JPS60168663A - Wire dot head - Google Patents

Abstract

PURPOSE:To obtain the wire dot head of low power consumption, which is free of magnetic interference, by a method in which the first bypass magnetic part is provided close to a permanent magnet and also the second bypass magnetic part is provided close to a magnetic erasor coil. CONSTITUTION:Most of the magnetic flux of a coil 5 pass through a closed loop A returning to a core 2 through the core 2, a plunger 6, and the second bypass magnetic part 31. The remaining of the magnetic flux pass through a closed loop B returning to the core 2 through the core 2, the plunger 6, an upper yoke 4, the first bypass magnetic part 32, and a lower yoke 3. Even when the magnetic flux passes through the suction portion of the adjacent drive units, no interference takes place, and even when the number of concurrently opening wires is increased, the current value necessary for opening is constant, thereby reducing the amount of power to be consumed. Since the magnetic flux for increment of suction forces by the permanent magnet 1 between the core 2 and the plungsr 6 can pass through the closed loop C by the first magnetic part 32, there is not increment of suction forces after being built in and therefore, the releasing current of the plunger can be reduced.

Description

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

[Prior art]

In order to improve the printing speed of a dot printer, it is necessary to increase the response frequency of the wire dot head and at the same time reduce the power consumption of the wire dot head. The spring charge method has superior responsiveness compared to the electromagnetic attraction method, but as will be explained in detail below, in the conventional structure, it has been difficult to reduce power consumption due to the problem of magnetic interference.

FIG. 6 shows a conventional wire dot head. In the figure, permanent magnet 101. Core 102 and upper yoke 1υ4. The plunger 106 is caused by the magnetic flux generated by the permanent magnet 101 in the magnetic path composed of the lower yoke 103.
is attracted to the core 102, and the plate spring 107 is deformed. When the coil 105 wound around the core 102 is energized for a certain period of time in the direction of canceling the magnetic flux, the first langeer 106 is released, and at the same time, the lever 108 fixed to the leaf spring 107 rotates and the wire fixed to the tip of the lever 108 is rotated. Make 109 stick out. The wire 109 collides with recording paper (not shown) via the ribbon. When the current is interrupted, the plunger 106
is attracted to the core 102 again, and the wire 109 also returns to the standby position.

A wire dot head is constructed by arranging a plurality of wire drive units that operate as described above on the circumference. A problem unique to a spring charge head having such a configuration is a so-called magnetic interference problem in which magnetic flux wraps around adjacent magnetic circuits. To solve this problem,
A method has been adopted in which the wire drive unit is made independent for each wire on the magnetic circuit, but when configuring a multi-pin head, the distance between the drive units cannot be kept large due to dimensional constraints, so the effects of magnetic interference are completely eliminated. It's not gone.

For this reason, as the number of simultaneously released wires increases, the current value required for release also increases, resulting in a drawback that the power consumption of the head increases. In addition, since an independent wire drive unit is used, permanent magnets magnetized in the same direction are adjacent to each other when the drive unit is used alone and when the drive unit is incorporated into the head. The leakage permeance changes when it is incorporated, and even if it is set to an appropriate suction state when used alone, when it is incorporated, the suction force increases, which also has the disadvantage of increasing the open current. 〇 [Eye] This invention has been performed to improve the various drawbacks described above, and aims to realize a low power consumption wire tsut head without magnetic interference.

〔Example〕

The present invention will be explained based on an embodiment shown in FIGS. 1 and 2. Lower yoke, r! The core 2 is fixed to the upper yoke 4, the permanent magnet 1 is inserted between the upper yoke 4, and the fixed shaft 12 is used to fix the core 2. The leaf spring 7 and lever 8 are swaged together by a buttenger 6.

The lever 8 is made of a thin plate and has a tip wrapped around a wire 9, and the two are fixed by resistance welding, brazing, or the like. The leaf spring 7 is fastened by a fixed shaft 12 and fixed between the upper eyelet 4 and the presser plate 10. The part 10c of the presser plate 10 also has the function of perforating the lever 8 in the standby position.
A stopper 11 made of a rubber material is attached to the collision surface. The two electrode terminals 15 and 16 of the coil 5 wound around the core 2 have spring properties.

The wire drive unit 30 described above can be individually attached to and detached from the head body after assembly is completed. Incorporation into the head body is
The wire guides 18 to 23 are assembled into the head frame 13 in which the wire guides 18 to 23 have been previously assembled so as to engage the projections 10α of the presser plate 10, and at this time, the ring-shaped first bypass magnetic member 32 shown in FIG. 3 is inserted into the lower yoke 3. Permanent magnet 1. It is installed between the head frame 13 and the wire drive unit so as to be in contact with the upper yoke 4. Next, the second bypass magnetic member 31 shown in FIG. 3 is assembled into each coil so as to wrap around the coil 5, and the drive terminals 15 and 16 corresponding to the wiring pattern of the wiring board 17 are brought into elastic contact to generate electricity. connected. A rubber sheet 14 is interposed between the head frame 26 and the drive unit 40 to eliminate assembly problems due to length variations between the drive units and to prevent noise generation. Furthermore, the head is assembled by assembling the back cover 25 and elastically fixing it to the head frame 13 with the fixing spring 26.

Next move! Explain the work. The plunger 6 is attracted to the core 2 by the magnetic flux generated by the permanent magnet 1, and the leaf spring 7 is held biased. 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 attracted state, the lever 8 rotates in an arch direction, and the wire 9 protrudes.

The wire 9 collides with the recording paper via an ink ribbon (not shown) and forms a dot on the recording paper, after which the plunger 6 attracts the core 2 again and the wire 9 also returns to the waiting position.

The function of the bypass magnetic members 31 and 32 in this embodiment will be explained using FIG. 4. Most of the magnetic flux generated by energizing the coil 5 is #! Closed loop A1 shown in Figure 4
In other words, core 2. The remaining magnetic flux passes through the bypass magnetic member 31 of the plunger 6*tg2 and returns to the core 2, and the remaining magnetic flux flows into the closed loop B1, that is, the core 2. Plunger 6, upper yoke 4. First bypass magnetic member 32. lower yoke 6
Since the magnetic flux passes through the loop and returns to the core 2, the magnetic flux does not pass through the attracting portions of adjacent drive units and cause interference, so no magnetic interference occurs. Therefore, even if the number of wires that are simultaneously opened increases, only one current is required to open the wires, and the power consumption of the wire dot head can be reduced. Furthermore, when the wire drive unit is assembled into the head, the first bypass magnetic member 32 allows the magnetic flux corresponding to the increase in the attraction force between the core and the plunger due to the permanent magnet to be transferred to the closed loop Q shown in 4F4, that is, the permanent magnet 1. Upper yoke 4. First bypass magnetic member 32. Since it passes through the lower yoke 6, the core 2
．． The suction force between the plungers 6 does not change.

Therefore, since there is no increase in the suction force after assembly, the plunger release current can be reduced, and power consumption can be reduced.

In this embodiment, a head that uses a lever to drive the wire has been described, but a second embodiment that has the same effect even in the case of a head that does not use a lever will be described using FIG. 5. . In FIG. 5, the second bypass magnetic member 31 is shaped like a ring, which is common to each drive unit, and the other configuration is exactly the same as that of the above embodiment. Therefore, in addition to obtaining the same effects as the above-described embodiment, since the second bypass magnetic member 31 is common, work efficiency is improved, and there is an effect that leads to cost reduction of the second bypass magnetic member 31. As described above, according to the present invention, by providing the first and second bypass magnetic members in the permanent wire portion and the coil portion, magnetic interference is eliminated and a low power consumption head can be realized. Further, even if the wire drive unit (y) is set to the proper suction state in the state of being alone, the suction state does not change after installation, so the release current can be made small, and the effect is great.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a wire dot head showing an embodiment of the present invention, FIG. 2 is an exploded view of the drive unit, and FIG. 3 is a diagram showing the first and second bypass magnetic members and drive unit of the present invention. Figure 4 is an exploded view showing the positional relationship, Figure 4 is a sectional view of the drive unit showing the path of magnetic flux, and Figure 5 is an exploded view showing the positional relationship between the second bypass magnetic member and the drive unit showing an embodiment of the present invention. 6 are sectional views of a conventional wire dot head. 1... Core for permanent magnet 2... Core 3... Lower yoke 4... Upper yoke 5...・・・・・・Coil 6・・・・・・・・・Plunger 7・・・・・・Plate lock 8 ・・・・・・・・・Shino(=9・・・・・・・
...Wire 10 ... Pressing plate 11 ... Shaft stopper 12 ... Fixed shaft 51 ... Second bypass magnetic member 52 ...
...! lI! 1 (73 bypass magnetic members and above) Applicant Epson Corporation Suwa Seikosha Co., Ltd. Representative Patent Attorney Tsutomu Mogami Figure 3 σ Figure 5

Claims (1)

[Claims] A plunger fixed to a leaf spring, a permanent magnet that attracts the plunger and biases the front leaf spring, a degaussing coil that cancels the magnetic flux of the permanent magnet and releases the attracted state, and a degaussing coil that is driven by the leaf spring. In a wire dot head in which a plurality of wire drive units each consisting of a wire are arranged, a first bypass magnetic member is provided adjacent to the permanent magnet, and a second bypass magnetic member is provided adjacent to the degaussing coil. A wire dot head characterized by: