JP2010238686A - Led module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED module that improves the utilization efficiency of the light radiated from an LED light source and uniformizes the emitted light intensity distribution. <P>SOLUTION: In the LED module, the LED light source 2 is inserted inside an optical element 1 filled with a refractive material 1A. The optical element 1 includes an emission surface (front surface) 3, in front thereof in the direction of optical axis J. A side surface 4 on the outside of the optical element 1 in the width direction (radial direction) extends in ring around the optical axis J. The side surface 4 of the optical element 1 is positioned behind the emission surface 3 in the emission direction of light beam. The side surface 4 reflects a light beam S2, which is totally reflected on the emission surface 3 inward in the width direction and generates a light beam S3. A wall surface (rear surface) 5 reflects the beam frontward, in the direction of optical axis, to generate parallel light beam S4 for emission forward in the direction of optical axis, from the emission surface 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an LED module, and includes, for example, a foot lamp, an indicator lamp, a spotlight, a wall washer, an architectural lamp, a stand, an interior lamp, a signal lamp, a line-of-sight guide lamp, an ultra-small projector, an LED (Light- The present invention relates to a backlight, an LED light source device that needs to supply light having a uniform intensity distribution and high directivity, and an LED module used in a device incorporating these.

  In general, in an LED module, there is an LED module in which a bullet-type lens is provided in front of an LED light source in order to control light rays emitted from the LED light source in parallel and emit them forward in the optical axis direction (Patent Document 1 No. 61-147487). The optical axis is the direction from the center of the light emitting surface of the LED light source toward the center front of the optical element, the front in the optical axis direction is the direction of light emission parallel to the optical axis, and the rear in the optical axis direction is light. It is parallel to the axis and opposite to the light exit direction.

  In Patent Document 1, as shown in FIG. 11, in order to collimate light rays emitted from the LED light source 101, a bullet-type lens 102 is provided in front of the optical axis direction, and parallel rays are extracted from the bullet-type lens 102. ing. In FIG. 11, reference numeral 103 denotes a lead frame.

  However, the utilization efficiency of the light beam emitted from the LED light source 101 is poor, and there is a drawback that the LED module becomes large forward in the optical axis direction in order to effectively use the light beam. In addition, since the light emitted from the LED light source 101 at a large angle cannot be made parallel, there is a drawback that the diameter of the emitted light becomes small.

  Therefore, in order to solve the above disadvantages, as shown in FIG. 12, a convex lens portion 203 is provided at the center of the emission surface 204 provided in the optical axis direction of the LED light source 201, and a reflection surface 202 is provided at the periphery thereof to emit light. There is a technique for extracting parallel light rays from the surface 204 (see Patent Document 2 (Japanese Patent Laid-Open No. 1-130578)).

  In this technique, among the light beams emitted from the LED light source 201, a light beam having a small emission angle is collected on the convex lens unit 203 provided at the center of the exit surface 204 and is extracted forward in the optical axis direction as parallel light. On the other hand, since the light beam emitted from the LED light source 201 at a large angle satisfies the total reflection condition on the exit surface 204, the reflection surface 202 provided around the convex lens portion 203 causes the light axis direction rearward and the width direction outer side. It can be bent. Here, the outer side in the width direction is a direction perpendicular to the optical axis and away from the optical axis, and the inner side in the width direction is a direction perpendicular to the optical axis and approaching the optical axis. The bent light beam is reflected from the LED light source 201 by the reflecting surface 206 protruding in a bowl shape in the optical axis direction, and is extracted from the exit surface 204 as a parallel light beam forward in the optical axis direction. In FIG. 12, 207 is an LED light source arrangement surface, and 205 is a wiring to the LED light source 101.

  By the way, in the technique shown in this patent document 2, in order to utilize the light ray radiated | emitted from the LED light source 101 effectively, there exists a fault to which the width direction dimension of an LED module becomes large. In addition, since there is a region on the exit surface 204 where no light is emitted, there is a disadvantage that the intensity distribution of the light becomes non-uniform.

  Therefore, in order to solve the drawbacks of the technique of the above-mentioned Patent Document 2, as shown in FIG. 13, a technique for extracting light emitted from the LED light source 301 as parallel light from the three regions 304A, 304B, and 304C of the exit surface 304. (Patent Document 3 (Japanese Patent Laid-Open No. 2001-237463)).

  In the technique of Patent Document 3, a light beam having a small emission angle from the LED light source 301 is extracted from the region 304A forward in the optical axis direction as a parallel light beam by the convex lens portion 303 of the emission surface 304 provided in the optical axis direction. On the other hand, the light beam emitted from the LED light source 301 at a large angle is reflected by the reflecting surface 306 protruding in a bowl shape from the LED light source 301 in the optical axis direction, and is extracted forward from the region 304B of the emission surface 304 in the optical axis direction.

  On the other hand, the light beam emitted at an angle between the light beams extracted from the regions 304A and 304B of the emission surface 304 satisfies the total reflection condition on the emission surface 302, and is bent backward in the optical axis direction and outward in the width direction on the emission surface 302. Thereafter, the light is totally reflected by the reflecting surface 306 protruding like a bowl in the optical axis direction from the LED light source 301 and is emitted from the region 304C. By making the reflection surface 306 into such a bowl shape, the light emitted from the LED light source 301 can be converted into a parallel light and extracted forward in the optical axis direction.

  By the way, in the technique disclosed in Patent Document 3, the light beams emitted from the areas 304A and 304C of the exit surface 304 shown in FIG. 13 have a large light flux because of the large number of light beams, and are extracted as parallel and uniform light beams. .

  However, since the light beam extracted from the region 304B of the exit surface 304 has a large radiation angle from the LED light source 301, the light beam density is low and the intensity is low. Therefore, the light beam extracted from the exit surface 304 shown in FIG. 13 has a problem that an intensity distribution is non-uniform, resulting in a donut-shaped intensity distribution.

JP-A 61-147487 Japanese Patent Laid-Open No. 1-130578 Japanese Patent Laid-Open No. 2001-237463

  Accordingly, an object of the present invention is to provide an LED module capable of improving the utilization efficiency of outgoing light emitted from an LED light source and making the outgoing light intensity distribution uniform.

In order to solve the above problems, an LED module of the present invention includes an LED light source,
An optical element attached to the LED light source and made of a refractive material,
The optical element is
A front surface that is positioned in front of the LED light source in the light emitting direction of the light beam and transmits or totally reflects light emitted from the LED light source;
A side surface for reflecting the light beam totally reflected on the front surface;
And a rear surface for reflecting the light beam reflected by the side surface toward the front surface.

  According to the LED module of the present invention, the light beam emitted from the LED light source forward at a small angle in the optical axis direction is bent at the front surface of the optical element, and is extracted as a parallel light beam forward in the optical axis direction. On the other hand, a light beam emitted from the LED light source at a large angle with respect to the optical axis is totally reflected by the front surface of the optical element, and is bent backward in the optical axis direction and outward in the radial direction (width direction). Thereafter, the light beam is reflected radially inward by the side surface of the optical element, reflected by the rear surface of the optical element, and emitted forward from the front surface in the optical axis direction.

  Thus, according to the LED module of the present invention, a sufficient optical path length is obtained until the light beam emitted from the LED light source is emitted forward in the optical axis direction inside the optical element, and the optical axis direction from the front surface of the optical element. Parallel light beams can be taken out, the use efficiency of the emitted light emitted from the LED light source can be improved, and the intensity distribution of the emitted light can be made uniform.

In one embodiment of the LED module, the optical element is
It has a convex lens part formed in the center part through which the optical axis of the LED light source of the front surface passes,
The front surface has a convex lens surface of the convex lens portion and a flat surface continuous to the convex lens surface.

  According to this embodiment, the light beam emitted from the LED light source at a small angle can be efficiently extracted in parallel by the convex lens portion provided at the center of the front surface of the optical element.

In the LED module of one embodiment, the distance between the LED light source and the extended surface of the flat surface of the front surface is Da (mm),
The distance from the intersection of the optical axis of the LED light source and the extended surface of the flat surface of the front surface to the point where the light beam emitted from the LED light source passes on the flat surface or the extended surface of the flat surface is Db (mm ) And
When the refractive index of the optical element is n, the following expression (1) is established.
Db ≧ Da · (n ² −1) ^1/2 (1)

According to this embodiment, the shape of the convex lens portion is obtained by determining the distance Da, the distance Db, and the refractive index n that satisfy the condition of the above equation (1). Further, a contact point between the convex lens and the flat surface on the front surface around the convex lens is obtained. As an example, by setting the radius of the convex lens portion to the minimum value (Da · (n ² −1) ^1/2 ) within the condition of the distance Db that satisfies the above equation (1), The emitted light can be used most effectively.

Further, in the LED module of one embodiment, the plurality of light beams totally reflected on the front surface are reflected toward the rear surface as parallel light beams, and the first paraboloid included in the side surface,
The plurality of light beams reflected by the side surfaces are reflected toward the front surface as parallel light beams and have at least one paraboloid of the second paraboloid included in the rear surface.

  According to this embodiment, at least one of the side surface and the rear surface of the optical element includes the paraboloid, so that the light emitted from the LED light source can be efficiently collimated inside the optical element. can do.

  In addition, by reflecting the reflected light from the front surface inward in the width direction on the side surface, the position where the parallel converted light beam is emitted from the front surface can be made near the LED light source, and the light beam extracted in the optical axis direction Illuminance unevenness can be suppressed, and light rays with uniform and parallel intensity distribution can be extracted. In addition, by arranging the side surface at a small angle with respect to the optical axis so that the reflected light from the front surface is reflected inward in the width direction on the side surface, it is possible to suppress the optical element from becoming large in the width direction. In addition, downsizing is possible.

  In the LED module of one embodiment, the LED light source is inserted into the optical element.

  According to this embodiment, the LED light source can be incorporated into the optical element simultaneously with the molding of the LED light source and the optical element by arranging the LED light source inside the optical element by insert molding, for example. Therefore, it is not necessary to attach an LED light source later, and it can be applied to mass production. Further, it is not necessary to consider the positional deviation of the LED light source when molding the optical element.

  Moreover, in the LED module of one embodiment, the optical element has a light beam capturing unit that receives the light emitted from the LED light source while the LED light source is fitted.

  According to this embodiment, the LED light source and the LED chip can be easily exchanged by attaching / detaching the LED light source to / from the light beam capturing portion of the optical element. In addition, it is not necessary to consider the displacement of the LED light source when molding the optical element, and the manufacturing cost and molding time can be reduced.

In one embodiment of the LED module, the optical element is fitted in a recess formed in a metal base,
A side surface and a rear surface of the optical element are in contact with a wall surface of a recess formed in the metal base.

  According to this embodiment, since the metal base can be used as a reflecting surface by molding the side surface and the rear surface of the optical element on the metal base, it is necessary to process the side surface and the rear surface into a reflecting surface after the optical element is molded. Absent.

  Moreover, in the LED module of one Embodiment, the convex lens part formed in the said front surface is integrally molded with the said optical element.

  According to this embodiment, by integrally molding the optical element and the convex lens portion, the center of the light emitting surface of the LED light source and the center of the convex lens portion can be precisely controlled, so that the utilization efficiency of the light emitted from the LED light is improved. Can be planned.

  Moreover, in the LED module of one Embodiment, the said convex lens part is a different member from the said optical element.

  According to this embodiment, by forming the convex lens part and then attaching it to the optical element, it is not necessary to consider the displacement of the LED light source during molding, and the manufacturing cost and molding time can be reduced.

Moreover, the LED backlight unit of one embodiment includes the LED module,
Unit case,
A light emitting surface member disposed in the opening of the unit case;
A hollow light guide region is formed between the LED module and the light emitting surface member disposed in the unit case, and the light emitted from the LED module to the hollow light guide region is reflected to the light emitting surface member. And a reflecting member to be directed.

  According to the LED backlight unit of this embodiment, the LED module can take out the divergent light from the LED light source in a parallel and uniform manner, and can further improve the light use efficiency of the LED light source. It is possible to reduce the size by reducing the size of the light emitting surface of the light emitting surface member in the normal direction.

Moreover, a micro projector according to an embodiment includes the LED module,
The polarization conversion element, the polarization beam splitter, the reflective liquid crystal element panel, and the projection lens are arranged so that the light rays emitted from the LED module are sequentially incident.

  According to the microprojector of this embodiment, the light beam emitted from the LED module and reflected by the reflective liquid crystal element panel through the polarization conversion element and the polarization beam splitter is directly projected on the screen through the projection lens. . For this reason, it is necessary to irradiate the reflective liquid crystal element panel with light having high directivity. Here, since the LED module can control the radiation angle from the LED light source within, for example, 5 °, it is possible to irradiate the reflective liquid crystal element (LCOS) panel with light having high directivity. In addition, a high-performance and miniaturized microprojector can be realized and can be mounted on a mobile phone or a small PDA.

  According to the LED module of the present invention, the light emitted from the LED light source at a large angle with respect to the optical axis is sequentially reflected on the front surface, the side surface, and the rear surface of the optical element and emitted from the front to the front in the optical axis direction. A sufficient light path length is obtained until the light beam emitted from the LED light source is emitted forward in the optical axis direction inside the optical element, and parallel light beams can be extracted from the front surface of the optical element in the optical axis direction front. Therefore, according to this invention, the utilization efficiency of the emitted light emitted from the LED light source can be improved and the intensity distribution of the emitted light can be made uniform.

It is sectional drawing which shows 1st Embodiment of the LED module of this invention. It is a schematic diagram which shows the path | route of the light ray c from the LED light source 42 to the output surface 43. FIG. It is the figure which showed the path | route until the light ray radiated | emitted from the LED light source 2 of the said 1st Embodiment is inject | emitted from the output surface 3. FIG. It is sectional drawing which shows 2nd Embodiment of the LED module of this invention. It is sectional drawing which shows 3rd Embodiment of the LED module of this invention. It is sectional drawing which shows the modification of the said 3rd Embodiment. It is sectional drawing which shows 4th Embodiment of the LED module of this invention. It is sectional drawing which shows 5th Embodiment of the LED module of this invention. It is sectional drawing which shows the modification of the said 5th Embodiment. It is sectional drawing of the backlight unit for liquid crystal displays as 6th Embodiment of this invention. It is a figure which shows typically the micro projector as 7th Embodiment of this invention. It is a figure which shows the light distribution characteristic of the LED modules 81-83 which the said 7th Embodiment has. It is a figure which shows the intensity distribution characteristic of the LED modules 81-83 which the said 7th Embodiment has. It is sectional drawing which shows the conventional LED module. It is sectional drawing which shows another conventional LED module. It is sectional drawing which shows another conventional LED module.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

(First embodiment)
FIG. 1A is a cross-sectional view showing the LED module of the first embodiment of the present invention. In the LED module of the first embodiment, an LED light source 2 as a light source is inserted into an optical element 1 filled with a refractive material 1A. For example, the LED light source 2 can be disposed inside the optical element 1 by insert molding. The optical element 1 has a front emission surface 3 in the direction of the optical axis J. This emission surface 3 forms the front surface of the optical element 1 and emits light emitted from the LED light source 2. The center of the light emitting surface of the LED light source 2 is on the optical axis J.

  Further, the side surface 4 on the outer side in the width direction (radial direction) of the optical element 1 has a shape that extends annularly around the optical axis J and is a parabola in cross section. The side surface 4 of the optical element 1 is located behind the emission surface 3 in the emission direction of the light beam. In FIG. 1, the side surface 4 is disposed so as to be inclined at an angle as small as 12 ° with respect to the optical axis with respect to the optical axis J. By forming a reflection film (not shown) on the side surface 4, the light beam totally reflected by the emission surface (front surface) 3 is reflected by the side surface 4.

  Further, a frustoconical recess 9 is provided behind the optical element 1 in the optical axis direction, and a reflective film (not shown) is formed on the wall surface 5 of the recess 9. The wall surface 5 constitutes the rear surface of the optical element 1. The wall surface 5 reflects the light beam reflected by the annular side surface 4 toward the emission surface (front surface) 3. The LED light source 2 is located at the bottom of the recess 9 and is connected to a wiring 6.

In the LED module of the first embodiment, the emission surface 3, the side surface 4, and the wall surface 5, which is the rear surface, are aspheric surfaces that satisfy the following expression (2). In this formula (2), α = Y ² / R and β = (1− (1 + K) · (Y ² / R ² )) ^1/2 .
Z = α / (1 + β) + AY ⁴ + BY ⁶ (2)
In equation (2):
α = Y ² / R,
β = (1- (1 + K) · (Y ² / R ² )) ^1/2 ,
K: conic constant,
A, B: aspheric coefficient,
Y: height from the optical axis,
R: radius of curvature of aspherical vertex,
Z: from the tangent plane of the aspherical vertex of the point on the aspherical surface with height Y from the optical axis
Vertical distance,
The radius of curvature R, the conic constant K, and the aspherical coefficients A and B are values as shown in (Table 1) below, for example. The unit of the curvature radius R is mm.
(Table 1)

  In addition, a wiring 6 for power supply is connected to the back surface of the LED light source 2, and the LED light source 2 is supplied with power from the outside via the wiring 6 for power supply. The reflective film (not shown) formed on the side surface 4 and the wall surface (rear surface) 5 of the optical element 1 can be formed by evaporating a metal such as aluminum or a dielectric multilayer film.

In general, the following can be said with respect to the angle of light incident on the peripheral portion of a refractive material used as a light-transmitting resin. That is, as shown in FIG. 1B, the distance from the LED light source 42 to the emission surface 43 is Za (mm), and the distance from the intersection of the optical axis J and the emission surface 43 to the point where the light beam c2 passes on the emission surface 43. Is Zb (mm) and the refractive index of the refractive material 41A is n, the light ray c2 that satisfies the following equation (3) is transmitted through the emission surface 43, and the light ray c2 that does not satisfy the following equation (3) is the emission surface 43. Total reflection.
Zb <Za · (n ² −1) ^1/2 (3)

On the other hand, in the configuration of the LED module of the first embodiment shown in FIG. 1C, the distance from the LED light source 2 to the exit surface 3 is Da, and the light beam passes on the exit surface 3 from the intersection of the optical axis J and the exit surface 3. The distance to the point is Db, and the refractive index of the refractive material 1A is n. Here, out of the light rays emitted from the LED light source 2, the light ray S0 incident on the emission surface (front surface) 3 of the optical element 1 in a range satisfying the following expression (4) is transmitted through the emission surface 3 and is in the optical axis direction. It is emitted as parallel light. The unit of the distances Da and Db is mm.
Db <Da · (n ² −1) ^1/2 (4)

  On the other hand, among the light beams emitted from the LED light source 2, the light beam S1 incident at a large angle not satisfying the above expression (4) of the output surface 3 does not pass through the output surface 3, and is rearward in the optical axis direction and outside in the width direction. Is totally reflected. The light beam S2 totally reflected by the exit surface 3 is reflected by the side surface 4 backward in the optical axis direction and inward in the width direction (radial direction). That is, the light beam S2 is reflected by the side surface 4 toward a plane including the optical axis J. The reflected light beam S3 is further reflected forward in the optical axis direction by the wall surface 5 of the depression 9, and is emitted from the emission surface 3 forward in the optical axis direction as a parallel light beam S4.

  As described above, in this embodiment, the light incident on the emission surface 3 of the optical element 1 from the light emitting surface of the LED light source 2 under the total reflection condition is repeatedly reflected on the side surface 4 and the wall surface 5 and emitted from the emission surface 3. In the meantime, a sufficient optical length can be gained inside the optical element 1, and it can be extracted from the exit surface 3 as a parallel light beam S 4. Therefore, according to this embodiment, it is possible to improve the utilization efficiency of the emitted light emitted from the LED light source 2 and make the emitted light intensity distribution uniform.

  Further, in this embodiment, as shown in FIG. 1C, the side surface 4 of the optical element 1 is arranged at an angle as small as 12 ° with respect to the optical axis J with respect to the optical axis J, thereby allowing the light beam S2 to be emitted. The light beam S4 can be reflected inward in the width direction (radial direction), and the exit region of the light beam S4 can be a radially inward region on the exit surface 3. As a result, it is possible to extract a light beam having a uniform intensity distribution from the exit surface 3 of the optical element 1. Further, by disposing the side surface 4 of the optical element 1 at an angle as small as 12 ° with respect to the optical axis J, for example, it is possible to suppress an increase in the width dimension of the LED module. In the above embodiment, the side surface 4 and the wall surface 5 of the optical element 1 are paraboloid surfaces represented by the above formulas (2) and (Table 1), so that the light emitted from the LED light source 2 is optically reflected. The elements 1 can be efficiently parallelized inside.

(Second embodiment)
FIG. 2 is a sectional view showing an LED module according to a second embodiment of the present invention. In the LED module of the second embodiment, an LED light source 12 as a light source is inserted into an optical element 11 filled with a refractive material 11A. This second embodiment is different from the first embodiment described above in that the optical element 11 has a convex lens portion 17 at the center of the exit surface 13.

  The optical element 11 has an emission surface 13 as a front surface in the direction of the optical axis J, and a convex lens portion 17 formed at a central portion of the emission surface 13 through which the optical axis J of the LED light source 12 passes. The exit surface 13 has a convex lens surface 17A of the convex lens portion 17 and a flat surface 18 formed on the radially outer side of the convex lens surface 17A. The exit surface 13 is an exit surface that emits the light emitted from the LED light source 12.

In the second embodiment, in order to effectively use the light emitted from the LED light source 12, the effective diameter of the convex lens portion 17 is a value of the distance Db that satisfies the following expression (1). In addition, it is desirable to set the effective diameter of the convex lens part 17 to the minimum value (Da · (n ² −1) ^1/2 ) among the values of the distance Db satisfying the expression (1). The center of the convex lens portion 17 and the center of the light emitting surface of the LED light source 12 are on the optical axis J.
Db ≧ Da · (n ² −1) ^1/2 (1)

  In this equation (1), the distance between the LED light source 12 and the extended surface Sp of the flat surface 18 of the emitting surface 13 is Da (mm). Further, the light beam emitted from the LED light source 12 passes through the flat surface 18 or the extended surface Sp of the flat surface 18 from the intersection point P0 between the optical axis J of the LED light source 12 and the extended surface Sp of the flat surface 18. Is the distance Db (mm). The refractive index of the optical element 11 is n.

  In the second embodiment, the side surface 14 on the outer side in the width direction (radial direction) of the optical element 11 has a shape that extends annularly around the optical axis J and is a parabola in cross section. The side surface 14 is inclined with a small angle of 12 ° with respect to the optical axis J, and a reflective film (not shown) is formed on the side surface 14 as a reflective surface. Yes. Further, a truncated cone-shaped recess 19 is formed behind the optical axis of the optical element 11, and a reflecting film (not shown) is formed on the wall surface 15 of the recess 19 to form a reflecting surface.

  In this embodiment, as an example, the shape of the optical element 11 is 11 mm in the width direction (radial direction) and 5 mm in the optical axis direction, and is emitted from the emission surface 13 that forms the front surface of the optical element 11. The beam diameter of the light beam is 9 mm.

In the optical element 11 of the second embodiment, the convex lens portion 17 on the exit surface 13 that forms the front surface, the flat surface 18 on the exit surface 13, the side surface 14, and the wall surface 15 that forms the rear surface are expressed by the above equation (2). The radius of curvature R, the conical constant K, and the aspherical coefficients A and B are, for example, values as shown in the following (Table 2). The unit of the curvature radius R is mm.
(Table 2)

  Further, a wiring 16 for power supply is connected to the back surface of the LED light source 12, and the LED light source 12 is supplied with power from the outside via the wiring 16 for power supply. The reflective film (not shown) formed on the side surface 14 and the wall surface (rear surface) 15 of the optical element 11 can be formed by evaporating a metal such as aluminum or a dielectric multilayer film, for example.

  In the LED module according to the second embodiment, among the light rays emitted from the LED light source 12, the light rays incident on the exit surface 13 within the range of the effective diameter Db of the convex lens 17 are bent by the convex lens portion 17, and are in the optical axis direction. It is emitted as parallel light forward. Of the light rays emitted from the LED light source 12, the light rays that are incident on the flat surface 18 out of the effective diameter Db of the convex lens 17 on the light exit surface 13 do not pass through the light exit surface 13, which is the front surface. It is totally reflected backward in the direction and outward in the width direction. The light beam totally reflected by the emission surface 13 is reflected by the side surface 14 toward the rear in the optical axis direction and toward the inner side in the width direction, reflected by the rear wall surface 15 in the optical axis direction, and parallel to the front emission surface 13. The light beam is emitted forward in the optical axis direction.

  In the LED module of the second embodiment, light emitted from the LED light source 12 at a large angle with respect to the optical axis J (that is, outside the range of the effective diameter Db of the convex lens 17) is flat on the emission surface 13 of the optical element 11. After being totally reflected by the surface 18, it is reflected by the side surface 14 and the wall surface 15 of the optical element 11, and is emitted in parallel with the optical axis J from the emission surface 13. As described above, in the second embodiment, the light incident on the emission surface 13 of the optical element 11 from the light emitting surface of the LED light source 12 is repeatedly reflected on the side surface 14 and the wall surface 15, and thus is emitted from the emission surface 13. In the meantime, a sufficient optical length can be gained inside the optical element 11, and it can be taken out as a parallel light beam from the emission surface 13.

  Moreover, in this 2nd Embodiment, by providing the convex lens part 17 on the output surface 13, it radiates | emits from the LED light source 12 at a small angle, and injects into the location within the distance Db from the intersection P0 by the above-mentioned Formula (1). Can be efficiently extracted in parallel. Further, by arranging the side surface 14 of the optical element 11 at a small angle (12 ° as an example) with respect to the optical axis J, the light beam is reflected by the side surface 14 in the width direction (radial direction), so The exit region of the light beam can be a radially inner region. As a result, it is possible to extract a light beam having no unevenness in intensity distribution from the exit surface 13 of the optical element 11. Further, by arranging the side surface 14 of the optical element 11 with respect to the optical axis J, for example, at an angle as small as 12 °, it is possible to suppress an increase in the width dimension of the LED module.

(Third embodiment)
FIG. 3A is a cross-sectional view showing an LED module according to a third embodiment of the present invention. In the LED module of the third embodiment, the LED light source 22 as a light source is not inserted into the optical element 21 filled with the refractive material 21A. In the third embodiment, as shown in FIG. 3A, a light beam capturing portion 30 is provided on the wall surface (rear surface) 25 of the truncated cone-shaped recess 29 inside the optical element 21. The wall surface 25 of the recess 29 forms the rear surface of the optical element 21. An LED light source 22 fitted with a shell-type cap 40 is fitted to the light beam capturing unit 30, and a light beam emitted from the LED light source 22 is captured from the light beam capturing unit 30 into the optical element 21.

  As shown in FIG. 3B, the LED light source 22 without the bullet-shaped cap 40 may be directly incorporated into the light beam capturing portion 31 provided on the wall surface 25 of the recess 29 of the optical element 21.

  In the third embodiment, the optical element 21 includes an emission surface 23 as a front surface in front of the direction of the optical axis J. The exit surface 23 includes a convex lens portion 27 formed in a range satisfying the above-described formula (1), and a flat surface 28 formed on the radially outer side of the convex lens portion 27. The exit surface 23 is an exit surface that emits the light emitted from the LED light source 22.

  In the third embodiment, in order to effectively use the light emitted from the LED light source 22, the effective diameter of the convex lens portion 27 is set to the minimum value among the values of the distance Db satisfying the above-described equation (1). It is desirable to set. The center of the convex lens part 27 and the center of the light emitting surface of the LED light source 22 are on the optical axis J.

  Further, the side surface 24 on the outer side in the width direction of the optical element 21 has a shape that extends annularly around the optical axis J and is a parabola in cross section. The side surface 24 is located behind the light exit surface 23 in the light emission direction. The side surface 24 is inclined with respect to the optical axis J at a small angle of, for example, 12 ° with respect to the optical axis J, and is reflected by forming a reflective film (not shown) on the side surface 24. It is a surface. Further, a truncated cone-shaped depression 29 is provided behind the optical axis of the optical element 21, and a reflection film (not shown) is formed on the wall surface 25 of the depression 29 to form a reflection surface.

  In this embodiment, as an example, the shape of the optical element 21 is such that the dimension in the width direction (radial direction) is 11 mm, the dimension in the optical axis direction is 5 mm, and the beam diameter of the light beam emitted from the exit surface 23 is 9 mm. It has become.

In the optical element 21 of the third embodiment, the convex lens portion 27 on the exit surface 23 that forms the front surface, the flat surface 28 on the exit surface 23, the side surface 24, the wall surface 25 that forms the rear surface, and the light beam capturing portion 30 are expressed by the formulas described above. The aspherical surface satisfying (2), and the radius of curvature R, the conic constant K, and the aspherical coefficients A and B have values as shown in (Table 3) below, for example. The unit of the curvature radius R is mm.
(Table 3)

  Further, a wiring 26 for power supply is connected to the back surface of the LED light source 22, and the LED light source 22 is supplied with power from the outside via the wiring 26 for power supply. The reflective film (not shown) formed on the side surface 24 and the wall surface (rear surface) 25 of the optical element 21 can be formed by evaporating a metal such as aluminum or a dielectric multilayer film, for example.

  In the LED module of the third embodiment, among the light rays emitted from the LED light source 22, the light rays that have entered the effective diameter Db of the convex lens portion 27 that satisfies the above-described formula (1) on the emission surface (front surface) 23 are The light is bent by the convex lens portion 27 and emitted as light parallel to the front in the optical axis direction. On the other hand, out of the light rays emitted from the LED light source 22, the light rays incident on the emission surface (front surface) 23 outside the effective diameter Db range of the convex lens portion 27 do not pass through the emission surface 23 and are rearward in the optical axis direction. And it is totally reflected outward in the width direction. The light beam totally reflected by the exit surface 23 is reflected rearward in the optical axis direction and inward in the width direction by the side surface 24, further reflected forward by the wall surface (rear surface) 25 in the optical axis direction, and parallel from the exit surface 23. Is emitted forward in the optical axis direction.

  In the LED module of the third embodiment, the light beam emitted from the LED light source 22 at a large angle (total reflection condition) with respect to the optical axis direction and emitted outside the effective diameter Db of the convex lens portion 27 After the total reflection at 23, the light is reflected by the side surface 24 and the wall surface 25 of the optical element 21, and is emitted from the emission surface 23 in parallel to the optical axis direction. That is, according to the third embodiment, light incident from the light emitting surface of the LED light source 22 to the emission surface 23 of the optical element 21 under the total reflection condition is repeatedly reflected on the side surface 24 and the wall surface 25, and is thus emitted from the emission surface 23. In the meantime, a sufficient optical length can be gained inside the optical element 21, and it can be taken out as a parallel light beam from the emission surface 23.

  In the third embodiment, the side surface 24 is inclined with respect to the optical axis J at an angle as small as 12 °, for example, so that the light beam is reflected by the side surface 24 in the width direction (radial direction). The exit region of the light beam from the exit surface 23 can be the radially inner region. Therefore, it is possible to take out a light beam having no unevenness in the intensity distribution from the emission surface 23 of the optical element 21.

  Further, by arranging the side surface 24 of the optical element 21 at a small angle (12 ° as an example) with respect to the optical axis J, it is possible to suppress an increase in the width dimension of the LED module. Further, by providing the optical element 21 with the light beam capturing unit 30, the LED light source 22 can be easily replaced. In addition, with this configuration, it is possible to suppress the generation of defective products due to the deviation of the LED light source 22 during manufacturing, thereby improving the yield and reducing the cost.

(Fourth embodiment)
FIG. 4 is a sectional view showing an LED module according to a fourth embodiment of the present invention. The LED module according to the fourth embodiment is different from the third embodiment described above only in that the reflective film is not formed on the side surface 24 and the wall surface 25 of the optical element 21 on the metal base 50. Different. Therefore, in the fourth embodiment, the same reference numerals are given to the same parts as those in the third embodiment, and the parts different from those in the third embodiment will be mainly described.

  As shown in FIG. 4, the LED module of the fourth embodiment is molded so as to fit into a recess V formed in the metal base 50. Accordingly, in the fourth embodiment, the side surface 24 of the optical element 21 is in contact with the wall surface 50A of the recess V of the metal base 50, and the wall surface (rear surface) 25 of the optical element 21 is in contact with the wall surface 50B of the recess V of the metal base 50. ing. Therefore, in the fourth embodiment, it can be used as a mirror surface without providing a vapor deposition film as a reflection film on the side surface 24 and the wall surface 25 of the optical element 21 that is a transmission surface as it is. Therefore, there is no need to process each of the side surface 24 and the wall surface 25 of the optical element 21 into a mirror surface. Further, by molding the optical element 21 on the metal base 50, the LED light source 22 and the metal base 50 are in contact with each other as shown in FIG. For this reason, the metal base 50 can be utilized as a heat dissipation mechanism, and an LED module with excellent heat dissipation can be obtained.

  In this embodiment, the lifetime of the LED light source 22 can be extended by improving the heat dissipation of the LED light source 22. Furthermore, since this embodiment is integrally formed with the metal base 50, a separate heat dissipation mechanism is not required, the number of members of the LED module can be reduced, and the cost can be reduced.

(Fifth embodiment)
FIG. 5 is a sectional view showing an LED module according to a fifth embodiment of the present invention. The fifth embodiment differs from the second embodiment only in that an optical element 51 is provided instead of the optical element 11 of the second embodiment. Therefore, in the fifth embodiment, the same reference numerals are given to the same portions as those in the second embodiment, and the portions different from those in the second embodiment will be mainly described.

  In the LED module of the fifth embodiment, an LED light source 12 as a light source is inserted into an optical element 51 filled with a refractive material 51A. The optical element 51 has a base portion 52 and a convex lens portion 53. The base 52 includes an emission surface 55 as a front surface in front of the direction of the optical axis J. A convex lens portion 53 is fixed on the emission surface 55 with an adhesive or the like. The center of the convex lens portion 53 is on the optical axis J and has the same shape as the convex lens portion 17 of the second embodiment described above.

  Further, the emission surface (front surface) 55, the side surface 56, the wall surface (rear surface) 57 and the recess 58 of the base portion 52 of the optical element 51 of the fifth embodiment are respectively the emission surface of the optical element 11 of the above-described second embodiment. 13, side surfaces 14, wall surfaces 15, and depressions 19.

  In the fifth embodiment, the base portion 52 and the convex lens portion 53 constituting the optical element 51 are molded as separate members. Thereby, in the molding process of the LED module, when a deviation occurs in the arrangement of the LED light source 12, the positional deviation can be easily corrected by adjusting the arrangement of the convex lens part 53 with respect to the emission surface 55 of the base part 52. Therefore, the position adjustment of the LED light source 12 and the convex lens part 53 can be performed accurately, the generation of defective products due to the deviation of the optical axis can be suppressed, and the yield can be improved.

  FIG. 6 shows a modification of the fifth embodiment. In the modification shown in FIG. 6, an optical element 61 is provided instead of the optical element 51. The optical element 61 includes a base 62 and a convex lens part 63, and has an output surface 65, a side surface 66, a wall surface 67, and a recess 68 similar to those of the optical element 51 described above. In this modification, the base 62 has a fitting recess 64, and the fitting convex portion 63 </ b> A of the convex lens portion 63 is fitted and fixed to the fitting concave portion 64. In the fifth embodiment described above, a guide for positioning the convex lens portion 53 may be provided on the emission surface 55 of the base portion 52 in FIG. The refractive material forming the base portions 52 and 62 of the optical elements 51 and 61 and the refractive material forming the convex lens portions 53 and 63 may be different materials.

(Sixth embodiment)
Next, FIG. 7 shows a cross section of a backlight unit for liquid crystal display as a sixth embodiment of the present invention. This backlight unit includes the LED module 77 of the first embodiment described above.

  The backlight unit according to the sixth embodiment is arranged along a line parallel to one side at the center of the bottom surface of the rectangular unit case 73 and the unit case 73, and gradually increases toward the sides of the ridge. It has a mountain-shaped light reflecting member 74 that is lowered. A light emitting surface member 75 is disposed on the front opening surface of the unit case 73.

  The unit case 73 is covered with the front frame 76 from the light emitting surface member 75 side and integrated with the unit case 73, whereby the backlight unit of this embodiment is assembled. A space portion sandwiched between the mountain-shaped light reflecting member 74 and the light emitting surface member 75 in the unit case 73 is a hollow light guide region 79. The mountain-shaped light reflecting member 74 is formed by laminating, for example, a white PET (Polyethylene Terephthalate) film or a white ink as a highly reflective and diffusely reflective material on a metal or resin material. Further, as the material having the luminance distribution of the light emitting surface member 75, in addition to the white PET, a highly reflective aluminum having a specular reflection property or the like may be coated with a light transmissive diffusing material. The light emitting surface member 75 is configured by further stacking an optical sheet such as a diffusion sheet or a lens sheet on at least the light transmission diffusion material. The light emitting surface member 75 passes through the hollow light guide region 79 and uniformly diffuses and emits the light reflected by the chevron-shaped light reflecting member 74, thereby eliminating unevenness in luminance on the light emitting surface and uniformity. It works to raise. The unit case 73 is made of a metal having high thermal conductivity such as an aluminum alloy.

  The LED module 77 of the first embodiment described above is disposed on each side surface of the unit case 73 parallel to the ridge line of the mountain-shaped light reflecting member 74. In the backlight unit of the sixth embodiment, a large number of LED modules 77 are mounted in a row or a plurality of rows on a long and narrow wiring board (not shown) having a width that can be accommodated on a corresponding side surface of the unit case 73. Further, the wiring 6 for supplying power is formed of a metal such as photothermal conductive aluminum or aluminum alloy, or a ceramic such as aluminum nitride. The wiring 6 is fixed to the side wall of the highly heat-conductive unit case 73 by screwing, bonding or other means.

  In the sixth embodiment, the LED module 77 is the LED module of the first embodiment, but any one of the LED modules of the second to fifth embodiments described above may be adopted.

(Seventh embodiment)
FIG. 8 schematically shows a micro projector as a seventh embodiment of the present invention. This ultra-small projector includes three LED modules 81, 82, and 83 and a dichroic prism 85. The three LED modules 81, 82, 83 face the dichroic prism 85 from three directions. In the seventh embodiment, the LED modules 81 to 83 are the LED modules of the first embodiment described above, but the LED modules of the second to fifth embodiments described above may be employed. Further, this ultra-compact projector includes a polarization conversion element 86 on which the light beam from the dichroic prism 85 is incident, a polarization beam splitter 88 on which the light beam from the polarization conversion element 86 is incident, and a display device. A reflective LCOS (Liquid Crystal On Silicon) panel 89 and projection lenses 87A, 87B, 87C are provided. Each optical component described above is arranged in the unit case 90.

  In the ultra-compact projector of the seventh embodiment, the LED light sources 81A, 82A, 83A included in the LED modules 81, 82, 83 employ red LEDs, green LEDs, and blue LEDs, respectively. In the seventh embodiment, the arrangement of these three LED light sources 81A to 83A is arbitrary and may be interchanged.

  The unit case 90 of the microminiature projector according to the seventh embodiment is as small as 50 mm × 40 mm × 15 mm in length × width × height as an example, and is thin notebook PC, mobile phone, PDA ( (Personal Digital Assistance: portable information terminal).

  A light beam incident on the reflective LCOS panel 89 from the polarizing beam splitter 88 is reflected by the reflective LCOS panel 89 and then directly projected by the projection lenses 87C, 87B, 87A. In this ultra-small project, the light incident on the reflective LCOS panel 89 is highly parallel to improve the F-number of the projection lenses 87A, 87B, 87C and to suppress the reduction in contrast caused by the polarizing beam splitter 88. It is desired that the light has been converted into a light beam.

  Next, the result of simulating the optical characteristics of the LED modules 81 to 83 included in the seventh embodiment will be described with reference to FIGS. Regarding this simulation condition, the LED light sources 81A to 83A showed a Lambertian distribution, the size of the light emitting surface was 1 mm square, and the distance between the optical element 1 and the LCOS panel 89 was 20 mm.

  The light distribution characteristic K1 shown in FIG. 9 is a result of simulating the light distribution characteristic of the light beam extracted from each LED module 81-83. The light emitted from the LED light sources 81A to 83A is parallel-converted to an angle of 5 ° or less by the LED modules 81 to 83, and it can be seen that the light rays extracted from the LED modules 81 to 83 have high parallelism. Further, the light utilization efficiency of the LED module, which was about 10% in the past, has increased to 30% by adopting the LED modules 81 to 83 of the above embodiment.

Moreover, the intensity distribution characteristic K2 shown in FIG. 10 is a result of simulating the intensity distribution on the LCOS panel 89 of the light rays extracted from the LED modules 81 to 83. In FIG. 10, the horizontal axis represents the distance Y (mm) from the optical axis of the LED module, and the vertical axis represents the intensity of the light beam (light flux / mm ² ). According to this intensity distribution characteristic K2, it can be seen that, when an 8 mm square LCOS panel 89 is used, light with a parallel and uniform intensity distribution can be supplied by using the LED modules 81 to 83 of the above embodiment.

  According to the light distribution characteristic K1 of FIG. 9 representing the optical characteristics of the LED modules 81 to 83 and the intensity distribution characteristic K2 of FIG. 10, the light distribution characteristics of the light rays extracted from the LED modules 81 to 83 are uniform, and the intensity. It can be seen that the distribution is uniform. That is, by adopting the LED modules 81 to 83, it is possible to take out light rays that are parallel and have a uniform intensity distribution.

  The LED module according to the present invention is a parallel and uniform lighting device such as a foot lamp, an indicator lamp, a spotlight, a wall washer, an architectural lamp, a stand, an interior lamp, a signal lamp, a gaze guidance lamp, a micro projector, an LED backlight, etc. It can be used for applications that require extra light.

1, 11, 21, 51, 61 Optical element 1A, 11A, 21A, 51A Refraction material 2, 12, 22 LED light source 3, 13, 23, 55 Output surface (front surface)
4, 14, 24, 56 Side surface 5, 15, 25, 57 Wall surface (rear surface)
6, 16, 26 Wiring 9, 19, 29, 58 Depression 17, 27, 53, 63 Convex lens portion 18, 28 Flat surface 30 Light receiving portion 40 Cannonball type cap 50 Metal base 52, 62 Base portion 73 Unit case 74 Light reflecting member 75 Light emitting surface member 76 Front frame 77, 81-83 LED module 79 Hollow light guide region 85 Dichroic prism 86 Polarization conversion element 87A-87C Projection lens 88 Polarization beam splitter 89 Reflection LCOS panel 90 Unit case

Claims (11)

An LED light source;
An optical element attached to the LED light source and made of a refractive material,
The optical element is
A front surface that is positioned in front of the LED light source in the light emitting direction of the light beam and transmits or totally reflects light emitted from the LED light source;
A side surface for reflecting the light beam totally reflected on the front surface;
And a rear surface that reflects the light beam reflected by the side surface toward the front surface. The LED module according to claim 1,
The optical element is
It has a convex lens part formed in the center part through which the optical axis of the LED light source of the front surface passes,
The LED module, wherein the front surface has a convex lens surface of the convex lens portion and a flat surface continuous to the convex lens surface. The LED module according to claim 2,
The distance between the LED light source and the extended surface of the flat surface of the front surface is Da (mm),
The distance from the intersection of the optical axis of the LED light source and the extended surface of the flat surface of the front surface to the point where the light beam emitted from the LED light source passes on the flat surface or the extended surface of the flat surface is Db (mm ) And
When the refractive index of the optical element is n, the following equation (1) is established:
Db ≧ Da · (n ² −1) ^1/2 (1) The LED module according to any one of claims 1 to 3,
A plurality of light rays totally reflected at the front surface are reflected toward the rear surface as parallel light rays and are included in the side surface;
A plurality of light beams reflected by the side surface are reflected toward the front surface as parallel light beams and have at least one paraboloid of a second paraboloid included in the rear surface. LED module. The LED module according to any one of claims 1 to 4,
The LED module, wherein the LED light source is inserted into the optical element. The LED module according to any one of claims 1 to 4,
The said optical element has a light beam taking-in part which takes in the light ray radiated | emitted from the said LED light source while the said LED light source is fitted, The LED module characterized by the above-mentioned. The LED module according to any one of claims 1 to 6,
The optical element is fitted in a recess formed in a metal base,
The LED module according to claim 1, wherein a side surface and a rear surface of the optical element are in contact with a wall surface of a recess formed in the metal base. The LED module according to any one of claims 2 to 7,
The LED module, wherein the convex lens portion formed on the front surface is formed integrally with the optical element. The LED module according to any one of claims 2 to 7,
The LED module, wherein the convex lens portion is a separate member from the optical element. The LED module according to any one of claims 1 to 9,
Unit case,
A light emitting surface member disposed in the opening of the unit case;
A hollow light guide region is formed between the LED module and the light emitting surface member disposed in the unit case, and the light emitted from the LED module to the hollow light guide region is reflected to the light emitting surface member. An LED backlight unit comprising a reflecting member that faces the LED backlight unit. An LED module according to any one of claims 1 to 9,
A microprojector, wherein a polarization conversion element, a polarization beam splitter, a reflective liquid crystal element panel, and a projection lens are arranged so that light rays emitted from the LED module are incident in order.

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