JPH023328A - Method of reducing stress of printing wire and printing head with reduced stress of printing wire - Google Patents

Abstract

PURPOSE:To enable employment of an extremely slender printing wire having a uniform section and being low-cost by specifying the relationship between a printing drive period of a printing wire driving element and a natural frequency period of a span of the printing wire of which the support point is a guide hole part and the fixed point is a fixed part of the wire with a lever body, and by suppressing the vibration of the printing wire positively. CONSTITUTION:A printing wire 2 becomes a vibration system of a span of which the fixed point is a fixed part 20 of the wire and the support point is a first axial bearing part 62 directed to the fore end part of the wire or a wire guide 61 if the wire has not the bearing part 62. By setting the relationship between a primary natural frequency period TW of this vibration system and a drive period TF of printing as TF=(N+0.5)+0.2XTW (where N is an integer and N >=3), the vibration delta of the printing wire 2 of the span is suppressed at the time of successive printing, since the vibration generated in the previous printing becomes reverse in phase to the vibration generated in the current printing at that time and they cancel each other. In printing at intervals of one dot as well, subsequent printing is conducted after the vibration delta of the printing wire 2 is attenuated and therefore the vibration is not increased. According to this constitution, an extremely slender wire being weak in strength but having a uniform section can be employed and the lifetime thereof can be prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wire dot printer print head capable of high-definition printing, which has a plurality of lever bodies to which uniform cross-section printing wires are fixed. The present invention relates to a printing wire stress reduction method suitable for extending the service life and a printing wire stress reduction print head.

[Conventional technology]

Conventional devices press felt against the printing wire, as described in Utility Model Application No. 58-10465, or actually
As described in Japanese Patent No. 57-47353, a method has been devised in which vibration of the printing wire is suppressed by providing a vibration damping guide to reduce stress on the printing wire.

[The invention tries to solve i! l! [Problem] In recent years, there has been a strong demand for high-definition printing of Chinese characters for print heads that print by hitting paper with a printing wire. In this case, the number of printing wires inevitably increases, and the diameter of the printing wires ranges from φ0.35nn to φ0.
The wires are becoming extremely thin, reaching the 0.2 side. For this reason, the printing wire becomes weak in strength, so ≧ φ0.2m on the striking surface of the paper.
However, in other parts, a stepped or tapered printing wire with a diameter of 0.3rR, which is high in cost but strong in strength, is used.

Although the conventional technology has the effect of dampening the vibration of the printing wire caused by the printing operation, it does not have the effect of actively suppressing the occurrence of vibration itself during the actual printing operation, and the print head using the above-mentioned ultra-thin wire Even in this case, the stepped or tapered printing wire described above had to be used.

The purpose of the present invention is to provide a printing wire stress reduction method and printing wire stress reduction method that makes it possible to use an inexpensive ultra-thin printing wire with a uniform cross section by actively suppressing the vibration of the printing wire during printing operation. The purpose is to provide a print head.

[Means to solve the problem]

The above object is to provide a wire guide having a guide hole, a printing wire whose tip end is inserted into the guide hole, one end of which is fixed, the other end is a free end, and the rear end of the printing wire is fixed to the free end. The printing wire drive unit includes a lever body and a printing wire drive unit consisting of an electromagnet and a permanent magnet arranged opposite to the lever body, and the printing wire drive unit drives the lever body to cause the tip end of the printing wire to protrude from the guide hole. In the method for reducing stress on a print wire of a print head that performs printing, the print drive period TF of the print wire drive unit and the span of the print wire in which the guide hole is a support point and the fixation point with the lever body are a fixed point. This is achieved by a printing wire stress reduction method in which the relationship between the normal vibration period TW of

Also, the natural vibration period T of the printing wire in the above relational expression
When at least one printing wire bearing part is provided between the wire guide and the printing wire fixing part of the lever body, the printing wire fixes the fixing part to the lever body as a fixing point. The first printed wire bearing on the side has a natural vibration period of the span with the support point at .

In order to achieve the above object, the print wire stress reducing print head according to the present invention is provided such that the span between the wire guide and the fixed portion of the print wire is set to the drive period TF.
A natural vibration period T that satisfies the above relational expression showing the relationship between
Arrange it so that it becomes w.

Further, at least one bearing section is provided between the fixed section of the printing wire and the wire guide, and the bearing on the fixed section side defines the span between the section and the fixed section of the printing wire according to the relational expression. They may be arranged so as to have a satisfying natural vibration period TW.

Furthermore, the wire guide or the first bearing, which serves as a support point for the natural vibration period TW, contacts the side of the part opposite to the fixed part when the lateral vibration amplitude of the printing wire reaches a predetermined value. It is preferable to provide a vibration isolating means for suppressing the above amplitude increase.

Preferably, the bearing is in a floating state with respect to the axial direction and the diametrical direction of the printing wire.

[Effect]

In the above configuration, the printing wire uses the fixing part of the printing wire as a fixing point, and the first bearing in the axial direction toward the tip of the printing wire serves as a support point, or if the bearing does not have a part, the wire guide serves as a support point. The relationship between the primary natural vibration period TW of this vibration system and the printing drive period TW is 1゛F=(N+0.5)±0.2 XTW (however, N is an integer and is N22). By doing this, the vibration of the printing wire in the span is such that during continuous printing, the vibration that occurred during the previous printing and the vibration that occurred during the current printing are in opposite phase, canceling each other out and suppressing the vibration, even when printing every other dot. By setting N≧3, the next printing is performed after the vibration of the printing wire is attenuated, which works to prevent vibration from increasing.

Further, when the lateral vibration amplitude of the printing wire reaches a predetermined value, the vibration isolating means comes into contact with the printing wire and functions to suppress further increase in the amplitude.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a side view showing the overall structure of a print head according to an embodiment of the present invention, with a partial cross-sectional view.

In FIG. 1, the leaf spring body 5 has a structure in which a plurality of tongues 53 extend from a base part 52 made of an annular plate toward the annular center of the base part 52 so as to be regularly adjacent to each other. ing. On the tip side of the tongue piece 53, print wires 2. A lever assembly 1 to which a lever body 3 and a suction member 4 are fixed is fixed.

One end of the vertical spring wire 51 is fixed to the vertical spring support plate 6, and the other end is fixed to the suction member 4. The vertical spring wire 51 intersects the center line of the tongue piece 53 vertically without contact, and defines the axial rotation center of the printing wire 2 of the lever assembly 1 at the crossing point, and the tongue piece 53 of the printing drive cycle. The vertical spring wire 51 receives the secondary vibration as an axial tensile and compressive force and prevents it. The core 13 has an insertion part 133 for the coil 9 corresponding to each lever assembly 1, and has a core suction surface 132 on its upper surface that attracts the suction member 4 of the lever assembly 1.
Each core 13 is integrated at a core outer peripheral portion 131. A permanent magnet 11. is placed on the core outer peripheral portion 131. yoke 1
0 are fixed to the casing 12 in a stacked state. The suction surface 132 of the core 13 and the upper surface of the yoke 10 are finished on the same plane. A terminal 92 of the coil 9 is drawn out from the casing 12 to the outside of the print head. yoke 1
On the upper surface of the side yoke 8.0, the side yoke 8. Spacer 7, leaf spring body 5. Vertical spring support 6. The casings 15 are laminated and fixed to the casing 12 to which the coil 9 and the like that drive the lever assembly 1 are fixed by means such as screws (not shown).

A wire guide 61 is fixed to the casing 15 to restrain the printing wire 2 so as to be movable back and forth in the axial direction thereof. The bearing 62 is not fixed to the casing 15 and is floating.

The base portion 52 of the leaf spring body 5 is sandwiched between the spacer 7 and the vertical spring support 6, and serves as a fixed end of a tongue piece 53 extending from the base portion 52.

The suction member 4 is inserted into the groove of the sight yoke 8. And York 10. Side yoke 8. The core suction surface 132 attracts the core suction member 4 .

(1) At this time, the leaf spring effective elastic portion 54 deforms and stores strain energy, generating a biasing force that causes the lever assembly 1 to return.

Next, the operation will be explained. A current corresponding to the recorded image is passed through each coil 9, the magnetic flux generated by the permanent magnet 11 is canceled by the core attraction surface 132, the magnetic attraction force is reduced, and the biasing force of the effective elastic portion 54 of the leaf spring becomes the magnetic attraction force. The strain energy stored in the leaf spring effective elastic portion 54 is released, and the lever assembly 1 rotates around the intersection of the tongue piece 53 and the vertical spring wire 51, causing the printing wire 2 to protrude from the wire bearing 61. , a printing medium such as an ink ribbon or printing paper (not shown) is struck to print dots.

Immediately before or after the printing wire 2 strikes the printing medium, the current in the coil 9 is cut off, and the lever assembly 1 returns to the initial position due to the reaction force to the printing medium and the restored magnetic attraction force.

The printing wire 2 in this embodiment is an ultra-fine wire with a uniform cross section of 0.2 strokes in diameter. The hole diameter of the wire guide 61 and bearing 62 of the printing wire 2 is 0.22 mm in diameter. The bearing 62 restrains the motion component of the printing wire 2 perpendicular to the axial direction. Further, the bearing 62 is floating with respect to the casing 15, and when the printing wire 2 vibrates, the bearing 62 is floating in the axial direction of the printing wire 2, so that the axial position changes and the bearing 62 moves the printing wire 2 whose position is a node. The resonance period of the transverse vibration is not constant and the vibration does not increase. In addition, since the printing wire 2 is floating in the shaft diameter direction, the vibration period of only the printing wire 2, which does not use the bearings 6 and 2 as a node, due to the difference between the bearing and the hole diameter.
Since the printing wire 2 and the bearing 62 come in contact with each other and have two different vibration periods, one being a vibration period with this as a node, resonance is less likely to occur. Floating the bearing 62 in this manner has the effect of preventing excessive vibration.

FIG. 2 is an enlarged view of the portion of FIG. 1 that performs the printing operation. When the lever assembly 1 is operated continuously, the printing wire 2
The printing wire 2 vibrates between the fixed portion 20 to the lever body 3 and the bearing 62. At this time, stress is highest in the printing wire 2 at the fixed portion 20 of the printing wire, and an increase in vibration δ causes the printing wire 2 to break from the fixed portion 20.

In FIG. 3, the vibration of the printing wire 2 between the fixed portion 20 and the bearing 62 is modeled as vibration of a beam with one end fixed and the other end supported.

The natural vibration period TW of this model is determined as follows.

If the material of the printing wire 2 is tungsten carbide, the longitudinal elastic modulus E = 4700000kg/ff
l Specific gravity r = 0.0125kg/air cross-sectional area
A=0.01. ZXπd gravitational acceleration
g=981■/S2, and if it is a negative-order vibration, the vibration coefficient λ=3.93, and if the span L of this vibration system is 9.3 nwn, the natural vibration period TW is 116 μs.

Through experiments, the natural vibration period TW of the printing wire 2 between the fixed point 20 and the bearing 62 was determined to be 118 μS, which is M
] It agrees well with the calculated value.

FIG. 4 shows the relationship between the natural vibration period TW of the printing wire 2 with respect to the driving period T''F and the ratio of the maximum amplitude of the printing wire 2 during single printing to the maximum amplitude of the printing wire 2 during continuous printing. This is what I asked for.

1611 period '1'F is the natural vibration period T of the printing wire 2
When it becomes an integral multiple of W, the amplitude of the printing wire 2 becomes excessive. The driving period TF is (N+0.3)×TW to (N+
0.7) In the case of TW (where N is an integer), the amplitude of the printing wire 2 does not increase even when continuous printing is performed compared to during single printing.

FIGS. 5(-) to 5-Y show the vibration of the printing wire 2 between the fixed portion 2o of the printing wire 2 and the bearing 62, with time on the horizontal axis.

FIG. 5(a) shows the vibration when the drive period TF is an integral multiple of the natural vibration period TW of the printing wire 2. FIG.

The amplitude increases because the vibrations caused by the printing on the sales counter overlap in the same phase.

On the other hand, FIG. 5(b) shows the vibration when the driving period '1゛F is (N+0.5)-0°2 times the natural vibration period TW of the printing wire 2 (N is an integer). . -The vibrations caused by the printing on the second sales outlet overlap in opposite phase to the residual vibration caused by the printing on the sales opening, so the vibration disappears.

For this reason, even during continuous printing, the amplitude of the printing wire 2 does not increase compared to instantaneous single printing. Therefore, even when repeated printing is repeated, stress on the fixed portion 20 of the printing wire 2 does not increase, and the life of the printing wire 2 can be extended. .

Further, FIG. 5(c) shows the case of continuous printing with every - print. The relationship between the driving period TF and the natural vibration of the printing wire 2 ±0.2 period TW is TF= (N+0.5) X1'
If w (N is an integer) is - every other drive cycle ±0.
4 TF' = (2N+1) × TW, T'
When F' becomes close to an integral multiple of TW, vibration tends to increase.

Therefore, by setting N≧3 as shown in Fig. 5(c), if the next printing is performed after the vibration generated in the previous printing has subsided sufficiently, even continuous printing every - Vibration should not be excessive.

From the above, the drive period TF of the lever body 3 is 379μ.
A print head of S φO, 2 mm carbide uniform cross-section wire was manufactured.

TF= (N+0.5)×TW −・−(
2) (however, N-3), 379=3.5×TW...
・(3) 3.5 Therefore, the natural vibration period TW of the printing wire is 109μS
becomes.

Next, when the length of the printing wire 2 from the fixed portion 20 to the bearing 62 is determined from equation (1), L=9+nm.

When we conducted a life test by continuous printing using the print head with the position of the bearing 62 determined in this way, we found that 2X
Printing of 108 dots or more was possible.

When a similar life test was conducted using a print head with L=1.2 mm and TF=3×TW, the print wire 2 broke at the fixed portion 20 of the print wire 2 at 108 dots.

From the above, the relationship between the drive period TF and the natural vibration period TW of the printing wire 2 is TF= (N+0.5)±0=-1-TW
""" (5) (where N is an integer and N≧3), vibration of the printing wire 2 can be reduced.

In the embodiments described above, an explanation is given of the case where at least one bearing is provided between the wire guide 61 and the fixed part 20 of the printing wire 2, but the wire guide 61 and the fixed part 20 of the printing wire 2 Even if there is no other bearing between the wire guide 61 and the printing wire 2, the relationship between the natural vibration period TW and drive period TW of the span between the wire guide 61 and the printing wire 2 as shown in equation (5) will improve the printing wire 2. Vibration can be reduced.

FIG. 6 is a sectional view of a print head showing one embodiment of the printing spatula 1 for reducing printing wire stress, and FIG. 7 is a perspective view thereof.

On the side of the fixed portion 20 of the printing wire 2 of the bearing 62, there is a part that does not come into contact with the printing wire 2 when the printing wire 2 moves forward and backward in the axial direction.
When the printing wire 2 vibrates, a vibration guide (vibration isolating means) 63 is formed whose outer periphery comes into contact and reduces the vibration.

This eliminates the need to install a vibration-proofing guide separately from the bearing, improves installation accuracy, and reduces the processing required for installation.
It has the effect of omitting processes and improving productivity.

〔Effect of the invention〕

According to the present invention, which is configured as described above, the following effects can be achieved.

Since the vibration of the printing wire can be reduced, evenly-disconnected thin wires with weak strength can be used as printing wires.
This has the advantageous effects of reducing the cost of the print head and extending the life of the print wire.

[Brief explanation of the drawing]

Fig. 1 is a side view of the overall structure of a print head according to an embodiment of the present invention, Fig. 2 is a partially enlarged view of Fig. 1, Fig. 3 is a vibration model diagram of a printing wire, and Fig. 4 is a drive cycle TF and printing A diagram showing the relationship with the wire's natural vibration period TW, Figures 5(a) to 6 are diagrams showing the vibration state of the printing wire, and Figure 6 is a cross section of the print head showing an embodiment of the printing wire stress reduction print head. FIG. 7 is a perspective view of FIG. 6. DESCRIPTION OF SYMBOLS 1... Lever assembly, 2... Printing wire, 3... Lever body, 4... Attraction member, 5... Leaf spring body, 9 Coil, 1-1... Permanent magnet, 20... Fixed part, 61...
・Wire Ga Part I Concave Part 2 Visit Part 3

Claims (1)

[Claims] 1. A wire guide having a guide hole, a printing wire whose tip end is inserted into the guide hole, and a rear end of the printing wire with one end fixed and the other end free. a lever body to which a part is fixed; and a printing wire drive unit including an electromagnet and a permanent magnet arranged opposite to the lever body, and the printing wire drive unit drives the lever body to move the tip of the printing wire to the guide. In a method for reducing stress on a print wire of a print head that prints by protruding from a hole, the print drive cycle T_F of the print wire drive unit and the print wire use the guide hole portion as a support point and fix the fixed portion to the lever body. The relationship between the natural vibration period T_W of the span defined as a point is T_F=(N+0.5)^±^0^. ^2×T_W (N is an integer and N≧3). A method for reducing stress in a printing wire. 2. At least one printing wire bearing part is provided between the wire guide and the printing wire fixing part of the lever body, so that the printing drive cycle T_F of the printing wire driving part and the printing wire are connected to the lever body. The relationship between the fixed part and the natural vibration period T_W of the span with the fixed part as the fixed point and the first printing wire bearing part on the fixed part side as the supporting point is T_F=(N+0.5)^±^0^. 2. The printing wire stress reduction method according to claim 1, wherein ^2×T_W (where N is an integer and N≧3). 3. A wire guide having a guide hole, a printing wire whose tip end is inserted into the guide hole, and a lever body having one end fixed and the other end free, and a rear end of the printing wire fixed to the free end. and a printing wire drive section consisting of an electromagnet and a permanent magnet arranged opposite to the lever body, the printing wire drive section drives the lever body to cause the tip end of the printing wire to protrude from the guide hole for printing. In a printing wire stress reduction printing head of a printing head that performs
The relationship between this and the natural frequency T_W of the span in which the printing wire has the guide hole as the support point and the fixed part to the lever body as the fixation point is T_F=(N+0.5)^±^0^. A printing wire stress-reducing printing head characterized in that printing wires are arranged at intervals of ^2×T_W (where N is an integer and N≧3). 4. At least one printing wire bearing part is provided between the wire guide and the printing wire fixing part of the lever body, and the first printing wire bearing part on the printing wire fixing part side and the printing wire fixing part of the printing wire The span between the fixed part of the lever body and the printing drive cycle T_W of the printing wire driving part is set such that the printing wire uses the first printing wire bearing part as a support point and the fixed part of the lever body as a fixed point. The relationship with the natural vibration period T_W of the span is T_F=(N+0.
5) ^±^0^. ^2×T_W (N is an integer and N≧3
4. The printing wire stress-reducing print head according to claim 3, wherein the print wires are arranged at intervals such that: . 5. Vibration isolating means that comes into contact with the printing wire to suppress the lateral vibration amplitude to the predetermined value when the lateral vibration amplitude of the printing wire reaches the predetermined value;
5. The print wire stress reducing print head according to claim 3, wherein the print wire stress reducing print head is provided on a side of the wire guide or the first bearing that is a support point of the natural vibration period T_W and faces the fixed part. 6. The print wire stress reduction print head according to claim 4, wherein the bearing portion is not restrained from moving in the axial direction and diametrical direction of the print wire.