JP3061087B2 - Impact dot head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a print head for an impact dot printer.

[0002]

2. Description of the Related Art An impact dot printer of a type in which required characters and the like are written in a row of dots by striking a wire protruding from the tip of a nose by magnetic attraction through an ink ribbon onto printing paper. Japanese Unexamined Patent Publication No. Hei 2-133345 discloses a method in which a reinforcing plate is provided on the back surface of a damper holder to reduce the resonance of the damper holder caused by the collision of the print lever with the damper during the return stroke, thereby generating noise. Is to suppress.

However, even with such a configuration, the impact force of the print lever when colliding with the damper is extremely large, so that there is a problem that the generation of noise caused by resonance cannot be sufficiently suppressed. .

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem.
It is an object of the present invention to provide a new impact dot head capable of minimizing resonance of a damper holder which causes noise.

[0005]

That is, in order to achieve the object, the present invention provides a reinforcing plate for reducing resonance.
To the impact dot bonded to the back of the bumper holder.
In the pad, the reinforcing plate is
Formed as a plate-like member with an integral bulge
This reinforcing plate is connected to a printing lever provided with a wire.
ー has a mass more than 5 times the inertial mass associated with all rotations
It is formed as a member.
The ring-shaped bulge provided on the peripheral edge of the surface is missing at two locations in the radial direction.
It is made to fall, and the missing part is made into the attachment part of a fixed spring .

[0006]

Embodiments of the present invention will be described below. FIG. 1 shows an embodiment of the present invention.

This print head is roughly divided into a print lever 16 provided with a wire 8 at the tip, a frame 2 integral with a frame core portion 14 for magnetically driving the print lever 16, and guides the wire 8. The nose 1 includes a damper holder 18 that supports a damper 17 that contacts the print lever 16 in the return stroke.

The fulcrum portion of the print lever 16 is held on the outer peripheral edge of the frame 2 by the first yoke 3 and the second yoke 4, and is pressed by a fulcrum pressing spring 22 provided on the damper holder 5. It is opposed to the surface of the frame core portion 14.

On the other hand, a damper 17 is attached to the inner surface of the damper holder 18 so as to be in contact with the print lever 16 urged by the return spring 15 mounted on the spring holder 13 of the inner peripheral ring portion 11 of the frame 2. A reinforcing plate 25, which will be described later, which is a feature of the present invention, is joined to this outer surface in a state pressed by the fixed spring 18.

In the drawings, reference numeral 6 denotes a tip guide provided at the tip of the nose 1, and 7 denotes a guide groove 2 provided at the inner surface of the nose 1.
Reference numeral 4 denotes an intermediate guide, 10 denotes a printed wiring board mounted on the back surface of the frame 2 via an insulating member 9, and 20 denotes a coil wound around the frame core 14, respectively. Reference numeral 21 indicates the platen 1
2 shows an ink ribbon for forming a dot image on the printing paper 19 on the second sheet.

By the way, all the print levers 16 whose total inertial mass due to the rotation is m1 are operated, and these wires 8 are brought into contact with the surface of the printing paper 19 to form a dot image. When the bumper 17 collides with the damper 17 at a high speed, the reinforcing plate 25 having the mass m2 is fixed to the fixed spring 18 having the spring constant K.
Assuming that the displacement of the displacement amount で occurs at the speed of V2 against the speed, the kinetic energy of both at this time is

[0012]

(Equation 1) Is represented as

In this equation, the print lever 1
Since the displacement amount の of the reinforcing plate 25 generated when the colliding member 6 collides with the damper 17 is actually a small amount of about several μm, the first term on the right side of this equation is ignored, and the printing lever 16 is moved to the damper 17. The formula of the actual kinetic energy when colliding with

[0014]

(Equation 2) As a result, most of the kinetic energy when the print lever 16 collides with the damper 17 is changed to the displacement of the reinforcing plate 25.

The volume of the sound generated when the damper holder 5 and the reinforcing plate 25 are displaced depends on the speed V of the reinforcing plate 25.
Since it is proportional to the square of 2, the displacement velocity V2 of the reinforcing plate 25 is obtained from the equation when the total inertial mass m1 of the print lever 16 and their collision velocity V1 are constant.

[0016]

(Equation 3) It can be seen that the noise m can be reduced by increasing the mass m2 of the reinforcing plate 25.

FIG. 5 shows the relationship between the mass m2 of the reinforcing plate 25, the displacement speed V2 thereof, and the magnitude of the noise measured at that time. As is clear from FIG. Is inversely proportional to the square root of its mass m2.

The total inertial mass m1 of 0.79 g of 24
According to the result of an experiment in which the impact force of the pair of print levers was suppressed by reinforcing plates having a mass m2 of 1 g and 4 g, the sound pressure level was reduced by changing the mass from 1 g to 4 g.
As shown in the figure, it is clear that the sound pressure level cannot be reduced so much even if the mass of the reinforcing plate is further increased. It was found that the ratio between the total inertial mass m1 and the mass m2 of the reinforcing plate should be at least 5 times.

FIG. 2 shows a wire 8 on the back of the damper holder 5.
This shows an embodiment of the present invention in which the reinforcing plate 25 having the above-mentioned conditions is applied to a print head having a margin in the axial direction.

In this embodiment, ceramics, lead, iron, and the like are formed so as to be joined to the center of the back surface of the damper holder 5.
A ring-shaped bulging portion 25b is formed on the periphery of the back surface of the disk-shaped main body 25a made of a material having a large specific gravity such as brass or zinc.
Are formed integrally with each other.
Thereby, the rigidity of the reinforcing plate 25 itself can be increased, and at the same time, the mass of the reinforcing plate 25 is at least five times the total inertial mass associated with the rotation of the wire 8 and the lever 16. By removing two radial portions of the ring-shaped bulging portion 25b and passing the left and right leg pieces 18a of the fixed spring 18 to these missing portions 25c and stopping their ends at the base of the nose 1, the wire 8 The entire print head is fastened without increasing the height in the axial direction.

The embodiment shown in FIG. 3 shows two half-ring-shaped bulges 27, 2 provided on the periphery of the rear surface of the disk-shaped main body 26.
7 is formed by a separate member, and the dowels 27a protruding from these joint surfaces are press-fitted or crimped into fitting holes 26a provided in the peripheral edge of the disc-shaped main body 26,
This type of reinforcing plate can be formed at low cost without using a die casting method or a lost wax method.

[0022]

As described above, according to the present invention, the dam
A reinforcing plate to be bonded to the back of the
Formed as a member with an integral bulge
Reinforces without significantly increasing the axial dimension of the wire
The plate can be given the required mass, and the periphery
The secondary section shape of the reinforcing plate is U-shaped due to the bulging part provided in
No rigidity can be increased as much as possible,
Print lever collides with the damper due to the large mass and rigidity
To effectively reduce the resonance of the damper holder
To make a quieter impact dot head
Can be.

In addition, this reinforcing plate is used to rotate all the print levers.
The experiment was performed by setting the inertial mass of the moving object to 5 times or more.
Between the determined noise level and the mass of the stiffener
Based on the relationship, reduce the sound pressure level to near the limit.
Can be.

Further, a phosphor provided on the peripheral edge of the reinforcing plate
The bulging portion in the shape of a ring is dropped at two places in the radial direction, and
With the fixed spring mounting part, impact
Without significantly increasing the axial dimension of the
Moreover, without causing a displacement of the fixed spring in the surface direction,
The entire head can be reliably integrated.

[Brief description of the drawings]

FIG. 1 is a side view showing a cross section of an impact dot head according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of an impact dot head provided with a reinforcing plate according to an embodiment of the present invention.

FIG. 3 is an exploded perspective view showing an impact dot head according to another embodiment.

FIG. 4 is a diagram showing the relationship between the mass of a reinforcing plate and noise.
You.

[Explanation of symbols]

 5 Damper holder 8 Wire 16 Print head 17 Damper 18 Fixed spring 25 Reinforcement plate

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shigeki Mizuno 3-5-5 Yamato, Suwa-shi, Nagano Seiko Epson Co., Ltd. (56) References JP-U 2-133345 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 2/235 B41J 2/275-2/28

Claims (3)

(57) [Claims] A reinforcing plate for reducing resonance is provided on the back of a damper holder.
In the impact dot head joined to the surface, the reinforcing plate is integrally formed with a ring-shaped bulging portion at the periphery of the back surface.
An impact dot head formed as a plate-shaped member provided in the above . 2. A printing lever provided with a wire, comprising:
ー has a mass more than 5 times the inertial mass associated with all rotations
The impact dot head according to claim 1, wherein the impact dot head is formed as a member . 3. A ring provided on a peripheral edge of a back surface of the reinforcing plate.
Bulges are cut off at two locations in the radial direction, and the cuts are fixed.
2. The impact dot head according to claim 1, wherein said impact dot head is a mounting portion for a constant spring .