JPH028767Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to the reduction of collision vibration and noise of a hammer during return in the printing operation of a spring charge type wire dot printing head.

[Prior art]

Below, a conventional spring charge type wire dot printing head will be explained based on drawings, and
I will describe its shortcomings.

FIG. 1 is a partial side sectional view of a conventional printing head, in which 1 is a printing wire, 2 is a hammer to which the printing wire is fixed to one end, 3 is a vibration spring to which the hammer 2 is fixed to its free end, and 4 is a vibration spring. Core facing hammer 2,
5 is a coil placed in the core 4, and 6 is a permanent magnet placed outside the core 4 and the coil 5.

In the illustrated state, the magnetic force of the permanent magnet 6 forms a magnetic flux passing through the hammer 2 and the core 4, so the hammer 2
is in a home position state where it is attracted to the core 4 against the elastic force of the vibration spring 3, and the vibration spring 3 stores strain energy due to its elasticity. this is,
This is when not printing.

In this state of hammer 2's home position,
The coil 4 is energized to generate a magnetic flux from the core 4 in a direction that cancels the magnetic flux of the permanent magnet 6, canceling the attractive force between the core 4 and the hammer 2, and causing the hammer 2 and the magnetic flux to be generated by the strain energy of the vibration spring 3. The printing wire 1 is made to protrude forward. At this time, the printing wire 1 contacts the printing medium to perform printing.

Thereafter, when the coil 5 is de-energized, the hammer 2 is returned to its home position by the magnetic force of the permanent magnet 6.

In this manner, in the spring charge type wire dot printing head, printing is performed by driving the printing wire 1 by turning on and off current to the coil 5 at appropriate timings.

Here, the hammer 2 collides with the core 5 directly or through a thin wear-resistant film, and is attracted to the core 5 by the magnetic force of the permanent magnet 6, thereby damping the vibration of the hammer 2.

However, this method requires oil lubrication to prevent wear and tear on the collision part, that is, the opposing surfaces of the hammer 2 and the core 4, which may cause the hammer 2 to be adsorbed to the core 4 by an oil film and become inoperable, or be forced by external force. Because it absorbs vibrations, the impact force during a collision is large and noise is also generated. In order to increase the attraction force of the hammer 2, the permanent magnet 6 had to be made larger, resulting in problems such as an increase in the size of the head.

Next, a conventional example for solving these problems will be explained based on FIG. 2.

FIG. 2 is a partial side sectional view of a conventional improved printing head, in which 7 is a printing element, 8 is a hammer that fixes the printing element 7, and 9 is a vibration spring that fixes the hammer 8 on the free end side. , 10 is a spring frame for fixing one side of the vibration spring 9; 11 is a permanent magnet fixed to the hammer 8 so as to face a core pole to be described later;
12 is a core pole arranged opposite to the permanent magnet 11 with a predetermined gap formed therein, 13 is a frame fixing the core pole 12, 14 is a bobbin arranged on the core pole 12, 15 is a coil arranged on the bobbin 14, and 16 is the back of the head. 17 is a cover yoke placed in front of the printing head so that the tip of the printing element 7 can protrude to the outside; 18 is a thin film made of viscoelastic rubber and wear-resistant material. Todenari hammer 8
This is an intervening member placed between the frame 13 and the frame 13.

Here again, the basic concept of operation based on the magnetic force of the permanent magnet 11 and the energization of the coil 15 that cancels it is the same as that explained in FIG. It is effective because it acts on

The intervening member 18 disposed between the hammer 7 and the frame 13 causes the hammer 8 to collide with the rubber, which is a viscoelastic body, constituting the intervening member 18 when the hammer 8 is sucked, thereby reducing the hysteresis of the rubber. The vibration of the hammer 8 is damped by its characteristics.

Although this solves the problem described in FIG. 1, the following drawbacks arise.

This is because the hysteresis characteristics of the rubber change depending on the number of collisions with the hammer 8, and as the temperature rises, the hysteresis characteristics become smaller and the vibration damping ability decreases. This has the disadvantage of causing disturbances in printing operation and deterioration of printing quality.

[Purpose of invention]

Therefore, the purpose of this invention is to transfer the vibration of the hammer to the core pole by supporting the core pole that attracts the permanent magnet with a viscoelastic member so that it can vibrate in a predetermined manner without completely fixing it, thereby solving the drawbacks of the conventional method. .

[Structure of the idea]

The configuration of the present invention is as follows.

A residial sheet is placed between the permanent magnet fixed to the hammer and the core pole, and lower and upper pole support plates are formed that support the upper and lower parts of the core pole from the frame so that the core pole can vibrate.

The core pole has a larger diameter on one end side to form a protrusion. The core pole is passed from the lower pole support plate to the upper pole support plate, and the protrusion of the core pole is locked to the lower pole support plate. A viscoelastic member is disposed on the back and fixed with a back frame.

With this configuration, the core pole is not fixed but can vibrate in response to the vibrations of the hammer, and can absorb the vibrations of the hammer.

〔Example〕

Hereinafter, the spring charge type wire dot printing head according to the present invention, which has the above-mentioned purpose and structure, will be explained based on the drawings, and its effects will be described.

Note that the same reference numerals are used for the same parts as in the conventional example described in FIG. 2 above.

FIG. 3 is a partial side sectional view of a printing head showing an embodiment of the present invention, in which 7 is a printing element, 8 is a hammer, 9 is a vibration spring, 10 is a spring frame, 11 is a permanent magnet, and 12 is a core pole. , 12a is a protrusion with a larger diameter at one end of the core pole 12, 13 is a frame, 13a is an upper pole support plate formed as a protrusion from the frame 13 to support the upper part of the core pole 12, and 13b is a support plate for supporting the lower part of the core pole 12. 14 is a bobbin provided so as to correspond to the outer periphery of the core pole 12 and the inside of the upper pole support plate 13a and lower pole support plate 13b; 15 is a bobbin 14;
17 is a cover yoke that covers the front surface of the head and integrates each component; 19 is a residial sheet made of wear-resistant material placed between the permanent magnet 11 and the core pole 12; 20 is the core pole 12;
21 is the back frame of the head. Note that A is the working gap between the hammer 8 and the core pole 12 formed by the thickness of the residial sheet 19, and B is the gap between the hammer 8 and the cover yoke 17, and the working gap A is narrower than the gap B. It's summery.

Next, an overview of the operation in this configuration will be described.

First, in the illustrated state, the coil 15 is not energized and the magnetic flux from the permanent magnet 11 passes through the working gap A formed by the residial sheet 19, enters the core pole 12, is exposed from this, and is exposed to the cover yoke 17.
The liquid enters the air, passes through the air gap B, and returns to the permanent magnet 11.

At this time, since the working gap A is smaller than the gap B, the permanent magnet 11 is attached to the hammer 8 and is attracted to the core pole 12 through the residial sheet 19, and is located at the home position. This movement is against the elastic force of the vibration spring 9, so the vibration spring 9
This means that distortion energy is accumulated.

In this state, the coil 15 is energized and the permanent magnet 11
When the magnetic flux of the permanent magnet 11, the hammer 8, and the printing element 7 begin to move due to the strain energy of the vibration spring 9, the permanent magnet 11, the hammer 8, and the printing element 7 begin to move due to the strain energy of the vibration spring 9, and are further moved by the magnetic flux of the permanent magnet 11. A repulsive force with the demagnetizing magnetic field created by the action of the magnetic flux of the coil 15 is also added, and the hammer 8 is accelerated and makes an impact.

Next, when the current to the coil 15 is cut off at an appropriate timing, the repulsive force of the impact and the permanent magnet 1
The hammer 8 starts to return due to the attraction force caused by the magnetic flux recovery of 1, and returns to the home position, and the permanent magnet 11 collides with the core pole 12 via the reciprocal sheet 19, accompanied by the vibration of the hammer 8. .

The following explanation is important in the present invention. As mentioned above, the permanent magnet 11 collides with the core pole 12 accompanied by the vibration of the hammer 8. At the time of this collision, the well-known Newton's Collision law, that is, hammer 8 (collision object)
, the mass M of the core pole 12 (collided object), and the repulsion coefficient e between the hammer 8 and the core pole 12 via the residial sheet 19, e=
If the configuration is such that the m/M relationship holds, all of the kinetic energy of the hammer 8 can be transferred to the core pole 12 after the collision, and the hammer 8 will quickly come to rest after the collision.

FIG. 4 shows that the coefficients are e=0.3, M=
This is a graph showing the relationship between the printing operation of the hammer 8 and the operation of the core pole 12 when m = 0.4g and m = 0.12g.As shown in this graph, the hammer 8 is almost stationary after the collision, and the core pole 12 is in motion immediately after the collision. It can be seen that the vibration of the hammer 8 is absorbed toward the core pole 12 side by performing damped vibration with the viscoelastic member 20.

This vibration of the core pole 12 causes the core pole 12 to
Since the protrusion 12a of the core pole 12 is fixed by the lower pole support plate 13a, the vibration of the core pole 12 in the printing direction is sliced, and the vibration is in one direction and does not strike out the stationary hammer 8.

Further, since the upper pole support plate 13a, the lower pole support plate 13b, and the core pole 12 slide, the vibration is rapidly attenuated due to the sliding loss.

As mentioned above, the impact force when the permanent magnet 11 collides with the core pole 12 through the residial sheet 19 accompanied by the vibration of the hammer 8 is small, and as mentioned above, the vibration of the hammer 8 is also rapidly attenuated and its amplitude is small. Therefore, the operation of the hammer 8 becomes stable, and the noise upon collision is significantly reduced. Further, since the main body that damps vibration is the mass of the core pole 12, the temperature characteristics of the collision vibration when the hammer 8 returns are almost eliminated.

[Effect of idea]

As explained above in detail, in the present invention, the core pole is supported and fixed by the upper pole support plate and the lower pole support plate formed on the frame so as to be able to vibrate in only one direction, and a viscoelastic member is attached to the lower end of the core pole, and the viscoelastic member is attached to the upper end of the core pole. By arranging the residial sheet, the following effects can be achieved.

By effectively absorbing the kinetic energy when the hammer returns with the unidirectional damping vibration system of the core pole, viscoelastic member, and lower pole support plate, the impact force when the hammer returns collides can be reduced. This eliminates the need for oil lubrication of the collision surface of the core pole between the permanent magnet having the hammer and the residial sheet, thereby eliminating the printing operation failure due to adsorption.

Further, since the rebound of the hammer is almost eliminated, the repetitive printing operation is stabilized, so the printing quality is significantly improved, and there is also the effect that there is no temperature dependence and the noise during printing is significantly reduced.

Due to these effects, the present invention can be usefully used in all spring charge type wire dot printing heads, and can also be used to prevent chatter in electromagnetic relays, etc., when the mover and stator in a magnetic circuit repeatedly collide. It can also be applied to noise reduction.

[Brief explanation of the drawing]

FIG. 1 is a partial side sectional view of a conventional print head.
Figure 2 is a partial side sectional view of a conventional improved print head, Figure 3 is a partial side sectional view of a print head showing an embodiment of the present invention, and Figure 4 is a hammer printing operation and a core pole operation. It is a graph showing a relationship. 7... Printing element, 8... Hammer, 9... Vibration spring, 11... Permanent magnet, 12... Core pole, 1
2a... Protrusion, 13... Frame, 13a...
Upper pole support plate, 13b...Lower pole support plate, 15...Coil, 19...Residial sheet, 20...Viscoelastic member.

Claims (1)

[Scope of utility model registration request] A printing element is attached to one end of the hammer, a vibration spring is attached to the other end, and a permanent magnet is fixed in the middle.A core pole with a coil is placed opposite the permanent magnet with a predetermined gap, and the magnetic flux of the permanent magnet is used to The wire dot is then drawn to the core pole side against the elastic force of the vibration spring, and by energizing the coil, the magnetic flux of the permanent magnet is erased, and the hammer is protruded by the elastic force of the vibration spring to perform printing. In the print head, a protrusion is formed at the lower end of the core pole, and the core pole is supported vibratingly by an upper pole support plate formed protruding from the frame and a lower pole support plate that locks the protrusion of the core pole. A wire dot print head characterized in that a viscoelastic member is placed in contact with a wear-resistant residial sheet at the upper end.