JP3969660B2 - White LED lamp - Google Patents

Description

  The present invention relates to an LED lamp, and more specifically, an LED chip that emits blue light is employed, and is also excited by light from the LED chip in a resin that covers the periphery of the LED chip to protect it. The present invention relates to a configuration of a white LED lamp in which phosphors that emit yellow light are dispersed so that white light emission that is a mixed color of blue and yellow can be obtained at the time of lighting.

As a conventional method of forming this type of white LED lamp 90, as shown in FIG. 11, in order to protect the LED chip 92 mounted on the substrate 91, a lens 93 for covering the LED chip 92 is formed. The phosphor 93b is mixed in the transparent epoxy resin 93a at a predetermined ratio (for example, 25% by weight), placed at a predetermined position by an appropriate means such as a printing means or an injection means, and solidified by thermosetting or the like. is there. (For example, refer to Patent Document 1.)
JP 2000-223750 A (paragraphs 0033 to 0037, FIG. 3)

  Here, in the LED lamp, since white light emission can be obtained, for example, new uses such as household lighting fixtures, vehicle lighting fixtures, and portable lighting fixtures are considered. It has become to. However, the above-described conventional LED lamp has problems that it is difficult to improve the light emission efficiency more than the present due to the occurrence of confusion loss and the low effectiveness when the reflector is provided.

  That is, the confusion loss is caused by the fact that the phosphors are uniformly dispersed throughout the resin covering the LED chip, so that the light emitted from the LED chip has a long distance to pass through the region where the phosphor exists. This is a phenomenon that occurs due to the confusion (diffusion) that is stronger than necessary due to contact with a plurality of phosphors, and the light from the LED chip is directed to the side of the LED chip in the irradiation direction due to the same factors. Even if a reflector that reflects light is provided, a substantial effect cannot be expected for light that is excessively confused and loses directionality.

The present invention provides an active layer made of a gallium nitride compound semiconductor (In _x Al _Y Ga _1-XY N, 0 ≦ Y, X + Y ≦ 1) as a specific means for solving the above-described conventional problems. The LED chip is mounted on the wiring pattern in the chip mounting recess of the surface mounting type package formed of a ceramic member provided with a chip mounting recess having a silver plated reflector formed on the inner surface. We have, an inner mold layer by molding resin phosphor covering substantially cylindrical in an appropriate thickness around this LED chips are dispersed in the LED chip, so as to cover the outside of the inner mold layer child provide white LED lamp, wherein a mold of a double layer composed of an outer mold layer of a transparent mold resin is filled in the chip-mounting recess is being performed In is intended to solve the problem.

As described above, according to the present invention, an LED chip having an active layer made of a gallium nitride-based compound semiconductor (In _X Al _Y Ga _1-XY N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) A package having a chip mounting recess having a reflector formed on the inner surface thereof is attached to the wiring pattern in the chip mounting recess by bonding, and the LED chip is surrounded by an appropriate wall around the LED chip. An inner mold layer made of a mold resin in which a phosphor covering a substantially cylindrical shape is dispersed, and an outer mold layer made of a transparent mold resin filled in the chip mounting recess so as to cover the outside of the inner mold layer By adopting a white LED lamp that has been molded in multiple layers, the number of times of contact with the phosphor is optimized in the optical path until the light emitted from the LED chip is emitted to the outside. Excessive diffusion caused by a number of contacts, eliminating the internal loss in the light amount caused by confusion, in which exhibits the excellent effect in improving the performance of this type of white LED lamps.

  In addition, since excessive diffusion is not performed as described above, the light emitted from the LED chip has directionality even after passing through the phosphor layer, and the light is emitted from the inner surface of the chip housing recess. When the reflector is formed, it can be reflected and emitted outside the package. Therefore, the light collected as the output light of the white LED lamp by the reflector can be added as an output, and the performance can be further improved.

  Below, this invention is demonstrated in detail based on embodiment shown in a figure. 1 and 2 show a first embodiment of a white LED lamp 1 according to the present invention. In the white LED lamp 1 of the present invention, for example, a package 2 formed of an insulating member such as ceramic or resin. A chip housing recess 2a is formed from the top surface, and a wiring pattern 2b is formed on the bottom surface of the chip housing recess 2a by a conductive member. The wiring pattern 2b extends to the back surface of the package 2 to be a terminal portion. 2c.

  Then, the LED chip 3 is soldered to one side of the wiring pattern 2b, die-bonded with a conductive adhesive or the like, wire-bonded with the other wiring pattern 2b and the gold wire 4, and the terminal portion from the back surface of the package 2 The LED chip 3 can be turned on by supplying power to 2c. In the present invention, a reflector 5 is formed on the side surface of the chip housing recess 2a by a reflection process such as silver plating (evaporation).

  Next, the inner mold layer 6 is formed by covering the LED chip 3 with a member in which the phosphor 6b is dispersed in the transparent silicone resin 6a. At this time, the inner mold layer 6 is mixed with blue light emitted from the LED chip 3 and yellow light that is excited when the light from the LED chip 3 comes into contact with the phosphor 6b in the inner mold layer 6. An optimum amount of the phosphor 6b is obtained to obtain white light. As the phosphor 6b, a cerium activated yttrium aluminate phosphor is used.

  In forming the inner mold layer 6, for example, the top surface is a hemispherical cylinder so that the light path when the light from the LED chip 3 passes through the inner mold layer 6 is not so long. ing. Then, after the inner mold layer 6 is formed, heating at a temperature of about 80 ° C. and lower than the curing temperature is performed, and temporary curing is performed while leaving a reactive group.

  Subsequently, only the transparent silicone resin to which the phosphor 6b is not added is injected into the remaining portion of the chip housing recess 2a to form the outer mold layer 7. Thereafter, the whole is heated at a temperature of 80 ° C. or higher to perform a curing process. By doing so, the remaining reactive groups in the inner mold layer 6 also react, and the inner mold layer 6 and the outer mold layer 7 are integrated and cured.

  Next, the operation and effect of the white LED lamp 1 of the present invention formed as described above will be described. FIG. 3 shows the light distribution characteristics Dnw and Dnn in the white LED lamp 1 according to the present invention. The light distribution characteristic Dnw is in a direction parallel to the major axis side of the package 2, that is, the major axis side of the chip housing recess 2a. The light distribution characteristic Dnn is a light distribution characteristic corresponding to the short diameter side.

  When the light distribution characteristics Dnw and Dnn are observed, the amount of light in the left and right directions of 30 to 40 ° to which the reflected light of the reflector 5 is added is clearly larger than the front direction of the package 2, and the white LED lamp of the present invention It can be seen that the light from 1 has a directionality with the LED chip 3 as the center of light emission, and therefore the light reaching the reflector 5 is reflected in the irradiation direction.

  On the other hand, the light distribution characteristics Dow and Don shown in FIG. 4 are the light distribution characteristics in the conventional white LED lamp in which the phosphor is uniformly dispersed throughout the transparent resin injected into the chip housing recess 2a. The light distribution characteristic Dow is the light distribution characteristic with respect to the major axis side of the package, and the light distribution characteristic Don is the light distribution characteristic with respect to the minor axis side.

  When the light distribution characteristics Dow and Don are observed, the light distribution characteristics Dow and Don have the highest illuminance in the front direction of the package, and are substantially circular light distribution characteristics in which both overlap. It shows a light distribution characteristic indicating a tendency, and no light distribution increase effect by the reflector 5 is recognized in any light distribution characteristic Dow, Don.

  That is, in the conventional configuration in which the phosphor is uniformly dispersed throughout the transparent silicone resin filled in the chip housing recess 2a, the light emitted from the LED chip is contained in the resin filled in the chip housing recess 2a. At the time of the process of passing through, a collision with the phosphor more than necessary is already performed, and a portion which is diffused and lost every time the collision occurs is generated. Therefore, when reaching the reflector, the directionality is lost due to the diffusion, and no reflection in a specific direction occurs, and the reflector does not function.

  On the other hand, in the white LED lamp 1 having the configuration of the present invention, the phosphor 5 is emitted only from the inner mold layer 6 having a limited thickness. The number of times the light collides with the fluorescent substance 6b is optimized, and excessive diffusion due to the excessive number of collisions is not performed, thereby preventing the occurrence of internal loss due to this and the direction of light. As a result, the reflector 5 can also reflect in the irradiation direction as the white LED lamp 1 and further increase the amount of light.

  A light amount curve Bn shown in FIG. 5 shows a state of light amount change when the amount of the phosphor 6b added in the inner mold layer 6 in the present invention is changed. FIG. The state of change of the light amount curve Bo when the addition amount is changed in a state where the phosphor is uniformly dispersed in the entire transparent silicone resin filled in the recess 2a is shown.

  First, in the case of the present invention (see FIG. 5), the state when the ratio of the phosphor 6b mixed and dispersed in the transparent silicone resin 6a of the inner mold layer 6 is increased by weight% for a while. The brightness is improved as the addition rate increases, and the addition of about 60% by weight adds the amount of luminous flux emitted from the LED chip in this state, and converts the wavelength from the phosphor. The sum of the light amounts thus reached reaches about 80 (lm / W) which is considered to be the maximum value.

  On the other hand, in the case of the conventional example, saturation is recognized in the increase value of luminance by adding about 12 (wt%) phosphor, and the maximum value of luminance at that time is about 68 (lm / W). . The difference between the two values is that light from the LED chip is radiated to the outside through the layer in which the longer (thick) phosphor is present in the configuration of the conventional example. It can be considered that the number of collisions increased, causing diffusion more than necessary and causing internal loss.

  Here, when the addition amount of the phosphor of the present invention and the conventional example is simply compared, for example, the efficiency at the same 10 (% by weight) is about 66 (lm / W) in the conventional example, and about 47 (lm / W), the efficiency of the conventional example seems to be higher, but this is because the total amount of the standard transparent silicone resin is overwhelmingly large and the use of phosphors The amount of the present invention is smaller in amount.

  As described above, according to the present invention, the inner mold layer 6 in which the transparent silicone resin 6a and the phosphor 6b are mixed at an appropriate ratio is formed, and the outer mold layer 7 made of only the transparent silicone resin is formed on the outer side. By using the white LED lamp 1, first, it is possible to arrange an appropriate amount of the phosphor 6b with respect to the light from the LED chip as an appropriate transmission distance, and to avoid excessive scattering. Increase the amount of light that can be taken out to the outside.

  Second, by preventing excessive scattering as described above, light can be reflected in the irradiation direction of the white LED lamp 1 when the reflector 5 is provided on the side surface of the chip housing recess 2a or the like. As a thing, the further light quantity increase is enabled.

  FIG. 7 shows a second embodiment of the white LED lamp 1 according to the present invention. The LED chip 31 in this second embodiment has an InGaN active layer on a sapphire substrate and a pair of positive electrodes on the upper surface. A negative electrode is provided. The sapphire substrate side is fixed to the chip housing recess 2a of the package 2 with an adhesive or the like, and positive and negative electrodes are wire-bonded to the respective wiring patterns 2b with gold wires 4, and thereafter, as in the first embodiment. Thus, the inner mold layer 6 and the outer mold layer 7 are formed.

  FIG. 8 shows a third embodiment of the white LED lamp 1 according to the present invention. The LED chip 31 in this third embodiment has an InGaN active layer on a sapphire substrate and a pair of positive electrodes on the upper surface. The same one as that of the second embodiment provided with the negative electrode is used. However, the attachment to the package 2 is performed by so-called face-down in which the upper and lower surfaces are reversed and fixed to the wiring pattern 2b on the positive and negative electrode sides. Thereafter, the inner mold layer 6 and the outer mold layer 7 are formed in the same manner as in the first embodiment and the second embodiment.

  FIG. 9 shows a fourth embodiment of the white LED lamp 1 according to the present invention. In the first to third embodiments described above, one LED chip 3 (31) is incorporated in the package 2. However, the present invention is not limited to this, and a plurality may be mounted as shown in FIG. The shape of the LED chip 3 (31) can be any of the first to third embodiments.

  FIG. 10 shows a fifth embodiment of the white LED lamp 1 according to the present invention, and the first to fourth embodiments described above differ in the shape, number, or mounting method of the LED chips. However, in the fifth embodiment, there is a difference in the configuration of the inner mold layer.

  That is, in the present invention, the mold performed in the chip housing recess 2a is formed as two layers of the inner mold layer 61 and the outer mold layer 7, but in this embodiment, in addition, the inner mold layer 61 is further added. Is configured as two layers of an inner layer 61a and an outer layer 61b.

  The inner layer 61a covers the LED chip 3 with a transparent silicone resin 6a mixed with a relatively small weight% of the phosphor 6b or only with the transparent silicone resin 6a, and is a hemisphere called a dome shape or the like. It is formed as a cylindrical shape having a shape-like top.

  The outer layer 61b is formed so as to cover the inner layer 61a with a certain thickness. At this time, white light can be obtained by mixing with direct light from the LED chip 3 (31). A transparent silicone resin 6a in which a sufficient amount of phosphor 6b is mixed and dispersed is used.

  By doing in this way, the light radiated | emitted from LED chip 3 (31) will permeate | transmit the outer layer 61b of the substantially the same distance even if it goes to which direction, ie, with respect to the fluorescent substance 6b. The number of collisions and the like can be almost the same. Therefore, the white LED lamp 1 formed according to this embodiment does not cause color unevenness, for example, the hue varies depending on the viewing direction.

  In addition, although the thing of above-described 1st embodiment-5th embodiment was shown in the example which employ | adopted so-called surface mount type package 2 formed with the resin member etc., this invention limits this However, in this type of white LED lamp, in recent years, for example, a lighting application that replaces an incandescent bulb, such as a light source of a flashlight, has been studied.

  In this case, since the amount of light is required and the driving power is increased, the LED chip 3 needs to be cooled more than before. For example, the portion where the LED chip 3 is die mounted may be formed as a metal block having excellent heat conduction. is there. The present invention can naturally be implemented in such a case, that is, the shape of the package 2 is not limited.

It is a top view which shows 1st embodiment of the white LED lamp which concerns on this invention. It is sectional drawing which follows the AA line of FIG. It is a graph which shows the light distribution characteristic of the white LED lamp which concerns on this invention. It is a graph which shows the light distribution characteristic of a prior art example. It is a graph which shows the relationship between the addition amount and the light quantity of the fluorescent substance in the white LED lamp which concerns on this invention. It is a graph which shows the relationship between the addition amount of the fluorescent substance of a prior art example, and a light quantity. It is sectional drawing which similarly shows 2nd embodiment of the white LED lamp which concerns on this invention. It is sectional drawing which similarly shows 3rd embodiment of the white LED lamp which concerns on this invention. It is sectional drawing which similarly shows 4th embodiment of the white LED lamp which concerns on this invention. It is sectional drawing which similarly shows 5th embodiment of the white LED lamp which concerns on this invention. It is sectional drawing which shows a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... White LED lamp 2 ... Package 2a ... Chip accommodation recessed part 2b ... Wiring pattern 2c ... Terminal part 3, 31 ... LED chip 4 ... Gold wire 5 ... Reflector 6, 61 ... Inner mold layer 6a …… Transparent silicone resin 6b …… Phosphor 61a …… Inner layer 61b …… Outer layer 7 …… Outer mold layer

Claims (2)

An LED chip having an active layer made of a gallium nitride compound semiconductor (In _x Al _Y Ga _1-XY N, 0 ≦ Y, X + Y ≦ 1) has a chip mounting recess in which a silver plated reflector is formed on the inner surface. of it provided with a surface mounting type package formed by a ceramic member and said chip by bonding to the wiring pattern of the mounting in the recess are carried out mounting, appropriate meat surrounding this LED chips in the LED chip An inner mold layer made of a mold resin in which a phosphor covering a substantially cylindrical shape is dispersed, and an outer mold layer made of a transparent mold resin filled in the chip mounting recess so as to cover the outside of the inner mold layer A white LED lamp characterized in that a multilayer molding is performed.   2. The white LED lamp according to claim 1, wherein the inner mold layer is composed of a plurality of layers having different concentrations of dispersed phosphors.

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