JP2012039000A - Light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reduce color shading of a light source device having light-emitting elements.SOLUTION: Since the optical path length, i.e. the distance which the light emitted from an LED chip 3 (a light-emitting element) passes through a sealing body 4, is adjusted over the whole azimuth angle with reference to the optical axis so that luminous intensity distribution of the LED chip 3 matches that of a phosphor, luminous intensity distribution and chromaticity distribution of a light source device 1 can be made uniform over the whole azimuth angle with reference to the optical axis. As a result, color shading of the light source device 1 can be reduced more effectively.

Description

  The present invention relates to a light source device using a light emitting element as a light source.

  Conventionally, a light emitting device that emits blue light (blue LED chip) and a phosphor that absorbs blue light emitted from the light emitting device and converts the wavelength (yellow phosphor) are emitted from the light emitting device. There is known a light source device that emits white (pseudo-white) light using a mixed color of the emitted blue light and yellow light emitted from a phosphor. In such a light source device, one of the technical problems is to eliminate the color unevenness caused by the light distribution characteristics of the light emitted from the light emitting element, so-called yellow ring.

  Therefore, in Patent Document 1, a semiconductor light-emitting element mounted on a support substrate is sealed with a transparent first sealing material, and this first sealing material is used as a second material containing a phosphor. The thickness of the second sealing material containing phosphor according to the directivity characteristics (light distribution characteristics or orientation distribution) of the light emission intensity of the light emitted from the semiconductor light emitting element. In other words, a semiconductor light-emitting device that sets the thickness, in other words, a semiconductor light-emitting device in which phosphors are distributed / arranged in each part of the light-emitting device according to the amount of light passing through the second sealing material is disclosed.

JP 2010-62286 A

  However, according to a detailed examination by the present inventor (applicant), even with the light emitting device having the configuration disclosed in Patent Document 1, color unevenness is not sufficiently suppressed, and there is still room for improvement. It had been. Accordingly, the present invention has been made in view of such circumstances, and an object thereof is to more effectively suppress color unevenness of a light source device having a light emitting element based on a novel idea.

  By the way, the applicant of the present application covers a blue LED chip with a hemispherical phosphor layer having a constant radius (not including a scatterer), and the phosphor layer is covered with a lens having a hemispherical outer shape (light source device). ) Was measured using an optical filter. As a result, as shown in FIG. 3, the light distribution of the light emitted from the phosphor (λ> 500 nm) has an omnidirectional angle (range of ± 90 °) with the optical axis as a reference (azimuth angle 0 °). It was almost uniform. That is, it was found that the light emitted from the phosphor has a small orientation angle dependency and a uniform orientation distribution over a wide angle range.

  In contrast, the light distribution of the light emitted from the light emitting device (λ <460 nm) emitted from the blue LED chip shows a clear trimodality, and the light emitted from the blue LED chip (transmits through the phosphor layer). The light distribution distribution of the light directly emitted without being shown (not shown) was substantially the same. That is, it was found that the light scattering effect by the phosphor is small, and the light emitted from the blue LED chip maintains the orientation distribution even when passing through the phosphor layer.

  The present invention has been invented based on the above findings, and has been completed through various studies. Accordingly, the light source device of the present invention includes a light emitting element and a sealing body that covers the light emitting element that contains a scatterer and a phosphor and is mounted on the mounting substrate, and the sealing body includes the light emitting element. The light distribution distribution after the light emitted from the element and passed through the sealing body is configured to match the light distribution distribution after the light emitted from the phosphor and passed through the sealing body. It is characterized by that.

  According to the present invention, color unevenness of a light source device having a light emitting element can be more effectively suppressed.

It is the schematic for demonstrating the structure of 1st Embodiment. It is explanatory drawing of 1st Embodiment, Comprising: Light distribution chromaticity distribution (before improvement) of one light source device of a prior art, Light distribution chromaticity distribution (after improvement) of the light source device to which 1st Embodiment is applied, FIG. It is explanatory drawing of 1st Embodiment, Comprising: It is a figure which shows each light distribution of the light emitting element and fluorescent substance using a filter, and the light distribution which does not use a filter in one light source device of a prior art. . It is explanatory drawing of 1st Embodiment and 2nd Embodiment, Comprising: The distance which the light radiate | emitted from the light emitting element passes through a sealing body and a scatterer layer is adjusted over the omnidirectional angle on the basis of an optical axis It is a figure which shows each light distribution of the light emitting element and fluorescent substance using a filter after having performed. It is sectional drawing of a part (upper part from a mounting surface) of the light source device of 1st Embodiment. It is a figure which shows the optical path length in the omnidirectional angle on the basis of the optical axis of the light source device of FIG. It is the schematic for demonstrating the structure of 2nd Embodiment.

(First embodiment)
A first embodiment of the present invention will be described with reference to the accompanying drawings. As shown in FIG. 1, the light source device 1 of the first embodiment includes a mounting board 2, an LED chip 3 (light emitting element) that is mounted on the mounting board 2 and emits blue light, and the LED chip 3. And a hemispherical transparent lens 5 provided on the mounting substrate 2 so as to cover the sealing body 4. In the present embodiment, the mounting substrate 2 is a ceramic substrate, and silver plating that has both a function as an electrode and a function as a reflector is applied to substantially the entire mounting surface 2a. The LED chip 3 and the driving method of the LED chip 3 are assumed to use the prior art as they are, and detailed description thereof is omitted here.

  The sealing body 4 uses a silicone resin as a sealing material. Moreover, the sealing body 4 contains scatterers, such as an alumina, by predetermined concentration, for example. Thus, the sealing body 4 is constituted by the scatterer layer 6 in which the scatterers are uniformly distributed in the silicone resin (sealing material). In addition, the scatterer layer 6 is a photoluminescent phosphor (yellow phosphor, hereinafter referred to as a phosphor) that absorbs a part of blue light emitted from the LED chip 3 and converts the wavelength. It is contained at a volume concentration lower than that of the scatterer. In addition, the phosphor is uniformly distributed in the sealing body 4 (or sealing material) like the scatterer. The light source device 1 is configured to emit white (pseudo-white) light using a color mixture of blue light emitted from the LED chip 3 and yellow light emitted from the phosphor. ing.

  It is preferable that the lens 5 is formed sufficiently large with respect to the sealing body 4 so that the sealing body 4 looks like a point light source. 5 is shown relatively small). Furthermore, it is preferable that the sealing body 4 is also formed sufficiently larger than the LED chip 3. Further, the sealing body 4 has a distance (L in FIG. 1, hereinafter referred to as an optical path length) through which the light emitted from the LED chip 3 passes through the sealing body 4 is based on the optical axis of the LED chip 3 (azimuth angle). Adjustment is made for each azimuth angle (θ = 0 °) (in the first embodiment, θ is in a range of ± 90 ° in FIG. 1). More specifically, the optical path length L is adjusted for each azimuth angle so that the light distribution chromaticity (color tone) of the light source device 1 is uniform. Specifically, the optical path length L is the light distribution (hereinafter also referred to as the orientation distribution of the LED chip 3) emitted from the LED chip 3 and passed through the sealing body 4 is emitted from the phosphor. Thus, it is adjusted for each azimuth angle so as to coincide with the light distribution of light after passing through the sealing body 4 (hereinafter also referred to as the orientation distribution of the phosphor).

  Next, the operation of the first embodiment will be described. FIG. 2 shows a light distribution chromaticity distribution (hereinafter referred to as a light distribution chromaticity distribution before improvement) of a general one light source device (top view type LED having a lamp house) currently on the market. The light distribution chromaticity distribution of the light source device to which the technique of the first embodiment is applied (hereinafter referred to as an improved light distribution chromaticity distribution) is compared. As shown in this figure, the light distribution chromaticity distribution before the improvement is in a region where the azimuth angle θ is 60 ° or more (and −60 ° or less) with the optical axis as a reference (azimuth angle θ = 0 °). The amount of change in chromaticity is remarkably large. In other words, in the light source device before improvement, color unevenness occurs in a region where the azimuth angle θ is 60 ° or more (and −60 ° or less).

  Next, a blue LED chip is covered with a hemispherical phosphor layer (not including a scatterer) having a constant radius, and the light distribution of the light source device in which the phosphor layer is covered with a hemispherical lens is filtered. As a result of using and measuring, as shown in FIG. 3, the light distribution (λ> 500 nm) of the phosphor was uniform for all azimuth angles with the optical axis as a reference (azimuth angle θ = 0 °). On the other hand, the light distribution (λ <460 nm) of the LED chip 3 (light emitting element) is substantially the same as the light distribution (not shown) when the filter is not used, and is trimodal (complex) Characteristic). Therefore, in the first embodiment, as shown in FIG. 4, the light distribution of the LED chip 3 is matched with the light distribution of the phosphor. Specifically, as shown in FIG. 5, a step shape in which two cylindrical bodies (disks) having different outer diameters are stacked in the optical axis direction (vertical direction in FIG. 5), in other words, the LED chip 3 is formed. The sealing body 4 was formed in a shape in which a cylindrical body having an outer diameter smaller than that of the cylindrical body was coaxially stacked on the cylindrical body (disk) to be covered. Here, in the sealing body 4 formed in this way, the optical path length of all azimuth angles with respect to the optical axis, that is, the distance L through which the light emitted from the LED chip 3 passes through the sealing body 4, As shown in FIG. Here, the optical path length L is a linear distance from the center position of the LED chip 3 to the outer surface of the sealing body 4 that does not consider displacement due to light diffusion.

  Here, the shape of the sealing body 4 is derived by trial and error, but by storing data, what shape should the sealing body 4 be formed from the light distribution? It becomes easy to understand. That is, by accumulating the correspondence between the light distribution shown in FIG. 3 and the optical path length shown in FIG. 6 as data, the shape of the sealing body 4 can be determined based on the accumulated data. The sealing body 4 is integrally formed, and there is no boundary between the lower columnar body and the upper columnar body in FIG. Moreover, in 1st Embodiment, the sealing body 4 uses the silicone resin whose refractive index of resin is 1.40-1.55 as a sealing material. Further, as the sealing body 4, a material containing alumina (scattering body) having a refractive index of 1.77 and a particle diameter of 5 μm at a volume concentration of 3% is used.

  In the first embodiment, the optical path length is adjusted over all azimuth angles with respect to the optical axis so that the light distribution of the LED chip 3 matches the light distribution of the phosphor (see FIG. 4). As a result, the sealing body 4 was formed in the step shape shown in FIG. As a result, as shown in FIG. 2, the light distribution chromaticity distribution of the light source device 1 can be made uniform over all azimuth angles with respect to the optical axis. As a result, the prior art (before improvement) is achieved. As a result, it is possible to obtain the light source device 1 in which the color unevenness is significantly improved.

  According to the first embodiment, the light path length, that is, the light emitted from the LED chip 3 is sealed so that the light distribution of the LED chip 3 (light emitting element) matches the light distribution of the phosphor. Is adjusted over the omnidirectional angle with respect to the optical axis, the light distribution chromaticity distribution of the light source device 1 can be made uniform over the omnidirectional angle with respect to the optical axis. As a result, the color unevenness of the light source device 1 can be more effectively suppressed. As a secondary matter, the orientation distribution as white light can be made uniform over a wide angular range.

In addition, embodiment is not limited above, For example, it can comprise as follows.
The shape of the sealing body 4 is determined so that the light distribution of the LED chip 3 (light emitting element) matches the light distribution of the phosphor. Therefore, the shape of the sealing body 4 is not limited to a step shape. For example, when the volume concentration of the scatterer (alumina) in the sealing body 4 is 0.3%, it is more preferable to form the sealing body 4 in a truncated cone shape.
In the first embodiment, the light source device 1 is configured by covering the sealing body 4 with the hemispherical transparent lens 5. However, the lens 5 is not an essential configuration, and the light source device 1 is configured without using the lens 5. You can also.
In addition, the light source device 1 can be configured by arranging a plurality of LED chips 3 (light emitting elements) on the mounting substrate 2. In this case, the optical path length L, that is, the center of symmetry of each LED chip 3 is measured from the symmetry center of each LED chip 3 so that the orientation distribution obtained by synthesizing the light distribution of each LED chip 3 matches the light distribution of the phosphor. The linear distance L to the outer surface may be adjusted over all azimuth angles with the optical axis as a reference.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to the accompanying drawings. In addition, about the structure which is the same as that of 1st Embodiment mentioned above, or equivalent, the same name and code | symbol are provided, and the detailed description is abbreviate | omitted.
As shown in FIG. 7, in the second embodiment, the sealing body 4 includes a scatterer layer 6 that covers the LED chip 3 (light emitting element) mounted on the mounting substrate 2, and a fluorescence that covers the scatterer layer 6. And body layer 7. In the scatterer layer 6, a silicone resin is used as a sealing material, and alumina as a scatterer is uniformly contained at a predetermined volume concentration. In the present embodiment, the phosphor layer 7 uses the same silicone resin as the scatterer layer 6 as a sealing material, and the photoluminescence phosphor (yellow phosphor) is based on the volume concentration of the scatterer in the scatterer layer 6. Is uniformly contained at a low concentration.

  In the second embodiment, the sealing body 4 is configured such that the distance W (optical path length) through which the light emitted from the LED chip 3 passes through the phosphor layer 7 is based on the optical axis of the LED chip 3 (azimuth angle θ = 0 °) is constant over an omnidirectional angle (in the second embodiment, θ is in a range of ± 90 ° in FIG. 7). In the scatterer layer 6, the distance L (optical path length) through which the light emitted from the LED chip 3 passes through the scatterer layer 6 is adjusted for each azimuth angle with respect to the optical axis of the LED chip 3. More specifically, the optical path length L of the light passing through the scatterer layer 6 is adjusted for each azimuth angle so that the light distribution chromaticity (color tone) of the light source device 1 is uniform. Specifically, the light path length L of the light passing through the scatterer layer 6 is such that the light distribution after the light emitted from the LED chip 3 and passed through the scatterer layer 6 is emitted by the phosphor. Adjustment is made for each azimuth angle with respect to the optical axis so as to match the light distribution of the light emitted from the layer 7.

  In addition, FIG. 7 is for demonstrating the outline of a structure of 2nd Embodiment. Therefore, in FIG. 7, the distance W (optical path length) that the light emitted from the LED chip 3 passes through the phosphor layer 7 is constant over all azimuth angles with respect to the optical axis of the LED chip 3. It has not been.

  Next, the operation of the second embodiment will be described. In the second embodiment, as shown in FIG. 4, the light emitted from the LED chip 3 and passing through the scatterer layer 6 so that the light distribution of the LED chip 3 matches the light distribution of the phosphor. By adjusting the optical path length L over all azimuth angles with reference to the optical axis, the light distribution chromaticity distribution of the light source device 1 can be made uniform over all azimuth angles with reference to the optical axis. As a result, it is possible to obtain the light source device 11 in which the color unevenness is significantly improved as compared with the prior art (before improvement). Note that the adjustment of the shape of the scatterer layer 6, that is, the optical path length L of the light emitted from the LED chip 3 and passing through the scatterer layer 6, can be derived by trial and error as in the first embodiment.

  According to the second embodiment, in order to make the light distribution of the LED chip 3 (light emitting element) coincide with the light distribution of the phosphor, the distance W (the light emitted from the LED chip 3 passes through the phosphor layer 7 ( (Optical path length) is made constant over all azimuth angles with respect to the optical axis of the LED chip 3, and the distance L (optical path length) of the light emitted from the LED chip 3 and passing through the scatterer layer 6 is defined as the optical axis. Therefore, the light distribution chromaticity distribution of the light source device 11 can be made uniform over the omnidirectional angle with respect to the optical axis, and as a result, the light source device 11 can be made uniform. Color unevenness can be more effectively suppressed.

DESCRIPTION OF SYMBOLS 1 Light source device, 2 Mounting board, 3 LED chip (light emitting element), 4 Sealing body, 5 Lens, 6 Scattering body layer, 7 Phosphor layer

Claims (7)

A light-emitting element, and a sealing body that covers the light-emitting element mounted on the mounting substrate containing a scatterer and a phosphor, and
In the sealing body, the light distribution of light after being emitted from the light emitting element and passing through the sealing body is the light distribution of light after being emitted from the phosphor and passed through the sealing body. It is comprised so that it may correspond to, and the light source device characterized by the above-mentioned. The light source device according to claim 1, wherein the sealing body is configured by distributing the phosphor in a scatterer layer that contains the scatterer and covers the light emitting element. The said sealing body is set according to the azimuth | direction angle on the basis of an optical axis, The distance through which the light radiate | emitted from the said light emitting element passes the said sealing body is set. Light source device. 4. The light source device according to claim 2, wherein the sealing body is formed in a step shape in which a plurality of cylindrical bodies having different outer diameters are stacked in the optical axis direction. The sealing body includes a scatterer layer that contains the scatterer and covers the light emitting element, and a phosphor layer that contains the phosphor and covers the scatterer layer. The light source device according to claim 1. The phosphor layer is formed such that the thickness in the emission direction of the light emitted from the light emitting element is constant over all azimuth angles with respect to the optical axis,
The distance from which the light radiate | emitted from the said light emitting element passes the said scatterer layer to the said scatterer layer is set according to the azimuth | direction angle on the basis of the said optical axis. Light source device. The light source device according to any one of claims 1 to 6, further comprising a lens on which light after passing through the sealing body is incident.

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