Illumination device and light-guiding member

• US 10,180,529 B2
• Filed: 03/12/2014
• Issued: 01/15/2019
• Est. Priority Date: 03/26/2013
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Ohno, Hiroshi, Yamamoto, Yuichiro, Kato, Mitsuaki, Takamatsu, Tomonao, Shiratsuchi, Masataka, Hayashihara, Hiromichi, Tamura, Hideo, Yamamoto, Masahiko
• Primary Examiner(s): Garlen, Alexander
• Assistant Examiner(s): Cattanach, Colin
• Application Number:
  US14/206,062
• Publication Number:
  US 20140293645A1
• Time in Patent Office: 1,770 Days
• Field of Search: 36231102, 362404, 362408, 362576, 362603, 362628
• CPC Class Codes: F21K 9/20 Light sources comprising attachment means
• CPC Class Codes: F21V 2200/20 of light guides of a generally planar shape
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 6/0021 for housing at least a part of the light source, e.g. by forming holes or recesses
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0043 provided on the surface of the light guide
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0085 Means for removing heat created by the light source from the package heat extraction or cooling elements for semiconductor light sources in general H01L33/64

Abstract

In one embodiment, an illumination device includes a light-guiding unit having a light output surface which outputs light and a back surface facing the light output surface, wherein the light-guiding unit has a curved surface in a region of the back surface farther than a first position on the back surface that is away by a first distance from an axis passing the light output surface and the back surface, and a rough surface in a region of the light output surface farther than a second position on the light output surface that is away by a second distance from the axis in a same direction as a direction from the axis toward the first position, and where an intersection of the axis and the back surface is an origin point, and a direction of the axis from the back surface to the light output surface is positive, a normal line of the curved surface intersects with the axis at the positive side of the axis, and an angle formed by a normal line vector at the second position in a direction toward the light output surface from the back surface of the light output surface and a vector in a direction from the curved surface to the second position is equal to or more than a critical angle.

Claims

1. An illumination device comprising a point light source and a light-guiding unit,

wherein the light-guiding unit is disc-shaped and is rotationally symmetrical about an axis, and the point light source is disposed in a central portion the light-guiding unit,

wherein the light-guiding unit has a light output surface, a back surface, a curved surface, and a rough surface that is angled relative to the axis,

wherein the back surface has a first position that is away by a first distance from the axis,

wherein the light output surface has a second position that is away by a second distance from the axis,

wherein the curved surface is disposed at an outer periphery of the back surface,

wherein an intersection of the axis and the back surface is an origin point, a direction of the axis from the back surface to the light output surface is positive, a normal line of the curved surface intersects with the axis at a positive side of the axis, and an angle formed by a normal line vector in a direction toward the light output surface from the back surface and a vector in a direction from the curved surface to the second position is equal to or more than a critical angle,

wherein the rough surface is in a region of the light output surface farther than the second position on the light output surface, and light that is totally reflected off the curved surface is diffused and transmitted through the rough surface,

wherein light sources are arranged with a regular interval in a ring shape manner, and

wherein the light-guiding unit comprises:

a rough end surface connecting with the back surface in a region of the light output surface farther than the second position, and a normal line of the end surface and a normal line of the back surface intersect each other at a negative side of the axis, and

scatter dots provided on the back surface in order to scatter guided light, a distribution of the scatter dots being rarefactional when the scatter dots are closer to the axis and condensational when the scatter dots are farther from the axis

wherein the back surface comprises a flat surface portion extending from a third position on the back surface to the first position; and

wherein the light output surface comprises a flat surface portion extending from a fourth position on the light output surface to the second position, and wherein the flat surface portion of the light output surface is substantially parallel to the flat surface portion of the back surface.

2. The illumination device according to claim 1, wherein

the light-guiding unit has a hollow hole whose center is at the axis, and

the light source is arranged in the hollow hole, and emits the light toward a side surface of the hollow hole.

3. The illumination device according to claim 1,

wherein the scatter dots of the light-guiding unit form scatter units for scattering incident light, and

wherein a coverage factor ρ

(r) of the scatter units at a distance r from the axis satisfies a following expression,

4. The illumination device according to claim 3, wherein the coverage factor ρ

(r) of the scatter units at the distance r from the axis satisfies a following expression,

5. The illumination device according to claim 4, wherein the scatter units are in a circular shape having a diameter D, and where a pitch P₁ of a radial direction of the scatter units is constant, a pitch P₂ (r) in an azimuth direction of the scatter units at the distance r from the axis satisfies a following expression,

6. The illumination device according to claim 2, comprising a heat radiation unit, wherein

a joint unit is connected to the heat radiation unit, and the light source is provided on the joint unit, and the joint unit is provided in the hollow hole, and

the joint unit is partially provided with a threading processed portion, and the light-guiding unit is fixed, in a sandwiched manner, by a plurality of nuts corresponding to the threading processed portion.

7. The illumination device according to claim 1, wherein

the light-guiding unit has a curved surface portion in a region of the back surface closer to the axis than the first position and in a region of the light output surface closer to the axis than the second position, and has an incidence surface, which connects the back surface and the light output surface, in a region of the back surface closer to the axis than the first position and in a region of the light output surface closer to the axis than the second position, and

a plurality of light sources having different wavelength spectrums are provided, and the light sources emit light onto the incidence surface.

15. The illumination device according to claim 1, wherein an exit surface is partially rough.

16. The illumination device according to claim 1, wherein the rough surface is formed such that the light further comes into contact with the light output surface of the light-guiding unit, and the light is transmitted outside without being totally reflected.

8. A light-guiding member comprising a light output surface, a curved surface, and a rough surface,

wherein the light-guiding member is disc-shaped and rotationally symmetrical about an axis, and the rough surface is angled relative to the axis,

wherein the back surface has a first position that is away by a first distance from the axis,

wherein the light output surface has a second position that is away by a second distance from the axis, wherein the curved surface is disposed at an outer periphery of the first position,

wherein an intersection of the axis and the back surface is an origin point, a direction of the axis from the back surface to the light output surface is positive, a normal line of the curved surface intersects with the axis at a positive side of the axis, and an angle formed by a normal line vector at the second position in a direction toward the light output surface from the back surface and a vector in a direction from the curved surface to the second position is equal to or more than a critical angle,

wherein the rough surface is in a region of the light output surface farther than the second position on the light output surface, and light that is totally reflected off the curved surface is diffused and transmitted through the rough surface,

wherein light sources are arranged with a regular interval in a ring shape manner so that an outward normal direction of a light emission surface is parallel to an outward normal direction of a light-incident surface, and

wherein the light-guiding member comprises:

a rough end surface connecting with the back surface in a region of the light output surface farther than the second position, and a normal line of the end surface and a normal line of the back surface intersect each other at a negative side of the axis, and

scatter dots provided on the back surface in order to scatter guided light, a distribution of the scatter dots being rarefactional when the scatter dots are closer to the axis and condensational when the scatter dots are farther from the axis

wherein the back surface comprises a flat surface portion extending from the light-incident surface to said first position; and

wherein the light output surface comprises a flat surface portion extending from the light-incident surface to said second position, and wherein the flat surface portion of the back surface is substantially parallel to the flat surface portion of the light output surface.

9. The light-guiding member according to claim 8, wherein the light-guiding member is in a shape of rotation symmetric about the axis.

10. The light-guiding member according to claim 8, wherein

the light-guiding member has a hollow hole whose center is at the axis for accommodating a light source that is provided in the hollow hole, and emits light toward a side surface of the hollow hole.

11. The light-guiding member according to claim 8,

wherein the scatter dots of the light-guiding unit form scatter units for scattering incident light, and

wherein a coverage factor ρ

(r) of the scatter units at a distance r from the axis satisfies a following expression,

12. The light-guiding member according to claim 11, wherein the coverage factor ρ

(r) of the scatter units at the distance r from the axis satisfies a following expression,

13. The light-guiding member according to claim 12, wherein the scatter units are in a circular shape having a diameter D, and where a pitch P₁ of a radial direction of the scatter units is constant, a pitch P₂ (r) in an azimuth direction of the scatter units at the distance r from the axis satisfies a following expression,

14. The light-guiding member according to claim 10, comprising a heat radiation unit, wherein

a joint unit is connected to the heat radiation unit, and the light source is provided on the joint unit, and the joint unit is provided in the hollow hole, and

the joint unit is partially provided with a threading processed portion, and the light-guiding member is fixed, in a sandwiched manner, by a plurality of nuts corresponding to the threading processed portion.

17. An illumination device comprising a point light source and a light-guiding unit,

wherein the light-guiding unit is disc-shaped and is rotationally symmetrical about an axis, and the point light source is disposed in a central portion the light-guiding unit,

wherein the light-guiding unit has a light output surface, a back surface, and a curved surface,

wherein the back surface has a first position that is away by a first distance from the axis,

wherein the light output surface has a second position that is away by a second distance from the axis,

wherein the curved surface is at an outer periphery of the back surface,

wherein an intersection of the axis and the back surface is an origin point, a direction of the axis from the back surface to the light output surface is positive, a normal line of the curved surface intersects with the axis at a positive side of the axis, and an angle formed by a normal line vector of the light output surface at the second position in a direction toward the light output surface from the back surface and a vector in a direction from the curved surface to the second position is equal to or more than a critical angle,

wherein a light that is totally reflected off the curved surface comes into the light output surface at an angle less than the critical angle,

wherein light sources are arranged with a regular interval in a ring shape manner so that an outward normal direction of a light emission surface is parallel to an outward normal direction of a light-incident surface, and

wherein the light-guiding unit comprises:

a rough end surface connecting with the back surface in a region of the light output surface farther than the second position, and a normal line of the end surface and a normal line of the back surface intersect each other at a negative side of the axis, and

scatter dots provided on the back surface in order to scatter guided light, a distribution of the scatter dots being rarefactional when the scatter dots are closer to the axis and condensational when the scatter dots are farther from the axis

wherein the back surface comprises a flat surface portion extending from the light-incident surface to said first position; and

wherein the light output surface comprises a flat surface portion extending from the light-incident surface to said second position, and wherein the flat surface portion of the back surface is substantially parallel to the flat surface portion of the light output surface.

18. An illumination device comprising a point light source and a light-guiding unit,

wherein the light-guiding unit is disc-shaped and is rotationally symmetrical about an axis, and the point light source is disposed in a central portion the light-guiding unit,

wherein the light-guiding unit has a light output surface, a back surface, a curved surface, and a rough surface that is angled relative to the axis,

wherein the back surface has a first position that is away by a first distance from the axis,

wherein the light output surface has a second position that is away by a second distance from the axis,

wherein the curved surface is in a region of the back surface farther from the axis than the first position,

wherein an intersection of the axis and the back surface is an origin point, a direction of the axis from the back surface to the light output surface is positive, a normal line of the curved surface intersects with the axis at a positive side of the axis, and an angle formed by a normal line vector at the second position in a direction toward the light output surface from the back surface and a vector in a direction from the curved surface to the second position is equal to or more than a critical angle,

wherein the rough surface is in a region of the light output surface farther than the second position on the light output surface, and light that is totally reflected off the curved surface is diffused and transmitted through the rough surface,

wherein light sources are arranged with a regular interval in a ring shape manner so that an outward normal direction of a light emission surface is parallel to an outward normal direction of a light-incident surface, and

wherein the light-guiding unit comprises:

a rough end surface connecting with the back surface in a region of the light output surface farther than the second position, and a normal line of the end surface and a normal line of the back surface intersect each other at a negative side of the axis, and

scatter dots provided on the back surface in order to scatter guided light, a distribution of the scatter dots being rarefactional when the scatter dots are closer to the axis and condensational when the scatter dots are farther from the axis

wherein the back surface comprises a flat surface portion extending from the light-incident surface to said first position; and

wherein the light output surface comprises a flat surface portion extending from the light-incident surface to said second position, and wherein the flat surface portion of the back surface is substantially parallel to the flat surface portion of the light output surface.

19. A light-guiding member comprising a light output surface, a back surface, a rotationally symmetric shape, and a curved surface,

wherein the light-guiding member is disc-shaped and is rotationally symmetrical about an axis,

wherein the back surface has a first position that is away by a first distance from the axis,

wherein the light output surface has a second position that is away by a second distance from the axis,

wherein the curved surface is disposed at an outer periphery of the back surface,

wherein an intersection of the axis and the back surface is an origin point, a direction of the axis from the back surface to the light output surface is positive, a normal line of the curved surface intersects with the axis at a positive side of the axis, and an angle formed by a normal line vector at the second position in a direction toward the light output surface from the back surface and a vector in a direction from the curved surface to the second position is equal to or more than a critical angle,

wherein a light that is totally reflected off the curved surface comes into the light output surface at an angle less than the critical angle,

wherein light sources are arranged with a regular interval in a ring shape manner so that an outward normal direction of a light emission surface is parallel to an outward normal direction of a light-incident surface, and

wherein the light-guiding member comprises:

a rough end surface connecting with the back surface in a region of the light output surface farther than the second position, and a normal line of the end surface and a normal line of the back surface intersect each other at a negative side of the axis, and

scatter dots provided on the back surface in order to scatter guided light, a distribution of the scatter dots being rarefactional when the scatter dots are closer to the axis and condensational when the scatter dots are farther from the axis

wherein the back surface comprises a flat surface portion extending from the light-incident surface to said first position; and

wherein the light output surface comprises a flat surface portion extending from the light-incident surface to said second position, and wherein the flat surface portion of the back surface is substantially parallel to the flat surface portion of the light output surface.

20. A light-guiding member comprising a light output surface, a back surface, a curved surface, and a rough surface,

wherein the light-guiding member is disc-shaped and is rotationally symmetrical about an axis, and the rough surface is angled relative to the axis,

wherein the back surface has a first position that is away by a first distance from the axis,

wherein the light output surface has a second position that is away by a second distance from the axis,

wherein the curved surface is disposed at an outer periphery of the back surface,

wherein an intersection of the axis and the back surface is an origin point, a direction of the axis from the back surface to the light output surface is positive, a normal line of the curved surface intersects with the axis at a positive side of the axis, and an angle formed by a normal line vector at the second position in a direction toward the light output surface from the back surface and a vector in a direction from the curved surface to the second position is equal to or more than a critical angle,

wherein the rough surface is in a region of the light output surface farther than the second position on the light output surface, and light that is totally reflected off the curved surface is diffused and transmitted through the rough surface,

wherein light sources are arranged with a regular interval in a ring shape manner so that an outward normal direction of a light emission surface is parallel to an outward normal direction of a light-incident surface, and

wherein the light-guiding member comprises:

a rough end surface connecting with the back surface in a region of the light output surface farther than the second position, and a normal line of the end surface and a normal line of the back surface intersect each other at a negative side of the axis, and

scatter dots provided on the back surface in order to scatter guided light, a distribution of the scatter dots being rarefactional when the scatter dots are closer to the axis and condensational when the scatter dots are farther from the axis

wherein the back surface comprises a flat surface portion extending from the light-incident surface to said first position; and

wherein the light output surface comprises a flat surface portion extending from the light-incident surface to said second position, and wherein the flat surface portion of the back surface is substantially parallel to the flat surface portion of the light output surface.