JP2013200453A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanner which allows suppression of vibration of a structural body when a mirror part is swung.SOLUTION: The optical scanner includes a structural body, a pedestal, and a driving unit. The structural body includes a mirror part, a pair of torsion beam parts, and a body part. The body part and the pedestal are fixed in a first part to be fixed, a second part to be fixed, and a third part to be fixed. In a direction of a second axial line passing the center of the mirror part and being orthogonal to a swing shaft of the mirror part, a pair of through holes extending in the direction of the swing axis of the mirror part is formed between the third part to be fixed and the driving unit. The body part includes an extension part which is provided between the pair of through holes in the direction of the swing shaft of the mirror part and is connected to the third part to be fixed, linearly symmetrically with respect to the second axial line.

Description

  The present invention relates to an optical scanner that scans light such as a laser.

  2. Description of the Related Art Conventionally, an optical scanner that scans light such as laser light with a swinging mirror is known. As an example of the optical scanner, a mirror unit that is swingably supported by a torsion beam unit is swung by a driving unit such as a piezoelectric element. For example, Patent Document 1 discloses an example of an optical scanner having a structure formed of stainless steel as a conductive material. In the optical scanner of Patent Document 1, a pair of drive units made of piezoelectric elements are provided on both sides of the mirror unit with a position on the structure. The structure is installed on the pedestal.

JP2011-27881A

  In the optical scanner, in order to oscillate the mirror part, vibration is applied to the structure including the mirror part. Due to this vibration, the torsion beam portion is torsionally vibrated. However, not only the torsion beam part but also the structure itself vibrates. The vibration of the structure itself causes a problem that abnormal noise is generated when the optical scanner is driven due to contact between the structure, the pedestal, and the drive unit. If the drive frequency of the optical scanner is within the range of the sound frequency of human audible range, this abnormal sound can be heard and the user may feel uncomfortable. In addition, since the driving force for originally swinging the mirror portion is used for the generation of abnormal noise, the driving efficiency is lowered, for example, the driving voltage necessary for obtaining a desired amplitude of the mirror portion is increased. . For this reason, it is desirable to suppress the vibration of the structure when the mirror portion is swung.

  An object of the present invention is to provide an optical scanner capable of suppressing vibration of a structure when a mirror portion is swung.

  In order to solve the above-described problems, one aspect of the present invention provides a mirror unit having a reflecting surface that reflects incident light and configured to be swingable about a first axis, and from both ends of the mirror unit. And a pair of torsion beam portions extending in parallel to the first axis, and a main body portion connected to ends of the pair of torsion beam portions and extending in a direction away from the mirror portion. A structure, a pedestal to which a part of the structure is fixed, and the main body, the structure is vibrated by applying a driving voltage, and the mirror portion is rotated around the first axis. And a drive unit that can be swung to the main body, wherein the main body includes a pair of first fixed portions that are fixed to the pedestal on an extension line of the pair of torsion beam portions; From the first fixed part, it passes through the center of the mirror part perpendicular to the first axis. A pair of second fixed portions that are separated in the direction of two axes and are fixed to the pedestal, and a third portion that is fixed to the pedestal at the end of the main body in the direction of the second axis. In the direction of the second axis, a pair of through holes extending in the direction of the first axis is formed between the third fixed part and the drive unit in the direction of the second axis, The portion includes an extending portion provided between the pair of through holes in the direction of the first axis and connected to the third fixed portion in line symmetry with respect to the second axis. This is an optical scanner.

  The main body is fixed to the base at the first fixed part, the second fixed part, and the third fixed part. Since these fixed portions are fixed to the base, they hardly vibrate even when the mirror portion is swung. An extension portion provided between the pair of through holes is connected to the third fixed portion. In other words, the extension part bridges the position where the drive part of the main body part is provided and the third fixed part. Since the extension portion bridges the position where the driving portion of the main body portion is provided and the third fixed portion, displacement of the structure in the main body portion is suppressed when the mirror portion is swung. As a result, when the mirror portion is swung, the vibration amount in the main body portion of the structure can be suppressed. The extending portion has a shape that is line-symmetric with respect to the second axis. Therefore, when the mirror portion is swung, the extending portion does not give an asymmetric constraint with respect to the structure in the first axial direction. Therefore, even if the extension portion is provided, the swinging direction of the mirror portion does not change.

  The extending portion may coincide with the second axis in the direction of the first axis.

  For example, when the main body extends in one direction of the second axis as a direction away from the mirror, that is, in the case of a cantilever type optical scanner, the number of extending portions that can coincide with the second axis Is one. When the main body portion extends in both directions of the second axis, that is, in the case of a double-supported optical scanner, the number of extending portions that can coincide with the second axis in the direction of the first axis. Are two, one on each side of the main body. Therefore, compared with the case where a plurality of extending portions are provided on one side of the main body portion, the position where the driving portion of the main body portion is provided and the third fixed portion are bridged with a minimum number. Since a minimum number of bridges are used, the structure is simplified.

  Further, the extension portion may have a length of 1/3 or more of the length from the first axis to the extension portion in the direction of the second axis.

  The inventor's research has revealed that the drive voltage necessary to obtain a desired amplitude is changed by adjusting the length of the extended portion in the direction of the second axis. Specifically, in the direction of the second axis, when the length of the extended portion is 1/3 or more of the length from the first axis to the extended portion, it is compared with an optical scanner in which no extended portion is provided. Thus, the drive voltage can be reduced.

  The extension portion may have a length that is ½ or less of the length from the first axis to the extension portion in the direction of the second axis.

  The inventors' research has revealed that the amount of vibration of the structure is changed by adjusting the length of the extended portion in the direction of the second axis. This amount of vibration increases if the length of the extending portion in the direction of the second axis is too long, and increases if it is too short. In other words, there is a range in which the vibration amount of the structure can be minimized in the length of the extending portion in the direction of the second axis. Specifically, in the direction of the second axis, when the length of the extended portion is not less than 1/3 and not more than 1/2 of the length from the first axis to the extended portion, the vibration amount is minimal. It becomes.

In addition, when the length of the extended portion in the direction of the second axis is b, and the length of the extended portion in the direction of the first axis is c, b / c ^{0 .4} may be configured to have a value of 2 or more and 4 or less.

  According to this, as shown in FIG. 5 to be described later, the vibration amount in the main body portion of the structure is reduced to about half or less as compared with the case where the extension portion is not provided. Furthermore, the drive voltage required to obtain the desired amplitude is also smaller than when no extension portion is provided.

Further, the extending portion may be configured in a shape in which the value of b / c ^0.4 is 3.

  According to this, as shown in FIG. 5 to be described later, an optical scanner in which the vibration amount in the main body of the structure is minimized can be obtained.

  According to the present invention, it is possible to obtain an optical scanner capable of suppressing vibration in the main body portion of the structure when the mirror portion is swung.

1 is a perspective view of an optical scanner 100 according to an embodiment. (A) The top view of the optical scanner 100 which concerns on embodiment, (B) AA sectional drawing of the optical scanner 100. FIG. The figure explaining the change of the maximum vibration amount of the main-body part 113 when the shape of the extension part 116 is changed. The figure explaining the change of a drive voltage at the time of changing the shape of the extension part 116. FIG. (A) The figure explaining the change of the maximum vibration amount of the main-body part 113 when the length b of the extension part 116 is normalized based on the length c, (B) The length of the extension part 116 is long. The figure explaining the change of a drive voltage at the time of normalizing based on length c. The perspective view of the optical scanner 200 which concerns on a comparative example. The top view of the optical scanner 200 which concerns on a comparative example. The figure explaining the change of the maximum vibration amount of the main-body part 213 when the position of the additional bridge 217 is changed. The figure explaining the change of a drive voltage when the position of the additional bridge | bridging 217 is changed. The top view of the optical scanner 300 which concerns on a modification. The top view of the optical scanner 400 which concerns on a modification.

<Embodiment>
Hereinafter, an embodiment reflecting one aspect of the present invention will be described with reference to the drawings. Note that the drawings to be referred to are used to explain technical features that can be adopted by the present invention, and the described configuration is merely an illustrative example rather than a limitation. For example, in each configuration described below, a predetermined configuration may be omitted or replaced with another configuration. Moreover, you may make it include another structure.

[Configuration of Optical Scanner 100]
As shown in FIGS. 1 and 2, the optical scanner 100 includes a structure 110 and a pedestal 120 to which the structure 110 is fixed. The oscillating part 111 and the mirror member 130 are oscillated around the first axis la by the driving part 140. By this swinging, the light incident on the mirror member 130 is scanned.

  The structure 110 is a plate-like structure having a rectangular shape in plan view, which includes a pair of short sides parallel to the front-rear direction and a pair of long sides parallel to the left-right direction. Note that the front-rear direction is parallel to the first axis la. The structure 110 includes a swing part 111, a pair of torsion beam parts 112, and a main body part 113. A drive unit 140 is provided on one surface (for example, the upper surface) of the main body unit 113. In the present embodiment, a pair of drive units 140 are provided so as to be symmetric with respect to the first axis la. The structure 110 is made of a metal material such as stainless steel or titanium. However, the structure 110 may be formed of a semiconductor material such as silicon. The structure 110 is parallel to the front, rear, left and right surfaces in FIG. Moreover, the size of the structure 110 in the front-rear direction, the left-right direction, and the up-down direction is, for example, about 20 mm, 30 mm, and 0.1 mm, respectively.

  One end of the pair of torsion beam portions 112 is coupled to the end portion of the swinging portion 111 in the front-rear direction. The pair of torsion beam portions 112 extend in the front-rear direction from the connection position with the swinging portion 111 in parallel with the first axis la. The first axis la passes through the center of the torsion beam portion 112. That is, the swinging portion 111 is elastically supported by the torsion beam portion 112 so as to be swingable about the first axis la. In other words, the torsion beam portion 112 serves as a torsion bar that supports the swinging portion 111 so as to be swingable about the first axis la.

  The main body portion 113 is connected to the other end of the pair of torsion beam portions 112. The main body portion 113 extends from the connecting position with the torsion beam portion 112 in a direction away from the swinging portion 111 and intersecting the first axis la. In the present embodiment, the main body 113 extends from the connecting portion with the torsion beam 112 to both sides in the left-right direction.

  The main body 113 is formed with four through holes X, two through holes Y, and four through holes Z. The through hole X is provided at a position farther from the mirror member 130 than the other ends of the pair of torsion beam portions 112 in the front-rear direction. Specifically, the through holes X are arranged symmetrically with respect to the first axis la at both ends of the main body 113 in the front-rear direction. The through hole X is formed in a rectangular shape, and its longitudinal direction is parallel to the left-right direction. The through hole X is also arranged symmetrically with respect to the second axis lb that is orthogonal to the first axis la and passes through the center of the swinging portion 111. The through hole Y is formed at the center of the main body 113. The longitudinal direction of the through hole Y is along the front-rear direction. The swinging portion 111 and the torsion beam portion 112 are defined with respect to the main body portion 113 by the through hole Y. The through hole Y is arranged symmetrically with respect to the first axis la. The through-hole Z is disposed symmetrically with respect to the second axis lb between the left and right ends of the main body 113 and the drive unit 114. The through hole Z extends in the direction of the first axis la, that is, the front-rear direction. The through-hole Z is arranged symmetrically with respect to the first axis la.

  The main body 113 includes two central bridging portions 114, four end bridging portions 115, and two extending portions 116. The center bridging portion 114 includes the first axis la and extends in the front-rear direction. That is, the center bridging portion 114 is formed in the same straight line as the pair of torsion beam portions 112. The center bridging portion 114 is located between the through holes X in the left-right direction. The end bridging portion 115 is provided at the end in the front-rear direction of the main body 113 in line symmetry with respect to the first axis la. The end bridging portion 115 is provided between the through hole X and the through hole Z in the left-right direction. The extending portion 116 is provided between the through holes Z in the front-rear direction. The extending portion 116 is arranged symmetrically with respect to the first axis la in the left-right direction. The extending portion 116 is arranged symmetrically with respect to the second axis lb in the front-rear direction. Since the extending part 116 is arranged in line symmetry with respect to the second axis lb in the front-rear direction, the structure 113 does not give an asymmetric constraint with respect to the front-rear direction. Therefore, even if the extension part 116 is provided, the swinging direction of the swinging part 111 does not change. In the present embodiment, the extension portion 116 coincides with the second axis lb in the front-rear direction. In other words, the second axis lb is included in the extended portion 116. In addition, the extension part 116 and the 2nd axis line lb may be spaced apart in the up-down direction. Since the main body 113 extends in both the left and right directions, the number of extending portions 116 that can coincide with the second axis lb is two, one on each side of the main body 113. . Therefore, as compared with the case where a plurality of extending portions 116 are provided on one side of the main body 113, the position where the driving portions 140 of the main body 113 are provided and the third fixed portion 116a are bridged with a minimum number. Is done. Since a minimum number of bridges are used, the structure is simplified.

  A driving unit 140 is provided on the upper surface of the main body unit 113. A pair of drive units 140 is provided at an intermediate position in the front-rear direction of the main body unit 113 and is symmetrical with respect to the first axis la in the left-right direction. However, the driving unit 140 may be provided at other positions. For example, the drive unit 140 may be provided on both the upper and lower surfaces of the main body unit 113. For example, the drive unit 140 is a laminate of 0.2 μm to 0.6 μm of gold, platinum, or the like as an electrode layer on both surfaces of a piezoelectric material such as lead zirconate titanate formed into a flat plate having a thickness of 30 μm to 100 μm It is formed by doing. The drive unit 140 and the main body unit 113 are bonded with a conductive adhesive. A thin metal wire (not shown) such as gold is connected to the upper surface of the drive unit 140 by wire bonding or the like.

  A mirror member 130 that reflects light such as a laser is fixed on the upper surface of the swinging portion 111. In other words, the swing part 111 and the mirror member 130 constitute a mirror part. The mirror member 130 having a rectangular shape in plan view is configured separately from the oscillating portion 111 by a dielectric having transparency to visible light such as sapphire or diamond. On the upper surface or the lower surface of the mirror member 130, a metal thin film such as aluminum or silver is formed by a method such as sputtering or vapor deposition in order to reflect light such as laser. The oscillating portion 111 and the mirror member 130 are fixed with, for example, an epoxy, phenol, or silicon thermosetting adhesive. The swing part 111 and the mirror member 130 are provided symmetrically with respect to the first axis la. Instead of using a separate mirror member 130, mirror processing such as polishing or formation of a reflective film may be performed on the upper surface of the oscillating portion 111. In this case, a reflecting surface is provided on the upper surface of the swinging part 111, and the swinging part 111 itself functions as a mirror part.

  The pedestal 120 is a plate-like member formed in a rectangular shape. The long side of the pedestal 120 is parallel to the left-right direction. The short side of the pedestal 120 is parallel to the front-rear direction. In the center of the pedestal 120, a rectangular through hole whose longitudinal direction extends in the left-right direction is provided. The ends of the main body 113 in the front-rear and left-right directions overlap the base 120 in the up-down direction. The vertical thickness of the pedestal 120 is sufficiently larger than the vertical thickness of the structure 110, for example, about 2 mm. Therefore, even if the structure 110 swings, the pedestal 120 hardly deforms. The pedestal 120 is made of a metal material such as stainless steel, for example.

  The structure 110 and the pedestal 120 are fixed at a portion where they overlap each other in the vertical direction. In the present embodiment, at least the structure 110 and the pedestal 120 in the first fixed portion 114a, the second fixed portion 115a, and the third fixed portion 116a that exist at the ends of the main body portion 113 in the front-rear and left-right directions. And are fixed. This fixing is performed by, for example, a conductive adhesive containing a conductive material such as a metal filler in a synthetic resin material such as epoxy, acrylic, or silicon. Alternatively, this fixing is performed by welding using a laser or the like. Since the structure 110 and the pedestal 120 are made of a metal material, the structure 110 and the pedestal 120 can be electrically connected to the lower surface of the driving unit 140 via the pedestal 120.

  The first fixed portion 114 a exists on an extension line of the pair of torsion beam portions 112. Specifically, the first fixed portion 114 a is a region of the main body portion 113 that is on the first axis la and is further away from the mirror member 130 than the central bridging portion 114. A pair of first fixed portions 114a are provided symmetrically with respect to the second axis lb.

  The second fixed portion 115a exists at a position spaced apart from the pair of first fixed portions 114a in the left-right direction. Specifically, the pair of second fixed portions 115a exist on the extension line of the end bridging portion 115 in the front-rear direction and at a position farther from the second axis lb than the end bridging portion 115. A pair of second fixed portions 115a are provided symmetrically with respect to the second axis lb. The pair of second fixed portions 115a is further provided in a pair symmetrical with respect to the first axis la. That is, four second fixed portions 115a are provided.

  The third fixed portion 116a is present at the end of the main body 113 in the left-right direction. Specifically, the third fixed portion 116a exists on the extension line of the extension portion 116 and at a position farther from the first axis la than the extension portion 116 in the left-right direction. A pair of third fixed portions 116a are provided symmetrically with respect to the first axis la. The structure 110 and the pedestal 120 are regions other than the first fixed portion 114a, the second fixed portion 115a, and the third fixed portion 116a described above, and are the upper and lower portions of the main body 113 and the pedestal 120. It may be further fixed at the overlapping portion in the direction.

[Driving of optical scanner 100]
Since the structure 110 and the pedestal 120 are made of a metal material, a voltage is applied to the drive unit 140 by applying a voltage between the pedestal 120 and a thin metal wire connected to the upper surface of the drive unit 140. Is done. When the voltage is applied to the driving unit 140, the driving unit 140 is deformed. The main body 113 is vibrated by the deformation of the driving unit 140. A drive signal is periodically applied to the drive unit 140 provided on the right side and the drive unit 140 provided on the left side so as to have opposite phases. When the frequency of the drive signal corresponds to the frequency necessary for resonant driving of the optical scanner 100, a plate wave is excited in the main body 113 with the deformation of the drive unit 140. The plate wave is transmitted to the swing part 111 via the main body part 113 and the torsion beam part 112, so that the swing part 111 swings around the first axis la at a predetermined resonance frequency. Here, the structure 110 is fixed to the base 120 at the first fixed portion 114a, the second fixed portion 115a, and the third fixed portion 116a. The main body 113 is in a state of being suspended in the air by the pedestal 120. Therefore, when the optical scanner 100 is driven, the main body 113 is displaced in the vertical direction. Since the torsion beam portion 112 is provided at a position that becomes a vibration node of the main body portion 113, even if the main body portion 113 is displaced in the vertical direction, the torsion beam portion 112 is suppressed from being displaced in the vertical direction. Note that the frequency of the drive signal may not exactly match the resonance frequency of the optical scanner 100. The frequency of the drive signal may be appropriately offset from the resonance frequency of the optical scanner 100 according to the Q value of the optical scanner 100 and the linearity of the frequency characteristics.

[Create Optical Scanner 100]
A production process of the optical scanner 100 will be described. Here, the case where the structure 110 is made of metal will be described as an example. First, a metal plate (for example, stainless steel or titanium) constituting the structure 110 is divided into a size equal to the outer shape of the structure 110. And the through-hole X, the through-hole Y, and the through-hole Z are formed by performing a predetermined removal process with respect to the divided | segmented metal plate. By forming the through hole X, the through hole Y, and the through hole Z, the outer shape of the structure 110 is formed. The predetermined removal processing includes, for example, etching, press processing, electric discharge processing, laser processing, and the like. As an example, when wet etching is performed, a resist film for masking is formed at a position of the divided metal plate excluding the through hole X, the through hole Y, and the through hole Z. Thereafter, after the outer shape of the structure 110 is formed by wet etching, the resist film is removed. It should be noted that, after the outer shapes of the plurality of structures 110 are formed on a metal plate that is sufficiently larger than the outer shape of the structures 110, a large number of pieces can be divided into individual structures.

  Next, the driving unit 140 provided with electrode layers on both surfaces of the piezoelectric material in advance is mounted on the structure 110. This mounting is performed using, for example, a conductive adhesive containing a conductive material such as a metal filler in a synthetic resin material such as epoxy, acrylic or silicon. Specifically, the drive unit 140 is installed on the conductive adhesive applied to the main body 113 of the structure 110. After the drive unit 140 is installed, the conductive adhesive is cured by placing the structure 110 in a heating furnace maintained in an atmosphere of 100 to 200 ° C. for 30 to 60 minutes. Thus, the mounting of the driving unit 140 is completed.

  Next, the pedestal 120 is created. The outer shape of the pedestal 120 is obtained by performing removal processing such as etching or pressing on the constituent material of the pedestal 120, as in the case of the structure 110.

  Next, the base 120 and the structure 110 are fixed at the first fixed portion 114a, the second fixed portion 115a, and the third fixed portion 116a. As described above, this fixing is performed using laser welding or a conductive thermosetting adhesive. Therefore, the structure 110 and the pedestal 120 are in an electrically connected state.

  Finally, signal lines are connected to the drive unit 140 and the pedestal 120. This signal line is connected to an AC power source (not shown). When the optical scanner 100 is driven, a drive signal is supplied between the drive unit 140 and the pedestal 120 via this signal line. Thus, the creation process of the optical scanner 100 is completed.

[Effects of the extended portion 116]
With reference to FIG. 3, the reduction of the maximum vibration amount of the main body 113 by the extended portion 116 will be described. The maximum amount of vibration shown on the vertical axis in FIG. 3 is the amount of vibration at a position where the amount of displacement in the vertical direction of the main body 113 is maximum during driving. The position where the displacement amount is maximum is, for example, a position where the drive unit 140 of the main body 113 is provided. Further, the maximum vibration amount is expressed as a percentage by dividing by the maximum vibration amount in the vertical direction of the mirror member 130 during driving. In the present embodiment, the change in the maximum vibration amount of the main body 113 is examined by fixing the length a and changing the length b. As shown in FIG. 2A, the length a is the length of the main body 113 from the first axis la to the extending portion 116 in the left-right direction. The length b is the length of the extending portion 116 in the left-right direction, as shown in FIG. The horizontal axis of FIG. 3 is indicated by a value obtained by dividing the length b by the length a. In the present embodiment, the length c (see FIG. 2A) of the extending portion 116 in the front-rear direction is also changed, and the change in the maximum vibration amount of the main body 113 is examined. The length c is similarly divided by the length a. The data of c / a = 0.118 is indicated by a hollow square and a solid line. The data of c / a = 0.235 is indicated by a hollow triangle and a dotted line. The data of c / a = 0.353 is indicated by a cross and a one-dot chain line. In FIG. 3, for comparison, data when the length c is “0”, that is, when the extended portion 116 does not exist is also indicated by a hollow circle. Further, the values shown in FIG. 3 are values obtained by simulation performed by changing the shape of the extended portion 116 based on parameters such as the shape and material of the optical scanner 100.

  As shown in FIG. 3, by providing the extension portion 116, the maximum amount of vibration is reduced regardless of the shape of the extension portion 116, compared to the case where the extension portion 116 does not exist. Strictly speaking, the value of b / a at which the maximum vibration amount is minimized differs slightly depending on the value of c / a. However, generally speaking, the maximum vibration amount decreases as the value of b / a increases when the value of b / a is 0.3 or less. The maximum amount of vibration is minimum when the value of b / a is approximately 0.3 to 0.5, in other words, when the length b is approximately 1/3 to 1/2 of the length a. When the b / a value is 0.5 or more, the maximum vibration amount increases as the b / a value increases. That is, the maximum vibration amount can be minimized by setting the value of b / a to approximately 0.3 to 0.5.

  With reference to FIG. 4, reduction of the drive voltage by the extended portion 116 will be described. The horizontal axis in FIG. 4 indicates the value of b / a, as in FIG. The vertical axis in FIG. 4 indicates the value of the drive voltage necessary to obtain the desired amplitude of the swinging part 111 at a certain b / a value. Note that the value of the drive voltage is indicated by a drive voltage ratio divided by the value of the drive voltage necessary to obtain a desired amplitude in the optical scanner 100 when the extended portion 116 is not present. It can be said that the smaller the drive voltage necessary to obtain a desired amplitude, the less the power consumption of the optical scanner 100. In FIG. 4, as in FIG. 3, the length c (see FIG. 2A) is also changed, and the drive voltage ratio is examined. The data of c / a = 0.118 is indicated by a hollow square and a solid line. The data of c / a = 0.235 is indicated by a hollow triangle and a dotted line. The data of c / a = 0.353 is indicated by a cross and a one-dot chain line. In FIG. 4, for comparison, data when the length c is “0”, that is, when the extended portion 116 does not exist is also indicated by a hollow circle. Also, the values shown in FIG. 4 are values obtained by simulation performed by changing the shape of the extended portion 116 based on parameters such as the shape and material of the optical scanner 100.

  In FIG. 4, the drive voltage ratio decreases as the value of b / a increases. Strictly speaking, the drive voltage ratio is slightly different depending on the value of c / a with respect to the same value of b / a. However, generally speaking, a monotonically increasing tendency of the drive voltage ratio according to the increase in the value of b / a was confirmed regardless of the value of c / a. Further, when the value of b / a is about 0.3 or more, in other words, when the length b is about 1/3 or more of the length a, the drive voltage ratio becomes smaller than 1. That is, by setting the length b to be approximately 1/3 or more of the length a, it is possible to reduce the driving voltage as compared with the case where the extension portion 116 is not provided.

  As shown in FIGS. 3 and 4, the value of c / a does not affect the tendency between the value of b / a and the maximum vibration amount and drive voltage ratio of the main body 113. For example, in FIG. 3, the maximum vibration amount temporarily decreases and then increases as the value of b / a increases, regardless of the value of c / a. In FIG. 4, the drive voltage ratio decreases as the value of b / a increases regardless of the value of c / a. However, in FIG. 3 and FIG. 4, when the value of c / a is different, the value of the maximum vibration amount and the drive voltage ratio are different even if the value is the same b / a. Here, the influence of the value of c / a on the maximum vibration amount and the drive voltage ratio will be described with reference to FIG.

  The vertical axis in FIG. 5A indicates the maximum vibration amount of the main body 113 as in FIG. The horizontal axis in FIG. 5B indicates a value obtained by dividing the length b by the 0.4th power of the length c. In FIG. 5A, data in the case of c / a = 0.118, c / a = 0.235, and c / a = 0.353 are shown using the same symbols as in FIG. The vertical axis in FIG. 5B indicates the drive voltage ratio as in FIG. The horizontal axis of FIG. 5B shows the value obtained by dividing the length b by the 0.4th power of the length c, as in FIG. In FIG. 5A, data in the case of c / a = 0.118, c / a = 0.235, and c / a = 0.353 are shown using the same symbols as in FIG.

For the value obtained by dividing the length b by the 0.4th power of the length c, the behavior of the maximum vibration amount and the drive voltage ratio is substantially the same regardless of the value of c / a. Specifically, as shown in FIG. 5A, when the length b is divided by the length c raised to the 0.4th power, even if the value of c / a is different, b / c ^0.4 The relationship between the value and the maximum amount of vibration is the same. When the value of b / c ^0.4 is 2 or more and 4 or less, the maximum vibration amount is reduced to about half or less compared to the case where the extension portion 116 is not provided. When the value of b / c ^0.4 is about 3, the maximum vibration amount is minimized. Further, as shown in FIG. 5B, even if the value of c / a is different, the relationship between the value of b / c ^0.4 and the drive voltage ratio is the same. If the value of b / c ^0.4 is 2 or more, the drive voltage ratio is smaller than 1. The interpretation of the physical meaning of a value of “0.4”, which is a multiplier of the length c, is not yet clear. However, as a result, the behavior of the maximum vibration amount and the drive voltage ratio is substantially the same regardless of the value of c / a with respect to the value of (1) b / c ^0.4 , and (2) b / c. ^When the value of ^0.4 is 2 or more and 4 or less, the maximum vibration amount is reduced to about half or less compared to the case where the extension portion 116 is not provided, (3) b / c ^0.4 When the value of “3” is “3”, new knowledge was obtained that the maximum vibration amount was minimized.

<Comparative example>
[Configuration of Optical Scanner 200]
As a comparative example, an example of an optical scanner 200 in which no extending portion is provided is shown. The optical scanner 200 is different from the optical scanner 100 in the shape of the structure 210. In the optical scanner 200, the same components as those in the optical scanner 100 are given the same numbers, and description thereof is omitted.

  As shown in FIGS. 6 and 7, the optical scanner 200 includes a structure 210 and a pedestal 120. The main body 213 of the structure 210 is different from the main body 113 of the structure 110. Specifically, the main body part 213 is different from the main body part 113 (FIGS. 1 and 2) in that (1) it has an additional bridging part 217 and (2) there is no extension part. The additional bridging portion 217 is separated from the first axis la in the left-right direction. The additional bridging portion 217 bridges the through hole X in the front-rear direction. A pair of additional bridging portions 217 are provided on both the left and right sides of the central bridging portion 114 so as to be line symmetric with respect to the first axis la. In addition, the pair of additional bridging portions 217 is provided in a line symmetry with respect to the second axis lb. That is, the structure 210 includes four additional bridging portions 217. A fourth fixed portion 217a that is fixed to the pedestal 120 is provided on the extension line of the additional bridging portion 217 in the direction away from the second axis lb in the front-rear direction.

[Effects of additional bridging portion 217]
The influence of the position where the additional bridging portion 217 is disposed on the maximum vibration amount and driving voltage of the optical scanner 200 will be described with reference to FIGS. Note that, as shown in FIG. 7, the distance from the center first axis la of the additional bridging portion 217 in the left-right direction is expressed as a distance d.

  The horizontal axis of FIG. 8 indicates a value obtained by dividing the distance d by the distance a (see FIG. 7) from the first axis la to the through hole Z. The vertical axis in FIG. 8 indicates the maximum vibration amount of the main body 213 as in FIG. For reference, data when the additional bridging portion 217 is not provided in the configuration of the optical scanner 200 is also shown in FIG. Evidently from FIG. 8, compared with the case where the additional bridging part 217 is not provided, the maximum amount of vibration is reduced by providing the additional bridging part 217.

  The horizontal axis of FIG. 9 shows the value obtained by dividing the distance d by the distance a, as in FIG. The vertical axis in FIG. 9 indicates the drive voltage ratio as in FIG. As apparent from FIG. 9, the drive voltage ratio is increased by providing the additional bridging portion 217 compared to the case where the additional bridging portion 217 is not provided. The drive voltage ratio is always 1 or more regardless of the shape of the additional bridging portion 217. More specifically, as compared with the case where the additional bridging portion 217 is not provided, the driving voltage for obtaining a desired amplitude in the optical scanner 200 is about 1.5 times at the minimum and about 3.5 times at the maximum. To rise.

  In the optical scanner 200 as the comparative example, the reduction of the maximum vibration amount was confirmed by providing the additional bridging portion 217. However, the optical scanner 100 is preferable to the optical scanner 200 from the viewpoint of keeping the drive voltage low.

  The present invention is not limited to the embodiments described so far, and various modifications and changes can be made without departing from the spirit of the present invention. An example is described below.

  In the above-described embodiment, the extending portion 116 is provided including the second axis lb. However, the extending portion may be arranged symmetrically with respect to the second axis lb. Therefore, the shape of the extending portion 116 is not limited to the above-described embodiment. The example of the other form of the extension part 116 is demonstrated using FIG.

  The optical scanner 300 shown in FIG. 10 is different from the optical scanner 100 in the shapes of the extended portion 316 and the third fixed portion 316a. In the optical scanner 300, the same components as those in the optical scanner 100 are given the same numbers, and description thereof is omitted.

  The extending portion 316 is arranged symmetrically with respect to the second axis lb in the front-rear direction. A pair of extending portions 316 are provided apart from the second axis lb in the front-rear direction. The pair of extending portions 316 are provided in a pair so as to be symmetric with respect to the first axis la in the left-right direction. Accordingly, four extending portions 316 are provided. The fixed portion 316a is provided on the extension line of the extending portion 316 in the left-right direction and at a position farther from the swinging portion 111 than the extending portion 316 is. In the fixed portion 316a, the structure 310 and the pedestal 120 are fixed.

  Even in the shape of the optical scanner 300, since the extended portion 316 is provided, an effect of suppressing vibration in the main body 313 can be obtained. That is, the optical scanner 300 is included in the scope of the present invention. In addition, since the extended portion 316 is arranged in line symmetry with respect to the second axis lb in the front-rear direction, the structure 313 is not restrained asymmetrically with respect to the front-rear direction. Therefore, even if the extension part 316 is provided, the swinging direction of the swinging part 111 does not change.

  In the above-described embodiment, the main body portion 113 extends from the connecting portion with the torsion beam portion 112 to both sides in the left-right direction. In other words, the torsion beam portion 112 is supported at both ends in the left-right direction by the main body portion 113. However, the shape of the main body is not limited to the above-described embodiment. Another example of the shape of the main body will be described with reference to FIG.

  An optical scanner 400 shown in FIG. 11 is different from the optical scanner 100 in the shape of the main body 413. In the optical scanner 400, the same components as those in the optical scanner 100 are given the same numbers, and description thereof is omitted. The main body portion 413 extends only in the right direction from the connecting portion with the torsion beam portion 112. In other words, the torsion beam portion 112 is cantilevered in the left-right direction by the main body portion 413. In the optical scanner 400, the drive unit 140, the through hole Z, the extended portion 116, and the third fixed portion 116a are axisymmetric with respect to the second axis lb, but are asymmetric with respect to the first axis la. Become. Such an optical scanner 400 is also included in the scope of the present invention.

  In the above-described embodiment, the pedestal 120 is a plate-like member formed in a rectangular shape. However, the pedestal is not limited to this shape. As long as the structure 110 and the pedestal 120 can be fixed in the first fixed portion 114a, the second fixed portion 115a, and the third fixed portion 116a, the shape of the pedestal 120 is any shape. May be.

  In the embodiment described above, the optical scanner is driven at a resonant frequency. However, the present invention can also be applied to an optical scanner that is not resonantly driven. This is because, even in an optical scanner that is not resonantly driven, vibration is applied to the structure for driving, so that the problem of vibration of the structure also occurs.

  In the above-described embodiment, a piezoelectric material is used as the driving unit 140. However, even an optical scanner that employs another driving method such as an electromagnetic driving method using a combination of a magnet and a coil pattern or an electrostatic driving method using an electrostatic force acting between electrode plates is included in the scope of the present invention. .

100, 200, 300, 400 Optical scanner 110, 210, 310, 410 Structure 111 Oscillating part 112 Torsion beam part 113, 213, 313, 413 Main body part 114 Central bridging part 114a First fixed part 115 End bridging part 115a Second fixed portion 116, 316 Extension portion 116a, 316a Third fixed portion 120 Base 130 Mirror member 140 Drive portion 217 Additional bridging portion 217a Fourth fixed portion

Claims (6)

A mirror portion having a reflecting surface for reflecting incident light and configured to be swingable about a first axis;
A pair of torsion beam portions extending in parallel to the first axis from both ends of the mirror portion;
A main body connected to the ends of the pair of torsion beam portions and extending in a direction intersecting the first axis;
A planar structure having
A pedestal to which a part of the structure is fixed;
A drive unit that is provided in the main body unit and can vibrate the structure by applying a drive voltage, and can swing the mirror portion around the first axis;
The main body is
A pair of first fixed portions fixed to the pedestal on an extension line of the pair of torsion beam portions;
A pair of second fixed parts that are spaced apart from the pair of first fixed parts in a direction of a second axis that is orthogonal to the first axis and that passes through the center of the mirror part, and fixed to the pedestal; ,
A third fixed portion fixed to the pedestal at the end of the main body in the direction of the second axis,
In the direction of the second axis, a pair of through-holes extending in the direction of the first axis is formed between the third fixed portion and the drive unit,
The main body includes an extending portion provided between the pair of through holes in the direction of the first axis and connected to the third fixed portion in line symmetry with respect to the second axis. ,
An optical scanner characterized by that. The extension portion coincides with the second axis in the direction of the first axis;
The optical scanner according to claim 1. The extending portion has a length of 1/3 or more of the length from the first axis to the extending portion in the direction of the second axis.
The optical scanner according to claim 2. The extending portion has a length of ½ or less of the length from the first axis to the extending portion in the direction of the second axis.
The optical scanner according to claim 3. The extending portion is
When the length of the extending portion in the direction of the second axis is b, and the length of the extending portion in the direction of the first axis is c, the value of b / c ^0.4 is 2 or more and 4 Configured in the following shape,
The optical scanner according to claim 1. The extension portion is configured in a shape where the value of b / c ^0.4 is 3.
The optical scanner according to claim 5.

Images