Patent Application
20150062870
The present invention relates to a display device.
Various image display devices provided with a phosphor substrate have been proposed up to now. The display devices disclosed in Japanese Patent Application Laid-Open Publication No. 2000-131683 and Japanese Patent Application Laid-Open Publication No. 2003-5182, for example, are provided with a liquid crystal display component, a light source that illuminates the liquid crystal display component from the rear side, and a wavelength converting section. The wavelength converting section includes at least one type of phosphor for converting wavelength that converts light from the light source into red or green, and this wavelength converting section is provided for each pixel on the light emitting side of the liquid crystal display component.
Furthermore, the display device disclosed in Japanese Patent Application Laid-Open Publication No. 2010-66437 is provided with a front plate, a light shutter, and a light source. The front plate has a plurality of light scattering members that generate diffused light and a planarizing film formed so as to cover the light scattering members.
The light scattering members include a red phosphor that converts blue light to red light, a green phosphor that converts blue light to green light, and a blue light scattering member that scatters blue collimated light.
The light shutter is a liquid crystal display component. A polarizing plate is provided on the uppermost layer of the liquid crystal display component. A polarizing plate of the light shutter and a planarizing film of the front plate are bonded by an adhesive.
In a display device provided with a phosphor similar to those mentioned above, in general, an adhesive layer is inserted between the light source unit and the color conversion substrate that includes the phosphor so as to fix the light conversion substrate to the light source unit.
If light with a prescribed frequency band from a light source unit enters the phosphor, the phosphor becomes excited, and emits a light with a prescribed frequency band.
Because the phosphor emits light radially, a portion of light from the phosphor is emitted towards the light source unit in some cases.
In such a case, if there is an adhesive layer or the like between the light source unit and the phosphor, then among the light emitted by the phosphor, the light traveling toward the light source unit enters into the adhesive layer. As a result, there is a problem of the light use efficiency decreasing.
Furthermore, the phosphor is formed on the main surface of a transparent substrate, but because the phosphor has a higher refractive index than the glass substrate, light with a large incident angle enters the glass substrate. In many cases, light with a large incident angle does not travel toward the viewer when exiting from the glass substrate towards the outside. In this manner, a display device provided with a conventional phosphor has a problem in that the light use efficiency thereof of the light from the phosphor is low.
The present invention was made in view of the above-mentioned problem, and an object thereof is to provide a display device aiming to improve the light use efficiency of light emitted from a phosphor.
The display device related to the present invention includes a light source unit that emits light; and a color conversion substrate, including: a plurality of phosphors that emit light when light from the light source unit is received; a transparent substrate disposed on the phosphors; a low refractive index layer that is formed between the phosphors and the transparent substrate and that has a lower refractive index than the phosphors; and a reflective member that reflects light that is emitted by the phosphors, wherein the reflective member is positioned closer to the light source unit than the phosphors, and wherein an air layer is formed between the phosphors and the light source unit.
It is preferable that the display device further include a spacer disposed between the color conversion substrate and the light source unit. It is preferable that the color conversion substrate be disposed farther towards the light source unit than the phosphor, the color conversion substrate further including a reflective member that reflects light emitted by the phosphor. The spacer is disposed between the reflective member and the light source unit.
It is preferable that a plurality of the spacers be provided between the color conversion substrate and the light source unit. It is preferable that the plurality of phosphors be aligned with gaps therebetween. A groove that extends in one direction is formed between the phosphors. The spacer is formed between the phosphors so as to extend in the one direction. It is preferable that the plurality of phosphors be aligned with gaps therebetween. The spacer is disposed between the phosphors. It is preferable that the phosphor has a receiving surface facing the light source unit and receiving light from the light source unit. The spacer is formed in a loop shape so as to extend along a periphery of the receiving surface of the phosphor. It is preferable that the spacer be formed of a material having light-shielding characteristics. It is preferable that the color conversion substrate include a light scattering member formed on a main surface of the transparent substrate, and have an air layer formed between the light source unit and the light scattering member.
It is preferable that the phosphor include a receiving surface that receives light from the light source unit, an emitting surface that faces the transparent substrate, and a side face between the receiving surface and the emitting surface. The color conversion substrate includes a resin layer that covers the side face of the phosphor. The resin layer is formed so as to protrude farther towards the light source unit than the receiving surface of the phosphor, and an air layer is formed between the receiving surface of the phosphor and the light source unit.
It is preferable that the resin layer be formed in a loop shape so as to surround the phosphor, and that the resin layer further includes a first opposing face that opposes the transparent substrate, a second opposing face that opposes the light source unit, and a side face that is between the first opposing face and the second opposing face. The color conversion substrate includes a reflective member formed across the side face and the second opposing face of the resin layer.
According to the display device related to the present invention, an improvement in light use efficiency of the light emitted by a phosphor can be achieved.
The light source unit 1a includes the light source module 2 that emits blue light BL and the light shutter 3 disposed on the light source module 2. The light shutter 3 and a color conversion substrate 4 are connected to each other by a fixing member 9.
The light source module 2 is provided with a light guide plate 2b, a plurality of LEDs (light emitting diodes) 2a provided on a side face of the light guide plate 2b, and the like, for example. The light source module 2 is a surface light-emitting unit that radiates blue light BL towards the light shutter 3. The light source module 2 is not limited to an edge-lit backlight like the one described above. The light source module 2 may be a direct-lit type provided with a plurality of the LEDs 2a arranged in an array, for example. The wavelength region of the blue light BL is 390 nm to 510 nm, for example. The wavelength in which the intensity of the blue light BL is highest is approximately 450 nm, for example.
The light shutter 3 selectively allows the blue light BL emitted from the light source module 2 to enter the color conversion substrate 4 while blocking light other than this blue light BL. As for the light shutter 3, an example using liquid crystal is described, but MEMS may also be used as the light shutter 3.
The light shutter 3 includes a TFT (thin film transistor) substrate 5 disposed towards the light source module 2, an opposite substrate 6 disposed farther towards the opposite side of the light source module 2 than the TFT substrate 5, a liquid crystal layer 7 sealed between the TFT substrate 5 and the opposite substrate 6, and a sealing member 8 that seals the liquid crystal layer 7.
The TFT substrate 5 includes a transparent substrate 10 such as a glass substrate, a polarizing plate 11 formed on the transparent substrate 10 on a main surface thereof that faces the light source module 2, a plurality of thin film transistors 13 formed on the transparent substrate 10 on a main surface thereof on an opposite side to the main surface where the polarizing plate 11 is formed, an interlayer insulating film 14 formed so as to cover the thin film transistors 13, a pixel electrode 15 formed on the interlayer insulating film 14, and an alignment film 16 that is formed so as to cover the pixel electrode 15.
Each of the thin film transistors 13 includes a gate electrode 20 formed on a main surface of the transparent substrate 10, a gate insulating film 12 formed so as to cover the gate electrode 20, a semiconductor layer 21 formed on the gate insulating film 12, and a source electrode 22 and a drain electrode 23 formed so as to have a gap therebetween on a semiconductor layer 21.
The pixel electrode 15 is formed of a transparent conductive film such as an ITO (indium tin oxide) film, an IZO (indium zinc oxide) film, or the like, for example. The pixel electrode 15 is connected to the drain electrode 23 by a contact (not shown). Thus, when the thin film transistor 13 is in an ON state, a prescribed voltage is applied to the pixel electrode 15.
A plurality of thin film transistors 13 are provided, and in the example shown in
Furthermore, the thin film transistors 13R, 13G, and 13B are respectively connected to pixel electrodes 15R, 15G, and 15B.
The gate insulating film 12 and the interlayer insulating film 14 are transparent insulating films similar to a silicon oxide film, a silicon nitride film, or the like. The alignment film 16 is formed of a polyimide film or the like, and a rubbing treatment is performed on the surface thereof so that the orientation of the liquid crystal molecules can be controlled. The liquid crystal layer 7 includes a plurality of liquid crystal molecules.
The opposite substrate 6 includes a glass substrate 30 formed of glass or the like, a common electrode 31 formed on the glass substrate 30 on a main surface thereof that faces the TFT substrate 5, an alignment film 32 formed so as to cover the common electrode 31, and a polarizing plate 33 formed on a main surface that faces the color conversion substrate 4. The sealing member 8 is formed along the periphery of the TFT substrate 5 and the opposite substrate 6 in a loop shape, and the liquid crystal layer 7 is sealed between the opposite substrate 6 and the TFT substrate 5.
The color conversion substrate 4 includes a main plate 39 and a phosphor layer 42 formed on a main surface of the main plate 39 that faces the light shutter 3. The main plate 39 includes a transparent substrate 40 and a low refractive index film 41 formed on the main surface of the transparent substrate 40. The transparent substrate 40 is a glass substrate, or the like, for example. The refractive index of the low refractive index film 41 is 1.20 to 1.40.
The phosphor layer 42 includes a light scattering member 44, phosphors 45, a resin layer 43 covering the light scattering member 44 and the phosphors 45, and a reflective member 46 formed on a resin layer 43. The phosphors 45 include a red phosphor 45R and a green phosphor 45G. The red phosphor 45R, the green phosphor 45G, and the light scattering member 44 are disposed so as to have a gap therebetween.
The refractive index of the red phosphor 45R and the green phosphor 45G are approximately 1.49 to 1.59. The red phosphor 45R and the green phosphor 45G are formed of an organic phosphor material, a nanophosphor material, or the like. Examples of the organic phosphor materials include a rhodamine pigment such as rhodamine B that is a red fluorescent pigment, a coumarin pigment such as coumarin 6 that is a green fluorescent pigment, or the like. The nanophosphor material includes a binder and a plurality of phosphors diffused in the binder. The binder is formed of a resin such as a transparent silicone type, an epoxy type, or an acrylic type, for example. CdSe, ZnS, or the like that is a nanoparticle phosphor can be used as the phosphor, for example.
By forming the red phosphor 45R using a material mentioned above, the red phosphor 45R can transmit red light (light with a wavelength region of 530 nm to 690 nm). As a result, the light emitted by exciting the red phosphor 45R can pass through the red phosphor 45R, and thus an improvement in light use efficiency of the light emitted by the red phosphor 45R is possible.
In a similar manner, the green phosphor 45G can allow green light to pass through and the light emitted by exciting the green phosphor 45G can pass through the green phosphor 45G, and thus an improvement in light use efficiency of the light emitted by the green phosphor 45G is possible.
The light scattering member 44 is a layer that diffuses light entering therein and then emits the light outside. The light scattering member 44 has a transparent resin as a binder and a plurality of scattering particles that are scattered in the resin. The transparent resin that is a binder allows blue light BL to pass through and allows the light use efficiency to be improved.
The resin layer 43 is formed of a transparent resin material. The resin layer 43 is formed so as to protrude farther towards the light shutter 3 than the light scattering member 44 and the phosphors 45. The reflective member 46 is formed so as to cover the surface of the resin layer 43 and to be in contact with a top face of the light shutter 3.
As a result, an air layer 48 is formed between the light shutter 3, the light scattering member 44, and the phosphors 45. In other words, the reflective member 46 and the resin layer 43 function as a spacer 47 forming the air layer 48 between the light shutter 3, the red phosphor 45R, the green phosphor 45G, and the light scattering member 44.
As shown in
The resin layer 43 includes a top face 25 that is in contact with the low refractive index film 41, a bottom face 26 located towards the opposite substrate 6, an inner surface 27 that is in contact with the side face 22 of the red phosphor 45R, and an outer surface 28.
The reflective member 46 includes a bottom face portion 55 formed on the bottom face 26 of the resin layer 43, an inner wall 56 formed on the inner surface 27, and an outer wall 57 formed on the outer surface 28.
The inner wall 56 is formed in a loop shape, and the inner wall 56 forms an opening 53 that permits the blue light BL to enter the red phosphor 45R. Similarly, in
In
A groove 37 is formed between the outer wall 57 of the reflective member 46B and the outer wall 57 of the reflective member 46R.
In
Furthermore, as shown in
The driving of the display device 1 with this type of configuration is described. In
Here, the refractive index of the low refractive index film 41 is lower than the refractive index of the red phosphor 45R. Therefore, red light RL1 that enters the low refractive index film 41 with a smaller incident angle than the critical angle of the interface between the low refractive index film 41 and the red phosphor 45R enters the main plate 39.
On the other hand, the red light RL that enters with a greater incident angle than the above-mentioned critical angle is reflected by the interface between the red phosphor 45R and the low refractive index film 41. Red light RL2 shown in
Then, the red light RL2 is reflected by the reflective member 46 and enters the low refractive index film 41 again. At this point, the incident angle of the red light RL2 entering the low refractive index film 41 is smaller than the critical angle and the red light RL2 enters the main plate 39.
Furthermore, a portion of the red light RL1 emitted in a radial manner travels towards the receiving surface 20. Red light RL3 and RL4 travel towards the receiving surface 20, for example. Here, the receiving surface 20 is exposed to the air layer 48. The refractive index of the air layer 48 is 1.0 and the refractive index of the red phosphor 45R is greater than the refractive index of air.
Therefore, if the incident angle of the red light RL3 and RL4 is greater than the critical angle of the interface between the air layer 48 and the red phosphor 45R, the red light RL3 and RL4 are reflected. As a result, the red light RL emitted by the red phosphor 45R can be suppressed from being emitted towards the light shutter 3. Following this, an improvement in light use efficiency can be attained. After the red light RL4 is reflected by the interface between the red phosphor 45R and the air layer 48, the red light RL4 is reflected by the reflective member 46. The red light RL4 reflected by the reflective member 46 enters the interface between the red phosphor 45R and the low refractive index film 41. During this time, the incident angle of the red light RL4 is smaller than the critical angle of the interface between the low refractive index film 41 and the red phosphor 45R, and the red light RL4 enters the main plate 39. Then, the red light RL4 is emitted outside from the emitting surface of the transparent substrate 40. When the red light RL3 is reflected by the interface between the red phosphor 45R and the air layer 48, the red light RL3 travels towards the light emitting surface 21.
During this time, if the incident angle to the interface between the low refractive index film 41 and the red phosphor 45R is greater than the critical angle, the red light RL3 is reflected by the interface between the low refractive index film 41 and the red phosphor 45R. Then, the red light RL3 is reflected by the reflective member 46 and enters the interface between the low refractive index film 41 and the red phosphor 45R again. Because the incident angle here is smaller than the critical angle, the red light RL3 passes through the low refractive index film 41. In addition, the red light that reaches the reflective member 46 after being reflected between the receiving surface 20 and the emitting surface 21 a plurality of times also passes through the low refractive index film 41. In this manner, an improvement in use efficiency of the red light RL that is emitted can be achieved by having the reflective member 46 reflect the red light RL that has been reflected by the interface between the red phosphor 45R and the air layer 48.
Furthermore, because the reflective member 46 includes the inner wall 56, the bottom face portion 55, and the outer wall 57, light that enters into the resin layer 43 can be suppressed from leaking to the light shutter 3. Because the outer wall 57 reflects the red light RL, the red light RL can be suppressed from entering the adjacent green phosphor 45G or the like.
The method of manufacturing the color conversion substrate 4 having a configuration similar to the configuration mentioned above will be described.
The film thickness of the low refractive index film 41 is approximately 0.5 μm to 3 μm, for example, and is preferably approximately 1 μm.
The film thickness of the red phosphor 45R and the green phosphor 45G is 2 μm to 10 μm, for example. It is preferable that the film thickness of the red phosphor 45R and the green phosphor 45G be 5 μm to 8 μm. The film thickness of the light scattering member 44 is 3 μm to 10 μm, for example. It is preferable that the film thickness of the light scattering member 44 be 5 μm to 8 μm.
When the color conversion substrate 4 is manufactured, a plurality of the color conversion substrates 4 may be simultaneously formed on the main surface of a wide mother glass substrate. In this case, a plurality of the color conversion substrates 4 that is formed on the mother glass substrate are cut into respective color conversion substrates 4.
Then, as shown in
A display device 1 according to Embodiment 2 will be described with reference to
The color conversion substrate 4 is disposed at a distance from a light shutter 3 due to the spacer 47. As a result, an air layer 48 is formed between a red phosphor 45R and the light shutter 3, between a green phosphor 45G and the light shutter 3, and between a light scattering member 44 and the light shutter 3.
As shown in
The resin layer 43 is formed so as to have a rectangular frame shape in the example shown in
In the present embodiment, the spacer 47 is formed in a cylindrical shape. Of course, the shape of the spacer 47 may be other shapes such as a rectangular columnar shape or a polygonal columnar shape.
In
The reflective member 46 includes a reflective member 46R that covers the resin layer 43R and a reflective member 46B that covers the resin layer 43B.
The reflective member 46R and the reflective member 46B both include a bottom face portion 55 and an outer wall 57. The bottom face portion 55 of the reflective member 46R is formed so as to cover a bottom face 26 of the resin layer 43R and the outer wall 57 is formed so as to cover an outer face 28 of the resin layer 43R. The bottom face portion 55 of the reflective member 46B is formed so as to cover a bottom face 26 of the resin layer 43B and the outer wall 57 is formed so as to cover an outer face 28 of the resin layer 43G.
The spacer 47A supports the bottom face portion 55 and the outer wall 57 of the reflective members 46B and 46R. As a result, the air layer 48 is formed between the red phosphor 45R and the light shutter 3. Thus, in the display device 1 of Embodiment 2, red light RL can also be suppressed from being emitted towards the light shutter 3 even if the red phosphor 45R emits light and the red light RL is emitted in a radial manner.
Furthermore, in
Furthermore, in the light scattering member 44, even if the blue light BL enters the light scattering member 44 and scatters, the scattered blue light BL can also be suppressed from being emitted to the light shutter 3 from the light scattering member 44.
Furthermore, the spacer 47 is formed between the reflective member 46 and the light shutter 3, and the spacer 47 is suppressed from blocking the blue light BL emitted to the red phosphor 45R, the green phosphor 45G, and the light scattering member 44 from the light shutter 3.
The spacers 47 are disposed in the groove 36 so as to have a gap therebetween. When the spacer 47 shown in
Here, the respective spacers 47a, 47b, and 47c are formed of a resin material having light-shielding characteristics. Due to this, in
As a result, light from the red phosphor 45R can be suppressed from entering the green phosphor 45G and the light scattering member 44.
Specifically, in
As shown in
In
In a similar manner, as shown in
As a result, in
Furthermore, according to
In a similar manner, even if the green light leaks from the green phosphor 45G towards the light shutter 3, the light that leaked can be suppressed from entering the red phosphor 45R and the light scattering member 44, and can be suppressed from entering another green phosphor 45G.
Furthermore, as for the light scattering member 44, even if the blue light BL diffused by the light scattering member 44 leaks towards the light shutter 3, the blue light BL can be suppressed from entering another green phosphor 45G, another red phosphor 45R, or both, and also suppress the blue light BL from entering another light scattering member 44.
As shown in
A display device 1 according to Embodiment 3 will be described with reference to
The phosphor layer 42 includes a plurality of light scattering members 44, a plurality of red phosphors 45R, a plurality of green phosphors 45G, and a reflective member 46.
A plurality of light scattering members 44 are aligned in an array direction D1 with a gap therebetween. A plurality of the green phosphors 45G are aligned in the array direction D1 with a gap therebetween, and a plurality of the red phosphors 45R are aligned along the array direction D1 with a gap therebetween.
Furthermore, grooves 62 are respectively formed between the green phosphor 45G and the light scattering member 44, between the green phosphor 45G and the red phosphor 45R, and between the red phosphor 45R and the light scattering member 44. The grooves 62 extend along the array direction D1. The color conversion substrate 4 has a groove 63 that intersects with the grooves 62. This groove 63 is formed so as to extend along the array direction D2.
The red phosphor 45R has a top face 24 that is in contact with the low refractive index film 41, a bottom face 23 that faces the light shutter 3, and a side face 22 that is between the top face 24 and the bottom face 23. A resin layer 43 is not formed in Embodiment 3. The reflective member 46 includes the outer wall 57 formed on the side face 22 of the red phosphor 45R and the bottom face portion 55 formed on the bottom face 23 of the red phosphor 45R.
Here, if the blue light BL enters the red phosphor 45R, then the red phosphor 45R emits red light RL in a radial manner. Even if a portion of the red light RL is about to leak from the side face 22, the outer wall 57 reflects the red light RL. In particular, the outer wall 57 is formed so as to have a slope shape that becomes wider as the outer wall 57 extends towards the transparent substrate 40 from the light shutter 3 side. As a result, the red light RL that heads towards the outside from the side face 22 can be reflected towards the transparent substrate 40 in a desirable manner. Furthermore, the bottom face portion 55 reflects the red light RL traveling towards the light shutter 3. In this manner, improvement in light use efficiency of the light emitted by the red phosphor 45R is also achieved in the display device 1 according to Embodiment 3.
An opening 58a that exposes a portion of the bottom face 23 is formed in the bottom face portion 55. Of the bottom face 23, the portion of the opening 58a that is exposed is a receiving surface 20. Here, the spacer 47 is disposed between the reflective member 46 and the light shutter 3. By disposing the spacer 47 in this manner, an air layer 48 is formed between the light shutter 3 and the receiving surface 20.
Therefore, similar to the display device 1 in Embodiment 1, the display device 1 of Embodiment 3 can also reflect at least a portion of the red light RL traveling towards the light shutter 3 from the red phosphor 45R, resulting in an improvement in light use efficiency.
In the example shown in
The air layer 48 is formed between the red phosphor 45R and the light shutter 3.
By forming the spacer 47 in this manner, the light emitted by the green phosphor 45G can be suppressed from entering the adjacent red phosphor 45R, the light scattering member 44, and the green phosphor 45G, for example.
The receiving surface 20 is formed by exposing a portion of the bottom face 23 of the red phosphor 45R through the opening 58a in the reflective member 46 and the opening 61c in the spacer 47R.
The spacer 47G is formed between the bottom face portion 55 of the reflective member 46G and the light shutter 3. The spacer 47B is formed between the bottom face portion 55 and the light shutter 3. An air layer is also formed between the green phosphor 45G and the light shutter 3, and between the light scattering member 44 and the light shutter 3.
In
Furthermore, because the spacer 47R is formed in a loop shape, even if external force is exerted on the display device 1, the air layer 48 formed between the red phosphor 45R and the light shutter 3 can suppress light from leaking outside. Embodiments of the present invention have been described above, but these embodiments are examples in every respect, and not limiting. The scope of the present invention is defined by the claims, and all modifications with the same meaning as the claims and within the scope defined thereby are included. In addition, the numbers and the like mentioned above are examples, and the present invention is not limited to such numbers or ranges.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-092854 | Apr 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2013/061152 | 4/15/2013 | WO | 00 |
