Optical element and lighting device with an optical element

• US 10,180,522 B2
• Filed: 05/19/2016
• Issued: 01/15/2019
• Est. Priority Date: 11/22/2013
• Status: Active Grant

• Current Assignee: Schott AG (Carl-Zeiss-Stiftung)
• Original Assignee: Schott AG (Carl-Zeiss-Stiftung)
• Inventors: Wolfing, Bernd, Schneider, Andreas
• Primary Examiner(s): Guharay, Karabi
• Application Number:
  US15/159,361
• Publication Number:
  US 20160259109A1
• Time in Patent Office: 971 Days
• CPC Class Codes: F21Y 2113/13 comprising an assembly of point-like light sources
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0075 Arrangements of multiple light guides G02B6/0028 takes precedence

Abstract

An optical arrangement is provided that includes a first optical element comprising a light guide that has a bevel face and a second optical element. The first optical element conducts light by total internal reflection at a wall and has a light entry area defined by a non-beveled end face and a light exit area formed by a surface area of the wall at that end proximate the bevel face. The second optical element has a light entry aperture arranged on or facing the light exit area. The light entry area has a width x and the light entry aperture has a height z, which meet the following relationship:
x/z≤1.5·[tan(90°−α/2)−tan(90°−(2·[α/2+90°]−[180°−arcsin(1/n)]))]⁻¹.

Herein, α denotes the deflection angle of the light at the bevel face and n denotes the refractive index of the material of the first optical element.

Claims

1. An optical arrangement, comprising:

a first optical element in the form of or comprising a light guide obliquely beveled with a bevel face; and

a second optical element,

wherein the first optical element conducts light by total internal reflection at a wall thereof, has a light entry area defined by a non-beveled end face, and has a light exit area defined by a surface area of the wall at that end of the light guide at which the bevel face is arranged, and

wherein the second optical element has a light entry aperture defined by an end face thereof, the light entry is arranged on or faces the light exit area of the first optical element,

wherein the light entry area of the first optical element has a width x measured in a direction along an intersection of the light entry area with a plane of light deflection at the bevel face,

wherein the light entry aperture of the second optical element has a height z measured in a direction along an intersection of the light exit area of the first optical element with a plane of light deflection at the bevel face,

wherein the width x and the height z meet the following relationship;

x/z≤

1.5·

[tan(90°

−

α

/2)−

tan(90°

−

(2·

[α

/2+90°

]−

[180°

−

arcsin(1/n)]))]<sup>−

1</sup>,

wherein α

denotes a deflection angle of light at the bevel face and n denotes a refractive index of material of the first optical element, and

wherein the width x and the height z meet the following relationship;

x/z≥

0.85·

[tan(90°

−

α

/2)−

tan(90°

−

(2·

[α

/2+90°

]−

[180°

−

arcsin(1/n)]))]<sup>−

1</sup>,

2. The optical arrangement as in claim 1, wherein the deflection angle at the bevel face of the first optical element ranges from 75°

to 105°

.

3. The optical arrangement as in claim 1, wherein the light guide has the shape of a prism and the light entry area is defined by a non-beveled base of the prism.

4. The optical arrangement as in claim 1, wherein the light guide has a cross-sectional area with a shape having dimensions monotonically expanding in a direction from a surface facing away from the second optical element towards the second optical element, and strictly monotonically expanding in at least one section along this direction.

5. The optical arrangement as in claim 4, wherein the light guide has two opposite flat faces, wherein one of the faces includes the light exit area, and wherein the face that includes the light exit area is wider than the opposite face.

6. The optical arrangement as in claim 1, wherein the bevel face extends at an angle of 45°

relative to a longitudinal extension of the light guide so that light conducted in the light guide is deflected by 90°

at the bevel face.

7. The optical arrangement as in claim 6, wherein the height z and the width x meet the following relationship:

x/z≤

1.5·

[1+tan(arcsin(1/n))]<sup>−

1</sup>.

8. The optical arrangement as in claim 1, wherein the bevel face is a mirror face.

9. The optical arrangement as in claim 1, wherein the refractive index of the material of the first optical element for visible light is at least 1.4 and not more than 2.0.

10. A lighting device, comprising:

the optical arrangement as in claim 1;

a plurality of light-emitting elements that differ from each other in the color of the emitted light, wherein the plurality of light-emitting elements are arranged so as to inject light into the light entry area of the first optical element.

11. The lighting device as in claim 10, wherein the second optical element comprises a second light guide into which light is injected which is emitted from the first optical element, wherein the second light guide has light-scattering features along a longitudinal extension, which scatter the injected light out of the second light guide.

12. The lighting device as in claim 11, wherein the second optical element is formed by the second light guide and the light entry aperture is defined by an end face of the second light guide facing the light exit area of the first optical element.

13. The lighting device as in claim 11, further comprising at least two optical arrangements, wherein each of said at least two optical arrangements comprises the second light guide as the second optical element and the light guides are arranged successively so that the light entry apertures are spaced apart from each other, and wherein the first optical element of each of said at least two optical arrangements are arranged side by side so that in an intermediate space between the light entry apertures, the light exit areas are facing in opposite directions and are facing the opposed light entry apertures of the light guides.

14. An optical arrangement, comprising:

a first optical element in the form of or comprising a light guide obliquely beveled with a bevel face; and

a second optical element,

wherein the first optical element conducts light by total internal reflection at a wall thereof, has a light entry area defined by a non-beveled end face, and has a light exit area defined by a surface area of the wall at that end of the light guide at which the bevel face is arranged, and

wherein the second optical element has a light entry aperture defined by an end face thereof, the light entry is arranged on or faces the light exit area of the first optical element,

wherein the light entry area of the first optical element has a width x measured in a direction along an intersection of the light entry area with a plane of light deflection at the bevel face,

wherein the light entry aperture of the second optical element has a height z measured in a direction along an intersection of the light exit area of the first optical element with a plane of light deflection at the bevel face,

wherein the width x and the height z meet the following relationship;

x/y≤

1.5·

[tan(90°

−

α

/2)−

tan(90°

−

(2·

[α

/2+90°

]−

[180°

−

arcsin(1/n)]))]<sup>−

1</sup>,

wherein α

denotes a deflection angle of light at the bevel face and n denotes a refractive index of material of the first optical element, and

wherein the light entry aperture has a shape with an aspect ratio from 0.8;

1 to 1.2;

1 for two mutually perpendicular directions.

15. An optical arrangement, comprising:

a first optical element in the form of or comprising a light guide obliquely beveled with a bevel face; and

a second optical element,

wherein the first optical element conducts light by total internal reflection at a wall thereof, has a light entry area defined by a non-beveled end face, and has a light exit area defined by a surface area of the wall at that end of the light guide at which the bevel face is arranged, and

wherein the second optical element has a light entry aperture defined by an end face thereof, the light entry is arranged on or faces the light exit area of the first optical element,

wherein the light entry area of the first optical element has a width x measured in a direction along an intersection of the light entry area with a plane of light deflection at the bevel face,

wherein the light entry aperture of the second optical element has a height z measured in a direction along an intersection of the light exit area of the first optical element with a plane of light deflection at the bevel face,

wherein the width x and the height z meet the following relationship;

x/y≤

1.5·

[tan(90°

−

α

/2)−

tan(90°

−

(2·

[α

/2+90°

]−

[180°

−

arcsin(1/n)]))]<sup>−

1</sup>,

wherein α

denotes a deflection angle of light at the bevel face and n denotes a refractive index of material of the first optical element, and

wherein the light entry area has depth y_G and the light entry aperture has a depth y2 that define a ratio y_G/y2, the ratio being in a range from 0.85 to 1.15.

16. An optical arrangement, comprising:

a first optical element in the form of or comprising a light guide obliquely beveled with a bevel face; and

a second optical element,

wherein the first optical element conducts light by total internal reflection at a wall thereof, has a light entry area defined by a non-beveled end face, and has a light exit area defined by a surface area of the wall at that end of the light guide at which the bevel face is arranged, and

wherein the second optical element has a light entry aperture defined by an end face thereof, the light entry is arranged on or faces the light exit area of the first optical element,

wherein the light entry area of the first optical element has a width x measured in a direction along an intersection of the light entry area with a plane of light deflection at the bevel face,

wherein the light entry aperture of the second optical element has a height z measured in a direction along an intersection of the light exit area of the first optical element with a plane of light deflection at the bevel face,

wherein the width x and the height z meet the following relationship;

x/y≤

1.5·

[tan(90°

−

α

/2)−

tan(90°

−

(2·

[α

/2+90°

]−

[180°

−

arcsin(1/n)]))]<sup>−

1</sup>,

wherein α

denotes a deflection angle of light at the bevel face and n denotes a refractive index of material of the first optical element, and

wherein the following relationship applies for a ratio of the height z_a of a projection of the bevel face to the light exit area and the height z of the light entry aperture;

z_a/z≤

1.5·

[tan(α

/2)·

[tan(90°

−

α

/2)−

tan(90°

−

(2·

[α

/2+90°

]−

[180°

−

arcsin(1/n)]))]]<sup>−

1</sup>.

17. The optical arrangement as in claim 16, wherein the following relationship applies for the ratio:

z_a/z≥

0.85·

[tan(α

/2)·

[tan(90°

−

α

/2)−

tan(90°

−

(2·

[α

/2+90°

]−

[180°

−

arcsin(1/n)]))]]<sup>−

1</sup>.

18. An optical arrangement, comprising:

a first optical element in the form of or comprising a light guide obliquely beveled with a bevel face; and

a second optical element,

wherein the first optical element conducts light by total internal reflection at a wall thereof, has a light entry area defined by a non-beveled end face, and has a light exit area defined by a surface area of the wall at that end of the light guide at which the bevel face is arranged, and

wherein the second optical element has a light entry aperture defined by an end face thereof, the light entry is arranged on or faces the light exit area of the first optical element,

wherein the light entry area of the first optical element has a width x measured in a direction along an intersection of the light entry area with a plane of light deflection at the bevel face,

wherein the light entry aperture of the second optical element has a height z measured in a direction along an intersection of the light exit area of the first optical element with a plane of light deflection at the bevel face,

wherein the width x and the height z meet the following relationship;

x/z≤

1.5·

[tan(90°

−

α

/2)−

tan(90°

−

(2·

[α

/2+90°

]−

[180°

−

arcsin(1/n)]))]<sup>−

1</sup>,

wherein α

denotes a deflection angle of light at the bevel face and n denotes a refractive index of material of the first optical element, and

wherein the light guide has a cross-sectional area with a shape having dimensions monotonically expanding in a direction from a surface facing away from the second optical element towards the second optical element, and strictly monotonically expanding in at least one section along this direction.