JPWO2008143183A1 - Glass-coated light emitting element, lighting device and projector device - Google Patents

Abstract

The light emitted from the semiconductor light emitting element can be efficiently introduced into the light control unit, and the alignment between the lens and the light emitting element is unnecessary, and the light emitted from the semiconductor light emitting element is efficiently extracted. Provided is a glass-coated light-emitting element that can be used. The semiconductor light emitting device 1 mounted on the substrate surface and emitting light of a predetermined wavelength band from the light emitting region, and the light emitting surface has a part of a spherical surface wider than the hemispherical surface, and the semiconductor light emitting device 1 on a surface other than the spherical surface Are integrated so as to cover the light emitting region of the semiconductor light emitting device 1 in a state of being opposed to each other, and the refractive index at the emission peak wavelength is 1.7 or more, and the ratio of the maximum diameter of the substrate surface of the semiconductor light emitting device to the diameter is The glass 2 which is at least 1.8 or more and the bonding surface 2A which is a light scattering portion that refracts the light existing inside the glass 2 without being emitted from the surface of the glass 2 are provided.

Description

  The present invention relates to a semiconductor light-emitting element coated with glass, that is, a glass-coated light-emitting element, an illumination device, and a projector device.

  BACKGROUND Semiconductor light-emitting elements typified by light-emitting diodes (LEDs) have features such as small size, high efficiency, and long life, and are used in various applications. For example, if an LED is used as a projector light source, the illumination system can be made compact because the LED is small, but the emitted light from the LED is non-directional, so the emitted light can be efficiently controlled by a liquid crystal panel, a micromirror array, etc. It is necessary to introduce to the department.

  Conventionally, in order to efficiently introduce such emitted light into the light control unit, a light emitting element with a lens, that is, various lenses manufactured separately so as to have a radiation angle and intensity distribution according to the purpose are attached with a holder such as a metal. The LED is adjusted and fixed in accordance with the position of a light emitting element such as an LED.

  However, such a conventional light emitting element with a lens includes a light emitting element, a lens and a fixing holder for the three parts, and an adjustment fixing process for these parts is also required, which is expensive. It was a thing. Further, there is a problem that the radiation intensity distribution is not always efficient with a normal lens shape.

In order to solve such problems, an illumination system using a light pipe has been proposed (see Patent Document 1). In such an illumination system, it is considered that the radiation intensity distribution is more efficient than the case where the lens-equipped light emitting element is used, but it is still necessary to align the light pipe with the light emitting element or the light control unit. Yes, it was insufficient to solve the problem.
JP-T-2006-505830

  According to the present invention, it is possible to efficiently introduce the light emitted from the semiconductor light emitting element into the light control unit, and it is not necessary to align the lens or the light pipe and the light emitting element as described above. In addition, an object of the present invention is to provide a glass-coated light-emitting element, an illumination device, and a projector device that can efficiently take out emitted light from a semiconductor light-emitting element as light for light emission and use it.

  The present invention has a semiconductor light emitting element and a surface from which the light emitted from the semiconductor light emitting element is emitted, and the surface has a spherical shape wider than a hemispherical surface and a part of a spherical notch. The glass is attached to the semiconductor light emitting element, the refractive index at the emission peak wavelength of the semiconductor light emitting element is 1.7 or more, and the ratio of the maximum diameter of the spherical notch to the diameter is at least 1.8 or more, There is provided a glass-coated light emitting device comprising: a light scattering portion that refracts light existing inside the glass without being emitted from the surface of the glass.

  The present invention also provides an illumination device including the glass-coated light emitting element and a field lens, and a projector device having the illumination device as a light source.

  According to the present invention, the coated glass has the same function as the lens or the light pipe, so that the alignment as described above is not necessary. That is, in the past, when using a lens to enhance directivity, the semiconductor light emitting element and the lens had to be arranged separately, so that they had to be aligned, but such alignment was not necessary. .

  In the present invention, when light is incident on the spherical glass from the light emitting element, the incident angle at the interface between the glass and the external air (hereinafter “glass interface”) exceeds the critical angle. Can return to the light emitting surface of the semiconductor light emitting device again by total reflection, but the light path can be changed by scattering at the light scattering portion, and the total reflection condition at the glass interface can be broken and emitted from the glass. Therefore, according to the present invention, it is possible to illuminate the emitted light from the semiconductor light emitting element as light for light emission efficiently and with an increased amount of light (irradiated surface with a desired irradiation pattern).

It is a conceptual diagram of the cross section of the light emitting element and wiring board of the glass covering light emitting element which concern on the 1st Embodiment of this invention. (A) is the expansion conceptual diagram of the cross section of the light emitting element and wiring board of the glass covering light emitting element, (B) is a schematic plan view which shows shapes, such as an electrode of the light emitting element. (A)-(D) are figures which show the calculation result (light quantity distribution) in case the refractive index of spherical glass is 1.5. (A)-(D) are explanatory drawings which show the calculation result (light quantity distribution) in case the refractive index of spherical glass is 2.0. (A) is a graph showing the irradiation light path from the non-directional light emitting element to the irradiation surface and the light quantity distribution on the irradiation surface, and (B) is the irradiation light path and irradiation surface from the glass-coated light emitting element of the present invention to the irradiation surface. It is a graph which shows light quantity distribution. It is a figure which shows the angle dependence of the emitted light of the glass covering light-emitting element of this invention. (A) is the optical path after exiting the spherical lens when the light emitting point A of the light emitting element is the rearmost point of the spherical lens, and (B) is the front of the light emitting point A in the irradiation direction from the rearmost point of the spherical lens. It is explanatory drawing which shows the optical path when it has shifted | deviated. It is explanatory drawing which shows the shift | offset | difference of the optical path by the spherical aberration in the glass-coated light emitting element of this invention. (A) is explanatory drawing which shows a total reflection area | region in the glass in the glass-coated light emitting element of this invention, (B) is an optical path figure which shows the optical path of illumination light when it radiate | emits from the inside of the glass. It is a conceptual diagram of the cross section of the glass-coated light emitting element which concerns on the 2nd Embodiment of this invention. (A), (B) is the conceptual diagram of the cross section of the glass-coated light-emitting device which concerns on the 3rd Embodiment of this invention, and its modification. It is a conceptual diagram of the cross section of the glass-coated light emitting element which concerns on the 4th Embodiment of this invention. It is a model figure which shows the setting conditions when performing the simulation which investigates illumination intensity distribution using the glass covering light-emitting device of this invention. It is a graph which shows illuminance distribution when a simulation is performed with the scattering rate at the reflector set to 0% (in this case, 100% regular reflection). It is a graph which shows the luminance distribution when it simulates by setting the scattering rate in a reflecting plate to 0% (in this case, 100% regular reflection). It is a graph which shows the in-plane illuminance distribution when it simulates by setting the scattering rate in a reflecting plate to 0% (in this case, 100% regular reflection). FIG. 14C is a contour diagram schematically showing FIG. 14C. It is a graph which shows illuminance distribution when simulating by setting the scattering rate in a reflector to 10%. It is a graph which shows luminance distribution when simulating by setting the scattering rate in a reflecting plate to 10%. It is a graph which shows the in-plane illumination intensity distribution when setting the scattering rate in a reflecting plate to 10%, and performing simulation. FIG. 15C is a contour diagram schematically showing FIG. 15C. It is a graph which shows illuminance distribution when simulating by setting the scattering rate in a reflecting plate to 30%. It is a graph which shows luminance distribution when simulating by setting the scattering rate in a reflecting plate to 30%. It is a graph which shows the in-plane illumination intensity distribution when simulating by setting the scattering rate in a reflecting plate to 30%. FIG. 16C is a contour diagram schematically showing FIG. 16C. It is a graph which shows illuminance distribution when simulating by setting the scattering rate in a reflector to 50%. It is a graph which shows luminance distribution when simulating by setting the scattering rate in a reflecting plate to 50%. It is a graph which shows the illumination intensity distribution in a plane when performing the simulation by setting the scattering rate in a reflecting plate to 50%. FIG. 17C is a contour diagram schematically showing FIG. 17C. It is a graph which shows illuminance distribution when simulating by setting the scattering rate in a reflecting plate to 60%. It is a graph which shows luminance distribution when simulating by setting the scattering rate in a reflector to 60%. It is a graph which shows the illumination intensity distribution in a plane when performing the simulation by setting the scattering rate in a reflecting plate to 60%. FIG. 18C is a contour diagram schematically showing FIG. 18C. It is a graph which shows illuminance distribution when simulating by setting the scattering rate in a reflecting plate to 70%. It is a graph which shows luminance distribution when simulating by setting the scattering rate in a reflector to 70%. It is a graph which shows the illuminance distribution in a plane when the scattering rate in a reflecting plate is set to 70%, and it simulates. FIG. 19C is a contour diagram schematically showing FIG. 19C. It is a graph which shows illuminance distribution when simulating by setting the scattering rate in a reflector to 90%. It is a graph which shows luminance distribution when simulating by setting the scattering rate in a reflector to 90%. It is a graph which shows the in-plane illumination intensity distribution when simulating by setting the scattering rate in a reflecting plate to 90%. FIG. 20C is a contour diagram schematically showing FIG. 20C. It is a graph which shows illuminance distribution when simulating by setting the scattering rate in a reflecting plate to 99%. It is a graph which shows luminance distribution when simulating by setting the scattering rate in a reflecting plate to 99%. It is a graph which shows the illuminance distribution in a plane when the scattering rate in a reflecting plate is set to 99%, and a simulation is performed. FIG. 21C is a contour map schematically showing FIG. 21C. It is a graph which shows the illumination intensity distribution when setting absorptance in a reflecting plate to 100%, and performing simulation. It is a graph which shows the luminance distribution when a simulation is performed with the absorptivity at the reflector set to 100%. It is a graph which shows the in-plane illumination intensity distribution when setting absorptance in a reflecting plate to 100%, and performing simulation. FIG. 22C is a contour diagram schematically showing FIG. 22C. It is a graph which shows the relationship between the scattering rate in a reflecting plate, and the total luminous flux. It is the block diagram and front view which show the illuminating device of this invention. It is a block diagram which shows the projector apparatus of this invention.

Explanation of symbols

1 Semiconductor light emitting device (light emitting device)
1A, 1B electrode
1C, 1D, 1E Mirror electrode 1F, 1G, 1H Transparent electrode 10, 20, 30A, 30B, 40 Glass-coated light-emitting element 10R, 10G, 10B Glass-coated light-emitting device 14 Transparent substrate 2 Spherical glass (glass)
2A Bonding surface 3 Wiring board 31 Substrate 31A Reflecting surface (scattering reflecting surface)
32 Wiring pattern 33 Bump 4 Filler 5 Mold part 50 Illumination device 60 Field lens (objective lens)
70R, 70G, 70B LCD (Liquid Crystal Display)
80 Multiplexing element 90 Projection lens 100 Projector

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a cross-sectional view showing a configuration of a glass-coated light emitting device (first light emitting device) according to the first embodiment of the present invention. The glass-coated light emitting element 10 includes a semiconductor light emitting element 1 and glass 2 and is disposed on a wiring board 3. Moreover, the fine processing which consists of fine unevenness is given to 2 A of joining surfaces with the semiconductor light-emitting device 1 of the glass 2 of this glass-coated light-emitting device 10. This fine processing (light scattering portion) scatters light that is emitted from the semiconductor light emitting element 1 and totally reflected by the spherical surface in the glass 2 and returned. This fine processing is formed, for example, by roughening the bonding surface 2A of the glass 2 using sandblasting, etching, or the like.

  A semiconductor light emitting element (light emitting element) 1 emits light in a predetermined wavelength band two-dimensionally from a surface having a light emitting region (hereinafter referred to as a light emitting surface), and is mounted on a wiring substrate 3. Here, the configuration of the light-emitting element 1 will be described with reference to FIG. The light emitting element 1 includes a transparent substrate 14, an n layer 12 formed on the transparent substrate 14, a light emitting layer 13 formed on the n layer 12, and a p layer 11 formed on the light emitting layer 13. . Electrodes 1 </ b> A and 1 </ b> B are provided on the p layer 11 and the n layer 12. The light emitting element 1 is so-called flip chip mounting. The electrodes 1A and 1B are connected to the wiring pattern 32 of the wiring board 3 via the bumps 33.

  In the first embodiment, the light emitting surface of the light emitting element 1 is the back surface of the transparent substrate 14 (the surface facing the bonding surface 2A of the glass 2). The light generated in the light emitting layer 13 travels in the direction of arrow A in FIG. 2A and is emitted through the transparent substrate 14. The electrodes 1A and 1B also have a function as a mirror for reflecting light that is totally reflected on the surface of the glass 2 and is not emitted from the surface of the glass 2 and returned to the electrodes 1A and 1B. In the first embodiment, a blue LED is used as the light emitting element 1, but it goes without saying that LEDs of other colors, laser diodes, and the like may be used.

  The light emitting element 1 is generally rectangular or square when viewed from above. The back surface of the transparent substrate 14 that is the light emitting surface of the light emitting element 1 may also be rectangular or square. Since the light generated from the light emitting layer 13 is emitted from the light emitting element 1 through the transparent substrate 14, the back surface of the transparent substrate 14 is considered to be the light emitting region of the light emitting element 1. The light emitting region is similar to the shape of the electrode (the region indicated by the oblique lines in FIG. 2B). Therefore, in order to obtain a desired projection shape, it is preferable that the shape of the electrode be a desired projection shape. As will be described later, the glass of the present invention has good directivity. In other words, the shape of the incident light can be projected to the outside as a substantially unchanged shape. That is, the light emitting surface of the glass-coated light emitting device of the present invention can be a light emitting surface that matches a desired projection surface. For example, the light emitting surface is rectangular or round, and the shape of the light emitting surface is irradiated. Thereby, it becomes possible to irradiate and illuminate the surface to be irradiated with light having various shape patterns, and the application of the illumination light source can be expanded.

  In addition, when the shape of the light-emitting element 2 viewed from above is a rectangle or a square, the maximum diameter L is the length of a diagonal line, and L is typically 400 to 1500 μm.

  The glass 2 covers the light emitting element 1, and the surface has a part of a spherical surface wider than the hemispherical surface and has a spherical shape (hereinafter “spherical glass”). Due to such a shape, the glass-coated light emitting device of the first embodiment can improve both the directivity and uniformity of the emitted light. The spherical glass 2 has a shape in which a sphere is cut at a joint surface with the light-emitting element 1 (a portion corresponding to the joint surface 2A in the first embodiment). Part 2C; see FIG. 7B and FIG.

As the spherical glass 2, for example, TeO ₂ 40 to 53%, GeO ₂ 0 to 10%, B ₂ O ₃ 5 to 30%, Ga ₂ O ₃ 0 to 10%, Bi ₂ O in terms of mol% based on oxide. _{3 0~10%, 3~20% ZnO,} Y 2 O 3 0~3%, La 2 O 3 0~3%, Gd 2 O 3 0~7%, Ta 2 O 5 0~5%, essentially from Glass is used. The glass may contain components other than the above components as long as the object of the present invention is not impaired. In that case, the total content of such components is preferably 10% or less, more preferably 5% or less. is there. Here, for example, “GeO ₂ 0 to 10%” means that GeO ₂ is not essential but may be contained up to 10%.

The refractive index n _p of the spherical glass 2 at the emission peak wavelength λ _p of the light emitting element 1 is 1.7 or more. If it is less than 1.7, the maximum illuminance or illuminance distribution described later becomes small. Preferably it is 1.8 or more, More preferably, it is 1.9 or more. Further, n _p is 2.3 or less, preferably 2.2 or less. Note that λ _p is generally 450 to 480 nm, particularly 450 to 460 nm for blue LEDs. Further, the light emitting element 1 is not limited to the blue LED, and one that emits light of various intrinsic wavelengths or specific wavelength bands can be used.

  When the diameter of the spherical surface of the spherical glass 2 is d and the diameter of the spherical portion is L, d / L (spherical portion ratio; the ratio of the maximum diameter of the spherical portion to the diameter) is at least 1.8, preferably 1.8. -3.5 (note that d is equal to the maximum horizontal width of the spherical notch 2C of the spherical glass 2 shown in FIG. 7B).

According to the experiments conducted by the present inventors, it is preferable that the maximum illuminance is 3 × 10 ⁻⁵ or more and the illuminance distribution is 0.35 or more. In this experiment, the spherical glass does not have a light scattering member, but there is no influence on the measurement result. Specifically, a light receiving surface was arranged in front of the light source, that is, on the outgoing light side, and the illuminance on the light receiving surface was calculated. The outgoing light from the light emitting element is non-directional and non-coherent in all directions of the outgoing light side space, and the refraction and reflection of the outgoing light are calculated according to the law of refraction and reflection (Snell's law). . The total light source intensity was normalized to 1 mW, and the number of emitted light rays was calculated as 1 million in total. It should be noted that the calculation was performed with the total light source intensity normalized to 1 mW for the sake of convenience, and the present invention is not limited to this. In this calculation, the polarization is not taken into account, and the light intensity is reduced due to multiple reflections. Was effective up to 0.0001%.

When L is 1 mm, the light-receiving surface is a square with a side of 15 mm, and the distance between the light-receiving surface and the point farthest from the spherical light-receiving surface, which is part of the spherical glass, is 19 mm. The illuminance at the light receiving surface is such that n _p is 1.5, 1.75, 2.0, 2.25, d is 1 mm, 2 mm, 3 mm, 4 mm, that is, d / L is 1 (when the spherical glass is a hemisphere), 2 Calculations were made for 3, 4 and 4 cases.

  Maximum illuminance (unit: mW) and illuminance distribution (unit:%) were read from the illuminance obtained by the calculation. The results are shown in Table 1 (maximum illuminance) and Table 2 (illuminance distribution).

  The illuminance distribution was read as follows. That is, the lateral length a and the lateral length b in which the illuminance is 80% or more of the maximum illuminance are obtained, and b / a is defined as the illuminance distribution. . The illuminance distribution at d = 1 mm could not be read because the effectively irradiated part was wider than the light receiving surface.

The light quantity distribution obtained by the above calculation is shown in FIGS. 3 (A) to 3 (D) and FIGS. 4 (A) to 4 (D). The illuminance distribution in the case where d is 2 mm, 3 mm, 4 mm, that is, d / L is 2, 3, 4 when n _p is 1.5 and 2.0 based on the smoothly drawn curves in each figure. I read it. The auxiliary lines for reading are also shown.

The maximum illuminance is preferably 3 × 10 ⁻⁵ or more and the illuminance distribution is preferably 0.35 or more. As described above, the maximum illuminance or the illuminance distribution is small when n _p is less than 1.7. If d / L is less than 1.8, the maximum illuminance or illuminance distribution may be small, and if it exceeds 3.5, the maximum illuminance or illuminance distribution may be small. Preferably it is 2.0-3.2.

  The spherical glass 2 preferably covers not only the upper surface of the light emitting element 1 (the back surface of the transparent substrate 14) but also the side surfaces (the side surfaces of the transparent substrate 14, the n layer 12 and the light emitting layer 13). By covering the side surface of the light emitting element 1 with the spherical glass 2, the light leaking to the outside from the side surface of the light emitting element 1 can be emitted in a desired direction (the direction of arrow A in FIG. 2A). The utilization efficiency of the incident light can be improved. Needless to say, the spherical glass 2 may cover the side surfaces of the electrodes 1 </ b> A and 1 </ b> B of the semiconductor light emitting device 1.

  As shown in FIG. 1, a wiring substrate 3 includes a substrate 31 made of alumina, for example, and an Au wiring, an Ag wiring, a copper foil or the like formed on the substrate 31 using a paste. Pattern 32.

  As shown in FIG. 1, the electrodes 1 </ b> A and 1 </ b> B of the glass-coated light emitting element 10 are electrically connected to the wiring pattern 32 of the wiring substrate 3 through bumps 33 such as gold. In FIG. 1, the spherical glass 2 is not in contact with the wiring board 3, but needless to say, it may be in contact with the wiring board 3.

As shown in FIG. 5A, in a light emitting element 200 having no directivity such as a normal LED, collimator 201 converts parallel light into parallel light unless there is an optical element (such as an integral lens) for uniformizing the light amount distribution. The light intensity I of the luminous flux becomes a normal distribution (Gaussian distribution) in which the central portion exhibits the maximum distribution according to the cosine fourth power law (COS ⁴ θ _Z ) (see data of d = 1.02 mm in FIG. 6). . θ _Z is the angle formed by the optical axis of the light beam before entering the collimator 201, Iz is the intensity distribution of all the light rays that are emitted from one point of the light source, pass through the lens, and reach the illuminated surface, and ΣIz is the light source It is an intensity distribution of all rays that are emitted from all points and reach the illuminated surface.

  On the other hand, in this invention, as shown to the same figure (B), it comprises with the glass-coated light emitting element 10 which coat | covered the light emitting element 1 with the spherical glass 2 which provided the joining surface 2A which is a light-scattering part. Thus, even if a normal LED having a normal distribution of light emission characteristics having the same non-directional light emission characteristics as the conventional one is used as the light emitting element 1, the light intensity I of the light beam that has become parallel light in the collimator 201 is The light quantity distribution is almost averaged (see data of Barechip, d = 0.55 mm, d = 0.72 mm in FIG. 6). This is because, in the case of a directional light source, even if the angle θz passing through the spherical glass 2 is large, it is converted into a thin directional light beam after passing through the spherical glass 2, so the angle of the light beam passing through the collimator 201 This is because the difference becomes small and only a part of the collimator 201 in each emission direction passes, so that θz that decreases by the cosine fourth law becomes small.

  Here, the lens action of the spherical glass 2 having a spherical shape will be described below.

(A) Scattering the return light totally reflected by the spherical glass 2 out of the light emitted from the light emitting element 1 by the scattering means:
Light emission peak wavelength lambda _p emitted from the light emitting element 1, for example, blue light of 460nm region to the surface-emitting over substantially the entire circumference of 360 degrees of the outgoing light side space except the rear of the light emitting element 1. Here, the irradiation pattern immediately after emission (when the spherical glass 1 is incident) is a mountain shape having a maximum peak at the center corresponding to a normal distribution, as shown by a line d = 1.02 mm in FIG. The emitted light from the light emitting element 1 travels immediately inside the spherical glass 2 without passing through the air after being emitted, and then totally reflected on the interface with the air when passing through the spherical glass 2. Only light rays incident below the angle (critical angle) are emitted to the outside of the spherical glass 2. On the other hand, a light ray incident on the interface with air at a total reflection angle or more is totally reflected and returns to the bonding surface 2A. The light that has returned to the bonding surface 2A is scattered by the bonding surface 2A of the spherical glass 2 that is a light scattering portion, and thereafter the optical path is changed. And it becomes the light which reached | attained the glass-air interface with the incident angle below a total reflection angle, and is radiate | emitted outside.

(B) When the light-emitting point A ′ of the light-emitting element 1 that is a light source is shifted to the front side in the irradiation direction from the virtual rearmost point A when the spherical glass 2 is a true sphere, About spreading in the direction of light flux diffusion:
For example, as shown in FIG. 7A, if a paraxial condition with no aberration is established such that the spherical aberration of the spherical glass 2 ′ having no spherical portion is negligible, the light emitting point A of the light emitting element 1 is If it exists in the last point A of spherical glass 2 ', the light beam after radiate | emitting spherical glass 2' will advance with a parallel light beam. Actually, a light beam emitted from the light emitting point A and emitted from the spherical glass 2 ′ has a larger spherical aberration as the position of the light emitted from the spherical glass 2 ′ moves away from the optical axis. It converges in a direction closer to the optical axis than the traveling direction of the light beam. On the other hand, in the light emitting element 1 of the present invention, the light emitting point A ′ is shifted from the rearmost point A of the spherical glass 1 to the front side in the irradiation direction (Z-axis direction) as shown in FIG. The effect of spreading in the direction in which the light beam diffuses (hereinafter referred to as the first effect) can be imparted.

(C) When transmitting through the spherical glass 2, the refractive index n can be set to 1.7 or more, for example, so that the light beam can be spread in the diffusion direction, or n is set to 2.2 or less for example. About things that can narrow in the convergence direction:
In general, in a cross section including the optical axis passing through the center of a double-sided spherical lens, when the lens surface radii are r ₁ and r ₂ , the refractive index of the spherical lens is n, and the lens thickness in the optical axis direction is t, the refractive power ( 1 / f; where f is the focal length.) Is expressed by equation (1).

1 / f = [(n−1) / r ₁ ] + [(1−n) / r ₂ ]
+ [{(N−1) ² d} / (n · r ₁ · r ₂ )] (1)

For a spherical lens, r ₁ = −r ₂ = d / 2.

For a spherical glass 2 having a shape in which a part of a sphere is cut off by a plane, that is, a spherical shape, the radius of the hemisphere on which a part of the sphere is cut off, here for convenience r ₁ Then, since r ₁ becomes ∞ and 1 / r ₁ → 0, the expression (1) becomes the following expression (2).

r ₂ = (1-n) · f (2)

Then, in the ideal case of sufficiently satisfying paraxial conditions, r _{2 =} -f next when n is 2, i.e. the focal length is equal to r _2, the object point from the center of the lens at the position of r ₂ is When placed, the emitted light becomes parallel light.

  Therefore, in such an ideal case, if the refractive index of the spherical glass 2 is less than 2, the light beam diffuses, and if it exceeds 2, the light beam converges (hereinafter referred to as a second effect). Can do.

(D) When the spherical glass 2 is transmitted through the spherical glass 2 due to the spherical aberration, an action in a converging direction that cancels (adjusts) the effects in (b) and (c) described above occurs. :
As is well known, except in the ideal case where the paraxial condition is sufficiently satisfied, as shown in FIG. 8, light traveling in parallel from an object point on the optical axis (Z) generally has an optical axis ( With respect to the direction (X) perpendicular to Z), the light at an object point farther from the optical axis (Z) has an effect of forming an image closer to the ideal focal position (spherical aberration).

Therefore, in the present invention, the d / L and refractive index _{np of} the spherical glass 2 are set to appropriate values in order to cancel the sum of the first and second effects described above by this action. Yes. That is, in the present invention, in order to specifically realize this,
a) the light emitting point A ′ of the light emitting element 1 is shifted from the rearmost point A of the spherical glass 2 to the front side in the irradiation direction;
b) As the spherical glass 2, one having n _p of 1.7 or more, preferably 1.8 to 2.2, and typically 1.9 to 2.2 is used.

  Therefore, according to this embodiment, as shown in FIG. 9A, the light from the semiconductor light emitting element 1 travels inside the spherical glass 2 and reaches the interface (glass interface) between the spherical glass 2 and the external air. When the incident angle exceeds the critical angle at the time of incidence (outside the range δ indicated by the broken line), it may return to the vicinity of the light emitting surface of the light emitting element 1 again by total reflection. In FIG. 9A, the reflected light that follows the optical path indicated by the thick arrow B corresponds to light that is not emitted from the spherical glass 2 due to total reflection and returns to the region where the semiconductor light emitting element 1 exists. And according to this embodiment, the light-scattering part is provided. Therefore, when light that has returned to the vicinity of the light-emitting element 1 by total reflection enters the bonding surface 2A (see FIG. 1) that is a light scattering portion, the light path is changed by being refracted there. For this reason, the refracted return light loses its total reflection condition at the glass interface, and the incident angle incident on the interface of the spherical glass 2 falls within the critical angle δ. It follows the optical path as shown in B and is emitted from the spherical glass 2. As a result, according to the glass-coated light-emitting element of the first embodiment, light that has not been emitted to the outside of the glass by total reflection so far can be emitted to the outside of the glass, so that the amount of light can be increased. Have

  Thereby, a high-intensity parallel light source can be realized in place of the conventional lamp light source, and the shape of the irradiation surface can be freely set to a desired shape.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals to avoid redundant description.

  FIG. 10 shows a glass-coated light-emitting element (second light-emitting element) 20 according to the second embodiment of the present invention. The glass-coated light-emitting element 20 has a spherical shape emitted from the semiconductor light-emitting element 1. A space between the spherical glass 2 and the semiconductor light emitting element 1 as a light scattering part for scattering the light that is totally reflected by the spherical surface in the glass 2, instead of performing fine processing including fine irregularities on the bonding surface 2 </ b> A. 2B is provided with a filler 4 as a large number of fine bead-shaped light scattering members made of alumina, and with these fillers 4 interposed, the spherical glass 2 and the semiconductor light emitting element 1 are bonded with a UV adhesive. Are joined together. Here, the particle size of the filler is preferably about 100 μm to 200 nm. This is because if it is too small, the scattering ability is lowered, and if it is too large, the scattering ability per unit volume is lowered. However, the particle size is not particularly limited.

  Therefore, also in this embodiment, the light from the semiconductor light emitting element 1 travels inside the spherical glass 2 and returns again to the vicinity of the light emitting surface of the semiconductor light emitting element by total reflection. Then, when the return light is incident on a large number of fine bead-like fillers 4 which are light scattering portions, the light path is changed by scattering there. Therefore, the refracted return light is emitted from the spherical glass 2 when the total reflection condition at the glass interface is broken and the incident angle incident on the interface of the spherical glass 2 falls within the critical angle δ. As a result, according to the glass-coated light-emitting device of the second embodiment, light that has not been emitted to the outside of the glass by total reflection so far can be emitted to the outside of the glass, so that the amount of light can be increased. Have Furthermore, according to the glass-coated light emitting device of the second embodiment, the light scattering portion is interposed between the spherical glass 2 and the semiconductor light emitting device 1, thereby eliminating the total reflection loss of the spherical glass and reducing the amount of emitted light. In addition to increasing or improving the light extraction efficiency, it is possible to change the scattering characteristics of the scattering layer using the particle size, refractive index, and filling factor of the filler as parameters. Therefore, according to the glass-coated light emitting device of the second embodiment, there is an effect that the emission luminance distribution can be made more uniform or optimized.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals to avoid redundant description.

  FIG. 11 shows a glass-coated light-emitting element (third light-emitting element) 30A according to the third embodiment of the present invention. In the glass-coated light-emitting element 30A, the glass 2 emits light from the semiconductor light-emitting element 1. As a light scattering portion for scattering the light that is totally reflected by the inner spherical surface and returned, a reflective surface that is finely processed on the electrode of the semiconductor light-emitting element 1 is used instead of the bonding surface 2A that is finely processed with fine irregularities. The mirror electrodes 1C and 1D having the light reflection function are used. Here, for the mirror electrode 1D, a metal having excellent hole injection property and good reflectivity such as Ni, Au, Pd, and Rh is used as the P electrode.

  The mirror electrodes 1C and 1D are made of a highly light-reflective material, and each of the mirror electrodes 1C and 1D is subjected to microfabrication of unevenness on the bonding surface (upper surface) near the light emitting surface, which is the bonding surface side with the p layer and n layer. It has been given.

  Therefore, also in this embodiment, among the return light that travels inside the spherical glass 2 and returns to the semiconductor light emitting element 1 again by total reflection, the light that goes to the mirror electrodes 1C and 1D is provided on the upper surfaces of the mirror electrodes 1C and 1D. Since the light is scattered and reflected by the uneven portions of the microfabrication, the optical path is changed to return to the inside of the spherical glass 2. As a result, according to the glass-coated light emitting device of the third embodiment, the light that has not been emitted to the outside of the glass by total reflection until now can be emitted to the outside of the glass, so that the amount of light can be increased. Have Furthermore, according to the glass-coated light emitting device of the third embodiment, by using the electrode as a mirror electrode, there is an effect of reducing cost without requiring new parts.

  Further, in the case of the glass-coated light emitting device 30B of the type shown in FIG. 5B that is similar to the glass-coated light emitting device 30A of the present embodiment, the electrodes are provided on both surfaces of the semiconductor light emitting device 1 instead of one surface. Of these electrodes 1E and 1F, the (negative) electrode 1F closer to the spherical glass 2 from which the emitted light is emitted is composed of a transparent electrode. On the other hand, the opposite (positive) electrode 1E is constituted by a mirror electrode, and one surface (upper surface) in contact with the p layer is subjected to fine processing of irregularities. The (negative) electrode 1F is connected to the wiring pattern 32 of the wiring board 3 by wire bonding using a gold wire 34, and the upper surface which is the light emitting surface of the semiconductor light emitting element 1 is made of a transparent resin together with the gold wire 34. A sealed mold part 5 is provided.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. In the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals to avoid redundant description.

  FIG. 12 shows a glass-coated light-emitting element (fourth light-emitting element) 40 according to the fourth embodiment of the present invention. In this glass-coated light-emitting element 40, the semiconductor light-emitting element 1 is placed on the transparent substrate 14. The semiconductor light-emitting element 1 is composed of transparent electrodes 1G and 1H. The transparent electrodes 1G and 1H of the semiconductor light emitting element 1 and the wiring pattern 32 of the wiring board 3 are connected by wire bonding with a gold wire 34 or the like. Further, in the glass-coated light emitting device 40 of the present embodiment, a mold part 5 sealed with a transparent resin is provided on the upper surface, which is the light emitting surface of the semiconductor light emitting device 1.

  Further, in the glass-coated light emitting device 40, light that is transmitted through the semiconductor light emitting device 1 and incident on at least the upper surface of the wiring substrate 3 immediately below the light emitting region corresponding to the light emitting region of the semiconductor light emitting device 1 as a light scattering portion. A reflective surface 31A for reflecting the light is formed. Further, the reflective surface 31A is finely processed to form a scattering reflective surface.

  Therefore, also in this embodiment, among the return light that travels inside the spherical glass 2 and returns to the semiconductor light emitting element 1 again by total reflection, the light that passes through the semiconductor light emitting element 1 and travels toward the wiring board 3 is the wiring board 3. The light is scattered and reflected by the reflective surface 31A of the uneven portion of the microfabrication provided on the upper surface. As a result, of the return light returning to the inside of the spherical glass 2 by changing the optical path, the return light whose total reflection condition is broken and the incident angle at the glass interface of the spherical glass 2 is less than the critical angle is emitted from the spherical glass 2. Is done. As a result, according to the glass-coated light-emitting element of the fourth embodiment, light that has not been emitted to the outside of the glass by total reflection so far can be emitted to the outside of the glass, so that the amount of light can be increased. Have Furthermore, according to the glass-coated light emitting device of the fourth embodiment, there is an effect that it can be applied to a surface mount type semiconductor light emitting device. In combination with the fourth embodiment and the second embodiment, there is no problem even if the mold part 5 for sealing the gold wire 34 has a light scattering structure.

  Next, using the glass-coated light-emitting element of the present invention, a simulation was performed on the illuminance distribution at a certain distance from the glass-coated light-emitting element. In this simulation, the glass-coated light-emitting element 10 of the first embodiment was used as the glass-coated light-emitting element. However, in this glass-coated light-emitting element 10, as shown in FIGS. 13A and 13B, one side of the light-emitting element 1 is 0.32 mm □ (where □ means a square. The same applies hereinafter). As the light source, the spherical glass 2 having a refractive index of 2.0 (when λ = 546 nm) and a diameter of 1.0 mm was used. Further, as shown in FIG. 5C, an illuminance distribution diagram was created by simulation by installing a photo detector D having a side of 100 mm □ at a front position separated from the light emitting element 1 by 50 mm. A reflector R is installed on the back surface of the light emitting element 1.

  According to this simulation, the scattering rate is 0% (in this case, 100% regular reflection), 10% (the remaining 90% is regular reflection, the same applies hereinafter), 30%, 50%, 60%. , 70%, 90%, and 99%, the optical characteristics were examined. As a result, the illuminance distribution as shown in FIGS. 14A to 21A, the luminance distribution as shown in FIGS. 14B to 21B, and FIGS. 14C to FIG. 21C of the planar illuminance distribution in which the illuminance distribution of 21A is represented by a plane (surface to be irradiated) were obtained. 14D to 21D are contour maps schematically showing FIGS. 14C to 21C. For comparison, FIG. 22 simultaneously shows each graph when the absorption at the reflector is 100%.

  According to this simulation, it is understood that there is a predetermined correlation between the scattering rate (scattering ratio) and the illuminance distribution, as shown in FIGS. 14A to 21A and 14C to 21C. For example, when the scattering rate is small as shown in FIG. 14 to FIG. 17, the illuminance is small at the central portion in the irradiation region and large at the outer edge portion. On the other hand, when the scattering rate is large as shown in FIGS. 20 and 21, it is shown that the illuminance is large at the central portion in the irradiation region and small at the outer edge portion.

  Then, as shown in FIGS. 18A, 18C, 19A, and 19C, when the scattering rate is a certain ratio (approximately 60% to 70%), it resembles the shape of the light emitting element 1 (having a square or a rectangle). It is understood that the illuminance in the irradiation area is substantially equal between the outer edge portion and the surface. Thus, it is understood that the illuminance in the irradiation region can be made uniform by adjusting the scattering rate. Such control is possible regardless of the specification of the light emitting element 1 and the change of the embodiment.

  Further, according to this simulation, there is a correlation as shown in FIG. 23 between the scattering ratio and the illuminance (total light flux amount), for example, and the scattering rate is a constant rate (in this simulation, the scattering rate is approximately 20%). ) Exceeding the predetermined value, it was found that illuminance of a predetermined value or more can be obtained stably.

  Next, the illuminating device of this invention is demonstrated, referring FIG.

  The illuminating device 50 of the present invention includes the glass-coated light emitting element 10 of the present invention and a field lens (objective lens) 60 disposed in front thereof. The glass-coated light-emitting element 10 is usually electrically connected to the wiring pattern of the wiring board by bumps.

  According to the illumination device 50 of the present invention, each light beam emitted from the glass-coated light-emitting element 10 is gathered in the Z direction along the principal light beam determined by the light-emitting point position of the LED and the center point of the glass-coated light-emitting element 10. It proceeds as a light beam having a directivity and reaches the field lens 60. Each light beam reaching the field lens 60 is further deflected in a direction close to parallel to the optical axis of the lens by its refractive power at the height of the arrival point of the field lens 60 to be illuminated (not shown). ).

  Here, if the spherical lens of the glass-coated light emitting element 10 and the field lens 20 are ideally non-aberration lenses, light in all directions can be incident on the illuminated body vertically. Since any lens has a large spherical aberration, it is inevitable that there is a light beam that is incident on the object to be illuminated obliquely to some extent.

  However, while observing the dispersion state of the light rays of the spherical lens and the field lens 60, the refractive power and position of the field lens 60 are optimized so that the light beams near the center and the periphery are substantially incident on the surface of the illuminated body as shown in FIG. As a result, almost all of the light emitted from the glass-coated light emitting element 10 can be incident on the surface of the illuminated body as close to vertical as possible within the aberration range.

  Further, as a means for collimating the passing light beam as much as possible, the field lens is replaced with an aspheric lens having an optimal aspheric shape (plano-convex or double-sided) instead of an inexpensive plano-convex spherical lens. It is also possible to make it vertical. In this case, whether or not the aspheric lens can be used can be considered in comparison with the effects of uniformizing illumination light and improving luminance.

  Since the position of the light beam incident on the illuminated body is determined corresponding to the light emitting point position of the glass-coated light emitting element 10, if the light intensity of the glass-coated light emitting element 10 is uniform, each position of the illuminated body The reaching light intensity is also nearly uniform. For this reason, for example, in the field of displays such as general architectural lighting members, liquid crystal televisions, and projector screens, it is necessary without using expensive additional optical systems such as expensive homogenizing optical systems such as conventional integrator lens systems. Even in such a case, it is possible to realize an irradiation surface or screen having a substantially uniform light intensity by adding an inexpensive uniformizing element such as a thin diffusion plate.

  In addition, in the present invention, since the glass-coated light emitting element 10 includes the light scattering portion, the inside of the illumination area can be illuminated with substantially the same illuminance as the outer edge portion, and the light emitting area of the light emitting element 1 is the light emitting element. Since the light emitting element 1 has a shape corresponding to the shape to be illuminated of the object to be illuminated, the illumination area on the object to be illuminated can be freely formed.

  Next, a projector device of the present invention (hereinafter simply referred to as a projector) will be described with reference to FIG. 25, but the present invention is not limited to the one shown in this figure.

  The projector 100 of the present invention includes the glass-coated light emitting elements 10R, 10G, and 10B of the present invention, a field lens 60, LCDs (liquid crystal display devices) 70R, 70G, and 70B, a multiplexing element 80, and a projection lens 90. I have. The glass-coated light emitting elements 10R, 10G, and 10B are usually electrically connected to the wiring pattern of the wiring board by bumps. Each of the glass-coated light emitting elements 10R, 10G, and 10B and the LCDs 70R, 70G, and 70B constitute lighting devices 50R, 50G, and 50B.

  According to the projector 100 having such a configuration, the light from the glass-covered light emitting elements 10R, 10G, and 10B provided as the RGB light sources passes through the field lens 60, and then LCDs (liquid crystal display devices) 70R and 70G. , 70B from the back surface to constitute a backlight. In the LCDs (liquid crystal display devices) 70R, 70G, and 70B, after images corresponding to the respective RGB light components are formed, the image components are combined by the combining element 80, and then the projection lens. 90 is incident.

  According to the projector 100 of the present invention, each of the three primary color LCDs can be replaced with a conventional complex optical system having a certain size by using only the configuration of the light emitting elements 10R, 10G, and 10B and the single field lens 60. An optical engine unit that uniformly illuminates the interior of the illumination area with substantially the same illuminance as the outer edge portion can be configured without using a uniformizing optical system. Therefore, the conventional three LCD projector optical systems can be manufactured at a low cost with a reduced number of parts.

  Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on May 17, 2007 (Japanese Patent Application No. 2007-132194), the contents of which are incorporated herein by reference.

  The glass-coated light emitting device of the present invention has an effect that the irradiation efficiency is good and the emitted light can be efficiently guided in a desired direction, and the alignment with the lens or the light pipe is not required. In addition to having the light emitted from the semiconductor light emitting element, it can be efficiently extracted and used as light for light emission by the light scattering part, so a field lens (objective lens) is placed in front of the glass-coated light emitting element. It is useful for an illumination light source that has been used and a projector apparatus having this illumination light source.

Claims (11)

A semiconductor light emitting device;
A surface that emits light emitted from the semiconductor light emitting element, and the surface has a spherical shape wider than a hemispherical surface and a part of a spherical notch, and is attached to the semiconductor light emitting element in the spherical notch, A glass having a refractive index at an emission peak wavelength of the semiconductor light-emitting element of 1.7 or more and a ratio of a maximum diameter of the spherical portion to a diameter of at least 1.8;
A light scattering part that refracts light existing inside the glass without being emitted from the surface of the glass;
A glass-coated light emitting device comprising: The glass-coated light emitting device according to claim 1,
The glass-coated light-emitting element, wherein the light scattering part is an unevenness formed on a surface of the glass that covers a light-emitting surface of the semiconductor light-emitting element. The glass-coated light emitting device according to claim 1,
The light scattering portion is a glass-coated light-emitting element including a light scattering member provided between a surface of the glass that covers a light-emitting surface of the semiconductor light-emitting element and the light-emitting surface of the semiconductor light-emitting element. The glass-coated light emitting device according to claim 1,
The light-scattering portion is an electrode having a light reflecting function formed on the semiconductor light-emitting element. The glass-coated light emitting device according to claim 1,
The glass-coated light-emitting element, wherein the light scattering portion is a scattering reflection surface provided on a wiring substrate to which the semiconductor light-emitting element is connected. The glass-coated light emitting device according to any one of claims 1 to 5,
A glass-coated light emitting device having a refractive index of 2.3 or less. The glass-coated light emitting device according to any one of claims 1 to 6,
A glass-coated light emitting device having a refractive index of 1.8 to 2.2 and a ratio of 3.5 or less. The glass-coated light emitting device according to any one of claims 1 to 7,
A glass-coated light emitting device, wherein the semiconductor light emitting device is a light emitting diode. The glass-coated light emitting device according to any one of claims 1 to 8,
A glass-coated light emitting device, wherein the semiconductor light emitting device has an emission peak wavelength of 450 to 480 nm.   The illuminating device comprised from the glass-coated light emitting element of any one of Claim 1 to 9, and a field lens.   The projector apparatus which has an illuminating device of Claim 10 as a light source.

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