JP4992037B2 - DRIVE DEVICE, DRIVE DEVICE STATE DETECTION METHOD, AND DRIVE DEVICE CONTROL METHOD - Google Patents

DRIVE DEVICE, DRIVE DEVICE STATE DETECTION METHOD, AND DRIVE DEVICE CONTROL METHOD Download PDF

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JP4992037B2
JP4992037B2 JP2007031966A JP2007031966A JP4992037B2 JP 4992037 B2 JP4992037 B2 JP 4992037B2 JP 2007031966 A JP2007031966 A JP 2007031966A JP 2007031966 A JP2007031966 A JP 2007031966A JP 4992037 B2 JP4992037 B2 JP 4992037B2
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potential difference
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龍一 吉田
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Konica Minolta Advanced Layers Inc
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Description

本発明は圧電素子を用いた摩擦駆動方式の駆動装置に関する。   The present invention relates to a friction drive type drive device using a piezoelectric element.

圧電素子によって、方向によって変位速度が異なるように、軸状の振動部材を軸方向に往復変位させ、振動部材に摩擦係合する摩擦係合部材を振動部材に対してすべり変位（摩擦係合部材が移動する場合と、振動部材が移動する場合とがある）させる摩擦駆動方式の駆動装置が公知である。   Depending on the piezoelectric element, the axial vibration member is reciprocally displaced in the axial direction so that the displacement speed varies depending on the direction, and the friction engagement member that frictionally engages the vibration member is slid relative to the vibration member (friction engagement member). There is a known friction drive device that moves the vibration member and the vibration member.

このような摩擦駆動方式の駆動装置では、圧電素子に周期的に変動する電圧を印加する駆動装置が必要とされる。中でも、半導体スイッチング素子によって、圧電素子の電極に電圧を印加または接地する駆動回路が利用される。   Such a friction drive type drive device requires a drive device that applies a periodically varying voltage to the piezoelectric element. In particular, a drive circuit that applies a voltage to the electrode of the piezoelectric element or grounds the semiconductor switching element is used.

例えば、特許文献１には、圧電素子の一極を常時接地しておき、他極を電源に接続するスイッチと、接地するスイッチング素子とを備えるハーフブリッジからなる駆動回路が開示されている。また、特許文献２には、電気機械変換素子のいずれか一極を電源に接続し、他極を接地することで、圧電素子に印加される極性が変化するフルブリッジ回路が開示されている。   For example, Patent Document 1 discloses a drive circuit formed of a half bridge that includes a switch that connects one pole of a piezoelectric element to the power source and connects the other pole to a power source and a switching element that is grounded. Patent Document 2 discloses a full bridge circuit in which the polarity applied to the piezoelectric element is changed by connecting any one of the electromechanical conversion elements to a power source and grounding the other pole.

このような駆動装置では、圧電素子の特性が変化して、摩擦係合部材をすべり変位させる駆動速度が変化してしまう可能性がある。また、圧電素子のショートなどの故障が発生したときに、過大な電流が流れ、駆動装置だけでなく電源等に損害が発生する危険性がある。
特開２００１−２６８９５１号公報 特開２００１−２１１６６９号公報 In such a drive device, there is a possibility that the drive speed at which the friction engagement member is slid and displaced changes due to a change in the characteristics of the piezoelectric element. In addition, when a failure such as a short circuit of the piezoelectric element occurs, an excessive current flows, and there is a risk of causing damage not only to the driving device but also to the power source and the like.
JP 2001-268951 A JP 2001-21669 A

前記問題点に鑑みて、本発明は、圧電素子の状態を検出できる駆動装置、駆動装置の状態検出方法、および、駆動装置の制御方法を提供することを課題とする。   In view of the above problems, it is an object of the present invention to provide a drive device that can detect the state of a piezoelectric element, a drive device state detection method, and a drive device control method.

また、本発明によれば、電圧が印加されると伸縮する圧電素子と、前記圧電素子に一端が固定され、前記圧電素子の伸縮によって、軸方向に往復変位可能な振動部材と、前記振動部材に摩擦係合し、前記振動部材の往復変位によって、前記振動部材に対してすべり変位する摩擦係合部材と、前記圧電素子の電極を所定の駆動周期で電源に接続する充電スイッチング素子と、前記電極を接地する放電スイッチング素子とを備える駆動回路とを有する駆動装置の状態検出方法は、前記電源と前記圧電素子との間の電路、または、前記圧電素子と接地点との間の電路に検出抵抗を配設し、前記駆動周期中の所定のタイミングで前記検出抵抗の両端の電位差を検出し、検出した前記電位差を基に前記圧電素子の状態を判定し、前記所定のタイミングは、前記充電スイッチング素子および前記放電スイッチング素子の動作から、前記電源から前記圧電素子を介して接地点に至る回路の時定数以上遅れたタイミングであり、検出した前記電位差が前記所定の範囲より大きいときは、前記圧電素子がショートしていると判定する方法とする。 In addition, according to the present invention, a piezoelectric element that expands and contracts when a voltage is applied, a vibration member that is fixed at one end to the piezoelectric element, and that can reciprocate in the axial direction by expansion and contraction of the piezoelectric element, and the vibration member A friction engagement member that frictionally engages and reciprocally displaces with respect to the vibration member by a reciprocating displacement of the vibration member, a charge switching element that connects an electrode of the piezoelectric element to a power source at a predetermined drive cycle, and A method for detecting a state of a driving device having a driving circuit including a discharge switching element that grounds an electrode is detected in an electric circuit between the power source and the piezoelectric element or an electric circuit between the piezoelectric element and a grounding point. resistance disposed, said detecting a potential difference across the detection resistor with a predetermined timing during the driving cycle, determines the state of the piezoelectric element based on the potential difference detected, the predetermined timing A timing delayed from the operation of the charge switching element and the discharge switching element by a time constant of a circuit from the power source to the ground point via the piezoelectric element, and when the detected potential difference is larger than the predetermined range A method for determining that the piezoelectric element is short-circuited.

この方法によれば、圧電素子に充放電する際の電流値を検出抵抗における電圧降下として検出し、電圧降下の波形の変化によって圧電素子の容量変化や充放電の経路の異常を検出することができる。これにより、圧電素子の状態変化に応じて駆動電圧波形を調整して駆動力や駆動速度を標準化したり、故障の発生を検出して動作を停止し、障害を最小限度に留めることができる。 According to this method, it is possible to detect a current value when charging / discharging the piezoelectric element as a voltage drop in the detection resistor, and to detect a capacitance change of the piezoelectric element and an abnormality in a charging / discharging path by a change in the voltage drop waveform. it can. As a result, the drive voltage waveform can be adjusted according to the state change of the piezoelectric element to standardize the drive force and the drive speed, or the operation can be stopped by detecting the occurrence of a failure, thereby minimizing the failure.

また、本発明による駆動装置の制御方法は、電圧が印加されると伸縮する圧電素子と、前記圧電素子に一端が固定され、前記圧電素子の伸縮によって、軸方向に往復変位可能な振動部材と、前記振動部材に摩擦係合し、前記振動部材の往復変位によって、前記振動部材に対してすべり変位する摩擦係合部材と、前記圧電素子の電極を所定の駆動周期で電源に接続する充電スイッチング素子と、前記電極を接地する放電スイッチング素子とを備える駆動回路とを有する駆動装置の制御方法であって、前記電源と前記圧電素子との間の電路、または、前記圧電素子と接地点との間の電路に検出抵抗を配設し、前記駆動周期中の所定のタイミングで前記検出抵抗の両端の電位差を測定し、検出した前記電位差を基に前記圧電素子の状態を判定し、前記所定のタイミングは、前記充電スイッチング素子および前記放電スイッチング素子の動作から僅かに遅れたタイミングであり、検出した前記電位差が増大したときは、前記圧電素子の容量が増加していると判定し、前記圧電素子の容量の増加を検出したときは、前記駆動周期を長くする方法とする。 Further, the control method of the driving device according to the present invention includes a piezoelectric element that expands and contracts when a voltage is applied, and a vibration member that has one end fixed to the piezoelectric element and is capable of reciprocating in the axial direction by the expansion and contraction of the piezoelectric element. Charge switching for frictionally engaging the vibration member and slidingly displacing the vibration member by reciprocating displacement of the vibration member and the electrode of the piezoelectric element connected to a power source at a predetermined drive cycle A drive device control method comprising: an element; and a drive circuit including a discharge switching element for grounding the electrode, wherein an electric path between the power source and the piezoelectric element, or between the piezoelectric element and a ground point A detection resistor is disposed in the electric circuit between the two, and a potential difference between both ends of the detection resistor is measured at a predetermined timing during the driving cycle, and a state of the piezoelectric element is determined based on the detected potential difference. Predetermined timing is a timing which is slightly delayed from the operation of the charge switching device and the discharge switching element, when the potential difference detected is increased, it is determined that the capacity of the piezoelectric element is increased, the When an increase in the capacitance of the piezoelectric element is detected, the driving cycle is lengthened.

圧電素子がショートした場合、充放電電流が減衰しないので、スイッチング素子の動作から圧電素子と検出抵抗とからなるＲＣ回路の時定数以上遅れたタイミングで検出抵抗の電位差を測定し、電位差が大きい場合は圧電素子のショートであることが分かる。圧電素子の容量の変化応じて、デューティ比や駆動周期などを変更することで、駆動力や駆動速度を標準化できる。 When the piezoelectric element is short-circuited, the charge / discharge current is not attenuated, so the potential difference of the detection resistor is measured at a timing that is delayed by more than the time constant of the RC circuit consisting of the piezoelectric element and the detection resistor from the operation of the switching element. Is a short circuit of the piezoelectric element. The driving force and driving speed can be standardized by changing the duty ratio and the driving cycle according to the change in the capacitance of the piezoelectric element.

本発明によれば、検出抵抗による電圧降下を測定して圧電素子の容量の変化を検出することにより、駆動装置の動作を最適化することができる。   According to the present invention, the operation of the driving device can be optimized by measuring the voltage drop due to the detection resistor and detecting the change in the capacitance of the piezoelectric element.

これより、本発明の実施形態について、図面を参照しながら説明する。
図１に、本発明の第１実施形態の駆動装置１の構成を示す。駆動装置１は、電圧Ｖｐ（Ｖ）の直流電源２および制御装置３が接続された駆動回路４と、駆動回路の出力が電極５ａ，５ｂに印加される圧電素子５と、圧電素子５に一端が固定された軸状の振動部材６と、振動部材６に摩擦力によって係合する摩擦係合部材７とを有する。 Embodiments of the present invention will now be described with reference to the drawings.
In FIG. 1, the structure of the drive device 1 of 1st Embodiment of this invention is shown. The driving device 1 includes a driving circuit 4 to which a DC power source 2 having a voltage Vp (V) and a control device 3 are connected, a piezoelectric element 5 to which an output of the driving circuit is applied to the electrodes 5a and 5b, and one end to the piezoelectric element 5. Is fixed to the shaft-like vibration member 6 and the friction engagement member 7 is engaged with the vibration member 6 by a frictional force.

圧電素子５は、電極５ａ，５ｂ間に印加される電圧に応じて、振動部材６の軸方向に伸縮するようになっている。圧電素子５が伸縮すると、振動部材６は軸方向に往復移動（変位）する。摩擦係合部材７は、振動部材６が緩慢に移動する場合には、振動部材６に摩擦係合したままともに移動するが、振動部材６が急峻に移動すると、その慣性力によってその場に留ろうとして、振動部材６に対してすべり変位する。   The piezoelectric element 5 expands and contracts in the axial direction of the vibration member 6 according to the voltage applied between the electrodes 5a and 5b. When the piezoelectric element 5 expands and contracts, the vibrating member 6 reciprocates (displaces) in the axial direction. When the vibration member 6 moves slowly, the friction engagement member 7 moves together with the vibration member 6 while being frictionally engaged. However, when the vibration member 6 moves steeply, the friction engagement member 7 stays in place due to its inertial force. As a result, the sliding displacement occurs with respect to the vibrating member 6.

駆動回路４は、制御装置３の制御信号Ｓ１，Ｓ２，Ｓ３，Ｓ４によってオン／オフさせられる４つのトランジスタ８，９，１０，１１と、保護抵抗１２とを備える。トランジスタ８は、オンすることで電源２の電圧を保護抵抗１２を介して圧電素子５の電極５ａに印加するｐチャネル型ＦＥＴからなる充電スイッチング素子であり、トランジスタ９は、オンすることで電極５ａを保護抵抗１２を介して接地するｎチャネル型ＦＥＴからなる放電スイッチング素子である。また、トランジスタ１０は、オンすることで電源２の電圧を電極５ｂに印加するｐチャネル型ＦＥＴからなる充電スイッチング素子であり、トランジスタ１１は、オンすることで電極５ｂを接地するｎチャネル型ＦＥＴからなる放電スイッチング素子である。   The drive circuit 4 includes four transistors 8, 9, 10, 11 that are turned on / off by control signals S 1, S 2, S 3, S 4 of the control device 3 and a protective resistor 12. The transistor 8 is a charge switching element composed of a p-channel FET that turns on to apply the voltage of the power supply 2 to the electrode 5a of the piezoelectric element 5 via the protective resistor 12, and the transistor 9 turns on the electrode 5a. Is a discharge switching element composed of an n-channel FET that grounds through a protective resistor 12. The transistor 10 is a charge switching element composed of a p-channel FET that turns on and applies the voltage of the power supply 2 to the electrode 5b. The transistor 11 is an n-channel FET that turns on and grounds the electrode 5b. This is a discharge switching element.

また、駆動装置１は、検出抵抗１２の両端の電位Ｖ１，Ｖ２の電位差ｄＶを導出して制御装置３に入力する差分器（電位差検出手段）１３を有している。制御装置３は、入力された電位差ｄＶをＡ／Ｄ変換し、電位差ｄＶに基づいて圧電素子５の状態を判定し（状態判定手段）、圧電素子５の状態に応じて駆動回路４を最適に制御する。   The driving device 1 also includes a differentiator (potential difference detection means) 13 that derives a potential difference dV between the potentials V1 and V2 across the detection resistor 12 and inputs the potential difference dV to the control device 3. The control device 3 performs A / D conversion on the input potential difference dV, determines the state of the piezoelectric element 5 based on the potential difference dV (state determination unit), and optimizes the drive circuit 4 according to the state of the piezoelectric element 5. Control.

制御装置３は、トランジスタ８，９，１０，１１をそれぞれ駆動する周期的な矩形波状の制御信号Ｓ１，Ｓ２，Ｓ３，Ｓ４を出力するが、制御信号Ｓ１と制御信号Ｓ２が同じ波形であり、制御信号Ｓ３と制御信号Ｓ４とは、制御信号Ｓ１，Ｓ２の反転出力である。これにより、制御装置３は、トランジスタ８とトランジスタ１１とが同時にオンし、トランジスタ９とトランジスタ１０とがトランジスタ８，１１がオフのときにオンするように駆動回路４を制御する。つまり、駆動回路４は、圧電素子５の電極５ａ，５ｂのいずれか一方に電源２の電圧Ｖｐ（Ｖ）を印加しながら他方を接地し、電圧Ｖｐ（Ｖ）を印加する電極５ａ，５ｂを交互に切り替えるフルブリッジ回路である。   The control device 3 outputs periodic rectangular wave-shaped control signals S1, S2, S3, and S4 that drive the transistors 8, 9, 10, and 11 respectively, but the control signal S1 and the control signal S2 have the same waveform, The control signal S3 and the control signal S4 are inverted outputs of the control signals S1 and S2. Thereby, the control device 3 controls the drive circuit 4 so that the transistor 8 and the transistor 11 are simultaneously turned on, and the transistor 9 and the transistor 10 are turned on when the transistors 8 and 11 are off. That is, the drive circuit 4 applies the voltage Vp (V) of the power source 2 to one of the electrodes 5 a and 5 b of the piezoelectric element 5 while grounding the other, and applies the electrodes 5 a and 5 b to which the voltage Vp (V) is applied. It is a full bridge circuit that switches alternately.

制御信号Ｓ１，Ｓ２，Ｓ３，Ｓ４の駆動周期をＴ（秒）とすると、例えば、トランジスタ８，１１は、０．７Ｔ（秒）のオンと０．３Ｔ（秒）のオフとを繰り返し、トランジスタ９，１０は、０．７Ｔ（秒）のオフと０．３Ｔ（秒）のオンとを繰り返す。これによって、圧電素子５の電極５ａ−５ｂ間には、＋Ｖｐ（Ｖ）が０．７Ｔ（秒）、−Ｖｐ（Ｖ）が０．３Ｔ（秒）、繰り返し印加される。この場合、圧電素子５および振動部材６の機械的な遅れによって、振動部材６は圧電素子５に押し出される方向と圧電素子５に引き戻される方向との移動速度に違いが生じ、摩擦係合部材７を振動部材６に対して一方向にだけすべり移動させて駆動する。   Assuming that the drive period of the control signals S1, S2, S3, S4 is T (seconds), for example, the transistors 8 and 11 repeat 0.7T (seconds) on and 0.3T (seconds) off, 9 and 10 repeat 0.7T (second) off and 0.3T (second) on. Accordingly, + Vp (V) is repeatedly applied between the electrodes 5 a-5 b of the piezoelectric element 5 by 0.7 T (seconds) and -Vp (V) by 0.3 T (seconds). In this case, due to the mechanical delay of the piezoelectric element 5 and the vibration member 6, the moving speed of the vibration member 6 is different between the direction in which the vibration member 6 is pushed out to the piezoelectric element 5 and the direction in which the vibration member 6 is pulled back to the piezoelectric element 5. Is driven by sliding in one direction with respect to the vibration member 6.

トランジスタ８，１１がオンする時間の比（デューティ比）は、摩擦係合部材７を移動させる速度に応じて変更されるようになっており、制御信号Ｓ１，Ｓ２と、制御信号Ｓ３，Ｓ４との出力時間比を入れ替えることによって、摩擦係合部材７がすべり移動する方向を逆転させることができる。   The ratio (duty ratio) of the time during which the transistors 8 and 11 are turned on is changed according to the speed at which the friction engagement member 7 is moved, and the control signals S1 and S2, the control signals S3 and S4, By switching the output time ratio, the direction in which the friction engagement member 7 slides can be reversed.

図２に、駆動装置１の制御信号Ｓ１，Ｓ２，Ｓ３，Ｓ４と、圧電素子５の電極５ａ−５ｂ間に印加される電圧と、検出抵抗１２における電圧降下（ｄＶ）、つまり、検出抵抗１２の両端の電位差（Ｖ１−Ｖ２）との関係を示す。   FIG. 2 shows the control signals S1, S2, S3, S4 of the driving device 1, the voltage applied between the electrodes 5a-5b of the piezoelectric element 5, and the voltage drop (dV) in the detection resistor 12, that is, the detection resistor 12 The relationship with the potential difference (V1-V2) of both ends of is shown.

制御信号Ｓ１，Ｓ２，Ｓ３，Ｓ４は、矩形波であり、トランジスタ８，１１またはトランジスタ９，１０を同時にオンして電源２と接地点とを圧電素子５を介して接続する。しかしながら、トランジスタ８，１１または９，１０のオン抵抗、検出抵抗１３および圧電素子の内部抵抗があるために、充電電流が制限され、これらの抵抗において電圧降下が発生するので、図示するように、圧電素子５の電極５ａ−５ｂ間に現れる電圧は、１次遅れの波形となる。   The control signals S1, S2, S3, and S4 are rectangular waves, and the transistors 8 and 11 or the transistors 9 and 10 are simultaneously turned on to connect the power source 2 and the ground point via the piezoelectric element 5. However, because of the on-resistance of the transistors 8, 11 or 9, 10 and the internal resistance of the detection resistor 13 and the piezoelectric element, the charging current is limited and a voltage drop occurs in these resistors. The voltage appearing between the electrodes 5a-5b of the piezoelectric element 5 has a first-order lag waveform.

圧電素子５の充放電に係る回路、つまり、駆動装置１の電源２から圧電素子５を介して接地点に至る回路は、ＲＣ回路と同視できる。例えば、検出抵抗が１（Ω）、ｐチャネル型ＦＥＴからなるトランジスタ８，１０のオン抵抗が０．７（Ω）およびｎチャネル型ＦＥＴからなるトランジスタ９，１１のオン抵抗０．３（Ω）であり、圧電素子５の容量が（７０ｎＦ）であるとすると、このＲＣ回路の時定数τは、約０．１４（μ秒）である。   A circuit related to charging / discharging of the piezoelectric element 5, that is, a circuit extending from the power source 2 of the driving device 1 to the ground point via the piezoelectric element 5 can be regarded as an RC circuit. For example, the detection resistance is 1 (Ω), the on-resistance of the transistors 8 and 10 made of p-channel FET is 0.7 (Ω), and the on-resistance of the transistors 9 and 11 made of n-channel FET is 0.3 (Ω) If the capacitance of the piezoelectric element 5 is (70 nF), the time constant τ of this RC circuit is about 0.14 (μ seconds).

駆動装置１の制御装置３は、トランジスタ８，９，１０，１１の動作（切り替わり）からτμ秒後と、１０τμ秒後の検出抵抗１２における電位差（それぞれ、ｄＶ１，ｄＶ２とする）とを測定している。 The control device 3 of the driving device 1 calculates the potential difference (referred to as dV 1 and dV 2 respectively) at the detection resistor 12 after τμ seconds and 10τμ seconds after the operation (switching) of the transistors 8, 9, 10, 11. Measuring.

駆動装置１が初期状態にある正常時において、電位差ｄＶ１は、トランジスタ８，９，１０，１１の動作時に現れる最大値の約３７％であり、電位差ｄＶ２は、略ゼロである。 In the normal state in which the driving device 1 is in the initial state, the potential difference dV 1 is about 37% of the maximum value that appears when the transistors 8, 9, 10, and 11 are operated, and the potential difference dV 2 is substantially zero.

圧電素子５の容量が増加した場合、圧電素子５を充電するために必要な電荷の量が多くなるので、正常時に較べて電流値の減少が緩やかになる。このため、トランジスタ８，９，１０，１１の動作から十分に時間が経過したときの電位差ｄＶ２は変わらないが、トランジスタ８，９，１０，１１の動作から僅かに遅れたタイミングでの電位差ｄＶ１は正常時に較べて大きな値を示している。 When the capacity of the piezoelectric element 5 is increased, the amount of electric charge necessary for charging the piezoelectric element 5 is increased, so that the current value is gradually decreased as compared with the normal time. For this reason, the potential difference dV 2 when a sufficient amount of time has elapsed from the operation of the transistors 8, 9, 10, 11 does not change, but the potential difference dV at a timing slightly delayed from the operation of the transistors 8, 9, 10, 11. 1 shows a larger value than in the normal state.

このように、トランジスタ８，９，１０，１１の動作から僅かに遅れたタイミングで、検出抵抗１２の両端の電位差ｄＶ１を測定すれば、電位差ｄＶ１の大きさによって圧電素子５の容量の増減を判定することができる。 Thus, if the potential difference dV 1 across the detection resistor 12 is measured at a timing slightly delayed from the operation of the transistors 8, 9, 10, 11, the capacitance of the piezoelectric element 5 increases or decreases depending on the magnitude of the potential difference dV 1. Can be determined.

この電位差ｄＶ１を測定するタイミングは、トランジスタ８，９，１０，１１の動作の直後では、測定値が大きく増減を判定しやすい反面、電位差の変化率が大きいために測定誤差が大きくなる。逆に、トランジスタ８，９，１０，１１の動作から大きく遅れると、電位差の変化率は小さく測定誤差が小さくなるが、測定値が非常に小さくなるので正常時との比較が困難になる。 The timing for measuring the potential difference dV 1 is large immediately after the operation of the transistors 8, 9, 10, and 11, but it is easy to determine increase / decrease, but the measurement rate increases because the change rate of the potential difference is large. Conversely, if the operation of the transistors 8, 9, 10, and 11 is greatly delayed, the change rate of the potential difference is small and the measurement error is small. However, the measurement value is very small, so that comparison with the normal time becomes difficult.

駆動装置１を完全なＲＣ回路と仮定すると、トランジスタ８，９，１０，１１の動作から時定数τの０．１倍だけ遅れた時点で、検出抵抗１２の電位差ｄＶは、最大値の約９０％まで減少し、変化率もある程度緩やかになる。また、トランジスタ８，９，１０，１１の動作から時定数τの２倍だけ遅れた時点では、検出抵抗１２の電位差ｄＶは、最大値の約１４％まで減少し、これ以上測定値が減少すると正常時との比が正確に求められなくなる。よって、圧電素子５の容量の変化を判定するためには、検出抵抗１２の両端の電位差ｄＶ１を、トランジスタ８，９，１０，１１の動作から時定数τの０．１倍以上、２倍以下だけ遅れた時点で測定することが好ましい。 Assuming that the driving device 1 is a complete RC circuit, the potential difference dV of the detection resistor 12 is about 90 times the maximum value at a time delayed by 0.1 times the time constant τ from the operation of the transistors 8, 9, 10, and 11. %, The rate of change will be moderate to some extent. When the operation of the transistors 8, 9, 10, and 11 is delayed by twice the time constant τ, the potential difference dV of the detection resistor 12 decreases to about 14% of the maximum value, and the measured value further decreases. The ratio to the normal time cannot be obtained accurately. Therefore, in order to determine the change in the capacitance of the piezoelectric element 5, the potential difference dV 1 across the detection resistor 12 is set to 0.1 times or more and 2 times the time constant τ from the operation of the transistors 8, 9, 10, and 11. It is preferable to measure at a point delayed by the following.

また、圧電素子５がショートした場合、電位差ｄＶ１だけでなく電位差ｄＶ２も上昇している。つまり、圧電素子５のショートを判定するためには、トランジスタ８，９，１０，１１の動作から十分に遅れた時点で、電位差ｄＶ２を測定することが効果的である。トランジスタ８，９，１０，１１の動作から時定数τだけ遅れた時点で、検出抵抗１２の電位差ｄＶは、最大値の約３７％まで減少し、ショート時の電位差との違いを容易に検出できる。つまり、圧電素子５のショートの判定には、トランジスタ８，９，１０，１１の動作から時定数τ以上遅れて、検出抵抗１２の電位差ｄＶ２を測定することが好ましい。 When the piezoelectric element 5 is short-circuited, not only the potential difference dV 1 but also the potential difference dV 2 is increased. That is, in order to determine whether the piezoelectric element 5 is short-circuited, it is effective to measure the potential difference dV 2 when it is sufficiently delayed from the operation of the transistors 8, 9, 10, and 11. When the operation is delayed by the time constant τ from the operation of the transistors 8, 9, 10, and 11, the potential difference dV of the detection resistor 12 decreases to about 37% of the maximum value, and the difference from the potential difference at the time of short-circuit can be easily detected. . That is, for determining whether the piezoelectric element 5 is short-circuited, it is preferable to measure the potential difference dV 2 of the detection resistor 12 after a time constant τ or more from the operation of the transistors 8, 9, 10, and 11.

また、圧電素子５または駆動回路４が断線したときは、電位差ｄＶ１およびｄＶ２はともにゼロになっている。つまり、トランジスタ８，９，１０，１１の動作から僅かに遅れて測定した電位差ｄＶ１によって断線を監視することもできる。 Further, when the piezoelectric element 5 or the drive circuit 4 is disconnected, the potential differences dV 1 and dV 2 are both zero. That is, the disconnection can be monitored by the potential difference dV 1 measured slightly after the operation of the transistors 8, 9, 10, and 11.

圧電素子５のショートや圧電素子５または駆動回路４の断線が検出された場合、電源２等を保護するために、制御装置３が制御信号Ｓ１，Ｓ２，Ｓ３，Ｓ４を出力しないようにするとよい。さらに、このような異常を知らせるために外部に信号を出力するようにしてもよい。   When a short circuit of the piezoelectric element 5 or a disconnection of the piezoelectric element 5 or the drive circuit 4 is detected, the control device 3 should not output the control signals S1, S2, S3, S4 in order to protect the power supply 2 and the like. . Further, a signal may be output to the outside in order to notify such an abnormality.

本実施形態では、検出抵抗１２を、トランジスタ８，９と電極５ａとの間の電路に設けているが、トランジスタ１０，１１と電極５ｂとの間の電路（図中の点Ａ）、電源２とトランジスタ８，１０との間の電路（図中の点Ｂ）、或いは、トランジスタ９，１１と接地点との間の電路（図中の点Ｃ）に検出抵抗１２を配設してもよい。   In the present embodiment, the detection resistor 12 is provided in the electric circuit between the transistors 8 and 9 and the electrode 5a. However, the electric circuit between the transistors 10 and 11 and the electrode 5b (point A in the figure), the power source 2 And the detection resistor 12 may be arranged in the electric circuit between the transistors 8 and 10 (point B in the figure) or the electric circuit between the transistors 9 and 11 and the ground point (point C in the figure). .

尚、本実施形態では、差分器１３によって、検出抵抗１２の電位差ｄＶを測定しているが、制御装置３の内部で演算によって算出するようにしてもよい。また、検出抵抗１２の電位差ｄＶの積分値を測定するようにすれば、電流値の総和、つまり、圧電素子５に充電された電荷の総量を算出することができ、圧電素子５の容量をより正確に判定できる。   In the present embodiment, the potential difference dV of the detection resistor 12 is measured by the differentiator 13, but may be calculated by calculation inside the control device 3. If the integral value of the potential difference dV of the detection resistor 12 is measured, the sum of the current values, that is, the total amount of charges charged in the piezoelectric element 5 can be calculated, and the capacitance of the piezoelectric element 5 can be further increased. Accurate judgment can be made.

さらに、図３に、本発明の第２実施形態の駆動装置１の構成を示す。本実施形態の説明において、第１実施形態と同じ構成要素には同じ符号を付して、説明を省略する。本実施形態の駆動回路４は、充電スイッチング素子である１つのトランジスタ８と、放電スイッチング素子である１つのトランジスタ９とを備え、圧電素子５の電極５ａが電源２または接地点に接続され、電極５ｂが常に接地されているハーフブリッジ回路である。   Further, FIG. 3 shows a configuration of the driving apparatus 1 according to the second embodiment of the present invention. In the description of the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The drive circuit 4 of the present embodiment includes one transistor 8 that is a charge switching element and one transistor 9 that is a discharge switching element, and the electrode 5a of the piezoelectric element 5 is connected to the power supply 2 or the ground point, and the electrode A half bridge circuit 5b is always grounded.

本実施形態では、小さな入力電流でトランジスタ８をスイッチングできるように、バイポーラトランジスタ１３と複数の抵抗１４，１５，１６，１７，１８を備えているが、制御信号Ｓ１によってトランジスタ８がオンし、制御信号Ｓ２によってトランジスタ９がオンすることに変わりはない。   In this embodiment, the bipolar transistor 13 and the plurality of resistors 14, 15, 16, 17, and 18 are provided so that the transistor 8 can be switched with a small input current. However, the transistor 8 is turned on by the control signal S1, and the control is performed. The transistor 9 is still turned on by the signal S2.

本実施形態においても、検出抵抗１２において、圧電素子５の充放電電流による電圧降下が発生し、この電圧降下を測定することで、圧電素子５の容量変化などの駆動装置１の状態を判定でき、判定結果に応じて、制御信号Ｓ１，Ｓ２のパターンを変えることによって、駆動装置１の性能変化を補償することができる。   Also in this embodiment, a voltage drop due to the charging / discharging current of the piezoelectric element 5 occurs in the detection resistor 12, and by measuring this voltage drop, the state of the driving device 1 such as a capacitance change of the piezoelectric element 5 can be determined. The performance change of the drive device 1 can be compensated by changing the pattern of the control signals S1 and S2 according to the determination result.

本実施形態においても、検出抵抗１２を、トランジスタ８，９と電極５ａとの間の電路（点Ｄ）や、電極５ｂと接地点との間の電路（点Ｅ）に設けてもよい。   Also in this embodiment, the detection resistor 12 may be provided on the electric circuit (point D) between the transistors 8 and 9 and the electrode 5a, or on the electric circuit (point E) between the electrode 5b and the ground point.

本実施形態において、圧電素子５をレンズユニットの筐体に固定し、摩擦係合部材７にレンズを保持すれば、素子固定式のレンズ移動機構になる。また、圧電素子５を移動ステージに固定し、摩擦係合部材７を筐体に固定すれば、振動部材６および圧電素子５が摩擦係合部材７に対して移動（摩擦係合部材７が相対的に振動部材６に対してすべり変位）して移動ステージを駆動する、自走式のステージ移動機構となる。   In this embodiment, if the piezoelectric element 5 is fixed to the housing of the lens unit and the lens is held on the friction engagement member 7, an element-fixing type lens moving mechanism is obtained. If the piezoelectric element 5 is fixed to the moving stage and the friction engagement member 7 is fixed to the housing, the vibration member 6 and the piezoelectric element 5 move relative to the friction engagement member 7 (the friction engagement member 7 is relatively Thus, a self-propelled stage moving mechanism that drives the moving stage by sliding relative to the vibration member 6 is obtained.

本発明の第１実施形態の駆動装置の回路図。The circuit diagram of the drive device of a 1st embodiment of the present invention. 図１の駆動装置に制御信号と充放電電流の関係を示すタイムチャート。The time chart which shows the relationship between a control signal and charging / discharging electric current in the drive device of FIG. 本発明の第２実施形態の駆動装置の回路図。The circuit diagram of the drive device of 2nd Embodiment of this invention.

符号の説明Explanation of symbols

１ 駆動装置
２ 電源
３ 制御装置（状態判定手段）
４ 駆動回路
５ 圧電素子
５ａ，５ｂ 電極
６ 振動部材
７ 摩擦係合部材
８ トランジスタ（充電スイッチング素子）
９ トランジスタ（放電スイッチング素子）
１０ トランジスタ（充電スイッチング素子）
１１ トランジスタ（放電スイッチング素子）
１２ 検出抵抗
１３ 差分器（電位差検出手段） DESCRIPTION OF SYMBOLS 1 Drive apparatus 2 Power supply 3 Control apparatus (state determination means)
4 Drive Circuit 5 Piezoelectric Element 5a, 5b Electrode 6 Vibration Member 7 Friction Engagement Member 8 Transistor (Charge Switching Element)
9 Transistor (Discharge switching element)
10 Transistor (Charge switching element)
11 Transistor (Discharge switching element)
12 Detection resistor 13 Differentiator (potential difference detection means)

Claims (2)

電圧が印加されると伸縮する圧電素子と、前記圧電素子に一端が固定され、前記圧電素子の伸縮によって、軸方向に往復変位可能な振動部材と、前記振動部材に摩擦係合し、前記振動部材の往復変位によって、前記振動部材に対してすべり変位する摩擦係合部材と、前記圧電素子の電極を所定の駆動周期で電源に接続する充電スイッチング素子と、前記電極を接地する放電スイッチング素子とを備える駆動回路とを有する駆動装置の状態検出方法であって、
前記電源と前記圧電素子との間の電路、または、前記圧電素子と接地点との間の電路に検出抵抗を配設し、
前記駆動周期中の所定のタイミングで前記検出抵抗の両端の電位差を測定し、
検出した前記電位差を基に前記圧電素子の状態を判定し、
前記所定のタイミングは、前記充電スイッチング素子および前記放電スイッチング素子の動作から、前記電源から前記圧電素子を介して接地点に至る回路の時定数以上遅れたタイミングであり、
検出した前記電位差が前記所定の範囲より大きいときは、前記圧電素子がショートしていると判定することを特徴とする駆動装置の状態検出方法。 A piezoelectric element that expands and contracts when a voltage is applied, a vibration member that is fixed at one end to the piezoelectric element, and that can reciprocally move in the axial direction by the expansion and contraction of the piezoelectric element, and frictionally engage with the vibration member, and the vibration A friction engagement member that slides and displaces with respect to the vibration member by a reciprocal displacement of the member; a charge switching element that connects an electrode of the piezoelectric element to a power source at a predetermined drive cycle; and a discharge switching element that grounds the electrode A state detection method for a drive device having a drive circuit comprising:
A detection resistor is disposed in an electric circuit between the power source and the piezoelectric element, or an electric circuit between the piezoelectric element and a ground point,
Measure the potential difference between both ends of the detection resistor at a predetermined timing during the driving cycle,
Determine the state of the piezoelectric element based on the detected potential difference ,
The predetermined timing is a timing delayed from the operation of the charge switching element and the discharge switching element by a time constant of a circuit from the power source to the ground point via the piezoelectric element,
When the detected potential difference is larger than the predetermined range, it is determined that the piezoelectric element is short-circuited . 電圧が印加されると伸縮する圧電素子と、前記圧電素子に一端が固定され、前記圧電素子の伸縮によって、軸方向に往復変位可能な振動部材と、前記振動部材に摩擦係合し、前記振動部材の往復変位によって、前記振動部材に対してすべり変位する摩擦係合部材と、前記圧電素子の電極を所定の駆動周期で電源に接続する充電スイッチング素子と、前記電極を接地する放電スイッチング素子とを備える駆動回路とを有する駆動装置の制御方法であって、
前記電源と前記圧電素子との間の電路、または、前記圧電素子と接地点との間の電路に検出抵抗を配設し、
前記駆動周期中の所定のタイミングで前記検出抵抗の両端の電位差を測定し、
検出した前記電位差を基に前記圧電素子の状態を判定し、
前記所定のタイミングは、前記充電スイッチング素子および前記放電スイッチング素子の動作から僅かに遅れたタイミングであり、
検出した前記電位差が増大したときは、前記圧電素子の容量が増加していると判定し、
前記圧電素子の容量の増加を検出したときは、前記駆動周期を長くすることを特徴とする駆動装置の制御方法。 A piezoelectric element that expands and contracts when a voltage is applied, a vibration member that is fixed at one end to the piezoelectric element, and that can reciprocally move in the axial direction by the expansion and contraction of the piezoelectric element, and frictionally engage with the vibration member, and the vibration A friction engagement member that slides and displaces with respect to the vibration member by a reciprocal displacement of the member; a charge switching element that connects an electrode of the piezoelectric element to a power source at a predetermined drive cycle; and a discharge switching element that grounds the electrode A drive circuit control method comprising: a drive circuit comprising:
A detection resistor is disposed in an electric circuit between the power source and the piezoelectric element, or an electric circuit between the piezoelectric element and a ground point,
Measure the potential difference between both ends of the detection resistor at a predetermined timing during the driving cycle,
Determine the state of the piezoelectric element based on the detected potential difference,
The predetermined timing is a timing slightly delayed from the operation of the charge switching element and the discharge switching element,
When the detected potential difference increases, it is determined that the capacitance of the piezoelectric element has increased,
The drive device control method, wherein when the increase in the capacitance of the piezoelectric element is detected, the drive cycle is lengthened.
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