias leaf spring and armature causes Since the spacer is made of a non-magnetic material, the number of spacers is reduced, and the magnetic flux that contributes to the attraction force of the bias leaf spring is increased.

According to the second structure, the first tongue-shaped protruding piece of the spacer is arranged in contact with the bias leaf spring to a position corresponding to the rotation fulcrum of the armature. At the time of releasing, the bias leaf spring rotates while being in contact with the first projecting piece, and the bias leaf spring and the armature do not sink. At this time, the second tongue-shaped protruding piece of the yoke prevents the first tongue-shaped protruding piece from bending. Since the shape of the second tongue-shaped protruding piece is a tongue shape having a narrow width, the magnetic flux flowing from the core to the yoke is small.

[0023]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an overall side view showing a left half of a wire dot type print head according to a first embodiment of the present invention. In the figure, the print head 1 is a spring charge type print head, and includes a guide frame 2, an armature yoke 3, a bias leaf spring 4, a spacer 5, a magnet yoke 6, a permanent magnet 7, a yoke 24, a base yoke 9, and a print. A substrate 10, a guide nose 11, a dot wire 12 for printing, an armature 13, a wire guide 14, a fin 15, a clamp spring 16, an exciting coil 18 for degaussing wound around a bobbin 17, and a rod-shaped trapezoidal section. The coil assembly 21 is composed of a core 19 and a pair of terminals 20, and the like.

FIG. 2 is an exploded perspective view of the main part of the print head 1 shown in FIG. Therefore, referring to FIG. 2, the print head 1
To further explain the main part of the bias leaf spring 4,
Two spring effective portions 4a, 4a, a front end side fixed portion 4b and a rear end side fixed portion 4c for fixing the armature 13, and an outer edge portion 4d fixed to the armature yoke 3 and the spacer 5 at the base end side are integrally formed. Has been formed. The armature 13 includes a front end side fixing portion 4b and a rear end side fixing portion 4c.
The fixing portion 13a which is disposed in contact with the leaf spring 4 for bias in a state of straddling and the lever portion 13b which extends from one end of the fixing portion 13a and fixes the dot wire 12 to the tip portion thereof are integrated. The fixing portion 13a and the bias leaf spring 4 are welded and fixed. The spacer 5 is
A ring-shaped magnetic outer spacer 5A made of a magnetic substance metal (see FIG. 4), and a tongue-shaped protruding piece 8 which is a part of the outer spacer 5A and is disposed inside the outer spacer 5A and extends toward the center side. And a ring-shaped non-magnetic inner spacer 5B (see FIG. 5) made of a non-magnetic substance metal. In addition, the outer spacer 5A and the inner spacer 5B are provided with engagement recesses 31A and 31B, which are engaged with the knock pin 29 (see FIG. 7) and positioned with respect to each other. The outer spacer 5A and the inner spacer 5B are fixed to the outer edge portion 4d of the bias leaf spring 4, respectively. Further, the positional relationship between the protruding piece 8 of the inner spacer 5B, the armature 13 and the bias leaf spring 4d when fixed is as shown in FIG. The yoke base 9 is formed by integrally forming the yoke 24 and the sub core 23, and the front end of the sub core 23 as the sub core is arranged so as to face the rear end side fixing portion 4c of the bias leaf spring 4. The height of the upper end surface 23a of the sub-core 23 is the upper surface of the magnet yoke 6 attached to the yoke 24 via the permanent magnet 7 and the core 19 as the main core.
The upper surface 9a is substantially the same as the upper surface 9a, and the gap between the upper end surface 23a of the sub core 23 and the rear end side fixing portion 4c of the bias leaf spring 4 is formed to be substantially the same as the spacer 5. However, the upper end surface 23a and the rear end side fixed portion 4c of the bias leaf spring 4 are fixed.
The gap between and disappears when the protruding piece 8 of the inner spacer 5B is extended to the position that serves as the fulcrum of rotation of the armature 13, and is assembled in that state.

Therefore, in the bias leaf spring 4 and the armature yoke 3 of the print head 1, the armature 13 is pulled by the core 19 and the sub-core 23 as described later, and the bias leaf spring to which the armature 13 is attached is attached. When 4 is displaced by the dimension G at a point separated from the fixed end by the dimension L1, the armature 13 rotates about the tip of the projecting piece 8 separated from the fixed end by the dimension L2. As a result, the spring constant of the bias leaf spring 4 remains the same, and at the time of attraction, the bias leaf spring 4 is attracted around the rotation center H (see FIG. 3) as a fulcrum without generating a higher-order vibration component, and thus is released. It becomes possible to move by the fundamental vibration component at the time.

FIG. 6 is a diagram showing the flow of magnetic flux in the print head 1. Therefore, the operation of the print head 1 shown in FIG. 1 will be described with reference to FIG. First, the print head 1 configured as described above is driven by turning on / off the current to the exciting coil 18, and when the printing is not performed, the current to the exciting coil 18 is cut off (off), and the current is applied when the printing is performed. Is configured to flow (on). Then, in the non-printing state in which the excitation coil 18 is not energized,
The magnetic flux generated from the N pole of the permanent magnet 7 leaks to the outer periphery from the portion a shown in FIG. 6 and the rest flows through the yoke 24 and the base yoke 9.
3, branch to the core 19. Then, the magnetic flux flowing in the sub-core 23 is further branched at a point c, and the protruding piece 8 of the inner spacer 5B made of a non-magnetic substance in the space e between the bias leaf spring 4 and the sub-core 23 is formed on one side. Bias leaf spring 4 and armature 1
3, the bias leaf spring 4 and the armature 13 are attracted, but the other side returns to the permanent magnet 7. On the other hand, the magnetic flux flowing through the core 19 flows through the gap f between the core 19 and the bias leaf spring 4 into the bias leaf spring 4 and the armature 13. Then, the bias leaf spring 4 and the armature 13 are attracted, and the magnetic flux that has passed through the inside of the armature 13 and passed through the sub-core 23 at the portion g is merged with the symbol i.
The magnetic flux merges with the leakage magnetic flux at a portion and returns to the S pole of the permanent magnet 7 through the outer spacer 5A made of a magnetic material. Therefore, in this state, the armature 13 and the leaf spring 4 for biasing are biased to the core 19 side by the magnetic attraction to the sub-core 23 and the core 19 side, and the entire dot wire 12 is drawn inside the guide frame 2. Is in a state.

On the other hand, when a current is passed through the exciting coil 18 for excitation, a magnetic flux opposite to the magnetic flux of the permanent magnet 7 is generated in the core 19. As a result, the magnetic flux of the magnet permanent magnet 7 is canceled out, and the bias leaf spring 4 that is attracted to the sub-core 23 and the core 19 in a biased state is released.
Then, the elastic reaction force of the bias leaf spring 4 causes the armature 13 to rotate around the other end toward the platen (not shown), and the dot wire 12 attached to the free end is instantly projected. And this protruding dot wire 12
A printing medium (not shown) is also impacted via an ink ribbon (not shown) to perform printing. Further, after the armature 13 is once released, the excitation coil 18 is de-energized again, and the armature 13 is adsorbed and held by the sub-core 23 and the core 19 side together with the dot wire 12 that has returned after impacting the print medium. Therefore, when this operation is selected for each of the plurality of dot wires 12 and is performed while moving the print head 1 in the row direction, characters and graphic patterns having dot configurations are printed on the print medium.

FIG. 8 shows experimental data of the speed waveform of the wire portion in the conventional print head 81 shown in FIG. 10 and the print head 1 according to the embodiment. The horizontal axis represents time and the vertical axis represents the speed of the dot wire 12. Is shown as printing energy. As can be seen from this figure, by applying the voltage shown by the one-dot chain line to the exciting coil (18, 68), the dot wire 62 in the conventional print head 81 changed at the speed of the dotted line, but in the present embodiment, According to the example, the speed change is indicated by the solid line. That is, since the time required for printing, which is the rise time, is shortened, and the speed is increased, the printing energy is also increased according to 1/2 mV ² . The peak value of the two-dot chain line waveform in FIG. 8 is a value representing the size of the printing energy according to this embodiment, which is about 1.4 times the value of the three-dot chain line representing the conventional printing energy. Is becoming Further, the time until printing, that is, the return time is also about 0.8 times faster, and it can be seen that high-speed and high-printing energy can be achieved even if the input energy is the same.

Therefore, according to the print head 1 of this embodiment, the protruding piece 8 of the inner space 5B formed of a non-magnetic material is used to rotate the armature 13 so as not to affect the flow of the magnetic flux of the print head 1. Since it is provided so as to extend to the center, compared with the conventional print head, even when the bias leaf spring 4 is released, the same input energy causes the spring speed of the bias leaf spring 4 to increase, increasing the printing energy and the printing time. It is possible to shorten and increase the repetition speed.

Next, a second embodiment according to the present invention will be described with reference to FIG. FIG. 20 is an exploded perspective view showing a main part of the second embodiment according to the present invention. 20, the print head 91 according to the second embodiment is the print head 5 shown in FIG.
As in the case of No. 1, it does not have a sub-core, and has a structure in which the armature 13 is sucked only by the core 19. A tongue-shaped protruding piece 93 extending toward the center side is formed on the spacer 92 arranged below the bias leaf spring 4. The tongue-shaped protruding piece 93 is formed of a magnetic material, and its width is dimensioned so as not to interfere with the effective portion 4a of the bias leaf spring 4. The tip portion 93a of the tongue-shaped protruding piece 93 is aligned with the position corresponding to the rotation fulcrum of the armature 13 as in the tongue-shaped protruding piece 8 of the first embodiment.

The magnet yoke 94 also has a spacer 92.
A tongue-shaped protruding piece 95 is also formed on the lower portion of the tongue-shaped protruding piece 93. The tip 95a of the protruding portion 95 extends to a position near the rotation fulcrum of the armature 13. The magnet 7, the yoke 58, and the base 59 are sequentially arranged below the magnet yoke 94, and only the core 19 is arranged inside the base 59. The structure and arrangement of the armature yoke 3, the armature 13 and the bias leaf spring 4 are the same as in the first embodiment.

In the second embodiment, the tongue-shaped protruding piece 93 of the spacer 92 holds down the rotation fulcrum of the armature 13. At this time, the protruding piece 95 of the magnet yoke 94 is held.
Reinforces the tongue-shaped protruding piece 93. As a result, the sinking of the armature 13 at the rotation fulcrum can be almost eliminated. Further, since the protruding piece 95 is tongue-shaped and has a narrow width, magnetic saturation is likely to occur, the leakage of magnetic flux from the core 19 to the magnet yoke 94 is small, and the attraction force for attracting the armature 13 to the core 19 is sufficient. Secured.

FIG. 21 is an exploded perspective view showing the main part of the wire dot print head according to the third embodiment of the present invention. Third
In the print head 101 of the embodiment, a rotation fulcrum pressing portion 103 that presses the rotation fulcrum of the armature 13 is provided in the center portion inside the spacer 102, and half etching portions 104 are provided on both sides thereof. The half-etched portion 104 is etched to the extent that the effective portion 4a of the bias leaf spring 4 does not interfere. Further, tongue-shaped protruding pieces 106 are formed on both inner ends of the magnet yoke 105, and both protruding pieces 106 are arranged so as to be located outside the effective portion 4 a of the leaf spring 4. The other structure is similar to that of the second embodiment.

In the third embodiment having the above structure, the second
Compared to the embodiment, the core 19 and the magnet yoke 105
Since the gap between the core 19 and the magnet is expanded, the leakage of the magnetic flux from the core 19 to the magnet yoke 105 is further reduced.

[0035]

As described above, according to the wire dot type print head according to the present invention, the protruding piece of the inner spacer is arranged in the space between the bias leaf spring and the sub core, and the armature rotation fulcrum. Since the portion of the bias leaf spring corresponding to the portion to be arranged is abutted, the lower side of the bias leaf spring is rotationally moved in a state of abutting the protruding piece at the time of release, The biasing leaf spring and armature do not subside and are allowed to move with the basic component. Therefore, the bias leaf spring and the armature can be reliably moved and printed in a short time, so that the printing time can be shortened. In addition, the magnetic flux that has passed through the bias leaf spring and armature returns to the permanent magnet side through the outer peripheral spacer, and the leakage flux that tries to return from the sub core to the permanent magnet side without passing through the bias leaf spring and armature causes Since the spacer is made of a non-magnetic material, the number of spacers is reduced, and the magnetic flux that contributes to the attraction force of the bias leaf spring is increased. Therefore, printing energy can be effectively used even with a small one, so that a small size and a low price are possible. In addition, in a print head that does not have a sub-core, since the tongue-shaped protruding piece is provided on the spacer and the magnet yoke located below it, the bias leaf spring and armature do not sink, and the armature can operate with the basic components. It will be possible. By narrowing the width of the tongue-shaped protruding piece of the magnet yoke, the leakage of magnetic flux from the core to the magnet yoke is small, and the attractive force of the armature is not reduced.

[Brief description of drawings]

FIG. 1 is an overall side view showing a left half of a wire dot type print head according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of essential parts of the wire dot type print head shown in FIG.

FIG. 3 is an explanatory view of an operation of a main part of the wire dot type print head shown in FIG.

FIG. 4 is a view of a single outer spacer of the wire dot type print head shown in FIG.

FIG. 5 is a view of a single inner spacer of the wire dot type print head shown in FIG.

FIG. 6 is a diagram for explaining the flow of magnetic flux in the wire dot type print head shown in FIG.

7 is a diagram showing a positional relationship between a spacer, a leaf spring for bias, and an armature in the wire dot type print head shown in FIG.

FIG. 8 is a characteristic diagram showing the print energy of the wire dot type print head shown in FIG. 1 and the print energy of the conventional wire dot type print head based on experimental data.

FIG. 9 is a side view showing an example of a conventional wire dot type print head with a half side sectioned.

FIG. 10 is a side view showing another example of a conventional wire dot type print head with a half side sectioned.

11 is an exploded perspective view of essential parts of the wire dot type print head shown in FIG.

FIG. 12 is a diagram for explaining the flow of magnetic flux in the wire dot type print head shown in FIG.

13 is an equivalent circuit diagram of the flow of magnetic flux in the wire dot type print head shown in FIG.

FIG. 14 is an equivalent circuit further simplifying the equivalent circuit shown in FIG. 13 and showing the non-energized state and the energized state of the exciting coil, respectively.

FIG. 15 is an explanatory view of an essential part operation of the wire dot type print head shown in FIG.

16 is an operation state diagram of the armature in the wire dot type print head shown in FIG.

17 is an operation waveform diagram of an armature in the wire dot type print head shown in FIG.

18 is a diagram schematically showing an example of a case where a fulcrum spring is used in the wire dot type print head shown in FIG.

FIG. 19 is a diagram for explaining a problem of the conventional wire dot type print head.

FIG. 20 is an exploded perspective view of essential parts of a wire dot type print head according to a second embodiment of the present invention.

FIG. 21 is an exploded perspective view of essential parts of a wire dot type print head according to a third embodiment of the present invention.

[Explanation of symbols]

 1 Printing Head 4 Bias Leaf Spring 5 Spacer 5A Outer Spacer 5B Inner Spacer 7 Permanent Magnet 8 Projecting Piece 12 Dot Wire 13 Armature 18 Excitation Coil 19 Core (Main Core) 23 Sub Core (Sub Core) 93 Tongue Projecting Piece 95 Tongue Shape Protruding piece

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayuki Ishikawa 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Koichi Ando 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (2)

[Claims] 1. A pair of main and sub cores magnetized by a permanent magnet to attract an armature to which a dot wire is attached against a biasing force of a leaf spring for biasing, and an excitation attached around the main core. In the wire dot print head that cancels the magnetic flux of the permanent magnet with the magnetic flux of the coil to release the armature and projects the dot wire for printing, a ring-shaped outer spacer made of a magnetic material and a non-magnetic material are used. A spacer formed of a ring-shaped inner spacer arranged inside the outer spacer is interposed between the bias leaf spring and the permanent magnet. The armature is extended in a space between the leaf spring and the sub-core to a position serving as a pivotal fulcrum, and is arranged in a state where the space is eliminated. Wire dot stamp head is characterized in that a Jo protruding piece. 2. A core magnetized with a permanent magnet, wherein an armature having a dot wire attached thereto is rotated and attracted against the biasing force of a leaf spring for biasing, and an armature coil mounted around the core is excited. In a wire dot print head for canceling the magnetic flux of the permanent magnet with magnetic flux to release the armature and projecting the dot wire for printing, a ring-shaped arrangement is provided on the side opposite to the armature with respect to the bias leaf spring. And a spacer having a first tongue-shaped projecting piece projecting to the position of the rotation fulcrum of the armature, and a spacer arranged in a ring shape on the side opposite to the bias leaf spring with respect to the spacer, the first tongue-shaped projection being provided. A wire dot print head, comprising: a yoke having a second tongue-shaped projecting piece for preventing bending of the piece.