Light guide film, backlight module and display device having the same
View Patent ↗A light guide film for use with a light source includes a light-transmissive substrate and a light-transmissive layer. The substrate includes a top surface, and a light-incident lateral surface adapted to be disposed adjacent to the light source. The layer is disposed on the top surface of the substrate and has a light-incident lateral surface aligned with the light-incident lateral surface of the substrate. The light-transmissive layer has an inclined surface that is opposite to the substrate and that extends away from the light-incident lateral surface of the layer and obliquely toward the top surface of the substrate. The layer has a refractive index different from that of the substrate.
1. A light guide film adapted for use with a light source, comprising:
a light-transmissive substrate including a top surface and a light-incident lateral surface that is adapted to be disposed adjacent to the light source; and
a light-transmissive layer disposed on said top surface and having a light-incident lateral surface that is aligned with said light-incident lateral surface of said substrate, said light-transmissive layer having an inclined surface that is opposite to said substrate and that extends away from said light-incident lateral surface of said light-transmissive layer and obliquely toward said top surface of said substrate;
wherein said light-transmissive layer has a refractive index different from that of said substrate;
said light-transmissive layer includes a first region that is adapted to be disposed adjacent to the light source, and a second region that is in contact with and extends away from said first region along said substrate; and
said first and second regions of said light-transmissive layer have mutually-different refractive indices that are smaller than the refractive index of said substrate and that are greater than a refractive index of air.
2. The light guide film according to claim 1 , wherein the refractive index of said first region of said light-transmissive layer is smaller than that of said second region.
3. The light guide film according to claim 1 , wherein said light-incident lateral surface of said light-transmissive layer is formed on said first region.
4. The light guide film according to claim 1 , wherein said first region of said light-transmissive layer has a contacting surface that is in direct contact with said second region.
5. The light guide film according to claim 4 , wherein:
said light-transmissive layer is configured to have a trapezoidal cross-section and further has top and bottom horizontal surfaces interconnecting said light-incident lateral surface and said inclined surface; and
said contacting surface of said first region extends obliquely downward from an intersecting line formed between said inclined surface and said top horizontal surface of said light-transmissive layer and meets with said top surface of said substrate.
6. The light guide film according to claim 5 , wherein said contacting surface of said first region meets with said top surface of said substrate at a line which is defined by projecting a midline of said top horizontal surface onto said top surface of said substrate.
7. The light guide film according to claim 5 , wherein said contacting surface of said first region meets with said top surface of said substrate at a line that is within an area defined by projecting said top horizontal surface onto said top surface of said substrate.
8. The light guide film according to claim 4 , wherein said inclined surface meets with said light-incident lateral surface of said light-transmissive layer, and said contacting surface of said first region meets with said inclined surface of said light-transmissive layer.
9. The light guide film according to claim 8 , wherein said light-transmissive layer is configured to have a triangular cross-section, and said contacting surface of said first region meets with said top surface of said substrate.
10. The light guide film according to claim 4 , wherein said contacting surface of said first region has an angle relative to said top surface of said substrate ranging from 30° to 75°.
11. The light guide film according to claim 1 , wherein said top surface of said substrate is partially covered by said light-transmissive layer.
12. A backlight module comprising:
a light source; and
said light guide film of claim 1 for guiding light emitted from said light source toward a direction where said top surface of said substrate faces.
13. The backlight module according to claim 12 , wherein said light guide film has an overall thickness of not less than that of said light source.
14. A display device, comprising:
said backlight module of claim 12 ; and
a display panel that is disposed to face toward said top surface of said substrate.
15. A light guide film adapted for use with a light source, comprising:
a light-transmissive substrate including a top surface and a light-incident lateral surface that is adapted to be disposed adjacent to the light source; and
a light-transmissive layer disposed on said top surface and having a light-incident lateral surface that is aligned with said light-incident lateral surface of said substrate, said light-transmissive layer having an inclined surface that is opposite to said substrate and that extends away from said light-incident lateral surface of said light-transmissive layer and obliquely toward said top surface of said substrate;
wherein said light-transmissive layer has a refractive index different from that of said substrate;
said light-transmissive layer includes a first region, and a second region that is disposed between said first region and said substrate;
said light-incident lateral surface of said light-transmissive layer has a first surface portion that is formed on said first region, and a second surface portion that is formed on said second region and that is formed between said light-incident lateral surface of said substrate and said first surface portion; and
said first and second regions of said light-transmissive layer have mutually-different refractive indices that are smaller than the refractive index of said substrate and that are greater than a refractive index of air.
16. The light guide film according to claim 15 , wherein said top surface of said substrate is partially covered by said light-transmissive layer.
17. A backlight module comprising:
a light source; and
said light guide film of claim 15 for guiding light emitted from said light source toward a direction where said top surface of said substrate faces.
18. The backlight module according to claim 17 , wherein said light guide film has an overall thickness of not less than that of said light source.
19. A display device, comprising:
said backlight module of claim 17 ; and
a display panel that is disposed to face toward said top surface of said substrate.