JP2005345837A - Method of manufacturing reflection mirror and reflection mirror - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology of manufacturing a reflection mirror with a wet etching method in the technology with which a plate reflection mirror having a reflection face to which light is made incident is manufactured by the etching. <P>SOLUTION: For manufacturing the reflection mirror by the etching, (a) a plate material to be etched composed of a single crystal is coated with a film etching mask material (S2), a mask pattern having a flat shape closer to a circle than a quadrangle is formed on the etching mask material coated on the material to be etched (S3), a wet etching is performed by immersing the material to be etched on which the etching mask material is coated into an etching liquid having a set density under a set temperature (S4), thus, the reflection mirror is manufactured having a flat shape of which the projected figure in a normal direction of the reflection mirror is closer to a circle than a quadrangle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for manufacturing a plate-like reflecting mirror having a reflecting surface on which light is incident by etching, and particularly to a technique for manufacturing the reflecting mirror by wet etching.

  For example, in the field of forming an image with light, a plate-like reflecting mirror having a reflecting surface on which light is incident may be used. This type of reflection mirror is used for various applications. For example, one type of reflection mirror of this type is used to scan the light by changing the reflection direction of the light incident on the reflection surface by being oscillated around an oscillation axis parallel to the reflection surface. used.

  One conventional example of this type of reflection mirror already exists (see, for example, Patent Document 1). This conventional reflecting mirror forms a vibrating body together with a plate-like spring that extends from the reflecting mirror along the swing axis and generates at least a torsional vibration around the swing axis. When at least a part is vibrated, it is used for changing the reflection direction of the light incident on the reflection surface and scanning the light.

As disclosed in Patent Document 1, this conventional reflecting mirror has been manufactured so as to have a planar shape that forms a quadrangle with the swing axis of the reflecting mirror as a symmetric center line. Furthermore, this conventional reflecting mirror has been manufactured by etching. Etching types include dry etching and wet etching.
JP 2003-57586 A

  In the field of using this type of reflection mirror, there is a strong demand to increase the maximum swing speed at which the reflection mirror can be swung around the swing axis. Specifically, for example, in an image forming apparatus including a scanning unit that scans light using this type of reflecting mirror, it is strongly desired to increase the scanning speed of light in order to increase the resolution of the image. In order to increase the scanning speed, there is a case where it is desired to increase the rocking speed of the reflecting mirror.

  On the other hand, in order to increase the maximum swing speed of this type of reflection mirror, it is effective to reduce the moment of inertia of the reflection mirror around the swing axis.

  However, the conventional reflection mirror manufactured by wet etching has been manufactured so as to have a planar shape that forms a quadrangle with the oscillating axis of the reflection mirror as the center line of symmetry, as described above. For this reason, when this conventional reflecting mirror must be used, the reflecting mirror is compared with a circular reflecting mirror having the same lateral dimension to secure a reflecting area comparable to that of the conventional reflecting mirror. It was difficult to reduce the moment of inertia.

  When the reflecting mirror is manufactured by dry etching, the mask pattern can be easily miniaturized and the reflecting mirror can be easily manufactured in an arbitrary shape with high accuracy, compared with the case where the reflecting mirror is manufactured by wet etching. However, the production of reflection mirrors by dry etching is not sufficiently suitable for batch processing in which etching is collectively performed on a large number of materials to be etched that are used to produce a large number of reflection mirrors. Therefore, the production of the reflection mirror by dry etching is not sufficiently suitable for increasing the production efficiency of the reflection mirror and reducing the production cost.

  Against the background described above, the present invention has an object of providing a technique for manufacturing a reflection mirror by wet etching in a technique for manufacturing a plate-like reflection mirror having a reflection surface on which light is incident. It was made.

  The following aspects are obtained by the present invention. Each aspect is divided into sections, each section is given a number, and is described in a form that cites other section numbers as necessary. This is to facilitate understanding of some of the technical features that the present invention can employ and combinations thereof, and the technical features that can be employed by the present invention and combinations thereof are limited to the following embodiments. Should not be interpreted. That is, it should be construed that it is not impeded to appropriately extract and employ the technical features described in the present specification as technical features of the present invention although they are not described in the following embodiments.

  Further, describing each section in the form of quoting the numbers of the other sections does not necessarily prevent the technical features described in each section from being separated from the technical features described in the other sections. It should not be construed as meaning, but it should be construed that the technical features described in each section can be appropriately made independent depending on the nature.

(1) A reflecting mirror manufacturing method for manufacturing a plate-like reflecting mirror having a reflecting surface on which light is incident by etching,
A coating step of coating a film-like etching mask material on at least one of both surfaces of a plate-like material to be etched composed of a single crystal;
A mask pattern forming step of forming a mask pattern having a planar shape closer to a circle than a quadrangle on at least one of the etching mask materials coated on the material to be etched;
A wet etching step of performing etching by immersing the material to be etched coated with the etching mask material in an etching solution having a set concentration under a set temperature, thereby making the reflection mirror A reflection mirror manufacturing method for manufacturing the reflection mirror so that a projection figure obtained by projecting in the normal direction of the above has a planar shape closer to a circle than a quadrangle.

  According to this method, the reflecting mirror is manufactured so that the projection figure obtained by projecting the reflecting mirror in the normal direction thereof has a planar shape that is closer to a circle than a quadrangle. Therefore, according to this method, in a reflection mirror that requires a circular reflection region having a required reflection area as a minimum, it is possible to omit a useless reflection region more easily than a reflection mirror having a quadrangular projection pattern. Therefore, a reflecting mirror that is lighter and has a smaller moment of inertia than a reflecting mirror that uses a quadrangle as a projected figure can be easily manufactured.

  Furthermore, according to this method, the reflecting mirror is manufactured not by dry etching but by wet etching. Therefore, according to this method, it becomes easier to manufacture the reflection mirror with higher production efficiency and at a lower cost than when the reflection mirror is manufactured by dry etching.

  By the way, when the reflection mirror is manufactured by dry etching, the reflection mirror is manufactured so as to have the same shape as the mask pattern formed on the etching mask material coated on the surface of the material to be etched. On the other hand, when the reflecting mirror is manufactured by wet etching, the reflecting mirror is manufactured so as to have a shape different from the mask pattern. The reason is an etching rate difference existing between a plurality of crystal planes of the material to be etched.

  Therefore, when the method according to this section is performed, a mask pattern is formed in consideration of an etching rate difference existing between a plurality of crystal planes of the material to be etched based on the target shape of the reflecting mirror. In this method, since the reflecting mirror is finally manufactured so that the projection figure thereof has a planar shape that is closer to a circle than a quadrangle, the mask pattern is also a planar shape that is closer to a circle than a quadrangle. It is formed to have a shape that does not match the target shape.

  As described above, even when the reflection mirror is manufactured by wet etching, if the mask pattern is determined in consideration of an etching rate difference existing between a plurality of crystal planes, the reflection mirror is manufactured to have a target shape. It is possible.

  The method according to this section can be performed in such a manner that the coating step is performed by coating the etching mask on both surfaces of the material to be etched, or by coating only on one surface. In the case of carrying out the former mode, the mask pattern forming step forms a mask pattern on each of two etching masks coated on both surfaces of the material to be etched, or any one of the two etching masks. Only a mask pattern can be formed. In short, it is sufficient that the method according to this section is performed so that the mask pattern is formed on at least one of both surfaces of the material to be etched.

(2) The reflection mirror is used to scan the light by changing the reflection direction of the light incident on the reflection surface by being oscillated around a swing axis parallel to the reflection surface ( The method for producing a reflecting mirror as described in the item 1).

  According to this method, the reflection mirror used for scanning light can be manufactured by wet etching so as to have a projected figure that is closer to a circle than a quadrangle.

(3) The reflecting mirror constitutes a vibrating body together with a plate-like spring that extends from the reflecting mirror along the swing axis and generates at least torsional vibration around the swing axis. The method of manufacturing a reflecting mirror according to the item (2), which is used to change the reflection direction of the light incident on the reflecting surface by scanning at least a part of the light.

(4) The reflective mirror manufacturing method according to any one of (1) to (3), wherein the planar shape of the mask pattern is generally a convex octagon.

  According to this method, it is possible to manufacture a reflecting mirror having a generally projected octagon as a projected figure as a reflecting mirror that can reduce the moment of inertia more easily than a reflecting mirror having a quadrangle as a projected figure.

(5) The reflective mirror manufacturing method according to (4), wherein the planar shape of the mask pattern is a shape having a convex octagon as a basic shape and having protruding portions at eight corners of the octagon.

  According to this method, in the wet etching process of the material to be etched, the erosion of the portion of the material to be etched facing the corner portion of the mask pattern is delayed as compared with the case where the corner portion has no protrusion. A reflection mirror is manufactured to reflect this delay.

  The “protruding portion” in this section can have, for example, a shape extending from each corner portion in a regular octagon toward a region corresponding to the outer corner of each corner portion.

(6) The mask pattern has a first side parallel to one reference line and a second side orthogonal to the reference line, and the first side and the first side on the (100) crystal plane of the material to be etched. The two sides are positioned with respect to the material to be etched so as to be orthogonal to the <110> crystal direction,
The outline of the mask pattern is (100) of the material to be etched for each region when the material to be etched is divided into four regions by two symmetrical center lines orthogonal to each other at the center point of the mask pattern. The method for producing a reflecting mirror according to (4) or (5), comprising: a first portion corresponding to a crystal plane; and a second portion corresponding to a (111) crystal plane.

  In the present specification, the crystal plane is expressed as (abc). The crystal plane that is expressed by this notation is a narrowly defined crystal plane in consideration of the signs of the numbers a, b, and c in the description. It includes not only the equivalent crystal plane. That is, the (abc) crystal plane should be interpreted according to a comprehensive definition including a plurality of corresponding crystal planes.

  Then, if the method according to this section is implemented, a reflection mirror having a projected figure of an n-gon (n: an integer greater than or equal to 3) that exposes the (100) crystal plane and the (111) crystal plane is obtained. It becomes possible to produce.

(7) The outline of the mask pattern further includes, for each region, a third portion corresponding to the (n11) crystal plane (n: an integer of 2 or more) of the material to be etched, and the first portion. The reflecting mirror manufacturing method according to the item (6), which is provided between the second portion and the second portion.

  According to this method, when it is assumed that the outline of the projection figure of the reflecting mirror is composed only of the (100) crystal plane and the (111) crystal plane, the octagon indicated by the projection figure is represented by the eight octagons belonging to the octagon. It is possible to produce a reflection mirror having an n-gon shape (n: multiple of 8 greater than 8) as a projected figure obtained by partially scraping off at least one kind of another crystal plane at each corner. It becomes possible.

  Therefore, according to this method, it is possible to manufacture a reflection mirror having a planar shape that is closer to a circle than an octagon. Furthermore, according to this method, it is easy to approximate the projection pattern of the reflection mirror to a circle rather than a quadrangle. Therefore, in a reflection mirror that requires a required reflection area (a required lateral dimension) is required. As compared with the case where the reflecting mirror is square, a useless reflecting area is omitted, and as a result, it is easy to reduce the weight of the reflecting mirror and reduce the moment of inertia.

  The circularity of the reflection mirror is improved when there are a plurality of types of crystal planes exposed at each corner of the octagon, which is the virtual shape, as compared with the case where only one type is present. For example, when there is only one type of crystal plane to be exposed, the projection pattern of the reflection mirror is a hexagon, but when there are two types of crystal plane to be exposed, the projection pattern of the reflection mirror is 24. It becomes a square. The tendency that the degree of circularity of the reflecting mirror increases as the number of exposed crystal faces increases, the stress increases as the number of exposed crystal faces increases, and the method according to this section increases the number of exposed crystal faces. Suitable for that.

(8) The outline of the mask pattern further includes, for each region, a fourth portion corresponding to the (520) crystal plane of the material to be etched between the first portion and the second portion. (6) The reflecting mirror manufacturing method according to item (6).

  According to this method, when it is assumed that the outline of the projection figure of the reflection mirror is composed only of the (100) crystal plane and the (111) crystal plane, the octagon indicated by the projection figure has eight In each corner, it is possible to manufacture a reflecting mirror whose projected figure is a shape that is partially cut off so that the (520) crystal plane is mainly exposed. The projection pattern of the reflecting mirror that can be manufactured by this method has a shape close to a hexagon.

  Therefore, according to this method, it is possible to manufacture a reflection mirror having a planar shape that is closer to a circle than an octagon. Furthermore, according to this method, since the octagon is only one type of crystal plane that is exposed when the octagon is scraped off at each corner of the octagon, the number of types of crystal planes does not vary. The final shape of the reflecting mirror is stabilized.

(9) The reflecting mirror manufacturing method according to any one of (1) to (8), wherein the etching solution is KOH or TMAH.

(10) The reflective mirror manufacturing method according to (8), wherein the set concentration is in a range of 35 wt% to 45 wt%.

(11) The reflecting mirror manufacturing method according to (9) or (10), wherein the set temperature is in a range of 60 ° C. to 80 ° C.

(12) The mask pattern forming step includes a step of forming the mask pattern on two etching mask materials respectively coated on both surfaces of the material to be etched. The reflecting mirror manufacturing method of description.

  When the method according to any one of the above items (1) to (11) is carried out, for example, as shown in FIGS. May be produced.

  In this case, when wet etching is performed only from one surface of the material to be etched, for example, a continuous inclined surface is formed on the side surface of the material to be etched 400 ′ as shown in a longitudinal sectional view in FIG. The inclined surface is formed asymmetrically with respect to the center line in the thickness direction of the material to be etched 400 ′.

  On the other hand, when wet etching is performed from both surfaces of the material to be etched, a discontinuous inclined surface is formed on the side surface of the material 400 to be etched, for example, as shown in a longitudinal sectional view in FIG. The inclined surface is formed symmetrically with respect to the center line in the thickness direction of the material 400 to be etched.

  Therefore, if the results of these two types of wet etching are compared with each other with respect to the weight of the reflection mirror to be finally produced, the case where the latter double-side wet etching is performed is the case where the former single-side wet etching is performed. Thus, the weight of the reflecting mirror can be easily reduced. If the weight of the reflecting mirror is easily reduced, the moment of inertia of the reflecting mirror can be easily reduced.

  Based on the knowledge described above, in the method according to this item, a mask pattern is formed on each of two etching mask materials coated on both surfaces of the material to be etched. Mask patterns are formed on both surfaces of the material to be etched, and as a result, wet etching is performed from both surfaces of the material to be etched.

(13) The reflecting mirror manufacturing method according to any one of (1) to (12), further including a peeling step of peeling the etching mask material from the material to be etched after the wet etching is finished.

(14) The method according to (13), further including a reflective film forming step of forming a reflective film on at least one of both surfaces of the etched material after the etching mask material is peeled from the etched material. Reflective mirror manufacturing method.

(15) A plate-like reflecting mirror having a reflecting surface on which light is incident,
A coating step of coating a film-like etching mask material on at least one of both surfaces of a plate-like material to be etched composed of a single crystal;
A mask pattern forming step of forming a mask pattern having a planar shape closer to a circle than a quadrangle on at least one of the etching mask materials coated on the material to be etched;
A wet etching step of performing etching by immersing the material to be etched, which is coated with the etching mask material, in an etching solution having a set concentration at a set temperature, thereby making the reflection mirror The reflecting mirror manufactured so that the projected figure obtained by projecting in the normal direction of the above has a planar shape closer to a circle than a quadrangle.

  In this reflection mirror, the projection figure obtained by projecting the reflection mirror in the normal direction thereof has a planar shape that is closer to a circle than a quadrangle. Therefore, according to this reflection mirror, a useless reflection area can be formed more easily than a reflection mirror having a quadrangle as a projected figure under the usage conditions in which a circular reflection area having a necessary reflection area is required at a minimum. It can be omitted. Therefore, according to this reflecting mirror, it is easier to reduce the weight and reduce the moment of inertia than the reflecting mirror having a quadrangular projection.

(16) The reflection mirror is used to scan the light by changing the reflection direction of the light incident on the reflection surface by being oscillated around an oscillation axis parallel to the reflection surface ( The reflecting mirror according to item 15).

(17) The reflecting mirror forms a vibrating body together with a plate-like spring that extends from the reflecting mirror along the swing axis and generates at least torsional vibration around the swing axis. The reflection mirror according to item (16), which is used to change the reflection direction of the light incident on the reflection surface by scanning at least a part of the light, and to scan the light.

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

  FIG. 1 systematically shows a retinal scanning display provided with a reflecting mirror unit manufactured by the reflecting mirror manufacturing method according to the first embodiment of the present invention for optical scanning. This retinal scanning display (hereinafter abbreviated as “RSD”), on the image plane of the retina 14 via the pupil 12 of the observer's eye 10 while appropriately modulating the wavefront and intensity of the laser beam. The image is projected directly onto the retina 14 by two-dimensionally scanning the laser beam on the imaging plane.

  This RSD includes a light source unit 20, and includes a wavefront modulation optical system 22 and a scanning device 24 in that order between the light source unit 20 and the eye 10 of the observer.

  The light source unit 20 includes an R laser 30 that emits red laser light and a green laser in order to combine three laser lights having three primary colors (RGB) into one laser light to generate laser light of an arbitrary color. A G laser 32 that emits light and a B laser 34 that emits blue laser light are provided. Each of the lasers 30, 32, and 34 can be configured as a semiconductor laser, for example.

  The laser beams emitted from the lasers 30, 32, 34 are collimated by the collimating optical systems 40, 42, 44 in order to combine them, and then each dichroic mirror 50, 52, having wavelength dependency. 54, so that each laser beam is selectively reflected and transmitted with respect to the wavelength.

  Specifically, red laser light emitted from the R laser 30 is collimated by the collimating optical system 40 and then incident on the dichroic mirror 50. The green laser light emitted from the G laser 32 is incident on the dichroic mirror 52 through the collimating optical system 42. The blue laser light emitted from the B laser 34 is incident on the dichroic mirror 54 via the collimating optical system 44.

  The laser beams of the three primary colors incident on the three dichroic mirrors 50, 52, and 54 are finally incident on and combined with one dichroic mirror 54 that represents the three dichroic mirrors 50, 52, and 54. The light is collected by the coupling optical system 56.

  Although the optical part of the light source unit 20 has been described above, the electrical part will be described below.

  The light source unit 20 includes a signal processing circuit 60 mainly composed of a computer. The signal processing circuit 60 is designed to perform signal processing for driving the lasers 30, 32, and 34 and signal processing for scanning the laser beam based on a video signal supplied from the outside. Yes.

  In order to drive each laser 30, 32, 34, the signal processing circuit 60 determines the color necessary for the laser light for each pixel on the image to be projected on the retina 14 based on the video signal supplied from the outside. A drive signal necessary for realizing the intensity is supplied to each laser 30, 32, 34 via each laser driver 70, 72, 74. Signal processing for scanning with a laser beam will be described later.

  The light source unit 20 described above condenses the laser beam in the coupling optical system 56 and makes it incident on the optical fiber 82. The laser beam incident on the optical fiber 82 is transmitted through an optical fiber 82 as an optical transmission medium, and passes through a collimating optical system 84 that collimates the laser beam emitted from the rear end of the optical fiber 82, thereby wavefront modulation optics. The light enters the system 22.

  The wavefront modulation optical system 22 is an optical system that modulates the wavefront (wavefront curvature) of the laser beam emitted from the light source unit 20. The wavefront modulation optical system 22 can have a form in which the wavefront curvature is modulated for each pixel of the image to be projected on the retina 14, but this is indispensable for carrying out the present invention. Instead, it is possible to adopt a format for every frame of an image. Modulating the wavefront curvature means changing the perspective of the display image or changing the focus position of the display image.

  In any case, the wavefront modulation optical system 22 modulates the wavefront of the laser beam incident on the wavefront modulation optical system 22 based on the depth signal input from the signal processing circuit 60. In the wavefront modulation optical system 22, the laser beam incident as parallel light from the collimating optical system 84 is converted into convergent light by the converging lens 90, and the converted convergent light is reflected by the movable mirror 92 and converted into diffused light. Is done. The converted diffused light passes through the converging lens 90 and is emitted from the wavefront modulation optical system 22 as a laser beam having a target wavefront curvature.

  As shown in FIG. 1, the wavefront modulation optical system 22 includes a beam splitter 94 that reflects or transmits a laser beam incident from the outside, a converging lens 90 that converges the laser beam incident through the beam splitter 94, and And a movable mirror 92 that reflects the laser beam converged by the converging lens 90.

  The wavefront modulation optical system 22 further includes an actuator 96 that displaces the movable mirror 92 toward or away from the converging lens 90. An example of the actuator 96 is a piezoelectric element. The actuator 96 modulates the wavefront curvature of the laser beam emitted from the wavefront modulation optical system 22 by moving the position of the movable mirror 92 according to the depth signal input from the signal processing circuit 60.

  In the wavefront modulation optical system 22 configured as described above, the laser beam incident from the collimating optical system 84 is reflected by the beam splitter 94, passes through the converging lens 90, and then is reflected by the movable mirror 92. Then, it passes through the converging lens 90 again, and then passes through the beam splitter 94 toward the scanning device 24.

  The scanning device 24 includes a horizontal scanning system 100 and a vertical scanning system 102.

  The horizontal scanning system 100 is an optical system that performs horizontal scanning in which a laser beam is raster-scanned horizontally along a plurality of horizontal scanning lines for each frame of an image to be displayed. On the other hand, the vertical scanning system 102 is an optical system that performs vertical scanning in which a laser beam is scanned vertically from the first scanning line toward the last scanning line for each frame of an image to be displayed. The horizontal scanning system 100 is designed to scan the laser beam at a higher speed, that is, at a higher frequency than the vertical scanning system 102.

  Specifically, in the present embodiment, the horizontal scanning system 100 includes an optical scanner 104 that swings a mirror by the vibration of an elastic body including a mirror that performs mechanical deflection. The optical scanner 104 is controlled based on the horizontal synchronization signal supplied from the signal processing circuit 60.

  FIG. 2 shows the optical scanner 104 in an exploded perspective view. As shown in FIG. 2, the optical scanner 104 is configured by mounting a main body 110 on a base 112.

  The main body 110 is formed using an elastic material such as silicon. As shown in the upper part of FIG. 2, the main body 110 generally has a thin plate rectangular shape having a through hole 114 through which light can pass. The main body 110 is provided with a fixed frame 116 on the outer side, and on the inner side is provided with a vibrating body 124 having a reflection mirror part 122 on which a reflection surface 120 is formed.

  Corresponding to the configuration of the main body 110, the base 112 includes a support 130 to which the fixed frame 116 is to be mounted and a vibrating body 124 in the mounted state with the main body 110 as shown in the lower part of FIG. And a concave portion 132 that faces each other. The recess 132 is formed to have a shape that does not interfere with the base 112 even when the vibrating body 124 is displaced by vibration in a state where the main body 110 is mounted on the base 112.

  As shown in FIG. 2, the reflecting surface 120 of the reflecting mirror unit 122 is swung around a swing axis 134 that is also a symmetric center line thereof. The vibrating body 124 further includes a beam portion 140 that extends from the reflection mirror portion 122 on the same plane as that, and joins the reflection mirror portion 122 to the fixed frame 116. In the present embodiment, a pair of beam portions 140 extend in opposite directions from both sides of the reflection mirror portion 122.

  Each beam portion 140 includes one mirror side leaf spring portion 142, a pair of frame side leaf spring portions 144, and a connection portion 146 that connects the mirror side leaf spring portions 142 and the pair of frame side leaf spring portions 144 to each other. It is configured as follows. The mirror side leaf spring 142 is connected to the oscillating axis 134 on the oscillating axis 134 from each of a pair of edges facing each other in the direction of the oscillating axis 134 of the reflecting mirror 122 to the corresponding connecting portion 146. Extending along. The pair of frame-side leaf springs 144 extend along the swing axis 134 from the corresponding connecting portions 146 in a posture that is offset in opposite directions with respect to the swing axis 134.

  In each of the overall spring portions 140, as shown in FIG. 2, drive sources 150, 152, 154, and 156 are attached to the pair of frame-side plate spring portions 144 and 144 in a posture that extends to the fixed frame 116, respectively.

  As shown in FIG. 3, each frame-side leaf spring portion 144 is locally thinned on the side close to the fixed frame 116, thereby forming a recess 158. A recessed portion 159 continuing to the recessed portion 158 is formed in the fixed frame 116. By using these recesses 158 and 159, each drive source 150, 152, 154, 156 is installed in a posture straddling each frame side leaf spring portion 144 and the fixed frame 116.

  Each of the drive sources 150, 152, 154, and 156 is configured mainly with a piezoelectric body 160 (also referred to as “piezoelectric vibrator” or “piezoelectric element”) as the drive source 154 is representatively shown in FIG. ing. The piezoelectric body 160 has a thin plate shape and is attached to one surface of the vibrating body 124, and is sandwiched between the upper electrode 162 and the lower electrode 164 in a direction perpendicular to the attachment surface. As shown in FIG. 3, the upper electrode 162 and the lower electrode 164 are connected to a pair of input terminals 168 installed on the fixed frame 116 by lead wires (not shown). On the other hand, the present invention can be implemented in such a manner that the upper electrode 162 and the lower electrode 164 are connected to external terminals (not shown) by lead wires (not shown).

  When a voltage is applied to the upper electrode 162 and the lower electrode 164, a displacement in a direction orthogonal to the application direction is generated in the piezoelectric body 160. Due to this displacement, as shown in FIG. 4, the beam portion 140 is bent, that is, warped. This bending is performed with the connection portion with the fixed frame 116 of the beam portion 140 as a fixed end and the connection portion with the reflection mirror portion 122 as a free end. As a result, the free end is displaced upward or downward depending on whether the bending direction is upward or downward.

  As is apparent from FIG. 4, the reflection mirror unit is located on one side with respect to the swing axis 134 among the four drive sources 150, 152, 154, and 156 attached to the four frame-side plate springs 144. The pair of drive sources 150 and 152 sandwiching 122 and the pair of drive sources 154 and 156 located on the other side and sandwiching the reflection mirror portion 122 are such that the free ends of the two piezoelectric bodies 160 belonging to each pair are mutually connected. It is bent so as to be displaced in the same direction.

  On the other hand, a pair of drive sources 150 and 154 that are located on one side with respect to the reflection mirror 122 and sandwich the swing axis 134, and a pair of drive sources 152 and 156 that are located on the other side and sandwich the swing axis 134 are shown. Each of the two piezoelectric bodies 160 belonging to each pair is bent so that the free ends thereof are displaced in directions opposite to each other.

  As a result, as shown in FIG. 4, the reflection mirror unit 122 has a displacement that rotates the reflection mirror unit 122 in the same direction as one of the pair of drive sources 150 and 152 positioned on one side with respect to the swing axis 134. Generated by both the directional displacement and the reverse displacement of the pair of drive sources 154 and 156 located on opposite sides.

  In short, each frame side leaf spring portion 144 has a function of converting the linear displacement (lateral displacement) of the piezoelectric body 160 affixed thereto into a bending motion (longitudinal displacement), and the connection portion 146 has each frame side leaf spring. It has a function of converting the bending motion of the portion 144 into the rotational motion of the mirror side leaf spring portion 142. The reflection mirror 122 is rotated by the rotational movement of the mirror side leaf spring 142.

  Therefore, in this embodiment, in order to control the four drive sources 150, 152, 154, 156, two drive sources 150, 152 located on one side with respect to the swing axis 134, that is, in FIG. The upper right drive source 150 and the upper left drive source 152 form a first pair, and two drive sources 154 and 156 located on the opposite side, that is, the lower right drive source 154 and the lower left drive source in FIG. 156 and the second pair.

  In the present embodiment, the two drive sources 150 and 152 forming the first pair and the two drive sources 154 and 156 forming the second pair are displaced in the opposite directions, and the reflection mirror unit 122 is moved to the opposite direction. In order to generate a reciprocating rotational motion, that is, a rocking motion around the rocking axis 134, an alternating voltage is applied to the two driving sources 150, 152 in the first pair in phase with each other. The alternating voltages having opposite phases are applied to the two driving sources 154 and 156 forming the second pair in the same phase. As a result, when the two drive sources 150 and 152 forming the first pair are both bent downward in FIG. 4, the two drive sources 154 and 156 forming the second pair are the same. In the figure, it will bend upward.

  In order to realize the above-described control, the horizontal scanning system 100 includes a horizontal scanning driving circuit 180 shown in FIG. In the horizontal scanning drive circuit 180, as shown in FIG. 5, the oscillator 182 generates an alternating voltage signal based on the horizontal synchronization signal input from the signal processing circuit 60. The oscillator 182 is connected to two drive sources 150 and 152 in a first pair via a first path that passes through a phase shifter 184 and an amplifier 186, while passing through a phase inverting circuit 188, a phase shifter 190, and an amplifier 192. It is connected to two drive sources 154 and 156 forming a second pair via the second path.

  The phase inversion circuit 188 inverts the phase of the alternating voltage signal input from the oscillator 182 and supplies it to the phase shifter 190. Since the phase inverting circuit 188 is provided only in the second path, the two drive sources 150 and 152 forming the first pair and the two drive sources 154 and 156 forming the second pair have corresponding amplifiers. The phases of the alternating voltage signals supplied from 186 and 192 are opposite to each other.

  In any of the paths, the phase shifters 184 and 190 are arranged so that the phase of the alternating voltage signal to be supplied to the drive sources 150, 152, 154, and 156 so that the video signal and the vibration of the reflection mirror unit 122 are synchronized with each other. It is provided to change

  FIG. 6 is a perspective view showing a specific shape of the vibrating body 124. In the vibrating body 124, the reflection mirror unit 122 is manufactured so that a projection figure obtained by projecting the reflection mirror unit 122 in the normal direction of the reflection surface 120 is generally circular. This reflection mirror section 122 constitutes an example of the “reflection mirror” in the item (1). In the present embodiment, the diameter of the reflecting mirror portion 122 is 1 mm, the thickness thereof is 100 μm, and the length of each whole spring portion 140 is 2 mm. The manufacturing method of the reflection mirror part 122 will be described in detail later.

  FIG. 7 is a perspective view showing a state in which light emitted from the optical fiber 82 enters the optical scanner 104 via the collimating optical system 84. The light emitted from the collimating optical system 84 is incident on the reflecting surface 120 of the reflecting mirror portion 122 which is generally circular, and the reflecting mirror portion 122 is swung around the swing axis 134, thereby causing the light from the reflecting surface 120. Is reflected in the horizontal direction.

  FIG. 8 is a perspective view showing the light emitted from the optical fiber 82 entering the conventional optical scanner 300 through the collimating optical system 84. In this optical scanner 300, the reflection mirror 302 has a quadrangular shape.

  If it is assumed that the reflection mirror 302 and the reflection mirror 122 in the present embodiment are common to each other in terms of the specific gravity, thickness, and maximum width of the material, and the weight is compared with each other, the reflection mirror in the present embodiment 122 is lighter, and therefore the reflection mirror portion 122 in this embodiment is smaller when compared with each other with respect to the moment of inertia around the swinging axes 134 and 304.

  Therefore, when the reflection mirror unit 122 in this embodiment and the conventional reflection mirror unit 302 scan light using their own resonance, the resonance frequency is increased to increase the light scanning frequency. Therefore, the reflection mirror unit 122 in this embodiment is more suitable than the conventional reflection mirror unit 302.

  The laser beam horizontally scanned by the optical scanner 104 described above is transmitted to the vertical scanning system 102 by the relay optical system 194 as shown in FIG.

  This RSD has a beam detector 200 in place. The beam detector 200 is provided to detect the position of the laser beam in the main scanning direction by detecting the laser beam deflected by the optical scanner 104. An example of the beam detector 200 is a photodiode.

  The beam detector 200 outputs a signal indicating that the laser beam has reached a predetermined position as a BD signal, and the output BD signal is supplied to the signal processing circuit 60. In response to the BD signal output from the beam detector 200, the signal processing circuit 60 waits for a set time to elapse from the time when the beam detector 200 detects the laser beam, and sends a necessary drive signal to each laser driver 70. , 72, 74. Thereby, the image display start timing is determined for each scanning line, and the image display is started at the determined image display start timing.

  Although the horizontal scanning system 100 has been described above, the vertical scanning system 102 includes a galvanometer mirror 210 as a swinging mirror that performs mechanical deflection, as shown in FIG. The laser beam emitted from the horizontal scanning system 100 is collected by the relay optical system 194 and enters the galvanometer mirror 210. The galvanometer mirror 210 is swung around a rotation axis that intersects the optical axis of the laser beam incident thereon. The start timing and rotation speed of the galvanometer mirror 210 are controlled based on the vertical synchronization signal supplied from the signal processing circuit 60.

  In cooperation with the horizontal scanning system 100 and the vertical scanning system 102 described above, the laser beam is scanned two-dimensionally, and an image represented by the scanned laser beam passes through the relay optical system 214 to the eyes of the observer. 10 is irradiated.

  Here, a manufacturing method of the reflection mirror unit 122 will be described in detail with reference to the process diagram of FIG.

  In this manufacturing method, first, in step S1, a plate-shaped material (silicon wafer) made of silicon single crystal is used as an etching object 400 (see FIG. 11) so as to have a thickness of 100 μm. Be prepared for.

  Next, in step S2, an etching mask material 410 (see FIG. 11) is coated on both surfaces of the material 400 to be etched. For example, the etching mask material 410 is a silicon oxide film formed on both surfaces of the material to be etched 400 by heating the material 400 to be etched. That is, this step S2 is a coating process.

  Subsequently, in step S <b> 3, a predetermined mask pattern is formed by lithography on the etching mask material 410 that is coated on both surfaces of the material to be etched 400. The shape of the mask pattern formed on each etching mask material 410 is such that when the material to be etched 400 is immersed in an etching bath (not shown), the etching solution contained in the etching bath is first contacted and etched. Determine the shape of the part to be used. That is, this step S3 is a mask pattern forming process.

  FIG. 10 is a plan view showing an example of the mask pattern.

  By the way, in this embodiment, in order to explain the crystal plane finally exposed in the material 400 to be etched, attention is paid to the symmetry of the final shape of the material 400 to be etched, and as shown in FIG. Along the surface of the etching material 400, four regions divided into four equal parts around one central point PC (Point of Center) of the surface are assumed. FIG. 13 representatively shows one of these four regions.

  In the present embodiment, as shown in FIG. 10, the mask pattern has a first side parallel to the swing axis 134 (this is an example of “one reference line” in the item (6)) and the swing axis. 134 and a second side orthogonal to the second side. This mask pattern is positioned with respect to the material to be etched 400 such that the first side and the second side are orthogonal to the <110> crystal direction on the (100) crystal plane of the material to be etched 400 shown in FIG.

  In the present embodiment, as shown in FIG. 10, the second side 422 (second part extending horizontally in FIG. 10) whose first side is parallel to the swing axis 134 among the plurality of second parts 422 described later. 422), on the other hand, the second side corresponds to a second portion 422 (second portion 422 extending vertically in FIG. 10) perpendicular to the swing axis 134 among the plurality of second portions 422. In order to define the shape of the mask pattern, for convenience, the material 400 to be etched has two symmetrical centerlines (oscillation axis 134 and the oscillation axis at the center point PC) orthogonal to each other at the center point PC of the mask pattern. Is divided into four regions I, II, III and IV.

  In the present embodiment, as shown in FIG. 10, the mask pattern further extends outward along the swing axis 134 on both sides of the mask pattern facing each other in the direction of the swing axis 134. It has an extending part 431 for taking out. The extending portion 431 is provided in a mask pattern for manufacturing the beam portion 140 shown in FIG. 4 together with the reflecting mirror portion 122 by wet etching.

  Here, referring to FIG. 13, the orientation of each region and the orientation of the xyz coordinate system assigned to the material to be etched 400 in order to define a plurality of crystal planes of the material 400 to be etched composed of a single crystal. The bisector of the central angle of each region (in the example of FIG. 13, the one located at the top in FIG. 13 among the four corners of the square indicated by the region) and the x axis The direction of each region and the direction of the xyz coordinate system are determined so that they coincide with each other. In other words, the material to be etched 400 is divided into four equal parts so that the normal to the (100) plane in each region coincides with the bisector of the central angle of each region.

  In FIG. 10, the above-described xyz coordinate system is shown not with the material to be etched 400 but with the etching mask material 410. In FIG. 10, the mask pattern is divided into four equal parts around one central point PC of the surface along the surface thereof, thereby forming four regions I, II, III and IV. An xyz coordinate system is assigned to each region, but this is representatively shown only for region I in FIG.

  As shown in FIG. 10, the mask pattern has a convex octagon. Specifically, the outline of the mask pattern includes, for each region, the first portion 420 corresponding to the (100) crystal plane of the material 400 to be etched, the (111) crystal plane (the (111) crystal plane in the narrow sense, and A second portion 422 corresponding to a crystal plane equivalent to that). The second portion 422 exists on both sides of the first portion 420.

  The mask pattern having the shape described above is formed on both surfaces of the material to be etched 400 so as not to be shifted from each other. Then, as shown in FIG. 9, in step S4, the laminated body of the to-be-etched material 400 and the etching mask material 410 is immersed in the etching tank which accommodates etching liquid. In this embodiment, the kind of etching solution is selected as potassium hydroxide solution (KOH), its concentration is selected as 40 wt%, and its temperature is selected as 70 ° C. Under this condition, wet etching is performed on the material 400 to be etched. That is, this step S4 is a wet etching process. Note that the type of etching solution can be changed to a tetramethylammonium hydroxide solution (TMAH). In this case, the shape of the mask pattern is changed from that shown in FIG.

  FIGS. 11A and 11B and FIGS. 12C and 12D show how the material to be etched 400 is wet-etched step by step. However, in these drawings, the material 400 to be etched is representatively shown only in any of the above-described four regions I, II, III, and IV, focusing on the symmetry thereof.

  In FIG. 11A, the wet etching of the material to be etched 400 is started from a portion that is not coated with the etching mask material 410. At this stage, only the (100) crystal plane and the (111) crystal plane appear in the material 400 to be etched.

  When wet etching is slightly advanced from the stage shown in FIG. 11A, as shown in FIG. 11B, in the material to be etched 400, the first exposed (100) crystal face and (111) crystal face are exposed. A plurality of different crystal planes are present in the intermediate portion, that is, in each corner portion (hereinafter referred to as “original corner portion”) belonging to the octagon indicated by the etching mask material 410 in the stage shown in FIG. It begins to be exposed and this rounds the original corners.

  When the wet etching slightly proceeds from the stage shown in FIG. 11B, as shown in FIG. 12C, in the material 400 to be etched, a portion between the (100) crystal plane and the (111) crystal plane is formed. A plurality of crystal planes exposed at the stage shown in FIG. 11B grow, and further, another crystal plane begins to be exposed, whereby the original corners are further rounded.

  When wet etching slightly proceeds from the stage shown in FIG. 12C, as shown in FIG. 12D, in the material to be etched 400, the portion between the (100) crystal plane and the (111) crystal plane is formed. A plurality of crystal planes exposed at the stage shown in FIG. 12C grow, and further, another crystal plane begins to be exposed, whereby the original corners are further rounded. The stage shown in FIG. 12D is an end stage of wet etching, and the material to be etched 400 is penetrated in the thickness direction by the etching solution. FIG. 12D shows the final shape of the material to be etched 400 together with the max pattern.

  In FIG. 13, the material 400 to be etched shown in FIG. When the wet etching of the material to be etched 400 is completed, the (211) crystal plane, the (311) crystal plane, the (411) crystal plane, and the (511) crystal plane between the (100) crystal plane and the (111) crystal plane. A plurality of other crystal planes including are exposed. The (211) crystal plane, the (311) crystal plane, the (411) crystal plane, and the (511) crystal plane are each a narrowly defined crystal plane represented by a numerical string in parentheses, like the (111) crystal plane. And an equivalent crystal plane.

  That is, in the present embodiment, as shown in FIG. 10, the etching mask material 410 corresponds to the (n11) crystal plane (N: an integer of 2 or more) between the first portion 420 and the second portion 422. The third portion 424 is provided.

  The reflection mirror 122 completed by the wet etching described above has a generally convex octagon when projected in the normal direction, and more precisely, an n-gon (n: an integer greater than 16) is formed. It is made. FIG. 14A is a longitudinal sectional view of the completed reflection mirror unit 122, and shows a case where it is cut by a plane passing through the (100) plane. FIG. 6B is a longitudinal sectional view of the completed reflection mirror unit 122, and shows a case where it is cut along a plane passing through the (111) plane.

  In FIG. 14C, as a comparative example of the material to be etched 400, a reflection mirror 122 ′ obtained when the material to be etched 400 ′ is wet-etched from only one surface is a plane that passes through the (111) surface. It is shown by the longitudinal cross-sectional view cut | disconnected by. As shown in FIG. 4B, according to the present embodiment, since the material to be etched 400 is wet-etched from both sides, the side surface thereof is symmetrical with respect to the center line in the thickness direction of the material to be etched 400. A discontinuous inclined surface is formed. Therefore, according to this embodiment, it is easier to manufacture the reflection mirror part 122 that is lighter and has a smaller moment of inertia than the above-described comparative example.

  According to the present embodiment, there are a plurality of types of crystal planes (hereinafter referred to as “intervening crystal planes”) different from those exposed between the (100) crystal plane and the (111) crystal plane. is there. Therefore, according to the present embodiment, the shape of the reflection mirror portion 122 is rounded from the hexagon that is the shape of the reflection mirror portion 122 when the number of types of intervening crystal planes is one. As the number of straight line segments (corresponding to each crystal plane) constituting the outline of the projected figure obtained by projecting the reflecting mirror unit 122 in the normal direction thereof increases, the outline tends to approach a circle. Because there is.

  Furthermore, according to this embodiment, both the (100) crystal plane and the (111) crystal plane are eroded by wet etching, and the respective length dimensions are reduced from the initial values. The decrease is replaced by another crystal plane having an oblique orientation with respect to both the (100) crystal plane and the (111) crystal plane.

  Therefore, according to the present embodiment, the lengths of the plurality of crystal planes constituting the outer peripheral surface of the reflecting mirror 112 are reduced and equalized, and this also makes the shape of the reflecting mirror portion 122 circular. Is done. When the number of the plurality of straight line segments (corresponding to each crystal plane) constituting the outline of the projection figure of the reflection mirror unit 122 is the same, the length of the longest straight line segment among these straight line segments is This is because the shorter the outline, the closer to the circle.

  In addition, FIG. 15 shows another example of the mask pattern. In this example, as in the previous example, the outline of the mask pattern includes a first portion 430 corresponding to the (100) crystal plane, a second portion 432 corresponding to the (111) crystal plane, and (n11) The third portion 434 corresponding to the crystal plane (N: an integer of 2 or more) is included.

  When the wet etching process is completed as described above, as shown in FIG. 9, thereafter, in step S5, the material to be etched 400 having the etching mask material 410 coated on both surfaces is taken out from the etching tank. Subsequently, in step S <b> 6, the etching mask material 410 is peeled off from both surfaces of the material to be etched 400. Thereafter, in step S7, a reflective film is formed on at least one of both surfaces of the material to be etched 400 using aluminum or silver as a material.

  This is the end of the series of implementations of the reflecting mirror manufacturing method.

  Next, a second embodiment of the present invention will be described. However, this embodiment differs from the first embodiment only in the shape of the mask pattern and the specific shape of the reflecting mirror, and is common to other elements. Therefore, only the different elements will be described in detail and common. Detailed description of elements is omitted by quoting using the same reference numerals or names.

  As shown in FIG. 16, in this embodiment, the mask pattern is parallel to the swing axis 134 (this is an example of “one reference line” in the above section (6)), as in the first embodiment. A first side and a second side orthogonal to the swing axis 134. This mask pattern is positioned with respect to the material to be etched 480 such that the first side and the second side are perpendicular to the <110> crystal direction on the (100) crystal plane of the material to be etched 480 shown in FIG.

  In the present embodiment, the first side corresponds to a second portion 472 (second portion 422 extending horizontally in FIG. 16) parallel to the swing axis 134 among a plurality of second portions 472 described later, The second side corresponds to a second portion 472 (second portion 472 extending vertically in FIG. 16) orthogonal to the swing axis 134 among the plurality of second portions 472. In order to define the shape of the mask pattern, for convenience, the material 480 to be etched has two symmetrical centerlines (oscillation axis 134 and the oscillation axis at the center point PC) orthogonal to each other at the center point PC of the mask pattern. Is divided into four regions I, II, III and IV.

  In the present embodiment, as in the first embodiment, the mask patterns are arranged on both sides of the mask pattern facing each other in the direction of the swing axis 134 as shown in FIG. An extending portion 431 extending outward along the line 134 is provided.

  In the present embodiment, as in the first embodiment, the mask pattern has a generally convex octagon, and the outline of the mask pattern has a first portion 470 corresponding to the (100) crystal plane, 111) and a second portion 472 corresponding to the crystal plane. Further, in the present embodiment, the fourth portion 474 is symmetrically disposed on both sides of the first portion 470, similarly to the second portion 472.

  As is clear from the above description, in this embodiment, the planar shape of the mask pattern has a convex octagon as a basic shape, and has fourth portions 474 as protrusions at eight corners of the octagon. It is a shape. The fourth portion 474 has a shape extending from each corner of the regular octagon toward a region corresponding to the outer corner of each corner.

  The fourth portion 474 has a function of delaying the timing at which corners that should be originally formed by the first portion 470 and the second portion 472 are eroded by wet etching by the absence of the fourth portion 474. Fulfill. With this function, the surface configuration of the outer peripheral surface of the final reflection mirror unit 122 is simpler than that of the first embodiment.

  In the present embodiment, as in the first embodiment, the etching mask material 490 is coated on both surfaces of the material to be etched 480, and each of the two coated etching mask materials 490 has a mask pattern having the above-described shape. Is formed. Thus, wet etching is performed on the material to be etched 480 to which the mask pattern is assigned.

  FIGS. 17A and 17B and FIGS. 18C and 18D show how the material to be etched 480 is wet-etched step by step. In FIG. 17A, wet etching of the material to be etched 480 is started from a portion not coated with the etching mask material 490.

  At this stage, the (100) crystal plane and the (111) crystal plane mainly appear in the material to be etched 480. Furthermore, another crystal plane also appears in the material to be etched 480 between the (100) crystal plane and the (111) crystal plane. A portion of the material to be etched 480 where another crystal plane appears forms a (100) crystal plane and a protruding portion 492 protruding from the (111) crystal plane. The protruding portion 492 is a portion formed as a result of the erosion being delayed from the peripheral portion by the fourth portion 474 of the mask pattern.

  When wet etching slightly proceeds from the stage shown in FIG. 17A, as shown in FIG. 17B, the material to be etched 480 is located between the (100) crystal face and the (111) crystal face. The protrusion 492 is eroded by wet etching, and the protrusion amount of the protrusion 492 is reduced. At this stage, a (520) crystal plane starts to form at the tip of the protrusion 492.

  When the wet etching is slightly advanced from the stage shown in FIG. 17B, as shown in FIG. 18C, the material to be etched 480 is located between the (100) crystal face and the (111) crystal face. The protrusion 492 is further eroded by wet etching, and the protrusion amount of the protrusion 492 is further reduced. At this stage, the (520) crystal plane formed at the tip of the protrusion 492 grows.

  When wet etching is slightly advanced from the stage shown in FIG. 18C, as shown in FIG. 18D, in the material to be etched 480, (520) between the (100) crystal face and the (111) crystal face. ) A crystal plane grows, and the (100) crystal plane and the (111) crystal plane are connected to each other by a slope by the (520) crystal plane. The stage shown in FIG. 18D is an end stage of wet etching, and the material to be etched 480 is penetrated in the thickness direction by an etching solution. FIG. 18D shows the final shape of the material to be etched 480 together with the max pattern.

  In FIG. 19, the material to be etched 480 shown in FIG. When the wet etching of the material to be etched 480 is completed, only the (520) crystal plane is exposed between the (100) crystal plane and the (111) crystal plane. As a result, according to the present embodiment, the (100) crystal plane is exposed. The plane and the (111) crystal plane are connected to each other with a simpler plane configuration than in the first embodiment.

  FIG. 20A shows the completed reflection mirror 122 in a perspective view, and FIG. 20B shows a plan view. If the reflecting mirror part 122 is projected in the normal direction, it forms a generally convex octagon, more precisely a hexagon, and more precisely a shape close to a hexagon. Is made.

  According to the present embodiment, the outer peripheral surface of the reflection mirror portion 122 is configured such that the (520) crystal plane is mainly interposed between the (100) crystal plane and the (111) crystal plane. The wet etching is performed so that there is mainly one type of intervening crystal plane, and the number of types of intervening crystal planes that are present does not vary. Therefore, according to this embodiment, the shape of the outer peripheral surface of the reflection mirror part 122 is stabilized, and as a result, the moment of inertia of the reflection mirror part 122 is also stabilized.

  In addition, FIG. 21 shows another example of the mask pattern. In this example, the outline of the mask pattern has a first portion 500 corresponding to the (100) crystal plane and a second portion 502 corresponding to the (111) crystal plane, as in the above example. Yes.

  As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are exemplifications, and are based on the knowledge of those skilled in the art including the aspects described in the section of [Disclosure of the Invention]. The present invention can be implemented in other forms with various modifications and improvements.

It is a systematic diagram which shows the retina scanning type display provided with the reflective mirror part manufactured by the reflective mirror manufacturing method according to 1st Embodiment of this invention for optical scanning. It is a disassembled perspective view which shows the optical scanner 104 in FIG. FIG. 3 is a side sectional view and a perspective view showing a drive source 154 and its periphery in FIG. 2. FIG. 3 is a perspective view showing a vibrating body 124 in FIG. 2. FIG. 2 is a block diagram showing a horizontal scanning drive circuit 180 in FIG. 1. FIG. 3 is a perspective view showing a specific shape of a vibrating body 124 in FIG. 2. It is a perspective view for demonstrating a mode that light injects into the circular reflective mirror part 122 of the vibrating bodies 124 in FIG. It is a perspective view for demonstrating a mode that light injects into the square-shaped reflective mirror part 302 of the comparative examples of the vibrating body 124 in FIG. It is process drawing which shows the said reflective mirror manufacturing method. It is a top view which shows the mask pattern formed in step S3 in FIG. FIG. 10 is a perspective view for explaining stepwise how the wet etching performed in step S4 in FIG. 9 proceeds. It is another perspective view for demonstrating in a stepwise manner how the wet etching performed in step S4 in FIG. 9 advances. It is a perspective view which expands and shows the to-be-etched material 400 shown in FIG.12 (d). FIG. 10 is a longitudinal sectional view showing a reflecting mirror part 122 finally manufactured by the reflecting mirror manufacturing method shown in FIG. 9 and a longitudinal sectional view showing a comparative example of the reflecting mirror part 122. It is a top view which shows the modification of the mask pattern shown in FIG. It is a top view which shows the mask pattern formed in order to manufacture the reflective mirror part 122 by the reflective mirror manufacturing method according to 2nd Embodiment of this invention. It is a perspective view for demonstrating in a stepwise manner how wet etching advances in 2nd Embodiment. It is another perspective view for demonstrating in a stepwise manner how wet etching advances in 2nd Embodiment. It is a perspective view which expands and shows the to-be-etched material 480 shown in FIG.18 (d). It is the perspective view and top view which show the reflective mirror part 122 finally manufactured by 2nd Embodiment. It is a top view which shows the modification of the mask pattern shown in FIG.

Explanation of symbols

120 Reflecting surface 122 Reflecting mirror part 124 Vibrating body 400, 480 Etched material 410, 490 Etching mask material 420, 430, 470, 500 First part 422, 432, 472, 502 Second part 424, 434 Third part 474 504 Fourth part

Claims (17)

A reflecting mirror manufacturing method for manufacturing a plate-like reflecting mirror having a reflecting surface on which light is incident by etching,
A coating step of coating a film-like etching mask material on at least one of both surfaces of a plate-like material to be etched composed of a single crystal;
A mask pattern forming step of forming a mask pattern having a planar shape closer to a circle than a quadrangle on at least one of the etching mask materials coated on the material to be etched;
A wet etching step of performing etching by immersing the material to be etched coated with the etching mask material in an etching solution having a set concentration under a set temperature, whereby the reflection mirror is A reflection mirror manufacturing method of manufacturing the reflection mirror so that a projection figure obtained by projecting in the normal direction of the above has a planar shape closer to a circle than a quadrangle.   2. The reflection mirror according to claim 1, wherein the reflection mirror is used to scan the light by changing the reflection direction of the light incident on the reflection surface by being oscillated around an oscillation axis parallel to the reflection surface. The reflecting mirror manufacturing method of description.   The reflecting mirror extends from the reflecting mirror along the swing axis, and constitutes a vibrating body together with a plate-like spring that generates at least a torsional vibration around the swing axis, and at least one of the vibrating bodies. The reflection mirror manufacturing method according to claim 2, wherein the reflection mirror is used to scan the light by changing a reflection direction of the light incident on the reflection surface by vibrating the part.   4. The reflection mirror manufacturing method according to claim 1, wherein a planar shape of the mask pattern is generally a convex octagon.   5. The reflecting mirror manufacturing method according to claim 4, wherein the planar shape of the mask pattern is a shape having a convex octagon as a basic shape and having protrusions at eight corners of the octagon. The mask pattern has a first side parallel to one reference line and a second side orthogonal to the reference line, and the first side and the second side are on the (100) crystal plane of the material to be etched. <110> positioned with respect to the material to be etched so as to be orthogonal to the crystal direction,
The outline of the mask pattern is (100) of the material to be etched for each region when the material to be etched is divided into four regions by two symmetrical center lines orthogonal to each other at the center point of the mask pattern. 6. The reflection mirror manufacturing method according to claim 4, further comprising: a first portion corresponding to a crystal plane; and a second portion corresponding to a (111) crystal plane.   The outline of the mask pattern further includes, for each region, a third portion corresponding to the (n11) crystal plane (n: an integer of 2 or more) of the material to be etched, the first portion and the second portion. The manufacturing method of the reflective mirror of Claim 6 which has between.   The outline of the mask pattern further includes, for each region, a fourth portion corresponding to the (520) crystal plane of the material to be etched between the first portion and the second portion. The reflecting mirror manufacturing method of description.   9. The reflection mirror manufacturing method according to claim 1, wherein the etching solution is KOH or TMAH.   The method of manufacturing a reflecting mirror according to claim 9, wherein the set concentration is in a range of 35 wt% to 45 wt%.   The method of manufacturing a reflecting mirror according to claim 9 or 10, wherein the set temperature is in a range of 60 ° C to 80 ° C.   12. The reflection mirror manufacturing method according to claim 1, wherein the mask pattern forming step includes a step of forming the mask pattern on two etching mask materials respectively coated on both surfaces of the material to be etched. .   Furthermore, the reflection mirror manufacturing method in any one of Claim 1 thru | or 12 including the peeling process which peels the said etching mask material from the said to-be-etched material after completion | finish of the said wet etching.   The method of manufacturing a reflecting mirror according to claim 13, further comprising a reflecting film forming step of forming a reflecting film on at least one of both surfaces of the etched material after the etching mask material is peeled from the etched material. . A plate-like reflecting mirror having a reflecting surface on which light is incident,
A coating step of coating a film-like etching mask material on at least one of both surfaces of a plate-like material to be etched composed of a single crystal;
A mask pattern forming step of forming a mask pattern having a planar shape closer to a circle than a quadrangle on at least one of the etching mask materials coated on the material to be etched;
A wet etching step of performing etching by immersing the material to be etched coated with the etching mask material in an etching solution having a set concentration under a set temperature, thereby making the reflection mirror The reflecting mirror manufactured so that the projected figure obtained by projecting in the normal direction of the above has a planar shape closer to a circle than a quadrangle.   16. The reflection mirror according to claim 15, wherein the reflection mirror is used to scan the light by changing the reflection direction of the light incident on the reflection surface by being oscillated around an oscillation axis parallel to the reflection surface. The reflecting mirror described.   The reflecting mirror extends from the reflecting mirror along the swing axis, and constitutes a vibrating body together with a plate-like spring that generates at least torsional vibration around the swing axis, and at least one of the vibrating bodies. The reflection mirror according to claim 16, wherein the reflection mirror is used for changing the reflection direction of light incident on the reflection surface and scanning the light by vibrating the part.

Images