JP2005341675A - Electret driver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electret driver, in which controllability of driving direction of a mover and controllability of the mover at the time of stopping can be enhanced. <P>SOLUTION: A pair of second electret portions 5c are provided on two end faces of a mover 2 along the driving direction, and second electrodes 4a and 4b are provided in the vicinity of the second electret portion 5c on the stator 1 side. Repulsion is generated between the second electret portion 5c and the second electrodes 4a and 4b at the time of driving the mover 2. At stopping of the mover 2, attraction is generated between the second electret portion 5c and the second electrode 4a, and repulsion is generated between the second electret portion 5c and the second electrodes 4b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electret driving device that drives a moving element using an electret.

  Conventionally, proposals for electrostatic actuators have been made. For example, in Patent Document 1, charges are induced in a movable element composed of a thin film by a voltage applied to a plurality of strip-shaped electrodes, and induced in the movable element. There has been proposed an electrostatic actuator that electrostatically drives a moving element using an electrostatic force between the charged electric charge and the electric charge of the electrode.

Also, among the electrostatic actuators, as proposed in Patent Document 2, the mover is composed of an electret film that has been pre-charged, and the mover is mounted using the electric charge held on the electret film. An electret drive device for driving has also been proposed. In the electret driving device using such an electret film, it is not necessary to induce charges when driving the moving element, and driving at a lower voltage is possible as compared with the electrostatic actuator of Patent Document 1.
Japanese Patent Laid-Open No. 8-220592 Japanese Patent Laid-Open No. 4-112683

  In such an electret driving device, it is conceivable that the moving element is sealed so that dust or the like does not enter the apparatus. In such a case, the driving is performed when the moving element is driven. When the direction is deviated from the desired driving direction, there is a possibility that the driving speed of the moving element is lowered by receiving a frictional force from the wall surface existing in the deviated direction.

  In addition, when control is performed to stop the moving element from a state where the moving element is driven at a high speed, if the moving element is stopped only by the suction force between the electrode and the moving element, the desired effect is obtained due to the influence of inertia or the like. There is also a possibility of stopping at a position slightly deviated from the stop position.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an electret driving device capable of improving the controllability in the driving direction of the moving element and the controllability when the moving element is stopped.

  In order to achieve the above object, an electret driving device according to a first aspect of the present invention includes a plurality of first electret portions formed along a driving direction and two end face portions along the driving direction. A movable body having at least one pair of second electret sites formed on the first electrode, a first electrode arranged to face the first electret sites, and the vicinity of each of the two end surface portions And a stator having at least one pair of second electrodes disposed on the substrate.

  According to the first aspect, in addition to the first electret site and the first electrode for driving the mover, the second electret site and the second electrode are provided. It is possible to improve the controllability in the driving direction and the controllability when the moving element is stopped.

  ADVANTAGE OF THE INVENTION According to this invention, the electret drive device which can improve the controllability of the drive direction of a slider and the controllability at the time of a stop of a slider can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the drive principle of the electret drive device using the electret will be described.

  The electret drive device basically includes a stator 1 and a mover 2, and the mover 2 is configured to be movable in the left-right direction in FIGS. 1A and 1B with respect to the stator 1. ing. Further, a plurality of strip-like first electrodes (drive electrodes) 4 extending in parallel with each other at a predetermined interval are arranged on the stator 1 in a direction perpendicular to the moving direction of the moving element 2. ing.

  The movable element 2 includes a plurality of sites of a derivative (first electretization site) that are permanently polarized and arranged in parallel to the extended first electrode 4.

  In such a configuration, when a frequency voltage is applied to the first electrode 4, an attractive force or a repulsive force is generated between the first electrode 4 and the above-described first electret portion, and as a result, the moving element 2 moves relative to the stator 1.

  FIG. 2 is a diagram schematically showing a cross section of such an electret driving device and a driving circuit for the electrostatic actuator.

  In the electret driving device, voltage signal lines from the driving circuit 10 are connected to the first electrodes 4 arranged in parallel to the stator 1. A four-phase voltage signal is applied to these voltage signal lines. Therefore, the same voltage signal is applied to the first electrode 4 every four lines. In FIG. 2, the voltage signals are distinguished by attaching the symbols A, B, C, and D to the first electrode 4.

  In addition, this figure is a schematic diagram to the last, and the actual number of first electrodes and first electret sites and the arrangement interval are the size of the device, the area of the opening, and the polarity of the first electret site. These are determined as appropriate according to various factors such as the arrangement, the drive resolution required for the electret drive device, and the drive speed. Moreover, in the case of this electret drive device, although the 1st electret part which has a positive / negative polarity is a type arrange | positioned alternately, either polarity may be abbreviate | omitted.

  The left side of FIG. 2 shows the configuration of the drive circuit 10 for generating a voltage signal to be applied to the electret drive device in addition to the configuration of the electret drive device described above.

  The rectangular wave train (drive pulse signal) generated by the pulse generation circuit 12 is supplied to the booster circuit 14 and the phase shifter 15. In the booster circuit 14, the input rectangular wave train is boosted to about 100 V, is branched into voltage signals having two polarities, and is supplied to the first electrodes 4 A and 4 C. On the other hand, the rectangular wave train input to the phase shifter 15 has a waveform delayed by 90 °, and is then input to the booster circuit 14 to form two rectangular wave trains similar to those described above, and the first electrode 4B and Supplied to 4D.

  FIG. 3 is a timing chart showing an example of a voltage signal sequence created by the drive circuit 10 and applied to the first electrodes 4A to 4D. 3A shows the first electrode 4A, FIG. 3B shows the first electrode 4B, FIG. 3C shows the first electrode 4C, and FIG. 3D shows the first electrode 4D. It is a timing chart.

  The voltage states of the first electrodes 4A to 4D are such that the four states from time t1 to time t4 change repeatedly as time elapses.

  4A to 4D are diagrams for explaining the operation of the electret driving device described above. 4A to 4D, the right side direction in FIG. 4 is the traveling direction of the moving element 2, and the first electret portion 5a of the positive electrode (plus) on the rear side (left side) and the front side (right side). It is assumed that negative electrode (minus) first electret sites 5b are arranged.

  FIG. 4A shows the voltage state (polarity) of the first electret site and the first electrode 4 immediately after switching to the time t1 shown in FIG.

  In this state, the first electret portion 5a of the positive electrode receives a repulsive force from the first electrode 4A (positive electrode) and receives an attractive force from the first electrode 4B (negative electrode). Further, the first electret portion 5b of the negative electrode receives a repulsive force from the first electrode 4C (negative electrode) and receives an attractive force from the first electrode 4D (positive electrode). Therefore, the mover 2 receives a force in the right direction in FIG. 4A and moves to the right by one electrode pitch d.

  FIG. 4B shows the voltage state of the first electret site and the first electrode immediately after switching at time t2.

  In this state, the first electret site 5a receives a repulsive force from the first electrode 4B (positive electrode) and receives an attractive force from the first electrode 4C (negative electrode). The first electret site 5b receives a repulsive force from the first electrode 4D (negative electrode) and receives an attractive force from the other first electrode 4A (positive electrode). For this reason, the movable element 2 receives a force in the right direction in FIG. 4B and moves by one electrode pitch d.

  Similarly, FIG. 4C shows a voltage state of the first electret site and the first electrode immediately after switching at time t3.

  In this state, the first electret site 5a receives a repulsive force from the first electrode 4C (positive electrode) and receives an attractive force from the first electrode 4D (negative electrode). The first electretized portion 5b receives a repulsive force from the first electrode 4A (negative electrode) and receives an attractive force from the first electrode 4B (positive electrode). For this reason, the moving element 2 receives a force in the right direction of FIG. 4C and moves by one electrode pitch d.

  Further, FIG. 4D shows the voltage state of the first electret site and the first electrode immediately after switching at time t4.

  In this state, the first electret site 5a receives a repulsive force from the first electrode 4D (positive electrode) and receives an attractive force from the first electrode 4A (negative electrode). The first electret site 5b receives a repulsive force from the first electrode 4A (negative electrode) and receives an attractive force from the first electrode 4C (positive electrode). Therefore, the mover 2 receives a force in the right direction in FIG. 4D and moves by one electrode pitch d.

  As described above, the mover 2 moves by one electrode pitch d, and this operation is repeated, so that the mover 2 moves to the right as shown in FIG. 4 (a) → (b) → (c) → (d). Move in the direction (arrow F direction in the figure). In order to move the movable element 2 in the left direction in the figure, the polarity of the voltage applied to the first electrode 4 may be switched in the reverse order.

  Further, as shown in FIG. 5, a support member 1a is attached to the stator 1 of the electret drive device, and a protective member 1b is further attached via the support member 1a. Here, although the support member 1a is attached to the periphery of the stator 1, the illustration of the support members 1a on the front side and the back side of the drawing is omitted in FIG. As described above, the mover 2 of the electret driving device is sealed by the stator 1, the support member 1a, and the protective member 1b, and has a structure that prevents dust from entering the device. ing. In the electret driving device having such a structure in which the moving element 2 is sealed, if the driving direction of the moving element 2 is deviated, the moving element 2 and the support member 1a come into contact with each other. It is conceivable that the driving speed of the moving element 2 is lowered.

  FIG. 6 is a diagram illustrating a configuration of an electret driving device according to an embodiment of the present invention. Here, FIG. 6 is illustrated with the protective member 1b omitted. In the present embodiment, as shown in FIG. 6, in addition to the first electret portion for driving the moving element 2, a pair of second surfaces are provided on two end surface portions along the driving direction of the moving element 2. The electret portion 5c is formed. Further, second electrodes 4a and 4b corresponding to the pair of second electret portions 5c are provided on the support member 1a. The second electrodes 4a and 4b are provided so as to face the side end surfaces of the movable element 2, respectively.

  FIG. 7 is a view of the electret drive device of FIG. 6 as viewed from the drive direction (traveling direction) side of the movable body 2. By adopting the configuration as shown in FIG. 7, the movable element 2 receives electrostatic force from both the first electrode 4 and the second electrodes 4a and 4b.

FIG. 8 is a diagram showing a drive circuit of the electret drive device of FIGS. 6 and 7. Here, the description of the same configuration as in FIG. 2 is omitted.
In FIG. 8, the rectangular wave train generated by the pulse generation circuit 12 is supplied to a booster circuit 14b made of an inductance. In the booster circuit 14b, the input rectangular wave train is boosted to about 100 V, and further branched to a voltage having two positive and negative polarities. Further, a diode is connected in series to each of the positive output and the negative output of the booster circuit 14b shown in FIG. 8, and a smoothing capacitor is further connected in parallel. Furthermore, a switching circuit 14c made of a photorelay is provided between the second electrode 4a and the positive output of the booster circuit 14b.

  In such a circuit configuration, when the switch of the switching circuit 14c is on the solid line side in the figure, after the rectangular AC voltage is output from the negative output of the booster circuit 14b, the positive component of the AC voltage is removed by the diode. Is done. Further, the output voltage from the diode is smoothed by the smoothing capacitor and supplied to each of the second electrodes 4a and 4b as a substantially constant negative voltage. On the other hand, when the switch of the switching circuit 14c is on the broken line side in the figure, a rectangular AC voltage is output from the positive output of the booster circuit 14b, and then the negative component of the AC voltage is removed in the diode. Further, the output voltage from the diode is smoothed by the smoothing capacitor, and is supplied to the second electrode 4a as a substantially constant positive voltage.

  Here, the switching control of the switch in the switching circuit 14c is performed in the control unit 100 constituted by the CPU. That is, from the start of driving of the moving element 2 to immediately before stopping, the control unit 100 switches the switch of the switching circuit 14c to the solid line side in FIG. 8 and applies a substantially constant negative voltage to each of the second electrodes 4a and 4b. To be supplied. On the other hand, when the moving element 2 is stopped, the control unit 100 switches the switch of the switching circuit 14c to the broken line side in FIG. 8 so that a substantially constant positive voltage is supplied only to the second electrode 4a. In the control unit 100, operation control of the pulse generation circuit 12 is also performed.

FIG. 9 is a flowchart showing processing from the start of driving of the moving element 2 to the stop of driving.
At the start of driving of the mover 2, the control unit 100 sends an instruction to the pulse generation circuit 12 and the switching circuit 14c so as to apply the first predetermined voltage to the second electrodes 4a and 4b (step S1). . The first predetermined voltage in step S1 is a voltage at which a repulsive force is generated between the second electret site and the second electrode. For example, when the second electret site 5c is negatively charged, the switch of the switching circuit 14c is switched to the solid line side in FIG. As a result, electrostatic forces such as arrows F1 and F2 in FIG. 10 act on the moving element 2, so that the driving direction of the moving element 2 is stabilized.

  FIG. 10 shows an example in which the second electret site 5c is negatively charged. When the second electret site 5c is positively charged, the second electrode 4a, Needless to say, a positive voltage is applied to each of 4b.

  After the process of step S1, in order to drive the movable body 2, the control unit 100 sends an instruction to the pulse generation circuit 12 so as to apply a voltage to the first electrode 4 (step S2). Since the process of step S2 has been described with reference to FIGS. 1 to 4, the description thereof is omitted here.

  After the process of step S2, the control unit 100 determines whether or not the driving of the mover 2 is finished (step S3), and continues the determination of step S2 until it is determined that the driving of the mover 2 is finished.

  On the other hand, in step S3, when the driving of the moving element 2 is finished, the control unit 100 applies the second predetermined voltage to the second electrodes 4a and 4b, and the pulse generation circuit 12 and the switching circuit 14c. An instruction is sent to (step S4). The second predetermined voltage in step S4 is a voltage at which an attractive force is generated between any one of the second electret sites and the second electrode corresponding to the second electret site. It is. For example, when the second electret site 5c is charged to the negative side, the switch of the switching circuit 14c is switched to the broken line side in FIG. As a result, electrostatic forces such as arrows F3 and F4 in FIG. 11A act on the movable element 2, so that the movable element 2 is attracted to the second electrode 4a as shown in FIG. 2 stops. That is, a frictional force is generated between the movable element 2 and the second electrode 4a by this adsorption, and the kinetic energy due to the inertial force of the movable element 2 is consumed by this frictional force, and the movement of the movable element 2 is stopped. Let

  FIG. 11A and FIG. 11B are examples when the second electret site is negatively charged, and when the second electret site is positively charged. Needless to say, the polarities of the second electrodes 4a and 4b are reversed. Further, in the example of FIG. 11A, a positive voltage is applied to the second electrode 4a and a negative voltage is applied to the second electrode 4b so that the movable element 2 is attracted to the second electrode 4a side. However, the polarity of the voltage may be reversed so that the movable element 2 is attracted to the second electrode 4b side.

  As described above, according to the present embodiment, by providing the second electret portion on the movable element 2 and providing the second electrode on the stator side, the controllability in the driving direction of the movable element and Controllability when the mover is stopped can be improved.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above-described embodiments, and various modifications and applications are naturally possible within the scope of the gist of the present invention. For example, in the above-described embodiment, one pair of the second electret site and the second electrode are provided, but two or more pairs may be provided. Moreover, if an electrostatic force generate | occur | produces between a 2nd electret site | part and a 2nd electrode, it is not necessary to arrange | position both facing each other. That is, it is only necessary that the second electrode be disposed in the vicinity of the second electretization site.

  Further, the above-described embodiments include various stages of the invention, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be extracted as an invention.

It is a figure explaining the drive principle of the electret drive device which concerns on this invention. It is the figure which showed the drive circuit of this electret drive device while showing the cross section of an electret drive device typically. FIG. 4A shows an example of a voltage signal train created by the drive circuit of FIG. 2 and applied to the first electrode. FIG. 4A shows the first electrode 4A, and FIG. 4B shows the first electrode. The electrode 4B, FIG. 4C is a timing chart of the first electrode 4C, and FIG. 4D is a timing chart of the first electrode 4D. It is a figure explaining operation | movement of the electret drive device shown by FIG. It is a figure for demonstrating the sealing structure of a needle | mover and a stator. It is a figure shown about the structure of the electret drive device which concerns on one Embodiment of this invention. It is a figure when the electret drive device of FIG. 6 is seen from the drive direction side. It is the figure which showed the drive circuit of the electret drive device which concerns on one Embodiment of this invention. It is a flowchart shown about the process from the drive start of a needle | mover to a drive stop. It is a figure for demonstrating the 1st predetermined voltage. It is a figure for demonstrating the 2nd predetermined voltage.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Stator, 1a ... Support member, 1b ... Protection member, 2 ... Mover, 4, 4A-4D ... 1st electrode, 4a. 4b ... second electrode, 5a, 5b ... first electret part, 5c ... second electret part, 10 ... drive circuit, 12 ... pulse generation circuit, 14,14b ... boost circuit, 14c ... switching circuit, 15 ... Phaser, 100 ... Control part

Claims (3)

A mover having a plurality of first electret sites formed along the drive direction, and at least one pair of second electret sites formed on two end face portions along the drive direction;
A stator having a first electrode arranged so as to face the first electretization site, and at least one pair of second electrodes arranged in the vicinity of each of the two end face portions;
An electret driving device comprising:   A voltage is applied to the first electrode of the movable element to drive the movable element, and the at least one pair of second electret portions and the second electrode corresponding to the second electret portions, respectively. 2. The electret driving device according to claim 1, further comprising control means for applying a voltage to the second electrode so that a repulsive force is generated between the first electrode and the second electrode.   At the end of driving of the moving element, the control means draws an attractive force between one of the at least one pair of second electret sites and the second electrode corresponding to the second electret sites. The electret driving device according to claim 2, further comprising applying a voltage to the second electrode so as to generate a voltage.

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