JPH03281356A - Printing hammer - Google Patents

Abstract

PURPOSE:To prevent outer and inner springs from a fatigue failure and to improve a printing speed by providing an outer block, a base, and a stopper, which are made of a magnetic material, an absorber made of a buffer, and a coil wound around the center pat of the stopper. CONSTITUTION:When a voltage application to a piezoelectric element 8 is brought to a stop, each member which has been displaced is returned downward by an inertia force. an armature block 3 comes into collision with an absorber 11. However, it is restricted by the absorber 11 and a stopper 10 to have a minute overshoot amount. The bending deformation amount of inner and outer springs 5, 4 is also very small. A bending stress is restricted to be small. At this time, when an electric current application to a coil 12 is stopped, the armature block 3, an armature 2, and a wire 1 tend to displace upward by a restitution of collision, but have a minute rebound amount and a small vibration damping in a short time. This is because the magnetic flux of a permanent magnet 13 causes an attracting force to act between the top end of the stopper 10 and the side face of the armature block 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printing hammer used in a dot matrix printer, which drives a printing wire to print.

[Conventional technology]

With the recent development of computer YA equipment, various types of print heads that print while forming characters and symbols using multiple print wires (print wires) are small and capable of printing in Mincho fonts. Due to market demands, there is a need for faster printing speeds and longer lifespans.

Conventional print heads used for this purpose are generally so-called electromagnetic print heads that are equipped with a plurality of print hammers that utilize electromagnets or a magnetic circuit composed of permanent magnets and electromagnets as a means of driving print wires. has been adopted.

However, such electromagnetic print heads consume a large amount of power, and the speed-up technology achieved by improving the magnetic circuit is approaching its limits, so in recent years so-called piezo print heads that use piezo elements as the drive source have been developed. is in the spotlight.

The printing hammer of the piezo type print head has a piezo element whose expansion and contraction amount is 10 μm even if multiple piezo elements are stacked.
Since the amount of displacement is small, the biggest challenge is to develop a displacement magnification mechanism to expand the amount of displacement to about several tenths of a millimeter, which is the distance required for the printing wire to move.

For this reason, many attempts have been made to prototype and put into practical use a displacement magnifying mechanism, but the currently most popular one is one that combines an armature, a leaf spring, a block, etc.

[Problem to be solved by the invention]

The disadvantages of the print hammer of the piezo print head as described above will be explained below using a specific example.

FIG. 6 is a front view showing an example of a conventional printing hammer when it is at rest, FIG. 7 is a front view showing the example shown in FIG. 6 when printing, and FIG. 8 is a return view of the example shown in FIG. 6. Front view showing the state at the time,
FIG. 9 is a perspective view showing the state of the example in FIG. 6 at rest;
FIG. 0 is a characteristic diagram showing the operation of the example shown in FIG.

Referring to FIGS. 6 to 9, the conventional printing hammer includes an armature 2 having the end of the wire 1 fixed to its tip, an armature block 3 having a front end surface connected to the base of the armature 2, and an armature An outer spring 4 and an inner spring 5, which are a pair of leaf springs whose front end is joined to the rear end of the block 3, an outer block 6 whose front end is joined to the rear end of the outer spring 4, and a rear end of the inner spring 5. an inner block 7 whose front end surface is joined to the rear end surface of the inner block 7; a piezo element 8 whose front end surface is joined to the rear end surface of the inner block 7; and a base whose front end surface is joined to the rear end surface of the outer block 6 and the rear end surface of the piezo element 8. 9.

The operation of the conventional printing hammer configured as described above is as follows.

That is, when a voltage is applied to the piezo element 8 from the stationary state shown in FIG. 6, the piezo element 8 expands and moves the inner block 7 to the right in the figure (in the direction of arrow E). At this time, since the inner spring 5, the armature block 3, the outer spring 4, and the outer block 6 are connected to each other, the armature block 3 rotates in the direction of arrow F, as shown in FIG.

Therefore, the armature 2 coupled to the armature block 3 magnifies the rotational displacement of the armature block 3 to move the wire 1 upward in the figure to perform a printing operation. At this time, the inner spring 5 and the outer spring 4 are deformed as shown in FIG. 7, and bending stress is generated in them.

When the application of voltage to the piezo element 8 is stopped, the displaced members return to their original positions, but the armature block 3, armature 2, and wire 1 do not return to their original positions due to their inertia. without stopping,
As shown in FIG. 8, it moves further downward in the figure (in the direction of arrow G). The amount of movement in the G direction at this time is the rest position (6th
(position shown in the figure) and move further downwards (this is called overshooting). The amount of overshoot is the amount shown by dimension C in FIG. After moving the maximum downward movement amount C, each member returns upward again, but at this time it passes its initial position again. This is the rebound, and the amount of rebound is the amount shown by the dimensions in FIG. Thereafter, such vibration continues while its amplitude is attenuated and is stopped after I&.

As shown in Fig. 8, at the overshoot stage, both the inner spring 5 and the outer spring 4 undergo bending deformation in the opposite direction to the direction of printing (see Fig. 7). It generates bending stress in the direction.

In the operation of the conventional printing hammer as described above,
It has the following drawbacks: First, overshoot during printing generates bending stress in the inner spring 5 and the outer spring 4 in the forward and reverse directions, which accelerates fatigue failure of the inner spring and the outer spring.

Secondly, repeated overshoots and rebounds make the printing operation unstable, so the frequency of the printing operation cannot be increased. [Means for Solving the Problem] The printing hammer of the present invention has five tip portions. an armature block formed of a magnetic material whose front end face is bonded to the root portion of the armature; and an outer spring which is a pair of plates b whose tip portions are bonded to the armature block. and an inner spring, an outer block formed of a magnetic material with a part of the front end surface coupled to the rear end of the outer spring, and the remaining part of the front end surface close to the rear end surface of the armature block; an inner block coupled to the rear end of the inner spring, a piezo element whose front end surface is coupled to the rear end surface of the inner block, and a portion of the front end surface coupled to the rear end of the piezo element with the remainder of the front end surface a base made of a magnetic material, which is coupled to the rear end of the outer block; a stopper formed of a magnetic material coupled to a side surface of the armature block; an absorber formed of a cushioning material such as rubber attached to a side surface of the tip of the stopper and disposed close to the side surface of the armature block; It is equipped with a coil wound around the central part.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a front view showing the embodiment of the present invention when it is at rest, FIG. 2 is a front view showing the embodiment of FIG. 1 when printing, and FIG. 3 is the embodiment of FIG. 1. 4 is a perspective view showing the state of the embodiment shown in FIG. 1 when it is at rest, and FIG. 5 is a characteristic diagram showing the operation of the embodiment of FIG. 1.

As shown in FIGS. 1 to 4, this embodiment includes an armature 2 whose tip end is fixed to the end of a wire 1, and an armature block made of a magnetic material whose front end surface is bonded to the base of the armature 2. 3, an outer spring 4 and an inner spring 5, which are a pair of leaf springs whose tips are connected to the armature block 3, and a part of the front end surface is connected to the rear end of the outer spring 4, and the remaining part of the front end surface is connected to the rear end of the outer spring 4. An outer block 6 made of a magnetic material is placed close to the rear end surface of the armature block 3, an inner block 7 whose front end surface is connected to the rear end of the inner spring 5, and a front end surface connected to the rear end surface of the inner block 7. A piezo element 8, a base 9 formed of a magnetic material in which a part of the front end face is coupled to the rear end of the piezo element 8 and the remaining part of the front end face is coupled to the rear end face of the outer block 6, and a side surface of the tip. A stopper 1° formed of a magnetic material is placed close to the side surface of the armature block 3 and connected to the rear end side surface of the base 9 via a permanent magnet 13 on the rear end side surface, and the stopper 10 is attached to the front end side surface of the stopper 10 An absorber 1 formed of a cushioning material such as rubber and placed close to the amateur block 3
1 and a coil 12 wound around the center of the stopper.

When the printing hammer configured as described above is in a stationary state, as shown in FIG. The absorber 11 is arranged closer to the side surface of the armature block 3 with a slight gap or just in contact with the side surface of the armature block 3. Further, the armature block 3, outer block 6, and base made of magnetic material, the permanent magnet 13, and the stopper 10 constitute a magnetic circuit, and the permanent magnet 13
magnetic flux is flowing through this magnetic circuit. When a current is passed through the coil 12, a magnetic flux in the opposite direction to the magnetic flux of the permanent magnet 13 is generated in this magnetic circuit.

With the above configuration, the printing hammer of this embodiment operates as follows.

That is, when a voltage is applied to the piezo element 8 from the stationary state shown in FIG. 1, the piezo element 8 expands and moves the inner block 7 to the right in the figure (in the direction of arrow E). Since the inner spring 5 and the armature block 3 and the outer spring 4 and the outer block 6 are connected to each other, the armature block 3 rotates in the direction of the arrow F, and the armature 2 rotates in the direction of the arrow F, as shown in FIG. The printing operation is performed by enlarging the amount of rotational displacement and moving the wire l in the upward direction in the figure (in the direction of arrow F).

Simultaneously with the application of voltage to the piezo element 8, the application of current to the coil 12 is started, generating magnetic flux to cancel the magnetic flux of the permanent magnet 13 and increasing the attractive force between the armature block 3 and the stopper 10. In order to eliminate the above-mentioned armature block 3 and armature 2 and wire 1
can operate without any interference. At this time, the inner spring 5 and the outer spring 4 are deformed into the state shown in FIG. 2, and bending stress is generated.

When the application of voltage to the piezo element 8 is stopped, the displaced members return to their initial positions, but at this time the armature block 3, armature 2, and wire 1
are displaced further downward (in the direction of arrow G) from their original position due to their inertial force, and as shown in FIG. 3, the armature block 3 collides with the absorber 11.

However, the displacement in the direction of arrow G is regulated by the absorber 11 and the stopper 10, and as shown in FIG. 5, the overshoot amount A becomes minute. Therefore, the amount of bending deformation of the inner spring 5 and the outer spring 4 is also small, and the bending stress thereon can be kept small.

At the time of this collision, the application of current to the coil 12 is stopped. Due to the repulsion of the collision, the armature block 3, armature 2, and wire 1 try to displace upward from the state shown in FIG. 3, but the permanent magnet 1 of the magnetic circuit described above
3 exerts an attractive force between the tip of the stopper 10 and the side surface of the armature block 3, so displacement in this upward direction is suppressed, and as shown in FIG. 5, the amount of rebound B is minute. Become something. Therefore, the continuing vibrations are small and their attenuation is fast.

〔Effect of the invention〕

As explained above, the print head of the present invention includes an armature having a print wire at its tip, and an outer spring which is a pair of leaf springs connected to an armature block made of a magnetic material and provided at the base of the armature. and an inner spring, an outer block formed of a magnetic material that is connected to the other end of the outer spring and has one end close to the side surface of the armature block, a piezo element that is connected to the other end of the inner block, and the other end of the outer block and A base made of a magnetic material bonded to the other end of the piezo element, a stopper made of a magnetic material bonded to the base with the side surface of the tip section parallel to and close to the side surface of the armature block, and a stopper made of a magnetic material bonded to the base at the rear end portion. By providing an absorber made of a cushioning material such as rubber attached to the side of the tip of the armature block and placed near the side of the armature block, and a coil wound around the center of the stopper, the following effects can be achieved. have.

In other words, the amount of overshoot that displaces the armature block, armature, and wires that return to their original positions after a printing operation in a direction lower than their original positions can be regulated and kept small, and therefore the outer spring and inner Bending stress generated in the spring in the direction opposite to that during printing can be suppressed to a small level, thereby preventing fatigue failure. Furthermore, since the overshoot is small,
Transient vibrations are small, so the next printing operation can be stabilized and printing speed can be improved. Further, by providing an absorber at the tip of the stopper, the above-mentioned effect can be enhanced. Furthermore, by generating an attractive force in the magnetic circuit, rebound can be reduced, thereby further increasing the effect and damping transient vibrations faster.

[Brief explanation of drawings]

FIG. 1 is a front view showing the embodiment of the present invention when it is at rest, FIG. 2 is a front view showing the embodiment of FIG. 1 when printing, and FIG. 3 is the embodiment of FIG. 1. FIG. 4 is a perspective view showing the state of the embodiment in FIG. 1 when it is at rest. FIG. 5 is a characteristic diagram showing the operation of the embodiment in FIG. 1. FIG. 7 is a front view showing an example of a conventional printing hammer when it is at rest, FIG. 7 is a front view showing the example of FIG. 6 when printing, and FIG. 8 is a state of the example of FIG. 6 when it returns. 9 is a perspective view showing the example in FIG. 6 when it is at rest, and FIG. 10 is a characteristic diagram showing the operation of the example in FIG. 6. 1... Wire, 2... Armature,
3... Armature block, 4...
Outer spring, 5...Inner spring,
6・16・・・Outer block, 7・17・・・
... Inner block, 8 ... Piezo element, 9
・19... Base, 1o... Stopper, 11... Absorber, 12... Coil, 13... Permanent magnet.

Claims (1)

[Claims] An armature whose tip is fixed to the end of the printing wire,
an armature block formed of a magnetic material and having a front end surface coupled to the root portion of the armature; an outer spring and an inner spring, which are a pair of leaf springs whose tip portions are coupled to the armature block; an outer block formed of a magnetic material, the outer block being joined to the rear end of the outer spring and having the remaining portion of the front end face close to the rear end face of the armature block; and an inner block having the front end face joined to the rear end of the inner spring. a piezo element whose front end surface is coupled to the rear end surface of the inner block; a part of the front end surface is coupled to the rear end of the piezo element and the remaining part of the front end surface is coupled to the rear end of the outer block; a base made of a magnetic material, and a stopper made of a magnetic material, the side surface of the tip portion being close to the side surface of the armature block, and the side surface of the rear end portion connected to the side surface of the rear end portion of the base via a permanent magnet. and an absorber made of a cushioning material such as rubber attached to the side surface of the tip of the stopper and disposed close to the side surface of the armature block, and a coil wound around the center of the stopper. A printing hammer featuring