KR20130027740A - Lighting device and lighting control method - Google Patents

Abstract

PURPOSE: A lighting device and a lighting device controlling method thereof are provided to improve lighting efficiency and color rendering properties by radiating a white light similar to natural light. CONSTITUTION: A first PWM controller(200) modulates the pulse width and size of current applied to first or fourth white LEDs(133). A second PWM controller(300) modulates the pulse width and size of current applied to second and fourth white LEDs. The lighting device moves X and Y coordinates of a 1931 CIE chromaticity diagram region due to the mixture of lights radiated at the first and fourth white LEDs by the modulation of the size and pulse width of the current of the first and second controllers to a black body radiant curve line of the 1931 CIE chromaticity diagram region. [Reference numerals] (200) First PWM controller; (300) Second PWM controller; (400) First controller; (500) Second controller

Description

Lighting device and lighting control method {LIGHTING DEVICE AND LIGHTING CONTROL METHOD}

Embodiments relate to a lighting apparatus and a lighting control method.

Since white LEDs, LCD backlight units, carreraphone flashes, electronic displays, and lighting have been expanded in their application areas, research and development on white LEDs have been actively conducted.

As a method of manufacturing a white light emitting device, a method using a single chip to combine a fluorescent material on a blue or UV LED chip to obtain a white and a method using a multi-chip emits light of two or three different wavelengths There is a method of obtaining white by combining LED chips.

One of the methods of implementing white using multi-chips is a combination of three chips, R, G, and B. In each chip, the operating voltage is uneven and the output of each chip changes according to the ambient temperature. There is a problem that the coordinates are different. Therefore, as a method of implementing a white light emitting device, a method using a single chip, which is relatively easy to manufacture and has excellent efficiency, is frequently used. For example, a white LED is produced by combining a blue light emitting LED and a phosphor excited by the blue light emitting LED to emit yellow light. In addition, there is a method of realizing white by mixing light of a plurality of wavelengths excited by the UV light emitting LED and the UV light emitting LED, wherein the UV light is used as a whole to excite the fluorescent material and directly to form white light It does not contribute.

On the other hand, as an index for analyzing the characteristics of the white light, there are Correlated Color Temperature (CCT) and Color Rendering Index (CRI). The correlated color temperature indicates that the temperature of the black body is equal to the temperature of the object when the object is shining with visible light and the color is the same as the color of the black body of a certain temperature. Even with the same white light, if the color temperature is low, the color feels warmer and if the color temperature is high, the color can be adjusted, so that various colors can be produced by adjusting the color temperature.

In addition, the color rendering index indicates the degree to which the color of the object is different when the sunlight is irradiated to the object and when the artificial light is irradiated, and the CRI is defined as 100 when the color of the object is the same as in the sunlight. That is, the color rendering index is an index indicating how close the color of the object is to the color of the object in sunlight under artificial illumination, and has a numerical value ranging from 0 to 100. White light sources with a CRI approaching 100 feel closer to sunlight. The CRI of incandescent bulbs is 80 or more, and the CRI of fluorescent lamps is 75 or more, whereas the CRI of commercially available white LEDs is about 70-75.

Therefore, even the same white light is required to increase the color rendering to feel close to natural light.

Korean Laid-Open Patent Publication No. 10-2007-0080694 (published: August 13, 2007)

The embodiment provides an illumination device and an illumination control method that emit white light close to natural light.

One embodiment, the first to fourth white light emitting device disposed on the substrate; First and second pulse width modulation controllers for pulse width modulating currents applied to the first and second white light emitting devices, respectively; And first and second controllers respectively controlling currents applied to the third and fourth white light emitting devices having a difference in color temperature from the first and second white light emitting devices. The x, y coordinates in the area on the 1931 CIE chromaticity diagram by mixing the pulse width modulation of the pulse width modulation controller and the light emitted from the first to fourth white light emitting elements by the control of the first and second controllers, 1931 Provides an illumination device that moves on a blackbody radiation curve in an area on a CIE chromaticity diagram.

Here, the first to the fourth white light emitting device, the first white light emitting device, the second white light emitting device, the third white light emitting device, the linear array arranged in the order of the fourth white light emitting device, illumination Provide a device.

The color temperature of the first and third white light emitting devices is higher than that of the second and fourth white light emitting devices.

In another embodiment, the 1931 CIE is obtained by applying first and second set currents to the first and second white light emitting devices disposed on the substrate, respectively, by mixing light emitted from the first and second white light emitting devices. A first step of obtaining x, y coordinates in the area on the chromaticity diagram; The first and fourth white currents may be applied to the third and fourth white light emitting elements disposed on the substrate, respectively, to the third and fourth white light emitting elements having a difference in color temperature from the first and second white light emitting elements. A second step of obtaining x, y coordinates in an area on a 1931 CIE chromaticity diagram by mixing light emitted from the light emitting device; And pulse width modulating a current applied to at least one light emitting device among the first and second white light emitting devices, and controlling a current applied to at least one light emitting device among the third and fourth white light emitting devices. And a third step of moving the x and y coordinates by mixing the light emitted from the first to fourth white light emitting elements onto a blackbody radiation curve in the region on the 1931 CIE chromaticity diagram. .

Here, in the third step, the current applied to the first to fourth white light emitting device is independently controlled, provides an illumination control method.

Here, in the third step, as the pulse width of the current applied to the first or second white light emitting device is smaller, the x and y coordinates of the x, y coordinates are provided to move in a small direction do.

According to an embodiment, by providing a lighting device and an illumination control method for emitting white light close to natural light by making the color coordinates of the light emitted from the white light emitting element on a black body radiation curve in the region on the 1931 CIE chromaticity diagram, further improving the light efficiency and color rendering properties. You can improve further.

1 is a schematic view of a lighting apparatus according to an embodiment.
2 is a graph illustrating the magnitude of current by pulse width modulation according to an embodiment.
3 is a graph illustrating a change in color coordinates due to the pulse width modulation of FIG. 2.
4 is a view for explaining a lighting control method on a black body radiation curve according to an embodiment.
5 is a diagram illustrating a principle of having color coordinates on a black body radiation curve according to an embodiment.

The thickness and size of each layer in the drawings are exaggerated, omitted, or schematically shown for convenience and clarity of explanation. In addition, the size of each component does not entirely reflect the actual size.

In the description of the embodiment according to the present invention, when one element is described as being formed on the "on or under" of another element, the above (up) or down ( (On or under) includes both the two elements are in direct contact with each other (directly) or one or more other elements are formed indirectly formed (indirectly) between the two elements. In addition, when expressed as “on” or “under”, it may include the meaning of the downward direction as well as the upward direction based on one element.

1 is a schematic view of a lighting apparatus according to an embodiment. Referring to FIG. 1, a lighting apparatus according to an embodiment may include a radiator 110, a light source unit 130, a reflector 150, an optical excitation plate 170, and a first pulse width modulation (PWM) controller 200. The second PWM controller 300 may include a first controller 400 and a second controller 500.

The radiator 110 may receive heat from the light source unit 130 and emit the heat. The heat sink 110 has one surface on which the light source unit 130 is disposed. Here, the surface on which the light source unit 130 is disposed may be a flat surface or may be a surface having a predetermined curvature.

In addition, the heat sink 110 may have a heat radiation fin 115. The heat dissipation fins 115 may protrude or extend outward from one side of the heat dissipation unit 110. The heat radiation fins 115 widen the heat radiation area of the heat sink 110. Therefore, the heat dissipation efficiency may be improved by the heat dissipation fin 115.

In addition, the radiator 110 may be formed of a metal material or a resin material having excellent heat dissipation efficiency, but is not limited thereto. For example, the material of the heat sink 110 may include at least one of aluminum (Al), nickel (Ni), copper (Cu), silver (Ag), and tin (Sn).

The light source unit 130 is disposed on the heat sink 110, and emits a predetermined light onto the heat sink 110. The light source unit 130 may include a substrate 131 and a light emitting element 133.

The substrate 131 may be any one of a general PCB, a metal core PCB (MCPCB), a standard FR-4 PCB, or a flexible PCB. The substrate 131 may directly contact the heat sink 110. The substrate 131 may be disposed on one surface of the heat sink 110.

In addition, one or more light emitting elements 133 are disposed on the substrate 131. In order to easily reflect light from the light emitting device 133 on the substrate 131, a light reflecting material may be coated or deposited.

The substrate 131 may optionally have a heat dissipation tape or a heat dissipation pad or the like for structural purposes or to improve heat transfer to the heat dissipator 110.

The light emitting devices 133 may be disposed on the substrate 131. The plurality of light emitting devices 133 may emit light of the same wavelength and may emit light of different wavelengths. In addition, the plurality of light emitting devices 133 may emit light of the same color and may emit light of different colors.

The light emitting device 133 may be any one of a blue light emitting device emitting blue light, a green light emitting device emitting green light, a red light emitting device emitting red light, and a white light emitting device emitting white light.

The light emitting device 133 may include a light emitting diode (LED) chip. The LED chip may be any one of a blue LED chip emitting blue light in the visible light spectrum, a green LED chip emitting green light, and a red LED chip emitting red light. Here, the blue LED chip has the main wavelength in the range of about 430nm to 480nm, the green LED chip has the main wavelength in the range of about 510nm to 535nm, and the red LED chip has the main wavelength in the range of about 600nm to 630nm.

In addition, the light emitting device 133 may further include a phosphor. The phosphor may be mixed with a resin which is a solvent to cover the LED chip. The phosphor may be any one or more of yellow phosphors, green phosphors and red phosphors.

The yellow phosphor may emit yellow light having a main wavelength in the range of 540 nm to 585 nm in response to blue light (430 nm to 480 nm) from the blue LED chip. The green phosphor may emit green light having a main wavelength in the range of 510 nm to 535 nm in response to blue light (430 nm to 480 nm). The red phosphor may emit red light having a main wavelength in a range of 600 nm to 650 nm in response to blue light (430 nm to 480 nm).

The yellow phosphor may be a silicate-based, garnet-based yag, or oxynitride-based phosphor. The yellow phosphor may emit light having a main wavelength in the range of 555 nm to 585 nm in response to blue light. In addition, the yellow phosphor may be selected from phosphors selected from Y3Al5O12: Ce3 + (Ce: YAG), CaAlSiN3: Ce3 +, Eu2 + -SiAlON series, and / or BOSE series. In addition, the yellow phosphor may be doped to any suitable level to provide light output of the desired wavelength. Ce and / or Eu may be doped into the phosphor at a dopant concentration ranging from about 0.1% to about 20%. Suitable phosphors include products of Mitsubishi Chemical Company (Tokyo, Japan), Leuchtstoffwerk Breitungen GmbH (Breitungen, Germany) and Intermatix Company (Frefornia, California).

The green phosphor may be a silicate-based, nitride-based, or oxynitride-based phosphor. The green phosphor may emit light having a main wavelength in the range of 510 nm to 535 nm in response to blue light.

The red phosphor may be a nitride or sulfide phosphor. The red phosphor may emit light having a main wavelength in the range of 600 nm to 650 nm in response to blue light. Red phosphors may include CaAlSiN 3: Eu 2+ and Sr 2 Si 5 N 8: Eu 2+. This phosphor can maintain the quantum efficiency at 80% or more at a temperature of 150 캜 or more. Other red phosphors that may be used include phosphors selected from CaSiN2: Ce3 +, CaSiN2: Eu2 + as well as the Eu2 + -SiAlON phosphor family, and / or phosphors selected from the (Ca, Si, Ba) SiO4: Eu2 + (BOSE) series. In particular, the CaAlSiN: Eu 2+ phosphor from Mitsubishi Chemical Company may have a dominant wavelength of about 624 nm, a peak wavelength of about 628 nm, and an FWHM of about 100 nm.

The plurality of light emitting devices 133 may include 1) a combination of blue light emitting elements and red light emitting elements, 2) a combination of blue light emitting elements, red light emitting elements and green light emitting elements, and 3) a white light emitting element. It may be.

The reflector 150 reflects the light from the light source unit 130. The reflector 150 may surround the light source unit 130, and may easily reflect light from the light source unit 130 to the outside.

In addition, the reflector 150 may have a reflecting surface that reflects light from the light source unit 130. The reflective surface may be substantially perpendicular to the substrate 131, and may be obtuse with the upper surface of the substrate 131. The reflective surface may be coated or deposited with a material that can easily reflect light.

In addition, the mixing space 160 may be formed by the reflector 150 and the heat sink 110. The mixing space 160 refers to a space in which light emitted from the light source unit 130 or emitted from the light source unit 130 and reflected by the reflector 150 is mixed.

In an exemplary embodiment, the light emitting device 133 includes a first white light emitting device, a second white light emitting device, a third white light emitting device, and a fourth white light emitting device. The first to fourth white light emitting devices are arranged in a linear array in order of the first white light emitting device, the second white light emitting device, the third white light emitting device, and the fourth white light emitting device. The color temperature of the first and third white light emitting devices is higher than that of the second and fourth white light emitting devices. That is, the first and third white light emitting devices are cool white light emitting devices, and the second and fourth white light emitting devices are warm white light emitting devices. The current applied to the first and second white light emitting devices so that the x and y coordinates due to the mixing of the light emitted from the first to fourth white light emitting devices can move on the black body radiation curve in the region on the 1931 CIE chromaticity diagram. Are pulse width modulated by the first PWM controller 200 and the second PWM controller 300, respectively, and the current is applied to the third and fourth white light emitting devices having a difference in color temperature from the first and second white light emitting devices. Are respectively controlled by the first controller 400 and the second controller 500.

As such, the first to fourth white light emitting devices emit light by pulse width modulation of the first PWM controller 200 and the second controller 300 and control of the first controller 400 and the second controller 500. The x, y coordinates in the area on the 1931 CIE chromaticity diagram by the mixing of the light can be moved on the blackbody radiation curve in the area on the 1931 CIE chromaticity diagram.

In addition, since the first PWM controller 200 and the second PWM controller 300 generate instantaneous high pulses compared to the first controller 100 and the second controller 200, a failure often occurs. At this time, even if a failure occurs in any of the first PWM controller 200 or the second PWM controller 300 by the first controller 100 and the second controller 200 which is a general controller cool white light emitting device and warm white light emission It is possible to control the current applied to the device.

2 is a graph illustrating a magnitude of current by pulse width modulation, and FIG. 3 is a graph showing a change in color coordinates by pulse width modulation of FIG. 2.

Referring to Figure 2, it can be seen that the change in the magnitude of the current applied to the white light emitting device over time. Here, the duty cycle is e-a (t).

The magnitude of the current applied to the first and third white light emitting devices may be changed by pulse width modulation of the first PWM controller, in which the area representing the magnitude of the current at turn-on time is the brightness of the white light emitting device. Corresponds to Similarly, the magnitude of the current applied to the second to fourth white light emitting devices may be changed by pulse width modulation of the second PWM controller.

When the turn-on time is b-a, the current flowing through the white light emitting device is 2500 mA. When the turn-on time is c-b, the current flowing through the white light emitting device is 1500 mA. When the turn-on time is d-c, the current flowing through the white light emitting device is 175 mA.

At this time, the magnitude of the current flowing during the turn-on time is different in all three cases, the brightness is the same in all three cases.

2 and 3 show color coordinates when the current applied to the white light emitting device is 175 mA, 350 mA, 700 mA, 1000 mA, 1500 mA, 2000 mA, or 2500 mA. As the magnitude of the current increases, x, y It can be seen that the x and y values on the color coordinates become small.

That is, when the pulse width of the current applied to the white light emitting device is modulated to be small, the magnitude of the current flowing through the white light emitting device increases, so that the x and y color coordinates of the light emitted from the white light emitting device are located below the left side.

4 is a view for explaining a lighting control method on a black body radiation curve according to an embodiment. Here, the control by the first and second PWM controllers is the pulse width modulation control of the current, and the control by the first and second controllers is the general current control.

Referring to FIG. 4, A and B represent two end points of a section in which x, y color coordinates of light emitted by controlling a current applied to a cold white light emitting device (or controlled by pulse width modulation) may move. B ′ represents two end points of a section in which x and y color coordinates of light emitted by controlling a current applied to a warm white light emitting device (or controlled by pulse width modulation) may move. In addition, x, y color coordinates of the light emitted by the pulse width modulation of the light emitted by the pulse width modulated current applied to the cold white light emitting device can be moved, the x, y color coordinates of the light emitted by the pulse width modulated current It is located below the left side of the moving section.

The first PWM controller pulse-modulates the current applied to the first white light emitting device, and the second PWM controller pulse-modulates the current applied to the second white light emitting device. Cool white light emitting devices by the pulse width modulation of the first PWM controller has x, y color coordinates on a straight line connecting A, B, warm white light emitting devices by the pulse width modulation of the second PWM controller is A ', B' It has x and y color coordinates on the straight line.

In addition, the first controller controls the current applied to the third white light emitting device, and the second controller controls the current applied to the fourth white light emitting device. Under the control of the third controller, the cool white light emitting device has x, y color coordinates on a straight line connecting A and B, and under the control of the fourth controller, the warm white light emitting device has a x, y on a straight line connecting A ', B'. It has color coordinates.

In this case, x and y color coordinates due to mixing of the light emitted from the first to fourth white light emitting devices may exist on four sections. That is, 1) a section indicated by a straight line connecting A and A ', 2) a section indicated by a straight line connecting A and B', 3) a section indicated by a straight line connecting B and A ', and 4) a straight line connecting B and B'. This is the section that represents.

From this principle, the pulse width modulated current applied to at least one light emitting device among the first and second white light emitting devices, and the current applied to at least one light emitting device among the third and fourth white light emitting devices is controlled. The x and y coordinates due to the mixing of the light emitted from the first to fourth white light emitting devices may be moved on the blackbody radiation curve in the region on the 1931 CIE chromaticity diagram.

5 is a diagram illustrating a principle of having color coordinates on a black body radiation curve according to an embodiment. 5, the lighting control method according to an embodiment is as follows.

First, an area on a 1931 CIE chromaticity diagram by applying first and second set currents to the first and second white light emitting elements disposed on the substrate, respectively, by mixing light emitted from the first and second white light emitting elements. Get the x, y coordinates inside. At this time, x, y coordinates in the region on the 1931 CIE chromaticity diagram by mixing light emitted from the first and second white light emitting devices are present in a section indicated by a straight line connecting A and A ', for example, P ₁ . .

Thereafter, the third and fourth set currents are applied to the third and fourth white light emitting elements having a difference in color temperature from the first and second white light emitting elements disposed on the substrate, thereby providing the first to fourth portions. The x, y coordinates in the area on the 1931 CIE chromaticity diagram are obtained by mixing the light emitted from the white light emitting device. At this time, x, y coordinates in the region on the 1931 CIE chromaticity diagram due to the mixing of the light emitted from the third and fourth white light emitting devices are present in a section indicated by a straight line connecting B and B ′, for example, P ₂ . The new coordinates are obtained by mixing with the x, y coordinates in the area on the 1931 CIE chromaticity diagram by mixing the light emitted from the first and second white light emitting devices obtained earlier. In this case, the new coordinate is more likely to be a point on the black body radiation curve such as P ₃ .

Subsequently, the pulse width modulated current applied to at least one light emitting device of the first and second white light emitting devices and the current applied to at least one light emitting device of the third and fourth white light emitting devices are controlled, The x and y coordinates due to the mixing of the light emitted from the first to fourth white light emitting elements are moved on the blackbody radiation curve in the region on the 1931 CIE chromaticity diagram. Because point on the previously obtained first through the 4, 1931 CIE chromaticity region in the x on the diagram, y coordinates of the light mixture emitted from the white light emitting device is the black body radiation curve such as P _3, and P ₃ through the control of the current Move to a point on the same blackbody radiation curve. At this time, the current applied to the first to fourth white light emitting devices is independently controlled, and the smaller the pulse width of the current applied to the first or second white light emitting devices, the smaller the x and y values of the x and y coordinates. Move in the direction of

The present invention is not limited by the above-described embodiment and the accompanying drawings. It is intended that the scope of the invention be defined by the appended claims, and that various forms of substitution, modification, and alteration are possible without departing from the spirit of the invention as set forth in the claims. Will be self-explanatory.

110: heat sink
115: heat dissipation
130: light source
131: substrate
133: light emitting element
150: reflector
160: mixing space
170: optical excitation plate
20O: first PWM controller
300: second PWM controller
400: first controller
500: second controller

Claims (6)

First to fourth white light emitting devices disposed on the substrate;
First and second pulse width modulation controllers for pulse width modulating currents applied to the first and second white light emitting devices, respectively; And
First and second controllers respectively controlling currents applied to the third and fourth white light emitting devices having a difference in color temperature from the first and second white light emitting devices;
Including,
X in an area on a 1931 CIE chromaticity diagram by mixing pulse width modulation of the first and second pulse width modulation controllers and light emitted from the first to fourth white light emitting elements by control of the first and second controllers. , shifting the y coordinate onto a blackbody radiation curve in the area on the 1931 CIE chromaticity diagram,
Lighting equipment. The method of claim 1,
The first to fourth white light emitting devices are arranged in a linear array in order of the first white light emitting device, the second white light emitting device, the third white light emitting device, and the fourth white light emitting device.
Lighting equipment. The method of claim 1,
The color temperature of the first and third white light emitting devices is higher than the color temperature of the second and fourth white light emitting devices,
Lighting equipment. In the region on the 1931 CIE chromaticity diagram by applying first and second set currents to the first and second white light emitting elements disposed on the substrate, respectively, by mixing light emitted from the first and second white light emitting elements. a first step of obtaining x and y coordinates;
The first and fourth white currents may be applied to the third and fourth white light emitting elements disposed on the substrate, respectively, to the third and fourth white light emitting elements having a difference in color temperature from the first and second white light emitting elements. A second step of obtaining x, y coordinates in an area on a 1931 CIE chromaticity diagram by mixing light emitted from the light emitting device; And
Pulse-width modulating a current applied to at least one light emitting device among the first and second white light emitting devices and controlling a current applied to at least one light emitting device among the third and fourth white light emitting devices, thereby A third step of moving the x and y coordinates due to the mixing of the light emitted from the fourth white light emitting device onto a blackbody radiation curve in a region on the 1931 CIE chromaticity diagram;
/ RTI >
Lighting control method. 5. The method of claim 4,
In the third step, the current applied to the first to fourth white light emitting device is controlled independently,
Lighting control method. The method of claim 5,
In the third step, as the pulse width of the current applied to the first or second white light emitting device is smaller, the x value and the y value of the x, y coordinates are moved in a smaller direction.
Lighting control method.

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