Led with controlled angular non-uniformity. RU patent 2504047.

FIELD: physics.

SUBSTANCE: light source which uses a light-emitting diode with a wavelength converting element is configured to produce a non-uniform angular colour distribution which can be used with a specific optical device which transforms the angular colour distribution into a uniform colour distribution. The ratio of height and width for the wavelength converting element is selected to produce the desired non-uniform angular colour distribution.

EFFECT: use of controlled angular colour non-uniformity in the light source and use thereof in applications which transform the non-uniformity into a uniform colour distribution increases the efficiency of the system compared to conventional systems in which a uniform angular light-emitting diode is used.

12 cl, 10 dwg

Field of the invention

The present invention relates to diodes (LED) with the transformation of the wavelength and, in particular, to the management of the angular dependence LED to the desired uneven.

Prerequisites

In many applications in the lighting technique of gaining lighting devices, which use light emitting diodes (LEDs). As a rule, LED use the conversion of primary emissions by means of phosphor to create white light, but the phosphors can also be used to create a more saturated colors such as red, green and yellow.

The standard identified in LED problem associated with the transformation of the is unmanaged angular dependence of the color unevenness of the received light. As a rule, the wavelength of light emitted by the phosphor layer, or a light with higher values of the angles coming out of layers of phosphor is of high value, i.e., a conversion occurs more light compared with the light emitted the upper part of the phosphor layer, because the light emitted by the upper part, is more perpendicular and has less potential for conversion by means of phosphor. In the result, the color of the light emitted is the angular dependence.

Modern approaches to the problem of uneven color includes the reduction of the angular dependence. As an example, one approach is to apply the coating on the sides of the phosphor material preventing side of the light emission. Another approach is to add the scattering particles in the phosphor material to mix transformed and not transformed the lights so the color of light emitted from the side and the light emitted by up was approximately the same. Such decisions, however, the problem of the angular dependence reduce the effectiveness of the devices, and also increase the cost of production. Thus, it is desirable to create other ways to solve the angular dependence.

Light source LED contains the element that converts the wavelength, with the selected value for the height and width to obtain the desired uneven angular distribution of colors, for example, with the unbalanced Δu'v'>0,015 within the angular distribution of 0o to 90 degrees. The light source used in applications that transform unequal angle distribution color of the light source in a uniform distribution of color, for example, with the unbalanced Δu'v'<0,01. Thus, increase the efficiency of the system relative to the standard systems, constructed with the use of LEDs, which are made with the possibility of obtaining uniform angular distribution of color.

Brief description of drawings

1 is a side view of the light source which contains LED to an element converts wavelength, which has managed uneven angular distribution of the colors.

Figure 2 is represented by a shift Δu'v' depending on the angle to demonstrate the corner of uneven color of the light source figure 1.

On fig.3 and 3B shows an example of the light source, which is used in the application in flashes.

Figure 4 shows the side of the light source with configuration of the emitter.

Figure 5 presented to the other variant of the implementation of the light source which emits light with a managed irregular angular dependence of the color.

On fig.6 and 6B an example is the top view and side view multiple light sources that are used in the application of the backlighting.

Figure 7 shows a plot of the absorption curve 1 mm for PMMA polymer, which is usually used as a waveguide in use in backlighting.

On Fig.8 shows a graph that illustrates the effect of spectral absorption of the waveguide.

Figure 9 shows a graph that illustrates the color shift due to the absorption of PMMA waveguide (blue) depending on the distance.

Detailed description

1 is a side view of the light source 100, which contains a light-emitting diode (LED) 101 element that converts the wavelength 110, which has controlled uneven angular distribution of the colors. Also figure 1 shows the device 120, used light source and 100, with lens 122, located to the reflection of light from the light source 100 toward the device 120. Unit 120 may constitute an application such as applying in flashes or backlighting or other suitable application. Angular uneven color of the light source 100 is made to use with optical device 120 to a complex system, that is, the source of light 100 and device 120, was more effective than the system that contains a standard light source 100 with a uniform angular LED.

LED 101 is depicted as a device with inverted crystal with pads 102, located on the lower surface of the LED 101. Pads 102 connected with contact elements 104 on the substrate 106, which can be done, for example, ceramic or silicon. If desired, substrate 106 you can install the heat sink 108. If desired, you can use the load-bearing structures, differing from the substrate 106 and heat sink 108.

One of the options for the implementation of the LED 101 may be a blue or ultraviolet (UV) LED and can be a device with a high energy brightness, for example, of the type described in the application for patent in the US with the serial No. 10/652348 entitled «the Package for a Semiconductor Light Emitting Device» authors Frank Wall et al., filed August 29, 2003, publication no 2005/0045901, has the same patent holder, and that the present disclosure and included in this document as a reference. Diagram of angular emission LED 101 can refer to type (as shown in figure 1) or a managed type using photonic crystals, such as the lattice structure.

The LED 101 mounted element, which transforms the wavelength 110, which can be, for example, phosphor in the binder material, built in, for example, in silicon, and molded over LED 101 or in a rigid ceramic plate, which is sometimes referred to in this document as fluorescent ceramics». As a rule, the ceramic plates are separate layers and may have translucency or transparency to specific wavelengths that can reduce losses from scattering associated with opaque layers, transformative wavelength, such as uniform layers. Fluorescent ceramic layers can be stronger than a thin film or uniform layers phosphor.

Examples of phosphors that you can use in your binder material over LED 101 or fluorescent ceramics include aluminum dark red phosphors with the General formula (Lu 1-x-y-a-b Y x y Gd ) 3 (Al 1-z Ga z ) 5 O 12 :Ce a Pr b , where 0<x<1, 0<y<1, 0<z 0,1, 0<a < = 0,2, 0<b≤0,1, such as Lu 3 Al 5 O 12 :3 Ce+ and Y 3 Al 5 O 12 :Ce 3+ , which emit light in the yellow-green region; and (Sr 1-x-y-Ba x Ca-y ) 2-z Si 5-a Al a N 8-a O a :Eu z 2+ , where 0<a<5, 0<x < 1, 0<y<1, 0<z<1, such as Sr 2 Si 5 N 8 :the Eu 2+ , which radiates the light in the red range. Suitable for ceramic plate, containing Y 3 Al 5 O 12 :Ce 3+ , available for purchase at Baikowski International Corporation of Charlotte, N.C. you can Also use other green, yellow and red emitting phosphors, including (Sr 1-a+b Ca b Ba c )Si x N y O z :Eu a 2+ (a=0,002-0,2, b=0,0-0,25, c=0,0-0,25, x=1,5-2,5, y=1,5-2,5, z=1.5 to 2.5)including, for example, SrSi 2 N 2 O 2 :the Eu 2+ ; (Sr 1-u-v-x Mg u Ca v Ba x )(2 Ga-y-z Al y In z S 4 ):the Eu 2+ , including, for example, SrGa 2 S 4 :the Eu 2+ ; Sr 1-x Ba x SiO 4 :the Eu 2+ ; and (Ca 1-x Sr x )S:Eu 2+ , where 0<x<1, including for example, CaS:Eu 2+ and SrS:Eu 2+ . The corresponding arrows 114 and 115 shows a light source 100, which emits light up and to the side, where the emitted light up 114 has bluish-white color, and emitted in the direction of the light 115 has a yellowish color. Driving H is the height of the element that converts the wavelength, 110 or, more specifically, the ratio of width/height (H/W), you can control the angular dependence of light to obtain the desired number of bluish-white light 114 and yellowish light 115, which is appropriate for the product 120. As an example, not so blue use the element that converts the wavelength, 110 with the increased value of the height H, whereas for more blue light use element, which transforms the wavelength, 110 with a lower height H.

On fig.2 presented shift Δu'v' depending on the angle, which shows one possible implementation of the corner of uneven color of the light source 100. Shift Δu'v' depending on the angle is a measure of the color shift relative to the origin. As you can see on fig.2, light source creates 100 shift Δu'v'>0,015 between 0 or 90 degrees relative to the initial point 0 degrees. This is the maximum change color depending on the angle within a given angular range. On fig.2 is an example Δu'v' for another source of light 100 with blue LED and a red/green , which is made with the possibility of obtaining Δu'v'>0,05 depending on the angle. Changing, for example, the ratio H/W, you can get different maximum values Δu'v' depending on the angle, for example, the maximum value Δu'v' depending on the angle can be more than 0,015, 0,03, 0,045 or 0.06 depending on the desired application, for example, the device 120, which use light source 100. The device then 120, which use light source 100, in accordance with one of the options for implementation creates a spatial uniformity of color Δu'v' less than 0,015, for example, less than 0.01 or 0,005.

Thus, instead of trying to resolve the angular dependence of light color, light source 100 is designed for the controlled corner of colour, which optimize for a specific device 120, which use light source 100. Thus, as described above, for example, light source 100 is made with the possibility of obtaining managed corner of colour shift Δu'v'>0,015 depending on the angle, but when you use your device to 120, the device 120 creates a spatial uniformity of color Δu'v'<0,015. Depending on the requirements of the application, there are various spatial uniformity of colour, such as from Δu'v'<0.05 to Δu'v'<0,015. For example, medical monitors or other applications that require high-precision representation of color, you can create backlit in accordance with one of the variants of implementation which has Δu'v'<0,05, whereas consumer monitors you can create a backlight which has Δu'v'<0.01, and such application, as a camera flash, can be Δu'v'<0,015. When managed corner of colour can increase the efficiency of the light source 100 because there is no need to block the emission of light from the light source is 100. So, the total system performance, device containing 120 and light source 100, improved compared with systems that use uniform angular LED.

On fig.3 and 3B shows an example of the light source 100, which you can use in your device 120 type of flash, for example, for the camera. On fig.3 presented to the light source 100 with an additional control element 112, such as dichroic filter located on top of the item converting the wave-length 110. Dichroic filter 112 different transmits the light depending on the angle, which further contributes to the management of the angular dependence. Alternatively, dissipative element can be used for a corresponding reduction or control of the angular dependence. As shown in fig.2, light source creates 100 bluish-white light 114 and yellowish light 115, which is reflected reflector 122 and mixed on the depicted target 124.

If desired, the light source 100 can represent the emitter in the side (or ) is a configuration in which there is a small issue up and a significant issue in hand. Figure 4 submitted to the light source 100 in configuration of the emitter, which lacks the necessity of the top reflector on the upper surface of 110 top element of converting the wave-length 110. As shown in figure 4, chart corner of emission of the parties 110 side of the light source 100 refers to type. When replacing the top reflector on the increased height H of the element that converts the wavelength, 110 in relation to the width W element of converting the wave-length 110 (which is the embodiment equal to the width LED 101), decreases the number of reflections of light in the direction LED 101. Reflection in the side LED 101 are not effective and, consequently, reducing the reflection in the side LED 101, reduce losses in the system. In addition, increasing the height H, increase the size of the parties 110 side of the element that converts the wavelength, 110, which provides increased extraction of light parties 110 side element of converting the wave-length 110. Increasing the height H of an element that converts the wavelength, 110 in relation to the width W, light source 100 optimize for applications that require extraction of light, in contrast to the accumulation of light. For example, in applications such as optical design, flash, it is desirable to use a small source designed so that you could save a small size optics, thus accumulating the greatest amount of light and guiding light towards the target of 1.05 x 0,8 m at a distance of 1 meter. Increasing the height of the element that converts the wavelength 110, increase the amount of extracted light. The concentration of Cc in the element, transformative wavelength, you can ask to get the desired colour point for a particular application. Additionally, the element that converts the length of the wave, you can add the scattering particles to facilitate the extraction of light in air.

On fig.6 and 6B as an example presented top view and side view multiple sources of light 100, which is used in the device backlight 120. The back-light 120 remove the color, such as blue vs green/red, from one light source 100 in various locations inside the backlight. Thus, using multiple light sources 100 and managing the angular distribution of the colour of the light emitted, you can get a uniform spatial distribution of color in use in backlighting.

Figure 7 shows a plot of the absorption curve 1 mm PMMA polymer, which is usually used as a waveguide in use in backlighting. X-axis postponed wavelength, while the Y-axis postponed percentage of absorption. On Fig.8 shows a graph that illustrates the effect of spectral absorption of the waveguide, illustrates the change in the spectrum from the edge (shown curve 202) and the center (shown curve 204) 72” waveguide of PMMA. X-axis postponed wavelength, while the Y axis shows the relative spectral distribution. As seen in Fig.8, centre 204 spectrum in the center of the waveguide contains not so blue light, as the edge 202 waveguide. Figure 9 shows a graph illustrating theoretical color shift due to the absorption of a waveguide of PMMA (blue) in bilateral backlight conditions depending on the distance to the standard light source which has a uniform angular and spatial input. On the X-axis position on the backlight diagonal inches, while the Y-axis postponed change in Δu'v' from the center to the edge. As shown, a standard waveguide using a standard uniform angular light source has Δu'v' more than 0.01 and actually comes to 0.02.

Thus, as you can see from the graphs Fig.7, 8 and 9, more blue light is absorbed depending on the distance waveguide PMMA, resulting in such waveguide is not so blue light in the center of the waveguide, as on the edges of the waveguide. In addition, as shown in figure 9, the shift Δu'v' varies approximately linearly with the distance. Using controlled uneven angular distribution color of the light source 100, more blue light can be emitting directly toward the center of the waveguide to compensate for the blue absorption material PMMA to obtain a more uniform distribution of color in use in backlighting. As an example, figure 10 provides a theoretical absorption waveguide of PMMA is similar to the presented figure 9, but using a light source, which has managed the corner uneven color shift Δu'v'>0.01 depending on the angle. As shown in figure 10, the resulting spatial uniformity of color has Δu'v' less than 0.01.

Although the present invention to clarify illustrated in connection with specific cases of the implementation of the present invention is not limited to them. Various improvements and modifications can be run, not deviating from the volume of the invention. Consequently, the nature and scope of the accompanying formula of the invention is not limited to the previous description.

1. Light source which contains: light-emitting diode; element, which transforms the wavelength above the diode element, which transforms the wavelength, which has a height and width, where the ratio of height and width choose to receive the light with the desired uneven angular distribution of the colors Δu'v'>0,015 within the angular distribution from 0 to 90 degrees.

2. The device according to claim 1, which further comprises a reflector to reflect the emitted light up and emitted in the direction of the light from the element that converts the wavelength where the emitted light up and emitted in the direction of the light have desired uneven angular distribution of the colors.

3. The device according to claim 2, in which the reflector focuses emitted light up and emitted in the direction of the light with the desired uneven angular distribution of the colors on the target, where the emitted light up and emitted in the direction of the light is mixed to a uniform spatial distribution of the colors on the target with the unbalanced Δu'v'<0,015.

4. The device according to claim 3, in which a light source is used as a flash.

5. The device according to claim 1, which further comprises optical device connected to the reception of the light emitted by an element that converts the length of the wave is desired uneven angular distribution color transform into a uniform color distribution in the optical device with the unbalanced Δu'v'<0,01.

6. Device according to claim 5, in which the optical device is a back-lighting using waveguide and where the device additionally contains multiple light sources.

7. The device according to claim 1, which further comprises layered element, connected with the element that converts wave-length.

8. The device of claim 1 in which the element that converts the wavelength, contains luminescent.

10. The method of claim 9, which additionally contains the desired transformation uneven angular distribution color of the light source in a uniform spatial distribution of colors in the optical application with the unbalanced Δu'v'<0,015.

11. The method according to paragraph 10, in which the optical application is the use in backlighting.

12. The method according to paragraph 10, in which the optical application is the application in flashes.