JPH05520A - Impact dot head - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize an impact dot head that is lightweight, realizes high-speed drive and high copying capability while preventing the printing wire from bending in the impact dot head. [Structure] The portion of the printing wire 5 that engages with the wire guide 23 has a large diameter and the other portions have a small diameter. [Effect] While the clearance between each wire guide 23 and the printing wire 5 is optimally secured, the diameter of the printing wire 5 is reduced to a large extent, and energy can be prevented from being lost. It becomes possible to drive at high speed efficiently, and the copying ability is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact dot head.

[0002]

2. Description of the Related Art In a printing apparatus, a wire type dot printer for exclusive use of alphanumeric characters, which has a thick printing wire diameter of about 0.3 mm, is the best in terms of printing quality and is in the mainstream. However, if the diameter of the printing wire is large, the mass thereof increases and it becomes difficult to drive at high speed. Further, since the wire has a high bending rigidity, in the case of a print head in which the wire is fixed to the lever, it becomes a load at the time of driving, which lowers energy efficiency and causes wear of the guide. As a method for solving these problems, for example, a stepped taper or a taper wire in which only the printing tip has a large diameter and the others have a small diameter, as shown in JP-A-63-31284 (FIG. 5), is known. There is.

[0003]

However, in the case of such a conventional printing wire, the hole diameter of the wire guide on the drive unit side is the same as the hole diameter of the wire guide on the printing end side, or if not larger, Insertion is impossible. Therefore,
In the small diameter portion of the printing wire, the clearance between the wire guide hole and the printing wire becomes extremely large, and as shown in FIG. 5 (b), the printing wire is largely deflected when it collides with the platen, resulting in loss of printing energy transmission. And the print density is lowered and the response is deteriorated.

Therefore, the present invention is intended to solve such a problem, and an object of the present invention is to reduce the mass of the printing wire while preventing the printing wire from flexing, to enable high-speed driving, and to improve the copying ability. It is to realize a high and high performance print head.

[0005]

The impact dot head of the present invention is a wire type impact dot head comprising a group of print wires, a wire guide for holding the print wires, and a drive unit for driving the print wires. It is characterized in that only a portion of the group of printing wires engaging with the wire guide has a large diameter and the other portions have a small diameter. Further, a part or all of the large diameter portion is formed by coating and fixing a tubular wear resistant material on the small diameter portion of the printing wire.

[0006]

According to the above configuration of the present invention, while ensuring the clearance between each wire guide and the printing wire under optimum conditions,
Since the weight of the printing wire can be reduced, it is possible to prevent printing energy transmission loss due to the bending of the printing wire, and to perform printing at high speed and with high copying ability.

[0007]

EXAMPLES The present invention will be described in detail below based on examples.

First, an example of the structure of an impact dot head to which the present invention is applied will be described.

1 and 2 are a side sectional view and a plan view of an impact dot head according to an embodiment of the present invention. Reference numeral 1 denotes a core block made of a magnetic material such as pure iron, silicon steel, and permendur, and a core 3 around which an electromagnetic coil 2 is wound is formed in a ring shape on its inner surface. The lever 4 is composed of an arm portion 6 having a print wire 5 fixed to the tip thereof, an armature portion 7 that is urged by the core 3 to be attracted, and a fulcrum shaft 8 that serves as a swing fulcrum of the lever.

The dish-shaped yoke 9 is formed of a magnetic material so as to form a part of the magnetic path together with the disk-shaped yoke 10 and the core block 1. The dish-shaped yoke 9 supports the fulcrum shaft 8 of the lever 4 and is finished to have an accurate thickness by a double-side polishing method so that the fulcrum shaft 8 can be supported on the front surface of the core block 1 at a predetermined height position. On this surface, slits 11 that form the swing space of the lever 4 are radially formed. On the other hand, the disk-shaped yoke 10 conforms to the planar shape of the lever 4 including the fulcrum shaft 8 on its surface so that each lever 4 can be positioned and held facing each corresponding core 3. The slits 12 are radially formed, and the lever 4 is attached to these slits 1.
The dish-shaped yoke 9 and the frame 1 are fitted in the inside of the casings 1 and 12.
The diameter of the fulcrum shaft 8 is slightly smaller than the diameter of the fulcrum shaft 8 so that the fulcrum shaft 8 can be sandwiched between the fulcrum shaft 3 and the protrusion 14.

On the other hand, the frame 13 comprises a disk portion 15 facing the core block 1 and a nose portion 17 holding a guide holder 16. The disk portion 15 cooperates with the disc-shaped yoke 9 near the peripheral portion thereof to support the fulcrum shaft 8 of the lever 4.
A plurality of protrusions 14 that sandwich the
Further, a fitting recess 19 for the spring holding member 18 is provided in this central portion. The spring holding member 18 is provided with a spring receiving hole 20 at a portion corresponding to the arm portion 6 of the lever 4, and the coil spring 21 inserted therein causes the spring receiving hole 20 to be recessed.
The arm portion 6 is always urged so as to abut the damper 22.

A wire guide 23 is attached to the tip and the middle of the guide holder 16.
The print wire 5 fixed to the tip is slidably guided toward the tip of the nose portion 17 so as to converge.

The above is the structure of the front-stage drive unit, but the rear-stage drive unit having almost the same structure is laminated on the front-stage rear surface, the radiator 24 is covered on the rearmost surface, and the whole screw 25 is provided.
It is fixed at.

The shape of the printing wire 5 is a feature of the present invention. As shown in FIG. 3, only the position where it engages with each wire guide 23 is thicker than the other portions. A portion including the tip of the printing wire 5 that engages with the wire guide 23 is a large-diameter portion 26 having a diameter of approximately 0.3 mm, and the other portion is a small-diameter portion 27 having a diameter of approximately 0.2 mm, and a boundary between the two is a taper 28. The shape is continuously connected by. The large-diameter portion 26 corresponds to the slide amount when the printing wire 5 is driven,
It is desirable that the length has a certain margin (for example, about 1 mm).

In the present embodiment, the engaging portion between the lever 4 and the wire 5 has a small diameter, but it is desirable that this portion has an optimum diameter according to the allowable stress of the material, the load when the wire is driven, and the like.

Next, the operation of the impact dot head thus constructed will be described.

When a pulse current is applied to one or more electromagnetic coils 2 selected by the print signal, the armature portion 7 of the lever 4 is attracted by the magnetic flux flowing from the core 3 to the dish-shaped yoke 9 and the disk-shaped yoke 10. The printing wire 5 held at the tip is projected in the axial direction for printing. When the application of the pulse current is finished, the suction force disappears, and the reaction force of collision between the printing wire 5 and the platen (not shown) and the coil spring 2
The spring force 1 returns the lever 4 to its original position.

FIG. 4 is a view showing another embodiment, in which the tubular member 30 is inserted into and fixed to the wire guide 23 engaging portion of the small-diameter printing wire 29 to form a large-diameter portion. If the tubular member 30 has abrasion resistance equal to or higher than that of the material of the small diameter portion, the tip may be formed by this method, but only the tip has a large diameter stepped wire (that is, the prior art shown in FIG. 5). When the tube-shaped member 30 is inserted in the middle part of (shape), it is possible to use a resin material or the like for the tube-shaped member 30, and further weight reduction is realized. In addition, the tip of the clothing material is a wear-resistant material such as ceramics,
A high-performance printing wire can be realized by combining a material such as a resin material such as POM in the middle portion. As the method of fixing the tubular member, an optimum method such as brazing, press fitting, heat crimping, bonding, HIP, or outsert molding may be selected depending on the material.

[0019]

As described above, according to the present invention, the clearance between each wire guide and the printing wire is optimally secured, and at the same time, the weight of the printing wire is reduced to a great extent to realize a significant weight reduction. It is possible to prevent the loss of printing energy due to the bending of the printing wire. As a result, the printing wire can be efficiently driven at high speed, and the copying ability is improved. Further, by fixing another tubular member to the small diameter wire, a very easy and inexpensive different diameter wire can be obtained.

[Brief description of drawings]

FIG. 1 is a side sectional view of an entire impact dot head showing an embodiment of the present invention.

FIG. 2 is a plan view of the entire impact dot head showing an embodiment of the present invention.

FIG. 3 is a schematic diagram showing a characteristic part of an embodiment of the present invention.

FIG. 4 is a schematic view showing another embodiment of the present invention.

FIG. 5 is a schematic diagram showing an example of a conventional technique. (A) is a figure which shows the standby state of a print wire, (b) is a figure which shows the collision state of a print wire.

[Explanation of symbols]

 1 core block 2 electromagnetic coil 3 core 4 lever 5 printing wire 8 fulcrum shaft 9 plate-shaped yoke 10 disk-shaped yoke 13 frame 16 guide holder 18 spring holding member 21 coil spring 22 damper 23 wire guide 24 radiator 26 large diameter part 27 Small diameter part 28 Taper 30 Tube-shaped member 31 Ink ribbon 32 Printing paper 33 Platen

Claims (1)

Claim: What is claimed is: 1. A wire type impact dot head comprising a group of print wires, a wire guide for holding the print wires, and a drive unit for driving the print wires. An impact dot head characterized in that only a portion engaging with the wire guide has a large diameter and the other portions have a small diameter. 2. A small-diameter portion of the printing wire is covered with a tubular wear-resistant material on a part or all of the large-diameter portion,
The impact dot head according to claim 1, wherein the impact dot head is formed by fixing.