JPH0286461A - Wire dot printer - Google Patents

Abstract

PURPOSE:To obtain satisfactory printing quality by making possible the independent adjustment of the pulse width of a voltage applied to each electromagnetic coil so that an impact force becomes constant. CONSTITUTION:A spring force brought to bear on wire is controlled by changing the pulse widths Ton1, Ton2 of a cancellation voltage or cancellation voltage Vb and controlling a cancellation time independently by wire, in accordance with the deterioration of an impact force. In addition, a counter for the number of printing actions is installed for each wire, and the Ton1 is continuously increased by coil in response to the number of printing actions by the relationship (Ton1 parameters) between the preset number of printing actions and the impact force so that the impact force becomes constant. Consequently, the impact force becomes constant against each wire regardless of the number of printing actions. Thus it is ensured to obtain the same satisfactory printing quality as when a new printer is used until the end of the life of the device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a print head that prints at the tip of a wire using the deflection return force of a spring, and particularly to a wire dot printer suitable for maintaining good print quality. .

[Conventional technology]

As described in Japanese Unexamined Patent Application Publication No. 61-47271, conventional devices maintain high-speed printing performance and reliability for a long period of time by increasing the surface treatment hardness of the core and yoke of the suction member. I was doing it.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, as shown in FIG. 5, the impact force of the print head decreases with time as the number of printing operations increases. As shown in Fig. 6, this is due to the amount of wire retraction (due to wear A and B of core 8 and wire 10 in Fig. 4, the tip of the wire retracts when the armature 9 is attracted to the core 8 compared to when it was new). This is because the change over time in the amount of printing, that is, C) increases with the number of printing operations, and the gap between the head and the paper surface becomes larger. But the armature.

In a print head where the core and wire collide repeatedly, wear is inevitable, and it is impossible to suppress the change in wire retraction amount over time to zero. Therefore, the impact force is
It decreases with the number of printing operations, and the printing quality deteriorates.

An object of the present invention is to prevent a decrease in impact force.

An object of the present invention is to provide a print head that can maintain good print quality for a long period of time.

[Means to solve the problem]

The above purpose is to increase the cancellation voltage pulse width T o n l # T o as shown in Fig. 3 as the impact force decreases.
This is achieved by changing n 2 or the cancellation voltage Vb, controlling the cancellation time, and controlling the spring force acting on the wire. Note that the cancellation time is controlled for each wire.

[Effect]

As shown in FIGS. 7 and 8, the cancellation voltage pulse width,
Alternatively, the impact force Ftmp can be adjusted by changing the cancellation voltage.

In other words, the impact force F'+mp, which decreases as the number of printing operations increases, is changed by changing the canceling voltage pulse width or canceling voltage according to the number of printing operations, and by changing the canceling time, that is, the time during which the spring force acts on the wire. By controlling each coil, it is possible to adjust the impact force Ft by increasing the number of printing operations.
It is possible to prevent a decrease in MP. Therefore, good print quality can be maintained for a long period of time.

〔Example〕

An embodiment of the present invention will be described below. In Figure 2,
Print head 3 is attached to carrier 20. The carrier 20 is supported by two rails and moves in parallel along the platen 2.

An ink ribbon 4 and paper 1 are inserted between a print head 3 and a platen 2.

FIG. 1 is a sectional view showing the structure of the print head 3. As shown in FIG. The wire 10 is connected to the armature 9. With spring 5.

combined. A permanent magnet 6 and a core 8 are joined to the yoke 21, and a coil 7 is attached to the core 8. When no canceling current is flowing through the coil 7, the permanent magnet 6 causes the armature 9 to move toward the core 7.
The spring 5 is attracted to .

Deflection energy is stored. Figure 3 (
When the canceling current shown in b) flows, a magnetic force is generated that cancels out the attractive force of the permanent magnet 6, so the stored energy is released and the wire that pops out is shown at 23 in Fig. 3(c). Displaced like this. That is, the wire 10 hits the paper surface 25, and the impact force Fi+m
yields p.

After this, by cutting off the cancellation current of coil 7,
Again, by the permanent magnet 6, the armature 9 is connected to the core 7
The wire will return to its original position as it will be sucked back into place.

By repeating this series of operations, characters made up of dots are printed on the paper. This operation causes the armature 9 and core 8 to wear due to repeated collisions. Further, the wire 10 also wears out because it collides with the paper surface. Therefore, it can be seen that as the number of repetitions of the printing operation increases, the amount of wire retraction described below increases. FIG. 4 shows the amount A that the wire retracts due to wear of the armature 9 and core 8, the amount B that the wire retracts due to wear, and the amount C that the wire retracts. FIG. 6 schematically shows the relationship between the number of printing operations and C. If we take the wire retraction amount on the vertical axis and the change over time on the horizontal axis, we get an upward-sloping curve to the right.In other words, the retraction amount increases with the number of wire printing operations, which means that the head paper gap (D in Figure 4) , to become wider.

In FIG. 12, the vertical axis represents wire displacement d, and the horizontal axis represents time t. 24 shows the wire operation waveform of a new head, and 24' shows the core 8, armature 9 .
The operation waveforms are shown when the wire 10 is worn out, the wire retraction amount C increases, and the head paper surface gap becomes wider. That is, at 24', the distance the wire is displaced is longer by C than at 24, so the time until the end of the printing operation is extended (t1 → t2), and if tz is longer than the required printing operation cycle. If this happens, printing becomes impossible. Furthermore, since the time for the wire to collide with the paper is delayed (t3→t4), this may lead to irregular printing. Furthermore, since the wire displacement becomes longer, the impact force FImp also decreases, resulting in a decrease in printing quality.

FIG. 7 shows impact force F1. ．． This diagram schematically shows the change in P, and the cancellation voltage pulse width T o l1
As the number of printing operations increases, the impact force F1mF increases.The present invention takes advantage of this characteristic and attempts to keep the impact force F1mF, which decreases as the number of printing operations increases, constant. That is, as shown in Fig. 13, a counter for the number of printing operations is provided for each wire, and as shown in Fig. 14, the number of printing operations and impact force F determined in advance are calculated.
Due to the relationship of tmp (T on 1 parameter), T0 is continuously adjusted so that the impact force Ftmp is constant.
Increase n1 according to the number of printing operations for each coil. As a result, as shown in Figure 11, the impact force F1mF can be kept constant for each wire regardless of the number of printing operations, and printing quality as good as when it was new can be maintained until the end of its life. can get.

Although T o l was increased as T increased, Vb may be increased instead of T o l (FIG. 15).

〔Effect of the invention〕

According to the present invention, in the print head of a dot printer, good print quality comparable to that when the print head is new can be obtained until the print head completes its life.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a print head according to an embodiment of the present invention, FIG. 2 is a perspective view of a printer according to the present invention, FIG. 3 is a diagram showing cancel voltage and pulse width, and FIG. 4 is a diagram showing cancel voltage and pulse width. Figures 5 and 6 are diagrams showing the amount of wire retraction, Figures 5 and 6 are diagrams showing changes in impact force and amount of withdrawal over time, and Figures 7 and 8 are diagrams showing the relationship between impact force, cancel voltage, and pulse width. , FIG. 9 and FIG. 10 are diagrams showing the canceling voltage and pulse width of the present invention, FIG. 11 is a diagram showing the temporal change in impact force according to the present invention, and FIG. 12 is a schematic diagram of wire operation. , 13th
The figures are block diagrams of the head driver, Figures 14 and 15.
The figure shows changes in impact force over time (Tonz, Vb parameters). T0n1: Cancellation voltage pulse width, Vb: Cancellation voltage, A: Amount of wear back between armature and core, B: Amount of wear back of wire tip, C: Amount of wire setback, 1mF. ...Impact force, T...Number of printing operations. 21st ￥1 3rd trouble ((1) Niji 13fiJ (C) Ding #40 No. 135ZJ No. 140 Ding #150

Claims (1)

[Claims] 1. By attracting the armature attached between the wire and the spring with the magnetic force of a permanent magnet, the spring is deflected, canceled by the magnetic force generated by the electromagnetic coil, and by the returning force of the spring. In a wire dot printer in which paper and ink ribbon are loaded between a print head that prints at the tip of the wire and a platen, the pulse width of the voltage applied to the electromagnetic coil is adjusted to each coil so that the impact force is constant. A wire dot printer that is equipped with a print head that can be adjusted independently.