Needle selection device, method for driving needle selection device, and program

Abstract

The present invention reduces the amount of electric power to be consumed and reduces the probability of trouble arising during use. This needle selection device of a knitting machine includes: a bimorph or unimorph piezoelectric drive element; and a drive means that applies a predetermined voltage between predetermined terminals of the piezoelectric drive element at the beginning of a period in which the piezoelectric drive element is bent in a predetermined direction and, during the period, insulates any of the terminals when a predetermined time has elapsed since the start of the application of the voltage between the terminals.

Description

Needle selection device, driving method and program for needle selection device

[0001] The present invention relates to a needle selector, a method for driving a needle selector, and a program, and more particularly to a needle selector for a knitting machine, a method for driving a needle selector for a knitting machine, and a computer program for controlling the needle selector for a knitting machine.

[0002] Piezoelectric drive elements are used in the needle selector of a knitting machine.

[0003] Conventionally, a piezoelectric driving element used in a needle selection device of a knitting machine has been proposed, which includes a substantially rectangular thin plate-shaped vibration plate in which two substantially rectangular thin plate-shaped piezoelectric elements are sandwiched between them, and which is a thin metal plate of substantially the same shape as the piezoelectric elements; a transmission section that clamps one of the ends of the shorter sides of the vibration plate, which transmits a driving force to the needle selection device, from both sides of the vibration plate; an end support section that clamps the other of the ends of the shorter sides of the vibration plate from both sides of the vibration plate; and an intermediate support section that straddles the longer sides of the vibration plate and clamps the middle part of the longer sides of the vibration plate from both sides of the vibration plate, and in which a hole is opened in one of the faces of the vibration plate in a direction that intersects with the face of the vibration plate and reaches the face of the vibration plate, and a first adhesive member is inserted into the hole and is adhered to the face of the vibration plate so as to fit into the hole, thereby fixing the intermediate support section to the vibration plate (see, for example, Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2017-103912

[0005] There is a demand for further reduction in the amount of power used for driving the needle selector of a knitting machine and for improvement in durability.

[0006] The present invention has been made in view of the above circumstances, and aims to reduce the amount of power consumed and the probability of malfunctions occurring during use.

[0007] A needle selection device according to one aspect of the present invention is a needle selection device for a knitting machine, and includes a bimorph or unimorph piezoelectric drive element, and drive means for applying a predetermined voltage between predetermined terminals of the piezoelectric drive element at the beginning of a period in which the piezoelectric drive element is bent in a predetermined direction, and for isolating one of the terminals when a first time has elapsed since the application of the voltage between the terminals began during the period.

[0008] The driving means may apply a voltage between the terminals when a second time has elapsed since the terminals were isolated during the period.

[0009] The driving means can apply a predetermined voltage between predetermined terminals of the piezoelectric driving element by means of a phototransistor of a photocoupler, and can insulate one of the terminals.

[0010] The driving means can apply a predetermined voltage between predetermined terminals of the piezoelectric driving element by a phototransistor of a photocoupler, and can insulate the terminals by a switch.

[0011] The switch can open and close the connection between the phototransistor of the photocoupler and the terminal of the piezoelectric driving element.

[0012] The switch can open and close between the piezoelectric driving element and a terminal that applies a predetermined voltage to the piezoelectric driving element.

[0013] The piezoelectric driving element may be a bimorph type and may be a three-wire type.

[0014] The piezoelectric drive element may be a two-wire connection.

[0015] A driving method for a needle selection device according to one aspect of the present invention is a driving method for a needle selection device of a knitting machine, in which, at the beginning of a period in which a bimorph or unimorph piezoelectric drive element is bent in a predetermined direction, a predetermined voltage is applied between predetermined terminals of the piezoelectric drive element, and when a predetermined time has elapsed since the start of application of the voltage between the terminals during the period, one of the terminals is insulated.

[0016] A program according to one aspect of the present invention causes a computer controlling a needle selection device of a knitting machine to execute processing including the steps of applying a predetermined voltage between predetermined terminals of a bimorph or unimorph piezoelectric drive element at the beginning of a period in which the piezoelectric drive element is bent in a predetermined direction, and isolating one of the terminals when a predetermined time has elapsed since the application of voltage between the terminals began during the period.

[0017] As described above, according to the present invention, it is possible to reduce the amount of power consumed and to reduce the probability of malfunctions occurring during use.

[0018] 1 is a perspective view showing the outer shape of the needle selection device 11 according to an embodiment of the present invention. FIG. 1 is a diagram explaining the displacement of a finger 21 by a piezoelectric drive element 31. FIG. 2 is a diagram showing an example of the configuration of a drive circuit. FIG. 3 is a block diagram explaining the hardware configuration of a microcontroller 74. FIG. 4 is a block diagram explaining the functional configuration of a microcontroller 74 realized by execution of a program. FIG. 5 is a flowchart explaining the process of driving the piezoelectric drive element 31 by the drive circuit 70. FIG. 6 is a graph showing the state of the piezoelectric drive element 31. FIG. 7 is a diagram showing another example of the configuration of the drive circuit. FIG. 8 is a flowchart explaining the process of driving the piezoelectric drive element 31 by the drive circuit 150. FIG. 9 is a diagram showing yet another example of the configuration of the drive circuit. FIG. 10 is a flowchart explaining the process of driving the piezoelectric drive element 31 by the drive circuit 180. FIG. 11 is a diagram showing an example of the configuration of a drive circuit that drives a piezoelectric drive element 31 in a two-wire connection system. FIG. 12 is a diagram showing another example of the configuration of a drive circuit that drives a piezoelectric drive element 31 in a two-wire connection system. FIG. 13 is a diagram showing yet another example of the configuration of a drive circuit that drives a piezoelectric drive element 31 in a two-wire connection system.

[0019] The following describes embodiments of the present invention. The correspondence between the constituent features of the present invention and the embodiments described in the Detailed Description of the Invention is exemplified as follows: This description is intended to confirm that the embodiments supporting the present invention are described in the Detailed Description of the Invention. Therefore, even if there is an embodiment described in the Detailed Description of the Invention that corresponds to a constituent feature of the present invention but is not described here, this does not mean that the embodiment does not correspond to that constituent feature. Conversely, even if an embodiment is described here as corresponding to a constituent feature, this does not mean that the embodiment does not correspond to constituent features other than the constituent feature.

[0020] A needle selection device according to one aspect of the present invention (e.g., needle selection device 11 in FIG. 1) is a needle selection device for a knitting machine, and includes a bimorph or unimorph piezoelectric drive element (e.g., piezoelectric drive element 31 in FIG. 3), and drive means (e.g., drive circuit 70 in FIG. 3) that applies a predetermined voltage between predetermined terminals of the piezoelectric drive element at the beginning of a period in which the piezoelectric drive element is bent in a predetermined direction, and isolates one of the terminals when a first time has elapsed since the application of the voltage between the terminals began during the period.

[0021] Hereinafter, a piezoelectric driving element according to an embodiment of the present invention will be described with reference to FIGS.

[0022] 1 is a perspective view showing the outer shape of a needle selector 11 according to an embodiment of the present invention. The needle selector 11 is attached to a knitting machine such as a flat knitting machine or a hosiery knitting machine. The needle selector 11 selects the operation of the knitting needles so that the knitting needles operate in accordance with the pattern.

[0023] The needle selector 11 is provided with a predetermined number of fingers 21, such as 4, 8, 16, or 32. Of the fingers 21 provided in the needle selector 11, fingers 21-1 to 22-5 are shown in Fig. 1. The fingers 21 select the operation of the knitting needles depending on their displaced positions. The fingers 21 are sliding or swinging type fingers. The fingers 21 are each displaced by a piezoelectric driving element (described later) built into the needle selector 11.

[0024] The left-right direction of the needle selection device 11 is illustrated as the X-axis, the up-down direction as the Z-axis, and the front-back direction as the Y-axis. Hereinafter, the lower left side of FIG. 1 in the Y-axis direction will be simply referred to as the front side, and the upper right side of FIG. 1 in the Y-axis direction will be simply referred to as the back side. Hereinafter, the left side of FIG. 1 in the X-axis direction will be simply referred to as the left side, and the right side of FIG. 1 in the X-axis direction will be simply referred to as the right side. Hereinafter, the upper side of FIG. 1 in the Z-axis direction will be simply referred to as the top side, and the upper side of FIG. 1 in the Z-axis direction will be simply referred to as the bottom side. The back side is the positive direction of the Y-axis, the left side is the positive direction of the X-axis, and the top side is the positive direction of the Z-axis. The Z-axis direction will also be simply referred to as the up-down direction, and the direction along a plane parallel to the X-axis and Y-axis will simply be referred to as the horizontal direction. This also applies to the following figures and descriptions.

[0025] FIG. 2 is a diagram illustrating the displacement of the finger 21 by the piezoelectric drive element 31. The piezoelectric drive element 31 is incorporated into the frame of the needle selector 11 and is charged and bent by an externally applied voltage. The finger 21 is rotatably attached to the frame of the needle selector 11. Because the end of the piezoelectric drive element 31 is engaged with the finger 21, when the piezoelectric drive element 31 bends, the finger 21 is displaced around the rotatable axis. The finger 21 selects the operation of the knitting needle depending on the displaced position. In other words, the piezoelectric drive element 31 displaces the finger 21 by bending. The piezoelectric drive element 31 is composed of a metal plate and piezoelectric elements superimposed on both sides of the metal plate, and is formed in the shape of a substantially rectangular thin plate. When an external voltage is applied, the piezoelectric drive element 31 is charged and bent. In other words, the piezoelectric drive element 31 bends so that the longitudinal end of the substantially rectangular shape is displaced in the thickness direction.

[0026] The piezoelectric driving element 31 is provided with a transmission section 41, a support section 42, and a support section 43. The piezoelectric driving element 31 is also configured to include a piezoelectric element 51, a piezoelectric element 52, and a plate 53. The piezoelectric driving element 31 is a bimorph type piezoelectric driving element.

[0027] The transmission portion 41, the support portion 42 and the support portion 43 are formed from a resin such as polyolefin, polypropylene, polyacetal, fluororesin or polycarbonate.

[0028] The transmission portion 41 is formed so as to sandwich one end in the longitudinal direction of the piezoelectric driving element 31 which is formed in the shape of a substantially rectangular thin plate.

[0029] The support part 42 is formed so as to sandwich one end in the longitudinal direction of the piezoelectric drive element 31 which is formed in the shape of a substantially rectangular thin plate, and when incorporated into the frame of the needle selector 11, is supported by (the frame of) the needle selector 11. The support part 43 intersects the piezoelectric drive element 31 in the short direction at approximately the middle position in the longitudinal direction of the piezoelectric drive element 31 which is formed in the shape of a substantially rectangular thin plate, protrudes from both sides in the longitudinal direction of the piezoelectric drive element 31, and is formed so as to sandwich the piezoelectric drive element 31. When incorporated into the frame of the needle selector 11, the support part 43 is rotatably supported by (the frame of) the needle selector 11.

[0030] The piezoelectric elements 51 and 52 are formed of a ternary piezoelectric ceramic such as PZT (PbZrO3-PbTiO3) (a solid solution of lead zirconate and lead titanate) or PZT solid-solution lead-based composite perovskite-type compound such as Pb(MG,Nb)O3 or Pb(Ni,Nb)O3, or other piezoelectric material. The piezoelectric elements 51 and 52 are formed as thin, approximately rectangular plates. The thickness of the piezoelectric elements 51 and 52 is 100 to 300 μm, and preferably 150 to 250 μm.

[0031] The plate 53 is made of a metal material that has the strength and conductivity to support the piezoelectric elements 51 and 52. Specifically, the plate 53 is made of stainless steel (SUS: Steel Use Stainless) or 42 Alloy. The plate 53 is formed as a thin, approximately rectangular plate that has approximately the same shape as the piezoelectric elements 51 and 52. The thickness of the plate 53 is 75 to 150 μm, and more preferably 75 to 125 μm.

[0032] An electrode film is formed on one surface of the piezoelectric element 51, that is, the outer surface (upper surface) (hereinafter referred to as the outer surface of the piezoelectric element 51), and another electrode film is formed on the other surface of the piezoelectric element 51, that is, the inner surface (the surface that contacts the plate 53) (hereinafter referred to as the inner surface of the piezoelectric element 51). Also, an electrode film is formed on one surface of the piezoelectric element 52, that is, the inner surface (the surface that contacts the plate 53) (hereinafter referred to as the inner surface of the piezoelectric element 52), and another electrode film is formed on the other surface of the piezoelectric element 52, that is, the outer surface (lower surface) (hereinafter referred to as the outer surface of the piezoelectric element 52). The electrode films formed on the piezoelectric element 51 or the piezoelectric element 52 are formed as thin films of gold or silver, etc., and are electrically conductive across the entire surface of the piezoelectric element 51 or the piezoelectric element 52, thereby uniformly charging the surface of the piezoelectric element 51 or the piezoelectric element 52 or removing charge from the entire surface of the piezoelectric element 51 or the piezoelectric element 52. The electrode film on the inner surface of the piezoelectric element 51 (the surface in contact with the plate 53), the plate 53, and the electrode film on the inner surface of the piezoelectric element 52 (the surface in contact with the plate 53) are electrically connected.

[0033] Although not shown in the drawings, the piezoelectric driving element 31 is provided with a terminal for electrical connection to the electrode film on the outer surface of the piezoelectric element 51, a terminal for electrical connection to the plate 53, and a terminal for electrical connection to the electrode film on the outer surface of the piezoelectric element 52. Note that the terminal for electrical connection to the electrode film on the outer surface of the piezoelectric element 51, the terminal for electrical connection to the plate 53, and the terminal for electrical connection to the electrode film on the outer surface of the piezoelectric element 52 are sufficient as long as they can be individually electrically connected to the electrode film on the outer surface of the piezoelectric element 51, the plate 53, and the electrode films on the outer surfaces of the piezoelectric element 52, respectively, and may be, for example, a male or female pin terminal as a single terminal, a male or female pin terminal as a terminal of a connector or coupler, a hole such as a through hole or via hole formed in the piezoelectric driving element 31 or an electric substrate, or the end of a conductor of an electric wire electrically connected to the piezoelectric driving element 31.

[0034] The piezoelectric elements 51 and 52 are polarized when used.

[0035] Of the ends of the fingers 21, the front end 61 is displaced to select the operation of the knitting needles. Of the ends of the fingers 21, the rear end 62 is formed in a groove shape. When the fingers 21 and the piezoelectric drive element 31 are incorporated into the needle selection device 11, the transmission part 41 of the piezoelectric drive element 31 is inserted into the end 62 which is formed in a linear groove shape. As a result, when the piezoelectric drive element 31 is bent, the fingers 21 are displaced.

[0036] 2, when a voltage is applied to the piezoelectric element 51, the piezoelectric driving element 31 bends so that the transmission part 41 is displaced upward. Since the finger 21 is pivotally fixed to the frame of the needle selection device 11, when the transmission part 41 of the piezoelectric driving element 31 is displaced upward, the end part 62 into which the transmission part 41 of the piezoelectric driving element 31 is inserted is displaced upward, and the end part 61 of the finger 21 is displaced downward.

[0037] 2, when a voltage is applied to the piezoelectric element 52, the piezoelectric driving element 31 bends so that the transmission part 41 is displaced downward. Since the finger 21 is pivotally fixed to the frame of the needle selection device 11, when the transmission part 41 of the piezoelectric driving element 31 is displaced downward, the end part 62 into which the transmission part 41 of the piezoelectric driving element 31 is inserted is displaced downward, and the end part 61 of the finger 21 is displaced upward.

[0038] Next, an example of a drive circuit that drives the piezoelectric drive element 31 will be described. Fig. 3 is a diagram showing an example of the configuration of the drive circuit. The drive circuit 70 applies a voltage to the piezoelectric drive element 31 and supplies a current to charge the piezoelectric element 51 or the piezoelectric element 52, thereby bending the piezoelectric drive element 31.

[0039] The drive circuit 70 includes photocouplers 71-1 and 71-2, resistors 72-1 and 72-2, resistors 73-1 and 73-2, and a microcontroller 74. The photocouplers 71-1 and 71-2 are elements that internally convert electrical signals to light and perform switching using light. The photocoupler 71-1 incorporates a light-emitting diode 81-1 and a phototransistor 82-1. The photocoupler 71-2 incorporates a light-emitting diode 81-2 and a phototransistor 82-2. The light-emitting diodes 81-1 and 81-2 are semiconductor elements that emit light when a voltage is applied. The phototransistors 82-1 and 82-2 are transistors that control current using light.

[0040] That is, the photocoupler 71-1 is a switching element that controls the current flowing through the phototransistor 82-1 in response to the light emitted by the light emitting diode 81-1, and the photocoupler 71-2 is a switching element that controls the current flowing through the phototransistor 82-2 in response to the light emitted by the light emitting diode 81-2.

[0041] The resistors 72-1, 72-2, 73-1 and 73-2 are each an electric resistance element and have a predetermined electric resistance value.

[0042] The microcontroller 74 is a microprocessor configured as a single integrated circuit including a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), an input / output interface, etc. The microcontroller 74 is a computer.

[0043] Here, a description will be given of the hardware configuration of the microcontroller 74. FIG.

[0044] In the microcontroller 74, a CPU 101, ROM 102, and RAM 103 are interconnected by a bus 104. The CPU 101 sequentially reads, interprets, and executes program code (machine language), performs data calculations, and controls the microcontroller 74. The ROM 102 is a read-only memory whose stored contents are retained even when the power is turned off. The RAM 103 is a readable and writable memory whose stored contents are lost when the power is turned off.

[0045] An input / output interface 105 is also connected to the bus 104. The input / output interface 105 is a hardware interface that transmits and receives signals to and from elements built into the microcontroller 74, the photocoupler 71, and connectors or comparators (not shown). The input / output interface 105 is connected to a storage unit 106 formed of a nonvolatile memory or the like, a communication unit 107 that communicates with a writer or the like via a connector, and a writer or an external computer or the like via a connector.

[0046] In the microcontroller 74 (computer) configured as described above, the CPU 101 loads a program stored in the storage unit 106, for example, into the RAM 103 via the input / output interface 105 and the bus 104, and executes the program, thereby performing a series of processes described below.

[0047] For example, a program executed by the microcontroller 74 (CPU 101) is written to the ROM 102 from a writer via the input / output interface 105 and a connector. Also, a program executed by the microcontroller 74 (CPU 101) is written to the ROM 102, RAM 103, or storage unit 106 from an external computer via the input / output interface 105 and a connector.

[0048] The program can be installed in the microcontroller 74, which is a computer, by receiving it via the communication unit 107 through a wired or wireless transmission medium and recording it in the storage unit 106. Alternatively, the program can be pre-installed in the microcontroller 74, which is a computer, by recording it in the ROM 102 or the storage unit 106 in advance.

[0049] That is, the microcontroller 74 (computer) executes the installed programs to realize the functions described below.

[0050] 3, one predetermined output terminal of the input / output interface 105 of the microcontroller 74 is connected to the anode of the light-emitting diode 81-1 of the photocoupler 71-1. The cathode of the light-emitting diode 81-1 of the photocoupler 71-1 is connected to one terminal of the resistor 73-1. The other terminal of the resistor 73-1 is grounded.

[0051] Another output terminal of the input / output interface 105 of the microcontroller 74 is connected to the anode of the light-emitting diode 81-2 of the photocoupler 71-2. The cathode of the light-emitting diode 81-2 of the photocoupler 71-2 is connected to one terminal of the resistor 73-2. The other terminal of the resistor 73-2 is grounded.

[0052] A voltage VH is applied to one terminal of the resistor 72-1. For example, the voltage VH is +48 V. The other terminal of the resistor 72-1 is connected to the collector of the phototransistor 82-1 of the photocoupler 71-1. The emitter of the phototransistor 82-1 of the photocoupler 71-1 is connected to a terminal for electrical conduction with the collector of the phototransistor 82-2 of the photocoupler 71-2 and the plate 53 of the piezoelectric drive element 31.

[0053] The emitter of the phototransistor 82-2 of the photocoupler 71-2 is connected to one terminal of a resistor 72-2. A voltage VL is applied to the other terminal of the resistor 72-2. For example, the voltage VL is −48 V.

[0054] A voltage VH is applied to a terminal for electrical connection to the electrode film on the outer surface of the piezoelectric element 51 of the piezoelectric driving element 31. A voltage VL is applied to a terminal for electrical connection to the electrode film on the outer surface of the piezoelectric element 52 of the piezoelectric driving element 31.

[0055] The piezoelectric driving element 31 is called a three-wire connection type because the outer surfaces of the plate 53, the piezoelectric element 51, and the piezoelectric element 52 are connected to each other.

[0056] Next, the function of the microcontroller 74 that executes the program will be described. Figure 5 is a block diagram that explains the configuration of the functions of the microcontroller 74 that are realized by executing the program.

[0057] The microcontroller 74 executes the program to realize a pattern data storage unit 121, a pattern data allocation unit 122, a timing control unit 123, and a drive control unit 124. The pattern data storage unit 121 stores pattern data that specifies the operation of the knitting needles so that the knitting needles perform an operation according to the pattern. For example, the pattern data storage unit 121 stores pattern data in the storage unit 106. The pattern data allocation unit 122 allocates data that specifies the operation of each of the piezoelectric drive elements 31 corresponding to each of the multiple fingers 21 provided in the needle selection device 11 from the pattern data.

[0058] The timing control unit 123 controls the timing of the operation of the drive control unit 124 in accordance with the operation of the knitting machine to which the needle selector 11 is attached. The drive control unit 124 drives each of the piezoelectric drive elements 31 corresponding to each of the multiple fingers 21 provided on the needle selector 11 in accordance with the pattern data assigned by the pattern data assignment unit 122, in accordance with the timing controlled by the timing control unit 123. That is, the drive control unit 124 changes the signal output from the output terminal of the input / output interface 105 of the microcontroller 74 to operate the photocouplers 71-1 and 71-2, and applies a predetermined voltage between predetermined terminals of the piezoelectric drive element 31 to drive the piezoelectric drive element 31.

[0059] The drive control unit 124 includes an insulation control unit 131 and a determination unit 132. The drive control unit 124 also includes one or more of a timer 133, a counter 134, or a current integration unit 135. The insulation control unit 131 insulates between predetermined terminals of the piezoelectric drive element 31 to which a predetermined voltage is applied. The determination unit 132 makes various determinations based on the conditions indicated by the timer 133, the counter 134, or the current integration unit 135.

[0060] The timer 133 measures the elapsed time since a predetermined voltage was applied between predetermined terminals of the piezoelectric drive element 31 or since the predetermined terminals were insulated. The counter 134 measures the number of determination processes performed by the determination unit 132. The current integrator 135 calculates the integrated value of the current flowing into the piezoelectric drive element 31 by integrating the current value calculated from the voltage value between the two terminals of the resistor 72-1 and the voltage value between the two terminals of the resistor 72-2. The integrated value of the current flowing into the piezoelectric drive element 31 indicates the amount of charge stored in the piezoelectric drive element 31.

[0061] Next, the operation of the drive circuit 70 will be described. FIG. 6 is a flowchart illustrating the process of driving the piezoelectric drive element 31 by the drive circuit 70. In step S101, the determination unit 132 of the drive control unit 124 determines whether the signal indicating the state of the piezoelectric drive element 31 is High, by referring to the pattern data assigned by the pattern data assignment unit 122 and the timing instruction from the timing control unit 123. A High signal indicating the state of the piezoelectric drive element 31 indicates that the end 61 of the finger 21 is displaced upward, as shown in the lower part of FIG. 2. That is, in this case, the transmission unit 41 of the piezoelectric drive element 31 is displaced downward.

[0062] Note that a signal indicating the state of the piezoelectric driving element 31 that is low indicates that the end 61 of the finger 21 is displaced downward, as shown in the upper part of Fig. 2. That is, in this case, the transmission part 41 of the piezoelectric driving element 31 is displaced upward.

[0063] If it is determined in step S101 that the signal indicating the state of the piezoelectric driving element 31 is high, the procedure proceeds to step S102, where the drive control unit 124 outputs a drive signal from the input / output interface 105 to the low-side photocoupler, i.e., photocoupler 71-2, to turn off the photocoupler 71-2. In step S103, the drive control unit 124 outputs a drive signal from the input / output interface 105 to the high-side photocoupler, i.e., photocoupler 71-1, to turn on the photocoupler 71-1. The procedures in steps S102 and S103 establish insulation between the collector and emitter of the phototransistor 82-2 of the photocoupler 71-2, and establish conduction between the collector and emitter of the phototransistor 82-1 of the photocoupler 71-1. This applies a voltage VH to the terminal of the plate 53 of the piezoelectric driving element 31. That is, a voltage VH is applied to the electrode film on the inner surface (the surface in contact with the plate 53) of the piezoelectric element 52. A voltage VL is applied to the terminal of the piezoelectric driving element 31 for electrical conduction to the electrode film on the outer surface of the piezoelectric element 52, and therefore the voltages VH and VL are applied to both surfaces of the piezoelectric element 52, respectively.

[0064] On the other hand, when a voltage VH is applied to the terminal of the plate 53 of the piezoelectric driving element 31, the voltage VH is applied to the electrode film on the inner surface of the piezoelectric element 51 (the surface that contacts the plate 53). Since the voltage VH is applied to the terminal of the piezoelectric driving element 31 that electrically connects to the electrode film on the outer surface of the piezoelectric element 51, the voltage VH is applied to both surfaces of the piezoelectric element 51. Since both surfaces of the piezoelectric element 51 have the same potential, the charge in the piezoelectric element 51 is discharged.

[0065] Therefore, electric charge is discharged from the piezoelectric element 51 and current flows into the piezoelectric element 52, so that electric charge accumulates in the piezoelectric element 52, and as shown in the lower part of Figure 2, the piezoelectric driving element 31 bends so that the transmission part 41 is displaced downward.

[0066] After the procedure of step S103, the timer 133 starts counting time.

[0067] FIG. 7 is a graph showing the state of the piezoelectric drive element 31. In FIG. 7, the horizontal axis represents the passage of time. In FIG. 7, the drive signal High represents the drive signal supplied from the input / output interface 105 to the photocoupler 71-1, and the drive signal Low represents the drive signal supplied from the input / output interface 105 to the photocoupler 71-2. In FIG. 7, the High-side piezoelectric element applied voltage represents the voltage applied to the inner surface of the piezoelectric element 52 of the piezoelectric drive element 31. In FIG. 7, the drive current represents the current flowing from the emitter of the phototransistor 82-1 of the photocoupler 71-1 and the collector of the phototransistor 82-2 of the photocoupler 71-2 to the plate 53 of the piezoelectric drive element 31.

[0068] 7, the High-side piezoelectric element charge indicates the charge stored in the piezoelectric element 52 of the piezoelectric driving element 31. In FIG. 7, the movement indicates the position of the end 61 of the finger 21 in the up-down direction.

[0069] 7, the procedure in step S102 causes the drive signal Low to go low, insulating the collector and emitter of the phototransistor 82-2 of the photocoupler 71-2, and the procedure in step S103 causes the drive signal High to go high, establishing conduction between the collector and emitter of the phototransistor 82-1 of the photocoupler 71-1. Then, at time t1, voltages VH and VL are applied to both surfaces of the piezoelectric element 52, as shown by the High-side piezoelectric element applied voltage in FIG.

[0070] From time t1, voltages VH and VL are applied to both surfaces of piezoelectric element 52, respectively, so that current begins to flow from the emitter of phototransistor 82-1 of photocoupler 71-1 to plate 53 of piezoelectric drive element 31, as shown by the drive current in Fig. 7, and charge is accumulated in piezoelectric element 52 of piezoelectric drive element 31, as shown by the High-side piezoelectric element charge in Fig. 7. When charge is accumulated in piezoelectric element 52 of piezoelectric drive element 31, bending of piezoelectric drive element 31 begins so that transmission section 41 is displaced downward, as shown in the operation in Fig. 7.

[0071] Returning to FIG. 6 , in step S104, the determination unit 132 of the drive control unit 124 references the time measured by the timer 133 to determine whether a predetermined time has elapsed since the high-side photocoupler, i.e., photocoupler 71-1, was turned on. For example, the determination unit 132 of the drive control unit 124 determines whether any time between 4 ms and 6 ms has elapsed since the photocoupler 71-1 was turned on. More preferably, for example, the determination unit 132 of the drive control unit 124 determines whether 5 ms has elapsed since the photocoupler 71-1 was turned on. If it is determined in step S104 that the predetermined time has elapsed since the photocoupler 71-1 was turned on, the procedure proceeds to step S105, where the insulation control unit 131 of the drive control unit 124 outputs a drive signal from the input / output interface 105 to the photocoupler 71-1 to turn off the high-side photocoupler, i.e., photocoupler 71-1. By the procedure of step S105, the collector and emitter of the phototransistor 82-1 of the photocoupler 71-1 are insulated from each other, and therefore the terminal of the plate 53 of the piezoelectric driving element 31 is insulated.

[0072] When the terminals of the plate 53 of the piezoelectric driving element 31 are insulated, the charge remains stored in the piezoelectric element 52, and the bending of the piezoelectric driving element 31 is maintained.

[0073] After the procedure of step S105, the timer 133 starts counting time. After the procedure of step S105, the procedure proceeds to step S106.

[0074] At time t2 in FIG. 7, the drive signal High becomes low level through the procedure of step S105, and the collector and emitter of the phototransistor 82-1 of the photocoupler 71-1 are insulated from each other, and the plate 53 of the piezoelectric drive element 31 is insulated as shown by the high-side piezoelectric element applied voltage represented by the dotted line in FIG. 7.

[0075] At time t2, the plate 53 of the piezoelectric drive element 31 is insulated, so that the current flowing from the emitter of the phototransistor 82-1 of the photocoupler 71-1 to the plate 53 of the piezoelectric drive element 31 is interrupted, as shown by the drive current in Fig. 7, and the charge accumulated in the piezoelectric element 52 of the piezoelectric drive element 31 is maintained, as shown by the high-side piezoelectric element charge in Fig. 7. When charge accumulates in the piezoelectric element 52 of the piezoelectric drive element 31, the piezoelectric drive element 31 continues to bend even after time t2, as shown in the operation in Fig. 7, and the transmission part 41 of the piezoelectric drive element 31 is displaced to a predetermined vertical position.

[0076] Returning to FIG. 6, if it is determined in step S104 that the predetermined time has not elapsed since the photocoupler 71-1 was turned on, the procedure of step S105 is skipped and the procedure proceeds to step S106.

[0077] In step S106, the determination unit 132 of the drive control unit 124 references the time measured by the timer 133 to determine whether a predetermined time has elapsed since the high-side photocoupler, i.e., photocoupler 71-1, was turned off. For example, the determination unit 132 of the drive control unit 124 determines whether any time between 0.1 seconds and 10 seconds has elapsed since the photocoupler 71-1 was turned off. More preferably, the determination unit 132 of the drive control unit 124 determines whether 5 seconds have elapsed since the photocoupler 71-1 was turned off. If it is determined in step S106 that the predetermined time has elapsed since the photocoupler 71-1 was turned off, the procedure proceeds to step S107, where the insulation control unit 131 of the drive control unit 124 outputs a drive signal from the input / output interface 105 to the photocoupler 71-1 to turn on the high-side photocoupler, i.e., photocoupler 71-1. As a result, the voltage VH is applied to the terminal of the plate 53 of the piezoelectric driving element 31 , and the voltages VH and VL are applied to both surfaces of the piezoelectric element 52 , respectively.

[0078] After a predetermined time has elapsed since the terminals of the plate 53 of the piezoelectric driving element 31 were insulated, the voltages VH and VL are again applied to both surfaces of the piezoelectric element 52, respectively, in order to prevent the charge accumulated in the piezoelectric element 52 from decreasing due to natural discharge and causing the bending posture of the piezoelectric driving element 31 to change.

[0079] After the procedure of step S107, the timer 133 starts counting time. After the procedure of step S107, the procedure proceeds to step S108.

[0080] If it is determined in step S106 that the predetermined time has not elapsed since the photocoupler 71-1 was turned off, the procedure of step S107 is skipped and the procedure proceeds to step S108.

[0081] In step S108, the determination unit 132 of the drive control unit 124 determines whether the signal indicating the state of the piezoelectric drive element 31 is High by referring to the pattern data assigned by the pattern data assignment unit 122 and the timing instruction from the timing control unit 123. If it is determined in step S108 that the signal indicating the state of the piezoelectric drive element 31 is High, the procedure returns to step S104, and the above-mentioned procedure is repeated.

[0082] If it is determined in step S108 that the signal indicating the state of the piezoelectric driving element 31 is not High, the procedure returns to step S101.

[0083] If it is determined in step S101 that the signal indicating the state of the piezoelectric drive element 31 is not high, i.e., the signal indicating the state of the piezoelectric drive element 31 is low, the procedure proceeds to step S109, where the drive control unit 124 outputs a drive signal from the input / output interface 105 to the photocoupler 71-1, turning off the high-side photocoupler, i.e., photocoupler 71-1. In step S110, the drive control unit 124 outputs a drive signal from the input / output interface 105 to the photocoupler 71-2, turning on the low-side photocoupler, i.e., photocoupler 71-2. The procedures of steps S109 and S110 establish insulation between the collector and emitter of the phototransistor 82-1 of the photocoupler 71-1, and establish conduction between the collector and emitter of the phototransistor 82-2 of the photocoupler 71-2. As a result, a voltage VL is applied to the terminal of the plate 53 of the piezoelectric drive element 31. That is, a voltage VL is applied to the electrode film on the inner surface (the surface in contact with the plate 53) of the piezoelectric element 51. A voltage VH is applied to a terminal of the piezoelectric driving element 31 for electrical conduction to the electrode film on the outer surface of the piezoelectric element 51, and therefore the voltages VH and VL are applied to both surfaces of the piezoelectric element 51, respectively.

[0084] On the other hand, when a voltage VL is applied to the terminal of the plate 53 of the piezoelectric driving element 31, the voltage VL is applied to the electrode film on the inner surface (the surface in contact with the plate 53) of the piezoelectric element 52. Since the voltage VL is applied to the terminal of the piezoelectric driving element 31 that electrically connects to the electrode film on the outer surface of the piezoelectric element 52, the voltage VL is applied to both surfaces of the piezoelectric element 52. Since both surfaces of the piezoelectric element 52 have the same potential, the electric charge in the piezoelectric element 52 is discharged.

[0085] Therefore, electric charge is discharged from the piezoelectric element 52 and current flows into the piezoelectric element 51, so that electric charge accumulates in the piezoelectric element 51, and as shown in the upper part of Figure 2, the piezoelectric driving element 31 bends so that the transmission part 41 is displaced upward.

[0086] After the procedure of step S110, the timer 133 starts counting time.

[0087] 7, the procedure in step S109 causes the drive signal High to go low, insulating the collector and emitter of the phototransistor 82-1 in the photocoupler 71-1, and the procedure in step S110 causes the drive signal Low to go high, establishing conduction between the collector and emitter of the phototransistor 82-2 in the photocoupler 71-2. Then, at time t3, although not shown in the figure, voltages VH and VL are applied to both surfaces of the piezoelectric element 51, respectively.

[0088] From time t3, voltages VH and VL are applied to both surfaces of the piezoelectric element 51, respectively, and as shown by the drive current in FIG. 7, current begins to flow from the emitter of phototransistor 82-2 of photocoupler 71-2 to plate 53 of piezoelectric drive element 31, causing charge to accumulate in piezoelectric element 51 of piezoelectric drive element 31. Meanwhile, charge is discharged from piezoelectric element 51. When charge accumulates in piezoelectric element 51 of piezoelectric drive element 31, bending of piezoelectric drive element 31 begins so that transmission section 41 is displaced upward.

[0089] Returning to FIG. 6 , in step S111, the determination unit 132 of the drive control unit 124 references the time measured by the timer 133 to determine whether a predetermined time has elapsed since the low-side photocoupler, i.e., photocoupler 71-2, was turned on. For example, the determination unit 132 of the drive control unit 124 determines whether any time between 4 ms and 6 ms has elapsed since the photocoupler 71-2 was turned on. More preferably, for example, the determination unit 132 of the drive control unit 124 determines whether 5 ms has elapsed since the photocoupler 71-2 was turned on. If it is determined in step S111 that the predetermined time has elapsed since the photocoupler 71-2 was turned on, the procedure proceeds to step S112, where the insulation control unit 131 of the drive control unit 124 outputs a drive signal from the input / output interface 105 to the photocoupler 71-2 to turn off the low-side photocoupler, i.e., photocoupler 71-2. By the procedure of step S112, the collector and emitter of the phototransistor 82-2 of the photocoupler 71-2 are insulated from each other, and therefore the terminal of the plate 53 of the piezoelectric driving element 31 is insulated.

[0090] When the terminals of the plate 53 of the piezoelectric driving element 31 are insulated, the charge remains stored in the piezoelectric element 51, and the bending of the piezoelectric driving element 31 is maintained.

[0091] After the procedure of step S112, the timer 133 starts counting time. After the procedure of step S112, the procedure proceeds to step S113.

[0092] At time t4 in FIG. 7, the drive signal Low goes to a Low level in the procedure of step S112, and the collector and emitter of the phototransistor 82-2 of the photocoupler 71-2 are insulated, and the plate 53 of the piezoelectric drive element 31 is insulated.

[0093] At time t4, the plate 53 of the piezoelectric drive element 31 is insulated, and so the current flowing from the emitter of the phototransistor 82-2 of the photocoupler 71-2 to the plate 53 of the piezoelectric drive element 31 is cut off, as shown by the drive current in Fig. 7, and the charge accumulated in the piezoelectric element 51 of the piezoelectric drive element 31 is maintained. When charge accumulates in the piezoelectric element 51 of the piezoelectric drive element 31, the piezoelectric drive element 31 continues to bend even after time t4, as shown in the operation in Fig. 7, and the transmission part 41 of the piezoelectric drive element 31 is displaced to a predetermined position in the vertical direction.

[0094] Returning to FIG. 6, if it is determined in step S111 that the predetermined time has not elapsed since the photocoupler 71-2 was turned on, the procedure of step S112 is skipped and the procedure proceeds to step S113.

[0095] In step S113, the determination unit 132 of the drive control unit 124 refers to the time measured by the timer 133 and determines whether a predetermined time has elapsed since the low-side photocoupler, i.e., photocoupler 71-2, was turned OFF. For example, the determination unit 132 of the drive control unit 124 determines whether any time between 0.1 seconds and 10 seconds has elapsed since the photocoupler 71-2 was turned OFF. More preferably, for example, the determination unit 132 of the drive control unit 124 determines whether 5 seconds have elapsed since the photocoupler 71-2 was turned OFF. If it is determined in step S113 that the predetermined time has elapsed since the photocoupler 71-2 was turned OFF, the procedure proceeds to step S114, where the insulation control unit 131 of the drive control unit 124 outputs a drive signal from the input / output interface 105 to the photocoupler 71-2 to turn ON the low-side photocoupler, i.e., photocoupler 71-2. As a result, the voltage VL is applied to the terminal of the plate 53 of the piezoelectric driving element 31 , and the voltages VH and VL are applied to both surfaces of the piezoelectric element 51 , respectively.

[0096] After a predetermined time has elapsed since the terminals of the plate 53 of the piezoelectric driving element 31 were insulated, the voltages VH and VL are again applied to both surfaces of the piezoelectric element 51, respectively, in order to prevent the charge accumulated in the piezoelectric element 51 from decreasing due to natural discharge and causing the bending posture of the piezoelectric driving element 31 to change.

[0097] After the procedure of step S114, the timer 133 starts counting time. After the procedure of step S114, the procedure proceeds to step S115.

[0098] If it is determined in step S113 that the predetermined time has not elapsed since the photocoupler 71-2 was turned off, the procedure of step S114 is skipped and the procedure proceeds to step S115.

[0099] In step S115, the determination unit 132 of the drive control unit 124 determines whether the signal indicating the state of the piezoelectric drive element 31 is Low by referring to the pattern data assigned by the pattern data assignment unit 122 and the timing instruction from the timing control unit 123. If it is determined in step S115 that the signal indicating the state of the piezoelectric drive element 31 is Low, the procedure returns to step S111, and the above-mentioned procedure is repeated.

[0100] If it is determined in step S115 that the signal indicating the state of the piezoelectric driving element 31 is not low, the procedure returns to step S101, and the above-described processing is repeated.

[0101] In this way, at the beginning of the period in which the piezoelectric drive element 31 is bent in a predetermined direction, a predetermined voltage is applied between predetermined terminals of the piezoelectric drive element 31, and when a predetermined time has elapsed since the application of voltage between the terminals began during the period in which the piezoelectric drive element 31 is bent in a predetermined direction, one of the terminals is insulated.

[0102] Also, a switch can be provided to isolate the terminals of the piezoelectric driving element 31 .

[0103] Next, another example of the drive circuit that drives the piezoelectric drive element 31 will be described. Fig. 8 is a diagram showing another example of the configuration of the drive circuit. The drive circuit 150 applies a voltage to the piezoelectric drive element 31 and supplies a current to charge the piezoelectric element 51 or the piezoelectric element 52, thereby bending the piezoelectric drive element 31.

[0104] The drive circuit 150 includes photocouplers 151-1 and 151-2, resistors 152-1 and 152-2, resistors 153-1 and 153-2, a switch 154, and a microcontroller 155. The photocouplers 151-1 and 151-2 are elements that internally convert electrical signals to light and perform switching using light. The photocoupler 151-1 incorporates a light-emitting diode 161-1 and a phototransistor 162-1. The photocoupler 151-2 incorporates a light-emitting diode 161-2 and a phototransistor 162-2. The light-emitting diodes 161-1 and 161-2 are semiconductor elements that emit light when a voltage is applied. The phototransistors 162-1 and 162-2 are transistors that control current using light.

[0105] That is, the photocoupler 151-1 is a switching element that controls the current flowing through the phototransistor 162-1 in response to the light emitted by the light emitting diode 161-1, and the photocoupler 151-2 is a switching element that controls the current flowing through the phototransistor 162-2 in response to the light emitted by the light emitting diode 161-2.

[0106] The resistors 152-1, 152-2, 153-1 and 153-2 are each an electric resistance element and have a predetermined electric resistance value.

[0107] The switch 154 is a so-called switch, and is a device or element that opens and closes a predetermined electrical path in the drive circuit 150. For example, the switch 154 can be a contact relay (mechanical relay) or a contactless relay (a semiconductor relay (solid state relay) such as a MOS FET (metal-oxide-semiconductor field-effect transistor) relay). The switch 154 can also be a relay.

[0108] The microcontroller 155 is a microprocessor configured with a CPU, ROM, RAM, input / output interface, etc., as a single integrated circuit. The microcontroller 155 is a computer. The hardware configuration of the microcontroller 155 is similar to that of the microcontroller 74, and therefore a description thereof will be omitted. The functional configuration of the microcontroller 155 realized by executing a program is similar to that of the microcontroller 74, and therefore a description thereof will be omitted.

[0109] That is, the microcontroller 155 (computer) realizes the same functions as the microcontroller 74 by executing the installed program.

[0110] A predetermined voltage VCC is applied to one terminal of resistor 153-1. The other terminal of resistor 153-1 is connected to the anode of light-emitting diode 161-1 of photocoupler 151-1. One predetermined output terminal of input / output interface 105 of microcontroller 155 is connected to the cathode of light-emitting diode 161-1 of photocoupler 151-1 and the anode of light-emitting diode 161-2 of photocoupler 151-2.

[0111] One terminal of the resistor 153-2 is connected to the cathode of the light-emitting diode 161-2 of the photocoupler 151-2, and the other terminal of the resistor 153-2 is grounded.

[0112] A voltage VH is applied to one terminal of resistor 152-1. For example, voltage VH is +48 V. The other terminal of resistor 152-1 is connected to the collector of phototransistor 162-1 of photocoupler 151-1. The emitter of phototransistor 162-1 of photocoupler 151-1 is connected to the collector of phototransistor 162-2 of photocoupler 151-2 and to one output terminal of switch 154. The other output terminal of switch 154 is connected to a terminal for electrical conduction to plate 53 of piezoelectric drive element 31.

[0113] The other output terminal of the input / output interface 105 of the microcontroller 155 is connected to the input terminal of the switch 154. The output terminal of the switch 154 is opened or closed by a signal to the input terminal.

[0114] The emitter of the phototransistor 162-2 of the photocoupler 151-2 is connected to one terminal of a resistor 152-2. A voltage VL is applied to the other terminal of the resistor 152-2. For example, the voltage VL is −48 V.

[0115] A voltage VH is applied to a terminal for electrical connection to the electrode film on the outer surface of the piezoelectric element 51 of the piezoelectric driving element 31. A voltage VL is applied to a terminal for electrical connection to the electrode film on the outer surface of the piezoelectric element 52 of the piezoelectric driving element 31.

[0116] The piezoelectric driving element 31 shown in FIG. 8 is called a three-wire connection type because the outer surfaces of the plate 53, the piezoelectric element 51, and the piezoelectric element 52 are connected to each other.

[0117] Next, the operation of the drive circuit 150 will be described. Fig. 9 is a flowchart illustrating the process of driving the piezoelectric drive element 31 by the drive circuit 150. In the description referring to the flowchart of Fig. 9, the pattern data storage unit 121, pattern data allocation unit 122, timing control unit 123, drive control unit 124, insulation control unit 131, determination unit 132, timer 133, counter 134, and current integration unit 135 are functions realized by the microcontroller 155 executing a program.

[0118] In step S131, the determination unit 132 of the drive control unit 124 refers to the pattern data assigned by the pattern data assignment unit 122 and the timing instructions from the timing control unit 123 and determines whether the signal indicating the state of the piezoelectric drive element 31 is High.

[0119] If it is determined in step S131 that the signal indicating the state of the piezoelectric drive element 31 is High, the procedure proceeds to step S132, where the drive control unit 124 outputs a drive signal from the input / output interface 105 to the switch 154 to close the switch 154. In other words, the output terminal of the switch 154 is connected.

[0120] In step S133, the drive control unit 124 sets the drive signal output from the input / output interface 105 to photocouplers 151-1 and 151-2 to a low level, turning off the low-side photocoupler, i.e., photocoupler 151-2, and turning on the high-side photocoupler, i.e., photocoupler 151-1. The procedure of step S133 provides insulation between the collector and emitter of phototransistor 162-2 of photocoupler 151-2, and provides conduction between the collector and emitter of phototransistor 162-1 of photocoupler 151-1. This applies voltage VH to the terminal of plate 53 of piezoelectric drive element 31. That is, voltage VH is applied to the electrode film on the inner surface of piezoelectric element 52 (the surface in contact with plate 53). A voltage VL is applied to the terminals for electrically connecting the electrode film on the outer surface of the piezoelectric element 52 of the piezoelectric driving element 31, so that the voltages VH and VL are applied to both surfaces of the piezoelectric element 52, respectively.

[0121] On the other hand, when voltage VH is applied to the terminal of plate 53 of piezoelectric driving element 31, voltage VH is applied to the electrode film on the inner surface (the surface in contact with plate 53) of piezoelectric element 51. Since voltage VH is applied to the terminal of piezoelectric driving element 31 for electrical conduction to the electrode film on the outer surface of piezoelectric element 51, voltage VH is applied to both surfaces of piezoelectric element 51. Since both surfaces of piezoelectric element 51 have the same potential, the electric charge of piezoelectric element 51 is discharged.

[0122] Therefore, electric charge is discharged from the piezoelectric element 51 and current flows into the piezoelectric element 52, so that electric charge accumulates in the piezoelectric element 52, and as shown in the lower part of Figure 2, the piezoelectric driving element 31 bends so that the transmission part 41 is displaced downward.

[0123] After the procedure of step S133, the timer 133 starts counting time.

[0124] In step S134, the determination unit 132 of the drive control unit 124 references the time measured by the timer 133 to determine whether a predetermined time has elapsed since the high-side photocoupler, i.e., photocoupler 151-1, was turned on. For example, the determination unit 132 of the drive control unit 124 determines whether a time between 4 ms and 6 ms has elapsed since the photocoupler 151-1 was turned on. More preferably, the determination unit 132 of the drive control unit 124 determines whether 5 ms has elapsed since the photocoupler 151-1 was turned on. If it is determined in step S134 that the predetermined time has elapsed since the photocoupler 151-1 was turned on, the procedure proceeds to step S135, where the insulation control unit 131 of the drive control unit 124 outputs a drive signal from the input / output interface 105 to the switch 154 to open the switch 154. In other words, the terminal of the plate 53 of the piezoelectric drive element 31 is insulated.

[0125] When the terminals of the plate 53 of the piezoelectric driving element 31 are insulated, the charge remains stored in the piezoelectric element 52, and the bending of the piezoelectric driving element 31 is maintained.

[0126] After the procedure of step S135, the timer 133 starts counting time. After the procedure of step S135, the procedure proceeds to step S136.

[0127] If it is determined in step S134 that the predetermined time has not elapsed since the photocoupler 151-1 was turned on, the procedure of step S135 is skipped and the procedure proceeds to step S136.

[0128] In step S136, the determination unit 132 of the drive control unit 124 determines whether a predetermined time has elapsed since the switch 154 was opened, by referring to the time measured by the timer 133. For example, the determination unit 132 of the drive control unit 124 determines whether a time between 0.1 seconds and 10 seconds has elapsed since the switch 154 was opened. More preferably, the determination unit 132 of the drive control unit 124 determines whether 5 seconds have elapsed since the switch 154 was opened. If it is determined in step S136 that the predetermined time has elapsed since the switch 154 was opened, the procedure proceeds to step S137, where the insulation control unit 131 of the drive control unit 124 outputs a drive signal from the input / output interface 105 to the switch 154, thereby closing the switch 154. That is, the output terminal of the switch 154 is connected. As a result, the voltage VH is applied to the terminal of the plate 53 of the piezoelectric drive element 31, and the voltages VH and VL are applied to both surfaces of the piezoelectric element 52, respectively.

[0129] After a predetermined time has elapsed since the terminals of the plate 53 of the piezoelectric driving element 31 were insulated, the voltages VH and VL are again applied to both surfaces of the piezoelectric element 52, respectively, in order to prevent the charge accumulated in the piezoelectric element 52 from decreasing due to natural discharge and causing the bending posture of the piezoelectric driving element 31 to change.

[0130] After the procedure of step S137, the timer 133 starts counting time. After the procedure of step S137, the procedure proceeds to step S138.

[0131] If it is determined in step S136 that the predetermined time has not elapsed since the switch 154 was opened, the procedure of step S137 is skipped and the procedure proceeds to step S138.

[0132] In step S138, the determination section 132 of the drive control section 124 determines whether the signal indicating the state of the piezoelectric drive element 31 is High by referring to the pattern data assigned by the pattern data assignment section 122 and the timing instruction from the timing control section 123. If it is determined in step S138 that the signal indicating the state of the piezoelectric drive element 31 is High, the procedure returns to step S134, and the above-described procedure is repeated.

[0133] If it is determined in step S138 that the signal indicating the state of the piezoelectric driving element 31 is not High, the procedure returns to step S131.

[0134] If it is determined in step S131 that the signal indicating the state of the piezoelectric drive element 31 is not High, that is, the signal indicating the state of the piezoelectric drive element 31 is Low, the procedure proceeds to step S139, and the drive control unit 124 outputs a drive signal from the input / output interface 105 to the switch 154 to close the switch 154. In other words, the output terminal of the switch 154 is connected.

[0135] In step S140, the drive control unit 124 sets the drive signal output from the input / output interface 105 to photocouplers 151-1 and 151-2 to a high level, turning off the high-side photocoupler, i.e., photocoupler 151-1, and turning on the low-side photocoupler, i.e., photocoupler 151-2. The procedure in step S140 provides insulation between the collector and emitter of phototransistor 162-1 in photocoupler 151-1, and conduction between the collector and emitter of phototransistor 162-2 in photocoupler 151-2. This applies voltage VL to the terminal of plate 53 of piezoelectric drive element 31. That is, voltage VL is applied to the electrode film on the inner surface of piezoelectric element 51 (the surface in contact with plate 53). A voltage VH is applied to the terminals for electrically connecting the electrode film on the outer surface of the piezoelectric element 51 of the piezoelectric driving element 31, so that the voltages VH and VL are applied to both surfaces of the piezoelectric element 51, respectively.

[0136] On the other hand, when a voltage VL is applied to the terminal of the plate 53 of the piezoelectric driving element 31, the voltage VL is applied to the electrode film on the inner surface (the surface in contact with the plate 53) of the piezoelectric element 52. Since the voltage VL is applied to the terminal of the piezoelectric driving element 31 for electrical conduction to the electrode film on the outer surface of the piezoelectric element 52, the voltage VL is applied to both surfaces of the piezoelectric element 52. Since both surfaces of the piezoelectric element 52 have the same potential, the electric charge of the piezoelectric element 52 is discharged.

[0137] Therefore, electric charge is discharged from the piezoelectric element 52 and current flows into the piezoelectric element 51, so that electric charge accumulates in the piezoelectric element 51, and as shown in the upper part of Figure 2, the piezoelectric driving element 31 bends so that the transmission part 41 is displaced upward.

[0138] After the procedure of step S140, the timer 133 starts counting time.

[0139] In step S141, the determination unit 132 of the drive control unit 124 references the time measured by the timer 133 to determine whether a predetermined time has elapsed since the low-side photocoupler, i.e., photocoupler 151-2, was turned on. For example, the determination unit 132 of the drive control unit 124 determines whether a time between 4 ms and 6 ms has elapsed since the photocoupler 151-2 was turned on. More preferably, the determination unit 132 of the drive control unit 124 determines whether 5 ms has elapsed since the photocoupler 151-2 was turned on. If it is determined in step S141 that a predetermined time has elapsed since the photocoupler 151-2 was turned on, the procedure proceeds to step S142, where the insulation control unit 131 of the drive control unit 124 outputs a drive signal from the input / output interface 105 to the switch 154 to open the switch 154. In other words, the terminal of the plate 53 of the piezoelectric drive element 31 is insulated.

[0140] When the terminals of the plate 53 of the piezoelectric driving element 31 are insulated, the charge remains stored in the piezoelectric element 51, and the bending of the piezoelectric driving element 31 is maintained.

[0141] After the procedure of step S142, the timer 133 starts counting time. After the procedure of step S142, the procedure proceeds to step S143.

[0142] If it is determined in step S141 that the predetermined time has not elapsed since the photocoupler 71-2 was turned on, the procedure of step S142 is skipped and the procedure proceeds to step S143.

[0143] In step S143, the determination unit 132 of the drive control unit 124 determines whether a predetermined time has elapsed since the switch 154 was opened, by referring to the time measured by the timer 133. For example, the determination unit 132 of the drive control unit 124 determines whether a time between 0.1 seconds and 10 seconds has elapsed since the switch 154 was opened. More preferably, the determination unit 132 of the drive control unit 124 determines whether 5 seconds have elapsed since the switch 154 was opened. If it is determined in step S143 that the predetermined time has elapsed since the switch 154 was opened, the procedure proceeds to step S144, where the insulation control unit 131 of the drive control unit 124 outputs a drive signal from the input / output interface 105 to the switch 154, thereby closing the switch 154. That is, the output terminal of the switch 154 is connected. As a result, the voltage VL is applied to the terminal of the plate 53 of the piezoelectric drive element 31, and the voltages VH and VL are applied to both surfaces of the piezoelectric element 51, respectively.

[0144] After a predetermined time has elapsed since the terminals of the plate 53 of the piezoelectric driving element 31 were insulated, the voltages VH and VL are again applied to both surfaces of the piezoelectric element 51, respectively, in order to prevent the charge accumulated in the piezoelectric element 51 from decreasing due to natural discharge and causing the bending posture of the piezoelectric driving element 31 to change.

[0145] After the procedure of step S144, the timer 133 starts counting time. After the procedure of step S144, the procedure proceeds to step S145.

[0146] If it is determined in step S143 that the predetermined time has not elapsed since the switch 154 was opened, the procedure of step S144 is skipped and the procedure proceeds to step S145.

[0147] In step S145, the determination unit 132 of the drive control unit 124 determines whether the signal indicating the state of the piezoelectric drive element 31 is Low by referring to the pattern data assigned by the pattern data assignment unit 122 and the timing instruction from the timing control unit 123. If it is determined in step S145 that the signal indicating the state of the piezoelectric drive element 31 is Low, the procedure returns to step S141, and the above-mentioned procedure is repeated.

[0148] If it is determined in step S145 that the signal indicating the state of the piezoelectric driving element 31 is not low, the procedure returns to step S131, and the above-described processing is repeated.

[0149] In this way, at the beginning of the period in which the piezoelectric drive element 31 is bent in a predetermined direction, a predetermined voltage is applied between predetermined terminals of the piezoelectric drive element 31, and when a predetermined time has elapsed since the application of voltage between the terminals began during the period in which the piezoelectric drive element 31 is bent in a predetermined direction, one of the terminals is insulated.

[0150] The switch can also be provided to insulate the wiring that applies the voltage VH or VL to the piezoelectric driving element 31.

[0151] Next, we will explain yet another example of the drive circuit that drives the piezoelectric drive element 31. Fig. 10 is a diagram showing yet another example of the configuration of the drive circuit. The drive circuit 180 applies a voltage to the piezoelectric drive element 31 and supplies a current to charge the piezoelectric element 51 or the piezoelectric element 52, causing the piezoelectric drive element 31 to bend.

[0152] The drive circuit 180 includes photocouplers 181-1 and 181-2, resistors 182-1 and 182-2, resistors 183-1 and 183-2, switches 184-1 and 184-2, and a microcontroller 185. The photocouplers 181-1 and 181-2 are elements that internally convert electrical signals to light and perform switching using light. The photocoupler 181-1 incorporates a light-emitting diode 191-1 and a phototransistor 192-1. The photocoupler 181-2 incorporates a light-emitting diode 191-2 and a phototransistor 192-2. The light-emitting diodes 191-1 and 191-2 are semiconductor elements that emit light when a voltage is applied. The phototransistors 192-1 and 192-2 are transistors that control current using light.

[0153] That is, the photocoupler 181-1 is a switching element that controls the current flowing through the phototransistor 192-1 in response to the light emitted by the light emitting diode 191-1, and the photocoupler 181-2 is a switching element that controls the current flowing through the phototransistor 192-2 in response to the light emitted by the light emitting diode 191-2.

[0154] The resistors 182-1, 182-2, 183-1 and 183-2 are each an electric resistance element and have a predetermined electric resistance value.

[0155] The switches 184-1 and 184-2 are so-called switches, and are devices or elements that open and close a predetermined electrical path in the drive circuit 180. For example, the switches 184-1 and 184-2 can be contact relays (mechanical relays) or contactless relays (semiconductor relays such as MOS FET relays). The switch 184 can also be a relay.

[0156] The microcontroller 185 is a microprocessor configured with a CPU, ROM, RAM, input / output interface, etc., as a single integrated circuit. The microcontroller 185 is a computer. The hardware configuration of the microcontroller 185 is similar to that of the microcontroller 74, and therefore a description thereof will be omitted. The functional configuration of the microcontroller 185 realized by executing a program is similar to that of the microcontroller 74, and therefore a description thereof will be omitted.

[0157] That is, the microcontroller 185 (computer) realizes the same functions as the microcontroller 74 by executing the installed program.

[0158] The photocouplers 181-1, 181-2, resistors 182-1, 182-2, resistors 183-1, 183-2, and the microcontroller 185 are connected to terminals for electrical conduction between the emitter of the phototransistor 192-1 of the photocoupler 181-1 and the collector of the phototransistor 192-2 of the photocoupler 181-2 and the plate 53 of the piezoelectric driving element 31, and the output terminals of the input / output interface 105 of the microcontroller 185 are connected to terminals for electrical conduction between the emitter of the phototransistor 192-1 of the photocoupler 181-1 and the collector of the phototransistor 192-2 of the photocoupler 181-2 and the plate 53 of the piezoelectric driving element 31. 8. Except for the fact that the photocouplers 181-1, 181-2, resistors 152-1, 152-2, 153-1, 153-2, and microcontroller 155 are connected to each other in the same manner as the photocouplers 151-1, 151-2, resistors 152-1, 152-2, 153-1, 153-2, and microcontroller 155 in FIG. 8, a description of the mutual connections of the photocouplers 181-1, 181-2, resistors 182-1, 182-2, resistors 183-1, 183-2, and microcontroller 185 will be omitted.

[0159] In the drive circuit 180 , the emitter of the phototransistor 192 - 1 of the photocoupler 181 - 1 and the collector of the phototransistor 192 - 2 of the photocoupler 181 - 2 are connected to terminals for electrical conduction to the plate 53 of the piezoelectric drive element 31 .

[0160] A voltage VH is applied to one output terminal of the switch 184-1. For example, the voltage VH is +48 V. The other output terminal of the switch 184-1 is connected to a terminal for electrical conduction to the electrode film on the outer surface of the piezoelectric element 51 of the piezoelectric drive element 31.

[0161] One output terminal of the input / output interface 105 of the microcontroller 185 is connected to the input terminal of the switch 184-1. The output terminal of the switch 184-1 is opened or closed by a signal to the input terminal.

[0162] A voltage VL is applied to one output terminal of the switch 184-2. For example, the voltage VL is −48 V. The other output terminal of the switch 184-2 is connected to a terminal for electrical conduction to the electrode film on the outer surface of the piezoelectric element 52 of the piezoelectric drive element 31.

[0163] The other output terminal of the input / output interface 105 of the microcontroller 185 is connected to the input terminal of the switch 184-2. The output terminal of the switch 184-2 is opened or closed in response to a signal to the input terminal. The output terminals of the switches 184-1 and 184-2 are individually opened or closed in response to a signal from the input / output interface 105 of the microcontroller 185.

[0164] The piezoelectric driving element 31 shown in FIG. 10 is called a three-wire connection type because the outer surfaces of the plate 53, the piezoelectric element 51, and the piezoelectric element 52 are connected to each other.

[0165] Next, the operation of the drive circuit 180 will be described. Fig. 11 is a flowchart illustrating the process of driving the piezoelectric drive element 31 by the drive circuit 180. In the description referring to the flowchart of Fig. 11, the pattern data storage unit 121, pattern data allocation unit 122, timing control unit 123, drive control unit 124, insulation control unit 131, determination unit 132, timer 133, counter 134, and current integration unit 135 are functions realized by the microcontroller 185 executing a program.

[0166] In step S171, the determination unit 132 of the drive control unit 124 refers to the pattern data assigned by the pattern data assignment unit 122 and the timing instructions from the timing control unit 123 and determines whether the signal indicating the state of the piezoelectric drive element 31 is High.

[0167] If it is determined in step S171 that the signal indicating the state of the piezoelectric drive element 31 is High, the procedure proceeds to step S172, where the drive control unit 124 outputs a drive signal from the input / output interface 105 to switch 184-1, which is the Low-side switch, and switch 184-2, which is the High-side switch, to close switches 184-1 and 184-2. In other words, the output terminals of switches 184-1 and 184-2 are connected.

[0168] In step S173, the drive control unit 124 sets the drive signal output from the input / output interface 105 to the photocouplers 181-1 and 181-2 to a low level, turning off the low-side photocoupler, i.e., photocoupler 181-2, and turning on the high-side photocoupler, i.e., photocoupler 181-1. According to the procedure of step S173, similar to step S133 in Fig. 9, voltages VH and VL are applied to both surfaces of the piezoelectric element 52, respectively, and the electric charge of the piezoelectric element 51 is discharged.

[0169] Therefore, electric charge is discharged from the piezoelectric element 51 and current flows into the piezoelectric element 52, so that electric charge accumulates in the piezoelectric element 52, and as shown in the lower part of Figure 2, the piezoelectric driving element 31 bends so that the transmission part 41 is displaced downward.

[0170] After the procedure of step S173, the timer 133 starts counting time.

[0171] In step S174, the determination unit 132 of the drive control unit 124 references the time measured by the timer 133 to determine whether a predetermined time has elapsed since the high-side photocoupler, i.e., photocoupler 181-1, was turned on. For example, the determination unit 132 of the drive control unit 124 determines whether any time between 4 ms and 6 ms has elapsed since the photocoupler 181-1 was turned on. More preferably, for example, the determination unit 132 of the drive control unit 124 determines whether 5 ms has elapsed since the photocoupler 181-1 was turned on. If it is determined in step S174 that the predetermined time has elapsed since the photocoupler 181-1 was turned on, the procedure proceeds to step S175, where the insulation control unit 131 of the drive control unit 124 outputs a drive signal from the input / output interface 105 to the switch 184-2, which is the high-side switch, to open the switch 184-2. That is, the terminals for electrical connection to the electrode films on the outer surfaces of the piezoelectric elements 52 of the piezoelectric driving elements 31 are insulated.

[0172] When the terminals for electrically connecting to the electrode film on the outer surface of the piezoelectric element 52 of the piezoelectric driving element 31 are insulated, the electric charge remains accumulated in the piezoelectric element 52, and the bending of the piezoelectric driving element 31 is maintained.

[0173] After the procedure of step S175, the timer 133 starts counting time. After the procedure of step S175, the procedure proceeds to step S176.

[0174] If it is determined in step S174 that the predetermined time has not elapsed since the photocoupler 181-1 was turned on, the procedure of step S175 is skipped and the procedure proceeds to step S176.

[0175] In step S176, the determination unit 132 of the drive control unit 124 references the time measured by the timer 133 to determine whether a predetermined time has elapsed since the switch 184-2, which is the high-side switch, was opened. For example, the determination unit 132 of the drive control unit 124 determines whether a time between 0.1 seconds and 10 seconds has elapsed since the switch 184-2 was opened. More preferably, for example, the determination unit 132 of the drive control unit 124 determines whether 5 seconds have elapsed since the switch 184-2 was opened. If it is determined in step S176 that a predetermined time has elapsed since the switch 184-2 was opened, the procedure proceeds to step S177, where the insulation control unit 131 of the drive control unit 124 outputs a drive signal from the input / output interface 105 to the switch 184-2 to close the switch 184-2. In other words, the output terminal of the switch 184 is connected. As a result, a voltage VL is applied to the terminal for electrically connecting to the electrode film on the outer surface of the piezoelectric element 52 of the piezoelectric driving element 31, and a voltage VH and a voltage VL are applied to each of the two surfaces of the piezoelectric element 52.

[0176] After a predetermined time has elapsed since the terminals for electrically connecting to the electrode film on the outer surface of the piezoelectric element 52 of the piezoelectric driving element 31 have been insulated, voltages VH and VL are again applied to both surfaces of the piezoelectric element 52, respectively, in order to prevent the charge accumulated in the piezoelectric element 52 from decreasing due to natural discharge and causing the bending posture of the piezoelectric driving element 31 to change.

[0177] After the procedure of step S177, the timer 133 starts counting time. After the procedure of step S177, the procedure proceeds to step S178.

[0178] If it is determined in step S176 that the predetermined time has not elapsed since the switch 184 was opened, the procedure of step S177 is skipped and the procedure proceeds to step S178.

[0179] In step S178, the determination section 132 of the drive control section 124 determines whether the signal indicating the state of the piezoelectric drive element 31 is High by referring to the pattern data assigned by the pattern data assignment section 122 and the timing instruction from the timing control section 123. If it is determined in step S178 that the signal indicating the state of the piezoelectric drive element 31 is High, the procedure returns to step S174, and the above-described procedure is repeated.

[0180] If it is determined in step S178 that the signal indicating the state of the piezoelectric driving element 31 is not High, the procedure returns to step S171.

[0181] In step S171, if it is determined that the signal indicating the state of the piezoelectric drive element 31 is not High, that is, the signal indicating the state of the piezoelectric drive element 31 is Low, the procedure proceeds to step S179, and the drive control unit 124 outputs drive signals from the input / output interface 105 to switch 184-1, which is the Low-side switch, and switch 184-2, which is the High-side switch, to close switches 184-1 and 184-2. That is, the output terminals of switches 184-1 and 184-2 are connected.

[0182] In step S180, the drive control unit 124 sets the drive signal output from the input / output interface 105 to the photocouplers 181-1 and 181-2 to a high level, turning off the high-side photocoupler, i.e., photocoupler 181-1, and turning on the low-side photocoupler, i.e., photocoupler 181-2. According to the procedure of step S180, similar to step S140 in Fig. 9, voltages VH and VL are applied to both surfaces of the piezoelectric element 51, respectively, and the electric charge of the piezoelectric element 52 is discharged.

[0183] Therefore, electric charge is discharged from the piezoelectric element 52 and current flows into the piezoelectric element 51, so that electric charge accumulates in the piezoelectric element 51, and as shown in the upper part of Figure 2, the piezoelectric driving element 31 bends so that the transmission part 41 is displaced upward.

[0184] After the procedure of step S180, the timer 133 starts counting time.

[0185] In step S181, the determination unit 132 of the drive control unit 124 references the time measured by the timer 133 to determine whether a predetermined time has elapsed since the low-side photocoupler, i.e., photocoupler 181-2, was turned on. For example, the determination unit 132 of the drive control unit 124 determines whether any time between 4 ms and 6 ms has elapsed since the photocoupler 181-2 was turned on. More preferably, for example, the determination unit 132 of the drive control unit 124 determines whether 5 ms has elapsed since the photocoupler 181-2 was turned on. If it is determined in step S181 that the predetermined time has elapsed since the photocoupler 181-2 was turned on, the procedure proceeds to step S182, where the insulation control unit 131 of the drive control unit 124 outputs a drive signal from the input / output interface 105 to the low-side switch 184-1, thereby opening the low-side switch 184-1. That is, the terminals for electrical connection to the electrode films on the outer surfaces of the piezoelectric elements 51 of the piezoelectric driving element 31 are insulated.

[0186] When the terminals for electrically connecting to the electrode film on the outer surface of the piezoelectric element 51 of the piezoelectric driving element 31 are insulated, the electric charge remains accumulated in the piezoelectric element 51, and the bending of the piezoelectric driving element 31 is maintained.

[0187] After the procedure of step S182, the timer 133 starts counting time. After the procedure of step S182, the procedure proceeds to step S183.

[0188] If it is determined in step S181 that the predetermined time has not elapsed since the photocoupler 71-2 was turned on, the procedure of step S182 is skipped and the procedure proceeds to step S183.

[0189] In step S183, the determination unit 132 of the drive control unit 124 references the time measured by the timer 133 to determine whether a predetermined time has elapsed since the switch 184-1, which is the low-side switch, was opened. For example, the determination unit 132 of the drive control unit 124 determines whether any time between 0.1 seconds and 10 seconds has elapsed since the switch 184-1 was opened. More preferably, for example, the determination unit 132 of the drive control unit 124 determines whether 5 seconds have elapsed since the switch 184-1 was opened. If it is determined in step S183 that the predetermined time has elapsed since the switch 184-1 was opened, the procedure proceeds to step S184, where the insulation control unit 131 of the drive control unit 124 outputs a drive signal from the input / output interface 105 to the switch 184-1 to close the switch 184-1. In other words, the output terminal of the switch 184-1 is connected. As a result, a voltage VH is applied to the terminal for electrically connecting to the electrode film on the outer surface of the piezoelectric element 51 of the piezoelectric driving element 31, and a voltage VH and a voltage VL are applied to each of the two surfaces of the piezoelectric element 51.

[0190] After a predetermined time has elapsed since the terminals for electrically connecting to the electrode film on the outer surface of the piezoelectric element 51 of the piezoelectric driving element 31 have been insulated, voltages VH and VL are again applied to both surfaces of the piezoelectric element 51, respectively, in order to prevent the charge accumulated in the piezoelectric element 51 from decreasing due to natural discharge and causing the bending posture of the piezoelectric driving element 31 to change.

[0191] After the procedure of step S184, the timer 133 starts counting time. After the procedure of step S184, the procedure proceeds to step S185.

[0192] If it is determined in step S183 that the predetermined time has not elapsed since the switch 184 was opened, the procedure of step S184 is skipped and the procedure proceeds to step S185.

[0193] In step S185, the determination unit 132 of the drive control unit 124 determines whether the signal indicating the state of the piezoelectric drive element 31 is Low by referring to the pattern data assigned by the pattern data assignment unit 122 and the timing instruction from the timing control unit 123. If it is determined in step S185 that the signal indicating the state of the piezoelectric drive element 31 is Low, the procedure returns to step S181, and the above-mentioned procedure is repeated.

[0194] If it is determined in step S185 that the signal indicating the state of the piezoelectric driving element 31 is not low, the procedure returns to step S171, and the above-described processing is repeated.

[0195] In this way, at the beginning of the period in which the piezoelectric drive element 31 is bent in a predetermined direction, a predetermined voltage is applied between predetermined terminals of the piezoelectric drive element 31, and when a predetermined time has elapsed since the application of voltage between the terminals began during the period in which the piezoelectric drive element 31 is bent in a predetermined direction, one of the terminals is insulated.

[0196] Alternatively, in the procedures of steps S175 and S182, both switches 184-1 and 184-2 may be opened, and in the procedures of steps S177 and S184, both switches 184-1 and 184-2 may be closed.

[0197] The piezoelectric driving element 31 can also be connected by a two-wire connection method.

[0198] 12 is a diagram showing an example of the configuration of a drive circuit that drives a two-wire connection type piezoelectric drive element 31. The drive circuit 70 is configured in the same manner as in the case shown in FIG. 3. In the two-wire connection type piezoelectric drive element 31, the outer surfaces of the piezoelectric elements 51 and 52 are grounded. In the two-wire connection type piezoelectric drive element 31, the plate 53 is connected to the emitter of the phototransistor 82-1 of the photocoupler 71-1 and the collector of the phototransistor 82-2 of the photocoupler 71-2 in the drive circuit 70.

[0199] According to the drive circuit 70 shown in FIG. 12, a voltage VH or a voltage VL is applied to the terminal for electrical conduction to the plate 53 of the piezoelectric drive element 31, or the terminal for electrical conduction to the plate 53 of the piezoelectric drive element 31 is insulated.

[0200] When a voltage VH is applied to the terminal for electrical connection to the plate 53 of the piezoelectric drive element 31, a forward bias is applied to the piezoelectric element 51 and a reverse bias is applied to the piezoelectric element 52, so that the transmission part 41 of the piezoelectric drive element 31 is displaced downward. On the other hand, when a voltage VL is applied to the terminal for electrical connection to the plate 53 of the piezoelectric drive element 31, a reverse bias is applied to the piezoelectric element 51 and a forward bias is applied to the piezoelectric element 52, so that the transmission part 41 of the piezoelectric drive element 31 is displaced upward.

[0201] The drive circuit 70 shown in FIG. 12 is operated in the same manner as the process described with reference to the flowchart of FIG. 6, and therefore a description thereof will be omitted.

[0202] FIG. 13 is a diagram showing another example of the configuration of a drive circuit that drives a two-wire connection type piezoelectric drive element 31. The drive circuit 150 is configured in the same manner as in FIG. 8. In the two-wire connection type piezoelectric drive element 31, the outer surfaces of the piezoelectric elements 51 and 52 are grounded. In the drive circuit 150 shown in FIG. 13, the emitter of the phototransistor 162-1 of the photocoupler 151-1 and the collector of the phototransistor 162-2 of the photocoupler 151-2 are connected to one output terminal of the switch 154. The other output terminal of the switch 154 is connected to a terminal for electrical conduction to the plate 53 of the piezoelectric drive element 31.

[0203] In the drive circuit 150 shown in Fig. 13, one output terminal of the input / output interface 105 of the microcontroller 155 is connected to the input terminal of the switch 154. The output terminal of the switch 154 is opened or closed in response to a signal input to the input terminal. According to the drive circuit 150 shown in Fig. 13, the voltage VH or voltage VL is applied to the terminal for electrical connection to the plate 53 of the piezoelectric drive element 31, or the terminal for electrical connection to the plate 53 of the piezoelectric drive element 31 is insulated.

[0204] When a voltage VH is applied to the terminal for electrical connection to the plate 53 of the piezoelectric drive element 31, a forward bias is applied to the piezoelectric element 51 and a reverse bias is applied to the piezoelectric element 52, so that the transmission part 41 of the piezoelectric drive element 31 is displaced downward. On the other hand, when a voltage VL is applied to the terminal for electrical connection to the plate 53 of the piezoelectric drive element 31, a reverse bias is applied to the piezoelectric element 51 and a forward bias is applied to the piezoelectric element 52, so that the transmission part 41 of the piezoelectric drive element 31 is displaced upward.

[0205] The drive circuit 150 shown in FIG. 13 is operated in the same manner as the process described with reference to the flowchart of FIG. 9, and therefore the description thereof will be omitted.

[0206] 14 is a diagram showing yet another example of the configuration of a drive circuit that drives a two-wire connection type piezoelectric drive element 31. The drive circuit 200 applies a voltage to the piezoelectric drive element 31 and supplies a current to charge the piezoelectric element 51 or the piezoelectric element 52, thereby bending the piezoelectric drive element 31.

[0207] The drive circuit 200 includes photocouplers 201-1 and 201-2, resistors 202-1 and 202-2, resistors 203-1 and 203-2, a switch 204, and a microcontroller 205. The photocouplers 201-1 and 201-2 are elements that internally convert electrical signals to light and perform switching using light. The photocoupler 201-1 incorporates a light-emitting diode 211-1 and a phototransistor 212-1. The photocoupler 201-2 incorporates a light-emitting diode 211-2 and a phototransistor 212-2. The light-emitting diodes 211-1 and 211-2 are semiconductor elements that emit light when a voltage is applied. The phototransistors 212-1 and 212-2 are transistors that control current using light.

[0208] That is, the photocoupler 201-1 is a switching element that controls the current flowing through the phototransistor 212-1 in response to the light emitted by the light emitting diode 211-1, and the photocoupler 201-2 is a switching element that controls the current flowing through the phototransistor 212-2 in response to the light emitted by the light emitting diode 211-2.

[0209] The resistors 202-1, 202-2, 203-1 and 203-2 are each an electric resistance element and have a predetermined electric resistance value.

[0210] The switch 204 is a so-called switch, and is a device or element that opens and closes a predetermined electrical path in the drive circuit 200. For example, the switch 204 can be a contact relay (mechanical relay) or a contactless relay (a semiconductor relay such as a MOS FET relay). The switch 204 can also be a relay.

[0211] The microcontroller 205 is a microprocessor configured with a CPU, ROM, RAM, input / output interface, etc., as a single integrated circuit. The microcontroller 205 is a computer. The hardware configuration of the microcontroller 205 is similar to that of the microcontroller 74, and therefore a description thereof will be omitted. The functional configuration of the microcontroller 185 realized by executing a program is similar to that of the microcontroller 74, and therefore a description thereof will be omitted.

[0212] Photocoupler 201-1, photocoupler 201-2, resistor 202-1, resistor 202-2, resistor 203-1, resistor 203-2, and microcontroller 205 are interconnected in the same manner as photocoupler 71-1, photocoupler 71-2, resistor 72-1, resistor 72-2, resistor 73-1, resistor 73-2, and microcontroller 74 in FIG. 3, except that the output terminal of input / output interface 105 of microcontroller 205 is connected to the input terminal of switch 204, and therefore a description of the interconnections of photocoupler 201-1, photocoupler 201-2, resistor 202-1, resistor 202-2, resistor 203-1, resistor 203-2, and microcontroller 205 will be omitted.

[0213] In the drive circuit 200, a terminal connected to the electrode film on the outer surface of the piezoelectric element 51 and a terminal connected to the electrode film on the outer surface of the piezoelectric element 52 are connected to one output terminal of the switch 204. The other output terminal of the switch 204 is grounded.

[0214] One output terminal of the input / output interface 105 of the microcontroller 205 is connected to the input terminal of the switch 204. The output terminal of the switch 204 is opened or closed by a signal to the input terminal.

[0215] The drive circuit 200 shown in Fig. 14 is operated by the same process as that described with reference to the flowchart of Fig. 9, and therefore description thereof will be omitted. When describing the process of the drive circuit 220, the photocoupler 151-1, photocoupler 151-2, switch 154, microcontroller 155, phototransistor 162-1, and phototransistor 162-2 in the description with reference to the flowchart of Fig. 9 can be read as photocoupler 201-1, photocoupler 201-2, switch 204, microcontroller 205, phototransistor 212-1, and phototransistor 212-2, respectively.

[0216] In this way, at the beginning of the period in which the piezoelectric drive element 31 is bent in a predetermined direction, a predetermined voltage is applied between predetermined terminals of the piezoelectric drive element 31, and when a predetermined time has elapsed since the application of voltage between the terminals began during the period in which the piezoelectric drive element 31 is bent in a predetermined direction, one of the terminals is insulated.

[0217] In addition, in the procedure of step S104, step S106, step S111, step S113, step S134, step S136, step S141, step S143, step S174, step S176, step S181 or step S183, the number of judgments may be counted by counter 134, and judgment unit 132 may compare the number of judgments with a predetermined threshold value to determine whether the number of judgments has reached a predetermined number.

[0218] Furthermore, in the procedure of step S104, step S111, step S134, step S141, step S174 or step S181, the current integrator 135 may calculate an integrated value of the current flowing into the piezoelectric driving element 31 by integrating the voltage value between the two terminals of resistor 72-1, resistor 152-1, resistor 182-1 or resistor 202-1 and the current value calculated from the voltage value between the two terminals of resistor 72-2, resistor 152-2, resistor 182-2 or resistor 202-2, and the judgment unit 132 may compare the integrated value of the current with a predetermined threshold value to judge whether the integrated value of the current has reached a predetermined value.

[0219] The drive circuit 70, the drive circuit 150, or the drive circuit 200 may drive a unimorph type piezoelectric drive element that is composed of, for example, one piezoelectric element similar to the piezoelectric element 51 and, for example, a plate similar to the plate 53. In this case, the unimorph type piezoelectric drive element is connected in the same manner as the two-wire connection type piezoelectric drive element 31.

[0220] Furthermore, although the microcontroller 74, the microcontroller 155, the microcontroller 185, or the microcontroller 205 has been described as performing control, the present invention is not limited to this. Instead of the microcontroller 74, the microcontroller 155, the microcontroller 185, or the microcontroller 205, a dedicated IC (Integrated circuit) or a dedicated circuit such as a PLD (Programmable logic device) such as an FPGA (Field-programmable gate array) or an ASIC (Application specific integrated circuit) can also be used.

[0221] By intermittently controlling the voltage application to the piezoelectric drive element 31, it is possible to reduce power consumption while maintaining the generated force and movement amount of the piezoelectric drive element 31. Furthermore, by reducing the power consumption of the piezoelectric drive element 31, it is possible to reduce heat generation in the circuit.

[0222] Furthermore, by reducing the time for which a voltage is applied to the piezoelectric driving element 31, i.e., by lengthening the time for which no voltage is applied, it is possible to reduce the probability of short circuit defects occurring between the electrodes of the piezoelectric driving element 31. If the charge decreases due to natural discharge when no voltage is applied, the force generated and the amount of movement of the piezoelectric element cannot be maintained, so voltage application is resumed after a certain period of time to maintain the force generated and the amount of movement.

[0223] As described above, the piezoelectric driving element 31 and the driving circuit 70, 150, 180, or 200 can reduce the amount of power consumed and the probability of malfunctions occurring during use.

[0224] In this way, the needle selector 11 is a needle selector for a knitting machine. The piezoelectric drive element 31 is a bimorph or unimorph piezoelectric drive element. The drive circuit 70, the drive circuit 150, the drive circuit 180, or the drive circuit 200 applies a predetermined voltage between predetermined terminals of the piezoelectric drive element 31 at the beginning of a period in which the piezoelectric drive element 31 is bent in a predetermined direction, and insulates one of the terminals when a first time has elapsed since the start of application of the voltage between the terminals during the period.

[0225] The drive circuit 70 can apply a voltage between the terminals when a second time has elapsed since the terminals were isolated during the period.

[0226] The drive circuit 70 can apply a predetermined voltage between predetermined terminals of the piezoelectric drive element 31 by the phototransistor 82-1 of the photocoupler 71-1, and isolate one of the terminals.

[0227] The drive circuit 150 applies a predetermined voltage between predetermined terminals of the piezoelectric drive element 31 by the phototransistor 162-1 of the photocoupler 151-1, and can isolate one of the terminals by the switch 154.

[0228] The switch 154 can open and close the connection between the phototransistor 162-1 of the photocoupler 151-1 and the terminal of the piezoelectric driving element 31.

[0229] The switch 184-1 can open and close the connection between the piezoelectric driving element 31 and a terminal for applying a predetermined voltage to the piezoelectric driving element 31.

[0230] The piezoelectric driving element 31 can be of a bimorph type and of a three-wire connection type.

[0231] The piezoelectric driving element 31 can be of a two-wire connection type.

[0232] Furthermore, the embodiments of the present invention are not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention.

[0233] 11 needle selection device, 21 and 21-1 to 22-5 fingers, 31 piezoelectric driving element, 41 and 42 support portion, 43 transmission portion, 51 and 52 piezoelectric element, 53 plate, 61 and 62 end portion, 70, 150, 180 and 200 driving circuit, 71-1 and 71-2, 151-1 and 151-2, 181-1 and 181-2 and 201-1 and 201-2 photocoupler, 72-1 and 72-2, 152-1 and 152-2, 182-1 and 182-2 and 202-1 and 202-2, 73-1 and 73-2, 153-1 and 153-2, 183-1 and 183-2 and 203-1 and 203-2 resistor, 74, 155, 185 and 205 microcontroller, 81-1 and 81-2, 161-1 and 161-2, 191-1 and 191-2 and 211-1 and 211-2 light-emitting diodes, 82-1 and 82-2, 162-1 and 162-2, 192-1 and 192-2 and 212-1 and 212-2 phototransistors, 154, 184-1 and 184-2 and 204 switch, 101 CPU, 102 ROM, 103 RAM, 104 bus, 105 input / output interface, 106 storage unit, 107 communication unit, 121 pattern data storage unit, 122 pattern data allocation unit, 123 timing control unit, 124 drive control unit, 131 insulation control unit, 132 Determination unit, 133 timer, 134 counter, 135 current integrator

Claims

1. In a needle selecting device of a knitting machine, A bimorph or unimorph piezoelectric driving element; a driving means for applying a predetermined voltage between predetermined terminals of the piezoelectric driving element at the beginning of a period in which the piezoelectric driving element is bent in a predetermined direction so as to displace one end of the piezoelectric driving element to one of positions for selecting the operation of the knitting needles, and for insulating one of the terminals when a first time has elapsed during which an electric charge for bending the piezoelectric driving element so as to maintain the displacement of the one end to the one position has been accumulated in the piezoelectric driving element since the start of application of the voltage between the terminals during the period; A needle selection device comprising:

2. In the needle selection device according to claim 1, The driving means applies the voltage between the terminals when a second time has elapsed since the terminals were insulated from each other during the period. Needle selection device.

3. In the needle selection device according to claim 1, The driving means applies a predetermined voltage between predetermined terminals of the piezoelectric driving element by a phototransistor of a photocoupler, and insulates one of the terminals. Needle selection device.

4. In the needle selection device according to claim 1, The driving means applies a predetermined voltage between predetermined terminals of the piezoelectric driving element by a phototransistor of a photocoupler, and isolates one of the terminals by a switch. Needle selection device.

5. The needle selection device according to claim 4, The switch opens and closes between the phototransistor of the photocoupler and the terminal of the piezoelectric driving element. Needle selection device.

6. The needle selection device according to claim 4, The switch opens and closes between a terminal for applying a predetermined voltage to the piezoelectric driving element and the piezoelectric driving element. Needle selection device.

7. In the needle selection device according to claim 1, The piezoelectric driving element is a bimorph type and has a three-wire connection type. Needle selection device.

8. In the needle selection device according to claim 1, The piezoelectric driving element is a two-wire connection type. Needle selection device.

9. A method for driving a needle selecting device of a knitting machine, comprising: At the beginning of a period in which a bimorph or unimorph piezoelectric driving element is bent in a predetermined direction so as to displace one end of the piezoelectric driving element to one of the positions for selecting the operation of the knitting needle, a predetermined voltage is applied between predetermined terminals of the piezoelectric driving element; In the period, when a predetermined time has elapsed since the start of application of the voltage between the terminals, during which charge that bends the piezoelectric driving element so as to maintain the displacement of the one end to the one position has been accumulated in the piezoelectric driving element, one of the terminals is insulated. A method for driving a needle selection device.

10. The computer that controls the needle selection device of the knitting machine A step of applying a predetermined voltage between predetermined terminals of the piezoelectric driving element at the beginning of a period in which the piezoelectric driving element of a bimorph type or a unimorph type is bent in a predetermined direction so as to displace one end of the piezoelectric driving element to one of the positions for selecting the operation of the knitting needle; a step of isolating one of the terminals when a predetermined time has elapsed since the start of application of the voltage between the terminals during the period during which charge that bends the piezoelectric driving element so as to maintain the displacement of the one end to the one position has accumulated in the piezoelectric driving element; A program that executes a process including: