JPH0452055Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The purpose of this invention is to speed up business-use dot impact printers that require high-speed printing processing. This relates to a hammer structure that suppresses the rebound phenomenon that occurs at impact, which inhibits the hammer's high-speed response.

[Conventional technology]

The hammer of a conventional dot impact printer is
A cantilever type hammer with a hammer pin at the tip was used.

FIG. 1 shows a shuttle printer equipped with a hammer of a conventional structure. Reference numeral 1-1 is a hammer spring having a hammer pin 1-2 at its tip and a base fixed to a back plate 5. This back plate 5 is fixed to a shuttle shaft 6 that shuttles perpendicularly to the plane of the paper, and a permanent magnet 4 is attached to the top.
A pole core 2 that attracts the hammer 1 via the pole core 2 is attached. A coil 3 is wound around the pole core 2 for applying a reverse magnetic field to release the hammer 1 attracted to the pole core 2 again.

FIG. 2 shows the details of a conventional hammer, in which (a) is a plan view and (b) is a cross-sectional view.

FIG. 3 shows the operating waveform and current waveform of a conventional hammer, and the broken line indicates the operating waveform of one cycle of the hammer operation.

In order to increase the printing speed with a conventional hammer structure, t _f , t _c , t _R , and t _S must be shortened.
Conventionally, the thickness of hammer spring 1-1 was increased,
By reducing the weight of the hammer pins 1-2, the natural frequency f _o of the hammer was increased and the speed of the hammer was increased.

[Problem that the invention attempts to solve]

The hammer structure described above has the following problems.

1 When increasing the thickness t of the hammer 1 to increase the natural frequency f _o to shorten _{t f} , the required suction force F to the pole core 2 increases,
There is a limit in the design of the magnetic circuit composed of 1, 2, 3, and 4.

2. Reducing the weight of the hammer pin in order to increase f _o in order to shorten t _f also reduces the impact force, so there is a limit to ensuring the required print density.

3. In addition, with the conventional hammer structure, as shown in Figure 4 A and B, the motion in mode 2 at the time of impact is large, so it is combined with the motion in mode 1 (motion for printing), and the repulsion speed from the platen is "zero"
A phenomenon such as a collision or a rebound (double collision) occurs, impeding high speed.

Therefore, the present invention proposes a simple structure that solves the above problems.

[Means for solving problems]

The present invention was made to solve the above problem. In a cantilever type hammer in which the clamp part is a fixed end and the pin part is a free end, the natural frequency f _oa of the cantilever mode is lower than the clamp part of the hammer spring. An additional spring piece is provided protruding from the free end of the hammer spring, with dimensions and weight set to be the same as the natural frequency f _os when the fixed end and pin part are used as the supporting end.

[Effect]

By providing an additional spring piece, the second-order mode movement of the hammer at the time of impact is suppressed, and by reducing the amplitude and period of the core surface rebound at the time of pole core return collision, the hammer's high-speed response is increased. Become.

〔principle〕

FIG. 5 shows the structure of the hammer according to the present invention, and FIG. 6A is an explanatory diagram of the principle of the present invention, in which 1-1 is a hammer spring, 1-2 is a hammer pin, and 1-3 is an additional spring piece.

In this case, in mode 1, the hammer pin 1-2 moves toward the platen surface 7, that is, cantilever mode movement of the hammer spring 1-1 for printing, but at the same time, mode 2 movement also occurs.

This is a movement in which the hammer spring 1-1 uses the left clamp portion as the fixed end and the pin portion as the supporting end, and the center of gravity of the hammer spring is lowered.

In this way, two modes of motion start simultaneously at the time of impact, but the frequency of the second mode is approximately twice as large as the frequency of the first mode, and therefore the motion of the pin tip at the time of impact is characteristic of a normal impact waveform. It is not a half sine wave (half sine),
As shown in FIG. 4B, the repulsion speed becomes "zero" or rebound occurs, causing a delay in the hammer operation.

On the other hand, in the hammer of the present invention shown in FIG. 5, as shown in FIG. 6A, at the time of impact, f _os = f _oa , so the additional spring piece 1-3 bends greatly, causing the secondary mode of the hammer spring 1-1. By the motion of point 0 ₁
Additional spring piece 1 for the moment M _B generated in
A moment M _a in the opposite direction due to −3 acts,
The displacement of the hammer spring in the secondary mode becomes smaller.

Therefore, the composite waveform of the movement of the hammer pins 1-2 becomes much closer to a half-sine wave than in the conventional structure, as shown in FIG. 6B, and the one-contact time _tc becomes shorter.

2 A positive repulsive force is generated against the platen, and the return flight time t _R to the pole core is also shortened.

3. The rebound amplitude of the core surface upon collision with the pole core also becomes smaller due to the similar action of the additional spring piece 1-3, as shown in FIG. 7B, so that _ts is shortened.

〔Example〕

FIG. 8 shows an embodiment in which the hammer according to the present invention is applied to the hammer of a shuttle type dot impact printer, where 1 is a hammer, 2 is a hammer 1
Pole core for attracting, 4 is a permanent magnet, 3
is a current coil for excitation of a reverse magnetic field to release the attracted 1 again in order to perform an impact operation, and a plurality of sets of 1, 2, 3, and 4 are fixed to a back plate 5 in a direction perpendicular to the plane of the paper, and are connected to a hammer bang 7.
, and when printing, the number of oscillations is perpendicular to the paper surface.
A shuttle movement of mm is provided by a shuttle shaft 6 fixed to the back plate 5.

In the figure, 7 is a platen, 8-1 is printing paper, 8-2
is an ink ribbon.

Figure 5 shows the details of the hammer. 1-1 is a hammer spring, 1-2 is a hammer pin, 1-3 has one end fixed to the tip of hammer spring 1-1, and the other end is fixed to the tip of hammer spring 1-1. This is an additional spring piece in the shape of a short rectangle that protrudes from the top.

The dimensions of this additional spring piece 1-3 are such that the natural frequency of the cantilever mode with the mounting part as the fixed end and the tip as the free end is the natural frequency of the secondary mode of the hammer spring 1-1, that is, the clamp part of the hammer spring 1-1. Hammer spring 1 when is the fixed end and the pin part is the supporting end
The dimensions and weight are set to be the same as the natural frequency of −1.

[Effect of idea]

As described above, by using the hammer structure according to the present invention, it is possible to achieve high-speed response of the hammer without increasing the necessary magnetic attraction force F of the pole core 3.

[Brief explanation of drawings]

Figure 1 is a side view of a shuttle type dot impact printer using a hammer with a conventional structure, Figure 2 is a detailed view of a hammer with a conventional structure, and Figure 3 is an operating waveform and current waveform of a conventional hammer and a hammer with the proposed structure. Fig. 4 is a diagram showing the hammer operation of the hammer of the conventional structure and the time waveform of the pin tip, Fig. 5 is a detailed view of the hammer of the proposed structure, Fig. 6 is a diagram explaining the principle of the proposed structure, Fig. 7 The figure is a comparative view of the rebound state on the core surface of the hammer of the conventional structure and the proposed structure, and FIG. 8 is a partially cut side view of the embodiment of the present invention. 1-1...Hammer spring, 1-2...Hammer pin, 1-3...Additional spring piece.

Claims (1)

[Scope of utility model registration request] In a cantilever hammer in which the clamp part is the fixed end and the pin part is the free end, the natural frequency f _oa of the cantilever mode is the natural frequency f oa when the clamp part is the fixed end and the pin part is the supporting end of the hammer spring. A dot impact printer hammer characterized in that an additional spring piece with dimensions and weight set to be the same as _{the OS} is provided protruding from the free end of the hammer spring.