JPH0469550B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printing hammer used in a printing head of a printer, and particularly to a printing hammer using a piezoelectric element as a driving source.

[Conventional technology]

An electromagnetic actuator is widely used as a driving source for printing hammers used in print heads of conventional printers. Such an electromagnetic actuator is configured to generate a magnetic field by passing a current through a coil, and drive a movable member using the resulting magnetic force. For this reason, copper loss and iron loss occur, which not only requires a large amount of input energy, but also causes problems such as heat generation and magnetic interference.

For this reason, a printing hammer is being considered that uses a piezoelectric element as a driving source, which has high electrical/mechanical energy conversion efficiency, can be driven with low power, generates little heat, and is free from magnetic interference. For example, there is a printing hammer as shown in FIG.

The printing hammer shown in FIG. 5 includes a piezoelectric element 51 whose lower end is connected to a fixing member 50, and two
first and second coupling portions 52 and 53, one coupling portion 52 of which is connected to the fixing member 50.
The other coupling portion 53 is connected to the piezoelectric element 51.
It has a first arm 54 coupled to the upper end, and two third and fourth coupling parts 55 and 56 that are close to each other in the vertical direction, one of which coupling parts 55 is connected to the arm 54. The other coupling portion 56 at the upper end includes a second arm 57 coupled to the upper side of the fixing member 50 and a printing wire 58 fixed to the left end of the arm 57.

FIG. 5a shows a state in which no voltage is applied to the piezoelectric element 51 (non-operating state), and FIG. 5 b shows a state in which a voltage is applied to the piezoelectric element 51 (operating state).
FIG.

When a voltage is applied to the piezoelectric element 51 in the state shown in FIG. 5a, as shown in FIG. 5b, the piezoelectric element 5
1 extends in the direction of arrow A, thereby pushing the right side of the lower end of the first arm 54, and pivoting in the direction of arrow _θ1 about the joint 52 as a fulcrum. Piezoelectric element 51
The amount of displacement is magnified by the lever principle and transmitted to the joint 55. Therefore, the arm 57 is pulled by the connecting portion 55 and rotates in the direction of arrow θ ₂ using the connecting portion 56 as a fulcrum. As a result, the connecting portion 55
The amount of displacement is also magnified by the lever principle and transmitted to the mark wire 58. In this way, the amount of displacement of the piezoelectric element 51 is magnified by the rotational movement of the arms 54 and 57, and is transmitted to the printing wire 58 to perform a printing operation.

[Problem that the invention seeks to solve]

The conventional print head mentioned above uses a piezoelectric element as a driving source, so it has the advantage of low power consumption, low heat generation, and no magnetic interference. The displacement amplification mechanism for this purpose is a two-stage amplification type in which a structure that performs a lever action with one arm and two coupling parts is connected in series in two stages. It serves as a displacement magnification mechanism. For this reason, the conventional printing hammer has a problem in that it has a complicated structure and is expensive to manufacture.

Further, since such a displacement amount enlarging mechanism applies the principle of a lever, it has the property that the displacement amount is increased but the force is reduced. Therefore, it is difficult for the first stage displacement magnification mechanism, which is composed of the first arm and the first and second coupling parts, to obtain a large force as its output. It is necessary to make the bending rigidity of the third and fourth joints of the eye displacement magnification mechanism smaller than the bending rigidity of the first and second joints. As a result, the natural frequency of the second stage displacement magnification mechanism, which is composed of the second arm and the third and fourth coupling parts, becomes low, and as a result, the response frequency of the printing operation of the printing hammer becomes high. There is also the problem that the printing speed cannot be increased because the printing speed is not high.

An object of the present invention is to improve the drawbacks of the conventional printing hammer using a piezoelectric element as a driving source as described above, and to provide a printing hammer that has a simple structure, is inexpensive to manufacture, and can operate at high speed. It's about doing.

[Means for solving problems]

The printing hammer of the present invention includes an arm having a printing wire fixed to one end thereof, and one end of which is fixed to the center of the other end of the arm, and the printing hammer is arranged in a direction perpendicular to the direction of movement of the printing wire. a thin plate-shaped first hinge disposed in the width direction; a piezoelectric element having one end fixed to the other end of the first hinge; and a piezoelectric element disposed on the left and right sides of the first hinge in the width direction; A thin plate having an equal step of a predetermined size in the direction of movement of the printing wire with respect to the first hinge, and having one end fixed to the other end of the arm and the other end fixed to a fixing member. second and third hinges;
and a fourth hinge having one end fixed to the other end of the piezoelectric element and the other end fixed to the fixing member.

[Effect]

The printing hammer of the present invention includes a first hinge in the form of a thin plate, which is a main member for connecting an arm carrying a printing wire and a piezoelectric element, and a first hinge provided on both sides in the lateral direction (width direction) with this hinge in between. , comprising second and third thin plate-like hinges arranged to have a predetermined height difference from the first hinge in the height direction, and the center line of the first hinge and the second and third hinges are arranged so as to have a predetermined height difference from the first hinge in the height direction. The distance between the third hinge and the center line is made shorter than the distance between the hinges when the conventional hinges are arranged in a plane. As a result, the displacement magnification rate of one displacement magnification mechanism can be increased, so that the operation amount (stroke) of the printing wire necessary for the printing operation can be obtained with only one stage amplification using only one arm.

Therefore, compared to the conventional two-stage amplification using two arms, the equivalent mass of the arm is smaller. Furthermore, since the bending rigidity of the hinge portion is increased, the natural frequency of the displacement magnification mechanism is increased, and the response frequency of the printing operation of the printing hammer is therefore increased, making it possible to obtain a printing hammer that can operate at high speed.

Further, since it is fixed to the fixing member via the piezoelectric element and the fourth hinge, the bending stress generated in the piezoelectric element during printing operation can be alleviated, and the printing hammer is highly reliable and has a long life. In this case, the natural frequency of the printing hammer is lower than when the piezoelectric element is directly fixed to the fixing member, but it is sufficiently higher than the conventional one.
Therefore, the present invention is particularly suitable for use in printing hammers that require high reliability and long life even if the printing speed is sacrificed a little.

Further, since the displacement amount enlarging mechanism is also composed of only one arm and three hinges, the structure of the printing hammer is simplified, and an inexpensive printing hammer can be obtained.

〔Example〕

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

FIG. 1 is a perspective view showing a first embodiment of the present invention;
2 is an enlarged perspective view showing the arrangement of the first to third hinges in the embodiment shown in FIG. 1, and FIG. 3 is a perspective view showing the operating state of the embodiment shown in FIG.

In FIG. 1, an arm 1 has a thin plate-shaped first hinge 2 at its end 1a, and thin plate-shaped second and third hinges 3 and 4 provided on both sides of the hinge in the lateral direction (width direction). have. The first hinge 2 is
It is connected to the end surface of one end 5a of the piezoelectric element 5 in the expansion/contraction direction (arrow B), and one ends of the second and third hinges 3 and 4 are connected to the end surface of the fixing member 6. The other end 5b of the piezoelectric element 5 in the expansion/contraction direction is coupled to the fixing member 6 via the fourth hinge 8. That is, one end of the fourth hinge 8 is connected to the end of the piezoelectric element 5, and the other end is connected to the fixing member 6. A printing wire 7 is coupled to the other end 1b of the arm 1.

FIG. 2 is a perspective view showing details of the arrangement of the first, second, and third hinges 2, 3, and 4 of the embodiment shown in FIG. Second and third hinge 3
and 4 are provided on both the left and right (width direction) sides of the first hinge 2, and are offset from the position of the first hinge 2 in the height (thickness) direction, with a step of a predetermined dimension. have. The second hinge 3 and the third hinge 4 are arranged at the same height.

When a voltage is applied to the piezoelectric element 5 of the printing hammer having such a configuration, the operation shown in FIG. 3 is performed. That is, the piezoelectric element 5 expands in the direction of arrow B1 and displaces the first hinge 2 in the direction of arrow B1. On the other hand, one end of the second and third hinges 3 and 4 is fixed to the fixing member 6, and the other end is fixed to the arm 1, and since there is a step between them and the first hinge 2, the thin plate-like first and third hinges The second and third hinges 2, 3, and 4 undergo bending deformation in the direction of arrow C, and the arm 1 also causes rotational movement in the direction of arrow C. As a result, the printing wire 7 connected to the tip of the arm 1 is transmitted with the amount of displacement of the piezoelectric element 5 magnified, and moves in the direction of arrow D to perform a printing operation.

In this way, in the printing hammer of this embodiment, the second and third hinges 3 and 4 are provided on both sides of the first hinge 2 in the lateral direction (width direction), and the height (thickness) direction is Position the first hinge 2
The distance between the center line of the first hinge 2 and the center lines of the second and third hinges 3 and 4 can be reduced by arranging the center line so as to have a step between the two hinges. can be shortened compared to a planar arrangement. As a result, the displacement magnification rate of the displacement magnification mechanism can be increased, so even if only one arm is used, it is possible to give the printing wire the necessary amount of movement (stroke) for its printing operation. can.

Therefore, compared to the conventional case where two arms are used, the equivalent mass of the arm is smaller, so the natural frequency of the displacement magnification mechanism becomes higher, and the response of the printing operation of the print head becomes smaller. A printing hammer capable of high-speed operation is obtained by increasing the frequency.

Furthermore, since the piezoelectric element 5 is fixed to the fixing member 6 via the fourth hinge 8, the bending stress generated in the piezoelectric element 5 during the printing operation can be alleviated, resulting in high reliability and long life. It becomes a printing hammer.

Further, as described above, since the displacement amount enlarging mechanism is composed of one arm and three hinges, the structure is simple and an inexpensive printing hammer can be obtained.

FIGS. 4a and 4b are a plan view and an
It is an X-ray cross-sectional view.

In FIG. 4, each of the plurality of arms 41 has a thin plate-like first hinge 42 at its end 41a.
and two thin plate-like second and third hinges 43 and 44 provided on both sides in the width direction (horizontal direction) with the two hinges sandwiched therebetween. The first hinge 42 is coupled to one end of a correspondingly provided piezoelectric element 45 in the expansion/contraction direction, and the second and third hinges 43 and 44 are coupled to an end surface of a fixing member 46. The other end 45b of the piezoelectric element 45 in the expansion and contraction direction
is coupled to the fixing member 46 via a fourth hinge 48. A printing wire 47 is coupled to the other end 41b of each arm 41, respectively.

The fixing member 46 is a single member and is commonly used for all printing hammers. That is, it is a part of the member constituting the main printing head, and is provided corresponding to the second and third hinges 43 and 44 of all the printing hammers, and is configured to fix each of them. Therefore, the second and third hinges 43 and 44 of each printing hammer are connected at one end to the end 41a of the respective corresponding arm 41, and at the other end to the common fixing member 4.
It is fixed at 6. In addition, all piezoelectric elements 4
5 is also fixed to this one common fixing member 46 via a fourth hinge 48.

The positional relationship between the first hinge 42, the second hinge 43, and the third hinge 44 is the same as that in the embodiment shown in FIG.
are provided on both sides of the first hinge 42 in the width direction, and are arranged at the same height with a step between them and the first hinge 42 in the thickness direction.

Each print hammer of the print head configured in this manner operates in the same manner as the print hammer of the first embodiment, and therefore provides similar effects.

〔Effect of the invention〕

As explained above, the print head of the present invention has
Since the structure is simple, it can be manufactured at low cost, and since the response frequency is high, high-speed printing operation can be performed. Furthermore, since the bending stress applied to the piezoelectric element can be alleviated, a highly reliable and long-life printing hammer can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a first embodiment of the present invention;
Fig. 2 is an enlarged perspective view showing the arrangement of the first to third hinges in the embodiment shown in Fig. 1, Fig. 3 is a perspective view showing the operating state of the embodiment shown in Fig. 1, and Figs. 4 a and b.
are a plan view and a sectional view taken along line X-X showing an example of a printing head constructed using the second embodiment of the present invention;
FIG. 5 is a side view showing an example of a conventional printing hammer, where a shows a non-operating state and b shows an operating state. 1,41,54,57...Arm, 2,42...First hinge, 3,43...Second hinge, 4,44...Third hinge, 5,45,51...Piezoelectric element, 6,4
6, 50... Fixing member, 7, 47, 58... Printing wire, 8, 48... Fourth hinge, 52, 53, 55,
56...Joining part.

Claims (1)

[Claims] 1. An arm having a printing wire fixed to one end thereof, and one end of the arm fixed to the center of the other end of the arm, the width direction of which is arranged perpendicular to the direction of movement of the printing wire. a thin plate-shaped first hinge; a piezoelectric element having one end fixed to the first hinge; and a piezoelectric element disposed on the left and right sides of the first hinge in the width direction, and second and third thin plate-like plates having equal steps of predetermined dimensions in the direction of movement of the printing wire, one end of which is fixed to the other end of the arm, and the other end of which is fixed to a fixing member; A printing hammer comprising: a hinge; and a fourth hinge having one end fixed to the other end of the piezoelectric element and the other end fixed to the fixing member.