JP2015228306A - On-vehicle head lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-vehicle head lamp that projects light with a clear outline ahead of a vehicle.SOLUTION: A light-emitting surface 2c of a fluorescent body 2, which receives a laser beam applied by laser beam oscillator 1 and emits light different in wavelength from the laser beam, is formed as a curved surface along a focal plane F of a projection lens 4, which assumes a shape bringing a peripheral part closer to the projection lens 4 than a central part. Thus, a bright spot of the light-emitting surface 2c can be projected like a spot with little halation ahead of a vehicle.

Description

  The present invention relates to an in-vehicle headlamp that illuminates the front of a vehicle.

  In the current situation where the trend of reducing carbon dioxide emissions to promote global warming and bright LEDs (light-emitting diodes, semiconductor light sources) with high luminous efficiency are realized, light sources for in-vehicle lamps have also been used in the past. Instead of tungsten filament bulbs, low-power LEDs are becoming popular. This LED is suitable as a light source for an in-vehicle lamp because it has a long life and can emit stable brightness by simple control for supplying a constant current. Furthermore, with the recent increase in output (high light intensity), it has begun to spread as a light source for in-vehicle headlamps.

  In many cases, LEDs that have been widely used are a combination of an LED that emits blue light and a phosphor (wavelength conversion element) that emits yellow light in response to the blue light emitted by the LED. A light source that combines a laser light oscillator (laser diode, LD) that emits blue laser light and a phosphor that emits white light is also becoming popular with a slight delay from LEDs.

  While the light source has changed to LED or laser light oscillator as described above, the function of on-vehicle headlamps has also evolved, and the driver driving oncoming vehicles is not dazzled while illuminating the front with bright light for driving lights Thus, a headlamp that darkens the direction of the oncoming vehicle, that is, does not irradiate light in the direction of the oncoming vehicle has been put into practical use. Do not irradiate light in the direction of the oncoming vehicle, in other words, as a headlamp that forms an arbitrary light distribution, direct light with a point-like irradiation surface like a laser beam (laser beam) in an arbitrary direction Configuration is desired. However, since the above laser light is monochromatic light, an in-vehicle headlamp that requires white light cannot be directly configured. Therefore, the laser light is first irradiated to the phosphor, and the arbitrary light generated on the surface of the phosphor The shade of the white light-emitting part having the shape is projected to the front of the vehicle using an optical member (projection lens) that projects light such as a convex lens to the front of the vehicle (for example, see Patent Documents 1 and 2). .

  Patent Document 1 relates to a vehicle headlamp that includes a laser light source and a light emitting unit that receives and emits laser light emitted from the laser light source, and emits light emitted from the light emitting unit forward. In this vehicle headlamp, a light control unit that guides laser light is disposed between a laser light source and a light emitting unit, and the position of the light emitted from the laser light in the light emitting unit is changed so that the light projected to the front of the vehicle It is the structure which moves a position. It is described that a MEMS (Micro Electro Mechanical System) mirror, a piezo mirror element, or a galvanometer mirror is used as the light control unit. However, in this patent document 1, the light emission part (phosphor surface) is a flat surface, and there is no description which makes it a curved surface.

  Patent Document 2 relates to a vehicular lamp including a laser light source and a fluorescent member that receives a laser beam emitted from the laser light source and forms a light distribution pattern. This vehicular lamp includes a scanning unit that scans laser light and distributes the laser light to each fluorescent member, and changes the irradiation direction of the laser light. It is described that a MEMS mirror or a galvanometer mirror is used as the scanning unit. However, in this patent document 2, the fluorescent member (phosphor surface) is a flat surface, and there is no description which makes it a curved surface.

JP 2013-232390 A International Publication No. 2013/99144 Pamphlet

  By the way, projection lenses used for in-vehicle headlamps are often cheap, simple in construction, and often use a single convex lens, which eliminates aberrations by combining multiple lenses like a camera or telescope. I can't. Therefore, it is assumed that a projection lens for a headlamp is a convex lens having a large aberration, such as a spherical aberration, with inconvenience.

  In a single convex lens having large spherical aberration, the focal point deviating from the optical axis is closer to the convex lens than the focal point on the optical axis. Therefore, when light is incident and a shadow is imaged inside like a camera, the focal plane is not flat like a film of a silver salt camera or an image sensor of a digital camera, and the surrounding area is around the center. The part becomes a curved surface approaching the convex lens. On the contrary, when light is emitted and an image is formed outside like a film projection device, if the projection image is made flat like a film, the peripheral image away from the optical axis will be blurred. It is necessary to draw an image for projection on a curved surface corresponding to the curved focal plane. The same applies to in-vehicle headlamps. When a flat fluorescent surface is arranged on a convex lens having a large focal aberration and a curved focal plane, the contour of light projected in front of the vehicle is blurred.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an in-vehicle headlamp with a clear outline of light projected in front of a vehicle.

  The in-vehicle headlamp according to the present invention includes a laser beam oscillator, a phosphor that emits light having a wavelength different from the laser beam received by the laser beam irradiated by the laser beam oscillator, and the laser beam irradiated by the laser beam oscillator. And a movable reflecting member that changes the irradiation position of the laser light on the phosphor, and an optical member that projects the light emitted from the phosphor to the front of the vehicle. The light emitting surface is a curved surface having a shape in which at least a part of the peripheral portion is closer to the optical member than the center portion.

  According to the present invention, since the light emitting surface of the phosphor is a curved surface in which at least a part of the peripheral portion is closer to the optical member than the central portion, the light emitting surface of the phosphor is disposed on the focal plane of the optical member. Thus, an in-vehicle headlamp having a clear outline of light projected in front of the vehicle can be provided.

It is sectional drawing which shows the structural example of the vehicle-mounted headlamp which concerns on Embodiment 1 of this invention. It is an enlarged view which shows an example of a laser beam oscillator, a fluorescent substance, a movable reflecting mirror, and a projection lens among the vehicle-mounted headlamps which concern on Embodiment 1. FIG. FIG. 3 is a reference example for helping understanding of the in-vehicle headlamp according to the first embodiment, and is a diagram using a planar phosphor in place of the curved phosphor in FIG. 2. It is a schematic diagram which shows an example of the MEMS mirror comprised from a movable reflecting mirror and a reflecting mirror drive part among the vehicle-mounted headlamps which concern on Embodiment 1. FIG. It is sectional drawing which shows the structural example of the vehicle-mounted headlamp which concerns on Embodiment 2 of this invention. It is a figure explaining the light which a fluorescent substance emits in the vehicle-mounted headlamp which concerns on Embodiment 2. FIG. FIG. 10 is a cross-sectional view showing a modification of the in-vehicle headlamp according to the second embodiment. It is sectional drawing which shows the structural example of the vehicle-mounted headlamp which concerns on Embodiment 3 of this invention. It is a figure explaining the light which a fluorescent substance emits in the vehicle-mounted headlamp which concerns on Embodiment 3. FIG. FIG. 10 is a cross-sectional view showing a modification of the in-vehicle headlamp according to the third embodiment.

Embodiment 1 FIG.
As shown in FIG. 1, the in-vehicle headlamp according to the first embodiment includes a laser light oscillator 1 and a fluorescent light that emits light having a wavelength different from that of the laser light received by the laser light emitted from the laser light oscillator 1. A body 2, a movable reflecting mirror (movable reflecting member) 3 that reflects the laser light irradiated by the laser light oscillator 1 to change the irradiation position of the laser light on the phosphor 2, and light emitted by the phosphor 2 A projection lens (optical member) 4 that projects the front of the vehicle, a phosphor holding / dissipating part 5 that also serves as a holding member that holds the phosphor 2, a case 6 that accommodates these, a front lens 7, and a movable And a reflecting mirror driving unit 8 for driving the reflecting mirror 3. In the configuration example of FIG. 1, a part of the phosphor holding / radiating part 5 is exposed to the outside of the case 6 to improve the heat dissipation of the heat generated by the phosphor 2.

FIG. 2 is an enlarged view for explaining the laser light oscillator 1, the phosphor 2, the movable reflecting mirror 3, and the projection lens 4. In FIG. 2, illustration of the reflector driving unit 8 is omitted.
The phosphor 2 (light emitting surface 2c) is a wavelength conversion element, receives laser light L1 (for example, blue) irradiated by the laser light oscillator 1, and has a wavelength (for example, white) that is different from that of the laser light L1. Issue L2. The light L2 emitted from the light emitting surface 2c of the phosphor 2 is projected from the projection lens 4 to the front of the vehicle.

As the projection lens 4 used for the vehicle headlamp, a single convex lens that is inexpensive and has a simple configuration is often used. Such a projection lens 4 has large spherical aberration, and the focal point at a position deviating from the optical axis is closer to the projection lens 4 than the focal point on the optical axis. For this reason, the focal plane F of the projection lens 4 is a curved surface whose peripheral portion approaches the projection lens 4 side with respect to the central portion. Therefore, in the first embodiment, the light emitting surface 2 c facing the projection lens 4 of the phosphor 2 is formed in a curved shape along the focal plane F of the projection lens 4. That is, the peripheral portion of the light emitting surface 2 c is a shape that approaches the projection lens 4 from the central portion, and the central portion is a shape that is recessed on the opposite side to the projection lens 4.
In the illustrated example, a configuration example using one projection lens 4 is shown, but a plurality of projection lenses 4 may be arranged side by side on the optical axis.

  When the reflecting mirror driving unit 8 tilts the movable reflecting mirror 3 in the vertical direction and the horizontal direction, the laser light L1 is scanned on the light emitting surface 2c of the phosphor 2. Thereby, the projection area | region of the light L2 projected ahead of a vehicle through the projection lens 4 changes according to the irradiation position of the laser beam L1 in the light emission surface 2c. In FIG. 2, the shapes of the projection areas A1 and A2 are expressed on the screen S, and the bright part is expressed darkly and the dark part is expressed lightly. When the curved light emitting surface 2c along the shape of the focal plane F of the projection lens 4 is used, the projection lens 4 projects the laser light L1 whichever irradiation position P1, P2 of the light emitting surface 2c is irradiated. Since the light becomes parallel light and is less blurred, the projected areas A1 and A2 on the screen S have clear outlines. Accordingly, if an arbitrary shadow is drawn on the light emitting surface 2c while scanning the laser light L1 up and down, left and right, and the shadow drawn on the light emitting surface 2c is projected from the projection lens 4 to the front of the vehicle, a light / dark boundary, that is, It is possible to form a headlamp with a clear outline and no unevenness in brightness. The shade drawn on the light emitting surface 2c is, for example, a light distribution pattern for a passing lamp or a light distribution pattern for a traveling lamp. For example, when a shadow that forms a cut-off line for a passing light is drawn on the light emitting surface 2c, the cut-off line projected in front of the vehicle becomes clear to the left and right peripheral parts.

  Here, as a reference example for explaining the effect of the first embodiment, FIG. 3 shows an optical system using a phosphor 20 having a planar light emitting surface. When the phosphor 20 is used, the projection area A1 on the screen S has a clear outline when the laser light L1 is irradiated onto the planar light emitting surface at the position P1 that overlaps the focal point F of the projection lens 4. On the other hand, when the laser light L1 is applied to the position P2 away from the focal point F of the projection lens 4 on the planar light emitting surface, the outline of the projection area A2 on the screen S is blurred. Therefore, for example, when a shadow forming a cut-off line for a passing lamp is drawn on the planar phosphor 20, the left and right peripheral portions of the cut-off line projected in front of the vehicle are blurred.

  FIG. 4 is a schematic diagram showing an example of a MEMS mirror composed of the movable reflecting mirror 3 and the reflecting mirror driving unit 8. The reflecting mirror driving unit 8 includes a base 8a, a first rotating body 8b, a first rotating shaft 8c, a second rotating shaft 8d, first piezoelectric elements 8e and 8f, and second piezoelectric elements 8g and 8h. The base 8a is a frame and is fixed to the vehicle headlamp. A first rotating body 8b is rotatably connected to the opening of the base 8a by a first rotating shaft 8c, and the first rotating body 8b is moved in a first time in accordance with the expansion and contraction of the first piezo elements 8e and 8f. It rotates around the moving shaft 8c. The movable reflecting mirror 3 is rotatably connected to the opening of the first rotating body 8b by the second rotating shaft 8d, and the movable reflecting mirror 3 is moved in accordance with the expansion and contraction of the second piezo elements 8g and 8h. It rotates around the moving shaft 8d. Thereby, the laser beam can be scanned at an arbitrary position on the light emitting surface 2c.

In FIG. 4, the MEMS mirror using a piezo element as a drive source is illustrated. However, the present invention is not limited to this, and a galvanometer mirror using a motor as a drive source may be used.
Also, the irradiation position of the light emitting surface 2c corresponding to the projection area illuminated brightly is scanned slowly with the laser light at the irradiation position of the light emitting surface 2c corresponding to the projection area illuminated relatively brightly. In this case, the brightness of the light can be adjusted for each portion projected in front of the vehicle by scanning the laser beam quickly (relatively shortening the irradiation time for one point).

  As described above, according to the first embodiment, the in-vehicle headlamp includes the laser beam oscillator 1 and the phosphor 2 that receives the laser beam irradiated by the laser beam oscillator 1 and emits light having a wavelength different from the laser beam. Then, the laser beam emitted from the laser oscillator 1 is reflected toward the phosphor 2, and the movable reflecting mirror 3 that changes the irradiation position of the laser beam on the phosphor 2 and the light emitted by the phosphor 2 in the vehicle The light emitting surface 2c of the phosphor 2 is a curved surface whose peripheral portion approaches the projection lens 4 from the central portion. For this reason, the vehicle-mounted headlamp with which the outline of the light projected ahead of the vehicle is clear can be provided. Further, by scanning the laser light applied to the light emitting surface 2c, it is possible to form a light source (shadow) having an arbitrary shape with no spots on the light emitting surface 2c, and to form an arbitrary light distribution pattern in front of the vehicle. Thereby, for example, it is possible to realize a traveling light that does not illuminate the direction of the oncoming vehicle and illuminates the other directions brightly so as not to dazzle the driver driving the oncoming vehicle.

  Further, according to the first embodiment, the light emitting surface 2c of the phosphor 2 is a curved surface having a shape along the focal plane F of the projection lens 4, so that the laser light is irradiated to any position on the light emitting surface 2c. Even in this case, the outline of the light projected in front of the vehicle becomes clear.

Further, according to the first embodiment, since the movable reflecting mirror 3 is arranged around the projection lens 4, the light emitted from the phosphor 2 is projected in front of the vehicle without being blocked, and the light use efficiency is high. .
However, since the laser light is irradiated from the oblique direction to the light emitting surface 2c, the laser light is irradiated at a shallow angle particularly on the laser light oscillator 1 side of the light emitting surface 2c, and a bright spot (that is, , The point of light emission) may increase.

Embodiment 2. FIG.
FIG. 5 is a cross-sectional view showing a configuration example of the in-vehicle headlamp according to the second embodiment. 5 that are the same as or equivalent to those in FIGS. 1 to 4 are denoted by the same reference numerals and description thereof is omitted. In the configuration example of FIG. 5, the movable reflecting mirror 3 is disposed on the optical axis of the projection lens 4, and the laser light L <b> 1 is irradiated from the front of the light emitting surface 2 c of the phosphor 2. As a result, a small bright spot that cannot be drawn when the light emitting surface 2c is irradiated with laser light from an oblique direction as in the first embodiment can be drawn.

  However, when the movable reflecting mirror 3 is arranged at the center of the projection lens 4, a part of the light emitted from the phosphor 2 is blocked by the movable reflecting mirror 3 as shown in FIG. Compared with the case where the movable reflecting mirror 3 is arranged, the light utilization efficiency is lowered.

  In FIG. 5, the laser light oscillator 1 is disposed behind the phosphor 2, and the laser beam L <b> 1 is applied to the movable reflecting mirror 3 through an opening formed in the phosphor 2 and the phosphor holding / heat dissipating unit 5. Although configured, it is not limited to this configuration. Here, a modification is shown in FIG. In the modification of FIG. 7, the fixed reflecting mirror 10 is disposed on the optical axis of the projection lens 4. The laser beam oscillator 1 and the movable reflecting mirror 3 are arranged at positions away from the projection lens 4 to guide the laser beam L1 to the fixed reflecting mirror 10.

  As described above, according to the second embodiment, since the movable reflecting mirror 3 is arranged on the optical axis of the projection lens 4, the spot-shaped light (laser beam) that has been narrowed down is scanned vertically and horizontally in front of the vehicle. Can be irradiated. Accordingly, it is possible to realize a headlamp with a light distribution that is precise and has a clear light / dark boundary.

Embodiment 3 FIG.
FIG. 8 is a cross-sectional view illustrating a configuration example of the in-vehicle headlamp according to the third embodiment. FIG. 9 is a diagram for explaining light emitted from the phosphor 2. 8 and 9, the same or corresponding parts as those in FIGS. 1 to 7 are denoted by the same reference numerals and description thereof is omitted. In the configuration example of FIG. 8, the movable reflecting mirror 3 is moved below the projection lens 4 and the light emitting surface 2c is inclined downward. Even in this case, a part of the peripheral portion of the light emitting surface 2c is arranged closer to the projection lens 4 than the central portion. With this arrangement, it is possible to irradiate the light emitting surface 2c with a laser beam at a deeper angle than in FIG. 1, and to draw a small bright spot on the light emitting surface 2c.

  Furthermore, an optical path correction member 11 is installed between the phosphor 2 and the projection lens 4, and the light path of the light emitted from the light emitting surface 2 c of the phosphor 2 is bent and emitted to the projection lens 4. Thereby, the incident light of the optical path correction member 11 is refracted, and a virtual image 2-1 (apparent light emitting surface) of the phosphor 2 is formed on the optical axis of the projection lens 4. The downward movement and inclination of the phosphor 2 are canceled out, which is equivalent to the phosphor 2 being arranged on the optical axis in accordance with the focal plane F of the projection lens 4.

  As the optical path correction member 11, for example, a plate-shaped prism having a triangular cross section is used. The triangular prism has a different light traveling direction depending on the wavelength of light (chromatic aberration). Therefore, when the white light incident on the optical path correction member 11 from the phosphor 2 is dispersed for each wavelength and the light / dark boundary portion of the light projected in front of the vehicle becomes iridescent, the optical path correction member 11 has a different refractive index. It is preferable to reduce the generation of the iridescent color by using a plurality of members or by providing fine irregularities on the surface.

  As described above, according to the third embodiment, the light emitting surface 2c of the phosphor 2 is disposed at a position shifted from the optical axis of the projection lens 4 so as to be inclined with respect to the optical axis. The optical path correction member 11 is installed between the two so that the optical path of the light emitted from the phosphor 2 is changed and incident on the projection lens 4. For this reason, it is possible to realize a headlamp with high light utilization efficiency (bright with low power) and a precise light distribution.

  8 and 9, the optical path correction member 11 is provided alone, but may be configured integrally with the projection lens 4. Here, FIG. 11 shows a configuration example of an in-vehicle headlamp using a modified projection lens 12 in which the projection lens 4 and the optical path correction member 11 are integrated. By using the deformable projection lens 12, it is possible to realize a headlamp with a simple structure and high light utilization efficiency (low power and bright) and a precise light distribution.

  In addition to the above, within the scope of the present invention, the present invention can freely combine each embodiment, modify any component of each embodiment, or omit any component of each embodiment. It is.

  DESCRIPTION OF SYMBOLS 1 Laser beam oscillator, 2 fluorescent substance, 2-1 Virtual image of fluorescent substance, 2c Light emission surface, 3 Movable reflecting mirror, 4 Projection lens, 5 Phosphor holding / radiating part, 6 Case, 7 Front lens, 8 Reflecting mirror drive part 8a base, 8b first rotating body, 8c first rotating shaft, 8d second rotating shaft, 8e, 8f first piezo element, 8g, 8h second piezo element, 10 fixed reflector, 11 optical path correcting member, 12 Deformation projection lens, F Focal plane of projection lens.

Claims (6)

A laser light oscillator;
A phosphor that receives laser light emitted by the laser oscillator and emits light having a wavelength different from that of the laser light;
A movable reflecting member that reflects the laser beam emitted by the laser beam oscillator toward the phosphor and changes the irradiation position of the laser beam in the phosphor;
An optical member that projects light emitted from the phosphor to the front of the vehicle,
The in-vehicle headlamp characterized in that the light emitting surface of the phosphor is a curved surface in which at least a part of a peripheral portion is closer to the optical member than a central portion.   The in-vehicle headlamp according to claim 1, wherein a light emitting surface of the phosphor is a curved surface having a shape along a focal plane of the optical member.   The in-vehicle headlamp according to claim 1, wherein the reflecting member is disposed around the optical member.   The in-vehicle headlamp according to claim 1, wherein the reflecting member is disposed on an optical axis of the optical member. The light emitting surface of the phosphor is disposed at a position shifted from the optical axis of the optical member and inclined with respect to the optical axis,
The in-vehicle device according to claim 1, wherein an optical path correction member that changes an optical path of light emitted from the phosphor and enters the optical member is disposed between the phosphor and the optical member. For headlamps.   The in-vehicle headlamp according to claim 5, wherein the optical path correction member is formed integrally with the optical member.

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