DE102016200582A1 - Light source assembly, vehicle headlamp and manufacturing method for a light source assembly - Google Patents

Abstract

The invention relates to a light source arrangement (10, 20, 40), comprising a laser (1) for emitting a light beam (4); a phosphor screen (2) in the beam path of the laser (1); a screen (3) which is arranged between laser (1) and phosphor screen (2), wherein the screen (3) in the beam path of the laser (1) has at least one opening for passing the light beam (4) emitted by the laser (1) whereby the light beam (4) emitted by the laser (1) is adapted to excite the phosphor screen (2) for emitting light (5a, 5c); and wherein the screen (3) comprises a retroreflective layer (3a) which is adapted to reflect light (5a) emitted by the phosphor screen (2).

Description

The present invention relates to a light source assembly, a vehicle headlamp, and a light source assembly manufacturing method.

State of the art

For example, in the automotive industry, there is a need for efficient light sources. One known method for producing a high-power light signal is to make a phosphor screen glow by means of a laser beam. The phosphor screen will generally deliver the radiation isotropically in all spatial directions. From the WO 2010/084451 A1 For example, such a light source is known, wherein a wire grid polarizer is arranged on both sides of the phosphor screen. The wire grid polarizers serve to reduce the temperature at the point where the laser beam strikes the phosphor screen and makes it glow.

Typically, however, only the radiation emitted in the forward direction, that is, in the direction away from the laser, is of practical relevance. So it is lost on average half of the generated light radiation, since it is emitted in the reverse direction, ie in the direction of the laser.

Disclosure of the invention

According to a first aspect, the invention provides a light source arrangement having the features of patent claim 1.

The present invention accordingly provides a light source arrangement which comprises a laser for emitting a light beam and a phosphor screen in the beam path of the laser. A screen is disposed between the laser and the phosphor screen, wherein the screen in the beam path of the laser has at least one opening for passing the light beam emitted by the laser, whereby the light beam emitted by the laser is adapted to excite the phosphor screen to emit light. The screen has a retroreflective layer which is configured to reflect light emitted by the phosphor screen.

According to a further aspect, the invention provides a vehicle headlamp with the features of claim 7. The invention therefore comprises a vehicle headlamp with at least one light source arrangement.

According to a further aspect, the invention provides a production method for a light source arrangement having the features of patent claim 8.

The present invention accordingly provides a production method for a light source arrangement, comprising a first method step of arranging a phosphor screen in the beam path of a laser. Next, a screen between the laser and phosphor screen is arranged. At least one aperture is formed in the screen to transmit a light beam emitted by the laser, whereby a light beam emitted by the laser can impinge on the phosphor screen and excite the phosphor screen to emit light. Further, a retroreflective layer is formed on the screen, which reflects light emitted from the phosphor screen.

Preferred developments are the subject of the respective subclaims.

Advantages of the invention

The retroreflective layer preferably reflects light emitted by the phosphor screen to the radiation source, that is to the excitation point of the phosphor screen. The radiation is in this case either transmitted through the phosphor screen or absorbed by the phosphor screen and the phosphor screen is thereby excited again to shine. Thus, the usable radiation power of the light source arrangement, that is, the total amount of radiation which is ultimately emitted in the forward direction, is increased. The radiation emitted in the reverse direction of the phosphor screen is preferably largely completely reflected by the retroreflective layer, so that the radiation loss is minimized by emitted in the backward direction and non-reflected light.

For example, by increasing the useful radiant power, the number of lasers needed for a vehicle headlamp can be reduced, thereby reducing not only power consumption but also the complexity and cost of the vehicle headlamp.

According to a preferred embodiment of the light source arrangement, the screen is spaced from the phosphor screen by a distance.

According to a preferred development of the light source arrangement, the retroreflective layer comprises triple mirror reflectors. As a result, the reflected light is substantially reflected back to the point of the phosphor screen from which the light was emitted.

According to a preferred development, the light source arrangement comprises a substrate, in particular of glass, wherein the screen and the phosphor screen are arranged on opposite sides on the substrate. The substrate ensures greater stability of the light source arrangement.

According to a preferred development of the light source arrangement, the substrate comprises a wire grid polarizer. The wireframe polarizer also reflects a portion of the incident radiation and thus can further increase the efficiency of the light source assembly.

According to a preferred development of the light source arrangement, the laser is designed as a laser scanner, which is designed to emit the light beam in an angular range, wherein a diameter of the at least one opening of the screen is chosen such that it substantially corresponds to a width of the angular range on the screen , In particular, the at least one opening of the screen is thus made as small as possible, so that that portion of the radiation emitted by the phosphor screen, which passes through the at least one opening in the direction of the laser and is thus not reflected, is minimized. The non-usable radiation is thereby further reduced.

Brief description of the drawings

Show it:

1 a schematic cross-sectional view of a light source assembly according to a first embodiment of the present invention;

2 a schematic cross-sectional view of a light source assembly according to a second embodiment of the present invention;

3 a schematic cross-sectional view of a light source assembly;

4 a schematic cross-sectional view of a light source assembly according to a third embodiment of the present invention;

5 a schematic cross-sectional view of a light source assembly according to a fourth embodiment of the present invention;

6 a schematic cross-sectional view of a vehicle headlamp according to the present invention; and

7 a flowchart for explaining a manufacturing method for a light source assembly according to the present invention.

In all figures, the same or functionally identical elements and devices - unless otherwise stated - provided with the same reference numerals. The numbering of method steps is for the sake of clarity and, in particular, should not, unless otherwise indicated, imply a particular chronological order. In particular, several method steps can be carried out simultaneously.

Description of the embodiments

1 shows a schematic cross-sectional view of a light source arrangement 10 according to a first embodiment of the present invention. The light source arrangement 10 includes a laser 1 for emitting a light beam 4 , The laser 1 In this case, it may in particular be designed to emit blue light or ultraviolet light.

The laser 1 is preferably a laser scanner, which is designed to scan a solid angle range. The laser 1 is aligned to the light beam 4 in a vertical direction in an angular range emit α, in particular by pivoting of micromirrors of the laser. The laser 1 may preferably also be aligned to the light beam 4 in a horizontal direction, which is perpendicular to the plane, emit in an angular range.

In the beam path of the laser 1 there is a phosphor screen 2 that is a screen with at least one phosphor layer. The phosphor layer can be replaced by that from the laser 1 emitted light beam 4 be excited to send out light.

At a distance d ₃ of the phosphor screen is located in the beam path of the laser 1 between lasers 1 and the phosphor screen 2 a screen 3 , The distance d _{3 of} the screen 3 from the phosphor screen 2 may for example be between 5 mm and 40 mm and preferably 20 mm. The screen 3 has at least one opening 9 for passing the light beam emitted by the laser 4 on. A geometry of the opening 9 is hereby arbitrary. Preferably, the opening 9 However, circular. A diameter d _{1 of} the opening 9 of the screen 3 is preferably chosen such that the light beam 4 in the entire angle range α through the opening 9 of the screen 3 can pass through. The diameter d ₁ is preferably chosen to be as small as possible, so that the diameter d ₁ preferably the width of the Angular range α on the screen 3 equivalent. Preferably, in this case also a beam waist d _{2 of} the light beam 4 considered.

Preferably, the laser is 1 centrally in front of a center of the opening 9 arranged. The laser 1 However, it can also be arranged offset.

The one from the laser 1 emitted laser beam 4 can through the opening 9 of the screen 3 get through and at a point of impact 6 on the phosphor screen 2 incident. The phosphor screen 2 will be at the point of impact 6 excited to send out light. By pivoting the laser 1 emitted laser beam 4 in the angular range α can be an area with diameter D on the phosphor screen 2 from the laser 1 be scanned or illuminated, the diameter D preferably between a and 20 Centimeters. However, the invention is not limited thereto. That's how the laser works 1 also an area of any shape on the phosphor screen 2 Scan and thus illuminate.

In the following, a distinction is made between emission of light in a "backward direction" and in a "forward direction". Through the plane, which is the phosphor screen 2 is located, the room is divided into two half-spaces. Transmission of a light beam in the "backward direction" now means that the light beam propagates in the half space in which the laser 1 located. If a ray of light is emitted in the "forward direction", it spreads out into the other half-space in which the laser is located 1 not located.

On the screen 3 is at least one retroreflective layer 3a educated. The retroreflective layer 3a may in particular include triple mirror reflectors. The retroreflective layer 3a however, may also include Lüneburg lenses. The retroreflective layer 3a may in particular include spherical elements with mirrored backs.

The aperture size of individual reflector elements of the triple mirror reflectors can be for example about 100 microns. Is the distance d _{3 of} the screen 3 from the phosphor screen 2 For example, 20 mm, the diameter of an Airy disk is on the phosphor screen 2 about 280 μm. The Airy disk preferably corresponds approximately to the beam waist d _{2 of} the emitted laser beam 4 , All these numerical values have only exemplary character.

A ray of light 5a , which is emitted in the reverse direction, strikes the retroreflective layer of the screen 3 , The retroreflective layer is formed, the light beam 5a essentially along a direction to reflect which of the direction of incidence of the light beam 5a on the retroreflective layer 3a is opposite. Such a reflected light beam 5b So propagates in the direction of the point of impact 6 of the phosphor screen 2 , The reflected light beam 5b can through the phosphor screen 2 be transmitted and then spreads in the forward direction. The reflected light beam 5b can the phosphor screen 2 but also to re-emit light and thereby increase the luminous efficacy.

The total proportion of light radiation ultimately emitted in the forward direction, i. initially emitted in the forward direction of radiation plus reflected radiation, at least 85% of the total light output from the phosphor screen can be estimated. However, this numerical value is only to be understood as an example.

The invention is not limited to said embodiment. In particular, the umbrella can 3 have a plurality of openings.

Further, a plurality of additional optical elements, in particular of lenses in front of and / or behind the phosphor screen 2 be introduced.

In 2 is a second embodiment of a light source arrangement according to the invention 20 illustrated. While according to the first embodiment, the screen 3 from the phosphor screen 2 spaced, that is separated by air, so are according to the second embodiment of the screen 3 and the phosphor screen 2 on opposite sides of a substrate 7 , The substrate 7 may in particular consist of glass or another translucent, that is transparent or translucent material. The phosphor screen 2 and the screen 3 are preferably fixed to the substrate 7 fixed, in particular by gluing or deposition.

3 shows a cross-sectional view of a light source assembly 30 , The light source arrangement 30 includes a laser 1 for emitting a light beam 4 , The laser 1 is preferably a laser scanner, which is adapted to the light beam 4 in a vertical direction in an angular range emit α, in particular by pivoting of micromirrors of the laser. In the beam path of the laser 1 is a phosphor screen 2 educated. The phosphor screen 2 is on a side of a substrate facing away from the laser 7 arranged. The substrate 7 here includes a wire grid polarizer 8th that is an arrangement of parallel metallic wires with good conductivity. The one from the laser 1 emitted light beam 4 is designed to the phosphor screen 2 to the Stimulate emission of light. A ray of light 5c , which is emitted in the reverse direction, in this case at least partially from the wire grid polarizer 8th be reflected. Such a reflected light beam 5d either hits the phosphor screen again 2 and stimulates this to the repeated emission of light or through the phosphor screen 2 transmits and propagates in the forward direction.

That of the phosphor screen 2 emitted light is generally randomly polarized, so has no special polarization direction. The light beam 5c is either transmitted or reflected depending on the polarization of the wire grid polarizer. For example, the transmissivity of p-polarized components for wireframe polarizers at a 45 ° incidence angle may be about 85%. The proportion of the reflected s-polarized components can be estimated to be about 85%. Based on this, it can be expected that at least 60% of the light will ultimately be emitted in the forward direction. These numerical values are only to be understood as examples.

4 shows a cross-sectional view of a light source assembly 40 according to a third embodiment of the present invention. The third embodiment is different from that in FIG 2 shown second embodiment in that in the substrate 7 between the phosphor screen 2 and the screen 3 a wireframe polarizer 8th is formed, analogous to in 3 shown light source arrangement 30 , The wire grid polarizer 8th this can be a light beam 5c , which is emitted in the reverse direction, reflect. Such a reflected light beam 5d is through the phosphor screen 2 transmits or excites the phosphor screen to re-emit light.

5 shows a cross-sectional view of a light source assembly 50 according to a fourth embodiment of the present invention. The fourth embodiment is different from that in FIG 4 shown third embodiment in that the distance d _{3 of} the screen 3 from the phosphor screen 2 is greater than a thickness d _{4 of} the substrate 7 with the wire-duster polarizer 8th , The screen 3 is thus from the substrate 7 spaced.

6 shows a cross-sectional view of a vehicle headlamp 60 with a light source arrangement 10 according to the first embodiment. The vehicle headlight 60 this includes a housing 51 , where the phosphor screen 2 in an opening of the housing 51 is arranged. The phosphor screen 2 is through a cover 52 protected against environmental influences. The cover 52 may further comprise a lens system which is aligned to that of the phosphor screen 2 send out emitted light at certain angles to the outside. The laser 1 is here arranged such that the emitted light beam 4 through the opening 9 of the screen 3 on the phosphor screen 2 and that from the phosphor screen 2 Forward propagating light through the cover 10 through from the vehicle headlight 60 radiates outwards.

The invention is not limited to this, so another embodiment of the light source arrangement for the vehicle headlight 60 be used.

7 FIG. 12 is a flowchart for explaining a manufacturing method of a light source device according to the present invention. FIG.

In a first method step S1, a phosphor screen 2 in the beam path of a laser 1 , in particular a laser scanner, arranged. The laser 1 may preferably be adapted to a Lichstrahl 4 emit in an angular range α. In a second method step S2 is between the laser 1 and the phosphor screen 2 a screen 3 arranged. In the screen 3 at least one opening is made in a third step S3 9 for passing one of the laser 1 emitted light beam 4 educated. Preferably, in this case, a plurality of openings in the screen 3 educated. A diameter d _{1 of} the opening 9 of the screen 3 In this case, it preferably corresponds essentially to a beam waist d ₂ of the laser 1 emitted light beam 4 , The one from the laser 1 emitted light beam 4 can pass through at least one of the openings and onto the phosphor screen 2 at a point of impact 6 incident. This will make the phosphor screen 2 excited to send out light.

In a fourth method step S4 becomes a retroreflective layer 3a on the screen 3 educated. The retroreflective layer 3a is here formed such that one of the phosphor screen 2 in the backward direction emitted light on the retroreflective layer 3a meet and be reflected there.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2010/084451 A1 [0002]

Claims (8)

Light source arrangement ( 10 . 20 . 40 . 50 ), with: a laser ( 1 ) for emitting a light beam ( 4 ); a phosphor screen ( 2 ) in the beam path of the laser ( 1 ); a screen ( 3 ), which between laser ( 1 ) and phosphor screen ( 2 ), wherein the screen ( 3 ) in the beam path of the laser ( 1 ) at least one opening for passing the laser ( 1 ) emitted light beam ( 4 ), whereby the laser ( 1 ) emitted light beam ( 4 ) is adapted to the phosphor screen ( 2 ) for emitting light ( 5a . 5c ) to stimulate; and where the screen ( 3 ) a retroreflective layer ( 3a ), which is formed by the phosphor screen ( 2 ) emitted light ( 5a ) to reflect. Light source arrangement ( 10 . 20 . 40 . 50 ) according to claim 1, wherein the screen ( 3 ) of the phosphor screen ( 2 ) is spaced by a distance (d ₃ ). Light source arrangement ( 10 . 20 . 40 . 50 ) according to one of claims 1 or 2, wherein the retroreflective layer ( 3a ) Comprises triple mirror reflectors. Light source arrangement ( 20 . 40 . 50 ) according to one of claims 1 to 3, with a substrate ( 7 ), in particular of glass, the screen ( 3 ) and the phosphor screen ( 2 ) on opposite sides of the substrate ( 7 ) are arranged. Light source arrangement ( 40 . 50 ) according to claim 4, wherein the substrate ( 7 ) a wireframe polarizer ( 8th ). Light source arrangement ( 10 . 20 . 40 . 50 ) according to one of claims 1 to 5, wherein the laser ( 1 ) is designed as a laser scanner, which is adapted to the light beam ( 4 ) emit in an angular range α; and wherein a diameter (d ₁ ) of the at least one opening of the screen ( 3 ) is selected such that it is substantially a width of the angular range α on the screen ( 3 ) corresponds. Vehicle headlights ( 60 ) with at least one light source arrangement ( 10 . 20 . 40 . 50 ) according to one of claims 1 to 6. Production method for a light source arrangement ( 10 . 20 . 40 . 50 ), with the steps: arranging (S1) a phosphor screen ( 2 ) in the beam path of a laser ( 1 ); Arranging (S2) a screen ( 3 ) between lasers ( 1 ) and phosphor screen ( 2 ); Forming (S3) at least one opening in the screen ( 3 ) for passing one of the laser ( 1 ) emitted light beam ( 4 ), whereby one of the laser ( 1 ) emitted light beam ( 4 ) on the phosphor screen ( 2 ) and the phosphor screen ( 2 ) for emitting light ( 5a . 5c ) can stimulate; and forming (S4) a retroreflective layer ( 3a ) on the screen ( 3 ) for reflecting from the phosphor screen ( 2 ) emitted light ( 5a ).

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