JPH0549344U - Wire dot print head - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent deterioration of the strength of the armature tip, facilitate positioning of the armature tip and the printing wire, and obtain sufficient joint strength between the two. [Structure] A concave portion 12 is formed in a joint portion 11a of a print wire 11, and a tip portion 1a of an armature 1 is inserted and fixed in the concave portion 12. The concave portion 12 and the armature tip portion 1a are flatly joined to each other, and a sufficient joining area can be secured.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a structure of a wire dot print head in a serial printer, and more particularly to a joint structure of an armature and a print wire.

[0002]

[Prior Art]

 Conventionally, there are various types of wire dot print heads such as a plunger type and a clapper type, but recently a spring charge type has become the mainstream because of its good high-speed response. In the spring-charged wire dot print head, a wire-fixed armature is swingably supported by a biasing leaf spring, and the armature is preliminarily supported by a permanent magnet against the elastic force of the biasing leaf spring. When printing, the coil wound around the core is excited to generate a magnetic flux in the direction opposite to that of the permanent magnet to release the armature.

FIG. 3 shows a cross section of a conventional wire dot print head.

In the figure, reference numeral 1 is an armature to which a printing wire 2 is fixed at its tip, and 2 is a printing wire for striking a printing medium via an ink ribbon for printing. 3 is a core, 4 is a permanent magnet for attracting the armature 1 to the core 3, and 5 is a coil wound around the core 3 to generate a magnetic flux that cancels the magnetic flux of the permanent magnet 4. Reference numeral 6 denotes a leaf spring that swingably supports the armature 1, and reference numeral 7 denotes a yoke that forms a magnetic path of the permanent magnet 4 for attracting the armature 1 to the core 3.

The armature 1 is supported by a leaf spring 6 in a cantilever manner and is swingable around a supporting portion. The armature 1 is attracted to the end face of the core 3 against the elastic force of the leaf spring 6 by the magnetic attraction force generated by the magnetic path formed by the permanent magnet 4.

Here, the operation of the wire dot print head will be briefly described.

First, in a state where the coil 5 is not excited, the magnetic flux of the permanent magnet 4 passes through the yoke 7, the armature 1 and the core 3, and the magnetic attraction force generated at this time causes the armature 1 to bias the leaf spring 6 and to cause the core 3 to move. Is sucked into.

Next, when the coil 5 is excited in this state, the magnetic flux of the coil 5 cancels the magnetic flux of the permanent magnet 4, and the leaf spring 6 in the biased state is released. As a result, the printing wire 2 joined and fixed to the tip of the armature 1 is driven, and printing is performed on the printing medium via the ink ribbon.

The printing wire 2 is bonded and fixed to the tip of the armature 1. FIG. 4 shows a perspective view of a conventional armature to which the printing wire is bonded and fixed.

In the figure, the armature 1 is formed so that its width becomes narrower near the tip portion, and the printing wire 2 is joined to the tip by using a silver solder.

However, with the recent improvement in the printing speed, the load applied to the joint between the armature 1 and the printing wire 2 tends to increase, and it is necessary to reduce the weight of the armature in order to improve the printing speed. Therefore, the joint area of the joint portion with the print wire 2 tends to decrease.

In the conventional armature of the above-mentioned wire dot printing head, since the printing wire 2 is simply bonded and fixed to the tip of the armature 1, it is difficult to obtain the bonding strength required at the time of printing. The print wire 2 sometimes peeled from the armature 1 during the repeated impact.

Therefore, it has been considered to secure the joining strength by various methods when the wire is joined to the tip of the armature which is thinner than the wire diameter.

[0014]

[Problems to be solved by the device]

 However, in the past, the shape of the armature tip was complicatedly processed to increase the brazing area with the printing wire and to secure the brazing strength.

Bending and cutting were performed as a process for increasing the brazing area, but the thickness of the armature tip becomes thinner as the armature becomes lighter in order to increase the printing speed. In this case, the strain caused by processing has a great influence on the mechanical strength of the armature tip. In other words, the fatigue characteristic of the armature tip is deteriorated, and this becomes an important factor causing damage such as breakage.

Further, originally, it is preferable in terms of force balance that the armature and the printing wire are joined so that the longitudinal center of the armature is flush with the longitudinal center of the printing wire. However, in reality, they are joined with some deviation. As shown in FIG. 5 (b), when the width of the joint portion of the armature 1 is relatively wide, the center deviation l ₂ has no great influence on the joint strength, but as shown in FIG. 5 (a). When the width of the armature 1 joint becomes thin, the influence on the joint strength becomes large even if the center deviation l ₁ is about the same as the provisional age l ₂ . Therefore, a high degree of precision was required for positioning the armature and the print wire during armature processing and joining.

The present invention has been made in view of the above problems, and an object thereof is to suppress strength deterioration due to processing on the armature tip portion, facilitate positioning of the armature tip portion and the printing wire, and reduce the joint area. It is an object of the present invention to provide an excellent wire dot printing head which can be secured and obtain a sufficient bonding strength.

[0018]

Means for Solving the Problems In order to solve the above problems, the present invention provides a wire dot printing head that prints by supporting an armature having a wire fixed to a tip end with a leaf spring and driven by an electromagnet. A recess is formed at the joint with the armature, and the tip of the armature is inserted and fixed in this recess.

[0019]

[Action]

 According to the present invention, since the concave portion is formed at the joining portion of the printing wire and the tip of the armature is inserted and fixed in the concave portion, the positioning of the printing wire and the armature is facilitated and the concave portion and the armature insertion portion are inserted. The joint area with the part becomes large. As a result, sufficient bonding strength can be obtained.

Further, in the present invention, since the armature tip portion is not particularly processed, it is possible to prevent the strength deterioration due to the processing.

[0021]

【Example】

 An embodiment according to the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an essential part showing an embodiment of the present invention, and FIG. 2 is a front view showing a printing wire of the embodiment.

In the figure, a concave portion 12 is formed at a substantially central portion of the joint portion 11 a of the print wire 11. The tip portion 1 a of the armature 1 is inserted in the recess 12. Since the concave portion 12 and the tip portion 1a are flatly joined to each other, the joining area is large. The armature 1 and the print wire 12 are fixed to each other at this joint by silver brazing or the like.

In this way, the joining area is increased to increase the joining strength, and further, the joining portion 11a is in a state of straddling the armature tip portion 1a, so that an impact at the time of printing is applied to the printing wire 11. However, the print wire 11 does not fall off the armature 1.

Further, the longitudinal center of the print wire 11 and the longitudinal center of the armature 1 are only the backlash of the fitting portion, and are not greatly displaced, and the yield due to defective bonding is improved. To do.

Further, in the present embodiment, since the armature 1 is not particularly processed, such as cutting, the mechanical strength of the armature 1 itself does not deteriorate.

[0026]

[Effect of the device]

 As described above, according to the present invention, since the concave portion is formed in the joint portion of the print wire and the tip portion of the armature is inserted into the concave portion and the joint is performed, sufficient joint strength can be obtained, and the impact during printing can be obtained. Even if the print is added, no trouble such as dropping of the print wire will occur.

Further, since the armature tip portion is not processed to increase the joining area, the mechanical strength of the armature tip portion is not impaired, the reliability against breakage is improved, and the armature is further improved. It is effective for downsizing and weight reduction.

Further, the printing wire can be easily positioned with respect to the armature, and there is an effect that the manufacturing yield is improved.

[Brief description of drawings]

FIG. 1 is a perspective view of an essential part showing an embodiment according to the present invention.

FIG. 2 is a front view showing the printing wire of the embodiment.

FIG. 3 is a sectional view showing a conventional wire dot print head.

FIG. 4 is a perspective view showing a conventional armature.

FIG. 5 is an explanatory view showing joining of a conventional armature and a wire.

[Explanation of symbols]

 1 Armature 11 Printing Wire 11a Joint 12 Recess

Claims (1)

[Scope of utility model registration request] 1. A wire dot printing head in which an armature having a wire joined to a tip thereof is supported by a leaf spring and is driven by an electromagnet for printing, and a recess is formed at a joint of the wire and the armature, and the armature is formed in the recess. A wire dot printing head characterized by inserting and fixing the tip of the.