JPS6331970Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a printing head for an impact-type dot printer, and particularly relates to an improvement of a so-called spring-storage type printing head in which a printing needle is driven by elastic energy stored in a spring. .

Conventionally, print heads for impact type dot printers have become popular due to their advantages such as high speed, low cost, and variety of character types. In particular, spring-loaded print heads are
It is fast and inexpensive, the printing cycle and printing force are not easily fluctuated by voltage fluctuations, and the power consumption is low.
Due to its advantages such as low heat generation and excellent durability, it has become the mainstream print head for impact-type dot printers. That is, they have been adopted from expensive print heads that perform the highest speed printing to small, lightweight, and inexpensive print heads for so-called low-end printers. In order to construct an inexpensive print head suitable for low-end printers, it is necessary to construct it with as few inexpensive parts as possible, but the basic performance required of the print head must be maintained as much as possible.

Conventionally, there is a print head for low-end printers having the structure shown in FIG. In FIG. 5, a yoke 1 formed into a cup shape from a magnetic material
One magnetic pole of a permanent magnet 102 is fixed to the bottom of the permanent magnet 102, and the bottom of a core body 103, which has a plurality of cores 103a standing upright on a disc made of magnetic material, is fixed to the other magnetic pole of the permanent magnet 102. A coil 104 is wound around each core 103a. At the edge of the yoke 101, there is a spacer 106 formed in a disk shape made of magnetic material and a leaf spring 1.
07 is clamped by a disk-shaped yoke plate 110 made of magnetic material, and is fastened together with a printing needle support 111 by a plurality of fixing screws 112. The leaf spring 107 is branched corresponding to the core 103a, and each branch has an armature 108 formed in a triangular shape made of magnetic material.
are arranged and fixed in an elliptical shape with the apex facing inward, one end of a printing needle 109 is fixed to each apex of the armature 108, and the other end of the printing needle 109 is fixed to the printing needle support 111. They are each linearly guided by a fixed printing needle guide 113 so as to be slidable in the longitudinal direction. Therefore, the leaf spring 107 to which the armature 108 is fixed is obliquely attracted to the core 103a by the magnetomotive force of the permanent magnet 102 against the spring force of the leaf spring 107. An ink ribbon 114 and a printing paper 115 are arranged opposite to the tip of the printing needle 109, and a platen 116 is arranged behind the printing paper 115 to receive the printing force of the printing needle 109. .

Next, the operation of the above conventional example will be explained. When the coil 104 is energized by the print signal, the core 103a around which the coil 104 is wound is excited so that magnetic flux flows in the opposite direction to the flowing magnetic flux due to the magnetomotive force of the permanent magnet 102. The magnetic flux generated by the permanent magnet 102 is canceled by the magnetomotive force of the coil 104, and the leaf spring 107 to which the armature 108 is fixed is released from the attracted core 103a, and the leaf spring 107 is released from the attracted core 103a. The restoring force of the printing needle 107 causes the tip of the printing needle 109 to protrude from the printing needle guide 113, and the printing needle 10
9 hits the platen 116 via the ink ribbon 114 and printing paper 115. The impact causes dots to appear on the printing paper 115, but prior to the imprinting, the power supply to the coil 104 is stopped, and the attraction force of the permanent magnet 102 causes the armature 108 to appear.
The leaf spring 107 to which is fixed is attracted by the core 103a and returns to its original position, colliding obliquely with the core 103a. Therefore, due to the inertia of the armature 108 and the suction force acting between the core 103a and the armature 108, the leaf spring 107 is deflected in a direction in which it comes into close contact with the end surface of the core 103a. Therefore, the leaf spring 107
vibrates and disturbs the next stamping operation, and the leaf spring 10
The bending stress applied to the leaf spring 7 increases, resulting in a decrease in the durability of the leaf spring 107. Further, since the collision area between the core 103a and the leaf spring 107 is very small, there is a drawback that the load per unit area is large and wear is large. In order to eliminate this drawback, core 1
It is also possible to form the tip end surface of the core 103a obliquely so that it closely contacts the surface of the leaf spring 107.
Since 03a is arranged in an elliptical shape, it is difficult to process it with high precision, so it has such a shape. It is also conceivable to join a leaf spring to the background of the surface of the armature that faces the core, and to form the surface of the armature that faces the core in close contact with the tip surface of the core. The problem was that the bond between the two could peel off.

In view of this, the purpose of this invention is to:
To obtain a printing head for an impact type dot printer which is small, lightweight, inexpensive, suitable for high-speed printing, and has excellent durability.

The gist of the present invention to achieve the above object is that it includes a printing needle that performs printing by stamping on printing paper, an armature that firmly holds the printing needle, and a leaf spring that firmly holds the armature. , a permanent magnet, which is magnetically coupled to one magnetic pole of the permanent magnet and faces the back side of the surface of the leaf spring to which the armature is fixed, and supports the armature and the leaf spring against the restoring force of the leaf spring. a core that is attracted and held; a coil that is wound around the core and is energized to release the armature and leaf spring that are attracted to the core; and a yoke that magnetically couples the other magnetic pole of the permanent magnet and the armature. and a leaf spring stop member disposed in a gap between the core and the leaf spring.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below with reference to embodiments and drawings. Fig. 1 is a front view showing the main structure of one embodiment as a partial cross section, Fig. 2 is a bottom view of Fig. 1 shown as a partial cross section, and Fig. 3 is a partially cutaway view of the yoke plate and armature of Fig. 2. FIG. One magnetic pole of a permanent magnet 2 is fixed to the bottom of a cup-shaped yoke 1 made of a magnetic material, and a plurality of cores 3a are made of a magnetic material and stand upright on a disk at the other magnetic pole of the permanent magnet 2. The bottom part of the core body 3 formed by
A coil 4 is wound around each. At the edge of the yoke 1, a leaf spring stopping member 5 formed in an annular shape made of a magnetic material, a spacer 6 formed in an annular plate shape made of a magnetic material, and a leaf spring formed in an annular shape made of a magnetic material are provided. 7 is clamped by a disk-shaped yoke plate 10 made of magnetic material, and is fastened together with a printing needle support 11 by a plurality of fixing screws 12. The leaf spring 7 is branched corresponding to the core 3a, and an armature 8 made of a magnetic material and formed in a triangular shape is arranged in an elliptical shape with the apex facing inward and fixed to each branch.
One end of a printing needle 9 is fixed to each apex of the armature 8, and the other end of the printing needle 9 slides linearly in the longitudinal direction on a printing needle guide 13 fixed to the printing needle support 11. Guided freely. Therefore, the leaf spring 7 to which the armature 8 is fixed is attracted to the core 3a by the magnetomotive force of the permanent magnet 2 against the restoring force of the leaf spring 7.
The tip end surface of the core 3a is machined flat along with the edge of the yoke 1 in order to form an accurate position relative to the fixed surface of the leaf spring 7 and to equalize the amount of movement in the longitudinal direction of all the printing needles 9. The edges of the yoke 1 are adjusted so that the restoring force of all the leaf springs 7 in the state in which they are attracted to the core 3a is constant, and the force required for hitting the printing paper 15 with the printing needle 9 and printing is constant. Since the leaf spring stop member 5 and the spacer 6 are interposed between the leaf spring 7 and the leaf spring 7, the leaf spring 7 is in contact with the corner of the core 3a at a position near the tip, and at a position near the root of the leaf spring 7. In this case, there is no contact with the core 3a, and a slight gap is created. The leaf spring stopping member 5 intervenes in the gap between the core 3a and the leaf spring 7. In order to prevent an increase in magnetic flux leakage, the leaf spring stopper 5 has a connecting portion 5a connecting the core facing portion and the outer peripheral fixing portion with a narrow width, as shown in FIG. An ink ribbon 1 is placed opposite the tip of the printing needle 9.
4. A printing paper 15 is disposed, and a platen 16 for receiving the printing force of the printing needle 9 is disposed behind the printing paper 15.

Next, the operation of the present invention will be explained with reference to an embodiment configured as described above. Coil 4 depending on the print signal
When energized, the core 3a around which the coil 4 is wound is excited so that a magnetic flux flows in the opposite direction to the direction of the flowing magnetic flux due to the magnetomotive force of the permanent magnet 2, and the coil 4 Due to the magnetomotive force of the permanent magnet 2
The magnetic flux generated by the armature 8 is canceled out, and the plate spring 7 to which the armature 8 is fixed is released from the attracted core 3a, and the restoring force of the plate spring 7 causes the tip of the printing needle 9 to print. Protruding from the needle guide 13, the printing needle 9 hits the platen 16 via the ink ribbon 14 and printing paper 15. The impact causes dots to appear on the printing paper 15, but prior to the imprinting, the coil 4 is de-energized, and the leaf spring 7 to which the armature 8 is fixed by the attractive force of the permanent magnet 2 It is attracted by the core 3a and returns, colliding obliquely with the core 3a. Therefore, due to the inertia of the armature 8 and the suction force acting between the core 3a and the armature 8, the leaf spring 7 tends to be deflected in the direction of coming into close contact with the end surface of the core 3a, but the leaf spring 7 is bent by the leaf spring stopping member 5. Since it touches the surface, it hardly bends. Therefore, unlike the conventional example described above, the leaf spring 7 does not vibrate, so the stamping cycle can be shortened without disturbing the next stamping operation, and an abnormally large bending stress is not applied to the leaf spring 7. Durability is improved. Furthermore, since the average gap between the core 3a and the leaf spring 7 becomes smaller, the suction force increases and the stored energy can be increased, which also contributes to shortening the stamping cycle. In addition, since the area where the leaf spring 7 collides with the core 3a increases, the load per unit area is reduced, and wear is reduced and durability is improved.

Next, another embodiment will be described based on FIG. 4.
Since the configuration is almost the same as that of the previous embodiment, it will be omitted, and only the configuration that is different from the previous embodiment will be explained. A plate spring stopping member 5 having a flat plate shape and an annular shape is joined to the distal end surface of the core 3a. In this embodiment, there is no outer peripheral fixing part as in the previous embodiment, and it is not interposed in the magnetic path from the yoke 1 to the yoke plate 10, so it does not need to be made of magnetic material. Therefore, magnetic leakage does not increase. Since the operation is the same as that of the previous embodiment described above, a description thereof will be omitted.

As is clear from the above description, according to the present invention, the leaf spring stopping member 5 is inserted into the gap between the tip end surface of the core 3a and the leaf spring 7 which is obliquely attracted to the tip end surface of the core 3a. As a result, the plate spring 7 does not undergo bending vibration, so the printing cycle becomes short, high-speed printing becomes possible, and the plate spring 7 is not subjected to abnormal stress, improving its durability. Furthermore, the collision area between the core 3a and the leaf spring 7 increases, reducing wear and improving durability. Further, since the leaf spring stop member 5 is formed into a flat plate, it can be manufactured by press punching or etching, so that it can be formed at low cost and with high precision. Further, since the leaf spring stop member 5 is annular and integrated, and is not an independent member corresponding to each core 3a, the number of parts is small, the cost is low, and assembly is easy. Furthermore, by making the leaf spring stop member 5 of a magnetic material, the attractive force is increased, so that the stored energy can be set to a large value, so that the printing cycle is shortened and high-speed printing becomes possible.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view of the main components of a printing head showing an embodiment of the present invention, Fig. 2 is a partially cutaway bottom view of Fig. 1, and Fig. 3 shows the yoke plate and armature of Fig. 2. FIG. 4 is a partially cutaway front view showing another embodiment of the present invention; FIG. 5 is a partially cutaway front view showing the main components of a conventional printing head. It is. DESCRIPTION OF SYMBOLS 1... Yoke, 2... Permanent magnet, 3a... Core, 4... Coil, 5... Leaf spring stop member, 7...
...Plate spring, 8... Armature, 9... Printing needle,
5a... Connection portion between the outer peripheral fixing portion of the plate spring stop member and the core opposing portion.

Claims (1)

[Scope of utility model claims] A printing needle that performs printing by printing on printing paper, an armature that fixes and holds the printing needle at one end, a flat plate spring that fixes and holds the armature at a movable end, a permanent magnet, and the plate. a yoke that supports the fixed end of the spring and magnetically couples one magnetic pole of the permanent magnet to the armature; It has an end surface formed on the same plane as the surface supporting the fixed end, and is magnetically coupled to the other magnetic pole of the permanent magnet to attract and hold the armature and the leaf spring against the restoring force of the leaf spring. The leaf spring includes a core, a coil wound around the core, and a leaf spring stopping member made of a magnetic material that is disposed between the yoke and the leaf spring and covers a part of the end face of the core, and the leaf spring is connected to the core. 1. A print head which is configured to prevent vibration of the armature by colliding with a leaf spring stop member almost simultaneously when the print head is attracted by the core and collides with the core.