GB2349978A

GB2349978A - A light emitting device

Info

Publication number: GB2349978A
Application number: GB9910789A
Authority: GB
Inventors: Fu-Kuo Huang
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-07-06
Filing date: 1999-05-10
Publication date: 2000-11-15
Also published as: GB9910789D0; JP2000036201A; FR2794537B3; BR9901964A; DE19923954A1; FR2794537A1

Abstract

A light emitting method for emitting light is characterised in that, a primary light source 23 emitting primary light 22 activates a secondary light source 24 to emit secondary light 25 of a colour different from that of the primary light. A blue led may be used to pump a layer of transitional metal compound, transitional complex metal compound, azo compound, or a variety of fluorescent or phosphate materials to produce a secondary light source. The secondary light produced may be orange, blue or red. The primary and secondary light sources may be mixed, the resulting light 27 may be for example white or violet light. A further layer of coloured material 31 may be used to filter the white light in order to produce light having the same colour as that of the further layer of coloured material.

Description

2349978 ELECTROMAGNETIC WAVE EMISSION BASED ON ENERGY LEVEL TRANSITION

ACTIVATED BY LIGHT INCIDENCE

FIELD OF THE INVENTION

The present invention generally relates to a device and method for generating light of desired color, particularly to a device and method for activating one type of material to emit secondary light of a desired color, by applying primary light thereto.

BACKGROUND OF THE INVENTION

Conventionally it always requires either extremely high manufacturing development cost or significant price of sacrificing quality, to make a LED (light emitting diode) capable of emitting light of very high frequency such as blue and violet light, or to make a EL (electro-luminscence) capable of emitting red and violet light.

SUMMARY OF THE INVENTION

A general object of the present invention is to provide a simple and economic device and method for obtaining light of desired colors.

A particular object of the present invention is to provide a simple and economic device and method for obtaining light of particular colors such as blue and violet light.

An embodiment of the present invention may be a light emitting method for emitting light, which is characterized in that a primary light source emits primary light to activate a secondary light source to emit secondary light of a I color different from that of the primary light. The secondary light source is activated to have the energy level of electrons therein changed for emitting the secondary light. This is a result of the fact that the electrons of the secondary light source as a whole are activated to be at a higher energy level than natural and stable status. Obviously there -shall be energy release when part or all of the electrons return to natural / stable status from the higher energy level which is unstable. The secondary light is thus generated as a result of the energy release.

The primary light source may be selected from among an electroluminescent (EL) source and a light emitting diode (LED). The primary light source and the secondary light source are usually different in the structure, shape, and size of molecule crystal lattice thereof The secondary light source may be selected from among transitional metal compound, transitional complex metal compound, azo compound, and a variety of fluorescent or phosphate materials, Another embodiment of the present invention may be a light emitting device for emitting light of various colors, which comprises:

a primary light source for emitting primary light; and a secondary light source receiving the primary light to emit secondary light of a color different from that of the primary light.

Obviously the primary light source may also be selected from among an electro-luminescent (EL) source and a light ernitting diode (LED), and the primary light activates the secondary light source to emit secondary light after being received thereat the secondary light source. The secondary light source is an approximately flat layer of material with electronic energy levels easily activated, whereby t lie secondary light source is easily activated to emit the secondary light.

2 The primary light source and the secondary light source for this embodiment are also different in the structure, shape, and size of molecule crystal lattice thereof The secondary light source may also be selected from among transitional metal compound, transitional complex metal compound, azo compound, and a variety of fluorescent or phosphate materials. - If the primary light reaching the secondary light source is fully absorbed by the secondary light source, the color of the secondary light is determined according to the color of molecules of the secondary light source.

If the primary light reaching the secondary light source is partially absorbed by the secondary light source, part of the primary light not absorbed penetrates the secondary light source, and another part of the primary light which is absorbed by the secondary light source activates the secondary source to emit secondary light, the part of the primary light penetrating the secondary light source and the secondary light mix together to form a compound light. If the primary light and the secondary light are complementary colors, the compound light is white.

The embodiment may further comprise a layer of colored material for receiving the white compound light to emit light of a color determined according to the color of the colored material. Practically the embodiment may be so configured that the layer of colored material receiving the white compound light may emit light of a color the same as that of the colored material.

The present invention may best be understood through tile following description with reference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

3 Fig. I is for illustrating a typical transition mode between different energy levels for the electrons (or molecules) of material.

Fig. 2 shows an embodiment comprising a primary light source and a secondary light source.

Fig. 3 shows another embodiment further comprising a layer of colored material in addition to a primary light source and a secondary light source.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fig. I shows a typical energy level transition for electrons (or molecules) of to one type of material, such as the secondary light source according to the present invention, which is activated by external energy applied thereto. The status of raising (E2-EO = E20) energy level from EO to E2 as a result of the external energy applied thereto is usually unstable, and shall lead to energy release E21 (= E2-EI) in response to the transition from energy level E2 to El (may be due to variation of the externally applied energy, such as reduction or removal of the applied energy). Energy release E21 can be in the form of light emission such as the secondary light in the embodiment of the present invention. The energy level transition ElO (=EI-EO) may be in the form of heat dissipation. The externally applied energy for leading to the energy level transition E20 can be in the form of light such as the primary light applied to the secondary light source according to the present invention.

When activated by external energy, the transitional metal compound or transitional complex metal compound which can be used as secondary light sources, will have electrons in P orbit thereof promoted to D orbit thereof This is because some electrons originally residing in crowded P orbit tend to move between P orbit and D orbit, some even tend to reside in the sparse D 4 orbit, and thereby the electrons as a whole are easily activated. Due to higher cost, the transitional metal compound or transitional complex metal compound are usually replaced by azo compound or fluorescent material.

Shown in Fig. 2 is an embodiment of a light emitting device / method according to the present invention, wherein a primary light source 23 in the form of a layer of material such as a conventional light emitting device, is covered by a layer of secondary light source 24 such as transitional metal compound, transitional complex metal compound, azo compound, or a variety of fluorescent or phosphate materials. Primary light source 23 emits primary light 22 to activate secondary light source 24 so that the electrons (or molecules) of secondary light source 24 are put at an unstable energy level such as E2 in Fig. 1, The energy release of secondary light source 24 as a result of the energy level transition from the unstable level E2 to another level El, such as E21 in Fig. 1, appears as secondary light 25 emitted from secondary light source 24.

It must be noted that the frequency of secondary light 25 varies with the structure, shape, size, and oscillating frequency of molecule crystal lattice of secondary light source 24, hence the embodiment may be so configured (proper selection of material to be the secondary light source, for example) that the color of secondary light 25 which corresponds to (or determined according to) the frequency of secondary light 25 is what we desire. Because the cost to acquire material for making secondary light source 24, primary light source 23, and for forming a configuration to emit light of desired colors is cheap, it shall be clear the present invention can provide a cost-effective device and method for generating light of desired colors by applying to secondary light source 24 a beam of light which can be easily and econornically generated by conventional devices.

The intensity of the primary light emitted by primary light source 23 and the thickness of secondary light source 24 can be so adjusted that part of the primary light is absorbed by secondary light source 24 to activate secondary light source 24 to emit secondary light 25, while another part 26 of the primary light 22 penetrates secondary light source 24 to mix together with secondary light 25 for forming a compound light 27 of a color different from that of secondary light 25. For example, suppose primary light 22 of blue color is applied to secondary light source 24 which is composed of molecules of orange color and which can not fully absorb primary light 22 (may be because the number of molecules therein is not big enough, for instance), part of the primary light 22 of blue color thus penetrates secondary light source 24 to appear as light 26 of blue color, another part of the primary light 22 of blue color absorbed by secondary light source 24 can be deemed as if being converted into secondary light 25 of orange color. Compound light 27 of white color may be formed by mixing light 26 of blue color and secondary light 2S of orange color, because blue color and orange color are complementary. Now if a layer of colored material (for example, red material) 31 of high transparency (allow light to penetrate) as shown in Fig. 3 is used to cover secondary light source 24 from which compound light 27 of white color is emitted, the light 32 coming out of 31-- shall have its color the same as that of colored material 31..It is especially worthwhile to apply the present invention to the production of red light based on EL (electro-luminscence), as can be seen from the fact that no pure red light has ever been made on the basis of EL for lack of red fluorescent powder made on the basis of EL in the market.

It mUst be noted that the layer of colored material 31 (such as red material) usually absorbs light of all colors except the light of the color (such as red one) the same as that of colored material 3 1. If the layer of red colored material 31 is seated between primary light source 23 and secondary light source 24 in the 6 above example, the blue light will be fully absorbed, and no light will reach secondary light source 24, thereby no secondary light can be seen.

On the contrary, if the color of primary light 22 is orange and secondary light source 24 is composed of molecules of blue color in the above example, the color of compound light 27 may be either white or various kinds of blue (ranging from light blue to dark blue). If primary light 22 is of green color and secondary light source 24 is composed of either molecules of mixing both red and blue colors (red molecules and blue molecules mixing together) or molecules of violet color, secondary light 25 of violet color and high frequency, Which is very hard to obtain conventionally, can be easily generated according to the present invention.

While the invention has been described in terms of what are presently considered to be the most practical and preferred embodiments, it shall be understood that the invention is not limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.

7

Claims

WHAT IS CLAIMED IS:

1. A light emitting method for emitting light is characterized in that a primary light source ernitting primary light to activate a secondary light source to emit secondary light of a color different from that of said primary light.

2. The light emitting method according to claim I wherein said secondary light source is activated to have the energy level of electrons therein changed for emitting said secondary light.

3. The light emitting method according to claim I wherein said primary light source is selected from among an electro-luminescent (EL) source and a light emitting diode (LED).

4. The light emitting method according to claim I wherein said primary light source and said secondary light source are different in the structure, shape, and size of molecule crystal lattice thereof

5. A light emitting device for emitting light of various colors, comprising:

a primary I ight source for emitting primary light; and a secondary light source receiving said primary light to emit secondary light of a color different from that of said primary light.

6. The light ernitting device according to claim 5 wherein said primary light source is selected from among an electro-luminescent (EL) source and a 20 light emitting diode (LED).

7. The light emitting device according to claim 5 wherein said primary light activates said secondary light source to emit secondary light after being received thereat.

8. The light emitting device according to claim 5 wherein said secondary 8 light source is an approximately flat layer of material with electronic energy levels easily activated, whereby said secondary light source is easily activated to emit said secondary light.

9. The light ernitting device according to claim 5 wherein said primary light source and said secondary light source are different in the structure, shape, and size of molecule crystal lattice thereof.

10. The light ernitting device according to claim 5 wherein if said primary light reaching said secondary light source is fully absorbed by said secondary light source, the color of said secondary light is detennined according to the 10 color of molecules of said secondary light source.

11. The light emitting device according to claim 5 wherein if said primary light reaching said secondary light source is partially absorbed by said secondary light source, part of said primary light penetrates said secondary light source, and another part of said primary light which is absorbed by said secondary light source activates said secondary source to emit secondary light, the part of said primary light penetrating said secondary light source and the secondary light mix together to form a compound light.

12. The light einitting device according to claim I I wherein if said primary light and said secondary light are complementary colors, said compound light is white.

13. The light emitting device according to claim 12 further comprising a layer of colored material for receiving the white compound light to ernit light of a color determined according to the color of said colored material.

14. The light emitting device according to claim 12 further comprising a layer of colored material for receiving the white compound light to emit light of a color the same as that of said colored material.

9

15. Light emitting methods as claimed in claim 1 and as herein described.

16. Light emitting methods as as herein described with reference to the accompanying drawings.

17. Light emitting devices as claimed in claim 5 and as herein described.

18. Light emitting devices as herein described with reference to the accompanying drawings.

is - 10