Patent Publication Number: US-11035544-B2

Title: Illumination device with laser element, rotating mirror member and wavelength converter

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2019-189161, filed on Oct. 16, 2019, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to an illumination device. 
     2. Description of Related Art 
     In recent years, development of an Adaptive Driving Beam (ADB) headlamps for vehicle headlamps to illuminate only the selected area has been in progress. With the ADB headlamps, for example, light can be projected only to a region in which oncoming vehicles or preceding vehicles do not exist. This allows the driver to have the field of view without obstructing operations of other vehicles. A device employing ADB is described in, for example, PCT Publication No. WO2017104167, which describes a device that includes a laser element, a polygon mirror, and a light-emitting portion containing a phosphor. 
     SUMMARY 
     Certain embodiments of the present invention have an object to provide an illumination device in which the scanning range of a laser beam can be expanded. 
     An illumination device according to one embodiment includes a laser element, a rotating member including a plurality of flat mirror regions that are disposed along a circumference direction of the rotating member to sequentially reflect laser beams emitted from the first laser element with rotation of the rotating member, and a wavelength conversion member. Each of the laser beams reflected at a corresponding one of the mirror regions is incident on the wavelength conversion member. When viewed in a direction in which a rotation axis of the rotating member extends, the mirror regions are disposed at mutually different angles with respect to respective ones of lines each connecting the rotation axis and the center of a respective one of the mirror regions. 
     Certain embodiments of the present invention can provide an illumination device in which the scanning range of a laser beam can be expanded. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view illustrating an illumination device according to a first embodiment. 
         FIG. 2  is a schematic side view illustrating a laser element and a rotating member of the illumination device according to the first embodiment. 
         FIG. 3  is a schematic view illustrating a layout of a plurality of mirror regions of the rotating members. 
         FIG. 4  schematically illustrates a lateral surface of the rotating member and a cross-section of a wavelength conversion member. 
         FIG. 5  is a schematic view illustrating an operation of the illumination device according to the first embodiment. 
         FIG. 6  is a schematic view illustrating an operation of the illumination device according to the first embodiment. 
         FIG. 7  is a schematic view illustrating an operation of the illumination device according to the first embodiment. 
         FIG. 8  is a schematic perspective view illustrating sections of the wavelength conversion member on each of which a corresponding one of laser beams is incident. 
         FIG. 9  is a graph illustrating control signals of the laser element from a controller of the illumination device according to the first embodiment. 
         FIG. 10  is a schematic view illustrating an operation of a headlight to which the illumination device according to the first embodiment is applied. 
         FIG. 11  is a schematic view illustrating an illumination device according to a second embodiment. 
         FIG. 12  is a schematic sectional view illustrating a wavelength conversion member of the illumination device according to the second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     An illumination device according to one embodiment includes a laser element, a rotating member having a plurality of flat mirror regions that are disposed along a circumferential direction of the rotating member to sequentially reflect laser beams emitted from the laser element with rotation of the rotating member, and a wavelength conversion member. The laser beams each of which is reflected at a corresponding one of the mirror regions is incident on the wavelength conversion member. When viewed from a direction in which a rotation axis of the rotating member extends, the mirror regions are disposed at mutually different angles with respect to respective ones of lines each connecting the rotation axis and the center of a respective one of the mirror regions. 
     Configurations of the illumination device according to certain embodiments will be described below. 
     First Embodiment 
     A first embodiment will be described. 
       FIG. 1  is a schematic view illustrating an illumination device according to the first embodiment. 
     The illumination device  1  includes at least one laser element  10 , a rotating member  20 , a wavelength conversion member  30 , an optical system  40 , and a controller  50 . 
     The rotating member  20  has a plurality of flat mirror regions A that are disposed along a circumferential direction of the rotating member. In the rotating member  20 , laser beams L 1  emitted from the laser element  10  are sequentially reflected at the plurality of mirror regions A with rotation of the rotating member. When viewed in a direction in which the rotation axis C of the rotating member  20  extends, the plurality of mirror regions A are disposed at mutually different angles θ with respect to respective ones of lines D each connecting the rotation axis C and the center B of a respective one of the mirror regions A. The laser beams L 1  reflected at the plurality of mirror regions A are incident on the wavelength conversion member  30 . Light L 2  emitted from the wavelength conversion member  30  is projected by the optical system  40 . The controller  50  controls operations of the laser element  10  and the rotating member  20 . 
     The structure will be described below in detail. Also, the direction in which the rotation axis C of the rotating member  20  extends may be hereinafter referred to as “an upper-lower direction”. 
       FIG. 2  is a schematic side view illustrating the laser element and the rotating member of the illumination device according to the first embodiment. 
     As shown in  FIG. 2 , in one example, the illumination device  1  includes four laser elements  10 . Other appropriate number of laser elements  10  may be employed. 
     Examples of each laser element  10  include a laser diode (LD). In one example, a laser beam L 1  emitted from each laser element  10  is a blue laser beam. The laser beam L 1  emitted from each laser element  10  may have a color other than blue. 
     The four laser elements  10  irradiate the laser beams L 1  to regions that are mutually different in the upper-lower direction of the rotating member  20  by. That is, a region on the rotating member  20  irradiated with a laser beam L 1  emitted from one of the laser elements  10  and a region on the rotating member  20  irradiated with a laser beam L 1  emitted from another one of the laser elements  10  are located at different locations in the upper-lower direction. 
     As shown in  FIG. 1 , each laser element  10  is spaced apart from the wavelength conversion member  30 . In an example shown in  FIG. 2 , the four laser elements  10  are disposed along the upper-lower direction. The four laser elements  10  are configured to emit laser beams L 1  in the same direction. Other arrangement of the four laser elements  10  may be employed as long as mutually different regions in the upper-lower direction of the rotating member  20  are irradiated with the laser beams L 1 . 
     For example, a collimating lens  11  is arranged at a light-emitting surface of each laser element  10 . The rotating member  20  is irradiated with the laser beam L 1  that has been collimated by the collimating lens  11 . 
     The illumination device  1  includes the rotating member  20 , a shaft  21  connected to the rotating member  20 , and a drive unit  22  configured to rotate the shaft  21 . When the shaft  21  is rotated by the drive unit  22 , the rotating member  20  rotates. The drive unit  22  include, for example, a motor and the like. 
       FIG. 3  is a schematic view illustrating a layout of the plurality of mirror regions of the rotating members. 
     The rotating member  20  has, for example, forty flat mirror regions A that are disposed along a circumference direction of the rotating member  20 . The forty mirror regions A that are disposed along the circumference direction are hereinafter referred to as “a mirror set S”. 
     As shown in  FIG. 2 , the rotating member  20  includes four mirror sets S that are disposed along the vertical direction. The rotating member  20  may include other number of mirror sets S. Further, other number of mirror regions A may constitute each mirror set S. The laser beam L 1  emitted from each of the laser elements  10  is incident on a corresponding one of the mirror sets S. 
     Each of the mirror regions A has, for example, a substantially rectangular shape. As shown in  FIG. 3 , in a top view, the centers B of respective mirror regions A in each mirror set S are, for example, located at substantially equal intervals along a circumference E about the rotation axis C. In a top view, the mirror regions A are disposed at mutually different angles θ with respect to respective ones of lines D each connecting the rotation axis C and the center B of a respective one of the 40 mirror regions A that constitute each of the mirror sets S. 
     In an example shown in  FIG. 3 , in each mirror set S, a mirror region A 1  that is one of the 40 mirror regions A is disposed at an angle θ 1  of, for example, 110 degrees, which is the maximum. The mirror region A 1  that is disposed at the maximum angle θ will be hereinafter referred to as “a first mirror region A 1 ”. Among the 40 mirror regions A, a mirror region that is located at i-th position when counted from the first mirror region A 1  in a counterclockwise direction R 1  in  FIG. 3  will be hereinafter referred to as “an i-th mirror region A i ” (i=2 to 40). An angle θ at which the i-th mirror region A i  is disposed will be hereinafter referred to as “an angle θ i ”. 
     The angle θ at which each mirror region A is disposed is decreased, for example, by one degree sequentially from the first mirror region A 1  in a counterclockwise direction R 1 . That is, the angle θ i  at which the i-th mirror region A i  is disposed is smaller by one degree with respect to the angle θ i-1  at which the (i−1)-th mirror region A i-1  is disposed. Accordingly, the angle θ 40  at which the 40th mirror region A 40  is disposed is, for example, 71 degrees, which is the minimum. The maximum value, the minimum value, and variations of the angle θ are not limited to the above. 
     For the four mirror sets S, for example, the distances between the rotation axis C and the centers B of the mirror regions A of the four mirror sets S are the same, and four mirror regions A at the same position along the circumferential direction are located at the same angle θ. With this configuration, the outputs of the laser elements  10  by the controller  50 , which will be described below, can be easily controlled. 
     As shown in  FIG. 2 , for example, in the four mirror sets S, the mirror regions A are disposed at the same angles with respect to the direction in which the rotation axis C extends. In an example shown in  FIG. 2 , in the four mirror sets S, all mirror regions A are disposed at the angle of 0 degree with respect to the direction in which the rotation axis C extends, that is, disposed parallel to the rotation axis C. Alternatively, mirror regions A in different mirror sets S may be disposed at mutually different angles with respect to the direction in which the rotation axis C extends. This allows the vertical length of the wavelength conversion member  30  to be determined irrespective of the rotating member  20 . 
     The rotating member  20  may, for example, be integrally formed of a metal. The rotating member  20  may have a structure in which, for example, a main body made of a resin material and having a plurality of flat areas disposed along the circumferential direction is provided with a mirror layer made of a metal. Also, in the rotating member  20 , a plurality of sheet-like mirrors made of a metal may be disposed on a lateral surface of the main body. 
     A single mirror set S may be included in the rotating member  20 . In this case, each mirror region A may have a shape elongated in the upper-lower direction, and regions at mutually different positions in the upper-lower direction of each of the mirror regions A may be irradiated with laser beams L 1  from the laser elements  10 . 
       FIG. 4  schematically illustrates a lateral surface of the rotating member and a cross-section of a wavelength conversion member. 
     The wavelength conversion member  30  is, for example, a transmissive wavelength conversion member that transmits a portion of the incident laser beam L 1 . The wavelength conversion member  30  includes, for example, a light-transmissive member  31  and a wavelength conversion substance  32  dispersed in the light-transmissive member  31 . 
     The light-transmissive member  31  has, for example, a substantially rectangular parallelepiped shape. Examples of materials for the light-transmissive member  31  include organic materials such as light-transmissive resins and inorganic materials such as light-transmissive glasses. The light-transmissive member  31  is preferably made of inorganic materials in view of heat resistance. The light-transmissive member  31  is disposed on optical paths of the laser beams L 1  each of which is reflected at a corresponding one of the mirror regions A. The laser beam L 1  reflected at the rotating member  20  is incident on the light-transmissive member  31 . The light-transmissive member  31  transmits a portion of the incident laser beam L 1 . At this time, the laser beam L 1  is diffused in the wavelength conversion member  30  by the wavelength conversion substance  32  and the like in the light-transmissive member  31 . 
     As shown in  FIG. 1 , the light-transmissive member  31  extends in a direction intersecting the optical axes of the laser beams L 1  each of which is reflected at a corresponding one of the mirror regions A. The direction in which the light-transmissive member  31  extends may be hereinafter referred to as “a lateral direction a 1 ”. The light-transmissive member  31  has a first end portion  31   a  near the laser element  10  and a second end portion  31   b  opposite to the first end portion  31   a  in the lateral direction a 1 . 
     As shown in  FIG. 4 , the wavelength conversion substance  32  is dispersed in the light-transmissive member  31 . Examples of the wavelength conversion substance  32  include a phosphor that absorbs a portion of the laser beam L 1  reflected at the rotating member  20  and emits yellow light. The wavelength conversion substance  32  may not be phosphors. Also, the wavelength conversion substance  32  may be configured to emit a color other than yellow. 
     The blue light of the laser beam L 1  that is diffused in the wavelength conversion member  30  and transmits the light-transmissive member  31  is mixed with yellow light emitted from the wavelength conversion substance  32 . This allows the wavelength conversion member  30  to emit, for example, white light L 2 . 
     The white light L 2  emitted from the wavelength conversion member  30  is projected by the optical system  40 . The light emitted from the optical system  40  is hereinafter referred to as “light L 3 ”. The optical system  40  is, for example, a combination of one or more convex lenses and one or more concave lenses (not shown). In  FIG. 1 , illustration of the optical system  40  is simplified. 
     Examples of the controller  50  include an electronic control unit (ECU) that includes control circuits each for a respective one of the laser elements  10 , a control circuit for the drive unit  22 , a central processing unit (CPU), memories, and the like. The controller  50  individually controls the outputs of the laser elements  10  each for a time period Δt during which each of the mirror regions A is located on the optical axis of a corresponding one of the laser beams L 1 . “Controlling the outputs” includes the state in which the laser elements  10  are totally turned off. 
       FIGS. 5 through 7  are schematic diagrams each illustrating operations of the illumination device according to the present embodiment. 
       FIG. 8  is a schematic perspective view illustrating regions of the wavelength conversion member on each of which a corresponding one of the laser beams is incident. 
     Next, the operation of the illumination device  1  according to the present embodiment will be described. 
     Specifically, an example of the rotating member  20  rotated in a clockwise direction a 2  shown in  FIGS. 5 through 7  will be described below. The rotating member  20  may be rotated in other directions. 
       FIG. 5  illustrates a state in which the center B of the first mirror region A 1  of each of the mirror sets S is located on the optical axis of a corresponding one of the laser beams L 1 . In this state, when the laser beam L 1  is emitted from a corresponding laser element  10 , the emitted laser beam L 1  is reflected at the first mirror region A 1  at an angle of reflection θR 1 . 
     As shown in  FIG. 8 , the laser beam L 1  reflected at the first mirror region A 1  of an uppermost mirror set S of the mirror sets S is incident on a portion P 1   1  near the first end portion  31   a  of the wavelength conversion member  30 . A laser beam L 1  reflected at the first mirror region A 1  of a second uppermost mirror set S of the mirror sets S is incident on a portion P 2   1  near the first end portion  31   a  of the wavelength conversion member  30  below the portion P 1   1 . A laser beam L 1  reflected at the first mirror region A 1  of a third uppermost mirror set S of the mirror sets S is incident on a portion P 3   1  near the first end portion  31   a  of the wavelength conversion member  30  below the portion P 2   1 . The laser beam L 1 , which is reflected at the first mirror region A 1  of a fourth mirror set S from the top, is incident on a portion P 4   1  near the first end portion  31   a  of the wavelength conversion member  30  below the portion P 3   1 . That is, the four portions P 1   1 , P 2   1 , P 3   1 , and P 4   1  are aligned in the upper-lower direction. 
     Each of the portions P 1   1 , P 2   1 , P 3   1 , and P 4   1  will be hereinafter referred to as “the first portion Pj 1 ” (j=1 to 4). With incidence of the laser beam L 1 , the light L 2  is mainly emitted from the first portion Pj 1  of the wavelength conversion member  30 . 
     In the same manner, an angle of reflection at the i-th mirror region A i  of each mirror set S will be referred to as “the angle of reflection θR i ”, and a portion of the wavelength conversion member  30  on which the laser beam L 1  reflected at the i-th mirror region A i  of a j-th uppermost mirror set S of the mirror sets S is incident will be referred to as “the i-th portion Pj i ”. 
       FIG. 6  illustrates a state in which the rotating member  20  has been rotated in the clockwise direction a 2  from the state of  FIG. 5  and the center B of the second mirror region A 2  of each of the mirror sets S is located on the optical axis of a corresponding one of the laser beams L 1 . In this state, when the laser beam L 1  is emitted from the laser element  10 , the emitted laser beam L 1  is reflected at the second mirror region A 2  at an angle of reflection θR 2 . The angle θ 2  at which the second mirror region A 2  is disposed is smaller than the angle θ 1  at which the first mirror region A 1  is disposed. This allows the angle of reflection θR 2  of the laser beam L 1  at the center B of the second mirror region A 2  to be larger than the angle of reflection θR 1  of the laser beam L 1  at the center B of the first mirror region A 1 . 
     Accordingly, the laser beam L 1  reflected at the second mirror region A 2  of each mirror set S is incident on the second portion Pj 2  at a second end portion  31   b  side with respect to the first portion Pj 1 . With this configuration, the light L 2  is mainly emitted from the second portion Pj 2  of the wavelength conversion member  30 . The first portion Pj 1  and the second portion Pj 2  may partially overlap each other. 
       FIG. 7  illustrates a state in which the rotating member  20  has further been rotated in the clockwise direction a 2  from the state of  FIG. 6  and the center B of the 40th mirror region A 40  of each of the mirror sets S is located on the optical axis of a corresponding one of the laser beams L 1 . In this state, when the laser beam L 1  is emitted from the laser element  10 , the emitted laser beam L 1  is reflected at the 40th second mirror region A 40 . 
     The angle θ 40  at which the 40th mirror region A 40  is disposed is smaller than each of the angles θ 1  to θ 39  at which the first to the 39th mirror regions A 1  to A 39  are disposed, respectively. This allows the angle of reflection θR 40  of the laser beam L 1  at the center B of the 40th mirror region A 40  to be larger than each of the angles of reflection θR 1  to θR 39  of the laser beams L 1  at the centers B of the first to the 39th mirror regions A 1  to A 39 , respectively. Accordingly, the laser beam L 1  reflected at the 40th mirror region A 40  is incident on a 40th portion Pj 40  that is closer to the second end portion  31   b  than the 39th portion Pj 39  in the wavelength conversion member  30 . The 40th portion Pj 40  is, for example, located near the second end portion  31   b . With this configuration, the light L 2  is mainly emitted from the 40th portion Pj 40  of the wavelength conversion member  30 . 
     Accordingly, as shown in  FIG. 8 , each of the mirror sets S can reflect the laser beams L 1  toward a corresponding one of the portions P 1   i  to P 4   i  that are mutually different in the vertical direction of the wavelength conversion member  30 . Each of the 40 mirror regions A of each mirror set S can reflect the laser beams L 1  toward a corresponding one of the portions Pj 1  to Pj 40  that are mutually different in the lateral direction a 1  of the wavelength conversion member  30 . The light L 2  emitted from each of the portions P 1   1  to P 1   40 , P 2   1  to P 2   40 , P 3   1  to P 3   40 , and P 4   1  to P 4   40  of the wavelength conversion member  30  is projected by the optical system  40 . That is, the light L 2  that is emitted from each of the portions P 1   1  to P 1   40 , P 2   1  to P 2   40 , P 3   1  to P 3   40 , and P 4   1  to P 4   40  of the wavelength conversion member  30  and that is incident on the optical system  40  is projected in mutually different directions by the optical system  40 . This configuration allows the illumination device  1  to distribute the light L 3  in the upper-lower direction and in the lateral direction a 1 . 
     The description above shows an example in which the angles θ at which the plurality of mirror regions A constituting each mirror set S are disposed are varied along the circumference direction by predetermined degrees (for example, by one degree). In this case, as described above, when the rotating member  20  is rotated to change the mirror region A irradiated with the laser beam L 1 , a portion of the wavelength conversion member  30  irradiated with the laser beam L 1  is shifted sequentially in the lateral direction a 1 . Alternatively, the plurality of mirror regions A that constitutes each mirror set S may be arranged at mutually different angles θ without regularity along the circumference direction. In this case, when the rotating member  20  is rotated to change the mirror region A irradiated with the laser beam L 1 , a portion of the wavelength conversion member  30  irradiated with the laser beam L 1  is shifted irregularly in the lateral direction a 1 . 
       FIG. 9  is a graph illustrating control signals of the laser element from the controller of the illumination device according to the present embodiment. 
     The controller  50 , for example, individually controls the outputs of the laser elements  10 . The controller  50 , for example, individually adjusts the number of pulses of the input current to each of the laser elements  10  for a time period Δt during which each of the mirror regions A is located on the optical axis of a corresponding one of the laser beams L 1 . The larger the number of pulses to be input for a time period Δt, the longer the total light-emitting time of the laser element  10  for the time period Δt. The longer the total light-emitting time of the laser element  10  for a time period Δt, the higher the luminous intensity of the light L 2  emitted from the wavelength conversion member  30  during the time period Δt. The laser element  10  can be turned off during a time period Δt by setting the number of pulses of the input current for the time period Δt to zero. This allows for individually selecting portions of the wavelength conversion member  30  to emit the light L 2 . Further, in the case in which the illumination device  1  emits the light L 2 , the luminous intensity of the emitted light L 2  can be adjusted. 
       FIG. 10  is a schematic view illustrating an operation of a headlight to which the illumination device according to the present embodiment is applied. 
     Examples of applications of the illumination device  1  include a high-beam unit of a headlight mounted in a vehicle. 
     As described above, the outputs of the four laser elements  10  are individually controlled and each of the mutually different areas in the vertical direction of the rotating member  20  are irradiated with the laser beams L 1  from a corresponding one of the four laser elements  10 . Hence, as shown in  FIG. 10 , a high beam area RH can be divided into the four columns in the vertical direction. Further, the high beam area RH can be divided, for example, into 40 rows in the lateral direction a 1  according to a time period Δt during which each of the mirror regions A of the mirror set S is located on the optical axis of a corresponding one of the laser beams L 1 . Accordingly, the high beam area RH can be divided into four columns in the vertical direction and 40 rows in the lateral direction, that is, 160 small areas RHa in total. It is noted that each of the small areas RHa corresponding to time periods Δt may partially overlap with other adjacent small areas RHa in the lateral direction a 1 . 
     A sensor mounted in a vehicle (not shown) detects a preceding vehicle  81 , an oncoming vehicle  82 , a sign  83 , and pedestrians  84  and  85  in the high beam area RH. Based on the signal detected by the sensor, the controller  50  adjusts the number of pulses to be input to the laser element  10  for each time period corresponding to the small area RHa. 
     With this configuration, for example, the illumination device  1  projects light onto an area out of the high beam area RH except for a rear windshield of the preceding vehicle  81 . Also, for example, the illumination device  1  projects light onto an area out of the high beam area RH except for a windshield of the oncoming vehicle  82 . For example, the illumination device  1  projects light with reduced intensity onto the sign  83 . This can reduce reflection glare. For example, the illumination device  1  projects light with high intensity onto body portions of the pedestrians  84  and  85  except for their heads. This can emphasize presence of the pedestrians  84  and  85 . Accordingly, visibility of a driver of the vehicle can be increased without dazzling a driver of the preceding vehicle  81 , a driver of the oncoming vehicle  82 , and the pedestrians  84  and  85 . 
     Next, the effects that can be obtained in the present embodiment will be described below. 
     The illumination device  1  according to the present embodiment includes a laser element  10 , a rotating member  20 , and a wavelength conversion member  30 . The rotating member  20  has the plurality of flat mirror regions A that are disposed along a circumference direction of the rotating member to sequentially reflect laser beams L 1  emitted from the laser element  10  with rotation of the rotating member. The laser beams L 1  reflected at the plurality of mirror regions A are incident on the wavelength conversion member  30 . When viewed in a direction in which the rotation axis C of the rotating member  20  extends, the plurality of mirror regions A are disposed at mutually different angles θ with respect to a line D extending from the rotation axis C to the center B of each of the mirror regions A. This allows the plurality of mirror regions A disposed along the circumference direction to reflect the laser beams L 1  toward mutually different sections of the wavelength conversion member  30 . With this arrangement, the illumination device  1  is obtained in which the scanning range of the laser beam can be expanded compared with an illumination device in which a plurality of mirror regions are disposed at the same angle. Accordingly, the illumination device  1  can project light onto a larger area. Alternatively, while keeping the projection area to be the same size as the conventional projection area, the illumination device  1  can be smaller in size by using a compact light source that densifies the laser beam. 
     An area on the rotating member  20  irradiated with a laser beam L 1  emitted from one of the laser elements  10  is different from an area on the rotating member  20  irradiated with a laser beam L 1  emitted from another one of the laser elements  10  in a direction in which the rotation axis C extends. This configuration allows the illumination device  1  to distribute the light L 2  in the direction in which the rotation axis C extends. 
     Each laser element  10  and the wavelength conversion member  30  are spaced apart from each other. Accordingly, the wavelength conversion member  30  has a good heat dissipation. 
     The wavelength conversion member  30  is a transmissive wavelength conversion member. With the transmissive wavelength conversion member  30 , the illumination device  1  with a reduced length in the direction in which the rotation axis C extends can be obtained. Accordingly, even when a space for the illumination device  1  is reduced in the direction in which the rotation axis C extends, the illumination device  1  can be disposed therein. 
     The illumination device  1  further includes an optical system  40  that projects light L 2  emitted from the wavelength conversion member  30 . The light L 2  that is emitted from each of the portions P 1   1  to P 1   40 , P 2   1  to P 2   40 , P 3   1  to P 3   40 , and P 4   1  to P 4   40  of the wavelength conversion member  30  and that is incident on the optical system  40  is projected by the optical system  40  toward mutually different directions. This configuration allows the illumination device  1  to distribute the light L 3  vertically and in the lateral direction a 1 . 
     The illumination device  1  further includes the controller  50  that controls operations of the laser elements  10  and the rotating member  20 . The controller  50  controls outputs of the laser elements  10  each for a time period Δt during which each of the mirror regions A is located on the optical axis of a corresponding one of the laser beams L 1 . Accordingly, the illumination device  1  can project light onto a selected area. 
     Second Embodiment 
     Next, a second embodiment will be described. 
       FIG. 11  is a schematic view illustrating an illumination device according to the second embodiment. 
     The illumination device  100  according to the second embodiment differs from the illumination device  1  according to the first embodiment in that a wavelength conversion member  130  is reflective. Only differences from the first embodiment will be mainly described below. Except for configurations in the descriptions below, the second embodiment has the same configurations as in the first embodiment. 
     Each of the laser elements  10  is, for example, disposed such that the laser beam L 1  is incident on a respective one of the mirror sets S of the rotating member  20  from below the respective mirror sets S. Each mirror set S of the rotating member  20 , for example, reflects a respective one of the laser beams L 1  upward. 
       FIG. 12  is a schematic sectional view illustrating the wavelength conversion member according to the second embodiment. 
     The wavelength conversion member  130  is, for example, a reflective wavelength conversion member that reflects a portion of the incident laser beams L 1 . The wavelength conversion member  130  includes, for example, a wavelength conversion layer  131  and a reflective layer  132  that reflects light emitted from the wavelength conversion layer  131 . 
     The wavelength conversion layer  131  includes, for example, a light-transmissive layer  131   a  and a wavelength conversion substance  131   b  in the light-transmissive layer  131   a.    
     Examples of materials for the light-transmissive layer  131   a  include organic materials such as light-transmissive resins and inorganic materials such as light-transmissive glasses. The light-transmissive member  31  is preferably made of inorganic materials in view of heat resistance. The laser beams L 1  reflected at the rotating member  20  are incident on the light-transmissive layer  131   a . The light-transmissive layer  131   a  transmits a portion of the incident laser beams L 1 . At this time, the laser beams L 1  are diffused in the wavelength conversion layer  131   a  by the wavelength conversion substance  131   b  and the like in the light-transmissive layer  131 . 
     The wavelength conversion substance  131   b  is dispersed in the light-transmissive layer  131   a . Examples of the wavelength conversion substance  131   b  include a phosphor that absorbs a portion of the laser beams L 1  reflected at the rotating member  20  and emits yellow light. 
     Examples of materials for the reflective layer  132  include ceramics and metal plates with high reflectance. In one example, the reflective layer  132  reflects the blue laser beam L 1  that is diffused in the wavelength conversion layer  131  and transmitted through the light-transmissive layer  131   a , and the yellow light that is emitted from the wavelength conversion substance  131   b . This allows the wavelength conversion member  130  to emit white light L 2 . The white light L 2  emitted from the wavelength conversion member  130  is projected by the optical system  40 . 
     Next, the effects that can be obtained in the second embodiment will be described below. 
     The illumination device  100  according to the second embodiment includes the wavelength conversion member  130  that is a reflective wavelength conversion member Compared with the transmissive wavelength conversion member  30 , the reflective wavelength conversion member  130  has a high heat dissipation and allows for efficiently extracting the light L 2 . With the reflective wavelength conversion member  130 , the illumination device  100  with a reduced length in the direction intersecting the direction in which the rotation axis C extends can be obtained. Accordingly, even when a space for the illumination device  100  is reduced in the direction intersecting the direction in which the rotation axis C extends, the illumination device  100  can be disposed therein. 
     Examples of application of the present invention include illumination devices such as headlights, spotlights, and lightings for projection mapping. 
     It is to be understood that although certain embodiments of the present invention have been described, various other embodiments and variants may occur to those skilled in the art that are within the scope and spirit of the invention, and such other embodiments and variants are intended to be covered by the following claims.