JP4404658B2 - Semiconductor light emitting device - Google Patents

Description

  The present invention relates to a semiconductor light emitting device using a semiconductor light emitting element as a light source, and more particularly, means for emitting light emitted from the semiconductor light emitting element by changing it to light that does not cause damage to the human body (eyes, skin, etc.). The present invention relates to a semiconductor light emitting device having an eye-safe measure.

  In recent years, with the advent of semiconductor lasers, lasers have become familiar, and, for example, the opportunity to touch the eyes of ordinary people such as pointers has increased rapidly. In addition, in super luminescent diodes (SLD) and light emitting diodes (LEDs), the emission wavelength region has been shortened, and at the same time light has been emitted over the ultraviolet to visible to infrared wavelength region, Luminous efficiency has been improved and brightness has been increased, and it has come to be used as a clear display light source and an information transmission medium for optical space transmission as one method of wireless data transfer.

  On the other hand, in such a situation, there is an increasing interest in the effects of light on the human body (skin and eyes), and lasers and LEDs are used as “world-wide safety standards” based on various safety confirmation tests. The international standard IEC60825-1 AMENDENT2 (2001) standard has been established in a manner that includes it. In this standard, products are classified as indicators for safety evaluation, and the highest safety class 1 (even with any optical system (lens or telescope) that can cause damage to the eyes and skin). A laser that is safe under reasonably foreseeable operating conditions. Therefore, it is necessary to be classified into this class 1 in order to freely use laser, SLD, and LED light in applications that may touch the human body.

  Here, an outline of the relationship between light and eyes (eyeballs) will be described. The light emitted from the light source and reaching the human eye forms an image of the light source on the retina through a lens system composed of the cornea of the eye and the crystalline lens. The size of this image depends on the size of the light source. When the light emitting area of the light source is small, the light collected by the lens system and reaching the retina is imaged as a minute spot on the retina. When the light emitting area is large, it is imaged as a large spot on the retina.

  The light in the eye-safe wavelength region (1400 nm to 2600 nm) does not reach the retina because most of the light energy is absorbed by the water (cornea) on the eyeball surface even when the light enters the eye. High safety. On the other hand, light having a wavelength in the ultraviolet region other than the eye-safe wavelength region is absorbed in the middle and does not reach the retina, but may cause damage to the cornea, conjunctiva and the like. Similarly, it can cause damage to the skin. In addition, light having a wavelength ranging from the visible to the infrared region has a high possibility of damaging the retina (specifically, biochemical reaction or thermal damage), and in any case, light energy absorbed per unit area ( The greater the energy density), the greater the possibility of causing damage or damage.

  Therefore, assuming that the total energy of light emitted from light sources other than the eye save wavelength region is the same, the spot imaged on the retina as the light source diameter (light emitting surface area) decreases. As a result, there is a high possibility that the energy density is locally increased and the retina is damaged.

  In particular, in the case of lasers, SLDs, and LEDs that are regarded as point light sources in the design of optical systems, the energy density becomes extremely large because the spot imaged on the retina becomes extremely small, increasing the risk to the eyes. Will do.

  As a general method for solving such problems, a light source that emits high energy by increasing the spot diameter formed on the retina by increasing the diameter of the light source to reduce the energy density. As a class 1, measures are taken to ensure safety.

  Specifically, in a package enclosing a point light source such as a semiconductor laser, a portion where light emitted from a light source is emitted to the outside is configured by a diffusion plate, and the light emitted from the semiconductor laser is transmitted through the diffusion plate. As a diffused light is emitted to the outside by guiding the light, and a spot light source is used as a dispersed light source to increase the size of the light source diameter, thereby enlarging the spot imaged on the retina to ensure safety for humans (For example, refer to Patent Document 1).

In addition, a light diffusion sheet is arranged in a radiation direction substantially on the optical axis of a point light source that emits superluminescent light mounted on the stem, and the light emission source and the light diffusion sheet are integrally sealed with a translucent epoxy resin. There is one in which a convex lens is formed in the light emitting direction of the light diffusion sheet. In this case, diffused light emitted from the light source and diffused by the light diffusing sheet is emitted by the lens in a desired light distribution pattern, the light source diameter is increased, and measures for eye-safe are taken and necessary light energy is taken. The optical system is configured to ensure the above (for example, see Patent Document 2).
JP-A-9-307174 JP 2002-76440 A

  However, in the former conventional structure, the diffused light emitted from the light source and diffused by the diffusion plate is directly emitted into the atmosphere and directed in various directions, making it difficult to control light distribution in design and manufacturing. Not only that, but the energy density substantially on the optical axis is extremely reduced, which hinders the use of the optical space transmission as an information transmission medium.

  In the latter structure, the diffused light emitted from the light emitting source and diffused by the light diffusing sheet is collected by the lens, so the light distribution pattern and the energy density on the substantially optical axis do not hinder use. It can be secured to the extent. However, since there is also light that does not contribute to the condensing of the lens among the diffused light diffused by the light diffusion sheet as in the former, the light extraction efficiency into the atmosphere is insufficient.

  Furthermore, as the light emission spot formed on the light diffusion sheet is increased by the light emitted from the light source, the safety for eye-safe is surely directed, but in order to maintain the light collection effect of the lens However, it is necessary to increase the radius of curvature of the lens, and as a result, the semiconductor light emitting device must be increased in size.

  On the other hand, if the light emitting spot is small, the lens condensing effect can be obtained even if the radius of curvature of the lens is small. Therefore, it is a problem to realize a desired semiconductor light emitting device by miniaturizing the light source diameter as much as possible and effectively functioning the lens effect while satisfying the eye-safe regulations.

  Accordingly, the present invention was devised in view of the above problems, and the object of the present invention is to achieve a miniaturized semiconductor light-emitting device that is fully safe for eyes, has high light extraction efficiency, and provides desired light distribution characteristics. Is to provide.

In order to solve the above problems, the invention described in claim 1 of the present invention includes a semiconductor light emitting element, a light guide having a light diffusing portion in the part of the surface consists of transparent member, the inner peripheral a semiconductor light-emitting device having a reflective frame surface is provided with a bottom in the central portion in the through hole of the recess with a recess of conical shape of the reflecting surface, the inner peripheral surface is mounted on the base The reflective frame is disposed in the semiconductor in a direction that is open toward the light emitting direction of the semiconductor light emitting element with respect to the optical axis of the semiconductor light emitting element and the through hole is positioned on the optical axis of the semiconductor light emitting element. The light guide is disposed above the light emitting direction of the light emitting element, and the light guide is disposed above the through hole in the concave portion so that the light diffusion portion is located in the concave portion and located in the light emitting direction of the semiconductor light emitting element. The concave portion is filled with a translucent resin.

  Moreover, the invention described in claim 2 of the present invention is characterized in that, in claim 1, the base and the reflection frame are integrally formed.

Further, in the invention described in claim 3 of the present invention, in any one of claims 1 and 2, the light diffusing portion is formed of Al ₂ O ₃ and SiO _{2 in} one of silicone resin and epoxy resin. Any one or both of them are dispersed.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the semiconductor light emitting device has a peak emission wavelength in a range of 200 to 2000 nm. It is.

  Light guide loss from the time when the light emitted from the semiconductor light emitting element enters the light guide until it is emitted into the atmosphere is reduced, and the light is incident on the light guide and scattered by the light diffusing portion to be reflected on the reflecting surface. Light extraction efficiency is improved by reflecting the incoming light on the reflective surface and directing it toward the light exit surface of the translucent resin, and small and eye-safe for easy light distribution control by reducing the light diffusion part of the light guide A semiconductor light-emitting device with countermeasures was realized.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. 1 to 6 (the same parts are denoted by the same reference numerals). The embodiments described below are preferable specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. Unless stated to the effect, the present invention is not limited to these embodiments.

  The basic elements constituting the present invention are a light emitting element, a light guide, and a reflection frame. The light emitting element uses one semiconductor light emitting element in the group consisting of laser, super luminescent diode (SLD) and light emitting diode (LED) semiconductor light emitting elements. The light guide is made of one light transmissive member in the group consisting of epoxy resin, silicone resin and glass light transmissive member, and has a light incident surface and a light output surface, and a light scattering means on the light output surface. Is given. The reflection frame has a bowl-shaped recess whose inner peripheral surface is a reflection surface, and a through hole is provided at the center of the bottom of the recess.

  Therefore, an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic sectional view of an embodiment of a semiconductor light emitting device according to the present invention. A mount base 3 on which a semiconductor light emitting element 2 is mounted is fixed to one surface of a stem 1 as a base, and an opening is formed. A cylindrical case 4 having the same is fixed to the stem 1 and surrounds the mount base 3. A plurality of lead wires 5 for supplying electric power to the semiconductor light emitting element 2 from the outside are led out on the other surface of the stem 1 to form a package 6.

  The upper part of the cylindrical case 4 of the package 6 (radiation direction of light emitted from the semiconductor light emitting element) has a bowl-shaped concave part 8 whose inner peripheral surface is a reflecting surface 7 and has a substantially central bottom part of the concave part. A reflection frame 10 provided with a through hole 9 in the part is disposed, and a spherical light guide 12 made of a transparent member is disposed in the recess 8 so as to block the through hole 9 with the light diffusion part 11 facing upward. ing.

  Furthermore, a translucent resin 13 is filled in the bowl-shaped concave portion 8 of the reflection frame 10 so that the light guide 12 is embedded and a convex lens 14 is formed.

  Actually, the lead wire 5 and the electrode provided on the semiconductor light emitting element 2 are electrically connected by some connecting means, but are omitted in the drawing.

  Here, the optical system of the semiconductor light emitting device 20 having the above configuration will be described. The light emitted from the semiconductor light emitting element 2 mounted on the mount 3 that also serves as a heat dissipation function when the semiconductor light emitting element 2 is turned on passes through the through hole 9 provided at the center of the bottom of the recess 8 of the reflection frame 10. It reaches the light incident surface 15 of the light guide 12 and enters the light guide 12. The light that has entered the light guide 12 is guided through the light guide 12 and reaches the light exit surface 16 of the light guide 12.

  The light diffusing portion 11 is formed on the light emitting surface 16 of the light guide 12, and the light reaching the light emitting surface 16 becomes scattered light in the light diffusing portion 11 and forms a light diffusing portion 11 and an interface. Is incident on the conductive resin 13. A part of the scattered light that has entered the translucent resin 13 is guided through the translucent resin 13 to reach the inner surface of the lens 14 of the translucent resin 13, collected by the lens 14, and emitted from the lens 14. Released from the surface 17 into the atmosphere 18.

  On the other hand, the scattered light that enters the translucent resin 13 and is guided through the translucent resin 13 toward the bowl-shaped reflective surface 7 provided on the reflective frame 10 is reflected by the reflective surface 7 and transmitted therethrough. The optical resin 13 is directed in the direction of the lens 14, further guided through the translucent resin 13, reaches the inner surface of the lens 14 of the translucent resin 13, and is condensed by the lens 14 from the light exit surface 17 of the lens 14. Released into the atmosphere 18.

  Therefore, the light emitted from the semiconductor light emitting element 2 and emitted into the atmosphere 18 from the light emitting surface 17 of the lens 14 of the translucent resin 13 is emitted from the semiconductor light emitting element 2 and is guided through the translucent resin 13. The light that travels along the optical path that is directly emitted into the atmosphere 18 and the light emitted from the semiconductor light emitting element 2 and reflected by the reflecting surface 7 in the translucent resin 13 are further guided through the translucent resin 13. The light that follows the optical path emitted into the atmosphere 18 is mixed.

Here, the effect of the reflection frame will be described with reference to FIGS. 2 and 3 show that light emitted from the semiconductor light emitting element 2 is incident on the light guide 12 and is emitted from the light diffusing portion 11 formed on the light exit surface 16 of the light guide 12. FIG. 2 shows the optical path of the scattered light that has entered the inside of FIG. 13. FIG. 2 shows a case where no reflecting frame is provided, and FIG. 3 shows a case where a reflecting frame is provided. In both cases, the optical paths followed by the light beams L _{0 to} L ₂ are the same, but the light beam L ₃ is guided through the translucent resin 13 in the absence of the reflection frame in FIG. The light is emitted in a direction nearly perpendicular to the direction, and becomes useless light that does not contribute as a semiconductor light emitting device. On the other hand, in the case of the reflection frame 10 in FIG. 3, the light beam L3 is reflected by the reflection surface 7 of the reflection frame 10 and is directed almost in the radiation direction of the semiconductor light emitting element 2. It is emitted and used as effective light. Accordingly, the provision of the reflective frame 10 increases the light utilization efficiency, thereby realizing a semiconductor light-emitting element with good light collecting properties.

In addition, the light diffusing part formed on the light emitting surface of the light guide body is any one of Al ₂ O ₃ and SiO ₂ having a particle diameter of 0.5 to 10 μm in one of silicone resin and epoxy resin. It can be realized by forming a light diffusion film with a member in which either or both are dispersed. Further, it is also possible to form the light emitting surface into a surface texture with an uneven pattern by embossing by a method such as chemical etching or sand blasting. Another possible method is to form a light emitting surface of the molded product with a textured surface by applying a texture pattern to the molding die.

  FIG. 4 is a schematic cross-sectional view of another embodiment of the semiconductor light emitting device of the present invention. The semiconductor light emitting device of this embodiment has the same configuration as that of the above embodiment, and the optical system is different only in that the reflection frame is formed integrally with the mount base on which the semiconductor light emitting element is mounted. Are the same. Therefore, the detailed description overlaps with the above-described embodiment, and is omitted here.

  However, in the case of this embodiment, since the reflecting frame and the mount base are integrally formed, the number of parts is small, and it is manufactured by reducing the mold cost and material cost related to parts manufacture and the man-hour related to product assembly. The cost can be reduced, and at the same time, the positional accuracy between the light guide and the semiconductor light emitting element disposed above the through hole provided in the reflection frame is increased, so that the desired light distribution characteristic is easily and highly accurate. Therefore, it can be finished into a product with high light extraction efficiency and little variation in optical characteristics.

  FIG. 5 shows another shape of the light guide used in the semiconductor light emitting device of the present invention. (A) The light incident surface 15 is made into a substantially spherical shape, the light emitted from the semiconductor light emitting element is taken into the light guide 12, and the light diffusion portion 11 formed on the light emitting surface is made into a substantially spherical shape to form a three-dimensional shape. The light diffusing unit 11 is configured to emit scattered light, and both the spherical surfaces forming the light incident surface 15 and the light diffusing unit 11 are connected by a conical surface.

  (B) is similar to (a) in that the light incident surface 15 is formed in a substantially spherical shape, the light emitted from the semiconductor light emitting element is taken into the light guide 12, and the light diffusing portion 11 formed on the light emitting surface is substantially omitted. The plane is shaped so that scattered light is emitted from the planar light diffusing portion 11, and the spherical surface forming the light incident surface 15 and the plane forming the light diffusing portion 11 are conical surfaces. It is connected.

  (C) As in (a) and (b), the light incident surface 15 is made into a substantially spherical shape, the light emitted from the semiconductor light emitting element is taken into the light guide 12, and the light diffusion formed on the light emitting surface. The part 11 is also formed in a substantially spherical shape so that scattered light is emitted from the three-dimensional light diffusion part 11, and the both spherical surfaces forming the light incident surface 15 and the light diffusion part 11 are cylindrical. Connected in terms of

  In addition, the light guide 12 of (a), (b), and (c) has a shape that places importance on the light distribution of scattered light emitted from the light diffusion portion 11 of the light guide 12.

  (D), the light incident surface 15 is formed in a concave, substantially spherical shape centered on one point on the outside, and the light emitted from the semiconductor light emitting element is arranged by arranging the semiconductor light emitting element in the vicinity of the center. Thus, the light is efficiently taken into the light guide 12 without being refracted by the light incident surface 15, reaches the substantially spherical light diffusion portion 11, and the scattered light is emitted from the three-dimensional light diffusion portion 11. It is a simple shape. The light guide 12 is shaped to improve the light extraction efficiency.

  (E) has a light guide 12 formed in a substantially flat plate, one surface having a light incident surface 15 and the other surface having a light diffusing portion 11, which has a simple shape and the lowest manufacturing cost. The light guide 12 has a simple structure and a shape aimed at reducing the cost.

  Which one of the light guides (a) to (e) above is adopted is determined in consideration of various conditions such as desired light distribution characteristics, the manufacturing cost of the reflection frame and the light guide. Is. It should be noted that the light guides listed here show some of the shapes that can be employed, and are not necessarily limited thereto.

  Next, the light distribution characteristic obtained by the semiconductor light emitting device of this embodiment is shown in FIG. This shows two examples obtained by changing the shape of the lens of translucent resin. (A) is a narrow angle type lens with a higher light collecting degree, (b) is a wide angle lens. It is a type that reduces the light concentration. In the measurement method, a photo sensor is arranged in front of the semiconductor light emitting device in the radial direction, and the semiconductor light emitting device is detected by the photo sensor while being rotated little by little. In the figure, the horizontal axis represents the rotation angle θx when the semiconductor light-emitting device is rotated, and the vertical axis represents the relative luminous intensity represented relatively with the luminous intensity at that time as 1.

  The measurement results are as follows. When the light spread angle at which the luminous intensity is ½ of the maximum luminous intensity is the full width at half maximum, (a) shows that the light distribution characteristic rises sharply with respect to the maximum luminous intensity, and the full width at half maximum is about A strong light condensing effect by the lens at 5 ° is shown. (B) shows that the light distribution characteristic rises gently with respect to the maximum luminous intensity, and the full width at half maximum is about 22 °, indicating a weak light condensing effect by the lens. In addition, it is possible to obtain the desired light distribution characteristics by changing each shape of the lens, the light guide, and the bowl-shaped reflecting surface independently, but it is also possible to control the light distribution by changing the shape of a plurality of combinations. Can do.

  Here, the effect of the present invention will be described. First, since the optical semiconductor element and the light incident surface of the light guide can be arranged close to each other, the opening of the light incident surface of the light guide can be reduced, and therefore the entire light guide can be reduced. it can. Therefore, the inner peripheral surface provided in the reflection frame of the light diffusion portion formed on the light emitting surface of the light guide can be positioned in the bowl-shaped recess of the reflection surface. As a result, light emitted from the semiconductor light emitting element is introduced into the light guide and guided to the light exit surface of the light guide located in the recess provided in the reflection frame, and the light formed on the light exit surface The light is emitted from the diffusing portion as scattered light into a translucent resin that forms an interface with the light diffusing portion.

  Accordingly, since light emitted from the semiconductor light emitting element enters the light guide and is emitted from the light diffusion portion formed on the light exit surface of the light guide, the light is guided through the light guide. There is almost no light guiding loss, and the light transmission efficiency is very good. In addition, light scattered in the translucent resin that is not directed directly toward the light-emitting resin exit surface is also reflected by the reflective surface and is directed to the light exit surface of the translucent resin. Light emitted as scattered light from the light diffusion surface of the light body can be efficiently guided to the light emission surface of the translucent resin. Furthermore, since light that is scattered at the light diffusion portion of the light guide and travels toward the light exit surface of the translucent resin is guided through the translucent resin, there is almost no light guide loss between them, and the light transmission efficiency Is very good. Thus, a semiconductor light-emitting device with high extraction efficiency of light emitted from the semiconductor light-emitting element can be realized by a combination of the light guide, the mortar-shaped reflection surface, and the translucent resin.

  At the same time, since the light emitted from the semiconductor light emitting element is changed to scattered light by the light diffusion portion formed in the light guide, the diameter of the light source is increased. Therefore, the eye-safe can be sufficiently secured, and at the same time, the function as a communication element that bears an optical medium such as optical space transmission is sufficiently fulfilled.

  Also, by reducing the diffusion surface of the light exit surface of the light guide, an optical design that approximates a point light source becomes possible, so that the accuracy of light distribution control with a translucent resin lens can be relatively easily increased. In addition, by obtaining a product with little light distribution variation, it is possible to ensure practicality as a light source for an illumination device or a display device.

  Furthermore, there is no factor that increases the manufacturing cost because there is no need to provide a particularly complicated process in the manufacturing process, and there is also an element that can reduce the number of parts. It is also possible to finish. There are many excellent effects.

It is a schematic sectional drawing which shows embodiment of the semiconductor light-emitting device of this invention. The optical path in the case where there is no reflection frame is shown typically showing the effectiveness of the reflection frame of the embodiment of the semiconductor light emitting device of the present invention. Similarly, it shows the effectiveness of the reflecting frame of the embodiment of the semiconductor light emitting device of the present invention, and schematically shows the optical path when there is a reflecting frame. It is a schematic sectional drawing which shows another embodiment of the semiconductor light-emitting device of this invention. It is sectional drawing of the light guide used by embodiment of the semiconductor light-emitting device of this invention, (a)-(e) represents each separately. It is a light distribution characteristic by embodiment of the semiconductor light-emitting device of this invention, (a) is a narrow-angle type, (b) is a wide-angle type.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stem 2 Semiconductor light emitting element 3 Mount stand 4 Case 5 Lead wire 6 Package 7 Reflecting surface 8 Recessed part 9 Through-hole 10 Reflecting frame 11 Light diffusion part 12 Light guide 13 Translucent resin 14 Lens 15 Light incident surface 16 Light emitting surface 17 Light exit surface 18 Atmosphere 20 Semiconductor light emitting device

Claims (4)

A semiconductor light emitting element, a light guide having a light diffusing portion in the part of the surface consists of light-transmitting member, in the bottom of the recess inner peripheral surface with a recess of conical shape of the reflecting surface central portion And a reflective frame provided with a through hole in the semiconductor light emitting device, the inner peripheral surface of the semiconductor light emitting device mounted on a base toward the light emitting direction of the semiconductor light emitting device The reflective frame is arranged above the light emitting direction of the semiconductor light emitting element so that the through hole is positioned on the optical axis of the semiconductor light emitting element in the open direction, and the light diffusion portion is in the recess. The semiconductor light emitting device is characterized in that the light guide is disposed above the through hole in the recess so as to be positioned in the light emitting direction of the semiconductor light emitting element, and the recess is filled with a translucent resin.   The semiconductor light emitting device according to claim 1, wherein the base and the reflection frame are integrally formed. Claim 1 or 2, wherein the light diffusing portion is made by dispersing either one or both of Al ₂ O ₃ and SiO ₂ to one of silicone resin and epoxy resin 2. The semiconductor light emitting device according to item 1.   The semiconductor light-emitting device according to claim 1, wherein the semiconductor light-emitting element has a peak emission wavelength in a range of 200 to 2000 nm.

Images