optical scanning device

Abstract

This invention provides an optical scanning device. This optical scanning device can address deviations in the installation position and characteristics of the photodetector, thereby improving the detection accuracy of the deflection angle of the mirror. The optical scanning device (1) includes a control unit (2), an optical deflector (3), an optical detection unit (4a, 4b), and a light source (5). The mirror (30) of the optical deflector (3) has a flat reflective portion (38) that generates scanning light (Lb) and a slotted reflective portion (39) that generates secondary reflected light (L2), and reciprocates about a rotation axis (36). The optical detection unit (4a, 4b) is positioned on the scanning trajectory of the scanning light (Lb) and can receive the secondary reflected light; it is divided into a photodetector (54a) and a photodetector (54b) by a dividing line (53) in the scanning direction of the scanning light (Lb). The control unit (2) detects the deflection angle (θ) of the mirror (30) based on the two outputs of the photodetectors (54a, 54b).

Description

TECHNICAL FIELD

[0001] The present application relates to an optical scanning device provided with an optical deflector. BACKGROUND

[0002] An optical deflector of MEMS (Micro Electro Mechanical Systems) and an optical scanning device provided with the same are known (for example, Patent Literature 1 and Patent Literature 2). The optical deflector of MEMS is provided with a mirror portion that reciprocally rotates around a rotation axis, reflects light from a light source in a direction corresponding to a deflection angle of the mirror portion, and emits the reflected light as scanning light.

[0003] The scanning position of the scanning light in the irradiation region varies in correspondence with the deflection angle of the mirror portion. Therefore, in order to appropriately control the irradiation quality of the scanning light, it is necessary to detect the deflection angle of the mirror portion.

[0004] The optical scanning device of Patent Literature 1 is provided with a PD (Photo-diode) that is disposed in the emission direction of the reflected light when the mirror portion reaches an end portion of the deflection angle range. Thereby, when the mirror portion rotates to a prescribed deflection angle of the end portion of the deflection angle range, the reflected light is detected by the PD.

[0005] In the optical scanning device of Patent Literature 2, the reflecting surface of the mirror portion is formed by a diffraction grating. In this optical scanning device, the 0th order diffracted light emitted from the mirror portion is used in the original use of the scanning light. In contrast to this, the 1st order diffracted light is used for detecting the deflection angle by being incident to a light receiving element.

[0006] PRIOR ART DOCUMENTS

[0007] PATENT LITERATURE

[0008] Patent Literature 1: Japanese Patent Application Publication No. 2006-243225

[0009] Patent Literature 2: Japanese Patent Application Publication No. 2011-118178 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] In the optical scanning devices of Patent Literature 1 and Patent Literature 2, due to the variation in the installation position and characteristics of the PD that detects the reflected light or the diffracted light, there is an error in the detection of the deflection angle of the mirror portion.

[0012] An object of the present application is to provide an optical scanning device that can detect the deflection angle of a mirror portion while compensating for the variation in the installation position and characteristics of a light detection portion.

[0013] MEANS FOR SOLVING THE PROBLEMS

[0014] The optical scanning device of the present application comprises:

[0015] a light source that emits light;

[0016] a light deflector that has a mirror portion including a flat reflecting portion that causes incident light, which is incident on a surface side from the light source, to be emitted as scanning reflected light, and a groove-shaped reflecting portion that has a longitudinal groove extending in a prescribed direction, the longitudinal groove having a pair of inclined surfaces that face each other in a manner in which a groove width of the longitudinal groove narrows from the surface side to a back surface side, the groove-shaped reflecting portion causing the incident light to be reflected twice, once on each of the pair of inclined surfaces, as index light; and a first actuator that causes the mirror portion to reciprocally rotate about a first rotation axis that is parallel to an extending direction of the longitudinal groove;

[0017] a light detection portion that is disposed on a scan track of a scan spot of the scanning reflected light and on a light-receiving position of an index spot of the index light, and is divided into a first light detector and a second light detector by a division line that divides the index spot in a scan direction of the scanning reflected light; and

[0018] a deflection angle detection portion that detects a first deflection angle, which is a deflection angle of the mirror portion about the first rotation axis, on the basis of a comparison between two outputs of the first light detector and the second light detector.

[0019] According to the present application, the first light detector and the second light detector are disposed on the scan track of the scan spot, and each divided portion of the index spot divided by the division line receives light. Also, the deflection angle of the mirror portion is detected on the basis of the two outputs of the first light detector and the second light detector. Since deviations in the mounting positions and characteristics of the light detection portion are reflected in the relationship between the two outputs of the first light detector and the second light detector, the deflection angle of the mirror portion can be detected on the basis of compensation for these deviations.

[0020] Preferably, in the optical scanning device of the present application, the deflection angle detection portion detects on the basis of a difference between the two outputs of the first light detector and the second light detector as the comparison between the two outputs.

[0021] According to this structure, the first deflection angle is detected on the basis of the difference between the two outputs of the first light detector and the second light detector. Thus, the detection accuracy of the deflection angle of the mirror portion can be improved.

[0022] Preferably, in the optical scanning device of the present application, the deflection angle detection portion detects on the basis of a ratio between the two outputs of the first light detector and the second light detector as the comparison between the two outputs.

[0023] According to this configuration, the first deflection angle is detected based on the comparison of the two outputs of the first light detector and the second light detector. Thus, the detection accuracy of the deflection angle of the mirror section can be improved.

[0024] Preferably, in the optical scanning device of the present application, the deflection angle detection section detects the case where the deflection angle of the mirror section around the first rotation axis becomes the index deflection angle based on the two outputs of the first light detector and the second light detector.

[0025] According to this configuration, the case where the deflection angle of the mirror section becomes the index deflection angle is detected based on the two outputs of the first light detector and the second light detector. Thus, the detection accuracy of the deflection angle of the mirror section can be improved.

[0026] Preferably, in the optical scanning device of the present application, the deflection angle detection section generates an intermediate value based on the comparison of the two outputs of the first light detector and the second light detector, sets the intermediate value at the time when the scanning spot is not receiving light as a reference value, corrects the intermediate value using the reference value to obtain a corrected value, and detects the first deflection angle based on the corrected value.

[0027] According to this configuration, the intermediate value at the time when the scanning spot is not receiving light is set as a reference value, and the deflection angle is detected based on a corrected value obtained by correcting the intermediate value using the reference value. Thus, it is possible to prevent each optical scanning device from having a deviation in detecting the deflection angle.

[0028] Preferably, in the optical scanning device of the present application, the deflection angle detection section detects the time when the deflection angle of the mirror section becomes the index deflection angle based on the time when the sign of the difference amount is reversed.

[0029] According to this configuration, the time when the mirror section becomes the index deflection angle is detected based on the time when the sign of the difference amount is reversed. Thus, it is possible to detect a time that has generality.

[0030] Preferably, in the optical scanning device of the present application, the intermediate value is a normalized difference amount Ev defined by the following (Formula 1).

[0031] According to this configuration, the first deflection angle is detected using the normalized difference amount Ev, and it is possible to use a general optical scanning device regardless of the type of the optical scanning device.

[0032] Preferably, in the optical scanning device of the present application,

[0033] The light detection sections are provided on both sides of the center of the deflection angle range of the scanning light spot as one light detection section and another light detection section,

[0034] The deflection angle detection section detects the angle range of the deflection angle of the scanning light spot based on the time difference between the sign inversion timing at the one light detection section and the sign inversion timing at the another light detection section.

[0035] The interval between the two light detection sections is fixed. According to this configuration, the angle range of the deflection angle can be smoothly detected by detecting the time difference.

[0036] Preferably, in the optical scanning device of the present application, the pair of inclined surfaces are formed to be left-right symmetrical with respect to a vertical plane perpendicular to the flat reflecting surface of the flat reflecting section.

[0037] According to this configuration, the light receiving intensity of the index light spot at the light detection section can be increased.

[0038] Preferably, in the optical scanning device of the present application, it is characterized in that,

[0039] When the inclination angle of the inclined surface of the longitudinal groove with respect to the flat reflecting surface is set to α, 2 x α is in the range of 80° to 120°.

[0040] According to this configuration, the light receiving intensity of the index light spot at the light detection section can be increased.

[0041] Preferably, in the optical scanning device of the present application,

[0042] The mirror section has the flat reflecting surface and the groove type reflecting section on the surface of a common substrate layer composed of a crystal layer of silicon,

[0043] The Miller indices of the main surface of the crystal layer and the inclined surface of the longitudinal groove are one or the other of (100) and (111).

[0044] According to this configuration, the inclined surface of the groove type reflecting section can be smoothly formed to have a desired inclination angle using the Miller indices of the crystal surface of silicon.

[0045] Preferably, in the optical scanning device of the present application, the longitudinal groove is open at least in part on the back surface side.

[0046] According to this configuration, the detection accuracy of the deflection angle of the mirror section can be improved by preventing the 3rd reflected light from being incident on the light detection section.

[0047] Preferably, in the optical scanning apparatus of the present invention, the inclined surface of the longitudinal groove is formed by a surface-side inclined surface portion, which is the surface-side inclined surface portion when the inclined surface of the V-groove is divided into a surface-side inclined surface portion and a back-side inclined surface portion by a dividing plane parallel to the flat reflective surface. The V-groove is the V-groove when the longitudinal groove is configured to open towards the surface side of the mirror portion.

[0048] When the lengths of the inclined surface portion and the inclined back surface portion in the cross-section of the V-groove are set to Da and Db respectively, and the inclination angle of the inclined surface of the longitudinal groove relative to the flat reflecting surface is set to α, the settings are as follows:

[0049] Da:Db=|tan(2×α)|:|tan(α)|.

[0050] Based on this configuration, the length of the inclined surface that prevents three reflected rays from incident on the light detection unit can be appropriately determined.

[0051] Preferably, in the optical scanning device of the present invention, the groove-shaped reflective portion is configured to overlap with the first rotation axis when the mirror portion is viewed from the front.

[0052] According to this configuration, the deflection angle can be detected without obstruction even when the lens is viewed from the front and deflected to either side of the deflector.

[0053] Preferably, in the optical scanning device of the present invention, the groove-shaped reflective portion occupies the central portion of the mirror portion.

[0054] According to this configuration, by increasing the intensity of the incident light incident on the groove-shaped reflector, the intensity of the index spot can be increased.

[0055] Preferably, in the optical scanning apparatus of the present invention, the optical deflector includes a second actuator that causes the mirror portion to reciprocate about a second rotation axis orthogonal to the first rotation axis.

[0056] The light detection unit is formed in an elongated shape in the scanning direction of the index light spot when the mirror reciprocates around the second rotation axis.

[0057] According to this configuration, the light detection unit is formed in an elongated shape in the scanning direction of the index light spot when the mirror reciprocates around the second rotation axis. Therefore, the first deflection angle can be detected without obstruction relative to the light deflector that performs two-dimensional scanning of the scanned light spot.

[0058] Preferably, in the optical scanning device of the present invention, the groove-shaped reflective portion has a plurality of the longitudinal grooves.

[0059] Based on this configuration, by setting multiple longitudinal grooves, the light intensity of the index light spot at the light detection unit can be increased.

[0060] Preferably, in the optical scanning device of the present invention, the spacing Dp of the plurality of longitudinal slots is set by the formula (2) described later.

[0061] According to this configuration, the photodetector is located at a position where the index light spots reflected from each longitudinal groove are enhanced by mutual interference. This increases the intensity of the index light spots received by the photodetector.

[0062] Brief description of the attached diagram

[0063] Figure 1 This is a structural diagram of a single-axis (one-dimensional) scanning optical scanning device.

[0064] Figure 2 This is a cross-sectional view of the groove-shaped reflector after cutting through the center of the mirror and perpendicular to the axis of rotation.

[0065] Figure 3 This is an explanatory diagram showing the relationship between the deflection angle of the mirror and the emission direction of each detection beam.

[0066] Figure 4 This is an illustration of two reflected beams.

[0067] Figure 5 It is a graph showing the relationship between the deflection angle of the mirror and the exit angle of each reflected light emitted from the light deflector.

[0068] Figure 6A It is a graph showing the relationship between the intensity of an index light spot of a light detection unit and the difference in tilt angle of the tilted surface for various deflection angles.

[0069] Figure 6B This is a graph showing the relationship between the intensity of the index spot of another optical detection unit and the difference in tilt angle of the tilted surface for various deflection angles.

[0070] Figure 7A It is a graph showing the relationship between the sum of the tilt angles of each tilted surface at a light detection unit and the intensity of the index light, using various deflection angles.

[0071] Figure 7B This is a graph showing the relationship between the sum of the tilt angles of each tilted surface at another light detection unit and the intensity of the index light, using various deflection angles.

[0072] Figure 8 This is an explanatory diagram schematically illustrating the depiction achieved by the optical scanning device.

[0073] Figure 9 This is a schematic diagram showing the relationship between the scanning spot, the index spot, and the photodetector.

[0074] Figure 10A It is a graph showing the relationship between the deflection angle of a lens at a light detection unit and the standardized difference.

[0075] Figure 10B It is a graph showing the relationship between the deflection angle of the mirror at another light detection unit and the standardized difference.

[0076] Figure 11 It is about Figure 10B A schematic diagram showing the relative positions of the scanning spot and index spot at P1-P5 and the photodetector at the photodetector unit.

[0077] Figure 12 It is a three-dimensional view of a groove-shaped reflector with multiple longitudinal grooves.

[0078] Figure 13 This is an explanatory diagram about countermeasures to prevent triple reflection of light.

[0079] Figure 14 It is a groove-shaped reflector with countermeasures against three-fold reflected light.

[0080] Figure 15 It means that it was adopted. Figure 1 The graph shows the relationship between the deflection angle and the intensity of the second reflected light when the groove-shaped reflector is used.

[0081] Figure 16 This is a graph showing the relationship between the emission angle and the intensity of light on the emission side under various deflection angles of the mirror, as investigated through experiments.

[0082] Figure 17 This is a graph showing the experimental results comparing the intensity distribution of the emitted light relative to a specified deflection angle between the implementation method and the comparative example.

[0083] Figure 18 It means Figure 17 A photo of the experimental results.

[0084] Figure 19 This is a structural diagram of an optical scanning device equipped with a two-dimensional scanning type optical deflector.

[0085] Figure 20 This is a structural diagram of an optical scanning device capable of detecting the deflection angle of a mirror around a second rotation axis. Detailed Implementation

[0086] Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments. In addition to the following embodiments, various configurations may be included within the scope of the technical concept of the present invention.

[0087] In the illustrated embodiments, the same reference numerals are used for common constituent elements. In various embodiments, different letters are used for the reference numerals of paired constituent elements. It should be noted that when referring collectively to elements with accompanying letter reference numerals, only the reference numerals with the letters omitted are used.

[0088] (Single-axis scanning optical scanning device)

[0089] Figure 1 This is a structural diagram of a single-axis (one-dimensional) scanning optical scanning device 1. The optical scanning device 1, being a single-axis scanning type optical scanning device, includes a single-axis scanning type optical deflector 3. In addition to the optical deflector 3, the optical scanning device 1 also includes a control unit 2, optical detection units 4a and 4b, and a light source 5.

[0090] The light source 5 is, for example, a laser light source. The light source 5 emits a primary light La, which is its original light. The primary light La is incident on the surface of the mirror 30 as the incident light of the light deflector 3. In this example, the surface of the circular mirror 30 is composed of a flat reflective portion 38 occupying most of the area and a groove-shaped reflective portion 39 disposed at the center O of the mirror 30.

[0091] The reflective surface of the flat reflective portion 38 is formed by a flat plane. In contrast, the groove-shaped reflective portion 39 has a V-groove-shaped reflective surface.

[0092] The light incident on the planar reflector 38 from the original light La constitutes the scanning light Lb, which exits from the planar reflector 38. The light incident on the slotted reflector 39 from the original light La constitutes the detection light Lc, which exits from the slotted reflector 39. The detection light Lc includes a first-reflection light L1, a second-reflection light L2, and a third-reflection light L3. Figure 3 The text details the first reflection L1, the second reflection L2, and the third reflection L3.

[0093] The control unit 2 includes a control device 21, a light source driving device 22, and an actuator driving device 23. The control device 21 further includes a deflection angle detection unit 26.

[0094] The light source driving device 22 and the actuator driving device 23 respectively drive the piezoelectric actuator 32 of the light source 5 and the light deflector 3. The light source driving device 22 drives the light source 5 to control the lighting, extinguishing and brightness of the light source when it is lit. The piezoelectric actuator 32 of the light deflector 3 is driven by the actuator driving device 23, thereby controlling the reciprocating rotation of the mirror 30 around the rotation axis 36.

[0095] The deflection angle detection unit 26 detects the deflection angle θ of the exit lens 30 relative to the optical deflector 3 based on the detection signals from each optical detection unit 4. Figure 3The control device 21 drives the light source 5 and the piezoelectric actuator 32 synchronously based on the deflection angle θ.

[0096] Except for the mirror 30, the single-axis scanning type optical deflector 3 is identical to the known single-axis piezoelectric optical deflector (e.g., Japanese Patent Application Publication No. 2014-056020). Therefore, a brief description of the optical deflector 3 will be provided. It should be noted that, for ease of explanation of the structure of the optical deflector 3, a three-axis orthogonal coordinate system of X, Y, and Z axes is defined.

[0097] The rotation axis 36 passes through the center O of the mirror portion 30 and extends along the Y-axis. Torsion bars 31a and 31b extend from each side of the mirror portion 30 along the rotation axis 36. Piezoelectric actuators 32a to 32d all extend in the X-axis direction. Piezoelectric actuators 32a and 32b are disposed on both sides of the torsion bar 31a in the X-axis direction and are located between the torsion bar 31a and the support frame 33. Piezoelectric actuators 32c and 32d are disposed on both sides of the torsion bar 31b in the X-axis direction and are located between the torsion bar 31b and the support frame 33.

[0098] The dimensions of each part of the mirror portion 30 are as follows. The mirror portion 30 is formed into a circular shape of 1 mmφ to 2 mmφ. The groove-shaped reflective portion 39 is square, with a side length of several tens of μm to several hundred μm.

[0099] The piezoelectric actuator 32 causes its junction with the torsion bar 31 to reciprocate about the rotation axis 36. This transmits the torsional vibration of the torsion bar 31 to the mirror 30, causing the mirror 30 to reciprocate about the rotation axis 36 at a predetermined resonant frequency. As a result, the scanning light Lb reciprocates within the amplitude (deflection angle range) Wb.

[0100] In the following Figures 2-4 Detailed explanation Figure 1 The document describes the scanning light Lb and the secondary reflected light L2 (detection light Lc). Scanning spot 50 is the spot generated at the target location by the scanning light Lb, which is generated by the reflection of the original light La at the flat reflector 38. Index spots 51a and 51b are the spots generated at the target location by the secondary reflected light L2 in the detection light Lc, which is generated by the reflection of the original light La at the grooved reflector 39. Figure 8 The following figures will provide a detailed description of the scanning spot 50 and the index spots 51a and 51b.

[0101] (Indicator light)

[0102] Figure 2 This is a cross-sectional view of the groove-shaped reflective portion 39 after cutting a plane through the center O of the mirror portion 30 and perpendicular to the rotation axis 36. It should be noted that... Figure 2The deflection angle θ of the mirror portion 30 shown in the diagram is 0°. It should be noted that in this embodiment, the deflection angle θ is defined as 0° when the normal 45 of the flat reflecting portion 38 is parallel to the Z-axis. Figure 2 In the diagram, the negative side of the Z-axis is the surface side of the mirror 30, and the positive side of the Z-axis is the back side of the mirror 30.

[0103] The reflected light emitted from the mirror 30 includes scanning light Lb and detection light Lc. The detection light Lc includes a first reflection L1, a second reflection L2, and a third reflection L3.

[0104] The groove-shaped reflector 39 has a longitudinal groove 41 extending parallel to the Y-axis. Figure 2 The longitudinal groove 41 is shown in cross-sectional view. The longitudinal groove 41 is formed by a V-shaped groove having a pair of inclined surfaces 42a, 42b facing each other in such a way that the groove width narrows towards the bottom.

[0105] Figure 3 This is an explanatory diagram regarding the relationship between the deflection angle θ of the mirror 30 and the emission direction of each detection beam Lc. Figure 3 In this context, it is assumed that the original light La is incident on the center O of the mirror 30 from a deflection angle θ = -90°. The normal 45 extends perpendicularly to the flat reflecting surface of the flat reflecting part 38.

[0106] It should be noted that the emission angle γ is defined for the emission directions of the scanning light Lb and the detection light Lc from the mirror 30. The emission angle γ is defined as the emission direction of the reflected light relative to the positive direction of the Z-axis. Figure 3 In this process, the original light La is parallel to the Z-axis and travels from the positive side to the negative side of the Z-axis. Therefore, the emission angle γ is the angle relative to the original light La, which is oriented in the reversed direction of emission from the mirror 30. It should be noted that the sign of the emission angle γ is defined as the positive and negative sides of the X-axis, respectively.

[0107] The exit angle γ of the first-reflected beam L1 and the third-reflected beam L3 varies with the deflection angle θ. In contrast, the exit angle γ of the second-reflected beam L2 becomes a fixed angle independent of the deflection angle θ. Figure 2 In the middle, the exit angle γ of the second reflected light L2 is ±38.8°.

[0108] Figure 4 This is an explanatory diagram of the second reflected light L2. α1 and α2 represent the tilt angles of the inclined surfaces 42a and 42b relative to the flat reflecting surface of the flat reflecting part 38. It should be noted that the tilt angle α is the tilt angle of the inclined surfaces 42a and 42b relative to the surface parallel to the flat reflecting part 38. In the illustrated embodiment, α1 = α2 = 54.7°. The original light La is incident on the groove-shaped reflecting part 39 from a constant direction.

[0109] γ' is the angle between the original light La and the second reflected light L2. A is the incident angle of the original light La relative to the inclined surface 42a, which varies according to the deflection angle θ. The sum of the interior angles of a triangle is 180°, therefore, γ' + 2 × A + 2 × (180° - A - α1 - α2) = 180° holds true. As a result, γ' becomes a fixed value, γ' = 2 × α1 + 2 × α2 - 180°, independent of the deflection angle θ of the mirror 30. Therefore, when the incident direction of the original light La is set to be parallel to the Z-axis, γ' = γ, and the exit angle γ of the second reflected light L2 becomes a fixed value independent of the deflection angle θ. When α1 = α2 = 54.7°, the exit angle γ of the second reflected light L2 becomes a fixed value of ±38.8°.

[0110] like Figure 8 As will be explained later, the second reflected light L2 constitutes the index light when the detection mirror 30 is deflected at an angle θ. Therefore, the emission angle γ of the second reflected light L2 is specifically referred to as the "index angle".

[0111] The reason for setting the emission direction of the second reflected light L2 to 38.8° is as follows. This is related to the crystal orientation of silicon in the wafer on which the optical deflector 3 and the optical deflector 103 described later are manufactured. That is, by utilizing the crystal orientation of silicon, α1=α2=α=54.7° can be easily obtained.

[0112] That is, when the optical deflector 3 is manufactured from a silicon substrate, the Miller index of the main surface in a typical silicon substrate is (100). On the other hand, the silicon crystal has crystal planes at (100) and (111), and the angle between (100) and (111) is 54.7°. Therefore, if the surface of the silicon substrate is processed by anisotropic etching, it is easy to manufacture a longitudinal groove 41 with an inclined surface 42 having an inclination angle α = 54.7°.

[0113] Specifically, when using alkaline aqueous solutions such as KOH (potassium hydroxide), TMAH (tetramethylammonium hydroxide), and EDP (ethylenediamine catechol) as etchants for anisotropic etching, the (111) surfaces of the inclined surfaces 42a and 42b can be selectively formed. When using a silicon substrate with a main surface of (100), a stable α of 54.7°, which is the angle between the (100) and (111) surfaces, can be obtained.

[0114] Figure 5 This is a graph showing the relationship between the deflection angle θ of the mirror 30 and the exit angle γ of each reflected light L1 to L3 from the light deflector 3. It should be noted that... Figure 5 In the given information, let α1 = α2 = 54.7°.

[0115] according to Figure 5The emission angle γ of the first-reflected light L1 and the third-reflected light L3 varies with the change in deflection angle θ. In contrast, the absolute value of the emission angle γ of the second-reflected light L2 is approximately fixed at 38.8° on both the - side and the + side.

[0116] Figure 6A and Figure 6B This is a graph showing the relationship between the intensity of the index light spots 51a and 51b at each deflection angle θ at light detection unit 4a (one light detection unit) and light detection unit 4b (another light detection unit), and the difference in tilt angle (=α1-α2) between the tilted surfaces 42a and 42b. The scale of the intensity of the index light (secondary reflected light L2) on the vertical axis is a relative value.

[0117] from Figure 6A and Figure 6B It can be seen that when the tilt angle difference is set to 0°, the relative intensity of the second reflected light L2 throughout the entire deflection range of the mirror 30 can be increased.

[0118] Figure 7A and Figure 7B This is a graph showing the relationship between the sum of the tilt angles α1 and α2 of the tilted surface 42a and 42b at each deflection angle θ, and the intensity of the index light. It should be noted that... Figure 7A and Figure 7B In the chart, let α1 = α2 = α, and the sum of the tilt angles = 2 × α.

[0119] from Figure 7A and Figure 7B It is evident that when the mirror 30 is symmetrically deflected relative to the vertical plane 43± of the reflecting mirror, it is advantageous to increase the relative intensity of the second reflected light L2 within the range of tilt angle total = 80° to 120°, particularly within the range of approximately 100° to approximately 110°. And 2 × 54.7° is contained within the advantageous tilt angle total range of 80° to 120°.

[0120] Figure 8 This is a schematic illustration of the optical scanning device 1. It should be noted that the optical scanning device 1 is a one-dimensional optical scanning device; therefore, the depicted area 56 is also a one-dimensional depicted area. In a two-dimensional optical scanning device (described later)... Figure 19 as well as Figure 20 In the case of the light deflector 103, the depicted area 56 becomes a two-dimensional area that extends not only horizontally but also vertically.

[0121] The mirror 30 reciprocates about the rotation axis 36. A portion of the original light La incident on the mirror 30 that strikes the flat reflector 38 becomes scanning light Lb and exits from the mirror 30. The scanning light Lb generates a scanning spot 50 at the target location. The scanning spot 50 moves reciprocally along the scanning trajectory 55 as the mirror 30 reciprocates about the rotation axis 36. The depiction area 56 is set at the center of the scanning trajectory 55, excluding both ends.

[0122] Of the original light La incident on the mirror 30, the portion that is incident on the groove-shaped reflector 39 becomes the detection light Lc and is emitted from the mirror 30. The second reflected light L2 in the detection light Lc becomes the emission angle γ = ±38.8°, independent of the reciprocating rotation of the mirror 30 around the rotation axis 36.

[0123] The photodetectors 54a and 54b are, for example, composed of PDs (photodetectors). The photodetectors 54a and 54b are configured as the first and second photodetectors at directions of -38.8° and +38.8°, respectively, to receive the index light spots 51a and 51b of the second reflected light L2. Furthermore, the photodetectors 54a and 54b are positioned outside the depicting area 56 in the scan trajectory 55.

[0124] Figure 9 This is a schematic diagram illustrating the relationship between the scanning light spot 50, the index light spots 51a and 51b, and the photodetectors 4a and 4b. The scanning light spot 50 is generated at the target location of the scanning light Lb generated by the reflection of the original light La by the flat reflector 38. Index light spots 51a and 51b are generated on the light-receiving surfaces of the photodetectors 4a and 4b, respectively, where the photodetectors 4a and 4b serve as the targets for the secondary reflected light L2a and L2b generated by the reflection of the original light La by the grooved reflector 39, respectively.

[0125] The light detection units 4a and 4b are located on the scanning trajectory 55 of the scanning light spot 50 and are respectively located on the optical paths of the second reflected light L2a and the second reflected light L2b.

[0126] Figure 10A and Figure 10B These are graphs showing the relationship between the deflection angle θ of the mirror 30 on the photodetectors 4a and 4b and the standardized difference Ev.

[0127] The standardized difference Ev is defined by the following formula (Equation 1).

[0128] (Equation 1)

[0129]

[0130] In Equation 1, Va and Vb are the output voltages of the photodetectors 54a and 54b in each photodetector unit 4, respectively.

[0131] In Equation 1, the numerator on the right-hand side is the difference between Va and Vb. The denominator on the right-hand side is the sum of Va and Vb, and the difference in the numerator is the standardized difference Ev, which is used to generate a standardized difference independent of the type of optical scanning device 1.

[0132] The photodetectors 4a and 4b are designed such that the centers of the index light spots 51a and 51b overlap with the dividing line 53, which serves as the boundary line between the photodetectors 54a and 54b. However, in practice, due to manufacturing errors, the dividing line 53 may sometimes deviate from the reflection direction of the index light spots 51a and 51b when the photodetectors 4a and 4b are installed. In this case, even if the deflection angle of the mirror 30 becomes the reflection angle of the second-order reflected light L2, under the condition that α1 = α2 = 54.7°, the difference Va-Vb will become a value that changes relative to 0 (zero) depending on the intensity of the first-order reflected light L1 and the second-order reflected light L2.

[0133] However, under the condition of α1=α2=54.7°, the normalized difference Ev (Equation 1) can eliminate the influence of the intensity difference between the second reflected light L2 from the groove-shaped reflector 39 and the first reflected light L1 from the flat reflector 38, and can accurately detect the timing of the reflection angle of the mirror 30, which is the deflection angle θ of the second reflected light L2.

[0134] That is, when the deflection angle θ = the reflection angle of the second reflected light L2 (= index deflection angle ± 38.8°), the standardized difference Ev of (Equation 1) is not zero, but the standardized difference Ev of (Equation 1) becomes the same value regardless of the intensity of the first reflected light L1 and the second reflected light L2.

[0135] It should be noted that the method for detecting the deflection angle θ is not limited to the differential method in (Equation 1). It can also be replaced by detection based on the ratio (Va / Vb) of the outputs of photodetectors 54a and 54b.

[0136] Figure 11 It is about Figure 10B A schematic diagram showing the relative positions of the scanning spot 50 and index spot 51b at P1-P5 and the photodetectors 54a and 54b at the photodetector unit 4b. Sc indicates the scanning direction of the scanning spot 50.

[0137] The following, with Figure 10A and Figure 10BSimilarly, with the dividing line 53 positioned in the direction of ±38.8° of the standard emission angle γ, the normalized difference Ev at each position from P1 to P5 is explained. It should be noted that in the following explanation, it is assumed that the position of the dividing line 53 is located in the direction of the emission angle γ = ±38.8°, which is the normalized position, and that the output characteristics of the photodetectors 54a and 54b are without deviation.

[0138] At point P1, the scanning spot 50 is positioned in front of the photodetector 4b along the scanning direction Sc. The index spot 51b is located at its center, overlapping with the dividing line 53. Therefore, photodetectors 54a and 54b each receive half the light intensity of the index spot 51b. Consequently, the standardized difference Ev = 0.

[0139] At point P2, the tip of the scanning spot 50 enters the photodetector 54a. The index spot 51b is located at the same position as at point P1. Therefore, the photodetector 54a receives half the light intensity of the index spot 51b and the light intensity of the tip of the scanning spot 50. Therefore, the normalized difference Ev is Ev > 0.

[0140] At point P3, the center of the scanning spot 50 overlaps with the dividing line 53. The front half of the scanning spot 50 overlaps with the photodetector 54b. Therefore, the light intensity of the scanning spot 50, together with the index spot 51b, is also divided into two equal parts by the dividing line 53, Ev = 0. The deflection angle θ of the mirror 30 at this time is 38.8°.

[0141] At point P4, the center of the scanning spot 50 enters the photodetector 54b. Therefore, Ev < 0.

[0142] At point P5, the front half of the scanning spot 50 is located outside the photodetector 4b in the scanning direction Sc, while the rear half of the scanning spot 50 remains in the photodetector 54b. Thus, as... Figure 10B As shown on page 5, the standardized difference Ev becomes Ev < 0.

[0143] It should be noted that when the scanning spot 50 passes through the dividing line 53 of the photodetectors 4a, 4b in the scanning direction Sc, the standardized difference Ev changes from positive to negative, and the sign is reversed. Conversely, when the scanning spot 50 passes through the dividing line 53 of the photodetectors 4a, 4b in the opposite direction to the scanning direction Sc, the standardized difference Ev changes from negative to positive, and the sign is reversed.

[0144] The deflection angle detection unit 26 identifies the moment when the sign of the standardized difference Ev is reversed as the moment when the deflection angle θ of the mirror 30 is ±38.8°.

[0145] The mirror 30 reciprocates around the rotation axis 36, therefore, the scanning spot 50 moves along the scanning trajectory 55. Figure 9The scanning spot 50 moves back and forth between left and right. When the scanning spot 50 moves from left to right on the scanning trajectory 55, the deflection angle θ changes in the direction of increasing. When the scanning spot 50 moves from right to left on the scanning trajectory 55, the deflection angle θ changes in the direction of decreasing.

[0146] In the light detection unit 4a, the moment when the standardized difference Ev of the light detection unit 4a reverses from positive to negative is detected as the moment when the scanning light spot 50 passes through the dividing line 53 of the light detection unit 4 from the outside to the inside. The moment when the standardized difference Ev of the light detection unit 4a reverses from negative to positive is detected as the moment when the scanning light spot 50 passes through the dividing line 53 of the light detection unit 4 from the inside to the outside.

[0147] In the light detection unit 4b, the moment when the standardized difference Ev of the light detection unit 4b reverses from positive to negative is detected as the moment when the scanning light spot 50 passes through the dividing line 53 of the light detection unit 4 from the inside to the outside. The moment when the standardized difference Ev of the light detection unit 4b reverses from negative to positive is detected as the moment when the scanning light spot 50 passes through the dividing line 53 of the light detection unit 4 from the outside to the inside.

[0148] The deflection angle detection unit 26 continuously monitors the outputs of the light detection units 4a and 4b. The deflection angle detection unit 26 sets the moment when the light detection unit 4a changes from positive to negative as time t1, and the moment when the light detection unit 4b changes from positive to negative as time t2. The time difference t2-t1 can be used to determine the time required for the deflection angle θ of the mirror 30 to change from -38.8° to +38.8°. On the other hand, the period of the reciprocating rotation of the mirror 30 around the rotation axis 36 and the distance between the light detection units 4a and 4b are fixed. Therefore, based on the time difference t2-t1 and the distance, the scanning speed of the scanning spot 50 can be calculated, and further, the maximum deflection angle θ of the mirror 30 around the rotation axis 36 (in other words, the range of angles within which the deflection angle θ changes or the amplitude of the scanning spot 50) can be detected based on this scanning speed.

[0149] Figure 12 This is a perspective view of a groove-shaped reflective section 40 having multiple longitudinal grooves 41. In the groove-shaped reflective section 39, there is only one longitudinal groove 41, therefore the intensity of the index light spots 51a and 51b is low. In contrast, the groove-shaped reflective section 40 has multiple longitudinal grooves 41. As a result, the light intensity received by the index light spots 51a and 51b at the photodetectors 4a and 4b can be increased.

[0150] On the other hand, when multiple longitudinal grooves 41 are present, the secondary reflected light L2 reflected from each longitudinal groove 41 interferes with each other. By utilizing the interference effect to enhance the secondary reflected light L2, the light intensity of the index light spots 51a, 51b at the photodetectors 4a, 4b can be further increased.

[0151] Therefore, the spacing Dd of the longitudinal grooves 41 (the spacing of the longitudinal grooves 41 in the X-axis direction when the optical deflector 3 is in a stationary state) is set using the following formula (2).

[0152] (Equation 2)

[0153]

[0154] In Equation 2, m is a natural number, λ is the wavelength of the original light La, and α1 and α2 are 54.7° in this embodiment.

[0155] The spacing Dp of the longitudinal grooves 41 along the X-axis can be calculated according to (Equation 2). Therefore, the position of the light detection unit 4 becomes the position where multiple secondary reflected beams L2 reflected from the groove-shaped reflector 40 mutually reinforce each other. Thus, the output S / N of the light detection unit 4 can be increased, improving the detection accuracy of the deflection angle θ.

[0156] (Countermeasures against 3 reflected beams)

[0157] then, Figure 13 This is an explanatory diagram regarding countermeasures to prevent third-order reflection L3. It should be noted that for the groove-shaped reflector 40 ( Figure 12 The statement outlines countermeasures for the third reflected light L3, but for the groove-shaped reflector 39 ( Figure 2 The same countermeasures can also be applied.

[0158] For ease of explanation, we define a first plane 59, a second plane 60, and a third plane 62 that are parallel to each other. The first plane 59 is the plane at the location of the opening of the longitudinal groove 41 on the surface side of the light deflector 3 in the Z-axis direction. The flat reflective surface of the flat reflector 38 is contained in the first plane 59. The third plane 62 is the plane that connects the bottoms of the valleys of the plurality of longitudinal grooves 41 formed by V-grooves in the groove-shaped reflector 40.

[0159] The second plane 60 is set as a dividing plane at the midpoint between the first plane 59 and the third plane 62 in the Z-axis direction. The inclined surfaces 42a and 42b are divided into a surface-side inclined surface portion Fa and a back-side inclined surface portion Fb by the second plane 60.

[0160] The length of the surface-side inclined surface portion Fa on the cross-section of the longitudinal groove 41 is set as Da. The length of the back-side inclined surface portion Fb on the cross-section of the longitudinal groove 41 is set as Db. Dc is the dimension in the X-axis direction between adjacent intersection lines 61b and 61a in the X-axis direction of the -side and +side relationship. Dd is the dimension in the X-axis direction between adjacent intersection lines 61a and 61b in the X-axis direction of the -side and +side relationship. De is the dimension of the surface-side inclined surface portion Fa in the Z-axis direction (depth direction of the longitudinal groove 41), and Df is the dimension of the back-side inclined surface portion Fb in the Z-axis direction.

[0161] The following relationship (Equation 3) exists between Da and Df. Wherein, α1 = α2 = α.

[0162] (Formula 3): Da:Db=Dc:Dd=De:Df=|tan(2×α)|:|tan(α)|.

[0163] Figure 14 It is the cross-section of the groove-shaped reflector 69 equipped with countermeasures against the third reflected light L3. The inclined surface 72 of the longitudinal groove 71 of the groove-shaped reflector 69 is configured as follows: from the groove-shaped reflector 39 ( Figure 13 The inclined surfaces 42a and 42b of the longitudinal groove 41 have the back side inclined surface portion Fb removed, leaving only the surface side inclined surface portion Fa.

[0164] The plurality of longitudinal grooves 71 of the groove-shaped reflector 69 are identical to the plurality of longitudinal grooves 41 of the groove-shaped reflector 39, and are aligned longitudinally parallel to the rotation axis 36. The length of the inclined surface 72 is set to Da( Figure 13 Each longitudinal groove 71 has a valley-side opening 75 on the back side. A recess 77 is formed on the back side of the groove-shaped reflective portion 69, and each valley-side opening 75 and the recess 77 are connected together.

[0165] As a result, in the groove-shaped reflector 69, the original light La is reflected towards the groove-shaped reflector 39 ( Figure 3 The original light La, irradiated by the inclined surface portion Fb on the back side of the mirror 30, passes through the valley bottom opening 75 towards the back side of the mirror 30. Therefore, in the groove-shaped reflector 69, the generation of the tertiary reflected light L3, which overlaps with the secondary reflected light L2, is prevented.

[0166] (Other applications of indicator light)

[0167] Figure 15 Indicates adoption Figure 12 The relationship between the deflection angle θ of the slotted reflector 40 and the intensity of the second-reflected light L2. When multiple longitudinal slots 41 exist, the result of interference between the multiple second-reflected lights L2 reflected from the multiple longitudinal slots 41 is as follows: Figure 15As shown, the intensity of the index spot 51 at the light detection unit 4 changes in response to the change in deflection angle θ.

[0168] Therefore, the control device 21 not only calculates the standardized difference Ev (=Va-Vb) between the output Va of photodetector 54a and the output Vb of photodetector 54b, but also calculates the sum of the output Va of photodetector 54a and the output Vb of photodetector 54b, Et (=Va+Vb). Furthermore, based on the sum of the sums, it can also measure the deflection angle θ other than ±38.8° (and...). Figure 15 The deflection angle θ corresponding to each valley peak.

[0169] Figure 16 This is a graph showing the relationship between the emission angle γ of the mirror 30 and the intensity of the light emitted from the emission side at various deflection angles θ. As the deflection angle θ of the mirror 30 increases, the emission angle γ of the scanning light Lb increases, but the emission angle γ of the second reflected light L2 remains constant at the index deflection angle of 38.8°. Furthermore, it can be assumed that the intensity of the light emitted from the mirror 30 can cover the entire amplitude Wb of the scanning light Lb. Figure 1 The emission angle γ was detected.

[0170] Figure 17 This is a graph showing the experimental results comparing the distribution of light intensity on the exit side with respect to a predetermined deflection angle θ in the mirror section 30 (implementation method) and a comparative example. The comparative example uses a diffraction grating type mirror section. Second-order reflected light L2 is generated in the mirror section 30, but in the comparative example, it can be considered that no noticeable diffracted light such as second-order light, third-order light, etc., is generated.

[0171] Figure 18 yes Figure 17 The photograph shows the experimental results. In the mirror 30 (implementation), two reflected lights L2 appeared at the index deflection angle. In contrast, in the comparative example (diffraction grating type mirror), no light appeared at the index deflection angle.

[0172] (Dual-axis scanning optical scanning device)

[0173] Figure 19 This is a structural diagram of an optical scanning device 101 equipped with a dual-axis (two-dimensional) scanning type optical deflector 103. As a dual-axis scanning type optical scanning device, it is equipped with a dual-axis scanning type optical deflector 103.

[0174] The difference between the optical scanning device 101 and the optical scanning device 1 is that the optical scanning device 101 has an optical deflector 103 and an optical detection unit 104 instead of the optical deflector 3 and the optical detection unit 4 of the optical scanning device 1. The optical deflector 103 and the optical detection unit 104 will be described below.

[0175] In the optical deflector 103, except for the mirror 130, the configuration is the same as that of a known biaxial piezoelectric optical deflector (e.g., Japanese Patent Application Publication No. 2017-207630). Details of the mirror 130 will be described later, and the structure of the optical deflector 103 will be briefly explained.

[0176] The optical deflector 103 includes a mirror 130, torsion bars 131a and 131b, inner piezoelectric actuators 145a and 145b, a movable frame 146, outer piezoelectric actuators 147a and 147b, and a fixed frame 148.

[0177] The first rotation axis 136 and the second rotation axis 137 are both set on the surface of the optical deflector 103 and are orthogonal at the center O of the mirror portion 130. The first rotation axis 136 is aligned with the central axis of the torsion bar 131. When the optical deflector 103 is stationary, the first rotation axis 136 and the second rotation axis 137 are in the Y-axis direction and the X-axis direction, respectively.

[0178] The inner piezoelectric actuator 145 causes the torsion bar 131 to torsionally vibrate about the first rotation axis 136 at a resonant frequency. As a result, the mirror portion 130 reciprocates about the first rotation axis 136 at a resonant frequency F1. The outer piezoelectric actuator 147 causes the movable frame 146 to reciprocate about an axis parallel to the X-axis at a non-resonant frequency F2 (F2 < F1). As a result, the mirror portion 130 reciprocates about the second rotation axis 137.

[0179] Next, the mirror portion 130 will be described in detail. Although the mirror portion 130 differs from the mirror portion 30 in that it reciprocates around the first rotation axis 136 and the second rotation axis 137, its structure itself is the same as that of the mirror portion 30. That is, the mirror portion 130 has a flat reflective portion 138 and a groove-shaped reflective portion 139 on its surface that are the same as those of the flat reflective portion 38 and the groove-shaped reflective portion 39 of the mirror portion 30, respectively.

[0180] In the optical scanning device 101, the deflection angle θ of the mirror 130 rotating about the first rotation axis 136 is detected by the optical detection units 104a and 104b. The optical detection units 104a and 104b correspond to the optical detection units 4a and 4b of the optical scanning device 1.

[0181] While the light detection units 4a and 4b are rectangular, the light detection units 104a and 104b are elongated in the Y-axis direction. This is because the mirror unit 130 also reciprocates around the second rotation axis 137. Therefore, the second reflected light L2, whose emission direction is fixed in the light scanning device 1, is also displaced in the Y-axis direction in the light deflector 103.

[0182] During the displacement of the second reflected light L2 in the Y-axis direction, the center of the displacement direction is closer to the inside in the X-axis direction relative to both ends. To correspond to this, the dividing lines of the light detection units 104a and 104b extend such that the center in the Y-axis direction is located inside the X-axis direction relative to both ends.

[0183] (Detection of non-resonance deflection angle)

[0184] Figure 20 This is a structural diagram of an optical scanning device 161 capable of detecting the deflection angle of the mirror 130 around the second rotation axis 137. Only the differences between the optical scanning device 161 and the optical scanning device 101 will be described.

[0185] The groove-shaped reflector 139 of the mirror 130 rotates 90° clockwise relative to the center O of the mirror 130 of the optical scanning device 101. As a result, the secondary reflected light L2, which is the index light reflected from the groove-shaped reflector 139, is emitted from the light deflector 103 to both sides in the Y-axis direction, and because the mirror 130 reciprocates around the first rotation axis 136, the secondary reflected light L2 is displaced in the X-axis direction.

[0186] Therefore, the photodetectors 164a and 164b that detect the second reflected light L2 are formed into an elongated shape in the X-axis direction. In addition, the dividing line 53 of the photodetectors 164a and 164b extends in such a way that the center portion in the X-axis direction is located inside the Y-axis direction relative to both ends.

[0187] The light detection units 164a and 164b, like the light detection units 4a and 4b of the light scanning device 1, detect the standardized difference Ev and the subtraction difference Es of the output voltages Va and Vb output from the light detection units 164a and 164b to the photodetectors 54a and 54b divided by the dividing line 53, respectively. In the light scanning device 161, these standardized difference Ev and subtraction difference Es correspond to the deflection angle of the mirror 130 about the second rotation axis 137. Therefore, based on the standardized difference Ev and subtraction difference Es, the deflection angle of the mirror 130 about the second rotation axis 137 can be detected.

[0188] (Supplementary examples and variations)

[0189] In one embodiment, when detecting the deflection angle θ of the mirror 30 about the first rotation axis (e.g., rotation axis 36) based on the two outputs (e.g., Va, Vb) of the first and second photodetectors (e.g., 4a, 4b), Va-Vb is used as the difference (refer to Equation 1 above). In this invention, the deflection angle θ can also be detected based on the comparison of the two outputs (e.g., Va / Vb as the ratio of the two outputs) instead of the difference.

[0190] In this embodiment, the index deflection angle, which is the deflection angle θ of the mirror 30 corresponding to the direction of travel of the index light (e.g., the second-reflected light L2), is set to 38.8°. The index deflection angle of this invention can be changed to a value other than 38.8°. For example, this can be achieved by adjusting... Figure 4 The tilt angles α1 and α2 of a pair of tilted surfaces 42a and 42b are changed to change the index deflection angle.

[0191] In one embodiment, the first rotation axis of the present invention corresponds to rotation axis 36 and first rotation axis 136, and the second rotation axis corresponds to second rotation axis 137. Alternatively, the present invention can also set the second rotation axis 137 as the first rotation axis in one embodiment.

[0192] The first actuator of the present invention corresponds to the piezoelectric actuator 32 and the inner piezoelectric actuator 145. The second actuator of the present invention corresponds to the outer piezoelectric actuator 147. In the embodiments, both the first and second actuators are piezoelectric actuators, but the first and second actuators of the present invention can also be electromagnetic coil type or electrostatic type actuators.

[0193] It should be noted that the specific structural examples of electromagnetic coil actuators are described in detail in the following documents.

[0194] "ADYalcinkaya, H. Urey, D. Brown, T. Montague, and R. Sprague, 'Two-axiselectromagnetic microscanner for high resolution distrys,' J. Microelectromech. Syst., vol. 15, no. 4, pp. 786-794, Aug. 2006." Furthermore, a detailed structural example of the aforementioned electrostatic actuator is provided in the following literature: "H. Schenk, P. Durr, D. Kunze, H. Lakner, and H. Kuck, 'Aresonantly excited 2D-micro-scanning-mirror with large deflection,' Sens. Actuators A, Phys., vol. 89, no. 1, pp. 104-111, Mar. 2001."

[0195] In the optical deflectors 3 and 103, only one slotted reflector 39 or slotted reflector 139 is provided at the center, and light detection units 4 and 104 are provided on both sides of the optical deflectors 3 and 103. In this invention, the slotted reflectors 39 and 139 are provided only on one side of the center O in the X-axis direction, and the light detection units 4 and 104 are provided only on the other side of the optical deflectors 3 and 103 in the X-axis direction, which also enables the detection of the deflection angle θ of the mirrors 30 and 130. Alternatively, the slotted reflectors 39 and 139 can be provided on both sides of the center O of the mirror 30, and the light detection unit 4 on the other side can receive the secondary reflected light L2 from the slotted reflectors 39 and 139 on one side, and vice versa.

[0196] The Miller index of the active layer of the SOI in the substrate layer forming the optical deflector 3,103 is (100), and the Miller index of the inclined surface 42 is (111). In the optical deflector of the present invention, the Miller index of the main surface of the silicon crystal layer of the substrate can also be (111), and the Miller index of the inclined surface 42 can be (100).

[0197] It should be noted that the flat reflective portions 38 and 138 and the grooved reflective portions 39, 69, 89a, 89b, and 139 are formed as a mirror layer covering the common substrate layer of the mirror portions 30 and 130. The mirror layer is composed, for example, a silicon crystal plane, a metal reflective film, or a dielectric multilayer film.

[0198] Symbol Explanation

[0199] 101, 161… Optical scanning device; 3, 103… Optical deflector; 4… Optical detection unit; 5… Light source; 21… Control device (deflection angle detection unit); 30, 130… Mirror part; 32… Piezoelectric actuator (first actuator); 36… Rotation axis (first rotation axis); 38, 138… Flat reflector; 39, 40, 69, 139… Groove reflector; 41, 71… Longitudinal groove; 42a, 42b… 72a, 72b… Inclined surface; 50… Scan spot; 51… Index spot; 53… Dividing line; 54a, 54b… Photodetector; 55… Scan trajectory; 59… First plane (flat reflective part); 60… Second plane (dividing plane); 136… First rotation axis; 137… Second rotation axis; 145… Inner piezoelectric actuator (first actuator); 147… Outer piezoelectric actuator (second actuator).

Claims

1. An optical scanning device, characterized by comprising: Possessing: a light source that emits light; a light deflector that has: a mirror portion that includes a flat reflecting portion that causes incident light, which the light source has incident on a surface side, to be emitted as scan reflected light, and a groove-shaped reflecting portion that has a longitudinal groove extending in a prescribed direction, the longitudinal groove having a pair of inclined surfaces that face each other in a manner in which a groove width of the longitudinal groove narrows from the surface side to a back surface side, the groove-shaped reflecting portion causing the incident light to be reflected on each of the pair of inclined surfaces one time each, for a total of two times, as index light; and a first actuator that causes the mirror portion to reciprocally rotate about a first rotation axis that is parallel to an extending direction of the longitudinal groove; a light detecting portion that is disposed on a scan track of a scan spot of the scan reflected light and on a light receiving position of an index spot of the index light, and is divided into a first light detector and a second light detector by a division line that divides the index spot in a scan direction of the scan reflected light; and a deflection angle detecting portion that detects a first deflection angle, which is a deflection angle of the mirror portion about the first rotation axis, on the basis of a comparison between two outputs of the first light detector and the second light detector.

2. The optical scanning device according to claim 1, wherein the deflection angle detecting portion detects on the basis of a difference between the two outputs of the first light detector and the second light detector as the comparison between the two outputs.

3. The optical scanning device according to claim 1, wherein the deflection angle detecting portion detects on the basis of a ratio between the two outputs of the first light detector and the second light detector as the comparison between the two outputs.

4. The optical scanning device according to any one of claims 1 to 3, wherein the deflection angle detecting portion takes a deflection angle of the mirror portion corresponding to a traveling direction of the index light as an index deflection angle, and detects a case where the deflection angle of the mirror portion about the first rotation axis becomes the index deflection angle on the basis of the comparison between the two outputs of the first light detector and the second light detector.

5. The optical scanning device according to claim 1, wherein the deflection angle detecting portion generates an intermediate value on the basis of the comparison between the two outputs of the first light detector and the second light detector, sets an intermediate value at a time when the scan spot is not receiving light as a reference value, corrects the intermediate value with the reference value to obtain a corrected value, and detects the first deflection angle on the basis of the corrected value.

6. The optical scanning device according to claim 2, wherein the deflection angle detecting portion takes a deflection angle of the mirror portion corresponding to a traveling direction of the index light as an index deflection angle, and detects a time when the deflection angle of the mirror portion becomes the index deflection angle on the basis of a sign inversion time of the difference.

7. The optical scanning device according to claim 5, wherein the intermediate value is a normalized difference Ev defined by the following (Formula 1), (Formula 1) 8. The optical scanning device according to claim 5, wherein ​ The light detection section is provided with one light detection section and another light detection section on both sides of the center of the deflection angle range of the scanning light spot, The deflection angle detection section detects the angle range of the deflection angle of the scanning light spot based on the time difference between the sign inversion timing at the one light detection section and the sign inversion timing at the another light detection section.

9. The optical scanning device according to claim 1, wherein The pair of inclined surfaces is formed to be left-right symmetrical with respect to a vertical plane perpendicular to the flat reflecting surface of the flat reflecting section.

10. The optical scanning device according to claim 9, wherein When the inclination angle of the inclined surface of the longitudinal groove with respect to the flat reflecting surface is set to be α, 2 x α is in the range of 80° to 120°.

11. The optical scanning device according to claim 10, wherein The mirror section has the flat reflecting surface and the longitudinal groove on the surface of a common substrate layer composed of a crystal layer of silicon, The Miller indices of the main surface of the crystal layer and the inclined surface of the longitudinal groove are one or the other of (100) and (111).

12. The optical scanning device according to claim 1, characterized by The longitudinal groove is open at least in part on the back surface side.

13. The optical scanning device according to claim 12, wherein The inclined surface of the longitudinal groove is formed by a surface-side inclined surface portion that is the surface-side inclined surface portion when a V groove, which is the longitudinal groove set to be open on the surface side of the mirror section, is divided by a division plane parallel to the flat reflecting surface into the surface-side inclined surface portion and a back surface-side inclined surface portion, When the lengths of the surface-side inclined surface portion and the back surface-side inclined surface portion in the cross section of the V groove are set to be Da, Db, and the inclination angle of the inclined surface of the longitudinal groove with respect to the flat reflecting surface is set to be α, Da: Db = |tan(2 x α)| : |tan(α)| is set. The groove-shaped reflecting section is disposed so as to overlap the first rotation axis when the mirror section is viewed from the front.

14. The optical scanning device according to claim 1, characterized by The groove-shaped reflecting section occupies the central portion of the mirror section.

15. The optical scanning device according to claim 14, characterized by 16. The optical scanning device according to claim 15, wherein The light deflection means includes a second actuator that reciprocally rotates the mirror section about a second rotation axis orthogonal to the first rotation axis, The light detection section is formed in an elongated shape in the scanning direction of the index light spot when the mirror section is reciprocally rotated about the second rotation axis. The groove-shaped reflecting section has a plurality of the longitudinal grooves.

17. The optical scanning device according to claim 1, characterized by 18. The optical scanning device according to claim 17, wherein The pitch Dp of the plurality of longitudinal grooves is set by the following (Formula 2), (Formula 2) where, in (Formula 2), m is a natural number, λ is the wavelength of the original light La, and α1 is the inclination angle of one inclined surface and another inclined surface of the pair of inclined surfaces of the longitudinal groove with respect to the flat reflecting surface of the flat reflecting section. ​

Images