JPH0226754A - Spring charge type dot head - Google Patents

Abstract

PURPOSE:To obtain a spring charge head having excellent printing quality and durability at low cost at small sized light-weight printing speed by mounting a high hardness layer onto the surface of a yoke plate. CONSTITUTION:A wire 3 is fixed to an armature 5 through a lever 4, and the armature 5 is fastened integrally to a leaf spring 2. The leaf spring 2 is fixed to a yoke plate 1. The carburizing curing treatment (a) of hardness Hv=300-700 and depth of 0.05-0.5mm is executed to the surface of the yoke plate 1. Consequently, since the leaf spring 2 is deformed while using the corner section (b) of the yoke plate 1 as a fulcrum under the state of holding, working stress concentrates to the section, but carburizing curing treatment (a) is executed to the surface of the yoke plate 2, thus preventing the generation of deformation and abrasion. Accordingly, the strain energy of the leaf spring 2 is stabilized for a prolonged term, thus obviating the deterioration of printing quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wire tod head which is a printing device such as a printer for a computer peripheral terminal.

[Prior Art] Conventionally, as shown in FIG. 3, a yoke plate 31 and a plate spring 62
In order to prevent the corners of the yoke plate from being deformed and worn out due to the operating stress of the leaf spring, a method is known in which a high hardness spacer 33 is provided at the engaging portion of the yoke plate.

In addition, there is a known method of reducing the operating stress applied to the corners of the yoke plate by increasing the width of the plate spring or reducing the plate thickness.[Problem to be Solved by the Invention] When the high-hardness spacer 66 is provided using the conventional method, the free length of the leaf spring 52 changes individually due to the shape accuracy, deformation, and warpage of the high-hardness spacer 65, and also due to positional deviation during installation. This method has the disadvantage that the variation in strain energy becomes large, which tends to cause printing defects. Furthermore, the method of widening the width of the leaf spring or reducing the thickness of the leaf spring has the disadvantage that the shape of the leaf spring becomes large and the dot head cannot be made smaller and lighter. SUMMARY OF THE INVENTION The present invention aims to solve the problems of the prior art and to provide a spring-charged dot head that has excellent print quality, is compact, lightweight, and has a long service life at a low cost.

[Means for Solving the Problems] In order to solve the above problem, the spring-charged dot head of the present invention deforms the armature fixed to the free end of the leaf spring by the magnetic force of a permanent magnet. Then, from the held state in which the core is attracted to the end surface, a current is applied to the electromagnetic filter to cancel the magnetic force of the permanent magnet described in III above, and the armature is opened by the strain energy stored in the leaf spring. In a spring-charged dot head that performs dot matrix printing by selectively protruding the wire fixed to the armature, the surface of the yoke plate is hardened to a depth of 0.05 to 0.5B with Hv=3DO to 700. It is characterized by having layers.

[Example] Embodiments of the present invention will be described below based on the drawings.

In the embodiment shown in FIG. 1, the wire 3 is fixed to an armature 5 via a lever 4, and the armature 5 is fixed integrally with the leaf spring 2. This leaf spring 2 is fixed to the yoke plate 1. The state shown in the lower part of FIG. 1 is a holding state in which the armature 5 is attracted to the end face of the core 7 by the magnetic force of the permanent magnet B, deforming the leaf spring 2 and storing strain energy. The state shown at the top of Figure 1 is
A current is applied to the electromagnetic coil 8 to cancel the magnetic force of the permanent magnet 6, and the armature 5 is released by the strain energy stored in the leaf spring 2, so that the tip of the wire 3 forms a dot on the printing paper 10 via the ribbon 9. The printing condition is as follows. Here, the surface of the yoke plate 10 has an altitude Hv = 500±
50, carburization hardening treatment α of depth 0.05-0-1 ran
This is a characteristic part of the present invention.

In the held state shown in the lower part of FIG. 1, the leaf spring 2 is deformed using the corner of the yoke plate 1 as a fulcrum, so the operating stress is concentrated in this part, but the surface of the yoke plate 20 is carburized. Hardening treatment α prevents deformation and wear.

At this time, since the hardness of the carburized layer is equal to or lower than that of the temporary spring 2, the leaf spring 2 does not wear out. Therefore, the strain energy of the leaf spring 2 is stabilized over a long period of time, and printing quality is not degraded.

Furthermore, by hardening the surface, the rigidity of the yoke plate is greatly increased, which reduces defects due to deformation of this part during assembly.

At the same time, manufacturing costs can be significantly reduced because there is no need for high-hardness spacers, which were conventionally used to prevent deformation and wear.

Furthermore, the corners of the yoke plate can be deformed by increasing the width of the plate spring or reducing the plate thickness to reduce the spring force.

Since there is no need to prevent wear, the spring force of the leaf spring 2 can be strengthened and the dot head can be made smaller, making it possible to make the dot head smaller and lighter and to increase printing speed.

Figure 2 shows that after polishing the upper and lower surfaces of a yoke plate that has been carburized and hardened, it is firmly attached to the leaf spring 22, but carburized and hardened parts C remain at the corners and inner and outer circumferences of the yoke plate 21. Therefore, the same effects as in the previous embodiment can be obtained.

Further, the same effect can be obtained by performing a nitriding hardening treatment, an electroless IIK nickel plating treatment, a ceramic coating treatment, or a titanium carbide chemical vapor deposition treatment in addition to the carburizing treatment as a surface hardening treatment method.

[Effects of the Invention] As explained above, the present invention provides a high hardness layer on the surface of the yoke plate to reduce the deformation of the engagement portion with the plate spring.
This has the effect of preventing wear and making it possible to obtain a spring-charged head that is small, lightweight, high printing speed, and has excellent printing quality and durability at a low cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention. FIG. 2 is a sectional view showing another embodiment. FIG. 6 is a sectional view showing a conventional method. 1 21...Yoke plate 2.22...Plate spring roller...Wire 4...Lever 5... ...Plunger 6...
......Permanent magnet 7 ......Core 8 ......'ti coil 9 ・
...... Ribbon 10 ...... Print paper Q, C ...... Carburized hardened layer b ...... Corner (plate Spring deformation fulcrum)
Figure 3-7 419-Nokmine Wire Renogu-

Claims (1)

[Claims] By deforming the armature fixed to the free end of the leaf spring by the magnetic force of a permanent magnet, and applying a current to the electromagnetic coil from the state in which the leaf spring is held attracted to the end face of the core,
A spring-charged type that performs dot matrix printing by canceling the magnetic force of the permanent magnet and using the strain energy stored in the leaf spring to open the armature and selectively protrude the wire fixed to the armature. In the dot head, on the surface of the yoke plate,
A spring-charged dot head characterized by having a surface hardening layer with Hv=300-700 and a depth of 0.05-0.5 mm.