JPS5989176A - Printing head - Google Patents

Abstract

PURPOSE:To suppress residual vibration and enable to print at high speed, by a method wherein a wire-driving unit comprised of a permanent magnet, a demagnetizing coil, a leaf spring, a lever with a wire fixed to the tip thereof and the like is provided with a stopper for determining a return position of an arm. CONSTITUTION:A core 2 is fixed to a lower yoke 3, the permanent magnet 1 is fixedly clamped between the lower yoke 3 and an upper yoke 4. The lever 8 and a plunger 6 are fixed to an end part of the leaf spring 7, and the wire 9 is fixed to the tip of the lever 8. The other end part of the leaf spring 7 is fixed between the upper yoke 4 and a holding plate 10. A coil 5 is wound around the core 2 to constitute a demagnetizing electromagnet. A part 10c of the plate 10 is used as a catch part at a stand-by position of the lever 8, and a stopper 11 formed of a rubber material is fitted to a colliding surface for the lever 8. A plurality of the thus constituted wire-driving units are fitted into the interior of a head frame 25 to constitute a printing head.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a print head of a wire dot printer.
C141 relates to a so-called spring-charge type print head that causes a wire to protrude using elastic energy stored in a leaf spring.

In order to improve the printing speed of a dot printer, it is necessary to increase the response frequency of the print head.

Although the spring charge method has a 1 dM, operation is more stable and has better response than the magnet attraction method, as mentioned below, in the conventional structure such as JP-A No. 6-37176, the It took a long time to come to rest, and there were limits to responsiveness. In other words, as shown in Fig. 4, which shows the change in conventional wire displacement over time, the wire returns to its original position after colliding with the recording paper, but at that time, it once crosses the standby position, returns to the standby position, and repeats the process several times in the same way. repeat the vibration. This not only increases the amount of time the wire rests in the standby position, but also has the disadvantage that when driven at high frequency, the motion of the motor system including the wire becomes unstable, and there is a limit to the responsiveness of the head. was. The present invention aims to suppress the above-mentioned residual vibration and realize high responsiveness.

The present invention will be explained with reference to an embodiment shown in FIGS. 1 and 2. FIG. 1 is a sectional view of the head, and FIG. 2 is an exploded view of a plurality of drive units attached to the head. In both figures, the core 2 is fixed to the lower yoke 3, and the permanent magnet 1 is sandwiched between it and the upper yoke 4 and fixed using the fixed shaft 12.A lever 8 is attached to the free end of the leaf spring 7, and a plunger 6 (in one piece) to be shunned. The lever 8 is made of a thin plate and has a shape in which a wire 9 is wound around the tip thereof, and both are fixed by resistance welding, brazing, or the like. The leaf spring 7 is fastened and fixed by a fixed shaft 12 between the upper yoke 4 and the presser plate. The two electrode terminals 15 and 16 of the coil 5 wound around the core 2 have spring properties.

The above-mentioned vibration unit 30 can be attached to and detached from the head body after assembly and adjustment. The assembly into the head body is carried out by engaging the protruding side a of the drive unit with the guide hole 13α of the head frame 1:(), and then press-contacting the electrode terminals 15 and 16 with the corresponding pattern of the wiring board 17 to establish an electrical connection. A rubber sheet 14 is interposed between the head frame 13 and the drive unit to prevent problems during assembly due to variations in length between each drive unit and to prevent the generation of noise.Next, the back cover 5 is inserted. The head is assembled by elastically fixing it to the head frame 1:3 with the fixing spring 26.The lever guide 2A has a slit that guides the side surface of the lever 8, and the lever guide 2A has a slit that guides the side surface of the lever 8. In addition to preventing vibration in the vertical direction, it also has a positioning function when installing the vibration unit.
(lc is used as a stopper when the lever 8 is in the standby position, and a stopper 11 made of a rubber material is attached to the collision surface with the lever 8.

Next, the operation will be explained. The plunger 6 is attracted to the core 2 by the magnetic flux of the permanent magnet 1 and holds the leaf spring 7 in a biased manner. When the coil 5 is energized in a direction to cancel the magnetic field, the attracted state is released and the lever 8 is rotated by the elastic force of the leaf spring 7.
The wire 9 fixed at the tip is made to protrude. The wire 9 collides with an ink ribbon and recording paper (not shown) to form dots.

After the current supply is cut off, the plunger 6 is attracted again, and the wire 9 also returns to the standby position. At this time, the core 2 and plunger 6 collide with l'! At the same time, the lever 8 also collides with the stopper 11. Therefore, as shown in FIG. 3, which shows the change in wire displacement over time in case J of this embodiment, the wire 9 does not go too far beyond the standby position and quickly comes to rest at the standby position with a very slight shivering. Therefore, the motion system including the wire operates stably and moves without disturbance, especially during high frequency drive, so high responsiveness can be achieved.

In addition, the retaining surface 11''j of the presser plate l (1 and the stopper 11
As shown in Figure 1, each slope is
By moving C11 vertically, lever 8
ljl'l in the front and back (horizontal direction in Fig. 1)
I can lick it. Therefore, due to errors in parts machining accuracy, etc.
Even if the standby position of the lever 8 is incorrect, the stop lever 11
You can set it in the optimal position by moving it vertically.

In this embodiment, the stopper IJ is made of polyurethane and has sufficient hardness, impact resistance, and abrasion resistance to restrict the stroke of the lever in the standby position.

According to the structure shown in the present embodiment, the impact caused by the impact between the core 2 of the suction part and the plunger 6 is alleviated, so that the wear and deformation of this impact part is significantly reduced.

Furthermore, since there is no residual vibration of the lever 8 and there is no disturbance in the movement of the wire during high frequency motion, the bending load on the wire is reduced and the wire life is extended.

As described above, according to the present invention, a long-life, high-responsive head can be realized.

[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 showing its drive unit, FIG. 3 is a diagram showing temporal changes in wire displacement of the print head of the present invention, and FIG. 4
The figure shows temporal changes in wire displacement in a conventional example. 1: Permanent magnet 2: Core 5: Coil 6: Plunger 7: Leaf spring 8 Nilever 10: Holder plate Applicant Epunun Co., Ltd. Agent Patent Attorney Saturn Senior Affairs

Claims (1)

[Claims] 1. A leaf spring connected to a shear wire is biased by an attractive force of a permanent magnet, and the biased state is released by energization of a degaussing coil that cancels the magnetic flux of the permanent magnet. In a spring-charged print head in which a wire is driven by elastic energy stored in a leaf spring, the wire is connected to the leaf spring via a lever, and a stopper abuts near a joint between the lever and the wire in the biased state. A print head characterized by being provided with. 2. The print head described in item 1 of qi) of Patent H111, characterized in that the stopper has a t-shaped surface portion.