KR102127968B1 - lighting device - Google Patents

Abstract

It relates to a lighting device.
The illumination device includes a light source that emits excitation light, an optical filter that selectively transmits at least a portion of the excitation light, a holographic optical element that controls the energy distribution of the excitation light emitted from the optical filter, and the holographic optical element. It includes a light conversion member for converting the wavelength of the excitation light emitted.

Description

Lighting device

The present invention relates to an illumination device, and relates to an illumination device that converts and outputs excitation light into visible light.

A luminous element is a device that converts electricity into light. Typical light emitting devices include light emitting diodes (LEDs), laser diodes (LDs), and lasers.

Recently, as demands for high-efficiency and low-power lighting devices have increased, research into lighting devices using lasers, LDs, and high-power light-emitting diodes (High-Power LEDs) as light sources has been conducted.

In particular, in the field of vehicles where energy saving is a hot topic, attempts have been made to convert light sources used in headlamps to lasers, LDs, or high power LEDs. These lasers, LDs or high power LEDs emit excitation light with a wavelength of 500 nm or less. When excitation light having a wavelength of 500 nm or less is exposed to the human body, it may have a detrimental effect on the human body, such as vision impairment and burns. Therefore, a lighting device using a laser, LD, or high-power LED as a light source needs to further include a conversion device that converts excitation light such as a phosphor into visible light.

On the other hand, lasers and LDs in which a large amount of light energy is concentrated in a narrow area have a small area where excitation light reacts with the phosphor, and accordingly, a lot of light energy is concentrated in a narrow area, resulting in a reliability problem that the phosphor is deteriorated or deteriorated. In order to prevent such a problem, a diffuser, a beam shaper, an optical fiber, etc. are used to disperse the light energy emitted from the laser or LD into a large area. However, the use of diffusers, beam shapers, optical fibers, etc., can limit the design of the lighting device.

Even when the intensity of the incident light is high, there is a limitation in converting it to white light, and the conversion efficiency of light uniformly incident on a large area tends to be higher than light locally incident on one part.

Light not converted by the phosphor acts as a loss of the lighting device. In order to reduce the loss, a method of increasing the density of the phosphor to improve the conversion efficiency for high intensity incident light may be used, but it is difficult to satisfy the color temperature, color coordinate, etc. required by the lighting device.

The technical problem to be achieved by the present invention is to provide an illumination device that converts and outputs excitation light into visible light.

According to an embodiment of the present invention, the lighting device includes a light source that emits excitation light, an optical filter that selectively transmits at least a portion of the excitation light, and a holographic optical element that controls energy distribution of excitation light emitted from the optical filter And, it includes a light conversion member for converting the wavelength of the excitation light emitted from the holographic optical element.

The holographic optical element may be a volume holographic optical element that uniformly controls the energy distribution of incident excitation light.

The lighting device may further include a bonding member interposed between the optical filter and the holographic optical element to couple the holographic optical element to the optical filter.

The optical filter may be deposited on the substrate of the holographic optical element.

The illumination device may further include an adhesive layer interposed between the holographic optical element and the light conversion member to couple the light conversion member to the holographic optical element.

The holographic optical element and the light conversion member may be spaced apart from each other with an air gap therebetween.

The light source and the optical filter may be spaced apart from each other with a gap therebetween.

The optical filter may be a short pass filter.

The light source may be a solid light emitting device that emits excitation light of 500 nm or less.

The light conversion member may include a phosphor or a quantum dot.

The holographic optical elements are photopolymer, photoresist, silver halide emulsion, dichromated gelatin, photographic emulsion, photothermoplastic and It may be formed using at least one of a photorefractive material.

According to an embodiment of the present invention, there is an effect of preventing deterioration or deterioration of the light conversion member by uniformly dispersing the energy of the excitation light incident on the incident surface of the light conversion member by applying a holographic optical element to the lighting device.

In addition, it is possible to secure the mechanical design freedom of the lighting device due to the characteristics of the holographic optical element which is lightweight and has a high degree of freedom in placement.

1 shows a lighting device according to an embodiment of the present invention.
2 and 3 show examples of a structure in which an optical filter and a holographic optical element are combined in a lighting device according to an embodiment of the present invention.
4 illustrates an example in which energy distribution and beam shape of excitation light are adjusted by a hologram optical element in a lighting device according to an embodiment of the present invention.
5 shows a lighting device according to another embodiment of the present invention.
6 and 7 show examples of applying a lighting device according to an embodiment of the present invention to a headlamp of a vehicle.
8 to 10 show examples of indoor lighting fixtures to which a lighting device according to an embodiment of the present invention is applied.

The present invention can be applied to various changes and can have various embodiments, and specific embodiments will be illustrated and described in the drawings. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms including ordinal numbers such as second and first may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, the second component may be referred to as the first component without departing from the scope of the present invention, and similarly, the first component may also be referred to as the second component. The term and/or includes a combination of a plurality of related described items or any one of a plurality of related described items.

In addition, the suffixes "module" and "part" for the components used in the following description are given or mixed only considering the ease of writing the specification, and do not have meanings or roles distinguished from each other in themselves.

When an element is said to be "connected" or "connected" to another component, it is understood that other components may be directly connected or connected to the other component, but other components may exist in the middle. It should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that no other component exists in the middle.

Terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "include" or "have" are intended to indicate the presence of features, numbers, steps, actions, components, parts or combinations thereof described in the specification, but one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. Terms, such as those defined in a commonly used dictionary, should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings, but the same or corresponding components are assigned the same reference numbers regardless of reference numerals, and redundant descriptions thereof will be omitted.

1 shows a lighting device according to an embodiment of the present invention. 2 and 3 show examples of a structure in which an optical filter and a holographic optical element are combined in a lighting device according to an embodiment of the present invention. In addition, FIG. 4 illustrates an example in which the energy distribution and beam shape of the excitation light are adjusted by the hologram optical element in the lighting device according to an embodiment of the present invention. In addition, Figure 5 shows a lighting device according to another embodiment of the present invention.

Referring to Figure 1, the lighting device includes a light source 10 and the light conversion member 40. Further, an optical filter 20 and a holographic optical element (HOE) 30 disposed between the light source 10 and the light conversion member 40 may be further included. That is, the optical filter 20, the HOE 30, and the light conversion member 40 are sequentially arranged on the traveling path of the excitation light irradiated from the light source 10 (hereinafter referred to as'light path').

The light source 10 emits excitation light. The excitation light is short wavelength light of 500 nm or less, and may be ultraviolet light or blue light. The light source 10 is not limited to this, but may emit excitation light having a peak wavelength of 350 nm to 490 nm.

The light source 10 includes laser diode (LD), laser, vertical cavity emitting laser (VCSEL), light emitting diode (LED), organic light emitting diodes (OLED), etc. It may include a solid state light emitter (SSL).

The optical filter 20 is disposed at a predetermined distance from the exit surface of the light source 10.

When the excitation light is incident from the light source 10, the optical filter 20 performs a filter function that selectively transmits at least a portion of the light. That is, the optical filter 20 transmits light of a specific range of wavelengths among the excitation light incident and blocks the rest. The optical filter 20 is not limited thereto, and may be a short pass filter (SPF) that transmits only short wavelength light having a wavelength of 450 nm or less.

HOE (30) is coupled to the exit surface of the optical filter (20), and the excitation light passing through the optical filter (20) enters the HOE (30).

The optical filter 20 may be directly deposited on the substrate of the HOE 30 as shown in FIG. 2 and combined with the HOE 30. In addition, the optical filter 20 may be combined with the HOE 30 by an adhesive member 60 after being separately manufactured from the HOE 30 as shown in FIG. 3.

HOE 30 is an optical element that adjusts an optical wavefront using a diffraction principle. The HOE 30 forms a diffraction grating corresponding to an interference fringe on a substrate formed of a photosensitive material, and adjusts a wavefront by adjusting a path of incident light using the same.

HOE 30 may be provided as a volume HOE (Volume HOE, VHOE). The volume HOE is an optical element that uses multiplexed recording characteristics of a volume hologram, and the volume hologram is a hologram in which an interference fringe created in space due to interference between an object wave and a reference wave is recorded in a three-dimensional manner on a photosensitive material.

HOE 30 operating as a volume HOE includes a multiplexed diffraction grating, multiplexes the light path of incident light through the multiplexed grating to control the beam shape, and uniformly distributes the energy distribution. Can be adjusted.

Referring to FIG. 4A, the excitation light incident on the HOE 30 after passing through the optical filter 20 rapidly decreases in energy as it moves away from the optical axis (OA). That is, the energy in the center appears relatively higher than the energy in the edge. Here, the optical axis OA is an imaginary straight line showing the direction of light travel from the point light source to the center of the three-dimensional luminous flux. As the excitation light passes through the HOE 30, the energy distribution is adjusted, and accordingly, the energy distribution appears uniformly as a whole.

Referring to FIG. 4B, incident light entering the HOE 30 after passing through the optical filter 20 shows a circular or elliptical beam shape. Thereafter, as the incident light passes through the HOE 30, the light path is adjusted to have a circular or rectangular beam shape with an increased diameter compared to the incident light.

HOE 30 includes a substrate formed of a photosensitive material, and photosensitive materials constituting the substrate of the HOE 30 include photopolymer, photoresist, silver halide emulsion, and dichromic acid. Dichromated gelatin, photographic emulsions, photothermoplastics, photorefractive materials, and the like can be used.

Referring again to FIG. 1, the light conversion member 20 is disposed on the exit surface of the HOE 30, and the excitation light passing through the HOE 30 enters the light conversion member 20.

The light conversion member 40 performs wavelength conversion of the incident excitation light. For example, the light conversion member 40 may convert the excitation light incident through the HOE 30 into a visible light having a color temperature (CCT) of 3,000k to 12,000k.

To this end, the light conversion member 30 may be a member containing a luminescent material such as a phosphor or a quantum dot. In addition, the light conversion member 30 may be implemented with a remote phosphor, a phosphor or quantum dots laminated on glass, a color filter, or the like.

The adhesive layer 50 is interposed between the HOE 30 and the light conversion member 40, and the HOE 30 and the light conversion member 40 can be mutually coupled by the adhesive layer 50.

Meanwhile, in FIG. 1, the case where the light conversion member 40 is coupled to the HOE 30 by the adhesive layer 50 is illustrated as an example, but the embodiment of the present invention is not limited thereto.

According to another embodiment of the present invention, the HOE 30 and the light conversion member 40 may be arranged spaced apart from each other as illustrated in FIG. 5. In this case, the adhesive layer 50 between the HOE 30 and the light conversion member 40 is omitted, and an air gap may be formed between the HOE 30 and the light conversion member 40.

In general, HOE can be formed on a very thin substrate, unlike other optical devices such as diffusers, beam shapers, and optical fibers for dispersing light energy over a large area. It can be implemented in light weight. In addition, it is possible to perform a predetermined function regardless of the geometrical arrangement of the substrate.

Therefore, as described above, when the HOE 30 is applied to the lighting device, the phosphors in the light conversion member 30 are deteriorated or deteriorated by uniformly dispersing the energy of the excitation light incident on the incident surface of the light conversion member 30. In addition to being prevented, it is possible to secure the mechanical design freedom of the lighting device.

Hereinafter, an example in which a lighting device according to an embodiment of the present invention is applied to a headlamp of a vehicle will be described.

6 and 7 show examples of applying a lighting device according to an embodiment of the present invention to a headlamp of a vehicle.

Referring to FIG. 6, the headlamp of the vehicle includes a light source 10, an optical filter 20, a HOE 30, a light conversion member 40 and a reflection member 70. In addition, the headlamp of the vehicle may further include a lens (not shown), a thermal pad (not shown), and a heat sink (not shown).

As the excitation light emitted from the light source 10 passes through the optical filter 20 and the HOE 30, the energy distribution is uniformly adjusted and output, and then the wavelength is converted to visible light by the light conversion member 40 and output. do. In addition, the light output from the light conversion member 30 is reflected by the reflection member 70 and output as the output of the headlamp.

The reflective member 70 is provided as a curved surface having a parabolic shape, and may operate as a multi-focus reflective member that reflects light through a reflective surface formed on the inner surface.

On the other hand, in the case of the head lamp having the structure of FIG. 6, the light conversion member 40 may have a cylindrical shape and light may be emitted in all directions through the remaining surfaces except for the incident surface. Therefore, in order to collect the light emitted in all directions in the output direction of the head lamp, the reflective member 70 is provided in a rotationally symmetrical shape around the optical axis OA so that the reflective surface surrounds the outer circumferential surface of the light conversion member 40. Can be.

FIG. 7 shows another example of a headlamp to which a lighting device according to an embodiment of the present invention is applied, and the headlamp shown in FIG. 7 has an optical filter (10) on the light source 10 different from the headlamp shown in FIG. 20), the HOE 30 and the light conversion member 40 are sequentially arranged, and the light conversion member 40 may be arranged to penetrate the fixing member 80. Also, the reflective member 70 ′ may be disposed on the fixing member 80.

The reflective member 70' is made of a curved surface whose inner surface is parabolic or elliptical. In addition, the inner surface includes a reflective surface that reflects light emitted from the light conversion member 40.

On the other hand, in the head lamp having the structure of FIG. 7, the light conversion member 40 is provided in a rectangular shape, the lower surface operates as an incident surface where excitation light enters from the light source 10, and the upper surface is wavelength converted It can operate as an exit surface from which light is emitted.

Accordingly, the reflecting member 70' is provided on the light converting member 40 so that the reflecting surface covers only the upper surface, which is the exit surface of the light converting member 40, and accordingly the reflecting member 70 shown in FIG. Compared to this, there is a disadvantage that the light emission area is reduced.

The lighting device according to the embodiment of the present invention can be widely applied to various fields such as indoor lighting, outdoor lighting, and outdoor billboards in addition to the above-described vehicle headlamps.

8 to 10 show examples of indoor lighting fixtures to which a lighting device according to an embodiment of the present invention is applied.

8 and 9, the indoor lighting fixture includes a light source 10, an optical filter 20, a HOE 30, a light conversion member 40 and a cover 90. In addition, the indoor lighting fixture may further include a heat sink (not shown), a socket (not shown), and the like.

Excitation light emitted from the light source 10 is converted into visible light while passing through the optical filter 20, the HOE 30 and the light conversion member 40, and the converted visible light passes through the cover 90 for indoor lighting. It is sent to the output of the bulb.

The cover 90 is made of glass, plastic, polypropylene (PolyPropylene, PP), polyethylene (PolyEthylene, PE), and polycarbonate (PolyCarbonate, PC), etc., may be provided with a transparent material that transmits light. The cover 90 may also include a diffusion material for diffusing light emitted from the light conversion member 40.

The cover 90 may be formed through a blow molding that can widen the directivity of light.

On the other hand, in the case of the indoor lighting fixture having the structure of Fig. 8, the light conversion member 40 may be emitted in all directions through the remaining surfaces except for the incident surface in the form of an optical small resource. On the other hand, in the case of the indoor lighting fixture having the structure of FIG. 9, the light conversion member 40 is provided in a rectangular shape, the lower surface operates as an incident surface through which light is incident from the light source 10, and the upper surface has a wavelength. The converted light may operate as an emission surface from which it is emitted.

FIG. 10 shows an example of a fluorescent lamp type indoor lighting fixture, which includes a light source 10, an optical filter 20, a HOE 30 and a light conversion member 40 at both ends, corresponding to the length of the fluorescent lamp. It includes a cover 90'. In addition, the indoor lighting fixture may further include a heat sink (not shown), a socket (not shown), and the like.

Although described above with reference to preferred embodiments of the present invention, those skilled in the art variously modify and change the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. You can understand that you can.

Claims (11)

A light source that emits excitation light;
An optical filter that selectively transmits some of the excitation light;
A holographic optical element that controls the energy distribution of excitation light emitted from the optical filter;
A light conversion member for converting the wavelength of the excitation light emitted from the holographic optical element; And
It includes a reflective member for changing the direction of the light emitted from the light conversion member,
The holographic optical element uniformly controls the energy distribution of the incident excitation light,
The opposing surface of the optical filter and the holographic optical element are bonded,
The opposing surface of the holographic optical element and the light conversion member are bonded,
The reflective member is a lighting device including a reflective surface that is rotationally symmetric about the optical axis to surround the outer peripheral surface of the light conversion member.
According to claim 1,
An illumination device in which a void is disposed between the light source and the optical filter.
According to claim 2,
The optical filter is a short wavelength pass filter (Short Pass Filter).
According to claim 3,
The light source is a solid-state light emitting device that emits excitation light of 500 nm or less.
According to claim 4,
The light conversion member is a lighting device including a phosphor (phosphor) or quantum dots (Quantum Dot).
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