LIGHTING DEVICE AND DISPLAY DEVICE
20170269431 · 2017-09-21
Inventors
Cpc classification
G02F1/133606
PHYSICS
G02F1/133607
PHYSICS
International classification
Abstract
A lighting device has a housing having a bottom part and an opening, the bottom part being formed with through holes, and a substrate having light sources mounted on one surface thereof, the substrate being placed outside of the bottom part of the housing such that light emitted from the light sources is passed through the respective through holes and radiated to the opening of the housing. The lighting device also has light guide parts, each of which has a cylindrical shape, inserted through the through holes of the bottom part of the housing for guiding the light emitted from the light sources, respectively, and diffusion lenses provided inside of the housing for diffusing the light guided by the light guide parts, respectively. Each of the light guide parts is hollow and configured to reflect the light by an inner surface thereof so as to guide reflected light to an associated diffusion lens.
Claims
1. A lighting device comprising: a housing having a bottom part and an opening, the bottom part being formed with through holes; a substrate having light sources mounted on one surface thereof, the substrate being placed outside of the bottom part of the housing such that light emitted from the light sources is passed through the respective through holes and radiated to the opening of the housing; light guide parts, each of which has a cylindrical shape, inserted through the through holes of the bottom part of the housing for guiding the light emitted from the light sources, respectively; and diffusion lenses provided inside of the housing for diffusing the light guided by the light guide parts, respectively, wherein each of the light guide parts is hollow and configured to reflect the light by an inner surface thereof so as to guide reflected light to an associated diffusion lens.
2. The lighting device according to claim 1, wherein the diffusion lenses have a diameter that is larger than that of the through holes, and the diffusion lenses cover the bottom part around the through holes.
3. The lighting device according to claim 2, wherein an outer peripheral part of each of the diffusion lenses is in contact with the bottom part of the housing.
4. The lighting device according to claim 1, wherein the light guide parts and the diffusion lenses are formed as separate members.
5. The lighting device according to claim 1, further comprising: a heat insulating material provided between the housing and the substrate.
6. The lighting device according to claim 1, further comprising: a radiator that is in contact with another surface of the substrate opposite to the one surface of the substrate.
7. The lighting device according to claim 6, wherein the radiator has a base in contact with the substrate, and radiating fins formed on the base in an erected manner.
8. The lighting device according to claim 6, wherein the radiator has a base in contact with the substrate, and radiating pins formed on the base in an erected manner.
9. The lighting device according to claim 1, wherein a treatment for enhancing heat radiation has been applied to another surface of the substrate opposite to the one surface of the substrate.
10. The lighting device according to claim 1, wherein the substrate is formed of metal.
11. A display device comprising: the lighting device according to claim 1; and a display panel provided so as to close the opening of the housing of the lighting device and configured to control transmittance of light emitted from the light sources so as to display an image.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not intended to limit the present invention, and wherein:
[0038]
[0039]
[0040]
[0041]
[0042]
[0043]
[0044]
[0045]
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[0047]
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[0049]
DETAILED DESCRIPTION OF THE INVENTION
[0050] The present invention will be described in detail below referring to the attached drawings showing various embodiments.
Embodiment 1
[0051]
[0052] The backlight 200 has a plurality of light emitting diodes (“LEDs”) 2 as light sources. The LEDs 2 are mounted on one surface (which is a mounting surface) of a substrate 3 so as to be arrayed vertically and horizontally. Preferably, the substrate 3 is formed of a metal with high heat dissipation, such as aluminum. The mounting surface of the substrate 3 is formed with wiring traces consisting of copper foil pattern 30 for conducting current to the LEDs 2 (see
[0053] The liquid crystal panel 1 has a laminated structure in which a liquid crystal material is contained between two opposed glass substrates, and two polarizing plates are provided so as to sandwich the two glass substrates. The liquid crystal panel 1 is configured such that voltage across the glass substrates is controlled pixel by pixel so as to change orientation of molecules of the liquid crystal material and that twist of a polarization plane of light passing through the two polarizing plates is controlled so as to control transmittance of the light pixel by pixel.
[0054] The backlight 200 has a back chassis 7. As shown in
[0055] An inner surface of the bottom part 70, inner surfaces of the side plates, and a surface of the edge part connected to those inner surfaces of the side plates will be generally referred to as an inner surface of the back chassis 7 below. A surface of the back chassis 7 opposite to the inner surface thereof will be referred to as an outer surface of the chassis 7.
[0056] A reflection sheet 11 for reflecting light is attached to the substantially entire inner surface of the back chassis 7 except where the through holes 7 (see
[0057]
[0058] Positions of the through-holes 71 in the bottom part 70 correspond to positions of the LEDs 2 on the substrate 3. The substrate 3 is provided outside of the bottom part 70, with the LEDs 2 being opposed to the corresponding light guide parts 41a in the respective holes 71. A recessed part is formed on one end of the light guide part 41a opposite to another end where the diffusion lens part 40a is placed, and a peripheral part around the recessed part is in contact with the substrate 3 and surrounds a corresponding LED 2 on the substrate 3. As a result, each of the LEDs 2 is placed within a space defined by the mounting surface of the substrate 3 and the recessed part of the corresponding light guide part 41a. Because the light guide parts 41a protrude from the bottom part 70, the substrate 3 is spaced from the back chassis 7. The substrate 3 may be, for example, screwed to the bottom part 70.
[0059] In an example of
[0060] A rectangular frame-shaped panel chassis 8 having an external shape substantially same as that of the back chassis 7 is joined on an inner surface side of an edge part of the back chassis 7 with the outer peripheries of the back chassis 7 and the panel chassis 8 being coincident with each other.
[0061] A groove is formed circumferentially on the inner periphery of the panel chassis 8 and a rectangular diffusion plate 5 is fitted in the groove 8 so as to be placed in parallel with the bottom part 70. The diffusion plate 5 is formed of a transparent resin material, such as acrylic, for example, which is mixed with a light diffusing agent. The diffusion plate 5 further diffuses, within it, light that is radiated from the guide and diffusion lens 4 on the bottom 70 and incident upon one surface, specifically, a rear surface, of the diffusion plate 5. The diffusion plate 5 radiates the internally diffused light from its front surface opposite to the rear surface.
[0062] An optical sheet laminate 6 is provided on the front side of the diffusion plate 5. The optical sheet laminate 6 includes one transparent diffusion sheet for diffusing incident light to provide uniform luminance and two transparent prism sheets for aligning the incident light in the normal direction of the prism sheets, wherein the transparent diffusion sheet and the transparent prism sheets are stacked on one another.
[0063] The liquid crystal panel 1 slightly larger than an opening of the panel chassis 8 is provided on the front side of the panel chassis 8 so as to entirely cover the opening of the panel chassis 8. An edge part of the liquid crystal panel 1 is in contact with a front surface of the panel chassis 8. Of two main surfaces of the liquid crystal panel 1, one surface farther from the back chassis 7 and the panel chassis 8 is a display surface for displaying images.
[0064] A rectangular frame-like bezel 9 having an L-shaped cross section is provided so as to cover the outer peripheral surface of the panel chassis 8 and the edge part of the liquid crystal panel 1. That is, the liquid crystal panel 1 is clamped by the panel chassis 8 and the bezel 9.
[0065] The back chassis 7, the panel chassis 8, and the bezel 9 constitute a housing 10 whose one face is opened.
[0066] In the display device 100 having the above configuration, light emitted from each of the plurality of LEDs 2 reaches a corresponding diffusion lens part 40a through a corresponding diffusion lens part 40a, and is diffused and radiated into the housing by the diffusion lens part 40a. The plurality of guide and diffusion lenses 4 diffuse light emitted from respective LEDs 2, so that the light to enter into the housing 10 is made uniform as a whole. Then, the diffusion plate 5 is irradiated with the light coming from the diffusion lenses 4 directly or through reflection by the reflection sheet 11.
[0067] The irradiation light is incident on the diffusion plate 5 from the rear surface thereof, then diffused in the inside of the diffusion plate 5 to be made more uniform, and finally radiated from the front surface thereof.
[0068] The light made uniform and radiated by the diffusion plate 5 enters the optical sheet laminate 6. As described above, the light entering the optical sheet laminate 6 is further diffused to be more uniform, and also aligned in the normal direction of the optical sheet laminate 6.
[0069] The light emitted from the optical sheet laminate 6 enters the liquid crystal panel 1 through its rear surface. The liquid crystal panel 1 is configured such that transmittance of the light is controlled pixel by pixel in accordance with a signal input from a control circuit (not shown) and an image corresponding to the input signal is displayed on the display surface.
[0070] As described above, in order to display images on the display device 100, it is necessary to supply electric power to the LEDs 2 to make the LEDs 2 emit light. At that time, a part of the electric power supplied to the LEDs 2 is discharged as heat. In the display device 100 of this embodiment, the substrate 3 is provided outside the housing 10 so as to be spaced and separated from the housing 10. Therefore, a large part of heat emitted from the LEDs 2 is discharged outside of the housing 10 and is hardly transferred to the inside of the housing 10. As a result of this, increase of the temperature in the diffusion plate 5, the optical sheet laminate 6, and the liquid crystal panel 1 is suppressed, so that thermal deformation of the diffusion plate 5 and the optical sheet laminate 6 and denaturalization of the liquid crystals filled in the liquid crystal panel 1 due to the increased temperature thereof are suppressed. Therefore, the LEDs are allowed to be supplied with as much electric power as possible so far as display defects are not caused, and emit light at a higher intensity, which allows the liquid crystal panel 1 to display images at a higher luminance. Thus, the visibility or legibility of the displayed images is improved.
[0071] In the display device 100 of this embodiment, the through holes 71 in the back chassis 7 are closed or occluded by the light guide parts 41a inserted in the respective through holes 71. Therefore, intrusion of dust into the housing 10, which would cause malfunction of the display device, is prevented. In addition, since the guide and diffusion lenses 4 are attached to the back chassis 7, when replacing the substrate 3 because of a failure in LEDs and/or the substrate 3 itself, the guide and diffusion lenses 4 are not required to be replaced, which facilitate repair operations.
Embodiment 2
[0072]
[0073] In this embodiment, the substrate 3 is provided outside of the housing 10 so as to be separated and spaced from the housing 10, as in Embodiment 1. Therefore, heat emitted from the LEDs 2 is hardly transferred to the inside of the housing 10. Thus, the liquid crystal panel 1 is allowed to display images at a higher luminance to an extent that display defects are not caused, whereby the visibility or legibility of the displayed images is improved.
[0074] The other configurations of this embodiment are same as or similar to those of Embodiment 1, and description thereof is omitted here.
Embodiment 3
[0075]
[0076] The light guide parts 41d in this embodiment are formed of, for example, light-reflecting material, so that light emitted by each LED 2 is reflected by an inner surface of the corresponding light guide part 41d while being guided to the associated diffusion lens part 40d. The hollow cylinder of the light guide part 41D is filled with air. Due to the heat insulating effect of the air, the light guide parts 40d in this embodiment hardly transfer heat, as compared with the light guide parts, which are not hollow, of Embodiment 1. Thus, heat emitted from the LEDs 2 is hardly transferred to the diffusion plate 5, the optical sheet laminate 6, and the liquid crystal panel 1, as a result of which increase of the temperature in these components is further suppressible.
[0077] The other configurations of this embodiment are same as or similar to those of the preceding embodiments, and description thereof is omitted here.
Embodiment 4
[0078]
[0079] In the display device 100 of this embodiment, because the heat insulating material 12 is provided between the back chassis 7 and the substrate 3, heat generated from the LEDs 2 is further suppressed from being transferred to the inside of the housing 10, and thus, increase of the temperature in the diffusion plate 5, the optical sheet laminate 6 and the liquid crystal panel 1 is further suppressible, as compared with the preceding embodiments. Thus, the liquid crystal panel 1 is allowed to display images at a higher luminance to an extent that display defects are not caused, whereby the visibility or legibility of the displayed images is improved.
[0080] The other configurations of this embodiment are same as or similar to those of the preceding embodiments, and description thereof is omitted here.
Embodiment 5
[0081]
[0082] Heat generated by the LEDs 2 are conducted via the substrate 3 to the radiator 13. Since the radiator 13 has a surface area which is increased by the plurality of radiating fins 131 erected from the base 130, the radiator 13 contacts with air by the increased surface. The heat conducted to the radiator 13 is efficiently released to the air by the increased surface of the radiator 13. That is, due to the radiator 13 mounted to the substrate 3, the substrate 3 is efficiently cooled, so that heat generated from the LEDs 2 is hardly transferred to the housing and increase of the temperature in the diffusion plate 5, the optical sheet laminate 6 and the liquid crystal panel 1 is suppressible. Thus, the display device 100 according to this embodiment is allowed to make the LEDs 2 emit light at a higher intensity to an extent that display defects are not caused, and to further increase the luminance of displayed images, as compared with other embodiments in which no radiator 13 is provided.
[0083]
[0084] In both examples shown in
[0085] The other configurations of this embodiment are same as or similar to those of the preceding embodiments and description thereof is omitted here.
Embodiment 6
[0086]
[0087] The radiator 13 is formed in a shape of a pin frog for flower arrangement as shown in
[0088] The other configurations of this embodiment are same as or similar to those of the preceding embodiments and description thereof is omitted here.
Embodiment 7
[0089] In a display device 100 according to Embodiment 7, various treatments for enhancing heat radiation may be applied to the rear surface of the substrate 3.
[0090]
[0091] Alternatively, instead of providing the black painted part 31, a black tape may be stuck to the rear surface of the substrate 3. In this case, the substrate 3 can be efficiently cooled as in the case in which the black painted part 31 is provided.
[0092] Alternatively, unlike the example of
[0093] In this embodiment, heat is efficiently discharged even if the substrate 3 is not formed of a material having high thermal conductivity such as aluminum, for example, but is formed of a material, such as glass epoxy resin, which has low thermal conductivity but is relatively inexpensive. Thus, the substrate 3 can be formed of less expensive material. Accordingly, the display device 100 according to the present embodiment can be manufactured at lower costs as compared to the embodiments in which the substrate is formed of a material having high thermal conductivity; nevertheless the display device 100 can display images at a same luminance as that of the display devices according to such embodiments.
[0094] The other configurations of this embodiment are same as or similar to those of the preceding embodiments and description thereof is omitted here.
[0095] In the above-described embodiments, several examples have been shown in which a liquid crystal panel is used as the display panel. The present invention is not limited to such examples, but the display panel may be of any type that is able to control the transmittance of light, and the display device may be of any type that includes such a display panel and light sources that irradiate the display panel with light. For example, the present invention is applicable to MEMS (Micro Electro Mechanical Systems) display devices that include a MEMS shutter panel configured to control the transmittance of light by opening and closing shutters using the MEMS, and light sources for irradiating the MEMS shutter panel with light.
[0096] It should be understood that the embodiments disclosed herein are only illustrative and not limitative in every respect. The scope of the present invention is defined by the scope of the following claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the scope of the claims.
REFERENCE SIGNS LIST
[0097] 100 display device
[0098] 200 backlight (lighting device)
[0099] 1 liquid crystal panel (display panel)
[0100] 2 LED
[0101] 3 substrate
[0102] 30 copper foil pattern
[0103] 31 black painted part
[0104] 32 through hole
[0105] 33 metal foil pattern
[0106] 4 guide and diffusion lens
[0107] 40a, 40b, 40c, 40d diffusion lens parts
[0108] 41a, 41d light guide parts
[0109] 5 diffusion plate
[0110] 6 optical sheet laminate
[0111] 7 back chassis
[0112] 70 bottom part
[0113] 71 through hole
[0114] 8 panel chassis
[0115] 9 bezel
[0116] 10 housing
[0117] 11 reflection sheet
[0118] 12 heat insulating material
[0119] 13 radiator
[0120] 130 base
[0121] 131 radiating fin
[0122] 132 radiating pin