JPH0435349B2 - - Google Patents

Description

[Detailed description of the invention] [Fields of industrial use]

In this invention, armatures to which the rear ends of printing wires are fixed are arranged in a radial manner, each of these armatures is elastically supported by a leaf spring on an armature holder, and the armatures are formed in a radial manner on the armature holder. The present invention relates to a print head in which armatures are individually loosely fitted into a plurality of grooves, and particularly to a structure for fixing the base end of a leaf spring to an armature holder.

[Conventional technology]

A conventional print head has a structure shown in FIGS. 1 to 5, and will be described in detail below with reference to these drawings. Fig. 1 is a sectional view of a conventional printing head, Fig. 2 is a sectional view taken along the line - - in Fig. 3, and a sectional view of the armature holder in Fig. 1, and Fig. 3 is a view taken in the direction of the arrow in Fig. 2. FIG. 4 is a cross-sectional view taken along the - line in FIG. FIG. 5 is an enlarged rear view of the main part, which is a view taken along arrow V in FIG. 4; The printing head 1 has a substantially rectangular cylindrical shape and has a printing wire holder 2 formed with a disk-shaped flange on the back side, and a guide plate 3 having a plurality of guide holes drilled therein at predetermined intervals. It is firmly fitted and fixed. And these guide plates 3
A plurality of printing wires 4 are individually inserted into the guide holes of the printing wire holder 2, and their tips are aligned and assembled into the printing wire holder 2 so as to be slidable. The rear end of the printing wire 4 is attached to the printing wire holder 2.
They pass through a through hole 5a drilled in the center of the armature holder 5 to which they are fixed, and are individually fixed to the plurality of armatures 6. The armatures 6 are individually loosely fitted into a plurality of grooves 5b formed radially on the back side of the printing wire holder 2 and are arranged in a radial manner. It is elastically supported by the portion 5c. Base end 7a of leaf spring 7 of armature holder 5
A core 10 is integrally fixed to the side surface of the flange portion 5c, which is fixed with screws 8, with a spacer 9 made of a magnetic material inserted therein. The core 10 includes an annular outer pole part 10a, a plurality of inner pole parts 10b having a substantially L-shaped cross section, which are arranged concentrically with the outer pole part 10a at intervals in the circumferential direction, and an outer pole part 10a. A permanent magnet 11 and a spacer 12 made of magnetic material are laminated on an annular flange 10c extending in the outer diameter direction of the inner pole part 10.
It has a structure including electromagnetic coils 13 that are individually fitted and fixed to b. In addition, the magnetic pole surface 10d of the inner pole portion 10b of the core 10
In this case, the armature 6 can be freely moved toward and away from the armature 6, and the magnetic flux of the permanent magnet 11 and the electromagnetic coil 13 flows from the inner pole part 10b of the core 10 through the outer pole part 10a to the armature holder 5. This structure constitutes a magnetic circuit that flows from the flange portion 5c to the inner pole portion 10b of the core 10 from the armature 6 through the side magnetic path portion 5d that serves as the circumferential wall of the groove 5b. Therefore, in the conventional printing head 1 having such a structure, the armature 6 is normally pushed against the inner pole of the core 10 by the magnetic flux of the permanent magnet 11 against the spring force of the leaf spring 7, as shown in FIG. The armature 6 is magnetically attracted to the magnetic pole surface 10d formed on the magnetic pole surface 10b, and by energizing the electromagnetic coil 13 and canceling out the magnetic flux of the permanent magnet 11 with the magnetic flux of the electromagnetic coil 13, the armature 6 absorbs the spring force of the leaf spring 7. Then, the inner pole portion 10b of the core 10 is separated from the magnetic pole surface 10d, and the printing wire 4 is projected from the printing wire holder 2. By the way, the armature holder 5 included in the conventional printing head 1 is designed in the shape shown in FIGS. 2 and 3. In other words, it has a shape with a generally dish-shaped cross section, a through hole 5a is bored in the center, a disc-shaped flange part 5c is formed on the outer periphery, and a groove is formed in the annular protrusion protruding from the back side. 5b is formed radially by milling, so that the remaining portion of the annular protrusion other than the groove 5b serves as a side magnetic path portion 5d. The structure for elastically supporting the armature 6 on the armature holder 5 is shown in imaginary lines in FIG. It is a structure consisting of figures. That is, the printing wire 4 and the leaf spring 7 are fixed to the armature 6, and the armature 6 is loosely fitted into the groove 5b of the armature holder 5, and at the same time, the printing wire 4 is inserted into the through hole 5a of the armature holder 5. do. The base end 7a of the leaf spring 7 is fixed to the armature holder 5 by a screw 8 screwed into a screw hole 5e formed in a flange 5c of the armature holder 5. Note that the reference numeral 14 shown in FIGS. 2, 4, and 5 is a washer for the screw 8.

[Problem to be solved by the invention]

In the conventional print head 1, the base end 7 of the leaf spring 7
Considering the fixing structure of a to the armature holder 5, an annular step portion 5f is formed on the side surface (back surface) of the flange portion 5c of the armature holder 5, and from the annular corner portion 5g of this step portion 5f. The line segment was configured as the fulcrum of the leaf spring 7. The applicant's intention in forming such a stepped portion 5f is to connect the corner portion of the inner diameter surface 5h of the flange 5c to the plate spring 7.
If configured as a fulcrum, the span of the leaf spring 7 from the inner diameter surface 5h to the outer surface 6a of the armature 6 will be shortened, and the spring load will increase rapidly relative to the amount of deflection of the leaf spring 7. The spring force (releasing force) of the leaf spring 7 that causes the tip of the platen 4 to strike the platen through the ink ribbon and printing paper does not meet the design standards. Furthermore, it was considered that if the diameter of the inner diameter surface 5h of the armature holder 5 were increased, problems such as an increase in the diameter and weight of the print head 1 would arise. However, in the print head 1 to which such a design change has been added, the corner portions 5g of the armature holder 5, which serve as individual fulcrums of the leaf springs 7, are arcuate, so the armature holder of the leaf spring 7 5
There was a problem in that stress was concentrated on both ends of the short side at the portion that abutted against the corner 5g of the plate spring 7, resulting in poor durability of the leaf spring 7. In this invention, the quality reliability of the print head 1 is improved by fixing the base end 7a of the leaf spring 7 to the armature holder 5, which prevents stress concentration at the fulcrum part of the leaf spring 7. The purpose is to improve.

[Means to solve the problem]

In order to achieve such an object, the present invention includes a printing wire holder, a plurality of guide plates fitted and fixed at predetermined intervals in the cylindrical part of the printing wire holder, and individual guide plates of the guide plate. A plurality of printing wires that are inserted into guide holes and whose tips are aligned and assembled, a plurality of armatures in which the rear ends of these printing wires are individually fixed and arranged in a radial pattern, and the printing wires of these armatures are fixed. A plurality of leaf springs having free ends fixed to the side opposite to the part, a base end of the leaf springs fixed to the side surface, and a plurality of leaf springs formed radially at intervals in the circumferential direction. An armature holder consisting of an annular member in which each armature is loosely fitted into a groove, a permanent magnet that magnetically attracts the armature against the spring force of a leaf spring, and a magnetic flux of the permanent magnet is applied to each armature. The printing wire passes through a through hole drilled in the center of the armature holder and guides the guide plate individually. In the print head inserted into the hole, a polygonal stepped portion having the same number of corners as the groove of the armature holder is formed on the side surface to which the base end of the leaf spring of the armature holder is fixed; A feature is that a line segment formed by a corner of this stepped portion is configured as a fulcrum of the leaf spring.

[Effect]

In the print head, the armature is usually magnetically attracted to the magnetic pole surface formed at the inner pole of the core against the spring force of the leaf spring due to the magnetic flux of the permanent magnet.
By energizing the electromagnetic coil and canceling out the magnetic flux of the permanent magnet with the magnetic flux of this electromagnetic coil, the armature is separated from the magnetic pole surface of the inner pole of the core by the spring force of the leaf spring, and the printing wire is projected from the printing wire holder. Ru.

【Example】

6 to 10 show a print head according to an embodiment of the present invention, FIG. 6 is a cross-sectional view of the print head, and FIG. 7 is a cross-section taken along the line -- in FIG. 8 is a rear view of the armature holder, which is a view taken in the direction of the arrow in FIG. 7, and FIG. 9 is a sectional view taken along the - line in FIG. FIG. 10 is an enlarged cross-sectional view of the main part for explaining the fixing structure to the holder, and FIG. 10 is an enlarged back view of the main part, which is a view taken along the arrow in FIG. In addition,
Components similar to those of the print head 1 described above are given the same reference numerals and detailed explanations will be omitted. The printing head 15 is an armature assembled by separately manufacturing an outer annular member 17 and an inner annular member 18 by press molding, and then concentrically fitting and fixing these annular members 17 and 18 together. The structure is largely different from the previous print head 1 in that it is provided with a own holder 16. The outer annular member 17 has screw holes 17a (corresponding to the screw holes 5e in FIG. 2) formed at positions divided into 24 equal parts, and has screw holes 17a (corresponding to the screw holes 5e in FIG. 2) formed on the front side surface to which the printing wire holder 2 is fixed. The inner edge of the core 10 and the inner edge of the back side to which the core 10 is fixed each have a diameter of 24 mm.
A rectangular step portion 17b and a step portion 17c are formed. On the other hand, the inner annular member 18 is formed with 24 grooves 18a corresponding to the screw holes 17a of the outer annular member 17 (with center lines that match the radial center line of the screw holes 17a), and , a flange portion 18c whose outer periphery is a 24-gon square circumferential surface 18b, which is fitted into a 24-sided stepped portion 17b formed on the front side surface of the outer annular member 17; A side magnetic path portion 18d is formed that protrudes by about 1/2 of the wall thickness from the side surface on the back side toward the core 10. Note that the symbols 19 and 20 indicate the outer annular member 17.
When the stepped portion 17b having a 24-gon shape and the corner peripheral surface 18b having a 24-gon shape of the inner ring member 18 are fitted together, the penetration serves as a mark for positioning the outer and inner annular members 17 and 18. It is a hole. The procedure for assembling the printing head 15 equipped with such an armature holder 16 is to fix the armature holder 16 to the printing wire holder 2 and insert the 24 printing wires 4 into the guide holes of the guide plate 3 individually. At the same time, the 24 armatures 6 are individually loosely fitted into the grooves 18a of the armature holder 16. Then, the base end 7a of the leaf spring 7 whose free end is fixed to the armature 6 is fixed to the armature holder 16 by the screw 8 which is screwed in with the washer 14 inserted into the screw hole 17a of the armature holder 16. Fixed at 16. In addition, a spacer 9 and a spacer 12 made of magnetic material are attached to the armature holder 16.
Then, with the permanent magnets 11 stacked, the printing wire holder 2, the armature holder 16, the core 10
be fixed together. In the print head 15 assembled in this way, as shown enlarged in FIGS. 9 and 10,
Circumferential direction 15 from the center of the armature holder 16
Screw holes 17a are placed on straight lines extending radially at intervals of
Since the center line of the groove 18a is aligned with the center line of the groove 18a, the stepped portion 17c forming the 24-gon shape
The corner portion 17d is perpendicular to the radial center line of the leaf spring 7. Therefore, the corner portions 17d of the armature holder 16, which serve as individual fulcrums of the leaf springs 7, are linear, and the stress distribution at the fulcrum portions of the leaf springs 7 becomes uniform. Moreover, by adopting such a structure, effects such as improved durability of the leaf spring 7 and less variation in spring force (release force) can be obtained. Note that the function of the print head 15 is similar to that of the print head 1.
Since the operation is almost the same as that of , the explanation will be omitted. Further, in this embodiment, the base end 7a of the leaf spring 7
was screwed to the annular member 17 on the outside of the armature holder 16 using the screw 8 and the washer 14.
It is preferable that a spacer having an inner peripheral surface of a corner having the same shape as the corner 17d of the annular member 17 is interposed between the leaf spring 7 and the washer 14.

【Effect of the invention】

As described above in detail, in the print head of the present invention, a polygonal step having the same number of corners as the groove of the armature holder is formed on the side surface to which the base end of the leaf spring of the armature holder is fixed. forming a section;
Since the line segment consisting of the corner of this step is configured as the fulcrum of the leaf spring, the stress concentration at the fulcrum of the leaf spring is equalized, the durability of the leaf spring is improved, and the spring force (release) of the leaf spring is improved. As a result, the quality and reliability of the printing head has been improved.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional printing head, Fig. 2 is a sectional view taken along the - line in Fig. 3, and Fig. 3 is a sectional view of the armature holder in Fig. 1, and Fig. 3 is a view taken along the arrow in Fig. 2. Rear view of armature holder, Figure 4 is
Fig. 5 is an enlarged sectional view of the main part for explaining the fixing structure of the leaf spring to the armature holder; 6 is a sectional view of a printing head according to an embodiment of the present invention, FIG. 7 is a sectional view taken along the line -- in FIG. 8, and is a sectional view of the armature holder in FIG. 6. 9 is a rear view of the armature holder, which is a view in the direction of arrows; FIG. FIG. 10 is an enlarged rear view of the main part, which is a view taken in the direction of the arrows in FIG. 9. In the drawings, 2... Printing wire holder, 3... Guide plate, 4... Printing wire, 6... Armature, 7
... leaf spring, 10 ... core, 11 ... permanent magnet,
13... Electromagnetic coil, 16... Armature holder, 17c... Step part, 17d... Corner part, 18a
...Groove, 18d...Side magnetic path section.

Claims (1)

[Claims] 1 A printing wire holder 2, a plurality of guide plates 3 that are fitted and fixed at predetermined intervals in the cylindrical part of this printing wire holder 2, and a plurality of guide plates 3 that are inserted into individual guide holes of this guide plate 3 and whose tips are aligned. A plurality of printing wires 4 that are gathered together, a plurality of armatures 6 to which the rear ends of the printing wires 4 are individually fixed and arranged radially, and a portion of the armature 6 to which the printing wires 4 are fixed are A plurality of leaf springs 7 whose free ends are individually fixed to the opposite side, and a plurality of leaf springs 7 whose base ends 7a are fixed to the side surface and which are formed radially at intervals in the circumferential direction. an armature holder 16 made of an annular member in which the armature 6 is individually loosely fitted into grooves 18a; and a permanent magnet 11 that magnetically attracts the armature 6 against the spring force of the leaf spring 7. , a core 10 having therein a plurality of multi-wound electromagnetic coils 13 that generate a magnetic flux that cancels the magnetic flux of the permanent magnet 11 for each of the armatures 6; At the print head 15 inserted into each guide hole of the guide plate 3 through a through hole drilled in the center of the armature holder 16, the proximal end of the leaf spring 7 of the armature holder 16 is inserted. The armature holder 16 is attached to the side surface to which the armature holder 7a is fixed.
A polygonal stepped portion 17c having the same number of corners as the groove 18a is formed, and the corner portion 17 of this stepped portion 17c is
d as a fulcrum of the leaf spring 7.