WO2010061318A1

WO2010061318A1 - A light emitting device

Info

Publication number: WO2010061318A1
Application number: PCT/IB2009/055157
Authority: WO
Inventors: Jian Zhang; Gang Wang; Wen SUN
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2008-11-28
Filing date: 2009-11-19
Publication date: 2010-06-03

Abstract

This invention proposes an improved device (20, 40) comprising a curved light entrance portion (201, 401) for receiving a light beam; and a ring-shaped portion (202, 402) for guiding and emitting the light beam, wherein said ring-shaped portion is connected to the curved light entrance portion. With this curved light entrance portion, a uniform light effect is obtained.

Description

A LIGHT EMITTING DEVICE

FIELD OF THE INVENTION

This invention relates to a light emitting device, more specifically to a ring-shaped light emitting device.

BACKGROUND OF THE INVENTION

In order to embellish the appearance of products or implement indicative functions, a growing number of designers are inclined to add light emitting units to their designs. Moreover, as one of the most popular geometric elements, the ring shape has been widely used in various designs. For example, ring-shaped emitting devices outlining rotary switches have been applied to facilitate user operation in a dark environment. In such applications, light guide technology is a promising and widely recognized option.

An example of the ring-shaped light emitting device is shown in FIGl. In FIGl, a light emitting device 10 is composed of a straight light entrance unit 101 and a ring-shaped light emitting unit 102. The straight light entrance unit is connected to the ring-shaped light emitting unit. The straight light entrance unit is capable of introducing light from a light source 11 into the ring-shaped light emitting unit for emitting the light from the emitting surface of the ring-shaped light emitting unit. However, when the light beams travel from the light source 11 to the ring-shaped light emitting unit, the connecting part of the straight light entrance unit and the ring-shaped light emitting unit often has a high-brightness area, such as the area of the inner circumference 104 and/or the area of the outer circumference 103. This high-brightness effect makes the user's eye feel uncomfortable and the nonuniform light effect adversely affects the decoration function.

SUMMARY OF THE INVENTION

This invention proposes an improved light emitting device. The proposed device comprises a curved light entrance portion for receiving a light beam, and a ring-shaped portion for guiding and emitting said light beam, wherein said ring-shaped portion is connected to the curved light entrance portion.

Since a curved light entrance portion is connected to the ring-shaped portion, the light beam will not be refracted particularly by the connecting part of the curved light entrance portion and the ring-shaped portion, and as a result, the high-brightness effect at the connecting area is avoided.

This invention also proposes a product comprising the improved light emitting device.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become more apparent from the following detailed description of the various aspects of the invention, taken in conjunction with the accompanying drawings, in which:

FIG.1 depicts a ring-shaped light emitting device according to the prior art;

FIG.2 depicts a three-dimensional stereogram of a device 20 according to an embodiment of this invention; FIG.3 depicts a top view of the device 20;

FIG.4 depicts a top view of a device 40 according to another embodiment of this invention;

FIG.5 A shows a light effect of light beams travelling in the prior art device in FIG.1 ;

FIG.5B shows a light effect of light beams travelling in the device of FIG.2;

FIG.5C shows a light effect of light beams travelling in the device of FIG.4.

DETAILED DESCRIPTION OF THE INVENTION

FIG.2 is a three-dimensional stereogram of a device 20 according to an embodiment of this invention; and FIG.3 is a top view of the device 20. Now referring to FIG.2 and FIG.3, the light emitting device 20 comprises a curved light entrance portion 201 and a ring-shaped portion 202. The curved light entrance portion 201 has an open end AC for receiving light beam 211 from a light source 21 and a connecting end BD for interconnecting the curved light entrance portion 201 and the ring-shaped portion

202. The curved light entrance portion 201 is capable of guiding the light beam 211 through the open end

AC to the connecting end BD, and subsequently the light beam enters the ring-shaped portion 202. The ring-shaped portion 202 is used for guiding and emitting the light beam 211. When the light beam 211 enters the ring-shaped portion 202, the light beam 211 travels throughout the ring-shaped portion 202 via total inner reflection.

The ring-shaped portion 202 is formed by an outer surface 202a, an inner surface 202b, an upper surface 202c and a lower surface 202d. The ring-shaped portion 202 has an emitting surface, for example, the upper surface 202c is made so as to be the emitting surface. In order to emit a light beam, out-coupling structures are required on the emitting surface 202c, for example, dot patterns made by laser carving or silk screen printing or injection moulding. To make an out-coupling structure is well known technology; therefore, no details will be given here.

The curved light entrance portion 201 is connected to the outer surface 202a of the ring-shaped portion 202. The curved light entrance portion 201 is formed by an outer surface 201a, an inner surface 201b, an upper surface 201c and a lower surface 201d. The outer surface 201a connects to the outer surface 202a at position B, and the inner surface 201b connects to the outer surface 202a at position D. The upper surface 201c connects to the upper surface 202c, and preferably, the upper surface 201c extends along the direction of the upper surface 202c. The lower surface 20 Id connects to the lower surface 202d, and preferably, the lower surface 20 Id extends along the direction of the lower surface 202d.

The light source 21 is responsible for emitting light toward the curved light entrance portion 201. It can be any type of light source, for example: LED, bulb, fluorescent lamp, etc.

The inner surface 201b of the curved light entrance portion and the outer surface 202a of the ring-shaped portion jointly form a gap between said light entrance portion and said ring-shaped portion, i.e. curve CD does not overlap the outer circumference of the ring- shaped portion 202; and they are separated from position D. Optionally, the outer surface 201a and the inner surface 201b may be circular in shape. In other words, Curve AB, which is the projection of the outer surface 201a from the top view, is part of a circle i.e. an arc. Similarly, Curve CD is also part of a circle, i.e. it is an arc. Advantageously, the outer surface 201a may be tangent with the outer surface 202a; i.e. the circle defined by the outer surface 202a is inscribed with the circle defined by curve AB. Similarly, the extension of the inner surface 201b may also be tangent with the inner surface 202b. That is, the circle defined by the inner surface 202b is inscribed with the circle defined by curve CD.

According to this invention, the cross section of the ring-shaped portion along the direction of 0-0 is not limited. It may be any shape, such as, a rectangle, a square, a trapezium, a polygon, an ellipse or even a circle.

FIG.4 depicts a light emitting device 40 according to another embodiment of this invention. The device 40 is formed by the curved light entrance portion 401 and the ring- shaped portion402. 401a is the outer surface of the curved light entrance portion 401. 401b is the inner surface of the curved light entrance portion 401. 401c is the upper surface of the curved light entrance portion 401. Curve FNMKE is the projection of the outer surface 401a from the top view. Curve FHJFG is the projection of the inner surface 401b from the top view. 402a is the outer surface of the ring-shaped portion 402. Curve FHJFG is composed of curve

FHJF and curve FG Curve FHJF is the same circle as the circle defined by the outer surface 402a, i.e. part of the inner surface 401b is superposed with the outer surface 402a of the ring- shaped portion 402. The outer surface 401a has a spiral shape, which means that curve FNMKE is a spiral. For example, it may be an Archimedes spiral. Similarly, except for the part which is superposed with the outer surface 402a, the inner surface 401b may also have a spiral shape, i.e. curve FG is a spiral.

Curve FG and curve FN jointly form a gap, meaning that curve FG and curve FN (curve FN is part of the outer circumference of curved light entrance portion 401) are not in superposition. As the inner surface FHJF is situated inward of curve FN, curve FG also forms a gap with curve FH. In other words, the inner surface 401b and the outer surface 402a also form a gap.

According to this invention, there are numerous combinations regarding the shape of the inner surface and the shape of the outer surface of the curved light entrance portion. For example, the outer surface of the curved light entrance portion may be circle or spiral- shaped; the inner surface of the curved light entrance portion may be circle or spiral-shaped or plane- shaped. Here, plane-shaped means that the inner circumference of the curved light entrance portion is a plane, i.e. line CD in FIG.2 or line FG in FIG.4 is a straight line. If the curved light entrance portion is very short, the impact on the light guiding effect of the inner circumference of the curved light entrance portion, being either a curve or a straight line, is not big.

However, the shape of the outer circumference of the curved light entrance portion is very important. As mentioned above, the outer circumference of the curved light entrance portion should be a curved surface, i.e. line AB and line EKMNF is a curve, such as part of a circle, a spiral. The experiment indicates that when the curvature of the outer circumference of the curved light entrance portion is very close to that of the outer circumference of the ring- shaped portion, a better light guiding effect will be obtained.

FIG.5A illustrates the path of light beams in the prior art device described in FIG.1. In FIG.5A, it is clear that at the connecting part, many light beams are refracted out. As a result, at the connecting end, there is a high-brightness area. FIG.5B illustrates the path of light beams in the device of FIG.2. It can be seen that the light beams refracted from the connecting part in FIG5B are smaller in number than in FIG.5A. FIG5C illustrates the path of light beams in the device of FIG.4. In FIG.5C, the light beam is refracted evenly from the whole outer circumference of the light emitting device, and thus the problem of high brightness at the connecting part is solved. From these three examples, the conclusion can be drawn that the light effects of FIG.5B and FIG.5C are much more uniform than the light effect of FIG.5A.

This invention also proposes a product having at least one round surface, said product comprising the above described device 20, or device 40. The device 20 or the device 40 surround said round surface. For example, the product could be a clock or watch with a round plate; a speaker; or any other electronic device with a round surface, like a DVD, CD, power amplifier, etc. The device 20 or the device 40 could surround for example the round plate of a clock or watch, or a rotary knob or round screen of any electronic device, etc.

The remarks made hereinabove demonstrate that the detailed description with reference to the drawings, illustrate rather than limit the invention. There are numerous alternatives, which fall within the scope of the appended claims. Any reference sign in a claim should not be construed as limiting the claim. The word "comprising" does not exclude the presence of other elements or steps than those listed in a claim. The word "a" or "an" preceding an element or step does not exclude the presence of a plurality of such elements or steps.

Claims

1. A device (20, 40) comprising: a curved light entrance portion (201, 401) for receiving a light beam (211); - a ring-shaped portion (202, 402) for guiding and emitting said light beam (211), said ring-shaped portion (202, 402) being connected to said curved light entrance portion (201, 401).

2. A device according to claim 1, wherein the inner surface (201b, 401b) of said curved light entrance portion has a circular shape.

3. A device according to claim 1, wherein the inner surface (201b, 401b) of said curved light entrance portion has a spiral shape.

4. A device according to claim 1, wherein the inner surface (201b, 401b) of said curved light entrance portion has a planar shape.

5. A device according to claim 1, wherein said curved light entrance portion is connected to the outer surface of said ring-shaped portion.

6. A device according to claim 5, wherein the inner surface (201b, 401b) of said curved light entrance portion and the outer surface (202a, 402a) of said ring-shaped portion jointly form a gap between said light entrance portion and said ring-shaped portion.

7. A device according to claim 5, wherein the extension of the inner surface (201b) of said curved light entrance portion is tangent with the inner surface (202b) of said ring-shaped portion.

8. A device according to claim 5, wherein the outer surface (201a) of said curved light entrance portion is tangent with the outer surface (202a) of said ring-shaped portion.

9. A device according to any one of claims 1 to 8, wherein the outer surface (201a, 401a) of said curved light entrance portion has a circular shape.

10. A device according to any one of claims 1 to 8, wherein the outer surface (201a, 401a) of said curved light entrance portion has a spiral shape.

11. A product having at least one round surface, wherein said product comprises a device (20, 40) as claimed in claim 1, said device (20, 40) surrounding said round surface.