JPWO2008096714A1 - Resin-sealed light emitting device, planar light source, method for producing the same, and liquid crystal display device - Google Patents

Abstract

A light emitting element and a light flux controlling member made of a thermoplastic resin formed into a shape capable of controlling a light flux emitted from the light emitting element, a light emitting surface of the light emitting element and a light incident surface of the light flux controlling member. A method for producing a resin-sealed light emitting element, wherein the curable resin is cured and bonded with a curable resin interposed therebetween.

Description

  The present invention relates to a resin-sealed light emitting device including a light flux controlling member, a planar light source, a manufacturing method thereof, and a liquid crystal display device.

  A light emitting diode (LED) element, which is a typical light emitting element, joins a p-type semiconductor and an n-type semiconductor, joins each of them to a positive electrode and a negative electrode, applies a voltage in the forward direction, and applies a voltage in the forward direction. It is an element that emits light by combining holes (holes) and electrons (electrons) of an n-type semiconductor near a pn junction.

  Such an LED element is applied to a light source of a projector or a backlight for a flat panel display such as a liquid crystal display device. For example, Patent Literature 1 discloses a technology in which LEDs of three primary colors of blue, green, and red are arranged to form an optical element, projected onto a liquid crystal panel to produce white light, and used as a display backlight. Yes.

Backlights using LED elements have a longer life than those using conventional cold-cathode tubes and are advantageous for widening the color gamut of displays. In order to uniformly illuminate a certain area, it is necessary to appropriately control the directivity of the luminous flux of each LED element. An LED element having a structure for controlling the directivity of a radiation beam is disclosed in, for example, Patent Document 2. Examples of an LED element suitable for a light source of a backlight device and a backlight device using the LED element are disclosed in Patent Literature 3 and Patent Literature 4.
International Publication No. WO03 / 107319 Pamphlet US Pat. No. 5,013,144 JP 2006-286906 A JP 2006-92983 A

  As described in Patent Document 2, in order to form a structure for controlling the directivity of a radiated light beam, a method of curing the epoxy resin while the LED element is immersed in a liquid epoxy resin However, in such a molding method, it is difficult to manufacture a highly accurate element due to curing shrinkage of epoxy resin, generation of reaction heat, and the like, and the manufacturing efficiency is also lowered.

  Therefore, an object of the present invention is to provide a method for efficiently manufacturing a light emitting device in which the light loss is reduced to a sufficient level. Another object of the present invention is to provide a planar light source using such a light emitting element as a light source, a method for manufacturing the same, and a liquid crystal display device using the planar light source.

  A method for manufacturing a resin-sealed light emitting device according to the present invention includes: a light emitting device; and a light beam control member made of a thermoplastic resin that is molded into a shape capable of controlling a light beam emitted from the light emitting device. The curable resin is cured and bonded in a state where the curable resin is interposed between the surface and the light incident surface of the light flux controlling member.

  Here, the curable resin is preferably a thermosetting resin, and when such a resin is used, the resin-sealed light-emitting element can be obtained by the following method. That is, a light emitting element and a light flux control member made of a thermoplastic resin molded in a predetermined shape are prepared, and a light emitting surface of the light emitting element and a light incident surface of the light flux control member are provided as a monomer composition of a thermosetting resin. The resin-encapsulated light-emitting element is manufactured by the manufacturing method, wherein the monomer composition is heat-cured at a predetermined curing temperature and the light-emitting element and the light flux controlling member are consolidated at a predetermined relative position. Can be provided.

In the present invention, it is preferable that the temperature Tc (° C.) at which the curable resin is cured and bonded and the heat distortion temperature Td (° C.) of the thermoplastic resin satisfy the following formula (1).
Tc ≦ Td-20 (1)

  The refractive index after curing of the curable resin is preferably lower than the refractive index of the material constituting the light emitting surface of the light emitting element and higher than the refractive index of the thermoplastic resin. As such, an episulfide resin or a thiourethane resin can be used.

  Particularly preferable as the light flux controlling member is a light flux controlling member in which a concave portion for accommodating the light emitting element is provided on the light incident surface, the concave portion has a curved surface, and the surface thereof is smooth. That is, it is preferable that a concave portion for accommodating the light emitting element is provided on the light incident surface of the light flux controlling member, and the surface of the concave portion is constituted by a smooth curved surface.

  In this case, it is particularly preferable that the concave portion has a spherical shape, and the light emitting point of the light emitting element is located at the center of curvature of the spherical shape.

  The light-emitting elements in the present invention are not limited to a single light-emitting element, and may be a plurality of light-emitting elements fixed in advance in a predetermined arrangement on a substrate. That is, the light emitting element is a plurality of light emitting elements arranged on the substrate, and a plurality of resin-sealed light emitting elements can be arranged to form an array by joining each of the light emitting elements and the light flux controlling member.

  Note that a light emitting diode (LED) can be used as the light emitting element, and it is particularly preferable to use a bare chip LED element.

  The resin-encapsulated light emitting device can be manufactured by the above manufacturing method. That is, a resin-sealed light emitting element having a light emitting element and a light flux controlling member made of a thermoplastic resin shaped into a shape capable of controlling the light emitted from the light emitting element, the light emitting surface of the light emitting element and the light flux A resin-sealed light-emitting element in which a light incident surface of a control member is bonded with a cured product of a curable resin is provided.

  In addition, a planar light source can be manufactured by applying the manufacturing method of the present invention. That is, a method for producing a planar light source is provided, which includes a step of producing a resin-sealed light emitting device by the above-described method for producing a resin-sealed light emitting device and a step of arranging the resin-sealed light emitting device as a light source in a planar shape. Is done. The planar light source thus obtained can be disposed on the backlight surface of a transmissive liquid crystal panel to form a liquid crystal display device.

  According to the resin-sealed light emitting device and the planar light source manufacturing method provided by the present invention, a resin-sealed light emitting device including a light flux controlling member and a planar light source device using the resin-sealed light emitting device as a light source are efficiently used. Can be manufactured well.

It is sectional drawing which shows an example of a resin sealing light-emitting device. It is sectional drawing which shows the example of a light beam control member It is sectional drawing which shows the example of a board | substrate and a light emitting element. It is a perspective view of a resin sealing light emitting element. It is sectional drawing which shows the example of a board | substrate and a light emitting element. It is sectional drawing which shows an example of a planar light source.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Light flux control member, 2 ... Light emitting element, 3 ... Board | substrate, 4 ... Hardened | cured material of curable resin, 5 ... Diffuser plate, 10, 11 ... Resin sealing light emitting element.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as the case may be, but the present invention is not limited to the following embodiments. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

  FIG. 1 is a cross-sectional view showing an embodiment of a resin-sealed light emitting device that can be obtained by the manufacturing method of the present invention. A resin-sealed light-emitting element 10 shown in FIG. 1 includes a light-emitting element 2 formed on a substrate 3 and a light-beam control member 1 made of a thermoplastic resin formed into a shape capable of controlling a light beam emitted from the light-emitting element 2. It has. The light flux controlling member 1 is provided with a recess for accommodating the light emitting element 2, and the surface of the recess corresponds to the light incident surface. In the resin-sealed light emitting element 10 of FIG. 1, the light emitting surface of the light emitting element 2 and the light incident surface of the light flux controlling member 1 are joined with a cured product 4 of a curable resin.

  The resin-sealed light emitting device 10 shown in FIG. 1 can be manufactured by the steps described below. First, a light flux controlling member 1 formed by molding a thermoplastic resin into a predetermined shape is prepared. Here, the predetermined shape means a shape capable of controlling the light beam emitted from the light emitting element. The light flux controlling member in the present invention is a member for giving desired directivity to a light flux emitted from a light emitting element such as an LED, and specifically, a transparent resin molded into a shape having a lens function. Member.

  The light flux controlling member 1 is not limited to the shape shown in FIG. 2A to 2D are cross-sectional views showing examples of light flux controlling members applicable to the present invention. 2 (b) has the same shape as the light flux control member 1 in FIG. 1, but FIGS. 2 (a), (c) and (d) have the same shape as the light flux control member 1 in FIG. Is different.

  Each of the light beam control members shown in FIGS. 2A to 2D has a light incident surface 1b on which a light beam emitted from the light emitting element is incident, and a light emission surface 1a on which the incident light beam is controlled and emitted. The light exit surface 1a and the light entrance surface 1b are desired directivities to be described later with respect to a light beam that is incident from the light incident surface 1b, passes through the inside of the light beam control member 1, and exits from the light output surface 1a. It is formed into a shape that gives

  For example, in the light flux controlling member 1 shown in FIG. 2A, the light incident surface 1b is formed into a smooth plane, and the light exit surface 1a is formed into a smooth curved surface having an inwardly inclined surface 1d near the center. When a light beam traveling in the direction of the light exit surface 1a is incident on the light incident surface 1b of the light flux controlling member having such a shape, the interior of the light flux controlling member 1 is moved as long as the inclination angle of the inclined surface 1d is appropriately set. The light beam that has passed through and reached the inclined surface 1d undergoes total reflection and diffuses to the surroundings. For this reason, since the intensity of the light beam emitted from the light exit surface 1a through the center of the light beam control member 1 is relatively lowered, a large number of light-emitting elements constituting a planar light source device such as a backlight can be used. Even when a plurality of light emitting elements are used in an array, uneven luminance in a plane caused by an increase in luminance directly above the light emitting elements can be suppressed. In the present invention, that the plane is smooth means that the arithmetic average roughness Ra defined by JIS B0601 (1994) is 0.1 μm or less.

  As the light flux controlling member 1, the directivity is controlled using the reflecting or refracting action of the member surface as described above, and the material itself constituting the member itself has a predetermined refractive index distribution, A member such as a so-called GRIN (GRreaded Index) lens that imparts directivity by utilizing refraction of light rays can also be used as a light flux controlling member.

  The light incident surface 1b of the light flux controlling member 1 may be a flat surface as shown in FIG. 2A, but it is preferable to provide a concave portion for accommodating the light emitting element. FIG. 2B is an example of a light flux controlling member provided with such a recess. The light flux controlling member 1 shown in FIG. 2B is provided with a concave portion for accommodating the light emitting element on the light incident surface 1b, and at least a part of the concave portion is light into which the radiant light flux from the light emitting element is incident. It acts as the incident surface 1b. At this time, if the light incident surface 1b is a rough surface, the light beam incident on the light beam control member 1 is scattered by the light incident surface 1b, and it is inevitable that the incident light amount is lost and the directivity of the emitted light beam is reduced. . Therefore, the surface of the recess is preferably smooth, and it is more preferable that the recess has a curved surface.

  When the concave portion of the light incident surface 1b has a curved surface and the surface of the concave portion is smooth, the concave portion has a spherical shape and is combined with a light emitting element having characteristics close to a point light source or a minute surface light source such as an LED. If the light emitting point is positioned at the center of curvature of the spherical shape, the incident angle of the incident light beam on the light incident surface 1b can be made substantially vertical, so that the loss due to reflection can be remarkably reduced. Even if it is not a perfect spherical surface, it is possible to reduce reflection loss by making the surface shape so that the incident angle to the light incident surface 1b is as vertical as possible.

  FIG. 2C shows an example of a light beam control member in which the light exit surface 1a is formed into a bullet shape and the light incident surface 1b is formed into a spherical shape. FIG. 2D shows the light exit surface 1a having a fly-eye lens shape and light. This is an example of a light flux controlling member in which the incident surface 1b is formed into a spherical shape.

  The shapes of the light exit surface 1a and the light entrance surface 1b should be designed in consideration of the radiation characteristics of the light emitting elements used in combination.

  The light flux controlling member 1 is made of a thermoplastic resin. The thermoplastic resin constituting the light flux controlling member 1 has a sufficiently high light transmittance (for example, light transmittance of 95 to 100%) with respect to at least a light beam having a wavelength used as a light source among light emission wavelengths of the light emitting element. Moreover, it is preferable that the moldability is good and the directivity control accuracy by the surface shape or the like is excellent. As thermoplastic resins satisfying such conditions, polyethylene resins, polycarbonate resins, styrene resins, acrylic resins, alicyclic olefin resins, or copolymer resins of alicyclic olefins and chain olefins have been conventionally used as optical materials. Various thermoplastic resins that are used can be used, and among them, alicyclic olefin resins and copolymer resins of alicyclic olefins and chain olefins are particularly suitable. Specific examples of these resins include ZEONEX (registered trademark) manufactured by Nippon Zeon Co., Ltd., ARTON (registered trademark) manufactured by JSR Corporation, APEL (registered trademark) manufactured by Mitsui Chemicals, Inc., and the like.

  These alicyclic olefin resins and copolymer resins of alicyclic olefins and chain olefins not only have high optical transparency, but also have an alicyclic structure, so that they have an environment resistance such as light resistance and moisture resistance. If it is used as the light flux controlling member 1 with excellent performance, it becomes possible to realize a resin-sealed light emitting device with excellent environmental resistance. In addition, since these resins have the feature of particularly high heat resistance among the environmental resistance performances, they are difficult to cause deterioration such as deformation and coloring due to heat generation of the light emitting element, and are combined with LEDs having a long life. Thus, it is possible to realize a resin-sealed light emitting element having a long life as a whole.

  The effect of the present invention that can realize a resin-sealed light emitting device having excellent environmental resistance and a long lifetime is that the molecule does not contain polar atoms such as oxygen atoms or unsaturated bonds, and only from saturated hydrocarbons. This is particularly remarkable when a thermoplastic resin is used.

  In addition, the thermoplastic resin used in the present invention may contain additives such as ultraviolet absorbers, plasticizers, and internal mold release agents that are commonly used by those skilled in the art, and to impart a new spectral distribution to the transmitted light beam. It may contain a dye or a fluorescent substance.

  The light flux controlling member 1 formed by molding these thermoplastic resins into a shape capable of controlling the light emitted from the light emitting element is preferably molded by injection molding.

  Conventionally, resin-sealed light-emitting elements have been manufactured by using a mold having a plurality of recesses, holding the light-emitting elements in the recesses, filling the recesses with resin, and curing the resin. However, in such a method, when the light flux controlling member is molded using a high refractive index resin, the moldability is low, and a light flux controlling member having a desired shape cannot be obtained efficiently. On the other hand, injection molding is a molding method that is excellent in both shape controllability and mass productivity of a molded product. In particular, if a thermoplastic resin is molded by injection molding, a molded product with high shape accuracy can be obtained at low cost in a short cycle time. It has the feature that it can be. In the present invention, since the light flux controlling member 1 is molded in advance before joining the light emitting element (injection molding is preferred), the resin-sealed light emitting element provided with the light flux controlling member 1 can be efficiently manufactured.

  A light emitting element including a light flux controlling member can be manufactured by a method of manufacturing a light emitting element sealed in a package having a predetermined shape and fitting the light emitting element into a light flux controlling member formed with a recess into which the shape can be fitted. In such a method, there is a problem that light emission characteristics are impaired due to a gap between the light flux controlling member and the light emitting element generated after fitting, and when trying to forcibly insert a light emitting element of a size that does not cause a gap. The productivity is not only greatly impaired, but the light emitting element may be damaged.

  On the other hand, the manufacturing method of the present invention cures the curable resin with the curable resin interposed between the light emitting surface of the light emitting element and the light incident surface of the light flux controlling member, as will be described in detail later. Therefore, not only the productivity is excellent, but also the problem of breakage of the light emitting element and the light flux controlling member hardly occurs, and a light emitting element excellent in light flux control can be obtained.

  Manufacturing conditions such as cylinder temperature, injection / holding pressure, injection speed, mold temperature, etc. when the light flux controlling member 1 is manufactured by injection molding are the type of injection molding machine, the shape and structure of the mold, the thermoplastic resin It can be set as appropriate by those skilled in the art according to characteristics and the like.

  In the method of the present invention, a light emitting element is also prepared together with the light flux controlling member 1 described above in manufacturing a resin-sealed light emitting element. Hereinafter, the light-emitting element used in the present invention will be described.

  As the light-emitting element used in the present invention, any self-light-emitting element whose directivity can be controlled by a light flux controlling member can be used without any particular limitation. A light-emitting diode (LED) which is a kind of such a light-emitting element is small in size, has high energy efficiency, and has a radiation characteristic close to that of a point light source or a minute surface light source, so that directivity can be easily controlled. It is suitable as.

  As the LED, it is desirable to prepare a so-called bare chip LED which is not enclosed in a package. In an LED packaged in advance with an epoxy resin or the like, the emitted light flux is emitted through the package, so that it is unavoidable that the directivity of the emitted light is affected by the manufacturing variation of the package, and it has a predetermined shape. This is because there is a possibility that the desired directivity may not be finally realized even when combined with the light flux controlling member formed in the above. On the other hand, since the bare chip LED does not have a package that affects the directivity of the emitted light, it can be handled almost as a point light source or a minute surface light source. Therefore, the light-emitting element used in the present invention is suitable.

  The light emitting element 2 is preferably fixed on the substrate 3 in advance before being joined to the light flux controlling member (FIG. 5). The material and shape of the substrate and the method for fixing the light emitting element to the substrate are arbitrary. When the bare chip light emitting element 2 is used, the mounting method includes flip chip mounting in which the wiring surface of the bare chip faces the substrate 3 and face-up mounting in which the wafer surface of the bare chip faces the substrate 3. Which one is selected is arbitrary, but the wafer surface is compared by comparing the refractive index after curing of the curable resin used in the subsequent process with the refractive index of the material constituting each of the wiring surface of the bare chip and the wafer surface. If the refractive index is closer to the refractive index after curing of the curable resin than the refractive index of the wiring surface, flip chip mounting is used, and the refractive index of the wiring surface is more curable than the refractive index of the wafer surface. When the refractive index after curing is close to that of face-up mounting, it is preferable. The smaller the difference between the refractive index after curing of the curable resin and the refractive index of the material constituting the surface in direct contact with the curable resin, the lower the reflection loss at the interface.

Here, the refractive index can be obtained by measuring the emission peak wavelength λ ₀ of the light-emitting element using a multi-spectral goniometer (for example, TPM-2500 manufactured by Tech World) in an environment of 25 ° C.

  In the case where the resin-sealed light emitting element is used for manufacturing a planar light source device such as a display backlight, a plurality of light emitting elements fixed on a single substrate may be used. FIG. 3 is an example of such a configuration, and shows a state in which a plurality of light emitting elements 2 are fixed at predetermined positions on the substrate 3. In this example, each of the plurality of light-emitting elements 2 is a light-emitting element that emits red (R), green (G), or blue (B). By providing directivity, the light source is arranged to be a uniform white surface light source by color mixing.

  When a light emitting element is used in which a plurality of light emitting elements 2 are fixed in a predetermined arrangement on a substrate 3 and a light flux controlling member is bonded to each of the light emitting elements 2, positioning of alignment marks or the like on the substrate 3 in advance is performed. If the means is formed, the fixed positions of the light emitting element 2 and the light flux controlling member 1 can be determined with high accuracy.

  As described above, the light emitting element used in the present invention has been described by taking the LED as an example. However, light emitting elements based on other light emission principles such as an organic EL (electroluminescence) element and a semiconductor laser can be used as well. Further, even a light emitting element having a radiation characteristic close to that of a surface light source can be used as the light emitting element in the present invention if the shape of the light flux controlling member can be designed in accordance with the radiation characteristic of the light emitting element. It is.

  After preparing the light flux controlling member and the light emitting element, the curable resin is cured in a state where the curable resin is interposed between the light emitting surface of the light emitting element and the light incident surface of the light flux controlling member. And the light flux controlling member.

  Examples of the curable resin include a thermosetting resin, a photocurable resin (such as an ultraviolet curable resin), a moisture curable resin, and a two-component mixed curable resin. The curable resin may contain a curing agent, a crosslinking agent, a curing accelerator, and a photosensitizer, and does not contain such a component, and is itself cured by heating or light irradiation. There may be.

  As the curable resin, a monomer composition of a thermosetting resin is preferable. Here, the monomer composition of the thermosetting resin is a thermosetting resin monomer that is added with additives such as a curing agent or an ultraviolet absorber as necessary, and has a desired property by heating. It refers to a composition that has been prepared so that a product can be obtained.

  As the thermosetting resin used in the present invention, the refractive index after curing is higher than the refractive index of the thermoplastic resin constituting the light flux controlling member and the refractive index of the material constituting the light emitting surface of the light emitting element. Is preferably selected and used.

  When a light beam control member made of a thermoplastic resin is directly bonded to the light emitting surface of the light emitting element, the refractive indexes of the two are considerably different, resulting in light loss due to Fresnel reflection and a reduction in the total reflection angle at the interface. As a result, the ratio of the total reflected light beam increases, and the amount of light finally available through the light beam control member decreases. Therefore, if a thermosetting resin layer having an intermediate refractive index (after curing) is disposed between the light flux controlling member and the light emitting surface of the light emitting element, only the effect of reducing the Fresnel reflectivity at the interface is obtained. In addition, since the ratio of the total reflected light beam is also reduced by increasing the total reflection angle, the amount of light that can be used through the light beam control member can be increased. In the present invention, the comparison of the refractive index levels is performed based on the refractive index at the wavelength that is the center of the light beam control.

  Specific examples of the thermosetting resin include an epoxy resin, a urethane resin, a silicone resin, an episulfide resin, a thiourethane resin, and the like. Generally, the refractive index of the material constituting the light emitting surface of the light emitting element is 2. Since it has a high value of 5 to 3.5, it is preferable to use a thermoplastic resin having a sulfur atom, and it is particularly preferable to use an episulfide resin or a thiourethane resin in terms of obtaining a higher refractive index.

  Here, the episulfide resin is a resin obtained by polymerizing and curing a sulfur-containing compound having an episulfide structure, and a specific example of such a resin is disclosed in JP-A-10-298287. The thiourethane resin is also known as a thiocarbamic acid S-alkyl ester resin, and a specific example of such a resin is as disclosed in JP-A-60-199016.

  In order to cure and bond the curable resin with the curable resin interposed between the light emitting surface of the light emitting element and the light incident surface of the light flux controlling member, at least one of the light flux controlling member and the light emitting element is used. After a certain amount of uncured curable resin (or curable resin that has not been cured) is attached, both may be fixed or stuck together. In this case, it is preferable to fix or stick to a predetermined position while applying pressure or vacuum deaeration. When using a monomer composition of a thermosetting resin, it is important to use an appropriate amount of the monomer composition so as not to generate bubbles or spaces on the sticking surface (bonding surface).

  When the light incident surface of the light flux controlling member and the light emitting surface of the light emitting element are fixed or adhered, the monomer composition is heated to a predetermined curing temperature (for example, 80 to 100 ° C.) while holding both at a predetermined relative position. The product is cured to manufacture a resin-sealed light-emitting element in which the light flux controlling member and the light-emitting element are bonded to a predetermined position. At this time, the temperature Tc (° C.) at which the curable resin is cured and joined (the thermosetting temperature of the thermosetting resin when a thermosetting resin is used) is the thermal deformation of the thermoplastic resin constituting the light flux controlling member. It is desirable to set it at least 20 ° C. lower than the temperature Td (° C.). That is, it is desirable to satisfy the relationship of Tc ≦ Td−20 (that is, Td−Tc ≧ 20).

  If Tc is set lower than Td and the temperature difference between the two is 20 ° C. or more, the light flux controlling member is prevented from being deformed by heating during curing, and the light flux controlling member is maintained while maintaining a properly designed surface shape. And the light emitting element can be bonded (consolidated) at a predetermined relative position. On the other hand, when Tc is higher than Td, or when Tc is lower than Td and the difference between the two is less than 20 ° C., the light flux controlling member undergoes thermal deformation during heat curing of the monomer composition, and the surface There may be a disadvantage that the scheduled light flux control performance cannot be obtained due to a change in shape or the like. The value of Td−Tc is more preferably 30 or more, and still more preferably 40 or more.

  The temperature Tc (° C.) at which the curable resin is cured and bonded means the highest temperature at which the curable resin is cured. When curing the monomer composition of the thermosetting resin, it is possible to use a stepwise temperature rising program of two or more steps in order to perform the gelation and complete curing of the resin at different temperatures. In this case, the maximum temperature in the temperature raising program is the curing temperature Tc.

  In the present invention, the heat distortion temperature Td is a temperature defined by the method described in JIS K7191-1,2.

  In order to join (consolidate) the light flux controlling member and the light emitting element at a predetermined relative position, it is desirable to provide positioning means such as an optical alignment mark or a mechanical fitting structure on both. When the light emitting element 2 is fixed on the substrate 3 in advance as in the example 3, positioning means may be provided on the substrate 3. In general, the monomer composition of a thermosetting resin temporarily decreases in viscosity during the heat curing process, and thus the monomer composition flows at this time, and the relative position between the light flux controlling member and the light emitting element is shifted. In order not to occur, it is preferable to carry out heat curing while maintaining the relative position of both by an appropriate fixing means.

  Through the above steps, a resin-sealed light emitting device having a structure like the resin-sealed light emitting device 10 of FIG. 1 is manufactured.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not limited to a following example.

  The present example is a manufacturing example of a resin-sealed light-emitting element composed of red (R), green (G), and blue (B) LED elements fixed at predetermined positions on a substrate, and the resin-sealed light-emitting element. Is a manufacturing example of a planar light source (planar light source device) that can be used as a backlight for a flat panel display.

  First, a light flux controlling member having the shape shown in FIG. 2B is manufactured by injection molding using ZEONEX-480R manufactured by Nippon Zeon Co., Ltd., which is an optical grade thermoplastic resin. At this time, the shape control accuracy by injection molding can be approximately 10 μm, and the cycle time is approximately 10 to 60 seconds. ZEONEX-480R has a thermal deformation temperature Td of 120 ° C. and a refractive index at 587 nm (D line) of 1.53.

  The light incident surface 1a of the light flux controlling member 1 having the shape shown in FIG. 2B is provided with a recess for accommodating a bare chip LED used as a light emitting element, and the surface thereof is formed into a smooth spherical shape. ing. Further, when combined with the bare chip LED fixed on the substrate, the light emitting point of the LED is formed so as to be positioned at the center of curvature of the spherical shape. The light exit surface 1a of the light beam control member 1 is provided with an inclined surface 1d for preventing light incident from the light incident surface 1b along the central axis of the light beam control member 1 from being totally reflected and not transmitted directly above. In addition, the other surface is formed into a shape that gives a predetermined directivity to the emitted light.

  Next, RGB bare-chip LEDs are fixed on the substrate. GOD-350 (AlInGaP / GaP) manufactured by Showa Denko KK is used for the red LED, GU35R525T (InGaN / sapphire) manufactured by the same company is used for the green LED, and GU35R470T (InGaN / sapphire) manufactured by the same company is used for the blue LED.

  FIG. 3 is a schematic view showing an example of a plurality of light emitting elements 2 fixed on the substrate 3. In the present embodiment, the light emitting elements 2 are bare chip LEDs each emitting light in red, green, or blue. Yes, the white light sources are configured by mixing colors and are distributed at appropriate positions.

  A wiring pattern is formed on the substrate 3 in advance, and an alignment mark for mounting the LED at a predetermined position is formed. Each of the bare chip LEDs is fixed to a predetermined position on the substrate 3 by flip chip mounting so that the luminous flux is emitted from the wafer surface. By flip-chip mounting the bare chip LED on the sapphire wafer, the light emission surface of the LED is formed by sapphire (refractive index 1.76 at 587 nm), so the difference in refractive index from the thermosetting resin is smaller. Thus, the reflection loss is reduced and the extraction efficiency of the radiated light flux is improved.

  Next, a predetermined amount of a thermosetting resin monomer composition is dropped on the light emitting surface of each bare chip LED fixed on the substrate 3, and the light incident surface of the light flux controlling member 1 is opposed to the light emitting surface of the bare chip LED. And stick it in place (FIG. 4). At this time, the light flux controlling member 1 is attached to an appropriate position with reference to the alignment mark provided on the substrate 3 using an automatic mounting machine. The dropping amount of the monomer composition is precisely controlled by using a metering pump or the like so as not to generate a gap between the concave portion of the light flux controlling member 1 and the bare chip LED and to flow out more than necessary outside the sticking surface. To do.

  As the monomer composition of the thermosetting resin, bis (β-epithiopropyl) sulfide, which is an episulfide resin disclosed in Example 11 of JP-A-10-298287, 95 parts by mass, bis (2- Mercaptoethyl) sulfide: A mixture of 5 parts by weight is used. The refractive index of the cured product of the composition is 1.71 at 587 nm.

  The substrate 3 on which the light flux controlling member 1 is adhered at a predetermined position is sent to a hot-air circulating heating furnace set at 100 ° C., held until the monomer composition is completely cured, and gradually cooled to room temperature. . The curing temperature Tc of the monomer composition at this time is 100 ° C.

  Through the above steps, a resin-sealed light-emitting element including the plurality of light-emitting elements 2 fixed on the substrate 3 and the light flux controlling member 1 is manufactured.

  When this resin-sealed light emitting element is combined with a diffusion plate, a planar light source that can be used as a backlight of a liquid crystal display device can be manufactured. FIG. 6 is a schematic cross-sectional view showing an example of a planar light source manufactured in this way. Here, the resin-sealed light-emitting element 11 constituting the planar light source includes a plurality of light-emitting elements 2 that are fixed on the substrate 3 and emit RGB colors, and a cured product of a thermosetting resin on each of the plurality of light-emitting elements 2. 4 and a light flux controlling member 1 made of a thermoplastic resin joined together. The resin-sealed light-emitting element 11 is disposed facing the diffusion plate 5 at a predetermined distance, and the emitted light beams of RGB colors whose directivities are controlled by the light beam control member 1 are mixed in the diffusion plate 5 to be uniform. A planar light source device that emits white light is configured.

  Moreover, if the planar light source device having the above configuration is arranged on the back surface (backlight surface) of a transmissive liquid crystal panel manufactured by a known method, a liquid crystal display device with a backlight can be manufactured.

  The resin-sealed light emitting device of this example is excellent in heat resistance and moisture resistance because the light flux controlling member is composed of an alicyclic olefin resin. In addition, since the light beam control member is molded with high accuracy by injection molding, the directivity control accuracy is high, and the light beam control member and the light emitting element are solidified by a thermosetting resin having an intermediate refractive index of both. The reflection loss at the interface is reduced, the efficiency of extracting the emitted light flux is increased, and high luminance can be obtained with low power consumption. Therefore, the planar light source device using the resin-encapsulated light emitting element of this embodiment as a light source has high durability, has little luminance unevenness and color tone shift, and can be produced at low cost. In addition, a liquid crystal display device in which a planar light source device is disposed on the back surface of a transmissive liquid crystal panel has characteristics that durability is high and luminance unevenness and color tone deviation are small.

  According to the method for manufacturing the resin-sealed light emitting device of this embodiment, the light flux controlling member is formed by injection molding of a thermoplastic resin, so that a light flux controlling member with high shape accuracy can be produced in a short cycle time. A resin-sealed light emitting element having a control member can be manufactured at low cost. Further, the light flux controlling member and the light emitting element are bonded with a thermosetting resin monomer composition, and the light beam control member and the light emitting element are fixed at a predetermined relative position at a curing temperature that is 20 ° C. or more lower than the thermal deformation temperature of the thermoplastic resin. It is possible to manufacture a high-performance resin-encapsulated light-emitting element having excellent property control accuracy. In addition, by incorporating a resin-sealed light emitting element as a light source, a planar light source device and a liquid crystal display device with reduced luminance unevenness and color tone deviation can be manufactured at low cost.

Claims (22)

A light emitting element, and a light flux controlling member made of a thermoplastic resin, shaped into a shape capable of controlling a light flux emitted from the light emitting element,
A method for producing a resin-sealed light emitting element, wherein the curable resin is cured and bonded in a state where a curable resin is interposed between a light emitting surface of the light emitting element and a light incident surface of the light flux controlling member. The temperature Tc (° C.) at which the curable resin is cured and bonded and the heat distortion temperature Td (° C.) of the thermoplastic resin are expressed by the following formula (1):
Tc ≦ Td-20 (1)
The manufacturing method of Claim 1 which satisfy | fills.   The refractive index after hardening of the said curable resin is lower than the refractive index of the material which comprises the light-projection surface of the said light emitting element, and is higher than the refractive index of the said thermoplastic resin. Production method.   The manufacturing method according to claim 1, wherein the curable resin is a thermosetting resin.   The said curable resin is a manufacturing method as described in any one of Claims 1-4 which is an episulfide resin or a thiourethane resin.   The light incident surface of the light flux controlling member is provided with a recess for accommodating the light emitting element, the recess has a curved surface, and the surface of the recess is smooth. The manufacturing method according to one item.   The manufacturing method according to claim 6, wherein the concave portion has a spherical shape, and the light emitting point of the light emitting element is located at the center of curvature of the spherical shape.   The said light emitting element is a several light emitting element arranged on the board | substrate, The manufacturing method as described in any one of Claims 1-7 which joins each of this light emitting element and the said light beam control member.   The manufacturing method according to claim 1, wherein the light emitting element is a light emitting diode.   The resin-sealed light emitting element which can be obtained with the manufacturing method as described in any one of Claims 1-9.   A planar light source comprising: a step of producing a resin-sealed light emitting device by the production method according to claim 1; and a step of arranging the resin-sealed light emitting device in a planar shape using the resin-sealed light emitting device as a light source. Production method. A resin-sealed light-emitting element comprising: a light-emitting element; and a light beam control member made of a thermoplastic resin molded into a shape capable of controlling a light beam emitted from the light-emitting element,
A resin-sealed light-emitting element in which a light emitting surface of the light-emitting element and a light incident surface of the light flux controlling member are bonded with a cured product of a curable resin.   The resin sealing according to claim 12, wherein a refractive index after curing of the curable resin is lower than a refractive index of a material constituting a light emitting surface of the light emitting element and higher than a refractive index of the thermoplastic resin. Light emitting element.   The resin-sealed light emitting element according to claim 12 or 13, wherein the curable resin is a thermosetting resin.   The resin-sealed light-emitting element according to any one of claims 12 to 14, wherein the curable resin is an episulfide resin or a thiourethane resin.   The resin-sealed light emitting element according to any one of claims 12 to 15, wherein the light emitting element is accommodated in a recess provided on a light incident surface of the light flux controlling member.   The resin-sealed light-emitting element according to claim 16, wherein the recess has a curved surface, and the surface of the recess is smooth.   The resin-sealed light emitting device according to claim 16 or 17, wherein the recess has a spherical shape, and a light emitting point of the light emitting device is located at a center of curvature of the spherical shape.   The resin light emitting according to any one of claims 12 to 18, wherein the light emitting elements are a plurality of light emitting elements arranged on a substrate, and each of the light emitting elements is joined to the light flux controlling member. element.   The resin-sealed light emitting device according to any one of claims 12 to 19, wherein the light emitting device is a light emitting diode.   The planar light source formed by arrange | positioning the resin-sealed light emitting element as described in any one of Claims 12-20 in planar shape.   A liquid crystal display device comprising the planar light source according to claim 21 disposed on a backlight surface of a transmissive liquid crystal panel.

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