CN212481157U

CN212481157U - Light emitting module

Info

Publication number: CN212481157U
Application number: CN202021004687.3U
Authority: CN
Inventors: 曾根秀伦; 前野雄壮
Original assignee: Koito Manufacturing Co Ltd
Current assignee: Koito Manufacturing Co Ltd
Priority date: 2019-06-14
Filing date: 2020-06-04
Publication date: 2021-02-05
Anticipated expiration: 2030-06-04
Also published as: WO2020250757A1; CN112082132A; JPWO2020250757A1; CN112082132B

Abstract

The utility model provides a can reduce the new technology that has the possibility that laser of higher energy density spills to the outside not by the scattering. The light emitting module includes: a light emitting element that emits laser light; a wavelength conversion member that emits converted light obtained by wavelength-converting the laser light; and a detection unit (26) that is fixed to the wavelength conversion member and detects the amount of displacement of the wavelength conversion member. The detection unit (26) contains a piezoelectric material that outputs an electrical signal that changes in accordance with the amount of displacement of the wavelength conversion member.

Description

Light emitting module

Technical Field

The present invention relates to a light emitting module using a light emitting element emitting light with a high energy density as a light source.

Background

In recent years, among various lamps that need to illuminate a farther distance, there has been proposed a lamp using laser light as a light source. Since the light emitted from the laser is coherent light and has a very high energy density, the following consideration is required: the laser light having a high energy density emitted from the laser does not leak out of the lamp. Further, a light emitting module has been proposed which generates white light by combining a light source which emits blue laser light and a fluorescent material which converts the blue laser light into light of another color (for example, yellow).

In such a light emitting module, since the laser light is scattered when passing through the phosphor, the laser light having a high energy density at the time of laser light emission does not leak out of the lamp in a normal state. However, when the phosphor is broken or falls off from a predetermined position, there is a possibility that the laser light may leak out of the lamp without being scattered. Therefore, a technique has been proposed in which an electrode is attached to a phosphor, an abnormality such as a crack in the phosphor is detected from a change in resistance between the electrodes when the crack or the notch is present in the phosphor, and a laser beam is turned off (see patent document 1).

[ Prior art documents ]

[ patent document ]

Patent document 1: german patent application publication No. 102016112691

SUMMERY OF THE UTILITY MODEL

[ problems to be solved by the utility model ]

However, in the above-described technique, since an abnormality cannot be detected when there is actually no crack or the like in the phosphor, the laser light leaking during a period from the start of the crack or the like in the phosphor to the turning off of the laser light cannot be set to zero.

The present invention has been made in view of such a situation, and an exemplary object of the present invention is to provide a novel technique for reducing the possibility that laser light having a high energy density leaks to the outside without being scattered.

[ means for solving the problems ]

In order to solve the above problem, the light emitting module according to an aspect of the present invention includes: a light emitting element that emits laser light; a wavelength conversion member that emits converted light obtained by wavelength-converting the laser light; and a detection unit that is fixed to the wavelength conversion member and detects the amount of displacement of the wavelength conversion member. The detection portion includes a piezoelectric material that outputs an electric signal that changes in accordance with the amount of displacement of the wavelength conversion member.

According to this aspect, it is possible to estimate in advance whether or not the wavelength converting member is as damaged by detecting the amount of displacement of the wavelength converting member with the piezoelectric material. Further, the displacement amount of the wavelength conversion member can be detected with a simple configuration.

The piezoelectric material may be a transparent film configured to: covering at least one of an emission surface of the wavelength conversion member from which the converted light is emitted and an incident surface of the wavelength conversion member on which the laser light is incident. This makes it possible to dispose the piezoelectric material in a region of the wavelength conversion member through which the laser beam is transmitted, and to detect cracks or the like in the incident surface or the emission surface of the wavelength conversion member.

The piezoelectric material may have a curie point of 300 ℃ or higher, or may have no curie point. Thus, even if the light emitting module is at a high temperature, it can be estimated in advance whether or not the wavelength conversion member is damaged.

The wavelength conversion member may be a ceramic phosphor. Thereby, the wavelength conversion member can be integrally formed with the detection portion (e.g., piezoelectric material).

In addition, any combination of the above-described constituent elements and the result of conversion of the expression of the present invention between a method, an apparatus, a system, and the like are also effective as aspects of the present invention.

[ effects of utility model ]

According to the utility model discloses, can reduce the possibility that the laser that has higher energy density spills to the outside not by the scattering.

Drawings

Fig. 1 is a schematic diagram showing a schematic configuration of a vehicle headlamp unit according to the present embodiment.

Fig. 2 is a cross-sectional view showing a schematic configuration of the light-emitting module of the present embodiment.

Fig. 3 is a cross-sectional view schematically showing the vicinity of the detection unit of the light-emitting module according to the present embodiment.

Fig. 4 is a plan view schematically showing the vicinity of the detection unit of the light emitting module according to the present embodiment.

Fig. 5 is a plan view schematically showing the vicinity of the detection unit of the light-emitting module according to the modification of the present embodiment.

Fig. 6 is a plan view schematically showing the vicinity of the detection unit of a light-emitting module according to another modification of the present embodiment.

Detailed Description

The present invention will be described below based on embodiments with reference to the drawings. The same or equivalent constituent elements, members, and processes shown in the respective drawings are denoted by the same reference numerals, and overlapping descriptions are appropriately omitted. The embodiments are not intended to limit the invention, and are merely examples, and all the features and combinations described in the embodiments are not necessarily essential to the invention.

(vehicle lamp)

First, a vehicle lamp using the light emitting module of the present embodiment will be described. The vehicle lamp is, for example, a vehicle headlamp unit that can illuminate the front of a vehicle to a distant place with a light source that emits light with high energy density. Fig. 1 is a schematic diagram showing a schematic configuration of a vehicle headlamp unit according to the present embodiment.

The vehicular headlamp unit 10 includes: a light emitting module 12; and a reflector 14 having a reflection surface 14a that reflects light L1 emitted by the light emitting module 12 toward the front of the vehicle.

The reflecting surface 14a of the reflector 14 constitutes a parabolic optical system having a parabolic shape and reflecting the light L1 incident from below as parallel light toward the front of the vehicle. The light emitting module 12 is disposed so that a position from which light is emitted is near the focal point F. The vehicle headlamp unit 10 may include an optical system in which a reflecting surface of the reflector is formed in a complex ellipsoid (polytopicoid) shape.

(light emitting module)

Fig. 2 is a cross-sectional view showing a schematic configuration of the light-emitting module of the present embodiment. The light emitting module 12 has: a semiconductor light emitting element 18 that emits blue laser light; a substrate 20 on which the semiconductor light-emitting element 18 is mounted; and a case 22 that houses the semiconductor light emitting element 18 so that the laser light L0 emitted by the semiconductor light emitting element 18 is not emitted in an unintended direction.

The semiconductor light-emitting element 18 preferably emits a laser beam having a peak wavelength of 380 to 480nm, and is, for example, an element that emits a blue laser beam (peak wavelength of about 450 nm) or a near ultraviolet laser beam (peak wavelength of about 405 nm). The substrate 20 may also serve as a heat dissipation member.

The case 22 is made of a material that does not transmit laser light therethrough, and has an opening 22a formed in an upper portion thereof. A fluorescent material 24 as a wavelength conversion member that emits converted light obtained by converting the wavelength of the laser light is fixed to the opening 22 a. The phosphor 24 is a plate-like member made of Yttrium Aluminum Garnet (YAG: Yttrium Aluminum Garnet) ceramic into which an activator such as cerium (Ce) is introduced, for example.

The light emitting module 12 emits white light L1 by mixing a blue laser beam emitted from the semiconductor light emitting element 18, for example, and a converted light of yellow, for example, which is emitted from the fluorescent material 24 excited by the blue laser beam and has undergone wavelength conversion. By mixing the blue laser light scattered by the fluorescent material 24 with the yellow wavelength converted light of the lambertian light distribution, the white light L1 becomes a high-luminance light having a certain width.

The light emitting module 12 of the present embodiment further includes a detection unit 26, and the detection unit 26 is fixed to the fluorescent material 24 and detects the amount of displacement of the fluorescent material 24. The detection unit 26 is configured to: an electric signal that changes in accordance with the amount of displacement of the phosphor 24 is output.

Fig. 3 is a cross-sectional view schematically showing the vicinity of the detection unit of the light-emitting module according to the present embodiment. Fig. 4 is a plan view schematically showing the vicinity of the detection unit of the light emitting module according to the present embodiment.

As shown in fig. 3, the case 22 includes a holding portion 22b, and the holding portion 22b is an insulating material surrounding the fluorescent material 24 fitted into the opening 22 a. The holding portion 22b may be made of a ceramic material, for example. Thereby, the fluorescent material 24 is held and fixed to the case 22. The detection section 26 is fixed to the emission surface 24a side of the fluorescent material 24. The detection unit 26 includes: a wiring pattern 28 disposed on the surfaces of the holding portion 22b and the phosphor 24; wires 30 connected to both ends of the wiring pattern 28; and a voltage detector 32 connected to the electric wire 30.

In the wiring pattern 28, a transparent conductive film 28a as an electrode formed on the emission surface 24a of the phosphor 24 and the surface 22c of the holding portion 22b, and a piezoelectric material 28b which generates a voltage when a mechanical strain (stress) occurs are formed in a layered manner. The transparent conductive film 28a is preferably made of conductive Indium Tin Oxide (ITO). Thus, even if the wiring pattern 28 is formed on the emission surface 24a of the phosphor 24, the light transmission is not hindered, and thus, the light extraction efficiency of the entire light emitting module 12 can be suppressed from being lowered.

The piezoelectric material 28b is, for example, a zinc oxide (ZnO) thin film having a thickness of about 3 μm. The piezoelectric material 28b preferably has a curie point of 200 ℃ or higher (or 300 ℃ or higher) or does not have a curie point, such as ZnO. This is because the piezoelectric material 28b may be heated by heat generated when the phosphor 24 is excited by the laser light L0, and when the curie point is low, the piezoelectric property is not exhibited.

When the phosphor 24 is YAG ceramic, the linear expansion coefficient is 8[ 10-6/. degree.C ]. Therefore, in the case of the phosphor 24 having a thickness of about 300 μm, the displacement amount at a temperature change Δ T of 150 ℃ is 8[ 10-6/° c ] × 150 ℃ × 300 μm, which is 0.36 μm. On the other hand, when a tensile load is applied to YAG ceramics, the YAG ceramics will break at an elongation of about 4%. Therefore, in the case of the phosphor 24 of YAG ceramic having a thickness of 300 μm, when the elongation of about 12 μm is generated in the thickness direction by the tensile load, the phosphor is broken.

Thus, the difference between the amount of displacement (for example, 0.36 μm) due to thermal expansion of the YAG ceramic and the amount of displacement (12 μm) at which the fracture occurs due to the tensile load is 30 times or more, and it is possible to estimate in advance whether or not the phosphor is damaged by detecting the amount of displacement of the phosphor.

The piezoelectric material 28b of the present embodiment is a ZnO thin film having a thickness of 3 μm, and since the linear expansion coefficient of ZnO is 3.2 to 3.9[ 10-6/deg.c ], the displacement amount at a temperature change Δ T of 150 deg.c is 3.2 to 3.9[ 10-6/deg.c ] × 150 deg.c × 3 μm, which is 0.00144 to 0.00176 μm. Similarly, in the case of a lead zirconate titanate (PZT) thin film having a thickness of 3 μm, since the linear expansion coefficient of PZT is 2 to 4[ 10-6/DEG C ], the displacement amount at a temperature change Δ T of 150 ℃ is 3.2 to 3.9[ 10-6/DEG C ] × 150℃ × 3 μm, which is 0.0009 to 0.0018 μm.

Here, regarding the relationship between the displacement amount and the voltage of the piezoelectric film made of PZT, the voltage generated by the displacement of about a factor μm to 10 μm is in the range of several tens V to several hundreds V, and can be sufficiently detected by the general voltage detector 32. That is, when the voltage detector 32 detects a large voltage corresponding to a displacement (for example, a displacement of about 1 to 10 μm) that is larger than the thermal expansion of the fluorescent material 24 and smaller than the displacement at which the breakage occurs, the control unit 34 (see fig. 3) determines that the fluorescent material 24 is in a state of being damaged, and stops the driving of the semiconductor light emitting element 18. The control unit 34 is formed by appropriately combining an arithmetic device, a drive circuit, and a memory circuit, for example.

As described above, the light emitting module 12 of the present embodiment can estimate in advance whether or not the fluorescent material 24 is damaged by detecting the displacement amount of the fluorescent material 24. Further, by using the piezoelectric material 28b in a part of the detection section 26, the displacement amount of the fluorescent material 24 can be detected with a simple configuration. Further, by using a material having a curie point of 200 ℃ or higher (or 300 ℃ or higher) or having no curie point such as ZnO as the piezoelectric material 28b, it can be estimated in advance whether or not the phosphor 24 is damaged even when the light-emitting module 12 is at a high temperature.

The detection section 26 can be formed integrally with the fluorescent body 24 by laminating the transparent conductive film 28a and the piezoelectric material 28b on the fluorescent body 24 made of a ceramic material of the same material.

Further, ZnO constituting the piezoelectric material 28b is a transparent thin film configured to: covering the exit surface 24a from which the light L1 converted by the phosphor 24 exits. This allows the piezoelectric material 28b to be disposed in the region (emission surface 24a) of the fluorescent material 24 through which the laser beam is transmitted, thereby allowing detection of cracks or the like in the emission surface 24a of the fluorescent material 24. The detection unit 26 similar to the present embodiment may be provided on the incident surface 24b side of the fluorescent material 24. This allows detection of cracks or the like in the incident surface 24b of the fluorescent material 24.

Further, as shown in fig. 4, the detection unit 26 of the present embodiment has a part of the zigzag wiring pattern 28 existing on the boundary region R1 between the fluorescent material 24 and the holding portion 22 b. Therefore, if the fluorescent material 24 is supposed to fall off from the holding portion 22b, the amount of displacement of the piezoelectric material 28b included in a part of the wiring pattern 28 changes rapidly, and is detected by the voltage detector 32 as a large voltage change before the wiring pattern 28 is disconnected.

(modification example)

Unlike the detection unit 26 shown in fig. 4, the light emitting module 36 shown in fig. 5 includes a detection unit 40, and the detection unit 40 has a wiring pattern 38 formed only on the emission surface 24a of the phosphor 24. Accordingly, when the fluorescent material 24 is displaced, the wiring patterns 38 are also displaced, and therefore the amount of displacement of the fluorescent material 24 can be detected with high accuracy by the voltage detector 32. In the detection section 40, most of the wiring pattern 38 is present above the boundary region R2 between the emission surface 24a of the fluorescent material 24 and the holding section 22 b. Further, since the wiring pattern 38 can be shortened, the material cost for forming the detection portion can be reduced.

In the detection unit 40, as shown in fig. 5, most of the wiring pattern 38 in the zigzag shape is present on the boundary region R2 between the fluorescent material 24 and the holding unit 22 b. Therefore, if the fluorescent material 24 is supposed to fall off from the holding portion 22b, the amount of displacement of the piezoelectric material 28b included in most of the wiring patterns 38 changes rapidly, and is detected by the voltage detector 32 as a large voltage change before the wiring patterns 28 are disconnected.

Unlike the detection unit 26 and the detection unit 40, the light emitting module 42 shown in fig. 6 does not have a wiring pattern 44 formed on the emission surface 24a of the phosphor 24. That is, most of the wiring pattern 44 is formed only on the surface 22c of the case 22. Therefore, the light emitted from the emission surface 24a of the phosphor 24 is not obstructed.

In addition, when the holding portion 22b is made of a ceramic material such as alumina (linear expansion coefficient 7.2[ 10-6/. degree. C. ]), there is a possibility that it will break due to thermal expansion, as in the case of YAG ceramics. Even when the holding portion 22b is broken (cracked), and the fluorescent material 24 is dropped or broken, the voltage detector 32 detects a large voltage change before the wiring pattern 44 is broken. That is, the state of the holding portion 22b is detected, whereby the falling or breaking of the fluorescent material 24 can be indirectly detected.

While the present invention has been described above with reference to the above embodiments, the present invention is not limited to the above embodiments, and the present invention is also intended to include the results of appropriate combinations and substitutions of the components of the embodiments. Further, the order of combination and processing in the embodiments may be changed as appropriate based on the knowledge of those skilled in the art, or various modifications such as design changes may be added to the embodiments, and the embodiments to which such modifications are added may be included in the scope of the present invention.

[ description of reference numerals ]

A 10-vehicle headlamp unit, a 12-light emitting module, an 18-semiconductor light emitting element, a 22 casing, a 22a opening, a 22b holding portion, a 24-phosphor, a 24a emission surface, a 24b incidence surface, a 26-detection portion, a 28-wiring pattern, a 28 a-transparent-conductive film, a 28 b-piezoelectric material, a 32-voltage detector, and a 34-control portion.

Claims

1. A light emitting module, comprising:

a light-emitting element which emits a laser beam,

a wavelength conversion member that emits converted light obtained by wavelength-converting the laser light, and

a detection unit that is fixed to the wavelength conversion member and detects a displacement amount of the wavelength conversion member;

the detection unit includes a piezoelectric material that outputs an electric signal that changes according to the amount of displacement of the wavelength conversion member.

2. The lighting module of claim 1,

the piezoelectric material is a transparent thin film configured to: covering at least one of an emission surface of the wavelength conversion member from which the converted light is emitted and an incident surface of the wavelength conversion member on which the laser light is incident.

3. Light emitting module according to claim 1 or 2,

the piezoelectric material has a Curie point of 300 ℃ or higher or does not have a Curie point.

4. Light emitting module according to claim 1 or 2,

the wavelength conversion member is a ceramic phosphor.

5. The lighting module of claim 3,

the wavelength conversion member is a ceramic phosphor.