JPH0364313B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing unit, particularly for use in a print head of a dot matrix printer.

Conventionally, there is a printing unit that performs a printing operation by utilizing distortion caused by the piezoelectric transverse effect of piezoelectric or electrostrictive ceramics.

FIG. 1 is a side view of a conventional printing unit. The printing unit shown in the figure fixes one end of a piezoelectric vibrator, which has piezoelectric plates 41 and 42 fixed to both sides of a conductive electrode plate 3, to the mounting member 1, and prints dots on the other end of the piezoelectric vibrator. It is constructed by fixing a pin 14. When a driving voltage is applied through the conductive wire 6 between the two electrodes 5 and the electrode plate 3 of the piezoelectric vibrator, the piezoelectric plate 41 extends in the direction shown by the arrow A due to the piezoelectric transverse effect, and the piezoelectric plate 42 extends in the direction shown by the arrow A. It contracts in the direction of B, causing deflection in the piezoelectric vibrator. In response to this deflection, the pin 14 moves in the direction of arrow C, striking a dot on the printing surface and performing a printing operation.

Since such conventional printing units utilize piezoelectric transverse effects, they have a small electromechanical coupling coefficient and therefore consume a large amount of driving power.In addition, piezoelectric vibrators are used to provide displacement to the pins for printing. The disadvantage is that the volume must be increased.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a printing unit that consumes less power and has a smaller volume than the conventional printing unit.

The unit of the present invention includes a piezoelectric body that generates dimensional distortion due to a piezoelectric longitudinal effect in accordance with a voltage applied to an electrode, a fixing member that fixes and supports one end of the piezoelectric body, and a fixing member that fixes and supports one end of the piezoelectric body. second and third connecting members each having one end connected to a first connecting member connected to the other end and transmitting the dimensional strain of the piezoelectric body;
a fourth connecting member, one end of which is connected to the other end of the second connecting member and the first predetermined location of the fixing member.
a first movable member which is connected to the other end of the coupling member and which produces a first angular displacement in response to the dimensional strain transmitted from the second coupling member; The second end is connected to the other end of a fifth coupling member whose one end is connected to the second predetermined location of the fixing member, and the second a second movable member that causes angular displacement; a sixth coupling member having one end connected to a predetermined location of the first movable member; and a seventh coupling member having one end connected to a predetermined location of the second movable member. are connected to the other ends of each of the sixth and seventh
a third movable member that generates a third angular displacement in response to the first and second angular displacements transmitted through the coupling member; and a printing member that moves in a predetermined direction in response to the third angular displacement.

In the printing unit of the present invention, displacement for performing printing operation is obtained by piezoelectric longitudinal effect. In the piezoelectric longitudinal effect, the electromechanical coupling coefficient is larger (usually more than twice) than in the case of the piezoelectric transverse effect, so the conversion efficiency from electrical energy to mechanical energy is large (square of the ratio of the electromechanical coupling coefficient, that is, (approximately 5 times as much), therefore, less driving power is required than in the past to obtain the same mechanical energy. Furthermore, in the piezoelectric longitudinal effect, the strain obtained is larger than in the case of the piezoelectric transverse effect (Poisson's number times, or about 3 times), so the mechanical energy stored per unit volume is large (Poisson's number squared, or about 9 ), therefore, the volume required to store the same mechanical energy is smaller than that of the conventional method.

The present invention will be described in detail below with reference to the drawings.

Figures 2a and 2b are a perspective view and a side view, respectively, showing a first embodiment of the invention. One end of the piezoelectric body 4, which causes strain due to the piezoelectric longitudinal effect, is fixed to a metal fixing member 2, and the other end of the piezoelectric body 4 is fixed to a first coupling member 10 made of metal. The first coupling member 10 is integrally provided with second and third coupling members 12 and 14. The second coupling member 12 is connected to one end of the first movable member 13, and the first movable member 13 has a fourth coupling member 16 at a predetermined distance from the second coupling member 12. Connected. The third coupling member 14 is connected to one end of the second movable member 15, and the second movable member 15 has a fifth coupling member 18 at a predetermined distance from the third coupling member 14. Connected. The fourth and fifth coupling members 16 and 18 are connected to the fixing member 2, respectively.
is connected to and supported by the end of the 1st and 2nd
At the other ends of the movable members 13 and 15, respectively, are sixth and seventh coupling members 20 and 2 of metal plates.
One end of each of the two is fixed. The other ends of the sixth and seventh coupling members 20 and 22 are each fixed to a predetermined location of a third movable member 21 made of metal, and a metal round bar is attached to the tip of the third movable member 21. A pin 24 is attached and fixed.
Note that the fixing member 2 is connected to the first to fifth coupling members 1
0, 12, 14, 16 and 18, together with the first and second movable members 13 and 15, are integrally formed of metal, thereby reducing the steps required to assemble the unit. Piezoelectric body 4
Conductive wires 6 are connected to electrodes 5 provided on both sides of the piezoelectric body 4, and when a driving voltage is applied through the conductive wires 6, mechanical strain is generated in the piezoelectric body 4 due to the piezoelectric longitudinal effect.

When a driving voltage is applied and the piezoelectric body 4 extends in the direction shown by the arrow F in FIG. The signals are then transmitted to the first and second movable members 13 and 15, respectively. In the first and second movable members 13 and 15 that have received this strain, the fourth and fifth movable members, respectively,
The sixth and seventh coupling members 20 and 22 are supported by the fixed member 2 through the coupling members 16 and 18, respectively, so that a rotational moment is generated and the sixth and seventh coupling members 20 and 22
Displacement occurs in the directions shown by arrows G and H at the location where the is fixed. Since the two displacements in the directions of arrows G and H are opposite to each other, a couple acts on the third movable member 21, causing the pin 24 to move in the direction of arrow K to perform a printing operation.

In the operation described above, the first (or second) movable member 13 (or 15)
(or fifth) coupling member 16 (or 18)
The movement of the lever with the supporting axis is expanded to expand the displacement due to the strain applied from the second (or third) coupling member 12 (or 14), and the sixth (or seventh) coupling member 20 (or 22)
It acts as a displacement amplifying means for transmitting data to This 2
The two displacement amplifying means transmit a couple of forces that cause two displacements in opposite directions to the third movable portion 21, thereby giving the pin 24 enough displacement to perform a printing operation.

FIGS. 3a to 3f are side views showing an example of the configuration of the displacement amplifying means described above. The lever L is the first (or second) movable member 13 (or 15),
One of the plate-shaped coupling parts P and Q is attached to the second (or third) coupling member 12 (or 14), and the other is attached to the fourth (or fifth) coupling member 16.
(or 18) respectively. For example, in the displacement amplifying means shown in FIG.
(or Q) as the fourth coupling member 16, coupling portion Q (or P) as the second coupling member 14,
Furthermore, if the lever L is used as the first movable member 13, the coupling part P (or Q) becomes the pivot of the lever L, and the displacement in the direction of the arrow D given from the coupling part Q (or P) is expanded. Then, the displacement is transmitted to the other end of the lever L in the direction of arrow E ₁ (or dotted arrow E ₂ ). By forming the coupling portions P and Q into plate shapes, stable displacement transmission with little lateral vibration can be achieved. Although FIGS. 3a to 3f show a case in which the plate surfaces of the connecting portions P and Q are parallel or perpendicular to each other, it is clear that a configuration in which both plate surfaces are oblique to each other is also possible.

In the printing unit shown in FIGS. 2a and b, 2
The configuration shown in FIG. 3c is applied to each of the displacement amplifying means. When one of the configurations shown in FIGS. 3a to 3f is selected as the configuration of the two displacement amplifying means and the two are combined, the strain generated in the piezoelectric body 4 is magnified and the third movable member 21 Since the number of combinations that give a couple is very large, it would be unnecessary to list them all, and two examples are shown below.

Figures 4a and 4b are side views showing second and third embodiments of the invention, respectively. For ease of contrast between the drawings, parts having the same function have been provided with the same reference numerals as in FIG. 2b, even though they have different shapes. Both of the two displacement amplifying means of the unit shown in FIG. 4a use the configuration shown in FIG. 3a, and one of the two displacement amplifying means of the unit shown in FIG. 4b uses the configuration shown in FIG. The other uses the configuration shown in FIG. 3e, and the other uses the configuration shown in FIG. In either case, the arrow F generated on the piezoelectric body 4
The strain in the direction of is transmitted through the two displacement amplifying means, and a couple of forces in the directions of arrows G and H act on the third movable member 21, and in response, the pin 24 moves in the direction of arrow K to print. Perform the action. In either case, the first to seventh coupling members 10, 12, 14, 16, 18, 20 and 22 and the first to third movable members 13, 15 and 21 are integrated together with the fixed member 2. This reduces the assembly process of the unit. Furthermore, by forming the fixing member 2 into a U-shaped structure, the fixing member 2 is made difficult to deform, so that the energy of strain generated in the piezoelectric body 4 is not consumed to deform the fixing member 2. .

FIGS. 5a to 5c are perspective views showing examples of the formation of plate-shaped portions of each joint. In the units shown in Fig. 2b and Figs. 4a and b, the second to seventh
The coupling members 12, 14, 16, 18, 20 and 22 are all formed in a plate shape, and the piezoelectric body 4
The displacement is transmitted to the pin 24 while bending in accordance with the strain generated in the pin 24. In order to further reduce the energy consumed for this bending, the plate thickness can be reduced, but if the plate thickness is too small, it becomes difficult to transmit strain. FIGS. 5a to 5c show examples of formation for solving this difficulty. Figures a and b show grooves formed on one plate surface and both plate surfaces, respectively, so as to have portions where the plate thickness is small. Figure c shows a structure in which a thin plate piece is joined between two plates to provide a portion with a small plate thickness. By providing such a portion with a small plate thickness, it is possible to reduce the energy consumed in bending during strain transmission and to perform a good strain transmission operation.

FIGS. 6a and 6b are perspective views showing an example of the structure of the piezoelectric body 4 used in the unit of the present invention. In each case, a plurality of electrodes 51 and 52 are provided inside the piezoelectric body 4, arranged alternately and parallel to each other, and the electrode 51 is connected to one of the pair of electrodes 5, and the electrode 52 is connected to the other. FIG. 6a shows a case where a piezoelectric material such as zircon/lead titanate is used. Polarization treatment in a predetermined direction, for example, the direction shown by arrow J, is performed between electrodes 51 and 52. When a driving voltage in the same direction (or in the opposite direction) as the polarization is applied between the electrodes 51 and 52 via the electrode 5, a strain is generated in the piezoelectric body 4 in the direction of the arrow T (or S). Therefore, by selecting the polarity of the drive voltage, it is possible to generate distortion in a desired direction. FIG. 6b shows a case where an electrostrictive material such as manganese lead niobate is used. In this case,
Generates strain in the direction of arrow T regardless of the polarity direction of the drive voltage applied between electrodes 51 and 52;
It has the advantage of operating with little hysteresis. By providing a multilayer electrode in which a plurality of electrodes 51 and 52 are arranged alternately as shown in FIGS. 6a and 6b, large strain due to the piezoelectric longitudinal effect of the piezoelectric body 4 can be generated with a low driving voltage.

As is clear from the above description, the present invention includes:
By magnifying and transmitting the strain caused by the piezoelectric longitudinal effect to perform a printing operation, it is possible to realize a printing unit that consumes less power and has a smaller volume than conventional printers.

[Brief explanation of drawings]

FIG. 1 is a side view showing a conventional printing unit; FIGS. 2a, 5a-c, and 6a, b are perspective views showing an embodiment of the present invention; FIGS. a~
f and FIGS. 4a and 4b are side views showing an embodiment of the present invention. 2... Fixed member, 4... Piezoelectric body, 5, 51, 5
2... Electrode, 6... Conductor wire, 10... First coupling member, 12... Second coupling member, 13... First movable member, 14... Third coupling member, 15... Third coupling member 2
movable member, 16... fourth coupling member, 18...
Fifth coupling member, 20...Sixth coupling member, 21
...Third movable member, 22...Seventh coupling member,
24...Pin.

Claims (1)

[Scope of Claims] 1. A piezoelectric body that generates dimensional distortion due to a piezoelectric longitudinal effect in accordance with a voltage applied to an electrode, a fixing member that fixes and supports one end of the piezoelectric body, and a piezoelectric body that fixes and supports one end of the piezoelectric body. second and third coupling members each having one end connected to the first coupling member connected to the other end of the piezoelectric body and transmitting the dimensional strain of the piezoelectric body; and the other end of a fourth coupling member having one end connected to the first predetermined location of the fixing member, and a first corner corresponding to the dimensional strain transmitted from the second coupling member. The first one that causes displacement
a movable member, and a fifth member having one end connected to the other end of the third coupling member and a second predetermined location of the fixed member.
a second movable member that is connected to the other end of the coupling member and causes a second angular displacement in response to the dimensional strain transmitted from the third coupling member; a sixth coupling member having one end connected to a predetermined location of the second movable member; and a seventh coupling member having one end connected to a predetermined location of the second movable member; a third movable member that produces a third angular displacement in response to the first and second angular displacements transmitted through the third movable member;
It is attached to a predetermined location of the movable part of the third
1. A printing unit comprising: a printing member that moves in a predetermined direction in response to an angular displacement of the printing member. 2. The second and fourth coupling members are each plate-shaped, and their plate surfaces form a predetermined angle, and the dimensional distortion of the piezoelectric body is caused to occur substantially along the plate surface of the second coupling member. 2. The printing unit according to claim 1, wherein a rotational moment is transmitted to the first movable member to generate a rotational moment about an axis substantially parallel to an end of the fourth coupling member connected to the fixed member. 3. The third and fifth coupling members are each plate-shaped, and their plate surfaces form a predetermined angle, and the dimensional distortion of the piezoelectric body is caused by the third coupling member substantially along the plate surface of the third coupling member. 2. The printing unit according to claim 1, wherein the rotational moment is transmitted to the second movable member to generate a rotational moment about an axis substantially parallel to an end of the fifth coupling member connected to the fixed member. 4. The sixth and seventh coupling members are each plate-shaped, and their plate surfaces form a predetermined angle, and the first and second angular displacements correspond to the plate surfaces of the sixth and seventh coupling members, respectively. is transmitted to the third movable member substantially along the axis to generate a rotational moment about an axis substantially parallel to the end sides of the sixth and seventh coupling members connected to the third movable member. A printing unit according to claim 1. 5. The printing unit according to any one of claims 2 to 4, wherein the plate-shaped second to seventh coupling members are formed with portions having different plate thicknesses. 6. The fixing member includes a first attachment part that fixes one end of the piezoelectric body, and is integrated with the first attachment part and is provided in parallel on both sides of the piezoelectric body at each predetermined location. 2. The printing unit according to claim 1, wherein the printing unit is formed in a U-shape, and has second and third attachment portions for connecting the fourth and fifth coupling members. 7. The piezoelectric body has a portion made of a piezoelectric material in which a plurality of electrodes are arranged approximately parallel to each other at predetermined intervals alternately, and a polarization process is performed in a predetermined direction between the plurality of electrodes. Claim No. 1
Printing unit as described in section. 8. The printing unit according to claim 1, wherein the piezoelectric body has a portion made of an electrostrictive material in which a plurality of electrodes are provided substantially parallel to each other at predetermined intervals alternately. 9. The printing according to claim 1, wherein at least any two of the first to seventh coupling members, the first to third movable members, and the fixed portion are integrally formed. unit.