国民经济行业分类号：
C4350 | C3874 | C4090 | C3879
当前申请(专利权)人：
SHARP KABUSHIKI KAISHA
原始申请(专利权)人：
SUMITANI, KEN
当前申请(专利权)人地址：
22-22, NAGAIKE-CHO, ABENO-KU, 545-8522, OSAKA-SHI, OSAKA, JAPAN
摘要：
A light source module includes: a light source; a lighting curtain that partially blocks light from the light source; and a reflective layer that is provided on the lighting curtain and that has a planar shape smaller than the lighting curtain.
技术问题语段：
However, when the CCFL is used as the light source of the light source module, the brightness of light emitted and the life are unsatisfactory.|Furthermore, disadvantageously, the brightness on a low voltage side is decreased, and thus it is difficult to achieve uniform light emission.|However, the lighting curtains disclosed in patent documents 1 to 3 do not always have their sufficient blocking ability.|Hence, when the lighting curtains disclosed in patent documents 1 to 3 are used in the conventional light source modules, the blocking ability is not sufficient, and thus an excessive amount of light passes through portions that need to block the light.|However, in this case, the increased thickness of the lighting curtain disadvantageously causes the thickness of the light source module to be increased.|Since the increased thickness of the reflective plate (the lighting curtain) makes it difficult to process the opening, it is disadvantageously difficult to obtain the lighting curtain (light source module) that can effectively reduce variations in brightness.|As disclosed in patent document 4, when a plurality of lighting curtains are stacked, it is possible to acquire a high blocking ability; however, even in this case, since the thickness of the lighting curtain is increased, the thickness of the light source module is disadvantageously increased.|Moreover, in this case, problems such as the displacement of positions between the lighting curtains and the increased number of assembly steps are newly produced.|Hence, the lighting curtains disclosed in patent documents 3 and 4 do not sufficiently function as solutions.|As described above, in the conventional light source module, when a light source having a high directivity is used or when the thickness of the module is reduced, it is disadvantageously difficult to obtain uniform illumination light.|In the conventional light source module, when a light source having a high directivity is used in order to obtain uniform illumination light, it is also disadvantageously difficult to reduce the thickness of the module.
技术功效语段：
[0022]The present invention is made to overcome the above problems; an object of the present invention is to provide a light source module that can illuminate a member to be illuminated without variations in brightness even when a light source having a high directivity is used or even when the thickness of the module is reduced.
[0023]Another object of the present invention is to provide a light source module that can emit, even when a light source having a high directivity is used, uniform illumination light having variations in brightness reduced while reducing the thickness of the module.
[0024]Yet another object of the present invention is to provide an optical member that has a sufficient blocking ability and that can improve the uniformity of light.
权利要求：
1. A light source module comprising:
a light source;
a lighting curtain that partially blocks light from the light source; and
a reflective layer that is provided on the lighting curtain and that has a planar shape smaller than the lighting curtain.
2. The light source module of claim 1,
wherein the lighting curtain is formed with a reflective plate in which a transmission portion is formed by an opening.
3. The light source module of claim 2,
wherein an opening hole is provided in the reflective layer so as to cover the opening of the lighting curtain.
4. The light source module of claim 3,
wherein the reflective layer is fixed to the lighting curtain through an adhesion layer, and the adhesion layer is provided in an area in which the adhesion layer is prevented from covering the opening hole of the reflective layer.
5. The light source module of claim 2,
wherein at least part of the opening of the lighting curtain is covered by the reflective layer.
6. The light source module of claim 1,
wherein the lighting curtain is formed with a plate-shaped member in which a transmission portion and a light blocking portion are provided by printing a reflective material.
7. The light source module of claim 6,
wherein the lighting curtain includes:
a transparent plate; and
a print layer that is formed by printing the reflective material on both surfaces of the transparent plate.
8. The light source module of claim 1,
wherein the reflective layer is formed into a separate sheet shape, and the sheet-shaped reflective layer is fixed to the lighting curtain through an adhesion layer,
9. The light source module of claim 8,
wherein the adhesion layer is formed by printing an adhesion material on the sheet-shaped reflective layer.
10. The light source module of claim 8,
wherein the adhesion layer is formed by printing an adhesion material on the lighting curtain.
11. The light source module of claim 8,
wherein the adhesion layer has ultraviolet radiation resistance.
12. The light source module of claim 8,
wherein the adhesion layer is transparent.
13. The light source module of claim 8,
wherein the adhesion layer is white.
14. The light source module of claim 8,
wherein the sheet-shaped reflective layer is fixed to the lighting curtain with a double-faced tape having the adhesion layer.
15. The light source module of claim 14,
wherein the double-faced tape includes a white base material.
16. The light source module of claim 14,
wherein the double-faced tape includes a transparent base material.
17. The light source module of claim 14,
wherein the double-faced tape includes no base material.
18. The light source module of claim 1,
wherein the reflective layer is formed with a first reflective member in which a reflective material is printed on a base material.
19. The light source module of claim 1,
wherein the reflective layer is formed with a second reflective member in which a reflective material is printed on a formed reflective sheet.
20. The light source module of claim 1,
wherein the light source is arranged on a side of one surface of the lighting curtain, and the reflective layer is provided on the surface of the lighting curtain on a side of the light source.
21. The light source module of claim 1,
wherein the light source is arranged on a side of one surface of the lighting curtain, and the reflective layer is provided on a surface of the lighting curtain opposite the surface on a side of the light source.
22. The light source module of claim 1,
wherein the light source is arranged on a side of one surface of the lighting curtain, and the reflective layer is provided on both the surface of the lighting curtain on a side of the light source and a surface opposite the surface on the side of the light source.
23. The light source module of claim 1,
wherein the reflective layer includes:
a first reflective layer that is fixed to the lighting curtain; and
a second reflective layer that has a planar shape smaller than the first reflective layer and that is fixed to the first reflective layer.
24. The light source module of claim 1,
wherein the reflective layer is substantially circular when seen in plan view.
25. The light source module of claim 1,
wherein the reflective layer is substantially quadrangular when seen in plan view.
26. The light source module of claim 1,
wherein the reflective layer has a thickness smaller than the lighting curtain.
27. The light source module of claim 2,
wherein the reflective layer is formed and fixed onto the lighting curtain by printing.
28. The light source module of claim 27,
wherein the reflective layer is formed with a white ink.
29. The light source module of claim 28,
wherein the reflective layer is formed with a metallic ink.
30. The light source module of claim 1,
wherein at least part of the reflective layer is scaled with a sealant.
31. The light source module of claim 1,
wherein the light source is formed with a light-emitting diode.
32. The light source module of claim 1, comprising:
a plurality of the light sources.
33. An optical member comprising:
a lighting curtain that partially blocks light; and
a reflective layer that is provided on the lighting curtain and that has a planar shape smaller than the lighting curtain.
背景技术：
[0002]1. Field of the Invention
[0003]The present invention relates to a light source module and an optical member that is used in the light source module.
[0004]2. Description of the Related Art
[0005]Conventionally, there is known a light source module that generates planar illumination light and that illuminates a member to be illuminated; the light source module is used as a backlight unit arranged in a liquid crystal display device or the like (for example, see patent document 1).
[0006]Conventionally, as a light source of the light source module, a CCFL (cold cathode fluorescent lamp) that seals mercury or xenon in a fluorescent lamp or the like is mainly used. However, when the CCFL is used as the light source of the light source module, the brightness of light emitted and the life are unsatisfactory. Furthermore, disadvantageously, the brightness on a low voltage side is decreased, and thus it is difficult to achieve uniform light emission. Hence, in order to eliminate such a disadvantage, instead of the CCFL, a light source module that uses an LED (light-emitting diode) package as a light source is proposed.
[0007]An example of the configuration of the conventionally proposed light source module will be described briefly below with reference to FIG. 43.
[0008]In the conventionally proposed light source module, as shown in FIG. 43, a plurality of LED packages 720 that are a light source are held within an enclosure 710 having an opening for light emission. Within the enclosure 710, a reflective sheet 730 that reflects light is also held. In the reflective sheet 730, exposure holes are formed, and the LED packages 720 are exposed (protrude) through the exposure holes.
[0009]A lighting curtain 740 is attached to the opening of the enclosure 710; the lighting curtain 740 blocks the opening of the enclosure 710. On the predetermined surface (the surface opposite the surface facing the LED packages 720) of the lighting curtain 740, a diffusion plate 750 that diffuses light is arranged.
[0010]The intensity of light that is emitted from the LED packages 720 and that is incident on the lighting curtain 740 depends on portions of the lighting curtain 740. Hence, processing for reducing the amount of light transmitted is performed on the portions of the lighting curtain 740 on which a large amount of light is incident. On the other hand, processing for increasing the amount of light transmitted is performed on the portions of the lighting curtain 740 on which a small amount of light is incident. Thus, variations in brightness are unlikely to be produced in planar light emitted from the lighting curtain 740. The light emitted from the predetermined surface of the lighting curtain 740 is diffused by the diffusion plate 750, and thereafter illuminates, as illumination light, a member to be illuminated.
[0011]As a method of configuring a lighting curtain such that the amount of light transmitted depends on its portions, various methods are known. For example, in patent document 2, a lighting curtain is formed with a transparent plate to which a reflective material is applied, and the transmittance is adjusted by the pattern of the application of the reflective member. Moreover, in patent document 3, a lighting curtain is formed with a reflective plate having an opening, and the transmittance is adjusted by the opening. Furthermore, as a method similar to that of patent document 2, patent document 4 discloses a configuration in which, instead of the transparent plate of patent document 2, a diffusion plate is used. In patent document 4, a plurality of lighting curtains are used such that they are stacked.
[0012]Patent document 1: JP-A-64-72193
[0013]Patent document 2: JP-A-2010-192301
[0014]Patent document 3: JP-A-2009-110696
[0015]Patent document 4: JP-A-2002-313103
[0016]When LED packages are used as the light source of a light source module, since the LED packages serving as the light source have high directivity as compared with a CCFL, a larger amount of light is concentrated in an area substantially directly above the light source. This tendency becomes greater as the thickness of the light module is reduced. In other words, the thickness of the light source module is reduced, and thus the light having a higher intensity is applied to the area substantially directly above the light source. When, as described above, a significantly large amount of light is applied to a specific portion of the lighting curtain, the lighting curtain is required to have the ability to sufficiently block the light.
[0017]However, the lighting curtains disclosed in patent documents 1 to 3 do not always have their sufficient blocking ability. Hence, when the lighting curtains disclosed in patent documents 1 to 3 are used in the conventional light source modules, the blocking ability is not sufficient, and thus an excessive amount of light passes through portions that need to block the light. Therefore, since the excessive amount of light passes through the portions and thus the portions become bright, variations in brightness are produced in the planar illumination light.
[0018]In the lighting curtain disclosed in patent document 3, if the thickness of the reflective plate of the lighting curtain is increased, it is possible to acquire a high blocking ability. However, in this case, the increased thickness of the lighting curtain disadvantageously causes the thickness of the light source module to be increased. Since the increased thickness of the reflective plate (the lighting curtain) makes it difficult to process the opening, it is disadvantageously difficult to obtain the lighting curtain (light source module) that can effectively reduce variations in brightness.
[0019]As disclosed in patent document 4, when a plurality of lighting curtains are stacked, it is possible to acquire a high blocking ability; however, even in this case, since the thickness of the lighting curtain is increased, the thickness of the light source module is disadvantageously increased. Moreover, in this case, problems such as the displacement of positions between the lighting curtains and the increased number of assembly steps are newly produced. Hence, the lighting curtains disclosed in patent documents 3 and 4 do not sufficiently function as solutions.
[0020]As described above, in the conventional light source module, when a light source having a high directivity is used or when the thickness of the module is reduced, it is disadvantageously difficult to obtain uniform illumination light. In the conventional light source module, when a light source having a high directivity is used in order to obtain uniform illumination light, it is also disadvantageously difficult to reduce the thickness of the module.
[0021]Since, in particular, a liquid crystal television having a small thickness is desired, it is desirable to reduce the thickness of a light source module that is used as a backlight unit. However, the reduced thickness of the light source module causes variations in brightness to be more disadvantageously produced.
发明内容：
[0022]The present invention is made to overcome the above problems; an object of the present invention is to provide a light source module that can illuminate a member to be illuminated without variations in brightness even when a light source having a high directivity is used or even when the thickness of the module is reduced.
[0023]Another object of the present invention is to provide a light source module that can emit, even when a light source having a high directivity is used, uniform illumination light having variations in brightness reduced while reducing the thickness of the module.
[0024]Yet another object of the present invention is to provide an optical member that has a sufficient blocking ability and that can improve the uniformity of light.
[0025]To achieve the above objects, according to a first aspect of the present invention, there is provided a light source module including: a light source; a lighting curtain that partially blocks light from the light source; and a reflective layer that is provided on the lighting curtain and that has a planar shape smaller than the lighting curtain.
[0026]In the light source module of the first aspect, as described above, the reflective layer is provided on the lighting curtain such that, when a large amount of light is applied from the light source to an area of the lighting curtain, the light can be blocked by both the reflective layer and the lighting curtain. Hence, since a sufficient light blocking ability can be acquired, even when a large amount of light is applied remarkably to a specific portion of the lighting curtain, the light can be satisfactorily blocked. Thus, it is possible to make it unlikely that, even when a light source having a high directivity is used or even when the thickness of the module is reduced, variations in the brightness of the light (illumination light) that is emitted through the lighting curtain are produced.
[0027]In the first aspect, the reflective layer has a planar shape smaller than the lighting curtain, and thus it is possible to provide the reflective layer in only the area to which a large amount of light is applied from the light source. Thus, it is possible to reduce the increases in the material cost, the weight and the like as compared with the case where, in order for the light blocking ability of the lighting curtain to be enhanced, the thickness of the lighting curtain is increased or a plurality of lighting curtains are stacked. When the reflective sheet segments are provided in the lighting curtain, the thickness of the lighting curtain itself is not increased. Hence, it is also possible to prevent the thickness of the light source module from being increased due to the increase in the thickness of the lighting curtain.
[0028]As described above, in the light source module of the first aspect, even when a light source having a high directivity is used, it is possible to reduce the thickness of the module. Even in the configuration described above, it is possible to emit uniform illumination light having variations in brightness reduced.
[0029]Furthermore, in the first aspect, in the configuration described above, it is possible to enhance the light blocking ability without the use of a plurality of lighting curtains. Thus, it is possible to prevent disadvantages produced when a plurality of lighting curtains are used. For example, it is possible to eliminate the need to give consideration to the attachment of a plurality of lighting curtains and the positioning of the lighting curtains when the light source module is assembled. Consequently, it is possible to, for example, enhance the accuracy of attachment of the lighting curtain, reduce the cost in the attachment step and enhance the throughput in the attachment step.
[0030]In the light source module of the first aspect, as the lighting curtain, the lighting curtain formed with the reflective plate including the transmission portions formed by the openings can be used. The reflective layers are provided in the lighting curtain described above, and thus it is possible to acquire the light source module that can easily and uniformly illuminate a member to be illuminated.
[0031]Even in this case, an opening hole can be provided in the reflective layer so as to cover the opening of the lighting curtain. In the configuration described above, since a portion having a high light blocking ability can be arranged adjacently to the opening, it is possible to enhance the light blocking ability over the vicinity of the opening.
[0032]The reflective layer can be fixed to the lighting curtain through an adhesion layer. When the opening hole is provided in the reflective layer, the adhesion layer is preferably provided in an area in which the adhesion layer is prevented from covering the opening hole of the reflective layer.
[0033]When, as the lighting curtain, a lighting curtain formed with the reflective plate in which the transmission portion is formed by the opening is used, at least part of the opening of the lighting curtain may be covered by the reflective layer. In the configuration described above, it is possible to form, for example, an area which has an intermediate light blocking ability, that is, in which the light is transmitted through the lighting curtain but is reflected off the reflective layer. Thus, the flexibility of the design of the light source module can be enhanced.
[0034]In the light source module of the first aspect, the lighting curtain can also be formed with a plate-shaped member in which a transmission portion and a light blocking portion are provided by printing a reflective material. The reflective layers are provided in the lighting curtain described above, and thus it is possible to acquire the light source module that can easily and uniformly illuminate the member to be illuminated without unevenness.
[0035]In this case, the lighting curtain preferably includes: a transparent plate; and a print layer that is formed by printing the reflective material on both surfaces of the transparent plate. In the configuration described above, since the print layer is formed on both surfaces of the transparent plate, it is possible to enhance the light blocking ability of the lighting curtain. In this case, the printing pattern of the reflective material on each surface and the position and the shape of the reflective layer are more preferably set such that, among the light emitted from the light source, light that is emitted at such an angle that a predetermined amount or more of strength is acquired is applied either to the reflective material (the print layer) printed on any one of the surfaces of the transparent plate or to the reflective layer.
[0036]Preferably, in the light source module of the first aspect, the reflective layer is formed into a separate sheet shape, and the sheet-shaped reflective layer is fixed to the lighting curtain through an adhesion layer.
[0037]In this case, the adhesion layer may be formed by printing an adhesion material on the sheet-shaped reflective layer, and the adhesion layer may be formed by printing an adhesion material on the lighting curtain. The adhesion layer (the adhesion material) preferably has ultraviolet radiation resistance. Furthermore, the adhesion layer (the adhesion material) is preferably transparent or white.
[0038]The sheet-shaped reflective layer can be fixed to the lighting curtain with a double-faced tape having the adhesion layer. The double-faced tape may include a base material; the double-faced tape more preferably includes no base material. When the double-faced tape includes a base material, the base material is preferably transparent or white.
[0039]In the light source module of the first aspect, the reflective layer is preferably formed with a first reflective member in which a reflective material is printed on a base material. With this configuration, it is possible to form the light reflecting area (a reflective area on which the reflective material is printed) into a complicated pattern or a fine pattern. Hence, since the reflective material can be accurately applied to the area in which the light blocking characteristic needs to be enhanced, it is possible to easily enhance the light blocking characteristic of the area.
[0040]In the light source module of the first aspect, the reflective layer may be formed with a second reflective member in which a reflective material is printed on a formed reflective sheet. In this configuration, since the reflective layer is formed with the reflective sheet and the reflective material printed thereon, the reflective layer is formed of a plurality of layers. Hence, since it is possible to easily enhance the reflection ability of the reflective layer, it is possible to easily enhance the light blocking ability of the lighting curtain on which the reflective is provided.
[0041]In the light source module of the first aspect, the light source can be arranged on the side of one surface of the lighting curtain. In this case, the reflective layer may be provided on the surface of the lighting curtain on the side of the light source or on a surface of the lighting curtain opposite the surface on the side of the light source. The reflective layer may also be provided on both the surface of the lighting curtain on the side of the light source and the surface opposite the surface on the side of the light source.
[0042]In the light source module of the first aspect, the reflective layer preferably includes: a first reflective layer that is fixed to the lighting curtain; and a second reflective layer that has a planar shape smaller than the first reflective layer and that is fixed to the first reflective layer. With this configuration, it is possible to further enhance the light blocking ability.
[0043]Preferably, in the light source module of the first aspect, the reflective layer is substantially circular or substantially quadrangular when seen in plan view. Since, in this configuration, in the design of the shape of the reflective layer, a calculation for determination of the application to the reflective layer can be performed rapidly, the enhancement of efficiency of the design can be expected. When the thickness of the reflective layer is small, the thickness of the reflective layer is set at 0 (zero), and it is possible to perform the calculation effectively. Hence, the thickness of the reflective layer is preferably smaller than that of the lighting curtain.
[0044]When the lighting curtain is formed with the reflective plate in which the transmission portion is formed by the opening, the reflective layer is preferably formed and fixed onto the lighting curtain by printing. In this configuration, with simple means, it is possible to locally enhance the light blocking ability of the lighting curtain.
[0045]In this case, the reflective layer is preferably formed and fixed onto the lighting curtain by printing a white ink. As described above, the white ink is used for the printing, and thus variations in the color of the light that are thereafter produced can be reduced, with the result that the light blocking ability can be enhanced. The reflective layer may be formed and fixed by printing, for example, a metallic ink other than the white ink on the lighting curtain. When the metallic ink is used for the printing, even if the printing is performed such that its thickness is small (even if the thickness of the print layer is small), it is possible to acquire a high light blocking ability.
[0046]In the light source module of the first aspect, at least part of the reflective layer is preferably sealed with a sealant. With this configuration, it is possible to easily prevent the reflective layer from falling off.
[0047]In the light source module of the first aspect, the light source is preferably formed with a light-emitting diode.
[0048]The light source module of the first aspect preferably includes a plurality of the light sources.
[0049]An optical member of a second aspect of the present invention includes: a lighting curtain that partially blocks light; and a reflective layer that is provided on the lighting curtain and that has a planar shape smaller than the lighting curtain. In this configuration, since it is possible to enhance the light blocking ability in an area of the optical member, even if a large amount of light is applied to the area, it is possible to sufficiently block the light. Hence, when the optical member described above is used as the light source module, it is possible to enhance the uniformity of the light emitted from the light source module.
[0050]As described above, according to the present invention, it is possible to easily acquire a light source module that can illuminate a member to be illuminated without variations in brightness even when a light source having a high directivity is used or even when the thickness of the module is reduced.
[0051]According to the present invention, it is possible to easily acquire a light source module that can emit, even when a light source having a high directivity is used, uniform illumination light having variations in brightness reduced while reducing the thickness of the module.
[0052]According to the present invention, it is possible to easily acquire an optical member that has a sufficient blocking ability and that can improve the uniformity of light.
具体实施方式：
[0096]Embodiments of the present invention will be described in detail below with reference to accompanying drawings.
First Embodiment
[0097]FIG. 1 is a cross-sectional view of a light source module according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing an enlarged portion of FIG. 1. FIG. 3 is a perspective view schematically showing the light source module according to the first embodiment of the present invention. FIGS. 4 to 7 are diagrams illustrating the light source module according to the first embodiment of the present invention. The light source module according to the first embodiment of the present embodiment will first be described with reference to FIGS. 1 to 7.
[0098]As shown in FIGS. 1 to 3, the light source module 100 of the first embodiment is configured to include an enclosure 10, LED packages 20, a reflective sheet 30 and an optical member 40. The optical member 40 has a lighting curtain 50 and a plurality of reflective sheet segments 60 that are fixed to the lighting curtain 50. Above the lighting curtain 50, a diffusion plate 70 that diffuses light is arranged. The LED packages 20 are an example of a “light source” of the present invention; the reflective sheet segments 60 are an example of a “reflective layer.”
[0099]The enclosure 10 is a substantially box-shaped member having an opening 11 for light emission, and includes a bottom portion 12 and a side portion 13 that is provided around the perimeter of the bottom portion 12. This enclosure 10 is formed by processing, for example, a metallic plate-shaped member. The enclosure 10 holds the LED packages 20 and the reflective sheet 30 by placing them over its bottom surface. A region enclosed by the side portion 13 of the enclosure 10 is substantially rectangular; the substantially rectangular region is a holding region that holds the LED packages 20 and the reflective sheet 30.
[0100]The LED packages 20 serving as the light source are held within the enclosure 10 while being mounted on a mounting board (unillustrated). The mounting board is a plate-shaped and rectangular board; a plurality of electrodes are arranged on its mounting surface. Onto these electrodes, the LED packages 20 are attached. A plurality of LED packages 20 are mounted on the same mounting board and thus they are combined into modules.
[0101]The LED packages 20 are mounted on the electrodes formed on the mounting surface of the mounting board, and thereby receive electric current and emit light. As shown in FIG. 3, a plurality of LED packages serving as the light source are mounted in the holding region of the enclosure 10. These LED packages 20 are structured such that white light is emitted from the light emission surface of each of the LED packages 20. The LED packages 20 are arranged in the holding region of the enclosure 10 (on the bottom surface 12 of the enclosure 10) two-dimensionally (for example, in a lattice).
[0102]The LED packages 20 are a top view type. The LED packages of this type often have a high directivity toward an area directly above the LED packages 20. Hence, the light distribution characteristic of the LED packages 20 is assumed to be the same as that described above.
[0103]The structure of the LED package 20 is not particularly limited; for example, it is a combination of a fluorescent material that converts blue light into yellow light and a blue LED element. The LED package 20 may also be a combination of a fluorescent material that converts blue light into green light and red light and a blue LED element; the LED package 20 may also be a combination of three types of LED elements that are a red LED element, a green LED element and a blue LED element.
[0104]The reflective sheet 30 has the function of reflecting light; for example, it is formed by processing a sheet member formed of resin. The reflective sheet 30 includes a bottom portion 31 and a side portion 32 that is provided around the perimeter of the bottom portion 31. In the bottom portion 31 of the reflective sheet 30, a plurality of exposure holes 33 are provided. These exposure holes 33 are formed to correspond to the LED packages 20 that are arranged two-dimensionally.
[0105]As shown in FIGS. 2 to 4, the reflective sheet 30 is held together with the LED packages 20 in the holding region of the enclosure 10 such that part of the LED packages 20 is exposed (protrudes) through the exposure holes 33. Thus, the bottom surface 12 of the enclosure 10 and the mounting surface of the mounting board are covered with the bottom portion 31 of the reflective sheet 30, and the inside surface of the enclosure 10 is covered with the side portion 32 of the reflective sheet 30. Since the reflective sheet 30 is provided within the enclosure 10 in this way and thus light is reflected off the reflective sheet 30, the amount of light travelling toward a member to be illuminated is increased. Consequently, the efficiency of utilization of light is enhanced.
[0106]The lighting curtain 50 of the optical member 40 is attached to the opening portion of the enclosure 10 so as to block the opening 11. This lighting curtain 50 is attached to an area above the LED packages 20 so as to face the bottom surface 12 of the enclosure 10. Hence, when light is emitted from the LED packages 20, the light is incident on the lighting curtain 50. The lighting curtain 50 has the function of reducing variations in brightness by partially blocking the light from the LED packages 20.
[0107]In the first embodiment, the lighting curtain 50 is formed by providing a plurality of circular openings 52 in a plate-shaped member (reflective plate 51). Portions where the openings 52 are formed are transmission portions through which the light is transmitted; portions where the openings 52 are not provided are reflective portions off which the light is reflected. The openings 52 are distributed and arranged such that the openings 52 are not coupled to each other.
[0108]In the first embodiment, in order for the thickness of the light source module 100 to be reduced, the lighting curtain 50 is attached to a position at a height H1 (see FIG. 2) of, for example, about 3 mm from the bottom portion 12 (the bottom surface) of the enclosure 10.
[0109]In the LED packages 20 arranged within the enclosure 10, the center portion of the light emission surface thereof faces the member to be illuminated (the lighting curtain 50). Since the LED packages 20 emit light having a high intensity to an area directly above the LED packages 20, in the lighting curtain 50, a large amount of light is incident on the vicinity of the area directly above the LED packages 20 (an area including the area directly thereabove), and the amount of light is gradually decreased as the area on which light is incident is positioned farther away from the vicinity of the area directly thereabove. As described above, the intensity of light that is emitted from the LED packages 20 and that is then incident on the lighting curtain 50 differs depending on the portions of the lighting curtain 50. Hence, in the openings 52 of the lighting curtain 50, the aperture ratio is changed depending on portions where the openings 52 are formed, and the amount of light transmitted is adjusted by the openings 52. In other words, the sizes of the openings 52 (the areas of the openings) are not uniform, and are different depending on the positions where the openings 52 are arranged.
[0110]Specifically, the size of each of the openings 52 in the lighting curtain 50 is set such that, as the opening is positioned farther away from the vicinity of the area directly above the LED packages 20, its aperture ratio is gradually increased. In other words, the size of each of the openings 52 in the lighting curtain 50 is gradually increased as the opening is positioned farther away from the vicinity of the area directly above the LED packages 20. Furthermore, in the lighting curtain 50, portions to which a large amount of light is applied from the LED packages 20 (for example, the vicinity of the area directly above the LED packages 20) are not provided with the openings 52; the lighting curtain 50 is configured such that the light applied is reflected off those portions.
[0111]The distribution of the intensity of light that is incident on the lighting curtain 50 depends not only the light distribution characteristic of the LED packages 20 but also the shape, the size, the position of attachment and the like of the light source module (for example, the pitch of the LED packages 20 arranged and the space between the reflective sheet 30 and the lighting curtain 50). Hence, the openings 52 are formed such that a small amount of light passes through the portions of the lighting curtain 50 on which a large amount of light is incident. On the other hand, the openings 52 are formed such that a large amount of light passes through the portions of the lighting curtain 50 on which a small amount of light is incident.
[0112]The lighting curtain 50 is produced by forming, with press punching processing, a plurality of openings 52 in the reflective plate 51, for example, about 1 mm thick. The press punching processing is a production method that is effective for mass production because it has advantages over the running cost and the productivity. Instead of using the press punching processing, the process of the openings 52 can also be performed with means such as drilling processing or laser processing. The lighting curtain 50 can also be obtained such as by injection molding a resin having a high reflectance.
[0113]When a small amount of light is reflected off (a large amount of light is absorbed by) portions other than the openings 52 in the lighting curtain 50, even if variations in brightness is reduced, the brightness itself is reduced. Hence, the reflective plate 51 of the lighting curtain 50 is preferably formed of a reflective material having a high total reflectivity. Thus, the decrease in brightness is reduced. This type of material includes, for example, a slightly foamed PET (polyethylene terephthalate) resin. The reflective plate using a slightly foamed PET includes, for example, “MCPET” (registered trademark) made by Furukawa Electric Co., Ltd. The “MCPET” (registered trademark) made by Furukawa Electric Co., Ltd. is 1.0 mm thick and has a high total reflectivity (about 99%).
[0114]Here, in the first embodiment, the reflective sheet segments 60 that reflect the light are fixed to a predetermined region of the lighting curtain 50. As shown in FIGS. 1, 6 and 7, these reflective sheet segments 60 have a planar shape (a plane area) smaller than that of the lighting curtain 50.
[0115]The reflective sheet segments 60 are molded products that are obtained by processing the reflective sheet into a predetermined shape. As shown in FIGS. 2 and 5, the reflective sheet segments 60 are formed into the shape of a separate sheet, and are fixed to the lighting curtain 50 through an adhesion layer 80. Specifically, the reflective sheet segments 60 are fixed to the lighting curtain 50 with an adhesion material 80a of which the adhesion layer 80 is formed.
[0116]The reflective sheet segments 60 are attached to the portions of the lighting curtain 50 on which a large amount of light is incident. Then, by attaching the reflective sheet segments 60 to the lighting curtain 50, the light blocking ability of the lighting curtain 50 is partially enhanced.
[0117]As shown in FIGS. 5 to 7, in the first embodiment, each of the reflective sheet segments 60 is formed into a circular shape. As shown in FIGS. 1 and 2, the reflective sheet segments 60 are attached to the vicinity of the area directly above the LED packages 20 (the area including the area directly thereabove). The reflective sheet segments 60 are attached onto the surface (on the one surface) of the lighting curtain 50 on the side of the LED packages 20 such that the reflective sheet segments 60 are prevented from overlapping with the openings 52 of the lighting curtain 50. Specifically, the reflective sheet segments 60 are attached to areas which are in vicinity of the area directly above the LED packages 20 and in which the openings 52 are not fanned.
[0118]For example, the thickness of the reflective sheet segment 60 is preferably set at 50 μm to 400 μm, and is more preferably set at 100 μm to 200 μm. The thickness of the reflective sheet segments 60 differs depending on various conditions such as the material of the reflective sheet segments 60, the intensity of the light from the LED packages 20 and the distance from the LED packages 20 to the lighting curtain 50. Hence, the thickness of the reflective sheet segments 60 is preferably set at, in consideration of various conditions, a thickness having a predetermined characteristic.
[0119]The thickness of the reflective sheet segments 60 is preferably set smaller than that of the lighting curtain 50.
[0120]The reflective sheet of the reflective sheet segments 60 is not particularly limited; for example, a sheet formed of PET containing a reflective material, a sheet member onto which metal is evaporated or the like can be used.
[0121]Since the reflective sheet segments 60 are fixed with the adhesion material 80a to the lighting curtain 50, the adhesion layer 80 is present between the reflective sheet segments 60 and the lighting curtain 50. In this case, the light that has passed through the reflective sheet segments 60 reaches the adhesion layer 80 (the adhesion material 80a), and transmission and reflection are performed in the adhesion layer 80. Hence, since it is likely that the color of the adhesion layer 80 (the adhesion material 80a) affects the color of the resulting light, the adhesion layer 80 (the adhesion material 80a) is preferably white or transparent (colorless and transparent). The adhesion material 80a (the adhesion layer 80) is not particularly limited; for example, a milky white emulsion adhesive, a transparent epoxy adhesive or the like is preferably used. The adhesion material 80a (the adhesion layer 80) preferably has ultraviolet radiation resistance so that the change of its color and the decrease in its adhesion caused by ultraviolet radiation are reduced. This is easily achieved by using, for example, an adhesion material containing an ultraviolet absorption material. The adhesion material 80a (the adhesion layer 80) conceptually includes an adhesion material (adhesive layer).
[0122]The diffusion plate 70 is an optical sheet that overlaps the lighting curtain 50 and that diffuses the light received through the lighting curtain 50. The diffusion plate 70 is attached to an area above the lighting curtain 50 so as to block the opening 11 of the enclosure 10. The diffusion plate 70 is attached to a position at a height H2 of, for example, about 5 mm from the lighting curtain 50.
[0123]In the light source module 100 configured as described above and according to the first embodiment, when light is emitted from the LED packages 20, a large amount of light is incident on the vicinity of the area directly above the LED packages 20, but the amount of light that does not pass through the lighting curtain 50 and that is reflected toward the reflective sheet 30 is increased. On the other hand, in the portions other than the vicinity of the area directly above the LED packages 20 in the lighting curtain 50, as the portion is positioned farther away from the vicinity of the area directly thereabove, the amount of light incident thereon is reduced whereas, as the portion is positioned farther away from the vicinity of the area directly thereabove, the amount of light transmitted through the lighting curtain 50 (light passing through the openings 52) is gradually increased. Hence, the difference is reduced between the amount of light emitted from the vicinity of the area directly above the LED packages 20 in the lighting curtain 50 (the vicinity of the area directly thereabove including a portion directly thereabove and portions near the portion directly thereabove) and the amount of light emitted from portions separate from the vicinity of the area directly above the LED packages 20 in the lighting curtain 50. Thus, it is unlikely that variations in brightness are produced in planar light emitted from a predetermined surface (light-emitting surface) of the lighting curtain 50.
[0124]The planar light (the planar light that has had variations in brightness reduced) that has been emitted from the predetermined surface (light-emitting surface) of the lighting curtain 50 enters the diffusion plate 70. The planar light that has entered the diffusion plate 70 is further diffused and is emitted as planar light of high quality to the member to be illuminated.
[0125]As described above, since the directivity in the LED packages 20 toward the area directly thereabove (in the vertical direction) is high, a large amount of light is applied to the area directly above the LED packages 20 in the lighting curtain 50. In the first embodiment, since the reflective sheet segments 60 are attached to this area, the light blocking ability of this area is enhanced. In other words, in the first embodiment, in the lighting curtain 50 (the optical member 40), the light blocking ability of the area to which a large amount of light is applied is enhanced. Hence, even when the light blocking ability of the lighting curtain 50 is insufficient, the transmission of light through this area is reduced, with the result that variations in brightness are reduced.
[0126]The enhancement of the light blocking ability (the total light transmittance) of the area to which the reflective sheet segments 60 are attached will be simply calculated. For ease of calculation, the optical effects on the adhesion material 80a are ignored. The reflection of light is assumed to be all performed on the surface of a reflective material, and actions other than the reflection and the transmission of light are ignored. When it is assumed that the total light transmittance of the reflective sheet segments 60 is, for example, 5% and that the total light transmittance of the lighting curtain 50 is, for example, 1%, light that passes through both the reflective sheet segments 60 and the lighting curtain 50 is simply calculated to be 0.05%, with the result that the total light transmittance is extremely reduced to one-twentieth as compared with the case where only the lighting curtain 50 is used. Since the reflective sheet segments 60 are attached as described above, a high light blocking ability is achieved, and thus it is possible to effectively prevent variations in brightness even if a significant amount of light is applied to the predetermined area (small area).
[0127]Since the reflective sheet segments 60 are formed with the reflective sheet, they have the corresponding reflectivity. The light that has been reflected off the reflective sheet segments 60 is reflected several times off the reflective sheet 30, the lighting curtain 50 and the like, and then reaches the diffusion plate 70 through the openings 52 of the lighting curtain 50. Hence, much of light that cannot pass through the reflective sheet segments 60 and the lighting curtain 50 in the area directly above the LED packages 20 finally functions as the illumination light simply without loss thereof. Thus, the decrease in brightness is limited.
[0128]When the LED packages 20 are used as the light source, as compared with the case where a CCFL is used, a large amount of light is collected in the area directly above the light source. This tendency becomes greater as the thickness of the light source module is reduced. This point will be described in more detail with reference to FIGS. 8 to 11. FIGS. 8 and 9 are diagrams illustrating a light distribution characteristic when the CCFL is used as the light source. FIGS. 10 and 11 are diagrams illustrating a light distribution characteristic when the LED packages are used as the light source. FIGS. 9 and 11 are characteristic diagrams that indicate the intensity of light emitted at a certain angle as the relative intensity with respect to the case where the intensity of light emitted in the direction in which the maximum intensity is achieved is assumed to be 100%.
[0129]Since the CCFL that is conventionally used as the main light source is generally nondirectional, as shown in FIG. 9, its light distribution characteristic is of a line light source whose light distribution characteristic does not depend on the angle at which the light is emitted. When the light source is nondirectional, since the light is emitted at any angle such that the intensity is the same, the relative intensity is 100% even if the light is emitted at any angle. Here, for ease of description, consideration is given to only the components of light applied from the light source to the side of the lighting curtain 50.
[0130]For example, as shown in FIG. 8, on an illumination surface 530 a distance a (for example, 10 mm) away from the CCFL 510 that is the light source, light (since the CCFL 510 is a line light source, this application region is band-shaped) that is applied to positions within the distance a (for example, 10 mm) in the horizontal direction of the figure from the light source (the CCFL 510) is 25% of all light that has been applied. On an illumination surface 540 a distance b (for example, 5 mm) away from the light source, this is 35% of all light that has been applied.
[0131]A case where the LED packages are used as the light source will now be described. Although each of the LED packages has a unique light distribution characteristic, a case where the LED packages are a point light source having a light distribution characteristic corresponding to a Lambertian distribution and shown in FIG. 11 will be described here.
[0132]In the Lambertian distribution, when an angle with respect to the direction of the normal is assumed to be 0, the intensity of light emitted in the direction of the angle θ is proportional to cos θ. Hence, as compared with a nondirectional light source such as the CCFL, light is emitted such that the light is collected in the direction of the normal. In other words, the Lambertian distribution is the distribution of application of light that has a high directivity in the vertical direction.
[0133]As shown in FIG. 10, as in the case of the CCFL, on the illumination surface 530 the distance a (for example, 10 mm) away from a LED package 520 that is the light source, light (since the LED package 520 is a point light source, this application region is circular) that is applied to positions within the distance a (for example, 10 mm) in the horizontal direction of the figure from the light source (the LED package 520) is 50% of all light that has been applied. On the illumination surface 540 the distance b (for example, 5 mm) away from the light source, this is 80% of all light that has been applied.
[0134]As described above, when a light source such as the LED packages is used in which the directivity in the vertical direction (toward the area directly thereabove) is high, a large amount of light is collected in the area directly above the light source, and this tendency becomes greater as the thickness of the light source module is reduced. Hence, when the LED packages are used as the light source, if the thickness of the light source module is reduced, a large amount of light is applied remarkably to a specific portion of the lighting curtain. Thus, it is very difficult to reduce the thickness of the light source module while reducing variations in brightness.
[0135]However, since, as described above, the light source module 100 of the first embodiment includes the optical member 40 in which the reflective sheet segments 60 are attached to the lighting curtain 50, and thereby has a sufficient light blocking ability, even when a large amount of light is applied remarkably to a specific portion of the lighting curtain 50, variations in brightness are reduced. Thus, it is possible to reduce the thickness of the light source module 100 while reducing variations in brightness.
[0136]With the reflective sheet segments 60 attached to the lighting curtain 50, the lighting curtain 50 is subjected to the assembly of the light source module 100. Hence, in the assembly of the light source module 100, the lighting curtain 50 (the optical member 40) can be attached in a step similar to the conventional step. Hence, the number of assembly steps, the throughput, the cost and the like are equivalent to those in the conventional case. It is possible to easily attach the reflective sheet segments 60 by, for example, attaching a plurality of reflective sheet segments 60 at a time.
[0137]In the first embodiment, as described above, when the reflective sheet segments 60 are attached to the lighting curtain 50 and thus a large amount of light is applied from the light source (the LED packages 20) to an area of the lighting curtain 50, the light can be blocked both by the reflective sheet segments 60 and by the lighting curtain 50. Hence, since a sufficient light blocking ability can be obtained, even when a large amount of light is applied remarkably to a specific portion of the lighting curtain 50, the light can be sufficiently blocked. Thus, it is possible to make it unlikely that, even when a light source such as the LED packages 20 having a high directivity is used or even when the thickness of the module is reduced, variations in the brightness of the light (illumination light) that is emitted through the lighting curtain 50 are produced.
[0138]Moreover, in the first embodiment, the reflective sheet segments 60 are configured to have a planar shape (a plane area) smaller than that of the lighting curtain 50, and thus it is possible to provide the reflective sheet segments 60 in only an area to which a large amount of light is applied from the light source (the LED packages 20). Thus, it is possible to reduce the increases in the material cost, the weight and the like as compared with the case where, in order for the light blocking ability of the lighting curtain 50 to be enhanced, the thickness of the lighting curtain is increased or a plurality of lighting curtains are stacked. When the reflective sheet segments 60 are provided in the lighting curtain 50, the thickness of the lighting curtain itself is not increased. Hence, it is also possible to prevent the thickness of the light source module 100 from being increased due to the increase in the thickness of the lighting curtain 50.
[0139]As described above, in the first embodiment, even when the light source having a high directivity is used, it is possible to reduce the thickness of the light source module 100. Even in the configuration described above, it is possible to emit uniform illumination light having variations in brightness reduced.
[0140]Furthermore, in the first embodiment, in the configuration described above, it is possible to enhance the light blocking ability without the use of a plurality of lighting curtains. Thus, it is possible to prevent disadvantages produced when a plurality of lighting curtains are used. For example, it is possible to eliminate the need to give consideration to the attachment of a plurality of lighting curtains and the positioning of the lighting curtains when the light source module 100 is assembled. Consequently, it is possible to, for example, enhance the accuracy of attachment of the lighting curtain, reduce the cost in the attachment step and enhance the throughput in the attachment step.
[0141]Since, in the first embodiment, as the lighting curtain 50, the lighting curtain formed with the reflective plate 51 including the transmission portions produced by the openings 52 is used, the reflective sheet segments 60 are provided in the lighting curtain 50, and thus it is possible to acquire the light source module 100 that can easily and uniformly illuminate the member to be illuminated.
[0142]As shown in FIG. 3, for example, the light source module 100 described above can be used as a backlight unit 100 (a direct-type backlight unit) of a liquid crystal display device 300.
[0143]This liquid crystal display device 300 includes; a liquid crystal display panel 200 (the member to be illuminated); and the backlight unit 100 (the light source module 100) that provides light to the liquid crystal display panel 200. For example, the liquid crystal display panel 200 is configured by adhering, with a seal material (unillustrated), an active matrix substrate 201 including switching elements such as a TFT (thin film transistor) to an opposite substrate 202 opposite the active matrix substrate 201. Liquid crystal (unillustrated) is injected into a space between both the substrates 201 and 202. A polarization film 203 is attached to each of the side of the light receiving surface of the active matrix substrate 201 and the side of the light emitting surface of the opposite substrate 202.
[0144]The liquid crystal display panel 200 configured as described above utilizes changes in transmittance due to the inclination of the molecules of the liquid crystal, and thereby displays an image. Since, as the backlight 100 illuminating the liquid crystal display panel 200, the light source module 100 is used, it is possible to provide the liquid crystal display device 300 which has an excellent display function and whose thickness is thin
Second Embodiment
[0145]FIG. 12 is a cross-sectional view of a light source module according to a second embodiment of the present invention; FIG. 13 is a cross-sectional view showing an enlarged portion of FIG. 12. FIG. 14 is a perspective view of a reflective sheet segment of the light source module according to the second embodiment of the present invention; FIG. 15 is a plan view showing a portion of a lighting curtain in the light source module according to the second embodiment of the present invention. The light source module according to the second embodiment of the present invention will now be described with reference to FIGS. 12 to 15. In the drawings, the corresponding constituent components are identified with common symbols, and therefore their description will not be repeated as appropriate.
[0146]As shown in FIGS. 12 and 13, in the light source module 101 (100) of the second embodiment, the reflective sheet segments 61 (60) are configured to cover at least part of the openings 52 of the lighting curtain 50. In other words, in the second embodiment, the reflective sheet segments 61 are attached to the lighting curtain 50 such that the reflective sheet segments 61 covers at least part of the openings 52 of the lighting curtain 50.
[0147]In portions (portions covered by the reflective sheet segments 61) of a plurality of openings 52 provided in the lighting curtain 50 that are covered by the reflective sheet segments 61, light is blocked by only the reflective sheet segments 61. Hence, in these portions, the total light transmittance is low as compared with the openings 52, and the total light transmittance is high as compared with portions (areas) in which light is blocked by both the reflective sheet segments 61 and the lighting curtain 50. Therefore, the portions in which the openings 52 are covered by the reflective sheet segments 61 have an intermediate total light transmittance.
[0148]When the adhesion material 80a (see FIG. 14) is applied to the entire surface of the reflective sheet segments 61, the openings 52 of the lighting curtain 50 may be blocked by the adhesion material 80a (the adhesion layer 80). Hence, in the second embodiment, the adhesion material 80a (the adhesion layer 80) is preferably applied (formed) to areas other than the openings 52 of the lighting curtain 50. In this case, by applying the adhesion material 80a with a printing method such as silk printing, it is possible to accurately and easily apply (form) the adhesion material 80a (the adhesion layer 80) to a predetermined area.
[0149]When the adhesion material 80a is applied with the printing method, as shown in FIG. 14, the adhesion material 80a (the adhesion layer 80) may be applied (formed) to the reflective sheet segments 61 whereas, as shown in FIG. 15, the adhesion material 80a (the adhesion layer 80) may be applied (formed) to the predetermined area of the lighting curtain 50. The adhesion material 80a (the adhesion layer 80) may be applied (formed) to both the reflective sheet segments 61 and the lighting curtain 50.
[0150]The configuration of the other portions in the second embodiment is