JP2017130454A - Light source device, vehicular headlight, and manufacturing method of light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device (10, 20, 40) comprising a laser (1) for sending out a light beam (4), a fluorescent screen (2) within a beam passage of the laser (1), and a screen (3) disposed between the laser (1) and the fluorescent screen (2).SOLUTION: The screen (3) within the beam passage of the laser (1) includes at least one opening through which the light beam (4) sent out by the laser (1) is passed. Thus, the light beam (4) sent out by the laser (1) excites the fluorescent screen (2) in such a manner that lights (5a and 5c) are sent out. The screen (3) includes a retroreflection layer (3a) formed to reflect the light (5a) that is sent out by the fluorescent screen (2).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light source device, a vehicle headlight, and a method for manufacturing the light source device.

Prior Art For example, in the automotive industry, there is a demand for efficient light sources. A known method for generating an optical signal with a strong output is to excite and illuminate a fluorescent screen using a laser beam. This phosphor screen emits the beam in all spatial directions, generally isotropic. From WO 2010/084451 (WO2010 / 084451 A1), for example, such a light source as described above is known. Here, wire grid polarizers are arranged on both sides of a fluorescent screen. This wire grating polarizer is used here to reduce the temperature where the laser beam is incident on the phosphor screen and excites the phosphor screen for light emission.

International Publication No. 2010/088441

  However, typically only the beam emitted in the forward direction, i.e. away from the laser, is actually relevant. That is, on average, half of the generated light beam is lost. This is because half of the light beam is emitted in the backward direction, ie in the direction of the laser.

DISCLOSURE OF THE INVENTION In a first aspect, the present invention realizes a light source device having the configuration described in the characterizing portion of claim 1.

  Accordingly, the present invention realizes a light source device that includes a laser that emits a light beam and a fluorescent screen in the beam path of the laser. A screen is disposed between the laser and the phosphor screen, wherein the screen has at least one opening through which the light beam transmitted by the laser passes in the laser beam path. Thus, the light beam emitted by the laser is configured to excite the phosphor screen to emit light. The screen has a retroreflective layer, and this retroreflective layer is formed so as to reflect the light transmitted by the fluorescent screen.

  In another aspect, the present invention realizes a vehicle headlight having the configuration described in the characterizing portion of claim 7. Accordingly, the present invention includes a vehicle headlight having at least one light source device.

  In another aspect, the present invention realizes a method of manufacturing a light source device having the configuration described in the characterizing portion of claim 8.

  Accordingly, the present invention realizes a method of manufacturing a light source device, and this method includes a first step of arranging a fluorescent screen in the beam path of a laser. Further, a screen is disposed between the laser and the fluorescent screen. At least one opening is formed in the screen for passing the light beam emitted by the laser. Thereby, the light beam transmitted by the laser is incident on the fluorescent screen, and the fluorescent screen can be excited so as to transmit light. Further, a retroreflective layer that reflects light transmitted by the fluorescent screen is formed on the screen.

  Advantageous developments are the requirements of each dependent claim.

Advantages of the invention The retroreflective layer advantageously reflects light transmitted by the phosphor screen back to the radiation source, ie the excitation point of the phosphor screen. This beam now passes through the fluorescent screen or is absorbed by the fluorescent screen, and the fluorescent screen is thereby excited to emit light again. Therefore, the usable beam output of this light source device, that is, the overall ratio of the beam finally transmitted in the forward direction is increased. The beam emitted in the rear direction of the phosphor screen is preferably reflected as completely as possible by the retroreflective layer. Thus, beam loss due to light transmitted in the backward direction and not reflected is minimized.

  By increasing the usable beam power, for example, the number of lasers required for a vehicle headlight can be reduced. This reduces not only the current consumption, but at the same time the complexity and cost of the vehicle headlight.

  In an advantageous development of the light source device, the screen is arranged at a distance from the fluorescent screen.

  In an advantageous development of the light source device, the retroreflective layer comprises a triple mirror reflector, whereby the reflected light is substantially returned again to the point of light delivery of the fluorescent screen. It is.

  In an advantageous development, the light source device includes a substrate, in particular made of glass. Here, the screen and the fluorescent screen are disposed on opposite surfaces of the substrate. This substrate ensures a higher stability of the light source device.

  In an advantageous development of the light source device, the substrate comprises a wire grating polarizer. Similarly, the wire grating polarizer reflects a part of the incident beam, thereby further enhancing the effect of the light source device.

  In an advantageous development of the light source device, the laser is configured as a laser scanner designed to deliver a light beam in an angular range. Here, the diameter of at least one opening of the screen is selected as follows. That is, the diameter is selected to substantially correspond to the width of this angular range on the screen. In particular, this makes at least one opening of the screen as small as possible, thus minimizing the proportion of the beam transmitted by the fluorescent screen that passes through this at least one opening in the direction of the laser and is not reflected. Is done. This further reduces the unusable beam.

1 is a schematic cross-sectional view of a light source device according to a first embodiment of the present invention. The schematic cross-sectional view of the light source device of the 2nd Embodiment of this invention. The schematic cross-sectional view of a light source device. The schematic cross-sectional view of the light source device of the 3rd Embodiment of this invention. The schematic cross-sectional view of the light source device of the 4th Embodiment of this invention. 1 is a schematic cross-sectional view of a vehicle headlight according to the present invention. The flowchart explaining the manufacturing method of the light source device of this invention.

  In all of the drawings, elements or devices that are equivalent or similar in function are labeled with the same reference signs unless otherwise stated. The numbering of the steps is for clarity and should not include the meaning of any particular temporal order, unless specifically stated otherwise. In particular, a plurality of steps can be performed simultaneously.

DESCRIPTION OF EXAMPLES FIG. 1 shows a schematic cross-sectional view of a light source device 10 according to a first embodiment of the present invention. Here, the light source device 10 includes a laser 1 that emits a light beam 4. The laser 1 here may in particular be configured to emit blue light or ultraviolet light.

  The laser 1 is advantageously a laser scanner designed to scan in a certain spatial angular range. The laser 1 is oriented so as to emit a light beam 4 in an angle range α in the vertical direction. This is done in particular by turning the micromirror of the laser. In addition to this, the laser 1 can advantageously be oriented to deliver a light beam 4 in a certain angular range in a horizontal direction perpendicular to the drawing plane.

  In the beam path of the laser 1, a fluorescent screen 2, that is, a screen having at least one fluorescent layer is arranged. This fluorescent layer is excited by the light beam 4 emitted by the laser 1 and emits light.

A screen 3 is arranged between the laser 1 and the fluorescent screen 2 in the beam path of the laser 1, separated from the fluorescent screen by a distance d ₃ . The distance d ₃ between the fluorescent screen 2 and the screen 3 may be, for example, 5 mm to 40 mm, and advantageously 20 mm. The screen 3 has at least one opening 9 through which the light beam 4 emitted by the laser passes. The geometric shape of the opening 9 is arbitrary here. However, advantageously, the opening 9 is circular. The diameter d ₁ of the opening 9 of the screen 3 is advantageously selected as follows. That is, the light beam 4 in the entire angle range α is selected so that it can pass through the opening 9 of the screen 3. Here, this diameter d ₁ is advantageously chosen to be as small as possible, and the diameter d ₁ advantageously corresponds to the width of the angular range α at the screen 3. Advantageously, the beam waist d ₂ of the light beam 4 is also considered here.

  Advantageously, the laser 1 is arranged centrally and before the center point of the opening 9. However, the laser 1 may be arranged shifted.

  The laser beam 4 transmitted by the laser 1 passes through the opening 9 of the screen 3 and enters the incident point 6 of the fluorescent screen 2. The fluorescent screen 2 is excited to emit light at the incident point 6. A surface having a diameter D on the fluorescent screen 2 is scanned or illuminated by the laser 1 by turning the laser beam 4 transmitted by the laser 1 in the angle range α. Here, this diameter D is preferably between 1 cm and 20 cm. However, the present invention is not limited to this. Therefore, the laser 1 can also scan and eventually illuminate a surface of an arbitrary shape on the fluorescent screen 2.

  Hereinafter, light transmission in the “rear direction” is distinguished from light transmission in the “forward direction”. The space is divided into two half spaces depending on the surface on which the fluorescent screen 2 is located. The transmission of the light beam in the “rear direction” here means that the light beam spreads in the half space where the laser 1 is present. When the light beam is transmitted in the “forward direction”, the light beam spreads in the other half space where the laser 1 is not present.

  On the screen 3, at least one retroreflective layer 3a is formed. The retroreflective layer 3a may include a triple mirror reflector in particular. However, the retroreflective layer 3a can also include a Luneburg lens. The retroreflective layer 3a may in particular comprise a spherical element with a metallized back.

The size of the openings of the individual reflector elements of the triple mirror reflector can be, for example, about 100 μm. The distance d ₃ between the fluorescent screen 2 and the screen 3, if for example, 20 mm, the diameter of the Airy disk on the phosphor screen 2 is about 280 .mu.m. Here, the Airy disk advantageously corresponds approximately to the beam waist d ₂ of the transmitted laser beam 4. However, all these numbers are only examples.

  The light beam 5 a transmitted in the backward direction is incident on the retroreflective layer of the screen 3. The retroreflective layer is configured to reflect the light beam 5a substantially along a direction opposite to the incident direction of the light beam 5a of the retroreflective layer 3a. That is, the light beam 5 b reflected in this way propagates in the direction of the incident point 6 of the fluorescent screen 2. The reflected light beam 5b can pass through the fluorescent screen 2 and then diffuses forward. However, the reflected light beam 5b can also excite the fluorescent screen 2 for the re-transmission of light, thereby increasing the light emission efficiency.

  Finally, the total proportion of light beams emitted in the forward direction, i.e., the sum of the originally emitted and reflected beams in the forward direction, is at least 85 of the total light beams emitted by the phosphor screen. Estimated as a percentage. However, it should be understood that this number is merely an example.

  The present invention is not limited to the above-described embodiment. In particular, the screen 3 can have a large number of openings.

  In addition, a number of additional optical elements, in particular lenses, may be mounted in front of and / or behind the fluorescent screen 2.

  FIG. 2 shows a second embodiment of the light source device 20 of the present invention. In the first embodiment, the screen 3 is spaced from the fluorescent screen 2, that is, separated from the air. In the second embodiment, the screen 3 and the fluorescent screen 2 are separated from each other by a substrate. 7 are arranged on opposite surfaces. The substrate 7 can consist in particular of glass or another light transmissive, ie transparent or translucent material. The fluorescent screen 2 and the screen 3 are here preferably fixed to the substrate 7 in a fixed manner, in particular by adhesion or deposition.

  FIG. 3 shows a cross-sectional view of the light source device 30. The light source device 30 includes a laser 1 that emits a light beam 4. The laser 1 is advantageously a laser scanner designed to deliver the light beam 4 in the vertical direction in the angular range α. This is done in particular by turning the micromirror of the laser. A fluorescent screen 2 is formed in the beam path of the laser 1. The fluorescent screen 2 is disposed on the surface of the substrate 7 opposite to the laser. The substrate 7 now contains a wire grid polarizer 8, i.e. an array of parallel metal wires with good conductivity. The light beam 4 transmitted by the laser 1 is configured to excite the fluorescent screen 2 so as to transmit light. The light beam 5c transmitted in the backward direction can here be at least partly reflected by the wire grating polarizer 8. The light beam 5d thus reflected is incident on the fluorescent screen 2 again to excite the fluorescent screen 2 so as to repeatedly transmit light, or is transmitted through the fluorescent screen 2 in the forward direction. Propagate.

  The light emitted by the fluorescent screen 2 is now generally randomly polarized. That is, it does not have a special polarization direction. The light beam 5c is transmitted or reflected based on the polarization of the wire grating polarizer. For example, for an incident angle of 45 °, the transmittance of the p-polarized component relative to the wire grating polarizer is about 85%. The percentage of reflected, s-polarized component can be estimated as approximately 85%. Based on this, it is expected that at least 60% of the light will eventually be emitted in the forward direction. However, it should be understood that this number is merely an example.

  FIG. 4 shows a cross-sectional view of the light source device 40 according to the third embodiment of the present invention. The third embodiment differs from the second embodiment shown in FIG. 2 in the following points. That is, the difference is that the wire grid polarizer 8 is formed in the substrate 7 between the fluorescent screen 2 and the screen 3 as in the light source device 30 shown in FIG. Here, the wire grating polarizer 8 can reflect the light beam 5c transmitted in the backward direction. The reflected light beam 5d passes through the fluorescent screen 2 or excites the fluorescent screen to send light again.

FIG. 5 shows a cross-sectional view of a light source device 50 according to a fourth embodiment of the present invention. The fourth embodiment differs from the third embodiment shown in FIG. 4 in the following points. In other words, the difference is that the distance d ₃ between the fluorescent screen 2 and the screen 3 is larger than the thickness d _{4 of the} substrate 7 having the wire grid polarizer 8. Accordingly, the screen 3 is arranged at a distance from the substrate 7.

  FIG. 6 shows a cross-sectional view of a vehicle headlight 60 having the light source device 10 of the first embodiment. The vehicle headlight 60 has a housing 51 here. Here, the fluorescent screen 2 is disposed in the opening of the housing 51. The fluorescent screen 2 is protected by the shielding part 52 from the influence of the surroundings. The shielding unit 52 further includes a lens system. This lens system is oriented so that the light transmitted by the fluorescent screen 2 is transmitted to the outside at a predetermined angle. The laser 1 is arranged here as follows. That is, the transmitted light beam 4 enters the fluorescent screen 2 through the opening 9 of the screen 3, and the light propagated forward by the fluorescent screen 2 passes through the shielding unit 10 and passes through the shielding unit 10. It is arranged to radiate out from 60.

  The present invention is not limited to this, and other embodiments of the light source device for the vehicle headlight 60 can be used.

  FIG. 7 shows a flowchart for explaining the method for manufacturing the light source device of the present invention.

In the first step S1, the fluorescent screen 2 is arranged in the beam path of the laser 1, in particular a laser scanner. The laser 1 is advantageously configured to deliver a light beam 4 in the angular range α. In the second step S2, the screen 3 is disposed between the laser 1 and the fluorescent screen 2. In the screen 3, at least one opening 9 through which the light beam 4 transmitted by the laser 1 passes is formed in the third step S <b> 3. Advantageously, here a large number of openings are formed in the screen 3. The diameter d ₁ of the opening 9 of the screen 3 here advantageously corresponds substantially to the beam waist d ₂ of the light beam 4 emitted by the laser 1. The light beam 4 transmitted by the laser 1 passes through at least one opening and enters the fluorescent screen 2 at the incident point 6. As a result, the fluorescent screen 2 is excited to emit light.

  In the fourth step S4, the retroreflective layer 3a is formed on the screen 3. Here, the retroreflective layer 3a is configured such that light transmitted backward by the fluorescent screen 2 enters the retroreflective layer 3a and is reflected there.

Claims (8)

A laser (1) for delivering a light beam (4);
A fluorescent screen (2) in the beam path of the laser (1);
A screen (3) disposed between the laser (1) and the fluorescent screen (2);
A light source device (10, 20, 40, 50) comprising:
The screen (3) in the beam path of the laser (1) has at least one opening through which the light beam (4) transmitted by the laser (1) passes, whereby the The light beam (4) transmitted by a laser (1) is configured to excite the phosphor screen (2) to transmit light (5a, 5c);
The screen (3) has a retroreflective layer (3a) formed to reflect the light (5a) transmitted by the fluorescent screen (2).
A light source device (10, 20, 40, 50) characterized by that. 2. The light source device (10, 20, 40, 50) according to claim 1, wherein the screen (3) is arranged at a distance (d ₃ ) from the fluorescent screen (2).   The light source device (10, 20, 40, 50) according to claim 1 or 2, wherein the retroreflective layer (3a) includes a triple mirror reflector. In particular it has a substrate (7) made of glass,
The light source device (20, 40, 4) according to any one of claims 1 to 3, wherein the screen (3) and the fluorescent screen (2) are arranged on opposite surfaces of the substrate (7). 50).   The light source device (40, 50) according to claim 4, wherein the substrate (7) comprises a wire grid polarizer (8). The laser (1) is configured as a laser scanner,
The laser scanner is designed to deliver the light beam (4) in an angular range α,
The diameter (d ₁ ) of the at least one opening of the screen (3) is selected to substantially correspond to the width of the angular range α at the screen (3). The light source device (10, 20, 40, 50) according to any one of 1 to 5. It has at least one light source device (10, 20, 40, 50) according to any one of claims 1 to 6.
The vehicle headlight (60) characterized by the above-mentioned. A method of manufacturing a light source device (10, 20, 40, 50),
Placing the fluorescent screen (2) in the beam path of the laser (1) (S1);
Placing the screen (3) between the laser (1) and the fluorescent screen (2) (S2);
The light beam (4) transmitted by the laser (1) is incident on the fluorescent screen (2) and can excite the fluorescent screen (2) to transmit light (5a, 5c). Forming at least one opening in the screen (3) for allowing the light beam (4) transmitted by the laser (1) to pass therethrough (S3);
Forming a retroreflective layer (3a) on the screen (3) to reflect the light (5a) transmitted by the fluorescent screen (2) (S4);
A method for manufacturing a light source device (10, 20, 40, 50), comprising: