JP2010085506A - Optical scanner and image display device equipped with optical scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provided an optical scanner wherein a large mirror displacement can be obtained while ensuring good stability of mirror displacement, and to provided an image display device using that optical scanner. <P>SOLUTION: A notch 122 is provided in the periphery of the coupling position of an outer frame 114 where the outer frame 114 and a pair of beams 113b are coupled. A fixing protrusion 123 is provided in the notch 122 between extensions which extend, respectively, from the pair of beams 113b in parallel with an oscillation axis AoR1. Since the notch 122 and the fixing protrusion 123 are provided, balance can be achieved between a large mirror displacement and good stability of mirror displacement. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical scanner used in a laser printer or an image display device, and more particularly to an optical scanner used in resonance drive using a MEMS mirror and an image display device using the optical scanner.

  Conventionally, optical scanners have been used in laser printers and image display devices that display light by scanning light. In general, there are optical scanners using a polygon mirror, galvanometer mirrors, and MEMS (Micro-Electro-Mechanical Systems) mirrors. In particular, the optical scanner using the MEMS mirror needs only one light reflecting surface, and the mirror, the torsion bar, and the support frame can be integrally processed. Therefore, the optical scanner using the polygon mirror and the galvanometer mirror can be downsized. Weight reduction is possible.

Many inventions relating to the mechanical structure of an optical scanner using a MEMS mirror (hereinafter referred to as an optical scanner) have been filed to date. As an example, the optical scanner described in Patent Document 1 is shown in FIG. The optical scanner 500 is divided into a base 510 and a pedestal 520. A reflection mirror 511 is located at the center of the base 510. The reflection mirror 511 is supported at both ends by a pair of first elastic beams 512. The pair of first elastic beams 512 is connected to a second elastic beam 513 divided into two branches. The second elastic beam 513 is connected to the outer frame portion 514. The pedestal 520 is fixed under the base 510 so that the outer frame portion 514 and the fixing portion 521 are fixed. As another example, an optical scanner described in Patent Document 2 is shown in FIG. The optical scanner 600 is divided into a base 610 and a pedestal 620. The structure of the base 610 is the same as the base 510 in Patent Document 1. On the other hand, the structure of the base 620 is different from the base 520 in Patent Document 1. Specifically, the notch 622 is provided at a position of the base 620 corresponding to the connection position between the second elastic beam 613 and the outer frame portion 614 of the base 610. In Patent Document 2, the natural frequency of the optical scanner 600 is adjusted by adjusting the shape of the notch 622.
JP 2003-57586 A JP 2007-94146 A

  For example, when an optical scanner is used in an image display device, the angle of view of the display image depends on the amount of displacement of the reflection mirror. Therefore, in order to display a large image or a detailed image, it is desirable that the amount of displacement of the reflecting mirror is larger. In the case of an optical scanner configured by fixing a base and a pedestal, the amount of displacement of the reflecting mirror during resonance driving (hereinafter referred to as mirror displacement) varies depending on the fixed position between the base and the pedestal. Specifically, the amount of mirror displacement of the optical scanner varies depending on how far the pedestal is fixed to the outer frame part away from the connection position between the outer frame part and the second elastic beam. Since the base is as thin as about 100 μm, it is easily deformed when driven by resonance. Since the pedestal is sufficiently thicker than the base, the fixed position between the base and the pedestal serves as a fixed end when driven by resonance. That is, the mirror displacement amount of the optical scanner changes depending on the distance between the fixed end and the connection position.

  In order to quantitatively investigate the relationship between the position of the fixed end and the mirror displacement amount of the optical scanner, a conventional example simulation was conducted to examine the change in the mirror displacement amount of the optical scanner. In the conventional example simulation, it is examined how the mirror displacement changes by moving the position of the fixed end in the direction parallel to the swing axis. Hereinafter, the contents of this conventional simulation will be described with reference to FIG. FIG. 12A is a schematic bottom view around the connection position of the second elastic beam 613 and the outer frame portion 614 of the optical scanner 600, and FIG. 12B shows the second elastic beam 513 of the optical scanner 500. FIG. 6 is a schematic bottom view around a connection position with an outer frame portion 514. The fixed end position p <b> 1 in the optical scanner 600 exists at a position farther from the mirror 611 than the connection position p <b> 2 between the second elastic beam 613 and the outer frame portion 614 because the notch 622 exists. On the other hand, the fixed end position p <b> 1 in the optical scanner 500 exists at a position that substantially matches the connection position p <b> 2 between the second elastic beam 513 and the outer frame portion 514. The change in the mirror displacement when the distance between the fixed end position p1 and the connection position p2 between the second elastic beam 513 and the outer frame portion 514 was changed was examined by simulation.

  Hereinafter, the result of the above-described conventional simulation will be described with reference to FIG. FIG. 13 is a diagram illustrating a change in the mirror displacement amount when the fixed end position is changed. The horizontal axis indicates the distance between the fixed end position p1 and the connection position p2 between the second elastic beam 513 and the outer frame portion 514. The distance between p1 and p2 in the optical scanner 600 shown in FIG. 12A is expressed as 0%. The distance between p1 and p2 in the optical scanner 500 shown in FIG. 12B, that is, when p1 and p2 are approximately at the same position is expressed as 100%. The vertical axis indicates how much the mirror displacement has increased by a percentage with respect to the case where the distance between p1 and p2 is 0%. In the range where the distance between p1 and p2 is from 0% to around 60%, the mirror displacement increases as the fixed end position approaches the reflecting mirror. When the distance between p1 and p2 is in the vicinity of 60%, the mirror displacement amount shows a maximum that is about 20% larger than that when the distance between p1 and p2 is 0%. When the distance between p1 and p2 is in the range from near 60% to 100%, the mirror displacement decreases as the fixed end position approaches the reflecting mirror. Further, the change amount of the mirror displacement when the fixed end position changes by a predetermined amount, in other words, the differential coefficient when the mirror displacement is regarded as a function of the fixed end position, the distance between p1 and p2 is 70% to 80%. % Is the largest in the region, and is the same in the other regions. Hereinafter, the change amount of the mirror displacement amount when the fixed end position changes by a predetermined amount is expressed as the stability of the mirror displacement amount. In addition, when the change amount of the mirror displacement amount is large, the stability of the mirror displacement amount is expressed as poor, and when the change amount is small, the stability of the mirror displacement amount is expressed as good.

  The position of the fixed end is easily changed by an attachment error when fixing the base body and the base, a processing error when processing the base body and the base, and the like. Then, the change in the position of the fixed end leads to a change in the mirror displacement amount of the optical scanner, as shown in FIG. Considering mass production of optical scanners, it is desirable that the individual difference in mirror displacement is small. Since the position of the fixed end easily changes for each individual, the stability of the mirror displacement needs to be good in order to reduce the individual difference in the mirror displacement. However, as shown in FIG. 13, there is no region in which the mirror displacement amount is stable regardless of how the fixed end position is adjusted.

  As described above, the optical scanner is desired to have two points: (1) a large amount of mirror displacement and (2) good stability of the mirror displacement. However, it has been difficult for conventional optical scanners to meet these two requirements simultaneously. In particular, no matter how the position of the fixed end of the conventional optical scanner is adjusted, it is impossible to improve the stability of the mirror displacement.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical scanner that obtains a large mirror displacement amount and has a good stability of the mirror displacement amount, and an image display device using the optical scanner.

  In order to achieve this object, the invention described in claim 1 is provided with a reflection mirror that is driven to resonate around the oscillation axis and scans incident light in a predetermined direction, and is disposed on the oscillation axis, and the reflection thereof. A pair of first elastic beams coupled to both sides of the mirror, a pair of beam portions symmetrical with respect to the swing axis, and a coupling portion in which both the beam portions are coupled, and the coupling portion includes the pair of first elastic beams. A base having a pair of second elastic beams connected to each of the first elastic beams and an outer frame connected to the pair of beams, and in the thickness direction of the base, A fixed pedestal, a drive unit for resonantly driving the reflection mirror, the pair of first elastic beams, and the pair of second elastic beams, and the outer frame unit and the pair of beam units are connected to each other. Provided around at least one of the outer frame portion and the pedestal. Between the void portion and an extension line extending in parallel with the swing axis from each of the pair of beam portions, a fixed portion provided in the void portion and fixed to the outer frame portion and the pedestal. It is characterized by comprising.

  According to a second aspect of the present invention, in the first aspect of the present invention, a pair of the first elastic beams are provided to support the reflection mirror at both ends, and the second elastic beams are a pair of the first elastic beams. In order to be connected to each of the first elastic beams, a pair is provided.

  According to a third aspect of the present invention, a reflection mirror that is driven to resonate around the oscillation axis and that scans incident light in a predetermined direction is arranged symmetrically with respect to the oscillation axis, and is disposed on one side of the reflection mirror. A base body having a pair of beam portions connected at each other, an outer frame portion to which the other side of the pair of beam portions is connected, and a base fixed to the outer frame portion in the thickness direction of the base body, A drive unit for resonantly driving the reflection mirror and the pair of beam parts; and a periphery of a connection position where the outer frame part and the pair of beam parts are connected, the outer frame part and the pedestal Between the space portion provided in at least one and the extension line extending in parallel with the swing axis from each of the pair of beam portions, provided in the space portion, and fixed to the outer frame portion and the pedestal And a fixed part.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the pair of beam portions are provided as a pair in order to support both of the reflection mirrors.

  The invention according to claim 5 is the invention according to claim 2 or 4, wherein the drive unit is a pair of piezoelectric bodies fixed to the pair of beam portions and the outer frame portion, and the pair of piezoelectric members. The body is provided with line symmetry with respect to the swing axis, and with a position on the same side with respect to the swing axis with respect to the reflection mirror or point symmetry with respect to the reflection mirror.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the fixing portion includes an oscillation axis and is located in a plane parallel to the thickness direction of the outer frame portion. And extending along the swing axis.

  The invention according to claim 7 is the invention according to claim 6, wherein the void portion is a notch provided in the pedestal, and the fixing portion is a protrusion extending from the notch. It is characterized by that.

  The invention according to claim 8 is the invention according to claim 6, wherein the void portion is provided on a surface of the outer frame portion that is fixed to the pedestal and is provided on a surface of the outer frame portion. And the fixing portion has the same thickness as that of the outer frame portion provided in the concave groove.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein at least a part of the fixing portion is sandwiched between the pair of beam portions at the connection position. It extends to the end of the part.

  The invention according to claim 10 is the invention according to any one of claims 1 to 9, wherein the fixing portion is in a direction orthogonal to a thickness direction of the outer frame portion and a direction of the swing axis. It is characterized in that the resonance frequency of the resonance drive can be adjusted by changing the width.

  The invention described in claim 11 is an optical scanner according to any one of claims 1 to 10 for forming an image by scanning light, and a light source for supplying light to the optical scanner. And an eyepiece optical system for guiding the light scanned by the optical scanner to the eyes of the user.

  In the first aspect of the present invention, a space portion is provided around the connection position where the outer frame portion and the pair of beam portions are connected, and at least one of the outer frame portion and the pedestal is provided, and the pair of beam portions A fixed portion is provided in the void portion between the extension lines extending in parallel with the swing axis from each of the two. By providing the void portion and the fixed portion, it is possible to achieve both a large mirror displacement amount and a good stability of the mirror displacement amount.

  In the invention according to claim 2, the first elastic beam supports the reflection mirror at both ends. When the reflection mirror is cantilevered, when the reflection mirror is driven to oscillate, movements other than oscillating about the oscillating axis, such as vibration in the thickness direction of the substrate, are likely to occur. Therefore, it is difficult for the light scanning direction to be a straight line. Since the reflection mirror is supported at both ends by the first elastic beam arranged on the swing axis, that is, symmetrically supported, the movement of the reflection mirror is limited to swing about the swing axis. As a result, it becomes easy to make the light scanning direction straight.

  In the invention according to claim 3, a space is provided around at least one of the outer frame part and the pedestal around the connection position where the outer frame part and the pair of beam parts are connected, and the pair of beam parts A fixed portion is provided in the void portion between the extension lines extending in parallel with the swing axis from each of the two. By providing the void portion and the fixed portion, it is possible to achieve both a large mirror displacement amount and a good stability of the mirror displacement amount.

  In a fourth aspect of the present invention, the pair of beam portions support the reflection mirror at both ends. Since the reflecting mirror is supported at both ends, the movement of the reflecting mirror is limited to the swinging around the swinging axis, and the light scanning direction can be easily made straight, similarly to the effect of the second aspect. Become.

  According to a fifth aspect of the present invention, the driving unit is a piezoelectric body fixed to a pair of beam portions, and a part of the piezoelectric body is fixed to the outer frame portion. Since a piezoelectric body is used, the optical scanner can be miniaturized.

  In the invention of claim 6, the fixed portion is positioned in a plane parallel to the thickness direction of the outer frame portion including the swing axis, and is disposed so as to extend along the swing axis. The pair of beam portions are configured symmetrically with respect to the swing axis. Therefore, it is considered that the place sandwiched between the pair of beam portions of the outer frame portion is deformed with the position of the swing axis as a node when the base body is driven to resonate. Therefore, the base and the pedestal are fixed at the position of the node by the arrangement of the fixing portion along the swing axis, and a large mirror displacement amount and a good mirror displacement amount stability are achieved.

  In the invention described in claim 7, the void portion is a notch provided in the pedestal, and the fixing portion is a protrusion extending from the notch. Therefore, the void portion and the fixed portion can be created by a simple operation of changing the contour line when processing the pedestal.

  In the invention according to claim 8, the void portion is a concave groove provided on a surface of the outer frame portion fixed to the pedestal, and the fixing portion is a thick portion provided in the concave groove. Since the void portion and the fixing portion are provided on the base side, the positional relationship between the pair of beam portions and the void portion and the fixing portion is determined with high accuracy without depending on the bonding position between the base body and the base. Therefore, it is possible to achieve both the large mirror displacement amount and the good mirror displacement amount stability without being influenced by the bonding position between the base and the base.

  In the invention according to claim 9, at least a part of the fixing portion extends to an end portion of the outer frame portion sandwiched between the pair of beam portions at a connection position where the outer frame portion and the pair of beam portions are connected. Yes. As a result, as shown in FIG. 5, which will be described later, the mirror displacement amount is maximized and the mirror displacement amount is most stable.

  The resonance frequency of the optical scanner varies due to accuracy problems when processing the substrate. In the tenth aspect of the present invention, since the fixed portion is configured to be able to adjust the resonance frequency of the resonance drive, a desired resonance frequency can be obtained regardless of this variation.

  In the invention according to claim 11, the optical scanner according to any one of claims 1 to 10 is used for an image display device. Since the improvement of the swing angle leads to an improvement of the display screen and the number of display pixels, it is possible to provide an image display device capable of displaying a more powerful and precise image.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
FIG. 1 is a perspective view of an optical scanner 100 according to the first embodiment of the present invention. In FIG. 1, the optical scanner 100 is shown in a state in which a base 110 and a pedestal 120 are separated. 2A and 2B are plan views of the base 110 and the pedestal 120. FIG. Here, the y-axis in the figure is a direction parallel to the oscillation axis AoR1 of the optical scanner 100, the z-axis is a direction parallel to the thickness direction of the base 110 and the pedestal 120, and the x-axis is a direction orthogonal to the y-axis and the z-axis. It is. The optical scanner 100 is configured by bonding a base 110 and a pedestal 120 in the z-axis direction shown in FIG. Hereinafter, the structure of the base 110 and the pedestal 120 will be described. The base 110 and the pedestal 120 described above are examples of the base and the pedestal of the present invention.

[Configuration of Optical Scanner 100]
The base 110 includes a reflection mirror 111, a first elastic beam 112, a second elastic beam 113, and an outer frame portion 114. The base 110 is provided with a piezoelectric element 130 and a lower electrode 131 and an upper electrode 132 for driving the piezoelectric element 130. The reflection mirror 111 formed in a substantially circular shape in plan view is provided at the center of the base 110 so that the position of the center of gravity is located on the swing axis AoR1. The first elastic beams 112 extending parallel to the y-axis are respectively connected to both sides of the reflection mirror 111 so as to include the swing axis AoR1. The second elastic beam 113 includes a coupling portion 113a and a pair of beam portions 113b. The coupling portion 133a is connected so as to be orthogonal to the first elastic beam 112, and extends parallel to the x-axis so as to be symmetric with respect to the swing axis AoR1. The pair of beam portions 113b extending in parallel to the y-axis are disposed so as to be symmetric about the swing axis AoR1. The pair of beam portions 113b are connected so that one end thereof is orthogonal to the coupling portion 113a and the other end thereof is orthogonal to the outer frame portion 114. The outer frame portion 114 is disposed in the shape of a square ring around the reflection mirror 111, the first elastic beam 112, and the second elastic beam 113. That is, the outer frame portion 114 includes a pair of sides parallel to the y axis and a pair of sides parallel to the x axis. The reflection mirror 111, the first elastic beam 112, the second elastic beam 113, the outer frame portion 114, the coupling portion 133a, the pair of beam portions 113b, and the piezoelectric element 130 are included in the reflection mirror of the present invention. It is an example of a 2nd elastic beam, a connection part, a pair of beam part, and a drive part.

  The piezoelectric element 130 is provided on the base 110 in order to drive the reflection mirror 111, the first elastic beam 112, and the second elastic beam 113 in resonance. Specifically, the piezoelectric element 130 is formed on the lower electrode 131 formed from the upper surface of the pair of beam portions 113 b to the outer frame portion 114. That is, the piezoelectric element 130 is fixed to the pair of beam portions 113b and the outer frame portion 114 via the lower electrode 131. An upper electrode 132 is provided on the upper surface of the piezoelectric element 130. When a voltage is periodically applied between the lower electrode 131 and the upper electrode 132, the piezoelectric element 130 is polarized and expands and contracts in the y-axis direction. Since the piezoelectric element 130 is fixed to the pair of beam portions 113b and the outer frame portion 114 via the lower electrode 131, the expansion and contraction of the piezoelectric element 130 in the y-axis direction is the bending displacement of the pair of beam portions 113b in the z-axis direction. Is converted to That is, the piezoelectric element 130 functions as a unimorph. The bending displacement in the z-axis direction of the pair of beam portions 113b is converted into rotational torque for swinging the first elastic beam 112 and the reflection mirror 111 via the coupling portion 113a.

  The configuration of the pedestal 120 will be described with reference to FIG. The pedestal 120 is formed so that the length in the x-axis direction and the y-axis direction is the same as that of the base body 110. The pedestal 120 includes a base fixing part 121, a notch 122, and a fixing protrusion 123. The base body fixing portion 121 is for fixing to the outer frame portion 114 of the base body 110, and has a quadrangular annular structure like the outer frame portion 114. That is, the base fixing part 121 includes a pair of sides parallel to the y axis and a pair of sides parallel to the x axis. The notches 122 are rectangular notches provided on a pair of sides parallel to the x-axis of the base fixing portion 121. The notches 122 are provided so as to be symmetric with respect to a plane including the swing axis AoR1 and parallel to the z-axis. The fixing protrusion 123 is a convex protrusion that extends from the notch 122 in parallel to the y-axis. The fixing protrusions 123 are provided in a plane that includes the swing axis AoR1 and is parallel to the z axis, and extends along the swing axis AoR1. Specifically, the fixing protrusions 123 are provided so as to be symmetrical about the swing axis AoR1. The notch 122 and the fixing protrusion 123 described above are examples of the void portion and the fixing portion of the present invention.

  The optical scanner 100 of the present embodiment scans incident light in a predetermined direction by being resonantly driven. Specifically, an AC voltage that matches the resonance frequency of the optical scanner 100 is applied between the lower electrode 131 and the upper electrode 132, so that the optical scanner 100 is driven to resonate. The resonance driving method is classified into in-phase driving and out-of-phase driving depending on the phase of the AC voltage applied to the piezoelectric element 130. In-phase driving is performed by two piezoelectric elements positioned on the same side with respect to the swing axis AoR1 with the reflection mirror 111 interposed therebetween, for example, two piezoelectric elements positioned in the x-axis positive direction with respect to the swing axis AoR1 in FIG. This is achieved by applying in-phase alternating currents to the elements. In the different phase drive, AC voltages of opposite phases are applied to two piezoelectric elements positioned in line symmetry with respect to the swing axis AoR1, for example, two piezoelectric elements positioned in the positive direction of the y axis with respect to the reflection mirror 111 in FIG. That is, this is achieved by applying alternating currents whose phases are shifted by π / 2. In the out-of-phase driving, an AC voltage having a reverse phase is applied to two piezoelectric elements that exist in point symmetry with respect to the reflecting mirror 111, for example, two piezoelectric elements that are located in the upper right and lower left of the reflecting mirror 111 in FIG. May be achieved.

[Method for Manufacturing Optical Scanner 100]
A method for manufacturing the optical scanner 110 will be described below. First, the manufacturing method of the base | substrate 110 is demonstrated using FIG. FIG. 3A shows the base body 110 on which the reflecting mirror 111, the first elastic beam 112, the second elastic beam 113, and the outer frame portion 114 are formed. First, on a thin rectangular silicon substrate having a thickness of about 30 μm to 200 μm, portions corresponding to the reflecting mirror 111, the first elastic beam 112, the second elastic beam 113, and the outer frame portion 114 are masked. The resist film is formed. Then, the silicon base material on which the resist film is formed is etched to form the reflection mirror 111, the first elastic beam 112, the second elastic beam 113, and the outer frame portion 114. Finally, the base film 110 is manufactured by removing the resist film.

  Next, a method for manufacturing the piezoelectric element 130, the lower electrode 131, and the upper electrode 132 will be described with reference to FIG. 3B shows a state where the lower electrode 131 is formed on the base 110, FIG. 3C shows a state where the piezoelectric element 130 is formed on the lower electrode 131, and FIG. A state in which the upper electrode 132 is formed on the element 130 is shown. As shown in FIG. 3B, the lower electrode 131 is made of platinum (Pt), gold (Au), or the like with a thickness of 0.2 μm to 0.6 μm from the upper surface of the pair of beam portions 113 b to the outer frame portion 114. It is formed by depositing. As shown in FIG. 3C, the piezoelectric element 130 is formed by depositing a piezoelectric element such as PZT with a thickness of 1 μm to 3 μm on the lower electrode 131 from the upper surface of the pair of beam portions 113 b to the outer frame portion 114. It is formed by doing. As shown in FIG. 3D, the upper electrode 132 is formed by depositing platinum (Pt), gold (Au), or the like on the piezoelectric element 130 to a thickness of 0.2 μm to 0.6 μm. . The lower electrode 131 and the upper electrode 132 are formed by sputtering or vapor deposition, and the piezoelectric element 130 is formed by spraying nano-sized fine particles, for example, an aerosol deposition method (see, for example, JP-A-2007-91416). ) And the like.

  The pedestal 120 is obtained by blasting a glass plate. Specifically, the pedestal 120 is formed by carrying out processing by causing a granule to collide with a rectangular glass plate so that the base fixing portion 121, the notch 122, and the fixing protrusion 123 are formed.

  The optical scanner 110 is formed by fixing the outer frame portion 114 of the base 110 and the base fixing portion 121 of the pedestal 120 by bonding, anodic bonding, or the like. At this time, the periphery of the connection position between the outer frame portion 114 and the pair of beam portions 113 b is not fixed to the base fixing portion 121 because the notch 122 exists in the pedestal 120. However, since the fixing protrusion 123 exists in the notch 122, the outer frame portion 114 and the base body fixing portion 121 are fixed between the extension lines extending in parallel to the swing axis AoR1 from each of the pair of beam portions 113b. Is done.

[Verification of mirror displacement and its stability]
In the present embodiment, since the fixing protrusion 123 is provided on the pedestal 120, it is possible to achieve both a large mirror displacement amount and stability of the mirror displacement amount. In order to investigate the relationship between the shape of the fixing protrusion 123 and the mirror displacement, an embodiment simulation was performed. Hereinafter, the results of this embodiment simulation will be described with reference to FIGS.

  FIG. 4 is a diagram for explaining how the widths of the fixing protrusions 123 in the x-axis direction and the y-axis direction are changed. 4A to 4D, the distance between the pair of beam portions 113b in the x-axis direction is DS1, the width of the fixing projection 123 in the x-axis direction is DS2, and the width of the notch 122 in the y-axis direction is The width of DS3 and the fixing protrusion 123 in the y-axis direction is expressed as DS4. As DS2 and DS4 change, the change in the mirror displacement amount is examined. For example, when DS2 has a width of 50% of DS1 and DS4 has a width of 50% of DS3, the fixing protrusion 123 has a shape shown in FIG. When DS2 and DS1 are equal and DS4 is 50% of the width of DS3, the fixing protrusion 123 has a shape shown in FIG. When DS2 is 50% of the width of DS1 and DS4 and DS3 are equal, the fixing protrusion 123 has a shape shown in FIG. When DS2 and DS1 are equal and DS4 and DS3 are equal, the fixing projection 123 has a shape shown in FIG. The state in which DS2 and DS1 are equal means a state in which at least a part of the fixing projection 123 extends to the end of the outer frame portion 114 sandwiched between the pair of beam portions 113b at the connection position. .

  FIG. 5 is a diagram illustrating a result of an embodiment simulation of how the mirror displacement changes when DS3 and DS4 are changed. The horizontal axis indicates the ratio between DS4 and DS3. When the horizontal axis is 0%, the fixing projection 123 does not exist, that is, the same shape as that of the conventional optical scanner 600. Further, when the horizontal axis is 100%, DS4 and DS3 are equal. The vertical axis indicates how much the mirror displacement amount has increased with respect to the conventional optical scanner 600. When DS2 is 50% of the width of DS1, it is indicated as PLT1 using x and a straight line. When DS2 is 75% of the width of DS1, it is indicated as PLT2 using black triangles and straight lines. When DS2 and DS1 are equal, it is indicated as PLT3 using a black square and a straight line. For reference, the conventional example shown in FIG. 12 is also shown using dotted lines.

  In FIG. 5, the mirror displacement increases monotonously as the ratio of DS4 and DS3, that is, the width of the fixing projection 123 in the y-axis direction increases. In the region where the ratio of DS4 to DS3 exceeds 80%, the mirror displacement increases only slightly, as can be seen from the fact that the slope of the graph is substantially flat in FIG. Further, when the ratio of DS2 to DS1, that is, the width of the fixing projection 123 in the x-axis direction is changed, the mirror displacement amount increases as the width in the x-axis direction increases. As is apparent from FIG. 5, the optical scanner 100 according to the present embodiment can obtain a large mirror displacement amount and has good stability of the mirror displacement amount. In particular, the stability of the mirror displacement amount is generally better than that of the conventional example, and is best in a region where the ratio of DS4 to DS3 exceeds 80%.

[Description of Image Display Device 1]
The overall configuration and operation of the image display apparatus 1 using the optical scanner 100 of this embodiment will be described. FIG. 6 shows the overall configuration of the image display apparatus 1 according to the first embodiment. The image display device 1 is a device for causing a viewer to visually recognize a virtual image by causing a light beam to enter the pupil 52 of the viewer and projecting an image on the retina 54. This device is also called a retinal scanning display.

  The image display apparatus 1 includes a light beam generation unit 2, an optical fiber 19, a collimating optical system 20, an optical scanner 100, a first relay optical system 22, a vertical scanning unit 23, and a second relay optical system 24. The light beam generation means 2 is composed of a video signal processing circuit 3, a light source unit 30, and an optical multiplexing unit 40. The video signal processing circuit 3 generates a B signal, a G signal, an R signal, a horizontal synchronization signal, and a vertical synchronization signal, which are elements for combining images, based on a video signal supplied from the outside.

  The light source unit 30 includes a B laser driver 31, a G laser driver 32, an R laser driver 33, a B laser 34, a G laser 35, and an R laser 36. The B laser driver 31 drives the B laser 34 so as to generate a blue light beam having an intensity corresponding to the B signal from the video signal processing circuit 3. The G laser driver 32 drives the G laser 35 so as to generate a green light beam having an intensity corresponding to the G signal from the video signal processing circuit 3. The R laser driver 33 drives the R laser 36 so as to generate a red light beam having an intensity corresponding to the R signal from the video signal processing circuit 3. The B laser 34, the G laser 35, and the R laser 36 can be configured as, for example, a semiconductor laser or a solid-state laser with a harmonic generation mechanism. The light source unit 30 described above is an example of the light source of the present invention.

  The optical multiplexing unit 40 includes collimating optical systems 41, 42, and 43 provided to collimate laser light incident from the light source unit 30 into parallel light, and a dichroic mirror 44 for multiplexing the collimated laser light. , 45, 46, and a coupling optical system 47 that guides the combined laser beam to the optical fiber 19. The blue laser light emitted from the B laser 34 is collimated by the collimating optical system 41 and then enters the dichroic mirror 44. The green laser light emitted from the G laser 35 enters the dichroic mirror 45 through the collimating optical system 42. The red laser light emitted from the R laser 36 enters the dichroic mirror 46 through the collimating optical system 43. The three primary color laser beams respectively incident on the dichroic mirrors 44, 45, and 46 are reflected or transmitted in a wavelength-selective manner and are combined as one light beam, and reach the condensing optical system 47. The laser light combined as one light beam is condensed by the condensing optical system 47 and enters the optical fiber 19.

  The horizontal scanning driver 61 drives the optical scanner 100 according to the horizontal synchronization signal from the video signal processing circuit 3. The vertical scanning driver 62 drives the vertical scanning scanner 23 according to the vertical synchronization signal from the video signal processing circuit 3. The laser light is converted into a light beam scanned in the horizontal direction and the vertical direction by the scanning of the optical scanner 100 and the vertical scanning scanner 23, and can be projected as an image. Specifically, laser light emitted from the optical fiber 19 is converted into parallel light by the collimating optical system 20 and then guided to the optical scanner 100. The laser beam scanned in the horizontal direction by the optical scanner 100 passes through the first relay optical system 22 and then enters the vertical scanning scanner 23 as parallel rays. At this time, an optical pupil is formed at the position of the vertical scanning scanner 23 by the first relay optical system 22. The laser beam scanned in the vertical direction by the vertical scanning scanner 23 passes through the second relay optical system 24 and then enters the observer's pupil 52 as parallel rays. At this time, the observer's pupil 52 and the optical pupil at the position of the vertical scanning scanner 23 are conjugated by the second relay optical system 24. The above-described second relay optical system 24 is an example of an eyepiece optical system according to the present invention.

<Second Embodiment>
In the first embodiment, the mirror displacement amount and the configuration for stabilizing the mirror displacement amount are a notch 122 and a fixing protrusion 123 provided in the pedestal 120. On the other hand, in the present embodiment, the mirror displacement amount and the configuration for stabilizing the mirror displacement amount are the concave groove 215 and the thick portion 216 provided in the outer frame portion 214 of the base body 210.

  FIG. 7 is a view showing the base 210 and the pedestal 220 constituting the optical scanner in the present embodiment. FIG. 7A is a plan view of the base 210. The base 210 includes a reflection mirror 211, a first elastic beam 212, a second elastic beam 213, and an outer frame portion 214. The base 210 is provided with a piezoelectric element 230 and a lower electrode 231 and an upper electrode 232 for driving the piezoelectric element 230. Since these structures are the same as the corresponding structure of 1st Embodiment shown by Fig.2 (a), description is abbreviate | omitted here.

  FIG. 7B is a bottom view of the base 210. The base body 210 in the present embodiment is different from the base body 110 in the first embodiment in that a concave groove 215 and a thick part 216 are provided on the bottom surface. The recessed groove 215 is a recessed groove having a depth smaller than the thickness of the outer frame portion 214 provided on the surface of the outer frame portion 214 that is fixed to the pedestal 220. The concave groove 215 is formed by etching. The thick portion 216 is a portion provided in the concave groove 215 and having the same thickness as the outer frame portion 214. The concave groove 215 and the thick portion 216 described above are examples of the void portion and the fixing portion of the present invention.

  FIG. 7C is a bottom view of the pedestal 220. The pedestal 220 is formed so that the length in the x-axis direction and the y-axis direction is the same as that of the base body 210. The pedestal 220 includes only the base fixing part 221 for fixing to the base 210, and does not have a notch or the like unlike the pedestal 120 in the first embodiment.

  When the base 210 is fixed to the pedestal 220, the periphery of the connection position between the outer frame portion 214 and the second elastic beam 213 is not fixed to the base fixing portion 221 because the base 210 has the concave groove 215. However, since the thick groove portion 216 exists in the concave groove 215, the outer frame portion 214 and the base body fixing portion 221 are between the extension lines extending in parallel to the swing axis AoR2 from each of the second elastic beams 213. Fixed. Therefore, also in the optical scanner including the base 210 and the pedestal 220 according to the present embodiment, as in the first embodiment, it is possible to obtain an effect that a large mirror displacement amount can be obtained and the mirror displacement amount stability is good. .

<Modification>
In the first and second embodiments described above, the substrate 110 and the substrate 210 are obtained by processing a silicon substrate. However, not only silicon but also a semiconductor substrate generally made of a semiconductor may be used. Furthermore, instead of the semiconductor substrate, for example, a substrate made of a stainless steel plate may be adopted. In general, the substrate is not limited to a silicon substrate, and may be a single substrate.

  As shown in FIG. 5, the change in the width of the fixing projection 123 in the x-axis direction and the y-axis direction changes the mirror displacement amount in the first embodiment. Changes in the width of the fixing projection 123 in the x-axis direction and the y-axis direction change not only the mirror displacement but also the resonance frequency of the optical scanner 100 as shown in FIG. FIG. 8 is a diagram showing a simulation result of how the resonance frequency of the optical scanner 100 in the first embodiment changes when DS3 and DS4 are changed. The horizontal axis is the same as in FIG. 5 and shows the ratio of DS4 and DS3. The vertical axis indicates how much the resonance frequency of the optical scanner 100 has increased with respect to the conventional optical scanner 600. Similarly to FIG. 5, when the ratio of DS2 to DS1 is 50%, 75%, and 100%, PLT4 using x and a straight line, PLT5 using a black triangle and a straight line, black square and straight line Are indicated as PLT6 using In FIG. 8, the resonance frequency monotonously increases as the ratio of DS4 and DS3, that is, the width of the fixing protrusion 123 in the y-axis direction increases. Further, when the ratio of DS2 to DS1, that is, the width of the fixing projection 123 in the x-axis direction is changed, the mirror displacement amount increases as the width in the x-axis direction increases. Accordingly, when processing the pedestal 120, the resonance frequency of the optical scanner 100 can be adjusted by changing at least one of the width in the x-axis direction and the width in the y-axis direction of the fixing protrusion 123.

  In the second embodiment, the concave groove 215 and the thick part 216 are provided in the base 210. However, the pedestal 220 may be provided with a concave groove and a thick portion.

  In the base 110 of the first embodiment, the reflection mirror 111 is connected to the outer frame portion 114 via a first elastic 112 beam and a second elastic beam 113 connected to both sides. The second elastic beam 113 includes a pair of beam portions 113b and a coupling portion 113a that couples the pair of beam portions 113b and the first elastic beam 112. However, the shape of the substrate may be other shapes. As an example, the shape of the substrate 310 will be described with reference to FIG.

  The base 310 includes a reflection mirror 311, a pair of beam portions 313 b and an outer frame portion 114. The base 310 is provided with a piezoelectric element 330 and a lower electrode 331 and an upper electrode 332 for driving the piezoelectric element 330. In the base 310, the reflection mirror 311 and the outer frame portion 114 are connected by the pair of beam portions 313b without using the first elastic beam and the coupling portion as in the above-described embodiment. The base 310 is fixed to the pedestal 120 shown in FIG. 2B by bonding, anodic bonding, or the like, whereby an optical scanner is formed. In this optical scanner, the outer frame portion 314 and the base fixing portion 121 are fixed between the extension lines extending in parallel to the swing axis AoR1 from each of the pair of beam portions 313b. A large mirror displacement amount can be obtained, and an effect that the stability of the mirror displacement amount is good can be obtained. The base 310 may be provided with a concave groove and a thick portion on the bottom surface, like the base 210 shown in FIG. In this case, the optical scanner is formed by fixing the base 310 to the pedestal 220 shown in FIG. 7C by bonding, anodic bonding, or the like.

  The bases 110, 210, and 310 described above have a structure in which the reflection mirror is supported at both ends. However, a cantilever support configuration as shown in FIG. 1 of Japanese Patent Laid-Open No. 7-65098, in which the reflection mirror is supported only on one side, may be used. The point is that a void portion is provided around the connection position between the pair of beam portions and the outer frame portion, and between the extension lines extending in parallel to the swing axis from each of the pair of beam portions, A fixing part may be provided.

  In both the embodiments and the modification shown in FIG. 9, both sides of the reflecting mirrors 111, 211, and 311 are symmetrical structures supported by a combination of beams having the same structure. An asymmetric structure supported by the combination may be used. For example, the first and second elastic beams employed in both embodiments are used to support one side of the reflecting mirror, and the pair of beam portions shown in FIG. 9 are used to support the other side. May be used.

1 is a perspective view of an optical scanner 100 according to a first embodiment of the present invention. The top view of the base | substrate 110 and the base 120. FIG. The figure explaining the process in which the lower electrode 131, the piezoelectric element 130, and the upper electrode 132 are formed on the base | substrate 110. FIG. The figure explaining how the width | variety of the x-axis direction and the y-axis direction of the protrusion 123 for fixation was changed. The figure which shows the relationship between the size of the processus | protrusion 123 for fixation, and mirror displacement amount. The figure which shows the whole structure of the image display apparatus 1 in 1st Embodiment. The top view and bottom view of the base | substrate 210, and the top view of the base 220. FIG. The figure which shows the relationship between the size of the processus | protrusion 123 for fixation, and the resonant frequency of the optical scanner 100. FIG. The figure which showed the modification of the base | substrate shape. FIG. 10 is a diagram showing an example of a conventional optical scanner in Patent Document 1. FIG. 10 is a diagram illustrating an example of a conventional optical scanner in Patent Document 2. The bottom face schematic diagram around the connection part of the 2nd elastic beam and outer frame part of the conventional optical scanner. The figure which shows the result of a prior art example simulation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image display apparatus 2 Light beam production | generation means 3 Video signal processing circuit 3
19 Optical fibers 20, 41, 42, 43 Collimating optical system 22 First relay optical system 23 Vertical scanning scanner 24 Second relay optical system 30 Light source unit 31 B laser driver 32 G laser driver 33 B laser driver 34 B laser 35 G laser 35 R laser 40 Optical multiplexing units 44, 45, 46 Dichroic mirror 47 Condensing optical system 52 Observer pupil 54 Retina of observer 61 Horizontal scanning driver 62 Vertical scanning driver 100, 500, 600 Optical scanners 110, 210, 310, 510, 610 Base 111, 211, 311, 511, 611 Reflection mirror 112, 212, 512, 612 First elastic beam 113, 213, 513, 613 Second elastic beam 113a Joint portion 113b, 313b A pair of beams 114, 214, 314, 514, 614 outer frame 20, 220, 520, 620 Base 121, 221, 521, 621 Base fixing part 122, 622 Notch 123 Fixing protrusion 130, 230, 330, 530, 630 Piezoelectric element 131, 231, 331 Lower electrode 132, 232, 332 Upper electrode 215 Concave groove 216 Thick part AoR1, AoR2, AoR3, AoR5, AoR6 Oscillation axis

Claims (11)

A reflection mirror that is driven to resonate around the oscillation axis and scans incident light in a predetermined direction, a first elastic beam that is disposed on the oscillation axis and is connected to the reflection mirror, and the oscillation axis A pair of symmetrical beam portions and a coupling portion in which both the beam portions are coupled, and the coupling portion is coupled to the second elastic beam, and the pair of beam portions are coupled to each other. A base body having an outer frame portion;
A pedestal fixed to the outer frame portion in the thickness direction of the base;
A drive unit for resonantly driving the reflection mirror, the first elastic beam, and the second elastic beam;
A space provided around at least one of the outer frame part and the pedestal, around a connection position where the outer frame part and the pair of beam parts are connected;
Between the extension lines extending in parallel to the swing axis from each of the pair of beam portions, provided in the void portion, and provided with a fixed portion fixed to the outer frame portion and the pedestal,
An optical scanner characterized by that. A pair of the first elastic beams are provided to support the reflection mirror at both ends,
A pair of the second elastic beams are provided to be connected to each of the pair of first elastic beams.
The optical scanner according to claim 1. A reflection mirror that is driven to resonate around the oscillation axis and scans incident light in a predetermined direction; and a pair of beams that are arranged symmetrically with respect to the oscillation axis and connected to the reflection mirror on one side; An outer frame portion to which the other side of the pair of beam portions is coupled, and a base body,
A pedestal fixed to the outer frame portion in the thickness direction of the base;
A drive unit for resonantly driving the reflection mirror and the pair of beam parts;
A space provided around at least one of the outer frame part and the pedestal, around a connection position where the outer frame part and the pair of beam parts are connected;
Between the extension lines extending in parallel to the swing axis from each of the pair of beam portions, provided in the void portion, and provided with a fixed portion fixed to the outer frame portion and the pedestal,
An optical scanner characterized by that. The pair of beam portions are provided in a pair to support the reflection mirror at both ends.
The optical scanner according to claim 3. The drive unit is a pair of piezoelectric bodies fixed to the pair of beam portions and the outer frame portion,
The pair of piezoelectric bodies are provided symmetrically with respect to the swing axis, and positioned symmetrically with respect to the swing axis with respect to the swing mirror, or point-symmetric with respect to the reflection mirror.
The optical scanner according to claim 2, wherein the optical scanner is an optical scanner. The fixing part is
Located in a plane that includes a swing axis and is parallel to the thickness direction of the outer frame portion,
Extending along the swing axis,
The optical scanner according to claim 1, wherein the optical scanner is an optical scanner. The void portion is a notch provided in the pedestal,
The fixing portion is a protrusion extending from the notch,
The optical scanner according to claim 6. The void portion is a recessed groove having a depth smaller than the thickness of the outer frame portion, provided on the surface of the outer frame portion fixed to the pedestal.
The fixing portion has the same thickness as the outer frame portion provided in the concave groove.
The optical scanner according to claim 6. At least a part of the fixed portion extends to an end portion of the outer frame portion sandwiched between the pair of beam portions at the connection position.
The optical scanner according to claim 1, wherein the optical scanner is an optical scanner. The fixing portion is configured to be able to adjust a resonance frequency of resonance driving by changing a width in a direction orthogonal to a thickness direction of the outer frame portion and a direction of the swing axis.
The optical scanner according to claim 1, wherein the optical scanner is an optical scanner. An optical scanner according to any one of claims 1 to 10 for scanning light to form an image;
A light source for supplying light to the optical scanner;
An eyepiece optical system for guiding the light scanned by the optical scanner to the eyes of the user,
An image display device characterized by that.

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