Lighting apparatus

Abstract

A lighting apparatus may include a light generating device for generating a primary light beam, a phosphor body that can be irradiated by means of the primary light beam and serves for partly converting primary light of the primary light beam into secondary light, and a spectral filter disposed downstream of the phosphor body. The spectral filter may be more highly transmissive to the secondary light than to the primary light where the spectral filter is arranged along a beam axis of the primary light beam incident on the phosphor body. The lighting apparatus may be used in LARP arrangement for vehicle lighting, general lighting, exterior lighting, stage lighting, effect lighting, etc.

Claims

1. An illumination apparatus, comprising a light generation device for generating a primary light beam, a phosphor body configured to be irradiated using the primary light beam, for partially converting primary light of the primary light beam into secondary light, and a spectral filter connected downstream from the phosphor body and configured to be more strongly transmissive for the secondary light than for the primary light, wherein the spectral filter is arranged along a beam axis of the primary light beam that is incident on the phosphor body, and the spectral filter (2) covers the entire primary-light-dominated region of a light emission pattern of the phosphor body (105); and further comprising a light sensor (4) arranged such that primary light (P) incident on the spectral filter (2) is able to be reflected into the light sensor (4); and wherein the spectral filter (2) is applied on a side (6) of the transmitted-light element (107) that faces away from the phosphor body (105); the primary light (P) is able to be reflected by the spectral filter (2) through the transmitted-light element (107) to a side (3) that faces the phosphor body (105); and the side (3) that faces the phosphor body (105) in the region of the reflected primary light (P) takes the form of a TIR-free region.

2. The illumination apparatus as claimed in claim 1, wherein the beam axis extends centrally through the spectral filter.

3. The illumination apparatus as claimed in claim 1, wherein the spectral filter is a dichroic mirror.

4. The illumination apparatus as claimed in claim 1, wherein the illumination apparatus has a control device coupled to the light sensor and the light generation device and is set up to evaluate a measurement signal of the light sensor with respect to damage of the phosphor body and to reduce a luminous flux of the primary light beam emitted by the light generation device upon detection of damage.

5. The illumination apparatus as claimed in claim 1, wherein the spectral filter is arranged on a transmitted-light element connected optically downstream from the phosphor body.

6. The illumination apparatus as claimed in claim 5, wherein the transmitted-light element is an imaging transmitted-light element and the spectral filter is arranged in an intermediate image plane.

7. The illumination apparatus as claimed in claim 1, wherein the spectral filter has a diameter between 100 m and 300 m.

8. The illumination apparatus as claimed in claim 1, wherein the light generation device has at least one semiconductor laser and the phosphor body is arranged at a distance from the at least one semiconductor laser.

9. The illumination apparatus as claimed in claim 1, wherein the illumination apparatus is a headlight or a spotlight.

10. The illumination apparatus as claimed in claim 1, wherein the illumination apparatus is a vehicle illumination apparatus.

11. The illumination apparatus as claimed in claim 1, wherein a surface of the spectral filter that is projected along the beam axis corresponds to the shape of a primary-light-dominated central region of the emission.

12. The illumination apparatus as claimed in claim 1, wherein a primary-light-dominated central region of the emission is completely covered by the surface of the spectral filter that is projected along the beam axis.

13. The illumination apparatus as claimed in claim 3, further comprising a light sensor arranged such that primary light incident on the dichroic mirror is able to be reflected into the light sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the illumination apparatus. In the following description, various aspects are described with reference to the following drawings, in which:

(2) FIG. 1 shows a side view as a sectional representation of a LARP illumination apparatus without a spectral filter;

(3) FIG. 2 shows a profile of a luminance of the primary light beam and of a sum color location of the useful light along an angle section that is symmetrical with respect to the beam axis;

(4) FIG. 3 shows a view along a beam axis of a light emission pattern of the useful light of the LARP illumination apparatus from FIG. 1;

(5) FIG. 4 shows a side view as a sectional representation of a first LARP illumination apparatus with a spectral filter;

(6) FIG. 5 shows a side view as a sectional representation of a second LARP illumination apparatus with a spectral filter; and

(7) FIG. 6 shows a side view as a sectional representation of a third LARP illumination apparatus with a spectral filter.

DETAILED DESCRIPTION

(8) FIG. 1 shows a sectional representation of a LARP illumination apparatus 101 without a spectral filter.

(9) The LARP illumination apparatus 101 has a light generation device in the form of a laser diode 102 for generating a (primary light) beam B of blue primary light P. Two lenses 103 and 104 for beam-shaping the primary light beam B are connected optically downstream of the laser diode 102. The primary light beam B is incident on a phosphor body in the form of a converting ceramic plate 105, specifically along a beam axis A.

(10) The ceramic plate 105 can be applied on a carrier 106 made of transparent sapphire, glass etc. The ceramic plate 105 is used to convert some of the primary light P into yellow secondary light S. Emitted by the ceramic plate 105 is consequently blue-yellow, or white, mixed light having a portion of primary light P and a portion of secondary light S as useful light P, S. A transmitting arrangement is present here, in which the useful light P, S is emitted by a side of the ceramic plate 105 that faces away from the laser diode 102. However, in principle a reflecting arrangement may also be used, in which the useful light P, S is emitted by the same side of the ceramic plate 105 on which the primary light P, or the primary light beam B, is also incident (the ceramic plate 105 can in that case be applied, e.g., on a reflective carrier). The useful light P, S can be beam-shaped, e.g., collimated, by a further beam-shaping transmitted-light element, here in the form of a further lens 107. The components 102 to 107 can be components of a LARP module N.

(11) FIG. 2 shows a profile of a luminance Lv of the primary light beam B and of a sum color location Cx of the useful light P, S on a light exit surface of the ceramic plate 105 along a direction x perpendicular to the optical beam axis A. This yellow-blue spatial region can have different extents in different directions perpendicular to the optical beam axis A, with the result that an elliptical color profile is obtained for example in the exit plane of the ceramic plate 105. However, the color profile can also be rotation-symmetrical with respect to the beam axis A, as is illustrated in FIG. 3. The beam axis A is incident centrally on the spatial region shown.

(12) The luminance Lv has a maximum at the location of the beam axis A and decreases as the distance from it increases. The sum color location Cx of the useful light P, S has a blue hue in a first section including the beam axis A (central section S1). That means that the portion of the blue primary light P is here so high that the sum color location Cx is situated outside a neutral white color band C1, specifically in the direction of the color location of the primary light P, i.e., shifted to blue.

(13) This is followed toward the outside, or with increasing distance x from the optical beam axis A, by a neutral section S2, in which the sum color location Cx is in the neutral white color band C1. With even more distance from the beam axis A, here in an external section S3, the sum color location Cx has a yellow hue. That means that the portion of the yellow secondary light S is here so high that the sum color location Cx has shifted to yellow and is situated outside the neutral white color band C1.

(14) The transitions between the region S1, S2 and S3 are not abrupt or in the shape of steps, but exhibit a gradual transition that depends on the beam profile of the primary light P and the properties of the converting ceramic plate 105, such as, e.g., the phosphor concentration thereof and distribution of possible scatter regions.

(15) FIG. 3 shows a rotation-symmetrical light emission pattern of the useful light P, S of the LARP illumination apparatus 101, which is centered around the beam axis A, without a spectral filter, specifically on the exit side of the converting ceramic plate 105 in a view along the beam axis A in a plane perpendicular to the beam axis A. A central region K1, which corresponds to the central section S1 in FIG. 2, is here configured in the shape of a circle and centered around the central axis A. The central region K1 is surrounded by an annular neutral region K2 which corresponds to the neutral section S2. The neutral region K2 in turn is surrounded by an annular external region K3 which corresponds to the external section S3. Generally, the color profile, or the light emission pattern, on the exit side of the conversion element can be oval or elliptical.

(16) FIG. 4 shows a side view as a sectional representation of a first LARP illumination apparatus 1, with a construction similar to the LARP illumination apparatus 101, but now additionally with a spectral filter in the form of a dichroic mirror 2. The dichroic mirror 2 is more strongly transmissive for the yellow secondary light S than for the blue primary light P.

(17) The dichroic mirror 2 is mounted on the further lens 107, specifically on a side 3 that faces the laser diode 102. The dichroic mirror 2 is arranged here along the beam axis A, specifically such that it substantially completely covers the primary light P emitted by the central region S1 (and possibly also a small part of the primary light emitted by the neutral region S2), as is stated in FIG. 2 for the spatial region. The dichroic mirror 2 to this end has an oval or circularly round shape and is inclined with respect to the beam axis A such that its surface that is projected along the beam axis A corresponds to the shape of the central region K1. The surface of the dichroic mirror 2 that is projected along the beam axis A has a specified diameter d, as is also indicated in FIG. 2. This diameter d is selected such that the primary-light-dominated (spatial or solid angle) region is entirely covered and possiblyas illustrated in FIG. 2even goes slightly beyond it. The diameter d can be for example at least between 100 m and 300 m. However, the regions K1, K2 and/or K3 can alternatively have a non-circularly round shape, e.g., be elongated, for example elliptical. The dichroic mirror 2 may be arranged at a small distance from the converting ceramic plate 105, for example in the region of a few millimeters.

(18) Consequently, the blue primary light P is attenuated downstream of the dichroic mirror 2. If a ceramic plate 105 that is not damaged (indicated here by dots) is present, the portion of the primary light P in the useful light P, S is consequently reduced in the central region K1, specifically in a manner such that the useful light here has a sum color location in the neutral white color band C1. With reference to FIG. 2, this is indicated by the dotted line L.

(19) However, if the ceramic plate 105 is damaged or has even fallen off the carrier 106, the primary light beam P is incident on the dichroic mirror 2 with its greatest luminance and is reflected by said mirror into a light sensor 4. This offers the advantage of improved eye safety, because the primary light P can leave the illumination apparatus 1 only in a strongly attenuated state.

(20) In addition, a strongly increased incident luminous flux is ascertained by the light sensor 4 in the case of a ceramic plate 105 that is damaged or has fallen off, as a result of which the existence of damage (including falling off of the ceramic plate 105) is reliably ascertainable. Due to the fact that damage has been ascertained, the primary light beam B can be dimmed, for example, or entirely switched off, e.g., using a control device (not illustrated) which is coupled or connected both to the laser diode 102 and to the light sensor 4.

(21) This illumination apparatus 1 can represent a headlight/spotlight or part thereof (for example a LARP module M), in particular a headlight for a vehicle.

(22) FIG. 5 shows a side view as a sectional representation of a second LARP illumination apparatus 5 with the dichroic mirror 2. The LARP illumination apparatus 5 is similar in design to the LARP illumination apparatus 1, although here, the dichroic mirror 2 is attached to a side 6 of the further lens 107 which faces away from the ceramic plate 105. At least the primary light P emitted by the central core region K1 is able to be reflected back by the dichroic mirror 2 through the lens 107 to the side 3 that faces the ceramic plate 105. On an incidence region of the back-reflected primary light P, the side 6 is formed as a TIR-free region 7.

(23) FIG. 6 shows a side view as a sectional representation of a third LARP illumination apparatus 8 with the dichroic mirror 2. The LARP illumination apparatus 8 can be configured in the form of a vehicle headlight with a LARP module N as per FIG. 1, connected downstream of which is a transmitted-light element in the form of a front-side cover plate 9. The LARP illumination apparatus 8 is similar in design to the LARP illumination apparatus 1 or 4, wherein the dichroic mirror 2 is now attached to the cover plate 9. The cover plate 9, the dichroic mirror 2 and the light sensor 4 here do not represent components of the LARP module N.

(24) Although the illumination apparatus has been further illustrated and described in detail by way of the non-limiting embodiments shown, the illumination apparatus is not limited thereto, and other variations can be derived herefrom by a person skilled in the art without departing from the scope of protection of the illumination apparatus.

(25) For example, in a further non-limiting embodiment, instead of the lens 107, an imaging lens system, for example in non-limiting embodiment that images 1:1, may be present, which produces an intermediate image of the spot profile located on the focal plane (luminance and color distribution) of the emission surface of the converting ceramic plate 105. The dichroic mirror 2 is then arranged in an intermediate image plane on the optical beam axis A inclined with respect to said beam axis A, with the result that the light reflected by the dichroic mirror 2 is incident on a sensor 4 which is arranged at a distance, as is shown analogously in FIG. 5a.

(26) Generally, in addition to a ceramic plate 105, another wavelength-changing conversion body may also be present.

(27) Generally, a or an can be understood to mean a singular or a plural, in particular in the sense of at least one or one or more etc., unless this is explicitly ruled out, e.g. by the expression exactly one etc.

(28) A mention of a number may also include both the stated number and a customary tolerance range, unless this is explicitly ruled out.

(29) While specific aspects have been described, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the aspects of this disclosure as defined by the appended claims. The scope is thus indicated by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced.

LIST OF REFERENCE SIGNS

(30) LARP illumination apparatus 1 Dichroic mirror 2 Side 3 Light sensor 4 LARP illumination apparatus 5 Side 6 TIR-free region 7 LARP illumination apparatus 8 Cover plate 9 LARP illumination apparatus 101 Laser diode 102 Lens 103 Lens 104 Ceramic plate 105 Carrier 106 Lens 107 Beam axis A Primary light beam B Neutral white color band C1 Sum color location Cx Diameter d Central region K1 Neutral region K2 External region K3 Luminance Lv LARP module M LARP module N Primary light P Secondary light S Central section S1 Neutral section S2 External section S3 Angle