JP4769620B2 - Light source module - Google Patents

Description

  The present invention relates to a light source module, and is particularly applicable to a light source module having at least three primary color LEDs (Light-Emitting Diodes) and an X-type dichroic prism.

  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 emitted light from three primary color LEDs has been proposed in order to realize an image with higher color purity. Yes. Here, by using three independent colors on the chromaticity coordinates, any color within the range of the color triangle formed by these three colors can be expressed, and the three primary colors are such 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, four primary colors obtained by mixing these three colors with yellow may be used. is there.

  As a light source module (LED module) that obtains white light from light emitted from 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 reflection surface of the dichroic mirror intersects in an X shape. A triangular prism that combines and emits three primary colors has been proposed (see Patent Document 1).

On the other hand, as a dichroic mirror, a dielectric multilayer film mirror in which high-refractive-index dielectric thin films and low-refractive-index dielectric thin films are alternately laminated at a predetermined film thickness, or a period having a period of about 1/10 of the wavelength. A sub-wavelength grating mirror by forming a grating (convex portion) at a predetermined pitch is known.
JP 2005-183005 A

  Conventional X-type dichroic prisms are usually formed by forming a dielectric multilayer mirror on a glass or plastic right-angle plane processed into a triangular prism, and bonding the dielectric multilayer mirror surface with an optical adhesive. It is. Dielectric multilayer films are formed by laminating many films on a substrate by vacuum evaporation or sputtering, so that the film formation time (man-hours) becomes long and expensive, and an X-type dichroic prism using the same However, the manufacturing man-hour is long and expensive.

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

  The present invention provides a light source module having at least three primary color LEDs and an optical device including a dichroic mirror that additively mixes light from the LEDs, and a surface portion functioning as the dichroic mirror has a parallel gap having a predetermined gap. It has an airtight space defined by a plane, and a subwavelength grating provided on at least one plane of the airtight space.

  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 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 is reflected from the red LED, and the first surface that transmits the other light is formed on the same surface including different prism surfaces. The second surface that 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 red light is formed, and a sub-wavelength grating that selectively reflects blue light is formed on the second surface, so that it is emitted from the three primary color LEDs. Make Door is preferable.

  According to the present invention, it is possible to provide an inexpensive light source module with reduced manufacturing steps.

(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 the first embodiment, and shows a section of an X-type dichroic prism. Although the light source module does not have the concept of up, down, left, and right, below, for convenience of explanation, up, down, left, and right are expressed 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.

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

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

  The first side prism 4 has a prism shape of a substantially right isosceles triangle with a right angle positioned to the right, and a protruding portion on the left side of the base prism 3 and a protruding portion extending to the left for joining on the upper surface thereof. have. The protruding portion on the left side of the base prism 3 and the protruding portion of the first side prism 4 are bonded by an optical adhesive to constitute a bonded portion 10.

  The projecting portion of the first side prism 4 has a stepped shape, and an end portion of the printed wiring board 7 on which the red LED 2R is mounted is placed and bonded on the upper surface. The red LED 2R is located at the center of the bottom side of the first side prism 4, and the direction of the light emitted from the red LED 2R is at the right-angled apex of the right isosceles triangular prism in the first side prism 4. It is the direction to go.

  The second side prism 5 is a prism having a substantially right isosceles triangular shape with a right angle located on the left side, and a protruding portion on the right side of the base prism 3 and a protruding portion extending to the right for joining on the upper surface thereof. have. 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.

  The projecting portion of the second side prism 5 has a stepped shape, and an end portion of the printed wiring board 9 on which the blue LED 2B is mounted is placed and bonded on the upper surface. The blue LED 2B is positioned at the center of the bottom side of the second side prism 5, and the direction of the light emitted from the blue LED 2B is at the right-angled apex of the right isosceles triangular prism in the second side prism 5. It is the direction to go.

  The upper prism 6 is a prism having a substantially right isosceles triangle 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 bonded by an optical adhesive. 13 is configured.

  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 made equal. Yes.

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

  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.

  The two sub-wavelength gratings 22A provided on the two planes extending in the upper right direction from the center reflect the red light emitted from the red LED 2R, and light of other colors emitted from the green LED 2G and the blue LED 2B. Is transparent. Similarly, the two sub-wavelength gratings 22A provided on the two planes extending in the lower left direction from the center similarly reflect the red light emitted from the red LED 2R and other colors emitted from the green LED 2G and the blue LED 2B. The light is transmitted.

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

  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 p in FIG. 4 described later) Is about 400 nm, the grating width (see d in FIG. 4 described later) is about 310 nm, and the grating height (see h in FIG. 4 described later) is about 220 nm. Further, for example, when a sub-wavelength grating that reflects a light beam emitted from the blue LED 2B (having a wavelength of 450 nm) is made of polycarbonate, the pitch of the grating (projection) is about 440 nm and the grating width is about 220 nm. The lattice height may be about 220 nm.

  In FIG. 1, the green LED 2G is provided at a position where the green light emitted from the green LED 2G is transmitted without being reflected, but the arrangement of the three primary colors LEDs 2R, 2G, and 2B is limited to this. It is not a thing. If the sub-wavelength grating that reflects the green light emitted from the green LED 2G 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.

  Although not shown in FIGS. 1 and 2, as shown in FIG. 3, the joint 20 (10 to 13) has a protrusion or protrusion provided on one surface thereof and the other. It is preferable to provide the fitting part 23 which consists of a recessed part or a recessed strip provided on the surface of the prism so that the prisms 3 to 6 can be appropriately positioned. When the fitting part 23 consists of a protrusion and a recess, it has contributed also to the airtight improvement.

  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 to the substrate 2. Second, when the base material is a polymer base material, the sub-wavelength grating 22 is produced by direct processing on the base material by irradiating with an ion beam or using a photo fine processing technique. To do. The second production method includes a case where the unevenness of the sub-wavelength grating 22 is directly produced on the surface of the base material using a mold. Third, the sub-wavelength grating 22 is produced 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 subwavelength grating 22, and the semiconductor substrate on which the subwavelength 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, the sub-wavelength grating 22 manufactured using a mold is shown. 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. 4. 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 protrusions is perpendicular to the sub-wavelength grating forming surface.

  In the light source module 1 of the first embodiment, the red light emitted from the red LED 2R is changed into light that is reflected upward by the sub-wavelength grating 22A extending from the center to the upper right and lower left from the center. Is done. 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 LED 2R includes a wavelength component other than the desired red component. It is supposed to be.

  Further, the blue light emitted from the blue LED 2B is reflected by the sub-wavelength grating 22B extending from the center to the upper left and the lower right from the center, and is changed to light directed upward. Even if the light emitted from the blue LED 2B includes a wavelength component other than the desired blue component, the sub-wavelength grating 22B extended to the upper left and lower right includes only the wavelength component (wavelength band) of the desired blue component. It is a reflection.

  Further, the upward green light emitted from the green LED 2G is transmitted through the sub-wavelength gratings 22A and 22B positioned in the traveling direction in the airtight space 14 as they are and is directed upward, and the light source module of the first embodiment. 1 is emitted. Each sub-wavelength grating 22A, 22B passes only the wavelength component (wavelength band) of the desired green component even if the upward light emitted from the green LED 2G includes a wavelength component other than the desired green component. It may be something to let you.

  As described above, the light emitted from the three primary colors LEDs 2R, 2G, and 2B is additively mixed with the X-type dichroic prism in the light source module 1 of the first embodiment in a state where the optical axes are substantially aligned, and white As an illumination light, an illuminated object (not shown) is illuminated.

  In the light source module 1 of the first embodiment, although not shown in the drawings, light quantity control means for electrically controlling the emitted light quantity from each LED 2R, 2G, 2B is mounted on the printed wiring boards 8, 9, 10. In addition, it is provided externally, and 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. Each of the LEDs 2R, 2G, and 2B may include a photodiode as a photodetector for detecting the light amount, and the detected light amount may be fed back to the light amount control means.

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

  (1) Since the functional layer for performing multiplexing as a dichroic mirror is formed with a sub-wavelength grating instead of a dielectric multilayer film, it is possible to omit the time-consuming film forming process, which facilitates manufacturing, 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. That is, 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, but is provided in an airtight space. Therefore, damage can be prevented, and adhesion of water or oil can be prevented, and a highly reliable functional film can be obtained.

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

  FIG. 7 shows a spectrum when a white phosphor is arranged on the optical path of light from a blue LED to achieve white. In FIG. 6, point A indicates the chromaticity of the blue LED, and point B indicates the chromaticity at the peak position of the light excited by the yellow phosphor. Therefore, 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 or adjusting the amount of yellow phosphor applied. However, as can be seen from the white LED spectrum obtained by combining the blue LED and the yellow phosphor shown in FIG. 7, the white light actually contains a red component and a green component. Therefore, it is possible to reproduce substantially the range of colors indicated by the color triangle ACD in FIG.

  On the other hand, as in the first embodiment, the color triangle obtained by additive color mixing of the emitted light from the three primary colors of red LED 2R, green LED 2G and blue LED 2B is the color purity of the light from each LED 2R, 2G, 2B. Is extremely high, a large color triangle AEF as shown in FIG. 6 is obtained, and a wide range of color reproduction is possible.

  Therefore, by adjusting the additive color mixture ratio of light from the three primary color light sources (LEDs), the emitted light of arbitrary chromaticity within the triangle AEF can be emitted from the light source module 1 of the first embodiment, and the illumination light The variety of colors is high.

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

  (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.

(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, and is a drawing corresponding to FIG. 1 according to the first embodiment. A reference numeral is attached.

  In the light source module 1 </ b> A of the second embodiment shown in FIG. 8, a fitting receiving portion made of, for example, a cylindrical hole is provided at the center of the bottom surface of the base prism 3, the first side prism 4, and the second side prism 5. 3H, 4H, and 5H are provided, and any of the corresponding LEDs 2G, 2R, and 2B are fitted to the fitting receiving portions 3H, 4H, and 5H. By doing so, the respective LEDs 2G, 2R, 2B are inserted into the corresponding fitting receiving portions 3H, 4H, 5H and bonded and fixed, whereby the positions and the emission angles of the respective LEDs 2G, 2R, 2B in the optical axis direction. It becomes possible to carry out easily.

  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 left-right direction in FIG. 9 corresponds to the normal direction of the paper surface in FIG.

  The LED 30 seals the LED chip 31, the wire 33 of the flexible printed wiring board 32 (7 to 9) and the LED chip 31, the LED chip 31 and the wire 34, and exhibits a lens function. And a sealing lens 35. 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. It has a nice lens shape. The sealing lens 35 is omitted when the emitted light from the LED chip 31 is small or when each prism (3 to 6) has a condensing lens as in the embodiment described later. Can do. The support base on which the LED chip 31 is placed 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 to an appropriate position on the optical axis.

  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 light source of the first embodiment. Similar to module 1.

  According to the second embodiment, the same effect as that of the first embodiment can be obtained. 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. Further, the optical coupling between the three primary color LEDs and the X-type dichroic prism is easy.

(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. A reference numeral is attached.

  In the light source module 1B of the third embodiment shown in FIG. 10, the red LED 2R is provided so that the emitted light travels upward, and the light from the red LED 2R travels to the first side prism 4. A first auxiliary prism 40 that changes the direction from the upper side to the right side is integrally provided. Further, 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 upper side to the left side 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 respective LEDs 2R, 2G, and 2B to the X-shaped center are equal.

  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 provided on the projecting portion of the base prism 3. However, it is needless to say that it may be provided on the same mating member as in FIG.

  Regarding the airtight space 14 and the sub-wavelength grating provided in the airtight space 14 (omitted in FIG. 8; refer to 22A and 22B in FIG. 3), the light source module 1B of the third embodiment is also the light source of the first embodiment. Similar to module 1.

  According to the third embodiment, the same effect as that of the first embodiment can be obtained. 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 board having the same configuration is applied to the printed wiring boards 7 to 9 for the respective color components. It is possible to make it possible.

  In addition, 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 so that the design is flexible. It becomes possible to. 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).

  Furthermore, with the arrangement as in the third embodiment, adjustment of the optical axis direction of each LED 2R, 2G, 2B becomes unnecessary, and the optical axis adjustment of each LED 2R, 2G, 2B becomes easy.

(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, corresponding to FIG. 10 according to the third embodiment, the same as FIG. A reference numeral is attached.

  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, and the red LED 2R A condenser lens (first condenser lens) 51 that condenses the emitted light from the blue LED 2B is provided integrally with the first side prism 4, and a condenser lens (second condenser lens) that condenses the emitted light from the blue LED 2B. 52 is provided integrally with the second side prism 5.

  In addition, the shape of each prism 3, 4, 5 etc. is ensured 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. Is selected.

  According to the fourth embodiment, the same effect as that of the third embodiment can be obtained. According to the fourth embodiment, since the condenser lens is provided so that the light from each LED is parallel light (or divergent light close thereto), additive color mixing can be executed more appropriately.

  In addition, the dichroic mirror characteristics 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 dichroic mirror can be reduced. Can be performed only on 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. A light source module 1D illustrated in FIG. 12 is obtained by replacing the condenser lenses 50 to 52 in the light source module 1C of the fourth embodiment with Fresnel lenses 60 to 62.

  FIG. 13 shows a light source module according to another embodiment (2) in which a part of the fourth embodiment is modified. 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 also provided on the surface of the upper prism 6 where additive color mixture light is emitted. The light condensing function is realized by being dispersed in the Fresnel lenses 60 to 62 and the Fresnel lens 63. At this time, the Fresnel lens 63 is not necessarily a condensing lens (or a convex lens), and may be a diverging lens (or a concave lens) depending on the usage.

(E) Other Embodiments Although not mentioned in the description of each of the above embodiments, the light source module of each embodiment includes, for example, an automobile headlight, a backlight of a liquid crystal panel for image display, indoor lighting, and a measuring device. It can be used as an illumination light source. As mentioned in the effect of the first embodiment, since arbitrary chromaticity can be realized, it is suitable for an apparatus that desires arbitrary chromaticity such as an illumination light source in a measuring apparatus.

  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).

  Further, in each of the above embodiments, for the additive color mixture, the light emitted from the green LED is caused to go straight by the X-type dichroic prism, but the straight light is taken as light emitted from the red LED or blue LED. You may do it. 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 is an X-type dichroic prism, but another optical device having a dichroic mirror may be used. For example, an optical device as shown in FIG. 14 in which three optical elements having a dichroic mirror surface are arranged in parallel may be used. However, the portion that functions as a dichroic mirror is an airtight space defined by a parallel plane, and at least one of the parallel planes is required to have a sub-wavelength grating that functions as a dichroic mirror (for example, (See FIG. 1B of Japanese Patent Laid-Open No. 2006-13127).

It is a schematic sectional drawing which shows the structure of the light source module which concerns on 1st Embodiment. It is a perspective view which shows the 2nd side prism of 1st Embodiment. It is an expanded sectional view around the airtight space in the first embodiment. It is an expanded sectional view of the surface of the subwavelength grating concerning a 1st embodiment. It is drawing used for description of the additive color mixing method in the first embodiment. It is a CIE chromaticity diagram for explaining the effect of the light source module according to the first embodiment. It is a drawing for explaining a conventional method of forming white light. It is a schematic sectional drawing which shows the structure of the light source module which concerns on 2nd Embodiment. It is a schematic sectional drawing which shows the detailed structure of LED in 2nd Embodiment. It is a schematic sectional drawing which shows the structure of the light source module which concerns on 3rd Embodiment. It is a schematic sectional drawing which shows the structure of the light source module which concerns on 4th Embodiment. It is a schematic sectional drawing which shows the structure of other embodiment (1) which deform | transformed 4th Embodiment. It is a schematic sectional drawing which shows the structure of other embodiment (2) which deform | transformed 4th Embodiment. It is a schematic sectional drawing which shows the additive color mixing structure in the light source module which concerns on other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A-1E ... Light source module, 2R ... Red LED, 2G ... Green LED, 2B ... Blue LED, 3 ... Base prism, 4 ... 1st side prism, 5 ... 2nd side prism, 6 ... Upper prism, 7- DESCRIPTION OF SYMBOLS 9 ... Flexible printed wiring board (FPC), 10-13, 20 ... Joint part, 14 ... Airtight space, 21 ... Recessed part, 22, 22A, 22B ... Sub wavelength grating, 40, 41 ... Auxiliary prism, 50-52 ... Condensing lens, 60-63 ... Fresnel lens.

Claims (2)

In 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 module, wherein 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. . 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 a portion where a light reflecting surface on the X surface of the X-type dichroic prism is located is predetermined. The first surface that reflects the red light from the red LED and transmits the other light is formed on the same surface including a different prism surface, and is formed from the blue LED. The second surface that reflects the blue light and transmits the other light is also formed on the same surface orthogonal to the first surface including different prism surfaces, and the red light is selectively applied to the first surface. A reflective sub-wavelength grating is formed, and the second surface is formed with a sub-wavelength grating that selectively reflects the blue light,
2. The light source module according to claim 1, wherein light emitted from the three primary color LEDs is additively mixed and emitted on substantially the same optical axis by the X-type dichroic prism.

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