JP6323299B2 - Wavelength conversion member and light emitting device - Google Patents

Description

  The present invention relates to a wavelength conversion member and a light emitting device including the same.

  Conventionally, a so-called edge light type backlight having a light guide and a light emitting device that emits light to a side surface of the light guide is used as a backlight of a liquid crystal display or the like. For example, Patent Document 1 describes using an LED and a light-emitting device having a wavelength conversion member that receives light from the LED and emits light having a longer wavelength as an edge-light type backlight. Yes. The wavelength conversion member described in Patent Document 1 includes a phosphor and a capillary tube in which the phosphor is enclosed. The cross-sectional shape of the capillary is an oval shape.

JP 2012-163798 A

  Edge-light type backlights are desired to reduce in-plane variations in the intensity of emitted light from the light exit surface of the backlight. In order to reduce the in-plane variation of the emitted light intensity, it is preferable that the light is uniformly incident on the side surface of the light guide.

  A main object of the present invention is to provide a wavelength conversion member that can emit light with small intensity unevenness with respect to a side surface of a light guide.

  The wavelength conversion member according to the present invention includes a tube having a curvature over the entire periphery, a wavelength conversion agent disposed in the tube, and a cover member provided so as to cover the outer peripheral surface of the tube over the entire periphery. Has planar first and second light entry / exit surfaces that face each other in a direction perpendicular to the longitudinal direction of the tube. Since the wavelength conversion member according to the present invention can suppress the incidence of light at a large incident angle with respect to the surface of the wavelength conversion member, it can emit light with small intensity unevenness.

  In the wavelength conversion member according to the present invention, the cover member includes a first reflection surface connecting the one side edge of the first light input / output surface and the one side edge of the second light input / output surface; It is preferable to further have a second reflecting surface connecting the other side edge of the first light entrance / exit surface and the other side edge of the second light entrance / exit surface. As a result, the amount of light emitted from the first or second light entrance / exit surface can be increased.

  In the wavelength conversion member according to the present invention, the difference between the refractive index of the cover member and the refractive index of the tube is preferably 0.3 or less. As a result, the amount of light emitted from the first or second light entrance / exit surface can be further increased, and undesired reflection at the interface between the cover member and the tube can be suppressed.

  In the wavelength conversion member according to the present invention, the shape of the cross section of the tube may be a circle or an ellipse.

  The light-emitting device according to the present invention includes the wavelength conversion member according to the present invention and a light source that emits light to the first light entrance / exit surface.

  ADVANTAGE OF THE INVENTION According to this invention, the wavelength conversion member which can radiate | emit light with small intensity unevenness with respect to the side surface of a light guide can be provided.

1 is a schematic plan view of a light emitting device according to a first embodiment. FIG. 2 is a schematic cross-sectional view taken along line AA in FIG. 1. It is a typical sectional view showing one usage pattern of the light emitting device concerning a 1st embodiment. It is a ray tracing figure in a comparative example. It is a ray tracing figure in a 1st embodiment. It is a ray tracing diagram in the second embodiment. It is a ray tracing diagram in a 3rd embodiment. It is a ray tracing figure in a 4th embodiment.

  Hereinafter, an example of the preferable form which implemented this invention is demonstrated. However, the following embodiment is merely an example. The present invention is not limited to the following embodiments.

  Moreover, in each drawing referred in embodiment etc., the member which has a substantially the same function shall be referred with the same code | symbol. The drawings referred to in the embodiments and the like are schematically described. A ratio of dimensions of an object drawn in a drawing may be different from a ratio of dimensions of an actual object. The dimensional ratio of the object may be different between the drawings. The specific dimensional ratio of the object should be determined in consideration of the following description.

(First embodiment)
FIG. 1 is a schematic plan view of a light emitting device 1 according to the first embodiment. FIG. 2 is a schematic cross-sectional view taken along line AA in FIG. In FIG. 2, hatching representing a cross section is omitted.

  As shown in FIGS. 1 and 2, the light emitting device 1 includes a wavelength conversion member 10 having an elongated shape and a light source 11. A plurality of light sources 11 are provided along the length direction of the wavelength conversion member 10.

  The wavelength conversion member 10 is a member that emits light having a wavelength different from that of the excitation light when the excitation light is incident. The light source 11 emits excitation light to the wavelength conversion member 10. In the light emitting device 1, substantially all of the light emitted from the light source 11 may be absorbed by the wavelength conversion member 10, or part of the light may pass through the wavelength conversion member 10. That is, the light emitting device 1 may be a device that emits mixed light of light emitted from the light source 11 and transmitted through the wavelength conversion member 10 and light emitted from the wavelength conversion member 10.

  The light source 11 can be composed of, for example, an LED (Light Emitting Diode) element, an LD (Laser Diode) element, or the like.

  FIG. 3 is a schematic cross-sectional view showing one usage pattern of the light emitting device according to the first embodiment. In FIG. 3, hatching representing a cross section is omitted.

  As shown in FIG. 3, the light emitting device 1 emits light to the side surface 12 a of the light guide 12. Specifically, the light emitting device 1 is provided on the side of the light guide 12 so as to face the side surface 12a. The light emitted from the light emitting device 1 and entering the light guide 12 is emitted as planar light from the main surface 12 b of the light guide 12. The light emitting device 1 and the light guide 12 are used as a backlight of a display device such as a liquid crystal device, for example.

  The wavelength conversion member 10 includes a tube 13, a wavelength conversion agent 14, and a cover member 15.

  The shape of the tube 13 is not particularly limited as long as it is an elongated shape. For example, in the wavelength conversion member 10, the tube 13 has a curvature over the entire circumference. The curvature of the tube 13 may be constant over the entire circumference or may not be constant. Specifically, the shape of the cross section of the tube 13 may be, for example, a circle or an ellipse.

  The tube 13 is not particularly limited as long as it has translucency. For example, the tube 13 is made of glass, resin, ceramics, or the like. Especially, it is preferable that the pipe | tube 13 is comprised with glass. By configuring the tube 13 with glass, it is possible to increase the light transmittance, particularly the light transmittance of short wavelengths.

  A wavelength conversion agent 14 is disposed inside the tube 13. When the excitation light is incident, the wavelength conversion agent 14 emits light having a wavelength different from that of the excitation light. As the wavelength conversion agent 14, a phosphor, a quantum dot, or the like is preferably used.

  As the phosphor, an inorganic phosphor is preferably used.

Specific examples of inorganic phosphors that emit blue visible light (fluorescence of wavelengths of 440 to 480 nm) when irradiated with excitation light of wavelengths from 300 to 440 nm include Sr ₅ (PO ₄ ) ₃ Cl: Eu ²⁺ , (Sr, Ba) MgAl ₁₀ O ₁₇ : Eu ^{2+ and the} like. Specific examples of the inorganic phosphor that emits green visible light (fluorescence having a wavelength of 500 nm to 540 nm) when irradiated with excitation light having a wavelength of 300 to 440 nm are SrAl ₂ O ₄ : Eu ²⁺ , SrGa ₂ S. ₄ : Eu <^2+> etc. are mentioned. Specific examples of inorganic phosphors that emit green visible light (fluorescence having a wavelength of 500 nm to 540 nm) when irradiated with blue excitation light having a wavelength of 440 to 480 nm include SrAl ₂ O ₄ : Eu ²⁺ and SrGa ₂ S ₄ : Eu. ^{2+ and the} like. A specific example of the inorganic phosphor that emits yellow visible light (fluorescence having a wavelength of 540 nm to 595 nm) when irradiated with excitation light having a wavelength of 300 to 440 nm is ZnS: Eu ²⁺ . As a specific example of an inorganic phosphor that emits yellow visible light (fluorescence having a wavelength of 540 nm to 595 nm) when irradiated with blue excitation light having a wavelength of 440 to 480 nm, Y ₃ (Al, Gd) ₅ O ₁₂ : Ce ^2+, etc. Is mentioned. Specific examples of the inorganic phosphor that emits red visible light (fluorescence having a wavelength of 600 nm to 700 nm) when irradiated with excitation light having a wavelength of 300 to 440 nm include Gd ₃ Ga ₄ O ₁₂ : Cr ³⁺ , CaGa. ₂ S ₄ : Mn ^{2+ and the} like. Specific examples of the inorganic phosphor that emits red visible light (fluorescence having a wavelength of 600 nm to 700 nm) when irradiated with blue excitation light having a wavelength of 440 to 480 nm include Mg ₂ TiO ₄ : Mn ⁴⁺ and K ₂ SiF ₆ : Mn. ^{4+ and the} like. As the inorganic phosphor, those having a particle diameter of about 5 μm to 50 μm can be used.

  The quantum dot emits light having a wavelength different from that of the excitation light when the excitation light of the quantum dot is incident. The wavelength of the light emitted from the quantum dot depends on the particle diameter of the quantum dot. That is, the wavelength of the light obtained by changing the particle diameter of the quantum dots can be adjusted. For this reason, the particle diameter of a quantum dot is made into the particle diameter according to the wavelength of the light to obtain. The particle diameter of the quantum dots is usually about 2 nm to 10 nm.

  For example, as a specific example of a quantum dot that emits blue visible light (fluorescence with a wavelength of 440 nm to 480 nm) when irradiated with excitation light of ultraviolet to near ultraviolet with a wavelength of 300 nm to 440 nm, the particle diameter is about 2.0 nm to 3.0 nm. And CdSe / ZnS microcrystals. As a specific example of a quantum dot that emits green visible light (fluorescence having a wavelength of 500 nm to 540 nm) when irradiated with excitation light of ultraviolet to near ultraviolet with a wavelength of 300 nm to 440 nm or blue excitation light with a wavelength of 440 nm to 480 nm, the particle diameter CdSe / ZnS microcrystals having a thickness of about 3.0 nm to 3.3 nm. Specific examples of quantum dots that emit yellow visible light (fluorescence having a wavelength of 540 nm to 595 nm) when irradiated with ultraviolet to near ultraviolet excitation light having a wavelength of 300 nm to 440 nm or blue excitation light having a wavelength of 440 nm to 480 nm include particle diameters. CdSe / ZnS microcrystals having a thickness of about 3.3 nm to 4.5 nm. As a specific example of a quantum dot that emits red visible light (fluorescence having a wavelength of 600 nm to 700 nm) when irradiated with excitation light having a wavelength of 300 nm to 440 nm or blue excitation light having a wavelength of 440 nm to 480 nm, CdSe / ZnS microcrystals having a thickness of about 4.5 nm to 10 nm.

  The wavelength conversion agent 14 may be enclosed in the tube 13 in a state of being dispersed in a dispersion medium, for example. The wavelength conversion agent 14 may be enclosed in the tube 13 while being supported on a carrier, for example. Alternatively, only the wavelength conversion agent 14 may be enclosed in the tube 13.

  A cover member 15 is provided on the outer peripheral surface of the tube 13. Specifically, the cover member 15 is provided so as to cover the outer peripheral surface of the pipe 13 over the entire circumference.

  The cover member 15 is not particularly limited as long as it has translucency. For example, the cover member 15 is made of, for example, resin, glass, ceramics, or the like. Especially, it is preferable that the cover member 15 is comprised with resin. When the cover member 15 is made of resin, the cover member 15 can be easily processed into a desired shape.

  The cover member 15 has first and second light entrance / exit surfaces 15a and 15b. The first and second light entrance / exit surfaces 15a and 15b are planar.

  In the present invention, “light entrance / exit surface” is a general term for “light entrance surface” and “light exit surface”.

  The first light entrance / exit surface 15a faces the light source 11 side. The first light entrance / exit surface 15 a is provided perpendicular to the optical axis of the light source 11. The light emitted from the light source 11 enters from the first light entrance / exit surface 15a. Accordingly, the first light entrance / exit surface 15a constitutes a light incident surface.

  The second light entrance / exit surface 15b is provided to face the first light entrance / exit surface 15a with the central axis of the tube 13 interposed therebetween. The second light entrance / exit surface 15 b faces the first light entrance / exit surface 15 a in a direction perpendicular to the longitudinal direction of the tube 13. The first light entrance / exit surface 15a and the second light entrance / exit surface 15b are provided in parallel. The light incident on the first light entrance / exit surface 15a exits from the second light entrance / exit surface 15b. Accordingly, the second light entrance / exit surface 15b constitutes a light exit surface.

  For example, as shown in FIG. 4, when a cover member is not provided around the tube 113, light emitted from the light source is incident on the surface of the tube 113 with a large incident angle. Light incident at a large incident angle with respect to a portion away from the optical axis is largely refracted toward the optical axis. For this reason, most of the light incident on the tube 113 is concentrated in the vicinity of the optical axis, and the intensity of the emitted light is extremely reduced when the distance from the vicinity of the optical axis is increased. That is, as shown in FIG. 4, when the cover member is not provided, most of the light emitted from the tube 113 is concentrated on the optical axis. Therefore, when viewed from the optical axis, the intensity of the emitted light from the wavelength conversion member varies greatly.

  On the other hand, in the case of the wavelength conversion member 10, a cover member 15 is provided so as to cover the outer peripheral surface of the tube 13 over the entire circumference, and the cover member 15 is a planar shape facing in a direction perpendicular to the longitudinal direction of the tube 13. First and second light entrance / exit surfaces 15a and 15b. For this reason, as shown in FIG. 5, the incident angle of the light which injects into the part away from the optical axis of the pipe | tube 13 is small. Therefore, the light incident on the part of the tube 13 away from the optical axis is not easily refracted toward the optical axis. For this reason, it is difficult for the emitted light to concentrate near the optical axis. Therefore, the intensity unevenness of the light emitted from the wavelength conversion member 10 is small. Therefore, the light emitting device 1 can emit light with small intensity unevenness with respect to the side surface of the light guide.

  From the viewpoint of further reducing the unevenness in strength, it is preferable that the difference between the refractive index of the cover member 15 and the refractive index of the tube 13 is small. Specifically, the difference between the refractive index of the cover member 15 and the refractive index of the tube 13 is preferably 0.3 or less, more preferably 0.2 or less, and 0.1 or less. More preferably. Thus, when the difference between the refractive index of the cover member 15 and the refractive index of the tube 13 is small, the reflectance at the interface is low. Therefore, the intensity of the emitted light can be increased. In addition, the refraction angle at the interface between the cover member 15 and the tube 13 can be reduced. For this reason, the intensity unevenness of the emitted light from the wavelength conversion member 10 can be further reduced.

  Note that the cover member 15 may be provided integrally, or may be configured by a plurality of cover member pieces.

  Hereinafter, other examples of preferred embodiments of the present invention will be described. In the following description, members having substantially the same functions as those of the first embodiment are referred to by the same reference numerals, and description thereof is omitted.

(Second Embodiment)
FIG. 6 is a ray tracing diagram in the second embodiment.

  In the first embodiment, an example in which the shape of the cover member 15 is rectangular when viewed from the direction in which the central axis of the tube 13 extends has been described. In the first embodiment, each of the first and second side surfaces 15c and 15d connecting the first light entrance / exit surface 15a and the second light entrance / exit surface 15b of the cover member 15 is at least a part. The light transmitting surface is configured to transmit light.

  On the other hand, in the second embodiment, the first side surface 15c constitutes the first reflecting surface. The second side surface 15d constitutes a second reflecting surface. For this reason, as shown in FIG. 6, the light incident on the first and second side surfaces 15c and 15d is reflected, and at least a part of the light exits from the second light entrance / exit surface 15b. Therefore, the light emitting device according to the second embodiment has high luminance.

  The method for making the first and second side surfaces 15c and 15d reflective surfaces is not particularly limited. For example, the first and second side surfaces 15c and 15d may be formed of a film made of a metal such as aluminum or silver, a white coating film, or the like, and the first and second side surfaces 15c and 15d may be reflective films. .

(Third embodiment)
FIG. 7 is a ray tracing diagram in the third embodiment.

  In the first embodiment, the example in which the shape of the cover member 15 is rectangular when viewed from the direction in which the central axis of the cover member 15 extends has been described. However, the present invention is not limited to this configuration. For example, as shown in FIG. 7, when viewed from the direction in which the central axis of the tube 13 extends, the cover member 15 may have a shape that tapers from the light source 11 side toward the second light entrance / exit surface 15b side. . In this case, since the cover member 15 can be reduced in size, the light emitting device can be reduced in size and weight.

(Fourth embodiment)
FIG. 8 is a ray tracing diagram in the fourth embodiment.

  The light emitting device according to the fourth embodiment is different from the light emitting device according to the third embodiment in that the first and second side surfaces 15c and 15d are configured by reflecting surfaces. In the fourth embodiment, since the first and second side surfaces 15c and 15d are constituted by reflecting surfaces, the light incident on the first and second side surfaces 15c and 15d is reflected, and at least a part thereof is reflected. The light exits from the second light entrance / exit surface 15b. Therefore, the light emitting device according to the fourth embodiment has high luminance.

DESCRIPTION OF SYMBOLS 1 Light emitting device 10 Wavelength conversion member 11 Light source 12 Light guide 12a Side surface 12b Main surface 13 Tube 14 Wavelength conversion agent 15 Cover member 15a First light entrance / exit surface 15b Second light entrance / exit surface 15c First side surface 15d Second side

Claims (5)

A tube having a curvature all around,
A wavelength converting agent disposed in the tube;
A cover member provided to cover the outer peripheral surface of the tube over the entire circumference;
With
The said cover member is a wavelength conversion member which has the planar 1st and 2nd light entrance / exit surface which opposes in the direction perpendicular | vertical to the longitudinal direction of the said pipe | tube. The cover member is
A first reflecting surface connecting one side edge of the first light entrance / exit surface and one side edge of the second light entrance / exit surface;
A second reflecting surface connecting the other side edge of the first light entrance / exit surface and the other side edge of the second light entrance / exit surface;
The wavelength conversion member according to claim 1, further comprising:   The wavelength conversion member according to claim 1 or 2, wherein a difference between a refractive index of the cover member and a refractive index of the tube is 0.3 or less.   The wavelength conversion member according to any one of claims 1 to 3, wherein a shape of a cross section of the tube is a circle or an ellipse. The wavelength conversion member according to any one of claims 1 to 4,
A light source for emitting light to the first light entrance / exit surface;
A light emitting device comprising: