JPS6315759A - Manufacture of printing head - Google Patents

Abstract

PURPOSE:To enable the adjustment of a spring constant to a prescribed value inexpensively, by changing the shape of a leaf spring whose spring constant is made higher than the prescribed value. CONSTITUTION:The operation performances of a printing wire 2 and an armature 1 are determined by the spring constant and the deflection amount of a leaf spring 6. In order to control the spring constant of the leaf spring 6 with a high precision, a distance H between a core 10, a yoke 11 and the attracting surface 21 of the armature 1, and a pressing member 19 provided in a housing 14, is set to be higher than a prescribed amount. A laser beam is applied to this leaf spring 6 from the direction A through a beam hole 18 formed in the housing 14 to effect trimming so that the symmetry is obtained with respect to the center line of the leaf spring 6. By the formation of a portion 20 trimmed in this way, the sectional form of the leaf spring 6 is changed and the spring constant is lowered to a prescribed value. Then, a trimming amount 20 of each leaf spring 6 is varied separately, and adjustment is made so that the spring constants of all the leaf springs 6 may be uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] 5. The present invention relates to a method for manufacturing a print head for a wire dot matrix printer.

[Conventional technology].

Conventionally, as this type of print head, for example, Japanese Patent Application Laid-Open No. 51J-17,7372 or Japanese Patent Application Laid-Open No. 56-37
．． As disclosed in No. 17.6, there is a printed word on one end,
Normally, the armature to which the ear is connected is attracted by the magnetic flux of the permanent magnet, and when printing, the attraction force by the permanent magnet is canceled by 1, and the strain energy stored in the leaf spring connected to the other end of the armature is released. There is a known structure in which the tire with the 1 character is urged toward the printed surface using the above-mentioned method. According to a print head with such a structure, the printing quality changes depending on the spring constant of the leaf spring, and also affects the maximum printing speed, so the spring constant of the leaf spring can be adjusted uniformly and with high precision. It is necessary to do so.

[φ problem that the invention attempts to solve].

However, what is shown in Japanese Patent Application Laid-open No. 58-1773.7g is that the deflection of the leaf spring can be adjusted by adjustment and screws.
Since the spring constant is adjusted by changing the amount of spring, it is necessary to provide the same number of adjustment screws as the number of leaf springs, which poses a problem of high cost.

On the other hand, in the method shown in JP-A No. 56-37176, a leaf spring with a high precision spring constant is selected and assembled, so the leaf spring material becomes expensive. There was a problem with the print head.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a print head that can be manufactured at low cost and with excellent print quality.

[Means for solving problems]

In the present invention, the spring constant of the leaf spring is set higher than a specified value before assembly, and is adjusted to the specified value by changing the shape of the spring during or after assembly.

[Operation] By changing the shape of the leaf spring, its spring constant is brought to a specified value m11. Therefore, there is no need to provide adjustment screws, and there is no need to use highly accurate spring materials.

〔Example〕

Hereinafter, the present invention will be explained in detail based on examples.

FIG. 1 is a vertical sectional view of a print head to which the present invention is applied, and FIG.
The figure is a perspective view of the armature part, and FIG. 3 is a plan view and a side view of the armature part.

In these figures, a printing wire 2 is connected to one end of each of a plurality of armatures 1.

The printing wire 2 is held and guided by a bearing 3 and guides 4 and 5, and is housed in a nose 9.

Further, a leaf spring 6 is connected to the other end of the armature 1. A notch 26 is provided at the end of the leaf spring 6, and the end serves as a spring load point 23. The armature 1 is positioned by a lever guide 20 and a positioning projection 22 that engages with a notch 26 in the leaf spring 6. In this case, the positioning protrusion 22 is provided on the housing 14. The armature 1 and the leaf spring 6 are housed in the housing 14 via a lever guide 20 and a positioning projection 22. The armature 1 constitutes a magnetic circuit together with a core 10 and a yoke 11, and when not printing, it is attracted to the core 10 by a permanent magnet 12 in the magnetic circuit, thereby bending the leaf spring 6.

Conversely, during printing, the magnetic flux of the permanent magnet 12 is canceled by passing current through the coil 13, and the strain energy stored in the leaf spring 6 separates the permanent magnet from the core 10 to perform the printing operation.

Therefore, the operational performance of the printing wire 2 and the armature 1 depends on the magnitude of the strain energy stored in the leaf spring 6. Since the strain energy is determined by the spring constant and amount of deflection of the leaf spring 6, the spring constant and amount of deflection of the leaf spring 6 must be set strictly in order to obtain the required operating performance and to reduce variations among multiple printing wires. Must be managed0
In the present invention, in order to control the spring constant of the leaf spring 6 with high precision, the core 10, the yoke 11, and the suction surface 2 of the armature 1 are
1 and the pressing portion 19 provided on the housing 14 is set in advance so that the strain energy is higher than a predetermined amount.

That is, as shown in FIG. 3, when the armature 1 is alone, the print head is assembled to the distance between the spring load □ point 23 of the leaf spring 6 and the suction surface 21, so that the leaf spring 6 is
The spring is deflected so that the distance H between the spring load point 23 and the suction surface 21 becomes h. At this time, h is set so that the strain energy of all the leaf springs 6 is higher than a predetermined amount even if all variations such as the thickness of the leaf spring 6 and the machining accuracy of the pressing part 19 of the housing 14 are included. I'll keep it. After simply assembling the print head, trial printing is performed to measure the printing force of each wire. Since strain energy and printing force can have a unique correspondence using a certain function, it is also possible to use printing force as a measure instead of strain energy. Since h is set so that the strain energy is high, the printing force is also measured to be higher than a predetermined value. A laser beam is irradiated from the direction of arrow A in FIG. 1 through the beam hole 18 formed in the housing 14 to the leaf spring 6 whose printing force is higher than a predetermined value, and the center line of the leaf spring 6 is Crop so that it is symmetrical left and right. By forming the trimming portion 20, the cross-sectional shape of the leaf spring 6 changes, the spring constant decreases, and the strain energy, that is, the printing force, can be reduced to a predetermined value. Such work is performed individually for each of the plurality of leaf springs 6. 2. In other words, each leaf spring 6 is trimmed individually according to the difference between the printing force measured in the trial printing and the predetermined printing force. and adjust the spring constants of all leaf springs 6 to be uniform. In this case, the above-mentioned trimming is performed to avoid deflection and stress concentration of the leaf spring 6, but it is also possible to reduce the spring constant by making a hole in the center of the spring. FIG. 4 shows the relationship between printing stroke and spring load when adjusting strain energy. In Figure 4, if the vertical axis is the spring load and the horizontal axis is the rotation stroke of the printing wire or armature, then the printing stroke when using the print head and the trapezoidal part surrounded by the spring load line are the distortions used for printing. It becomes energy. At the stage where the print head is simply assembled, the strain energy is set to be higher than a predetermined value, so the spring load lines are as shown by the dashed line and the dashed double dot line in the figure. On the contrary,
By trimming the handling spring 6 by an appropriate amount, the spring constant of the leaf spring 6 decreases, so the spring load line changes to the solid line and broken line in the figure, and the trapezoidal area shown by the diagonal line is the predetermined strain energy. Used for printing.

Next, an example of actually adjusting the spring constant will be explained with reference to FIG. The print wire of the simply assembled print head 30 is connected to the print head driver 32 according to a command from the control unit 31.
The printing force of each wire is measured by a printing force sensor 33. Thereafter, the measured value is loaded into the storage section 34 as measurement data, and the data is judged by the calculation section 35. The calculation unit 35 calculates the difference between each measurement data and the specified printing force range, and ranks the difference into several preset printing force ranges. Next, the print head 30 is moved from the print force measurement position to the beam irradiation position by the command from the control unit 31.
The beam is set so that the beam is focused on the temporary spring corresponding to each wire. Then, a trimming command for a trimming amount corresponding to the rank of the measured value of the printing force is outputted from the control section 31 to the beam generator 36, whereby each wire is trimmed according to the printing force. When trimming of one leaf spring is completed, the print head 30 is moved to the trimming position of the leaf spring for the next wire, and similar trimming is performed. Above, as a specific example of the actual adjustment method, a method of adjusting the spring constant by trimming has been shown, but the same applies to the case where the surface of the leaf spring 6 is scribed.

6 and 7 are a longitudinal sectional view and a perspective view of an armature portion showing an embodiment in which the present invention is applied to a print head having a different spring structure, in which the rear ends of a plurality of leaf springs 6 are circular. Alternatively, the ring part is integrally connected with a substantially circular ring part, and the ring part is connected between the yoke 11 and the housing 14 via a spacer 16 and a side yoke plate 17 for giving the leaf spring 6 the amount of deflection. It is held in place by being inserted into the Conventionally, in order to obtain high print quality with a print head having such a spring structure, it was necessary to make parts such as the plate thickness of the leaf spring 6 and the spacer 16 extremely high in precision. However, if the present invention is applied, after incorporating a spacer 16 with a thicker plate so that the strain energy is higher than a predetermined strain energy even including all variations, the beam hole provided in the housing 14 can be A laser beam is irradiated from direction A to trim the leaf spring 6 as shown by the trimming part 20 shown with diagonal lines, and the spring constant is lowered so that each wire is adjusted within the specified printing force range.
General precision parts can be used. Note that the same parts as in FIGS. 1 to 3 are indicated by the same symbols.

FIG. 8 is a perspective view of the armature portion of an embodiment in which the present invention is applied to a print head having another spring structure. The print head with this structure has two springs, a horizontal leaf spring 24 and a vertical spring 25, and is of a so-called cross spring type.Similarly to the above, the horizontal leaf spring 24 is shown as a trimming part 20 shown with diagonal lines. By trimming to
The spring constant is adjusted to the specified value.

FIG. 9 is a perspective view showing an example of application to a print head with yet another spring structure. In this example, the armature 1 and leaf spring 6 are integrated, but in the same manner as in the previous case. A trimming portion 20 can be formed to adjust the spring constant.

In the above embodiment, the spring constant is adjusted after the print head is assembled, but the spring constant may be adjusted during the assembly.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention,
This suppresses variations in spring strain energy, which can be an impediment to print quality and print speed.

It is possible to create a print head with good print quality and suitable for high speed at a low cost because it can be achieved by an adjustment method that is easy to automate without installing new adjustment mechanism parts or extremely increasing the accuracy of parts and assembly. It has the effect of being able to.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a print head to which the present invention is applied, FIG. 2 is a perspective view of the armature portion of FIG. 1,
Figure 3 is a plan view and side view of the armature part in Figure 1, Figure 4 is a diagram showing the relationship between printing stroke and spring load, and Figure 5 is a diagram showing the relationship between printing stroke and spring load.
The figure is a block configuration diagram showing an example of a device for adjusting the spring constant, FIG. 6 is a longitudinal cross-sectional view showing a second embodiment of the print head to which the present invention is applied, and FIG. 7 is the armature portion of FIG. 6. The perspective views, FIGS. 8 and 9, show the third section of the print head to which the present invention is applied. FIG. 7 is a perspective view showing a fourth embodiment. DESCRIPTION OF SYMBOLS 1... Armature, 2... Printing wire, 6... Leaf spring, 10... Core, 11... Yoke, 12...
Permanent magnet, 1.3... Coil, 14... Housing, 16... Spacer, 18... Beam hole, 19...
- Pressing part, 20... Trimming part, 21... Suction surface, 22... Positioning protrusion, 23... Spring load point, 2
4...Horizontal leaf spring, 25...Vertical spring, 26...
Notch.

Claims (1)

[Claims] 1. A plurality of armatures having a printing wire coupled to one end and a leaf spring coupled to the other end, and a permanent magnet that magnetically attracts each armature and stores strain energy in the leaf spring. and,
In a print head equipped with a magnetic coil that selectively cancels the magnetic flux to the attracted armature to release the armature and opposes the printing wire to the printing surface with a pressure corresponding to the strain energy stored in the leaf spring. A method for manufacturing a print head, characterized in that the spring constant of the leaf spring is configured to be higher than a specified value before assembly, and the spring constant is adjusted to the specified value by changing the shape of the spring during or after assembly. . 2. The method of manufacturing a print head according to claim 1, wherein the shape of the leaf spring is changed by trimming with a laser beam.