JPH0420276B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrostrictive body driving device for displacing a plurality of driving bodies made of a material having an electrostrictive effect.

Conventional Structure and Problems There has been a device for reciprocating a material having an electrostrictive effect, and an example of such a device is shown in FIGS. 1 and 2. In FIGS. 1 and 2, 6 is a bimorph, which is made by laminating two thin plate-like piezoelectric ceramics. This piezoelectric ceramic has electrodes formed on a bonded surface and a surface opposite to the bonded surface, and is subjected to polarization treatment. bimorph 6
The electrodes on the bonded surfaces of the piezoelectric ceramics are common, and this electrode is connected to the terminal 7. Further, the electrodes on the surfaces opposite to the bonded surfaces of the respective piezoelectric ceramics are also common and connected to the terminals 8. In FIG. 2, bimorphs 11 and 12 have exactly the same structure as bimorph 6, and terminals 13 and 14 and terminals 15 and 16 are drawn out, respectively. These bimorphs 6,1
1 and 12 have their right ends fixed by a fixture (not shown), and by applying voltage between terminals 7, 8, terminals 13, 14, and terminals 15, 16, the left end of the bimorph is fixed as shown in the figure. It is bent and displaced in the A direction or the B direction. A wire 17 is attached to the tips of the bimorphs 6, 11, and 12, and the tips of the wires 17 are positioned opposite the platen 20 with the ink ribbon 18 and recording paper 19 interposed therebetween. The tip of the wire 17 is configured to come into contact with the ink ribbon 18 when the bimorphs 6, 11, and 12 are displaced in the direction B shown in the figure, and further press the ink ribbon 18 against the recording paper 19 and the platen 20. By this operation, printing is performed on the recording paper.

Bimorphs 6, 11, and 12 are connected to a circuit as shown in FIG. 1, but since they have similar configurations, only the circuit for bimorph 6 is shown in FIG. Reference numeral 1 denotes a drive signal generation circuit, which is a circuit for generating a signal for driving the bimorph. Reference numerals 2, 3, 4, and 5 are switching transistors, each of which functions to flow a current between the collector and emitter when a potential difference of more than a predetermined value occurs between the emitter and the base. The transistors 2 and 4 are connected to the drive signal generation circuit 1,
When a drive signal is supplied, each turns on,
Configured to conduct current. When a drive signal is supplied to transistor 2, transistor 2 is turned on, and current flows through transistor 2. Therefore, a potential difference is generated between the base and emitter of the transistor 3, and the transistor 3 is also turned on. At this time, no drive signal is supplied to transistor 4, transistor 4 is off, and therefore transistor 5 is also off. Since the transistor 3 is on and the transistor 5 is off, the potential of the terminal 7 is approximately equal to the potential of the positive electrode of the power supply 9. Also, terminal 8
The potential of is equal to the potential of the load of the power supply 9. Therefore, a voltage approximately equal to the potential difference between the two poles of the power source 9 is applied to the bimorph 6. At this time, the bimorph 6 is bent and displaced in the direction A shown in FIG.

Next, when transistor 2 is turned off and transistor 4 is turned on, transistor 3 is turned off and transistor 5 is turned on in the same manner as described above. At this time, the potential of the terminal 7 becomes approximately equal to the potential of the negative electrode of the power supply 10. Further, the potential of the terminal 8 is equal to the potential of the positive electrode of the power source 10. Therefore, a voltage approximately equal to the potential difference between the two electrodes of the power source 10 is applied to the bimorph 6. At this time, the direction of the voltage applied to the bimorph 6 is opposite to the direction of the voltage when the transistor 2 is turned on and the transistor 4 is turned off. Therefore, at this time, the bimorph 6 is bent and displaced in the direction of arrow B shown in FIG. Bimorphs 11 and 12 also have the same circuit configuration as bimorph 6.

Next, the operation of this device will be explained. When the bimorph 6 is driven to perform printing, first, a drive signal is issued by the drive signal generation circuit 1, the transistor 2 is turned on, and the transistor 4 is turned off. This turns transistor 3 on and transistor 5 off. Therefore, as described above, a voltage approximately equal to the voltage of the power supply 9 is applied to the bimorph 6, and the bimorph 6 is bent in the direction A shown in FIG.

Next, the drive signal turns off transistor 2 and turns on transistor 4. Therefore, transistor 3 is turned off and transistor 5 is turned on. As a result, a voltage approximately equal to the voltage of the power supply 10 is applied to the bimorph 6, and the direction of the voltage at this time is opposite to that previously, and the bimorph 6
is bent and displaced in the direction B shown in FIG. By displacing the bimorph 6 in the B direction, the tip of the wire 17 is pressed against the recording paper 19 and platen 20 of the ink ribbon 18. As a result, printing is performed on the recording paper 19. At this time, the bimorph 6 is displaced in the direction A shown in the figure and then in the direction B shown in the figure, but this is done by displacing the bimorph 6 in the opposite direction to store potential energy, and then displacing it in the forward direction. This is to ensure a large amount of displacement. The operations of bimorphs 11 and 12 are performed in the same manner. As described above, in the conventional electrostrictive body driving device, each electrostrictive body is independently driven back and forth, so the circuit configuration is complicated, the number of parts is large, and the device is expensive.

OBJECTS OF THE INVENTION An object of the present invention is to provide an electrostrictive body driving device that has a small number of parts, a simple circuit configuration, and is inexpensive.

Structure of the Invention The electrostrictive body driving device of the present invention includes a plurality of driving bodies, at least a part of which is made of an electrostrictive material and is displaced by applying an electric field, and a first a first electric field applying means that operates to displace each of the driving bodies in a second direction opposite to the first direction; and a second electric field applying means that operates to selectively displace each of the driving bodies in a second direction opposite to the first direction. Therefore, the circuit configuration is simple, and the number of parts is small, making it possible to create an inexpensive electrostrictive body driving device.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 is a circuit diagram of an electrostrictive body driving device according to an embodiment of the present invention, and FIG. 4 is a partial perspective view of the same device. In Figures 3 and 4, 25, 26, 2
Reference numeral 7 denotes a bimorph serving as a plurality of driving bodies, which is made by laminating two sheets of electrostrictive thin plate-like piezoelectric ceramics. This piezoelectric ceramic has electrodes formed on a bonded surface and a surface opposite to the bonded surface, and is subjected to polarization treatment. Bimorphs 25, 26, and 27 each have a common electrode on the bonded surface of piezoelectric ceramics, and terminals 28, 3, respectively.
0,32. In addition, the electrodes on the surface opposite to the bonded surface of each piezoelectric ceramic are also common, and each bimorph 2
5, 26, 27, terminals 29, 3 respectively
1 and 33. bimorph 25,2
6 and 27 are fixed at their right ends with a fixture (not shown), and a wire 36 is attached to their left ends. Bimorphs 25, 26, and 27 have terminals 28, 29, 30, 31, and 32, 33, respectively.
By applying a voltage between them, the left end of each bimorph is bent and displaced in the C direction or D direction shown in the figure. The tip of the wire 36 is located at a position facing the platen 39 with an ink ribbon 37 and a recording paper 38, which is a contact object and a recording medium, sandwiched therebetween. The tip of the wire 36 comes into contact with the ink ribbon 37 when the bimorphs 25, 26, 27 are displaced in the direction D shown in the figure, and the ink ribbon 37 is transferred to the recording paper 38 and the platen 39.
It is configured to be pressed against the This operation transfers the ink to the recording paper and prints.

Bimorphs 25, 26, 27 are connected to a circuit as shown in FIG. In the figure, reference numeral 21 denotes a drive signal generation circuit that generates a signal for driving the bimorph and constitutes timing means for determining the timing of driving the bimorph. 22,2
3 and 24 are switching transistors constituting the second electric field applying means, and 34 is a switching transistor constituting the first electric field applying means. Transistors 22, 23, 24, 3
4 functions to flow a current between the collector and emitter when a potential difference of a predetermined value or more occurs between the base and emitter. These transistors 2
2, 23, 24, and 34 are connected to the drive signal generation circuit 21, and are configured so that when a drive signal is supplied, each turns on and current flows.
When transistor 34 is turned on, terminals 29,3
The potentials of the terminals 1 and 33 become approximately equal to the ground potential, and when the transistors 22, 23, and 24 are turned on, the potentials of the terminals 28, 30, and 32 become approximately equal to the ground potential. Further, when the transistors are off, the potential of the terminal connected to the emitter terminal of each transistor is equal to the potential of the positive electrode of the power supply 35. Therefore, for example, only the transistor 34 is turned on,
When the other transistors are off, terminals 28, 3
The potentials of terminals 0 and 32 are equal to the potential of the positive electrode of the power supply 35, and the potentials of terminals 29, 31, and 33 are approximately equal to the ground potential. At this time, bimorph 25,2
A voltage approximately equal to the potential difference between the two poles of the power supply 35 is present across both ends of the bimorphs 6 and 27, and at this time the bimorphs 25, 26 and 27 are displaced in the direction C in FIG. Further, when the transistor 34 is turned off and one of the transistors 22, 23, and 24 is turned on, the potential of the terminal connected to the transistor that is turned on among the terminals 28, 30, and 32 is approximately equal to the ground potential. Therefore, the potential of the terminal connected to the turned-off transistor becomes equal to the potential of the positive electrode of the power supply 35. Therefore, at this time, the bimorph connected to the transistor that is turned off among the transistors 22, 23, and 24 has the same potential at both ends and is not displaced. Further, a voltage approximately equal to the voltage between the two poles of the power supply 35 is applied to the bimorph connected to the transistor that is turned on, but the direction of the voltage at this time is different from that when the transistor 34 is turned on. It is in the opposite direction. Therefore, this bimorph is displaced in the direction D shown in FIG.

Next, the operation of this device will be explained. A case where the printing operation is performed only by the bimorph 25 will be described. At this time, first, a drive signal is issued by the drive signal generation circuit 21, and only the transistor 34, which is the first electric field applying means, is turned on.
As a result, the potentials of the terminals 29, 31, and 33 become approximately equal to the ground potential. Terminals 28, 30, 3
Since the potential of 2 is equal to the potential of the positive electrode of the power source 35, a voltage is applied across the bimorphs 25, 26, and 27, and the bimorphs 25, 26, and 27
bending displacement in the direction.

Next, the drive signal generation circuit outputs a drive signal at a certain timing, turning off the transistor 34, and only the transistor 22 among the transistors 22, 23, and 24 serving as the second electric field applying means. turns on. As a result, the potentials at the terminals 29, 31, and 33 rise to the potential of the positive electrode of the power supply 35, and the voltage at the terminal 28 drops to a potential approximately equal to the ground potential. The potentials of the terminals 30 and 32 do not change and remain equal to the potential of the positive electrode of the power supply 35. At this time, the bimorphs 26 and 27 return to their neutral positions because no voltage is applied between their ends. Further, a voltage in the opposite direction to that when the transistor 34 is turned on is applied to the bimorph 25, so that the bimorph 25 is displaced in the direction D in FIG.
At this time, the tip of the wire 36 of the bimorph 25 is
The ink ribbon 37 is attached to the recording paper 38 and the platen 39.
The ink is transferred onto the recording paper 38 to perform printing. The same applies when driving the bimorphs 26 and 27. The reason why the bimorph is displaced in the C direction and then in the D direction is that when the bimorph is displaced in the C direction, it is stored as potential energy and then used as a reaction when it is displaced in the D direction. This is to increase the amount of displacement.

Effects of the Invention As is clear from the above description, the electrostrictive body driving device of the present invention can simultaneously displace a plurality of driving bodies made of a material having an electrostrictive effect in one direction, and selectively displace them in the other direction. Because we are trying to displace the
The circuit configuration is simple and the number of parts is small, so the device can be provided at low cost.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional electrostrictive body driving device, FIG. 2 is a partial perspective view of the same device, FIG. 3 is a circuit diagram of an electrostrictive body driving device according to an embodiment of the present invention, and FIG. is a partial perspective view of the same device. 21... Drive signal generation circuits 25, 26, 27... Bimorph.

Claims (1)

[Scope of Claims] 1. A plurality of driving bodies, at least a portion of which is made of an electrostrictive material and is displaced by applying an electric field from the outside, and a power source for applying voltage to the driving bodies; a first electric field applying means for applying a voltage of the power source to the driving bodies so as to displace all of the driving bodies in a first direction, and selectively opposite to the first direction with respect to each of the driving bodies; an electrostrictive body driving device, comprising a second electric field applying means for applying a voltage opposite to a voltage applied by the first electric field applying means to the driving body so that the driving body can be displaced in a second direction. 2. Timing means for ordering only those selected by the second electric field applying means to be displaced in the second direction after all of the driving bodies are displaced in the first direction by the first electric field applying means. An electrostrictive body driving device according to claim 1, characterized in that: 3. A patent characterized in that it has a contacted body at a position facing the driving body, and is configured such that the driving body comes into contact with the contacted body by displacement of the driving body in the second direction. Claim 1 or 2
The electrostrictive body drive device described in . 4. The object to be contacted is a recording medium, and printing is performed on the recording medium by contacting the driving body directly or indirectly through an ink ribbon. Electrostrictive body drive device.