Patent Publication Number: US-2022236458-A1

Title: Optical unit

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to an optical unit and an optical unit used in a vehicle lamp. 
     2. Description of the Related Art 
     An optical unit provided with a lens in which a light output from a light source is incident from behind and which outputs the light in front of a vehicle as an irradiating beam and configured to form a predetermined light distribution pattern by scanning an area in front of the vehicle with a transmitted light transmitted through the lens is proposed in the related art. 
     Patent document 1: JP2012-256494 
     The lens provided in the above-mentioned optical unit is a transparent disc-shaped member, and the rotation axis of the lens is parallel to the light axis. This requires that the motor for driving the lens be provided behind the lens and requires a space in the longitudinal direction. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the above-described issue and an illustrative purpose thereof is to provide a novel optical unit for scanning with a light of a light source. 
     An optical unit according to an embodiment of the present invention includes: a cylindrical rotatable lens; and a light source provided in the rotatable lens. The rotatable lens is configured such that a light output from the light source is incident via an inner circumferential surface and is output via an outer circumferential surface as an irradiating beam, and a predetermined irradiated area is formed by scanning a space in front with the irradiating beam according to a periodical movement of the rotatable lens. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will now be described, by way of example only, with reference to the accompanying drawings which are meant to be exemplary, not limiting, and wherein like elements are numbered alike in several Figures, in which: 
         FIG. 1  is a schematic side view of the vehicle headlamp according to the first embodiment; 
         FIG. 2  is a schematic top view of the vehicle headlamp according to the first embodiment; 
         FIG. 3A  is an A-A cross-sectional view of the rotatable lens shown in  FIG. 1 ; 
         FIG. 3B  is a B-B cross-sectional view of the rotatable lens shown in  FIG. 1 : 
         FIG. 3C  is a C-C cross-sectional view of the rotatable lens shown in  FIG. 1 ; 
         FIG. 3D  is a D-D cross-sectional view of the rotatable lens shown in  FIG. 1 ; 
         FIG. 3E  is a E-E cross-sectional view of the rotatable lens shown in  FIG. 1 ; 
         FIG. 3F  shows a projected image formed by the irradiating beam transmitted through the cross-sectional shape shown in  FIG. 3A ; 
         FIG. 3G  shows a projected image formed by the irradiating beam transmitted through the cross-sectional shape shown in  FIG. 3B ; 
         FIG. 3H  shows a projected image formed by the irradiating beam transmitted through the cross-sectional shape shown in  FIG. 3C ; 
         FIG. 3I  shows a projected image formed by the irradiating beam transmitted through the cross-sectional shape shown in  FIG. 3D ; 
         FIG. 3J  shows a projected image formed by the irradiating beam transmitted through the cross-sectional shape shown in  FIG. 3E ; 
         FIG. 4  is a schematic side view of the vehicle headlamp according to the second embodiment; 
         FIG. 5A  shows area A′ of the rotatable lens shown in  FIG. 4 ; 
         FIG. 5B  shows area B′ of the rotatable lens shown in  FIG. 4 ; 
         FIG. 5C  shows area C′ of the rotatable lens shown in  FIG. 4 ; 
         FIG. 5D  shows area D′ of the rotatable lens shown in  FIG. 4 ; 
         FIG. 5E  shows area E′ of the rotatable lens shown in  FIG. 4 ; 
         FIG. 5F  shows a projected image formed by the irradiating beam transmitted through area A′ shown in  FIG. 5A ; 
         FIG. 5G  shows a projected image formed by the irradiating beam transmitted through area B′ shown in  FIG. 5B ; 
         FIG. 5H  shows a projected image formed by the irradiating beam transmitted through area C′ shown in  FIG. 5C ; 
         FIG. 5I  shows a projected image formed by the irradiating beam transmitted through area D′ shown in  FIG. 5D ; and 
         FIG. 5J  shows a projected image formed by the irradiating beam transmitted through area E′ shown in  FIG. 5E . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An optical unit according to an embodiment of the present invention includes: a cylindrical rotatable lens; and a light source provided in the rotatable lens. The rotatable lens is configured such that a light output from the light source is incident via an inner circumferential surface and is output via an outer circumferential surface as an irradiating beam, and a predetermined irradiated area is formed by scanning a space in front with the irradiating beam according to a periodical movement of the rotatable lens. 
     According to this embodiment, the predetermined irradiated area can be formed by scanning the space in front with the irradiating beam according to the periodical movement of the cylindrical rotatable lens. As compared with the case of forming a predetermined irradiated area directly with the light output from the light source, the size of the light source can be reduced. 
     The rotatable lens may be configured to be rotated around a rotary shaft coupled to a driving unit such that a direction of refraction of a light output from the light source and transmitted through the rotatable lens varies periodically. In this manner, scanning by using the light of the light source can be realized by a simple configuration. 
     The light source may be arranged such that a frontal direction of an output surface intersects the rotary shaft. This causes the output surface of the light source to face the inner circumferential surface of the rotatable lens. 
     The rotatable lens may be arranged such that the rotary shaft is aligned with a direction of vehicle width of the vehicle. This reduces the space of the optical unit in the vehicle longitudinal direction. 
     The light source may be configured such that an intensity of light varies in a certain phase range in a period of movement of the rotatable lens. This can change the brightness in a portion of the predetermined irradiated area. 
     Optional combinations of the aforementioned constituting elements, and implementations of the invention in the form of methods, apparatuses, and systems may also be practiced as additional modes of the present invention. 
     Hereinafter, the invention will be described based on preferred embodiments with reference to the accompanying drawings. Identical or like constituting elements, members, processes shown in the drawings are represented by identical symbols and a duplicate description will be omitted as appropriate. The embodiments of the present invention are not limited to those described and appropriate combinations or replacements of the features of the embodiment are also encompassed by the present invention. 
     First Embodiment 
     The optical unit according to the embodiment can be used in various vehicle lamps. First, a description will be given of an outline of a vehicle headlamp in which the optical unit according to the embodiment described below can be mounted. 
       FIG. 1  is a schematic side view of the vehicle headlamp according to the first embodiment.  FIG. 2  is a schematic top view of the vehicle headlamp according to the first embodiment. 
     A vehicle headlamp  10  includes an optical unit  12  and a projection lens  14  that projects a light source image output from the optical unit  12  in front of the vehicle. The optical unit  12  includes a cylindrical rotatable lens  16 , a semiconductor light-emitting element  18  as a light source provided in the rotatable lens  16 , a motor  20  provided to the side of the rotatable lens  16  and driving the rotatable lens  16  into rotation, and a control unit  22  that controls the lighting and extinguishing of the semiconductor light-emitting element  18  and the driving of the motor  20 . 
     For example, a light emitting diode (LED), a laser diode (LD), or an organic light emitting diode (OLED) is preferable as the semiconductor light-emitting element  18 . Further, the light source may be other than a semiconductor light-emitting element so long as it is small enough to be accommodated in the rotatable lens  16 . 
     A transmitting area of the rotatable lens  16  is formed by a transparent material such as glass and plastic. The rotatable lens  16  is configured such that the light output from the semiconductor light-emitting element  18  is incident via an inner circumferential surface  16   a  of the transmitting area and is output via an outer circumferential surface  16   b  of the transmitting area as an irradiating beam. Further, the rotatable lens  16  is driven by the motor  20  and is configured to form a predetermined irradiated area by scanning the space in front with the irradiating beam horizontally according to a periodic movement (rotational movement) around a rotary shaft R. More specifically, the configuration is realized by appropriately devising the surface shape of the inner circumferential surface  16   a  and the outer circumferential surface  16   b.    
       FIG. 3A  is an A-A cross-sectional view of the rotatable lens shown in  FIG. 1 ,  FIG. 3B  is a B-B cross-sectional view of the rotatable lens shown in  FIG. 1 ,  FIG. 3C  is a C-C cross-sectional view of the rotatable lens shown in  FIG. 1 ,  FIG. 3D  is a D-D cross-sectional view of the rotatable lens shown in  FIG. 1 ,  FIG. 3E  is a E-E cross-sectional view of the rotatable lens shown in  FIG. 1 ,  FIG. 3F  shows a projected image formed by the irradiating beam transmitted through the cross-sectional shape shown in  FIG. 3A ,  FIG. 3G  shows a projected image formed by the irradiating beam transmitted through the cross-sectional shape shown in  FIG. 3B ,  FIG. 3H  shows a projected image formed by the irradiating beam transmitted through the cross-sectional shape shown in  FIG. 3C ,  FIG. 3I  shows a projected image formed by the irradiating beam transmitted through the cross-sectional shape shown in  FIG. 3D , and  FIG. 3J  shows a projected image formed by the irradiating beam transmitted through the cross-sectional shape shown in  FIG. 3E . 
     The A-A cross section is positioned at the angle of rotation of the rotatable lens  16  of 0 degrees, the B-B cross section is positioned at the angle of rotation of the rotatable lens  16  of 72 degrees, the C-C cross section is positioned at the angle of rotation of the rotatable lens  16  of 144 degrees, the D-D cross section is positioned at the angle of rotation of the rotatable lens  16  of 216 degrees, and the E-E cross section is positioned at the angle of rotation of the rotatable lens  16  of 288 degrees. 
     As shown in  FIGS. 3F-3J , a projected image I moves gradually in the right direction of the figure. Thus, the vehicle headlamp  10  can form a predetermined irradiated area (a high beam light distribution pattern PH) by scanning the space in front with the irradiating beam according to the periodical movement of the cylindrical rotatable lens  16 . As compared with the case of forming a predetermined irradiated area (the projected image I) directly with the light output from the semiconductor light-emitting element  18 , therefore, scanning with the irradiating beam can form a high beam light distribution pattern PH wider than the projected image I. Therefore, the size of or the number of semiconductor light-emitting element(s)  18  can be reduced. 
     Further, the rotatable lens  16  is configured to be rotated around the rotary shaft R coupled to the motor  20  such that the direction of refraction of the light output from the semiconductor light-emitting element  18  and transmitted through the rotatable lens  16  varies periodically as shown in  FIGS. 3A-3E . In this manner, scanning by using the light of the semiconductor light-emitting element  18  can be realized by a simple configuration such as appropriately devising the shape of the outer circumferential surface  16   b  of the rotatable lens  16 . 
     Further, the semiconductor light-emitting element  18  according to the embodiment is arranged such that the frontal direction F of an output surface  18   a  (see  FIG. 2 ) intersects (is substantially orthogonal to) the rotary shaft R. This causes the output surface  18   a  of the semiconductor light-emitting element  18  to face the inner circumferential surface  16   a  of the rotatable lens  16  in parallel. 
     Further, the rotatable lens  16  according to the embodiment is arranged such that the rotary shaft R is aligned with the direction of vehicle width Y of the vehicle. This reduces the space of the optical unit  12  in the vehicle longitudinal direction X. 
     The semiconductor light-emitting element  18  may be controlled by the control unit  22  such that the intensity of light varies in a certain phase range in the period of movement of the rotatable lens  16 . This can change the brightness in a portion of the predetermined irradiated area. For example, a portion of the high beam light distribution pattern PH can be placed in a non-irradiated state by substantially extinguishing the semiconductor light-emitting element  18  by the control unit  22  at a point of time when the projected image I passes the position of  FIG. 3F  and lighting the semiconductor light-emitting element  18  at the other points of time. 
     Thus, the optical unit  12  according to this embodiment functions as a novel optical unit not found in the related art that scans the direction of light irradiation (front) with the transmitted light output from the light, by appropriately devising the surface shape of the rotatable lens  16 . 
     Variation to the First Embodiment 
     In the optical unit  12  described above, one rotation of the rotatable lens  16  around the rotary shaft R causes the space in front scanned once by the projected image I from left to right. By appropriately devising the surface shape of the rotatable lens  16 , it can also be ensured that one rotation of the rotatable lens causes the space in front to be scanned N times (N≥2) by the projected image I from left to right. Alternatively, by configuring the shape of the outer circumferential surface  16   b  of the rotatable lens  16  to result in the cross sectional shape in the order of  FIG. 3A ,  FIG. 3B ,  FIG. 3C ,  FIG. 3B ,  FIG. 3A ,  FIG. 3E ,  FIG. 3D ,  FIG. 3E , and  FIG. 3A , an optical unit in which the projected image I scans the space in front of the vehicle horizontally and reciprocally can be realized. 
     Second Embodiment 
       FIG. 4  is a schematic side view of the vehicle headlamp according to the second embodiment. Those features that are equivalent to the features of  FIG. 1  and  FIG. 2  are denoted by the same reference numerals and a description thereof is omitted as appropriate. The advantages and features different from those of the first embodiment will be highlighted. 
     A vehicle headlamp  30  includes an optical unit  32  and a projection lens  14  that projects a light source image output from the optical unit  32  in front of the vehicle. The optical unit  32  includes a cylindrical rotatable lens  34 , a semiconductor light-emitting element  18  provided in the rotatable lens  34 , a motor  20  provided to the side of the rotatable lens  34  and driving the rotatable lens  34  into rotation, and a control unit  22  that controls the lighting and extinguishing of the semiconductor light-emitting element  18  and the driving of the motor  20 . 
     The rotatable lens  34  is configured such that the light output from the semiconductor light-emitting element  18  is incident via an inner circumferential surface  34   a  of the transmitting area and is output via an outer circumferential surface  34   b  of the transmitting area as an irradiating beam. Further, the rotatable lens  34  is driven by the motor  20  and is configured to form a predetermined irradiated area by scanning the space in front with the irradiating beam vertically according to a periodic movement (rotational movement) around the rotary shaft R. 
       FIG. 5A  shows area A′ of the rotatable lens shown in  FIG. 4 ,  FIG. 5B  shows area B′ of the rotatable lens shown in  FIG. 4 ,  FIG. 5C  shows area C′ of the rotatable lens shown in  FIG. 4 ,  FIG. 5D  shows area D′ of the rotatable lens shown in  FIG. 4 ,  FIG. 5E  shows area E′ of the rotatable lens shown in  FIG. 4 ,  FIG. 5F  shows a projected image formed by the irradiating beam transmitted through area A′ shown in  FIG. 5A ,  FIG. 5G  shows a projected image formed by the irradiating beam transmitted through area B′ shown in  FIG. 5B ,  FIG. 5H  shows a projected image formed by the irradiating beam transmitted through area C′ shown in  FIG. 5C ,  FIG. 5I  shows a projected image formed by the irradiating beam transmitted through area D′ shown in  FIG. 5D , and  FIG. 5J  shows a projected image formed by the irradiating beam transmitted through area E′ shown in  FIG. 5E . 
     Area A′ is positioned at the angle of rotation of the rotatable lens  16  of 0 degrees, area B′ is positioned at the angle of rotation of the rotatable lens  16  of 72 degrees, area C′ is positioned at the angle of rotation of the rotatable lens  16  of 144 degrees, area D′ is positioned at the angle of rotation of the rotatable lens  16  of 216 degrees, and area E′ is positioned at the angle of rotation of the rotatable lens  16  of 288 degrees. 
     As shown in  FIGS. 5F-5J , a projected image I moves gradually in the upward direction of the figure. Thus, the vehicle headlamp  30  can form a predetermined irradiated area (a light distribution pattern P 1 ) by scanning the space in front with the irradiating beam according to the periodical movement of the cylindrical rotatable lens  34 . 
     OTHER ADVANTAGES 
     The rigidity of a cylindrical rotatable lens can be higher as compared with a rotatable lens having a blade. Further, the rotary shaft R is perpendicular to the longitudinal direction of the optical unit (vehicle headlamp) so that a driving source can be provided to the side of the rotatable lens. Accordingly, the length of the longitudinal direction of the optical unit can be reduced. Further, in the embodiments described above, the light of the semiconductor light-emitting element is incident on the inner circumferential surface substantially perpendicularly so that the impact from refraction is little. For this reason, refraction of light transmitted through the rotatable lens and output from the outer circumferential surface need be primarily considered, and it is relatively easy to configure the surface shape of the outer circumferential surface. Conversely, an attempt to control refraction on the inner circumferential surface also requires considering refraction on the outer circumferential surface, which makes it difficult to configure the surface shape of the inner circumferential surface and the outer circumferential surface. Further, it is difficult to work the inner circumferential surface of the rotatable lens into a complicated shape, but it is relatively easy to work the outer circumferential surface. 
     The embodiments of the present invention are not limited to those described above and appropriate combinations or replacements of the features of the embodiments are also encompassed by the present invention. The embodiments may be modified by way of combinations, rearranging of the processing sequence, design changes, etc., based on the knowledge of a skilled person, and such modifications are also within the scope of the present invention. 
     For example, a light source that emits invisible light such as infrared (IR)-LD, IR-LED, light detection and ranging (LiDAR) LD may be used in the optical unit according to the embodiments described above. This can realize an optical unit that can be applied to sensor devices and sensing support devices.