JPS62104770A - Connecting of drive arm and movable yoke - Google Patents

Abstract

PURPOSE:To increase the driving efficiency and durability of a printing head by enhancing the bonding strength and by constantly stabilizing the response characteristics of each drive arm by using mechanical connection and bonding together in connecting a drive arm with a movable yoke in a spring-release type printing head. CONSTITUTION:A bush 10 is fixed to the through hole 6a of a drive arm by caulking or pressing, and a movable yoke 11 is passed through the through hole 8a of a yoke plate 8. A shaft 11a is inserted into the hole 10a of the bush 10, and a drive arm assembly in a loosely combined state is set on a tool 19 and an adhesive 12 is charged into the hole 10a of the bush 10. The angle thetaof a mount face 19a to the horizontal face is set up to be equal to the rocking angle of a drive arm 6. The back end face of the yoke 11 can make a face- contact with the end face 13a of a core 13 in a non-conducting retracting state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of coupling a drive arm and a movable yoke in a spring release type print head.

[Prior Art] A spring release type print head is disclosed in, for example, Japanese Patent Application Laid-Open No. 55-1541.
As disclosed in Japanese Patent No. 78, the drive arm that drives the printing element is biased backward by a permanent magnet against its elastic force, and the magnetic field of the permanent magnet is canceled out by the excitation of the drive coil to maintain the biased state. The drive arm is released and the drive arm moves forward with its own elastic force, thereby driving the printing element.

Normally, the drive arm is equipped with a movable yoke at a position facing the core around which the drive coil is wound, but conventionally, this movable yoke is mechanically connected directly to the drive arm by caulking or press-fitting. , or was fixed using adhesive.

[Problems to be Solved by the Invention] When the movable yoke is directly connected to the drive arm by mechanical connection by caulking or press-fitting, the connection strength between the two is sufficient, but the drive arm may be damaged due to processing distortion during connection. It may undergo deformation such as warping. When the drive arm is warped, the positional relationship of the movable yoke with respect to one end surface of the core varies, and this results in variation in response characteristics for each drive arm.

If the movable yoke is directly attached to the drive arm with adhesive, the drive arm is less likely to warp;
There was a problem that the bonding strength was insufficient. This is because, according to the conventional simple adhesive structure, the adhesive surface between the drive arm and movable yoke is parallel to the plate surface of the drive arm, so the deformation of the drive arm during printing operations causes the adhesive on the adhesive surface to be peeled off. This is because the bonding area itself is small because it is subjected to repeated force.

Furthermore, in known spring-release type printheads, the movable yoke moves in an arc around the support portion of the drive arm, so that when the movable yoke is drawn to the core, the edge of the rear end surface locally aligns with the core. Abuts against the end face. This has resulted in decreased magnetic efficiency and durability.

SUMMARY OF THE INVENTION An object of the present invention is therefore to provide a bonding method that uses both mechanical bonding by caulking or press-fitting and bonding by adhesive to take advantage of the respective advantages of both.

Another object of the present invention is to provide a coupling method that allows the movable yoke to be easily coupled into a mounting relationship in which the rear end surface of the movable yoke is in substantial surface contact with the end surface of the core.

[Means for Solving the Problems] A feature of the method of coupling the drive arm and the movable yoke according to the present invention is that mechanical coupling by caulking or press-fitting and bonding with an adhesive are used in combination. First, a bushing having a through hole is fixed by caulking or press fitting into a through hole of a drive arm supported in a cantilevered manner. The movable yoke fixed to the bushing has a shaft portion smaller in diameter than the through hole formed in advance on the surface facing the bushing, and this shaft portion is loosely aligned with the through hole of the bushing. Then, the movable yoke, which is in a loose state with respect to the bushing, is held in a desired mounting posture via a jig, and in this state, adhesive is injected into the through hole, so that the movable yoke adheres to the bushing. be done.

[Example] First, the structure of a print head to which the bonding method according to the present invention is applied will be explained.

In FIG. 1, a printing wire 1 is slidably passed through a wire guide 2. As shown in FIG. It goes without saying that a plurality of printing wires 1 are actually provided and are supported by a plurality of wire guides. Printing wire 1
A printing pin 3 is fixed to the rear end, and the printing wire 1 is urged backward (downward in FIG. 1) by a return spring 4 inserted between the printing pin 3 and the wire guide 2. There is.

Behind the printing wire 1, a drive arm assembly consisting of a stopper plate 5, a drive arm 6, a spacer ring 7, and a yoke plate 8 is arranged. They are integrated by screws 9 that pass through and are screwed onto the yoke plate 8. Stopper plate 5. The drive arm 6 and spacer ring 7 are made of non-magnetic material, and the yoke plate 8 is made of magnetic material. A bushing 10 is fixed to the middle part of the drive arm 6.
A movable yoke 11 made of a magnetic material is fixed to the yoke 1 through an adhesive 12. The bush 10 has a through hole 10a formed in its center, and the movable yoke 11 has a cylindrical shape, and a shaft portion 11a having a smaller diameter than the through hole 10a is formed protruding from one end surface of the movable yoke 11. ing. Further, a peripheral wall portion 11b is provided protruding from the outer peripheral portion of the movable yoke 11, and the outflow of the adhesive 12 is restricted by this peripheral wall portion 11b.

As shown in the third figure, the drive arms 6 are arranged radially at equal angular intervals 1, and are connected together at their respective rear ends. A bushing 10 is provided in the middle of the drive arm 6.
A through hole 6a for attaching is provided. The yoke plate 8 has a concentric through hole 8a through which the movable yoke 11 can pass, corresponding to the arrangement of the drive arm 6.

The stopper plate 5 also has a shape substantially similar to the yoke plate 8 shown in FIG.

Behind the drive arm assembly is a U-shaped core 13.
One end surface 13a thereof is arranged to face the movable yoke 11. A permanent magnet 14, a magnet plate 15, and a spacer ring 16 are sandwiched between the other end surface 13b of the core 13 and the yoke plate 8. Further, a drive coil 17 is wound around a part of the core 13.

The core 13, magnet plate 15, and spacer ring 16 are made of magnetic material. Therefore, the magnetic plate 15. A magnetic path 18 for the permanent magnet 14 is formed by the spacer ring 16, the movable yoke 11, and the core 13, and the movable yoke 11 is attracted to the end surface 13a against the elastic force of the drive arm 6 when no current is applied. When the drive coil 17 is energized, the magnetic flux from the permanent magnet 14 passing through the magnetic path 18 is canceled out. As a result, the magnetic attraction of the movable yoke 11 to the one end face 13a of the core is released, and the drive arm 6 moves forward by its own elastic force to move the printing wire 1 forward against the spring force of the return spring 4, as shown in the figure. Dots are formed on print media that does not.

Here, a method of coupling the drive arm 6 and the movable yoke 11 according to the present invention will be described in detail.

First, as shown in FIG. 5(a), the drive arm 6
A bushing 10 is fixed to the through hole 6a by caulking or press fitting. Next, in this embodiment, as shown in FIG. 5(b), the stopper plate 5.degree. drive arm 6, spacer ring 7, and yoke plate 8 are stacked and integrated with screws 9. After that, moveable yoke 1
1 from the through hole 8a side of the yoke plate 8 and insert the shaft portion 11
a into the through hole 10 of the bushing 10. At this stage, the shaft portion 11a of the movable yoke 11 can move relatively freely relative to the through hole 10a of the bush 10.

Therefore, as shown in FIG. 5(C), the drive arm assembly is set on the jig 19 with the movable yoke 11 inserted. The jig 19 is formed with a mounting surface 19a on which the rear end surface of the movable yoke 11 is placed, and this mounting surface 19a is inclined at an angle θ with respect to the horizontal plane. Therefore, the movable yoke 11 has its axis L2 aligned with the bush 10.
It is held in an attitude tilted by an angle θ with respect to the axis L1 of. Then, the adhesive 12 is injected into the through hole 10a of the bushing 10 while the movable yoke 11 is held in the above-described position via the jig 19.

The adhesive 12 injected into the through hole 10a
, the shaft portion 11a, the lower surface of the bushing 10, and the movable yoke 1.
Although the movable yoke 11 penetrates into the gap formed between the movable yoke 11 and the upper surface of the movable yoke 11 due to capillary action, the peripheral wall portion 11b formed at the periphery of the upper surface of the movable yoke 11 restricts its outflow to the outside.

As the adhesive 12 hardens, the movable yoke 11 becomes
As shown in FIG. 2, the rear end surface is fixed to the plate surface of the drive arm 6 at an angle θ. Angle θ
is set to be substantially equal to the swing angle of the drive arm 6, so that the rear end surface of the movable yoke 11 substantially faces the end 13a of the core 13 in the retracted state when no current is applied. (See Figure 1).

FIG. 6 shows a movable yoke 20 according to another embodiment, in which a groove 20c is formed on the outer peripheral surface of the shaft portion 20a. According to this movable yoke 20, since the adhesive enters the groove 20c, it becomes difficult to peel off. Note that 20b is a peripheral wall for controlling the outflow of adhesive.

The movable yoke 21 shown in FIG. 7 has a rear end face cut diagonally at an angle θ.
is fixed in such a manner that its axis substantially coincides with that of the bushing 10. The other configurations are completely the same as the movable yoke 11.

In the above embodiment, the drive arm 6 is connected to the stopper plate 5, the spacer ring 7, or the yoke plate 8.
It is not an essential requirement of the present invention to be integrated with. Moreover, in order to increase adhesive strength, a groove may be formed in the through hole 10a of the bushing 10.

[Effects of the Invention] According to the above-described method of coupling a drive arm and a movable yoke according to the present invention, the following effects can be achieved.

Although the drive arm is deformed in an arched manner during operation, since the adhesive is formed between the rigid bush and the movable yoke, the adhesive will not come off due to this effect. The adhesive surface between the through hole of the bushing and the shaft of the movable yoke is parallel to the load acting on the movable yoke (the force that pulls the movable yoke backwards. This is the force that tries to peel off the adhesive). , and the sowing area increases accordingly.
Sufficiently high adhesive strength can be obtained.

When the bushing is connected to the drive arm by caulking or press-fitting, the drive arm may warp, but this accuracy error is completely absorbed during bonding, and the movable yoke is fixed to the bushing with its rear end surface uniformly aligned. Ru. This makes the response characteristics of each drive arm constant.

Furthermore, if the mounting surface of the jig that receives the rear end surface of the movable yoke is inclined at an angle substantially equal to the swing angle of the drive arm, the rear end surface of the movable yoke will be substantially aligned with the end surface of the core when no power is applied. As a result, the drive efficiency and durability of the print head are improved.

If a concave groove is formed on the outer circumferential surface of the shaft portion of the movable yoke or on the inner circumferential surface of the bushing, the bonding strength of the adhesive can be further improved.

Furthermore, if the peripheral wall is formed to protrude from the outer periphery of the end surface of the movable yoke, troubles due to adhesive leakage will not occur.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the main part of a print head in which a movable yoke is fixed to a drive arm by the coupling method according to the present invention, Fig. 2 is a side view showing the mounting posture of the movable yoke with respect to the drive arm, and Fig. 3 is a drive FIG. 4 is a reduced front view of the arm, FIG. 4 is a reduced plan view of the stopper plate, FIGS. The front view and FIG. 7 are sectional views showing a structure for attaching a movable yoke to a drive arm according to still another embodiment. 6... Drive arm 6a... Through hole 10...
... Bush 10a... Through hole 11.20.
21・・・・・・・・・・・・Movable yoke 11a
, 20a, 21a...Shaft portions 11b, 20b, 2
1b...Surrounding wall portion 20c...Concave groove 19...Jig 19a...Placement surface θ
...More than the inclination angle of the mounting surface

Claims (5)

[Claims] (1) A bushing having a through hole is fixed to the through hole of the drive arm supported in a cantilevered manner, and a shaft portion with a smaller diameter than the through hole is formed protruding from the surface of the movable yoke that faces the bushing. Then, the shaft portion of the movable yoke is loosely engaged with the through hole of the bushing, and the movable yoke that is loosely engaged with the bushing is held in a desired mounting posture via a jig, and in this state. A method for coupling a drive arm and a movable yoke, comprising injecting an adhesive into the through hole and fixing the movable yoke to the bushing with the adhesive. (2) The jig has a mounting surface on which the rear end surface of the movable yoke is placed, and this mounting surface is inclined at an angle substantially equal to the swing angle of the drive arm. A method of coupling a drive arm and a movable yoke according to claim 1. (3) A method for coupling a drive arm and a movable yoke according to claim 1, wherein a groove is formed in at least one of the outer circumferential surface of the shaft portion of the movable yoke or the inner circumferential surface of the bush. (4) The drive arm and movable yoke according to claim 1, wherein the movable yoke is integrally formed with a peripheral wall portion protruding from the peripheral edge of the opposing surface to prevent the adhesive from flowing out. Combined structure with. (5) The coupling structure of the drive arm and the movable yoke according to claim 1, wherein a plurality of the drive arms are arranged in a radial manner and are integrally connected at the outer peripheral portion thereof. .