JPH0626898B2 - Printing head for dot printer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head for a dot printer used as an output terminal of various computers.

Configuration of conventional example and its problems In recent years, due to the development of various computers, dot printers that can print on various types of paper and are low-priced are widely used, and there is a strong demand for further downsizing and cost reduction. .

The following is the first print head for a conventional dot printer.
It will be described with reference to FIG.

FIG. 1 is a schematic side sectional view of a conventional print head for a dot printer of the outer magnet permanent magnet type. In FIG. 1, 1 is a print needle, 2 is a bearing having a guide hole for guiding one end of the print needle 1, 3 is a housing for holding the bearing 2, and 4 is an actuator fixed to the other end of the print needle 1. 5 is a leaf spring fixed to one end of the actuation body 4, 6 is a yoke plate that supports one end of the leaf spring 5, and returns the magnetic flux of the actuation body 5, 7 is a spacer, 8 is a ring, 9 is a permanent magnet, 10 is a support ring, a ring 8, a permanent magnet 9,
The support rings 10 are joined by adhesion. 11
Is a substrate, 12 is a pole pole connected by the support ring 10 and the substrate 11, and 13 is a degaussing coil wound around the pole pole 12. Here, the plurality of actuating bodies 4 and the leaf springs 5 are arranged in an annular shape, and the magnetic pole posts 12 are arranged so as to face the actuating body 4. The permanent magnet 9 is arranged outside the magnetic pole column 12 and has a ring shape. The yoke plate 6 is provided with a plurality of grooves so as to embrace the side surface of the actuation body 4.

The operation of the conventional outer magnet permanent magnet type dot printer print head configured as described above will be described below.

First, in a state where no current is flowing through the degaussing coil 13, the magnetic flux of the permanent magnet 9 is guided to the actuating body 4 through the supporting ring 10, the substrate 11 and the magnetic pole post 12 and the leaf spring 5.
Further, it is returned from the side surface of the actuating body 4 to the permanent magnet 9 through the yoke plate 6, the leaf spring 5, the spacer 7 and the ring 8. Therefore, the actuating body 4 is attracted downward toward the magnetic pole post 12 by the magnetic flux of the permanent magnet 9, and the leaf spring 5 is in a bent state attracted to the magnetic pole post 12. next,
When a current is passed through the degaussing coil 13, the magnetic flux of the permanent magnet 9 is canceled and the attractive force of the actuating body 4 decreases, so that the restoring force of the leaf spring 5 accelerates the actuating body 4 upward. At this time, since the print needle 1 is also accelerated upward, the tip of the print needle 1 projects from the bearing 2 and impacts an ink ribbon (not shown) to print dots. Further, when the current of the degaussing coil 13 is stopped, the actuating body 4 is attracted again by the time flux of the permanent magnet 9 as described above, and thus the print needle 1 returns to the original position.

With the above operation as one cycle, dot-matrix printing is performed by operating the print needle 1 while scanning the dot printer print head left and right.

However, in the above-described conventional configuration, as described above, the permanent magnet 9 is arranged outside the magnetic pole column 12, and there are the following drawbacks.

First, since the permanent magnet 9 is arranged outside the magnetic pole column 12, its outer diameter inevitably becomes large, and it is unavoidable that the permanent magnet 9 has a ring shape, that is, a plate shape with holes. As described above, a permanent magnet having a large outer shape is very expensive because it is difficult to provide flatness and is easily cracked in the grinding process. Further, since the outer diameter is large, the magnetic leakage is inevitably large. Further, as described above, since the plate has a hole, the magnetic leakage also occurs from the inside of the hole. Further, according to the manufacturing method of the permanent magnet, the permanent magnet with holes can only be pressed in the plate thickness direction, and cannot be pressed in the radial direction. However, even if the same permanent magnet material is used, pressing in the radial direction is 1
The magnetic energy can be increased by 0 to 20%.
That is, the permanent magnet having a hole has a magnetic energy loss due to the manufacturing method thereof in addition to the magnetic leakage from the inside of the hole. As described above, arranging the permanent magnets 9 on the outer side of the magnetic pole columns 12 is disadvantageous in terms of downsizing and cost reduction of the dot printer print head.

Further, as described above, after the permanent magnet 9, the ring 8 and the support ring 10 are joined by an adhesive or the like, the upper surface of the ring 8 is ground or polished so that the upper surface thereof is flush with the upper surface of the pole post 12. . This is to make the air gap between the leaf spring 5 and the magnetic pole column 12 constant, but as described above, since the permanent magnet 9, the ring 8 and the support ring 10 are joined by an adhesive or the like, the dimension with respect to the temperature change. Since the change is large, it is difficult to keep the gap between the leaf spring 5 and the magnetic pole column 12 stable, and the operation of the actuation body 4 may become unstable.

Next, a conventional print head for a dot printer of the inner magnet permanent magnet type will be described with reference to FIG.

FIG. 2 is a schematic side sectional view of a conventional inner-permanent-magnet type print head for a dot printer, in which 15 is a print needle, 16 is a bearing having a guide hole for guiding one end of the print needle 15, and 17
Is a casing holding the bearing 16, 19 is a leaf spring fixed to the other end of the printing needle 15, 18 is an actuating member fixed to one surface of the leaf spring 19, 20 is a ring, 21 is a leaf spring support ring, 2
Reference numeral 2 is a substrate, 23 is a magnetic pole column arranged in a substantially annular shape on the substrate 22, 24 is a permanent magnet such as alnico or ferrite fixed near the center of the substrate 22, and 25 is fixed on the upper surface of the permanent magnet 24. A yoke, 26 is a degaussing coil, and 27 is a yoke plate. Here, the magnetic flux of the permanent magnet 24 is guided to the actuating body 18 through the yoke 25, and is returned to the permanent magnet 24 by the pole post 23 and the substrate 22.

Since the operation of the conventional dot printer print head of the inner magnet permanent magnet type configured as described above is the same as that of the conventional dot printer print head of the outer magnet permanent magnet type,
The description is omitted. Here, since the permanent magnet 24 of alnico, ferrite or the like is used in the conventional print head for dot printer of the inner magnet permanent magnet type as described above, in order to obtain a sufficient magnetic attraction force, the permanent magnet 24 It is necessary to make the thickness of the permanent magnet 24 sufficiently thick, and as shown in FIG. Therefore, since the magnetic resistance of the permanent magnet portion was large, the drive current was increased and inevitably large magnetic interference was caused. Furthermore, since the thickness H of the permanent magnet 24 is large, magnetic leakage is large, which is an obstacle to improving the efficiency of the magnetic circuit.

The actuating body 18 is located below the leaf spring 19 in the figure, that is,
Since it is arranged so as to face the magnetic pole column 23,
The working distance of was changed depending on the thickness T of the working body 18. Here, when the degaussing coil 26 is energized, the permanent magnet 2
The magnetic flux of No. 4 is canceled and the leaf spring 19 sets the gap distance between the operating body 18 and the magnetic pole post 23 when the leaf spring 19 returns to the equilibrium position as the operating distance of the operating body 18.

For this reason, the thickness T of the actuating body 18 is made uniform, which leads to an increase in cost, and those having a non-uniform thickness T result in malfunction. Further, since the tip end portion C of the leaf spring 19 is sufficiently close to the yoke 25, the magnetic attraction force acts on the tip end portion C of the leaf spring 19 even when the degaussing coil 26 is energized, and the leaf spring returns. Because it works as a braking force against the force,
There was a decrease in operating force, that is, a decrease in printing power.

Further, as shown in FIG. 2, since the B surface of the pole post 23 and the A surface of the leaf spring support ring 21 are not in the same plane,
It is difficult to obtain parallelism between the surfaces A and B, and it is difficult to make the air gap between the operating body 18 and the magnetic pole post 23 uniform for each operating body, which causes a malfunction. Was.

An object of the present invention is to solve the above-mentioned conventional problems, and to provide a print head for a dot printer which is small in size, low in price and low in power consumption.

To achieve the above object, the present invention provides a plurality of actuating bodies each having a print needle at the tip, a leaf spring fixed to one end of each of the plurality of actuating bodies, and one end of the leaf spring. A supporting ring, a substrate on which the supporting ring is arranged in a substantially circumferential shape, a plurality of magnetic pole posts and a degaussing coil disposed on the substrate inside the supporting ring and having a surface facing the leaf spring. A converging magnetic pole column arranged in the center of the substrate, a permanent magnet provided on one surface of the converging magnetic pole column so as to exert a magnetic force on the actuating member, and a joint provided on the other surface of the permanent magnet. An iron column is provided, and the yoke column is composed of a yoke plate and a plurality of tip columns formed on the yoke plate, and the yoke plate and the plurality of tip columns are integrally formed, and the yoke plate is , A conical shape on the inner peripheral side of the plurality of tip columns The configuration is such that a concave portion is provided, thereby providing a small size, low price, low power consumption print head for a dot printer.

Description of Embodiments One embodiment of the present invention will be described below with reference to FIGS. 3 and 4. The same parts are denoted by the same reference numerals in FIGS. 3 and 4. FIG. 4 is a schematic side sectional view showing an embodiment of the present invention, and FIG. 3 is a partial plan view thereof. In FIGS. 3 and 4, 28 is a print needle and 29
Is a bearing having a guide hole 29a for guiding one end of the print needle 28, 30 is a housing for holding the bearing 29, and 31 is the print needle 28.
To the other end of the plate spring 32, 32 is a leaf spring fixed to one end of the actuator 31, 33 is a spacer fixed to the lower surface of the plate spring 32, and 34 is the other end of the plate spring 32 via the spacer 33. A supporting ring for supporting 35, a substrate on which the supporting ring 34 is disposed in a substantially circumferential shape, and 36, a plurality of annular members disposed on the substrate 35 at the inner periphery of the supporting ring 34 and having a surface facing the leaf spring 32. Of the individual pole columns, the top surface of the pole column 36 is flush with the top surface of the support ring 34. Reference numeral 37 denotes a degaussing coil wound around a magnetic pole column, 38 denotes a converging magnetic pole column provided at the center of the substrate 35, 39 denotes a permanent magnet joined to the upper surface of the convergent magnetic pole column 38, and 40 denotes an upper surface of the permanent magnet 39. The yoke plate has a conical recess G having an inner peripheral surface substantially parallel to the lower surface of the actuating body 31 at the center thereof. Four
Reference numeral 1 denotes a front end column of a yoke plate 40 having a projecting portion on the outer peripheral side, which is annularly arranged between the plurality of actuating bodies 31, and the yoke plate 40 and the tip column 41 constitute a yoke column.

Next, the present embodiment having the above configuration will be described. The magnetic flux of the permanent magnet 39 passes through the yoke column 4 and the tip column 4 of the yoke column 4.
1 to the actuating body 31, through the leaf spring 32, through the pole post 36, the substrate 35, and the converging pole post 38,
It returns to the permanent magnet 39. Here, since the permanent magnet 39 is arranged in the vicinity of the actuating body 31 to which the magnetic attraction force should act, the magnetic leakage is small and the permanent magnet can be downsized. Further, since the permanent magnet 39 is arranged in the central portion of the substrate 35, that is, on the inner peripheral side of the magnetic pole column 36, the permanent magnet 39 can be formed in a plate shape without a hole, and high-speed utilization at an hour can be achieved. Therefore, the permanent magnet 39 can be further downsized.

If the permanent magnet 39 is formed into a thin plate by using a high coercive force magnet such as a rare earth magnet, the magnetic resistance of the permanent magnet portion can be reduced, so that magnetic interference can be reduced and power consumption can be reduced. Here, with respect to a conventional external magnet permanent magnet type dot printer print head, for example, a 24-pin print head for Chinese character printing, the diameter of the permanent magnet is generally 50 mm or more. As is well known, since permanent magnets are hard and brittle materials, it is very difficult to reduce their thickness. For example, for permanent magnets with a diameter of 50 mm or more, the maximum thickness is 1.5 mm. Was used. By using this inner magnetic permanent magnet type magnetic circuit structure of the present invention, the outer diameter of the permanent magnet can be reduced to 1/2 or less of the conventional one, and thus the thickness of the permanent magnet can be reduced to about 1/2. It has become possible to do.

Further, if the support ring 34, the pole post 36, the substrate 35, and the converging pole post 38 are integrally formed of a soft magnetic material, and the support ring 34 and the pole post 36 are arranged in the same plane, the support ring 34 and the pole post are formed. By simultaneously processing each surface of 36, parallelism of both surfaces can be easily obtained, the gap between the leaf spring 32 and the pole post 36 can be made uniform, and the assemblability is improved and the operation is stabilized. Can be converted.

Further, the yoke column is integrally formed with the yoke plate 40 and a plurality of tip columns 41 formed on the yoke plate 40, and the yoke plate 40 has a conical shape on the inner peripheral side of the plurality of tip columns 41. Recess G
By providing the above, the operating body 31 can have a simple shape, and the efficiency of the magnetic circuit can be improved, so that the dot printer head can be further downsized.

Further, if a non-magnetic spacer is interposed between the support ring 34 and the leaf spring 32, the leaf spring 32 can be removed from the support ring 34.
It is possible to reduce the leakage magnetic flux that passes through and further downsize the permanent magnet 39.

Effects of the Invention As described above, according to the print head for a dot printer of the present invention, the following effects can be obtained.

(1) The inner magnet permanent magnet type magnetic circuit configuration and the permanent magnets are arranged in the vicinity so as to exert a magnetic force on the operating body, so that the permanent magnets can be downsized, and the permanent magnets have no holes. As a result, the magnetic leakage can be reduced, and large magnetic energy can be obtained in the manufacturing method of the permanent magnet. Therefore, the permanent magnet can be further reduced in size and cost.

(2) Since the outer diameter of the permanent magnet can be made small, the thickness of the permanent magnet can be made thin, and the magnetic resistance of the permanent magnet part can be made small, so magnetic interference can be reduced and power consumption can be reduced. .

(3) The gap between the actuating body and the pole piece can be easily made uniform, and the assemblability can be improved and the operation can be stabilized.

(4) The actuator can have a simple shape, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic sectional side view of a conventional dot printer print head of the outer magnet permanent magnet type, and FIG. 2 is a schematic side sectional view of a conventional dot printer print head of the inner magnet permanent magnet type. FIG. 4 is a partial plan view and a schematic side sectional view showing a print head for a dot printer according to an embodiment of the present invention. 1,15,28 ... Printing needle, 2,16,29 ... Bearing,
3, 17, 30 ... Casing, 4, 18, 31 ... Actuator,
5, 19, 32 ... Leaf spring, 6, 27, 40 ... Yoke plate, 7, 20, 33 ... Spacer, 8 ... Ring, 9,
25, 39 ... Permanent magnets 10, 21, 34 ... Support rings 11, 22, 35 ... Substrate, 12, 23, 36 ...
… Pole poles, 13, 26, 37 …… Degaussing coils, 41 ……
Tip pillar.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Hayakawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-56-27365 (JP, A) (JP, U)

Claims (4)

[Claims] 1. A plurality of actuating bodies each having a print needle at its tip, a leaf spring fixed to one end of each of the plurality of actuating bodies, a support ring supporting one end of each leaf spring, and the support ring. A substantially circularly arranged substrate, a plurality of magnetic pole posts and a degaussing coil disposed on the substrate inside the support ring and having a surface facing the leaf spring, and a central portion of the substrate. Converged magnetic pole columns arranged, a permanent magnet provided on one surface of the convergent magnetic pole so as to exert a magnetic force on the actuating body, and a yoke column provided on the other surface of the permanent magnet. Is composed of a yoke plate and a plurality of tip columns formed on the yoke plate, and integrally molding the yoke plate and the plurality of tip columns, the yoke plate of the plurality of tip columns. Features a conical recess on the inner circumference Print head for dot printer. 2. The print head for a dot printer according to claim 1, wherein the permanent magnet is plate-shaped and a high coercive force magnet such as a rare earth magnet is used. 3. A support ring, a magnetic pole post, a substrate, and a converging magnetic pole post are integrally formed of a soft magnetic material, and the upper surfaces of the support ring and the magnetic pole post are arranged in the same plane. A print head for a dot printer according to item 1 above. 4. The print head for a dot printer according to claim 1, wherein a non-magnetic spacer is interposed between the support ring and the leaf spring.