JPS5995161A - Printing head - Google Patents

Abstract

PURPOSE:To form a printing head having high responsiveness by suppressing the vibration in a vertical direction while using a light wt. lever having high rigidity in a drive direction, in a printing head constituted of a spring charge system, by providing a slit shaped guide for guiding the side surface of the lever. CONSTITUTION:A plunger 6 is attracted to a core 2 by the magnetic flux of a permanent magnet 1 in a stand-by state and a leaf spring is held under a distorted state. When a current is supplied to a coil for a definite time toward a direction for negating the magnetic field of the permanent magnet 1, the plunger 6 is relieved from the attracted state while a lever 8 is rotated by the elastic force of the leaf spring 7 to protrude a wire 9 and, after dots are printed onto recording paper, the plunger 6 is again attracted by the core 2 and the wire 9 is also returned to a stand-by position. Because the lever 8 made of a thin plate is guided at the side surface thereof by the slit 24b of a lever guide 24 and the vibration thereof to the plate thickness direction is prescribed, the lever is stably operated and responsiveness is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a print head for a dot printer. More specifically, the present invention relates to a so-called spring-charged dot head that drives a wire by releasing elastic energy stored in a leaf spring.

In order to increase the printing speed of a dot printer, it is necessary to increase the response frequency of the print head. The spring charge method operates more stably and has better responsiveness than the electromagnetic attraction method, but the conventional structure had the disadvantage that the inertial mass of the moving parts was large, which limited the ability to increase speed. In the conventional structure, an armature made of a block of magnetic material is fixed to the free end of a leaf spring, and a wire is further fixed to the tip of the armature, as can be seen in Japanese Patent Application Laid-Open No. 56-37176. was common. For this reason, the weight of the armature was large, and there was a limit to how much weight it could be made. To improve this point, as shown in Japanese Patent Publication No. 56-46989, a thin plate is made into a box shape, and while maintaining sufficient rigidity in the driving direction and perpendicular directions, the leaf spring and the wire are connected using a lightweight lever. is also known, but it has the disadvantage that the structure is complicated and the workability and assemblability are reduced.

In consideration of these points, the present invention aims to realize a highly responsive head by suppressing vibrations in the vertical direction while using a lightweight lever having high rigidity in the driving direction.

FIG. 1 is a sectional view of a print head showing an embodiment of the present invention, and FIG. 2 is an exploded view of a drive unit constituting the print head. The present invention will be explained based on both figures.

A core 2 is fixed to a lower yoke 3, a permanent magnet 1 is inserted between it and an upper yoke 4, and fixed using a fixed shaft 12. A lever 8 is swaged together with the free end of the leaf spring 7 by a plunger B. The lever 8 is made of a thin plate and has a wire 9 at the tip.
The two are fixed by resistance welding, brazing, etc. The leaf spring 7 is fastened and fixed between the upper yoke 4 and the presser plate 10 by a fixed shaft 12. Part 10C of presser plate 10
also has the function of stopping the lever 8 in its standby position, and a stopper 11 made of a rubber material is attached to the collision surface with the lever. The two electrode terminals 15 and 16 of the coil 5 wound around the core 2 have spring properties. The above-mentioned drive unit 30 can be individually attached to and detached from the head body after assembly and adjustment.

FIG. 3 is a perspective view of the lever guide 24, and FIG. 4 is a perspective view of the back cover 2.
5 is a diagram illustrating the head main body with part 5 removed. FIG. The lever guide 24 is provided with a wide slit 24α and a narrow slit 24b, and the end surface 24c has a step for engaging with the back cover 25. To assemble the drive unit and Toro 0 into the head body, after setting the wire guides 18 to 23 and the lever guide 24 on the head frame 13, place the part 106 of the presser plate into the slit 24α of the lever guide, and insert the protrusion 1oa into the slit 24α of the lever guide. This is done by inserting it into the guide hole 13α of the head frame. As shown in FIG. 4, the projection 10/
engages with the inner circumferential surface of the lever guide and positions the drive unit 30 in the radial direction. Lever 8 is reno-
The side surface is guided by the guide slit 24b, and vibration in the plate thickness direction is regulated. Electrical connections are made by pressing the corresponding notches of the wiring board 17 and the electrode terminals 15 and 16. A rubber sheet 14 is interposed between the head frame 13 and the drive unit to eliminate assembly problems caused by variations in length between the drive units and to prevent noise generation. After the guide hole 25a of the back lid is engaged with the projection 10h of the presser plate, the back lid 25 is fixed to the head frame by the fixing spring 26 to assemble the head.Next, the operation will be described. In standby state, permanent magnet 1
The plunger 6 is attracted to the core 2 by the magnetic flux, and the plate spring 7 is kept in a biased state. When the coil 5 is energized for a certain period of time in a direction that cancels the magnetic field of the permanent magnet 1, the plunger 6
is released from the suction state, the lever 8 is rotated by the elastic force of the plate spring 7, and the wire 9 is projected. The wire collides with the recording paper via an ink ribbon (not shown), and after printing a dot on the recording paper, the plunger 6 is sucked into the core 2 again, and the wire 9 also returns to the standby position.

According to the present invention, since the lever 8 is guided on the side by the wire 9h of the lever guide 24, the lever 8 is guided by the wire 9
It is possible to reduce the weight by using a thin plate that has high rigidity in the driving direction and low lateralization in the direction perpendicular to this. In other words, a thin plate made of a thin plate with low rigidity in a direction perpendicular to the plane of the paper in FIG. Since the vibration in the thickness direction is regulated by
It can operate stably and achieve high responsiveness even in the case of Furthermore, the lever guide also functions as a guide when assembling the drive unit into the head body, and has the effect of contributing to improved assembling efficiency.

As described above, according to the present invention, it is possible to realize a highly responsive head by suppressing unnecessary vibration of a lightweight lever.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a print head showing an embodiment of the present invention;
FIG. 2 is an exploded view of the drive unit, FIG. 3 is a perspective view of the lever guide according to the present invention, and FIG. 4 is a view showing the embodiment of FIG. 1 with the back lid removed. 1... Permanent magnet 7... Plate spring 8... Reno - 9... Wire 10... Holding plate 24... Lever guide and above Figure 1 Figure 3 Figure 4

Claims (1)

[Claims] A plunger fixed to a leaf spring, a permanent magnet that attracts the plunger and biases the leaf spring, a degaussing coil that cancels the magnetic flux of the permanent magnet and releases the attracted state, and a wire fixed to the leaf spring. 1. A print head comprising a wire drive unit consisting of a lever made of a thin plate that holds the print head, and a slit-shaped guide provided in the head body to guide the side surface of the lever.