JP2015228277A - Optical element and led illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element which can be highly-accurately positioned corresponding to the power-up of an LED light source, and an LED illumination device employing the optical element.SOLUTION: In a bottom face OEa of an optical element OE, a positioning part OEd is formed integrally with an incident face OEc. In the view of a cross section along a light axis orthogonal direction, the positioning part OEd is brought into contact with a support part Lc around a light-emitting part Lb of an LED light source L in at least two positions. This allows the positioning of the optical element OE and the LED light source L in the light axis orthogonal direction.

Description

  The present invention relates to an optical element and an LED lighting device that are installed on the back side of a relatively large surface member and perform illumination so that light passes through the surface member.

  In a conventional large-sized liquid crystal display device, light from a number of cold-cathode tubes arranged on the back side of the liquid crystal panel is guided to the back side of the liquid crystal panel via a diffusion plate, a reflector, etc., and is uniformly used as a backlight. By illuminating, the image was clearly visible. On the other hand, in recent years, an LED has been used as a light source of a backlight from the viewpoint of energy saving. Further, from the viewpoint that brightness and darkness can be controlled in accordance with an image displayed on the liquid crystal display device, the LED is easy to use, thereby further reducing the power consumption of the liquid crystal display device.

  Thus, when using an LED as a backlight of a liquid crystal display device, the light distribution of the LED package alone is narrow. Therefore, if such an LED package is placed directly on the back side of the liquid crystal panel, in order to ensure uniform illumination This is not practical because a myriad of LED packages are required. Therefore, an optical element that converts light emitted from the LED package into illumination light with uniform illuminance is required. Patent Documents 1 to 3 disclose an optical element for a backlight for liquid crystal that can convert light from an LED into illumination light with as uniform illuminance as possible.

International Publication No. 2011/062089 Pamphlet JP 2008-532300 A JP 2009-117207 A

  By the way, in recent years, it has been desired to reduce the number of LED packages used per unit in order to reduce the cost of a backlight for a large-sized liquid crystal display device. However, when the number of LED packages is reduced, it is necessary to increase the degree of diffusion of the lens that refracts the emitted light, and the curvature (C = 1 / R) of the optical surface of the lens increases. In this way, as the curvature of the optical surface of the lens increases, a slight change tends to cause deterioration in optical performance. For these reasons, there is a problem that optical performance deterioration (occurrence of luminance unevenness, color unevenness, etc.) due to an attachment error in the direction orthogonal to the optical axis becomes more conspicuous than before.

  In order to solve this problem, in Patent Document 1, since the optical element is fixed to the substrate, the positioning error between the substrate and the LED package is combined with the positioning error between the optical element and the substrate, which is expensive. It is necessary to carefully eliminate assembling errors of each element using a simple positioning mechanism, resulting in high costs.

  In Patent Document 2, as shown in FIG. 6, a fixing member protruding from the bottom surface of the optical member is inserted into a hole formed in the casing of the LED package. However, in such a configuration, a hole must be formed in the LED package, and a large and specially structured LED package is required, resulting in high costs.

  Further, in Patent Document 3, since the leg protruding from the bottom surface of the optical member is fitted to the substrate, in the same manner as in Patent Document 1, in addition to the positioning error between the optical member and the substrate, the substrate and the LED package Therefore, it is necessary to carefully eliminate the assembly error of each element by using an expensive positioning mechanism for mounting the LED package, resulting in high cost.

  The present invention has been made in view of the problems of the prior art, and an optical element capable of easily realizing high-accuracy positioning corresponding to the high power of the LED light source and an LED illumination device using the optical element. The purpose is to provide.

  The optical element according to claim 1 is an optical element that is disposed on a light emission side of an LED light source, and receives light from the LED light source, and the optical element receives light from the LED light source. A light emitting surface that emits light incident from the light incident surface, and a positioning portion that is provided outside the light incident surface in the direction perpendicular to the optical axis. The LED light source includes the light emitting portion and the light emitting portion. The incident surface has a concave shape, and the optical axis orthogonal direction maximum diameter of the incident surface is larger than the optical axis orthogonal direction maximum dimension of the light emitting unit, and the optical axis orthogonal to the support unit. The positioning portion is not more than the maximum dimension in the direction, and the positioning portion is in contact with at least two portions of the support portion when viewed in a cross section in the direction perpendicular to the optical axis.

  The principle of the present invention will be described with reference to FIG. Fig.1 (a) is sectional drawing of the optical element concerning a comparative example, FIG.1 (b) is sectional drawing of the optical element concerning an example of this invention, and has each shown with the LED light source. First, in the comparative example shown in FIG. 1A, the leg portion OEb extends from the bottom surface OEa of the optical element OE and is in contact with the top surface of the substrate ST to which the LED light source L is attached. In such a comparative example, since there is no positioning means for the LED light source L and the optical element OE, for example, after marking the substrate ST, the optical element OE must be positioned with respect to the marking. Take it.

  On the other hand, according to the present invention, as shown in FIG. 1B, the positioning portion OEd formed integrally with the incident surface OEc is formed on the bottom surface OEa of the optical element OE. The positioning portion OEd comes into contact with at least two places when viewed in a cross section in the direction perpendicular to the optical axis with respect to the light emitting portion Lb of the LED light source L and the surrounding support portion Lc (see FIG. 2 described later). As a result, the optical element OE and the LED light source L can be positioned in the direction perpendicular to the optical axis. Note that the positioning portion OEd is preferably in contact with the position of the maximum dimension in the optical axis orthogonal direction at the support portion Lc or in the vicinity thereof.

  The support part is a part that supports the positioning part, and may be a part of the surface of the LED light source, and the shape is determined so that a flat surface or other positioning part can be positioned. Specifically, a package substrate, a heat sink, a sealing material surface, or the like may be used.

  Here, the “maximum dimension in the direction perpendicular to the optical axis” is the diameter with the maximum distance from the center as the radius when the light emitting part or support part of the LED light source is circular, and the length of the diagonal line when it is square or rectangular Is applicable. However, when the position of the light source center is not on or near the intersection of the two diagonal lines, the diameter may be a radius with the farthest distance from the light source center being a square or rectangular outer shape.

  Further, the “maximum diameter of the incident surface of the optical element in the direction perpendicular to the optical axis” is the maximum diameter of the incident surface, so even if some incident surfaces have steps or multiple surfaces, they are connected to the lens bottom surface (connected to the leg OEb). The maximum diameter of the surface in contact with the (surface) may be “the maximum diameter in the direction perpendicular to the optical axis of the incident surface of the optical element”. Further, the light emitting portion is a portion constituted by a semiconductor chip that emits light, a phosphor, and a sealing material.

  Furthermore, “the optical axis orthogonal direction maximum diameter of the incident surface of the optical element is larger than the optical axis orthogonal direction maximum dimension of the light emitting part of the LED light source and is equal to or less than the optical axis orthogonal direction maximum dimension of the support part” In FIG. 2 in which the LED light source L is viewed in the optical axis direction, when the light emitting portion Lb is circular or elliptical and the support portion Lc is rectangular, the maximum diameter (entrance side diameter) of the incident surface OEc is φ1, When the diameter of the light emitting portion Lb is φ2 and the diagonal length of the support portion Lc is T, it means that T ≧ φ1> φ2. Thereby, the optical element can be reduced in size by bringing the diameter φ1 of the incident surface OEc closer to the diameter φ2 of the light emitting portion Lb, and the support portion Lc is less likely to exist between the incident surface OEc and the light emitting portion Lb. The light emitted from the light emitting portion Lb is suppressed from being blocked by the support portion Lc on the incident surface OEc, and the light use efficiency can be increased.

  According to a second aspect of the present invention, there is provided the optical element according to the first aspect, wherein the positioning portion is in contact with the support portion by a point or a line.

  When considering reducing the number of LED chips in the backlight illumination device, in order to ensure the same illuminance as before, it is preferable to increase the power per LED chip. As the power is increased, the amount of heat generated increases accordingly, so it is desirable to consider the influence of heat on the optical element due to contact. Here, although the problem of heat generation can be dealt with by forming an optical element using a resin having excellent heat resistance such as polycarbonate, there are cases where it is desired to use a less expensive resin in order to reduce the cost. In such a case, according to the present invention, since the positioning portion contacts the support portion with a point or a line, even if the support portion is at a high temperature, heat conduction to the positioning portion is then suppressed. Therefore, even if a resin material having low heat resistance is used, deformation or the like that causes deterioration of optical characteristics can be suppressed. Moreover, it is conceivable that the influence of heat is greater than in the past by placing the positioning part near the light source, but the positioning part is in contact with the support part by a point or a line as in the present invention. Even if the support portion becomes high temperature, it has a remarkable effect that heat conduction to the positioning portion can be suppressed.

  According to a third aspect of the present invention, in the optical element according to the second aspect, the total contact length of the positioning portion is 6 mm or less.

  Considering heat conduction, the smaller the total contact length of the positioning portion, the better. However, on the other hand, there is a problem that the positioning cannot be performed sufficiently. Therefore, when the total contact length of the positioning portion is 6 mm or less, a sufficient total positioning contact length can be secured while further suppressing heat conduction to the positioning portion.

  The size of a general direct type LED package is about 2.8 mm to 3.5 mm on one side, and its periphery is 2.8 mm × 4 = 11.2 mm and 3.5 mm × 4 = 14 mm. In order to reduce the transfer of heat, the contact length is preferably suppressed to ½ or less of the circumference, and more preferably ¼ or less. By doing so, only heat is transmitted locally, and the influence on the optical surface can be reduced.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the positioning portion protrudes in a ring shape from the bottom surface of the optical element.

  When the support part of the LED light source has a square shape, the positioning part can be supported at four points regardless of the rotational phase.

  The optical element according to claim 5 is the invention according to any one of claims 1 to 3, wherein the positioning portion is a plurality of protrusions protruding at equal intervals in the circumferential direction from the bottom surface of the optical element. The protrusion contacts the corner of the support portion of the LED light source or the vicinity thereof.

  By determining the position of the protrusion according to the shape of the LED light source, the protrusion can be brought into contact with all corners or in the vicinity thereof even when the support portion is polygonal.

  According to a sixth aspect of the present invention, in the invention of the fifth aspect, the projection is in contact with two different directions orthogonal to the optical axis across the corner of the LED light source.

  Thereby, the optical element can be positioned from two directions orthogonal to the optical axis across the corner of the LED light source.

  The optical element according to claim 7 is the invention according to any one of claims 1 to 3, wherein a plurality of pyramid-shaped parts are formed on the bottom surface of the optical element, and the positioning part is the pyramid. It consists of a part of shape part.

  The pyramid-shaped portion can suppress color unevenness by allowing the light emitted from the optical element to pass through the pyramid-shaped portion, and can position the optical element with respect to the LED light source with high accuracy.

  An optical element according to an eighth aspect of the present invention is the optical element according to any one of the first to seventh aspects, wherein the light emitting portion and the incident portion are brought into contact with the bottom surface in the optical axis direction with respect to the support portion. An adjustment unit that adjusts the distance from the surface is provided.

  According to the present invention, the distance between the light emitting unit and the incident surface can be adjusted only by placing the optical element on the LED light source.

  The optical element according to claim 9 is the invention according to any one of claims 1 to 8, wherein a plurality of legs extending toward the substrate of the LED light source are provided on the bottom surface of the optical element. It is characterized by being.

  Thereby, a space communicating with the outside can be provided between the optical element and the substrate, and the heat generated from the LED light source can be effectively released. In addition, it is preferable to adhere | attach a leg part with respect to the board | substrate of a LED light source. As a result, the bonding area can be increased as compared with the case where the positioning portion and the LED light source are bonded, so that higher bonding strength can be secured, and the LED light emitting surface is bonded because the bonding is performed at a position away from the light emitting portion of the LED light source It is not contaminated by the agent, and furthermore, since the heat transmitted from the LED light source to the optical element via the adhesive is small, the possibility of causing thermal deformation of the optical element can be reduced.

  An optical element according to a tenth aspect is characterized in that in the invention according to any one of the first to ninth aspects, the optical element is formed of a polycarbonate resin.

  Thereby, even when the amount of heat generation increases with the increase in power of the LED light source, there is little risk of causing deformation or the like due to an ancestor.

  An LED illumination device according to an eleventh aspect includes the optical element according to any one of the first to tenth aspects and an LED light source.

  The LED (Light Emitting Diode) illumination device according to the present invention includes an LED light source and an optical element.

  Various LED light sources can be used, but it is preferable to use a white LED having a flat light emission surface and emitting white light.

  As the white LED, a combination of a blue LED chip and a phosphor such as a YAG phosphor that emits yellow light by blue light emitted from the blue LED chip is preferably used. As white LED, what was described, for example in Unexamined-Japanese-Patent No. 2008-231218 can be used, However, It is not restricted to this.

  In the present embodiment, the white LED package specifically includes an LED chip and a phosphor layer formed on the LED chip so as to cover the LED chip. The LED chip emits light having a first predetermined wavelength (light of a first color), and emits blue light. However, the wavelength of the LED chip of the present invention and the wavelength of the emitted light of the phosphor are not limited, as long as the light mixed with the emitted light from the LED chip and the emitted light from the phosphor becomes white light. Anything can be used.

  In addition, as such an LED chip, a well-known blue LED chip can be used. As the blue LED chip, any existing one including InxGa1-xN can be used. The emission peak wavelength of the blue LED chip is preferably 440 to 480 nm. In addition, as a form of the LED chip, the LED chip is mounted on the substrate and directly radiated upward or sideward, or the blue LED chip is mounted on a transparent substrate such as a sapphire substrate, and bumps are formed on the surface thereof. Any form of LED chip, such as a so-called flip chip connection type, in which it is formed and turned over and connected to an electrode on a substrate, can be applied.

  The phosphor layer includes a phosphor that converts light having a first predetermined wavelength emitted from the LED chip into light having a second predetermined wavelength (light of a second color). In an embodiment described later, blue light emitted from the LED chip is converted into yellow light.

  The phosphor used for such a phosphor layer uses an oxide or a compound that easily becomes an oxide at a high temperature as a raw material of Y, Gd, Ce, Sm, Al, La and Ga, and converts them into a stoichiometric amount. The raw material is obtained by thoroughly mixing in a theoretical ratio. Alternatively, a coprecipitated oxide obtained by calcining a solution obtained by coprecipitation of oxalic acid with a solution obtained by dissolving a rare earth element of Y, Gd, Ce, and Sm in an acid at a stoichiometric ratio, and aluminum oxide and gallium oxide. Mix to obtain a mixed raw material. An appropriate amount of fluoride such as ammonium fluoride is mixed with this as a flux and pressed to obtain a molded body. The compact can be packed in a crucible and fired in air at a temperature range of 1350 to 1450 ° C. for 2 to 5 hours to obtain a sintered body having the phosphor emission characteristics.

  The LED light source is preferably a high-power LED light source. Here, the high-power LED light source can be constituted by an LED having an output of 0.5 watts or more.

  The optical element is preferably made of a heat resistant plastic. As the plastic constituting the optical element, for example, PMMA or polycarbonate can be used for manufacturing by injection molding, and the manufacturing cost can be greatly reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the optical element which can implement | achieve highly accurate positioning corresponding to the high power of an LED light source, and an LED lighting apparatus using the same can be provided.

FIG. 1A is a cross-sectional view of an optical element according to a comparative example, and FIG. 1B is a cross-sectional view of the optical element according to an example of the present invention. It is the figure which looked at the LED light source in the optical axis direction. Fig.3 (a) is an exploded view of the LED illuminating device concerning this Embodiment, FIG.3 (b) is an assembly drawing. 3 is an enlarged perspective view showing a light bar 20. FIG. It is sectional drawing of the LED lighting apparatus cut | disconnected along the optical axis of an optical element. It is a figure which shows the optical element concerning 1st Embodiment. It is a perspective view shown in the state which assembled the optical element and the LED light source. It is a figure which shows the optical element concerning 2nd Embodiment. It is a figure which shows the optical element concerning 3rd Embodiment. It is a perspective view shown in the state which assembled the optical element and the LED light source. It is a figure which shows the optical element concerning 4th Embodiment. It is a perspective view shown in the state which assembled the optical element and the LED light source. It is a figure which shows the optical element concerning 5th Embodiment. It is a figure which shows the modification of protrusion 23s which contacts the heat sink 22b of LED light source 22. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Fig.3 (a) is an exploded view of the LED illuminating device concerning this Embodiment, FIG.3 (b) is an assembly drawing. In FIG. 1, the LED lighting device includes a metal rectangular shallow dish-shaped casing 10, three (or four) light bars 20, and a reflective sheet that is bent into a rectangular shallow dish like the casing 10. 30 and a rectangular diffusion plate (a laminated diffusion sheet or prism sheet) 40.

  The casing 10 has four side surfaces 11 inclined upward. A light bar 20 is attached to the bottom surface 12 of the housing 10 in parallel. The reflection sheet 30 is provided with holes 32 on the bottom surface 31 corresponding to the optical elements provided on the light bar 20.

  FIG. 4 is an enlarged perspective view showing the light bar 20. FIG. 5 is a cross-sectional view of the LED lighting device cut along the optical axis of the optical element. 4 and 5, the light bar 20 is arranged on an elongated substrate 21, a plurality (seven in this case) of LED light sources 22 provided on the substrate 21 at equal intervals, and the LED light sources 22. And an optical element 23. In FIG. 5, an LED light source 22 is a light emitting unit 22a formed by laminating an LED chip that emits blue light (La in FIG. 2) and a yellow phosphor (Lb in FIG. 2) provided on the light emitting side. And a heat sink 22b as a support portion which is provided around and has a square plate shape as a whole. In the assembled state as shown in the figure, the light bar 20 is sandwiched between the bottom surface 12 and the bottom surface 31, and the optical element 23 is exposed upward from the hole 32 of the reflection sheet 30.

(First embodiment)
FIG. 6 is a diagram showing an optical element according to the first embodiment that can be used in the above-described embodiment. FIG. 7 is a perspective view showing the assembled optical element and LED light source. The optical element 23 is integrally formed by injection molding using PMMA or polycarbonate as plastic. Further, the optical element 23 is disposed on the light emission side of the LED light source 22, and has an incident surface 23 a which is a concave aspheric surface on which light emitted from the LED light source 22 is incident, and light incident from the incident surface 23 a is externally transmitted. And a bottom surface 23c facing the substrate 21, and an outer peripheral surface 23d which is a cylindrical surface or a conical surface provided on the outer periphery of the output surface 23b. The outer peripheral surface 23d is a portion where a gate is provided when the optical element 23 is injection molded. Similar to the example shown in FIG. 2, the maximum diameter of the incident surface 23 a is larger than the maximum diameter of the light emitting portion 22 a of the LED light source 22 and smaller than the diagonal length of the heat sink 22 b.

  The exit surface 23b is concave in the vicinity of the optical axis and convex in the periphery, but may be convex as a whole. The bottom surface 23c can be a rough surface having a diffusion action by increasing the roughness of the corresponding transfer surface of the mold. The outer peripheral surface 23d can also be a roughened surface having a diffusion action by increasing the roughness of the corresponding transfer surface of the mold.

  As shown in FIGS. 6B and 6C, the optical element 23 has an annular portion 23e as a positioning portion that protrudes from the bottom surface 23c in the annular shape around the incident surface 23a. The annular portion 23e as the positioning portion has a length in the optical axis direction that covers at least a part of the heat sink 22b, and preferably in the optical axis direction that covers a range within 1/2 of the upper surface side of the thickness of the heat sink 22b. Is set to the length of The annular zone 23e includes a circular bottom surface 23f parallel to the bottom surface 23c, an inner peripheral tapered surface 23g extending inward with respect to the circular bottom surface 23f, and an outer peripheral tapered surface 23h extending outward with respect to the circular bottom surface 23f. Have The inner circumferential tapered surface 23g is in point contact with the corner of the heat sink 22b of the LED light source 22 indicated by a dotted line in FIG. Thereby, the optical element 23 can be accurately attached to the LED light source 22 while suppressing heat conduction from the LED light source 22.

  Around the annular portion 23e, three leg portions 23i are formed at equal intervals in the circumferential direction so as to extend from the bottom surface 23c. After bringing the inner peripheral tapered surface 23g into contact with the corner of the heat sink 22b of the LED light source 22, the leg 23i is brought into contact with the surface of the substrate 21 and bonded thereto. At this time, it is desirable to use an ultraviolet curable resin containing carbon black having optical absorption characteristics in the visible light region. However, both the annular zone 23e and the leg 23i may be bonded, or only the annular zone 23e and the LED light source 22 may be bonded. .

  According to the present embodiment, in FIG. 5, the light emitted from the light emitting portion 22a of the LED light source 22 enters from the incident surface 23a of the optical element 23 and diffuses and exits from the output surface 23b. Thereby, since the light beam in which the luminance unevenness and the color unevenness due to the mounting error are suppressed is incident on the diffusion plate 40, the backlight illumination with uniform illuminance can be realized.

(Second Embodiment)
FIG. 8 is a diagram illustrating an optical element according to the second embodiment. This Embodiment can be used for the LED lighting apparatus of FIGS.

  In this embodiment, the optical element 23A shown in FIG. 8 has four protrusions 23j protruding from the bottom surface 23c at equal intervals in the circumferential direction around the incident surface 23a, instead of the ring-shaped protrusions. The inner peripheral side surface 23k of the protrusion 23j is an inclined slope, and the inner peripheral side surface 23k is in point contact with the corner of the heat sink 22b of the LED light source 22 indicated by a dotted line in FIG. Other configurations are the same as those of the above-described embodiment.

(Third embodiment)
FIG. 9 illustrates an optical element according to the third embodiment. FIG. 10 is a perspective view showing the assembled optical element and LED light source. This embodiment can also be used for the LED illumination devices of FIGS.

  In the optical element 23B shown in FIG. 9, hemispheres 23m having the same diameter are arranged in a line around the incident surface 23a in the embodiment of FIG. As shown in FIG. 10, each hemisphere 23 m constituting the adjusting unit is in point contact with the heat sink 22 b of the LED light source 22 (although there are some that do not contact). Thereby, in addition to the positioning function of the projection 23j in the optical axis orthogonal direction, the optical element 23 and the LED light source 22 can be positioned (distance adjustment) in the optical axis direction. Other configurations are the same as those of the above-described embodiment.

(Fourth embodiment)
FIG. 11 is a diagram illustrating an optical element according to the fourth embodiment. FIG. 12 is a perspective view showing the assembled optical element and LED light source. This embodiment can also be used for the LED illumination devices of FIGS.

  In the optical element 23C shown in FIG. 11, the shape of the protrusion is L-shaped with respect to the embodiment of FIG. More specifically, the protrusion 23n provided on the bottom surface 23c has an L shape when viewed in the optical axis direction, and the tapered surfaces 23o and 23p inclined with respect to the optical axis direction intersecting on the inner peripheral side thereof are 11, line contact is made from two different directions with respect to a ridge line in the vicinity of the corner across the corner of the heat sink 22 b of the LED light source 22 indicated by a dotted line in FIG. 11. As a result, the optical element 23C can be positioned in two directions perpendicular to the optical axis with respect to the heat sink 22b. Other configurations are the same as those of the above-described embodiment.

(Fifth embodiment)
FIG. 13 shows an optical element according to the fifth embodiment. This embodiment can also be used for the LED illumination devices of FIGS.

  In the present embodiment, small pyramid-shaped protrusions 23q are arranged vertically and horizontally on the bottom surface 23c of the optical element 23D. Among them, a pair of large pyramidal protrusions 23r are provided at a portion adjacent to the incident surface 23a so as to sandwich the corner of the heat sink 22b of the LED light source 22.

  In the present embodiment, the tip of the large pyramidal protrusion 23 r is in point contact with the heat sink 22 b of the LED light source 22. Thereby, the optical element 23 and the LED light source 22 can be positioned in the optical axis direction. On the other hand, the pair of large pyramidal protrusions 23r sandwich the ridge line in the vicinity of the corner of the heat sink 22b of the LED light source 22 from the two directions orthogonal to the optical axis, so that the optical axis orthogonality between the optical element 23 and the LED light source 22 is obtained. Directional positioning can be performed. The small pyramidal protrusions 23q have a light diffusing effect, and therefore have a color unevenness suppressing effect. Other configurations are the same as those of the above-described embodiment.

  FIG. 14 is a diagram illustrating a modification of the protrusion 23 s that contacts the heat sink 22 b of the LED light source 22. The protrusion 23s can take various shapes as shown in FIG. However, in the example shown in FIGS. 14E to 14G, the tapered surface of the protrusion 23 s is in line contact with the ridge line of the heat sink 22. The total length of contact is preferably 1 mm or less in order to enhance the heat conduction suppressing effect.

  The present invention is not limited to the embodiments described in the specification, and other embodiments and modifications are apparent to those skilled in the art from the embodiments and ideas described in the present specification. It is. For example, the present invention can be used not only for a backlight of a liquid crystal display but also as an illumination device for signboard illumination.

DESCRIPTION OF SYMBOLS 10 Housing | casing 11 Side surface 12 Bottom surface 20 Light bar 21 Board | substrate 22 LED light source 22a Light emission part 22b Heat sink 23 Optical element 23A Optical element 23B Optical element 23C Optical element 23D Optical element 23a Incident surface 23b Output surface 23c Bottom surface 23d Outer peripheral surface 23e Ring zone part 23f Circular bottom surface 23g Inner peripheral taper surface 23h Outer peripheral taper surface 23i Leg 23j Protrusion 23k Inner peripheral side surface 23m Hemisphere 23n Protrusion 23o, 23p Tapered surface 23q Protrusion 23r Protrusion 23s Protrusion 30 Reflective sheet 31 Bottom surface 32 Hole 40 Diffusion plate

Claims (11)

An optical element disposed on the light emission side of the LED light source and receiving light from the LED light source,
The optical element includes an incident surface on which light from the LED light source is incident, an exit surface that emits light incident from the incident surface, and a positioning portion provided outside the incident surface in the direction perpendicular to the optical axis. And
The LED light source includes the light emitting unit and a support unit around the light emitting unit,
The incident surface is concave, and the optical axis orthogonal direction maximum diameter of the incident surface is larger than the optical axis orthogonal direction maximum dimension of the light emitting unit and is equal to or less than the optical axis orthogonal direction maximum dimension of the support unit,
The optical element is characterized in that the positioning portion is in contact with at least two portions of the support portion when viewed in a cross section perpendicular to the optical axis.   The optical element according to claim 1, wherein the positioning portion contacts the support portion with a point or a line.   The optical element according to claim 2, wherein a total contact length of the positioning portion is 6 mm or less.   The optical element according to any one of claims 1 to 3, wherein the positioning portion protrudes in a ring shape from the bottom surface of the optical element.   2. The positioning portion is a plurality of protrusions protruding at equal intervals in the circumferential direction from the bottom surface of the optical element, and each protrusion contacts a corner of the support portion of the LED light source or the vicinity thereof. The optical element in any one of -3.   6. The optical element according to claim 5, wherein the protrusion is in contact with two different directions orthogonal to the optical axis across the corner of the LED light source.   The optical element according to claim 1, wherein a plurality of pyramid-shaped portions are formed on a bottom surface of the optical element, and the positioning portion is formed of a part of the pyramid-shaped portion. element.   The bottom surface is provided with an adjusting portion that adjusts a distance between the light emitting portion and the incident surface by contacting the support portion in the optical axis direction. An optical element according to any one of the above.   The optical element according to claim 1, wherein a plurality of legs extending toward a substrate of the LED light source are provided on a bottom surface of the optical element.   The optical element according to claim 1, wherein the optical element is made of a polycarbonate resin.   An LED illumination device comprising the optical element according to claim 1 and an LED light source.

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