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EP-4737792-A1 - LIGHTING DEVICE AND COLOR CONVERSION ELEMENT

EP4737792A1EP 4737792 A1EP4737792 A1EP 4737792A1EP-4737792-A1

Abstract

A lighting device includes (100): a white light source (110) that includes a blue light-emitting element and a yellow phosphor, and emits a first white light; and a color conversion element (130) that converts the first white light to a second white light. 2500 ≤ (TG / TB) × T2 ≤ 5000 and T1 - T2 ≥ 300 are satisfied, where: TB is an average transmittance of the color conversion element (130) in a range of from 435 nm to 480 nm, inclusive; TG is an average transmittance of the color conversion element (130) in a range of from 540 nm to 590 nm, inclusive; T1 is a color temperature of the first white light for which a unit of measurement is K; and T2 is a color temperature of the second white light for which a unit of measurement is K.

Inventors

  • KITANO, HIROSHI
  • HIRATANI, Kosuke

Assignees

  • Panasonic Intellectual Property Management Co., Ltd.

Dates

Publication Date
20260506
Application Date
20240530

Claims (9)

  1. A lighting device comprising: a white light source that includes a blue light-emitting element and a yellow phosphor, and emits a first white light; and a color conversion element that converts the first white light to a second white light, wherein 2500 ≤ TG / TB × T 2 ≤ 5000 and T 1 − T 2 ≥ 300 are satisfied, where: TB is an average transmittance of the color conversion element in a range of from 435 nm to 480 nm, inclusive; TG is an average transmittance of the color conversion element in a range of from 540 nm to 590 nm, inclusive; T1 is a color temperature of the first white light for which a unit of measurement is K; and T2 is a color temperature of the second white light for which a unit of measurement is K.
  2. The lighting device according to claim 1, further comprising: a first optical system that is disposed between the white light source and the color conversion element, and converts the first white light emitted from the white light source to a parallel light.
  3. The lighting device according to claim 1, further comprising: a second optical system that projects the second white light that exits from the color conversion element.
  4. The lighting device according to any one of claims 1 to 3, wherein the white light source includes a plurality of blue light-emitting elements arranged in a two-dimensional matrix, the plurality of blue light-emitting elements each being the blue light-emitting element, and the yellow phosphor is disposed on a side toward which the plurality of blue light-emitting elements emit light.
  5. The lighting device according to any one of claims 1 to 3, wherein the blue light-emitting element is a blue light semiconductor laser element.
  6. The lighting device according to any one of claims 1 to 3, wherein the color conversion element is a dichroic filter.
  7. The lighting device according to any one of claims 1 to 3, wherein a minimum value of transmittance of the color conversion element in a range of from 400 nm to 450 nm, inclusive, is smaller than a minimum value of transmittance of the color conversion element in a range of from 525 nm to 575 nm, inclusive.
  8. The lighting device according to any one of claims 1 to 3, wherein a maximum value of transmittance of the color conversion element in a range of from 450 nm to 500 nm, inclusive, and a maximum value of transmittance of the color conversion element in a range of from 600 nm to 750 nm, inclusive, are at least 90 percent.
  9. A color conversion element that converts a first white light to a second white light, wherein 2500 ≤ TG / TB × T 2 ≤ 5000 and T 1 − T 2 ≥ 300 are satisfied, where: TB is an average transmittance of the color conversion element in a range of from 435 nm to 480 nm, inclusive; TG is an average transmittance of the color conversion element in a range of from 540 nm to 590 nm, inclusive; T1 is a color temperature of the first white light for which a unit of measurement is K; and T2 is a color temperature of the second white light for which a unit of measurement is K.

Description

[Technical Field] The present invention relates to a lighting device and a color conversion element. [Background Art] Patent Literature (PTL) 1 discloses an optical filter that includes an optical multi-layer film for which an average reflectance of light in a wavelength range of from green light to yellow light and a wavelength range of blue light is selectively enhanced. The optical filter disclosed in PTL 1 is described as being capable of enhancing color rendering properties while inhibiting light-emission efficiency from decreasing and color temperature from changing. [Citation List] [Patent Literature] [PTL 1] Japanese Patent No. 6058948 [Summary of Invention] [Technical Problem] The present invention provides a lighting device and a color conversion element that can achieve both enhanced color rendering properties and reduced color temperatures. [Solution to Problem] A lighting device according to one aspect of the present invention includes: a white light source that includes a blue light-emitting element and a yellow phosphor, and emits a first white light; and a color conversion element that converts the first white light to a second white light, wherein 2500 ≤ (TG / TB) × T2 ≤ 5000 and T1 - T2 ≥ 300 are satisfied, where: TB is an average transmittance of the color conversion element in a range of from 435 nm to 480 nm, inclusive; TG is an average transmittance of the color conversion element in a range of from 540 nm to 590 nm, inclusive; T1 is a color temperature of the first white light for which a unit of measurement is K; and T2 is a color temperature of the second white light for which a unit of measurement is K. A color conversion element according to one aspect of the present invention is a color conversion element that converts the first white light to a second white light, wherein 2500 ≤ (TG / TB) × T2 ≤ 5000 and T1 - T2 ≥ 300 are satisfied, where: TB is an average transmittance of the color conversion element in a range of from 435 nm to 480 nm, inclusive; TG is an average transmittance of the color conversion element in a range of from 540 nm to 590 nm, inclusive; T1 is a color temperature of the first white light for which a unit of measurement is K; and T2 is a color temperature of the second white light for which a unit of measurement is K. [Advantageous Effects of Invention] According to the present invention, enhanced color rendering properties and reduced color temperatures can both be achieved. [Brief Description of Drawings] [FIG. 1] FIG. 1 is a schematic perspective view of a lighting device according to an embodiment.[FIG. 2] FIG. 2 is a diagram that illustrates a configuration of the lighting device according to the embodiment.[FIG. 3] FIG. 3 is a schematic plan view of a white light source of the lighting device according to the embodiment.[FIG. 4] FIG. 4 is a schematic cross-sectional view of a white light-emitting element of the lighting device according to the embodiment.[FIG. 5] FIG. 5 is a diagram that illustrates transmittance of a color conversion element according to a comparative example and light intensity before and after light passes through the color conversion element.[FIG. 6] FIG. 6 is a diagram that illustrates transmittance of a color conversion element according to Working Example 1 and light intensity before and after light passes through the color conversion element.[FIG. 7] FIG. 7 is a diagram that illustrates transmittance of a color conversion element according to Working Example 2 and light intensity before and after light passes through the color conversion element.[FIG. 8] FIG. 8 is a diagram that illustrates transmittance of a color conversion element according to Working Example 3 and light intensity before and after light passes through the color conversion element.[FIG. 9] FIG. 9 is a diagram that illustrates transmittance of a color conversion element according to Working Example 4 and light intensity before and after light passes through the color conversion element.[FIG. 10] FIG. 10 is a diagram that illustrates transmittance of a color conversion element according to Working Example 5 and light intensity before and after light passes through the color conversion element.[FIG. 11] FIG. 11 is a diagram that illustrates transmittance of a color conversion element according to Working Example 6 and light intensity before and after light passes through the color conversion element.[FIG. 12] FIG. 12 is a diagram that illustrates transmittance of a prototype of the color conversion element for which data is shown in FIG. 7 and light intensity before and after light passes through the prototype.[FIG. 13] FIG. 13 is a diagram that illustrates transmittance of a prototype of the color conversion element for which data is shown in FIG. 10 and light intensity before and after light passes through the prototype.[FIG. 14] FIG. 14 is a diagram that illustrates transmittance of a prototype of the color conversion element for which data is shown in FIG. 11