Drive device and method for linear or rotary positioning

Abstract

The disclosure relates to a drive means for non-resonant linear and/or rotary positioning of an object, comprising at least two piezoelectric or electrostrictive actuator groups, where-in a first actuator group moves a first runner portion relative to a stationary base of the drive means according to the principle of an inertia drive, and by means of the second actuator group a second runner portion is moved relative to the first runner portion with a limited range of movement in the high-resolution scan mode, wherein a common electrical control signal is applied to the first and second actuator groups.

Claims

1. A drive device for non-resonant linear and/or rotary positioning of an object comprising: a base; a first actuator group having at least one piezoelectric or electrostrictive actuator; a second actuator group having at least one piezoelectric or electrostrictive actuator; a runner having a first portion and a second portion, the first portion and the second portion being configured to be movable toward one another in at least one direction of movement, wherein the second portion of the runner is the object to be positioned or is coupled to the object to be positioned; and a controller coupled to the first and second actuator groups, wherein the first actuator group is configured to move the first portion of the runner relative to the base, wherein the second actuator group is configured to move the second portion relative to the first portion of the runner along the at least one direction of movement, wherein one of the first or second actuator groups is configured for a movement in accordance with an inertia drive and the other one of the first or second actuator groups is configured for direct or indirect coupling as a coupling actuator group, and wherein the controller is configured to generate a control signal for the first and second actuator groups, the control signal having at least one inertia drive signal portion comprising sections with different gradients and a semi-static scan signal portion.

2. The drive device according to claim 1, wherein the first actuator group is the one that is configured for movement in accordance with the inertia drive includes a high-pass filter for partial or full suppression of the semi-static scan signal portion.

3. The drive device according to claim 1, comprising a position sensor for determining a position or movement of the second portion of the runner relative to the base.

4. The drive device according to claim 1, comprising a first guide means for guiding the runner relative to the base.

5. The drive device according to claim 4, comprising a second guide means for guiding the second portion of the runner relative to at least one of the first portion of the runner or the base.

6. The drive device according to claim 1, wherein the drive device is equipped with a multi-actuator drive for moving the first portion or the second portion of the runner, wherein the first actuator group is the one configured for movement in accordance with the inertia drive and is part of the multi-actuator drive.

7. The drive device according to claim 1, comprising a lever mechanism for transmitting a stroke of the coupling actuator group.

8. The drive device according to claim 1, wherein the first actuator group is configured for movement of the first portion of the runner relative to the base in accordance with the inertia drive, and wherein the second actuator group couples the second portion of the runner directly or indirectly with the first portion of the runner.

9. The drive device according to claim 1, wherein the second actuator group includes a low-pass filter for partial or full suppression of the at least one inertia drive signal portion.

10. A method for non-resonant linear and/or rotary positioning of an object, the method comprising: moving a first portion of a runner relative to a base using a first actuator group, wherein the first actuator group includes at least one piezoelectric or electrostrictive actuator, moving a second portion of the runner relative to the first portion of the runner along a direction of movement using a second actuator group, wherein the second actuator group includes at least one piezoelectric or electrostrictive actuator, wherein moving the first portion is performed in accordance with an inertia drive and moving the second portion is performed via a direct or indirect coupling, and providing a control signal to the first and second actuator groups, the control signal having at least one inertia drive signal portion comprising sections with different gradients and a semi-static scan signal portion.

11. The method according to claim 10, comprising high-pass filtering of the control signal for the first actuator group which performs the movement in accordance with the inertia drive, for partial or full suppression of the semi-static scan signal portion.

12. The method according to claim 10, comprising low-pass filtering of the control signal for the second actuator group for partial or full suppression of the at least one inertia drive signal portion.

13. The method according to claim 10, comprising determining a position or movement of the second portion of the runner relative to the base.

14. A drive device for non-resonant linear and/or rotary positioning of an object, comprising: a base; a first actuator group having at least one piezoelectric or electrostrictive actuator; and a second actuator group having at least one piezoelectric or electrostrictive actuator; and a runner having a first portion and a second portion, the first portion and the second portion being configured to be movable toward one another in at least one direction of movement, wherein the second portion of the runner is the object to be positioned or is coupled to the object to be positioned; wherein the first and second actuator groups have a control signal connection configured to receive a control signal having at least one inertia drive signal portion comprising sections with different gradients and a semi-static scan signal portion, wherein the first actuator group is configured to move the first portion of the runner relative to the base in response to receiving the control signal, wherein the second actuator group is configured to move the second portion relative to the first portion of the runner along the at least one direction of movement in response to receiving the control signal, and wherein one of the first or second actuator groups is configured for a movement in accordance with an inertia drive and the other one of the first or second actuator groups is configured for direct or indirect coupling as a coupling actuator group.

15. The drive device according to claim 14, wherein the second actuator group includes a low-pass filter for partial or full suppression of the at least one inertia drive signal portion.

16. The drive device according to claim 14, comprising a position sensor for determining a position or movement of the second portion of the runner relative to the base.

17. The drive device according to claim 14, comprising a first guide means for guiding the runner relative to the base.

18. The drive device according to claim 17, comprising a second guide means for guiding the second portion of the runner relative to at least one of the first portion of the runner or the base.

19. The drive device according to claim 14 wherein the drive device is equipped with a multi-actuator drive for moving the first portion or the second portion of the runner, wherein the first actuator group is the one configured for movement in accordance with the inertia drive and is part of the multi-actuator drive.

20. The drive device according to claim 14, comprising a lever mechanism for transmitting a stroke of the coupling actuator group.

21. The drive device according to claim 14, wherein the first actuator group is the one that is configured for movement in accordance with the inertia drive includes a high-pass filter for partial or full suppression of the semi-static scan signal portion.

22. The drive device according to claim 14, wherein the first actuator group is configured for movement of the first portion of the runner relative to the base in accordance with the inertia drive, and wherein the second actuator group couples the second portion of the runner directly or indirectly with the first portion of the runner.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) In the following, the disclosure shall be described in greater detail with reference to preferred embodiments and to the enclosed Figures, in which

(2) FIG. 1 shows a schematic sketch of a prior art inertia drive with typical sawtooth control,

(3) FIG. 2 shows a schematic illustration of a prior art multi-actuator drive,

(4) FIG. 3 shows a schematic view of control signals for a prior art multi-actuator drive and the resulting movement,

(5) FIG. 4 shows a schematic view of a first embodiment of a drive means according to the disclosure,

(6) FIG. 5 shows a schematic view of a second embodiment of a drive means according to the disclosure,

(7) FIG. 6 shows a schematic view of a third embodiment of a drive means according to the disclosure,

(8) FIG. 7 shows a schematic view of a fourth embodiment of a drive means according to the disclosure,

(9) FIG. 8 shows a schematic view of a fifth embodiment of a drive means according to the disclosure,

(10) FIG. 9 shows a schematic view of a sixth, preferred embodiment of a drive means according to the disclosure,

(11) FIG. 10 shows a schematic view of a seventh embodiment of a drive means according to the disclosure, and

(12) FIG. 11 shows a schematic flow diagram of an embodiment of a drive method according to the disclosure.

DETAILED DESCRIPTION

(13) FIG. 1 shows a schematic sketch of a prior art inertia drive with typical sawtooth control.

(14) In a prior art inertia drive, an actuator D is provided to which a periodic, sawtooth-like signal is applied, and which produces an acceleration relative to a displaceably mounted runner E which is frictionally connected to the actuator. Actuator D contracts on the falling edge of the actuator signal, but due to the inertia of runner E, the latter does not follow this retraction of actuator D, thus resulting in a relative displacement between actuator D and runner E.

(15) Multi-actuator drives, so called, can easily be created by using several such drives in parallel with one another.

(16) FIG. 2 shows a schematic illustration of a prior art multi-actuator drive.

(17) A prior art multi-actuator drive has a plurality of actuators. Three actuators 1.sub.1, 1.sub.2, 1.sub.3 are provided in this case, but the multi-actuator drive can basically have any number of actuators, each of which can be excited individually or in groups by means of a control signal to perform a limited stroke (generally up to a few microns in the case of piezo actuators). The actuators each have a point of friction 2.sub.1, 2.sub.2, 2.sub.3 2 which is in frictional contact with a runner 3. Each of the actuators is in constant contact with a base 4.

(18) FIG. 3 shows a schematic view of control signals for a prior art multi-actuator drive as shown in FIG. 2, and the resulting movement. FIG. 3 shows typical voltage curves a, b, c over time for controlling the three actuators, with control based in each case on a time-shifted sawtooth waveform. For the runner, this results in the typical movement d shown in FIG. 3.

(19) FIG. 4 shows a schematic view of a first embodiment of a drive means according to the disclosure.

(20) The drive means (or device) 40 according to the first embodiment comprises a first portion 41a of the runner according to the principle of an inertia drive, and an actuator group 42 which is in frictional contact with the first portion 41a of the runner via a friction surface 43. The friction surface is pressed against the first portion 41a of the runner by a force F. It is advantageous, although not essential, if the first portion of the rotor 41a is guided relative to a stationary base 45, whereby a ball bearing 46 is shown in the figure. A second portion 41b of the runner is in contact with a second actuator group 44 which is in contact at its opposite end with the first portion 41a of the runner. In this embodiment, the second actuator group 44 has a longer stroke than the first actuator group 42, although this is only advantageous, but not essential (the stroke lengths can also be the same, and the stroke of the second actuator group 44 can also be smaller than that of the first actuator group). The second portion 41b of the runner can be moved relative to the first portion 41a of the runner by means of the second actuator group 44, the path travelled being limited to the stroke of the second actuator group 44. Actuator groups 42 and 44 are supplied by control means 47 with a common control signal which is supplied via electrical lines 48 and 49 to actuator groups 42 and 44.

(21) Even though a linear drive device is shown in FIG. 4, the principle can also be used in this way for rotary drive devices.

(22) If there is a plurality of parallel actuator groups or drives in the base, control can also be performed to operate a multi-actuator drive, analogously to the description above (FIG. 2 and FIG. 3).

(23) FIG. 5 shows a schematic view of a second embodiment of a drive means (or device) 50 according to the disclosure. This embodiment is almost identical to the first embodiment, with the difference that the second portion 41b of the runner is guided relative to the first portion 41a of the runner. In FIG. 5 this guide means (or system) 51 is shown as a rolling bearing. This has the advantage that external forces F.sub.ext acting on the second portion 41b of the runner do not exert a load on the second actuator group 44, as these forces are absorbed by guide means 51.

(24) FIG. 6 shows a schematic view of a third embodiment of a drive means (or device) 60 according to the disclosure. This embodiment is again almost identical to the second embodiment, with the difference that the guide means is provided in the form of a flexure joint 61 between the first portion 41a of the runner and the second portion 41b of the runner. This has the advantage that the motion of actuator group 44 can be transferred undisturbed to the second part 41b of the runner, which means that particularly high-resolution movement can be achieved. If solid bodies are used, it is particularly easy to provide the first and second portions of the runner (41a and 41b) in one piece, which simplifies production.

(25) FIG. 7 shows a schematic view of a fourth embodiment of a drive means (or device) 70 according to the disclosure. This embodiment is again almost identical to the third embodiment, with the difference that a sensor 71 which can measure the movement of the second portion 41b of the runner, for example by reading a ruler 72, is integrated into base 45. Depending on the kind of sensor that is used, an additional medium for detecting the position, such as ruler 72, may not be necessary. For example, an interferometer may be able to detect directly the positional displacement of the second portion of the runner.

(26) It should be noted that the fourth embodiment can also be modified, in relation to the third embodiment, according to the first or second embodiment.

(27) FIG. 8 shows a schematic view of a fifth embodiment of a drive means 80 according to the disclosure. This embodiment is almost identical to the first embodiment, with the difference that the second portion 41b of the runner is mounted relative to base 45, the guide means 71 being shown in FIG. 8 in the form of a rolling bearing, although of course any other known kind of guide means may be used. If the second portion 41b of the runner is guided by a bearing 71, then the first portion 41a of the runner does not necessarily have to be mounted relative to base 45 as well, as shown by the roller guide 46 means in FIG. 8.

(28) FIG. 9 shows a schematic view of a sixth, preferred embodiment of a drive means (or device) 90 according to the disclosure. This embodiment has similarities with the fourth embodiment, with the difference that a low-pass filter 91 and a high-pass filter 92 are provided in the electrical lines 48, 49 to actuator groups 42, 44. The effect of the high-pass filter 92 in line 48 leading to the first actuator group 42 is that slowly changing voltage levels outputted by control means (or controller) 47 do not or do not completely reach the first actuator group 42, so this actuator group does not perform a respective movement and therefore does not entrain the first portion 41a of the runner, either, when there are slowly varying signals. However, fast-changing signals are passed to the first actuator group 42, so this actuator group can drive the runner (41a+41b) according to the principle of an inertia drive, high-pass filter 92 being set in such a way that the slow edges of the sawtooth voltage signal preferably being used are not filtered out. The effect of the low-pass filter 91 in line 49 to the second actuator group 44 is that fast-changing signals do not pass through to actuator group 44. Thus, the steep edges of the sawtooth voltage signal preferably being used, which are used for macroscopic movement of the first portion 41a of the runner 41a, do not reach the second actuator group 44. With an advantageously adjusted low-pass filter 91, actuator group 44 is not reached by the slow edges of the sawtooth signal, either, but only by voltages that change even more slowly. A corresponding drive means 90 can operate macroscopically according to the principle of an inertia drive when the driver is supplied with a sawtooth voltage, and it has a very large fine positioning range (scanning range) when the changes in voltage are correspondingly slow. It is not necessary to use both high- and low-pass filters. For example, a suitable drive means is already very usable when only the low-pass filter 91 is used. In that case, actuator group 42 supports the fine positioning range of actuator group 44. This can be advantageous, but can also have disadvantages, for example if guide means 46 introduces interference.

(29) It is clear that the above statements concerning the high-pass filter and/or the low-pass filter can also be applied accordingly to the other embodiments if the respective elements are likewise provided there.

(30) FIG. 10 shows a schematic view of a seventh embodiment of a drive means (or device) 100 according to the disclosure. This embodiment is almost identical to the sixth embodiment, but the stroke of the second actuator group 44 is transferred in enlarged form to the second portion 41b of the runner via a lever device 101. This can be advantageous, especially when a large fine positioning range is needed, but the entire drive means is to be built small, with the result that a large actuator group 44 cannot be integrated into drive means 100.

(31) FIG. 11 shows a schematic flow diagram of an embodiment of a drive method according to the disclosure.

(32) The non-resonant drive method 1000 comprises the steps of:

(33) arranging 1100, in a stationary base, a first piezoelectric or electrostrictive actuator group having a friction surface;

(34) pressing 1200 the friction surface against a surface on a first portion of the runner, such that said surfaces are in friction contact and such that the first portion of a runner can be driven according to the principle of an inertia drive or a multi-actuator drive by controlling the first actuator group with at least one sawtooth voltage waveform;

(35) arranging 1300 a second actuator group in the first portion of the runner;

(36) connecting 1400 the actuator group with the first and a second portion of the runner which is movable relative to the first portion, such that the two portions can be moved in a targeted manner relative to each other when the second actuator group is deflected;

(37) connecting 1500 a common control signal from a control means with the first and second actuator group;

(38) generating 1900 a continuous sawtooth voltage waveform, or some other signal waveform having alternating flat and steep edges, by means of the control means, in order to move the runner macroscopically according to the principle of an inertia drive until the desired distance has been moved and it is possible to switch to the fine positioning mode; and

(39) generating 2000 a slowly changing voltage so as to move the second portion of the runner relative to the first portion of the runner with high resolution in the fine positioning mode in order to reach a setpoint position, then switching to the inertia drive mode when the setpoint position is outside the fine positioning range available.

(40) Connecting 1500 the common control signal can be followed by various alternatives preceding generation 1900, namely

(41) introducing 1600 a high-pass filter between the control means and the first actuator group, or

(42) introducing 1700 a low-pass filter between the control means and the second actuator group, or

(43) introducing 1600 a high-pass filter between the control means and the first actuator group and introducing 1700 a low-pass filter between the control means and the second actuator group, or

(44) not introducing 1800 a high-pass or low-pass filter

(45) Even if the embodiments discussed above each relate to a linear movement of the object to be driven, the disclosure is not limited to such a linear movement, and rotary movement as well as composite movements and positionings are likewise possible. In the case of rotary movement or positioning, the friction surface is moved tangentially instead of parallel.

(46) It is preferred that the pressing force F is determined by an adjusting spring structure. It is possible that the effective direction of the springs being used is deflected by a mechanical structure.

(47) It is also possible for a plurality of actuators to be used in parallel, so the actuators can be controlled in such a way that a surface to be driven can also be controlled according to the principle of the multi-actuator drive.

(48) In the embodiments, the present disclosure has been described in such a way that the drive device as such is stationary, whereas the object to be moved is moved relative to the base and therefore in absolute terms also. However, it should be understood that the movement between the base and the object is to be understood primarily as the relative movement between these elements. It is also possible that the movement between the object and the base is manifested as an absolute movement of the drive means, in which case the object then remains stationary in absolute terms. It is also possible that the relative movement results in a respective absolute movement of both the base and the object (in opposite directions).

(49) Even if different aspects or features of the disclosure are shown in combination in the Figures, it is clear to a person skilled in the art, unless otherwise specified, that the combinations shown and discussed are not the only ones possible. More particularly, it is possible to swap corresponding units or groups of features from different embodiments.

(50) According to one embodiment of the present disclosure, a drive means for non-resonant linear and/or rotary positioning of an object is provided, comprising at least two piezoelectric or electrostrictive actuator groups each consisting of at least one actuator, wherein a first actuator group moves a first runner relative to a stationary base of the drive means according to the principle of an inertia drive, by alternatingly bringing friction surfaces that are pressed together into static and sliding friction by means of this actuator group, and wherein a second portion of the runner is moved relative to the first runner portion driven by the first actuator group with a limited range of movement in the fine positioning mode (scan mode) by means of the second actuator group, wherein the first and second actuator groups are supplied with a common electrical control signal, with which the movement of the runner according to the principle of an inertia drive is produced by means of the first actuator group as soon as the control signal has an appropriate sawtooth voltage with flat and steep edges, the steep edge of which accelerates the actuator so strongly that slipping of the friction surfaces in contact with each other occurs, and wherein the control signal has a semi-static or slowly varying voltage during the period in which no sawtooth curve is applied, in order to move at least one actuator group without any slipping of a friction surface occurring.

(51) In particular, an electrical low-pass filter may be provided before or after the second actuator group, for example in the form of an electrical resistance, so that fast-changing signal variations do not reach or only partially reach the second actuator group.

(52) Additionally or alternatively, an electrical high-pass filter may also be provided for the first actuator group, so that slowly changing signal variations do not reach or only partially reach the first actuator group.

(53) The movement of the second portion of the runner relative to the stationary base may be detected by means of a position sensor, which can be either a sensor integrated into the drive means, for example an optical, inductive, magnetic or capacitive encoder or interferometer, or an external sensor such as a laser interferometer.

(54) The runner may be guided relative to the stationary base of the drive means by a guide means, for example a sliding bearing, a rolling bearing, a magnetic bearing, an air bearing or a flexure joint.

(55) The second portion of the runner, which is moved relative to the first portion of the runner by means of the second actuator group, may be guided relative to the first portion of the runner, whereby the guide means can take the form of a flexure joint, an air bearing, a magnetic bearing, a rolling bearing or a sliding bearing, for example.

(56) The second portion of the runner, which is moved relative to the first portion of the runner by the second actuator group, may be guided relative to the stationary base of the drive means, whereby the guide means can take the form of a flexure joint, an air bearing, a magnetic bearing, a rolling bearing or a sliding bearing, for example.

(57) The runner may be driven by a multi-actuator drive, and at least one of the actuator groups of the multi-actuator drive may be supplied with a control signal shared with the second actuator group.

(58) The stroke of the second actuator group may be transferred via a lever such that a movement larger than the stroke of the second actuator group is transferred to the second portion of the runner.

(59) The second actuator group may be arranged in the stationary base of the drive means, and the first actuator group inside the runner, the components of which are moved relative to each other according to the principle of an inertia drive or a multi-actuator drive.

(60) According to one embodiment of the present disclosure, a method for non-resonant linear and/or rotary positioning of an object comprises the steps of arranging, in a stationary base, a first piezoelectric or electrostrictive actuator group having a friction surface, and pressing the friction surface against a surface on a first portion of the runner such that said surfaces are in friction contact and such that the first portion of a runner can be driven according to the principle of an inertia drive or a multi-actuator drive by controlling the first actuator group with at least one sawtooth voltage waveform; arranging a second actuator group in the first portion of the runner and connecting the actuator group to the first and a second portion of the runner which is movable relative to the first portion, such that the two portions can be moved in a targeted manner relative to each other when the second actuator group is deflected; connecting a common control signal from a control means with the first and second actuator group; optionally introducing a high-pass filter between the control means and the first actuator group and optionally introducing a low-pass filter between the control means and the second actuator group; generating a sawtooth voltage waveform, or some other signal waveform having alternating steep and flat edges, by means of the control means, in order to move the runner macroscopically according to the principle of an inertia drive, and generating a slowly changing voltage so as to move the second portion of the runner relative to the first portion of the runner with high resolution in the fine positioning mode.