CN111413841B - Wavelength conversion device, light source system and display device - Google Patents

Abstract

The present invention provides a wavelength conversion device, comprising a first wavelength conversion element for converting a first excitation light into a first subject light; and a second wavelength conversion element for converting a second excitation light into a second subject light Laser light, the first excitation light and the second excitation light are transmitted along different optical paths, the wavelength of the first subject light is within the first wavelength range, and the wavelength of the second subject light is within the second wavelength range The bandwidth of the first wavelength range is wider than that of the second wavelength range, which is conducive to improving the brightness and color purity of the illumination light used for display, and the adopted structure has the advantages of simple process and low cost. The invention also provides a light source system and a display device comprising the wavelength conversion device.

Description

Wavelength conversion device, light source system and display device

technical field

The invention relates to the field of display technology, in particular to a wavelength conversion device, a light source system and a display device.

Background technique

At present, in addition to using light-emitting diodes of corresponding colors, the main technical solutions that can be used to obtain light sources of various colors (especially white light sources) include RGB light mixing and fluorescent conversion. Among them, the fluorescent conversion scheme uses the emitted light from other light sources (such as but not limited to LED chips) to excite phosphors to generate longer-wavelength received light. The optical system obtained by using the fluorescent conversion scheme has a simple structure and low manufacturing cost. Strong practicality.

In the current red light-emitting device using the fluorescence conversion scheme, due to the large thermal Stokes shift of the red light, the red phosphor is easy to reach a thermal saturation state, thereby reducing the conversion efficiency of the red light. In practical applications, red light can be generated by using a long-wavelength yellow wavelength conversion material including YAG:Ce ³⁺ with a red light filter. Please refer to Figure 1. Under the same excitation power, the red wavelength conversion material emits The red laser light spectrum is 902a, and the yellow laser light spectrum emitted by the yellow wavelength conversion material is 901a. It can be seen that the energy of the yellow laser light is greater than that of the red laser light (spectral energy is the area covered by the spectrum). However, the wavelength range covered by the yellow laser light spectrum 901a is approximately 500nm-700nm, and only the spectral components with a wavelength greater than 590nm correspond to red light. It can be seen that in order to obtain red light output, a red light filter must be used to filter out components in the yellow light spectrum with a wavelength less than 590nm. Please refer to Fig. 2, the filtered yellow stimulated spectrum is 901b, and the filtered red stimulated spectrum is 902b. It can be easily seen from the spectrum that the energy loss of the yellow laser spectrum 901a is very large during the filtering process. Although the energy of the red laser light spectrum 902a itself is low, most of its energy is concentrated in the wavelength range greater than 590nm, so the energy loss in the filtering process is very small. Before filtering, the luminous flux of the yellow laser spectrum is 4.56 times that of the red laser spectrum, but after filtering to achieve the same red color coordinates, the filtered yellow laser light flux is only 11.6% of that before filtering, while the filtered red The luminous flux of the laser is 53.4% of that before filtering. Finally, the method of using yellow wavelength conversion material and red light filter to generate red light is almost the same as the method of directly using red wavelength conversion material to generate red light, although the former uses a higher light saturation characteristic. YAG: Ce ³⁺ yellow phosphor, but most of the energy will be lost in the subsequent filtering process, the luminous flux of the finally filtered monochromatic light is not satisfactory, the overall energy conversion efficiency is low, and the light source is increased size and cost.

Another known high-brightness red light-emitting device uses long-wavelength yellow phosphors or short-wavelength red phosphors and red lasers to generate red light. Although the efficiency and brightness of red lasers are high, the cost of red lasers is high and packaging The requirements are relatively high, and an additional optical path is required, which is not conducive to the miniaturization design of the light source and display equipment. Therefore, the existing red light emitting device cannot achieve high brightness and high efficiency at low cost, and is inconvenient to promote.

Contents of the invention

The first aspect of the present invention provides a wavelength conversion device, including:

a first wavelength conversion element for converting the first excitation light into the first stimulated light; and

a second wavelength conversion element, configured to convert the second excitation light into a second subject light;

The first excitation light and the second excitation light are transmitted along different optical paths, the wavelength of the first subject light is in the first wavelength range, and the wavelength of the second subject light is in the second wavelength range, so The bandwidth of the first wavelength range is wider than that of the second wavelength range.

The second aspect of the present invention provides a light source system, including:

a light source for emitting excitation light; and

The wavelength conversion device according to the first aspect of the present invention, wherein the first wavelength conversion element and the second wavelength conversion element are used to receive the excitation light and generate the first subject light and the second subject light ;

The first received light and the second received light emerge from the light source system along the same optical path.

A third aspect of the present invention provides a display device, including:

The light source system provided by the second aspect of the present invention.

The wavelength of the first received light emitted by the wavelength conversion device provided by the present invention is within the first wavelength range, and the wavelength of the second emitted light is within the second wavelength range, and the first wavelength range is compared with the second wavelength range. The bandwidth of the wavelength range is wide, which is conducive to improving the brightness and color purity of the illumination light used for display, and the adopted structure has the advantages of simple process and low cost. The invention also provides a light source system and a display device including the wavelength conversion device.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments/methods of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments/methods. Obviously, the accompanying drawings in the following description are some embodiments of the present invention /method, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work.

Figure 1 is the stimulated light emission spectrum curves of the yellow wavelength conversion material and the red wavelength conversion material.

Fig. 2 is a spectrum curve of the excited light of the yellow wavelength conversion material and the red wavelength conversion material after passing through the filter device.

Fig. 3 is a schematic structural diagram of the light source system provided by the present invention.

Figure 4 is the absorption spectrum and emission spectrum curves of Eu ³⁺ doped oxide ceramics.

Fig. 5 is a normalized curve of the absorption spectrum of Eu ³⁺ doped oxide ceramics and the emission spectrum of the second light source.

Description of main component symbols

The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings.

Detailed ways

In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

In the following description, many specific details are set forth in order to fully understand the present invention, and the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of the invention. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention.

The invention provides a wavelength conversion device and a light source system including the wavelength conversion device, and the light source system can be applied to low-power light source products. The present invention also provides a display device including the light source system, which can be applied to projection products, especially to micro-projectors. The light source system and display device provided by the invention have the characteristics of high light efficiency, high brightness and high color purity, and the wavelength conversion device has a simple structure and manufacturing process, low cost, and has broad market application prospects.

Referring to FIG. 3 , the present invention provides a light source system 100 . The light source system 100 includes a light source 110 and a wavelength conversion device 120 . Wherein, the light source 110 is used to emit excitation light, and the wavelength conversion device 120 is used to receive the excitation light and generate the first received light and the second received light, and the first received light and the second received light are emitted from the light source system 100 along the same optical path.

Further, the light source 110 includes a first light source 111 for emitting the first excitation light and a second light source 112 for emitting the second excitation light. In this embodiment, the first light source 111 is a blue light emitting diode (Light Emitting Diode, LED), and the second light source 112 is a laser light source, such as a blue laser diode (Laser Diode, LD). In one embodiment, the first light source 111 may be a blue LED chip, and the second light source 112 may be a blue LD chip. In other embodiments, the types and colors of the first light source 111 and the second light source 112 may be the same or different, and the first light source 111 and the second light source 112 may also be arc light sources, fluorescent light sources, etc., the first excitation light And the second excitation light can also be white light, ultraviolet light, green light, yellow light, red light or light of other colors.

The wavelength conversion device 120 includes a first wavelength conversion element 121 and a second wavelength conversion element 122 , the surface of the first wavelength conversion element 121 facing away from the second wavelength conversion element 122 is bonded to the light output surface of the first light source 111 . The first wavelength conversion element 121 is used to generate the first received light in the first wavelength range under the irradiation of the incident light of the first wavelength conversion element 121; the second wavelength conversion element 122 is arranged adjacent to the first wavelength conversion element 121, It is used for generating the second received light within the second wavelength range under the irradiation of the incident light of the second wavelength converting element 122 . Specifically, the first wavelength conversion element 121 and the second wavelength conversion element 122 are stacked. In other implementation manners, the first wavelength conversion element 121 and the second wavelength conversion element 122 may be arranged at intervals. The emission direction of the first converted light is the same as that of the first excitation light incident on the first wavelength conversion element 121 , and the emission direction of the second converted light is opposite to the direction of the second excitation light incident on the second wavelength conversion element 122 .

The first wavelength conversion element 121 includes a mixture of phosphor powder and silica gel, and the phosphor powder in the first wavelength conversion element 121 is used to generate the first received light under the irradiation of the incident light of the first wavelength conversion element 121 . In this embodiment, the first wavelength conversion element 121 is formed by mixing and curing phosphor powder and silica gel. Preferably, the phosphor powder is a red phosphor powder including (Sr, Ca)AlSiN ₃ :Eu ^{2 +} to produce a red first wavelength conversion element 121. By laser. In order to balance the conversion efficiency of the first wavelength conversion element 121 and the reliability of bonding the first light source 111 and the second wavelength conversion element 122 , the silica gel is preferably methylphenyl silica gel with a refractive index of 1.45-1.52. The second wavelength conversion element 122 includes oxide ceramics. In this embodiment, the second wavelength conversion element 122 includes oxide ceramics doped with Eu ³⁺ to generate red second received light. The second wavelength conversion element 122 uses oxide ceramics doped with Eu ³⁺ to increase the density of the red light ceramics, thereby improving the brightness, efficiency and color gamut of the red light emitted by the light source system 100 .

Specifically, the bandwidth of the first wavelength range of the first received light is wider than that of the second wavelength range of the second received light. In this embodiment, the second wavelength range is 600-620nm, the bandwidth of the second wavelength range is 20nm, the bandwidth of the first wavelength range is greater than 20nm, the first wavelength range can be but not limited to 580-620nm, 590-630nm or 570nm -620nm. In a modified embodiment, the second wavelength range is 610-630 nm. It can be understood that the wavelength conversion material in the second wavelength conversion element 122 can be flexibly selected according to the target color gamut, so that the color coordinate of the second received light is within the range of the target color gamut.

Please refer to Figure 4, the emission spectrum of oxide ceramics doped with Eu ³⁺ shows strong 4f-4f sharp line emission in the range of 610-630nm, and X=0.64-0.68 in the color coordinates of the emission spectrum, the emitted The narrow-band red light has a high color purity, exceeding the REC709 red light standard. In addition, the preparation process of oxide ceramics doped with Eu ³⁺ is relatively simple. Generally, high-density ceramics can be prepared in air, and the cost is relatively low. Ceramics have high thermal conductivity and stability. In this embodiment, the second wavelength conversion element 122 includes oxide ceramics doped with Eu ³⁺ , so it can not only reduce the production cost of the light source system 100, simplify the production process, but also improve the brightness and color purity of the second received light. Moreover, the conversion efficiency of the second wavelength conversion element 122 to the blue laser light is improved, thereby widening the color gamut of the illumination light emitted from the light source system 100 , and improving the light source utilization rate of the illumination light to reduce light consumption.

In this embodiment, the first light source 111 emits blue LED light including a third wavelength range, and the third wavelength range may be but not limited to 450-465nm. (Sr, Ca)AlSiN ₃ :Eu ²⁺ in the second wavelength conversion element 122 can efficiently absorb the blue LED light in the third wavelength range and convert it into the first received light, which is beneficial to improve the performance of the first wavelength conversion element 121. The conversion efficiency of the first excitation light can reduce the light consumption to achieve the effect of energy saving.

Please refer to FIG. 5 , the oxide ceramic doped with Eu ³⁺ can efficiently absorb the light in the fourth wavelength range of the second excitation light, wherein the fourth wavelength range can be but not limited to 462-468nm. The absorption spectrum bandwidth (i.e. the wavelength range corresponding to half of the absorption peak) of the oxide ceramics doped with Eu ³⁺ is 4-5nm, and the oxide ceramics doped with Eu ³⁺ presents a relatively narrow spectrum in the fourth wavelength range. Strong 4f-4f sharp line absorption. The wavelength of the blue laser light emitted by the second light source 112 is the fourth wavelength range. Specifically, as shown in ^FIG . The bandwidth of the second excitation light exceeds the bandwidth of the second subject light by 1.5nm, so that the second excitation light emitted by the second light source 112 will be converted into the second subject light by the second wavelength conversion element 122, and the Eu ³⁺ doped In the case of unsaturated oxide ceramics, the unconverted part of the second excitation light does not exist or accounts for a very small proportion, so it is beneficial to improve the utilization rate of the second excitation light by the second wavelength conversion element 122, and it is beneficial to improve the efficiency of the light source. The light effect of the system 100.

As shown in FIG. 3 , the light source system 100 also includes a thermally conductive substrate 150, the surface of the first light source 111 facing away from the first wavelength conversion element 121 is bonded to the thermally conductive substrate 150, and the thermally conductive substrate 150 is used to dissipate the heat generated by the first light source 111 The heat conduction substrate 150 or the surface of the first light source 111 connected to the heat conduction substrate 150 is used to reflect the light, so that the second received light and the first received light emerge from the light source system 100 along the same optical path. In one embodiment, the heat conduction substrate 150 is used to reflect light, and the heat conduction substrate 150 can be made of various plates with heat conduction properties, such as glass plate or metal plate. In one embodiment, the first light source 111 is connected to the surface of the thermally conductive substrate 150 for reflecting light, for example, the surface can reflect the first excitation light, the first subject light, the second excitation light and the second subject light, it can be understood Notably, the heat accumulated by the wavelength conversion device 120 during the wavelength conversion process can be diffused into the surrounding space through the first light source 111 and the heat-conducting substrate 150 by way of heat transfer, thereby reducing the working temperature of the wavelength conversion device 120 to avoid the wavelength conversion device 120 thermal saturation occurs with the increase of temperature, which leads to the decrease of conversion efficiency.

The light source system 100 also includes a light-receiving lens 130 and a light-splitting element 140. The light-receiving lens 130 is used to guide the first and second light beams excited on the wavelength conversion device 120 to be parallel to the light-splitting element 140. The light-splitting element 140 includes Guide the second excitation light emitted by the second light source 112 to enter the first region 141 of the second wavelength conversion element 122, and the second region 142 for transmitting the first and second converted light to emit high brightness and high color saturation degrees of red light. Optionally, the light source system 100 also includes a light homogenizing element, which is arranged between the light collecting lens 130 and the light splitting element 140 to improve the uniformity of the emitted red light. The light homogenizing element can be a fly-eye lens or a square rod.

On the one hand, the light source system 100 excites the red phosphor containing (Sr, Ca)AlSiN ₃ :Eu ²⁺ through the blue LED chip to efficiently excite to form red light with a wide wavelength range; on the other hand, it excites the red phosphor doped with Eu ³⁺ oxide ceramics to form red light with a narrow wavelength range with high brightness and color purity, and combine red light with a wide wavelength range and red light with a narrow wavelength range to form red light with high brightness and high color purity , which solves the problems of high cost, high process requirements and low red light excitation efficiency of the current red light emitting device. The present invention also provides a display device including the light source system 100, the display device can be a projection product, preferably a micro projector.

In another modified embodiment, the phosphor in the first wavelength conversion element 121 includes green phosphor containing LuAG:Ge ¹⁺ , which is used to generate the green first received light in the first wavelength range, and the second The wavelength converting element 122 includes oxide ceramics doped with Tb ³⁺ for generating a green second received light in a second wavelength range. The main energy of the second excitation light emitted by the second light source 112 is concentrated in the range of 480-486 nm. The first received light and the second received light are transmitted through the light splitting element 140 to form green light for display.

In a modified embodiment, the phosphor in the first wavelength conversion element 121 includes yellow phosphor containing YAG:Ce ³⁺ , and the first wavelength conversion element 121 generates the first stimulant under the excitation of the first light source 111. The laser is yellow light. The second wavelength conversion element 122 is used to generate the red second subject light, the first excitation light, the second excitation light, the first subject light and the second subject light pass through the heat conduction substrate 150 or the first light source 111 and the connection surface of the heat conduction substrate 150 After being reflected, it passes through the light splitting element 140 and emerges from the light source system 100 to form white light for display.

It will be apparent to those skilled in the art that the invention is not limited to the details of the above-described exemplary embodiments, but that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Accordingly, the embodiments should be regarded in all points of view as exemplary and not restrictive, the scope of the invention being defined by the appended claims rather than the foregoing description, and it is therefore intended that the scope of the invention be defined by the appended claims rather than by the foregoing description. All changes within the meaning and range of equivalents of the elements are embraced in the present invention. Any reference sign in a claim should not be construed as limiting the claim concerned. In addition, it is obvious that the word "comprising" does not exclude other elements or steps, and the singular does not exclude the plural. A plurality of devices stated in the device claims can also be realized by the same device or system through software or hardware. The words first, second, etc. are used to denote names and do not imply any particular order.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be Modifications or equivalent replacements can be made without departing from the spirit and scope of the technical solutions of the present invention.

Claims (16)

1. A wavelength conversion device, characterized in that, comprising: a first wavelength conversion element for converting the first excitation light into the first stimulated light; and a second wavelength conversion element, configured to convert the second excitation light into a second subject light; The first excitation light and the second excitation light are transmitted along different optical paths; the first subject light and the second subject light are light of the same color, wherein the wavelength of the first subject light is between Within the first wavelength range, the wavelength of the second subject light is within the second wavelength range, and the bandwidth of the first wavelength range is wider than that of the second wavelength range. 2. The wavelength conversion device according to claim 1, wherein the first wavelength conversion element is used to convert the incident light in the third wavelength range into the first received light, and the second wavelength The converting element is used for converting incident light in a fourth wavelength range into the second received light, and the bandwidth of the third wavelength range is wider than that of the fourth wavelength range. 3. The wavelength conversion device according to claim 1, wherein the first wavelength conversion element comprises a mixture of phosphor powder and silica gel, and the phosphor powder is used to transform the light incident on the first wavelength conversion element converted to the first subject light. 4 . The wavelength conversion device according to claim 3 , wherein the phosphor comprises (Sr, Ca)AlSiN ₃ :Eu ^{2 +} , YAG:Ce ³⁺ or LuAG:Ge ³⁺ . 5. The wavelength conversion device according to claim 3, wherein the silica gel comprises methylphenyl silica gel with a refractive index of 1.45-1.52. 6. The wavelength conversion device of claim 1, wherein the second wavelength conversion element comprises an oxide ceramic. 7. The wavelength conversion device according to claim 6, wherein the oxide ceramic is doped with Eu ³⁺ or Tb ³⁺ . 8. The wavelength conversion device according to claim 1, wherein the first wavelength conversion element and the second wavelength conversion element are stacked; the first wavelength range covers the second wavelength range, or The second wavelength range is partially within the first wavelength range. 9. The wavelength conversion device according to claim 1, wherein the emission direction of the first received light is the same as that of the first excitation light, and the emission direction of the second received light is the same as that of the first excitation light. The directions of the two excitation lights are opposite. 10. A light source system, characterized in that it comprises: a light source for emitting excitation light; and The wavelength conversion device according to any one of claims 1-9, wherein the first wavelength conversion element and the second wavelength conversion element are respectively used to receive the excitation light and generate the first stimulated light and the the second receiving light; The first received light and the second received light emerge from the light source system along the same optical path. 11. The light source system according to claim 10, wherein the light source comprises a first light source and a second light source, wherein the first light source is used to emit the first excitation light, and the first excitation light The first received light is generated after being incident on the first wavelength conversion element; the second light source is used to emit the second excitation light, and the second excitation light is incident on the second wavelength element to generate the Describe the second receiving light. 12. The light source system of claim 11, the first light source comprising a light emitting diode and the second light source comprising a laser light source. 13. The light source system according to claim 11, wherein a surface of the first wavelength conversion element facing away from the second wavelength conversion element is bonded to the light-emitting surface of the first light source. 14. The light source system according to claim 11, wherein the light source system further comprises a thermally conductive substrate, and the surface of the first light source facing away from the first wavelength conversion element is bonded to the thermally conductive substrate, The heat conducting substrate is used for conducting the heat generated by the first light source to the surrounding space. 15. The light source system according to claim 14, characterized in that, the heat-conducting substrate or the surface where the first light source is connected to the heat-conducting substrate is used to reflect light, so that the second received light and the The first received light exits from the light source system along the same optical path. 16. A display device, comprising the light source system according to any one of claims 10-15.