JP2019179632A - Luminaire - Google Patents

Abstract

To provide a luminaire which uses a laser light source and a phosphor suppressing color irregularity without any expansion of a light distribution resulting from suppression on generation of color irregularity due to a difference in emission region size between laser light and phosphor emitted light.SOLUTION: A luminaire 100 comprises: a light source 1 which emits light; a phosphor 2 which transmits the light emitted from the light source 1 and is excited with the light to emit fluorescent light; and a volume phase type optical element 5 which equalizes a light distribution angle of the light transmitted through the phosphor 2 to a light distribution angle of the fluorescent light.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lighting device using a phosphor.

  Conventionally, what uses a laser light source is known as an illuminating device using a fluorescent substance. In the illumination device using the laser light source, the size of the light emission region of the laser light passing through the phosphor surface is different from the size of the light emission region of the phosphor emission light that is fluorescence emitted from the phosphor. For this reason, color unevenness occurs in the illumination light in which the laser light and the phosphor emission light (fluorescence) are mixed. For the purpose of suppressing the occurrence of color unevenness, Patent Document 1 discloses an illumination device provided with a light mixing layer that diffuses light in the vicinity of a phosphor surface. In Patent Document 1, laser light and phosphor emission light are multiple-scattered in the light mixing layer, and laser light and phosphor emission light are emitted isotropically, thereby improving color uniformity. It is what.

JP 2012-54084 A

  However, the illumination device disclosed in Patent Document 1 expands the light emission region of the laser light and the phosphor light emitted from the phosphor due to the diffusion effect of the light mixing layer. For this reason, the light distribution is expanded.

  The present invention has been made to solve the above-described problems, and provides an illumination device that suppresses color unevenness without expanding the light distribution.

  An illumination device according to the present invention includes a light source that emits light, a phosphor that transmits light emitted from the light source, and that emits fluorescence when excited by light, and a light distribution angle of the light that has passed through the phosphor. And a volume phase optical element that matches the light distribution angle of the fluorescence.

  According to the present invention, the volume phase optical element makes the light distribution angle of the light transmitted through the phosphor coincide with the light distribution angle of the fluorescence. For this reason, the light distribution angle is not wider than the fluorescence, and the occurrence of color unevenness can be suppressed. Therefore, color unevenness can be suppressed without expanding the light distribution.

It is a schematic diagram which shows the illuminating device 100 which concerns on Embodiment 1 of this invention. It is a figure which shows the optical path of the light which injected into the fluorescent substance 2 which concerns on Embodiment 1 of this invention. It is a figure which shows the light emission area | region of the light on the fluorescent substance 2 output surface which concerns on Embodiment 1 of this invention. It is a figure which shows the optical path of the light radiate | emitted from the illumination lens 4 which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the illuminating device 200 which concerns on a comparative example.

Embodiment 1 FIG.
Hereinafter, embodiments of a lighting device according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an illumination device 100 according to Embodiment 1 of the present invention. As shown in FIG. 1, the illumination device 100 includes a light source 1, a condenser lens 3, a phosphor 2, an illumination lens 4, and a volume phase optical element 5. The light source 1 is made of, for example, a semiconductor laser diode and emits blue light. The condenser lens 3 is provided in the emission direction of the light emitted from the light source 1 and is made of an optical member, and condenses the light emitted from the light source 1 on the phosphor 2. In FIG. 1, a solid line arrow indicates fluorescence and a broken line arrow indicates transmitted light.

  FIG. 2 is a diagram showing an optical path of light incident on the phosphor 2 according to Embodiment 1 of the present invention. The phosphor 2 is provided in the emission direction of the light emitted from the condensing lens 3, transmits the light emitted from the light source 1 and collected by the condensing lens 3, and is excited by the light to give fluorescence (phosphor Emission light). The phosphor 2 is made of, for example, YAG and is excited by blue light to generate yellow fluorescence. A part of blue light transmitted without being absorbed by the phosphor 2 and yellow fluorescence are mixed and incident on the illumination lens 4. A mixture of blue light and yellow fluorescence results in pseudo white light. As shown in FIG. 2, the light incident on the phosphor 2 is diffused inside the phosphor 2, propagates inside the phosphor 2, and is excited. On the other hand, a part of the light incident on the phosphor 2 is transmitted without being diffused.

  FIG. 3 is a diagram showing a light emission region of light on the emission surface of phosphor 2 according to the first embodiment of the present invention. Since the fluorescence that has been propagated and excited inside the phosphor 2 is diffused inside the phosphor 2, the emission region when emitted from the phosphor 2 is wide. On the other hand, since the light transmitted through the phosphor 2 is not diffused, the light emitting region is narrower than the fluorescence. For this reason, as shown in FIG. 3, the fluorescence emission region on the emission surface of the phosphor 2 has a wider range than the emission region of the transmitted light.

  FIG. 4 is a diagram showing an optical path of light emitted from the illumination lens 4 according to Embodiment 1 of the present invention. The illumination lens 4 is provided in the emission direction of the light emitted from the phosphor 2, and controls the light distribution of the light in which a part of the light transmitted without being absorbed by the phosphor 2 and the fluorescence are mixed. As shown in FIG. 4, the illumination lens 4 is arranged so that the focal point is located on the light emitting surface of the phosphor 2. For this reason, light emitted from an arbitrary point on the emission surface of the phosphor 2 is emitted from the illumination lens 4 as parallel light. Since the light emitting region on the emission surface of the phosphor 2 depends on the irradiation spot size of the light emitted from the light source 1, it does not become a point but has a spread. The light emitted from each point in the light emitting region becomes the outgoing light having a light distribution angle (divergence angle) depending on the area of the light emitting region as a whole, as the combined light of the light that has become parallel light by the illumination lens 4. The light is emitted from the illumination lens 4.

  The volume phase type optical element 5 is provided in the emission direction of the light emitted from the illumination lens 4 and matches the light distribution angle of the light transmitted through the phosphor 2 with the light distribution angle of the fluorescence. The volume phase optical element 5 controls the light distribution of light having a wavelength emitted from the light source 1. In the first embodiment, the volume phase optical element 5 is optimized for blue light, controls the light distribution angle of only blue light, and matches the fluorescence light distribution angle. It is.

  The volume phase type diffractive lens is manufactured by irradiating a hologram light sensitive material with two light beams having high coherence such as laser light and recording the interference state as interference fringes of refractive index in the hologram light sensitive material. . Examples of the hologram sensitive material include silver salt emulsion, dichromated gelatin, and photopolymer. When one volume of light beam applied at the time of fabrication is applied to the volume phase diffraction lens, the other beam is reproduced as a hologram. The volume phase type diffractive lens has high diffraction efficiency because light is diffracted by Bragg diffraction, which is light wave interference from many interference fringe surfaces. The volume phase type diffractive lens diffracts only light having a wavelength close to the wavelength used at the time of manufacture, and does not exert a diffractive action on light having a different wavelength. That is, the volume phase type diffractive lens is optimized for the light having the wavelength used in the production. Laser light generally has a narrow wavelength range, but the volume phase type diffractive lens can selectively control the light distribution angle of only blue laser light, for example, even if the wavelength range is narrow. In the first embodiment, the volume phase optical element 5 has the same light distribution angle as the blue luminous flux corresponding to the blue light after passing through the illumination lens 4 and the yellow fluorescence after passing through the illumination lens 4. The hologram recording is performed by causing the blue light beam to interfere with the hologram recording.

  Next, the light distribution of the illumination device 100 will be described with reference to FIG. Blue light emitted from the light source 1 is condensed and irradiated on the phosphor 2 by the condenser lens 3. A part of the blue light incident on the phosphor 2 is absorbed by the phosphor 2 as fluorescence, and yellow emission light that is fluorescence emitted from the phosphor 2 is emitted from the phosphor 2. The remaining blue light that has not been absorbed by the phosphor 2 is transmitted through the phosphor 2 and mixed with the yellow fluorescence emitted from the phosphor 2 to become pseudo white.

  As described above, the fluorescence emission region on the emission surface of the phosphor 2 has a wider range than the light emission region of the light transmitted through the phosphor 2. The fluorescence and the light transmitted through the phosphor 2 are converted into parallel light by the illumination lens 4. Here, among the parallel lights, the light distribution angle of the fluorescence is wider than the light distribution angle of the light transmitted through the phosphor 2 because the emission region is wider than the light transmitted through the phosphor 2.

  The volume phase optical element 5 causes the blue luminous flux corresponding to the blue light after passing through the illumination lens 4 to interfere with the blue luminous flux having the same light distribution angle as the yellow fluorescence after passing through the illumination lens 4. It is manufactured by recording a hologram. Thus, when blue light after passing through the illumination lens 4 that is the same light flux as one of the light fluxes at the time of recording is incident, a blue light flux having the same light distribution angle as yellow fluorescence after passing through the illumination lens 4 as the other light flux. Is played. Thereafter, the light distribution angle of the blue light after passing through the illumination lens 4 becomes the same as the light distribution angle of the yellow fluorescence.

  On the other hand, the volume phase optical element 5 does not change the light distribution angle of the yellow phosphor 2 because the wavelengths of the yellow fluorescence and the recorded light are different. That is, the blue light and the yellow fluorescence after passing through the volume phase optical element 5 become light beams having the same light distribution angle. Thus, the illumination device 100 selectively controls the blue light by the volume phase optical element 5 and matches the light distribution angle of the yellow fluorescence, so that the distribution of the light emitted from the illumination device 100 is the same. The light angle does not spread beyond the light distribution angle of yellow fluorescence. In addition, since the light distribution angle of blue light is matched with the light distribution angle of yellow fluorescence, it is possible to suppress the occurrence of color unevenness on the irradiation surface of the illumination device 100.

  FIG. 5 is a schematic diagram showing an illumination device 200 according to a comparative example. The illumination device 200 according to the comparative example does not have the volume phase optical element 5. The light distribution angle of the fluorescence is wider than the light distribution angle of the light transmitted through the phosphor 2 because the emission region is wider than the light transmitted through the phosphor 2. For this reason, when illumination light is irradiated to the irradiation target, color unevenness occurs in which the central portion is blue and the peripheral portion is yellow. On the other hand, since the first embodiment includes the volume phase optical element 5, the light distribution angle of blue light coincides with the light distribution angle of yellow fluorescence. Therefore, the occurrence of color unevenness on the irradiation surface of the illumination device 100 can be suppressed.

  As described above, according to the first embodiment, the volume phase optical element 5 matches the light distribution of the light transmitted through the phosphor 2 and the light distribution of the fluorescence. For this reason, the light distribution angle is not wider than the fluorescence, and the occurrence of color unevenness can be suppressed. Therefore, color unevenness can be suppressed without expanding the light distribution.

  In the first embodiment, the case where the volume phase optical element 5 is separate from the illumination lens 4 is illustrated, but the volume phase optical element 5 and the illumination lens 4 may be integrated. Good. In this case, the volume phase optical element 5 is formed on the entrance surface or the exit surface of the illumination lens 4. Thus, by integrating the volume phase optical element 5 and the illumination lens 4, the number of optical elements through which light passes is reduced, so that the light transmittance can be improved. Therefore, the light efficiency equivalent to that of the illumination device 100 that does not have the volume phase optical element 5 can be obtained. Further, when the lighting device 100 is assembled, the labor of adjusting the optical axis alignment and distance alignment between the illumination lens 4 and the volume phase optical element 5 can be saved.

  DESCRIPTION OF SYMBOLS 1 Light source, 2 Phosphor, 3 Condensing lens, 4 Illumination lens, 5 Volume phase type optical element, 100 Illumination device, 200 Illumination device.

Claims (4)

A light source that emits light;
A phosphor that transmits light emitted from the light source and emits fluorescence when excited by the light; and
A volume phase optical element that matches the light distribution angle of the light transmitted through the phosphor and the light distribution angle of the fluorescence;
A lighting device comprising: The volume phase optical element is
The illumination device according to claim 1, wherein the light distribution of light having a wavelength emitted from the light source is controlled. The illumination device according to claim 1, further comprising an illumination lens that controls light distribution between the fluorescence emitted from the phosphor and the light transmitted through the phosphor. The volume phase optical element is
The illumination device according to claim 3, wherein the illumination device is formed on an incident surface or an exit surface of the illumination lens.

Images