JP2011119402A - Light source unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source of white light of high uniformity by eliminating the unevenness of the emission color of a light source unit that subjects the emission light of an LED element to wavelength conversion using a fluorescent material to generate white light. <P>SOLUTION: The light source unit includes a cup-shaped resin case integrally holding a metal base and a metal lead by insert molding, and an LED element stuck on the metal base inside the resin case, an electrode of the LED element being connected to the metal lead by a connection wire inside the resin case, the LED element being sealed by a sealing resin layer formed by packing a transparent sealing resin to which a fluorescent material converting excitation light into visible light having a different wavelength from the wavelength of the excitation light is added. The resin sealing layer is separated into two upper and lower layers. Each of the layers separated is made of the transparent sealing resin to which the fluorescent material is added. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light source unit in which a light emitting diode (hereinafter referred to as LED) is used as a light emitting source, which is molded and sealed with a resin.

  As a light source unit configured by molding an LED element with a resin, as shown in Patent Document 1, it is excited by light emitted from the LED element in a resin that seals the LED element and has a wavelength different from the wavelength of the excitation light. A material to which a fluorescent material that converts visible light is added is known.

  FIG. 3 shows the configuration of a conventional light source unit 20 of this type. 21 is an LED element, 22 is a metal base composed of a lead frame, and 23 and 24 are metal leads similarly composed of a lead frame. Reference numeral 25 denotes a cup-shaped resin case formed by insert-molding the metal base 22 and the metal leads 23 and 24 with resin while being coupled to the lead frame. The LED element 21 is fixed on the exposed surface of the metal base 22 in the resin case 25, and the connection line 26 made of a gold wire or the like is connected to the two surface electrodes (not shown) of the LED element 21 and the metal leads 23 and 24. Are connected by wire bonding. Thereafter, the LED element 21 is sealed with a resin sealing layer 28 formed by filling a transparent sealing resin to which a fluorescent material 27 is added into a space in which the LED element 21 of the resin case 25 is housed, thereby providing a light source. A unit 20 is formed. A plurality of light source units are formed on one lead frame, but are separated from each other by cutting from the lead frame stay.

  In such a light source unit 20, when a DC voltage is applied between the metal leads 23 and 24, the LED element 21 emits light, and the fluorescent material 27 added in the sealing resin layer 28 is emitted by the LED light. When excited, it is converted into visible light having a wavelength different from that of the LED light to generate white light.

  By the way, in the light source unit 20 configured to emit white light by such wavelength conversion, when the resin sealing layer 28 is made of a thermosetting resin, the sealing resin filled in the resin case 25 is heated and cured. In the process, the sealing resin is temporarily fluidized and liquefied. Since the specific gravity of the fluorescent material 27 added to the sealing resin due to the liquefaction of the sealing resin is heavy with respect to the resin, the fluorescent material 27 settles in the sealing resin, and most of them are in the voids of the resin case 5. Deposit on bottom and layer. As a result, most of the fluorescent material 27 in the resin sealing layer 28 formed by curing the sealing resin is a layer unevenly distributed at the bottom of the resin sealing layer 28 as shown in FIG.

  As described above, when the fluorescent material 27 is unevenly distributed at the bottom of the resin sealing layer 28, the emitted light mainly from the peripheral side surface of the LED element 21 does not hit the fluorescent material 27 and is directly emitted to the outside. For this reason, the excitation efficiency of the fluorescent material by the LED element 21 is lowered, the color of the emitted color is uneven, and uniform white light cannot be obtained.

  In order to eliminate the occurrence of the uneven color of the light emission color of the light source unit, in Patent Document 2, as shown in FIG. 4, a resin sealing layer 28 for sealing the LED element 21 is formed by the first resin sealing. A light source unit 30 that is divided into a layer 28a and a second resin sealing layer 28b and has a two-stage structure has been proposed.

  The lower first resin sealing layer 28a directly covering the LED element 21 is formed by filling only a transparent sealing resin to which no fluorescent material is added, and the upper resin sealing layer 28b is formed by filling the first resin sealing layer 28b. After the sealing resin of the stop layer 28a is cured, the transparent sealing resin to which the fluorescent material 27b is added is filled from above.

  According to the light source unit 30 having such a configuration, even when the fluorescent material 27b added to the resin settles during the process of heat-curing the sealing resin of the resin sealing layer 28, Since the resin stays at the bottom near the boundary with the first resin sealing layer 28a at the lower stage of the one resin sealing layer 28a, the fluorescent material 27b is above the upper surface of the LED element 21 as shown in FIG. It is deposited near the middle part of the film and forms a layer.

  For this reason, in the light source unit 30, since the layer of the fluorescent material 27 b exists at a position above the upper surface of the LED element 21, most of the emitted light from the LED element 21 comes into contact with the fluorescent material 27 b. The excitation efficiency of the fluorescent material is increased, the wavelength conversion efficiency of the emitted light by the fluorescent material 7 is increased, the occurrence of uneven color of the emitted color is suppressed from the conventional light source unit 20 shown in FIG. Can be increased.

Japanese Patent No. 2900928 JP 2000-077723 A

  However, the conventional light source unit 30 shown in FIG. 4 in which the occurrence of uneven color of the emission color is improved also has the following disadvantages.

  That is, on the upper surface electrode (not shown) of the LED element 21 of the light source unit 30, a connection line 26 having one end connected to supply current to the LED element 21 connects the other end to the metal leads 23 and 24. When being done, the middle part is curved in an arc. The top of the curved portion of the connection line 26 may protrude from the upper surface of the first resin sealing layer 28 a of the resin sealing layer 28. In such a case, when the first resin sealing layer 28a is liquefied during the heat curing process, the first resin sealing layer 28a rises to the vicinity of the top along the connection line 26 due to the surface tension of the resin. It cannot be a flat surface. A raised portion is formed at the bottom of the second resin sealing layer 28b in contact with the portion crawled up along the connection line 26 of the first resin sealing layer 28a, and the fluorescent material added in the resin is formed in the raised portion. 7 is difficult to deposit, and the fluorescent material 27b is not distributed or distributed even if it is distributed, and the wavelength conversion efficiency of the emitted light of the LED element 1 in this portion is lowered. As a result, the emission color is uneven at the curved portion of the connection line 26 connected to the LED element 21, that is, the central portion of the light source unit 30, and uniform white light cannot be obtained.

  An object of the present invention is to provide a light source unit that eliminates such disadvantages and generates more uniform white light.

  In order to solve such problems, the present invention includes a cup-shaped resin case that integrally holds a metal base and a metal lead by insert molding, and an LED element is fixed on the metal base in the resin case. In the resin case, the electrode of the LED element and the metal lead are connected by a connecting line, and a transparent material to which a fluorescent material that converts the excitation light into visible light having a wavelength different from the wavelength of the light is added. In the light source unit formed by sealing the LED element with a resin sealing layer formed by filling a sealing resin, the resin sealing layer is divided into two upper and lower layers, and each of the divided layers is It is formed by a transparent sealing resin to which a fluorescent material is added.

  In the present invention, a light reflecting surface is preferably formed on the inner peripheral surface of the cup-shaped resin case and on the exposed surfaces of the metal base and the metal lead. Further, the metal base and the metal lead can be constituted by a lead frame.

  In the present invention, when the resin sealing layer for sealing the LED element of the light source unit is formed of a transparent resin to which a fluorescent material is added, the resin sealing layer is divided into two upper and lower layers. By forming each with a transparent resin to which a fluorescent material is added, a dispersed layer of the fluorescent material is formed on each of the two separated layers of the resin sealing layer, and the fluorescent materials of each layer complement each other, so that the entire fluorescent layer is fluorescent. Since the wavelength conversion of the material is effectively performed, the occurrence of color unevenness is suppressed and white light with high uniformity can be generated.

It is a longitudinal cross-sectional view which shows the structure of the Example of the light source unit of this invention applied to the light source of the indicator lamp integrated in an illumination type pushbutton switch etc. It is a longitudinal cross-sectional view which expands and shows the part of the light source unit of the indicator lamp shown in FIG. It is a longitudinal cross-sectional view which shows the structure of the conventional light source unit. It is a longitudinal cross-sectional view which shows the structure of the conventional improved light source unit.

  Embodiments of the present invention shown in the drawings will be described below.

  FIG. 1 is a longitudinal sectional view showing a configuration of an embodiment of a light source unit of the present invention applied to a light source of an indicator lamp incorporated in an illuminated push button switch or the like, and FIG. 2 is an enlarged view of the light source unit portion of the indicator lamp. It is a longitudinal cross-sectional view shown.

  In FIGS. 1 and 2, reference numeral 50 denotes an indicator lamp, and 10 denotes a light source unit incorporated in the indicator lamp 50. The holder 51 of the indicator lamp 50 that holds the light source unit 10 is provided with external connection terminals 52 and 53, and is connected to the metal leads 13 and 14 of the light source unit via current limiting resistors 54 and 55.

  The light source unit 10 includes a cup-shaped resin base 15 in which a metal base 12 and metal leads 13 and 14 are integrally formed by insert molding, and the LED element 11 is placed on the exposed surface of the metal base 12 in the space of the resin base 15. Stick. One end of a connection line 16 made of a gold wire or the like is joined to a surface electrode (not shown) of the LED element 11, and the other end is made of resin of the metal leads 13 and 14 while curving an intermediate portion of the connection line 16 in an arc shape. The electrodes of the LED element 11 and the metal leads 13 and 14 are connected by bonding to the surface exposed from the base 15. As a result, the electrode of the LED element 11 is connected to the external connection terminal 52.53 via the current limiting resistors 54 and 55.

  By filling the empty space of the cup-shaped resin base 15 containing the LED element 11 with a transparent sealing resin to which a fluorescent material 17 that converts excitation light into visible light having a wavelength different from the excitation light is added, the LED A resin sealing layer 18 for sealing the element 11 is formed. As the sealing resin, for example, a thermosetting transparent resin such as an epoxy resin is used.

  The resin sealing layer 18 includes a first resin sealing layer 18a and a second resin sealing layer 18b that are divided into two upper and lower layers. The two resin sealing layers 18 can be formed by filling the transparent sealing resin to which the fluorescent material is added in two portions.

  That is, first, a transparent sealing resin to which the fluorescent material 17a is added is filled in a space in which the LED element 11 of the resin base 15 is accommodated to a half depth of the space, and this is heated and cured to be first. A resin sealing layer 18a is formed. Then, the space where the LED element 11 of the resin base 15 is accommodated is filled with the transparent sealing resin to which the fluorescent material 17b is added from above the first resin sealing layer 18a to the remaining space. The second resin sealing layer 18b is formed by heat curing. The sealing resin and the fluorescent material constituting the first resin sealing layer 18a and the second resin sealing layer 18b are not necessarily the same material, and may be different materials.

  As shown in FIG. 2, the first resin sealing layer 18a and the second resin sealing layer 18b divided into two layers in the resin sealing layer 18 in the light source unit 10 thus completed are provided at the bottom of each layer as shown in FIG. The fluorescent materials 17a and 17b are deposited to form a fluorescent material layer. In this way, the fluorescent material layer is formed at the bottom of the first and second resin sealing layers 18a and 18b, which is dispersed and added to the entire transparent sealing resin forming the resin sealing layer. This is because the fluorescent material settles and deposits due to the specific gravity of the fluorescent material being heavier than that of the resin when the sealing resin is temporarily fluidized and becomes liquid during the heat curing process of the thermosetting sealing resin. is there.

  In the first resin sealing layer 18a, the fluorescent material 17a deposited on the bottom and the surface of the LED element 11 forms a fluorescent material layer. In the second resin sealing layer 18b, the fluorescent material 17b deposited on the bottom of the second resin sealing layer 18b, which is the boundary between the first resin sealing layer 18a and the second resin sealing layer 18b, is a fluorescent material layer. Form. In the portion where the connection line 6 protrudes from the first resin sealing layer 18a, the upper surface is raised because the connection resin 16 is pulled up by the surface tension of the sealing resin. For this reason, the bottom surface of the second resin sealing layer 18b that contacts the top surface of the first resin sealing layer 18a also protrudes at the portion where the connection line 16 enters. In the raised portion of the second resin sealing layer 18b, there is little or no deposition of the fluorescent material, and the distribution of the fluorescent material becomes dilute.

  The metal base 12 and the metal leads 13 and 14 are optimally constituted by a lead frame provided with a large number of these. And it is good to finish so that the inner peripheral wall surface 15a of the space in which the LED element 11 of the resin base 15 is accommodated, and the upper surfaces of the metal base 12 and the metal leads 13 and 14 may be light reflecting surfaces.

  In the light source unit 10 configured as described above, the LED element 11 emits light when a DC voltage is applied to the external connection terminals 52 and 53 from an external power source. The emitted light of the LED element 11 is radiated to the surroundings and travels straight through the two resin sealing layers 18a and 18b of the resin sealing layer 18 or is reflected by the inner peripheral surface 15a of the resin base 15 and the like. To be emitted.

  When the emitted light of the LED element 11 travels through the sealing resin layers 18a and 18b, the fluorescent material layer formed on the bottom of each resin sealing layer hits the fluorescent materials 17a and 17b to excite the fluorescent material layer 17a. 17b perform the action of converting the light emitted from the LED element 11 into visible light having a wavelength different from that of the LED element 11, and white light is generated.

  Along the connection line 16 to the vicinity of the top of the curved portion of the connection line 16 connected between the LED element 11 at the bottom of the second resin sealing layer 18b in the upper stage of the resin sealing layer 18 and the metal leads 13 and 14. Since the fluorescent material 17b is hardly deposited on the pulled up portion, the light emitted from the LED element 11 is radiated to the outside without being wavelength-converted in this vicinity.

  However, in the present invention, the fluorescent material 17a is also added to the lower first resin sealing layer 18a, and the fluorescent material 17a is deposited on the upper surface of the LED element 11 in the process of being settled and deposited on the bottom. To come. The fluorescent material 17a deposited on the upper surface of the LED element 11 is excited by the light emitted from the LED element 11 and converts the wavelength of the light emitted from the LED element 11, so that the wavelength-converted visible light moves upward from here. Since it progresses and emits to the outside through a portion where the fluorescent material 17b is not deposited on the LED element 11 of the upper second resin sealing layer 18b, color unevenness occurs in this portion. Suppressed and more uniform white light can be obtained.

  As described above, according to the present invention, both the upper and lower two resin sealing layers constituting the resin sealing layer for sealing the LED element are formed of the transparent resin to which the fluorescent material is added, thereby encapsulating the resin. Since the fluorescent materials of the two resin-encapsulated layers separated from each other complement each other and wavelength conversion by the fluorescent material can be effectively performed as a whole, the occurrence of color unevenness is suppressed and uniformity is achieved. High white light can be generated.

10: Light source unit 11: LED element 12: Metal base 13, 14: Metal lead 15: Resin base 16: Connection lines 17, 17a, 17b: Fluorescent material 18, 18a, 18b: Resin sealing layer 50: Indicator lamp

Claims (3)

  A cup-shaped resin case for integrally holding a metal base and a metal lead by insert molding is provided, and an LED element is fixed on the metal base in the resin case, and the electrode of the LED element and the electrode in the resin case A sealing resin layer formed by filling a metal lead with a transparent sealing resin added with a fluorescent material that converts excitation light into visible light having a wavelength different from the wavelength of the light while connecting the lead with a connection line. In the light source unit formed by sealing the LED element, the resin sealing layer is divided into two upper and lower layers, and each of the divided layers is formed of a transparent sealing resin to which the fluorescent material is added. A light source unit characterized by   2. The light source unit according to claim 1, wherein a light reflecting surface is formed on an inner peripheral surface of the cup-shaped resin case and exposed surfaces of the metal base and the metal lead.   The light source unit according to claim 1, wherein the metal base and the metal lead are constituted by a lead frame.

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