JP7646785B2 - Light reflector - Google Patents

Description

The present invention relates to a light reflector that reflects light.

Conventionally, there are known scanning devices that perform optical scanning of an object to obtain information on the distance to the object, the shape, and the like. Such scanning devices have, for example, a movable mirror that variably deflects the scanning light and emits it toward the object. For example, Patent Document 1 discloses an optical device that includes a plate-shaped movable part and a reflective film formed on the movable part.

Patent No. 5146204

The scanning device has a scanning area that corresponds to the movable range of the movable mirror. For example, when a rotating mirror is used as the light deflection element, the scanning area corresponds to the maximum rotation angle of the mirror. However, the stability of the rotation of the mirror may decrease while the mirror is rotating at or near the maximum rotation angle. An example of a case in which the stability of the rotation decreases is when the maximum rotation angle of the mirror fluctuates with each rotation period.

In this case, the light emission direction corresponding to the maximum rotation angle of the mirror may differ from the designed direction, which may result in the light not being emitted to the designed position or coordinates within the scanning area. In this case, the scanning area may shrink or expand unstably, or the outer edge shape may deform unstably.

In this case, for example, scanning information obtained from an unstable portion of the scanning area may not be treated as valid scanning information. Also, it may be necessary to set an area smaller than the entire range of the light emitted from the mirror as the valid scanning area.

The present invention was made in consideration of the above points, and one of its objectives is to provide a light reflector with a stable rotation range.

The invention described in claim 1 is characterized by having a support, a rotating body supported by the support so as to rotate around a rotation axis, the rotating body having a first surface including a light-reflective area and a second surface opposite the first surface, and first and second protrusions each provided on at least one of the first surface and the second surface of the rotating body, and arranged spaced apart from each other and facing each other across the rotation axis.

1 is a diagram showing an overall configuration of a scanning device according to a first embodiment; FIG. 2 is a perspective view of a rotating element according to the first embodiment. FIG. 2 is a plan view of a rotating element according to the first embodiment. FIG. 2 is a plan view of a rotating element according to the first embodiment. FIG. 2 is a cross-sectional view of a rotating element according to the first embodiment. 1 is a schematic diagram of a system for measuring a range of light emitted from a rotating element according to a first embodiment. FIG. 6 is a diagram showing a change in rotation angle according to the ambient temperature of the rotating element according to the first embodiment; FIG. FIG. 13 is a plan view of a rotating element according to a first modified example of the first embodiment. FIG. 11 is a plan view of a rotating element according to a second modified example of the first embodiment. FIG. 11 is a cross-sectional view of a rotating element according to a third modified example of the first embodiment. FIG. 13 is a cross-sectional view of a rotating element according to a fourth modified example of the first embodiment.

The following describes in detail an embodiment of the present invention.

Figure 1 is a schematic layout diagram of a scanning device 10 according to the first embodiment. In this embodiment, the scanning device 10 is a scanning type distance measuring device that performs optical scanning of a predetermined area (hereinafter referred to as the scanning area) R0 and measures the distance to an object OB present within the scanning area R0. The configuration of the scanning device 10 will be explained using Figure 1. Note that Figure 1 shows a schematic diagram of the scanning area R0 and the object OB.

The scanning device 10 has a light source 11 that generates and emits, for example, pulsed light as the primary light L1. In this embodiment, the light source 11 generates laser light having a peak wavelength in the infrared region as the primary light L1 and emits it intermittently.

The scanning device 10 has a rotating element 12 that rotates around mutually orthogonal rotation axes (second and first rotation axes) AX and AY and reflects the primary light L1 emitted from the light source 11 toward the scanning region R0. In this embodiment, the rotating element 12 functions as a deflection element that deflects the emitted light L1 in a variable direction. The rotating element 12 emits the reflected emitted light L1 as secondary light L2. The secondary light L2 becomes the scanning light for scanning the scanning region R0.

In this embodiment, the rotating element 12 is a rotating mirror having one light reflecting surface 12S that rotates around the rotation axes AX and AY. In addition, the light reflecting surface 12S of the rotating element 12 is reflective to at least the primary light L1.

The rotating element 12 is also configured so that the light reflecting surface 12S rotates periodically. Therefore, the emission direction of the secondary light L2 emitted from the rotating element 12 changes periodically. The area irradiated with the secondary light L2 within the period of change in the emission direction of the secondary light L2 becomes the scanning area R0.

For example, the scanning region R0 is a virtual three-dimensional space into which the secondary light L2 is emitted. In FIG. 1, the outer edge of the scanning region R0 is shown diagrammatically by a dashed line. For example, the scanning region R0 can be defined as a cone-shaped space having a height range along a height direction D1 corresponding to the axial direction of the rotation axis AY, a width range along a width direction D2 corresponding to the axial direction of the rotation axis AX, and a depth range along a depth direction corresponding to the axial direction of the optical axis of the scanning light L2 reflected by the light reflecting surface 12S when not rotating.

For example, the normal vector of the light reflecting surface 12S of the rotating element 12 changes periodically in response to the rotation of the rotating element 12. In this embodiment, the light source 11 emits the primary light L1 toward the rotating element 12 so that the primary light L1 is incident on the light reflecting surface 12S of the rotating element 12.

Therefore, for example, the height direction range of the scanning region R0 corresponds to the range of change of the axial component of the rotation axis AY in the axial direction of the optical axis of the primary light L1 and the optical axis of the secondary light L2 determined by the normal vector of the light reflecting surface 12S of the rotating element 12 at the time of incidence of the primary light L1. The width direction range of the scanning region R0 corresponds to the range of change of the axial component of the rotation axis AX in the axial direction of the secondary light L2. The depth direction range of the scanning region R0 corresponds to the distance range in which the secondary light L2 can maintain a predetermined intensity (intensity detectable by the scanning device 10).

When a virtual plane located a predetermined distance away from the rotating element 12 within the scanning region R0 is defined as a scanning surface R1, the scanning surface R1 can be defined as a two-dimensional region extending along the height direction D1 and width direction D2. The secondary light L2 is emitted toward the scanning region R0 so as to scan this scanning surface R1.

Also, as shown in FIG. 1, if an object OB (i.e., an object or material that is reflective or scattering to the secondary light L2) is present in the scanning region R0, the secondary light L2 is reflected or scattered by the object OB. A portion of the secondary light L2 reflected by the object OB travels as tertiary light L3 along substantially the same optical path as the secondary light L2 in the opposite direction to the secondary light L2, and returns to the rotating element 12.

The scanning device 10 has a separation element 13 that is provided on the optical path of the primary light L1 and separates the primary light L1 and the tertiary light L3, and a light receiving element 14 that receives the separated tertiary light L3. The separation element 13 is, for example, a beam splitter that reflects the primary light L1 and transmits the tertiary light L3.

In this embodiment, the light receiving element 14 receives tertiary light L3, which is light projected through the rotating element 12, reflected by the object OB, and passed through the rotating element 12. The light receiving element 14 also has at least one detection element that detects the tertiary light L3 and generates an electrical signal indicating the detection result of the tertiary light L3, for example, the intensity value of the tertiary light L3. The scanning device 10 generates the electrical signal generated by the light receiving element 14 as the scanning result of the scanning region R0.

Although not shown, the scanning device 10 may have an optical system provided on the optical path of the primary light L1 between the light source 11 and the rotating element 12 to shape the primary light L1. The scanning device 10 may also have an optical system provided on the optical path of the tertiary light L3 between the separation element 13 and the light receiving element 14 to focus the tertiary light L3. These optical systems may include, for example, at least one lens and may include a filter.

The scanning device 10 has a control unit 15 that drives and controls the light source 11, the rotating element 12, and the light receiving element 14. The control unit 15 has a light source control unit 15A that drives and controls the light source 11, a rotating element control unit 15B that drives and controls the rotating element 12, and a light receiving element control unit 15C that drives and controls the light receiving element 14.

The control unit 15 also has a distance measuring unit 15D that measures the distance to the object OB based on the result of receiving the tertiary light L3 by the light receiving element 14. In this embodiment, the distance measuring unit 15D detects a pulse indicating the tertiary light L3 from the electrical signal generated by the light receiving element 14. The distance measuring unit 15D also measures the distance to the object OB (or a part of its surface area) by a time-of-flight method based on the time difference between the emission timing of the secondary light L2 and the reception timing of the tertiary light L3. The distance measuring unit 15D also generates data (distance measurement data) indicating the measured distance information.

In addition, in this embodiment, the distance measurement unit 15D divides the scanning area R0 (scanning surface R1) into a plurality of distance measurement points (scanning points) and generates an image (distance measurement image) of the scanning area R0 that shows the distance measurement results (distance values) of each of the plurality of distance measurement points as pixels. In this embodiment, the distance measurement unit 15D associates the distance measurement points with information indicating the displacement of the light reflecting surface 12S of the rotating element 12, and generates image data that shows a two-dimensional map or a three-dimensional map of the scanning area R0.

The distance measuring unit 15D also generates one distance measuring image for each scanning period, which is the period during which the scanning area R0 is scanned, by setting the period during which the emission direction of the secondary light L2 changes. Note that the distance measuring unit 15D may be connected to a display unit (not shown) that displays the distance measuring image, and may be configured to transmit the distance measuring image to the display unit.

Figure 2 is a schematic perspective view of the rotating element 12. In this embodiment, the rotating element 12 is a MEMS (Micro Electro Mechanical System) mirror configured so that the light reflecting surface 12S rotates around the rotation axes AX and AY.

First, in this embodiment, the rotating element 12 has a base 21 and an annular fixed frame 22 fixed to the base 21. The fixed frame 22 has a rectangular plate-like outer shape and is supported by the base 21 at the outer periphery of one of its plate surfaces.

The rotating element 12 has a first support portion 23 consisting of first and second torsion bars 23A and 23B that are each provided on the inner periphery of the fixed frame 22 and extend along the first direction (hereinafter referred to as the x direction) so as to face each other in the x direction. In this embodiment, each of the first and second torsion bars 23A and 23B has elasticity.

The rotating element 12 has an annular rotating frame 24 that is supported at its outer periphery by a first support portion 23 and rotates around a first rotation axis (an axis corresponding to the rotation axis AX, hereinafter referred to as the rotation axis AX) whose axial direction is the x direction.

In this embodiment, the rotating frame 24 is elastically supported at the end of each of the first and second torsion bars 23A and 23B opposite the fixed frame 22. In this embodiment, the rotating frame 24 has a rectangular ring shape as a whole, and has a frame-shaped inner peripheral frame portion 24A on its inner periphery. In this embodiment, the inner peripheral frame portion 24A has a portion that overlaps with the portion that forms the outer periphery of the rotating frame 24.

The rotating element 12 has a second support portion 25 consisting of third and fourth torsion bars 25A and 25B that are provided on the inner periphery of the movable frame 24 and extend along a second direction perpendicular to the x direction (hereinafter referred to as the y direction) so as to face each other in the y direction. In this embodiment, each of the third and fourth torsion bars 25A and 25B has elasticity.

The rotating element 12 has a disk-shaped rotating plate 26 that is supported at its outer periphery by a second support portion 25 and rotates around a second rotation axis (an axis corresponding to the rotation axis AY, hereinafter referred to as the rotation axis AY) whose axial direction is the y direction. The rotating element 12 also has a light reflecting film 27 that is provided concentrically with the rotating plate 26 on one plate surface of the rotating plate 26 and has light reflectivity to the primary light L1. In this embodiment, the light reflecting film 27 constitutes the light reflecting surface 12S of the rotating element 12.

The rotating element 12 also has a driving source 28 that generates a rotational force that rotates the rotating frame 24 and the rotating plate 26. In this embodiment, the driving source 28 has a first permanent magnet 28A that is provided on the base 21 and arranged to sandwich the fixed frame 22 in the y direction, and a first coil 28B that is formed on the outer periphery of the movable frame 24 and wired to surround the rotating plate 26 on the outer periphery and to be arranged inside the first permanent magnet 28A. The first permanent magnet 28A and the second coil 28B generate a rotational force that rotates the rotating frame 24 and the rotating plate 26 around the rotation axis AX.

In this embodiment, the driving source 28 has a second permanent magnet 28C provided between the rotating plate 26 and the base 21 on the base 21, and a second coil 28D wired to surround the rotating plate 26 on the inner periphery 24A of the rotating frame 24. The second permanent magnet 28C and the second coil 28D generate a rotational force that rotates the rotating plate 26 around the rotation axis AY.

In this embodiment, the rotating frame 24 has two openings 24B arranged to sandwich the rotating plate 26 in the x direction. The driving source 28 also has two magnetic bodies 28E arranged on the base 21 to extend in the z direction so that each is inserted into the opening 24B of the rotating frame 24, and to sandwich the second permanent magnet 28C and the second coil 28D in the x direction.

In addition, the rotating element control unit 15B in the control unit 15 is connected to the first and second coils 28B and 28D, and applies a voltage to the first and second coils 28B and 28D as a drive signal.

By applying a voltage to the first and second coils 28B and 28D, a rotational force is generated for the rotating frame 24 and the rotating plate 26 based on the magnetic field generated by the first and second permanent magnets 28A and 28C and the current flowing through the first and second coils 28B and 28D. For example, a rotational force around the rotation axis AX for the rotating frame 24 is generated based on the current flowing through the first coil 28B and the magnetic field in the y direction generated between the first permanent magnets 28A.

In addition, in this embodiment, a rotational force is generated around the rotation axis AY for the rotating frame 24 by the current flowing through the second coil 28D and the magnetic field generated between the second permanent magnet 28C and the magnetic body 28E, and the rotating plate 26 rotates around the rotation axis AY accordingly.

In this way, the rotating element control unit 15B functions as a drive circuit that drives the drive source 28 to rotate the rotating plate 26 (and the light reflecting surface 12S) around the rotation axes AX and AY.

In this embodiment, the rotating element control unit 15B applies voltages to the first and second coils 28B and 28D so that the rotating plate 24 rotates in a non-resonant manner around the rotation axis AX and resonates around the rotation axis AY.

Specifically, for example, the rotating element control unit 15B applies to the first coil 28B a voltage whose value changes periodically at a frequency different from the frequency for resonating the rotating frame 24 and the rotating plate 26, for example a sawtooth voltage whose value changes at a frequency lower than the resonant frequency. On the other hand, the rotating element control unit 15B applies to the second coil 28D a voltage whose value changes periodically at a frequency corresponding to the resonant frequency of the rotating frame 24 and the rotating plate 26, for example a sine wave voltage.

Note that, below, the direction perpendicular to the x and y directions may be referred to as the z direction. For example, the z direction corresponds to the normal direction of the rotating plate 26 or the light reflecting surface 12S when not rotating. The primary light L1 is incident on the light reflecting surface 12S along a direction that has a component in the z direction, for example.

Figures 3 and 4 are plan views of the vicinity of the rotating plate 26 in the rotating element 12. Figure 3 is a plan view showing the plate surface (hereinafter sometimes referred to as the first surface or front surface) 26A of the rotating plate 26 on which the light reflecting film 27 is provided. Figure 4 is a plan view showing the plate surface (hereinafter sometimes referred to as the second surface or back surface) 26B on the opposite side of the plate surface 26A of the rotating plate 26.

Figure 5 is a cross-sectional view taken along line 5-5 in Figure 3, showing the rotating plate 26 along the rotation axis AX. The configuration of the rotating element 12 in the vicinity of the rotating plate 26 will be described using Figures 3 to 5.

First, as shown in Figures 3 and 5, in this embodiment, the rotating element 12 has a surface protrusion group 30 consisting of first and second surface protrusions (first and second protrusions) 31 and 32, each of which protrudes in the z direction (direction perpendicular to the surface of the light reflecting film 27) at the outer edge of the surface of the light reflecting film 27.

In this embodiment, each of the first and second surface protrusions 31 and 32 consists of a single protrusion formed continuously in a curved shape along the outer edge of the light reflecting film 27. The first and second surface protrusions 31 and 32 are arranged spaced apart from each other across the rotation axis AY. Each of the first and second surface protrusions 31 and 32 has a symmetrical shape with respect to the rotation axis AX. The first and second surface protrusions 31 and 32 are arranged in symmetrical positions with respect to the rotation axis AY.

As shown in Figures 4 and 5, in this embodiment, the rotating element 12 has a back surface protrusion group 40 consisting of first, second and third back surface protrusions (third, fourth and fifth protrusions) 41, 42 and 43, each of which protrudes from the back surface 26B of the rotating plate 26 in the z direction (direction perpendicular to the back surface 26B of the rotating plate 26).

In this embodiment, the first and second back surface protrusions 41 and 42 are provided at positions facing the first and second front surface protrusions 31 and 32, respectively, across the rotating plate 26. The third back surface protrusion 43 is provided in an area 26BB facing the light reflecting film 27 on the back surface 26B of the rotating plate 26.

The first and second back surface protrusions 41 and 42 are formed to extend in a curved line, similar to the first and second front surface protrusions 31 and 32, respectively. The first and second back surface protrusions 41 and 42 are arranged spaced apart from each other across the rotation axis AY. The first and second back surface protrusions 41 and 42 each have a symmetrical shape with respect to the rotation axis AX. The first and second back surface protrusions 41 and 42 are arranged in symmetrical positions with respect to the rotation axis AY.

In this embodiment, the third backside protrusion 43 has a symmetrical shape with respect to each of the rotation axes AX and AY. In this embodiment, the third backside protrusion 43 is formed in a mesh or lattice shape on the back side 26B of the rotating plate 26.

Also, as shown in FIG. 5, the front surface protrusion group 30 is smaller and thinner than the back surface protrusion group 40. More specifically, for example, the width W1 of the first front surface protrusion 31 is narrower than the width W2 of the first back surface protrusion 41. Also, the height H1 of the first front surface protrusion 31 is smaller than the height H2 of the first back surface protrusion 41.

For example, the rotating plate 26 is integrally formed with the fixed frame 22, the first support portion 23, the rotating frame 24, and the second support portion 25. These can be formed by processing a semiconductor substrate such as a silicon substrate.

The back surface projection group 40 can also be formed by processing a semiconductor substrate separate from the semiconductor substrate used to form the rotating plate 26, and bonding the processed substrate to the back surface 26B of the rotating plate 26. That is, in this embodiment, the first, second and third back surface projections 41, 42 and 43 are integrally formed.

On the other hand, the surface protrusion group 30 is formed, for example, from the same material and through the same process as the first and second coils 28B and 28D of the driving source 28. For example, the surface protrusion group 30 is made of copper plating.

Therefore, for example, the width W1 and height H1 of the front projection group 30 (e.g., the first front projection 31) are less than half the width W2 and height H2 of the back projection group 40 (e.g., the first back projection 41). Also, in this embodiment, the width W1 and height H1 of the front projection group 30 are smaller than the thickness T1 of the rotating plate 26.

For example, the width W1 and height H1 of the first front projection 31 are approximately 20 μm. On the other hand, the width W2 and height H2 of the first rear projection 41 are approximately 40 μm and 140 μm, respectively. The thickness T1 of the pivot plate 26 is approximately 40 μm.

Figure 6 is a diagram showing a schematic configuration of a system for measuring the emission range of secondary light L2. In this embodiment, a screen SC with a small hole is prepared, a light source 11 is positioned so that primary light L1 passes through this hole, and a rotating element 12 is positioned on the opposite side of the screen SC from the light source 11.

Then, the rotating element 12 was driven to rotate the rotating plate 26 periodically, and the light source 11 was driven to emit the primary light L1. Then, the angle range SA around the rotation axis AY where the secondary light L2 on the screen SC was stably emitted (hereinafter referred to as the stable rotation angle) was measured. Specifically, the rotation angle of the rotating plate 26 was gradually increased, and the rotation angle of the rotating plate 26 where the variation in the irradiation width in the x direction of the secondary light irradiated to the screen SC was less than a predetermined value was determined as the stable rotation angle SA.

Figure 7 shows the measurement results. Figure 7 shows the stable rotation angle SA for the scanning device 10 of this embodiment, which includes the rotating element 12, and the scanning device 100 of a comparative example, which includes a rotating element 101 that has a similar configuration to the rotating element 12, except that the rotating plate 26 does not have a surface protrusion group 30. Figure 7 also shows the measurement results of the change in the stable rotation angle SA when the ambient temperature of the rotating elements 12 and 101 is changed.

First, as shown in FIG. 7, it can be seen that the stable rotation angle SA of the rotating element 12 exceeds the stable rotation angle SA of the rotating element 101 at all ambient temperatures. This is believed to be due to the fact that the surface protrusion group 30 is provided, which stabilizes the flow of gas in the atmosphere near the rotating plate 26 when the rotating plate 26 rotates.

More specifically, the rotating plate 26 pushes aside the surrounding gas every time it rotates. The faster the rotating speed of the rotating plate 26, the more likely it is that the flow of gas (air current) pushed aside by the rotating plate 26 will become turbulent. This is thought to be due to the generation of turbulence in the air current.

In particular, the larger the maximum rotation angle of the rotating plate 26, the faster it rotates. Therefore, the larger the rotation angle of the rotating plate 26, the more turbulent the airflow near the rotating plate 26 becomes. Therefore, the inventors of the present application thought that by stabilizing the flow of gas around the rotating plate 26, it would be possible to increase the stable rotation angle SA of the rotation angle.

For example, in this embodiment, the surface protrusion group 30 is disposed opposite each other across the rotation axis AX and has a symmetrical shape with respect to the rotation axis AX. This allows the gas pushed aside by the rotating plate 26 during rotation to move stably in the y direction (the direction along the rotation axis AY). In addition, the surface protrusion group 30 has a symmetrical shape with respect to the rotation axis AY, which provides a high control effect on this airflow.

The inventors of the present application believe, at least at the time of filing the present application, that this principle has enabled the surface protrusion group 30 to increase the stable rotation angle SA of the rotating plate 26.

Furthermore, as the ambient temperature decreases, the viscosity of the gas decreases, making the airflow more turbulent. Therefore, the lower the ambient temperature, the smaller the stable rotation angle SA. Even in this case, as shown in Figure 7, it can be seen that the surface protrusion group 30 has the effect of stabilizing the airflow regardless of the ambient temperature. Although not shown in Figure 7, it is estimated that the stable rotation angle SA will be larger at other ambient temperatures based on the above-mentioned principle.

Similarly, when the air pressure increases, the gas becomes more turbulent, just as when the ambient temperature decreases. Even in this case, it is believed that the effect of the surface protrusion group 30 can be obtained. Therefore, it is believed that the stable rotation angle SA will be large even when used in various environments. Therefore, the rotating element 12 can be used to configure a scanning device 10 that can stably emit secondary light L2 over a wide range.

In addition, in this embodiment, the rotating plate 26 is driven to rotate while resonating around the rotation axis AY. In this case, the rotating plate 26 rotates at high speed, causing significant disturbance to the airflow. Therefore, when the rotating plate 26 is resonated, the surface protrusion group 30 has a significant effect of suppressing disturbance to the airflow.

In addition, in this embodiment, a back surface protrusion group 40 is provided on the back surface 26B of the rotating plate 26. Of this back surface protrusion group 40, the first and second back surface protrusions 41 and 42 are considered to have the effect of suppressing turbulence of the airflow, similar to the front surface protrusion group 30. Furthermore, the third back surface protrusion 43 has the effect of suppressing deformation (e.g., wavy deformation) of the rotating plate 26 during rotation. Therefore, by providing the back surface protrusion group 40, the stable rotation angle SA is increased, and the emission direction of the secondary light L2 is stabilized by suppressing deformation of the light reflecting film 27.

The configuration of the surface protrusion group 30 is not limited to the above. For example, each of the first and second surface protrusions 31 and 32 may be formed intermittently. Figure 8 is a plan view showing the surface 26A of the rotating plate 26 of the rotating element 12A in the scanning device 10A according to the first modified example of this embodiment.

As shown in FIG. 8, the rotating element 12A of the scanning device 10A has a configuration similar to that of the rotating element 12, except that it has a surface protrusion group 30A consisting of first and second surface protrusions 31A and 32A that are intermittently formed.

In this modified example, the first surface protrusion 31A has a plurality of protrusions P11 and P12 arranged opposite and spaced apart from each other across the rotation axis AX. Similarly, the second surface protrusion 32A has a plurality of protrusions P21 and P22 arranged opposite and spaced apart from each other across the rotation axis AX.

Like the surface protrusion group 30, the first and second surface protrusions 31A and 32A may have multiple protrusions P11, P12, P21, and P22. Even in this case, the effect of stabilizing the airflow can be obtained.

In consideration of effectively stabilizing the airflow, it is preferable that protrusions, like the surface protrusion group 30, are provided in the part of the rotating plate 26 that has the largest amount of displacement and the largest displacement speed when the rotating plate 26 rotates, such as the part on the rotation axis AX, the part farthest from the rotation axis AY, or the outer edge part of the surface 26A of the rotating plate 26. That is, for example, as shown in FIG. 3, the first and second surface protrusions 31 and 32 are preferably formed in the area on the rotation axis AX of the rotating plate 26.

In the example shown in FIG. 8, each of the protrusions P11, P12, P21, and P22 in each of the first and second surface protrusions 31A and 32A is formed in a continuous line shape. However, each of the first and second surface protrusions 31A and 32A may include multiple columnar protrusions.

Furthermore, the surface protrusion group 30 may be provided on the surface 26A of the rotating plate 26. Figure 9 is a plan view showing the surface 26A of the rotating plate 26 of the rotating element 12B in the scanning device 10B according to the second modified example of this embodiment.

As shown in FIG. 9, the rotating element 12B of the scanning device 10B has a configuration similar to that of the rotating element 12, except that it has a surface protrusion group 30B consisting of first and second surface protrusions 31B and 32B formed on the outside of the light reflecting film 27.

In this modified example, the first and second surface protrusions 31B and 32B are each formed on a curve along the outer edge of the light reflecting film 27 on the surface 26A of the rotating plate 26. Even in this case, the effect of stabilizing the air flow can be obtained.

In addition, in order to ensure that the surface protrusion group 30B is securely fixed to the rotating plate 26, it is preferable that the surface protrusion group 30B is formed on the light reflecting film 27 as shown in this embodiment. This is because, when the surface protrusion group 30 is formed by metal plating as in this embodiment, even minute protrusions such as the surface protrusion group 30 can be sufficiently fixed to the rotating plate 26 by forming it on a light reflecting metal that serves as a light reflecting film that has a high affinity with the metal.

The protrusions for stabilizing the airflow may be provided on the rear surface 26B of the rotating plate 26. Figure 10 is a cross-sectional view of the rotating plate 26 of the rotating element 12C in the scanning device 10C according to the third modification of this embodiment.

As shown in FIG. 10, the rotating element 12C of the scanning device 10C has a configuration similar to that of the rotating element 12, except that no protrusions are provided on the front surface 26A of the rotating plate 26, and the configuration of the rear surface protrusion group 40A.

In this modified example, the rear projection group 40A has first and second rear projections 41A and 42A having the same configuration as the first and second front projections 31 and 32 in the front projection group 30. That is, each of the first and second rear projections 41A and 42A is provided on the rear surface 26B of the rotating plate 26, facing each other across the rotation axis AY and spaced apart from each other. Also, each of the first and second rear projections 41A and 42A is made of the same material as the front projection group 30, for example, copper plating.

As in this modified example, by providing a rear surface protrusion group 40A on the rear surface 26B of the rotating plate 26, it is possible to suppress turbulence of the air flow during rotation. In other words, the rotating element 12 may be provided with, for example, a front surface protrusion group 30 (first and second front surface protrusions 31 and 32) or a rear surface protrusion group 40A (first and second rear surface protrusions 41A and 42A).

In addition, if the rotating plate 26 has a characteristic of reflecting a part or all of the primary light L1, it is not necessary to provide a light reflecting film 27. Figure 11 is a cross-sectional view of the rotating plate 26 of the rotating element 12D in the scanning device 10D according to the fourth modification of this embodiment.

As shown in FIG. 11, the rotating element 12D of the scanning device 10D has a configuration similar to that of the rotating element 12, except that it does not have a light reflecting film 27 and has a rotating plate 26 whose surface 26A (plate surface) functions as the light reflecting surface 12S.

In this case, the light source 11 and the rotating element 12D need only be configured and arranged so that the primary light L1 is incident on the surface 26A of the rotating plate 26. Furthermore, the surface protrusion group 30 needs only to be provided on the surface 26A of the rotating plate 26. In other words, the rotating plate 26 needs only to have at least the surface 26A that includes an area having light reflectivity, and the back surface 26B opposite the surface 26A.

In the present embodiment, the rotating plate 26 is configured to rotate around the rotation axes AX and AY. However, the configuration of the rotating plate 26 is not limited to this. The rotating plate 26 only needs to be configured to rotate at least around the rotation axis AY. In this case, for example, the rotating frame 24 only needs to be fixed to the base 21 or the fixed frame 22, and function as a support that rotatably supports the rotating plate 26.

The rotating plate 26 is not limited to having a disk shape. The rotating plate 26 may have, for example, a rectangular or polygonal plate shape. The rotating plate 26 does not have to have a plate-like shape. The rotating plate 26 may have various shapes as long as it has at least a light reflecting surface 12S.

Therefore, for example, when the rotating element 12 is configured to rotate only around the rotation axis AY, it is sufficient that the rotating element 12 is configured as a light reflector having at least a rotating frame 24 as a support body and a rotating plate 26 as a rotating body that is supported by the support body and rotates around the rotation axis AY. A protrusion is provided on at least one of the front surface 26A and the back surface 26B of the rotating plate 26 as a rotating body. In this case, when the rotating plate 26 as a rotating body is configured to rotate while resonating around the rotation axis AY, the effect of providing a protrusion is great.

In addition, when the rotating plate 26 is rotated only around the rotation axis AY, for example, each of the first and second surface protrusions 31 and 32 may be formed on a straight line that passes through the center of at least one of the front surface 26A and the back surface 26B of the rotating plate 26 and is perpendicular to the rotation axis AY. In addition, for example, each of the first and second surface protrusions 31 and 32 may have a symmetrical shape with respect to a straight line that passes through the center of at least one of the front surface 26A and the back surface 26B of the rotating plate 26 and is perpendicular to the rotation axis AY.

In addition, in this embodiment, the surface protrusion group 30 is formed on a curved line. However, the surface protrusion group 30 is not limited to being formed on a curved line. For example, the surface protrusion group 30 may be formed in such a manner that it functions like a fin that controls the flow of gas pushed aside by the rotating plate 26. As a preferred arrangement example, for example, each of the first and second surface protrusions 31 and 32 may have at least one protrusion formed continuously along the outer edge of at least one of the front surface 26A and back surface 26B of the rotating plate 26.

In addition, in this embodiment, the rotating element 12 is mounted as a deflection element that deflects the primary light L1 in a variable direction within the scanning device 10 and emits it as secondary light L2 toward the scanning region R0. However, the rotating element 12 can be mounted in a device other than the scanning device 10. In other words, the rotating element 12 can function as a light reflector that deflects light in a variable direction for purposes other than scanning.

Thus, in this embodiment, the light reflector has a support (e.g., a rotating frame 24), a rotating body (e.g., a rotating plate 26) supported by the support so as to rotate around a rotation axis AY, having a first surface (e.g., a front surface 26A) including a light-reflective area and a second surface (e.g., a back surface 26B) opposite the first surface, and first and second protrusions (e.g., first and second front surface protrusions 31 and 32, or first and second back surface protrusions 41A and 42A) each provided on at least one of the first surface and the second surface of the rotating body and arranged spaced apart and facing each other across the rotation axis AY. Therefore, a light reflector having a stable rotation range can be provided.

12, 12A, 12B, 12C, 12D Rotating elements 30, 30A, 30B Front surface protrusion group 40, 40A Back surface protrusion group

Claims (18)

A support;
a rotating body supported by the support so as to rotate about a rotation axis, the rotating body having a first surface including a light-reflective area and a second surface opposite to the first surface;
first and second protrusions, each of which is provided on at least one of the first surface and the second surface of the rotating body, and which are disposed opposite to and spaced apart from each other across the rotation axis;
third and fourth protrusions, each of which is provided on the second surface of the rotating body, disposed opposite to and spaced apart from each other across the rotation axis, and provided at positions opposite to the first and second protrusions;
A light reflector, wherein the height of each of the first and second protrusions is smaller than the height of each of the third and fourth protrusions. 2. The light reflector according to claim 1 , wherein each of the first and second protrusions is provided on the first surface of the rotating body. 2. The light reflector according to claim 1 , wherein each of the first, second, third and fourth protrusions is integrally formed. 2. The light reflector according to claim 1 , wherein the first and second protrusions are disposed at positions symmetrical with respect to the rotation axis. a light reflecting film provided on the first surface of the rotating body;
The light reflector according to claim 1, further comprising a fifth protrusion portion provided in an area of the second surface of the rotating body facing the light reflecting film across the rotating body, the fifth protrusion portion having a shape symmetrical with respect to the rotation axis. 6. The light reflector according to claim 5 , wherein each of the first and second protrusions is formed on the light reflecting film. 6. The light reflector according to claim 5 , wherein the third, fourth and fifth protrusions are integrally formed. The light reflector according to claim 1 , wherein the rotating body is configured to rotate around the rotation axis while resonating. The light reflector according to claim 1 , wherein the rotating body has a disk shape. The support has a frame shape,
the rotating body is supported by the support body on the inner side of the support body by a torsion bar extending along the rotation axis,
2. The light reflector according to claim 1 , wherein the support body, the torsion bar, and the rotating body are integrally formed. 2. The light reflector according to claim 1, wherein each of the first and second protrusions includes a protrusion formed continuously along an outer edge of at least one of the first and second surfaces of the rotating body. The light reflector according to claim 1, characterized in that each of the first and second protrusions is formed on a straight line passing through the center of at least one of the first and second surfaces of the rotating body and perpendicular to the rotation axis . The light reflector according to claim 1, wherein each of the first and second protrusions has a symmetrical shape with respect to a straight line passing through the center of at least one of the first or second surfaces of the rotating body and perpendicular to the rotation axis . a movable frame having an inner periphery on which the rotating body and the support body for supporting the rotating body are provided;
a coil portion for obtaining a rotational force for rotating around a rotation axis disposed on the movable frame,
2. The light reflector according to claim 1 , wherein the first and second protrusions are formed from the same material as the coil portion. The light reflector according to claim 14 , wherein the first and second protrusions and the coil portion are formed in the same process. A support;
a rotating body supported by the support so as to rotate about a rotation axis, the rotating body having a first surface including a light-reflective area and a second surface opposite to the first surface;
a first protrusion and a second protrusion, each of which is provided on at least one of the first surface and the second surface of the rotating body and disposed opposite to each other and spaced apart from each other across the rotation axis;
each of the first and second protrusions includes a protrusion formed continuously along the shape of an outer edge of at least one of the first and second surfaces of the rotating body;
The light reflector is characterized in that the rotating body has a disk shape. A support;
a rotating body supported by the support so as to rotate about a rotation axis, the rotating body having a first surface including a light-reflective area;
a first protrusion and a second protrusion, each of which is provided on the first surface of the rotating body and disposed opposite to and spaced apart from each other across the rotation axis;
The light reflector is characterized in that the rotating body has a disk shape. A support;
a rotating body supported by the support so as to rotate about a rotation axis, the rotating body having a first surface including a light-reflective area and a second surface opposite to the first surface;
a first protrusion and a second protrusion, each of which is provided on at least one of the first surface and the second surface of the rotating body and is disposed at positions symmetrical with respect to the rotation axis;
each of the first and second protrusions includes a protrusion formed continuously along the shape of an outer edge of at least one of the first and second surfaces of the rotating body;
The light reflector is characterized in that the rotating body has a disk shape.

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