JP2007088290A - Enclosure for light emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To radiate outside the light emitted from a light emitting element at constant intensity from the surface of an enclosure. <P>SOLUTION: A rough side is formed at an interface between the air and a sealing resin 3. The rough side has such shape that compensates a light intensity distribution (c) on the interface to a light intensity distribution (a). The interface of the sealing resin 3 is formed in an uneven pattern such as the light intensity distribution (c) being inverted and transferred upside down, for providing characteristics of the light intensity distribution (a). Since, at an interface (b), the area just over the light emitting element 1 in the light intensity distribution (c) is the strongest in light intensity, that portion of the interface is concave while its surroundings where the light intensity becomes weaker are convex. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an envelope of a light emitting element that emits light emitted by the light emitting element to the outside.

  A light emitting element such as a light emitting diode (LED) needs an envelope (package) to efficiently emit light to the outside. As such an envelope, for example, one having a configuration shown in a sectional view of FIG. 8 is known. The conventional envelope as shown in the cross-sectional view of FIG. 8 includes a recess 5 whose inner wall is inclined in the package 4. A light emitting element 1 is disposed at the bottom of the recess 5 and is configured to be capable of emitting light by being connected to a bonding wire 2.

  The recess 5 is sealed with a light-transmitting sealing resin 30, and the light as shown in the light intensity distribution (c) is transmitted through the light-transmitting sealing resin 30 when the light emitting element 1 emits light. Light is emitted into the air with an intensity distribution characteristic.

In the envelope shown in FIG. 8 or the envelope represented by Patent Document 1, the boundary surface between the sealing resin 30 and air is formed uniformly and flat. Therefore, the light intensity distribution (c) of the light emitted from the light emitting element 1 is the strongest in the vicinity immediately above the light emitting element 1, and the light intensity distribution on the boundary surface becomes weaker as it deviates from just above (see Patent Document 1). ).
Japanese Patent Application Laid-Open No. 2002-217459

  However, when illuminating a flat screen with light using a small light source such as a light emitting diode, it is necessary to illuminate the entire screen with uniform brightness. In addition, a light source capable of emitting light evenly within the field angle region of an image sensor is also desired for use in a flash light source for a camera.

  However, in the envelope of each of the above-described configurations or the envelope represented by Patent Document 1, only the vicinity of the light emitting element on the irradiated object is brightly illuminated, and the entire irradiated object has a uniform light intensity distribution. It was difficult to illuminate. In particular, when the light source is illuminated close to the object to be illuminated, the difference between light and dark appears remarkably.

  Further, when a light emitting element that emits strong light in a direction perpendicular to the installation surface of the light emitting element is installed in the concave portion of the envelope, the electrode pattern of the light emitting element 1 and the bonding wire 2 on the irradiated object Shadows are projected, the light intensity distribution becomes non-uniform, and a difference in brightness occurs.

  This invention is made | formed in view of the above, The place made into the subject is to radiate | emit the light which the light emitting element light-emitted outside with equal intensity | strength from the envelope surface.

  An envelope of a light emitting element according to the present invention is a light emitting device in which a light emitting element is mounted on a conductive lead frame, and the mounted light emitting element is covered with a transparent material. The shape of the boundary is a concavo-convex shape contrary to the light intensity distribution of the reached light emitting element.

  In the present invention, the light emitting element emits light, and the boundary surface with air is formed in a shape that is inverted upside down so as to transfer the light intensity distribution on the boundary surface between the transparent material and air. The shape of the boundary surface can compensate for the intensity of the light intensity distribution and can emit light to the outside with uniform intensity.

  According to the envelope of the light emitting element of the present invention, the light emitted from the light emitting element can be emitted to the outside with uniform intensity from the surface of the envelope.

<First Embodiment>
FIG. 1 is a sectional view for explaining a first embodiment of an envelope. In FIG. 1, a package 4, a recess 5 provided with an inclined inner wall in the package 4, a light emitting element 1 disposed at the bottom of the recess 5, and bonding for supplying electric power for causing the light emitting element 1 to emit light. A wire 2 and a translucent sealing resin 3 are shown.

  The sealing resin 3 provided in the first embodiment of the envelope shown in FIG. 1 is different in the shape of the boundary surface with the surrounding air as compared with the sealing resin 30 already shown in FIG. Concavities and convexities are formed on the boundary surface of the sealing resin 3 with air, and the shape of the concavities and convexities is the light intensity distribution (c) of the envelope by the sealing resin 30 indicated by the broken line in FIG. A shape for compensating the distribution (a) is provided. This shape is a concavo-convex pattern in which the boundary surface of the sealing resin 3 is substantially transferred by vertically inverting the light intensity distribution (c).

  About this uneven | corrugated pattern, the boundary surface of sealing resin 3 is shown in the boundary surface (b) in FIG. The boundary surface (b) has the highest light intensity in the vicinity of the light emitting element 1 in the light intensity distribution (c). Therefore, the boundary surface of this portion is concave, and the surrounding light intensity is the weakest. The part is formed in a convex shape.

  This is because, when light is transmitted from the high refractive index sealing resin 3 side into the low refractive index air, if the boundary surface is a concave lens shape, the transmitted light 6 is spread over a wide angular range, and the boundary surface is a convex lens. If it is in the shape, the light is condensed in a narrow angle range.

  Therefore, when the boundary surface between the air and the sealing resin 3 is formed in the shape of the sealing resin 3, the boundary surface of the sealing resin 3 is a concave lens in a region where the light intensity is high near the light emitting element 1 and a convex lens in a region where the strength is low. Works.

  Therefore, the effect of compensating the intensity of the transmitted light intensity distribution when the boundary surface of the sealing resin 3 is flat (that is, a flat boundary surface such as the sealing resin 30) is obtained, and uniform strength is obtained from the envelope surface. Can emit light to the outside.

  The light intensity due to the light intensity distribution at the boundary surface (b) with the air of the sealing resin 3 is based on the illuminance of light incident on the boundary surface (b) from the sealing resin 3 side or the luminous flux divergence. The concavo-convex pattern may be formed. Or it determines based on the brightness | luminance in a boundary surface (b), and the uneven | corrugated pattern may be formed.

<Second Embodiment>
FIG. 2 shows a cross-sectional view for explaining a second embodiment of the envelope.

  The sealing resin 7 in the second embodiment of the envelope shown in FIG. 2 has a boundary surface region (d) where the light intensity distribution (c) shown in FIG. Concavities and convexities are provided in a shape that substantially transfers the metal electrode pattern and bonding wire shape on the upper surface of the light emission. The concavo-convex shape includes a concavo-convex pattern in which the region corresponding to the metal electrode pattern and the bonding wire existing on the light emitting surface on the upper side of the light emitting element 1 is convex and the other region is concave. With the boundary surface region (d) having such a concavo-convex pattern, a substantially uniform light intensity distribution can be obtained as shown in the light intensity distribution (a ′) with respect to the light intensity distribution (c).

  Here, the shape of the metal electrode pattern and the bonding wire will be described. First, FIG. 3 shows an explanatory diagram for explaining the positional relationship between the light emitting element 1 and the bonding wire 2. A p-type region 12 and an n-type region 13 bonded to each other are fixed to the surface of the package 4 with a silver paste 10. An electrode pattern 11 is formed on the surface of the p-type region 12, and a bonding wire 2 is connected to the electrode pattern 11.

  Next, FIG. 4 shows an example of the electrode pattern 11. An electrode pattern 11 is formed on a surface that emits light by joining the p-type region 12 and the n-type region 13, and the bonding wire 2 is connected to the electrode pattern 11 to supply power for light emission.

  Thus, since the light generated inside the light emitting element 1 is blocked by the metal electrode pattern 11 on the surface of the light emitting element 1 (for example, the p-type region 12), the light is sealed only from the surface region without the metallic electrode pattern 11. Light is emitted into the resin 7. Even after radiating from the light emitting element 1, the emitted light is blocked by the bonding wire 2.

  Therefore, when the light emitting element 1 is installed in the concave portion 5 of the envelope so as to exhibit strong directivity in a direction perpendicular to the installation surface of the light emitting element, the metal electrode pattern of the light emitting element 1 on the irradiated object. 11 and the shadow of the bonding wire 2 appear clearly.

  In the present embodiment, the light / dark distribution (shadow) of the light intensity distribution derived from the structure of the metallic electrode pattern 11 and the bonding wire 2 of the light emitting element 1 is provided on the boundary surface area of the unevenness provided on the boundary surface of the sealing resin 7 ( Compensation is made uniform by d), and a uniform light intensity distribution characteristic of the light intensity distribution (a ′) can be obtained.

<Third Embodiment>
FIG. 4 is a sectional view for explaining a third embodiment of the envelope.

  The sealing resin 8 in the third embodiment of the envelope shown in FIG. 5 is flip-chip mounted on the boundary surface region (e) where the light intensity distribution (c) shown in FIG. In order to transfer the metal electrode pattern 18 on the back surface of the light emitting element 21 on the installation side, a concave / convex pattern in which the region corresponding to the metallic electrode pattern 18 is concave and the other region is convex is provided. The boundary area (e) provided with such a concavo-convex pattern can provide a substantially uniform light intensity distribution as shown in the light intensity distribution (a ″) with respect to the light intensity distribution (c).

  Here, FIG. 6 and FIG. 7 are explanatory views for explaining the positional relationship between the light emitting element 21 and the bump 18 which are flip-chip mounted. An electrode pattern 17 is provided on the light emitting element 21 disposed on the bottom surface of the package 4. On the other hand, an insulating layer 20 is provided on the bottom side of the package 4, and an electrode pattern 19 is also provided on the surface of the insulating layer 20. The electrode pattern 17 and the electrode pattern 19 are bonded to each other by a bump 18, and flip chip mounting is performed.

  When the light emitting element 21 is flip-chip mounted in this manner, light is mainly generated in the light emitting element directly above the electrode pattern 17 on the back surface on the installation side. In this flip-chip mounting, the metallic electrode and the bonding wire are not present on the observer side surface of the light emitting element 21. For this reason, the light intensity distribution in the light emitting element 21 is transferred to some extent to the light intensity distribution at the boundary surface (e) between the sealing resin 8 and the air. In the present embodiment, the unevenness pattern obtained by substantially transferring the electrode pattern 17 is provided on the boundary surface (e) of the sealing resin with air, thereby eliminating the brightness and darkness in the light intensity distribution, and the light intensity distribution (a ″). Uniform light intensity distribution characteristics can be obtained.

  According to the embodiment of the envelope of the light emitting element described above, the light emitted from the light emitting element can be emitted to the outside with uniform intensity from the surface of the envelope.

Sectional drawing for demonstrating the structure of the envelope in 1st Embodiment is shown. Sectional drawing for demonstrating the structure of the envelope in 2nd Embodiment is shown. Explanatory drawing for demonstrating the structure of the light emitting element in 2nd Embodiment is shown. Explanatory drawing for demonstrating the metal electrode pattern in 2nd Embodiment is shown. Sectional drawing for demonstrating the structure of the envelope in 3rd Embodiment is shown. Explanatory drawing for demonstrating the structure of the light emitting element in 3rd Embodiment is shown. Explanatory drawing for demonstrating the structure of the light emitting element in 3rd Embodiment is shown. Sectional drawing of the structure of the envelope of the conventional light emitting element is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light emitting element 2 ... Bonding wire 3 ... Sealing resin 4 ... Package 5 ... Recessed part

Claims (3)

In a light emitting device in which a light emitting element is mounted on a conductive lead frame, and the mounted light emitting element is covered with a transparent material,
An envelope of a light-emitting element, wherein a shape of a boundary with air radiated from a transparent material is an uneven shape that is contrary to the light intensity distribution of the light-emitting element that has reached.   The light intensity in the light intensity distribution on the boundary surface with the air of the transparent material is an illuminance of light incident on the boundary surface from the transparent material side or a luminous flux divergence. The envelope of the light emitting element according to 1.   2. The envelope of a light emitting element according to claim 1, wherein the transparent material has a light intensity in a light intensity distribution on an interface with air as brightness at the interface.

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