WO2007116880A1

WO2007116880A1 - Light source module

Info

Publication number: WO2007116880A1
Application number: PCT/JP2007/057446
Authority: WO
Inventors: Tadao Iwaki
Original assignee: Miraial Co., Ltd.
Priority date: 2006-04-07
Filing date: 2007-04-03
Publication date: 2007-10-18
Also published as: JP4769620B2; JP2007280815A

Abstract

It is possible to provide a cheap light source module by reducing the number of manufacturing steps. The light source module includes, for example, at least three-primary color LED and an X-type dichroic prism. A predetermined gap is hermetically formed from the environment on the X-plane of the X-type dichroic prism where a light reflection plane is positioned. A first plane reflecting the light of the first band is formed on the same plane containing a different prism plane. A second plane reflecting the light of the second band is formed on the same plane containing a different prism plane and orthogonally intersecting the first plane. On the first plane is formed a sub wavelength grating for selectively reflecting the light of the first band. On the second plane is formed a sub wavelength grating for selectively reflecting the light of the second band. The lights emitted from the three-primary color LED are added and mixed substantially on the same optical axis by an X-type dichroic prism for output.

Description

Specification

Light source module technology

[0001] The present invention relates to a light source module, and in particular, at least three primary color LEDs (Light-Emitting

Diode) and a light source module having an X-type dichroic prism.

Background art

[0002] In recent years, with the development of large-screen liquid crystal display devices and projectors, a light source module that obtains white light by additively mixing light emitted from three primary color LEDs in order to realize images with higher color purity. Has been proposed. Here, by using three independent colors on the chromaticity coordinates, it is possible to represent any color within the range of the color triangle formed by these three colors. Three independent colors on the degree coordinate. In general, red, green, and blue (blue-violet) are often used as the three primary colors of light. Recently, in order to expand the color reproduction range, use four primary colors that are mixed with yellow in these three colors. There is also.

[0003] As a light source module (LED module) that obtains white light from the light emitted from the three primary color LEDs, the light from each of the three primary color LEDs is converted into parallel light by a lens, and then the reflecting surface force of the dichroic mirror A triangular prism intersecting in a letter shape has been proposed to combine and emit the three primary colors (see Patent Document 1).

[0004] On the other hand, as a dichroic mirror, a dielectric multilayer mirror in which high-refractive-index dielectric thin films and low-refractive-index dielectric thin films are alternately laminated with a predetermined film thickness, or a period of about 1/10 of a wavelength. Sub-wavelength grating mirrors are known by forming periodic gratings (convex parts) with a predetermined pitch.

Patent Document 1: JP 2005-183005

Disclosure of the invention

Problems to be solved by the invention

[0005] In the conventional X-type dichroic prism, a dielectric multilayer mirror is formed on a glass or plastic right-angle plane processed into a triangular prism, and the dielectric multilayer mirror surface is joined with an optical adhesive. It is usual to form. A dielectric multilayer film is formed on a substrate by vacuum evaporation. Since many films are stacked by the putter method, the film formation time (man-hours) becomes long and expensive, and the X-type dichroic prism using the film also requires long man-hours and becomes expensive. Has a problem.

[0006] On the other hand, the sub-wavelength grating has many fine convex portions that are easily damaged, and thus has not been used for a dichroic mirror provided on a contact surface of a plurality of triangular prisms.

Means for solving the problem

[0007] The present invention provides a light source module having at least three primary color LEDs and an optical device including a dichroic light mirror that additively mixes light from the LEDs, and functions as the dichroic mirror. The portion includes an airtight space defined by a parallel plane having a predetermined gap, and a sub-wavelength grating provided on at least one plane of the airtight space.

[0008] Here, when the optical device is an X-type dichroic prism and the three primary color LEDs are a red LED, a green LED, and a blue LED, the X surface of the X-type dichroic prism In the portion where the light reflecting surface is located, a predetermined gap is formed in an airtight manner from the environment, and the first surface that reflects the red light from the red LED and transmits the other light is a different prism surface. The second surface that reflects blue light from the blue LED and transmits the other light is also formed on the same surface that includes a different prism surface and is orthogonal to the first surface. A sub-wavelength grating that selectively reflects the red light is formed on the first surface, and a sub-wavelength grating that selectively reflects the blue light is formed on the second surface. It is preferable that the light is emitted from the three primary color LEDs. The invention's effect

[0009] According to the present invention, an inexpensive light source module can be provided while reducing the number of manufacturing steps.

FIG. 1 is a schematic cross-sectional view showing the structure of a light source module according to a first embodiment.

FIG. 2 is a perspective view showing a second side prism of the first embodiment.

FIG. 3 is an enlarged cross-sectional view around an airtight space in the first embodiment.

FIG. 4 is an enlarged cross-sectional view of the surface of the subwavelength grating according to the first embodiment. FIG. 5 is a drawing for explaining an additive color mixing method in the first embodiment.

FIG. 6 is a CIE chromaticity diagram for explaining the effect of the light source module according to the first embodiment.

FIG. 7 is a drawing for explaining a conventional method of forming white light.

FIG. 8 is a schematic cross-sectional view showing the structure of a light source module according to a second embodiment.

FIG. 9 is a schematic sectional view showing a detailed configuration of an LED in a second embodiment.

FIG. 10 is a schematic cross-sectional view showing the structure of a light source module according to a third embodiment.

FIG. 11 is a schematic sectional view showing the structure of a light source module according to a fourth embodiment.

FIG. 12 is a schematic sectional view showing the structure of another embodiment (1) obtained by modifying the fourth embodiment.

FIG. 13 is a schematic sectional view showing the structure of another embodiment (2) obtained by modifying the fourth embodiment.

FIG. 14 is a schematic cross-sectional view showing an additive color mixing structure in a light source module according to another embodiment.

Explanation of symbols

[0011] 1, 1A-: IE ... light source module, 2R ... red LED, 2G ... green LED, 2B ... blue LED, 3 ... base prism, 4 ... first side prism, 5 ... second side prism, 6 ... Upper prism, 7-9 ... Flexible printed circuit board (FPC), 10-13, 20 ... Joint, 14 ... Airtight space, 21 ... Recess, 22, 22A, 22B ... Sub-wavelength grating, 40, 41 ... Auxiliary prism 50-52 ... Condensing lens, 60-63 ... Fresnel lens.

BEST MODE FOR CARRYING OUT THE INVENTION

[0012] (A) First embodiment

Hereinafter, a first embodiment of a light source module according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a schematic structure of a light source module according to a first embodiment, and shows a section of an X-type dichroic prism. In the following, for the sake of convenience of explanation, the light source module is expressed as up, down, left, and right based on the state shown in FIG. In FIG. 1, a light source module 1 according to the first embodiment includes a red LED 2R, a green LED 2G and a blue LED 2B, which are three primary color LEDs, and an X-type dichroic prism. The X-type dichroic prism includes a base prism 3, a first side prism 4, a second side prism 5, and an upper prism 6.

[0015] The base prism 3 is a prism having a substantially right-angled isosceles triangle with a right angle located upward, and has a portion protruding from the bottom side to the left and right.

[0016] At the center of the bottom side of the base prism 3, a green LED 2G mounted on the end of the printed wiring board 7 is joined. As the printed wiring board 7, a film-like printed wiring board FPC (Flexible Printed Circuit) is often used. The direction of the emitted light from the green LED 2G is the direction toward the right apex of the prism of a right isosceles triangle.

[0017] The first side prism 4 has a prism shape of a substantially right isosceles triangle with a right angle located on the right side, and is on the left side to join the protruding portion on the left side of the base prism 3 on its upper surface. It has an overhanging portion that extends. The projecting portion on the left side of the base prism 3 and the projecting portion of the first side prism 4 are joined together by an optical adhesive to constitute a joint 10.

[0018] The protruding portion of the first side prism 4 has a stepped shape, and the end force of the printed wiring board 7 on which the red LED 2R is mounted is mounted and bonded to the upper surface. The red LED2R is positioned in the center of the bottom side of the first side prism 4, and the direction of the light emitted from the red LED2R is the right-angled apex of the right isosceles triangular prism in the first side prism 4. It is the direction toward.

[0019] The second side prism 5 is a prism having a substantially right isosceles triangle shape with a right angle on the left side. The second side prism 5 is on the right side of the base prism 3 so as to be joined to the right protruding portion on the upper surface. It has an overhanging portion that extends. The protruding portion on the right side of the base prism 3 and the protruding portion of the first side prism 4 are bonded together by an optical adhesive to form a bonded portion 11.

[0020] The projecting portion of the second side prism 5 has a stepped shape, and the end portion of the printed wiring board 9 on which the blue LED 2B is mounted is placed and bonded on the upper surface thereof. The blue LED2B is located at the center of the bottom of the second side prism 5, and the blue LED2 The direction of the light emitted from B is the direction toward the right-angled apex of the right isosceles triangular prism in the second side prism 5.

[0021] The upper prism 6 is a prism having a generally right isosceles triangular shape with a right angle located downward, and has a portion slightly protruding from the bottom side to the left and right. The upper ends of the first side prism 4 and the second side prism 5 described above are flat surfaces, and these flat surfaces and the portions protruding to the left and right of the upper prism 6 are joined by an optical adhesive, and the joint portion 12 And 13 are configured.

[0022] The distances from the center of the X-type dichroic prism consisting of the base prism 3, the first side prism 4, the second side prism 5, and the upper prism 6 to the light emitting points of the red LED 2R, the green LED 2G, and the blue LED 2B are equal. It is made like that.

In the base prism 3, the first side prism 4, the second side prism 5, and the upper prism 6, the surfaces facing the surfaces of other prisms in the prism shape of a right isosceles triangle are shown in FIG. As illustrated for the side prism 5, the bottoms are flat concave portions 21A and 21B except for the peripheral joint portion 20. The concave portions 21A and 21B have sub-wavelength gratings 22A and 22B as optical functional layers. Is provided. These sub-wavelength gratings 22A and 22B have different color components to be reflected, as will be described later.

[0024] Due to the presence of the recesses 21A and 21B as described above, the X-shaped portion of the X-type dichroic prism is an airtight space 14 as shown in FIG.

FIG. 3 is an enlarged cross-sectional view around the airtight space 14. The airtight space 14 has two planes extending from the center in the upper right direction, the lower left direction, the upper left direction, and the lower right direction. The surface extending in the upper right direction and the lower left direction corresponds to the first surface in the claims, and the surface extending in the upper left direction and the lower right direction corresponds to the second surface in the claims.

[0026] Central force Two sub-wavelength gratings respectively provided on two planes extending in the upper right direction

22A reflects red light emitted from the red LED 2R and transmits light of other colors emitted from the green LED 2G and the blue LED 2B. Similarly, the two sub-wavelength gratings 22A provided on the two planes extending in the lower left direction from the center also reflect the red light emitted from the red LED2R, and the green LED2G and blue LED2B. Forces light of another color emitted.

[0027] The two sub-wavelength gratings 22B provided on the two planes extending in the upper left direction from the center reflect the blue light emitted from the blue LED 2B and are emitted from the green LED 2G and the red LED 2R. It transmits light of other colors. Similarly, the two sub-wavelength gratings 22B provided on the two planes extending from the center to the lower-right direction reflect the blue light emitted from the blue LED 2B and the other emitted from the green LED 2G and the red LED 2R. The light of the color is transmitted.

[0028] For example, when a sub-wavelength grating that reflects red light (having a wavelength of 680 nm) emitted from the red LED 2R is made of polycarbonate, the pitch of the grating (protrusion) (see FIG. 4 described later). (Refer to p in Fig. 4) is about 400 nm, the lattice width (see d in Fig. 4 to be described later) is about 310 nm, and the grating height (see h in Fig. 4 to be described later) is about 220 nm. For example, when a sub-wavelength grating that reflects light emitted from the blue LED 2B (having a wavelength of 450 nm) is made of polycarbonate, the pitch of the grating (projections) is about 440 nm and the grating width is It is good if the grid height is about 220nm.

[0029] In Fig. 1, the power of the green LED 2G is shown in a position where the green light emitted from the green LED 2G is transmitted without being reflected. The arrangement of the three primary colors LEDs 2R, 2G, and 2B is shown here. It is not limited. If the sub-wavelength grating that reflects the green light emitted from the green LED2G is made of polycarbonate, the pitch of the grating (protrusions) is about 350 nm, the grating width is about 230 nm, and the grating height is about 220 nm. Just do it.

[0030] It should be noted that the force not shown in FIG. 1 and FIG. 2, as shown in FIG. 3, the joint 20 (10-13) has a protrusion or protrusion provided on one surface thereof. It is preferable to provide a fitting portion 23 formed of a recess or a groove provided on the other surface so that the prisms 3 to 6 can be appropriately positioned. In the case where the fitting portion 23 is formed of a ridge and a groove, it contributes to an improvement in airtightness.

[0031] As a method (manufacturing method) for providing the sub-wavelength grating 22 (22A, 22B) on the base material (prisms 3 to 6), for example, the following method can be applied. First, a sub-wavelength grating 22 is produced by transferring (imprinting) a polymer film functioning as the sub-wavelength grating 22 onto the substrate 2. Second, when the substrate is a polymer substrate, it is irradiated with an ion beam or photo fine processing. The sub-wavelength grating 22 is produced by direct processing on the substrate using, for example, a technique. The second production method includes a case where the unevenness of the sub-wavelength grating 22 is directly produced on the surface of the substrate using a mold. Third, the subwavelength grating 22 is fabricated by attaching a strip (foil) to the surface of the substrate. Fourth, the surface of a semiconductor substrate such as silicon, germanium, or a compound semiconductor is processed to form a sub-wavelength grating 22, and the semiconductor substrate on which the sub-wavelength grating 22 is formed is bonded to a base material.

FIG. 4 is an enlarged cross-sectional view of the surface of the sub-wavelength grating 22 (22A, 22B) according to the first embodiment. For example, FIG. 4 shows the sub-wavelength grating 22 manufactured using a mold. Yes. In the sub-wavelength grating 22, the extending direction of the protrusions arranged in a lattice shape is not parallel to the normal direction of the sub-wavelength grating 22 but is inclined as shown in FIG. The extending direction of the protrusions arranged in a lattice shape is parallel to the pressing direction of the mold and the pulling direction of the mold, so that the protrusions are not easily damaged during manufacturing using the mold. Of course, when the mold drawing direction is perpendicular to the sub-wavelength grating forming surface, it is preferable to design the sub-wavelength grating so that the extending direction of the protrusion is perpendicular to the sub-wavelength grating forming surface.

[0033] In the light source module 1 of the first embodiment, the red light emitted from the red LED 2R is reflected in the hermetic space 14 by the sub-wavelength grating 22A extending from the center to the upper right and lower left, and upward. It is changed to light that is suitable for. The sub-wavelength grating 22A extended to the upper right and lower left reflects only the wavelength component (wavelength band) of the desired red component, even if the light emitted from the red LED2R contains a wavelength component other than the desired red component. It is supposed to be.

[0034] The blue light emitted from the blue LED 2B is reflected in the airtight space 14 by the sub-wavelength grating 22B extending from the center to the upper left and the lower right, and is changed to an upward force and light. .

[0035] The sub-wavelength grating 22B extended in the upper left and lower right has a desired blue component wavelength component (wavelength band) even if the light emitted from the blue LED 2B includes a wavelength component other than the desired blue component. ) Only.

[0036] Further, the green LED 2G emits upward force Green light passes through the sub-wavelength gratings 22A and 22B positioned in the traveling direction in the airtight space 14 as they are, and the upward force and light remain as they are. Light is emitted from the light source module 1 of the first embodiment. Each sub-wavelength grating 22A, 22B has only the wavelength component (wavelength band) of the desired green component even if the directional light contains a wavelength component other than the desired green component above the green LED 2G. You may pass it through.

[0037] As described above, the light power emitted from the three primary colors LEDs 2R, 2G, and 2B is added in the state where the optical axes are substantially aligned by the X-type dichroic prism in the light source module 1 of the first embodiment. Illuminates an object (not shown) as mixed illumination and white illumination light

[0038] In the light source module 1 of the first embodiment, although not shown, the light quantity control means for electrically controlling the quantity of light emitted from the LEDs 2R, 2G, 2B is provided on the printed wiring boards 8, 9, 10. It is mounted or provided externally so that the additive color mixture ratio can be varied. That is, as shown in FIG. 5, the light intensity of the desired bands (R, G, B) from the LEDs 2R, 2G, 2B can be controlled independently.

[0039] Each of the LEDs 2R, 2G, and 2B may have a built-in photodiode as a photodetector for detecting the light amount, and the detected light amount may be fed back to the light amount control means.

[0040] According to the light source module 1 of the first embodiment, the following effects (1) to (5) can be achieved.

[1] (1) Since the functional layer that performs multiplexing as a dichroic mirror is formed with a sub-wavelength grating that is not a dielectric multilayer film, it is possible to omit a film-forming process that requires man-hours and facilitates manufacture. Thus, a significant cost reduction is possible.

(2) Since the sub-wavelength grating is provided in an airtight space formed by joining a plurality of prisms and separated from the outside air, a highly reliable functional film can be obtained. In other words, the sub-wavelength grating has many fine gratings (protrusions) and is easily damaged, and its function is deteriorated or impaired by adhesion of water or oil. Since it is provided, damage can be prevented and adhesion of water or oil can be prevented, and a highly reliable functional film can be obtained.

[0043] (3) Since the white color is obtained by additive color mixture of light from the three primary color light sources (LEDs), a larger color A triangle can be realized, and the color reproduction range of the illuminated object can be widened. Figure 6 is a CIE chromaticity diagram for explaining this effect. FIG. 7 is an explanatory diagram for obtaining white light using one LED.

[0044] FIG. 7 shows a spectrum in a case where a white phosphor is arranged on the optical path of light from a blue LED to achieve white. In FIG. 6, point A shows the chromaticity of the blue LED, and point B shows the chromaticity at the peak position of the light excited by the yellow phosphor. For this reason, the conventional method intends to obtain the chromaticity of an arbitrary point on the line segment AB by adjusting the amount of light from the blue LED and adjusting the coating amount of the yellow phosphor. However, as can be seen from the white LED spectrum that combines the blue LED and yellow phosphor shown in Figure 7, this white light actually contains red and green components. Therefore, it is possible to reproduce colors in the range indicated by the color triangle ACD in FIG.

[0045] On the other hand, as in the first embodiment, the color triangle obtained by additively mixing the emitted light from the three primary colors LED of red LED2R, green LED2G and blue LED2B is the light of each LED2R, 2G, 2B power. Because of the extremely high color purity, the large color triangle AEF shown in Fig. 6 becomes possible, and a wide range of color reproduction is possible.

[0046] Therefore, by adjusting the additive color mixture ratio of light of three primary color light sources (LEDs), it is possible to emit light of arbitrary chromaticity within the triangle AEF from the light source module 1 of the first embodiment. , Increase the variety of color of illumination light.

[0047] (4) Since an LED is used as the light source, it is a long-life light source module capable of high-speed modulation.

[0048] (5) Since the sub-wavelength gratings having the same function are provided on both surfaces of the parallel plane, the light control function carried by the sub-wavelength gratings can be reliably achieved. Of course, the sub-wavelength grating may be provided only on one surface of the parallel plane.

[0049] (B) Second embodiment

Next, a second embodiment of the light source module according to the present invention will be described in detail with reference to the drawings.

FIG. 8 is a schematic cross-sectional view showing the structure of the light source module according to the second embodiment. FIG. 2 is a diagram corresponding to FIG. 1 according to the first embodiment, and the same and corresponding parts as those in FIG. 1 are denoted by the same reference numerals.

In the light source module 1 A of the second embodiment shown in FIG. 8, the base prism 3, the first side prism 4, and the second side prism 5 have, for example, a cylindrical hole at the center of the bottom surface. The fitting receiving portions 3H, 4H, 5H are provided, and any of the corresponding LEDs 2G, 2R, 2B are fitted into the fitting receiving portions 3H, 4H, 5H. By doing this, each LED2G, 2R, 2B is inserted into the corresponding fitting receiving portion 3H, 4H, 5H and bonded and fixed, so that the position and emission direction of each LED2G, 2R, 2B can be obtained. It is possible to easily perform cornering.

FIG. 9 is a schematic cross-sectional view showing the configuration of the LED 30 (2R, 2G, 2B) in the second embodiment. Note that the horizontal direction in FIG. 9 corresponds to the normal direction of the paper in FIG.

[0053] The LED 30 includes an LED chip 31, a wire 34 for connecting the wiring 33 of the flexible printed wiring board 32 (7-9) and the LED chip 31, and the LED chip 31 and the wire 34 are sealed and a lens. And a sealing lens 35 that exhibits its function. The sealing lens 35 has a cylindrical shape that fits with the fitting receiving portions 3H, 4H, and 5H, and its tip side converts the emitted light from the LED chip 31 into divergent light that is as close to parallel light as possible. The lens shape is as follows. The sealing lens 35 is omitted when the light emitted from the LED chip 31 is small or when each prism (3 to 6) has a condensing lens as in an embodiment described later. Power S can be. The support base on which the LED chip 31 is mounted and fixed has the function of grounding the LED chip 31 at the same time as determining the light emitting point position of the LED chip 31 at an appropriate position on the optical axis.

[0054] Regarding the airtight space 14 and the sub-wavelength grating provided in the airtight space 14 (omitted in FIG. 8; see 22A and 22B in FIG. 3), the light source module 1A of the second embodiment is also the first This is the same as the light source module 1 of the embodiment.

[0055] The second embodiment can provide the same effects as those of the first embodiment. In addition, in the case of the second embodiment, since the three primary color LEDs are attached by fitting, there is an effect that the positions of the three primary color LEDs can be easily made appropriate. In addition, it is easy to optically connect the three primary color LEDs and the X-type dichroic prism. [0056] (C) Third embodiment

Next, a third embodiment of the light source module according to the present invention will be described in detail with reference to the drawings.

FIG. 10 is a schematic cross-sectional view showing the structure of the light source module according to the third embodiment, and is a drawing corresponding to FIG. 1 according to the first embodiment. Are denoted by the same reference numerals.

In the light source module 1B of the third embodiment shown in FIG. 10, the red LED 2R force is provided so that the emitted light travels upward, and the red LED 2R is connected to the first side prism 4. The first auxiliary prism 40 for integrally changing the traveling direction of the light from above to the right is integrally provided. In the light source module 1B of the third embodiment, the blue LED 2B is provided so that the emitted light travels upward, and the traveling direction of the light from the blue LED 2B is indicated on the second side prism 5. A second auxiliary prism 41 for converting from the top to the left is integrally provided.

Here, when the folding of the first auxiliary prism 40 and the second auxiliary prism 41 is developed, the distances from the light emitting points of the LEDs 2R, 2G, and 2B to the X-shaped center are equal.

[0060] In FIG. 10, unlike FIG. 1 according to the first embodiment, the printed wiring board 8 on which the red LED 2R is mounted and the printed wiring board 9 on which the blue LED 2B is mounted are shown in the base prism 3. Although what was provided in the overhang | projection part was shown, of course, you may provide in the other member similar to FIG.

[0061] Regarding the airtight space 14 and the sub-wavelength grating provided in the airtight space 14 (omitted in FIG. 8; see 22A and 22B in FIG. 3), the light source module 1B of the third embodiment is also the first This is the same as the light source module 1 of the embodiment.

[0062] According to the third embodiment, the same effects as those of the first embodiment can be obtained. First

According to the third embodiment, since all the LEDs 2R, 2G, and 2B can be similarly mounted on the printed wiring boards 7 to 9, the printed wiring boards having the same configuration can be applied to the printed wiring boards 7 to 9 for the respective color components. It is possible to do so.

[0063] Since each of the prisms 3 to 6 on which the sub-wavelength grating is formed can be made of plastic, the auxiliary prisms 40 and 41 can be integrated and the degree of freedom of the outer diameter shape can be improved. Therefore, the design can be made flexible. This also applies to the case where the condenser lens as in the fourth to sixth embodiments described later is integrated with the prism (3-6).

[0064] Further, the arrangement as in the third embodiment eliminates the need to adjust the optical axis direction of each LED 2R, 2G, 2B, and facilitates the optical axis adjustment of each LED 2R, 2G, 2B.

[0065] (D) Fourth Embodiment

Next, a fourth embodiment of the light source module according to the present invention will be described in detail with reference to the drawings.

FIG. 11 is a schematic cross-sectional view showing the structure of the light source module according to the fourth embodiment, which is a drawing corresponding to FIG. 10 according to the third embodiment, and is the same as or corresponding to FIG. Are indicated by the same reference numerals.

In the light source module 1C of the fourth embodiment shown in FIG. 11, a condensing lens (third condensing lens) 50 that condenses the light emitted from the green LED 2G is provided integrally with the base prism 3, A condenser lens (first condenser lens) 51 that condenses the light emitted from the red LED 2R is provided integrally with the first side prism 4, and a condenser lens (second condenser) that condenses the light emitted from the blue LED 2B. (Optical lens) 52 is provided integrally with the second side prism 5.

[0068] It should be noted that each prism 3, 4, 5 is secured so as to secure a predetermined distance from each LED 2G, 2R, 2B to the condenser lenses 50-52 so that the condenser lenses 50-52 function effectively. The shape is selected.

[0069] According to the fourth embodiment, the same effects as those of the third embodiment can be obtained. According to the fourth embodiment, since the condensing lens is provided so that the light from each LED is parallel light (or divergent light close thereto), additive color mixture can be executed more appropriately.

[0070] The characteristics of the dichroic mirror by the sub-wavelength gratings (22A, 22B) can reduce the incident angle dependency. However, by adopting the configuration as in the fourth embodiment, The optical characteristics of the mirror can be performed only for substantially parallel incident light, and the optical characteristics of the dichroic mirror can be improved.

FIG. 12 shows a light source module according to another embodiment (1) obtained by modifying a part of the fourth embodiment. The light source module 1D shown in FIG. 12 is a light source module of the fourth embodiment. Condensation lens 50-52 in Le 1C is replaced with Fresnel lens 60-62

FIG. 13 shows a light source module according to another embodiment (2) obtained by modifying a part of the fourth embodiment. The light source module 1E shown in FIG. 13 is different from the light source module 1D shown in FIG. 12 in that a Fresnel lens 63 is provided on the surface of the upper prism 6 where additive color mixture light is emitted. The light condensing function is realized by being distributed to the Fresnel lens 60 to 62 and the Fresnel lens 63. At this time, the Fresnel lens 63 is not necessarily a condensing lens (or convex lens), and may be a diverging lens (or concave lens) depending on the usage.

[0073] (E) Other embodiments

In the above embodiments, the three primary colors are red, green, and blue. However, any three independent colors on the chromaticity coordinates may be applied to the three primary colors. The present invention can also be applied to a light source module that additively mixes four or more primary colors (for example, the method shown in FIG. 14 described later can be expanded to add and mix four or more primary colors).

[0074] Further, in each of the above embodiments, for additive color mixing, the straight light from the red LED or the blue LED is emitted from the green LED, indicating that the light emitted from the green LED goes straight by the X-type dichroic prism. Even if it is made to be light, it is good. In other words, the arrangement of the LEDs 2R, 2G, and 2B is not limited to that of each of the above embodiments.

In each of the above embodiments, the optical device that additively mixes the light from the three primary color LEDs may be another optical device having a force S and a dichroic mirror indicating that it is an X-type dichroic prism. . For example, as shown in FIG. 14, an optical device in which three optical elements having dichroic mirror surfaces are arranged in parallel may be used. However, the part that functions as a dichroic mirror is an airtight space defined by a parallel plane, and at least one of the parallel planes is provided with a sub-wavelength grating that functions as a dichroic mirror. This is necessary (for example, see FIG. 1 (B) of JP-A-2006-13127).

Industrial applicability

[0076] The light source module of the present invention can be used, for example, as an automobile headlight, a backlight of a liquid crystal panel for image display, indoor lighting, an illumination light source in a measuring device, and the like. Also Since an arbitrary chromaticity can be realized, it is suitable for an apparatus that desires an arbitrary chromaticity such as an illumination light source in a measuring apparatus.

Claims

The scope of the claims

[1] A light source module having at least three primary color LEDs and an optical device including a dichroic mirror that additively mixes light from each of the LEDs.

The light source characterized in that the surface portion functioning as the dichroic mirror has an airtight space defined by a parallel plane having a predetermined gap, and a sub-wavelength grating provided on at least one plane of the airtight space. module.

[2] The optical device is an X-type dichroic prism, the three primary color LEDs are a red LED, a green LED, and a blue LED, and the light reflecting surface on the X surface of the X-type dichroic prism is positioned. A predetermined gap is formed airtight from the environment in the portion where the red light from the red LED is reflected and the first surface that transmits the other light is on the same surface including different prism surfaces. The second surface that is formed and reflects the blue light from the blue LED and transmits the other light is also formed on the same surface that includes a different prism surface and is orthogonal to the first surface. A sub-wavelength grating that selectively reflects the red light is formed, and a sub-wavelength grating that selectively reflects the blue light is formed on the second surface, and is emitted from the three primary color LEDs. On the same optical axis in the X-type dichroic prism. The light source module according to claim 1, characterized in that is emitted by additive color mixing.