JP4476080B2 - Variable focus optical device - Google Patents

Description

  The present invention relates to a variable focus optical device capable of changing a focal length of an optical means fixed to a movable part movably supported by a fixed part via a beam part.

  Conventionally, as an optical device that performs optical scanning, for example, semiconductor manufacturing, by providing an optical means in a movable part that is movably supported by a fixed part via a beam part, and moving the optical means through the movable part There are planar optical devices manufactured using technology, and there are a light reflection type using a reflection mirror as an optical means and a light transmission type using a lens as an optical means.

  As an example of the light reflection type, for example, a movable part is pivotally supported on a fixed part via a beam part, a driving coil provided on the movable part, and a static magnetic field that applies a static magnetic field to the driving coil. The driving means of the movable part is constituted by the generating means, and the movable part is rotated around the beam part by utilizing the Lorentz force generated by the interaction between the magnetic field generated in the driving coil by energization and the static magnetic field. In some cases, the reflection mirror is rotated to deflect the light beam (see, for example, Patent Document 1).

As an example of the light transmission type, for example, the movable part is supported by an H-shaped beam part, the beam part is a movable electrode, a fixed electrode is arranged around the beam part, and the beam part (movable electrode) is fixed. There is an apparatus that deflects a light beam transmitted through a lens by using a refractive action of the lens by generating an electrostatic attraction between the electrode and displacing the lens via a movable part (for example, non-patent document). 1).
Japanese Patent No. 2722314 Norihiko Saruta, Hiroyuki Fujita, Hiroshi Toshiyoshi "Manufacture of microlens optical scanners using SOI substrates" IEEJ Transactions, 2003, Vol. 123, No. 7, pp. 231-236

  By the way, in an optical apparatus such as an optical scanner or an optical disk device, it is necessary to adjust the focal position of the light beam reflected or refracted by the optical means to the predetermined position by adjusting in the optical axis direction. However, none of the conventional optical devices of this type can change the focal length (curvature radius) of the reflecting mirror or the lens. For this reason, when this type of optical device is mounted on an optical device such as an optical scanner or an optical disk device, conventionally, a collimator lens and a condenser lens are provided in the optical path of the light beam so that the focal position of the light beam is an appropriate position. Alternatively, it is necessary to provide an optical component such as an f-θ lens.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a variable focus optical device that can adjust the focal position of a light beam from an optical means without providing an optical component.

For this reason, the variable focus optical device according to the first aspect of the present invention is fixed to the movable portion, a movable portion that is movably supported by the fixed portion via the beam portion, driving means for driving the movable portion, and the movable portion. A drive coil comprising optical means for refracting or reflecting an incident light beam and control means for variably controlling the focal length of the optical means , wherein the drive means is laid on the movable part and generates a magnetic field by energization And a static magnetic field generating means for applying a static magnetic field to a drive coil portion located on the opposite side of the movable portion parallel to the axial direction of the beam portion, and generated on the drive coil portion located on the opposite side of the movable portion. The electromagnetic force acts on the opposite side of the movable part by the interaction between the magnetic field and the static magnetic field, and the control means superimposes the movable part driving current on the movable part heating current to the driving coil. Supply and drive the drive coil. Heating controlling the movable section as a data, characterized in that the radius of curvature of the optical means to control the deformation amount of the optical means is deformed together with the movable unit configured to variably control.
In such a configuration, the movable part driving current is supplied to the drive coil to move the movable part relative to the fixed part to drive the optical means, while the control means superimposes the movable part drive current on the drive coil. Thus, the focal length of the optical means can be varied by supplying and controlling the current for heating the movable part and controlling the heating of the movable part .

In the invention of claim 2 , a shape memory metal is provided on the movable part, and the shape memory metal is heated .

According to a third aspect of the present invention, the control means inputs the target value of the focal length and the current value for heating the movable portion as deformation control amount data of the optical means corresponding to each focal length of the optical means. A configuration including a storage unit that stores data in advance, and a control unit that determines a current value for heating the movable unit corresponding to the target value input based on the storage data of the storage unit and controls the deformation of the optical means. did.

In this case, as in claim 4 , there is provided detection means for detecting an actual focal length of the optical means, and the control unit compares the detection value of the detection means with the target value, and the detection value is The movable part heating current value may be feedback controlled so as to coincide with the target value.

  As described above, according to the variable focus optical device of the present invention, since the focal length can be varied by variably controlling the radius of curvature of the optical means, the focal position of the light beam when mounted on an optical device, for example. Can be adjusted by the optical device itself so as to be in a predetermined position, and there is no need to separately provide a focus position adjusting lens or the like. Therefore, it is possible to reduce the number of parts of the optical device and simplify the configuration, and to increase the degree of design freedom.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a configuration diagram of a first embodiment of a variable focus optical device according to the present invention, and FIG. 2 shows a plan view of an optical scanning unit which is a main part of the first embodiment.
In FIG. 1, the variable focus optical device of this embodiment includes a light emitting unit 1, a light emission control unit 2, an optical scanning unit 3, an input unit 4, a drive control unit 5, and a data storage unit 6. It is prepared for.

The light emitting unit 1 emits a light beam to the optical scanning unit 3, and may be any light source as long as it can emit light, such as a laser light source that emits laser light.
The light emission control unit 2 drives and controls the light emitting unit 1 and controls the light emission timing of the light emitting unit 1 in accordance with the scanning angle of the optical scanning unit 3 described later. Specifically, for example, the light emission control unit 2 includes a memory that stores correspondence data between a later-described movable unit drive current value transmitted from the drive control unit 5 and a scanning angle of the movable unit 13, and the movable unit that has been input The scanning angle of the movable unit 13 is read from the memory from the drive current value, and a light emission command is transmitted to the light emitting unit 1 at a predetermined interval within a preset scanning angle range.

  The optical scanning unit 3 scans the light beam emitted from the light emitting unit 1 and uses, for example, a planar actuator manufactured by applying semiconductor micromachine technology. FIG. 2 is a plan view of the optical scanning unit 3 according to this embodiment.

In FIG. 2, in the optical scanning unit 3 of the present embodiment, a movable unit 13 is pivotally supported by a frame-shaped fixed unit 11 via a pair of torsion bars 12 and 12 as beam units. The fixed portion 11, the torsion bars 12, 12 and the movable portion 13 are integrally formed by etching a silicon substrate, for example. On the surface of the movable portion 13, an optical means 14 is provided at the center thereof, and the movable portion 13 is variably controlled by controlling the amount of deformation of the optical means 14 so as to surround the optical means 14 at the peripheral portion. A drive coil 15 also serving as a heater for heating is provided. The drive coil 15 is drawn out to the fixing unit 11 side via the torsion bar portion electrode terminal 16A, the heating current and the drive current and connected Ru is supplied to 16B. Also, on the outer side of the fixed portion 11, a pair of static magnetic field generating means 17A which acts a static magnetic field in a direction parallel to the axial drive coil portion of the movable portion opposite sides of the torsion bars 12, 12, 17B is, the movable portion 13 It is arranged with the opposite magnetic poles facing each other. The static magnetic field generating means 17A and 17B may be permanent magnets or electromagnets.

  Here, the optical unit 14 may be a reflection mirror that reflects the light beam emitted from the light emitting unit 1 or a lens that transmits and refracts the light beam. In the case of a reflection mirror, aluminum, gold, or the like is deposited on the movable portion 13 to form. In the case of a lens, a separately processed lens may be attached to the movable portion 13 by forming a through hole. The transparent resin is dropped on the movable portion 13 and formed on the movable portion 13 by surface tension. You may do it. As the lens material, a material that can be deformed by heat or external pressure, such as a polymer material or silicon, is used. When a lens is used as the optical means 14, the light emitting portion 1 is disposed on the side opposite to the light beam scanning side, so that a light beam passing through hole is usually provided in the lens mounting portion of the movable portion 13. However, when the movable portion 13 is made of a material that can transmit a light beam, it is not necessary to provide a through hole.

The driving principle of the optical scanning unit 3 is described in detail in, for example, Japanese Patent No. 2722314, and will be briefly described here.
When a current is passed through the drive coil 15 on the movable portion 13, a magnetic field is generated, and a Lorentz force is generated by the interaction between this magnetic field and the static magnetic field generated by the static magnetic field generating means 17A, 17B, and the axial direction of the torsion bars 12, 12 Rotating forces in opposite directions are generated on the opposite sides of the movable part parallel to the movable part 13, and the movable part 13 rotates to a position where the spring force of the torsion bars 12, 12 and the generated rotational force are balanced. When an alternating current is passed through the drive coil 15, the optical means 14 swings through the movable part 13, and the light beam emitted from the light emitting part 1 can be scanned. Since the generated rotational force is proportional to the current value flowing through the drive coil 15, the swing angle (light beam scanning angle) of the movable portion 13 can be controlled by controlling the current value of the drive coil 15. Here, a drive means is comprised by the drive coil 15 and the static magnetic field generation means 17A, 17B.

  The input unit 4 inputs a target value of the focal length of the optical means 14, and manually inputs the target value when the distance to the irradiation target of the light beam does not change at a fixed value. A keyboard or the like can be used. If the distance to the object irradiated with the light beam changes constantly, the detected value may be input as a target value using a distance measuring device capable of detecting the distance to the object.

  The drive control unit 5 controls the heating of the movable unit 13 so as to variably control the drive of the optical scanning unit 3 and the focal length of the optical means 14, and controls the AC current for driving the movable unit supplied to the drive coil 15. At the same time, based on the target value input from the input unit 4 and the data stored in the data storage unit 6, the DC current for heating the movable part superimposed on the AC current is controlled to control the deformation amount of the optical means 14. The radius of curvature is variably controlled, and the focal length is controlled to a target value. Further, as described above, in the optical scanning unit 3, the rotational force of the movable unit 13 is proportional to the drive current supplied to the drive coil 15, and the scanning position (scanning angle) of the movable unit 13 is known from the drive current value. The drive control unit 5 transmits the drive current value to the light emission control unit 2 as a light emission timing control signal for the light emission unit 1. The drive control unit 5 is a scanning angle detection device that detects the scanning angle of the optical scanning unit 3 by, for example, providing a mirror on the back side of the movable unit and receiving the reflected light by a light receiving element array or the like. Alternatively, the scanning angle detector may directly detect the scanning angle and transmit the detected value to the light emission control unit 2 as a light emission timing control signal. In this case, the light emission control unit 2 does not need a memory that stores the correspondence data between the movable part drive current value and the scanning angle of the movable part 13 described above.

  The data storage unit 6 is a storage unit that preliminarily stores deformation control amount data of the optical unit 14 corresponding to each focal length of the optical unit 14 measured in advance through experiments or the like. The DC current value data for heating the movable part is stored in association with each focal length data as deformation control amount data of the optical means 14 corresponding to each focal length.

Next, the operation of the variable focus optical device of this embodiment will be described.
The swing angle control of the movable unit 13 of the optical scanning unit 3 is the same as in the prior art. The light emission control unit 2 reads the scanning angle of the movable unit 13 from the memory based on the alternating current value transmitted from the drive control unit 5 and intermittently issues a light emission command to the light emitting unit 1 within a preset scanning angle range. Output. The light emitting unit 1 emits a light beam every time the light emission command is input. Thereby, the light beam is scanned in a predetermined scanning range by the swinging operation of the movable portion 13 of the optical scanning portion 3.

Next, the focal length control operation of the optical means 14 which is a feature of the present invention will be described with reference to the flowchart of FIG.
In step 1 (indicated by S1 in the figure, the same applies hereinafter), target value data of the focal length is input by the input unit 4. For example, the scanning angle of the movable unit 13 and the focal length value at that time are input as target value data.
In step 2, the heater control value (DC current value) corresponding to each focal length value of the target value data input in step 1 is read from the data storage unit 6 by the drive control unit 5 and associated with each scanning angle. Remember.
In step 3, the drive control unit 5 reads the scan angle from the drive current value based on the correspondence data between the drive current value and the scan angle stored in advance, and the DC current value corresponding to the read scan angle 2 is read from the correspondence data between the heater current value read and stored in step 2 and the scanning angle, and the read DC current value is superimposed on the AC current for driving the movable part and supplied to the drive coil 15 to control the heating of the movable part 13. The

  Thereby, the movable part 13 is deformed according to the amount of heater current supplied. For example, when the optical means 14 is a reflection mirror, the movable portion 13 is deformed as shown in FIG. 4 and the amount of warpage thereof changes, the radius of curvature of the reflection mirror 14 changes, and the focal position F changes. Further, when the optical means 14 is a lens, the lens 14 is deformed by the deformation of the movable portion 13 as shown in FIG. 5, the radius of curvature of the lens 14 is changed, and the focal position F is changed.

  According to this configuration, since the focal length of the optical means 14 of the optical scanning unit 3 can be variably controlled, the focal position of the light beam irradiated through the optical scanning unit 3 can be controlled without interposing optical components such as lenses. It can be adjusted to a predetermined position. Therefore, the number of parts of the optical device can be reduced, and the configuration can be simplified. Further, in the case of the electromagnetic driving type optical scanning unit 3 that drives the movable unit 13 using electromagnetic force by the driving coil and the static magnetic field generating means as in this embodiment, the driving coil 15 can be used as a heater coil. There is.

Next, a second embodiment of the present invention will be described.
FIG. 6 shows a configuration diagram of the second embodiment. In addition, the same code | symbol is attached | subjected to the same element as 1st Embodiment, and description is abbreviate | omitted.
The second embodiment is configured to feedback control the focal length of the optical means 14, and is configured by adding a focal length detection means 7 for detecting the actual focal length of the optical means 14 to the configuration of the first embodiment. The

  The focal length of the optical means 14 is determined by the deformation amount of the movable portion 13. Accordingly, in the configuration in which the movable portion 13 is heated and deformed, the focal length of the optical means 14 is related to the temperature of the movable portion 13, and therefore, for example, a temperature sensor is used as the focal length detection means 7 to detect the temperature of the movable portion 13. By doing so, the focal length of the optical means 14 can be detected. In this embodiment, a temperature sensor is attached to the movable part 13 and an actual focal length is detected. In this case, in this embodiment, for example, in order to convert the detection temperature of the temperature sensor into a focal length, a correspondence relationship between the movable portion temperature and the focal length is obtained in advance through experiments or the like, and correspondence data between the movable portion temperature and the focal length is obtained. For example, it is stored in the data storage unit 6 and the focal length value is read from the data storage unit 6 based on the detection value from the temperature sensor.

Next, the focal length control operation of the second embodiment will be described with reference to the flowchart of FIG. Note that the swing angle control of the movable portion 13 is the same as that in the first embodiment, and a description thereof will be omitted.
The operations in steps 11 to 13 are the same as those in steps 1 to 3 in FIG.
In step 14, the detection value of the temperature sensor (focal length detection means 7) is input, and the focal length value B corresponding to the input detection value is read from the data storage unit 6.

  In step 15, the target focal length value A is compared with the actual focal length value B obtained in step 14. If A = B, the heater current value at that time is maintained. If A <B, the process proceeds to step 16, and the heater current is increased and controlled to increase the deformation amount of the movable portion 13 and shorten the focal length. For example, the heater current is increased and corrected by a predetermined value set in advance from the current heater current value until A = B. On the other hand, if A> B, the process proceeds to step 17, and the heater current is decreased and controlled to reduce the deformation amount of the movable portion 13 and increase the focal length. For example, the heater current is decreased and corrected by a predetermined value set in advance from the current heater current value until A = B.

  According to the configuration of the second embodiment, since the heater current is feedback-controlled so that the actual focal length is detected and the target focal length value is obtained, the control accuracy of the focal length can be improved.

In addition, the structure of the optical scanning part 3 is not limited to embodiment mentioned above. For example, as shown in FIG. 8, a rectangular shape memory alloy 21 provided in the movable portion 13 surface, but it may also in a configuration providing a driving coil 15 of the heater coil also serves on the shape memory alloy 21. As in this, with the configuration of deforming the movable portion 13 by heating the shape memory alloy 21, the deformation of the shape memory alloy 21 to facilitate the deformation of the movable portion 13, tends to deform the movable portion 13 Benefits There is.

Also, as shown in FIG. 9, for example, an electromagnetic driving type which is provided a drive coil 15 to the movable portion 13, a pair of movable electrodes 31A on the back side of the movable portion 13, 31B (shown in broken lines in the drawing) is provided, It is good also as a structure which arrange | positions a fixed electrode (not shown) in the fixed part under the movable part 13 facing this movable electrode 31A, 31B, and uses electromagnetic drive and electrostatic drive together.

1 is a configuration diagram showing a first embodiment of a variable focus optical device according to the present invention. Variation of the optical scanning section The flowchart which shows the heating control operation | movement of 1st Embodiment. Explanatory drawing of focal length change state in case of reflection mirror Explanatory drawing of changing focal length in the case of lens The block diagram which shows 2nd Embodiment of this invention The flowchart which shows the heating control operation | movement of 1st Embodiment. Main part plan view showing another configuration example of the optical scanning unit The principal part top view which shows another example of a drive form of the movable part of an optical scanning part

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emission part 2 Light emission control part 3 Optical scanning part 4 Input part 5 Drive control part 6 Data storage part 7 Focal length detection means 11 Fixed part 12,12 Torsion bar 13 Movable part 14 Optical means 15 Drive coil (heater coil)
17A, 17B Static magnetic field generating means

Claims (4)

A movable part supported movably by a fixed part via a beam part;
Drive means for driving the movable part;
Optical means fixed to the movable part and refracting or reflecting an incident light beam;
Control means for variably controlling the focal length of the optical means ;
With
The driving means lays on the movable portion and generates a magnetic field by energization, and a static magnetic field that acts on a portion of the driving coil located on the opposite side of the movable portion parallel to the axial direction of the beam portion. A magnetic field generating means, and an electromagnetic force is applied to the movable portion opposite side portion by the interaction between the magnetic field generated in the drive coil portion located on the movable portion opposite side portion and the static magnetic field,
The optical means that supplies the movable part heating current to the drive coil superimposed on the movable part drive current, controls the heating of the movable part using the drive coil as a heater, and deforms together with the movable part. A variable focus optical device characterized in that the amount of deformation of the optical means is controlled to variably control the curvature radius of the optical means. The variable focus optical device according to claim 1 , wherein a shape memory metal is provided on the movable portion, and the shape memory metal is heated. The control means includes an input section for inputting a target value of the focal length, and a storage section for previously storing the movable portion heating current value data as deformation control amount data of the optical means corresponding to each focal length of the optical means. If, in claim 1 or 2 is configured to include a control unit that deforms controlling the optical means to determine the movable portion heating current value corresponding to the target value input based on the stored data of the storage unit The variable focus optical device described. Wherein the detecting means for detecting the actual focal length of the optical means is provided, wherein the control unit is configured such that the detection value by comparing the detected value and the target value of said detecting means coincides with the target value movable 4. The variable focus optical device according to claim 3 , wherein the current value for part heating is feedback-controlled.

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